JPH0449338B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an optical deflection motor in which air bearing is performed by dynamic pressure air flow on a cylindrical rotating shaft equipped with a rotor and an optical deflection mirror. Regarding.

[Technical background of the invention and its problems]

Conventionally, in optical deflection motors, a horizontal plane is formed on a motor base, a fixed shaft is erected thereon, air grooves for radial load are formed at the base end and the distal end of this fixed shaft, respectively, and the motor base is A cylindrical rotating shaft with a thrust load air groove formed in the horizontal plane of the shaft and a rotor and a light deflection mirror for laser beam deflection on the outer periphery is fitted to the fixed shaft, so that when the rotating shaft rotates, , a dynamic pressure air flow is formed between the lower end surface of the rotating shaft and the horizontal surface of the motor base to receive the thrust load of the rotating shaft, and also between the inner circumferential surface of the rotating shaft and the outer circumferential surface of the fixed shaft. A configuration is provided in which a dynamic pressure air flow is formed and the radial load of the rotating shaft is received here.

By the way, high machining accuracy is normally required when forming a dynamic pressure air flow, but in the conventional method described above, in addition to the space between the outer circumferential surface of the fixed shaft and the inner circumferential surface of the rotating shaft, Since the configuration creates a dynamic pressure air flow between the lower end surface and the horizontal surface of the motor base, there are many parts that require high machining accuracy, and machining takes time. Since the horizontal plane of the machine requires extremely high levelness with respect to the vertical fixed axis, it is necessary to pay sufficient consideration to its machining, which has the drawback of requiring time and effort to manufacture and resulting in high costs. .
There is also a structure in which the thrust load is received by a magnetic bearing instead of a hydrodynamic air bearing, but this is inferior to the hydrodynamic air bearing in terms of stability in supporting the rotating shaft.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and its object is to provide a system in which a rotating shaft including a rotor and an optical deflection mirror is supported by a hydrodynamic air bearing, in which a portion where a hydrodynamic air flow is formed is provided. It is an object of the present invention to provide an optical deflection motor which can achieve high rotational accuracy, and which can also facilitate manufacturing and reduce manufacturing man-hours.

[Summary of the invention]

In the present invention, a radial load air groove and a thrust load air groove are formed on a rotating shaft that is installed upright on a motor base, and the rotating shaft is fitted to this fixed shaft, so that the radial load and thrust load of the rotating shaft are fixed. In addition, one of the rotor and the optical deflection mirror is positioned near the maximum air pressure generation area in the air groove part for the radial load, and the air groove part for the thrust load is configured so that it can receive the air pressure at one location. It is characterized in that the other is located near the location where the maximum air pressure is generated.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a short cylindrical motor base with a bottom, and a mounting boss 2 is formed at the center of the bottom wall of the motor base, and a fixed shaft 3 is fitted and fixed to the mounting boss 2 and stands upright. . A radial load air groove 4 is formed at the base end (lower end) of the fixed shaft 3, and as shown in the figure, the radial load air groove 4 has a spiral groove with an upward left-hand shape in the lower half. It consists of a spiral groove that slopes upward to the right in the upper half, forming a so-called herringbone shape. Furthermore, from the middle part to the tip (upper end) of this fixed shaft 3, there is a thrust load air groove 5.
is formed, and this thrust load air groove 5
consists of a left-up spiral groove. A stator 6 is attached to the inner surface of the peripheral wall of the motor base 1, and is composed of a stator core 7, a stator winding 8, and a winding holding bobbin 9, and the lower end of the winding holding bobbin 9. is fixed to the bottom wall of the motor base 1 via screws 10. Reference numeral 11 denotes a cylindrical rotating shaft, which is rotatably fitted to the fixed shaft 3 with an extremely small gap in between, and a plug 13 having an air vent hole 12 is fitted into its upper opening. It is worn.

