JPH06215384A - Optical pickup device - Google Patents

Abstract

PURPOSE:To reduce a number of power feeders connected to a movable optical system and to smooth the seeking movement of the movable optical system. CONSTITUTION:This device is provided with an objective lens 10 and an objective lens actuator for making the objective lens 10 perform focusing operation and a carriage 12 moving linearly on the seeking rails 6, 6 is provided on a seeking base 5. Fixed coils 7, 7 which are devided into plural parts, respectively, are arranged on both sides of the carriage 12 and a soft magnetic material 8 is provided inside the fixed coils 7, 7. Permanent magnets 15, 15 are fixed on the carriage 12 so as to oppose to the fixed coils 7, 7. By causing a current to flow through the fixed coils 7, 7, Lorentz force is generated in the permanent magnets 15, 15 and the movable optical system 4 moves for seeking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device for recording / reproducing information on / from an information recording medium such as an optical disc, which is applied to an optical disc device or a magneto-optical disc device.

[0002]

2. Description of the Related Art An optical pickup device is, as is well known,
By guiding the laser light to the objective lens by the optical system, the objective lens focuses the laser light and irradiates it to the information track on the optical disc which is the information recording medium, and further detects the reflected light from the optical disc by the light receiving element or the like. , Recording / reproducing information.

As an example, there is a technique described in Japanese Patent Laid-Open No. 2-68730. In this Japanese Patent Application Laid-Open No. 2-68730, the magnetic force generated by one magnetic circuit is made to correspond to the magnetic force generated by each of the focusing coil, the tracking coil, and the seek coil, and the focusing operation and the tracking operation are performed. , A technique of performing three kinds of operations of seek operation is disclosed.

[0004]

However, in the technique described in Japanese Patent Application Laid-Open No. 2-68730, in order to make three kinds of coils correspond to one magnetic circuit, the three kinds of coils are both sought. It is incorporated in a movable optical system that irradiates the optical disc with focused light while moving.
Further, in order to generate a magnetic field in each of the three types of coils, a power supply line for supplying power to each coil is connected to each coil.

However, as the number of power supply lines increases, the number of assembling work increases due to the increase in the number of wire connection works, and the load due to the pulling of the power supply lines during seek movement increases, which hinders seek movement. Further, the space for moving the power supply line also increases, which makes it difficult to downsize the device.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems, to reduce the number of power supply lines connected to a movable optical system, to save power, and to provide a pickup device which is downsized.

[0007]

In order to achieve the above object, the present invention provides an objective lens actuator for driving an objective lens that forms a light spot on an information recording medium in at least an optical axis direction, and an objective lens actuator. In an optical pickup device including a mounted carriage and a seek motor that drives the carriage in a direction that traverses an information track on the surface of an information recording medium, a permanent magnet that includes the seek motor in the carriage and the permanent magnet It is characterized by comprising a plurality of fixed coils facing each other and arranged in parallel to the moving direction of the carriage.

Further, in the above structure, the length of each of the plurality of fixed coils in the seek direction is longer than the length of the permanent magnet mounted on the carriage in the seek direction.

Further, according to the present invention, an objective lens actuator for driving an objective lens for forming a light spot on the information recording medium in at least the optical axis direction, a carriage for mounting the objective lens actuator, and an information track on the surface of the information recording medium are provided. In the optical pickup device including a seek motor that drives the carriage in a transverse direction, the objective lens actuator and a magnetic force are applied to the objective lens actuator inside bent portions of both ends formed in the carriage. A magnetic circuit, a deflection prism for guiding a light beam to the objective lens, and a power feeding line connected to a coil provided in the objective lens actuator to feed power are provided.

In the above structure, the magnetic flux of the permanent magnet provided in the magnetic circuit of the objective lens actuator and the magnetic flux of the permanent magnet provided in the magnetic circuit of the seek motor are oriented in the same direction. And

[0011]

Since the fixed coil is divided and a plurality of fixed coils are arranged by adopting the above-described structure, when the carriage is driven, it is sufficient to generate a magnetic force in the fixed coil facing the permanent magnet provided in the carriage. Therefore, the coil resistance value becomes small and power saving can be achieved.

Further, since the length of each of the plurality of fixed coils in the seek direction is longer than the length of the permanent magnet mounted on the carriage in the seek direction, the permanent magnets are connected to the joints between the coils. It does not face two or more joints at the same time.

Further, since the objective lens actuator and its magnetic circuit, the deflection prism, and the feed line are arranged inside the carriage made of sheet metal whose both ends are bent, the height of the carriage and the moving space of the objective lens actuator, the deflection prism, and the feed line are arranged. Can overlap with the height of.

