CN100428345C - Three-dimensional objective lens driving device with tilt driving method - Google Patents

Abstract

The invention relates to a three-dimensional object lens driving device in an inclined driving mode, which belongs to the technical field of optical pickup heads in optical storage systems. In order to overcome the shortcomings of the existing three-dimensional objective lens driving device, which has too many coils and causes the sensitivity to drop or the three-dimensional driving independence is not strong, the present invention discloses a new type of tilt-driven three-dimensional objective lens driving device. Movable parts, and a magnetic field generating system composed of an outer yoke and a magnet. The core components of the present invention are four magnets and four coils, two of which are magnetized by boundaries, and the coils are fixed on the movable parts, and the coils are arranged vertically in pairs, so that the combined force couple of two couples can be used to drive the movable The part makes a tilting motion. The device not only reduces the weight of the movable parts of the objective lens driving device, ensures the sensitivity of the objective lens driving device, but also improves the independence of movement in all directions. The device also has the characteristics of few parts, low cost, simple and compact structure, easy processing and the like.

Description

Three-dimensional objective lens driving device with tilt driving method

technical field

The invention belongs to the technical field of optical pick-up heads in optical storage systems, and in particular relates to the design of an objective lens driving device with three-dimensional motion servo functions of focusing, tracking and tilting.

Background technique

In the optical disc storage system, the optical pick-up head is the actuator for reading the data from the optical disc. The optical pick-up head is mainly composed of two parts: the optical path structure and the objective lens driving device. In recent years, many two-dimensional objective lens driving devices with focusing and tracking functions have been disclosed in the literature. However, with the increase of the storage density, there is a higher requirement for the reading accuracy of the optical disc, or due to the requirement of the writable optical disc, the three-dimensional objective lens driving device is indispensable. In recent years, some three-dimensional objective lens driving devices have appeared. The three-dimensional objective lens driving device is usually composed of magnets, inner and outer yokes, fixed parts and movable parts supported by suspension wires. Some three-dimensional torque devices use six or more coils to drive the three-dimensional movement of the movable parts focusing, tracking and tilting respectively. The disadvantage of this method is that there are too many coils, which increases the weight of the movable parts of the objective lens drive device. , so that the sensitivity of the objective lens driving device decreases. There is also a three-dimensional torque device with four coils, but its tilting method will cause insurmountable interference force to the movement in the focus or tracking direction, or generate additional movement of movable parts, that is, the independence of three-dimensional movement is not strong, thus affecting Reading of disc data. The common feature of these torque devices is that the resultant torque is used to drive the movable parts to produce tilting motion. The resultant moment is generated because the two forces in the same direction are of different magnitudes.

Contents of the invention

In order to overcome the shortcomings of the existing three-dimensional objective lens driving device, which has too many coils and causes the sensitivity to drop or the three-dimensional driving independence is not strong, the present invention proposes a new type of tilt-driven three-dimensional objective lens driving device, including a fixed part, which is fixed on the fixed part The magnetic field generating system composed of the outer yoke and four magnets fixed on the outer yoke, and the movable part supported by the suspension wire fixed on the fixed part, the movable part includes the objective lens holder, the objective lens holder The objective lens on the top, and the four coils between the magnets are characterized in that: the four magnets in the magnetic field generating system are respectively the first focusing tilting magnet, the second focusing tilting magnet, the first tracking magnet and The second tracking magnet, wherein the first focusing tilting magnet and the second focusing tilting magnet are magnetized by boundaries, that is, the magnetic pole directions of the upper half and the lower half of the magnet are opposite, while the first tracking magnet and the second tracking magnet The magnets each have a single magnetic pole orientation;

The four coils are respectively the first focusing coil, the second focusing coil, the first tracking tilting coil and the second tracking tilting coil, the spatial arrangement direction of the first focusing coil and the first tracking tilting coil is vertical, and the first The spatial arrangement direction of the second focusing coil and the second tracking tilting coil is vertical;

The first tracking tilt coil, the first focus coil, the first focus tilt magnet and the first tracking magnet form a first driving force generating system, and the first focus coil is placed next to the first focus tilt magnet; Two tracking tilting coils, a second focusing coil, a second focusing tilting magnet and a second tracking magnet form a second driving force generating system, and the second focusing coil is placed next to the second focusing tilting magnet; the two driving forces The generating system is arranged centrally symmetrically.

