JPH026134B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical head for recording and reproducing optical information that is small in size, simple in structure, and has a high response speed.

[Conventional technology]

A schematic diagram of a conventional optical head of this type is shown in FIGS. 1 and 2. In FIGS. 1 and 2, 1 is a focusing lens for focusing a light beam on the disk recording surface of an optical recording disk (not shown), 2 is a lens housing for holding the focusing lens 1, and 3 is a lens housing. 2 is a frame for movably supporting it in the focus adjustment control direction via a support spring 4; 5 is an electromagnetic coil section attached to the lens housing 2; and 6 is a magnet fixed to the frame 3. Further, in FIG. 1, 7 is a galvanometer mirror, in FIG. 2, 8 is a brake spring, 9a is an iron piece, and 9b is a track access control coil.

In such an optical head, focus adjustment control on the disk recording surface is performed by the magnetic force between the electromagnetic coil section 5 and the magnet 6, which is generated when a current sent from a control section (not shown) passes through the electromagnetic coil section 5. The lens housing 2 and the focusing lens 1 are moved up and down, and rough track access is achieved by attaching the frame 3 to the tip of a head positioner (not shown) and moving it from side to side. The track access control (within 100 μm) is based on the rotation of the galvanometer mirror 7 in the example shown in FIG. 1, and on the left-right movement of the focusing lens 1 by the track access control coil 9b and iron piece 9a in the example shown in FIG. This is achieved by changing the incident position of the light beam with respect to the focusing lens 1.

[Problem to be solved by the invention]

When using an optical head with such a configuration, if the head positioner is operated at high speed, unnecessary vibrations will occur in the galvanometer mirror 7 or the iron piece 9a and the focusing lens 1, making it impossible to accurately control minute track accesses. There were flaws. On the other hand, since the position of the light beam on the disk recording surface varies depending on the displacement of the incident position of the light beam on the focusing lens 1, the vibration of the focusing lens 1 makes it difficult to detect the position of the light beam. However, it is generally difficult to control the vibrations of the focusing lens 1, which has the drawback of not allowing accurate and high-speed access to the information track.

In addition, since the incident position of the light beam on the focusing lens 1 changes, the focusing lens 1 requires an expensive lens with little aberration even at the periphery.
a. It has a complicated structure such as the track access control coil 9b, and its dimensions in the focus adjustment control direction become large. Therefore, when forming a disk pack in which multiple disks are stacked, it is necessary to increase the spacing between each disk. This has hindered the increase in the capacity of the above-mentioned disk packs.

Furthermore, in the example shown in FIG. 1, the galvano mirror 7 is omitted, and a head positioner is used to perform minute track access control, but this has the disadvantage that high-speed tracking is not possible due to the large mass of the entire head.

In view of the above drawbacks of the conventional optical head, the present invention provides a focusing lens that is held movable only in the focus adjustment control direction, and an optical path of a light beam having an optical axis in the track access direction parallel to the disk recording surface. An optical head is configured by housing an optical head main body equipped with an optical path changer that changes the optical path in a direction perpendicular to the surface in a head outer housing so as to be movable only in the track access direction, and the optical head is used for optical recording. The head positioner is attached to the tip of a head positioner that performs track access in the radial direction of the disk, and accesses the information tracks of the optical recording disk.Furthermore, the optical head body is minutely driven and controlled in the track access direction within the head outer casing to perform minute track access. An optical head that prevents unnecessary vibrations and enables high-speed access, and an optical head that uses a displacement detector to detect the amount of displacement of the optical head body in the track access direction, enabling more accurate track access. The purpose is to provide a head.

