JPS632119A - Optical head driver - Google Patents

Abstract

PURPOSE:To attain the access with high accuracy and a high speed by providing the 1st and 2nd rolling members arranged to an optical head at a prescribed interval so as to be in contact via an elastic body and the 3rd-7th rolling members fixed to the optical head at a prescribed interval. CONSTITUTION:The 3rd, 4th, 6th and 7th rolling members 9, 10, 12, 13 are in complete contact with a guide shaft 3. Thus, the degree of freedom of the optical head is the degree of freedom turning around the shaft center of the guide shaft 3 and that going in parallel along the shaft center only. Since the 1st and 2nd rolling members 7, 8 are fixed to the other guide shaft 3' via an elastic body, the 1st and 2nd rolling members 7, 8 and the 5th rolling member 11 are in contact with the guide shaft 3' without fail. Thus, the degree of freedom of the optical head 2 turned around the guide shaft 3 is restricted, and the optical head 2 has the degree of freedom only going in parallel along the guide shaft 3 and moved radially to the optical disk 1. Thus, the access with a high speed and high accuracy is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical head driving device for an optical recording/reproducing apparatus for recording or reproducing optical information on a disk.

Conventional technology In recent years, optical disc recording and playback devices have increased in capacity.

Because it has the three main features of high-speed access and high reliability, it has attracted attention and has been the subject of much research. Among these, high-speed access technology has been improved by the development of lighter and smaller optical heads, access control technology, and optical head drive devices, and has become extremely fast. Many proposals have also been made regarding optical head drive devices, which are important for increasing access speed. (For example, Utility Model Application Publication No. 61-192167, Utility Model Application No. 6
0-3568, etc.) The optical head driving device described above will be described below with reference to the drawings.

FIG. 3 is a plan view of a conventional optical head driving device, and FIG. 4 is a cross-sectional view taken along line AA in FIG.

In FIGS. 3 and 4, 31 is an optical disk, 32 is an optical head that forms a minute light spot on the optical disk 31, and 33 is an optical head fixing member that fixes the optical head 32. Bearings 34 and 34' are provided with a certain width at one end of the optical head fixing member 33, and are slidably supported on the main guide shaft 35. Further, at the other end of the optical head fixing member 33, a rotation stopper 36 with a narrow U-shaped cross section is provided so as to sandwich a sub-guide shaft 37 provided parallel to the main guide shaft 35, Supported by friction. A driving coil 38 is provided at the end of the optical head fixing member 33 on the side of the bearings 34 and 34, and a magnetic circuit member 39 facing the driving coil 38 is provided along the main guide shaft 35. In addition, 4o is a spindle motor, 41 is an objective lens of an optical head, and the main guide shaft 35 is installed so that the objective lens moves in the radial direction of the optical disk 31.

The operation of the optical head driving device configured as described above will be explained below.

When a current is passed through the coil 38, electromagnetic force is generated in the coil due to interaction with the magnetic circuit member 39, and the optical head 32 fixed to the optical head fixing member 33 is moved by the electromagnetic force.
The optical disc 31 can be moved in the radial direction along the main guide shaft 35.

The speed is determined by directly driving the optical head 32 with electromagnetic force, and since there is no deceleration mechanism, the electromagnetic force is F, and the optical head 32 is driven directly by electromagnetic force.

If the total movable mass including the optical head fixing member, coil, etc. is M, the optical head 32 can be moved in the radial direction of the optical disk 31 at a very high speed because it can be accelerated or decelerated at an acceleration of F/M. Therefore, it becomes possible to perform so-called random access control in which the optical head is quickly moved from any position on the disk to any position on the disk for recording or reproduction.

When the parallelism between the main guide shaft 35 and the sub guide shaft 37 is not perfect, and the height of the disc and the guide shaft are equal, the distance between both guide shafts changes depending on the location, that is, the main and sub guide shaft When the shaft is attached, the optical head attachment member 33
Since the bearings 34 and 34' are widely provided,
The optical head is along the main guide axis. Optical head mounting member 3
At the U-shaped rotation stopper 36 at the other end of 3, the sub guide 3
7, the contact point between the sub guide 37 and the U-shaped rotation stopper 36 moves along the parallel U-shaped portion. Therefore, even if the optical head mounting member 33 moves, it can move smoothly without increasing friction.

In addition, if the main and subguides 35 and 37 are not perfectly parallel, and the distance between the guides is equal, and the height of the disk and the guide is different depending on the location, the optical head mounting member 33 may be When the optical head mounting member 33 is moved to , the bearings 34 and 34 are supported.
It rotates and tilts by the amount of change in the height of the sub-guide shaft 37. ,
Therefore, even if the optical head mounting member 33 moves, it can move smoothly without increasing friction.