The device of the present invention only uses four coils, which reduces the weight of the movable parts of the objective lens driving device, ensures the sensitivity of the objective lens driving device, improves the independence of movement in all directions, and can better meet the growing demand for optical discs. storage requirements. The device also has the characteristics of low cost, simple and compact structure, easy processing and the like.

Description of drawings

Fig. 1a is a schematic diagram of the overall structure of an embodiment of the present invention.

Figure 1b is a top view of Figure 1a.

Fig. 1c shows the structure and position of four magnets and four coils of the core component in Fig. 1a.

Fig. 2a is a schematic diagram of the principle of the present invention.

Fig. 2b is a directional diagram of Fig. 2a.

Fig. 3 is a structural diagram of the present invention after removing the outer yoke, which is a supplementary description of the structure of the present invention.

Figure 4 shows another arrangement of the core components of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Fig. 1 a and Fig. 1 b have shown an embodiment of the three-dimensional objective lens driving device of novel tilting driving mode of the present invention, and it comprises: by the fixed part that suspension wire support 1 and printed circuit board (PCB board) 2 are formed, by objective lens 5 , objective lens support 4, four coils and the movable parts that other two printed circuit boards (PCB boards) form, the magnetic field generation system that outer yoke iron 13 and four magnets form. The PCB board 2 is fixed on the suspension wire bracket 1 for connecting the suspension wire, and one end of the suspension wire is usually welded on the PCB board 2 by welding. Suspension wire brackets usually have a structure that is connected to the optical disc system. The four magnets are all fixed on the outer yoke 13. In addition to supporting the magnet, the outer yoke 13 can also make the magnetic field generated by the magnet more concentrated. The outer yoke 13 is fixed on the fixed part, and the movable part is supported by the suspension wire And located in the middle of the four magnets.

Above-mentioned structure is the general structure of existing three-dimensional objective lens driving device, and the feature of the present invention is: the space combination arrangement mode of four magnets and four coils on the movable part, the magnetization mode and the combination mode of direction of four magnets. Referring to FIG. 1 c , the four magnets are respectively a first focusing tilt magnet 10 , a second focusing tilt magnet 6 , a first tracking magnet 3 and a second tracking magnet 9 . The four coils are the first focusing coil 11, the second focusing coil 15, the first tracking tilting coil 12 and the second tracking tilting coil 8, and the coils are usually treated with glue so that the coils can keep their shape after winding. Change and not disperse. In order to avoid interference, the upper and lower horizontal parts of the focusing coil should not be too close, and there should be a certain amount of space in the middle. Structurally, it can be divided into two groups, the first tracking tilt coil 12, the first focusing coil 11, the first focusing tilting magnet 10 and the first tracking magnet 3 form a group to form a first driving force generating system. A focusing coil 11 is placed next to the first focusing tilting magnet 10; the second tracking tilting coil 8, the second focusing coil 15, the second focusing tilting magnet 6 and the second tracking magnet 9 form a second driving force generating system, the The second focus coil 15 is placed next to the second focus tilt magnet 6 . The shortest distance between the coil and the magnet is generally 0.2mm to 1mm. If it is too close, it will cause friction when moving, which will affect the disk reading. If it is too far away, the magnetic field at the position of the coil will become smaller, making the driving force insufficient. The magnetization directions of the four magnets are all parallel to the axial direction of the suspension wire, but the specific directions of the magnetization directions are different. The first focusing tilting magnet 10 and the second focusing tilting magnet 6 adopt demarcation magnetization, that is, the magnetic pole directions of the upper half and the lower half of the magnet are opposite, while the first tracking magnet 3 and the second tracking magnet 9 are not adopted. Boundary magnetization, where the two magnets each have a single magnetic pole orientation. The spatial arrangement direction of the first focusing coil 11 and the first tracking tilt coil 12 is vertical, and the spatial arrangement direction of the second focusing coil 15 and the second tracking tilt coil 8 is vertical. The two driving force generating systems are arranged symmetrically about the center.

The first focusing coil 11 and the second focusing coil 15 are wound into a rectangle as much as possible, and the coils are wound into a rectangle to make the driving force larger and improve the sensitivity. 11 and the second focusing coil 15 can also be wound into a circle. The first tilting tracking coil 12 and the second tilting tracking coil 8 are preferably wound in a rectangular shape, so that the force-generating parts thereof are as close as possible to the magnet.