Here, to describe in advance the dynamic pressure airflow characteristics when the rotating shaft 11 is rotated, the rotating shaft 11
When is rotated, a dynamic pressure air flow is formed between it and the fixed shaft 3 by the radial load air groove 4 and the thrust load air groove 5, and at this time the air flows as indicated by the arrow in Figure 1. As shown, the plug 1 flows from the base end side of the fixed shaft 3 between the rotating shaft 11 and the fixed shaft 3.
It comes to flow out from the air hole 12 of No.3. Also, at this time, air pressure is generated between the fixed shaft 3 and the rotating shaft 11 due to the dynamic pressure air flow, and in particular, air pressure whose main component is in the radial direction is generated in the radial load air groove 4 portion. Air groove 5 for thrust load
Air pressure that acts mainly in the thrust direction but also in the radial direction is generated in this part. Such air pressure characteristics are shown in graphs a and b in FIG. The pneumatic characteristics of the thrust component in the radial direction are shown by the line Ps. Therefore, as can be seen from graph a, the maximum air pressure in the radial load air groove 4 portion occurs at a portion A midway between the upper and lower sides of the formation area of the radial load air groove 4, and the thrust load air groove 4 The maximum air pressure in a portion is generated at a portion B near the upper end of the region where the thrust load air groove 5 is formed.

Now, 14 is a rotor, which is constructed by attaching a rotor core 16 and a magnet 17 to a holder 15, and the rotor 14 is connected to a rotating shaft 11.
It is fitted and fixed to the outer circumferential surface of the radial load air groove 4 so as to be located near the maximum air pressure generation area, that is, the area A, particularly above the area A. Reference numeral 18 denotes a light deflection mirror having a polygonal outer periphery, which is attached to the outer circumferential surface of the rotating shaft 11 by a screw ring 21 while being sandwiched from above and below by a lower holder 19 and an upper holder 20. The mounting position thereof is determined to be near the portion where the maximum air pressure is generated in the thrust load air groove 5 portion, that is, the portion B, particularly near the bottom of the portion B. Therefore, the rotator 14 and the light deflection mirror body 18 are located between the portion A and the portion B. Further, in the rotating shaft 11, its lower end (one end) projects downward from the rotor 14, and its upper end (other end) projects upward from the light deflection mirror 18, and both of these projecting parts 11a and 11b are formed so that their outer diameters are the same. Reference numeral 22 denotes a drive control circuit board, on which a well-known position detection element and a power transistor (both not shown) are arranged. Therefore, the drive control circuit board 22
is attached to the lower part of the winding holding bobbin 9 via a pin 23 so as to be located near the end of the fixed shaft 3 on the air inflow side, that is, the base end.

In the above configuration, when the rotor 14 rotates together with the rotating shaft 11, a dynamic pressure air flow is formed between the fixed shaft 3 and the rotating shaft 11, as described above. The rotary shaft 11 is supported in a non-contact manner in the radial direction and the thrust direction by the air pressure described above.

According to this embodiment as described above, the following effects can be obtained. That is, in addition to the radial load air groove 4, a thrust load air groove 5 is formed on the circumferential surface of the fixed shaft 3, so that the rotating shaft 11 can be moved not only in the radial direction but also in the thrust direction only on the circumferential surface of the fixed shaft 3. Therefore, the machining to obtain the dynamic pressure air flow is done on the circumferential surface of the fixed shaft 3 and the rotating shaft 1.
1, and the lower end surface of the rotating shaft 11 and the motor base also require the above-mentioned machining, which simplifies manufacturing and reduces manufacturing man-hours, resulting in lower costs. can be achieved. Moreover, the rotor 14 having a large mass on the rotating shaft 11
Since the optical deflection mirror body 18 is located near the maximum air pressure generation area in the radial load air groove 4 section and the maximum air pressure generation area in the radial direction in the thrust load air groove 5 section, the rotation of the rotation shaft 11 is prevented. is stable, high rotation accuracy can be obtained, and so-called shaft runout does not occur. in this case,
Since the rotor 14 and the optical deflection mirror 18 are particularly located between the two maximum air pressure generating parts,
The supporting state of the rotating shaft 11 is further stabilized, and extremely high rotation accuracy can be obtained overall. Further, a drive control circuit board 22 is provided at the base end of the fixed shaft 3 on the air inflow side.
2 can be cooled by air flowing between the fixed shaft 3 and the rotating shaft 11, so there is no need for a special air cooling means, and the structure is simplified and the drive control circuit board 22 can be cooled. It is possible. Furthermore, the rotation axis 1
1 is made to protrude from the rotor 14 and the light deflection mirror body 18, respectively, and both protruding parts 11a and 11b
Since the outer diameters of the two are the same, the rotating shaft 11, the rotor 14, and the optical deflection mirror 1 can be easily assembled before assembly.
When adjusting the balance of an integral body consisting of 8 with a balancing machine, the rotating shaft 11 can be supported by both of its protrusions 11a and 11b.In particular, since the upper end of the rotating shaft 11 is protruded, the protruding Part 1
The plug body 13 can be press-fitted into the plug body 1b, and therefore, changes in the dimensions of the rotating shaft 11 due to the influence of the press-fitting can be prevented from reaching the portion of the optical deflection mirror 18 of the rotating shaft 11. The optical deflection mirror 18, which requires very high accuracy of roundness and concentricity, can maintain its original setting accuracy.

