JP2009157311A - Bearing mechanism for motor, optical scanning apparatus having bearing mechanism for motor, and optical reader having optical scanning apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a bearing mechanism for a motor, which can make the motor small in size and can simultaneously achieve higher rotation speed; an optical scanning apparatus using the bearing mechanism; and an optical reader. <P>SOLUTION: The bearing mechanism for the motor includes a second spring 110 for imparting a second pressure value weaker than a first pressure value of a first spring to first and second inner rings 52 and 62 between a pair of opposing surfaces of first and second roller bearings 50 and 60. Accordingly, even when the first pressure value is made large, a pressure value applied to first and second rolling elements 56 and 66 can be kept substantially constant if the second pressure value is made large. Therefore, static frictional force of the first inner ring 52 and a locator member 90, and a static frictional force of the second inner ring 62 and the first spring 100 can be made larger, thereby: achieving higher rotation speed of the motor; and preventing the outer external shape of the motor from being made large. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a bearing mechanism of a motor, an optical scanning device having the bearing mechanism of the motor, and an optical reading device having the optical scanning device.

2. Description of the Related Art Conventionally, an optical scanning device that rotates a polygon mirror with a motor to scan a laser beam in an optical reading device that reads a barcode or a two-dimensional code is known. (For example, Patent Document 1)

In recent years, due to the high functionality and downsizing of these optical readers and the like, the optical scanning device and the motor used therein are also required to be further downsized as well as faster.

FIG. 7 shows a perspective view of the optical scanning device 900.

In the optical scanning device 900, a scanning unit 910 and a light source unit 990 are installed on a substrate 980. The light source unit 990 includes a laser element 992 and a lens 994, and emits the light projected from the laser element 992 toward the polygon mirror 912 of the scanning unit 910 while expanding the light with the lens 994. The scanning unit 910 rotates the polygon mirror 912 around the fixed axis 916 in order to scan the light from the light source unit 990. In order to describe the inside of the optical scanning unit 910 in detail, FIG. For simplicity, the polygon mirror 912 is removed. A direction in which the fixed shaft 916 extends with respect to the substrate 980 is an upward direction.

As shown in FIG. 8, in the scanning unit 910, a holder 919 is fixed to a substrate 980, and the holder 919 supports a cylindrical fixed shaft 916 and a stator 920. The stator 920 is provided with six coils 922 that are separated by 60 degrees around the axis of the fixed shaft 916.
The fixed shaft 916 is provided with a first rolling bearing 930 at its upper end, and the second rolling is separated from the axial direction of the fixed shaft 916 between the first rolling bearing 930 and the holder 919. A bearing 940 is provided.

A hub 952 that supports a polygon mirror 912 (not shown) is sandwiched between the bottom surface of the first outer ring 934 and the upper surface of the second outer ring 944 and is rotatably supported by the fixed shaft 916.

Each of the first rolling bearing 930 and the second rolling bearing 940 has 7 to 8 spherical first rolling elements 936 and second rolling elements 946 inside thereof. A plurality of first and second rolling elements 936, 946 are provided between the outer peripheral surfaces of the first and second inner rings 932, 942 and the inner peripheral surfaces of the first and second outer rings 934, 944. And the inside of the 1st and 2nd rolling bearings 930 and 940 revolves while rotating according to rotation of the 2nd outer ring 934,944. The hub 952 is sandwiched between the first and second outer rings 934 and 944 and rotates with respect to the fixed shaft 916 together with the first and second outer rings 934 and 944. The rotational movement between the fixed shaft 916 and the hub 952 is caused by the rolling of the plurality of first and second rolling elements 936 and 946 described above, and the rotational friction between the fixed shaft 916 and the hub 952 is changed from sliding friction to rolling friction. It is converted and rotation with less loss is realized.

At the lower end of the hub 952, a yoke 954 that prevents magnetic field leakage is provided in an annular shape. On the inner peripheral surface of the yoke 954, a plurality of magnetic bodies 956 are provided at positions facing the plurality of coils 922 described above. The yoke 954 prevents the magnetic fields of the plurality of magnetic bodies 956 from leaking outside by covering the plurality of magnetic bodies 956 on the inner peripheral surface.

Further, a retaining ring 970 is provided above the first rolling bearing 930 provided on the fixed shaft 916 in order to position the first rolling bearing 930. The retaining ring 970 positions the first rolling bearing 930 in the axial direction by bringing the bottom surface of the retaining ring 970 into contact with the top surface of the second inner ring 932 in the axial direction of the fixed shaft 916.

The preload spring 960 is disposed between the holder 919 and the bottom surface of the second inner ring 942 in order to apply preload to the first and second rolling bearings 930 and 940. The preload spring 960 applies a predetermined pressure value to the holder 919 and the second inner ring 942, so that the first and second inner rings 932 and 942, the first and second rolling elements 936 and 946, It is possible to eliminate the clearance between the first and second outer rings 934 and 944 and eliminate backlash. In particular, it is possible to prevent the first and second inner rings 932 and 942 and the rotating member 950 from rotating together. More specifically, the second inner ring 942 is restrained from co-rotation by the static frictional force on the contact surface with the preload spring 960, and the first inner ring 932 is driven by the preload transmitted through the hub 952. It can be said that co-rotation is suppressed by the static frictional force on the contact surface with the retaining ring 970 that is pressed against the retaining ring 970.
JP 2001-117042 A

In order to further increase the rotational speed of the motor while preventing the first and second inner rings 932 and 942 from rotating together with the rotating member 950, the static frictional force between the second inner ring 942 and the preload spring 960, and the first It is necessary to increase the static frictional force between the inner ring 932 and the retaining ring 970. For this purpose, it is necessary to increase the pressure value by the preload spring 960. If this pressure value is too high, the first and second inner rings 932, 942 in the first and second rolling bearings 930, 940 and Abnormal heat generation and an increase in friction moment occur at the contact surfaces of the first and second outer rings 934, 944 and the first and second rolling elements 936, 946. Further, the resultant force due to excessive compressive stress or shear stress is applied to the surfaces of the first and second rolling elements 936 and 946 beyond the fatigue limit, causing surface separation and causing a phenomenon such as a decrease in fatigue life. Therefore, there is a limit to the pressure value applied to the first and second rolling bearings 930 and 940, and there is a problem that the rotational speed of the motor cannot be increased.

Other methods for preventing the inner ring from rotating together include a method of applying and fixing an adhesive between the fixed shaft 916 and the first and second inner rings 932 and 942, and the first and second inner rings 932 and 932. For example, a method in which the inner diameter of 942 is slightly smaller than the outer diameter of the fixed shaft 916 and is press-fitted and fixed. However, in the case of a small motor having a fixed shaft 916 having a diameter of 1 to 1.5 mm, it is troublesome to apply an adhesive between the fixed shaft 916 and the first and second inner rings 932 and 942. It becomes. Further, in order to press-fit the first and second inner rings 932 and 942 made of high carbon chrome steel or the like into the fixed shaft 916 made of high carbon chrome steel or the like, the fixed shaft 916 may be too thin and deform. Is expensive. Therefore, the smaller the motor is, the more difficult it is to increase the rotational speed of the motor while preventing the inner rings 932 and 942 and the hub 952 from rotating together.

