JPH02267576A - Developing device - Google Patents

Abstract

PURPOSE:To obtain an alternation rotating magnetic field and to quiet a rotational noise by a simple constitution by bringing an AC current of plural phases to electric conduction to plural sets of armature coils. CONSTITUTION:Along the inside circumference of a cylinder 11 of a developing sleeve 10, a single coil (b) of an armature coil 13 is provided between single coils (a) of an armature coil 12, and provided by shifting electrical angles of the adjacent single coils (a), (b) by 90 deg. each. In this state, an AC current of two phases being 90 deg. out of phase is brought to electric conduction to the coils 12, 13, respectively, and on the outside periphery of the cylinder 11, an alternation rotating magnetic field is generated. In such a way, while a magnetic developer is being attracted onto the outside circumferential surface of the cylinder 11, the developer moves on the outside circumferential surface of the cylinder in accordance with a rotating speed of the rotating magnetic field. Accordingly, the developer moves to an image carrying body 1 from a prescribed position in a developing device 3, and attracted to its electrostatic latent image.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a developing device of an image forming apparatus that employs electrophotography or the like.

(Prior art) For example, in a copying machine that uses electrophotography, an electrostatic latent image formed on a photosensitive drum, which is an image carrier, is developed by a developing device, and this is visualized as a developed image. Is there a need to do that? When developing an electrostatic latent image, do you need to supply the developer (toner) in the developing device to the electrostatic latent image through the developing device? It's a sleeve. The developing sleeve generally rotates a multi-pole magnetized permanent magnet within a cylindrical member made of a non-magnetic material, and utilizes the fact that the leakage magnetic field from the permanent magnet moves with the rotation of the permanent magnet. Many devices are used that supply magnetic toner along the outer peripheral surface toward an adjacent photosensitive drum.

A developing device 100 having such a developing sleeve will be described with reference to FIG. a non-magnetic thin-walled cylindrical member ill in contact with the magnetic toner), and the cylindrical member Ill
An annular, multi-pole magnetized permanent magnet 1 rotatably disposed inside
It is composed of 12 mag. and the cylindrical member 11
Toner T is attracted to the outer periphery of the magnet 1 as shown by diagonal lines in FIG. 1 due to a leakage magnetic field from an internal permanent magnet 112.

Here, if the permanent magnet 112 rotates counterclockwise as shown by the arrow in the figure, its leakage magnetic field also rotates, so that the attracted toner T on the first cylindrical member 111 also moves in the opposite direction to the rotation of the permanent magnet 112, that is, as shown in the figure. It will rotate and move clockwise as shown. Therefore, the attracted toner T on the cylindrical member 111 is sequentially moved to a portion facing the photosensitive drum 120 by the rotation of the permanent magnet 112, and this toner is attracted to the electrostatic latent image on the photosensitive drum 120, so that the toner T is attracted to the electrostatic latent image on the photosensitive drum 120. This means that it is possible to convert the image into a toner image.

(Problem to be Solved by the Invention) However, since the basic principle of the developing device 100 according to the above-mentioned prior art is to rotate the permanent magnet 112, a bearing device for rotatably supporting the permanent magnet 112, a bearing device for rotationally supporting the permanent magnet 112, etc. It requires a motor, belt, reduction gear, etc. for rotation, making it structurally complex.

Also, since the permanent magnet 112 rotates, rotation noise is generated.
This has caused the inconvenience of generating noise in copying machines, printers, etc. used in quiet offices and the like.

The present invention has been made in view of the above problems, and its objectives are: *When supplying developer to an electrostatic latent image on a carrier, there is no need for mechanical rotating parts, and the structure is simple; The purpose is to provide a noise-free developing device.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a developing device that develops an electrostatic latent image on an image carrier by moving a developer using magnetic force. A first armature coil made of P single coils and a second armature coil made of P single coils are placed inside a thin cylinder made of a non-magnetic material in the circumferential direction of this cylinder. The first. An alternating rotating magnetic field is generated on the outer periphery of the cylinder by applying two-phase alternating currents having a phase difference of 90 degrees to the second armature coil, and the rotating magnetic field carries an image of the magnetic developer along the outer periphery of the cylinder. It is characterized by moving towards the body.

