JPS59195337A - Optical pickup - Google Patents

Abstract

PURPOSE:To reduce the overall thickness of an optical pickup and at the same time to improve the record/reproduction characteristics by setting both the tracking and focusing driving coils at the same height as a lens barrel and adding the magnets in opposition to each other to both driving coils. CONSTITUTION:When a driving current is flowed to a focusing driving coil 16 based on the focus error signal detected by a focus error detecting circuit, the focus driving power acts in the ZZ direction between magnet units 23a and 23b by the Fleming's left-hand rule. As a result, the spring parts 26a and 26b of elastic support members 19a and 19b move toward ZZ and therefore an objective lens 13 has displacement in the ZZ direction. Thus the focus control is performed. For the tracking control, the driving power is generated in the XX direction between magnet units 18a and 18b by the Fleming's left-hand rule when a tracking driving current flows to tracking driving coils 17a and 17b. Thus the spring parts 26a and 26b move in the XX direction to perform the tracking control.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical recording and reproducing apparatus that records or reproduces information on a disk-shaped information recording medium (hereinafter referred to as a disk) using a laser or the like as a light source. This invention relates to an optical pickup that performs focusing control to correct focus deviations caused by shake, etc., and tracking control to correct tracking deviations caused by disk eccentricity, etc.

Conventional Structures and Problems In recent years, as optical recording and reproducing devices such as video disks, DADs, and optical disk files have come into practical use, there has been an increasing need for smaller optical pickups and higher performance.

First, an example of a conventional optical pickup will be explained. FIG. 1 is a sectional view of a conventional optical pick amplifier. In Fig. 1, 1 is a semiconductor laser, 3 is a reflecting mirror, 4 is an objective lens, 5 is a disk, 6Id, vance I, 7a
, Ryusu is a tracking drive coil, sa and sb are tracking drive magnetic circuits, 9 is a focusing drive coil,
10a, 10b.

10C is a focusing drive magnetic surface path, 11° and 12 are elastic support members, and 2 is an optical axis. XX is disk 5
and ZZ indicate the thickness direction of the disk 5, respectively.

The operation of the conventional optical pink-up configured as described above will be described below.

A tracking correction current is transmitted from a tracking error detection circuit (not shown) to tracking 1 drive coils γa and 7b.
4c, the tracking drive magnetic circuit s a ,
An electromagnetic force based on Fleming's left-hand rule is generated between s and b, and the objective lens 4 moves in the XX direction in the figure in balance with the elastic force of the elastic support members 11 and 12.
Tracking control is performed. Similarly, focusing control is performed by electromagnetic force generated between the focusing drive coil 9 and the focusing drive magnetic circuits 10a and 10b.

However, in the above configuration, the tracking 1 drive coil 7a, which is the position where the driving force for tracking cloth control is generated,
The center position M of the elastic support member "11.degree. When the disc 6 is tilted, aberrations occur due to the inclination between the optical axis 2 and the optical axis of the objective lens 4 itself, and the relative inclination between the optical axis of the objective lens 4 itself and the disk 6, which deteriorates the recording and reproducing characteristics. Still, the focus drive coil 9 and the tracking drive coils 72L and 7b are arranged separately above and below the lens barrel 6, and each magnetic circuit for tracking and focusing is Since it constitutes a completely closed magnetic path, the height of the optical pickup becomes thicker due to the need for gaps '+b+c and d for focusing movement shown in Fig. 1.Therefore, optical recording and reproducing is not possible. There is a drawback that it is difficult to make the entire device thinner.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and aims to improve the recording and reproducing characteristics, as well as to reduce the thickness of the optical pickup and the overall thickness of the optical recording and reproducing apparatus.

Structure of the Invention The present invention provides a lens barrel housing an objective lens for focusing light emitted from a light source onto a recording trunk on a disk-shaped information recording medium, and a coil axis is attached to the outer periphery of the lens barrel. a first coil wound so as to coincide with the optical axis of the lens; and a pair of second coils wound such that the coil axis coincides with the tangential direction of the recording track and disposed via the optical axis of the objective lens. a first magnet unit comprising two magnets each having a coil and having magnetic poles in the radial direction of the recording trunk, arranged such that magnetic pole surfaces of the same polarity face each other across the winding surface of the first coil; and two sets of magnet units configured such that two magnets each having a magnetic pole in the tangential direction of the recording track are configured such that one has an N pole and the other has an S pole facing the winding surface of the second coil. , one N through the optical axis
A pole is arranged so as to face the other south pole, and the first and second coils are arranged so that the centers of the first and second coils in the optical axis direction are approximately 9 points apart, and the positions are substantially equal from the center of the coil in the optical axis direction. By disposing an elastic support member that movably supports the lens barrel, the elastic support member is moved in parallel during tracking control and vertically during focus drive, thereby preventing the occurrence of aberrations and improving recording and reproducing characteristics. The optical pickup is made thinner, and the optical recording/reproducing device is made thinner.

