JPS61132920A - Optical deflector - Google Patents

Abstract

PURPOSE:To make a device small-size and light-weight and to reduce the cost by forming a ring-shaped rotor magnet constituting a rotor into a polyhedron with a revolving shaft as a center and attaching polygon mirrors to this polyhedron as one body. CONSTITUTION:The first magnetic iron plate 21 constituting a magnetic circuit and a coil substrate 22 are fixed to the first enclosure 11 of an optical deflector, and a coreless flat coil 23, etc. are arranged on them to constitute a fixed armature. A ring-shaped rotor magnet 34 constituting the rotor or a flange 32 is formed into a polygonal polyhedron with a revolving shaft 31 as the center, and polygon mirrors 35 are attached to this polyhedron as one body. A laser light is made incident on the window part 11b of the enclosure 11. Thus, dimensions in the axial direction of the revolving shaft 31 are shortened, and the device is small-sized and light-weight to reduce the cost.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. This invention is suitable for use in laser printers, digital copying machines, facsimile machines, and other types of optical information processing devices equipped with laser deflectors.

This is an ultra-compact optical deflector that uses a coreless flat brushless motor system.In particular, by integrally configuring the mirror and rotor magnet, the axial dimension of the rotation axis of the optical deflector body can be shortened, making it more compact. The present invention relates to a lightweight and inexpensive optical deflector that eliminates mounting constraints and enables cost reduction by reducing the number of parts.

Five plates of rice! Conventionally, various optical devices such as laser deflectors for laser printers, laser deflectors for digital copying machines, laser deflectors for facsimiles, and barcode readers for POS terminals use laser beams for reading and writing. For deflection, an optical deflector using a polygon mirror (multifaceted II) is used.

In general, the inner rotor type, outer rotor type, and coreless flat type are known as brushless motor types used in this type of optical deflector.

In terms of cost, these brushless motor systems are ranked in the following order: coreless flat type, outer rotor type, and inner rotor type, with the coreless flat brushless motor type being the most advantageous.

Furthermore, since this coreless flat type has less cogging and large inertia, it is superior to other types in terms of rotational unevenness and jitter characteristics at low speed rotations of about 4°,000 rpm, for example. Furthermore, it has many advantages such as light weight and low noise.

Figures 11 (1) and (2) are diagrams showing an example of the main part configuration of a conventional coreless flat brushless motor type optical deflector, where Figure (1) is a longitudinal cross-sectional view and Figure (2) is a longitudinal cross-sectional view. FIG. In the drawing, 41 is a first casing, 41a is a window portion opened in a part thereof, 42 is a second casing, 43 is a first magnetic iron plate, 44 is a coil substrate, and 45 is a coreless flat coil. , 46 is a circuit board, 47a and 47b are rotor speed detection elements, 51 is a rotating shaft, 52 is a flange, 53 is a second magnetic iron plate, 54 is a ring-shaped rotor magnet, 55 is a polygon mirror, and 56a and 56b are bearings. Show part.

The configuration of the optical deflector shown in FIGS. 11 (1) and (2) is as follows.

It is as follows.

First, in the fixed armature, a first magnetic iron plate 43 forming a magnetic circuit and a coil substrate 44 on which coreless flat coils 45 are arranged are fixed inside a first casing 41.

The coil board 44 is a so-called printed board, and although not particularly shown, a wiring pattern for wiring these components is formed on the board.

A ring-shaped rotor magnet 54, which is axially opposed to the coreless flat coil 45 shown in FIG. 11 (1) constituting the fixed armature with an appropriate gap therebetween, is magnetized into multiple poles, and a magnetic circuit. A second magnetic iron plate 53. Furthermore, a polygon mirror 55 for laser deflection is attached to the flange 5.
2, and furthermore, the flange 52 is fixed to the rotating shaft 5.
1 to form a rotor assembly.

Bearing portions 56a and 56b are lightly press-fitted into the rotating shaft 51 of the rotor assembly constructed in this way, respectively.

Note that the circuit board 46 on which the rotor speed detection elements 47a and 47b are attached is connected to the polygon mirror 5 of the rotor assembly.
5, and the second casing 42 is attached.

The bearing parts 56a and 56b of the rotor assembly are connected to the first housing 4.
1. They are each supported by the second casing 42.

Therefore, the rotor assembly has a bearing portion 56a.

