JP2667855B2 - Optical disk drive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording / reproducing apparatus, and more particularly to an information recording / reproducing apparatus having a head drive unit that is small and thin and easy to assemble.

[Conventional technology]

2. Description of the Related Art Conventionally, various guide mechanisms and drive mechanisms for positioning a head at high speed and with high accuracy in a head drive device for an information recording / reproducing device such as a CD-ROM and an optical disk file device have been considered. In order to position the head with high precision, not only a guide mechanism with high running stability that is unlikely to cause yawing, pitching and rolling is required, but also there is a strong tendency to reduce the size and weight of the device. Equipment is strongly demanded.

A related device of this type is disclosed, for example, in Japanese Utility Model Laid-Open No. 58-109860. Showa 58
In the case of the -109860 publication, the optical head is driven by a linear motor arranged below the optical head. Also, a total of four rollers are attached to the optical head, and one grooved roller and one cylindrical roller are arranged above and below the first guide shaft, and one cylindrical roller is arranged above and below the second guide shaft. By
The optical head is driven and positioned.

[Problems to be solved by the invention]

The prior art described above has a problem that the drive motor for driving the head and the guide mechanism for guiding the head are not considered in terms of size and thickness.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an information recording / reproducing apparatus having a head driving mechanism which is small, thin and easy to assemble.

[Means for solving the problem]

The above-mentioned object is to provide a rotary drive device for rotationally driving the disc, a head equipped with an optical means for reading at least information from the disc rotated by the rotary drive device, and a movement for moving the head in the radial direction of the disc. And an optical disk device comprising: a base mounted on both sides of the head as viewed from a moving direction of the head with respect to an optical unit mounted on the head; When viewed from the moving direction of at least one of the guide shaft fixed to the base so as to be arranged on both sides of the rotary shaft of the rotary drive device when viewed from the moving direction, and the both bearing means. A driving coil supported by the head on the outside, and a loop passing through the inside of the driving coil and the driving coil as viewed from the moving direction. By providing a magnetic circuit provided and a magnet in the magnetic circuit, bending a base end portion along the moving direction substantially vertically, and forming the bent base portion as an outer magnetic circuit viewed from the moving direction. To be achieved.

[Action]

By arranging the head on which the optical means is mounted, the bearing means, and the motor for driving the head in order with respect to the center of rotation of the disk toward both outwards as viewed from the moving direction of the head, the apparatus can be mounted on the disk surface. Thin in the direction perpendicular to the In such a structure, the structure which also serves as a magnetic circuit by bending the base portion substantially vertically reduces the number of parts for attaching the magnetic circuit to the base,
Device thickness direction (direction perpendicular to the disk surface) and width direction (direction parallel to the disk surface and perpendicular to the head movement direction)
Prevent the increase in size. In addition, in the above-described structure intended to be thinned, it is possible to configure the magnetic circuit at the end portion in the width direction of the base, and to prevent an increase in size in the width direction.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view including a partial cross-sectional view of an information recording / reproducing apparatus which is an embodiment of the present invention. In FIG.
Is an information recording disk (optical disk in this embodiment), and a transparent material such as polycarbonate (PC resin) is used as a material. The lower part of the information recording disk is covered with a transparent protective layer, pits representing digital information are engraved on it, and a reflective surface is created by aluminum evaporation, and a transparent protective film is applied above the pit row. (Not shown). As the information recording disk, for example, a track formed spirally or concentrically, a track with or without a groove, and the like can be used. Information recording disk 1 is sub-base 2
It is rotationally driven by the disk drive motor 3 mounted above. The disk drive motor 3 is a disk motor driver.
Driven by 16.

