JP2765199B2 - Optical disk drive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical disk device.

2. Description of the Related Art In recent years, optical disk devices have been used as external storage devices of computers and the like.

 Hereinafter, a conventional optical disk device will be described.

FIG. 4 is an exploded view of a conventional swing arm type optical disk device. In FIG. 4, 27 is an optical disk, 28 is a spindle motor for rotating the optical disk 27,
Reference numeral 29 denotes a condensing lens for condensing laser light for reading and writing information on the recording film of the optical disc disc 27, and reference numeral 30 supports the condensing lens 29, and roughly describes the condensing lens 29 in the tracking direction of the optical disc disc 27. A swing arm actuator for positioning, and rotates around a rotation shaft 31 arranged outside the optical disk board 27. Reference numeral 32 denotes an optical head fixing unit that houses a semiconductor laser not mounted on the swing arm actuator 30, various prisms, optical elements and sensors for detecting a tracking error and a focus error, and is fixed to the device base 33. Numeral 34 denotes a parallelogram prism provided for guiding laser light from the optical head fixing part 32 to the condenser lens 29. 36 is a condenser lens 29 in a focus direction which is an optical axis direction of the condenser lens 29.
Is a focus actuator in which a coil is wound to drive the focus actuator.

FIG. 5 is an exploded view of the swing arm actuator 30. In FIG. 5, 37a and 37b are magnetic yokes, and 38 and 39 are permanent magnets whose upper surfaces are magnetized to the N pole and S pole, respectively. Another pair is provided as the axis of symmetry. Reference numeral 40 denotes a swing arm made of a non-magnetic lightweight metal such as aluminum, and holds the coil 41. 45 is a galvanomirror provided in the optical path 44 of the laser beam from the optical head fixing part 32 for performing precise and highly sensitive tracking control, and 48 is a swing arm 40
The lens holding member 49, the condensing lens 29, and the focus coil 50 are support springs for moving the condensing lens 2a formed of four leaf springs provided in
I support. The shape of the focus coil 50 is saddle-shaped, and is suitable for straddling the magnetic yoke 51. Magnetic yoke
Numeral 51 is integrated with the opposing magnetic yoke 52, and a permanent magnet 53 is bonded to the magnetic yoke. Regarding the magnetization direction of the permanent magnet 53, the magnetic yoke 51 side has an N pole, and the magnetic yoke 52 side has an S pole.

The operation of the optical disk device configured as described above will be described below.

First, a magnetic circuit formed by the permanent magnets 38 and 39 will be described. The magnetic force line 38a coming out of the N pole passes through the magnetic yoke 37b, reaches the S pole side as shown by the arrow 39a, and then passes through the magnetic yoke 37a to reach the N pole of the permanent magnet 38 again. Coil 4
When a current is applied to 1 in the direction of arrow 42, the swing arm 40 receives a rotating force in the direction of arrow 43 according to Fleming's left hand rule. By controlling the direction of the current flowing through the coil 41 in this way, the condenser lens 29 can be driven in the direction of arrow t. However, since the swing arm 40 rotates around the rotation shaft 31 disposed outside the optical disc disk 27, the moment of inertia is large, and it is difficult to obtain sensitivity sufficient to follow the high-speed rotation of the optical disc disk 27. It is.
Therefore, in a conventional optical disc device, a galvano mirror configured with a sufficiently small moment of inertia in the optical path 44 of the laser beam
By rotating 45 in the direction of arrow 46 and oscillating the light emitted from the condenser lens 29 as shown by arrow 47, more accurate and highly sensitive tracking control is performed. In other words, the swing arm 40 is used for rough positioning of the condenser lens 29 in the tracking direction, and the Garno mirror 45 is used for precise and highly sensitive tracking control.

Next, a driving method in the focus direction will be described. FIG. 6 is an explanatory view of a mechanism for generating a driving force in the focus direction. In FIG. 6, an arrow 54 points to the focus coil 50.
When the current in the direction is passed, the direction of the magnetic force line is the arrow 55,
According to Fleming's left-hand rule, a force acts on the focus coil 50 in the direction of the arrow 56. By controlling the direction of the source flow flowing through the focus coil 50 in this manner, the fifth
The condenser lens 29 can be driven in the direction of the arrow f in the figure.

