JPH0444070A - Developing unit of electrophotographic recording 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 [Field of Industrial Application] The present invention relates to an electrophotographic recording device 93 that records characters and patterns on paper based on the principles of electrophotography. especially,
Related to the improvement of the developing unit [Prior art 1] Fig. 6 shows a side view of a conventional developing unit.

As shown in the figure, a developing sleeve for supplying the developer, ie, toner, accommodated in the toner accommodating portion 104 to the image bearing member, ie, the photosensitive drum 106, has a rotatable magnetic pole.
It was formed by an ifl=II member 102 and a rotatable metal outer sleeve 101.

Then, by rotating the metal outer cylinder sleeve 101 and rotating the Gn member 102 at a speed three to five times as fast as this rotation, the particles 1 to 1 are charged and conveyed, and a certain gap d is formed between the metal sleeve and the photosensitive member. I have been developing toner while keeping it in a body drum.

[Problems to be Solved by the Invention] The conventional developer units 1 to 1 as described above have 4 to 1 ops.
Even in a relatively low-speed machine of pm, the metal sleeve can be
0 rpm to 300 rpm, the 6R member 102
It is necessary to rotate at a relatively high speed of about 0 to 200 rpm, and it has been impossible to downsize the developing device due to the complexity of the drive system due to the increase in torque and the increase in size.

In such a developing unit, it is necessary to process the outer diameter of the metal outer cylinder sleeve, polish it, and sandblast it, and it is also necessary to precisely arrange the photoreceptor drum and metal conveyance sleeve with a gap between them. This caused an increase in man-hours and costs.

In addition, printing quality deteriorated due to toner scattering and fog caused by high-speed rotation of the metal outer cylinder sleeve and magnetic member, and fluctuations in toner blue density occurred due to instability in the amount of toner charge.

In addition, there has been proposed a method of eliminating the developer conveying member and conveying the developer using m-type rollers, for example, in Japanese Patent Application Laid-Open No. 63-223675 and VSP4.
The developing device of 851.874 prevents oxidative corrosion (
In cases where image deterioration is caused by so-called rust, or when the image is developed in contact with a photoreceptor belt or photoreceptor drum, for example, when the photoreceptor material is an organic photoreceptor such as OPC, 6n materials are more effective than photoreceptor materials. Due to its high hardness, it has the problem of scratching the photoreceptor material and causing fatal defects in the image.

Therefore, the present applicant has devised a developing device unit that solves this problem by disposing an outer cylindrical sleeve made of an elastic member that can be rotated or fixed on the outer peripheral surface of a magnetic member. As the stone material of the magnetic member, ferrite]-,
Known 6f1 stone materials such as alnico, manganese aluminum, and aM 6H stone can be used. However, when a high-resistance material such as a ferrite magnet is used as the magnetic member, a developing bias voltage may be applied to the developer conveyed on the iiR material member during development, or A so-called developing electrode is installed separately to emphasize the electric field formed by the potential forming the electrostatic latent image, or a conductive member such as a core frame installed inside the magnetic member is used as the developing electrode. In the former case, the structure becomes complicated, while in the latter case, the developing electrode is located far from the latent image holder and the developer, resulting in a decrease in resolution and a problem in the effectiveness of the structure. Problems arise such as an increase in energy consumption due to the increase in the output of the power supply to compensate for the decrease in the target developing bias.

Furthermore, when a conductive material such as a rare earth magnet is used as the magnetic member, the ffl material portion can be used as a developing electrode, but oxidation corrosion occurs on the surface of the magnetic member, making it difficult to obtain high-quality images. Due to the problem that it cannot be formed stably for a long period of time, when actually using an iin member made of rare earth N1 stone, surface corrosion prevention is applied to the surface to prevent oxidation corrosion on the surface of the above-mentioned 6 magnetic members. It is necessary to provide a layer, and if the 6R member is coated with a high resistance material such as rubber as the surface corrosion prevention layer, the same method as in the case where a high resistance material such as ferrite FF1 stone is used as the magnetic member. Problems such as the complexity of the structure due to the need to install the developing electrode separately, and the decrease in resolution and increase in energy consumption due to the developing electrode being installed at a location away from the latent image holder and the developer. be.