[Means to solve the problem]

In order to achieve the above object, the optical head of the present invention is composed of a head outer casing and an optical head main body disposed within the head outer casing, and the optical head main body is configured to emit light beams parallel to the disk recording surface. an optical path converter that converts the optical path of the optical beam into a vertical direction; a focusing lens that focuses the optical beam converted in the vertical direction onto the disk recording surface; The optical head is comprised of a supported movable body and a first drive device that drives the movable body to control focus adjustment, and is parallel to the disk recording surface and located between the head outer casing and the optical head body. A second drive device for driving the optical head main body in a track access direction that is perpendicular to the driving direction of the apparatus is provided, and the second drive device drives the optical head main body in a track access direction that is perpendicular to the driving direction of the apparatus, and the second drive device drives the optical head main body in the track access direction, which is a direction perpendicular to the driving direction of the apparatus. between the inner wall surface of the upper plate and the inner wall surface of the lower plate, and between both side surfaces of the head frame that are perpendicular to the upper and lower surfaces of the head frame and parallel to the track access direction and the optical head body. A spherical member is disposed in each of the four-sided spaces formed between the facing inner wall surfaces of both side plates of the head outer casing, and the optical head main body is movable only in the track access direction within the head outer casing. The apparatus is characterized in that it includes a displacement detection section that detects a relative displacement amount of the optical head main body with respect to the head outer casing in the track access direction.

[Effect]

According to the optical head having such a configuration, the movable body holding the optical path changer and the focusing lens is movable only in the focus adjustment control direction relative to the optical head main body, and the optical head main body is movable relative to the head outer casing. Since minute displacement is possible only in the track access direction, it is easy to prevent uncontrollable vibrations and control the light beam, which has the advantage of enabling high-precision and high-speed access to the disk recording surface.

In addition, since the light beam emitted in the track access direction is diverted to the focus adjustment control direction by an optical path changer and focused on the disk recording surface by a focusing lens, the dimensions in the focus adjustment control direction are small. This has the advantage that the optical head body can be made thin and the capacity of the disk pack can be increased.

Furthermore, since a displacement detection section is provided, displacement of the optical head body in the track access direction that occurs during high-speed access by the head positioner can be immediately detected, which has the advantage of enabling faster and more precise track access. have.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a longitudinal sectional front view of the main parts of an optical head shown in one embodiment of the present invention, and the optical head itself is attached to the tip of a head positioner (not shown), and the head positioner rotates at high speed for optical recording. drive in the radial direction of the optical recording disk to access information tracks on the optical recording disk.

In FIG. 3, 10 is the optical head main body, 11
Reference numeral 12 indicates a hollow prismatic head frame having a through hole 11a on one side of the optical head main body 10, a focusing lens 12 focuses the light beam onto the disk recording surface of the optical recording disk, and 13 indicates the focusing lens 12. It is a cylindrical movable body that is held at the top and has an electromagnetic coil 14 at the bottom, and has a through hole 13a opposite to the through hole 11a on the side surface. 15 and 16 are dampers that support the movable body 13 within the head frame 11 so that it can be displaced only in the focus adjustment control direction (E-Y' direction) shown in the lower part of FIG. The magnet attached to the lower part constitutes a first driving device that drives the movable body 13 in the focus adjustment control direction together with the electromagnetic coil section 14. Reference numeral 18 denotes an optical path changer, such as a mirror, mounted on the center ball 7a of the magnet 17, and the track shown in the lower part of FIG. The optical path of the light beam in the access direction (low-low direction) is changed to a direction perpendicular to the disk recording surface, and the light beam is guided to the disk recording surface through the center of the focusing lens 12. .
Reference numeral 19 denotes a cylindrical electromagnetic coil portion attached to the head frame 11 on the opposite side to the head frame 11 in which the through hole 11a is formed. Reference numeral 20 designates a hollow rectangular head outer casing for accommodating the optical head main body 10 configured as described above, the side opposite to the through hole 11a is opened to form an opening 20a, and the focusing lens 12 is opened.
It has a through hole 20b at a position facing the . Reference numeral 21 denotes a side wall portion 2 of the head outer casing 20 on the opposite side from the opening 20a.
The magnet 21 is a circular magnet attached to the optical head 0c so as to include a cylindrical electromagnetic coil portion 19, and the magnet 21 and the electromagnetic coil portion 19 constitute a second drive device that drives the optical head main body 10 in the track access direction. 30 is a spherical member, which is attached to the head outer casing 2;
The head frame is located in the surface space between the inner wall surface 20d of the upper plate 0 and the upper surface 11b of the head frame 11, and between the inner wall surface 20e of the lower plate of the head outer casing 20 and the lower surface 11c of the head frame 11. The distance between the optical head 11 and the outer head housing is constant, so that displacement of the optical head main body 10 in the focus adjustment control direction is suppressed.

