JPH0279877A - developing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention includes a developer carrier that supplies a developer to an electrostatic latent image formed on the latent image carrier to perform development. It relates to a developing device.

[Prior Art] Generally, in various image forming apparatuses such as copying machines, an electrostatic latent image corresponding to an image is formed on a latent image carrier such as a photoreceptor, and a developing device is applied to this electrostatic latent image. The developer (hereinafter referred to as toner) is removed from the developer carrier provided inside.
is supplied and development is performed, whereby a visible image is obtained.

The above-mentioned developer carrier is formed in the shape of a roller or the like that is rotated and transferred at a constant circumferential speed. A developer replenishment member formed by the developer replenishment member is attached in contact with the developer replenishment area. Further, in the developer UM region formed downstream of the developer replenishment region, a developer thinning regulating member formed in the shape of a blade or roller is attached in a contact state 6 and the developer is developed. In the developer replenishment area, the new toner stored in the toner storage ridge is replenished to the developer carrier side by the action of the developer replenisher, thereby causing the toner to adhere to the surface of the developer carrier. The toner deposited on the surface of the developer carrier is uniformly thinned in the developer thinning region by the action of the thinning regulating member. This uniformly thinned developer is sent to a development area formed downstream of the developer thinning area, where the developer is selectively supplied to the electrostatic latent image and a developing operation is performed. It looks like this.

[Problems to be Solved by the Invention] However, due to the recent demand for higher image quality, fine particle toner having a volume average particle diameter of 10 μm or less may be used.

When such fine particle toner is used in the above-mentioned general developing device, especially in a high humidity environment, the powder properties such as toner fluidity are deteriorated, causing problems in the developer replenishment area. There is a problem in that toner replenishment performance is reduced. In addition, in order to prevent toner filming on the developer carrier, materials that have low surface energy on the surface of the developer carrier, such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene, etc. Ethylene (TFE), Telorafluoroethylene-hexafluoropropylene copolymer (FED), Polychlorotrifluoroethylene (C
Even when using fluoropolymer materials such as TFE) or materials containing these fluoropolymer materials, or materials with high toner releasability such as polyethylene, polypropylene, and silicone resin, the A similar problem arises in that toner replenishment performance is reduced. Furthermore, there is a developing device in which a toner collection member is placed in contact with the developer carrier to remove residual toner on the developer carrier after development, but in this case as well, toner replenishment to the developer carrier is difficult. There is a risk that it will be lowered.

Therefore, the present invention can be used under various conditions in which the ability to replenish toner to the developer carrier is reduced, such as when fine particle toner is used, when a high-resistance developer carrier is used, or when a toner collection member is provided. An object of the present invention is to provide a developing device that can replenish toner well and maintain image quality highly and stably over a long period of time.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a developer carrier that is transported at a constant speed, and a developer carrier that is moved at a constant speed while being placed in contact with the developer carrier in a developer supply area. The developer supplying member is provided with a developer replenishing member that is transported, and the developer is supplied and deposited on the developer carrier side through the developer replenishing member, and the developer deposited on the developer carrier is transferred to the developer. In a developing device in which developer is fed into a developing area formed downstream of a replenishing area to supply developer to an electrostatic latent image to perform development, the transport speed of the developer replenishing member is set to It has a configuration that is set to exceed the transfer speed of .

[Function] In the means having such a configuration, the toner present in the developer supply area where the developer supply member and the developer carrier are arranged in contact with each other is transferred to the developer transported at a higher speed. The toner is moved following the replenishing member, and the toner is well fed into the pinched area between the developer replenishing member and the developer carrier, and toner replenishment performance is maintained well. ing.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows a developing device 1 using a one-component non-magnetic developer (toner). This developing device 1 is attached near a photosensitive drum 2 as a latent image carrier. The photoreceptor drum 2 is formed from an organic photoreceptor (OPC) or the like.

A developing roller 4 serving as a developer carrier is pivotally supported within the developing unit 3 of the developing device 1, and this developing roller 4 is arranged so as to elastically contact the surface of the photosensitive drum 2 in the developing area. has been done. The photosensitive drum 2 and the developing roller 4 are rotated in opposite directions indicated by arrows A and B, that is, in the same direction at the contact area between the two, and the contact area between the two has a developing area where a developing operation is performed. It is formed as described above.

