JPH0812337B2 - Rotating polygon mirror scanning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Use of the Invention] In the present invention, for example, in an image scanning device such as a facsimile machine, a rotary polygon mirror is irradiated with laser light and the reflected light is scanned on a screen. It is a rotating polygon mirror scanning device that rotates at high speed and is suitable for constant speed scanning, and can be used in many other fields such as laser printers, image scanners, and shape measuring machines.

[Technical Background and Conventional Problems] Conventionally, an information laser beam modulated by an information signal is deflected by using a mirror or other deflecting means, and the surface to be scanned on which a photoconductor or the like is scanned to scan the information signal. It is well known to perform recording and read information signals on the surface to be scanned.

There are various types of such an optical deflector, and a rotary polygon mirror scanning device is one of them.

This rotary polygon mirror scanning device has a high deflection speed and can perform continuous light deflection, so that it is possible to record or read information at high speed and high density.

For example, the printing method using a wire dot printer or the like adopted in a personal computer or a word processor has a drawback that the printing speed is slow and high-precision printing is impossible due to the limitation of the number of dots. As a result, there was a drawback that it suffered from noise.

In particular, due to the development of OA equipment, there are many cases where one room has a plurality of OA equipment. When a plurality of wire / dot printers are driven simultaneously with this, the large print sound has a synergistic effect, which is a kind of noise. This is annoying that it gives discomfort not only to those who operate the OA equipment, but also to those around them.

From this reason as well, a rotary polygon mirror scanning device is desired not only for measuring devices but also for laser printers.

However, since the conventional rotary polygon mirror scanning device only attaches the rotary polygon mirror to the rotary shaft of the iron core type motor having the salient pole rotor to rotate the rotary polygon mirror, the concentric rotation polygon mirror is rotated. It was difficult to keep balance, it was difficult to mount the rotary polygon mirror, and it became very large, which made it unsuitable for use in high-density electronic devices these days.

Especially, the radial air gap type iron core motor with salient pole rotor is not suitable for high speed rotation such as several to 100,000 revolutions because it has no coreless structure. It was not suitable for polygon mirror scanning devices.

For example, as these conventional ones, Japanese Patent Application Laid-Open No. 49-9302
No. 7, 57-62751.
Further, in the structure of the both-ends shaft rotation type disclosed in these documents, it is extremely difficult to center the bearing, and therefore the dynamic pressure of the rotary polygon mirror is set to a constant rotation and a high speed so as not to dynamically change. It was difficult to use the air bearing, or even if the air bearing was used, the maximum advantage of using the air bearing could not be fully exhibited.

Further, according to the conventional rotary polygon mirror scanning device using the radial air gap type iron core motor having the salient pole rotor as described above, a large iron core having a large axial length and a large thickness is still used. Since a rotary polygon mirror is simply attached to the rotary shaft of a motor,
In particular, when it is used in high-density packaging electronic devices that are required to be small and lightweight so that it does not become a burden when mounted on a housing, it is heavy, large, expensive, and highly accurate. In addition, there is a drawback that it is not possible to obtain a thin rotary polygonal mirror that is particularly suitable for mass production at low cost, because of its simple thickness structure.

Further, in the conventional rotary polygon mirror scanning device using the iron core motor, since the iron core motor is used, cogging is inevitably generated, and smooth rotation cannot be performed, resulting in uneven rotation. When used in laser printers, etc., there was the drawback that scanning unevenness occurred and screen scanning could not be performed accurately.

Further, in the rotary polygon mirror scanning device, it is necessary to scan the information at a constant speed while rotating at a high speed. However, according to the conventional rotary polygon mirror scanning device, it is difficult to scan the information at a constant speed. For scanning, a tacho generator, an encoder, a resolver or the like must be provided outside the rotary polygon mirror as a large and expensive rotation speed detecting means, and if the above rotation speed detecting means is provided inside, the structure becomes complicated. As a result, the rotary polygon mirror scanning device itself becomes large and expensive, and in addition to the cost, it is a major drawback to apply it to high-density mounting electronic devices that are required to be light, thin, short, and small. Was becoming.

In particular, according to the conventional rotary polygon mirror scanning device, when a rotary polygon mirror with a small number of reflecting surfaces is used for low-cost construction, when it is rotated at high speed,
Due to the large wind loss, there was a drawback that it was very offensive to the ear and produced a large rotating noise. Further, since the windage loss is large, it hinders high-speed rotation, smooth rotation cannot be performed, and uneven scanning occurs as described above, and there is a drawback that accurate screen scanning cannot be performed. Further, since such a defect is caused, there is a drawback that an inexpensive polygonal polygonal rotary polygonal mirror cannot be used as the rotary polygonal mirror and an inexpensive rotary polygonal mirror scanning device cannot be formed.

[Problems of the Invention] The present invention is a compact, flat, lightweight, inexpensive, and suitable for high-speed rotation, which is useful for high-density packaging electronic devices that are required to be light, thin, short, and small. Is a rotary polygon mirror scanning device that is suitable for mass production at a low cost because of its structurally simple structure that enables high-accuracy constant-speed scanning, and it is lightweight and can be mounted on the housing. In order to reduce the added load, even if a rotary polygonal mirror with a light weight and an inexpensive decahedron is used, there is little wind loss,
Another object of the present invention is to obtain a rotary polygon mirror scanning device that rotates smoothly with good efficiency and low rotation noise.