The present invention also provides a developing device that develops an electrostatic latent image on an image carrier by moving a developer using magnetic force, in which a thin cylinder made of a non-magnetic material is disposed close to the image carrier. The first coil consists of 2P single coils each. Second. The third armature coils are arranged in the circumferential direction of the cylinder such that the single coils alternate with each other and are shifted by 120 degrees in electrical angle from adjacent single coils.
A three-phase alternating current with a phase difference of 120 degrees is applied to the second and third armature coils to generate an alternating rotating magnetic field on the outer periphery of the cylinder, and the rotating magnetic field causes the magnetic developer to move along the outer periphery of the cylinder. is characterized in that it moves toward the image carrier.

(Function) A single coil of the second armature coil is arranged between the single coils of the first armature coil along the inner circumference of the cylinder, and a single coil of the adjacent first armature coil and the single coil of the first armature coil The second armature coil is arranged with an electrical angle shifted from the single coil by 90 degrees, and the first. Since the second armature coils are energized with two-phase traffic currents each having a phase difference of 90 degrees, an alternating rotating magnetic field can be generated on the outer periphery of one cylinder.

This produces an effect similar to that of rotating a permanent magnet within a cylinder, so the magnetic developer is absorbed and leaked onto the outer circumferential surface of the cylinder, and the developer moves on the outer circumferential surface of the cylinder according to the rotational speed of the rotating magnetic field. . Therefore, the developer moves from a predetermined position in the developing device toward the image carrier and is attracted to the electrostatic latent image.

In addition, the first of three sets using three-phase alternating current. Since the concept is exactly the same when using the 25th w43rd armature coil, the explanation of its operation will be omitted.

(Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings, taking a copying machine that employs electrophotography as an example.

First, an outline of image formation by a copying machine will be explained with reference to FIG. 1. In the figure, 1 is a photosensitive drum which is an image bearing member, and around the photosensitive drum 1 are primary chargers 2. Developing device f3. Transfer charger4. A cleaning device 5 is provided. That is, when image light from a document (not shown) is exposed onto the photosensitive drum l uniformly charged by the primary charger 2, an electrostatic latent image is formed on the photosensitive drum 1 due to the image light. Ru. The electrostatic latent image moves toward the developing device 3 as the photosensitive drum l rotates, and is developed through the developer (magnetic toner containing a magnetic material, hereinafter referred to as toner) in the developing device 3. The image is visualized and turned into a toner image. This toner image is transferred from a paper feed system (not shown) onto a transfer paper R via a transfer charger 4. The transfer paper R carrying the primary toner image is transferred to a fixing device (not shown). sent to
This toner image is fixed as a permanent image on the transfer paper R, and the photosensitive tram 1 after the transfer is transferred to a cleaning device 5.
The residual toner is cleaned, and images are sequentially formed on the transfer paper R by performing similar operations.

Here, the developing device 3 includes a developing device main body 3a having toner therein, and is housed within the developing device main body 3a, and supplies the toner in the developing device main body 3a toward the photosensitive tram l. It is composed of a developing sleeve 10, etc., which converts the electrostatic latent image on the top into a toner image. The developing sleeve lO has a portion exposed outwardly from the developing device main body 3a disposed close to the photosensitive drum, and moves the toner in the developing device main body 3a to the proximal portion 10a to the photosensitive tram l. It is made to adhere to the electrostatic latent image on the photosensitive drum.

First, based on Figures 2 to 6, the developing sleeve l
The toner transport mechanism using O will be explained.

Figure t14P is a diagram conceptually showing a cross section of the developing sleeve IO, in which a first armature coil 12 is arranged on the outside and a second armature coil 13 is arranged on the inside of the thin cylindrical member 11 made of a non-magnetic material. It is set up. First and second armature coils 12
．． 13 are 22 single coils (P is a positive integer and is P-9 in the case of this embodiment) each wound around a predetermined core, that is, 18 single coils a or b are wound in the circumferential direction of the cylindrical member 11. The coils a (or b) of each car are arranged at equal intervals.
are electrically connected to alternately generate magnetic fields of opposite polarity.

That is, if two magnetic poles, N and S, are represented by 1, for example, the odd-numbered single coil al+83+・"all of the first armature coil 12 generates N magnetic poles on the radially outer side of the cylindrical member 11, The even-numbered single coils a,,a,...mal@ generate magnetic poles S on the radially outer side of the cylindrical member 11, and similarly the odd-numbered single coils b,... b
3. ...If b17 generates N magnetic poles on the radially outer side of the cylindrical member 11, even numbered single coils ba, b
4. ...b18 generates a magnetic pole of S on the radially outer side of the cylindrical member 11.

