JPH071552B2 - Optical head - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head for recording / reproducing or erasing information on / from an information track formed on a recording medium.

2. Description of the Related Art In general, an optical disk drive device has an objective lens driving unit for moving an objective lens in a focus direction and a tracking direction, and an optical unit including the objective lens driving unit, for making a light spot follow an information track. It consists of access means to transfer to a truck. The objective lens drive means and the access means generally have a structure in which a movable coil is arranged in the magnetic flux of a magnetic circuit and a driving thrust is generated by passing an electric current through the movable coil.

On the other hand, in recent years, as performance requirements for an optical disk drive device, it has been desired that the size and thickness of the optical disk drive device be reduced and that the search be performed at high speed.

For this purpose, conventionally, the optical unit is separated, and only a part of the optical components such as the objective lens driving means and the reflection mirror are mounted on the access means to reduce the weight of the transfer section, and the separation optical system for performing high-speed search. A head has been devised. Moreover,
As disclosed in Japanese Patent Application No. Sho 63-220941, there has been proposed an optical head aiming at further miniaturization and thinning and high-speed retrieval by sharing the magnetic circuit of the objective lens driving means and the access means. An example of this prior art will be described with reference to FIGS.

FIG. 5 is an exploded perspective view, FIG. 6 is a top view, and FIG. 7 is B.
It is a -B 'sectional view.

5 to 7, the X direction is a direction orthogonal to the information track of the recording medium (called a tracking direction), and the Y direction is a direction perpendicular to the recording medium (called a focusing direction).

Reference numeral 101 denotes a recording medium, which is an optical disc on which spiral or concentric information tracks are formed. A disk motor 102 is a motor for mounting and rotating the recording medium 101. 1
A fixed optical unit 03 is a fixed optical unit in which a semiconductor laser that serves as a light source, a detector that detects reflected light from the recording medium 101, an optical element such as a prism that collimates a light beam from the semiconductor laser into parallel light, and the like are housed in a fixed member. Yes, it is fixed to the side yoke A116 with screws. Reference numeral 104 denotes an objective lens that focuses the light beam on the recording medium 101. A mover bobbin 105 accommodates the objective lens 104, and is wound with two focus coils 105a for driving the objective lens 104 in the Y direction and two tracking coils 105b for driving the objective lens 104 in the X direction. Ten
Reference numeral 6 denotes a focus leaf spring, which is composed of a spiral focus leaf spring and a dipping rubber that damps resonance of the focus leaf spring, and each is fixedly bonded to the outer peripheral portion of the cylindrical portion of the mover bobbin 105. 107 is a carriage,
The peripheral portions of the two focus leaf springs 106 are bonded and fixed on the surface on the recording medium 101 side in the Y direction and the surface on the opposite side. Reference numeral 108 denotes a bearing A, which has two cylindrical plain bearings formed on both ends thereof and is fixed to the carriage 107 by adhesion. Reference numeral 109 denotes a bearing B, which restricts rotation of the carriage 107, and is fixed to the carriage 107 by adhesion. Reference numeral 110 denotes a reflecting mirror, which is a mirror for reflecting the light beam emitted from the fixed optical unit 103 in the X direction in the Y direction. 111 is an access coil bobbin A, to which the reflection mirror 110 is adhered and fixed,
Access coil 111a for driving the carriage 107 in the X direction
Is wound in a rectangular shape and is fixed to the carriage 107 by adhesion. An access coil bobbin B 112 has an access coil 112a wound in a rectangular shape similarly to the access coil bobbin A111, and is fixed to the carriage 107 by adhesion. Reference numeral 113 denotes a magnet, which constitutes a magnetic circuit together with the back yoke 114, the facing yoke 115, the side yoke A116, and the side yoke B117, and drives the carriage 107 in the X direction by the electromagnetic force of the access coils 111a and 112a. The mover bobbin 105 is driven in the Y direction and the X direction by electromagnetic force with the tracking coil 105b. Reference numeral 118 is a guide shaft, and together with bearing A108 and bearing B109, carriage 10
7 is slidably supported in the X direction. A guide shaft support spring 119 is screwed and fixed to the side yoke B117 to fix the guide shaft 118 to the side yoke B117.