An object of the present invention is to provide a motor bearing mechanism capable of simultaneously reducing the size of the motor and increasing the speed of rotation of the motor, an optical scanning device having the motor bearing mechanism, and an optical device having the optical scanning device. Propose reading device.

A motor bearing mechanism according to a first aspect of the present invention includes a base, a columnar support member erected on the base, and the base or the support member provided in a substantially annular shape around the support member. A plurality of coils, a first inner ring provided on the support member and spaced apart from the base, and having an inner diameter substantially the same as the outer diameter of the support member, and larger than the outer diameter of the first inner ring A first rolling bearing comprising a first outer ring having an inner diameter, a first rolling element sandwiched between an outer peripheral surface of the first inner ring and an inner peripheral surface of the first outer ring; The first rolling bearing and the base are spaced apart from the first rolling bearing and the base, respectively, and are provided on the support member, and have an inner diameter substantially the same as the outer diameter of the support member. Two inner rings, a second outer ring having an inner diameter larger than the outer diameter of the second inner ring, A second rolling bearing comprising a second rolling element sandwiched between an outer peripheral surface of the second inner ring and an inner peripheral surface of the second outer ring; the first rolling bearing; and the second rolling bearing. Between a pair of opposing surfaces of the rolling bearing, the first outer ring and the second outer ring are sandwiched between and supported by the support member in a rotatable manner, and a plurality of positions are opposed to the plurality of coils. A rotating member having a substantially annular magnetic body, and a first inner ring abutting in the axial direction on a back surface of a surface of the first rolling bearing that is fixed to the supporting member and sandwiches the rotating member. Between the positioning member for positioning the first rolling bearing in the axial direction and the second inner ring on the back surface of the base that sandwiches the rotating member of the second rolling bearing. For the base and the second inner ring A first spring that provides a first pressure value determined for the motor, and a bearing mechanism for a motor that rotates the rotating member by electromagnetic force generated between the plurality of coils and the plurality of magnetic bodies. Then, between the first and second inner rings between a pair of opposing surfaces of the first rolling bearing and the second rolling bearing, a first pressure value of the first spring is applied. And a second spring that provides a weak second pressure value.

1st invention of this application is the 1st pressure value of the 1st spring with respect to the 1st and 2nd inner ring between a pair of surfaces where the 1st rolling bearing and the 2nd rolling bearing oppose. By providing the second spring that gives a weaker second pressure value, the first and second rolling elements can be increased by increasing the second pressure value even if the first pressure value is increased. Can be kept substantially constant. Therefore, the static frictional force between the first inner ring and the positioning member and the static frictional force between the second inner ring and the first spring can be increased, and the rotation of the motor can be speeded up. Further, since the second spring is provided between a pair of opposing surfaces of the first rolling bearing and the second rolling bearing and is housed inside the rotating member, the outermost diameter of the motor is increased. There is nothing.
Here, it is needless to say that the plurality of magnetic bodies includes a plurality of pairs of magnetic poles and includes a single magnet.

A motor bearing mechanism according to a second aspect of the present invention is provided in a substantially annular shape around the support member on the base, a columnar support member standing on the base, and the base or the support member. A plurality of magnetic bodies, a first inner ring provided on the support member and spaced apart from the base, and having an inner diameter substantially the same as an outer diameter of the support member; and an outer diameter of the first inner ring A first rolling bearing comprising a first outer ring having an inner diameter, a first rolling element sandwiched between an outer peripheral surface of the first inner ring and an inner peripheral surface of the first outer ring; Between the first rolling bearing and the base, the first rolling bearing and the base are spaced apart from each other and provided on the support member, and have an inner diameter that is substantially the same as the outer diameter of the support member. A second inner ring, a second outer ring having an inner diameter greater than the outer diameter of the second inner ring, and the front A second rolling bearing comprising a second rolling element sandwiched between an outer peripheral surface of the second inner ring and an inner peripheral surface of the second outer ring; the first rolling bearing; and the second rolling bearing. Between a pair of opposing surfaces of the rolling bearing, the first outer ring and the second outer ring are sandwiched and supported rotatably with respect to the support member, and a plurality of positions are provided opposite to the plurality of magnetic bodies. A rotating member provided with a substantially annular coil, and a first inner ring abutting in the axial direction on a back surface of a surface of the first rolling bearing that is fixed to the support member and sandwiches the rotating member. Between the positioning member for positioning the first rolling bearing in the axial direction and the second inner ring on the back surface of the base that sandwiches the rotating member of the second rolling bearing. For the base and the second inner ring A first spring that provides a first pressure value determined for the motor, and a bearing mechanism for a motor that rotates the rotating member by electromagnetic force generated between the plurality of magnetic bodies and the plurality of coils. Then, between the first and second inner rings between a pair of opposing surfaces of the first rolling bearing and the second rolling bearing, a first pressure value of the first spring is applied. And a second spring that provides a weak second pressure value.

The 2nd invention of this application also has the same effect as the 1st invention. The difference from the first invention is that, contrary to the first invention, a plurality of coils are provided on the rotating member side which is a rotor, and a plurality of magnetic bodies are provided on a base or support member which is a stator. It is a point.

According to a third aspect of the present invention, there is provided the motor bearing mechanism according to the first or second aspect, wherein the first and second springs are winding springs arranged around the support member.

In the third invention of the present application, since the first and second springs are wound springs arranged around the support member, the first and second springs are attached to the support member without providing other fixing members. Can be fixed in the radial direction, contributing to the miniaturization of the motor.

According to a fourth aspect of the present invention, there is provided the motor bearing mechanism according to the first to third aspects, wherein the first pressure value and the second pressure value are the first pressure value and the second pressure value, respectively. The pressure values generated by the difference between the first and second rolling bearings are set so as to be within the fatigue limits of the first rolling bearing and the second rolling bearing, respectively.

In the fourth invention of the present application, if all the first pressure values act on the first and second rolling elements, even if the fatigue limit of the first rolling bearing or the second rolling bearing is exceeded, Actually, since the pressure value generated by the difference between the first pressure value and the second pressure value is applied to the first and second rolling elements, the pressure value is applied to the first rolling bearing and the second rolling element. If it is within the fatigue limit of the bearing, the fatigue life will not be shortened. In addition, since the first pressure value can be set large, the motor can be rotated at high speed. Here, the fatigue limit basically means the maximum stress value that can withstand an infinite number of stress cycles without breaking the material, but is standard in the equipment to which the motor of the present invention is applied. Needless to say, even if a value that can withstand an infinite number of stress cycles is included in the scope of the present invention, it can be sufficiently endured up to the number of times it is used.

