JP4561277B2 - Optical pickup actuator - Google Patents

Description

  The present invention relates to an optical pickup actuator, and more particularly to a shaft sliding actuator for an optical pickup.

  Optical pickup actuators employed in disk devices such as DVD players can be broadly classified into shaft sliding types and wire types. The former shaft-sliding type actuator is designed so that the displacement of the lens holder with the objective lens is controlled in the focus direction and tracking direction by fitting the shaft hole into the support shaft. In this actuator, the lens holder is cantilevered by a spring material (wire or the like), and the displacement of the lens holder is controlled in the focus direction and the tracking direction through deformation of the spring material.

  4 is a schematic perspective view for explaining the overall configuration of the optical pickup P on which the shaft sliding type actuator A is mounted, and FIG. 5 is a schematic sectional view of a main part of the shaft sliding type actuator shown in FIG.

As shown in FIG. 4 or FIG. 5, the actuator A is erected vertically on a metal (sheet metal) actuator base 1 formed into a box shape with an open upper surface and a lower plate portion 12 of the actuator base 1. The metal support shaft 2A, the lens holder 3 having the shaft hole 31 fitted into the metal support shaft 2A, the focus coil 4 and the tracking coil provided in the lens holder 3 5, a permanent magnet 6 held on the left and right rising walls 13 of the actuator base 1, and a resin cover 7 A that is mounted on the actuator base 1 and covers the lens holder 3 from above. 3 has an objective lens 32 . As can be seen from FIG. 5, the focus coil 4 is held by the lens holder 3 so as to surround the periphery of the shaft hole 31 of the lens holder 3, whereas the tracking coil 5 is provided on the left and right sides of the lens holder 3. The metal support shaft 2A and the left and right permanent magnets 6 face each other with the focus coil 4 and the tracking coil 5 interposed therebetween.

  In the actuator A, when a current flows through the focus coil 4 and the tracking coil 5, a magnetic circuit is formed by the metal support shaft 2A, the focus coil 4 or the tracking coil 5, the permanent magnet 6, and the actuator base 1. The displacement of the lens holder 3 in the focus direction F and the tracking direction T is controlled by the action of the magnetic circuit. The focus direction F is the axial direction of the metal support shaft 2A, in other words, the perspective direction with respect to a disk (not shown) as a recording medium, and the tracking direction T is the direction around the axis of the metal support shaft 2A. is there.

The actuator A having the above-described configuration is mounted on the base structure 8 as shown in FIG. 4, and the base structure 8 is controlled to move in the radial direction of the disk by a feed mechanism (not shown). The objective lens 32 is opposed to the scanning position of the disk. The base structure 8 is assembled with an optical element forming an optical system such as a half mirror and a collimator lens in addition to a laser diode and a light receiving element as a light source.

  By the way, in order to increase the displacement sensitivity in the focus direction and tracking direction of the lens holder, the sliding performance between the shaft hole of the lens holder and the support shaft with which the shaft hole is fitted is improved. Various researches have been made (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3). In addition, studies have been made on the low-friction bearing itself and the manufacturing method thereof (see Patent Document 4).

On the other hand, in the case of wire type actuators, a technology is known in which the upper cover and the side portion of the holder are covered with a magnetic material to prevent the intrusion of dust, thereby suppressing the leakage magnetic field. (See Patent Document 5). In addition, a technique for sharing the function of the pickup cover with an actuator yoke has been known (see Patent Document 6).
Japanese Patent Laid-Open No. 5-89499 JP-A-8-329509 JP-A-10-334490 Japanese Patent Laid-Open No. 7-121894 JP-A-6-301993 JP-A-9-91727

  In the shaft sliding type actuator A described with reference to FIGS. 4 and 5, the lens holder 3 is displaced in the focus direction F and the tracking direction T by fitting the shaft hole 31 to the metal support shaft 2A. In contrast, the metal support shaft 2A is a stainless steel shaft body with nickel-fluorine resin plating applied to prevent rusting.

  However, the metal support shaft 2A on which the surface layer is formed by nickel-fluorine resin plating, although the rusting is suppressed by the nickel-fluorine resin plating, the surface smoothness is further enhanced to make the lens holder It is impossible to improve the displacement sensitivity of 3. This is because the nickel-fluorine-based resin plating layer, which is the surface layer of the metal support shaft 2A, is an aggregate of fine particles, so that the surface smoothness of the metal support shaft 2A formed with such a surface layer is improved. This is because there is a restriction from the structural aspect of the surface layer itself.

  In this regard, Patent Document 2 describes that the friction resistance of the lens holder with respect to the support shaft is reduced by coating the support shaft with a PTFE-containing thermosetting resin. The inventor of the present application also knows that the surface of the resin molded body is superior in surface smoothness compared to the nickel-fluorine resin plating layer.