While achieving the above-mentioned problems, the rotary shaft and the rotary polygon mirror can be easily mounted, and when the rotary polygon mirror is mounted, the bearing can be easily centered and the dynamic balance of the rotary polygon mirror can be facilitated. It is an object to obtain a rotary polygon mirror scanning device which can be manufactured easily and can be mass-produced at low cost.

Another issue is to enable the use of dynamic pressure air bearings (dynamic pressure groove bearings) and efficient coreless flat brushless motors to prevent cogging, significant rotational unevenness, smooth rotation, and screen scanning. An object of the present invention is to mass-produce a rotary polygon mirror scanning device which has a high accuracy and a high efficiency, and which has a long life, at low cost.

[Means for Achieving the Object of the Invention] The object of the present invention can be achieved by providing a multi-rotating polygon mirror scanning device composed of the following components.

Constituent elements: A rotary polygon mirror scanning device configured to deflect an incident light beam applied to the rotary polygon mirror [12] by rotating the rotary polygon mirror [12] having at least an outer peripheral portion serving as a polygon mirror. .

It consists of a fixed shaft [3] planted at the fixed side and a rotating shaft [10] that rotates around this fixed shaft [3], and the fixed shaft [3] or the rotating shaft [10] face each other. The dynamic pressure groove bearing is formed by forming the dynamic pressure groove bearing forming groove [3a] on at least one of the surfaces to be formed.

The rotary shaft [3] has a disk-shaped magnet rotor orthogonal to the rotary shaft [3] and a rotary polygon mirror supporting collar [10].
b] is integrally formed.

A rotary polygonal mirror [12] having a polygonal mirror at least in the outer peripheral portion is provided on the upper end surface of the support collar [10b].

2P of N pole and S pole are alternately arranged on the above-mentioned supporting collar [10b].
(P is an integer greater than or equal to 1) A flat magnet rotor [11] having driving magnetic poles [11a] is provided to form a rotor, and the rotor has substantially N-pole and S-pole magnetic poles. A frequency detection multi-pole magnetized magnetic pole [11b] that is magnetized to form multiple poles so as to be arranged alternately at a fine pitch.

Magnetic pole [11a] for driving the magnet rotor [11]
A stator coreless armature [16] is provided at a fixed position opposite to the stator coreless armature [16] via an air gap [17] in the axial direction, and the rotating polygon mirror [12] is rotated by exciting the stator coreless armature [16]. What you are doing.

A comb-teeth conductive pattern [15] for frequency detection is provided on the fixed side, which faces the frequency detecting multi-pole magnetic pole [11b] via an air gap [17] in the axial direction. Rotating polygon mirror [12]
It is used as a signal for the constant speed rotation control of.

Another means for achieving the object is to form the frequency detecting multi-pole magnetic pole [11b] on the magnet rotor [11], or to form the frequency detecting multi-pole magnetic pole [11b] on the magnet rotor [11]. Driving magnetic pole surface magnetized on [11
a], the strong magnetic pole N and the weak magnetic pole N ′ are alternately magnetized to form a multi-pole at a fine pitch. S poles of strong magnetic poles and S'poles of weak magnetic poles are alternately magnetized to form multiple poles at a fine pitch.
Comb-shaped conductive pattern [15] for frequency detection,
The stator coreless armature [16] is formed on a portion of the printed circuit board [7] disposed on the surface facing the magnet rotor [11] facing the frequency detecting multi-pole magnetized magnetic pole [11b], or A windshield [13] having a radius longer than that of the rotary polygon mirror [12] is provided on the upper surface of the rotary polygon mirror [12], and / or the rotary polygon mirror [12] is attached to the rotary shaft [3]. This can be achieved by interposing it between the upper surface of the support collar [10b] and the lower surface of the windshield [13].

[First Embodiment of the Invention] A first embodiment of the present invention will be described with reference to FIGS. 1 to 7.

FIG. 1 is a longitudinal sectional view of the rotary polygon mirror scanning device 1, and FIG. 2 is an exploded perspective view of a main part of FIG. 1, which will be described below mainly with reference to FIGS. 1 and 2.

Reference numeral 1 is a rotary polygon mirror scanning device, 2 is a flat cup type support body having a concave portion 2a (however, not shown in FIG. 2), and 3 is a motion fixed vertically to substantially the center of the support body 2. The screw groove (spiral groove, which is not limited to these, but may be a dynamic pressure groove bearing forming groove of another type, for example, a herringbone groove or the like that can achieve the same purpose) 3a is formed on the outer periphery. It is a fixed shaft formed in.

Although the screw groove 3a is formed on the outer circumference of the fixed shaft 3, it may be formed on the inner circumference of the rotary shaft 10 (cylindrical bearing portion 10a) or on both.

