JP2003153516A - Dc brushless motor, light deflector, optical scanning device, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brushless motor capable of attaining high efficiency by improving motor efficiency; a light deflector capable of attaining high-speed rotation even in a rotary polygon mirror with relatively high windage loss; an optical scanning device with high speed and density using the light deflector; and an image forming device with high speed and quality. SOLUTION: This DC brushless motor of N-phase (N: an integer of two or more) comprises a rotor disposed with a permanent magnet, winding coils for N-phase respectively on the inner-periphery side and outer-periphery side where the permanent magnet rotates, and a rotating magnetic-field generating means arranged on inner-periphery side and outer-periphery side where the permanent magnet rotates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC brushless motor, an optical polarizer, an optical scanning device and an image forming apparatus, and more particularly to a high speed rotation of a dynamic pressure air bearing type polygon scanner used in a digital copying machine, a laser printer or the like. DC brushless motor

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus using an optical scanning device such as a digital copying machine or a laser printer has been rapidly improved due to excellent features such as high print quality, high speed printing, low noise and low cost. It is becoming popular. The optical deflector, which is a component of the optical scanning device of these image forming apparatuses, is required to have a rotation speed corresponding to the print speed and pixel density of the image forming apparatus.

In recent years, image forming apparatuses have been improved in printing speed, image quality by increasing pixel density, and colorization, and a polygon scanner used as an optical deflector rotates at a high speed of 20000 rpm or more. Is required. On the other hand, in order to satisfy the required qualities of long life, high durability and low noise in terms of bearing life and bearing noise, an optical deflector for high speed rotation has been developed using a dynamic air bearing. There is. In addition, high image quality due to high printing speed using an optical deflector and high pixel density,
For colorization, an optical scanning device using a plurality of laser light sources has been developed as an optical scanning device. As the optical deflector, a rotary polygon mirror with a plurality of stages formed in the axial direction,
High-speed rotation is desired. As one of conventional optical scanning devices using the plurality of laser light sources, Japanese Patent Application Laid-Open No. HEI-1
Japanese Patent Laid-Open No. 1-271654 (hereinafter referred to as Conventional Example 1)
A polygon scanner using a polygon mirror having two mirror surface portions and a non-mirror surface portion having a diameter smaller than the diameter of the mirror surface portions has been proposed. Further, since the light spot that does not contribute to higher pixel density is a small-diameter spot, it is required that the rotary polygonal mirror has a large horizontal width and the rotary polygonal mirror has a large inscribed circle radius.

[0004]

However, according to the above-mentioned conventional example 1, the wind loss due to the rotary polygon mirror increases,
The efficiency of the motor was low and it was difficult to rotate at high speed. In a DC brushless sliding motor proposed in Japanese Patent Application Laid-Open Nos. 2000-50603 and 2000-37067 as a conventional motor system for increasing the efficiency of the motor, a permanent magnet fixed to a rotating body is used. The efficiency of the motor was low because the stator having the winding coil wound was arranged on one of the outer circumference side and the outer circumference side, and only the magnetic force on the inner circumference side of the permanent magnet was used.

The present invention has been made to solve these problems, provides a brushless motor having improved motor efficiency and high efficiency, and is capable of rotating a rotary polygon mirror having a relatively large wind loss up to a high speed. It is an object of the present invention to provide an optical deflector capable of Another object of the present invention is to provide a high-speed, high-density optical scanning device using the optical deflector of the present invention, and to provide a high-speed, high-quality image forming apparatus.

[0006]

In order to solve the above-mentioned problems, the N-phase (N is an integer of 2 or more) DC brushless motor of the present invention comprises a rotating body in which permanent magnets are arranged and fixed,
Having winding coils for N phases respectively arranged and fixed on the inner circumference side and the outer circumference side where the permanent magnet rotates, and having a rotating magnetic field generating means arranged on the inner circumference side and the outer circumference side where the permanent magnet rotates. Is characterized by. Therefore, it is possible to provide a highly efficient DC brushless motor by utilizing the magnetic forces on the inner circumference side and the outer circumference side of the permanent magnet fixed to the rotating body to drive the rotating body.

Another aspect of the present invention is a DC brushless motor of N phase (N is an integer of 2 or more) in which a permanent magnet is arranged and fixed, and a permanent magnet is arranged on the inner peripheral side where the permanent magnet rotates. An inner circumference side stator in which a plurality of winding coils are wound around a stator core made of a magnetic material, and an outer circumference side stator in which a plurality of winding coils are wound around a stator core made of a ferromagnetic material and arranged on the outer circumference side of a permanent magnet. And a rotating magnetic field generating means including. Therefore, since the windings are distributed on the inner peripheral side and the outer peripheral side of the permanent magnet, the number of windings is small, and the axial thickness of the stator including the windings can be reduced.

