Patent Application
20080059984
a is a diagram illustrating components of a force generated when a disc makes contact with a guiding section according to a conventional aligning claw.
b is a diagram illustrating components of a force generated when a disc makes contact with a guiding section according to the aligning claw of the present invention.
An entire structure of a brushless motor of the present invention will be described with reference to
According to
First, the rotator 10 will be described.
The rotator 10 includes: a shaft 12 which is a rotation axis J1; a rotor holder 13 which is a steel sheet pressed into a covered and substantially cylinder shape and is affixed to the shaft 12; a ring shaped rotor magnet 11 affixed to an interior surface of a cylinder section 13a of the rotor holder 13; and a ring shaped preload magnet 14 which is affixed to a downward facing surface of a cover section 13b of the rotor holder 13.
Next, the stator unit section 20 will be described.
The stator unit section 20 includes: a housing 22 which is a steel sheet pressed into a covered and substantially cylinder shape; a substantially cylinder shaped sleeve 23, affixed to an interior of the cylinder section 22a of the housing 22, for radially supporting the shaft 12 so as to allow the shaft 12 to rotate; a stator 21 affixed to a peripheral surface of the cylinder section 22a of the housing 22; a mounting board 24 affixed to a peripheral surface of the cylinder section 22a and is located axially toward a bottom part of the stator 21; a circuit board 25 affixed on a top surface of the mounting board 24; and a thrust plate 26, which is a thin plate, for axially supporting the shaft 12 so as to allow the shaft 12 to rotate and is located on a top surface of a base section 22b of the housing 22.
The sleeve 23 is formed by a lubricated sintering material. Also, toward a bottom of the cylinder 22a in the housing 22, a leveled section 22c, having a reduced circumference compared with the rest of the cylinder 22a, is formed. On an upper surface of the leveled section 22c, a ring shaped plate 27 is provided. The plate 27 is affixed by being sandwiched between the upper surface of the leveled 22c and a surface facing downward of the sleeve 27. Further, at a point of the shaft nearest to the plate 27, a reduced circumference section 12a is provided. An interior of the plate 27 is located radially near and facing an external circumference of the reduced circumference section 12a, and is located in such a manner that the inner surface of the plate 27 is nearer to a center of the shaft 12 than an external surface of the shaft 12 in areas other than the reduced circumference section 12a. Consequently, the plate 27 functions as a mechanism to prevent the shaft 12 from coming off the cylinder.
An extension section 22d, which extends radially outward, is provided at an upper end of the housing 22. The extension section 22d has its uppermost surface facing, without touching, the preload magnet 14. Due to an axially applied force of the preload magnet 14, rotation of the rotator unit 10 is stabilized.
The shaft 12 protrudes upwardly above the rotor holder 13. Also, the chucking device 30 is affixed, above the rotor holder 13, to the shaft 12 so as to allow the disc (not illustrated in
Next, details of the chucking device of the present invention will be described with reference to
According to
Further, the centering case section 31 and the aligning claw 33 of the chucking device 30 are conjointly molded as phenolic resin product. Materials for the resins are composite materials (e.g., polycarbonate (PC), poly phenylene sulfide (PPS), polyacetal (POM), etc.).
According to
An exterior of the retainer section 33a and that of the guiding section 33b form an inclined surface extending outwardly toward a bottom of the chucking device. A retainer section side angle of inclination θ2, which is an acute angle generated by the rotation axis J1 and the inclined surface of the retainer section 33a, and a guiding section side angle of inclination θ1, which is an acute angle generated by the rotation axis J1 and the inclined surface of the guiding section 33b, are such that θ2<θ1.
Further, at a section bordering the retainer section 33a and the guiding section 33b, an inclined section 33d, which is a surface protruding radially outward, is provided. Due to the inclined section 33d, the chucking device becomes able to guide the disc from the guiding section 33b to the retainer section 33a, thereby reducing the disc loading force.