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and its object is to provide a developing unit with a simple structure that can stably form high-quality images over a long period of time.

[Means for Solving the Problems] A developing device unit of the present invention includes a storage portion for storing a developer, an LiR member having a plurality of rotatable LA poles, and a magnetic member disposed around the outer periphery of the magnetic member. In a developing unit that includes a rotatable outer sleeve of an elastic member and transports developer by rotating at least one of the magnetic member and the outer sleeve, the elastic member is coated with at least one conductive substance. It is characterized by containing.

[Function] According to the above configuration of the present invention, by providing the outer cylindrical sleeve containing at least one kind of conductive material on the outer circumferential surface of the main member, the elastic member can be rotated or fixed.
By the conductive material functioning as a developing electrode,
It becomes possible to form high-quality images stably for a long period of time.

[Example 1 Below, please refer to the drawings for an example of the present invention! +4. and explain. FIG. 1 is a diagram that does not show the structure of a developing sleeve according to the present invention. A magnetic member 2 having magnetic poles arranged on the outer periphery of the core frame 3 is disposed, and at least ]f is disposed on the outer periphery of the magnetic member 2.
! ! An outer sleeve made of an elastic material containing a conductive material such as
(hereinafter referred to as elastic outer cylinder sleeve 1) is provided. As a method of imparting conductivity to the elastic outer cylinder sleeve 1, metals such as AI2, Fe, N1, Cr, Au, Ag, and Cu or conductive materials such as carbon black may be made into fine powder and dispersed in the elastic member. , electroplating or chemical plating of the conductive material, or disposing it on the surface of the elastic member by 8-shot or the like is suitable.

FIG. 2 shows a state in which the developing sleeve is arranged in one henna storage part 4. As shown in FIG. The doctor bullet 5 was fixed so as to be in contact with the outer peripheral surface of the developing sleeve, and development was performed. A latent image was formed on the photoreceptor drum 6 by the light generating unit 1-, and when a bias voltage was applied to the core frame 3, a toner image was formed on the photoreceptor drum 6. Since the developing sleeve and the photosensitive drum 6 rotated at a constant speed, a good image without toner scattering could be obtained. In addition, since the photosensitive drum 6 and the developing sleeve are in contact with each other, the nip width at the developing position is large (because it can be removed), the development rate increases and the elastic outer cylinder sleeve l forms a latent image on the photosensitive drum 1. It was possible to improve the development density and achieve uniformity due to the development electrode effect such as the enhancement of the electric field due to the potential potential.Furthermore, due to the friction caused by the contact between the photoreceptor drum 6 and the developing sleeve, the photoreceptor drum 6 It was also confirmed that the developing sleeve rotates in accordance with the rotation of the developing sleeve, and that the gear train of the developing sleeve can be removed.

The experiment was conducted under the same conditions as the embodiment shown in FIG. 2 above, except that the rotation speed of the developing sleeve was made faster than the rotation speed of the photosensitive drum 6. As a result, an image with high -layer development density could be obtained.

Furthermore, even when the rotational speed was increased, no scratches were observed on the photosensitive drum 6 due to the effect of arranging the elastic body on the outer peripheral surface of the developing sleeve.