6 is a cross-sectional plan view taken along the line AA' in FIG. 3. That is, when viewed from above the focusing lens 12 in FIG.
The side wall surface 20c, the magnet 21, and the electromagnetic coil portion 19 are traversed by a plane passing through the center of the magnet 21 parallel to the track access direction (a plane perpendicular to the plane of the paper in FIG. 3), and the optical head main body 10 is This is a plan view of the interface between the upper surface 11b of the head frame 11 and the support member 30, similarly viewed across the plane parallel to the track access direction. Perpendicular to 1c,
In addition, side surfaces 11e and 11f of the head frame 11 parallel to the track access direction and the optical head main body 1
The inner wall surface 20f of the side plate of the head outer casing 20 facing 0,
Similarly to FIG. 3, a spherical member 30 is arranged in the surface space between the head frame 11 and the head outer casing 20 so that the distance between the head frame 11 and the head outer casing 20 is constant, and in the direction of the arrow shown on the right side of FIG. Displacement of the optical head main body 10 in the (Ha-Ha' direction) is suppressed.

Here, each of the four surface spaces formed between the optical head main body 10, which is a box-shaped movable body as in the present invention, and the head outer casing that covers the periphery thereof, is defined by three or more spheres ( In this example, 4 pieces)
When the optical head body is supported by the optical head body, the linear movement of the optical head body can be performed with one degree of freedom. That is, as shown in FIGS. 3 and 6, between the upper surface 11b and lower surface 11c of the head frame 11 in the optical head main body 10 and the inner wall surface 20d of the upper plate and the inner wall surface 20e of the lower plate of the head outer casing 20. , and side surfaces 11e and 11f of the head frame 11 that are perpendicular to the upper surface 11b and lower surface 11c of the head frame 11 and parallel to the track access direction, and inside the side plate of the head outer casing 20 facing the optical head main body 10. By disposing the spherical member 30 in the four surface spaces formed between the wall surfaces 20f and 20g,
The optical head main body 10 is always supported parallel to the inner surface of the head outer casing 20, and is configured to be able to move minutely only in the track access direction.

Here, the optical head main body 1 inside the head outer casing 20 for performing minute track access control will be described.
The movable range of the optical head 0 in the track access direction is approximately several hundred μm at most, and the spherical member 30 is close to the upper surface 1 of the head frame 11 in the optical head main body 10.
1b, the lower surface 11c, and the side surfaces 11e and 11f, it will not fall off as the optical head main body 10 moves minutely in the track access direction. In addition, the side surfaces 11e and 11f and the inner wall surface 20f of the side plate of the head outer casing 20,
When assembling an optical head, there is a risk of the spherical member 30 disposed between the optical head and the head outer casing 20 falling due to gravity.
This can be prevented by press-fitting the optical head main body 10 and the spherical member 30 with an excess pressure that is sufficiently greater than the weight of the spherical member 30, but this is not related to the essence of the present invention, so a detailed explanation will be omitted. . Furthermore, it is clear that various methods can be applied to the support structure of such a linear mechanism, such as the combination of well-known bearing shaft stiffness (for example, Research and Practical Application Report of the Institute of Telecommunications, Vol. 28, No. 10).
No., pp. 2189-2203, 1978).