It can be rotated around 56°b.

As shown in FIGS. 11 (1) and (2), in the conventional coreless flat brushless motor type optical deflector, a fixed armature having a plurality of coreless flat coils 45 and a multi-pole magnetized Ring-shaped rotor magnet 54 and rotating shaft 51
A rotor having a polygon mirror 55 having a mirror surface parallel to that formed therein, and a housing 41 . It is composed of.

In this optical deflector, the window portion 41 provided in the first housing 41
a forms part of the optical path from the outside.

That is, in order to deflect external laser light by the polygon mirror 55, the laser light source → mirror surface (reflection)
The optical path acts to deflect the laser beam in the desired direction.

Furthermore, in order to rotate the rotor at a constant speed, it is necessary to detect the rotational speed of the rotor and perform constant speed control on the target rotational speed.

For this purpose, the circuit board 4 is used as a rotor speed detection means.
6, rotor speed detection elements 47a and 47b are arranged. The speed detection element 47a is a light emitting element such as an LED, and 47b is a light receiving element such as a phototransistor.

Using the detection signal from this speed detection means, constant speed control of the rotor to which the polygon mirror 55 is fixed is performed.6 By the way, in the conventional coreless flat brushless motor type optical deflector, the ring-shaped rotor magnet 54 and the polygon mirror 55 are stacked in the axial direction of the rotating shaft, and are integrally formed with the flange 52 provided on the rotating shaft 51.

Therefore, the axial dimension of the rotation axis of the optical deflector main body inevitably becomes large, and the mounting position is restricted.

On top of that, a ring-shaped rotor magnet 54 and a polygon mirror 5 are placed.
5 as separate parts, there are disadvantages such as not only increased weight but also increased cost.

Therefore, in the optical deflector of the present invention, such inconveniences in the conventional coreless flat brushless motor type optical deflector are solved, and the radial dimension of the optical deflector is shortened to make it smaller and lighter. By the way.

The purpose is to reduce costs by removing mounting constraints and reducing the number of component parts.

In order to solve this problem, the optical deflector of the present invention uses a fixed armature consisting of a first magnetic iron plate and a plurality of coreless flat coils, a ring-shaped rotor magnet, and a magnetic circuit to solve these problems. The radial dimension of the optical deflector has been shortened to make it more compact, and accurate speed control has been made possible by eliminating speed detection errors caused by surface deflection of the polygon mirror caused by rotor eccentricity. The purpose is to

For this purpose, the optical deflector of the present invention includes a fixed armature having a plurality of coreless flat coils, a multi-pole magnetized ring-shaped rotor magnet, and a mirror surface parallel to the rotation axis. In a flat brushless motor type optical deflector comprising a rotor having a polygon mirror, and a casing having a part provided with an affected area for guiding laser light from the outside to the mirror surface of the polygon mirror, the polygon mirror When the radius of the circumscribed circle is rl and the radius of the inscribed circle is rl, rl(r3<
A light-emitting element and a light-receiving element constituting the speed detection means are respectively arranged at a position of radius r3 corresponding to rl and on both sides of the non-mirror surface of the polygon mirror.

Next, an embodiment of the optical deflector of the present invention will be described in detail with reference to one drawing.

FIG. 1 is a longitudinal sectional view showing the configuration of essential parts of an embodiment of the optical deflector of the present invention.
is the first casing, lla is a mechanical part forming a part of the labyrinth mechanism for preventing scattering of bearing oil, llb is a window portion opened in the part, 12 is the second casing, and 12a is A mechanical part forming a part of the labyrinth mechanism for preventing scattering of bearing oil, 13 a light emitting element forming a speed detection means, 14 a preload spring, 21 a first magnetic iron plate, 22 a coil substrate, and 23 a coreless A flat coil, 24 a light receiving element constituting a speed detection means, 31 a rotating shaft, 32 a flange, 32a and 32b a mechanical part constituting a part of a labyrinth mechanism for preventing scattering of bearing oil, and 33 a second 34 is a ring-shaped rotor magnet, 35 is a polygon mirror, and 36a and 36b are bearing parts.

As shown in FIG. 1, a first casing 11 made of a lightweight non-magnetic material has a polygon mirror 3 provided therein.
A partially opened affected area 11b is provided for entering the laser beam.

