JPS59139149A - Optical pickup - Google Patents

Abstract

PURPOSE:To obtain a movable range for required tracking and focusing control by fitting a pair of coils which are inclined in the opposite directions to each other with respect to a focusing direction to a lens barrel and crossing magnetic flux in the diameter directions of the coils by using a magnet. CONSTITUTION:If a current in a direction shown by I1 is allowed to flow into a coil 14 and a current shown by I2 is allowed to flow into a coil 15, electromagnetic force is generated between a current flowing into the straight line parts 14a, 14a' of the coil 14 and the most part of the coil 15 and the magnetic flux of a gap. The figure shows the electromagnetic force. In the figure, F1 is the force generated in the coil 14, F2 is the force generated in the coil 15 and these components are located in a plane including a Z-Z axis and an X-X axis and form an angle theta with the Z-Z axis. Therefore, driving force for optional tracking control and focusing control can be obtained by selecting the current I1 flowing into the coil 14 or the current I2 flowing into the oil 15.

Description

[Detailed Description of the Invention] (1) - Industrial Application Field The present invention uses a laser or the like as a light source and focuses it on a desired position on a disk-shaped information recording medium (hereinafter referred to as a disk) to record information such as images and audio information. This invention relates to an optical pickup for an optical recording/reproducing device that records or reproduces.

Conventional configurations and their problems In recent years, with the practical use of optical recording and reproducing devices such as video discs, DADs (digital audio discs), and optical disk file devices, there is a need for smaller optical pickups and higher performance. sexuality is increasing. By the way, this optical pickup mainly consists of an aperture lens, but it also has focusing control that corrects focus deviations that normally occur due to surface runout of the disk, and tracking control that corrects tracking deviations that occur due to disk eccentricity, etc. Equipped with equipment to do this. That is, a conventional optical pickup is shown in FIG. 1 is a semiconductor laser, 2 is a laser beam, 3 is a reflecting mirror, 4 is an aperture lens, 5 is a disk, 6 is a lens mirror M, 7, 7' (2) Tracking that drives the lens barrel 6 in its radial direction Drive coils 8 and 8' are tracking drive magnetic circuits; 9 is a focusing drive coil that drives the lens barrel 6 in its axial direction;
Reference numeral 10 indicates a focusing drive magnetic circuit, and reference numerals 11 and 12 indicate elastic support members. This conventional optical pickup is
When a tracking correction current is applied to the tracking drive coil 7.7' from the tracking error detection circuit (not shown), an electromagnetic force is generated between the tracking drive coil 7.7' and the top king drive magnetic circuit 8.8', and the aperture lens 4 is moved by the elastic support member. Tracking control is performed by moving in the X-x direction (radial direction of the lens barrel 6) in the figure until the elastic force is balanced with the elastic force of 11.12. Similarly, focusing control is performed by focusing drive coil/I
/9 and the focusing drive magnetic circuit 10 by moving the aperture lens 4 in two directions by electromagnetic force.

However, in this optical pickup, the tracking and focusing coils and magnetic circuits are separated and placed independently, which makes it difficult to downsize in the focus adjustment direction, that is, to lower the height of the optical pickup. . Furthermore, since the tracking drive coil is arranged in the radial direction of the disk, the dimensions of the optical pickup in the tracking adjustment direction become large, which limits the ability to use the inner peripheral portion of the disk as a recording area. Furthermore, it is necessary to provide a gap between the tracking coil and the tracking magnetic circuit in the focus adjustment direction outside the movable range during focusing movement, resulting in the problem that it is difficult to lower the height of the optical pickup. Was.

OBJECTS OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned conventional drawbacks and to provide a compact optical pickup that can provide a desired tracking and focus control movable range.

Structure of the Invention This invention holds an aperture lens and elastically holds a companion lens barrel with a support so as to be movable in the focus adjustment direction and the tracking adjustment direction, and focuses in the axial direction within a plane including the focus adjustment direction and the tracking adjustment direction. A pair of coils tilted in opposite directions with respect to the adjustment direction are fitted into the boundary portion, and a magnet interlinks magnetic flux in the radial direction of these coils. As a result, it is possible to reduce the dimensions in the focus adjustment direction and the tracking adjustment direction compared to the conventional one, and it is possible to achieve miniaturization without losing the desired movable range.

Embodiment An embodiment of the present invention is shown in FIGS. 2 to 5. That is, in FIGS. 2 and 3, the X-y axis is the moving direction in which the optical pickup corrects the tracking error signal, the 2-2 axis is the moving direction in which the optical pickup corrects the focus error signal,
The Y-Y axis is a direction substantially perpendicular to both the X-y axis and the z-2 axis. 4' is an aperture lens, 6' is a lens barrel that accommodates the aperture lens 4', and 12 is an elastic support member that supports the lens barrel 6' movably in the directions of the x-y axes and the Z-2 axis. . 1331913a' has a magnetic pole direction of y-
It is a magnet that coincides with the y-axis, and is placed across the lens barrel 6' so that its north poles face each other.