FIG. 3 shows a state in which the developing sleeve is separated from the photosensitive drum 6 by a gap d. In this state, when developing was performed by rotating the developing sleeve at the same speed as the photoreceptor drum 6, the developed density was lower than that shown in FIG.
An image with highly uniform toner adhesion to the latent image was obtained. In other words, the toner is uniformly charged due to the contact between the elastic member 3 and the doctor blade 5, the toner becomes a thin layer on the developing sleeve, the charging and toner conditions are stable, and the developing electrode effect is observed. This indicates that the If the developed density is low, take measures such as using highly chargeable toner or increasing the rotation speed of the developing sleeve.
There are measures such as increasing the developer density. This time, I tried increasing the rotation speed of the developing sleeve, and was able to increase the developed density. In this experiment, a loppm machine was used. The diameter of the photosensitive drum is φ30mm and the rotation speed is approximately 37rp.
m, and in the embodiment shown in FIG. 2, the developing sleeve has a diameter of φ20
mm, the rotation speed of the developing sleeve is approximately 56 rpm. In the embodiment shown in Fig. 3, the developing sleeve is 70 to 80 r.
There was a good range in pm, and the speed was lower than that of the conventional example.

Of course, the optimal area varies depending on the toner and printing speed. In both Figures 2 and 3, insulating magnetic l-component toner is used, the gap d is 02 to 0.5 mm, and the developing sleeve is The core frame is φ6mm, and the magnetic member is φ15.5mm.
, φ17.5mm, and φ18.5mm, and the elastic outer sleeve 1 has three thicknesses of 2mm, 1mm, and 0.5mm.
The diameter of the developing sleeve was set to φ20 mm. Of course, the above experimental conditions are not limited, and vary depending on the diameter of the developing sleeve and photosensitive drum 6, peripheral speed, toner physical properties, printing speed, etc. In the embodiments indicated by section numbers 3 from FIG. 1, the elastic outer cylinder sleeve 1 and the magnetic member 2 are rotated at the same speed, so when the magnetic member 2 is fixed,
An experiment was conducted in the case where the rotational speed of the magnetic member 2 was different from that of the elastic outer sleeve 1.

When the magnetic member 1 was fixed, an image almost identical to that of the above example was obtained. Further, regarding the fixed position of the magnetic member 2, as the magnetic peak was brought closer to the vicinity of the development position, an increase in the development density was observed, and as the magnetic member was moved away from the position, the resolution was improved. In other words, it has been found that the required image quality can be met by a fixed position. The la magnetic member is
When the rotation speed was different from that of the elastic outer sleeve 1, particularly when the rotation speed of the m-elastic member 2 was made higher than that of the elastic outer sleeve 1, a marked increase in print density was observed. As long as the rotation speed of the magnetic member 2 is at least 1.5 times that of the elastic outer cylinder sleeve, there will be no problem in print density, and the speed can be significantly reduced compared to the conventional example.

When the rotational speed of the IiR member 2 was the same as the rotational speed of the elastic outer cylinder sleeve 1, some unevenness occurred in printing. In addition, the methods shown in FIGS. 4 and 5 were also tried for bringing the doctor blade 5 into contact. In FIG. 4, a spring 7 is arranged behind the doctor blade 5, and the doctor blade 5 is an elastic member.
It is designed so that the load is uniform.

However, in the case of FIG. 4, there are problems such as an increase in the number of parts, so as shown in FIG. 5, a doctor blade 5 made of a material with 1 elasticity is used for contact. If managing the contact pressure between the blade 5 and the elastic member takes time and effort, measures such as those shown in FIGS. 4 and 5 are appropriate.

In this embodiment, the 8 rods 3 are made of iron, but they may be made of other metals, plastics, etc. that can be conductive, or other conductive materials such as suppressing electrodes on m-type members. If I can find the means, I especially don't mind the materials. The magnetic member 1 disposed on the outer peripheral surface of the 8 rod 3 is made of ferrite, alnico, manganese aluminum, rare earth elements with atomic numbers 58 to 71 (element symbols Ce to Lu), and among them, Nd.
, at least one of the rare earth elements represented by Pr and Sm
In addition, it is possible to use rare earth linstone to which at least one of 3D transition metals represented by Fe, Ni, and Co is added.