Further, a holding member for holding the outer peripheral side stator is provided, a collar portion is formed extending to the holding member, and a bent portion for elastic fixing is formed on the collar portion, so that the holding member is interposed. It is possible to provide a DC brushless motor in which the outer peripheral side stator is easily fixed and assembled.

An optical deflector of another invention has a rotating body on which a rotary polygon mirror is formed, a bearing for rotatably supporting the rotating body, and a motor for driving the rotating body. It is the DC brushless motor. Therefore, an optical deflector with high motor efficiency and low power consumption can be provided.

Further, as another invention, a beam from a semiconductor laser is guided to a surface to be scanned through an optical system including an optical deflector to form a light spot, which is deflected by the optical deflector to be scanned. In the optical scanning device that scans the surface with the scanning line, the optical deflector is the optical deflector. Therefore, it is possible to provide an optical scanning device having a high scanning speed, a high pixel density, and low power consumption.

In addition, a plurality of beams from the semiconductor laser are guided to the surface to be scanned through an optical system including an optical deflector to form a plurality of light spots separated in the sub-scanning direction,
It is possible to provide a multi-beam type optical scanning device that has a high scanning speed, a high pixel density, and low power consumption by deflecting by a light deflector and scanning a plurality of scanning lines on a surface to be scanned adjacently. .

Further, according to another aspect of the invention, an image forming apparatus that forms a latent image by performing optical scanning on a photosensitive surface of a photosensitive medium by an optical scanning device and visualizes the latent image to obtain an image is The optical scanning device for optically scanning the photosensitive surface of the medium is characterized by using the above optical scanning device. Therefore, high-speed output,
An image forming apparatus with high image quality and low power consumption can be provided.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The N-phase (N is an integer of 2 or more) DC brushless motor of the present invention has a rotating body on which permanent magnets are arranged and fixed, and an inner peripheral side and an outer peripheral side on which the permanent magnets rotate. Rotating magnetic field generating means are respectively arranged and fixed on the winding coils for N phases, and arranged on the inner peripheral side and the outer peripheral side on which the permanent magnet rotates.

[0014]

1 is a sectional view showing the structure of an optical deflector according to an embodiment of the present invention. FIG. 2 is an exploded perspective view showing the structure of the optical deflector of this embodiment. In both figures, a reference surface 21a for attachment to the optical housing is formed on the lower surface of the cover case 21. The housing 1 is fixed to the cover case 21. A bearing mounting portion 1b is formed in the center of the upper surface of the housing 1, and a fixed shaft 2 forming a dynamic pressure air bearing is fixed. A groove 2a for forming a dynamic pressure air bearing is formed on the cylindrical surface of the fixed shaft 2. When the rotating body 3 which is a rotary polygon mirror starts to rotate, the air pressure in the bearing gap formed between the rotating sleeve 16 and the fixed shaft 2 increases, and the rotating body 3 is supported in the radial direction (radial direction) without contact. To do. Inside the fixed shaft 2, a fixed portion 5 of the attraction type magnetic bearing is fixed. The fixed portion 5 of the attraction type magnetic bearing is sandwiched and fixed in the axial direction by the cap member 6 and the stopper 7 being press-fitted and fixed to the inner cylindrical portion of the fixed shaft 2. A fine hole of about φ0.2 to φ0.5 is formed in the central portion of the cap member 6 to dampen the vertical vibration by utilizing the viscous resistance when air passes. Both the cap member 6 and the stopper 7 are made of a non-magnetic material such as a stainless steel plate.

The fixed portion 5 of the attraction type magnetic bearing has a ring-shaped permanent magnet 8 which is magnetized to have two poles in the rotation axis direction and a strong center circle which is smaller than the inner diameter of the ring-shaped permanent magnet 8. It has a first fixed yoke plate 9 made of a magnetic material, and a second fixed yoke plate 10 made of a ferromagnetic material in which a central circle smaller than the inner diameter of the ring-shaped permanent magnet 8 is formed. First fixed yoke plate 9 and second fixed yoke plate 10
Are arranged and fixed such that the ring-shaped permanent magnet 8 is axially sandwiched and the central circle of the first fixed yoke plate 9 and the central circle of the second fixed yoke plate 10 are coaxial with the rotation center axis. ing. As a material for the ring-shaped permanent magnet 8, a rare earth-based permanent magnet is mainly used. Steel plates are used for the fixed yoke plates 9 and 10. The fixed shaft 2 is ceramic,
Alternatively, a non-magnetic material such as an aluminum alloy is used.