Reference numeral 4 denotes an optical head, which includes optical means for recording / reproducing (objective lens 7, focusing of the objective lens on the recording surface of the information recording disk 1, and precisely in the vertical and radial directions of the disk). It has a built-in objective lens actuator 8) to drive it. The semiconductor laser is driven by the semiconductor laser driver 17 so as to always obtain a stable output. The optical head 4 can be moved in the radial direction of the information recording disk 1 by a tracking linear servomotor 5 arranged on the sub-base 2, and a so-called coarse access for roughly positioning the track by moving the entire optical head. Perform the operation. Tracking linear servo motor 5
Are driven through a servo control circuit 10 and a tracking servo motor driver 11 based on a command from the system control microprocessor 9. At this time, the speed of the optical head is controlled by the output of the optical head speed sensor 6. Similarly, the objective lens actuator 8 is driven by the objective lens actuator focus coil driver 14 and the objective lens actuator track coil driver 15, and the objective lens 7 focuses on the recording surface of the information recording disk 1. In addition, a tracking operation is performed precisely in the track direction. The focusing operation and the precision tracking operation of the objective lens are performed by amplifying and calculating the output of a photodetector (not shown) built in the optical head 4 by a preamplifier 12 and a signal processing circuit 13 to generate a control signal. This is performed by driving the lens actuator 8.

FIG. 2 is an enlarged view of a recording and reproducing optical system built in the optical head 4 of FIG. 1 are the same as those in FIG. In FIG. 2, a pit 23 representing digital information is engraved on the information recording disk 1. The light 26 emitted from the semiconductor laser 18 passes through the diffraction grating 19, is orthogonally polarized by the half mirror 20, passes through the collimating lens 21, is further orthogonally polarized by the reflecting prism 22, and passes through the objective lens 7. Focus on the surface of the pit 23 of the information recording disk 1. The light reflected from the pit surface passes through the objective lens 7 again, is polarized at a right angle by the reflecting prism 22, passes through the collimating lens 21, the half mirror 20, and the plano-concave lens 24, and then is incident on the photodetector 25. Tie the statue. Reference numeral 8 denotes an objective lens actuator which performs focusing by driving the objective lens 7 in a direction perpendicular to the surface of the information recording disk 1 and drives the objective lens 7 in a radial direction of the information recording disk 1. Perform precision tracking. The photodetector 25 is an element for converting the return light from the information recording disk 1 into an electric signal, and detects a focus error signal and a tracking error signal based on the magnitude of the output of the obtained electric signal. , A focusing operation and a tracking operation are performed. Also a photo detector
At 25, a digital signal on the information recording disk surface is also detected at the same time.

FIG. 3 is a front view of an information recording / reproducing apparatus according to one embodiment of the present invention. In FIG. 3, an information recording disk (not shown) is received by a turntable 27 and is rotationally driven by a disk drive motor 3 fixed on a sub-base 2. The optical head 4 is equipped with only an objective lens actuator 8 and a reflection prism (not shown) for driving the objective lens 7 in the focusing direction and the tracking direction, and includes other optical elements such as a semiconductor laser and a photodetector. The system is incorporated in a separate fixed optical system 28 fixed on the sub-base 2. Therefore, the weight of the optical head is reduced, and the access speed can be increased. The optical head 4 is supported by a total of two guide shafts, a first guide shaft 29 and a second guide shaft 30. The sub-base 2 employs a sheet metal structure for cost reduction. A part of the sub-base 2 is bent to form a shaft pedestal (not shown), and the first guide shaft 29 and the second guide shaft 30 are fixed by a shaft retainer 31 and a screw 32. This situation will be described with reference to FIG. FIG. 4 is a view including a partial cross section viewed from the direction A in FIG. The sub-base 2 is provided with a base for a guide shaft by bending a part of the sub-base 2 in a right angle direction like 2 'or 2 ", performing surface cutting, and receiving a first guide shaft 29 and a second guide shaft 30, The first guide shaft 29 and the second guide shaft 29
Fix the guide shaft 30.

The optical head 4 is partially supported by a cylindrical bearing composed of 33 and 34.