Reference numeral 4 denotes a stator yoke made of a flat annular magnetic body fixedly provided in the upper end opening of the support body 2, for example, a mixture of iron powder and plastic powder compression-molded, or a magnetic material such as iron powder. A desired material can be obtained by using a resin formed of powder.

Reference numeral 5 denotes the support body 2 having a stator yoke 4 and a recess 2a.
An example of effectively using the energization control circuit accommodating cavity 5 in the energization control circuit [may include only the drive circuit] is formed on the lower surface of the stator yoke 4. A board is arranged, electric parts are arranged on the printed board, a cutout such as a through hole is formed in a part of the stator yoke 4, and the cutout is used to form a printed board on the lower surface of the stator yoke 4. Printed circuit board 7
It is a method of electrically connecting with the above, but not limited to this method, there are many methods that can effectively use the void portion 5.

In this way, when the energization control circuit [driving circuit] is built in, the energization control circuit [driving circuit] -integrated rotary polygon mirror scanning device 1 can be compactly configured and used in high-density mounting electronic devices. It is possible to obtain a suitable one.

An air-core type coreless armature coil 6 is provided on the stator yoke 4 (in this case, the stator yoke 4 is preferably insulated and shielded).
As shown in FIG. 3, a coreless armature coil group 6-1, ..., 6-6 for forming a three-phase brushless motor is provided.
Are arranged at equal intervals so as not to be overlapped with each other to form a stator coreless armature 16 for a three-phase brushless motor. This will be described later in detail with reference to FIG.

Reference numeral 7 is a printed circuit board having a through hole in the center and an unillustrated printed wiring conductor portion (printed power distribution pattern) formed by means of etching or the like, and is used for the armature coil group 6 (stator coreless armature 16). It is fixed on the top.

Reference numeral 8 denotes a magnetoelectric conversion element such as a Hall element or a Hall IC used as a position detection element arranged on the lower surface of the printed circuit board 7 and at a position facing the in-frame cavity portion 9 of the armature coil 6. This magnetoelectric conversion element uses three magnetoelectric conversion elements 8-1, ..., 8-3 to form a three-phase brushless motor. The magnetoelectric conversion element 8-1 is an armature coil 6-2. Of the armature coil 6-1 and the magnetoelectric conversion element 8-3 is disposed at the position 9 of the armature coil 6-1. The armature coil 6-3 is arranged at the position of the hollow portion 9 in the frame.

Details of the arrangement positions of the magnetoelectric conversion elements 8-1, ..., 8-3 will be described later.

Reference numeral 10 denotes a cylindrical bearing portion 10a rotatably mounted on the outer peripheral portion of the fixed shaft 3, and a disk-shaped magnet rotor integrally formed so as to extend radially outward in a direction orthogonal to the outer periphery of the bearing portion 10a. It is a rotating shaft that has a flange [10b] for supporting the rotating polygon mirror, and also functions as a bearing.

In addition, in the case of the rotary shaft 10 in this embodiment, the cylindrical bearing portion 10a, the magnet rotor and the rotary polygon mirror support collar 10a are integrally formed.
10 can be obtained in a more optimal way by making various efforts according to the material forming it. For example, the rotation axis
When 10 is made of ceramics, a rotor yaw that closes the magnetic paths of 11 magnet rotors may be provided in the magnet rotor and the rotating polygon mirror support collar 10a. However, when the rotating shaft 10 is made of a magnetic material,
Since the magnet rotor and the rotary polygon mirror support collar 10b also have the function of the rotor yoke for closing the magnetic path of the magnet rotor 11, the rotor yoke is unnecessary.

Therefore, in this embodiment, the rotating shaft 10 made of a magnetic material is used. Therefore, the magnet rotor and the rotary polygon mirror support collar 10b function as a rotor yoke.

In this case, if a surface of the rotary shaft that slides on the fixed shaft 3 is made of ceramics, a more desirable one can be obtained.

Since the fixed shaft 3, the rotary shaft 10, the magnet rotor 10 and the stator coreless armature 16 are used,
The bearing is lightly loaded, and centering of the bearing is not a problem.

Further, since the magnet rotor and the rotary polygon mirror support flange 10b are formed integrally with the rotary shaft 10, it is not necessary to directly attach the rotary polygon mirror 12 to the rotary shaft 10, and the rotary flange 10b is directly or indirectly attached to the upper surface of the support flange 10b. However, since the rotary polygon mirror 12 can be easily arranged and fixed, the rotary polygon mirror 12 can be easily aligned and mounted with a dynamic balance. The magnet rotor 11 can be easily arranged and fixed to the lower surface of the support collar 10b, either directly or indirectly. Therefore, it is extremely necessary to align the magnet rotor 11 and attach the magnet rotor 11 in a dynamic balance. To be easier.

As a result, the rotary polygon mirror scanning device 1 is easily assembled, so that mass production can be performed extremely easily and inexpensively.