Further, on the upper surface of the housing 1, a printed circuit board 11 having a hole formed at a substantially central portion is arranged.
The printed circuit board 11 and the inner peripheral side stator 12 are fitted and fixed to the outer diameter of the bearing mounting portion 1b of the housing 1. Since the housing 1 is made of a conductive material such as aluminum alloy, the printed circuit board is an iron board so that an eddy current does not flow in the housing 1 due to the influence of the alternating magnetic field due to the rotation of the rotor magnet 14 and the loss of the motor does not increase. It is composed of.

The motor section includes a rotor magnet 14 mounted on the rotating body 3, an inner peripheral stator 12, an outer peripheral stator 13, and winding coils 12 of the stators 12 and 13.
The printed circuit board 11 and the like to which a and 13a are connected are configured. The rotor magnet 14 has two stators 12, 13
It is sandwiched between. The inner side stator 12 and the outer side stator 13 have winding coils 1 for three phases, respectively.
2a and 13a are wound. Since the windings are distributed to the inner and outer stators, the number of windings of the stator is small, and the axial thickness of the stator including the windings can be reduced.

Further, the stator is made of a ferromagnetic material,
A laminate of silicon steel plates is used so that eddy currents do not increase the iron loss. A material other than a ferromagnetic material can be used for the stator, but the use efficiency of the magnetism of the winding coil can be increased by using the ferromagnetic material.

Further, the printed circuit board 11 is equipped with a position detecting element for switching energization to the winding coil. An outer peripheral portion of the outer peripheral side stator 13 is press-fitted into the holding member 15 to be held and fixed. Since it is fixed on the outer circumference of the outer circumference side stator 13, it can be firmly fixed with a large holding force, and the assembly is easy. The holding member 15 has a thin-walled cylindrical stator holding portion 15a formed therein and a plurality of slits 15b formed in the stator holding portion 15a. , Easy to fix.

Further, a flange portion 15c is formed extending to the stator holding portion 15a, and the bent portion 15c is formed on the flange portion 15c.
d is formed. The holding member 15 is configured such that the flange portion 15c is sandwiched from above and below and the bent portion 15d is elastically deformed, and thus the outer peripheral side stator 13 is easily fixed and assembled via the holding member 15. Has become. The holding member 15 is made of a ferromagnetic material such as a steel material and also serves as a magnetic yoke of the outer peripheral side stator 13. The holding member 15 is connected to the outer peripheral side stator 13 by the influence of energization of the winding coil of the outer peripheral side stator 13 and excitation switching. The influence of the generated magnetic force is prevented from reaching the outside of the outer circumferential side stator and causing eddy current loss in the cover case 21 and the housing 1 formed of a conductive material such as an aluminum alloy.

Further, in the rotating body 3, a metal outer peripheral member 17 whose main component is aluminum is shrink-fitted and fixed on the outer side of a ceramic rotating sleeve 16 over the entire axial length of the rotating sleeve 16, and a mirror portion is provided. 17a is integrally formed. A rotor magnet 14 for a motor is bonded or press-fitted and fixed to the lower side of the outer peripheral member 17. The rotor magnet 14 may be a permanent magnet divided in the circumferential direction, but is formed in a ring shape so as to be easily bonded or press-fitted. Press-fitting makes it possible to reduce balance and vibration change due to temperature changes, and is therefore suitable as a motor for high speed rotation.

Further, the outer circumference of the rotor magnet 14 is held by a non-magnetic material such as an aluminum alloy so that the magnetic force on the outer circumference is effectively used for driving the motor and the permanent magnet is prevented from being destroyed by the centrifugal force. . In order to hold the outer circumference of the rotor magnet 14 with a non-magnetic material, a rare earth-based permanent magnet is mainly used as the rotor magnet 14. By using a rare earth-based permanent magnet having a strong magnetic force, the rotor magnet 14 and the outer circumference side stator The magnetic gap of 13 is set wide. A closing member 18 having a linear expansion coefficient substantially equal to that of the outer peripheral member 17 is press-fitted and fixed in the through hole at the upper end of the outer peripheral member 17. The closing member 18 has a disc shape. The rotating portion 19 of the suction type magnetic bearing is fixed to the closing member 18. An outer cylindrical surface forming a magnetic gap is formed between the center circle of the first fixed yoke plate 9 and the center circle of the second fixed yoke plate 10 in the rotating portion 19 of the attraction type magnetic bearing, and The cylindrical surface is arranged so as to be coaxial with the central axis of rotation. A permanent magnet or a ferrous steel-based ferromagnetic material is used for the rotating portion 19 of the attraction type magnetic bearing. Since the rotating body 3 is rotated at a high speed, the upper and lower portions of the rotating body 3 are adjusted so that unbalanced vibration is at a very small level.
Balance correction is performed on the correction surfaces 17b and 14a at various locations. The printed circuit board 11 has motor windings 12a, 13
a and the hall element 11a are pattern-wiring, and the drive circuit 2
By 0, the energization of the motor windings 12a and 13a is sequentially switched according to the position detection signal of the hall element 11a to rotate the rotating body 3 to perform constant speed control.