A cylindrical outer cylinder 33 is press-fitted into the optical head 4 with a through hole, and a ball retainer 34 incorporating a number of precision steel balls is rollingly engaged between the first guide shaft 29 and the outer cylinder 33. I do. FIG. 5 shows a detailed view thereof. The outer cylinder 33 is press-fitted into an optical head (not shown). A large number of precision steel balls 52 are incorporated in the ball retainer 34, and rollingly engage between the outer cylinder 33 and the first guide shaft 29. Accordingly, in FIG. 3, when the optical head 4 makes a displacement of 1 with respect to the first guide shaft 29, the ball retainer 34 moves to the first guide shaft 29.
A displacement of half the size of 29 is made. Since the optical head 4 rolls with a large number of precision steel balls, stable running with small yawing and pitching can be obtained. Further, the overall length of the ball retainer 34 is longer than the axial width of the optical head 4, and the span for supporting the optical head 4 is long, so that the ball retainer 34 is strong against the overturning moment generated in the optical head 4 and stable running can be obtained. .

With respect to the second guide shaft 30, the optical head 4 is supported by a fixed roller 35 attached to the optical head 4 and a preload roller (not shown). The manner of attachment will be described with reference to FIG. FIG. 6 is a cross-sectional view taken along the center of the objective lens 7 and perpendicular to the first guide shaft 29 in a cross section A′-A ″ viewed from the direction A in the embodiment of the present invention shown in FIG. The fixed roller 35 is pressed into the pin 36, the collar 37 is pressed, and the pin 36 is pressed into the optical head 4. On the other hand, the preload roller 38 is
A part of the preload spring 39 is bent into a cylindrical shape, and a pin
Secure by pressing 40 in. Preload spring 39 is screw
Fix to the optical head by 41. FIG. 7 shows in detail how the preload roller is in contact with the guide shaft by the preload spring. FIG. 7 is a detailed view of the preload roller mechanism of FIG. The optical head 4 is supported by a fixed roller 35 and a preload roller 38 with the second guide shaft 30 interposed therebetween. In order to understand this situation, FIG. 8 is obtained by viewing a cross section passing through the axial center of the second guide shaft 30 in FIG. 3 from the direction B.
As shown in FIG. 8, the optical head 4 is supported by a fixed roller 35 on a second guide shaft 30 while being supported by a roller.
By 38, a preload is applied in the direction of arrow F, and a good guide system without play can be constructed. In this embodiment, the cylindrical bearing disposed on the first guide shaft is responsible for the main linear motion of the optical head, and realizes a guide mechanism with small yawing and pitching. Further, a method is adopted in which rolling of the optical head is suppressed by a fixed roller and a preload roller disposed above and below the second guide shaft. For this reason,
Even if the second guide shaft is fixed to the first guide shaft in a state where the parallelism is slightly maintained in a horizontal plane, the smoothness of the movement of the optical head is not impaired.

Next, a tracking linear servomotor for driving the optical head in the radial direction of the information recording disk will be described with reference to FIG. The tracking linear servo motor includes a drive coil and a magnetic circuit. The drive coil 42 is formed by winding a copper wire around a bobbin 43 in a multilayer shape, and the bobbin 43 is screwed (not shown) to the head 4.
The magnetic circuit includes an outer yoke, a center yoke, a side yoke, and a magnet. A first outer yoke 2 is formed by bending a part of the sub-base 2. Reference numeral 44 denotes a second outer yoke, on which the S pole side of a plate-like magnet 45 is bonded. The second outer yoke 44 is screwed to the first outer yoke 2
Fixed to Two sets of side yokes, in which the plate-shaped iron piece is bent into a U-shape, are passed through a first inner yoke 47 and a second inner yoke 48 in which a part of the plate-shaped iron piece is bent into an L-shape. At 49, the outer yoke and the inner yoke are pressed so as to be sandwiched from both ends, and are fixed to the first outer yoke with screws 50. With such a magnetic circuit configuration, it is possible to provide a low-cost tracking linear servomotor with good assemblability. A gap is provided between the first inner yoke 47 and the second inner yoke 48 and the bobbin 43 so that the optical head 4 can travel in a non-contact state with the first inner yoke 47 and the second inner yoke 48.

The magnetic circuit described above is shown in detail in FIG. The arrows in FIG. 9 indicate the direction of assembly.

Here, the first tracking linear servomotor arranged on the first guide shaft 29 side has been described.
The same applies to the second tracking linear servomotor disposed on the side of the second guide shaft 30, and a description thereof will be omitted.

