JPS59178936A - Rotary polyphase mirror scanner - Google Patents

Abstract

PURPOSE:To reduce the size of a scanner by mounting a polygonal mirror and N-poles and S-poles of flat plates on a rotary shaft, varying the magnetic force at fine pitch at the end as a rotor and opposing a plurality of coils not superposed in flat plate shape as stator. CONSTITUTION:A stationary shaft 3 is stool on a flat cut-shaped support 2, and a rotational shaft 10 made of magnetic material is rotatably supported. A polygonal mirror 12 is engaged with the collar 10b integral with the shaft 10 at the top of the shaft 10. The collar 10b forms a belt part 10c extended vertically, and contains field magnets 11 disposed annularly alternately at N-poles and S- poles. The periphery of the magnet 11 is strongly and weakly magnetized at fine pitch to form a rotor. A magnetic yoke 4, a plurality of not superposed coils 6, and a printed board 7 are provided at the hole of the support 2, and opposed to the magnet 11. A plurality of position detectors 8 mounted on the board 7 detect the rotating speed from the variation in the magnetic force of the magnets 11 to control the speed. In this manner, the scanner having small size and accurate operation is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating polygon mirror scanning device that irradiates a rotating polygon mirror with laser light and scans a screen with the reflected light in an image recording device such as a facsimile.

Conventionally, an information laser beam modulated by an information signal is polarized using a mirror or other polarizing means, and the information signal is recorded by scanning the scanned surface on which a photoreceptor is arranged.
It is well known to read information on a scanned surface. There are various types of such optical polarizers, one of which is a rotating polygon scanning device. This rotating polygon mirror scanning device has a high polarization speed and can perform continuous optical photometry, so it is possible to record or read out high-density information at high speed.

However, the conventional rotating polygon mirror scanning device uses a cylindrical motor with a salient pole rotor, so although it is a device that requires a small size, it has a heavy weight and is large, low cost, and has high performance. I couldn't get anything. Particularly thin ones could not be obtained. These are disclosed in JP-A-49-93027 and JP-A-57-62751.

In addition, in the structure of the shaft rotating type shown at both ends, it is extremely difficult to center the bearing, so an air bearing is used to rotate the rotating polygon mirror at a constant rate without dynamic fluctuation. That was impossible.

Furthermore, it is difficult for conventional rotating polygon mirror scanning devices to scan at a constant rotation speed, and a large and expensive tachometer generator or encoder must be used as means for detecting the N rotation speed. The scanning device itself was also large and expensive.

The present invention has been made based on the above circumstances, and is equipped with a rotational speed detection means, so that the heavy chain is light, small, and inexpensive.
This was developed with the aim of obtaining a rotating polygon mirror scanning device that has high performance, is thin in the axial direction, and is capable of scanning at a constant rotational speed.

The present invention will be described in detail below with reference to the drawings.

A first embodiment of the present invention will be described with reference to FIGS. 1 to 7.

Figure 1 is a vertical cross-sectional view of the rotating polygon mirror scanning device, and Figure 2 is a vertical cross-sectional view of the rotating polygon mirror scanning device.
FIG.

Mainly referring to FIGS. 1 and 2, 1 is a rotating polygon mirror scanning device showing a first embodiment of the present invention, 2 is a flat cup-shaped support (not shown in FIG. 2), and 3 is the above-mentioned A fixed shaft having a screw groove fixed perpendicularly to the center of the support 2; 4 is a flat annular magnetic yoke fixed to the upper opening of the support 2; It is made by compression molding a mixed powder with plastic powder. 5
6 is an air gap, a drive circuit housing portion, and 6 is an armature coil wound into a frame shape, which is arranged on the magnetic yoke 4 in an appropriate number. This is explained in FIG.