According to a fifth aspect of the present invention, there is provided the motor bearing mechanism according to any one of the first to fourth aspects, wherein the first pressure value is the same as the first and second rolling elements. When acted, the pressure value exceeds the fatigue limit of the first rolling bearing or the second rolling bearing.

In the fifth invention of the present application, by providing the second spring, the first pressure value of the first spring can be set to a pressure value exceeding the fatigue limit of the first rolling bearing or the second rolling bearing. The second inner ring can be pressed with a stronger force than in the prior art. In addition, the force is transmitted to the first inner ring via the second spring, and the first inner ring can be pressed with a stronger force. Therefore, even if the motor is rotated at a high speed, the inner ring rotates together. It becomes possible to prevent.

According to a sixth aspect of the present invention, there is provided the motor bearing mechanism, wherein the first pressure value and the second pressure value are generated by a difference between the first pressure value and the second pressure value. The static friction force between the first and second outer rings is larger than the force that the rotating member generated by the electromagnetic force tries to slide relative to the first and second outer rings. It is characterized by being set respectively.

In the sixth invention of the present application, since the first and second pressure values are set as described above, the sliding between the rotating member and the first and second outer rings is prevented, so that wear between the two is prevented. This prevents the motor from rotating at high speed.

In a motor bearing mechanism according to a seventh aspect of the invention, the first rolling bearing and the second rolling bearing have substantially the same shape, and the first pressure value and the second pressure value are The difference between the first pressure value and the second pressure value is 1 to 1.5% of the basic dynamic load rating defined in JIS B1518 of the first rolling bearing and the second rolling bearing. It is set so that it may become.

In the seventh invention of the present application, by setting the first and second pressure values as described above, the motor is rotated at a high speed without substantially shortening the fatigue life of the first and second rolling bearings. It becomes possible. Specifically, even if the motor is rotated at 15000 rpm, it can theoretically withstand continuous use for a sufficient time of 30 years or more.

An optical scanning device according to an eighth aspect of the present invention is an optical scanning device that scans light projected from a light projecting element using a polygon mirror, and includes the above-described motor bearing mechanism, and the motor bearing mechanism described above. The polygon mirror is supported by rotation.

In the eighth invention of the present application, in the optical scanning device, the polygon mirror can be rotated at a higher speed while reducing the size of the optical scanning device by rotating and supporting the polygonal mirror by the optical scanning device using the motor bearing mechanism as described above. Therefore, faster optical scanning is realized.

An optical reading device according to an eighth aspect of the invention is an optical reading device used for reading a bar code or a two-dimensional code, and has the above-described optical scanning device.

In the eighth invention of the present application, in the optical reading device, the above-described motor bearing mechanism is used in the optical scanning device, so that the optical scanning is performed at a high speed. The size of the apparatus can be reduced.

As described above, according to the bearing mechanism of the motor according to the present invention, the motor is rotated by providing the second spring between a pair of opposed surfaces of the first rolling bearing and the second rolling bearing. Further speeding up is possible. Further, since the second spring is provided between a pair of opposing surfaces of the first rolling bearing and the second rolling bearing and is housed inside the rotating member, the outermost diameter of the motor is increased. There is nothing. As described above, it is possible to increase the number of rotations of the motor only by adding the second spring that gives the second pressure value. Therefore, compared to the method of applying the adhesive and the method of press-fitting, Workability is also greatly improved.
Further, according to the optical scanning device of the present invention, the polygon mirror can be rotated at a higher speed while reducing the size of the optical scanning device, so that higher-speed optical scanning is realized. Furthermore, according to the optical reading device of the present invention, the optical scanning device having the above-mentioned motor rolling bearing realizes high-speed optical scanning while reducing the size of the optical reading device, and stable reading at high speed. Can be realized.

A motor bearing mechanism according to an embodiment of the present invention will be described below with reference to FIGS.
Fig.1 (a) is a top view which shows an example of the bearing mechanism of the motor which concerns on embodiment of this invention, FIG.1 (b) is a perspective view, FIG.1 (c) is a front view.
As shown in FIG. 1B, in the motor bearing mechanism 1, a fixed shaft 30 is erected on a substrate 10, and a rotating member 70 is rotatably supported on the fixed shaft 30. Hereinafter, the direction in which the fixed shaft 30 extends from the substrate 10 will be described as the upward direction. First, in order to explain the schematic structure of the present invention and the transmission of the pressing force of the spring, a schematic cross-sectional view of the AA ′ cross-section of FIG. 1A is shown in FIG.

(Schematic structure of motor bearing mechanism)
As shown in FIG. 2, in the motor bearing mechanism 1, the fixed shaft 30 is erected on the substrate 10 as described above.
The fixed shaft 30 is provided with a stator (not shown) at a position close to the substrate 10, and the stator is provided with six coils (not shown) spaced 60 degrees around the fixed shaft 30. ing. A first rolling bearing 50 is provided at the upper end portion of the fixed shaft 30, and a second rolling bearing 60 is disposed between the substrate 10 and the first rolling bearing 50 in the axial direction of the fixed shaft 30. They are spaced apart.

The first rolling bearing 50 includes a first inner ring 52 having an inner diameter substantially the same as the outer diameter of the fixed shaft 30, a first outer ring 54 having an inner diameter larger than the outer diameter of the first inner ring 52, And a plurality of first rolling elements 56 sandwiched between the outer peripheral surface of one inner ring 52 and the inner peripheral surface of the first outer ring 54. In the present embodiment, since the first rolling bearing 50 is inserted into the fixed shaft 30 and assembled, the inner diameter of the first inner ring 52 is set to be the same as or slightly larger than the outer diameter of the fixed shaft 30. More specifically, the plurality of first rolling elements 56 are configured by seven balls.

The second rolling bearing 60 has substantially the same shape and the same dimensions as the first rolling bearing 50, and has a second inner ring 62 and a second inner ring that have an inner diameter substantially the same as the outer diameter of the fixed shaft 30. A second outer ring 64 having an inner diameter larger than the outer diameter of 62, and a plurality of second rolling elements 66 sandwiched between the outer peripheral surface of the second inner ring 62 and the inner peripheral surface of the second outer ring 64. And have.