Problems to be Solved by the Invention However, in the above-described conventional configuration, there are
It is necessary to provide a certain air gap. It is also necessary to provide a certain gap between the rotation stopper 36 and the sub-guide shaft 37. Therefore, the optical head mount 33 is not completely supported by the main guide shaft and the sub guide shaft and can be positioned freely within the gap, making it impossible to accurately position the optical head. Further, since the drive coil 38 is installed outside the main guide shaft, the optical head 32. Optical head mounting member 33. Since the center of gravity of the movable object formed by the drive coil 38 and the drive point are different, when a drive current is applied to the drive coil to move the optical head 32 at high speed, a rotational moment is generated around the center of gravity of the movable object. Due to the air gap in the bearing, the optical head 32 undergoes rotational vibration, i.e., yawing mode vibration, about an axis passing through the center of gravity of the movable object and perpendicular to the disk, which makes it difficult for accurate positioning of the optical head 32 and for servo control. have a negative impact.

Further, in this conventional configuration, the optical head 32 is fixed on an optical head mounting member 33. Therefore,
The mass of the movable object is heavy, making it unsuitable for moving the optical head 32 at high speed. Therefore, it has been considered to provide bearings 34 and 34/ and a rotation stopper 36 directly on the optical head 32, eliminating the optical head mounting member and reducing the weight, but the main guide shaft 35 is inserted into the bearings 34 and 34'. Because of this structure, the guide shaft must also be removed when installing or removing the optical head, which is not suitable for mass production or maintenance.

The present invention has been made in view of the above-mentioned conventional problems, and provides an optical head drive device that eliminates the gap in the bearing, is less likely to generate unnecessary vibrations in the yawing mode, and is highly accurate and capable of high-speed access. It is something.

Means for Solving the Problems In order to solve the above problems, the optical head drive device of the present invention has two guide shafts installed approximately parallel to each other, and a rotating optical disk located between the guide shafts. A drive coil and a magnetic circuit are respectively arranged outside between the two guide shafts, and the drive coil and the optical head are fixed. It is supported via a seventh rolling member.

1st. The second rolling member is located in the first space with a plane connecting the approximate axial centers of the two guide shafts as a boundary, and is pressed against one of the two guide shafts via an elastic body with pressure. The third . The fourth rolling member is located in the first space, and the fourth rolling member is located in the first space.
The fifth rolling member is fixed to the optical head at a predetermined interval so as to be in contact with the other axis of the guide shaft of the book, and the fifth rolling member is located in the second space and approximately in the center of the first and second rolling members. It is fixed to the optical head so as to contact the guide shaft. Also, 6th. The seventh rolling member is located in the second space and is fixed to the optical head at a predetermined interval so as to contact the other guide shaft.

Function The present invention provides a third guide shaft with a plane connecting approximately the axial centers of two guide shafts as a boundary. Fourth and sixth. Since the seventh rolling member is arranged, the third rolling member is attached to one of the two guide shafts. Fourth and sixth. The seventh four rolling members are always in contact. Therefore, the optical head only has a degree of freedom to rotate around the axis of this guide shaft and a degree of freedom to translate along the axis. On the other guide shaft, the fifth rolling member is fixed, and the first and second rolling members are fixed while being pressed through the elastic body, so that
These three rolling members are also always in contact. Therefore, the rotational degrees of freedom around the axes of the other guide shafts are restricted, the optical head has only a translational degree of freedom, and the optical head can move along the guide shafts. Even if the parallelism of the guide shaft is not accurate or the linearity is reduced, the elastic bodies of the first and second rolling members are deflected to absorb the error.
It is possible to eliminate gaps in the bearing while maintaining low friction.

Further, when a current is passed through the drive coils arranged on both sides, a driving force is generated, and the resultant force acts on the central portion of the optical head. Furthermore, since the center of gravity of the movable object consisting of the optical head and the drive coil has a substantially symmetrical shape, it can be designed at the center of the optical head. Therefore, it is possible to design the drive point and the center of gravity to almost match, so there is no unnecessary rotational moment caused by trying to rotate the movable object around the center of gravity.
This prevents unnecessary vibrations in yawing mode, enabling high-speed movement and accurate positioning of the optical head.