An exterior of the supporter section 33c forms an inclined surface protruding outwardly in a radial manner and extending downwardly in an axial manner. Further, a supporter section side angle of inclination θ3, which is an acute angle generated by the rotation axis J1 and the inclined surface of the supporter section 33c, and the guiding section side angle of inclination θ1 are such that θ1<θ3. Furthermore, an elastic bend fulcrum section 33c1, which is provided at a topmost point of the supporter section 33c axially (e.g., at a radially innermost point thereof), as a fulcrum for causing the supporter section 33c to elastically bend both axially downward and radially inward when the disc makes contact with the aligning claw 33. A connection section 33e is provided axially downward from a top of the elastic bend fulcrum section 33c1 so as to connect the elastic bend fulcrum section 33c1 and the centering case section 31.
An exterior of the guiding section 33b has applied thereon a lapping or a polishing process, thereby improving sliding performance thereof and allowing the disc to smoothly be guided thereupon. Consequently, the disc loading force will be reduced. To be more specific, roughness of the exterior of guiding section 33b is, preferably, Ry≦6.4 μm (preferably, Ry≦1.0 μm).
According to
The inclined guiding surface 31a includes an inclined surface having two angles of inclination positioned axially one over the other, wherein each angle of inclination having a different angle, with respect to the rotation axis, from the other. An inclined surface for one of the angles of inclination located axially above the other angle of inclination will be referred to as an upper inclined guiding surface 31a1, and an inclined surface for the other angle of inclination will be referred to as a lower inclined guiding surface 31a2. Here, an upper guiding side angle of inclination θ5, which is an acute angle generated by the rotation axis J1 and the upper inclined guiding surface 31a1, and a lower angle of inclination θ4, which is an acute angle generated by the rotation axis J1 and the lower inclined guiding surface 31a2 are such that θ4<θ5.
Also, an exterior of the inclined guiding surface 31a has applied thereon the lapping or the polishing process, thereby improving sliding performance thereof and allowing the disc to smoothly be guided thereupon. Consequently, the disc loading force will be reduced. To be more specific, roughness of the exterior of the inclined guiding surface 31a is, preferably, Ry≦6.4 μm (preferably, Ry≦1.0 μm).
According to
According to
The DF1, which is a component of force: generated when the disc 50 makes contact with the inclined guiding section 2b2 of the conventional aligning claw 2b; generated by a point of the inclined guiding section 2b2 making the contact with the disc; and applied upward in axial manner to the disc 50 illustrated in
With reference to
The disc 1b, which is a disc facing the loading section 32, of the multilayer disc 1 makes contact with the contact point CP of the guiding section 33b and will be guided to the guiding section 33a. Only a point at the lower end of the central opening space 1b1 of the disc 1b makes contact with the retainer section 33a due to the retainer section side angle of inclination θ2 the retainer section 33a. Then, a restoring force, which is generated by the aligning claws 33 elastically bending radially inward due to the contact between the multilayer disc 1 and the retainer section 33a, and applied radially outward to the disc 1b, becomes a retaining force SF2. Since the retainer section 33a is tilted, an extent to which the aligning claw is forced to bend becomes great, wherein the force bending the aligning claw is in proportion to the restoring force SF2a. Consequently, the multilayer disc 1 will be accurately aligned with the chucking device.
A central opening space 1a1 of the disc 1a makes no contact with the aligning claw 33 (e.g., aligning claw 33 aligns the multilayer disc 1 with the chucking device by making contact solely with the disc 1b). While the multilayer disc 1 remains loaded on the loading section 32, the guiding section 33b and an inner surface of the central opening space 1a1 of the disc 1a are positioned near one another having a slight space therebetween in a radial manner. A situation in which a maximum misalignment occurs between the central opening space 1b1 of the disc 1b and the central opening space 1a1 of the disc 1a is when disc 1a and 1b are misaligned from each other by, in total, 0.15 mm in opposite directions while vertical thickness of each of the discs 1a and 1b is 0.6 mm. Since the retainer section 33a will be elastically bent inward in the radial direction due to the contact between the retainer section 33a and the multilayer disc 1, the guiding section side angle of inclination θ1 is to be small. Hereafter, the angle of the guiding section side angle of inclination while the multilayer disc 1 remains loaded on the loading section 32 is to be θ1a. Also, the angle of the retainer section side angle of inclination while the multilayer disc 1 remains loaded on the loading section 32 is to be θ2a. A distance between a contact point of the disc 1b and the retainer section 33a, and an apex of the inclined section 33d is to be t (mm). A minimum angle for the guiding section side angle of inclination θ1a, such that the guiding section 33b cannot make contact with the central opening space 1b1 of the disc 1b, can be calculated using the following equation; θ1a=tan−1{(0.15−t×tan θ2a)/(0.6−t)}. Therefore, the guiding section side angle of inclination θ1a is to be, preferably, greater than the value calculated by using the above equation. Further, since the size of the disc loading force DF2 is to be preferably smaller than the size of the retaining force SF2, a maximum guiding section side angle of inclination θ1a is to be approximately 45° such that the size of the disc loading section DF2 and the size of the disc retaining force SF2 become substantially equal to one another. Therefore, the guiding section side angle of inclination θ1a is to be preferably smaller than 45°. The lower side angle of inclination θ4 of the lower inclined guiding surface 31b2 in the inclined guiding surface 31b of the centering case section 31 can also be made such that it is greater than the value calculated by using the above equation and smaller than 45°. Therefore, the lower inclined guiding surface 31b2 makes contact solely with the disc 1b and guides the multilayer disc 1 to the guiding section 32. While the multilayer disc remains loaded on the loading section 32, the lower inclined guiding surface 31b2 radially overlaps with disc 1a. The exterior of the lower inclined guiding surface 31b2 faces the internal surface of the central opening space 1a1 of the disc 1a, wherein there is a slight space therebetween.