Further, a mechanism portion 11a that constitutes a part of a labyrinth mechanism for preventing scattering of bearing oil is provided at the portion where the bearing portion 36b is attached, and is also used together with the bearing portion 36b to prevent the scattering of bearing oil and grease. construct a labyrinth mechanism for

First, the configuration of the fixed armature will be explained. Note that the members constituting the fixed armature are numbered in the 20s from 21 to 24.

A first magnetic iron plate 21 for forming a magnetic circuit and a coil board 22 are fixed inside the first casing 11, and a coreless flat coil 23. Light receiving element 24 for speed detection. and fixing the arrangement of the necessary circuit components. In this way, the fixed armature is constructed.

The following FIGS. 2(1) and (2) are structural diagrams showing the detailed structure of the coil substrate 22 of the optical deflector of the present invention shown in FIG. 1. FIG. 1(1) is a plan view, and FIG. 2) is a longitudinal sectional view. The reference numerals in the drawings are the same as in FIG. 1.

In addition, 22a to 22f are holes for mounting the coil board 22;
4a is a slit plate arranged close to the light receiving element 24;
25a to 25c represent rotor position detection elements, ICI and IC2 are integrated parts, R1 to R3 are resistors, and C is a capacitor.

The coil board 22 is a so-called printed circuit board.

A wiring pattern for wiring these components is formed on the board.

Further, the light receiving element 24 for speed detection and the slit plate 24a are arranged on the coil substrate 22 at a position with a diameter r3.

Next, the rotor assembly will be described. The members constituting the rotor assembly are numbered in the 30s from 31 to 35.

Figures 3 (1) and (2) are structural diagrams showing the detailed configuration of the rotor assembly of the optical deflector of the present invention shown in Figure 1; Figure 1 (1) is a plan view, and Figure (2) is a vertical sectional view.

Reference numbers in the drawings are the same as in FIG. 1, and 32a
32c indicates a hole in which the flange 32 is attached.

As shown in FIGS. 3(1) and (2), the rotor assembly of the optical deflector of the present invention includes a rotation shaft 31, a flange 32,
Second magnetic iron plate 33, ring-shaped rotor magnet 34. and a polygon mirror 35.

That is, while maintaining an appropriate gap with the coreless flat coil 23 that constitutes a part of the fixed armature shown in FIG.

A ring-shaped rotor magnet 34 facing in the axial direction and magnetized into multiple poles, a second magnetic iron plate 33 for forming a magnetic circuit, and a polygon mirror 35 for laser deflection are integrated into the flange 32. and then flange 3
2 is integrally fixed to the rotating shaft 31 to constitute a rotor assembly.

As shown in FIGS. 3(1) and (2), if the polygon mirror 35 for laser deflection is integrally fixed to the ring-shaped rotor magnet 34 and the flange 32, the optical deflector can be The dimensions are also reduced. Therefore, even if the light emitting element 13 and the light receiving element 24 constituting the speed detecting means are arranged on both sides of the polygon mirror 35, the optical deflector can be made smaller than the conventional optical deflector.

The flange 32 is provided with mechanical parts 32a and 32b that form part of a labyrinth mechanism for preventing the bearing oil from scattering so that the bearing oil, grease, etc. do not scatter.

This mechanism portion 32a, together with the mechanism portion 12a that constitutes a part of the labyrinth mechanism of the second housing 12, similarly
The mechanism portion 32b, together with the mechanism portion 11a that constitutes a part of the labyrinth mechanism of the first casing 11, respectively constitute a labyrinth mechanism for preventing scattering of bearing oil.

The bearing portions 36a and 36b are lightly press-fitted into the rotating shaft 31 of the rotor assembly constructed in this way, respectively.

These bearing parts 36a, 36b are supported by the first housing 11 and the second housing 12, respectively, so that the rotor assembly rotates around the bearing parts 36a, 36b.

In the optical deflector shown as an example in FIG. 1, the excitation phase is detected in the 8-pole, 3-phase, 6-coil motor section by the output signal of the rotor position detector composed of rotor position detection elements 25a to 25c. When switching and energizing the six coils in sequence, the rotor is rotated at a rotational speed compared to the supply voltage of the motor, according to Fleming's left-hand rule (so-called Bli rule). In addition, when explaining using the Bli law, F=
The force of Bit is the force acting on the coil, but since the optical deflector of this invention uses a brushless motor in which the coil is fixed and the rotor magnet rotates, the rotation direction of the rotor magnet is Bli The direction is the opposite of the rule.