11 is a magnetic rotor supporting collar 10b that functions as a rotor yoke, and the magnetic poles of the N pole and the S pole fixed to the lower surface of the magnet rotor supporting collar 10b are alternately arranged for 2P.
(P is an integer greater than or equal to 1), in this example, 8 flat drive magnetic poles 11a having 8 magnetic poles 11a are magnetized to form a flat annular magnet rotor (see FIG. 4). The stator coreless armature 16 which is fixed to the lower surface and has the printed circuit board 7 on the upper surface and which is composed of a group of armature coils 6-1, ..., 6-6 is face-to-face with an air gap 17 in the axial direction between them. I am trying to make a target rotation.

The magnet rotor support collar 10b is provided with a bent portion 10c extending vertically downward on the outer peripheral portion thereof.
Thus, the magnet rotor 11 is held and the generation of leakage magnetic flux generated from the outer peripheral portion of the magnet rotor 11 is prevented as much as possible. The bent portion 10c allows the magnet rotor 1
Positioning 1 is easy and dynamic balance is easy to obtain.

Reference numeral 12 is a rotary polygonal mirror having at least an outer peripheral surface which is a decahedron mirror, which is now integrally formed of aluminum and has a reflecting surface 12a on its outer circumference by a polishing means. It is a quadrangular plate of a four-sided mirror, which is a decosahedral mirror in the plane and has an axially flat surface 12a.
It is fixed to the upper surface of 10b by appropriate means.

In addition, although the reflecting surface 12a and the rotary polygon mirror 12 in this embodiment are made of an integral material, it is not always necessary to do so, and the main body of the rotary polygon mirror 12 made of plastic or the like is used. It goes without saying that the reflecting surface 12a may be formed on the outer peripheral surface by adopting a vapor deposition means such as plating or coating.

Reference numeral 13 designates an air layer located on the reflecting surface 12a as a rotary polygon mirror 1
A disc body for the windshield to rotate and transfer with the rotation of 2.
It is formed to have a longer radius than the rotary polygon mirror 12, and is fixed to the upper surface of the rotary polygon mirror 12 by appropriate means.

Regarding the reason why this windshield disc 13 is necessary,
If the disc body 13 for windshield is a polyhedron in which a large number of reflecting surfaces 12a of the rotating polygon mirror 12 are formed,
Although it hardly causes a problem, it plays an important function when the rotary polygon mirror 12 is a decahedron such as a three-sided mirror or a four-sided mirror in order to form it at a low cost.

That is, when the rotary polygon mirror 12 is a polyhedron, even if the rotary polygon mirror 12 rotates, the wind pressure resistance of the air layer on the reflecting surface 12a is small, and therefore there is almost no air layer on the reflecting surface 12a. Even if the disc body 13 is provided, the wind loss is small and it does not have an important meaning. However, when the rotating polygon mirror 12 is a decimal face such as a tetrahedron as shown in FIG. Since there are many air layers on the reflecting surface 12a and the wind pressure resistance (wind loss) becomes large, when the rotary polygon mirror 12 rotates at high speed in that state, a large rotating noise is generated, and the efficiency is poor due to wind loss. The rotary polygon mirror scanning device 1 has a drawback.

Therefore, when the rotary polygon mirror 12 is a decahedron (mirror), the windshield disc body 13 is formed on the upper surface of the rotary polygon mirror 12 as described above.
Since the air layer in which the escape path is eliminated on the reflecting surface 12a rotates together with the rotation of the rotary polygon mirror 12, the wind pressure is higher than that when the windshield disk 13 is not provided. The resistance is reduced, and the rotating sound generated by the high-speed rotation of the rotating polygon mirror 12 is very small. Therefore, the rotating polygon mirror scanning device 1 has a very small rotating sound (a substantial rotating sound accompanying the rotation, It can be configured as a useful one that rotates with almost no rotating sound). Therefore, the rotary polygon mirror scanning device 1 with high accuracy can be mass-produced at low cost even if the inexpensive polygon polygonal mirror 12 is used.

FIG. 3 is a perspective view for explaining conditions and arrangement method of the six coreless armature coils 6-1, ..., 6-6 group forming the stator coreless armature 16. Is.

As is clear from FIG. 3, the six coreless armature coils 6-1, ..., 6-6 group are air-core type coils formed in a fan frame shape. Armature coil 6-1,
..., 6-6 is a magnet with the opening angle between the effective conductors 6a and 6b contributing to the generated torque in the radial direction (in this case, generally, the center line of the effective conductors 6a, 6b is used as a reference). The rotor 11 is formed to have an opening angle equal to the width of one magnetic pole so that an efficient rotor can be obtained.

The six armature coils 6-1, ..., 6-6 are arranged on the stator yoke 4 (not shown in FIG. 3) at equal intervals so as not to overlap each other. Six coreless armature coils 6-1 on the stator yoke 4,
The stator coreless armature 16 is formed by arranging 6-6, and the upper surface of this stator coreless armature 16 has a structure as shown in FIG. 1, FIG. 2, and FIG. The lower surface of the printed circuit board 7 on which the disk-shaped printed circuit board 7 formed of a magnetic material is arranged and which faces the in-frame cavities 9 of the three armature coils 6-1, 6-2, 6-3 Magnetoelectric conversion elements 8-2, 8-1, and 8-3 are provided in the respective units. For details of the arrangement positions of the magnetoelectric conversion elements 8-2, 8-1, 8-3, see
It will be described later in the figure.