Reference numeral 7 denotes a printed circuit board having a through hole in the center and a printed wiring conductor section (not shown), and is fixed on the upper surface of the armature coil 6. Reference numeral 8 denotes a Hall element or Hall I used as a position detection element, which is disposed on the lower surface of the printed circuit board 7 and at a position facing the cavity 9 within the frame of the armature coil 6.
It is a magnetoelectric conversion element such as C. The arrangement position of the magnetoelectric transducer 8 will be described later. Reference numeral 10 denotes a cylindrical bearing portion 10a rotatably mounted on the outer periphery of three fixed shafts, and the bearing portion. Further, a collar 10b formed of a magnetic yoke for closing the magnetic path of a field magnet H1, which will be described later, functions as a support member for a rotating polygon mirror 12, which will be described later. 11 is a 2P (P is a positive integer greater than or equal to 1) pole annular field magnet (see Figure 4), which is fixed to the lower surface of the collar 10 b, which is a magnetic yoke. ) is fixed on the lower surface of the above-mentioned tsuba J (lb) and faces a group of armature coils having a printed circuit board 7 on the upper surface. ．(
A field magnet 11 is provided at this bent portion 10c.
I try to keep it. Reference numeral 12 denotes a rotating polygon mirror, which has a rectangular shape flat in the axial direction and has four reflecting surfaces 12a around its periphery, and is fixed on the upper surface of the collar 10b.

13 is rotating polygon mirror 12? It is a windshield disc body with a radius longer than the radius, and is fixed on the upper surface of the rotating polygon mirror 12. This windshield disc body 13 is unnecessary when the rotating polygon i12 is a polyhedron, but is necessary when the rotating polygon mirror 12 is a small face, such as a three-sided mirror or a four-sided mirror. This is the result. That is, when the rotating polygon mirror 12 is a polyhedron, there is little wind pressure resistance even if the offshore polygon bell 12 rotates, so if the windshield disc body 13 is provided, there will be no place for the wind to escape, and the rotation will be reversed. A loud rotation sound is generated due to the 120 rotations of the polygon mirror. On the other hand, when the rotating polygonal broom 112 is an oligohedron such as a tetrahedron, its reflective surface 1.
2a has a large wind pressure resistance, so if the rotating polygon mirror 12 continues to rotate at high speed, it will generate a loud rotation sound.

Therefore, when the rotating polygon mirror 2 is an oligohedron, the windshield disk 13 is provided (and the wind on the reflecting surface 12a is
Since there is no escape route due to the disk body 13, the wind rotates together with the reflecting surface 12a as the rotating polygon mirror 12 rotates. For this reason, the wind pressure resistance is reduced compared to the case where the windshield disc body 13 is not provided, so there is an effect that the noise caused by the rotation of the rotary polygon mirror 12 is greatly reduced.

Figure 3 shows the conditions and arrangement method of the 6 groups of armature coils.
FIG.

As is clear from this Fig. 3, six armature coils 6-
1. . . . , 6-6 is wound into a fan frame shape, and includes six armature coils 6-1. ...
. . , 6-6 are arranged at equal intervals so as not to overlap each other. Three armature coils 6-1,...
In the frame cavity 9 of 6-3, magnetoelectric conversion elements 8-1, 8
-2.8-3 is installed.

This will be explained in detail in Figure 5.

A circular printed circuit board 7 is fixed to the upper surface of a stake electric element consisting of six groups of armature coils, and a comb-shaped conductive setan J5 is formed on the surface of this printed circuit board 70 for detecting the rotational quality of the rotor. (See Figure 6). The printed circuit board 7 and the field magnet 11 face each other with a small gap in between. As shown in FIG. 4, the driving magnetic pole 11a of the field magnet 11 is N,
It is magnetized into eight poles having S magnetic poles alternately spaced at equal intervals, and around 180 frequency detection magnetic poles 11b for detecting the rotor rotational speed are formed around the eight poles. N and S are more strongly magnetized than N' and S'. The frequency detection magnetic pole 11b has strongly magnetized portions (N) arranged at fine pitches along the circumferential direction on the outer circumference of the driving magnetic pole 11a.

It is formed by double magnetization means so as to alternately have weakly magnetized parts (N', S' poles). N' pole is S
The 8' pole functions as a north pole.

