JPS644172B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device that applies toner to an electrostatic latent image formed on a photoreceptor of an electronic copying machine and develops the image.

2. Description of the Related Art It is known that a developing device for an electronic copying machine uses a fur brush roller as a means for attaching toner to an electrostatic latent image formed on a photoreceptor. A brush roller for supplying toner is provided so as to rub against the fur brush roller, and is configured to supply toner to the fur brush roller and to frictionally charge the toner.

However, it is impossible to charge the supplied toner uniformly by simply rubbing the fur brush roller and the brush roller as a means of charging the toner, and the toner that adheres to the photoreceptor becomes uneven. This has the disadvantage of causing uneven development.

This invention was made in view of the above-mentioned circumstances, and its purpose is to provide a developing device that can uniformize toner charging and prevent uneven development by applying frictional charging and electrical charging to toner. This is what we are trying to provide.

The present invention will be explained below based on an embodiment shown in the drawings. FIG. 1 shows the basic configuration of an electronic copying machine, where 1 is the main body. A document mounting table 2 is provided on the upper surface of the main body 1, and is configured to reciprocate by a drive motor 3 provided within the main body 1. A zinc oxide-resin dispersant photoreceptor 4 is pivotally supported approximately in the center of the main body 1 in the form of a drum as an image carrier that rotates synchronously with the mounting table 2 . An exposure system 7 including a lamp 5, a focusing light transmitter 6, etc. is located between the photoreceptor 4 and the original table 2.
is provided to irradiate the document placed on the document table 2 and guide the reflected light to the photoreceptor 4 to form an image of the document. From this image forming position, in order along the rotational direction of the photoreceptor 4, a developing device 8, a transfer device 9, a cleaning device 10, and a charging device 11, which will be described later.
is installed. The developing device 8 visualizes the latent image of the document formed on the surface of the photoreceptor 4 by the exposure system 7. The transfer device 9 transfers the original toner image formed on the photoreceptor 4 onto the copy paper p, and the cleaning device 10 transfers the original toner image formed on the photoreceptor 4 to the copy paper p.
This removes toner remaining on the surface of the
Further, at the bottom of the main body 1, there is provided a paper feeding device 14 consisting of a removable cassette 12 for storing copy paper p, and a paper feed roller 13 for feeding the copy paper p. The transfer device 9 also includes a transfer roller 1.
5 and a transfer belt 17 having an insulating property such as Mylar (trade name), which is stretched between a plurality of guide rollers 16, 16. and,
This transfer belt 17 is in contact with a part of the outer circumferential surface of the photoreceptor 4, and this transfer belt 17
7, a transfer charging device 18 having basically the same structure as the charging device 11 and a cleaning blade 19 are in contact with each other. Further, a fixing device 20 and a delivery roller 21 are provided on the delivery end side of the transfer belt 17, and the copy paper p onto which the image has been transferred by the transfer device 9 is fixed, and then delivered to the tray 22. ing. Note that 23 is a control device.

Next, the developing device 8 will be explained based on FIG. 2. 24 is a casing, and inside this casing 24 is a toner supply chamber 25 that accommodates toner.
and a roller chamber 26 are provided. An opening 27 facing the outer peripheral surface of the photoreceptor 4 is provided at the front of the roller chamber 26 . Inside the roller chamber 26 facing this opening 27 is a fur brush roller 28 for development, which will be described later, and a brush roller 2 behind it.
9 is provided. The developing fur brush roller 28 and the brush roller 29 are each connected to a drive source and are configured to rotate in the direction of the arrow.

Further, the developing fur brush roller 28 is constructed as shown in FIG. That is, 3
0 is a rotating shaft made of aluminum material as a metal core, and the outer peripheral surface of this rotating shaft 30 is coated with foamed polyurethane such as EMM polyurethane (product name: MTP).
A flexible cylindrical core 32 of the developing fur brush roller 28 is provided. In addition, EMM polyurethane 31 has a hardness
23±5Kg (displayed according to JIS standard K-6401 test method),
Uses rebound resilience of 45%. And this
A conductive adhesive 33 is continuously applied to the outer peripheral surface and end surface of the EMM polyurethane 31 to form a seamless conductive adhesive layer 34 on the EMM polyurethane 31. That is, the rotating shaft 30 and the conductive adhesive layer 34 are electrically connected so that a bias potential is applied thereto. As the conductive adhesive 33, 25% by weight of styrene-butadiene rubber, such as Tuffprene (product name: Asahi Kasei Co., Ltd.), 50% by weight of xylene resin, and 25% by weight of carbon XC-72 (product name: Kyabot, Tokyo Materials) are used. The material used was diluted with toluene and kneaded in a ball mill for about 2 hours. Note that, as a characteristic of the conductive adhesive 33, the rubber agent shrinks as toluene evaporates, but by controlling the coating thickness, the amount of shrinkage can be suppressed to a level that poses no problem in practice.

