JPS6161185A - Ppc type developing device - Google Patents

Abstract

PURPOSE:To obtain an image of good quality, which is free from a fog phenomenon caused by scattering of a toner by providing a nonmagnetic cylindrical sleeve on the periphery of a permanent magnet axis so as to be freely rotatable, and providing a permanent magnet layer brought to multipole magnetization, on the outside periph eral surface or the inside peripheral surface of this cylindrical sleeve. CONSTITUTION:On the periphery of a permanent magnet axis 12, a nonmagnetic cylindrical sleeve 10 is provided so as to be freely rotatable. Also, a permanent magnet layer 11 brought to multipole magnetization is provided on the outside peripheral surface or the inside peripheral surface of this cylindrical sleeve 10. Also, in this case, a magnetic pole width W of said permanent magnet layer 11 is set to 1mm-7.5mm, and when the number of magnetic poles of the permanent magnet layer 11, a revolving speed of the permanent magnet layer 11, and a moving speed of a latent image on a photosensitive drum are denoted as P, N (rps), and S (mm/sec), respectively, if a distance R between transfer same magnetic pole centers shown by R=2S (P, N) (mm) is set to 0.4mm-3.0mm, and a ratio Cr to a peripheral speed of the permanent magnet layer of the moving speed S of the latent image is set to 0.2-0.4, a fog phenomenon by scattering of a toner does not occur, and an image of good quality is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of industrial application) The present invention relates to an apparatus for PPC used in electrostatic copying machines, and particularly relates to a device for transferring magnetic 11J'8 and toner. Mixed present (two precepts using cross-agent M i'P('
Type I current T: Regarding equipment.

(Conventional Branch Technique) Figure 9 shows the configuration of this type of conventional PPC model (94 device). 7.Leave 1 or 1 time
A permanent magnet shaft 2 is fixed concentrically within the cylindrical sleeve 1 to constitute a P r'C developing device. Permanent magnets f4 forming magnetic poles N, S, N, S, N, and a cap are fixed to two permanent magnet shafts, for example, irregularly shaped shafts 71 and 3. Further, in the developer container 5, there is provided a developer in which toner and magnetic carrier are mixed in a predetermined weight. The outer periphery of the sleeve 1 is subjected to groove processing or roughening. This is to provide a frictional force between the outer peripheral surface of the sleeve and the magnetic carrier. Here, the function of the carrier is to disperse the toner into individual particles and to generate an electrostatic charge having a polarity opposite to that of the latent image, which is sufficient for development. 1. The non-magnetic cylindrical sleeve 1 and the permanent magnet shaft 2 are arranged close to the photosensitive drum 6 of the electrostatic copying machine. Note that 8 is a regulating plate for regulating the amount of developer that adheres to the outer periphery of the sleeve 1.

Note that instead of the permanent magnet shaft 2, a cylindrical magnetic roller having magnetic poles on the outer peripheral surface is also used.

In the configuration shown in FIG. 9, the magnetic carrier moves with rotation due to the action of the magnetic carrier, is regulated to 19 mm suitable for development during the movement, and is transported to the contact area with the photoreceptor drum 6 (developing section). Due to the action of the developing magnetic pole N1, the elongated brush shape extends along the magnetic line of force 1 and rubs the surface of the photoreceptor drum. At this time, due to the potential difference generated between the photosensitive drum 6 and the sleeve 1, the toner is electrostatically attracted to the surface of the photosensitive drum 6 (11) and is developed.

(Problems to be Solved by the Invention) By the way, if it is 41V71M such as No. 9r''/1, then the number of permanent magnets 4 to constitute the permanent magnet shaft 2 will be 4 to 5 or more. In addition, it is necessary to use anisotropic permanent magnets to provide strong magnetic poles, and the shape of the irregularly shaped shaft 713 is also complex, resulting in high cost and weight. There is a drawback 1
8. 1. Filling the outer peripheral surface of the sleeve 1. Or, uneven processing is required. Furthermore, in the case of using a developer containing a mixture of toner and carrier, several mechanisms are required to stir the two-thirds.

In addition, a magnetic toner developing device Y (with N poles and S poles arranged alternately around the circumference of a metal cylinder) was introduced in issue No. 11C580(-ri). )1.
In this case, it is necessary to rotate both the magnetizable gold 1" r circle and the magnetic sword inside it, and the number of magnetic poles of the magnetic control is also large. There was a risk of borrowing money or becoming a multiple wholesaler.

