JPS63113943A - Three-axis optical head - Google Patents

Abstract

PURPOSE:To prevent deviation of the optical axis by applying jitter control by the turning around the shaft of a rotary slide frame, applying focus control by the slide along the shaft of a rotary slide frame and applying radial control by the slide in the radial direction of a slide table to use an inexpensive objective lens. CONSTITUTION:A laser beam from a semiconductor laser 19 is focused onto an optical disk by an objective lens 4 via a mirror 5 to record information. In supplying a focus control signal to a focus coil 16, the objective lens 14 is moved along the shaft 3 together with the rotary slid frame 13 by the action of the focus magnetic path unit to apply focus control. In supplying a jitter control signal to jitter coils 17a-17d, the rotary slide frame 13 is driven around the shaft 3 by the action of the focus magnetic path units 9a, 9b to apply jitter control. In giving a radial control signal to a radial coil 4, the slide table 2 is moved radially by the action of the radial magnetic path unit 8 to apply radial control.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a three-axis optical head used for recording information on an optical recording medium or reproducing recorded information, and in particular, the present invention relates to a three-axis optical head used for recording information on an optical recording medium or reproducing recorded information. , relates to a three-axis optical head that prevents deviation of the optical axis.

[Conventional technology]

In recent years, with the rapid development of optical recording and optical reproduction technology,
Various information optical recording and reproducing devices such as optical video disk players, compact disk players, and video file devices have been developed.

This information recording and reproducing device changes the optical recording layer by irradiating an optical disc as an optical recording medium with a laser beam (light beam) modulated according to recorded information, thereby recording information. It is carried out. Furthermore, reading of recorded information is carried out by detecting changes in the amount of light reflected from the optical recording layer due to irradiation with a weak laser beam.

Here, the optical head irradiates the optical recording medium with a laser beam and reads the reflected light, and is an important part of the information optical recording/reproducing apparatus. This optical head has focus control to focus the laser beam on the surface of the optical recording layer of the optical recording medium, radial control to make the laser beam follow the recording track, and jitter control to move the laser beam in the rotational direction of the optical disk. It is necessary to control the three axes that are orthogonal to each other.

Here, in the optical head commonly used in the past, focus control is performed by sliding the objective lens in the optical axis direction, and for tracking control and jitter control, two galvano mirrors are provided in the optical path. A method is used in which the optical axis of the laser beam supplied to the objective lens is moved in two orthogonal axes directions.

[Problem that the invention seeks to solve]

However, in the optical head with the above configuration, the objective lens is slid only in one axis direction along the optical axis direction, and the incident angle of the laser beam with respect to the objective lens is changed by two galvanic mirrors, thereby achieving radial and jitter control. Because of this, the effective image circle diameter of the objective lens must be increased. here,
When the effective image circle diameter of the objective lens is increased, its weight increases, which makes sliding movement for controlling the force of force difficult, and the characteristic of controlling the force of force deteriorates. Also,
Objective lenses with large effective image diameters are expensive, so
This leads to an overall cost increase. Furthermore, when two galvano mirrors are used, it is difficult to maintain the neutral point, and therefore a large number of man-hours are required to adjust the optical system, making manufacturing extremely difficult.

On the other hand, it may be possible to simplify the structure by supporting it in series with leaf springs or the like so that it can move only in three orthogonal axes, but this would result in relatively large vibrations being applied from the outside. Vehicle-mounted compacted disc players and the like have a problem in that secondary resonance occurs, resulting in errors in writing and reading information.

The present invention has been made to solve the above problems, and allows the use of an inexpensive objective lens, is easy to manufacture, and prevents misalignment between the optical axis of the objective lens and the optical axis of the collimator. Furthermore, it is an object of the present invention to obtain a three-axis optical head in which secondary resonance does not occur.

[Means for solving problems]

The three-axis optical head according to the present invention includes a slide table that slides while being guided by a shaft, and a radial coil is attached to the side surface of the slide table and positioned in the magnetic path of the radial magnetic path unit to supply a radial control signal. By doing so, the slide table is slid in the radial control direction. In addition, a shaft extending upward perpendicular to the sliding direction of the slide table is installed, and a rotary slide frame having an objective lens attached to the longitudinal end thereof is rotated and rotated around the shaft. The focus coil is mounted so as to be slidable in the direction along the same direction, and is provided with a focus coil wound around the outer periphery in a ring shape and a thick coil wound in the shape of a mouth and equally distributed at four locations on the circumference of the focus coil. The focus I is placed in the magnetic path of the focus magnetic path unit, and the focus coil is placed in the magnetic path of the focus magnetic path unit.
II? By supplying a wholesale signal, the lens holder is slid along the axis in the focus control direction, and by supplying a jitter control signal to the jitter coil, the lens holder is rotated in the jitter control direction. By moving each part in this way, the objective lens mounted on the rotating slide frame is moved in three orthogonal axes directions, and the optical axis of this objective lens is
The mirror is used to align the optical axis of the optical processing section located on the outside of the slide frame along the sliding direction.