FIG. 4 is a bottom view of the magnet rotor 11. In this embodiment, eight magnetic poles for driving 11a, in which eight magnetic poles of N pole and S pole are alternately formed with equal width and equally spaced, are used in this embodiment. Indicates that

Around the outer periphery of the magnetic pole 11a for driving the magnet rotor 11, about 18 for detecting the rotational speed of the magnet rotor 11 is detected.
The zero pole frequency detecting multi-pole magnetized pole 11b is multi-pole magnetized.

This frequency detecting multi-pole magnetized pole 11b is formed by magnetizing the drive magnetic pole 11a and then magnetizing the multi-pole magnetizing yoke (this has a fine pitch of about 180 turns to form a comb tooth shape). By winding a wire with a thin wire diameter) and applying a voltage to the wire of this magnetizing yoke, approximately 1
Since the 80-pole multi-pole magnetized pole is double magnetized, it can be easily formed by a single magnetizing means.

By using such double magnetizing means,
When the frequency detecting multi-pole magnetic pole 11b is formed on the surface 11a, the strong magnetic pole having a large magnetic force and the weak magnetic pole having a small magnetic force are attached to the N magnetic pole 11a for driving. A magnetized N'pole is formed. The frequency detecting multi-pole magnetized magnetic pole 11b having a weak magnetic force is formed because the magnetic pole is applied by the double magnetizing means in order to weaken the magnetic pole of the N magnetic pole for driving 11a. It is what is formed.
Here, a multi-pole attached magnetic pole 11b for detecting the frequency of the N pole of a strong magnetic pole
Is a magnetic pole that is stronger than the N ′ pole, and it is the driving magnetic pole 11a.
In general, the magnetic pole stronger than the N pole does not occur. Therefore, as is clear from FIG. 7, the N ′ pole in the frequency detecting multi-pole magnetized magnetic pole 11b substantially acts as the S pole.

Similarly, according to the double magnetizing means, the S-pole driving magnetic pole 11
In a, a multi-polarized magnetic pole 11b for frequency detection, which is a strongly magnetized S pole and a weakly magnetized S'pole, is alternately formed. In this case, the S'pole acts as an N pole. Eggplant

Therefore, the N pole of the driving magnetic pole 11a is formed with a frequency detecting multipole magnetic pole 11b in which N poles and N'poles are alternately magnetized at a fine pitch, and the S pole of the driving magnetic pole 11a is formed. The S pole and the S'pole are alternately magnetized at a fine pitch to form a frequency detecting multipole magnetized magnetic pole 11b. Here, as described above, the N ′ pole acts as the S pole, and the S ′ pole acts as the N pole. Therefore, the frequency detection multipole magnetic pole 11b has substantially the N pole and the S pole. The magnetic poles are alternately arranged at a fine pitch, for example, about 180
The frequency detecting multi-pole magnetized magnetic pole 11b is formed on the poles.

Incidentally, as a matter of course, the north pole and the south pole of the driving magnetic pole 11a are
At the boundary of the poles, the N of the multi-pole magnetic pole 11b for frequency detection is used.
If the poles, N'poles, S poles, and S'poles are not suitable, it is necessary to take design considerations such as deleting the required magnetic poles in this portion or forming them with a phase shift.

Since the frequency detecting multi-pole magnetized magnetic pole 11b is formed as described above, the magnetic flux density waveform 18 in the gap 17 formed by the magnet rotor 11 is as shown in FIG.

As shown in FIG. 7, the magnetic flux density waveform 19 formed by the driving magnetic pole 11a is added to the frequency detecting multi-pole magnetic pole 11b.
Since the magnetic flux density waveform 20 formed by is overlapped, the magnetic flux density waveform 19 formed by the driving magnetic pole 11a is
Since the magnetic flux density waveform 20 is superposed on the peaks or valleys of the above, a fine uneven waveform is formed.

Here, if only this fine uneven magnetic flux density waveform 20 is taken out independently, it becomes the same as the frequency signal obtained from the frequency generator. Therefore, such a signal is obtained by the comb-shaped frequency detecting conductive pattern 15 described later. By taking it out, the rotation speed of the magnet rotor 11 can be easily detected.

Therefore, the rotary polygon mirror scanning device 1 can be controlled at a constant speed,
The information can be scanned with constant quality and speed.

FIG. 5 shows the six coreless armature coils 6-1 forming the magnet rotor 11 and the stator coreless armature 16.
.., 6-6 is a development view, and the magnetic-electric conversion element 8-1, ...
., 8-3 is the arrangement position.

As is clear from FIG. 5 (see also FIG. 3), the armature coils 6-1, ..., 6-6 that form the stator coreless armature 16 of the three-phase brushless motor generate torque in the radial direction. The open angle between the effective conductors 6a and 6b that contributes to the magnetic field is approximately 2n−1 of one magnetic pole width of the driving magnetic pole 11a of the magnet rotor 11.
In this embodiment, n = 1 is selected, and an air-core type having an open angle width substantially equal to one magnetic pole width of the driving magnetic pole 11a of the magnet rotor 11, that is, an open angle width of 45 degrees. And each armature coil 6-1, ..., 6-6 group is
As shown in FIGS. 3 and 5, they are arranged at equal intervals so that they do not overlap each other.