The rotating member 70 has a substantially cylindrical shape. The rotating member 70 has a through hole 72a having an inner diameter substantially the same as the outer diameter of the first and second outer rings 54 and 64, and a first hole provided on the inner peripheral surface of the through hole 72a. And an annular protrusion 73 sandwiched between the second outer rings 54 and 64, and a plurality of magnetic bodies that generate the rotational force of the motor.
The through-hole 72a is provided at the center of the rotating member 70, and an annular protrusion 73 having a predetermined axial height is formed on the inner peripheral surface in the vicinity of the center in the axial direction.
The annular protrusion 73 protrudes from the inner peripheral surface of the through hole 72 a over the entire circumference by a predetermined thickness in the axial center direction of the fixed shaft 30.
The rotating member 70 is rotatably supported with respect to the fixed shaft 30 by sandwiching the annular protrusion 73 between the bottom surface of the first outer ring 56 and the upper surface of the second outer ring 66 described above.
The projecting amount of the annular protrusion 73 in the axial center direction is a range in which the annular protrusion 73 does not interfere with the first and second inner rings 52 and 62 when rotating, in other words, the annular protrusion 73 has the first and second inner rings 52. , 62 can be set within a range not touching. More specifically, the radial thickness of the first and second outer rings 54, 64, the contact area between the first and second outer rings 54, 64 and the annular protrusion 73, the material of each member, and the necessary. It is set as appropriate depending on the frictional force, the pressure values of the first and second springs described later, and the like. In the present embodiment, the annular protrusion 73 is in contact with only the first and second outer rings 54 and 64 and protrudes to substantially the center of the first and second outer rings 54 and 64.

The positioning member 90 is provided above the first inner ring 52 of the fixed shaft 30 in order to position the first rolling bearing 50 in the axial direction.
Although the details will be described later, the positioning member 90 is formed by a member having a C-shaped cross section and is fitted into a groove portion 32 formed at the upper end portion of the fixed shaft 30.

Here, the positioning of each of the first and second rolling bearings 50 and 60 in the axial direction will be described. The first rolling bearing 50 is positioned in the axial direction by bringing the top surface of the first inner ring 52 into contact with the bottom surface of the positioning member 90 and bringing the bottom surface of the first outer ring 54 into contact with the top surface of the annular protrusion 73. Is done. Further, the second rolling bearing 60 abuts the upper surface of the second outer ring 64 against the bottom surface of the annular protrusion 73 and abuts the bottom surface of the second inner ring 62 with an upper end portion of the first spring 100 described later. As a result, positioning in the axial direction is performed.

The first spring 100 is provided in a compressed state between the substrate 10 and the bottom surface of the second inner ring 62. The first spring 100 is a compression coil spring (winding spring) disposed around the fixed shaft 30, and is compressed to a length L 1 between the bottom surface of the second rolling bearing 60 and the substrate 10. The second inner ring 62 is configured to have a pressing force capable of giving a predetermined first pressure value.

The second spring 110 is provided in a compressed state at a position between the bottom surface of the first inner ring 52 and the upper surface of the second inner ring 62 in order to relieve the preload of the first spring 100. The second spring 110 is a compression coil spring (winding spring) disposed around the fixed shaft 30 and is compressed to a length L2 determined by the axial width of the annular protrusion 73 in the first state. The spring 100 is configured to have a pressing force capable of giving a second pressure value that is weaker than the first pressure value of the spring 100.
In the present embodiment, the first spring 100 is adjusted to provide a first pressure value at a length L1, and the second spring 110 is adjusted to provide a second pressure value at a length L2. In other words, this means that the length L1 is set such that the first spring 100 gives the first pressure value, and the length that the second spring 110 gives the second pressure value. Needless to say, L2 may be set.

The first pressing force F <b> 1 gives a first pressure value to the bottom surface of the second inner ring 66 by the first spring 100, and is transmitted from the outer peripheral surface of the second inner ring 62 to the second rolling element 66. The pressure is distributed to the pressing force F2 and the third pressing force F3 transmitted to the upper surface of the second inner ring 62. FIG. 2 shows the transmission of each pressing force with arrows.

The second pressing force F <b> 2 is transmitted to the inner peripheral surface of the second outer ring 64 via the second rolling element 66. Further, the second pressing force F <b> 2 is transmitted from the second outer ring 64 to the first outer ring 54 via the rotating member 70. Subsequently, the first inner ring 52 is transmitted to the first inner ring 52 via the first rolling element 56 that contacts the first outer ring 54, and a pressing force is applied to the upper surface of the first inner ring 52 against the positioning member 90.

The third pressing force F3 is a reaction force of the fourth pressing force F4 in which the second spring 110 presses the upper surface of the second inner ring 62. The fifth pressing force F5 is a pressing force paired with the fourth pressing force F4 as a restoring force of the second spring 110, and has the same magnitude as the fourth pressing force F4 in the axial direction of the fixed shaft 70. Push the bottom surface of the first inner ring 52 in the opposite direction. If the weight of the rotating member 70 and the like is ignored, the fifth pressing force F5 becomes a pressing force that abuts the first inner ring 52 against the positioning member 90 together with the above-described second pressing force F2.

Here, since the third pressing force F3 is determined by the fourth pressing force F4, the difference between the first pressing force F1 of the first spring 100 and the fourth pressing force F4 of the second spring 110. As a result, the second pressing force F2 is obtained. That is, even if the first pressing force F1 of the first spring 100 is increased, if the fourth pressing force F4 of the second spring 110 is increased and the difference is kept constant, the first and second It is possible to increase the first pressing force F1 without increasing the second pressing force F2 transmitted to the rolling elements 56, 66.
Further, the resultant force of the second pressing force F2 and the fifth pressing force F5 that prevents the first inner ring 52 from rotating together increases the fourth pressing force F4 as the first pressing force F1 increases. Therefore, the fifth pressing force F5 paired with the fourth pressing force F4 also increases, and the resultant force can be increased even if the second pressing force F2 is kept constant.

That is, the second spring 110 abuts between the first inner ring 52 of the first rolling bearing 50 and the second inner ring 62 of the second rolling bearing 60, so that The preload applied to the second rolling elements 56 and 66 is relaxed. Therefore, if the first preload value given by the first pressing force F1 of the first spring 100 acts on the first and second rolling elements 56 and 66, the first rolling bearing 50 or the first It is possible to increase the pressure value to exceed the fatigue limit of the second rolling bearing 60. As a result, the above-described static frictional force of the first and second inner rings 52 and 62 can be increased, so that even if the rotating member 70 is rotated at a higher speed than in the prior art, it is possible to prevent co-rotation.
On the other hand, since the second spring 110 is provided in the gap between the first and second rolling bearings 50 and 60 that existed in the past, the conventional motor can be referred to from the viewpoint of the overall size of the apparatus. Compared with the bearing mechanism, it is possible to contribute to miniaturization without enlarging its outermost shape.

The second pressing force F2 is generated by the difference between the first pressure value and the second pressure value, and the pressure value is within the fatigue limit of the first and second rolling bearings 50 and 60. It is preferable to set to. This is because abnormal heat generation and wear in the first and second rolling bearings 50 and 60 do not occur or hardly occur if used within the fatigue limit.
Furthermore, the static frictional force between the rotating member 70 generated by the second pressing force F2 and the first and second outer rings 54, 64 is generated by the rotating member 70 generated by the electromagnetic force, and the first and second outer rings. It is preferable that the setting is made so as to be larger than the force to slide against 54 and 64, respectively. Accordingly, since the rotating member 70 and the first and second outer rings 54 and 64 rotate together, heat generation and wear are less likely to occur on the contact surfaces.