Description of examples FIG. 2 is a cross-sectional view of one embodiment of the present invention.

In FIG. 2, 13 is an objective lens, 14 is a disk,
15 is a lens barrel, 16 is a hollow rectangular prism-shaped focus drive coil, 17a and 1γb are tracking drive coils, 1B&, 18b are tracking drive magnet units,
Reference numerals 19a and 19b indicate a pair of elastic members, 2Q indicates a housing of the entire optical pickup, YY in the figure indicates the tangential direction of the recording track formed on the disk 14, and 22 indicates the thickness direction of the disk 14. show.

FIG. 3 is a plan view with the elastic support member 19a removed, and XX and YY indicate the radial direction and tangential direction of the recording tracks formed on the disk 14, respectively.

21 & , 21 b , 21 C indicate the configuration of the tracking drive magnet 18 b, and 21 a.

21b is a pair of magnets each having a magnetic pole in the YY direction, the magnet 21a has its N pole, and the magnet 21b has its S pole.
Each is configured to face the coil winding surface of the tracking drive coil 17b.

22a, 22b, 22(! indicates the same magnets and yoke plates as 21a to 21c and constitute the tracking drive magnet unit 18a, but the S pole of the magnet 22'a facing the magnet 21a is the same as that of the magnet 21b. The N pole of the magnet 22b facing the tracking drive coil 17
It is configured to face the coil winding surface of a.

Reference numerals 23a and 23b indicate focus drive magnet units, respectively, and yoke plates 25 and 24b are arranged so that their magnetic poles coincide with each other in the XX direction, and the same poles face each other via the focus drive coil 16.
25b.

Further, the center of the focus drive coil 16 in the ZZ direction,
The centers of the tracking drive coils j 7a and 17b in the 22 directions are approximately aligned with the line AA in FIG. 2.

Further, the pair of upper and lower elastic support members 19a and 19b are A
They are arranged vertically symmetrically with respect to A.

FIG. 4 is a plan view of the elastic support members 192L and 19b, including the spring portions 26a and 26b, and the ring portion 27.
, outer circumferential fixing part 2sa, 28b, the ring part 27 is attached to the lens barrel 6, and the outer circumferential fixing part 28a is attached to the lens barrel 6.

28b are each fixed to the housing 20.

Next, the operation of the above embodiment will be explained. First, focus system '11] will be explained. When a drive current flows through the focus drive coil 16 based on a focus error signal detected by a focus error detection circuit (not shown), a buff focus 1 is generated between the magnet units 23a and 23b based on Fleming's left hand rule. The driving force acts in 22 directions, and the spring portions 26 & of the elastic support members 19a, 19b
, 26b are displaced in the direction of the zz force, and as a result, the objective lens 13
is displaced in 22 directions to perform focus control.

This focus control requires driving the objective lens 13 vertically in the disk thickness direction without tilting the optical axis of the objective lens 130.

The tracking drive magnet Uniso) 18a.

18b and focus drive magnet (Unino) 23a.

The arrangement of magnets 23b will be explained using FIG. 5.

FIG. 5 is a magnet layout diagram of an optical pickup according to an embodiment of the present invention. The same numbers in the figures refer to the same parts as shown in FIGS. 2 and 3. Still, P.
Q, R, and Z indicate the vertices of the focus drive coil 16.

In FIG. 6, the tracking drive magnet unit 18a
, 18b on the focus drive coil 16 are the magnetic flux directed from the magnet 22a to the magnet 21b and the magnetic flux directed from the magnet 22a to the magnet 21b.
The magnetic flux from b to the magnet 22a, the magnetic flux from the magnet 24b to the magnet 21b, and the magnetic flux from the magnet 23b to the magnet 22 & are canceled by the coil winding surface represented by PQ and the coil winding surface represented by ZR, respectively. being focused,
The drive coil 16 is likely to be unbalanced around the YY axes. As a result, the objective lens 13 can be driven in the disk thickness direction without tilting its optical axis. Further, in tracking control, similarly to focus control, when a tracking drive current flows through tracking drive coils 17a and 17b, a drive force in the XX direction is generated between magnet units 18a and 18b based on Fleming's left hand rule. As a result, the elastic support member 19ia,
The spring portions 26a and 26b of 19b are displaced in the XX direction, but at this time, the elasticity is applied to the center C of the tracking drive coil in the ZZ direction, indicated by AA in FIG. Support member 19fL, 1
9b are arranged symmetrically, so that during tracking control, the wing portions 26a.