Further, the first armature coil 12 and the second armature coil 13 are arranged to be shifted from each other by half the pitch of the single coil a (or b), that is, by 90 degrees in electrical angle.

Here, to explain the electrical connection method between each single coil 3 of the first armature coil 12 with reference to FIG. 3, the current flows in from the right side of the single coil a14 and flows out from the left side of the single coil aSS. The single coil a13 and the single coil a14 are electrically connected so that the current flows in and flows out from the right side. Single coil a1. ... are connected in the same way, so that the current finally flows out from the right end of the single coil a4, and the right ends of each of the single coils a14+a11 serve as input terminals Pa of the power supply. Therefore, the input terminal Pa
When an alternating current is applied to the coils, the magnetic fields of the adjacent single coils a have opposite polarities. In addition, pb is the second armature coil 13
It is assumed that the electrical connection between each single coil 5 of this second armature coil 13 is the same as that of the first tJm child coil.

In addition, in the above explanation, the first and second armature coils 12, 13
Although the case where the single coils a and b are connected in series has been described, it is not limited to this, and each single coil a or b may be connected in parallel, or several single coils may be connected in parallel. Various connection methods are possible, such as connecting a or b in series and connecting them in parallel, and these are selected depending on the balance between the power supply voltage used and the inductance of the coil.

Further, as shown in FIG. 5, the first and second armature coils 12 and 13 are supplied with alternating currents having a frequency f whose phases are shifted by 90 degrees, that is, Icos2πft.

It is necessary to supply l5in2πft, which is the fourth
As shown in the figure, a power supply 20 and first and second armature coils 1
2.13 power supply input terminal Pa.

This is realized by connecting the drive circuit 21 between pb and pb.

FIG. 6 shows an example of this drive circuit 21.
is a well-known CR oscillation circuit, CI+ Ct *r 11 r
2 is a capacitor and electric resistance that determine the oscillation frequency, and their respective capacitance and resistance are (: 1 * Cw +
If r I+ r 2, one oscillation frequency f is expressed as follows. Note that Vcc is the voltage of the power supply, and A1
is an operational amplifier. Also, 21B is the CR transmitting circuit 21A
This is a circuit that creates two-phase alternating current with a phase shift of 90 degrees from the alternating current of frequency If generated by capacitor C.
3 generates alternating currents with a phase shift of 90 degrees. In addition, A2 is an operational amplifier for a buffer amplifier, and 2
1a.

21b is the first. This is an output terminal connected to the input terminals P- and Pb of the power source of the second armature coil 12.13.

Next, the first. The action of the second armature coil 12.13 will be explained.

1st. When an alternating current with a frequency f whose phase is shifted by 90 degrees is applied to the second armature coils 12 and 13, the first
, a rotating magnetic field is generated around the second armature coil 12, 13. This will be explained below using a formula.

First, when a unit current is passed through the first armature coil 12, the magnetic field Ha generated in the radial direction of the cylindrical member 11 is determined by the number of single coils a being 2P, and the circumferential angle along the outer peripheral surface of the cylindrical member 11 from a predetermined position. Let θ (see Figure 2) and the constant be Hv.

It is expressed as HaxHv-sinPθ. Further, when a unit current is passed through the second armature coil 13, the magnetic field Hb generated in the radial direction of the cylindrical member 11 is also expressed as HbwHv-cosPθ as described above.

Next, Ico is applied to the above first and second armature coils 12 and 13.
s2wft, Isin2wft with 90 degree phase difference
When the alternating current of each phase is applied, the first. The composite magnetic field H due to the second armature coil 12.13 is:

HwHalcos2wft +) lb-1sin 2πft mHv 1 -5in(Pθ+2πft) becomes 1
The composite magnetic field H is an alternating rotating magnetic field in which two sine waves advance in the direction of θ at a frequency f. Note that I is the amplitude of the alternating current.

Therefore, in the present developing sleeve 1O as well, it is possible to generate a rotating magnetic field on the outer peripheral surface of the cylindrical member 11.
As shown in the prior art of FIG.

By moving the toner in the circumferential direction of the cylindrical member 11, the electrostatic latent image on the photosensitive tram l can be developed with the toner.

As mentioned above, the first. 2nd armature coil 12° 13 to 90
The cylindrical member 11 is
A rotating magnetic field can be generated on the outer circumferential surface of the
There is no need to mechanically rotate the permanent magnet within the cylindrical member 11 as in the past, and there is no need for a bearing device for the permanent magnet, a motor, a belt, or a speed reducer for rotating the permanent magnet. Due to permanent magnets etc.
No rotational noise occurs at all.