(1,000 z for solving the problem) = 31 The present invention addresses the above points, and provides a non-magnetic cylindrical sleeve rotatably around the permanent magnet shaft, and the outer circumferential surface of the cylindrical sleeve or By providing a multi-polar magnetized permanent magnetic 7T layer on the inner peripheral surface, the magnetic carrier and toner can be uniformly transported directly by the multi-polar magnetized permanent magnet layer,
A PPC type developer that can simplify the configuration of the permanent magnet shaft inside the sleeve and reduce weight, and also simplify or omit the carrier and toner agitation function, which in turn can reduce costs. The aim is to provide equipment.

(Function) The present invention fixedly supports a permanent magnet shaft having a developing magnetic pole that always faces a photoreceptor drum, a non-magnetic cylindrical sleeve is rotatably provided around the permanent magnet shaft, and the outer periphery of the cylindrical sleeve is A multipolar magnetized permanent magnet layer is provided on the surface or inner peripheral surface,
In the structure in which the permanent magnet layer attracts and conveys a developer containing a mixture of toner and magnetic A/Yaria, the magnetic pole width W of the permanent magnet layer is set to 1. vn to 7.5+n1o, the number of magnetic poles of the permanent magnet C4 is P, the rotation speed of the permanent magnet rT JM is N (rps), and the latent image above is The moving speed is S (m + n /
'Jaku・c) Todoki, permanent A1 between the centers of the same magnetic poles of the silica layer! Taking into account how the latent a is transferred to the C surface of the photoreceptor, the transfer tj is expressed as R=2.8/(P-N)in+n): 1 between the centers of the same magnetic poles. (11th year old mouth 0, 4.
+n+o to 3.0 mm, and by setting the ratio Cr of the moving speed S of the latent image to the circumferential speed of the permanent magnet layer to 0.2 to 0.4, it is possible to prevent uneven development and decrease in magnetic force. , 1: Rukayu ζchi) increase and Y-scattering increase are prevented from rain, so that a good image can be obtained.

(Example) Hereinafter, an example of a PPC type developing device according to the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention. In this figure, a non-magnetic circular sleeve 10 is provided on the bow middle part 1,
The outer circumferential surface of the magnetized sleeve 10 is covered with a Asasuke permanent magnet mixed with magnetic particles such as gold and other small polymer particles (for example, conductive resin) and magnetized with multipole X1. A permanent magnet layer 11 is provided over the entire circumference of the sleeve by winding the sleeve 1, inserting a cylindrical composite permanent magnet, or electrostatically coating a mixture of permanent magnet powder and conductive paint in a magnetic field. In the case of a composite permanent magnet that does not have a magnetic field, a conductive coating is provided after external attachment or insertion of the permanent magnet layer 11.The permanent magnet layer 11 has N poles and S poles arranged alternately and continuously in the axial direction of the sleeve. In addition, a permanent magnet shaft 12 is fixedly arranged concentrically inside the non-magnetic cylindrical sleeve 10. Here, the permanent magnet shaft 12 has a developing N pole attached to a deformed shaft 13. A permanent magnet 14 is fixed thereto.The N pole for development is fixed in a direction facing the photoreceptor drum 6.The structure of the developer container 5, the photoreceptor drum 6, the regulating plate 8, etc. is as follows. It is similar to FIG.

FIG. 2 shows the circumferential magnetic distribution of the outer peripheral surface of the permanent magnet layer 11 of the PPC type developing device shown in FIG.

This figure shows that the magnitude of the magnetic flux fluctuates little by little due to the interaction between the N pole of the permanent magnet shaft 12 and the sleeve-side permanent magnet layer 11.

In the configuration of the first embodiment, a multipolar magnetized permanent magnet layer 11 provided on the outer peripheral surface of the non-magnetic cylindrical sleeve 10
On the surface of the non-magnetic cylindrical sleeve 1 ( ), it is also possible to adopt counterclockwise rotation (however, in the design "biaxial rotation"). ) and the magnetic force of the multi-pole N and S poles, the toner and carrier adhere evenly and directly, and are transported as the non-magnetic cylindrical sleeve 10 rotates.
As shown in the developed view of the figure and the enlarged view of FIG. 6 Rub the surface. Thereby, a predetermined developing action can be performed.

The above is an outline of the operation, but next we will consider the practical development range that does not cause striped development unevenness or fog development.

In FIG. 3, the permanent magnet 7 (N 1
Letting the magnetic pole width of 1 be W (mm), how the distance 2W between the centers of the same magnetic poles is transferred to the latent image surface of the photoreceptor drum 6 is expressed by a formula. However, S: moving speed of the latent image on the photosensitive drum 6 (man/
see ) P: Number of magnetic poles of permanent magnet layer 11 N: Number of rotations (rps) of permanent magnet layer 11 φ: Permanent magnet W
It is expressed as the outer diameter (Im) of J11. Furthermore, here, since the gap between the photosensitive drum 6 and the sleeve-side permanent magnet N11 is a small value relative to their respective outer diameters, its influence will be ignored.