26b is not loaded with an undesired moment,
The spring portions 26a and 2eb of the pair of upper and lower elastic support members 192L and 19b are equally displaced in the XX direction. As a result, the objective lens 13 is displaced in the XX direction without tilting, thereby improving tracking control.

As described above, the pickup of this embodiment includes: a hollow rectangular prism-shaped focus drive coil 16, and a hollow rectangular prism-shaped tracking drive coil 17a, 1γb.
are fixed to the lens barrel 15 so that their centers in the height direction substantially coincide with each other, and a pair of elastic support members 19a and 19b are arranged vertically symmetrically with respect to the centers in the height direction. By arranging a magnet unit to face each of the drive coil 16 and the tracking drive coils 1&, 17b to obtain a drive force, tracking control can be performed without tilting the objective lens 13.

Also, a tracking drive magnet unit 18a.

18b and a focus drive magnet unit 23a.

23b, the objective lens 13 can be moved to the disk 1 without causing an imbalance in the focus driving force.
It can be driven perpendicular to 4.

Therefore, during focus control and tracking control, it is possible to prevent the occurrence of aberrations (coma aberration, astigmatism) caused by the inclination of the objective lens optical axis with respect to the disk 14 and the inclination with respect to the incident optical axis 29 from the light source, resulting in good recording and reproduction. characteristics are obtained.

Furthermore, a coil 1 for tracking and focus drive
6, 17a, 1. By aligning the centers of the magnet units in the height direction, it is possible to make the optical pink-up thinner, making it possible to make the entire optical recording and reproducing device thinner. Effects can be obtained.

Effects of the Invention In the optical pink-up of the present invention, the tracking and focus drive coils are installed at the same height of the lens barrel, and furthermore, each drive coil is designed so that the focus drive force is not unbalanced. By arranging the magnets facing each other, a driving force for tracking and focusing is obtained, and furthermore, a pair of elastic support members are arranged vertically symmetrically with respect to the positions where both coils are attached to the lens barrel. This makes it possible to make the optical pickup thinner, making it possible to make the entire optical recording/reproducing device thinner, and to improve tracking control.
This is performed by parallel movement of the objective lens, and focus control is performed by vertical movement of the objective lens, thereby preventing the occurrence of aberrations and improving recording and reproducing characteristics, which has great industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a sectional front view of a conventional optical pickup amplifier, FIG. 2 is a sectional view of an optical pickup device according to an embodiment of the present invention, FIG. 3 is a plan view of the same, and FIG. 4 is an elastic support used in the device. A plan view of the members, and FIG. 6 is a plan view of the magnet arrangement of the device. 13...Objective lens, 19a, 19b...
...Elastic support member, 16...Focus,
Drive coil, 17a, 17b... Tracking drive coil, 18L, 1 sb...
・Tracking drive magnet unit, 232L, 23b
...Focus drive magnet unit, 21a, 2
1b, 22a, 22b, 23a. 23b... Magnet. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 2 Figure 3 Figure 4 Figure 26 Z'/

Claims (1)

[Claims] A lens barrel housing an objective lens for focusing light emitted from a light source onto a recording track on a disc-shaped information recording medium is provided, and a coil axis is arranged on the outer periphery of the lens barrel to coincide with the optical axis of the objective lens. a first coil wound so that the coil axis coincides with the tangential direction of the recording track; and a pair of second coils wound so that the coil axis coincides with the tangential direction of the recording track and disposed via the optical axis of the objective lens; a first magnet unit including two magnets having magnetic poles in the radial direction of the recording track, arranged such that the magnetic pole faces of the same polarity face each other across the winding surface of the first coil; Two sets of magnet units each having two magnets having magnetic poles in the tangential direction of the recording track, one with an N pole and the other with an S pole facing the winding surface of the second coil, are arranged so that the optical axis is aligned with the optical axis. one N pole is arranged to face the other S pole through the first
and an optical pickup arranged so that the centers of the second coil in the optical axis direction substantially coincide with each other.