Next, the specific structure of the first and second armature coils 12, 13 will be explained with reference to FIGS. 7 to 9.

FIG. 7 shows the concentrated winding type first and second armature coils 12.
13, 30 is a core made of a laminated iron core, and 2 The outer periphery of the core 30 has 4P protrusions (in this case, P=5, so 4P-20) at equal intervals in the circumferential direction. pole 30-1. ...is formed. The salient pole 30-1.
, coils 31, . are constructed, and these single coils al + a2 + a, ... are arranged so that the adjacent single coils (for example, a8 for a) generate magnetic fields of opposite polarity, that is, they are shifted by 180 degrees in electrical angle. The single coils b+, b*, b3, etc. of the second armature coil 13 are electrically connected between them. The single coils b are also electrically connected so that the adjacent fist coils (for example, bi generate a magnetic field of opposite polarity to bl, that is, are shifted by 180 degrees in electrical angle).

Further, adjacent single coils a and b are electrically positioned so as to be shifted by 90 degrees in electrical angle.

That is, if the two magnetic poles are N and S, then on the outer end side of each single coil a and b, for example, as shown in the figure, there is a single coil &, clockwise like this, N, I Nh I Ss * Sb + N, etc.
Nb,... magnetic poles are generated, but the adjacent first
Single coil a of armature coil 12 and second armature coil 13
Since the single coil b is arranged to be deviated from the single coil b by 90 degrees in electrical angle, Na and Nb, Nb and Sa, Sa and s b, -... are each separated by 90 degrees in electrical angle. There will be a difference. Therefore, if alternating currents with a phase difference of 90 degrees are applied to the second armature coil 12.13, a rotating magnetic field can be generated by the first and second armature coils 12.13. Become.

Figure 8 shows the first and second armature coils 12 of the distributed winding type.
．． 13, and the core 30 has 20 salient poles 30-1. ..., but the coil 31. ... is wound across adjacent salient poles 30-1, -.... That is, for example, in the single coil a□ of the first armature coil 12, the coil 31 is wound around the salient poles 30-1 and 30-2, and the single coil a is wound around the salient poles 30-1 and 30-2.
The coil 31 is wound around the salient poles 30-2 and 30-3, and the single coil b1 of the second armature coil 13 has the coil 31 wound around the salient poles 30-2 and 30-3. The single coil b2 is arranged so that the coil 31 is wound across the salient poles 30-4 and 30-5.

That is, for example, the single coils a and A share the salient pole 30-2, and the first. The second armature coils 12 and 13 constitute a so-called distributed winding armature. Even in such a case, each adjacent single coil al of the first armature coil 12.

@ * , 6 mm are electrically connected to each other so that they are shifted by 180 degrees in electrical angle, and similarly, each adjacent single coil b+ * b * * "" of the second armature coil 13 is also electrically connected so that they are shifted by 180 degrees in electrical angle. By connecting the concentrated winding first and second armature coils 12.1 shown in FIG.
It can perform the same function as 3.

Fig. 9 shows the wave-wound type first and second armature coils 1.
2.13, and this type also has exactly the same function as the one with 5 concentrated windings and distributed winding.

Now, in the above explanation, we have explained the armature coil when supplying two-phase alternating current, but generating an alternating rotating magnetic field is not limited to two-phase, but various types such as three-phase and four-phase. Configurable. However, as the number of phases increases, the structure of the drive circuit 21 becomes more complex, and the pitch of the magnetic poles around the two cylindrical members 11 increases, resulting in a decrease in the number of traveling waves that can be obtained on the same circumference. The higher the quality of the alternating rotating magnetic field, the higher the quality of the alternating rotating magnetic field.

FIG. 10 shows a specific configuration of a concentrated winding armature coil for three-phase alternating current, with every third salient pole 3 in the core 30
The single coils a8, 'a I + ``'' and s, b, -... and CI t Ct + ``'' of each 0-1... are electrically connected to the first, second, and Forming three armature coils 12, 13 and 14, adjacent single coils a and b
, c is set to 120 degrees, then this first . Second. By energizing the third armature coils 12, 13, and 14 with three-phase alternating current whose phases differ by 120 degrees, the first, second, and third armature coils are energized. An alternating rotating magnetic field can be generated around the third armature coils 12, 13, and 14.