By using the motor configuration of the embodiment described above, an optical deflector with high motor efficiency and low power consumption can be obtained. Further, by using a dynamic pressure bearing as the bearing, it is possible to provide an optical deflector that has a long life and low noise with respect to high speed rotation. Even when a plurality of rotary polygon mirrors are formed in the axial direction and the wind loss is large as in the above-described embodiment, the motor efficiency is high, and thus high speed rotation is possible.

Next, the structure of a DC brushless motor according to another embodiment of the invention will be described with reference to FIGS. 1 and 2, and FIGS. 3 and 4 which are development views showing a series connection method of motor windings. To do.

The stators 12 and 13 are arranged on the inner peripheral side and the outer peripheral side so as to face the rotor magnet 14 magnetized to have four poles (two pole pairs) in the circumferential direction. The rotor magnet 14 has magnetic poles opposite to each other on the inner circumference side and the outer circumference side. In the stator, twelve salient poles are formed on a core made of a ferromagnetic material, and twelve windings are wound in slots between the salient poles. As shown in FIG. 3, the windings of the inner circumference side stator 12 are composed of three phases of U, V and W, and U1, U2, U3 and U4 are a set of four windings, which are U phase, V1, V2, V3 and V4 are V phase, W1, W2 and W
3, W4 constitutes W phase. The winding of the outer circumference side stator 13 is composed of three phases of X, Y, Z, and is X1, X2, X3, X.
4 is the X phase, Y1, Y2, Y3, Y4 is the Y phase, Z1, Z
2, Z3 and Z4 form the Z phase. As shown in FIGS. 3 and 4, adjacent windings of U1, U2, U3, and U4 are wound in opposite directions so that the magnetic poles generated by the energization (on the surface facing the permanent magnet) alternate. There is. Similarly, adjacent windings are wound in opposite directions for the V, W phases and the X, Y, Z phases. U, V, W of the inner circumference side stator 12
The phases and the X, Y, and Z phases of the outer peripheral side stator 13 are connected to the drive circuit by connecting respective winding groups in series or in parallel. In the series connection of FIG. 3 and FIG.
U, V, W phases and the X, Y, Z phases of the outer peripheral side stator 13 are the first phase U phase and X phase, the second phase V phase and Y phase, the third phase W phase and Z phase. The phases are connected in series on the printed circuit board 11. One end of the U-, V-, and W-phase winding groups of the inner circumference side stator 12 is commonly connected by a Y-type connection as shown in FIG. 5, and one end of the X, Y, Z phases of the outer circumference side stator 13 is connected to the drive circuit. Has been done.

Further, in FIG. 5 and FIG. 6 which are development views showing another method of connecting the motor windings in parallel, the inner circumference side stator 12 is shown.
U, V, W phases and the X, Y, Z phases of the outer peripheral side stator 13 are the first phase U phase and X phase, the second phase V phase and Y phase, the third phase W phase and Z phase. Each phase is connected in parallel. As shown in FIG. 6, one end of the U-, V-, and W-phase winding groups of the inner circumference side stator 12 is commonly connected by a Y-type connection, and the other end is connected to a drive circuit. Similarly, the X, Y, and
One end of the Z phase is commonly connected by a Y-type connection, and the other end is connected to the drive circuit. The winding group of each phase is connected to the drive circuit, and switches the phase to be energized according to the position detection signal to generate a rotating magnetic field and rotate the rotating body. In order to detect the rotational position of the permanent magnet, three position detection elements (H
1, H2, H3) are arranged at 60 ° intervals, and two energized phases are selected by the position detection signal. A magnetoelectric conversion element such as a Hall element is used as the position detecting element.

FIG. 7 is a sectional view of a linear brushless motor according to another embodiment of the invention. Position detecting elements H1, H2,
When the N, S, and N poles are detected in H3, two phases U and V are selected for the inner circumferential side stator 12, and two phases X and Y are selected for the outer circumferential side stator 13 to be energized and excited. It shows the state of being performed. In FIG. 7, the inner circumference side stator 12
Then, current flows in from U1 and flows out from V1, so that the salient poles of U1 and U3 are S poles, the salient poles of U2 and U4 are N poles, the salient poles of V1 and V3 are N poles, and V2 and V4. An S pole is generated at the salient pole of the
Flowing in from Y1 and flowing out from Y1, the salient poles of X1 and X3 are S poles, the salient poles of X2 and X4 are N poles, and the salient poles of Y1 and Y3.
The salient poles of No. 3 and No. 4 have salient poles of S,
A magnetic repulsive force or a magnetic attractive force acts between the permanent magnet and the permanent magnet to rotate the permanent magnet counterclockwise.