Reference numeral 40 denotes a displacement detection section, which includes a magnet 42 attached to the outside of the head frame 11 in the optical head main body 10 via a support structure 41, and a displacement detection section attached to the inner wall surface of the head outer casing 20 via a support structure 43. The magnet 42 and the Hall element 44 are used to calculate the amount of displacement in the track access direction of the relative position of the optical head main body 10 with respect to the head outer casing 20 that occurs during high-speed access by the head positioner. The Hall element 44 can detect a change in the magnetic field strength with a change in the distance between the optical head 10 and the optical head main body 10 in the track access direction with high precision.

Next, the operation of this embodiment will be explained. By driving the head positioner in the radial direction of the optical recording disk rotating at high speed, the optical head of the present invention attached to the tip of the head positioner is moved to a predetermined position on the information track formed on the disk recording surface. accessed,
Furthermore, when the light beam is emitted from a light emitting section (not shown), the light beam enters the through hole 11 of the head frame 11 of the optical head main body 10 constituting the optical head.
a and the movable body 1 through the through hole 13a of the movable body 13.
3, is reflected at right angles by the optical path changer 18, passes through the center of the focusing lens 12, and is focused onto the disk recording surface. Here, the focus adjustment control is
Current from a control circuit (not shown) flows into the electromagnetic coil section 1.
4, the movable body 13 moves up and down with respect to the optical head main body 10 via the dampers 15 and 16 due to the magnetic force between the electromagnetic coil section 14 and the magnet 17. On the other hand, the minute drive of the optical head main body 10 in the track access direction within the head outer casing 20 is caused by the current flowing from the control circuit into the electromagnetic coil section 19 and the magnetic force between the magnet 21 and the optical recording disk section 19. Optical head body 1
0 is displaced only in the track access direction with respect to the head outer casing 20 via the support member 30.

Therefore, according to this embodiment, for the minute track access of the optical head, the optical head main body 10 is driven only in the track access direction within the head outer casing 20, and the movable body 13 is also moved toward the optical head. The main body 10 is driven only in the focus adjustment control direction, and the electromagnetic coil parts 14 and 1 drive the optical head main body 10 and the movable body 13, respectively.
9 and magnets 17 and 21, unnecessary vibrations are not generated and the control is easy.

Furthermore, since the light beam irradiated onto the disk recording surface moves in parallel in the track access direction as the optical head main body 10 is minutely driven for track access, its position can be easily detected. Furthermore, since the direction of the light beam is changed by 90 degrees by the optical path changer 18, the dimension in the focus adjustment control direction can be reduced, and the light beam always passes through the center of the focusing lens 12, which has less aberration. Therefore, an inexpensive lens can be used as the focusing lens 12.

FIG. 4 is a longitudinal sectional front view of the main parts of an optical head showing another embodiment of the present invention.
The focus adjustment control magnet 17 attached to the lower part of the head is separated from the head frame 11 and fixed to the inner wall surface 20e of the lower plate of the head outer casing 20. That is, the head frame 11 of the optical head main body 10
has an arm 11d on the inner wall opposite to the through hole 11a, and the arm 11d supports the optical path converter 18 through the through hole 13b of the movable body 13.

FIG. 5 is a cross-sectional plan view taken along the line V-V' in FIG. gap 1
7b is wide with an interval corresponding to the displacement width,
The gap 17c in the direction perpendicular to the track access direction is narrow. This is because this is a commonly used circular magnetic recording medium circuit, and if a gap is provided in the track access direction at an interval corresponding to the displacement width, the efficiency will decrease.
Therefore, according to this embodiment, the magnet 1, whose mass accounts for a larger proportion than the optical head main body 10, can be used without reducing the efficiency of the magnetic circuit for focus adjustment control.
7 can be separated, it becomes possible to significantly increase the control response speed in the track access direction. Other configurations, operations, and effects are the same as those of the previous embodiment.

FIG. 7 is a block diagram of the vibration control system in the track access direction in the optical head of the present invention. In the figure, 100 is an optical head, 101 is a movable part including the optical head main body 10, an electromagnetic coil part 19, a displacement detection part 40, etc., 102 is a displacement detection circuit connected to the displacement detection part 40, 103 is an external control circuit, 104 is a track access direction control circuit;
When the movable part 101 is displaced in the track access direction, the amount of displacement is detected by a displacement detection circuit 102, and an electromagnetic coil section for controlling the movable part 101 in the track access direction by a track access direction control circuit 104 through a control circuit 103. 1
A drive current is applied to the track access point 9 to suppress vibration in the track access direction.