The developing roller 4 is made of an elastic material that bends according to external pressure, such as silicone rubber or acrylonitrile butadiene rubber having a hardness of 15° to 50' JISA.
It is formed into a roller shape with a diameter of
A substance having low surface energy such as a fluorine-based polymer material is deposited on the surface as necessary to improve toner filming resistance. Furthermore, this developing roller 4
Development characteristics In order to ensure development characteristics that faithfully reproduce half-tone images and low-contrast images, it is made of an insulating material with a volume resistivity of about 1011 to 1012 Ω, and a speed of 300 rpm. It is rotated and transferred.

The developing unit 3 is provided with a toner hopper 5 as a toner storage section, and also serves as a developer replenishing member for replenishing the surface of the developing roller 4 with new toner stored in the toner hopper 5. A toner supply roller 6, a toner layer regulation roller 7 as a thinning regulation member that thins the toner supplied and adhered to the surface of the developing roller 4, while stirring the toner stored in the toner hopper 5. An agitator 8 that conveys the toner to the toner supply roller 6 side is connected to the developing unit 3.
It is pivotally supported within the shaft so as to be rotationally driven in the directions indicated by arrows C, D, and E, respectively.

The toner replenishing roller 6 and the toner layer regulating roller 7 are arranged so as to be in contact with the surface of the developing roller 4, and the toner replenishing roller 6 and the toner layer regulating roller 7 are arranged from the upstream side in the rotational direction of the developing roller 4. They are arranged in sequence at predetermined intervals. A developer supply area and a developer thinning area are respectively formed at the contact portions of the toner supply roller 6 and the toner layer regulating roller 7 with the developing roller 4.

The toner supply roller 6 has a diameter of 20 mm and has a surface stone made of an elastic material such as polyurethane foam.
It is formed from one piece of sponge roller with a diameter of 900 mm.
It is rotated and transferred at a speed of rpm. Therefore, the peripheral speed ratio of the 1-toner replenishing roller 6 to the developing roller 4 is set to 2.0. This toner supply roller 6
As described above, the function is to replenish the surface of the developing roller 4 with new toner stored in the toner hopper 5, and to scrape off undeveloped developer remaining on the surface of the developing roller 4 after development. It is equipped with functions.

The toner layer regulating roller 7 is formed from a hard roller member, and its material is a metal material or a hard resin material. The rotational circumferential speed of the toner layer regulating roller 7 is set to be less than 1 relative to the rotational circumferential speed of the developing roller 4. Furthermore, this toner layer regulating roller 7 comes into contact with the developing roller 4.
They are installed so that they can reciprocate in the direction perpendicular to the axis so that they are spaced apart. As a result, the toner layer regulating roller 7 is lifted from the surface of the developing roller 4 by the thickness of the toner layer, and the contact pressure against the developing roller 4 is maintained substantially constant. Further, the tip edge of a toner scraping blade 9 is pressed onto the surface of the toner layer regulating roller 7, and the sliding force of the toner scraping blade 9 causes the toner to adhere to the surface of the toner layer regulating roller 7. Toner is effectively scraped off and cleaned.

In the developing device 1 in this embodiment, exposure writing is first performed on the surface of the photoreceptor drum 2, which is charged in a negative manner, to form an electrostatic latent image corresponding to an image. Toner is selectively supplied to this electrostatic latent image in the development area from the developing roller 4 of the developing device 1, whereby the electrostatic latent image is developed and a visible image is obtained. There is. The developing roller 4 is supplied with a toner hopper 5 by the toner replenishing roller 6 in the developer replenishing area.
At the same time, the toner adhered to the surface of the developing roller 4 is uniformly made into a thin layer by the toner layer regulating roller 7 in the developer thinning area and sent to the developing area. - In this case, the toner existing in the developer replenishment area where the toner replenishment roller 6 and the developing roller 4 are arranged in contact with each other is moved to follow the toner replenishment roller 6 side which is being transported at a higher speed. As a result, the toner in the developer replenishing area is smoothly fed into the nip area between the toner replenishing roller 6 and the developing roller 4 due to the following movement of the toner replenishing roller 6 . As a result, toner replenishment performance is maintained satisfactorily. The toner fed into the nip area between the toner replenishing roller 6 and the developing roller 4 is attached to the surface of the developing roller 4 while being frictionally charged by the sliding force between the toner replenishing roller 6 and the developing roller 4 .