The armature coils 6-1, ..., 6-6 are each composed of two groups of two armature coils 6 that are electrically in phase and are 180 degrees out of phase in the circumferential direction. A stator coreless armature 16 for forming a three-phase brushless motor by forming a set is formed.

That is, the U-phase armature coils 6-1 and 6-4, the V-phase armature coils 6-2 and 6-4, and the W-phase armature coils 6-3 and 6-6 form a set of each phase. Is forming. One magnetoelectric conversion element 8 is provided for each armature coil 6 group of each phase group.

The magnetoelectric conversion elements 8-1, ..., 8-3 are housed in the frame cavities 9 of the armature coils 6-2, 6-1, 6-3, respectively. The reason for doing this is shown below.

The U-phase armature coils 6-1 and 6-4, the V-phase armature coils 6-2 and 6-4, and the W-phase armature coils 6-3 and 6-
6 are arranged so as to be sequentially shifted by 60 degrees in conduction angle.

Here, only three magnetic-electric conversion elements 8-1, ..., 8-3 are provided in order to configure a three-phase brushless motor.
Since the armature coils 6-1, ..., 6-6 are provided with the magnetoelectric conversion elements 8 respectively, the cost is high. Therefore, the armature coils 6 in the in-phase position have a common magnetoelectric conversion element. This is because the element 8 is also used so that it can be constructed at a low cost.

Magnetoelectric conversion elements 8-1, ..., 8-3 which are position detection elements
The preferred position for arranging the effective conductor is 6a or 6b.
It is a position facing.

However, if the armature coils 6-4, 6-5, 6-6 are located
If U, V, W are selected, the printed circuit board 7 is present in such a position, so that the arrangement of the magnetoelectric conversion element 8 becomes troublesome, and even if the surface of the printed circuit board 7 is magnetized. When the conversion element 8 is provided, the length of the air gap 17 between the magnet rotor 11 and the stator yoke 4 increases by the thickness of the element 8, and a large torque cannot be obtained, and an efficient three-phase brushless motor is provided. Will not be obtained.

Therefore, the effective conductor portion 6b of the armature coil 6-4, the effective conductor portion 6a of the armature coil 6-5, and the positions U, V, W on the effective conductor portion 6a of the armature coil 6-6 are arranged. Magnetoelectric conversion element 8
-1,8-2,8-3 and armature coil 6 in the same position
-2,6-1,6-3 are arranged at the positions U ', V', W'in the frame cavity 9 to prevent the length of the air gap 17 from increasing and to provide an efficient three-phase I am trying to get a brushless motor.

FIG. 6 shows the printed circuit board 7 shown in FIGS.
FIG. A frequency detecting conductive pattern 15 for detecting the rotational speed of a toothed tooth is formed on the surface of the printed board 7 facing the frequency detecting multi-pole magnetized magnetic pole 11b of the magnet rotor 11, as shown in FIG. Has been done. The pitch of the power generating line elements 15a in the radial direction of the conductive pattern 15 is the same as one pitch of the multipole magnetized magnetic poles 11b for frequency generator detection, as shown in FIG. For example, when a group of every other power generation line element 15a in the radial direction of the conductive pattern 15 faces the N pole or the S pole of the frequency detection multi-pole magnetized magnetic pole 11b, the power generation line element 15a group between them is present. Faces the N ′ pole or the S ′ pole. As a result, an electromotive force in the same direction corresponding to the frequency detecting multi-pole magnetized magnetic pole 11b is generated in each power generating line element 15a group, and the same direction corresponding to the rotation speed of the magnet rotor 11 is output from the output terminal (not shown) of the conductive pattern 15. Electromotive force is generated, and a detection output having a frequency corresponding to the rotation speed of the magnet rotor 11 is obtained from an output terminal (not shown) of the conductive pattern 15.

The pulsed magnetic flux generated by the frequency detecting multi-pole magnetized magnetic pole 11b appears intermittently, but since the conductive pattern 15 is formed on the entire circumference as shown in FIG. 6, the detection output is obtained as a continuous wave. .

Even if the frequency detecting multi-pole magnetized magnetic pole 11b has pitch irregularity, the pitch irregularities are averaged by the power generating line elements 15a of the plurality of conductive patterns 15, and a constant frequency is detected when the rotation speed of the magnet rotor 11 is constant. Output is obtained. The fluctuation of the rotation speed of the magnet rotor 11 is extracted as the frequency modulation component of the detection output.

FIG. 8 is a longitudinal sectional view of a rotary polygon mirror scanning device 1'showing a second embodiment of the present invention. Although this rotary polygon mirror scanning device 1'is almost the same as that shown in the first embodiment. , The axial thickness of the drive circuit accommodating space 5'is increased, and a plurality of printed circuit boards equipped with control circuits, drive circuits, etc. can be arranged in parallel in the space 5 '. The rotary polygon mirror scanning device 1'is designed to be stable and highly accurate.