FIG. 4 is a layout diagram showing the relationship between the coils of the 8-pole, 3-phase, 6-coil motor shown in FIG. 2 and the arrangement positions of the rotor position detection elements 25a to 25c.

Reference numerals in the drawings are the same as in FIGS. 1 and 2.

FIG. 5 is a circuit diagram showing an example of the coil connection and drive circuit of the 8-pole, 3-phase, 6-coil motor shown in FIG. ~Q6 indicates a transistor.

Figure 6 applies the principle of the brushless motor in which the rotor magnet in the 8-pole, 3-phase, 6-coil motor section shown in Figure 1 and the rotating magnetic field and evening magnet rotate.
Since the rotor is a magnet, the direction of the rotational force acting on the rotor is opposite to this Bli law.

FIG. 6 is a layout diagram showing the relationship between the coils of the 8-pole, 3-phase, 6-coil motor shown in FIG. 2 and the arrangement positions of the rotor position detection elements 26a to 26c.

The symbols in the drawings are the same as in FIGS. 1 and 2,
Further, Cp indicates a pitch between coils, and CP indicates a coil pitch.

FIG. 7 is a circuit diagram showing an example of the coil connection and drive circuit of the 8-pole, 3-phase, 6-coil motor shown in FIG. Q6 indicates a transistor.

FIG. 8 is a time chart showing an example of rotor magnets, rotating magnetic fields, and coil positions in the 8-pole, 3-phase, 6-coil motor section shown in FIG.

In the time chart of the drawing, the vertical axis shows the magnetic flux density, and the horizontal axis shows the rotation angle.

As already explained, in order to rotate the rotor at a constant speed, it is necessary to detect the speed of the rotor and perform constant speed control with respect to the target rotation speed.

In the optical deflector of this invention, when the polygon mirror rotates, this mirror functions as a shutter.

The light from the light emitting element 14 is turned on and off, and the light from the light receiving element 2
given to 4.

For this purpose, an LED or the like is placed at a position on the second housing 12, for example, at a position having a radius r3 that satisfies the relationship r2 (r3 < rt) with respect to the radius rt of the circumscribed circle of the mirror and the radius r2 of its inscribed circle. One or more light-emitting elements 14 are fixed with mutually changing phases, and on opposing coil substrates 22,
Similarly, one or more light receiving elements 24 such as phototransistors are arranged with different phases from each other.

When one speed detection means is arranged.

The light from one light emitting element 14 is turned off at the corner of the polygon mirror 35, and the level of the speed detection signal generated from the light receiving element 24 is changed.

The following Figure 9 is a layout diagram for explaining the arrangement of a polygon mirror and two speed detection means in the case of an 8-pole, 3-phase, 6-coil motor. show.

In this FIG. 9, the number of mirror surfaces of the polygon mirror is N=8 (
), and the case where the number of light receiving elements P=4 (pieces) is shown.

FIG. 10 is a time chart showing an example of the speed detection signal generated from the two speed detection means shown in FIG. 9. T in the drawing represents the speed detection signal generated from one speed detection means One period of , and to indicate the time width of the speed detection signal.

As shown in FIG. 1O, when two speed detection means are used, the outputs of the light receiving elements p1 and p2 are combined to generate a frequency signal corresponding to the speed of the rotor.

Also, when it is necessary to change the on/off duty ratio of the frequency signal for reasons related to the control system, or for the purpose of preventing noise due to light diffraction of the light emitting element.

Between the light emitting element 14 and the light receiving element 24, there are
As shown in 2), a slit plate 25 is provided.

By appropriately selecting the width and mounting position of this slit plate 25, a pulse signal of the required time width to can be obtained.

Here, the number of mirror surfaces or the number of angles of the polygonal rotor magnet (in the case of the embodiment shown in FIG. 1, the number of mirror surfaces as a polygon mirror) is N, and the number of light receiving elements 24 is P. Then, the Pnth light receiving element is arranged in a positional relationship according to the 9th order equation with respect to the first light receiving element.

Here, Pn is 1, 2, 3.・・・・・・PHere,
An example of the arrangement when N=8 (corners) and p=4 (pieces) is shown in a table as follows.