  However, if the metal support shaft 2A shown in FIG. 5 is replaced with the support shaft described in Patent Document 2 coated with a thermosetting resin containing PTFE, the surface smoothness of the support shaft is reduced. Even if it can be improved, the diameter of the stainless steel shaft must be reduced by the thickness of the coating layer, so that it can function as a yoke to form the magnetic circuit required for the support shaft. Therefore, the displacement sensitivity characteristic of the lens holder 3 whose displacement is controlled by the magnetic circuit as a whole may be deteriorated.

  On the other hand, Patent Documents 5 and 6 describing wire-type actuators describe providing a function as a yoke for forming a magnetic circuit on a cover. It is possible to reduce the leakage magnetic field of the magnetic circuit by replacing the cover having the function with the resin cover 7A shown in FIG. However, even if this is done, the metal support shaft 2A in FIG. 5 is plated with nickel-fluorine resin, and it is impossible to improve its surface smoothness. The displacement sensitivity characteristic of the lens holder 3 to be controlled may be deteriorated.

  The present invention has been made under the above circumstances, and by making at least the surface of the support shaft into which the shaft hole of the lens holder is fitted as a resin surface, the surface smoothness thereof is made of the metal described in FIG. The displacement is controlled by the magnetic circuit by improving the support shaft 2A more than that of the support shaft and by taking measures that can sufficiently compensate for the function of the yoke that decreases as the support shaft is configured as such. It is an object of the present invention to provide an actuator for an optical pickup capable of improving the displacement sensitivity characteristic of the lens holder as a whole.

  Further, the present invention replaces the metal support shaft described in FIG. 5 with a resin support shaft, so that even if the function of the yoke disappears from the support shaft, the entire lens holder whose displacement is controlled by a magnetic circuit is also provided. It is an object of the present invention to provide an actuator for an optical pickup capable of improving the displacement sensitivity characteristic.

The actuator of the optical pickup according to the present invention is such that a shaft hole of a lens holder provided with an objective lens is fitted to a metal support shaft, the metal support shaft, a focus coil or a tracking coil, a permanent magnet, The lens holder is controlled in displacement in the focus direction and tracking direction by a magnetic circuit formed by a metal actuator base holding a permanent magnet, and a resin cover that covers the lens holder is mounted on the actuator base. In the optical pickup actuator, the metal support shaft is replaced with a support shaft made of a resin or the surface of the core material covered with a resin layer, whereby the support shaft and the hole of the shaft hole of the lens holder are replaced. In addition to improving the slidability with the wall, the resin cover is replaced with a sheet metal cover. Thus, a magnetic circuit for controlling the displacement of the lens holder in the focus direction and the tracking direction holds the sheet metal cover, the focus coil or the tracking coil, the permanent magnet, and the permanent magnet. The actuator base is made of metal. In addition, the focus coil and the tracking coil are provided in the lens holder, and a protruding piece that is provided in the sheet metal cover and is inserted into a space formed in the lens holder includes the focus coil. And the structure of facing the said permanent magnet on both sides of the said tracking coil is employ | adopted.

  According to the present invention, the metal support shaft is replaced with a support shaft made of a resin support shaft or a core material whose surface is covered with a resin layer, thereby sliding the support shaft and the hole wall surface of the lens holder shaft hole. Since the mobility is improved, the lens holder is easily displaced in the focus direction and tracking direction with respect to the support shaft, but on the other hand, the function of the support shaft as a yoke is lost, or the support is lost. The function of the shaft as a yoke is reduced. Therefore, in order to sufficiently supplement the function of the lost or lowered spindle as a yoke, a resin cover is replaced with a sheet metal cover, and a magnetic circuit for controlling the displacement of the lens holder in the focus direction and the tracking direction is provided. , A sheet metal cover, a focus coil or the tracking coil, a permanent magnet, and a metal actuator base. Therefore, the actuator according to the present invention improves the overall displacement sensitivity characteristic of the lens holder whose displacement is controlled by the magnetic circuit.

In addition, in the present invention, the focus coil and the tracking coil are provided in the lens holder, and the protruding piece that is provided in the sheet metal cover and is inserted into a space formed in the lens holder includes: The permanent magnet is opposed to the focus coil and the tracking coil. By adopting this configuration, the leakage magnetic field of the magnetic circuit is reduced, which helps to improve the displacement sensitivity characteristic of the lens holder.