FIG. 9 is a vertical sectional view of a rotary polygon mirror scanning device 1 ″ showing a third embodiment of the present invention, in which the void portions 5 and 5 ′ shown in FIGS. By providing the components such as the less armature 16, the magnet rotor 11, and the rotary polygon mirror 12 at the lower position, the rotary polygon mirror scanning device 1 ″ is stabilized and a thin flat plate in the axial direction is provided. It made it possible to obtain.

In this rotary polygon mirror scanning device 1 ″, the rotary shaft 10 and the fixed shaft 3 are formed so as to project above the rotary polygon mirror 12. This is the rotary polygon mirror scanning device 1,
In order to make the rotary polygon mirror scanning device 1 ″ even flatter because of the balance with 1 ′, the rotary shaft 10
This can be achieved by using, for example, those having a short length in the axial direction so as not to largely project above the rotary polygon mirror 12. Reference numeral 14 indicates a thrust cap.

[Operation of the Invention] According to the rotary polygon mirror scanning device 1, 1 ′, 1 ″ shown in the present invention, the magnetoelectric conversion element 8 is the driving magnetic pole of the magnet rotor 11.
When the N pole and S pole of 11a are detected, the signal is transmitted to a drive circuit (not shown), and a current in an appropriate direction is applied to the armature coil group 6 to excite it, which results in Fleming's left-hand rule. Accordingly, the magnet rotor 11 rotates in a predetermined direction.

When the magnet rotor 11 rotates, the frequency detecting multi-pole magnetized magnetic pole 11b formed on the magnet rotor 11 rotates relative to the conductive pattern 15. Therefore, the rotation speed detecting frequency corresponding to the rotation speed of the magnet rotor 11 is the above-mentioned. Since it can be taken out from a terminal (not shown) of the conductive pattern 15, this frequency signal is F / V (frequency / voltage) converted by the rotation speed control circuit, converted into a speed voltage, and fed back based on this voltage to the armature. The magnet rotor 11 can be rotated at a constant rotation speed by controlling the energization of the coil 6 group.

Therefore, the rotary polygon mirror 12 fixedly mounted on the magnet rotor supporting collar 10a also rotates at a constant speed, and the information laser light emitted to the reflecting surface 12a of the polygon mirror 12 becomes a deflected reflected light to cause a screen reflection. Scan at a constant speed.

[Advantages of the Invention] According to the present invention, without using a large and expensive encoder or tacho-generator as in the prior art, and without requiring a particularly large space as in the prior art,
With a simple structure consisting of a conductive pattern and multi-pole magnetic poles for frequency detection, and without requiring a particular space, the rotation speed detection mechanism can be reasonably built into the rotary polygon mirror scanning device, so a lighter, thinner, smaller size is required. Compact, flat, lightweight, high-speed rotating and accurate constant-speed rotating, which is useful for high-density mounted electronic devices, and therefore a rotary polygon mirror scanning device that can accurately scan the screen at a constant speed is extremely inexpensive. Mass production can be configured.

Furthermore, in the present invention, since the magnet rotor and the rotary polygon mirror support flange are integrally formed with the rotary shaft that rotates the outer periphery of the fixed shaft, the alignment and mounting of the rotary polygon mirror and the magnet rotor are very easy. It is simple and the structure is simple, and the rotary polygon mirror scanning device can be easily assembled and can be mass-produced at low cost.

Further, according to the rotary polygon mirror scanning device of the present invention, even if an inexpensive rotary polygonal mirror of a decahedron is used, the wind noise and the wind noise are hardly generated, so that the rotation noise is small and therefore the efficiency is good. It is very easy and cheap to use a rotary polygon mirror scanning device that is small, flat, lightweight, high-speed rotation, accurate at a constant speed, and can scan the screen with low sound, which is useful for high-density packaging electronic equipment that requires miniaturization. Mass production can be configured.

Moreover, since it is lightweight, the load applied to the housing when it is attached to the housing can be reduced, so that it can be used as a device that is useful for various high-density electronic devices.

In addition, since it is possible to use a dynamic pressure air bearing (dynamic pressure groove bearing) and an efficient coreless flat brushless motor, it is possible to prevent cogging, remarkable rotation unevenness, smooth high speed rotation, and accuracy. A high-speed rotary polygon mirror scanning device that enables good high-speed screen scanning and has good efficiency can be mass-produced at low cost.