Further, since the direction of the magnetic flux of the permanent magnet forming the magnetic circuit of the objective lens actuator and the direction of the magnetic flux of the permanent magnet forming the magnetic circuit of the seek motor are set to the same direction, leakage generated from each magnetic circuit. The magnetic flux acts on each other in the direction of increasing the magnetic flux.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing the configuration of the first embodiment of the present invention, in which 1 is an optical disk which is an information recording medium, 2 is a spindle motor for rotating the optical disk 1, and 3 is a fixed optical system. Inside the fixed optical system 3, a light source for generating a laser beam, a collimating lens for making diffused light from the light source into parallel light, and reflected light from the optical disc 1 are detected and photoelectrically converted into a reproduction signal. A known optical system such as a light receiving element or a light receiving element for detecting the deviation of tracking or the size of a light spot is provided.

Reference numeral 4 denotes a movable optical system which irradiates the optical disc 1 with focused light, sends the reflected light to the fixed optical system 3, and moves in the radial direction of the optical disc 1, 5 is a seek base, 6
Shows the seek rails formed on both sides of the seek base 5. The movable optical system 4 is placed on the seek base 5,
Further, the movable optical system 4 makes a linear motion on the seek rails 6, 6.

Reference numeral 7 denotes fixed coils installed on both sides of the movable optical system 4. This fixed coil 7 is composed of a plurality of coils (four in FIG. 1), and these element coils 7a, 7b, 7c, 7d that form the fixed coil 7 are fed with power independently of each other. To be done. Further, a shaft-shaped soft magnetic body 8 is inserted into the fixed coils 7, 7.

The spindle motor 2, the fixed optical system 3, the seek base 5, and the fixed coils 7, 7 described above are fixed on the drive base 9.

Reference numeral 10 denotes an objective lens which focuses parallel light from the fixed optical system 3 to form a light spot on an information track of the optical disc 1, and 11 has the objective lens 10 placed at the center,
A bobbin around which a focusing coil (described later) is wound, 12 is a carriage made of sheet metal, 13 is one end attached to the carriage 12, and the other end is attached to the bobbin 11,
A leaf spring that supports the bobbin 11 and a yoke 14 are provided. The yoke hole 11a of the bobbin 11 is loosely fitted in the yokes 14, 14.

Reference numeral 15 denotes a permanent magnet fixed to the carriage 12 so as to face the focusing coil of the yoke 14 and the bobbin 11. This permanent magnet 15,15 is a fixed coil 7,
7, the widths of which are opposed to each other are element coils 7a, 7b, 7
It is smaller than the width of c and 7d. Reference numeral 16 denotes a flexible substrate that sends current to the focusing coil.

The movable optical system 4 is constituted by the objective lens 10, the bobbin 11, the carriage 12, the leaf spring 13, the yoke 14, the permanent magnet 15, and other members provided on the carriage 12.

Reference numeral 17 denotes a deflecting prism, which is installed on the seek base 5 and deflects the optical path of the parallel light emitted from the fixed optical system 3 to guide it to the movable optical system 4.

FIG. 2 is a perspective view showing the structure of the carriage 12. As shown in FIG. 2, the carriage 12 is formed by processing a rectangular sheet metal.

In FIG. 2, 18 is a slide table formed by bending both sides of a sheet metal, 19 is a groove formed inside the slide table 18, and 20 is the center of a bent portion for forming the slide table 18. A concave portion 21 formed by cutting out is a bent portion for fixing a reflection prism (described later) that guides laser light to the objective lens 10 shown in FIG. The bent portion 21 is formed such that the central portion of the sheet metal is cut and raised in the same direction as the slide table 18 and the cut and raised surface is perpendicular to the surface of the slide table 18.

Reference numeral 22 indicates a central hole formed in the central portion of the sheet metal by the bent portion 21. The yoke 14 is formed by cutting and raising both sides of the central hole 22 in the direction opposite to the slide table 18.

FIG. 3 is a sectional view taken along the line AA of FIG. 1, 23 is a reflecting prism fixed to the bent portion 21 of the carriage 12 shown in FIG. 2, 24 is a focusing coil wound around the bobbin 11, and 25 is a focusing coil. Is a carriage arranged between the groove 6a formed in the seek rail 6 and the groove 19 of the slide table 18.
12 shows a hard sphere to facilitate 12 seek movements. Also,
Permanent magnets 15 are installed in the recesses 20, 20 of the carriage 12.

Next, the operation of the movable optical system 4 will be described.