Now, in the #fJJ diagram, if we consider the brush-like spikes on the outer surface of the permanent magnet layer 11 of the developer in which toner and magnetic carrier are mixed, we can see that the N pole for development of the permanent magnet shaft 12 and the magnetic pole of the permanent magnet layer 11 It can be seen that brush-like spikes can be seen in the case of homopolar comrades. Between different poles, the developer is directed in the circumferential direction of the sleeve. Therefore, it contributes to the electrostatic latent image on the photoreceptor drum 6. The only spikes that appear are the same polarity as the N-pole for development.

Now, assuming that spikes occur only at the center point of the 7;8 N pole, which is the same as the developing N pole of the sleeve-side permanent magnet layer 11, the electrostatic latent image on the photoreceptor drum 6 is completely [At low values, the 1-toner adheres in stripes, resulting in striped development. However, the magnetic pole width W of the sleeve-side permanent magnet layer 11 (() is
Since it has an effective spike width We similar to J in FIG. 4, it is possible to find a practical development range in which striped development does not occur.

This effective Hotate Sapporo We has a slight difference in the magnetic properties of the magnetic carrier and the permanent magnet on the sleeve side) VJll, but the W-W ego i in Fig. 5 is different from the magnetic pole 1 corner W.
It has been found that there is a relationship between the n curve and the W-Wcmax curve. The measurement conditions in this case are that the surface magnetic flux density of the magnetic pole of the permanent magnet layer 11 is /1. 0 0 to E3 0 (l
G a. u! Xs, the surface magnetic flux density on the surface of the permanent magnet layer of the developing magnetic pole of the permanent magnet shaft 12 is 50() to 100
0 Gauss, which is a value within the applicable range of general magnetic carriers.

The magnetic carrier used was an iron powder-based, 7-Elai 1-based soft magnetic carrier, and the particle size was 2o to 200μ.
The electrical resistance is 109 to 1016 Ω-CIll.

The surface potential of the photosensitive drum 6 was set at 6°O to 1000V. Further, when determining the effective spike width We as shown in FIG. 4, the gap a between the photoreceptor drum 6 and the outer peripheral surface of the permanent magnet layer 11 was set in the usual range of 0.3 to 4vn. It was also confirmed that if the width of the developing magnetic pole (N pole) of the permanent magnet shaft 12 is 2w or more, the effective standing of the electrostatic latent image on the photoreceptor drum 6 is satisfied.

The W, -Wemax curve and the W-Wemin curve in FIG. 5 correspond to the surface magnetic pole of the permanent magnet layer 11 and the permanent magnet axis 1.
2 shows the maximum and minimum values of the effective spike width We, which includes the above-mentioned variations in the developing magnetic poles of No. 2 and variations in the magnetic carrier.

FIG. 6 shows the relationship between the magnetic pole width W and the center-to-center distance R of the transferred magnetic poles, which is derived from the equation (1). At this time, the parameter Cr is the ratio of the outer peripheral speed of the photoreceptor drum 6 (latent image moving speed S) and the outer peripheral speed of the sleeve-side permanent magnet layer 11. In the above relationship, W- in FIG.
By superimposing the W e +oa x curves, the practical development range is set.

In other words, the upper side of W - W e + nax is a range where striped development unevenness occurs and is therefore an unsuitable part for development.If the magnetic pole width is smaller than 1vnm, this is a range where the magnetic properties of the magnetic pole are deteriorated and the spikes are insufficient, making development unsuitable. . On the other hand, Cr=0.
A portion smaller than 2 is a range where a phenomenon occurs, possibly due to toner scattering from the tip of the mixture of magnetic carrier and toner, and is also unsuitable for development. Therefore, W
-W e+nax curve, diagonal line of Cr=0.2 and W=1
The shaded area surrounded by the straight line is the optimum range for practical development.

Note that instead of W e m n ×, W e m i
It is obvious that the optimal range is reduced if the value of n is assumed.

According to the configuration of the first embodiment, the following effects can be achieved -1-
I can do something.

(1) It is possible to directly attract the carrier and toner by the multipolar magnetized permanent magnet layer 11 that is wrapped around the outer peripheral surface of the non-magnetic cylindrical sleeve 10 and provided in a layered manner by fitting or electrostatic coating. , carrier and toner can be uniformly transported. Furthermore, by appropriately setting the developing conditions, it is possible to obtain good image quality without striped unevenness and without blurring caused by flying toner.