In addition, the focus coil 105a and the tracking coil 105b
The movable unit moved by the driving force generated in the access coils 111a and 112a is mainly composed of two movable units. The first is movable unit A,
The objective lens 104 is supported by the focus leaf spring 106,
It is a unit integrally configured by a mover bobbin 105, a focus coil 105a, and a tracking coil 105b. The second is the movable unit B, which is the carriage 107 and the bearing A.
108, bearing B109, reflection mirror 110, access coil bobbin
A111, the access coil bobbin B112, and the access coils 111a and 112a are integrally formed, and the vibration characteristic in the Y direction, that is, the focus characteristic is the mass of the movable unit A and the Y of the focus leaf spring 106.
It has a one-degree-of-freedom vibration characteristic determined by the directional rigidity. Also,
The vibration characteristic in the X direction, that is, the tracking characteristic or the access characteristic is a vibration characteristic of a two-degree-of-freedom system having resonance and anti-resonance points determined by the mass of the movable unit A, the rigidity of the focus leaf spring 106 in the X direction, and the movable unit B.

Regarding the optical head of the conventional example configured as described above,
The operation will be described below.

First, when drive power is supplied to the focus coil 105a, the focus coil 105a is moved to Y
Driving force is generated in the direction. At this time, since the spiral portion of the focus leaf spring 106 that supports the movable unit A with respect to the movable unit B is sufficiently soft in the Y direction, the spiral portion of the focus leaf spring 106 is deformed, so that the movable unit A moves in the Y direction. Move. As a result, the objective lens 104 moves in the focus direction and focus control is performed.

On the other hand, when a drive current flows through the tracking coil 105b,
A driving force is generated in the X direction by the electromagnetic action of the tracking coil 105b with the magnetic circuit. At this time, the movable unit A and the movable unit B move integrally until near the anti-resonance frequency, and only the movable unit A moves above the resonance frequency band higher than that, and tracking control is performed.

Further, when a drive current flows through the access coils 111a and 112a, a drive force is generated in the X direction by the electromagnetic action with the magnetic circuit in the access coils 111a and 112a. At this time, contrary to the case of the tracking coil 105b, the movable unit A and the movable unit B move integrally until near the anti-resonance frequency, so that only the movable unit B moves above the high resonance frequency band. Access is made.

With such a configuration, it is possible to reduce the weight of the transfer unit and the thickness of the optical head in accordance with the sharing of the magnetic circuit.

However, in the conventional embodiment, since the vibration characteristic in the tracking direction is the two-degree-of-freedom system, the tracking control and the access control are instable as compared with the one-degree-of-freedom system. Was. That is, the focus leaf spring 10
When the rigidity of 6 in the X direction is increased, the movable unit A and the movable unit B move integrally during access,
The movement of the objective lens is small and the access operation is stable, but
During tracking, the movable mass increases and tracking sensitivity decreases, and bearing A108 and bearing B109 and the guide shaft
Tracking control was unstable due to sliding friction with 118. On the other hand, when the rigidity of the focus leaf spring 106 in the X direction is reduced, the tracking control is stable, but the movable unit A sways during access and the access operation becomes unstable, resulting in a long search time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above conventional problems, and provides an optical head having a stable tracking control and suitable for high-speed search in an optical head sharing a magnetic circuit for focus, tracking, and access. To aim.

Means for Solving the Problems Technical means of the present invention for solving the above problems include a movable element bobbin holding an objective lens for condensing a light beam on an information track of a recording medium, and the objective lens for the recording medium. A focus coil fixed to the mover bobbin that is driven in a direction perpendicular to the track, a tracking coil fixed to the mover bobbin that drives the objective lens in a direction orthogonal to the information track, and an information track by transfer guide means. A carriage guided to be movable in a direction orthogonal to
Elastic holding means connected to the mover bobbin and the carriage, for elastically holding the mover bobbin on the carriage, and tracking restricting means for restricting movement of the mover bobbin in a direction orthogonal to the information track. An access restricting unit that restricts the movement of the carriage, and a magnetic circuit that supplies a magnetic flux commonly to both the focus coil and the tracking coil to generate a driving force, and operates the access restricting unit during tracking. To fix the carriage, and to operate the tracking restricting means at the time of access so as to fix the mover bobbin and the carriage, the restricting operation and the restricting releasing operation of the tracking restricting means and the access restricting means. It is characterized by the fact that and.