In the above embodiment, the case where the coil 44 is provided on the fixed shaft 30 on the stator side of the motor and the magnetic body group 78 is provided on the rotating member 70 on the rotor side of the motor has been described. Not limited to this, the coil 44 may be provided on the rotor side, and the magnetic body group 78 may be provided on the stator side. Further, although the coil 44 is provided on the fixed shaft 30, it may be provided on the substrate 10 at a position facing the magnetic body group 78.
Further, the rotating member 70 is supported by the rotating member 70 only by the annular protrusion 73, but not limited to this, between the inner peripheral surface of the through hole 72 a and the outer peripheral surfaces of the first and second outer rings 54 and 64. An adhesive may be applied and bonded and fixed. Also, recesses and projections extending in the axial direction are provided at corresponding positions on the inner peripheral surface of the through-hole 72a and the outer peripheral surfaces of the first and second outer rings 54 and 64, respectively, so that positioning in the rotational direction can be performed. Good.
Further, since the rotary member 70 has the annular protrusion 73, the rotary member 70 is supported and the length L2 of the second spring 110 is dimensioned. However, the present invention is not limited thereto, and the through hole 72a of the rotary member 70 is not limited. The inner peripheral surface and the first and second outer rings 54 and 64 are fixed by bonding, and instead of the annular protrusion 73, an annular dimension having the same height and the same radial thickness as the annular protrusion 73 is determined. The length L2 of the spring 110 may be dimensioned by separately providing a member at the same position as the annular protrusion 73. Of course, this dimension determining member does not necessarily need to be annular, and may have any shape as long as the dimension of the length L2 can be measured without interfering with the first and second inner rings 52, 62. Needless to say, it may be composed of a plurality of members.
Further, in the present embodiment, an example in which the fixed shaft 30 is fixed to the substrate 10 is shown, but the present invention is not limited to this, and the rotating member 70 is fixed by another member, and the fixed shaft 30 is not fixed to the substrate 10. You may take the structure which the side rotates.

(Detailed structure of motor bearing mechanism)
Next, the detailed structure of the present invention will be described together with the assembling method. FIG. 3 is a detailed AA ′ sectional view of the motor bearing mechanism 1 of the present invention in FIG. 1B, and FIG. 4 is an assembled perspective view.

The motor bearing mechanism 1 is first assembled using the substrate 10 as a base.
As shown in FIGS. 3 and 4, the substrate 10 is provided with a through hole 11 in the center. The substrate 10 is formed of a silicon steel plate in order to function as a part of a magnetic circuit mainly including the coil 44 and the magnetic body group 78.
The holder 20 is provided to fix a fixed shaft 30 and a stator 40, which will be described later, to the substrate. Hereinafter, the holder 20 will be described.
The holder 20 has a cylindrical shape having substantially the same diameter as the through hole 11 of the substrate 10, and has a slightly larger diameter than the through hole 11 until the flange portion 25 provided on the entire circumference hits the substrate 10. The substrate 10 is fixed to the substrate 10 by being inserted into the through-hole 11 and caulking the substrate 10 with an annular convex portion 26 provided on the outer peripheral edge of the bottom portion of the holder 20.
The holder 20 is provided with a through hole 22 extending in the vertical direction at the center, and one end of a cylindrical fixed shaft 30 made of stainless steel is press-fitted into the through hole 22, so that the fixed shaft 30 is attached to the substrate 10. Standing up.
Furthermore, the upper end portion 28 of the holder 20 is formed so that the outer diameter is slightly smaller than that of the through hole 11. A through-hole 41 of the stator 40 described later is pressed into the upper end 28 after the above-described fixed shaft 30 is press-fitted, and is pressed downward against an annular step 29 provided on the outer peripheral surface. The stator 40 is positioned and fixed with respect to the holder 20.
In this embodiment, the holder 20 is made of brass that is relatively soft and has good cutting properties because the substrate 10 is caulked and held by the annular convex portion 26 or the stator 40 is press-fitted into the upper end portion 28 as described above. ing.

  As shown in FIG. 4, the stator 40 has a substantially T-shaped core comprising a neck portion 42a extending in the radial direction and a head portion 42b protruding in the circumferential direction at the tip thereof in order to further enhance the generation of the magnetic field. Sixty-two 42 are provided spaced apart by 60 degrees in the circumferential direction. A coil 44 that generates magnetic flux is wound around the neck portion 42a of each core 42, and the head portion 42b prevents the coil 44 from coming off in the radial direction. The stator 40 uses a silicon steel plate to increase the magnetic flux of the coil 44.

The first spring 100 is provided to apply preload to first and second rolling bearings 50 and 60 described later. Therefore, the first spring 100 is set so that its inner diameter is slightly larger than the outer diameter of the fixed shaft 30 along the outer peripheral surface of the fixed shaft 30 in the axial direction, and the fixed shaft 30 is fixed after the fixed shaft 30 is press-fitted into the holder 20. Inserted into the shaft 30, the lower end of the first spring 100 comes into contact with the upper surface 21 of the holder 20.

Next, the second rolling bearing 60 is inserted into the fixed shaft 30 to rotate and support a rotating member 70 described later, and the bottom surface of the second inner ring 62 abuts on the upper end portion of the first spring 100.
FIG. 5 shows a cross-sectional perspective view of a rolling bearing used in the present embodiment in order to explain the details of the second rolling bearing 60.
As described above, the second rolling bearing 60 includes the second inner ring 62 having an inner diameter substantially the same as the outer diameter of the fixed shaft 30 and the second outer ring having an inner diameter larger than the outer diameter of the second inner ring 62. 64 and a plurality of second rolling elements 66 sandwiched between the outer peripheral surface of the second inner ring 62 and the inner peripheral surface of the first outer ring 64.
Specifically, the plurality of second rolling elements 66 are provided with 7 to 8 balls. A pair of race surfaces 62 a and 64 a corresponding to the surface shape of the ball are provided on the outer peripheral surface of the second inner ring 62 and the inner peripheral surface of the second outer ring 64, respectively.
The second outer ring 64 rolls with respect to the second inner ring 62 by revolving the inside of the second rolling bearing 60 while the plurality of balls described above revolve between the pair of race surfaces 62a and 64a. It can be rotated by friction.
In the present embodiment, the first and second rolling bearings 50 and 60 mainly receive axial loads, and therefore, for example, thrust bearings are used. These are high carbon chromium from the viewpoint of hardness and wear resistance. It is made of steel.