The stator coreless armature in the above embodiment is formed by the air-core type coreless armature coil group, but such a stator coreless armature is formed by a sheet coil or a print coil formed by means such as etching. Is also good.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a rotary polygon mirror scanning device showing a first embodiment of the present invention, and FIG. 2 is an exploded perspective view of a main part of the same, and FIG.
Figure is a perspective view of a stator coreless armature consisting of a coreless armature coil group. Figure 4 is a bottom view of a magnet rotor.
FIG. 5 is a development view of a magnet rotor and a stator coreless armature including a coreless armature coil group, FIG. 6 is a plan view of a printed circuit board on which a conductive pattern for frequency detection is formed, and FIG. 7 is formed by the magnet rotor. FIG. 8 is an explanatory view of a magnetic flux density waveform, FIG. 8 is a vertical sectional view of a rotary polygon mirror scanning device showing a second embodiment of the present invention, and FIG. 9 is a vertical section of a rotary polygon mirror scanning device showing a third embodiment of the present invention. It is a side view. [Explanation of symbols] 1,1 ′, 1 ″ …… Rotating polygon mirror scanner, 2 …… Flat cup type stator yoke support, 2a …… Recess, 3 …… Fixed shaft, 3a ……
Screw groove (spiral groove), 4 ... Stator yoke,
5,5 '... Vacation space for driving circuit, 6,6-1, ..., 6-6
...... Coreless armature coil, 6a, 6b ...... Effective conductor portion that contributes to generated torque, 7 ...... Printed circuit board, 8,8-1, ..., 8-
3 ... Magnetoelectric conversion element, 9 ... In-frame cavity, 10 ... Rotation axis, 10
a …… Cylindrical bearing part, 10b …… Magnet rotor and rotary polygon mirror support collar, 10c …… Bent part, 11 …… Magnet rotor,
11a …… Drive magnetic pole, 11b …… Multi-pole magnetic pole for frequency detection, 12
...... Rotating polygon mirror, 12a ...... Reflecting surface, 13 ...... Disc body for windshield, 14
...... Thrust cap, 15 …… Frequency detecting conductive pattern, 16 …… Stator coreless armature, 17 …… Void, 18 ……
Magnetic flux density waveform in the air gap 17, 19 ... Magnetic flux density waveform formed by the driving magnetic pole 11a, 20 ... Magnetic flux density waveform formed by the frequency detecting multi-pole magnetic pole 11b.

Claims (6)

[Claims] 1. A rotary polygon mirror scanning device comprising the following components. A rotary polygon mirror scanning device configured to deflect an incident light beam applied to the rotary polygon mirror [12] by rotating the rotary polygon mirror [12] having at least an outer peripheral portion of the polygon mirror. It consists of a fixed shaft [3] planted at the fixed side and a rotating shaft [10] that rotates around this fixed shaft [3], and the fixed shaft [3] or the rotating shaft [10] face each other. The dynamic pressure group bearing is formed by forming the dynamic pressure group bearing forming groove [3a] on at least one of the surfaces to be formed. The rotary shaft [10] has a disk-shaped magnet rotor orthogonal to the rotary shaft [10] and a rotary polygon mirror supporting collar [10].
b] is integrally formed. A rotary polygonal mirror [12] having a polygonal mirror at least in the outer peripheral portion is provided on the upper end surface of the support collar [10b]. 2P of N pole and S pole are alternately arranged on the above-mentioned supporting collar [10b].
(P is an integer greater than or equal to 1) A flat magnet rotor [11] having driving magnetic poles [11a] is provided to form a rotor, and the rotor has substantially N-pole and S-pole magnetic poles. A frequency detection multi-pole magnetized magnetic pole [11b] that is magnetized to form multiple poles so as to be arranged alternately at a fine pitch. Magnetic pole [11a] for driving the magnet rotor [11]
A stator coreless armature [16] is provided at a fixed position opposite to the stator coreless armature [16] via an air gap [17] in the axial direction, and the rotating polygon mirror [12] is rotated by exciting the stator coreless armature [16]. What you are doing. A comb-teeth conductive pattern [15] for frequency detection is provided on the fixed side, which faces the frequency detecting multi-pole magnetic pole [11b] via an air gap [17] in the axial direction. Rotating polygon mirror [12]
It is used as a signal for the constant speed rotation control of. 2. The frequency detecting multi-pole magnetized magnetic pole [11b] comprises:
The rotary polygon mirror scanning device according to claim (1), which is formed on the magnet rotor [11]. 3. The frequency detecting multi-pole magnetized magnetic pole [11b] comprises:
It is formed on the driving magnetic pole surface [11a] magnetized on the magnet rotor [11], and the driving magnetic pole of N pole is composed of a strong magnetic pole N and a weak magnetic pole N'alternatingly with a fine pitch. It is characterized in that it is magnetized to have multiple poles, and that the S pole having a strong magnetic pole and the S ′ pole having a weak magnetic pole are alternately magnetized to form a multipole at a fine pitch. The rotary polygon mirror scanning device according to claim (1). 4. The comb-teeth-shaped conductive pattern [15] for frequency detection is provided on a printed circuit board [7] disposed on a surface of the stator coreless armature [16] facing the magnet rotor [11]. The rotary polygon mirror scanning device according to any one of claims (1) to (3), characterized in that the rotary polygon mirror scanning device is formed in a portion facing the frequency detecting multipole magnetized magnetic pole [11b]. 5. The windshield [13] having a radius larger than the radius of the rotary polygon mirror [12] on the upper surface of the rotary polygon mirror [12].
Claims (1), characterized in that
The rotary polygon mirror scanning device according to any one of items (4) to (4). 6. The rotary polygon mirror [12] is interposed between the upper surface of the support collar [10b] of the rotary shaft [3] and the lower surface of the windshield [13], the patent The rotary polygon mirror scanning device according to claim (5).