The present invention has the above-described configuration, and during tracking, the access restricting means is operated to fix the carriage and only the mover bobbin moves in the tracking direction. Therefore, the mass of the mover bobbin and the spring constant of the elastic holding member in the tracking direction. The tracking characteristic of the secondary system is determined by, and at the time of access, the tracking restricting means is operated to fix the mover bobbin and the carriage so that they can be integrally accessed. It is possible to provide an optical head which is excellent in tracking control characteristics and faster in access as compared with the conventional one, since it is possible to prevent the fluctuation of the optical axis.

Example An optical head according to an example of the present invention will be described below with reference to the drawings.

1 is an exploded perspective view, FIG. 2 is a top view, and FIG. 3 is a sectional view taken along the line AA ′ in FIG. 1 to 3, the X direction is the tracking direction and the Y direction is the focus direction.

Reference numeral 1 is a recording medium, which is an optical disk having spiral or concentric information tracks formed thereon. Reference numeral 2 is a disk smoke, which is a motor for mounting the recording medium 1 and rotating the same. A fixed optical unit 3 includes a semiconductor laser as a light source and a recording medium 1.
A detector for detecting the reflected light from the optical fiber, an optical element such as a prism for collimating the light beam from the semiconductor laser into parallel light, and the like are housed in a fixing member, which is fixed to the side yoke A21 by screws. An objective lens 4 focuses the light beam on the recording medium 1. A mover bobbin 5 accommodates the objective lens 4, and a focus coil 6 for driving the objective lens 4 in the Y direction and a tracking coil 7 for driving the objective lens 4 are fixed. An elastic holding member 8 is composed of a focus leaf spring 8a movable in the Y direction, a tracking leaf spring 8b movable in the X direction, and a connecting portion 8c connecting the focus leaf spring 8a and the tracking leaf spring 8b. A magnetic attraction plate 9 is fixed to the connecting portion 8c. The movable element bobbin 5 is fixed to the tip of the focus leaf spring 8a of the elastic holding member 8, while the tip of the tracking leaf spring 8b is fixed to the fixed plate 10. Thus, the mover bobbin 5 is held by the elastic holding member 8 so as to be movable in the X and Y directions. Reference numeral 11 denotes a carriage. A bearing A12, which is a cylindrical sliding bearing, and a bearing B13 that restricts the rotation of the carriage 11 are adhesively fixed to both ends, and a guide shaft 14 that engages with the bearing A12 and the bearing B13.
Is guided slidably in the X direction. A fixed plate integrated with the mover bobbin 5 and the elastic holding member 8 described above.
10 is fixed to the side wall surface of the carriage 11. Reference numeral 15 denotes a mirror holder to which a reflection mirror 16 for reflecting the light beam emitted from the fixed optical unit 3 in the X direction in the Y direction is attached, and is fixed to the carriage 11. 17 is an electromagnet,
The elastic holding member 8 is fixed to the carriage 11 at a position facing the magnetic attraction plate 9 in the connecting portion 8c. In the energized state, a magnetic attraction force is generated in the magnetic attraction plate 9, and the elastic holding member 8
Regulates movement in the tracking direction. A carriage stopper 18 is composed of a leaf spring 18a capable of magnetic attraction and a buffer member 18b such as rubber, and is fixed to the carriage 11 at a position facing the electromagnet 17. A carriage stopper
The cushioning member 18b of the guide shaft 1 is provided when the electromagnet 17 is not energized.
4, the carriage 11 is fixedly held, and when the electromagnet 17 is energized, the leaf spring 18a is attracted to the electromagnet 17 and the carriage 1
The contact with 1 is released. Reference numeral 19 denotes a magnet, which constitutes a magnetic circuit together with the back yoke 20, the side yoke A21, and the side yoke B22, and drives the mover bobbin 4 in the Y direction and the X direction by the electromagnetic force of the focus coil 6 and the tracking coils 7a, 7b. To do. 23 is a guide shaft support spring,
The guide shaft 14 is fixed to the side yoke A21 and the side yoke B22 by screws, and the guide shaft 14 is fixed to the side yoke A21 and the side yoke B22.

The operation of the optical head of the present embodiment having the above structure will be described below.

