JPH0222812Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pickup objective lens driving device used in an optical information recording/reproducing device.

2. Description of the Related Art In recent years, techniques for recording and reproducing information such as video and audio on disks using optical technology have been developed and are being widely used. The pick-up objective lens of an optical disk information recording/reproducing device is required to be capable of focusing adjustment in order to correct the distance error with the disk surface, and it is also necessary to pull the objective lens into a range where the above focusing adjustment is possible. In order to facilitate so-called servo retraction, it is required to improve the positional accuracy of the objective lens when the drive device is kept stationary at all times when it is in a non-driving state.

Conventionally, in order to meet the above requirements, the objective lens was able to be adjusted within a certain range in the focusing direction by an electromagnetic drive means composed of a coil and a magnet, and the objective lens was always in a non-driven state. In order to hold the lens stationary at the movable center position, metal plate springs or rubber elastic bodies with restoring force have often been used.

However, metal leaf springs are prone to bending and distortion, which tends to cause the objective lens to become erroneous in its stationary holding position, and its shape tends to cause harmful resonance phenomena. The drawback was that the degree of freedom was limited. Furthermore, it is generally difficult to achieve dimensional accuracy with rubber elastic bodies, and if they are small and thin, it is difficult to obtain the desired shape and characteristics.In order to suppress variations in the static holding position of the lens, parts management and installation must be carried out. In addition to requiring careful attention and significantly reducing work efficiency, it also has disadvantages such as high temperature dependence and easy change in characteristics, which narrows the operating temperature range. In addition, metal plate springs and rubber elastic bodies have various drawbacks, such as fatigue, weather resistance, and aging, and generally poor long-term reliability.

The purpose of the present invention is to eliminate the above-mentioned drawbacks and improve the positional accuracy of holding the objective lens of the pick-up stationary in the focusing direction with a simple configuration, thereby making it easier to pull in the servo and keeping the objective lens stationary in the focusing direction. We provide a pick-up objective lens drive device that can perform correction drive smoothly without causing resonance phenomena, and is stable and highly reliable against temperature changes, changes over time, repeated vibrations for correction, etc. It is to be.

Hereinafter, the present invention will be explained along with the illustrated embodiments. Figures 1 and 2 show an embodiment of a pickup objective lens driving device in which the pickup objective lens is driven in the upper and lower X-axis directions, that is, in the focusing direction in Figure 1, in order to correct focusing errors. be. The lower end of a hollow cylinder 2 is fixed to the center of the bottom 1a of the U-shaped base 1, and a sliding cylinder 4 of a driven support 3 is fitted onto the outer periphery of the hollow cylinder 2 so as to be able to slide up and down. has been done. The driven support 3 is driven and guided using the hollow cylinder 2 as a guide. An objective lens 5, which is a component of the pickup, is mounted and fixed on the upper end of the sliding cylinder 4 via a cylinder 6. On both sides of the lower outer periphery of the sliding cylinder 4, magnetic bodies 7 and 8 are symmetrically fixed, respectively, and coils 9 and 10 are wound around them.

Both bent parts 1b and 1c of the base body 1 are arranged symmetrically on both sides of the hollow cylinder 2, and the bent parts 1
Magnets 13, 14 and 15, 16 forming a magnetic circuit via magnetic plates 11, 12 are located at positions where the tips of the magnetic bodies 7, 8 are opposite to each other on the inside of b, 1c.
are fixed respectively. The magnet, coil, and magnetic body constitute electromagnetic drive holding means.
That is, when the coils 9 and 10 are energized, the driven support 3 is driven by the electromagnetic force acting between the magnetic field generated in the coils 9 and 10 and the magnetic circuit formed by the magnet. When the coils 9 and 10 are not energized, the driven support 3 balances the magnetic force of the magnetic closed circuit composed of the magnets 13 and 15 and the magnetic body 7, and the magnets 14 and 16 and the magnetic body 8, respectively. It is configured to be held stationary at a point where the magnetic force is neutral.