Therefore, the magnetic flux density waveform in the gap formed by the field magnet 11 is as shown in FIG.

As shown in FIG. 7, the magnetic flux density waveform formed by the driving magnetic pole 11a has a frequency detection magnetic field: $11b.
Since the magnetic flux density waveforms formed by the driving magnetic poles 11a are superimposed, a fine uneven waveform is formed at the peaks or valleys of the magnetic flux density waveform formed by the driving magnetic pole 11a.

Figure 5 is a developed view of the field magnet and armature coil.
The location of the magnetoelectric transducer is shown in the table below.

As is clear from FIG. 5, in the armature coil 6, the opening angle between the conductor portions 6a and 6b, which contributes to the generated torque in the radial direction, is approximately 2n1 of the magnetic pole width of the field magnet J1. (However, n double) times, that is, it is wound with an opening angle width that is approximately equal to the magnetic pole width of the first field magnet.
As shown in FIGS. 3 and 5, the six groups of root coils are arranged at regular intervals so as not to overlap each other. The 6 groups of armature coils are made up of 3 groups, each consisting of 2 groups of 6 armature filters that are electrically in phase and 180 degrees out of phase in the circumferential direction.
A review has been established. That is, armature coils 6-1 and 6-4.6
-2 and 6-5.6-3 and 6-6 form each set. One magnetoelectric conversion element 8 is provided in each group of 6 armature coils. The magnetoelectric conversion element 8 is the armature coil 6
It is stored and arranged in the frame cavity 9 of.

With reference to FIG. 5, armature coil 6-4.6-5.6-
Positions U, V, on the conductor portion 6a that contribute to the generated torque of 6.
The magnetoelectric transducer 8 disposed on W is placed at the symbol Z, U', W' position of the frame hollow part 9 of the armature coils 6-1', 6-2, 6-3, which are located at the same position. It is located in

FIG. 6 is a plan view of the printed circuit board 7 shown in FIG. f. Field magnet 110 frequency detection magnetic pole on the surface of the printed circuit board 70 1.1. In the part facing b, as shown in FIG. 6, 51z < 1. A tooth-shaped conductive ξ turn 15 is formed. The pitch of this conductive turn J5 is the same as the pitch of the frequency detection magnet % 1.1b shown in FIG. When every other line segment group in the radial direction of the conductive ξ-turn 15 faces, for example, N or S of the frequency detection magnetic pole, the line segment group between these faces N' or N'. This allows each line segment to have a magnetic pole for frequency detection], ]
An electromotive force is generated in the same direction according to the rotation speed of b, and conductivity
A detection output of a frequency corresponding to the rotational speed of the rotor is obtained from an output terminal (not shown) of the rotor 15.

Incidentally, the wave-like rupture caused by the frequency detection magnetic pole 11b appears intermittently, but since the conductive ξ turf 15 is formed around the entire circumference as shown in FIG. 6, the detection output is a continuous wave. can get. Further, even if there is pitch unevenness in the frequency detection magnetic poles 1] and b, the pitch unevenness is averaged out by the plurality of conductive ξ turns 15, and when the rotational speed of the rotor is constant, a detection output of a constant frequency can be obtained. A variation in the rotor rotational speed is extracted as a frequency modulation component of the detection output.

FIG. 8 shows a rotating polygon mirror scanning device 1' showing a second embodiment of the present invention. By increasing the thickness width of the gap 5 shown in FIG. It is possible to store a plurality of printed substrates in parallel and to stabilize the device 1'.

FIG. 9 is a rotating polygonal ψ scanning device showing a third embodiment of the present invention]
At θ1", the 4V gap 5 shown in FIGS. 14 is a thrust carriage, which is formed so that the thickness of the device 1'' becomes thinner and thinner.

Since the present invention has the above configuration, when the electric shock conversion element 8 detects the N or S magnetic pole of the field magnet The field magnet) 11 rotates in an appropriate direction 4).