First, when a drive current flows through the focus coil 6, a drive force is generated in the Y direction by the electromagnetic action with the magnetic circuit in the focus coil 6. Since the mover bobbin 5 is supported by the focus leaf spring 8a of the elastic holding member 8 so as to be movable in the Y direction, it moves in the Y direction. Therefore, the mover bobbin 5
The objective lens 5 housed in is driven in the focus direction and focus control is performed.

Next, the tracking control operation will be described. Electromagnet 17
Is de-energized. For example, the electromagnet 17 is set to the non-energized state in conjunction with the tracking ON signal. That is, since no attraction force is generated between the electromagnet 17 and the magnetic attraction plate 9 of the connecting portion 8c of the elastic holding member 8,
The movement of the elastic holding member 8 in the X direction is not restricted, and the mover bobbin 5 is moved by the tracking leaf spring 8b of the elastic holding member 8 in the X direction.
It is ready to move in any direction. On the other hand, since the buffer member 18b of the carriage stopper 18 is in contact with the guide shaft 14, the carriage 11 is fixedly held. Therefore, the vibration characteristic of the mover bobbin 5 is determined by the mass of the mover bobbin 5 and the spring constant of the tracking leaf spring 8b.
It becomes the secondary system vibration characteristic. When a driving current flows in the tracking coil 7 in such a state, a driving force is generated in the X direction by the electromagnetic action with the magnetic circuit in the tracking coil 7,
The objective lens 5 housed in the mover bobbin 5 is driven in the tracking direction and tracking control is performed. In this way, the tracking control is the control of the secondary system vibration characteristics,
Stable control performance can be obtained compared to the conventional one.

Next, the access control operation will be described. The electromagnet 17 is energized. For example, the electromagnet 17 is set to the energized state in conjunction with the access ON signal. That is, an attraction force is generated between the electromagnet 17 and the magnetic attraction plate 9 of the connecting portion 8c of the elastic holding member 8, the X-direction movement of the elastic holding member 8 is restricted, and the mover bobbin 5 moves in the focus direction. Only movably held. On the other hand, since the leaf spring 18a of the carriage stopper 18 is attracted to the electromagnet 17, the buffer member 18b is in a state where the contact with the guide shaft 14 is released.
That is, the mover bobbin 5 and the carriage 11 are in a state in which they can be integrally moved in the X direction. When a driving current flows through the tracking coil 7 in this state, a driving force is generated in the X direction by the electromagnetic action of the magnetic circuit in the tracking coil 7, and the mover bobbin 5 and the carriage 11 are integrated in the X direction. Move to access control. In this way, since the mover bobbin 5 does not swing during the access operation, stable access control performance can be obtained as compared with the conventional case. Further, in such a configuration, since the carriage 11 is fixed to the guide shaft 14 during tracking control, the vibration resistance characteristic of the carriage 11 against external shock vibration can be improved, and an optical head having excellent vibration characteristics can be obtained.

In this configuration, the guide shaft is used as the fixing means of the carriage, but it goes without saying that another fixing member can be substituted.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. 4 is a sectional view of another embodiment of the present invention. The same reference numerals as those in FIGS. 1 to 3 represent the same parts, and the description thereof will be omitted.

Reference numeral 31 denotes an electromagnet fixed to the carriage 11, which is arranged so as to face a guide shaft 32 made of a magnetically attractable material, and its movement in the X direction is restricted by the magnetic attraction force with the guide shaft 32 in the energized state. . An elastic holding member stopper 33 fixed to the carriage 11 is composed of a leaf spring 33a capable of magnetic attraction and a cushioning member 33b such as rubber, and is fixed to the carriage 11 at a position facing the electromagnet 31. The buffer member 33b of the elastic holding member stopper 33 contacts the connecting portion 8c of the elastic holding member 8 to fix the elastic holding member 8 when the electromagnet 31 is not energized, and when the electromagnet 31 is energized, the leaf spring 33a causes the electromagnet 3 to move.
1, and the contact between the elastic holding member 8 and the connecting portion 8c is released.

With such a configuration, it is possible to obtain the same focus control, tracking control, and access control characteristics as those of the above-described embodiment. Further, in this configuration, since the guide shaft and the stopper are not brought into contact with each other, the guide shaft is unlikely to be scratched or dust is attached, and the reliability of the optical head is high.