The operation of correcting the focusing error when the pickup drive device is configured as described above will be described in further detail. The ends of the magnetic bodies 7 and 8 facing the magnet are connected to the coils 9 and 1, respectively.
When the magnetic bodies 7 and 8 are excited to the north pole by the correction current flowing through the magnet 1, the magnetic bodies 7 and 8
3 and 14, and is repelled by the lower magnets 15 and 16, causing the driven support 3 to slide upward in accordance with the amount of current. Furthermore, when the current direction of the coils 9, 10 is changed and the tips of the magnetic bodies 7, 8 are excited to the S pole, the magnetic bodies 7, 8 are attracted by the lower magnets 15, 16 according to the amount of current. , is repelled by the upper magnets 13 and 14 and slides in the downward direction.

At this time, the magnets 13, 15 and 14, 16, the coils 9 and 10, and the magnetic bodies 7 and 8 constituting the electromagnetic drive holding means are placed symmetrically on both sides of the hollow cylinder 2 serving as the guide section. Since I placed it,
The sliding movement of the driven support 3 can be performed smoothly without causing a resonance phenomenon, and the magnets 13, 15 and 14, 16 are aligned with the coils 9, 10 and the magnetic bodies 7, 8 in the focusing direction. Since the structure is such that the driven support 3 is placed facing each other in a horizontal position perpendicular to (see Fig. 1), the driven support 3 is stably kept at the neutral point of the magnetic force when no current is applied, and it is kept at a precise standstill. can be retained.

Winding direction of the above coils 9 and 10 and magnet 1
The relationship between the magnetized poles 3, 14, 15, and 16 can be arbitrarily configured so that the above-mentioned sliding movement is performed. For example, the coils are arranged so that the excitation poles of the magnetic bodies 7 and 8 are different from each other. The winding direction and the current direction may be changed, and the magnetic poles of the magnets 13 to 16 may be made to correspond to the winding direction and the direction of energization, thereby controlling the raising and lowering of the driven support 3. Furthermore, the above-mentioned magnet may be constructed by subjecting one magnet material to two sets of upper and lower magnets having different polarities, as shown in FIG. Further, it is desirable that the hollow cylinder 2 and the sliding cylinder 4 be formed of a material with a low coefficient of friction.

The embodiments shown in FIGS. 4 and 5 are other embodiments of the pickup driving device in which the objective lens of the pickup can perform both focusing error correction and tracking error correction. The first driven support 17 on which the objective lens 5 is mounted and fixed is slidably incorporated into the second driven support 18 in the X-axis direction perpendicular to the plane of the paper in FIG. 4, that is, in the focusing direction. ing. Further, the second driven support body 18 includes a plurality of pins 20 provided on the base body 19.
It is slidably assembled in the Y-axis direction up and down along the plane of the paper, that is, in the tracking direction. The first driven support 17 is
It is constructed in the same manner as the driven support 3 shown in FIGS. It is held slidably.

At the inner upper and lower positions on both longitudinal sides of the second driven support 18 (see FIG. 5), there are magnets 2.
1, 22 and 23, 24 are fixed opposite to the magnetic bodies 7, 8, while magnetic bodies 25, 26 and coils 27, 28 are arranged on the outer sides of the second driven support 18 in the longitudinal direction. The magnets 29, 30 and 31, 32, which are provided and fixed to the base body 19, are arranged to face each other, respectively.

The first and second driven supports 17 and 18, like the driven supports 3 of FIG. 1, are maintained at the neutral point of the magnetic force when no current is applied. Correction of focusing error and tracking error is as follows.
By passing correction currents through the coils 9, 10 and 27, 28, respectively, the first and second driven supports 1
7 and 18 are slidably driven in respective correction directions.