  The actuator of the optical pickup according to the present invention is such that a shaft hole of a lens holder provided with an objective lens is fitted to a metal support shaft, the metal support shaft, a focus coil or a tracking coil, a permanent magnet, The lens holder is controlled in displacement in the focus direction and tracking direction by a magnetic circuit formed by a metal actuator base holding a permanent magnet, and a resin cover that covers the lens holder is mounted on the actuator base. In an optical pickup actuator, the metal support shaft is replaced with a resin support shaft made of PPS resin as a molding material, thereby improving the slidability between the support shaft and the wall surface of the lens holder shaft hole. In addition to the above, by replacing the resin cover with a sheet metal cover, The magnetic circuit for controlling the displacement of the lens holder in the focus direction and the tracking direction is made of the sheet metal cover, the focus coil or the tracking coil, the permanent magnet, and a metal holding the permanent magnet. The focus base and the tracking coil are provided in the lens holder, and are provided in the sheet metal cover and formed in the lens holder. A projecting piece inserted into the lens is opposed to the permanent magnet with the focus coil and the tracking coil interposed therebetween, and the actuator base is formed from a lower plate portion disposed below the lens holder and the lower plate portion. Standing up and deployed on the left and right sides of the lens holder Adopting a configuration in which the permanent magnets are held on the rising walls, and the falling pieces provided on the sheet metal cover are in contact with and overlapped with the rising walls. To make it more concrete.

  As described above, according to the present invention, since the surface of the support shaft into which the shaft hole of the lens holder is fitted is formed as a resin surface, the surface smoothness of the metal support shaft described in FIG. A sheet metal in which the function as a yoke of the support shaft, which has been improved further than that and disappears or decreases as the surface of the support shaft is formed as a resin surface, is replaced with the resin cover described in FIG. Since the cover is sufficiently supplemented by the function as a yoke, the overall displacement sensitivity characteristic of the lens holder whose displacement is controlled by the magnetic circuit is improved. Therefore, it is extremely useful as a technology that can promote high performance required for a disk device such as a recent DVD player.

  FIG. 1 is a schematic perspective view for explaining the overall configuration of an optical pickup P on which a shaft sliding actuator A according to the present invention is mounted, and FIG. 2 is a schematic cross section of a main part of the shaft sliding actuator shown in FIG. FIG.

  1 and 2 differs from the actuator A described with reference to FIG. 4 or 5 mainly in the configuration of the support shaft 2 and the cover 7, and the actuator base 1 and the lens holder. 3, the change of the structure accompanying the change of the structure of the spindle 2 and the cover 7 is added. Since the other configurations are the same, the same or corresponding elements are denoted by the same reference numerals to avoid redundant description.

  In this embodiment, the support shaft 2 is made of a resin, that is, a resin molded body, and is used in place of the metal support shaft 2A shown in FIG. 4 or FIG. More specifically, the support shaft 2 is molded using polyphenylene sulfide resin (PPS resin), and its surface smoothness is higher than that of the metal support shaft 2A shown in FIG. 4 or FIG. Are better. The support shaft 2 is fixed to the actuator base 1 by joining a flange 21 integrally formed at the lower end thereof to the lower plate portion 12 of the actuator base 1 with an adhesive.

  On the other hand, the cover 7 is made of a sheet metal as a magnetic body and is formed in a substantially gate shape (made of sheet metal), and includes a pair of left and right falling pieces 71 and a pair of projecting pieces 72 at the center.

  The shaft hole 31 of the lens holder 3 is fitted to the resin support shaft 2. In addition, a pair of protruding pieces 72 of the sheet metal cover 7 are inserted into the spaces 33 provided on both sides of the lens holder 3 with the shaft hole 31 therebetween, and the pair of falling pieces of the cover 7 is also provided. 71 are superimposed on the left and right rising walls 13 of the actuator base 3 in contact with each other.

  According to this actuator A, since the support shaft 2 is made of resin, the slidability between the support shaft 2 and the hole wall surface of the shaft hole 31 of the lens holder 3 is improved as compared with that of FIG. On the other hand, since the support shaft 2 is made of a resin, the support shaft 2 cannot function as a yoke forming a magnetic circuit. On the other hand, the cover 7 is made of sheet metal, and the cover is provided with a function as a yoke, and a magnetic circuit for controlling the displacement of the lens holder 3 in the focus direction F and the tracking direction T is provided with the sheet metal cover 7 and the focus coil. 4 or the tracking coil 5, the permanent magnet 6, and the actuator base 1, the function as a yoke disappeared when the support shaft 2 is made of resin is the function as the yoke of the sheet metal cover 7. Is sufficiently compensated, and the leakage magnetic field is less than that of FIG. 4 or FIG. In the actuator of this embodiment, it has been confirmed that the overall displacement sensitivity characteristic of the lens holder 3 whose displacement is controlled by a magnetic circuit is improved as compared with that of FIG.