EFFECTS OF THE INVENTION As described above, according to the present invention, a mover bobbin that holds an objective lens that focuses an optical beam on an information track of a recording medium, and the objective lens is driven in a direction perpendicular to the recording medium. A focus coil fixed to the mover bobbin, a tracking coil fixed to the mover bobbin that drives the objective lens in a direction orthogonal to the information track, and transfer in a direction orthogonal to the information track by transfer guide means. A carriage that is guided as much as possible, an elastic holding means that is connected to the mover bobbin and the carriage, and that elastically holds the mover bobbin on the carriage, and a direction perpendicular to the information track of the mover bobbin. A tracking regulation means for regulating the movement, an access regulation means for regulating the movement of the carriage, and the focus A magnetic circuit that supplies a magnetic flux to both the coil and the tracking coil in common to generate a driving force, operates the access restricting means to fix the carriage during tracking, and also restricts the tracking during access. Means for operating the moving element bobbin and the carriage, the access regulating means is operated at the time of tracking by making the regulating operation and the regulation releasing operation of the tracking regulating means and the access regulating means conflict with each other. As a result, the carriage is fixed and only the mover bobbin moves in the tracking direction, so that the tracking characteristic of the secondary system is determined by the mass of the mover bobbin and the spring constant of the elastic holding member in the tracking direction. Operate the regulating means to fix the mover bobbin and the carriage. Since it is possible to the body to access, it is possible to prevent the shaking of the movable bobbin due to the access operation, it is possible to access excellent tracking control characteristics over conventional to provide a high-speed optical head,
The effect is great.

[Brief description of drawings]

1 is an exploded perspective view of an optical head according to an embodiment of the present invention, FIG. 2 is a top view of the optical head of the present invention, FIG. 3 is a sectional view taken along the line AA 'shown in FIG. 2, and FIG. Is a cross-sectional view of another embodiment of the present invention, FIG. 5 is an exploded perspective view of a conventional optical head, FIG. 6 is a top view of the conventional optical head, and FIG. 7 is a conventional optical head of FIG. It is a BB 'sectional view. 1 ... recording medium, 4 ... objective lens, 5 ... mover bobbin, 6 ... focus coil, 7 ... tracking coil, 8 ... elastic holding member, 9 ... magnetic attraction plate, 11 ... carriage, 14 ... Guide shaft, 17 ... Electromagnet, 18 ... Carriage stopper, 19 ... Magnet, 20 ... Back yoke, 21 ... Side yoke A, 22 ... Side yoke B.

Claims (3)

[Claims] 1. A mover bobbin holding an objective lens for focusing a light beam on an information track of a recording medium, and a focus fixed to the mover bobbin for driving the objective lens in a direction perpendicular to the recording medium. A coil, a tracking coil fixed to the mover bobbin for driving the objective lens in a direction orthogonal to the information track, a carriage guided by a transfer guide means in a direction orthogonal to the information track, and the movable body. Elastic holding means connected to the child bobbin and the carriage to elastically hold the mover bobbin on the carriage; tracking restricting means for restricting movement of the mover bobbin in a direction orthogonal to the information track; Both the access control means for restricting the movement of the carriage and the focus coil and the tracking coil Common and a magnetic circuit for generating a supply and driving force flux, tracking at the time of the carriage and fixed by operating the access restriction means,
During the access, the tracking restricting means is operated to fix the mover bobbin and the carriage, so that the restricting operation and the restricting releasing operation of the tracking restricting means and the access restricting means are opposed to each other. Optical head to do. 2. As the tracking restricting means, a part or the whole of the elastic holding means is a magnetic attraction member, and the carriage is provided with an electromagnet capable of attracting the magnetic attraction member of the elastic holding means. It is composed of an elastic member capable of attracting the electromagnet provided on the carriage and contacting a fixing member outside the carriage, and is configured to be released from contact with the fixing member outside the carriage when the electromagnet is energized. The optical head according to claim 1, wherein 3. A carriage transfer guide means comprises a bearing provided on the carriage and a guide shaft made of a magnetically adsorbing material, and an electromagnet provided on the carriage as an access control means between the guide shaft and the guide shaft. An elastic member that is configured to generate an attracting force and serves as a tracking restricting means that is attractable to the electromagnet provided on the carriage and contacts the mover bobbin, and contacts the mover bobbin when the electromagnet is energized. The optical head according to claim 1, wherein the optical head is configured to be released.