[For production]

In the 3-axis optical head configured in this way, jitter control is performed by rotating around the axis of the rotating slide frame on which the objective lens is attached, and focus control is performed by sliding along the axis of the rotating slide frame. Radial control (tracking control) is performed by sliding a slide table that fixes a shaft for rotating and sliding the lens holder in a radial direction perpendicular to the shaft. In this case, the movement of each part in the three orthogonal axes directions is rotational movement and sliding movement around the axis, so even if the support system is in series, secondary resonance will occur, as in the case of spring support. will not occur at all. In addition, in radial control, the objective lens and
The ° mirror moves as one, and the direction of movement is along the optical axis that connects this 90 ° mirror and the optical processing section, which prevents the optical axis from shifting. This makes it possible to use an objective lens with a small diameter.

〔Example〕

1 and 2 are a sectional view and a plan view showing an embodiment of the 3-axis optical head according to the present invention, and FIG. 3 is an exploded perspective view of the 3-axis optical head shown in FIGS. 1 and 2. be. In the figure, reference numeral 1 denotes a base, which is composed of a disk-shaped portion 1a and a plate-shaped portion 1b extending in the radial direction from a part of this disk-shaped portion 1a. Arc-shaped side walls 1c and ld are provided in the peripheral portion of the disc-shaped portion 1a and in a portion other than the extending direction of the plate-shaped portion 1b. In addition, the root plate part 1
A block 1e is provided above the tip of b, and holes 1f and Lg are formed in both sides of the block 1e on the disk-shaped portion 1a side. Shafts lh and Ii are inserted and fixed into the holes 1f and Ig, respectively, thereby forming parallel shafts. 2
is a rectangular slide table, and shafts lh and li are inserted into holes provided on the sides of the slide table, so that the table slides while being guided by the shafts lh and li. A shaft 3 is implanted and fixed in the center of the upper surface of the slide table 2. Tama, the shaft lh in this slide table 2
, li is inserted, and the shafts lh, i
A radial coil 4 wound into a cylindrical shape is fixed to the portion between t. 5 is a 90° angle fixed to the surface of the slide table 2 opposite to the surface on which the radial coil 4 is fixed.
A mirror 6 is a block fixed to the upper surface of the slide table 2, and holds one end of a neutral point holding member 7 made of an elastic material such as rubber in the shape of a frame, for example.

8 is the side surface of the block le on the disk-shaped portion 1a side, and the shirt l-1h.

The radial magnetic path unit is fixed to a portion between 1g and 1g, and includes a yoke 8a having a U-shaped side surface, a cylindrical radial magnet 8b fixed to the bottom of this yoke 8a, and an end face of this radial magnet 8b. By being constituted by a center yoke 8c that is fixed and whose tip end is inserted into the inside of the radial coil 4, there is a gap between the center yoke 8C and the side yokes 3d and 8e of the yoke 8a located on the side thereof. The magnetic flux is focused in the air gap.

Reference numerals 9a and 9b denote focus magnetic path units, which include a yoke having an arcuate groove 11 that is fixed along the inner surface of the arcuate side walls 1c and 1d of the base 1 and that is open upward; A focus magnet 12 is fixed along the upper part of one inner side wall surface of the groove 11 in the groove 11. Reference numeral 13 denotes a rotary slide frame in which the shaft 3 is attached to a hole 13a formed in a longitudinal central portion, so that rotation about the shaft 3 and sliding in a direction along the shaft 3 are possible. It is. A hole 13b is provided at one end of the rotary slide frame 13, into which an objective lens holder 15 that accommodates the objective lens 14 is mounted. Further, the other end of the neutral point holding member 7 is fixed to a part of the rotating slide frame 13. Reference numeral 16 denotes a focus coil wound in a ring shape and fixed to the outer periphery of the rotating slide frame 13, a part of which is connected to the focus magnet 12 in the focus magnetic path units 9a and 9b.
and the opposing side surfaces. Reference numerals 17a to 17d are jitter coils wound in the shape of an opening, which are located on the circumferential surface of the focus coil 16 and on the second
As shown in the figure, only a portion thereof is fixed at a position facing the focus magnet 10. The jitter coils 17a to 17d are set so that their winding directions are arranged alternately.