FIG. 6 shows another application example in which the second driven support 18
In this embodiment, one end is extended and rotatably supported on the base body 1 by a support shaft 33. A coil 28 is attached to the magnetic body 26 on the outside of the other end of the second driven support 18 .
is wound and placed opposite to the magnets 31 and 32 inside the bent portion 1c of the base body 1. Also,
The magnets 21, 22, 23, 24 provided inside the second driven support 18 are constructed in the same manner as in FIG. has been done. In this application example as well, the magnetic bodies 7 and 8 are
and 26 are held at the neutral point of the magnetic force with the magnet when the coils 9, 10 and 28 are not energized, and when the coils are energized,
Due to the magnetic poles generated in each of the above magnetic materials, the
The driven support 17 is slid in the X-axis direction perpendicular to the plane of the paper to eliminate focusing errors, and the second driven support 18 is rotated about the support shaft 33 in the vertical Y-axis direction along the plane of the paper. Tracking errors are respectively corrected.

As described above, the present invention comprises: a driven support on which a pick-up objective lens is placed and driven in the focusing direction; a base having a guide portion for driving and guiding the driven support in the focusing direction; The electromagnetic drive holding means of a pick-up objective lens drive device is provided with an electromagnetic drive holding means constituted by a magnet forming a magnetic circuit on either one of the support body and the base body, and a coil and a magnetic body arranged on the other side. In particular, the guide portion is arranged symmetrically on both sides of the guiding portion so that the electromagnetic acting force in the direction perpendicular to the focusing direction is canceled out, and the magnet of the electromagnetic drive holding means, the coil and the magnetic With this structure, by energizing the coil, the driven support body can be moved perpendicular to the focusing direction. The driven support body can be driven so that the electromagnetic forces in the directions are canceled out, and the driven support body can be smoothly driven in the focusing direction without causing a resonance phenomenon. At the same time, when the coil is not energized, the driven support is moved to the neutral point of the magnetic closed circuit formed by the magnet and the magnetic material by a magnetic force in a direction perpendicular to the focusing direction. Can maintain and maintain high positional accuracy,
This also makes it possible to easily pull in the focusing servo. Furthermore, since there is no need to use leaf springs or rubber elastic bodies,
In addition to being able to obtain stable characteristics over a long period of time with no changes over time or temperature, the number of parts can be reduced.
It has now become possible to provide a pick-up objective lens driving device that is small and inexpensive and has excellent practical effects.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a partially sectional side view of a pickup objective lens drive device equipped with a driven support that is driven in the X-axis direction, and FIG. A plan view of an objective lens drive device, FIG. 3 is an explanatory diagram of another embodiment regarding magnetization of a magnet, and FIG. 4 is a pick-up device equipped with a driven support body driven in the X-axis direction and the Y-axis direction, respectively. FIG. 5 is a partially sectional side view of the same, and FIG. 6 is a plan view of another application example. 1, 19... Base body, 2... Hollow cylinder (guide part),
3, 17, 18... Driven support body, 7, 8, 2
5, 26...magnetic material, 9, 10, 27, 28...
Coils, 13-16, 21-24, 29-32...
...Magnet.

Claims (1)

[Claims for Utility Model Registration] A driven support body on which a pick-up objective lens is placed and driven in the focusing direction, a base body having a guide portion for driving and guiding the driven support body in the focusing direction, and electromagnetic drive holding means configured by arranging a magnet forming a magnetic circuit on either one of the support body and the base body and a coil and a magnetic body on the other; The magnet is arranged symmetrically so that the electromagnetic force in the direction perpendicular to the focusing direction is canceled out, and the magnet of the electromagnetic drive holding means, the coil, and the magnetic body are arranged perpendicular to the focusing direction. By energizing the coil, the driven support is driven by the electromagnetic force of the electromagnetic drive holding means, and when the coil is not energized, the electromagnetic drive is held. A pickup objective lens driving device characterized in that the driven support is held at a neutral point of the magnetic force of the means.