Next, the rotating member 70 that is a rotating portion of the motor will be described. The rotating member 70 is placed on the upper surface of the second outer ring 64 of the second rolling bearing 60 described above. The rotating member 70 includes a second rolling bearing 60 on the fixed shaft 30 and a hub 72 that is rotatably supported by a first rolling bearing 50 described later, and an annular yoke 76 that is held at the bottom of the hub 72 and prevents leakage of magnetic flux. And an annular magnetic group 78 that is held by the inner peripheral surface of the yoke 76 and functions as a part of the magnetic flux circuit.

Each component of the rotating member 70 will be described below.
The hub 72 has a substantially cylindrical shape, and has a through hole 72a extending in the vertical direction at the center, and includes the first and second rolling bearings 50 and 60 therein. The annular protrusion 73 described above is provided on the inner peripheral surface of the through-hole 72a, and the annular protrusion 73 is sandwiched between the first and second rolling bearings 50 and 60, and is thereby rotatably supported by the fixed shaft 30.
A polygon mirror (not shown) is attached to an outer peripheral surface 75 that is opposed to the inner peripheral surface of the through hole 72 a and is formed on the upper portion of the hub 72. The flange portion 74 is provided below the outer peripheral surface 75 to extend the radial direction from the outer peripheral surface 75 in order to hold the yoke 76.
An annular convex portion 74 a is provided on the bottom surface of the flange portion 74 so as to be inserted into the yoke 76. More specifically, the annular convex portion 74 a is provided in an annular shape, slightly inside the outer edge portion 74 b of the flange portion 74 and depending on the bottom surface of the flange portion 74.
Although details will be described later, the hub 72 is formed of a relatively soft brass or the like because the annular protrusion 74a fixes the yoke 76 by fixing it.

The yoke 76 includes a disc portion 76b that forms an opening 76a into which the annular convex portion 74a of the hub 72 is inserted, and a magnetic body holding portion 76c that is connected to the disc portion 76b and holds the magnetic body group 78. Yes. In order to fix the yoke 76 to the hub 72, the annular convex portion 74a of the hub 72 is inserted from above the opening 76a, and the outer edge portion 74b is abutted against the disc portion 76b. The yoke 76 is a corner portion formed by the annular convex portion 74a and the outer edge portion 74b, and is positioned in the axial direction and the radial direction with respect to the hub 72. By caulking the annular convex portion 74a from below, the hub 72 is provided. Fixed to.
The magnetic body holding portion 76c is connected to the disc portion 76a and has an annular shape that hangs down from the outer edge of the disc portion 76a. After the yoke 76 is fixed to the hub 72, the magnetic body group 78 is press-fitted into the inner peripheral surface of the magnetic body holding portion 76c, and the magnetic body group 78 is positioned and fixed to the hub 72.
The yoke 76 as a whole prevents the magnetic flux generated from the magnetic body group 78 from leaking to the outside, but the magnetic body holding portion 76c is partially used to leak a part of the magnetic flux to the outside at a limited position. Is provided with a rectangular opening 76d.
By providing the magnetic flux detection circuit 16 (not shown) on the substrate 10 at a position close to the rotating member 70, the above-described leaked magnetic flux is detected. More specifically, since the opening 76d approaches or moves away from the magnetic flux detection circuit 16 due to the rotation of the rotating member 70, the rotation of the rotating member 70 can be detected by measuring the strength of the magnetic flux. By counting the number of times the magnetic flux is detected, the number of rotations of the motor can be measured.
As described above, the yoke 78 is formed of a relatively soft cold-rolled steel plate or electrogalvanized steel plate in order to caulk the magnetic body group 78 while preventing leakage of magnetic flux of the magnetic body group 78.

FIG. 6 is a view for explaining the positional relationship between the stator 40 and the magnetic body group 78 when the rotating member 70 is fixed to the fixed shaft 30. In order to generate a magnetic field, the magnetic body group 78 is formed of neodymium and has a polarity in the order of the N pole and the S pole toward the center of the stator 40, and the polarity in the reverse order. The second magnetic body 78S has a total of eight magnetic bodies arranged alternately four by 45 degrees in the circumferential direction. The magnetic body group 78 is disposed so as to face the magnetic field of the coil 42 of the stator 40 when the rotating member 70 is fixed to the fixed shaft 40.

The rotating member 70 formed as described above accommodates the second rolling bearing 60 in a space below the annular protrusion 73 of the through hole 72a, while the bottom surface of the annular protrusion 73 is the second outer ring 64. By striking the upper surface, it is placed on the second rolling bearing 60.
In addition to the second rolling bearing 60, the rotating member 70 is positioned on the fixed shaft 30 by a first rolling bearing 50, a first spring 100, a positioning member 90, and the like, which will be described later.
When the rotation member 70 is positioned on the fixed shaft 30, the annular protrusion 73 of the through hole 72 a described above so that the second rolling bearing 60 is positioned above the stator 40 and the coil 44 described above. Is provided. Further, the above-described flange portion 74 is provided at substantially the same height as the second rolling bearing 60 so as to surround the above-described stator 40, and a yoke 76 that is suspended from the substantially outer edge of the flange portion 74 is further provided. Further, the rotating member 70 holds the magnetic body group 78 on the inner peripheral surface of the yoke 76 between the stator 40 and the yoke 76 in the radial direction, so that a plurality of coils provided in the stator 40 described above. The magnetic body group 78 can be arranged on the outer periphery of the disk 44 and at almost the same height as the plurality of coils 44.
The magnetic body group 78 can efficiently form a magnetic circuit with the plurality of coils 44 by these positional relationships.
The distance between the magnetic body group 78 and the coil 44 is desirable because a stronger magnetic field is generated. However, the distance is appropriately set depending on shaft runout during rotation of the motor, the size of the core 42, a desired magnetic field strength, and the like. In the present embodiment, the magnetic body group 78 is configured as a single unit as a magnet and has eight pairs of magnetic poles. However, the present invention is not limited to this, and the magnetic body group 78 has eight pairs of magnetic poles. You may comprise from a magnet. In addition, an example in which a plurality of magnetic bodies and coils are provided in an approximately annular shape has been introduced.

The second spring 110 is provided for the purpose of relaxing the preload by the first spring 110, and its inner diameter is slightly larger than the outer diameter of the fixed shaft 30 along the axial direction with respect to the outer peripheral surface of the fixed shaft 30. It is set larger and is inserted into the fixed shaft 30. As a result, the lower end portion of the second spring 110 is brought into contact with the upper surface of the second inner ring 62. Whichever of the second spring 110 and the rotating member 70 may be inserted into the fixed shaft 30 first, when the rotating member 70 is inserted first, the second spring 110 has the annular shape described above. It is accommodated in a gap surrounded by the protrusion 73.
Similar to the second rolling bearing 60, the first rolling bearing 50 is provided for rotatably supporting the rotating member 70 described above on the fixed shaft 30. In particular, the first rolling bearing 50 is inserted into the fixed shaft 30 after the second spring 110 and the rotating member 70, and the upper end of the second spring 110 abuts against the bottom surface of the first inner ring 52. As a result, the first rolling bearing 50 is accommodated in a space above the annular protrusion 73 of the through hole 72 a of the rotating member 70. Since the first rolling bearing 50 has the same shape and the same dimensions as the second rolling bearing 60 in the present embodiment, detailed description thereof is omitted.