In the above embodiment, the rotor 14 is provided near the maximum air pressure generation site in the radial load air groove 4 section, and the optical deflection mirror 18 is provided near the maximum air pressure generation site in the thrust load air groove 5 section. However, the optical deflection mirror 18 is provided near the maximum air generation area in the radial load air groove 4 portion, and the rotor 14 is provided together with the stator 6 near the maximum air generation area in the thrust load air groove 5 portion. It is also possible to achieve the desired purpose in this case as well.

Furthermore, in the above embodiment, the radial load air groove was formed in a herringbone shape, but the shape is not limited to this, and in the above embodiment, the rotor 14 of the rotating shaft 11 is Although a so-called inner rotor type motor arranged on the inside is illustrated, this may be applied to an outer rotor type motor in which the rotor 14 is arranged outside the stator 6.
Further, in the above embodiments, a brushless motor is illustrated, but the present invention is not limited to this.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications within the scope of the invention.

〔Effect of the invention〕

As is clear from the above description, since the present invention can support the rotating shaft only on the peripheral surface of the fixed shaft, high-precision machining for forming dynamic pressure airflow is unnecessary for the lower end surface of the rotating shaft and the motor base. This makes manufacturing easy and reduces the number of manufacturing steps.Moreover, since the rotor and optical deflection mirror are supported near the area where the maximum air pressure of the dynamic air flow is generated, high rotational accuracy can be achieved. It is possible to obtain excellent effects such as being able to obtain the following properties and also to prevent shaft runout.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional side view, and FIG. 2 is an air pressure characteristic diagram for explaining air pressure distribution characteristics in relation to a fixed shaft. In the figure, 1 is the motor base, 3 is the fixed shaft, 4 is the air groove for radial load, 5 is the air groove for thrust load,
6 is a stator, 11 is a rotating shaft, 13 is a stopper, 14 is a rotor, 18 is a light deflection mirror, and 22 is a drive control circuit board.

Claims (1)

[Scope of Claims] 1. A fixed shaft that is erected on the base of the motor and has a herringbone-shaped radial load air groove and a thrust load air groove consisting of a spiral groove, and a cylinder fitted to the fixed shaft. a rotating shaft formed in the shape of a rotating shaft; and a rotating shaft formed at the upper part of the rotating shaft when the rotating shaft is in a rotating state, between the rotating shaft and the fixed shaft when the rotating shaft is rotating, and above the fixed shaft together with the thrust load air groove. an air vent hole section that performs a fluid bearing so that a dynamic pressure air flow is formed in a direction along the direction of the rotating shaft so that the rotating shaft is supported in a non-contact state in the radial and thrust directions; a light deflection mirror body formed in a shape, and a rotor attached to the rotation shaft; An optical deflection motor characterized in that the motor is disposed between and near a maximum air pressure generating portion in the radial load air groove portion and a maximum air pressure generating portion in the thrust load air groove portion. 2. The rotor is located near the maximum air pressure generation portion in the radial load air groove portion,
2. The optical deflection motor according to claim 1, wherein the optical deflection mirror is located near a maximum air pressure generating portion in the thrust load air groove portion. 3. The rotor is located near the maximum air pressure generation portion in the thrust load air groove portion,
2. The optical deflection motor according to claim 1, wherein the optical deflection mirror is located near a maximum air pressure generating portion in the radial load air groove portion.