In the speed detection means, the basic arrangement method is to arrange the same number of light emitting elements 14 on the circuit board 13 at a position opposite to the light receiving element 24 or on the second casing 12. When arranged according to (1), since the arrangement angle is small, the number of light receiving elements 24 can be smaller than the number of light receiving elements 24.

By using the speed detection signal generated in this way, the rotor can be controlled at a constant speed. In this regard,
Since this is the same as the conventional control method, a detailed explanation will not be provided.

As explained above in detail, the optical deflector of the present invention includes a fixed armature consisting of a first magnetic iron plate and a plurality of coreless flat coils, a ring-shaped rotor magnet, and a second armature for forming a magnetic circuit. A ring-shaped rotor constituting the rotor in an optical deflector comprising a rotor consisting of a magnetic iron plate and a polygon mirror for laser deflection, and a casing surrounding the rotor and having a window portion through which the laser beam passes. The magnet is a polygon having a polygonal shape centered on its rotation axis, and a polygon mirror is formed on the polygon.

Therefore, according to the optical deflector of the present invention, the axial dimension of the rotation axis of the optical deflector main body is shortened.

It is smaller, lighter, and easier to implement.

This is also advantageous for rotation control.

Furthermore, since the rotor magnet and polygon mirror are integrally constructed, the number of parts is reduced and one assembly process is simplified, which is advantageous in terms of cost.

Many excellent effects can be obtained.

[Brief explanation of drawings]

12LJ- is an embodiment of the optical deflector of this invention,
A vertical cross-sectional view showing the structure of the main part, 2 1a:m is the first
FIG. 1 is a configuration diagram showing a detailed configuration of the coil substrate 22 of the optical deflector of the present invention shown in the figure, where FIG. (1) is a plan view, FIG. FIG. 1 is a block diagram showing the main structure of an example of a rotor assembly of the optical deflector of the present invention. FIG. (1) is a plan view, FIG. (2) is a cross-sectional view, and Regarding the optical deflector of the present invention shown in FIG. This is a configuration diagram showing the main structure of an example of the flange.
) is a plan view, FIG. (1) is a plan view, Figure (2) is a cross-sectional view, and l main 1 is the 8-pole 3 shown in Figure 2.
Phase 6 coil motor coil and rotor position detection element 2
6a to 26c, a layout diagram showing the relationship with the arrangement position of 6a to 26c, t+ is a circuit diagram showing an example of the coil connection and drive circuit of the 8-pole 3-phase 6-coil motor shown in Fig. 1, and UJL is the circuit diagram shown in Fig. 1. 8. A time chart showing an example of the rotor magnet, rotating magnetic field, and coil position in a motor section with 3 phases and 6 coils, t
ti is a layout diagram to explain the arrangement of the polygon mirror and two speed detection means in the case of an 8-pole, 3-phase, 6-coil motor, and JLLQJL is from the two speed detection means shown in Figure 9. A time chart showing an example of a generated speed detection signal, 1-L U%- is a diagram showing an example of the main part configuration of a conventional coreless flat brushless motor type optical deflector, and Figure 1 (1) is a longitudinal section. Top view Figure 1 (2) is a plan view. In the drawings, 11 is a first casing, 12 is a second casing,
13 is a circuit board, 14 is a light emitting element of a speed detector, 16 is a lid member, 21 is a first magnetic iron plate, 22 is a coil board, 2
3 is a coreless flat coil. 24 is a light receiving element of the speed detector, 31 is a rotating shaft, 32 is a flange, 33 is a second magnetic iron plate, 34 is a ring-shaped rotor magnet, 35 is a mirror segment, and 36a and 36b are bearing parts. God 6 M ″vCC Shizume 7 fig. 9 fig. 10 fig. ke 11 fig.

Claims (1)

[Claims] A rotor consisting of a fixed armature consisting of a first magnetic iron plate and a plurality of coreless flat coils, a ring-shaped rotor magnet, a second magnetic iron plate for forming a magnetic circuit, a polygon mirror for laser deflection, and a flange. In the optical deflector, the ring-shaped rotor magnet or flange constituting the rotor has a polygonal shape centered on its rotation axis. 1. An optical deflector, characterized in that it is a polyhedron having the shape of , and a polygon mirror is formed on the polyhedron.