The positioning member 90 is provided for positioning the first rolling bearing 50, and is formed by a retaining ring made of PET having a C-shaped cross section as shown in FIG. The positioning member 90 compresses the above-described second spring 110 and the first rolling bearing 50 abuts against the upper surface of the annular protrusion 73 of the hub 72, so that the groove 32 provided at the upper end of the fixed shaft 30 is provided. The first rolling bearing 50 is positioned in the axial direction by being fitted to the first and second bearings.
Here, the positioning member 90 may be formed of a resin such as nylon in addition to PET, and may be an E-shaped retaining ring other than the C-shape. The resin is used because it is easy to attach and detach, and if it is not necessary to attach and detach, it may be made of metal. Further, in order to increase the static frictional force with the first inner ring 52, it is preferable that the surface is roughened. The positioning member 90 does not necessarily have to be a ring. If the first rolling bearing 50 is positioned, a through hole is provided in the upper end portion of the fixed shaft 30, and the first rolling bearing 50 is attached to the fixed shaft 30. After the insertion, positioning may be performed by putting a pin in the through hole.
The motor bearing mechanism 1 is assembled as described above.

When the position of the first rolling bearing 50 in the axial direction is determined by the positioning member 90 and the upper surface of the annular protrusion 73 of the hub 72, the second spring 110 has the axial length of the annular protrusion 73. The pressure is compressed to the determined length L2, and a pressing force having a second pressure value is applied to the first and second inner rings 52 and 62.
In addition, when the position of the second rolling bearing 60 in the axial direction is determined by the bottom surface of the annular protrusion 73 and the upper end portion of the first spring 100, the first spring 100 is connected to the second inner ring 62 with the first spring 100. A pressing force having a pressure value is applied.
Here, the first and second springs 100 and 110 are made of stainless steel, particularly austenitic stainless steel, and for example, JIS standard SUS304 is preferable. This is because the steel wire material is not plated in the case of a small diameter, so that the corrosion resistance is insufficient, and the copper material cannot obtain the necessary spring force.

Next, the relationship between the specific size and pressure value in this embodiment will be described.
In the present embodiment, the inner diameters 52 and 62 of the first and second inner rings are about 1.5 mm, and the outer diameter of the yoke 76 is about 14 mm. In the conventional motor bearing mechanism, the pressure value applied to the first and second rolling elements 56 and 66 has an upper limit of about 100 gf when the inner diameter of the inner ring of the rolling bearing is about 1.5 mm. The value was almost the fatigue limit. Further, if the pressure value applied to the first and second rolling elements 56 and 66 is a pressure value of about 100 gf, the rotational speed of the motor is limited to about 6000 rpm. However, there was a problem of rotating together with the rolling elements and the outer ring.

In order to solve this problem, in the present embodiment, the first pressure value of the first spring 100 is set to be 135 gf when the length L1 is 1.5 mm. The pressure value of 2 is set to 75 gf when the length L2 is 1.0 mm. From these relationships, the pressure value applied to the first and second rolling elements 56 and 66 is 135 gf−75 gf = 60 gf when the weight of the rolling elements is ignored, and the above-described problems such as fatigue limit do not occur.
In the motor employing the present invention, the pressure value applied to the first and second rolling elements 56 and 66 is suppressed to 60 fg, and the first pressure value of the first spring 100 is set to 135 gf. It is possible to obtain a larger frictional force generated between the bottom surface of the inner ring 62 and the first spring 100 than in the prior art. Further, the resultant force of the transmitted second pressing force F2 and the fifth pressing force F5 is 135 gf which is substantially the same as the first pressure value as described above. Therefore, the frictional force between the upper surface of the first inner ring 52 and the retaining ring 90 can be obtained larger than that of the prior art as described above. From these facts, in the present embodiment, it is possible to finally increase the rotation speed of the motor from 6000 rpm to 15000 rpm.

In particular, the difference between the first pressure value and the second pressure value is 1 to 1.5% of the basic dynamic load rating defined in JIS B1518-1992 for the first rolling bearing 50 and the second rolling bearing 60. It is preferable to set so as to be. When 1.5% is selected as the first and second pressure values, even if the rotational speed is increased to 15000 rpm, it can theoretically withstand continuous use for 30 years or more. Can be secured.
It should be noted that the spring length, pressure value, and inner diameter of the rolling bearing described herein exemplify a motor bearing mechanism for embodying the technical idea of the present anti-jaw I, and the present invention is described above. It is not specified by the numerical value.

In the motor bearing mechanism 1 according to the present invention, a polygon mirror is further attached to the outer peripheral portion 75 of the rotating member 70, and is rotated and supported with respect to the substrate 10, thereby scanning light from a light projecting element such as a laser. Applied to the device. Since the present optical scanning device can rotate the polygon mirror at a higher speed for the reasons described above, the projected light can be scanned at a higher speed.
Furthermore, the optical scanning device is applied to an optical reading device that reads an optical code such as a bar code or a two-dimensional code. By using the optical scanning device described above, this optical reading device can scan the light projected from the light projecting element at a higher speed toward the detection area of the optical code. For this reason, the number of reading times and reading speed of the optical coat are improved, and high-speed and stable reading can be realized. In addition, since the outermost shape of the optical scanning device does not increase in size, the overall size of the optical reading device can be prevented from increasing.

As described above, by providing the second spring 110 between the first and second inner rings 52, 62, the pressure value applied to the first and second rolling elements 56, 66 is suppressed, and the first spring 110 is suppressed. The first pressure value of the spring 100 can be increased. Therefore, since the static friction force for fixing the first and second inner rings 52 and 62 can be obtained more strongly, the first and second inner rings 52 and 62 are not rotated even when the rotating member 70 is rotated at a high speed. There is no co-rotation with. Furthermore, since the second spring 110 is accommodated in the gap between the first and second inner rings 52 and 62 that existed conventionally, without increasing the size of the entire bearing mechanism 1 of the motor, High-speed rotation can be realized. Further, in the optical scanning device, the polygon mirror is rotated and supported by using the bearing mechanism 1 of the motor, so that the polygon mirror can be rotated at a higher speed while reducing the size of the optical scanning device, so that higher-speed optical scanning is realized. The In addition, the optical reading device includes the optical scanning device having the above-described motor rolling bearing, so that high-speed optical scanning can be realized while reducing the size of the optical reading device, and high-speed and stable reading can be realized.

