JPS6223377B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical disc recording device.

An optical disk recording device records minute information patterns spirally on a disc-shaped recording medium as a rotating groove pattern or a pattern of appropriate refractive index changes, or condenses light in order to reproduce the recorded information pattern. A light beam is irradiated to write or detect a pattern. A pickup device that irradiates a focused light beam and detects information uses a gas laser such as He-Ne or a semiconductor laser as a light source, and is composed of an optical system such as a condenser lens and a photodetector. In order to record and reproduce minute information patterns, it is necessary to control the track so that the focused light beam accurately tracks the recording track of the recording medium, and at the same time, it is necessary to control the recording track to the focal position of the light beam. It is necessary to perform focus control to match the values.

When conventional optical disk recording devices are actually used, the recording tracks on the recording surface tend to constantly fluctuate in position due to surface runout due to high-speed rotation of the disk or external vibrations.
Therefore, a drive mechanism is provided to control the movement of the entire pickup device or a part of the light focusing system in accordance with the positional deviation of the recording track, and to reliably perform the above-mentioned track control and focus control.
An example of a pickup device equipped with this drive mechanism is shown in FIG. Output light from a semiconductor laser 1 serving as a light source is passed through an objective lens 2, and its optical path is changed by a galvanometer mirror 3. The galvanometer mirror 3 receives a driving force through the action of a magnetic circuit, rotates about a rotation axis perpendicular to the plane of the drawing, and deflects the irradiation beam to perform track control. The beam whose optical path has been changed by the galvano mirror 3 is focused by the condenser lens 4 and irradiated onto the recording surface 5. The condensing lens 4 is provided with a driving section for performing focus control. This drive unit is composed of a magnetic circuit consisting of a permanent magnet 6 and soft iron yokes 7 and 8, and a cylindrical conductive wire coil 9 connected to a condensing lens 4. The interaction between the generated magnetic field and the magnetic circuit creates a driving force that moves the condenser lens 4 in a direction perpendicular to the recording surface 5, thereby controlling the distance between the condenser lens 4 and the recording surface 5.

In the drive mechanism for track control and focus control shown in FIG. 1, a total of two magnetic circuits are required for each control. On the other hand, miniaturization and weight reduction are very important factors in optical disk recording devices, and therefore rare earth magnets with small capacity and large BH product are used as magnets in order to miniaturize the magnetic circuit. . However, rare earth magnets are much more expensive than the generally widely used ferrite magnets, and therefore have the drawback of increasing the material cost of optical disk recording devices.

In addition, in an optical disk recording device, in order to continuously record/reproduce information according to a recording track or record/reproduce information at an arbitrary point on the disk, a pick-up device is moved at an arbitrary point in the radial direction of the disk at low speed or Need to move fast. Therefore, in addition to the drive mechanism for track control and focus control, a pick-up transport mechanism is provided for moving the pick-up device at a predetermined speed. The pick-up feed mechanism may be constructed by a combination of a DC motor, step motor, etc. and a rack pinion, or it may be constructed by a linear motor.

As detailed above, conventional optical disk recording devices require a pick-up feed mechanism as well as a drive mechanism for track control and focus control using expensive rare earth magnets. The disadvantage is that the drive system becomes complicated and the manufacturing cost increases.

The present invention aims to simplify the conventional complicated magnetic circuit drive system by making full use of technical means, and to provide an inexpensive optical disk recording device.

Hereinafter, the present invention will be explained in detail according to embodiments with reference to the drawings.

FIG. 2 is a diagram showing the main parts of a drive mechanism for track control and focus control, and a pick-up feed mechanism, explaining one embodiment of the present invention.

A focus control coil 9' that can move the pick-up in a direction perpendicular to the disk recording surface, and a focus control coil 9' that is placed on both sides of the focus control coil 9' and that allows the pick-up to be moved in a direction parallel to the disk recording surface and orthogonal to the recording track direction. Rectangular parallelepiped coils 10 and 11 for track control and pick-up feeding
is inserted into the soft iron yoke 13 at the center of three soft iron yokes 12, 13, and 14 formed into a prismatic shape and arranged in parallel with a certain gap between them. Soft iron yoke 12 at both ends,
14 is a permanent magnet 1 similarly formed into a prismatic shape.
5 and 16 are fixed on top of each other, and the permanent magnets 15 and 16 face the focus control coil 9' and the rectangular parallelepiped coils 10 and 11 at a constant distance. Soft iron yoke 12, 13, 14
The axial direction is parallel to the recording surface and perpendicular to the recording track. In addition, permanent magnet 15,1
6 is in the gap between the soft iron yokes 12, 13, 14,
Soft iron yokes 12, 13,
It is magnetized in a direction perpendicular to the axial direction of 14.
soft iron yokes 12, 13, 14 and permanent magnets 15,
16 constitutes a magnetic circuit, and the rectangular parallelepiped coils 10 and 11 for track control and pick-up feeding are configured to receive driving force independently from each other when energized in the axial direction of the soft iron yoke 13. On the other hand, the focus control coil 9' is connected to the soft iron yoke 1.
It is configured to receive a driving force in a direction perpendicular to the axial direction of No. 3. As is well known, in a drive mechanism whose magnetic circuit is composed of a conductive wire coil, the direction of its driving force is perpendicular to the magnetic lines of force and the conductive wire according to Fressing's law. Therefore, the rectangular parallelepiped coils 10 and 11 are wound with insulated conductors in the direction of winding the soft iron yoke 13, but in focus control it is necessary to drive the pick-up in a direction perpendicular to the axial direction of the soft iron yoke 13. Therefore, in this embodiment, as the focus control coil 9', an insulated conductor is spirally wound on a plane, and this plane spiral conductor is bent into a "U" shape as shown in FIG. 3 to form the axis. It is loosely fitted into the soft iron yoke 13, and the direction of the magnetic lines of force in the magnetic circuit gap and the direction of the conducting wire coil are made perpendicular to the direction of the driving force. Alternatively, as a focus control coil 9', an insulated conductive wire is wound into a cylindrical shape, and this cylindrical coil is bent into a flat shape, and then bent into a "U" shape as shown in FIG.
3, so that the direction of the magnetic lines of force in the magnetic circuit gap and the direction of the conductive wire coil are perpendicular to the direction of the driving force. In the above embodiment, the soft iron yokes 12, 13, and 14 are formed into linear shapes, but they are formed into arc shapes so that the pick-up travels in an arc shape in a direction perpendicular to the track direction. You can also.