As described above, in the series connection of FIGS. 3 and 4, one end of each phase winding of the inner peripheral side stator 12 and both ends of each phase winding of the outer peripheral side stator 13 on the printed circuit board 11 are connected. 6 points, total 9 points are connected. Outer peripheral side stator 13
Since the currents flowing in the two phases X and Y of the above flow in the two phases U and V of the inner circumferential side stator 12, the rotating body can be rotated with a small driving current. On the other hand, in the parallel connection of FIGS. 5 and 6, since one end of each of the outer peripheral side stator 13 and the inner peripheral side stator 12 is connected as a common connection point,
On the printed circuit board 11, one end 3 of each phase winding of the inner stator 12 and one end 3 of each phase winding of the outer stator 13
Since it suffices to connect a total of 6 points, it becomes easy to connect the winding to the printed circuit board. The series connection and parallel connection of the windings of the outer circumferential side stator 13 and the inner circumferential side stator 12 can be appropriately selected according to the required characteristics of the motor.

FIG. 8 is a diagram showing the relationship between the generation of a rotating magnetic field due to position detection / energization switching and the rotation of a rotor magnet (rotating body) in another embodiment of the invention. In the figure, energization switching is performed every 30 ° to generate a rotating magnetic field,
The rotating body including the rotor magnet 14 rotates counterclockwise. Therefore, the energization switching is performed 6 times while the rotor magnet 14 rotates 180 °, and 1 rotation is performed during one rotation.
The energization is switched twice. FIG. 9 shows a circuit configuration of a drive element of a drive circuit that supplies a current to each phase winding. In the inner circumference side stator 12, U1 and V1, U2 and V2,
W4, W1, W between U3 and V3, U4 and V4 respectively
A magnetic circuit is formed by sandwiching 2 and W3, and a magnetic repulsive force or a magnetic attractive force is exerted on all four poles of the rotor magnet 14 to effectively use the entire circumference. At the same time, in the outer peripheral side stator 13, X1 and Y1, X2 and Y2, X3 and Y
3, Z4, Z1, Z2, Z3 between X4 and Y4 respectively
A magnetic circuit is constructed by sandwiching the rotor magnet 14
The magnetic repulsive force or the magnetic attractive force is exerted between all four poles of the above, and the inner and outer circumferences of the rotor magnet 14 are effectively used. Therefore, a motor with high driving efficiency and low power consumption can be obtained. Further, the windings can be dispersed to reduce the number of turns of one winding, and the axial thickness can be reduced.

In the above embodiments, the ferromagnetic material was used as the material of the stator, but a so-called coreless motor in which the stator is simply a winding frame using a non-magnetic material may be used. Further, the stator shape has been described in the form in which the salient pole is formed on the outer peripheral side, but it may be one in which the salient pole is formed on the inner peripheral side. In the above embodiment, the rotor magnet 14 is magnetized into four poles in the circumferential direction, and the three-phase DC brushless motor has 12 salient poles, slots, and windings of the inner and outer stators. The number of poles and the number of salient poles, slots and windings of the stator are not limited to those in the above embodiment. An example in which the rotor magnet is magnetized into N poles in the circumferential direction and the salient poles of the stator are composed of 3N in the above embodiment, or the rotor magnet is magnetized into N poles in the circumferential direction, and the salient poles of the stator are 3N / 2
An example is shown in which the number is N (N is an even number of 2 or more).
As specific examples, the former is 4 poles 12 salient poles type, 6 poles 18 salient poles type, 8 poles 24 salient poles type, the latter is 4 poles 6 salient poles type, 6 poles 9 salient poles type, 8 poles 12 salient poles type Etc.

Further, the present embodiment is not limited to three phases, and if the rotating magnetic field generating means is arranged on the inner and outer circumferences so as to sandwich the rotor magnet 14, the rotating magnetic fields on both the inner and outer sides can be used. A highly efficient motor can be obtained.

FIG. 10 is an exploded perspective view showing the structure of an optical scanning device according to another embodiment of the invention. The optical scanning device shown in the figure is of a single beam type. The beam emitted from the light source 101, which is a semiconductor laser, is a divergent light beam, and is coupled to the subsequent optical system by the coupling lens 102. The form of the coupled beam can be a weakly divergent light beam, a weakly converging light beam, or a parallel light beam, depending on the optical characteristics of the optical system thereafter. When the beam that has passed through the coupling lens 102 passes through the aperture of the aperture 103, it is blocked at the peripheral portion of the light beam and shaped into a beam, and enters the cylindrical lens 104 that is a line image forming optical system. The cylindrical lens 104 has a direction with no power directed to the main scanning direction, has positive power in the sub-scanning direction, focuses an incident beam in the sub-scanning direction, and deflects the polygon mirror 105, which is an optical deflector. Focus the light near the reflection surface. The beam reflected by the deflecting / reflecting surface is deflected at a constant angular velocity as the polygon mirror 5 rotates at a constant speed, passes through the two lenses 106 and 107 forming the scanning optical system, and bends the optical path by the bending mirror 108. Then, the light is focused as a light spot on the photoconductive photosensitive member 109 that is the substance of the surface to be scanned, and the surface to be scanned is scanned. The beam is incident on the mirror 110 prior to scanning and is focused on the light receiving element 112 by the lens 111. Based on the output of the light receiving element 112,
The write start timing is determined.