By passing a current through the element coil 7b facing the permanent magnet 15, a magnetic field is generated, and the Lorentz force acts on the permanent magnet 15 by this magnetic field, causing the movable optical system 4 to seek. When the movable optical system 4 makes a seek movement,
When the permanent magnet 15 is located at a joint between coils, for example, between the element coil 7b and the element coil 7c, a coil that generates a magnetic field is changed from the element coil 7b to the element coil 7c.
By switching to, the movable optical system 4 continuously seeks.

The tracking operation is performed by moving the movable optical system 4 by sending a current to the fixed coil 7 according to the output of the light receiving element which detects the tracking deviation in the fixed optical system 3. Further, the focusing operation is performed by moving the objective lens 10 up and down by sending an electric current to the focusing coil 24 through the flexible substrate 16 according to the output of the light receiving element that detects the deviation of focusing in the fixed optical system 3. Be seen.

FIG. 4 is a plan view showing a second embodiment of the present invention. The same members as those shown in FIG. 1 are designated by the same reference numerals.

In FIG. 4, 26 is a carriage formed by processing a rectangular sheet metal, 27 is a coil fixed on both sides of the carriage 26, 28 is an inner yoke loosely fitted in the coil 27,
29 is an outer yoke attached to both ends of the inner yoke 28 and fixed to the drive base 9, and 30 is a coil of the outer yoke 29.
27 shows a permanent magnet fixed to the facing surface of 27.

Further, 31 is a bobbin on which the objective lens 10 is placed in the central portion, 32 is a flat focusing coil fixed to both side surfaces of the bobbin 31, and 33 is a focusing coil.
A permanent magnet facing 32 is shown. The bobbin 31 is supported by the leaf spring 13 and attached to the carriage 26. 34 is a central hole formed on the surface of the carriage 26, and 35 is a coil 27.
And a flexible substrate for feeding power to the focusing coil 32.

FIG. 5 is a sectional view taken along the line AA of FIG. 4, and 36 is
The slide table of the carriage 26 is formed by bending both ends of the sheet metal in the same direction, and 37 is a U-shaped yoke.

The carriage 26 is movably mounted on the seek base 5 by installing the slide table 36 on the seek rail 6 via the hard sphere 25. The coils 27, 27 are fixed to the outer surfaces of the slide tables 36, 36, and one outer side surface of the yokes 37, 37 is fixed to the inner surfaces. Further, the reflection prism 23 is held by the other outer side surfaces of the yokes 37, 37 facing each other.

Further, on one side surface inside the yokes 37, 37,
The permanent magnets 33, 33 are fixed. This permanent magnet 33,33
Are located on substantially the same straight line as the permanent magnets 30, 30 fixed to the outer yoke 29, and the magnetic flux directions of both permanent magnets 30, 33 are the same.

Furthermore, the seek base 5 and the yokes 37,3
A flexible board 35 is arranged between the flexible board 35 and the board 7. This flexible substrate 35 is provided on the seek base 5 so as not to hinder the movement of the carriage 26 in the seek direction.
And bend inside the yoke 37,37.

Next, the operation of the movable optical system 4 according to the second example will be described.

Coil 27, 27 through flexible substrate 35
By supplying a current to the coils 27, a driving force is generated in the coils 27, 27, and the movable optical system 4 makes a seek movement. Further, according to the output of the light receiving element that detects the tracking deviation in the fixed optical system 3, the coils 27, 27 are passed through the flexible substrate 35.
A current is sent to, and the movable optical system 4 is moved to perform the tracking operation. Further, by sending a current to the focusing coil 32, the objective lens 10 moves up and down and the size of the light spot is adjusted.

By adopting the configuration described above in this embodiment, the following operational effects can be obtained.

First, according to the configuration of the first embodiment, since the movable optical system 4 has no coils other than the focusing coil 24, only the focusing coil 24 needs to be connected to the flexible substrate 16. Therefore, the connection work is facilitated and the lightweight movable optical system 4 can be realized. Moreover, by repeating the seek operation of the movable optical system 4, since the number of power feedings is small, the risk of disconnecting the connection between the coil terminal of the focusing coil 24 and the flexible substrate 16 is reduced.

Further, since the fixed coil 7 is divided and a plurality of fixed coils are arranged, the coil resistance value becomes small, and power saving can be achieved. Further, since the permanent magnet 15 faces only one place at the joint between the element coils at the same time, it is possible to perform stable and smooth seek movement and acceleration / deceleration of the movable optical system 4.

Further, by passing a current through the fixed coil 7 to perform the seek movement and the tracking operation of the movable optical system 4, the movable optical system 4 itself need only perform the focusing operation, so that the apparatus can be simplified.