With reference to
The leveled section 1d2 provided on the downward facing surface of the disc 1d is, approximately, 0.1 mm in thickness, whereas the chamfered section 1d3 is C0.1 in width (0.1 mm×45° chamfer, or index corner). That is to say, the chamfered section 1d3 is, approximately, 0.1 mm in thickness. Therefore, in case when the leveled section 1d2 and the chamfered section 1d3 are provided, the disc 1d makes contact with the aligning claw 33 at a point 0.2 mm higher than a point at which the disc 1d and the aligning claw 33 are to make contact if not for the leveled section 1d2 and the chamfered section 1d3. Since the retainer section 33a will be elastically bent inward in the radial direction due to the contact between the retainer section 33a and the multilayer disc 1e, the guiding section side angle of inclination θ1 is to be small. Hereafter, the angle of the guiding section side angle of inclination while the multilayer disc 1 remains loaded on the loading section 32 is to be θ1b. Also, the angle of the retainer section side angle of inclination while the multilayer disc 1 remains loaded on the loading section 32 is to be θ2b. A distance between a contact point of the disc 1b and the retainer section 33a, and an apex of the inclined section 33d is to be t (mm). When such disc 1d having the maximum misalignment is to be loaded, the minimum guiding section angle of inclination θ1b, such that the guiding section 33b cannot make contact with the disc 1C, is a value calculated by using a following equation: θ1b=tan−1{(0.15−t×tan θ2b)/(0.4−t)}. Therefore, when the disc 1d having formed thereon the leveled section 1d2 and the chamfered section 1d3 is to be loaded, the guiding section side angle of inclination θ1b is preferably greater than the value calculated by using the above equation. Also, the lower side angle of inclination θ4 is to be, when the disc 1d having formed thereon the leveled section 1d2 and the chamfered section 1d3 is to be loaded, greater than the value calculated by using the above equation.
With reference to
The aligning claw 60 includes: a retainer section 61 for making contact with the disc (not illustrated in
An embodiment of a disc drive device of the present invention will be described with reference to
According to
The optical pick up mechanism 104 is a mechanism for, by using a laser beam, storing and reproducing information in the disc 102. The optical pick up mechanism 104 includes an optical system for leading a light source and the laser beam from the light source to the disc 102, and a light receiving element for receiving a light reflected off the disc 102.
The optical pick up transport mechanism 106 includes a train of gears connecting the optical pick up mechanism 104 and the optical pick up transport mechanism 106, and a motor for driving the train of gears.
The clamp mechanism 106 is located approximately at a same position as the rotation axis J1, and is operable to transport along the axis. When the disc 102 is loaded on the chucking device 103a of the brushless motor 103, then the disc 102 is aligned, and the clamp mechanism 106 is lowered axially. The clamp mechanism 106 gives pressure on the disc 102 applied axially from above the disc so as to retain the disc 102.
While the invention has been described with respect to preferred embodiment, the foregoing description is in all aspects illustrative and not restrictive. It is understood that the numerous other modifications and variations can be devised without departing from the scope of the invention.