In the above examples, the winding central axes of the first focusing coil 11 and the second focusing coil 15 are parallel to the axial direction of the suspension wire. However, for the convenience of manufacture, the direction of the central axis of the two may have a certain angle with the axial direction of the suspension wire. Similarly, the magnetization directions of the four magnets are generally parallel to the axial direction of the suspension wire, but may not be parallel in some cases. If the magnets and coils cannot be arranged strictly according to the embodiment shown in FIG. 1 a to FIG. 1 b due to structural arrangement requirements, the best effect can be obtained by adjusting the magnetization direction. Or in order to increase the magnetic field strength produced by the magnetized magnetization at the boundary, the magnetization direction of the upper and lower parts of the magnetized magnetization at the boundary can have a certain angle with the axial direction of the suspension wire.

Figure 2a illustrates the working principle of the present invention. Figure 2b is the direction indication diagram of Figure 2a, the tilting motion of the movable part is essentially a rotational motion, and its rotational direction is in the plane composed of the focusing motion direction and the tracking motion direction, with the axial direction of the suspension wire as the direction of the central axis of rotation . The first tracking tilt coil 12 produces force F1 in the magnetic field produced by the first tracking magnet 3, and the second tracking tilt coil 8 produces force F2 in the magnetic field produced by the second tracking magnet 9, controlling the first tracking magnet 3 and the direction of magnetization of the second tracking magnet 9 (i.e. controlling the direction of the magnetic field they produce) and the direction of the current in the first tracking tilt coil and the second tracking tilt coil so that F1 and F2 are in the same direction, F1 and F2 The resultant force is the driving force for the tracking motion of the movable parts. The first focus coil 11 produces force F3 in the magnetic field produced by the first focus tilt magnet 6, and the second focus coil 15 produces force F4 in the magnetic field produced by the second focus tilt magnet 10. The first focus tilt magnet 10 and the second focus The tilted magnets 6 are all magnetized at the boundary, so the magnetization direction of the upper and lower parts of each magnet is different, so the direction of the magnetic field generated is also different, and the current direction of the upper and lower parts of each coil is just opposite, so the upper and lower parts of each coil The direction of the force generated by the two parts is the same, so that the two coils can generate the resultant force F3 and the resultant force F4 respectively, and control the specific magnetization direction of the two focusing tilt magnets and the current direction of the two focusing coils, so that the directions of F3 and F4 are the same. The resultant force of F3 and F4 is the driving force of the focus movement of the movable part. Just because the direction of the magnetic field produced by the first focus tilt magnet 10 and the second focus tilt magnet 6 is demarcated, the magnetic field at the upper and lower parts near the vertical part of the first focus tilt magnet 10 of the first tracking tilt coil 12 Direction is different, so the direction of the force that its upper and lower two parts produces is opposite, therefore produced force couple M1; The magnetic field direction of the upper and lower parts where the vertical part of the second tracking tilting coil 8 is close to the second focusing tilting magnet 6 is Different, so the direction of the force generated by its upper and lower parts is opposite, so a force couple M2 is generated, which controls the magnetization direction of the two focusing tilt magnets and the current direction of the two tracking tilt coils, so that M1 and M2 are reversed, and their The resultant couple is the driving force for the tilting motion of the movable part. When there is no need for movable parts to do tilting motion, control the current in the two tracking tilting coils so that the resultant force of F1 and F2 is equal to the driving force required for tracking motion, while M1 and M2 are equal in magnitude and opposite in direction, thus The resultant force couple is 0, and there is no driving force couple for tilting motion; when the movable part is required to do tilting motion, control the current in the two tracking tilting coils so that the resultant force of F1 and F2 is equal to the driving force required for tracking motion, and M1 and M2 are different in size and opposite in direction, so the resultant force couple is not 0, thus generating the driving force couple of tilting motion. It can be seen that in this structure, both the focusing motion and the tracking motion are driven by the resultant force, while the tilting motion is driven by the resultant force of the two force couples, which is different from the method used by others to drive the tilting motion by using the resultant torque. Based on the above structure and principle, there are many combinations of magnetic field magnetization direction and strength, current direction and strength that meet the requirements of three-directional movement (tracking, focusing and tilting), which can be selected according to needs and are easy to implement . The stronger the magnetization of the magnet, the stronger the magnetic field it will generate, thereby improving the sensitivity of the movable parts, but it will increase the cost, which can be considered as a trade-off.