In the embodiment of the present invention shown in FIG. 3, when the optical head 4 is driven by only one tracking linear servomotor, a tracking linear servomotor is disposed on the first guide shaft 29 side. This, as mentioned earlier,
The guide mechanism composed of the outer cylinder 33 and the ball retainer 34 disposed on the first guide shaft 29 is strong against the overturning moment and can achieve stable running with small yawing and pitching. This is because the running stability of the optical head 4 is good.

As shown in FIG. 6, in the present embodiment, the first guide shaft 29
And a reflection mirror 22 on a line connecting the center of the second guide shaft 30
Try to match the center. This is because the optical axis deviation can be minimized even if the rolling of the optical head occurs. Ideally, it is desirable to arrange the reflection mirror 22 at the midpoint between the first guide shaft 29 and the second guide shaft 30.

Next, another embodiment of the head drive device in the information recording / reproducing apparatus of the present invention will be described with reference to FIGS. 10 to 15. FIG. 10 is a front view including a partial cross section of another embodiment of the present invention. In FIG. 10, the information recording disk 1 is rotationally driven by a disk drive motor (not shown). The optical head 4 is equipped with only an objective lens actuator 8 and a reflection prism (not shown) for driving the objective lens 7 in the focusing direction and the tracking direction, and other optical elements such as a semiconductor laser and a photodetector. The system is
It is incorporated in a separate fixed optical system (not shown) fixed on a sub-base (not shown). Therefore, the weight of the optical head is reduced, and the access speed can be increased. The optical head 4 is supported by a total of two guide shafts, a first guide shaft 29 and a second guide shaft 30.

A through hole is made in the optical head 4, and two slide bearings 53 are fixed to the optical head 4 by screws (not shown).
The optical head 4 slides on the first guide shaft 29 by the slide bearing 53.

With respect to the second guide shaft 30, the optical head 4 is supported by a fixed roller 35 attached to the optical head 4 and a preload roller (not shown). The manner of attachment will be described with reference to FIG. FIG. 11 is a view of the cross section AA ′ seen from the direction B in the direction perpendicular to the first guide shaft 29 through the center of the objective lens 7 in the embodiment of the present invention shown in FIG. is there. The fixed roller 35 is press-fitted into the pin 56, and an E-ring 57 is fitted in a groove (not shown) formed in the pin 56 so that the fixed roller 35 does not shift, and the pin 56 is press-fitted into the optical head 4. On the other hand, the preload roller 38 has a direction of applying a preload to the second guide shaft by a mechanism using a preload spring. FIG. 12 shows a state in which the preload roller is in contact with the guide shaft by the preload spring. The optical head 4 includes a fixed roller 35 and a preload roller 38.
Therefore, the second guide shaft 30 is supported. The preload roller 38 is pressed into the pin 58, and an E-ring 57 is fitted in a groove (not shown) formed in the pin 58 so that the preload roller 38 does not shift, and the pin 58 is pressed into the first block 59. A first leaf spring 61 and a second leaf spring 62 are placed so as to sandwich the first block 59 and the second block 60, and a spring retainer 63 is applied thereon, and they are fixed with screws 64. The second block is a screw
With 65, it is fixed to the optical head 4.

FIG. 13 is a view of the preload roller mechanism in FIG. 10 viewed from the direction of arrow C. As shown in FIG. 13, the optical head 4 is supported on the second guide shaft 30 by a fixed roller 35, and is preloaded in the direction of arrow F by the preload roller 38, so that a good guide without play is provided. The system can be configured.

FIG. 14 is a view of the preload roller mechanism of one embodiment of the present invention shown in FIG. 10 as viewed from the back. The preload roller 38 rolls while receiving a preload on the second guide shaft 30.