〔effect〕

As described above, according to the present invention, the movable body 13 holding the focusing lens 122 is movable only in the front focus adjustment control direction with respect to the optical head main body 10, and the optical head main body 10 is Since the disc 11 can be displaced only in the track access direction, it is possible to detect and control the position of the light beam irradiated onto the disk recording surface in the track access direction without causing uncontrollable vibrations. This has the advantage of making it possible to access the recording surface of the previous disk with high precision and at high speed.

Further, since the parallel light beam emitted in the track access direction is changed to a direction perpendicular to the disk recording surface by an optical path changer 18 and focused through a focusing lens 12, the focus The dimensions in the adjustment control direction are reduced, the optical head main body 10 can be made thinner, and the capacity of the disk pack can be increased.
Since only the central portion of the focusing lens 12 is used, it has the economical advantage that an inexpensive lens can be used.

Furthermore, since the optical head main body 10, movable body 13, etc. have a simple structure and are small in weight, they have not been used in this type of optical head due to the small movable weight and the lack of freedom in the structure. It has the advantage that a solid-state driving device using a piezoelectric element or the like can also be used.

Furthermore, since the displacement detection unit 40 is provided, the displacement of the optical head body 10 in the track access direction that occurs during high-speed access by the head positioner can be immediately detected, and its control is also easy, making it possible to perform faster and more accurate optical head positioning. It has advantages such as track access.

[Brief explanation of drawings]

The drawings are provided to explain the present invention, and FIGS. 1 and 2 are schematic configuration diagrams of a conventional optical head, and FIG. 3 is a schematic diagram of a conventional optical head.
4 is a longitudinal sectional front view of the essential parts of an optical head showing another embodiment of the present invention, and FIG.
6 is an enlarged cross-sectional view in the direction of the arrow V' line, FIG. 6 is a cross-sectional plan view in the direction of the arrow A-A' in FIGS. 3 and 4, and FIG. 7 is vibration control in the track access direction in the optical head of the present invention. FIG. 2 is a block diagram of the system. DESCRIPTION OF SYMBOLS 10... Optical head main body, 11... Head frame body, 12... Focusing lens, 13... Movable body, 1
4, 19... Electromagnetic coil section, 15, 16... Damper, 17, 21... Magnet, 18... Optical path changer, 20... Head outer casing, 30... Spherical member.

Claims (1)

[Claims] 1. An optical head that is attached to the tip of a head positioner that accesses tracks in the radial direction of an optical recording disk, and records and reproduces optical information on the information tracks of the optical recording disk, which includes a head outer casing and an inside of the head outer casing. an optical head body disposed in the disk recording surface; the optical head body includes an optical path converter that converts the optical path of the light beam parallel to the disk recording surface into a vertical direction; a focusing lens for focusing on the disk recording surface; a movable body supported so as to be displaceable only in a focusing control direction perpendicular to the disk recording surface;
a first driving device that drives the movable body to control focus adjustment; A second driving device is provided for driving the optical head main body in the track access direction, which is a direction perpendicular to the track access direction, and the second driving device drives the optical head main body in the track access direction, which is a direction perpendicular to the track access direction. between the inner wall surface and the inner wall surface of the lower plate, and between both side surfaces of the head frame that are perpendicular to the upper and lower surfaces of the head frame and parallel to the track access direction, and facing the optical head main body. A spherical member is disposed in each of the four-sided spaces formed between the inner wall surfaces of both side plates of the head outer casing, so that the optical head main body is movable only in the track access direction within the head outer casing; An optical head comprising: a displacement detection section that detects a relative displacement amount of the optical head main body with respect to the head outer casing in the track access direction.