(A) Overall perspective view (b) Plan view (c) Front view Schematic sectional view of the present invention Detailed sectional view of the present invention Assembly perspective view of the present invention The perspective view of the 2nd rolling bearing 60 Explanatory drawing of the stator 40 and the magnetic body group 78 Conventional optical scanning device 900 Sectional view of a conventional motor rolling bearing

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor rolling bearing mechanism 10 Board | substrate 11 Through-hole 20 Holder 22 Through-hole 24 Outer peripheral surface 26 Annular convex part 30 Fixed shaft 32 Groove part 40 Stator 42 Core 42a Neck part 42b Head 44 Coil 50 1st rolling bearing 52 1st Inner ring 54 First outer ring 56 First rolling element 60 Second rolling bearing 62 Second inner ring 64 Second outer ring 66 Second rolling bearing 70 Rotating member 72 Hub 74 flange 74a annular convex part 74b outer edge part 75 Outer peripheral surface 76 Yoke 78 Magnetic body group 78N First magnetic body 78S Second magnetic body 90 Positioning member 900 Optical scanning device 910 Scanning section 912 Polygon mirror 916 Fixed shaft 919 Holder 920 Stator 922 Coil 930 First rolling bearing 932 First inner ring 934 First outer ring 936 First rolling element 940 Second rolling bearing 942 Second inner Wheel 944 Second outer ring 946 Second rolling element 950 Rotating member 952 Hub 954 Yoke 956 Magnetic body 970 Retaining ring

Claims (9)

The base,
A columnar support member erected on the base;
A plurality of coils provided on the base or the support member in a substantially annular shape around the support member;
A first inner ring provided on the support member and spaced apart from the base and having an inner diameter substantially the same as the outer diameter of the support member, and a first inner ring having an inner diameter larger than the outer diameter of the first inner ring A first rolling bearing comprising an outer ring and a first rolling element sandwiched between an outer peripheral surface of the first inner ring and an inner peripheral surface of the first outer ring;
Between the first rolling bearing and the base, the first rolling bearing and the base are spaced apart from each other and provided on the support member, and have an inner diameter that is substantially the same as the outer diameter of the support member. It is sandwiched between a second inner ring, a second outer ring having an inner diameter larger than the outer diameter of the second inner ring, and an outer peripheral surface of the second inner ring and an inner peripheral surface of the second outer ring. A second rolling bearing comprising a second rolling element;
Between the pair of opposing surfaces of the first rolling bearing and the second rolling bearing and sandwiched between the first outer ring and the second outer ring and rotatably supported by the support member; A rotating member provided with a plurality of magnetic bodies in a substantially annular shape at positions facing the plurality of coils;
The first rolling bearing is axially positioned by contacting the first inner ring in the axial direction on the back surface of the surface of the first rolling bearing that holds the rotating member. A positioning member to perform;
A first predetermined for the base and the second inner ring is provided between the base and the second inner ring on the back surface of the surface of the second rolling bearing that sandwiches the rotating member. A first spring for providing a pressure value, a bearing mechanism for a motor that rotates the rotating member by electromagnetic force generated between the plurality of coils and the plurality of magnetic bodies,
The first pressure value of the first spring is weaker with respect to the first and second inner rings between a pair of opposing surfaces of the first rolling bearing and the second rolling bearing. A motor bearing mechanism comprising a second spring for applying a second pressure value. The base,
A columnar support member erected on the base;
A plurality of magnetic bodies provided in a substantially annular shape around the support member on the base or the support member;
A first inner ring provided on the support member and spaced apart from the base and having an inner diameter substantially the same as the outer diameter of the support member, and a first inner ring having an inner diameter larger than the outer diameter of the first inner ring A first rolling bearing comprising an outer ring and a first rolling element sandwiched between an outer peripheral surface of the first inner ring and an inner peripheral surface of the first outer ring;
Between the first rolling bearing and the base, the first rolling bearing and the base are spaced apart from each other and provided on the support member, and have an inner diameter substantially the same as the outer diameter of the support member. A second inner ring having an inner diameter greater than an outer diameter of the second inner ring, and an outer peripheral surface of the second inner ring and an inner peripheral surface of the second outer ring. A second rolling bearing comprising a second rolling element formed,
Between the pair of opposing surfaces of the first rolling bearing and the second rolling bearing and sandwiched between the first outer ring and the second outer ring and rotatably supported by the support member; A rotating member in which a plurality of coils are provided in a substantially annular shape at positions facing the plurality of magnetic bodies;
The first rolling bearing is axially positioned by contacting the first inner ring in the axial direction on the back surface of the surface of the first rolling bearing that holds the rotating member. A positioning member to perform;
A first predetermined for the base and the second inner ring is provided between the base and the second inner ring on the back surface of the surface of the second rolling bearing that sandwiches the rotating member. A first spring for providing a pressure value, and a motor bearing mechanism for rotating the rotating member by electromagnetic force generated between the plurality of magnetic bodies and the plurality of coils,
The first pressure value of the first spring is weaker with respect to the first and second inner rings between a pair of opposing surfaces of the first rolling bearing and the second rolling bearing. A motor bearing mechanism comprising a second spring for applying a second pressure value.     3. The motor bearing mechanism according to claim 1, wherein the first and second springs are winding springs arranged around the support member. 4.     As for the first pressure value and the second pressure value, a pressure value generated by a difference between the first pressure value and the second pressure value is the first rolling bearing and the second rolling bearing. 4. The motor bearing mechanism according to claim 1, wherein the motor bearing mechanism is set so as to be within the fatigue limit.     The first pressure value is a pressure that exceeds the fatigue limit of the first rolling bearing or the second rolling bearing when all of the first pressure values act on the first and second rolling elements. 5. The motor bearing mechanism according to claim 1, wherein the motor bearing mechanism is set to a value.     The first pressure value and the second pressure value are between the rotating member generated by the difference between the first pressure value and the second pressure value and the first and second outer rings. 2. The static frictional force is set so that the rotating member generated by the electromagnetic force is larger than a force of sliding the first and second outer rings against the first and second outer rings. The motor bearing mechanism according to any one of claims 1 to 5.     The first rolling bearing and the second rolling bearing have substantially the same shape, and the first pressure value and the second pressure value are the first pressure value and the second pressure bearing, respectively. The difference from the pressure value is set to be 1 to 1.5% of the basic dynamic load rating defined in JIS B1518 of the first rolling bearing and the second rolling bearing. The motor bearing mechanism according to any one of claims 1 to 6. An optical scanning device that scans light projected from a light projecting element using a polygon mirror,
It has a bearing mechanism of a motor given in any 1 paragraph of Claims 1-7,
An optical scanning device characterized in that the polygon mirror is rotatably supported by a bearing mechanism of the motor.     An optical reading device used for reading a bar code or a two-dimensional code, comprising the optical scanning device according to claim 8.

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