Next, the slide bearing will be described in detail with reference to FIG. FIG. 15 is a diagram showing a cross section of the sliding bearing engaged with the first guide shaft in the embodiment of the present invention shown in FIG. A through hole is made in the optical head 4, and two slide bearings 53 are fixed to the optical head 4 with screws 66. The optical head 4 slides on the first guide shaft 29 by the slide bearing 53. 42 is a drive coil and 43 is a bobbin, which will be described later. When the shaft diameter of the first guide shaft 29 is d ₀ and the inner diameter of the end surface 67 of the slide bearing 53 on the bobbin 43 side is d ₂ , d ₂ > d ₀ . Also, the inner diameter of the exposed end face 68 of the plain bearing 53 is
When the d _1, taken up in d _1> d _2, the holes in the sliding bearing 53 is provided with a smooth curved surface portion of radius R. In this case, good sliding characteristics can be obtained.

In this embodiment, the cylindrical bearing disposed on the first guide shaft is responsible for the main linear motion of the optical head, and realizes a guide mechanism with small yawing and pitching. Further, a method is adopted in which rolling of the optical head is suppressed by a fixed roller and a preload roller disposed above and below the second guide shaft. For this reason, even if the second guide shaft is fixed to the first guide shaft in a state where the parallelism is not maintained in a horizontal plane, the smoothness of the movement of the optical head is not impaired. .

Next, a tracking linear servomotor for driving the optical head in the radial direction of the information recording disk will be described with reference to FIG. The tracking linear servo motor includes a drive coil and a magnetic circuit. The drive coil 42 is formed by winding a copper wire in a multilayer shape around the bobbin 43,
The bobbin 43 is adhered to the optical head 4. The magnetic circuit includes an outer yoke 54, a magnet 45 having an S pole side adhered to the outer yoke 54, a sector shape of a cross section, a first guide shaft 29 also serving as a center yoke, and the first guide shaft 29 and the outer yoke. Side yoke that connects the yoke 54
It consists of 55. The cross-sectional shape of the magnetic circuit is as shown in FIG. The first guide shaft 29, which also serves as a center yoke, is passed through the bobbin 43, the outer yoke 54 is connected by a side yoke (not shown), and the outer yoke 54 is screwed to the sub-base 2 (not shown). Zu) A gap 69 is provided between the first guide shaft 29 and the bobbin 43 as shown in FIG. 15, and the optical head 4 is supported only by the slide bearing 53.

In this embodiment, a tracking linear servomotor is arranged on the side of the first guide shaft 29. The guide mechanism composed of slide bearings arranged on the first guide shaft has a long support span of the optical head, is strong against the overturning moment generated in the optical head, and has stable yawing and pitching. This is because the driving stability of the optical head is better when the one guide shaft side is driven.

In this embodiment, as shown in FIG. 11, the magnet 45 has a fan-shaped cross section and a central angle of 130 °. Therefore, the effective drive coil length is
36%. In the first embodiment shown in FIGS. 3 to 9, the ratio is 26%, and this embodiment is more efficient. Further, in the present embodiment, since the mechanism that also serves as the center yoke and the guide shaft is adopted, the head drive device becomes compact and there is an advantage that its dimension in the width direction becomes small.

As shown in FIG. 11, in this embodiment, the first guide shaft 29
Also, the center of the reflection mirror 22 is made to coincide with the line connecting the centers of the second guide shafts 30. This way,
This is because even if rolling occurs in the optical head, the optical axis deviation can be minimized. Ideally, it is desirable to arrange the reflection mirror 22 at the midpoint between the first guide shaft 29 and the second guide shaft 30.

〔The invention's effect〕

According to the present invention, the head on which the optical unit is mounted, the bearing unit, and the motor for driving the head are sequentially configured with respect to the rotation center of the disk toward both outwards when viewed from the moving direction of the head. In addition, the thickness of the device can be reduced. Further, since the magnetic circuit can be formed at an end portion in the width direction of the base, an increase in size in the width direction can be prevented. Therefore, it is possible to reduce the thickness and size of the device.