The optical deflector of the above-described embodiment is used as the optical deflector of the optical scanning device. Therefore, since the driving efficiency of the motor of the optical deflector is high and the power consumption is low, the optical scanning device can have a high scanning speed, a high pixel density, and low power consumption.

FIG. 11 is an exploded perspective view showing the structure of a multi-beam optical scanning device according to another embodiment of the invention. In the figure, the same reference numerals as those in FIG. 10 indicate the same components. The light source 101A is a semiconductor laser ray,
The four light emitting sources ch1 to ch4 are arranged in one row at equal intervals. In the present embodiment, the four light emitting sources are arranged in the sub-scanning direction, but the light source 101 which is a semiconductor laser ray.
A may be tilted so that the arrangement direction of the light sources is tilted with respect to the main scanning direction. The four beams emitted from the four light-emitting sources ch1 to ch4 are divergent light beams in which the long axis direction of the elliptical far field pattern is oriented in the main scanning direction as shown in the figure, but are common to the four beams. Coupling lens 1
02, it is coupled to the subsequent optical system. The form of each coupled beam can be a weakly divergent light beam, a weakly converging light beam, or a parallel light beam, depending on the optical characteristics of the optical system thereafter. The four beams that have passed through the coupling lens 102 have an aperture 103.
By the action of the cylindrical lens 104, which is a common line image forming optical system, is focused in the sub-scanning direction, and near the deflection reflection surface of the polygon mirror 105 which is the optical deflector according to the above-described embodiment. Each of them forms a line image that is long in the main scanning direction and is separated from each other in the sub scanning direction to form an image. The four beams deflected at a constant angular velocity by the deflecting / reflecting surface are composed of two lenses 106 and 10 forming a scanning optical system.
7, the light path is bent by the bending mirror 108, and the light is condensed as four light spots separated in the sub-scanning direction on the photoconductor 109 that is the substance of the surface to be scanned, and the four scanning lines on the surface to be scanned are collected. Scan at the same time. One of the beams is incident on the mirror 110 prior to the optical scanning and is focused on the light receiving element 112 by the lens 111. The writing start timing of four beams is determined based on the output of the light receiving element 112. The scanning optical system is an optical system that condenses the four beams deflected simultaneously by the optical deflector 105 into four light spots on the surface to be scanned 109.
6, 107 are included.

Therefore, since the driving efficiency of the motor of the optical deflector is high and the power consumption is small, the multi-beam optical scanning device can have a high scanning speed, a high pixel density, and a low power consumption.

Next, FIG. 12 is a schematic sectional view showing the structure of an image forming apparatus according to another embodiment of the invention. As an example of the image forming apparatus of this embodiment, a tandem type full color laser printer will be shown.

First, on the lower side of the apparatus, there is provided a conveyor belt 2 which is arranged horizontally and conveys a transfer sheet (not shown) fed from the sheet feeding cassette 201. On this conveyor belt 202, a photoconductor 3Y for yellow Y, a photoconductor 3M for magenta M, a photoconductor 3C for cyan C, and a photoconductor 3K for black K are sequentially arranged at equal intervals from the upstream side. There is. In addition, hereinafter, subscripts Y, M, and
C and K are appropriately attached to distinguish them. These photoconductors 3Y, 3M, 3C and 3K are all formed to have the same diameter, and process members are sequentially arranged around them in accordance with the electrophotographic process. Taking the photoconductor 3Y as an example,
Charging charger 4Y, optical scanning device 5Y, developing device 6Y,
A transfer charger 7Y, a cleaning device 8Y, etc. are arranged in that order. The same applies to the other photoconductors 3M, 3C, 3K. That is, in this embodiment, the photoconductors 3Y, 3M,
3C and 3K are irradiation surfaces set for each color, and each of the optical scanning devices 5Y, 5M, 5C and 5K constituting the optical scanning system 231 according to the above embodiment has a one-to-one correspondence.
It is provided in a corresponding relationship.