18 is an optical processing section, which includes a semiconductor laser 19, a beam splitter 20, a collimating lens 21, and a λ
It is composed of a convex lens 23, a cylindrical lens 24, and a light receiving sensor 25.

In the three-axis optical head configured as described above, in the normal state, the rotating slide frame 7, which can freely rotate and slide by the neutral point holding member 7,
It will be held at a predetermined midpoint position.

Here, when a laser beam modulated according to recorded information is generated from the semiconductor laser 19, this laser beam is supplied to the collimating lens 21 via the beam splitter 20. The collimating lens 21 converges the laser beam supplied via the beam splitter 20 into parallel light, and then separates the λ/4 plate 2 sheet metal 2 into 90
° Mirror 5 is supplied. The 90° mirror 5 deflects the laser beam supplied from the λ/4 plate 2 in the direction along the axis 3 by 906. The laser beam deflected by 90° passes through the hole 13 provided in the rotating slide frame 13.
The light is supplied to the objective lens 14 via b. Objective lens 1
4, by converging this laser beam and irradiating it onto the optical recording layer of an optical disc (not shown), the information is optically recorded by changing the part.

Next, when a focus control signal is supplied to the focus coil 16, the magnetic flux generated in the focus coil 16 is transmitted to the focus magnetic path unit 9a.

A force in the direction along the axis 3 is generated by acting on the magnetic flux generated in the gap (inside the groove 11) between the focus magnet 12 and the yoke 10 facing the focus magnet 9b.

Since this force acts on the rotating slide frame 13 to which the focus coil 16 is fixed, the rotating slide frame 13 distorts the neutral point holding member 7 while responding to the focus control signal as shown in FIG. It will move up and down. Since an objective lens holder 15 that holds an objective lens 14 is attached to the rotary slide frame 13 in the hole 13b, the objective lens 14 can move up and down, that is, the optical disc 7
Focus control is performed by sliding the lens in a direction perpendicular to the surface of the lens.

Next, when a jitter control signal is supplied to the jitter coils 17a to 17d, the magnetic flux generated from the jitter coils 17a to 17d is transferred to the focus magnetic path units 9a and 9b.
Acting on the magnetic flux generated in the gap between the focus magnet 12 and the inner wall surface of the yoke that faces the focus magnet 12 via the groove 11, an acting force in the rotational direction is generated between the two. . Here, York 10
are fixed to the inner wall surfaces of the side walls 1c and ld of the base 1, the rotational force generated by the jitter coils 17a to 17d distorts the neutral point holding member 7 and causes the rotating slide frame 13 to respond to the jitter control signal. It will be rotated accordingly. In this way, when the rotating slide frame 13 rotates around the axis 3, the objective lens 14 attached to the tip of the rotating slide frame 13
moves in the circumferential direction to perform jitter control.

Next, when a radial coil control signal is supplied, a magnetic flux is generated according to the radial coil control signal, and the center yoke 8c and side yoke 3 in the radial magnetic path unit 8 are
It acts on the magnetic flux generated in the air gap between d and 3e. Here, the radial magnetic path unit 8 is fixed to the side surface of the block 1e on the base 1, and the radial coil 4 is fixed to the side surface of the slide table 2 that slides while being guided by the two shafts Ig and lh arranged in the opposite direction. Since the slide table 2 is fixed, it slides in response to the radial control signal. Since the shaft 3 supporting the rotary slide frame 13 is implanted in the center of the upper surface of the slide table 2, movement of the slide table 2 moves the rotary slide table 13 in the direction of its rotation radius. It turns out.

Further, the movement of the rotary slide table 13 in the direction of the rotation radius is performed by moving the objective lens 14 attached to the end thereof in a direction perpendicular to its optical axis, thereby performing radial control. It turns out.

As explained above, the optical axis of the objective lens 14 is aligned with the optical axis of the optical processing unit 18 by being deflected by 90° by the mirror 5 906, but this 90° mirror 5 is The optical axis of the optical processing section 18 is fixed to the end face of the slide table 2.
Since the optical axis is aligned with the sliding direction of the optical axis, there is no deviation of the optical axis due to radial control. In addition, the movement of each part associated with each jitter control, focus control, and radial control is rotation and sliding movement guided by the axis and the shaft, so the operation is extremely stable, and each of these Even if the fixed system is configured in series, secondary resonance will not occur.