With the configuration of the second embodiment, the carriage
By fixing the yokes 37, 37 in the 26, and by holding the reflecting prism 23 by the yokes 37, 37, the yoke 3
Reference numerals 7 and 37 serve also as a holding member of the reflection prism 23 and a constituent member of an objective lens actuator for moving the objective lens 10 in the focusing direction. Therefore, since the distance between the objective lens 10 and the reflection prism 23 can be reduced,
Within the height range of the carriage 26, the objective lens 10 and bobbin 3
1, members such as the reflection prism 23 and the flexible substrate 35 can be arranged, and the device can be made thin.

Since the direction of the magnetic flux of the permanent magnet 33 forming the magnetic circuit of the objective lens actuator is the same as the direction of the magnetic flux of the permanent magnet 30 forming the magnetic circuit of the seek motor, the direction shown in FIG. As described above, since the leakage magnetic flux B generated from each magnetic circuit acts in the direction in which the magnetic flux increases, the thrust of the objective lens actuator and the seek motor can be increased.

[0046]

By constructing the present invention as described above, the following effects can be obtained.

According to the first aspect of the present invention, the objective lens actuator mounted on the carriage is required to perform at least the focusing operation. Therefore, the apparatus can be simplified and it is necessary to mount a member such as a tracking coil on the carriage. Since the carriage is not provided, the weight of the carriage and the number of parts can be reduced. Further, since it is sufficient for the carriage to include at least the focusing coil, the number of connections to the movable optical system for supplying power is reduced, and the assembling work is facilitated. Furthermore, by providing a plurality of fixed coils, a seek movement is performed by passing an electric current through the fixed coils facing the permanent magnets provided on the carriage, so that power saving can be achieved.

According to the second aspect of the invention, it is possible to easily switch the current between the element coils of the fixed coil, and to perform stable and smooth seek operation.

With the structure according to the third aspect, it is possible to reduce the distance between the reflecting prism and the objective lens,
The size of the device can be reduced.

According to the structure of claim 4, the direction of the magnetic flux of the permanent magnet forming the magnetic circuit of the objective lens actuator and the direction of the magnetic flux of the permanent magnet forming the magnetic circuit of the seek motor are the same. Since the leakage magnetic fluxes generated from the respective magnetic circuits act in a direction in which the magnetic fluxes are mutually increased, it is possible to increase the thrust of the objective lens actuator and the seek motor.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of a first embodiment of the present invention.

FIG. 2 is a perspective view showing the configuration of a carriage according to the first embodiment.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a plan view showing a configuration of a second exemplary embodiment of the present invention.

5 is a cross-sectional view taken along the line AA of FIG.

FIG. 6 is an explanatory diagram showing a magnetic flux of a permanent magnet of a magnetic circuit according to a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 4 ... Movable optical system, 5 ... Seek base, 6 ... Seek rail, 7 ... Fixed coil, 8 ... Soft magnetic material, 10 ... Objective lens, 11, 31 ... Bobbin, 12, 26
… Carriage, 13… Leaf springs, 14, 37… Yoke, 1
5, 30, 33 ... Permanent magnet, 16, 35 ... Flexible substrate,
18, 36 ... Slide table, 20 ... Concave, 21 ... Bent, 22,34 ... Center hole, 23 ... Reflecting prism, 24,32
… Focusing coil, 27… Coil, 28… Inner yoke, 29… Outer yoke.

Claims (4)

[Claims] 1. An objective lens actuator for driving an objective lens for forming a light spot on an information recording medium in at least an optical axis direction, a carriage equipped with the objective lens actuator, and a direction traversing an information track on the surface of the information recording medium. In an optical pickup device including a seek motor for driving the carriage, the seek motor is arranged in parallel with a permanent magnet provided in the carriage, facing the permanent magnet, and parallel to a moving direction of the carriage. An optical pickup device comprising a plurality of fixed coils. 2. The optical pickup device according to claim 1, wherein the length of each of the plurality of fixed coils in the seek direction is longer than the length of the permanent magnet mounted on the carriage in the seek direction. 3. An objective lens actuator that drives at least an objective lens that forms a light spot on an information recording medium in the optical axis direction, a carriage that mounts the objective lens actuator, and a direction that traverses an information track on the surface of the information recording medium. In the optical pickup device including a seek motor that drives the carriage, the objective lens actuator, and a magnetic circuit that applies a magnetic force to the objective lens actuator, inside the bent portions formed at both ends of the carriage. An optical pickup device comprising: a deflection prism that guides a light beam to the objective lens; and a power supply line that supplies power by connecting to a coil provided in the objective lens actuator. 4. A magnetic flux of a permanent magnet provided in a magnetic circuit of an objective lens actuator and a magnetic flux of a permanent magnet provided in a magnetic circuit of a seek motor are oriented in the same direction. Item 3. The optical pickup device according to item 3.