FIG. 11 shows a specific configuration of a distributed winding armature coil for three-phase alternating current. By winding the coil 31 around the three salient poles 30-1 in the core 30, One single coil a, b+, or cl is formed, and the rest is the same as in the case of two-phase alternating current, so the explanation will be omitted.

Although the above explanation has been made with reference to a copying machine that uses electrophotography, the developing device according to the present invention is not limited to electrophotography, and can be used as long as it simply develops an electrostatic latent image with a magnetic developer. Of course, it can be applied to anything.

(Effect of the invention) As is clear from the above explanation, according to the present invention, two or three sets of
By applying two-phase or three-phase alternating current to a set of armature coils, it is possible to obtain the same alternating rotating magnetic field as when rotating a multi-pole magnetized permanent magnet at a constant speed, and the configuration is simpler than the conventional one. 2, it is possible to provide a quiet developing device with no rotational noise at low cost.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining image formation by a copying machine, Fig. 2 is a conceptual cross-sectional view of the developing sleeve, Fig. 3 is a diagram showing the wiring state of the armature coil, and Fig. 4 is a diagram showing the wiring state of the armature coil. Figure 5 is a diagram explaining two alternating currents with a phase difference of 90 degrees, Figure 6 is a circuit diagram for generating alternating currents with a phase difference of 90 degrees at a predetermined frequency, and Figure 7 is a diagram explaining the power supply of two AC currents with a phase difference of 90 degrees. First, in the case of group concentrated winding. An explanatory diagram of the second armature coil, FIG. 8 shows the first armature coil in the case of two sets of distributed winding. An explanatory diagram of the second armature coil, FIG. 9 shows the first armature coil in the case of two-phase wave winding. An explanatory diagram of the second armature coil, Fig. 1θ shows the first armature coil in the case of three sets of concentrated winding. An explanatory diagram of the second and third armature coils, Figure 1ul1 shows the first and third armature coils in the case of three-phase distributed winding. Second. An explanatory diagram of the third armature coil, FIG. 12 is an explanatory diagram of the prior art. l...Photosensitive drum (image carrier), 3-...Developing device 1
1... Cylindrical member (cylinder), 12-... First armature coil (first armature coil), 13... Second armature coil (second armature coil), 14-... Third armature coil (third armature coil), a, b, c... single coil. Patent Applicant Canon Co., Ltd. Canon Seiki Co., Ltd. Representative Patent Attorney Ryo Yamashita Figure 4, 10 Figure 5 Figure 8 Figure 9j Figure 12 Figure 10

Claims (4)

[Claims] (1) In a developing device that develops an electrostatic latent image on an image carrier by moving a developer using magnetic force, a thin cylinder made of a non-magnetic material is disposed close to the image carrier. A first armature coil consisting of P single coils and a second armature coil similarly consisting of P single coils are arranged alternately in the circumferential direction of this cylinder with electrical angles shifted by 90 degrees from each other. A two-phase alternating current having a phase different by 90 degrees is applied to the first and second armature coils to generate an alternating rotating magnetic field on the outer periphery of the cylinder, and the rotating magnetic field causes the magnetic developer to move along the outer periphery of the cylinder. A developing device characterized in that it moves toward an image carrier. (2) The first and second armature coils are comprised of two sets of armature coils each consisting of P single coils each concentratedly wound around 2P laminated salient pole magnetic cores. The developing device according to claim 1. (3) The first and second armature coils are two sets each consisting of 2P single coils with distributed winding wound across two adjacent salient poles of 4P laminated salient pole magnetic cores. 2. The developing device according to claim 1, comprising an armature coil. (4) In a developing device that develops an electrostatic latent image on an image carrier by moving a developer using magnetic force, each of the two pins is placed inside a thin cylinder made of a non-magnetic material disposed close to the image carrier. The first, second, and third armature coils each consisting of a single coil are arranged alternately in the circumferential direction of this cylinder, and the electrical angle between adjacent single coils is 12.
The first, second, and third armature coils are arranged so that they are shifted by 0 degrees, and three-phase alternating currents having a phase difference of 120 degrees are applied to the first, second, and third armature coils to create an alternating rotating magnetic field on the outer periphery of the cylinder. What is claimed is: 1. A developing device that generates a rotating magnetic field and moves a magnetic developer toward an image bearing member along an outer circumferential surface of a cylinder.