In addition, the elastic outer sleeve 1 disposed on the outer circumferential surface of the magnetic material tl' is designed to control the contact area (so-called nip) between the photoreceptor drum 6 and the elastic member 1, the contact pressure with the doctor blade 5, and the contact area between the photoreceptor drum 6 and the elastic member 1. Considering the problem of scratches caused by contact with 6, it is desirable to use a rubber material with a rating of about 90.
For example, butyl rubber, Acnol rubber, urethane rubber, silicone rubber, fluoro rubber, polysulfide rubber, ethylene-brobylene rubber, Hypalon, ethylene-vinyl acetate rubber, chlorinated polyethylene, Alfine rubber, polyester rubber, Ebichlor rubber, natural rubber, Isoprene rubber, styrene rubber, nitrile rubber, butadiene rubber, chloropsin rubber, etc. are suitable. In addition, the elastic outer cylinder sleeve 1 is
When considering toner conveyance, it does not matter if the arrangement is such that a magnetic flux density of 2000 AUSS or more can be obtained on the surface of the elastic outer sleeve.

30″G, 60%RH in the embodiments shown in Figures 2 and 3
When images corresponding to t0000 sheets were continuously formed under the following environment, the resulting images were high-quality, high-resolution, high-density images similar to the first printed sheet. For comparison, a
1. Image formation was performed using the same structure as shown in FIGS. 2 and 3 except that the magnetic material and the elastic outer cylinder sleeve 1 on the outer periphery were not provided (comparative experiment 2). In the configuration shown in FIG. 2, the photoreceptor drum 6 is immediately scratched, causing a fatal defect in the image, and in the configuration shown in FIG. When the toner was removed and the top of the magnetic member 2 was observed, the occurrence of rust was confirmed, and the effect of providing the elastic outer sleeve 1 was confirmed. In addition, an experiment (comparative experiment ■) similar to the above comparative experiment ■ was conducted except that the elastic outer cylinder sleeve 1 was eliminated and the magnetic member 2 contained an elastic material such as rubber (comparative experiment ■), but the results were the same as above. If the contact occurs, the photoreceptor drum 6 will be damaged immediately, resulting in
After printing 00 sheets, rust was observed on the magnetic member 2.

In other words, it has been found that even if an elastic material is included, a problem occurs because a magnetic material, which is a metal and has a higher hardness than a photosensitive material such as OPC, is exposed on the surface.

Furthermore, in the case of a developing device in which the photosensitive drum 6 and the developing sleeve contact each other to perform development, as in the embodiment shown in FIG. , which caused the problem of low-temperature soil retention. However, in this embodiment, the 1ift member 2 is arranged, and the magnetic force of the 1ift member 2 causes the 1st to return to the developing sleeve side. However, no low-temperature soil failure occurred.

[Effects of the Invention 1] The present invention is equipped with a developing sleeve in which an elastic outer cylinder sleeve is arranged on the outer circumferential surface of a magnetic material in the developing device unit, thereby reducing torque by lowering the speed, simplifying the mechanism, improving density, and printing quality. This makes it possible to provide a high-quality, compact developing device.

[Brief explanation of the drawing]

Figure 1! "Front 1υi curve diagram of the present invention. FIGS. 2 to 5 are cross-sectional views of a developing sleeve disposed in a developing device unit. FIG. 6 is a cross-sectional view showing a conventional developing unit. 1...Elastic outer cylinder sleeve 2...Magnetic member 3, 4, 5, 6, 7, ] 06, 8 rods, 1-ner housing section, doctor press photoreceptor drum, wafer, metal outer cylinder slide magnetism Part photoreceptor drum Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kisanbe Suzuki (and 1 other person)

Claims (1)

[Claims] The magnetic member and the outer cylinder are provided with an accommodating portion for accommodating a developer, a polar member having a plurality of rotatable magnetic poles, and an outer cylinder sleeve of a rotatable elastic member disposed around the outer periphery of the magnetic member. A developing unit for an electrophotographic recording apparatus, wherein the developing unit conveys developer by rotating at least one of the sleeves, wherein the elastic member includes at least one conductive material.