Fig. 3 is a supplementary explanatory diagram of the structure of the present invention. The suspension wire not only plays a supporting role, but also plays a role in transmitting electric current. The current is transmitted from the PCB board 2 on the fixed part to the suspension wire, and then passed to the coil on the movable part through the suspension wire. Therefore, one end of the four suspension wires is usually welded on the PCB board 2 by welding, the other end of the first upper suspension wire 14 and the first lower suspension wire 18 are welded on the first printed circuit board 17, and the second upper suspension wire 18 is welded on the first printed circuit board 17. The other end of the wire 7 and the second lower suspension wire 19 is welded on the second printed circuit board 16 . The first printed circuit board 17 and the second printed circuit board 16 are fixed on the objective lens holder 4, and in this way, the movable parts are supported by the suspension wires. The advantage of adopting such a method is that the requirements for the material of the objective lens holder are not high, and the cost can be reduced. Sometimes in order to improve performance and reduce processing steps, you can choose more expensive high-temperature-resistant objective lens bracket materials, so that the suspension wire can be directly welded on the objective lens bracket, and no longer need two printed circuit boards as intermediate connecting parts.

Figure 4 shows another arrangement of the core components of the present invention. In the embodiment described in Fig. 1a to Fig. 1c, the focus coil is placed inside the tracking tilt coil, while in the embodiment shown in Fig. 4, the first focus coil 11 is placed outside the first tracking tilt coil 12, The second focusing coil 15 is placed outside the first tracking and tilting coil 8 . Can have different selections because of the difference of production process, if directly winding the coil on the objective lens support 4 can adopt the former, can adopt the latter to attach the wound coil on the objective lens support 4. In addition, Fig. 4 also shows the centrosymmetric arrangement relationship between the first driving force generating system and the second driving force generating system. Compared with the structure shown in Fig. 1c, the positions of the magnets and coils inside the two driving force generating systems are the same. A face-symmetric position shift is performed, but the center-symmetric arrangement requirement is still met, which is the result of satisfying the balance requirement of the driving force.

Claims (6)

1. a three-dimensional objective lens driving device of a tilting drive mode, comprising a fixed part, a magnetic field generating system composed of an outer yoke (13) fixed on the fixed part and four magnets fixed on the outer yoke (13), and A movable part supported by a suspension wire fixed on the fixed part, the movable part includes an objective lens support (4), an objective lens (5) arranged on the objective lens support (4), and a magnet located between the magnets Four coils, characterized in that: the four magnets in the magnetic field generating system are respectively the first focusing tilting magnet (10), the second focusing tilting magnet (6), the first tracking magnet (3) and the second tracking magnet (3) Tracking magnet (9), wherein the first focusing tilting magnet (10) and the second focusing tilting magnet (6) are magnetized by boundaries, that is, the magnetic pole directions of the upper half and the lower half of the magnet are opposite, and the first tracking The magnet (3) and the second tracking magnet (9) respectively have a single magnetic pole direction; The four coils are respectively the first focusing coil (11), the second focusing coil (15), the first tracking tilting coil (12) and the second tracking tilting coil (8), and the first focusing coil ( 11) the normal of the plane where the ring is located and the normal of the plane where the ring of the first tracking tilt coil (12) is vertical, the normal of the plane where the ring of the second focusing coil (15) is and the second tracking tilt coil ( 8) The normal of the plane where the ring is located is vertical; The first tracking tilting coil (12), the first focusing coil (11), the first focusing tilting magnet (10) and the first tracking magnet (3) form a first driving force generation system, and the first focusing The coil (11) is placed next to the first focusing tilting magnet (10); the second tracking tilting coil (8), the second focusing coil (15), the second focusing tilting magnet (6) and the second tracking magnet ( 9) Forming a second driving force generating system, the second focusing coil (15) is placed next to the second focusing tilting magnet (6); the two driving force generating systems are arranged symmetrically about the center. 2 . The three-dimensional objective lens driving device in a tilting driving mode according to claim 1 , wherein the magnetization directions of the four magnets are all parallel to the axial direction of the suspension wire. 3 . 3. the three-dimensional objective lens driving device of tilting driving mode according to claim 1, is characterized in that: the winding central axis of described first focus coil (11) and the second focus coil (15) is parallel to the axis of suspension wire direction. 4. The three-dimensional objective lens driving device in tilt driving mode according to claim 1, characterized in that: the first focusing coil (11) is placed inside or outside the tracking tilt coil (12). 5. The three-dimensional objective lens driving device in tilt driving mode according to claim 1, characterized in that: the second focusing coil (15) is placed inside or outside the second tracking tilt coil (8). 6. The three-dimensional objective lens driving device in tilt driving mode according to claim 1, characterized in that: the first focusing coil (11) and the second focusing coil (15) are wound into a rectangle or a circle.

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