Embodiment An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of an optical head driving device according to an embodiment of the present invention, and FIG. 2 is a front view of FIG. 1. In FIGS. 1 and 2, 1 is an optical disk, and 2 is an optical head that forms a minute spot on the optical disk 1. In FIG. 3 and 3/ are guide shafts arranged on both sides of the optical head 20.

Reference numerals 4 and 4' denote drive coils disposed outside the guide shafts 3 and 3', and are firmly fixed to a protrusion 2a protruding from the optical head 2 with screws 6. 6 and σ are magnetic circuits for generating thrust in the drive coils 4.4', and are arranged parallel to the guide shafts 3 and 31, respectively. Reference numerals 7 and 8 denote first and second rolling members that move the optical disc 1 with a plane passing approximately through the axial centers of the two guide shafts 3 and 3 as the boundary.
The elastic support 1 is located in a space that does not include the optical head 2.
4, the first rolling member 7 contacts the guide shaft 31 with pressure, and the first rolling member 7,
It is arranged so as to have a wide interval from the second rolling member 8.

Note that the elastic support 14 is removably attached to the optical head 2 with screws or the like. Reference numerals 9 and 10 denote third and fourth rolling members; It is located in the same space as the second rolling member, is firmly fixed to the optical head 2 with a wide interval from the third rolling member 9 and the fourth rolling member 1o, and is in contact with the guide shaft 3.

11 is the sixth rolling member, which has two guide shafts 3.3'
1st degree, 2nd degree, and 2nd degree, with the plane connecting approximately the axial center of the boundary as the boundary. Third.
The fourth rolling member element is located in a space opposite to the space in which the fourth rolling member elements 8, 9, and 10 are arranged, that is, in the space containing the optical disc 1, and is located approximately at the center of the first and second rolling members 7, 8 with a guide shaft. The optical head 2 is firmly fixed to the optical head 2 so as to be in contact with the optical head 3'. Reference numerals 12 and 13 denote sixth and seventh rolling members, which are located in the same space as the fifth rolling member 11 with a plane connecting the approximate axial centers of the two guide shafts 3 and 3/ as a boundary, and are located in the same space as the fifth rolling member 11. The optical head 2 is in contact with the
is firmly fixed.

Fifth. 6th. The seventh rolling member 11, 12°130 rotation axis is located in a plane parallel to the plane of the optical disc 1. 1st. 2nd and 3rd. Fourth rolling member 7, 8
, 9.10 are in the same plane, and the fifth
．． 6th. It is arranged at an angle with the plane containing the axis of rotation of the seventh rolling member 11.12.13.

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

Third. 4th and 6th. The seventh four rolling members are in complete contact with the guide shaft 3. Therefore, the six degrees of freedom of the optical head (3 degrees of freedom in translation, 2 degrees of freedom in rotation, 3 degrees of freedom in rotation) are only the degree of freedom to rotate around the axis of the guard shaft 3 and the degree of freedom to translate along the axis. Become. On the other guide shaft 3' side, the first and second rolling members 7, 8 are fixed with pressing pressure through an elastic body, so that
The second rolling members 7, 8 and the fifth rolling member 11 always come into contact with the guide shaft 3I. Therefore, the rotational freedom of the optical head 2 around the guide shaft 3 is restricted, and the optical head 2 can move in the radial direction of the optical disc 1 with only a translational freedom along the guide shaft 3. Even if the guide shafts 3 and 3' are not completely parallel and the linearity is reduced, the elastic bodies of the first and second rolling members 7 and 8 deform to absorb the error and reduce friction. It is possible to eliminate the gap in the bearing without increasing the size.

When current flows through the drive coils 4 and 4/, an electromagnetic force is generated between the magnetic circuits 6 and 4/. The drive coils 4 and 41 are
Since it is firmly fixed to the protrusion 2a provided on the optical head 2 with a screw, the generated electromagnetic force is transmitted to the optical head without attenuation.At this time, the characteristics of the magnetic circuits 6 and σ and the drive coils 4 and 1 are If they are equal, equal electric forces will occur,
The point of application of the resultant force acts on the geometric center of the optical head 2.

- On the other hand, due to the internal structure of the optical head 2, it is possible to design the center of gravity of the optical head 2 to be the geometric center of the optical head 2, so the point of action of the resultant force of the driving force and the center of gravity of the optical head 2 can be - Therefore, there is no rotational moment around the center of gravity, and during high-speed access, the optical head can be moved to any location on the optical disk at high speed while preventing unnecessary vibrations caused by the yawing mode of rotating around the center of gravity. Record and reproduce optical information on optical discs.