  In particular, as in this embodiment, by inserting the protruding piece 72 of the metal cover 7 into the space 33 of the lens holder 3, the protruding piece 72 faces the permanent magnet 6 with the focus coil 4 and the tracking coil 5 interposed therebetween. It has been found that the displacement sensitivity characteristic of the lens holder 3 can be improved by reducing the leakage magnetic field of the magnetic circuit.

  FIG. 3 shows a modification of the support shaft 2. The spindle 2 is configured by covering the top surface and the outer peripheral surface forming the surface of the high-strength core material 22 with a resin layer 23 having excellent surface smoothness. The support shaft 2 can be replaced with the resin support shaft 2 described with reference to FIG. 2. By replacing the support shaft 2 as described above, the lens holder 3 can be displaced in the focus direction F and the tracking direction T so as to function as a yoke. Demonstrate the function. In this support shaft 2, the core material 22 can be formed of an inexpensive stainless steel shaft body that is not plated, and the resin layer 23 is insert-molded on a resin sleeve formed of a resin molded body or the core material 22. In the case of using a resin sleeve, it can be integrated with the core material 22 by fitting the molded resin sleeve to the core material 22.

It is a schematic perspective view for demonstrating the whole structure of the optical pick-up which mounts the shaft sliding type actuator which concerns on this invention. It is a schematic sectional drawing of the principal part of the shaft sliding type actuator shown in FIG. It is sectional drawing which showed the modification of the spindle. It is a schematic perspective view for demonstrating the whole structure of the optical pick-up which mounts the conventional shaft sliding type actuator. It is a schematic sectional drawing of the principal part of the shaft sliding type actuator shown in FIG.

DESCRIPTION OF SYMBOLS 1 Actuator base 2 Resin support shaft 2A Metal support shaft 3 Lens holder 4 Focus coil 5 Tracking coil 6 Permanent magnet 7 Sheet metal cover 7A Resin cover 12 Lower plate portion 13 Standing wall 31 Shaft hole 32 Objective lens 33 Space 71 Falling piece 72 Protruding piece F Focus direction T Tracking direction A Actuator

Claims (2)

The shaft hole of the lens holder provided with the objective lens is fitted to a metal support shaft, and the metal support shaft, the focus coil or tracking coil, the permanent magnet, and the metal holding the permanent magnet are made. In the actuator of the optical pickup, the displacement of the lens holder is controlled in the focus direction and the tracking direction by a magnetic circuit formed by the actuator base, and a resin cover that covers the lens holder is mounted on the actuator base.
In addition to improving the slidability between the support shaft and the hole wall surface of the shaft hole of the lens holder by replacing the metal support shaft with a resin support shaft made of PPS resin as a molding material, the resin A magnetic circuit for controlling the displacement of the lens holder in the focus direction and the tracking direction by replacing the cover made of sheet metal, the sheet metal cover, the focus coil or the tracking coil, the permanent magnet, It is configured to be formed by the actuator base made of metal holding the permanent magnet,
The focus coil and the tracking coil are provided on the lens holder, and a protruding piece that is provided in the sheet metal cover and is inserted into a space formed in the lens holder includes the focus coil and the tracking coil. Facing the permanent magnet across the coil,
The actuator base has a lower plate portion disposed on the lower side of the lens holder, and rising walls that are raised from the lower plate portion and are disposed on the left and right sides of the lens holder. An actuator for an optical pickup, wherein the permanent magnet is held, and falling pieces provided on the sheet metal cover are stacked in contact with the rising wall. The shaft hole of the lens holder provided with the objective lens is fitted to a metal support shaft, and the metal support shaft, the focus coil or tracking coil, the permanent magnet, and the metal holding the permanent magnet are made. In the actuator of the optical pickup, the displacement of the lens holder is controlled in the focus direction and the tracking direction by a magnetic circuit formed by the actuator base, and a resin cover that covers the lens holder is mounted on the actuator base.
Replacing the metal support shaft with a support shaft made of resin or a core material whose surface is covered with a resin layer improves the slidability between the support shaft and the wall surface of the lens holder shaft hole. In addition, by replacing the resin cover with a sheet metal cover, a magnetic circuit for controlling the displacement of the lens holder in the focus direction and the tracking direction includes the sheet metal cover and the focus coil or the tracking coil. a coil, and the permanent magnet, Ri configured tear as formed by the metal of the actuator base holding the permanent magnets,
The focus coil and the tracking coil are provided on the lens holder, and a protruding piece that is provided in the sheet metal cover and is inserted into a space formed in the lens holder includes the focus coil and the tracking coil. An actuator for an optical pickup, wherein the actuator faces the permanent magnet with a coil interposed therebetween .

Images