[Brief description of the drawings]

FIG. 1 is a perspective view including a partial sectional view of a head driving device in an information recording / reproducing apparatus according to one embodiment of the present invention, and FIG. 2 is a recording / reproducing apparatus incorporated in the optical head 4 of FIG. FIG. 3 is an enlarged view of an optical system, FIG. 3 is a front view of a head driving device in an information recording / reproducing apparatus according to one embodiment of the present invention, FIG. 4 is a side view including a partial cross-sectional view of FIG. 3, and FIG. FIG. 3 is an enlarged view of the cylindrical bearing shown in FIG. 3, and FIG. 6 is a sectional view taken along line A′-A ″ of FIG.
FIG. 7 is a detailed view of the preload roller mechanism of FIG. 3, FIG.
FIG. 9 is a B view including a partial cross-sectional view of FIG. 3, FIG. 9 is a detailed view of the magnetic circuit of FIG. 3, and FIG. Front view of the 11th
FIG. 10 is a sectional view taken along the line A′-A in FIG. 10, and FIG.
FIG. 13 is a detailed view of the preload roller mechanism shown in FIG. 13, FIG. 13 is a C view of the preload roller mechanism in FIG. 10, FIG. 14 is a rear view of the preload roller mechanism in FIG. 10, and FIG. It is sectional drawing of a sliding bearing. 1 ... information recording disk, 2 ... sub-base, 2 ', 2 "
...... Guide shaft base, 2 ... First outer yoke, 3
...... Disk drive motor, 4 ...... Optical head, 5 ...... Tracking linear servo motor, 6 …… Optical head speed sensor, 7 …… Objective lens, 8 …… Objective lens actuator, 9 …… System control micro Processor, 10 servo control circuit, 11 tracking linear servo motor driver, 12 preamplifier, 13
…………………………………………………………………………………………………………………………………… 対 物 対 物 対 物, 15… 対 物 16 15 16 16 16, 16… 16 16 16 16
17 ... Semiconductor laser driver, 18 ... Semiconductor laser, 19
...... Diffraction grating, 20 ... Half mirror, 21 ... Collimate lens, 22 ... Reflection prism, 23 ... Pit, 24 ... Plano-concave lens, 25 ... Photodetector, 26 ... Light, 27 ... Turn Table, 28 …… Separate fixed optical system, 29 …… First guide shaft,
30: 2nd guide shaft, 31: Shaft retainer, 32: Screw, 33
... outer cylinder, 34 ... ball retainer, 35 ... roller, 36 ...
Pins, 37 ... Collar, 38 ... Preload roller, 39 ... Preload spring, 40 ... Pin, 41 ... Screw, 42 ... Drive coil, 43 ...
... bobbin, 44 ... second outer yoke, 45 ... magnet, 46 ... screw, 47 ... first inner yoke, 48 ... second inner yoke, 49 ... side yoke, 50 ... screw,
51 …… Optical head stopper, 52 …… Precision steel ball, 53 …… Slide bearing, 54 …… Outer yoke, 55 ……
Side yoke, 56 ... pin, 57 ... E-ring, 58 ... pin, 59 ... first block, 60 ... second block, 61 ...
1st leaf spring, 62 ... 2nd leaf spring, 63 ... spring retainer, 64
…… Screw, 65 …… Screw, 66 …… Screw, 67 …… The end face of the slide bearing on the bobbin side, 68 …… The end face of the slide bearing on the exposed side,
69 ... gap, 70 ... speed detection coil, 71 ... bobbin, 72
...... Magnet.

Claims (1)

(57) [Claims] 1. A rotary drive device for rotationally driving a disk,
An optical disk apparatus comprising: a head having an optical means for reading at least information from a disk rotated by the rotation drive device, and a moving means for moving the head in a radial direction of the disk on a base, The moving means includes bearing means fixed to both sides of the head when viewed from the moving direction of the head with respect to the optical means mounted on the head, and the rotation driving device when viewed from the moving direction. A guide shaft fixedly mounted on the base so as to be disposed on both sides of a rotation shaft, a drive coil supported on the head at an outside of the at least one of the two bearing means as viewed from the moving direction, A magnetic circuit provided to form a loop passing through the inside of the drive coil and the outside of the drive coil as viewed from the moving direction, and a magnet provided in the magnetic circuit. An optical disc device, comprising: a base end portion along the moving direction is bent substantially vertically, and the bent base portion is an outward magnetic circuit viewed from the moving direction.