However, in the above-described conventional configuration, the swing arm 40
Is rotated about a rotation axis 31 disposed outside the optical disc disk 27, so that the condenser lens 29 is supported at a position on the swing arm 40 away from the rotation axis 31, and the moment of inertia is reduced. In addition, it is not only necessary to use a swing arm 40 for rough positioning of the condenser lens 29 in the tracking direction, and to perform two systems of control using a galvanometer mirror 45 for precise and highly sensitive tracking control. When a high-speed swing is performed, a strong driving magnetic circuit is required, and power consumption is large.

Means for Solving the Problems The present invention has been made to solve the above problems, and has a sliding rotation member rotatable about a shaft and slidably held in the axial direction, and a sliding rotation member. A rotating means for rotating the moving member, a moving means for moving the sliding rotating member in the axial direction, and a collecting means provided at a distal end portion of a part of the sliding rotating member extending in the outer peripheral direction. A light condensing means for condensing light transmitted through a light guide path provided on a shaft and an extended portion of the sliding rotation member onto an optical disc to be mounted, and an innermost circumference of the mounted optical disc; An optical disc device characterized in that the center of the shaft is arranged substantially at the center between the track and the outermost track.

According to the present invention, the light collecting means can be supported near the rotation center axis of the sliding rotation member, and the moment of inertia can be reduced.

FIG. 1 is an exploded view of an optical disk device according to an embodiment of the present invention. In FIG. 1, 1 is an optical disk, 2
Performs the sliding in the focus direction f along the axis z and the rotation in the tracking direction t about the axis z, further extends a part in the outer peripheral direction, and supports the condenser lens 3 at the position of the tip. It is a sliding rotation member. A permanent magnet 4 polarized and magnetized on the inner surface and the outer surface is attached to a lower portion of the sliding rotation member 2. Next, a driving portion of the sliding rotation member 2 will be described. 5 has a transmission hole 5a inside,
5b is a guide member having a surface polished and coated with Teflon (registered trademark) resin or the like. Reference numeral 6 denotes a center yoke made of a ferromagnetic material and arranged to face the inner surface of the permanent magnet 4 at a small distance. Reference numerals 7a and 7b denote a pair of side yokes which are formed integrally with the center yoke 6 from a high magnetic permeability material, and are disposed at positions opposing each other about the axis z. A tracking coil 8b for tracking control is wound around the focus coil 8a around the side yoke 7b.

Next, the optical system will be described. In this embodiment, a case of a magneto-optical disk device will be described as an example. 9 is a semiconductor laser, 10 is a collimator lens, and 11 is a reflection mirror for changing the optical path. Reference numeral 12 denotes a beam splitter (hereinafter abbreviated as BS), 13 denotes a 1 / 2λ plate, and 14 denotes a deflection beam splitter (hereinafter abbreviated as PBS). The optical path changing mirror 15 is located inside the sliding and rotating member 2 and moves together with the sliding and rotating member 2. Emitted from the semiconductor laser 9 and a collimator lens
The laser light 16 converted into parallel light at 10 is condensed on the recording surface of the optical disc 1 via the reflecting mirrors 11aBS12 for mirroring the optical path, the mirror 11b, the mirror 15, and the condenser lens 3. The light reflected from the optical disk 1 is condensed by the condenser lens 3, the reflection mirror 15 for changing the optical path, the reflection mirror 11, the BS 12, the 1 / 2λ plate 13
, The light is split by the PBS 14 into two components, a P-wave component and an S-wave component. The P wave component is a condenser lens
The light is condensed on the sensor 18 at 17, and the S wave component is condensed on the sensor 20 by the astigmatic lens 19. This astigmatism lens 19 is used for error detection in the focus direction,
The signal obtained from the sensor 18 is used for detecting an error in the tracking direction of the push-pull method. The magneto-optical signal is obtained as a differential output of the sensors 18,20.

An electromagnet 21 for generating an external magnetic field, which determines the magnetization direction of the optical disk recording film at the time of data recording, is arranged on the side opposite to the sliding and rotating member 2 across the optical disk 1.

FIG. 2 is a plan view of a main part of an optical disk device according to an embodiment of the present invention. The optical system is omitted in the figure. In FIG. 2, reference numeral 1a denotes an innermost track of the optical disc 1, 1b denotes an outermost track, and 1c denotes an intermediate track located between 1a and 1b. The axis z of the sliding rotation member 2 is located on the intermediate track 1c. Reference numerals 2a and 2b indicated by broken lines represent states in which the sliding and rotating member 2 accesses the innermost track 1a and the outermost track 1b, respectively.