When the center of gravity is not at the geometrical center of the optical head, the bare moving coils 4 and 41. The same result can be obtained even if the characteristics of the magnetic circuits 6 and q are changed.

The above is the operation when ignoring the force of the rolling member, but when considering the force, the point of application of the resultant force of the force is the point of application of the resultant force of the driving force mentioned above, and the center of gravity of the optical head. If they match, they will behave exactly the same. According to experiments, the frictional force is on the order of sg, f, and the thrust of the drive coil is 700g.
f, which can be almost ignored.

Effects of the Invention As described above, according to the present invention, by arranging the guide shaft and the drive coil on both sides of the optical head, the center of gravity of the optical head, the point of application of the resultant force of the drive force, and the rollers are located at the very center of the nine members. Since the points of action of the two resultant forces can be made to coincide, the moment of rotation of the center of gravity is eliminated, and unnecessary vibrations in the yawing mode are eliminated, making it possible to move the optical head at high speed. In addition, 3
Dimensionally the center of gravity of the optical head, the point of action of the resultant force of the driving force,! By matching the points of action of the resultant force, unnecessary vibrations in the pitching mode of the optical head can also be prevented.

In addition, since the first and second rolling members are supported by elastic supports, even if the accuracy of the parallelism and straightness of both guide shafts is rough, the errors are absorbed by the elastic body, so the rolling members The gap is always zero and there is little friction, allowing accurate positioning of the optical head. Furthermore, since the parallelism and straightness of the guide shafts may be rough, production costs can be reduced.

The first and second rolling members are fixed to the optical head with screws or the like via an elastic support. Second
By removing the rolling member 〒#, the optical head can be easily attached and detached while the guide shaft remains fixed, and the work efficiency is high.

The drive coil and the optical head are attached by screws to projections provided on the optical head. The material of the optical head is usually aluminum, so the protrusions have high rigidity, and the driving force can be transmitted from the drive coil *teφ without attenuation, making positioning servo easier.

The rotational axes of the nine roller members arranged in the space containing the optical disk with the plane passing approximately through the axial centers of the two guide shafts and the triple motherboard as the boundary are in a plane parallel to the optical disk, so the distance between the optical disk and the guide shaft is Even when the distance between the two guides is equal and the distance between the two guides is not uniform, that is, when the two guide shafts are arranged in a V-shape, the height and inclination of the optical head and optical disk do not change, resulting in good focus servo and good It is possible to obtain a light spot on the surface of the recording medium. Normally, the optical head cannot be narrowed down to a minute extent, making it impossible to perform good recording and reproduction, and it is possible to realize an excellent optical head driving device that can prevent this.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an optical head driving device according to an embodiment of the present invention, FIG. 2 is a front view of FIG. 1, FIG. 3 is a plan view of a conventional optical head driving device, and FIG. It is an AA sectional view of the figure. 1... Optical disk, 2... Optical head, 3.3'... Guide shaft, 4.4'...
・Drive coil, 5... Screw, 6, 61...
... Magnetic circuit, 7, 13... First to seventh rolling members. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 13 7th Rolling Sound 1 Year Old Figure 2 12 Hayabusa 6 Rolling Question Ao

Claims (3)

[Claims] (1) Two guide shafts installed approximately in parallel, an optical head located between the guide shafts for recording and reproducing information on a rotating optical disk, and an optical head located outside the space between the two guide shafts. The drive coil and magnetic circuit for driving the optical head are located in a first space with a plane connecting approximately the axial center between the guide shafts as a boundary, and have a drag force on one of the two guide shafts. first and second rolling members disposed on the optical head at a predetermined interval so as to be in contact with each other via an elastic body; The third and fourth rolling members fixed at a predetermined interval and the guide shaft are located in a second space with a plane connecting approximately the axial center between the guide shafts as a boundary, and are guided at approximately the center of the first and second rolling members. A fifth rolling member fixed to the optical head so as to be in contact with the shaft, and an optical member located in the second space at a predetermined interval so as to be in contact with the guide shaft that the fifth rolling member does not contact. An optical head drive device comprising sixth and seventh rolling members fixed to a head, the optical head and the guide shaft being supported via the first to seventh rolling members. (2) With the plane connecting the approximate axial centers of the two guides as the boundary,
A fifth, a sixth, a seventh arranged in a space containing the optical disc.
2. The optical head driving device according to claim 1, wherein the axial center of the rolling member is disposed within a plane parallel to the optical disk. (3) Claim 1 or 2, wherein a protrusion is provided on the optical head, and the protrusion and the drive coil are coupled with a screw or the like.
The optical head drive device described in 2.