In the above embodiment, the focus magnetic path units 9a and 9b are provided on the side wall 1c of the base 1.

Although the case where it is fixed to the inner wall surface of 1d has been described, it is ideal to fix it to the slide table 2 if the load allows it. Further, although an elastic material cut into a picture frame shape was used as the neutral point support member 7, the present invention is not limited to this, and the rotating slide frame 1
Any type of material may be used as long as it can maintain the center point in the rotation and sliding directions of 3, and may be constructed from a plurality of members.

〔Effect of the invention〕

As explained above, the three-axis optical head according to the present invention is provided with a slide table that slides while being guided by a shaft, and a radial coil is provided on the side surface of this slide table and positioned in the magnetic path of the radial magnetic path unit. By supplying a radial control signal, the slide table is slid in the radial control direction. Also,
A shaft extending in a direction perpendicular to the sliding direction of this slide table is installed, and a rotary slide frame having an objective lens at the end is rotatably and slidably attached to this shaft, and a ring-shaped A focus coil wound around the focus coil is provided coaxially and positioned in the magnetic path of the focus magnetic path unit, and a plurality of jitter coils wound around the focus coil are equally distributed. By positioning these two coils in the magnetic path of the focus magnetic path unit and supplying a focus control signal and a jitter control signal to each coil, the rotary slide frame is rotated and slid about the axis, and the focus is adjusted. 181J'<This is for wholesale and jitter control. By moving each part along the shaft and axis in this way, the objective lens mounted on the rotating slide frame is moved in three orthogonal axes directions, and the optical axis of this objective lens is aligned with the slide table using a 90° mirror. It is configured so that the optical axes of the optical processing sections located in the direction along the sliding direction are aligned. Therefore, the movement of the objective lens in the three orthogonal axes directions is guided by the axes and shafts, resulting in extremely stable movement.

As a result, even if the support system of three orthogonal axes is arranged in series, the occurrence of secondary resonance can be reliably prevented, and assembly and adjustment can be made extremely easy. In addition, when the 90° mirror is fixed to a slide table, the movement of the objective lens and the 90' mirror during radial control is integrated, so optical axis deviation during radial control is reliably prevented. It has various excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a 3-axis optical head according to the present invention, FIG. 2 is a sectional view of the 3-axis optical head shown in FIG. 1, and FIG. 3 is an exploded perspective view of the 3-axis optical head shown in FIG. 1. be. 1 is a base, 1a is a disk-shaped part, 1b is a plate-shaped part, Ic,
ld is the side wall, 1e is the block, if, Ig is the hole, lh,
li is the shaft, 2 is the slide table, 3 is the axis, 4 is the radial coil, 5 is the 90° mirror, 6 is the block, 7
is a center point holding member, 8 is a radial magnetic path unit, 8a is a yoke, 8b is a radial magnet, 8c is a center yoke, 8C18d is a side yoke, 9a and 9b are focus magnetic path units, IO is a yoke, 11 is a groove, 2 is a focus magnet, 13 is a rotating slide frame, 13
14 is an objective lens, 15 is an objective lens holder, 16 is a focus coil, 17a to 17d are jitter coils, and 18 is an optical processing section. Applicant: NEC Home Electronics Figure 2 1”1110

Claims (4)

[Claims] (1) A slide table that slides while being guided by a parallel shaft, and a part of the slide table that is fixed to this slide table and positioned in the magnetic path of the radial magnetic path unit, allows the slide table to be moved in response to a radial control signal. A radial coil to be slid, a shaft embedded in the slide table and extending in a direction perpendicular to the sliding direction of the slide table, and supported by this shaft to freely rotate and slide in the direction along the axis. a rotating slide frame, an objective lens provided in a portion of the rotating slide frame radially away from the center of rotation, and an objective lens coaxially fixed to the rotating slide frame in a magnetic path of a focus magnetic path unit. a jitter coil wound in a rectangular shape and fixed to the circumferential surface of the focus coil; and a jitter coil that deflects the optical axis of the objective lens outward along the sliding direction of the slide table. 90° aligned with the optical axis of the optical processing section
A three-axis optical head characterized by being equipped with a mirror. (2) The three-axis optical head according to claim 1, wherein the 90° mirror is fixed to a slide table. (3) The three-axis optical head according to claim 1, wherein the rotary slide table is held at its midpoint in the rotational direction and the sliding direction by a midpoint holding member. (4) The three-axis optical head according to claim 1, wherein the focuser magnetic path unit is fixed to a slide table.