Around the conveying belt 202, the registration roller 209 is positioned upstream of the photoconductor 5Y.
And the belt charger 210 are provided, and the photoreceptor 5
Belt separation charger 21 should be located downstream of K
1, a static eliminator charger 212, a cleaning device 213, and the like are sequentially provided. Also, the belt separation charger 2
A fixing device 214 is provided on the downstream side in the transport direction with respect to 11, and is connected by a discharge roller 216 toward a discharge tray 215. In such a schematic configuration, for example, in the full color mode (multi-color mode), each photoconductor 3
Optical scanning devices 5Y, 5M, 5 for Y, 3M, 3C, 3K based on image signals of respective colors for Y, M, C, K
An electrostatic latent image is formed by optical scanning of a light beam with C and 5K. These electrostatic latent images are developed with toners of corresponding colors to form toner images, which are electrostatically adsorbed on the conveyance belt 202 and sequentially transferred onto the conveyed transfer paper to be superposed, thereby forming a full-color image. After being fixed as an image, it is ejected. In the black mode (single color mode), the photoconductors 3Y, 3M, 3C and their process members are inactive, and only the photoconductor 3K is operated by the optical scanning device 5K based on the black image signal. An electrostatic latent image is formed by optical scanning of a light beam. This electrostatic latent image is developed with a black toner to become a toner image, which is electrostatically adsorbed on the conveyor belt 2 and transferred onto the conveyed transfer paper to be fixed as a black monochrome image, The paper is ejected.

Therefore, since the driving efficiency of the motor of the optical deflector is high and the power consumption is small, an image forming apparatus can be provided which has high speed output, high image quality, and low power consumption. In the tandem type image forming apparatus, since the optical deflector in which the two-stage rotating polygon mirror is formed in the axial direction is used, the effect of low power consumption according to the present invention is particularly high, but the image forming apparatus is limited to the tandem type. However, similar effects can be obtained in other types of image forming apparatuses.

It is needless to say that the present invention is not limited to the above embodiments, and various modifications and substitutions can be made within the scope of the claims.

[0041]

As described above, the N phase (N
Is an integer greater than or equal to 2), the DC brushless motor has permanent magnets arranged and fixed on the rotor, and winding coils for N phases are arranged and fixed on the inner circumference side and the outer circumference side on which the permanent magnets rotate. Further, it is characterized by having a rotating magnetic field generating means arranged on the inner peripheral side and the outer peripheral side on which the permanent magnet rotates. Therefore, it is possible to provide a highly efficient DC brushless motor by utilizing the magnetic forces on the inner circumference side and the outer circumference side of the permanent magnet fixed to the rotating body to drive the rotating body.

According to another aspect of the present invention, an N-phase (N is an integer of 2 or more) direct current brushless motor has a rotating body in which permanent magnets are arranged and fixed, and an inner peripheral side in which the permanent magnets rotate, and is strong. An inner circumference side stator in which a plurality of winding coils are wound around a stator core made of a magnetic material, and an outer circumference side stator in which a plurality of winding coils are wound around a stator core made of a ferromagnetic material and arranged on the outer circumference side of a permanent magnet. And a rotating magnetic field generating means including. Therefore, since the windings are distributed on the inner peripheral side and the outer peripheral side of the permanent magnet, the number of windings is small, and the axial thickness of the stator including the windings can be reduced.

Further, a holding member for holding the stator on the outer peripheral side is provided, a collar portion is formed extending to the holding member, and a bent portion for elastic fixing is formed on the collar portion. It is possible to provide a DC brushless motor in which the outer peripheral side stator is easily fixed and assembled.

An optical deflector of another invention has a rotating body on which a rotary polygon mirror is formed, a bearing for rotatably supporting the rotating body, and a motor for driving the rotating body. It is the DC brushless motor. Therefore, an optical deflector with high motor efficiency and low power consumption can be provided.

Further, as another invention, a beam from a semiconductor laser is guided to a surface to be scanned through an optical system including an optical deflector to form a light spot, which is deflected by the optical deflector to be scanned. In the optical scanning device that scans the surface with the scanning line, the optical deflector is the optical deflector. Therefore, it is possible to provide an optical scanning device having a high scanning speed, a high pixel density, and low power consumption.

Further, a plurality of beams from the semiconductor laser are guided to the surface to be scanned through an optical system including an optical deflector to form a plurality of light spots separated in the sub-scanning direction,
It is possible to provide a multi-beam type optical scanning device that has a high scanning speed, a high pixel density, and low power consumption by deflecting by a light deflector and scanning a plurality of scanning lines on a surface to be scanned adjacently. .

Furthermore, according to another aspect of the invention, an image forming apparatus that forms a latent image by performing optical scanning on a photosensitive surface of a photosensitive medium by an optical scanning apparatus and visualizes the latent image to obtain an image is The optical scanning device for optically scanning the photosensitive surface of the medium is characterized by using the above optical scanning device. Therefore, high-speed output,
An image forming apparatus with high image quality and low power consumption can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an optical deflector according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a configuration of an optical deflector of this embodiment.