(5) 13b and 13b' are magnets whose magnetic pole direction coincides with the X-y axis, and are arranged across the lens barrel 6' so that their south poles face each other. 13C is magnet 13
There is a yoke that connects a e 13a'+ 13b e 13b', 13 is magnet 1aa @ 13a'# 1
This is a magnetic circuit consisting of 3b t 13b'. In this magnetic circuit 13, as shown by a dashed line, there are magnets 138,
Magnet 13b from the north pole of 138'.

The magnet 13a passes through the yoke 13C toward the S pole of 13b'.
.

A magnetic path returning to the S pole of 13a' is formed, and the lens barrel 6' and magnet 13a # 13a'# 13b j 1
Air gap magnetic flux is generated in the air gap with 3b'. 14 is a first moving coil whose coil axis direction is in the B-B direction in FIG. This is a second moving coil that is symmetrical with respect to the AA direction, that is, the BB direction, and the z-2 axis in FIG. The first moving coil 14 and the second moving coil/
Each I/15 is connected to the lens barrel 6 via a connecting portion 16.

FIG. 4 shows details of the coil 14, which has a rectangular frame shape and consists of straight portions 14a, 14a'l, 14b, and 14b' (6). ■This is the current flowing through the avoidance coil 14.

The operation of this optical pickup will be explained.

As shown in FIG. 3, when a current in the direction indicated by I □ is passed through the coil 14 and a current indicated by An electromagnetic force is generated between the current flowing through the air gap and the air gap magnetic flux. Figure 5 shows the electromagnetic force.

In this figure, F is the force generated in the coil 14.
l), F are forces generated in the coil 15, which are located within a plane including the z-2 axis and the X-X axis, and are at an angle θ with the Z-Z axis.
is doing.

Therefore, the driving force for focus control is expressed as F2 = (F + p2)wθ, and the driving force for tracking control is:
It is expressed as Fx=(F engineering+F2) iunθ. Therefore, by selecting the current (2) flowing through the coil 14 and the current (2) flowing through the coil IIC, any driving force for tracking control and focus control can be obtained.

Because of this configuration, according to this embodiment, the magnet 1
Magnetic circuit 13 consisting of 3a I 138', 13b l 13b' and yoke 13C, and coils 14.15
In combination with this, it is possible to integrate the tracking and focusing drive parts that are open on both sides, and it is possible to provide a compact optical pickup that can obtain the desired movable range.

As another embodiment of the present invention, for example, a magnet 138°13
The magnet 13b is arranged such that the south pole and the south pole face each other.

The same effect can be achieved by arranging 13b' so that the north poles face each other.

In addition, as another example, magnet 138.13a'
A magnetic circuit having only one layer may be used. In this case, in order to obtain the same driving force, the shapes of the magnets 138 and 13a' are larger than those in the first embodiment, but the magnets 13b and
, 13b' are unnecessary, and the X-X axis can be made smaller.

Note that the axial directions of the coils 14 and 15 do not have to be symmetrical with respect to the focus control direction. This is because the current can be controlled.

As described above, according to the optical pickup of this invention, 2
In order to obtain power for both focusing and tracking by a combination of two fixed magnets and a pair of movable coils that are fitted into the lens barrel and intersect diagonally, a gap in the height direction is provided between the tracking coil and the magnetic circuit. In addition to eliminating the need for optical pickup, the height of the optical pickup can be lowered, the entire device can be made thinner, and the dimensions of the optical pickup in the disk radial direction can be reduced. It has a great practical effect because it can be used for many purposes.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional example, Fig. 2 is a front view of an optical pickup according to an embodiment of the present invention, Fig. 3 is a plan view thereof, Fig. 4 is a perspective view of a moving coil, and Fig. 5 is an operation. It is an explanatory diagram. 4'... Aperture lens, 6'... Lens barrel, 12... Elastic support member, 13... Magnetic name circuit, 13a e 13
a'* 131) e 13b"" magnet, 14.15・
...Movable coil (9) Fig. 1 Fig. 3 Fig. 14 Fig. 4 Fig. 5

Claims (1)

[Scope of Claims] (A lens barrel having an 11-diaphragm lens; a support member that elastically holds the lens barrel so as to be movable in the focus adjustment direction and the tracking adjustment direction; A pair of coils located in a plane including the focus adjustment direction and the tracking adjustment direction and tilted in opposite directions with respect to the focus adjustment direction, and a fixed magnet that generates magnetic flux interlinking in the radial direction of these coils. (2) The fixed magnet includes a pair of magnets with the same polarity facing each other in the tracking adjustment direction with the lens barrel in between, and a pair of magnets with the same polarity facing each other in the tracking adjustment direction with the lens barrel in between. The optical pickup according to claim 1, comprising a pair of magnets that are at right angles to each other and have magnetic poles different from those of the magnet and opposite magnetic poles, and have the same polarity facing each other.