FIG. 5 is a block diagram of a pickup device equipped with the drive mechanism shown in FIG. 2.

The rectangular parallelepiped coils 10, 11 for track control and pick-up feeding, and the focus control coil 9' are directly connected to the pick-up 17, and the driving force is received independently by each coil 9', 10, 11, but during operation, the pick-up 17 It is linked with By energizing the rectangular parallelepiped coils 10 and 11 for track control and pick-up feeding, the rectangular parallelepiped coils 10 and 11 move to the soft iron yoke 13 due to the action of the magnetic field generated in the coils and the magnetic lines of force in the magnetic circuit gap.
The pickup 17, which is directly connected to the pickup 17, is also driven in the direction parallel to the recording surface and perpendicular to the recording track direction. Movement of the pick-up 17 means movement of the entire irradiation optical system, and the movement of the cuboid coil 1 means movement of the entire irradiation optical system.
By controlling the amount of current applied to the irradiation beams 0 and 11, track control of the irradiation beam light on the recording surface and high-speed movement to an arbitrary track are executed. In this operation, since the focus control coil 9' is also directly connected to the pickup 17, it is linked to the rectangular parallelepiped coils 10 and 11. Next, when the focus control coil 9' is energized, the focus control coil 9' is driven in a direction perpendicular to the recording surface of the disk, and the pickup 17 directly connected thereto is also driven in a direction perpendicular to the recording surface. In this focus control, in this embodiment, the rectangular parallelepiped coils 10 and 11 for track control and pick-up feeding are also linked, but the rectangular parallelepiped coils 10 and 11 are loosely fitted into the soft iron yoke 13 with a gap. Therefore, the rectangular parallelepiped coils 10 and 11 can be freely moved within this insertion gap.

In this way, focus control, track control, and pick-up feeding operation can be performed by the same magnetic circuit by controlling the current supply to the focus control coil and the rectangular parallelepiped coil.

As explained in detail above, according to the present invention, by sharing the same magnetic circuit, focus control, track control, and pick-up feeding can be performed with a simple drive mechanism, and the structure is small and simple, so manufacturing costs can be reduced. A control drive mechanism that is inexpensive and highly reliable can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional pickup device. FIG. 2 is a diagram illustrating a main part of a drive mechanism for focus control, track control, and pick-up feeding, illustrating an embodiment of the present invention. FIG. 3 is a perspective view showing an embodiment of the focus control coil in FIG. 2. FIG. 4 is a perspective view showing another embodiment of the focus control coil in FIG. 2. FIG. 5 is a block diagram of a pickup device equipped with the drive mechanism shown in FIG. 2, showing an embodiment of the present invention. 1... Semiconductor laser, 2... Objective lens, 3
...Galvano mirror, 3'...Fixed mirror, 4...
... Condenser lens, 5 ... Disk recording surface, 6 ... Permanent magnet, 7, 8 ... Yoke, 9, 9' ... Focus control coil, 10, 11 ... Rectangular parallelepiped coil, 12, 13, 14 ... ...soft iron yoke, 15,1
6...Permanent magnet, 17...Pickup.

Claims (1)

[Scope of Claims] 1. In an optical information processing device that optically records or reproduces information by irradiating a beam light from a light beam irradiation system onto a recording track of a disk, the optical information processing device is provided with a plurality of optical information processing devices that are long in the radial direction of the disk and that are connected to each other. A magnetic circuit consisting of three yokes arranged in parallel with a certain gap between them, and a permanent magnet closely attached to the yokes to generate a magnetic field in the gap between the yokes, and a permanent magnet magnetically coupled to the magnetic circuit. a first coil that performs focus control by driving the light beam irradiation system using electromagnetic force in a direction substantially perpendicular to the disk surface; and a second coil for driving the light beam irradiation system with electromagnetic force in a direction substantially perpendicular to the track direction to perform track control and radial feeding, using the same generated magnetic field of the magnetic circuit. An optical information processing device characterized in that the first coil and the second coil are driven independently.