FIG. 3 is a development view showing a method of connecting motor windings in series.

FIG. 4 is a development view showing a series connection method of Y connections of motor windings.

FIG. 5 is a development view showing a parallel connection method of motor windings.

FIG. 6 is a development view showing a parallel connection method of Y connections of motor windings.

FIG. 7 is a sectional view of a linear brushless motor according to another embodiment of the invention.

FIG. 8 is a diagram showing a relationship between generation of a rotating magnetic field due to position detection / energization switching and rotation of a rotor magnet (rotating body) in an embodiment of another invention.

FIG. 9 is a circuit diagram showing a circuit configuration of a drive element of a drive circuit that supplies a current to each phase winding.

FIG. 10 is an exploded perspective view showing a configuration of an optical scanning device according to another embodiment of the invention.

FIG. 11 is an exploded perspective view showing a configuration of a multi-beam optical scanning device according to another embodiment of the invention.

FIG. 12 is a schematic cross-sectional view showing the configuration of an image forming apparatus according to another embodiment of the invention.

[Explanation of sign figure number]

1; housing, 1a; reference surface, 1b; bearing mounting part, 2; fixed shaft, 2a, groove, 3; rotating body, 5; fixed part,
6; Cap member, 7; Stopper, 8; Ring-shaped permanent magnet, 9; First fixed yoke plate, 10; Second fixed yoke plate, 11; Printed circuit board, 12; Inner peripheral side stator, 1
3; outer peripheral side stator, 14; rotor magnet, 15;
Holding member, 15a; Stator holding member, 15b; Slit, 15c; Collar portion, 15d; Bending portion, 16; Rotating sleeve, 17; Peripheral member, 18; Closing member, 19; Rotating portion, 20; Drive circuit, 21; Cover case, 21a;
Mounting reference plane.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H02K 21/12 H04N 1/036 Z 5 H621 H04N 1/036 B41J 3/00 D 1/113 H04N 1/04 104A F term (reference) 2C362 AA04 AA07 AA10 BA04 EA24 2H045 AA13 5C051 AA02 CA07 DC07 DE09 5C072 AA03 BA03 HA02 HA06 HA12 HB15 XA05 5H019 AA04 AA08 AA10 DD01 EE01 5H621 BB01 BB07 BB10 GA01 GA01

Claims (7)

[Claims] 1. In an N-phase (N is an integer of 2 or more) DC brushless motor, a rotating body in which permanent magnets are arranged and fixed, and N on an inner peripheral side and an outer peripheral side on which the permanent magnets rotate, respectively.
A DC brushless motor, comprising: winding magnetic coils for phases; fixed; and rotating magnetic field generating means arranged on an inner peripheral side and an outer peripheral side on which the permanent magnet rotates. 2. In an N-phase (N is an integer of 2 or more) DC brushless motor, a rotating body in which permanent magnets are arranged and fixed, and an inner circumferential side in which the permanent magnets rotate are arranged. An inner circumference side stator having a plurality of winding coils wound around the stator core, and an outer circumference side stator having a plurality of winding coils wound around a stator core made of a ferromagnetic material and arranged on the outer circumference side of the permanent magnet. A DC brushless motor having a rotating magnetic field generating means. 3. A holding member for holding the outer peripheral side stator is provided, a collar portion is formed extending to the holding member, and a bending portion for elastic fixing is formed on the collar portion. DC brushless motor. 4. A rotary body having a rotary polygon mirror formed thereon, a bearing for rotatably supporting the rotary body, and a motor for driving the rotary body, wherein the motor is any one of claims 1 to 3. An optical deflector which is the DC brushless motor described in 1. 5. A beam from a semiconductor laser is guided to a surface to be scanned through an optical system including an optical deflector to form a light spot, which is deflected by the optical deflector to scan the surface to be scanned. An optical scanning device for scanning a line, wherein the optical deflector is the optical deflector according to claim 4. 6. A plurality of beams from the semiconductor laser are guided to a surface to be scanned through an optical system including an optical deflector to form a plurality of light spots separated in a sub-scanning direction,
The optical scanning device according to claim 5, wherein the plurality of scanning lines on the surface to be scanned are adjacently scanned by being deflected by the optical deflector. 7. An image forming apparatus for forming a latent image by performing optical scanning on a photosensitive surface of a photosensitive medium by an optical scanning device and visualizing the latent image to obtain an image, wherein the optical scanning of the photosensitive surface of the photosensitive medium is performed. An image forming apparatus using the optical scanning device according to claim 5 as an optical scanning device.