The operation of the optical disk device of the present invention configured as described above will be described below.

FIG. 3 is a sectional view taken along the line AA in FIG. 2, and the drive magnetic circuit will be described with reference to FIG. The permanent magnet 4 has a cylindrical shape in which the outer periphery is magnetized to the N pole and the inner periphery is magnetized to the S pole.
4a is adhesively fixed to the sliding rotation member 2. With the permanent magnet 4, the center yoke 6, and the side yokes 7a and 7b,
Magnetic circuits 21 and 24 are formed. When a current is applied to the focus coil 8a in the current direction 22, the permanent magnet 4 receives a driving force in the focus direction in the direction of the arrow 23 according to Fleming's left hand rule. When a current is applied to the tracking coil 8b placed in the magnetic circuit 24 in the current direction, the permanent magnet 4 receives a driving force in the tracking direction in the direction perpendicular to the paper surface 26 according to Fleming's left-hand rule.

By controlling the direction of the current flowing through the focus coil 8a in this manner, the sliding rotation member 2 supporting the condenser lens 3 can be moved in the focus direction, and the direction of the current flowing through the tracking coil 8b can be controlled. By doing so, it is possible to rotate the sliding rotation member 2 about the axis z on the intermediate track 1c and move the condenser lens 3 in the tracking direction.

By setting the axis z of the sliding rotation member 2 on the intermediate track 1c, it becomes possible to support the condensing lens 3 near the rotation center axis of the sliding rotation member 2, and to reduce the moment of inertia. it can.

Further, since the sliding and rotating member 2 that supports the condenser lens 3 can be reduced in size and weight, the rotation time from the innermost track 1a to the outermost track 16 can be reduced, and the projection occupied by the optical disc 1 can be reduced. The moving system of the condenser lens 3 can be configured within a range not protruding from the surface, and the entire apparatus can be made compact.

Effect of the Invention As described above, the optical disc device of the present invention is configured such that the rotation center axis of the sliding rotation member that is rotatably held on the shaft that supports the light condensing means and that can slide along the axis. By being located approximately halfway between the innermost track and the outermost track of the optical disc, the light condensing means can be supported near the rotation center axis of the sliding rotation member, and the inertia momentum can be reduced. In addition, tracking access control can be performed by a single system, and even when a high-speed swing is performed, a small driving force can be used and power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is an exploded view of an optical disk device according to one embodiment of the present invention, FIG. 2 is a plan view of a main part of the optical disk device according to one embodiment of the present invention, and FIG. FIG. 4 is an exploded view of a conventional swing arm type optical disk apparatus, FIG. 5 is an exploded view of a swing arm actuator 30, and FIG. 6 is an explanatory view of a driving force generating mechanism in a focus direction. DESCRIPTION OF SYMBOLS 1 ... Optical disk board, 1a ... Innermost track, 1b ... Outermost track, 1c ... Intermediate track, 2 ... Sliding rotating member, 3 ... Condensing lens, 4 ... Permanent magnet, 5 ... Guide member, 6 Center yoke, 7a, 7b Side yoke, 8a Focus coil, 8b Tracking coil, 9 Semiconductor laser, 10 Collimator lens, 11
…… Reflecting mirror for changing the optical path, 12 …… Beam splitter,
13 ... 1 / 2λ plate, 14 ... polarizing beam splitter, 15 ...
Mirror for changing the optical path, 17: Condensing lens, 18: Sensor, 19: Astigmatism lens, 20: Sensor, 21: Electromagnet for generating an external magnetic field.

Claims (1)

(57) [Claims] 1. A sliding rotation member rotatable about a shaft and held slidably in the axial direction, rotation means for rotating the sliding rotation member, and the sliding rotation member. A moving means for moving the shaft in the axial direction, and a light collecting means which extends a part of the sliding and rotating member in an outer peripheral direction and is provided at a tip part thereof, wherein the light collecting means is provided with the shaft and the shaft. The transmitted light of the light guide path provided on the extended portion of the sliding rotation member is condensed on the optical disk to be mounted, and the axis of the shaft is located substantially in the middle between the innermost track and the outermost track of the mounted optical disk. An optical disc device having a center disposed.