(2) The structure of the permanent magnet shaft 12 provided inside the non-magnetic cylindrical sleeve 10 is extremely simple, and the irregularly shaped shafts 71 and 13
The structure is also easy, and the cost is 30 to 50 compared to the conventional one.
% weight reduction.

Moreover, cost reduction can be achieved.

(3) The carrier and toner can be stirred by reversing the carrier using the multi-pole magnetic pole of the permanent magnet layer 11, and the carrier and toner stirring mechanism can be simplified or omitted. can.

FIG. 7 shows a second embodiment of the invention. In this case, the permanent magnet shaft 12A has a permanent magnet 14 having an N developing magnetic pole and a permanent magnet 15 having stirring phase magnetic poles N and S poles fixed to the irregularly shaped shirt 13A. As a result, the toner and carrier are sufficiently agitated due to the generation of friction due to the counterclockwise rotation of the non-magnetic cylindrical sleeve 10 and the reversal effect of the carrier due to the alternating arrival of N and S poles. directly onto the surface of the permanent magnet layer 1] in a state of almost uniformity,
The stirring action can be performed even better.

Note that the other structure may be the same as that of the first embodiment described above.

Figure 8 shows the permanent magnet W of the PPC type developing device shown in Figure 7.
The circumferential magnetic distribution of i11 is shown. Also in this figure,
It can be seen that the magnitude of the magnetic flux fluctuates little by little due to the interaction between the N and S poles of the permanent magnet shaft 12A and the sleeve-side permanent magnet layer 11.

(Effects of the Invention) As explained above, according to the PPC type developing device of the present invention, a non-magnetic cylindrical sleeve is rotatably provided around the permanent magnet shaft, and a plurality of non-magnetic cylindrical sleeves are provided on the outer or inner peripheral surface of the cylindrical sleeve. Since a polarized permanent magnet layer is provided, the structure of the permanent magnet shaft inside the sleeve can be simplified and lightweight, and the mechanism for stirring the toner and carrier can be simplified or omitted. In addition, by appropriately setting development conditions, it is possible to produce good images without striped unevenness or fogging. Furthermore, since the multi-pole magnetized permanent magnet layer can directly and uniformly attract toner and carrier, P
In addition to exhibiting sufficiently good performance as a PC type developing device, it is also easy to manufacture and reduces cost.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing a first embodiment of the PPC type developing device according to the present invention, FIG. 2 is a graph showing the surface magnetic flux density of the permanent magnet layer of the PPC type developing device of the first embodiment, and FIG. The figure is an enlarged explanatory diagram of the photoreceptor drum and the part facing it,
FIG. 4 is an enlarged side sectional view of the part facing the photoreceptor drum;
FIG. 5 is a graph showing the relationship between the magnetic pole width W and the effective spike width We, FIG. 6 is a graph showing the practical development range, FIG. 7 is a side sectional view showing the second embodiment of the present invention, and FIG. The figure is a graph showing the surface magnetic flux density of the permanent magnet layer of the PPC type developing device of the second embodiment, and FIG. 9 is a side sectional view showing an example of the structure of the conventional PPC type developing device. 1.10...Nonmagnetic cylindrical sleeve, 2, 12, 12A
... Permanent magnetic f-axis, 3, 13, 1.3A ... Unusual shaft, 4, . 14,115...Permanent magnet, 5...
Developer container, 6... photosensitive drum, 8... regulation plate,
11...Permanent magnet layer. Patented Kakujin TDC Co., Ltd.

Claims (1)

[Claims] (1) A permanent magnet shaft having a developing magnetic pole that always faces the photoreceptor drum is fixedly supported, a non-magnetic cylindrical sleeve is rotatably provided around the permanent magnet shaft, and the outer circumferential surface or inner circumference of the cylindrical sleeve is A PPC type developing device is provided with a multi-pole magnetized permanent magnet layer on its surface, and the permanent magnet layer attracts and conveys a developer containing a mixture of toner and magnetic carrier, wherein the magnetic pole width W of the permanent magnet layer is 1 mm to 7.5 mm, the number of magnetic poles of the permanent magnet layer is P, the rotation speed of the permanent magnet layer is N (rps), and the moving speed of the latent image on the photosensitive drum is 5 (mm/sec). Then, the distance R between the centers of the transferred same magnetic poles, expressed as R=2S/(P・N) (mm), is 0.4 mm to 3
．． 0 mm, and a ratio Cr of the moving speed S of the latent image to the circumferential speed of the permanent magnet layer is set to 0.2 to 0.4.