At this time, the peripheral speed ratio of the toner replenishing roller 6 to the developing roller 4 is desirably set to 1.5 or more in order to maintain good toner replenishment performance.
．． When setting it to less than 0, for example 0.5,
Toner replenishment becomes insufficient, resulting in a decrease in image density and white spots may also occur. On the other hand, if the circumferential speed ratio is excessively increased, it will have negative effects such as toner scattering and vibration, so it is necessary to keep it within an appropriate range.

Further, undeveloped toner remaining on the surface of the developing roller 4 after the above-mentioned development is scraped off from the developing roller 4 side by the rotational sliding force of the toner replenishing roller 6, whereby the developing roller 4 is initialized and the toner remains on the surface of the developing roller 4. A replenishment operation is now to be performed.

In the embodiment shown in FIG. 2, a brush roller including a large number of fur brushes is used as the toner supply roller 16. Further, in the embodiment shown in FIG. 3, a bias voltage for toner replenishment is applied to the toner replenishment roller 26 from the voltage application circuit 20, thereby further improving toner replenishment performance. ing. Furthermore, in the embodiment shown in FIG. 4, a toner collecting roller 30 is provided in the area of the developing roller 4 after development to scrape off the toner remaining on the developing roller 4. The developing roller 4 is cleaned and initialized by the sliding force of the toner collecting roller 30, and then sent to the toner supply area. Even when such a toner collection roller 30 is installed, there is a risk that the toner replenishment performance will be lowered, but by applying the present invention, it is possible to maintain the toner replenishment performance well even in this case.

Note that the rotational direction of the toner replenishment roller in each of the above embodiments can also be set to be opposite to the respective rotational directions.

In the developing roller 44 shown in FIG. 5, an elastic layer 44b of a constant thickness is attached around a core metal 44a forming a support shaft, and the outer peripheral surface of this elastic layer 44b has low surface energy. A toner-resistant film layer 44c of a substance is applied. Even when such a developing roller 44 is used, according to the present invention, good toner replenishment performance is ensured.

Furthermore, in the case of using a fine particle toner, for example, a toner with a volume average particle diameter of 10 μm or less, to improve image quality, the present invention can be used even in a situation where the fluidity of the toner is significantly deteriorated, especially in a high humidity environment. Toner replenishment performance is ensured.

[Effects of the Invention] As described above, in the present invention, the transport speed of the developer replenishing member is adjusted so that the toner existing in the developer replenishing area is moved toward the developer replenishing member. Since the structure is set to exceed the transport speed of the developer carrier, it is difficult to carry the developer when using fine particle toner, when using a high-resistance developer carrier, or when providing a toner collection member. Even under various conditions in which the ability to replenish toner to the body is reduced, toner replenishment can be performed satisfactorily, and image quality can be maintained highly and stably over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is an explanatory longitudinal cross-sectional view showing the entire developing device using one-component non-magnetic toner in one embodiment of the present invention, and FIG.
3 and 4 are longitudinal cross-sectional explanatory views showing a developing device in other embodiments of the present invention, and FIG. 5 is a partial cross-sectional view showing a modified example of the developer carrier. 1... Developing device, 2... Photosensitive drum, 4, 44.
...Developing roller, 6.16, 26.36... Toner supply roller.

Claims (1)

[Claims] The developer replenishing member comprises a developer carrier that is transported at a constant speed, and a developer replenishment member that is transported at a constant speed while being placed in contact with the developer carrier in a developer replenishment area. The developer is replenished and deposited on the developer carrier side through the developer carrier, and the developer deposited on the developer carrier is sent to the development area formed downstream of the developer replenishment area to form an electrostatic latent material. A developing device configured to supply developer to an image to perform development, characterized in that a transport speed of the developer replenishing member is set to exceed a transport speed of the developer carrier. Device.