In addition, the rotation speed can be controlled by allowing the year number from the frequency generator formed by the frequency detection magnetic poles + and +b and the conductive turf 15 to be fed back to the rotation speed control circuit. Can scan at high speed.

Therefore, the rotating polygon mirror J2 fixed to the rotating shaft 10 rotates, and the information laser beam irradiated to the reflective surface 21a of the polygon mirror J2 scans the screen at a constant speed with polarized reflected light. do.

As is clear from the above description and description, the rotating polygon mirror scanning device of the present invention uses a disk-type brushless motor suitable for mass production, so it can be expected to have a long life, and is small, superimposed, light, thin, and inexpensive. You can get something. Also, it would be easy to obtain a constant rotation speed with little fluctuation.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing the first embodiment of the present invention, Fig. 2 is an assembly diagram of the same, Fig. 3 shows an F phase diagram showing an example of the arrangement method of an armature coil group, and Fig. 4 Figure 5 is a plan view of a field magnet with magnetic poles for frequency detection shown as an example, Figure 5 is a developed view of the field magnet and armature coil group, and Figure 6 is a print forming an 8-electron ξ turn. Top view of the board,
7 is a diagram of the magnetic flux density waveform formed by the field magnet of FIG. 5, FIG. 8 is a longitudinal sectional view showing the second embodiment of the present invention, and FIG.
The figure is a longitudinal sectional view showing a third embodiment of the present invention. 1.1. ', 1''...Rotating multi-sided bell scanning device, 2...
Flat cup type support, 3... Fixed shaft, 4... Magnetic yoke, 5... Air gap (driving circuit storage part), 6... Armature coil, 7... Printed circuit board, 8... ...Position detection element (magnetoelectric conversion, 12...rotary polyhedral 8.13...
・Windshield disc body, 14...Thrust cap, 15・
...Conductive pattern. Patent applicant Yoshi Takahashi it<+ (472,'
,゛. 1st Figure 6 Chrysanthemum 7 Figure 8V 萬90

Claims (1)

[Claims] 1. In a rotating polygon scanning device in which an incident light beam is polarized by a rotating polygon mirror, a 2P mirror having a polygon mirror and flat annular N and S magnetic poles alternately on the rotation axis. (P is a positive integer of 1 or more) A field having a driving magnetic pole and a frequency detection magnetic pole magnetized so that the driving magnetic pole has strong magnetized parts and weakly magnetized parts alternately at a fine pitch. A stator armature with a magnetic magnet attached thereto and a comb-like conductive ξ turn for frequency detection on the part facing the frequency detection magnetic pole is disposed on the fixed side, and a rotational position detection means is provided. Features a rotating polygon mirror scanning device. 2. The rotating polygon mirror scanning device according to claim 1, wherein the rotating shaft is a bearing provided on the outer periphery of the stationary side. 3. The rotation according to claim 1 or 2, wherein the member for closing the magnetic path of the field magnet and the supporting member of the rotating polygon mirror are integrally formed. Polygon mirror scanning device. 4. The rotating polygon mirror scanning device according to any one of claims 1 to 3, wherein the rotating polygon mirror has a windshield disk on its upper part. 5. The armature coil forming the stator armature is characterized in that the conductor portion that contributes to the generated torque is wound so that the opening angle width is approximately equal to the magnetic pole width of the field magnet. A rotating polygon mirror scanning device according to any one of claims 1 to 4. 6. The rotating polygon mirror scanning device according to any one of claims 1 to 5, wherein the armature coil groups are arranged at regular intervals so as not to overlap each other. 7. The rotating polygon mirror scanning device according to any one of claims 1 to 6, characterized in that the rotational position detection means is a magnetoelectric conversion element. 8. The rotating polygon mirror scanning device according to claim 7, wherein one magnetoelectric conversion element is provided for each of several armature coil groups that are electrically in phase. 9. The above-mentioned magnetoelectric transducer is disposed in a hollow part within the frame of the armature coil, which is located at the same position as the conductor part that contributes to the generated torque of the armature coil. 9. The rotating polygon mirror scanning device according to item 8.