A soft type developing fur brush roller 28 is constructed by planting surface bristles 35 on the outside of the conductive adhesive layer 34 on the outer peripheral surface of the core 32. This surface hair body 35...is made of abrasion-resistant special rayon (fiber length
1.5 mm, thickness 1.5 denier, electrical resistance 10 ⁸ ~ 10 ⁹ Ω・
cm).

Further, as shown in FIG. 2, the brush roller 29 is provided with a conductive adhesive layer 37 of the same quality as the conductive adhesive layer 34 of the developing fur brush roller 29 on the outer peripheral surface of a cylindrical body 36 made of an aluminum material. The surface hair body 38 made of seamless Teflon fiber...
... is provided, a hard type brush roller 29
It consists of

The developing fur brush roller 28 is
It is connected to a DC200V power supply 39 and a bias potential is applied to the brush roller 29.
is grounded.

Further, a charger 4 for charging the toner is provided in the casing 24 facing the brush roller 29.
0 is set.

This charger 40 has an electrode 41 as shown in FIG.
and a cloth 42 as a contact that is superposed on the electrode 41. Then, the electrode 4
1 is carbon as a stock solution (Kyabon VULCAN)
×C72) 30% by weight, SBR (Asahi Kasei Toughprene)
Solid content mixed with 50% by weight and 20% by weight of xylene resin (Nicanol, Mitsubishi Gas Chemical Co., Ltd.) and a solvent.
Mix at a ratio of 1.75%:82.5%, and mix this first liquid with the above SBR 50% and a second liquid containing 50% of a solvent such as toluene.
It is made of a sheet-like conductive rubber with a thickness of about 50 μm, which is mixed with a liquid at a ratio of 1:1. The resistance value of this electrode 41 is maintained lower than that of the cloth 42 (10 ⁵ to ⁷ Ω·cm). Further, the cloth 42 is made of velveteen. This velveteen is formed by flocking nylon hair 44 to a cotton fiber base 43, and the thickness of this hair 44 is 4.5 to 10 mm, and the length is 0.5 to 3 mm, but for example, it is set to 5 mm and 2 mm. has been done.
The resistance value of this cloth 42 is 10 ² to ^{10 10} Ωcm,
As an example, it is kept at 10 ⁸ Ωcm.

The charger 40 formed in this way is connected to the cloth 4.
The bristles 44 of No. 2 are formed in an arc shape so as to slide on the surface bristles 38 of the brush roller 29, and are connected to a DC-1000V power source 45.
A bias potential is applied.

When developing the electrostatic latent image formed on the outer circumferential surface of the photoreceptor 4 by applying toner, the developing fur brush roller 28 and the brush roller 29 are rotated in the direction of the arrow, and the developing fur brush roller 28 and brush roller 29 are A bias potential is applied to the fur brush roller 28 and charger 40. When the brush roller 29 rotates, the surface bristles 38 of the brush roller 29 and the bristles 44 of the charger 40 rub against each other, and frictional electrification occurs between them, and DC-1000V is applied from the power source 45.
Since the bias potential of is applied, the toner supplied from the toner supply chamber 25 is charged. Since the charged toner is supplied to the developing fur brush roller 28 by the brush roller 29, the toner is attached to the photoreceptor 4 by the developing fur brush roller 28 that rubs against the photoreceptor 4. Therefore, the electrostatic latent image formed on the outer peripheral surface of the photoreceptor 4 is developed.

As explained above, in this invention, a charger having a flexible contact is rubbed against the brush roller that supplies toner to the developing fur brush roller.
The toner can be charged by electrical charging in addition to frictional charging. Therefore, toner charging can be made uniform, and a highly reliable developing device without uneven development can be provided.

[Brief explanation of drawings]

The drawings show one embodiment of the invention.
The figure is a schematic configuration diagram of an electronic copying machine, FIG. 2 is a sectional view of a developing device, FIG. 3 is a partially enlarged sectional view of a developing fur brush roller, and FIG. 4 is a sectional view of a charger. . 4... Photoreceptor (image carrier), 28... Fur brush roller for development, 29... Brush roller, 40
... Charger, 41 ... Electrode, 42 ... Cloth (contact).

Claims (1)

[Claims] 1. In an apparatus that attaches toner to an electrostatic latent image formed on an image carrier and develops it, a developing fur brush roller that rubs against the image carrier, and a brush that supplies toner to the developing fur brush roller. 1. A developing device comprising a roller and a charger that contacts the brush roller and charges toner, and the charger is provided with a power supply means for supplying power to a flexible contact.