JPH04344331A - Light pickup device - Google Patents

Abstract

PURPOSE:To reduce the cost and to improve the performance by supporting a holder to slide freely taking into account dynamic balance and composing a tracking coil and a tracking magnet. CONSTITUTION:A holder 1 is driven in the tracking direction by a tracking coil 6 and a tracking magnet 7. Further, it is driven in the focusing direction by a focusing coil 8 and a focusing magnet. Thus, the holder 1 is driven in the focusing and tracking directions against a supporting axis 5 to move an objective lens 2 to the required position. The laser beam passing through the lens 2 is irradiated correctly to the optical disk surface to record and reproduce digital information. Therefore, the number of parts is reduced and the inexpensive and good device can be obtained.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an optical pickup device, more specifically, a tracking coil and a tracking magnet for sliding a lens holder that holds an objective lens in a direction around an optical axis (hereinafter referred to as the tracking direction). It is related to.

0002

[Prior Art] Compact discs (hereinafter referred to as CDs) are known as optical discs on which digital information is recorded.Audio information, etc. is converted into digital signals on tracks formed on the CD, and minute discs are recorded. It is recorded as a pit. When reproducing the digital information recorded on this CD, a narrowly focused laser beam is irradiated onto the tracks of the CD that rotates at high speed, and the laser beam modulated and reflected by the pits is extracted as an electrical signal and converted into an analog signal. This allows the recorded audio information to be retrieved.

Furthermore, among optical disks, there are write-once disk memories in which information can be recorded only once, and magneto-optical disk memories in which information can be recorded and erased many times. Information is recorded and reproduced by shining light onto the disk surface.

Conventionally, as a lens holder for an optical pickup device that records or reproduces digital information by irradiating an optical disc with a laser beam, for example, the lens holder shown in FIG.
A lens holder having a structure as shown in FIG. 4 is used. Figure 3 is a plan view showing the structure of a conventional lens holder, and Figure 4
4 is a cross-sectional view of a main part of the lens holder shown in FIG. 3. FIG.

As shown in FIG. 3, an objective lens 2 is integrally assembled into a holder 1 with an adhesive 3, and a bearing hole is formed in parallel to the optical axis direction of the laser beam (hereinafter referred to as the focusing direction). 4 is formed through the hole. A support shaft 5 is inserted through the bearing hole 4, and the holder 1 is supported by the support shaft 5 so as to be slidable in the tracking direction and the focusing direction.A pair of two tracking coils are provided at both ends of the holder 1. 6 is provided.

As shown in FIG. 4, a focusing coil 8 is provided at the bottom of the holder 1 to drive the holder 1 in the focusing direction, and the holder 1 and the housing 12 are connected via a damper 9. There is. This damper 9
is made of a viscoelastic body such as silicone rubber that provides a predetermined brake on the movement of the holder 1, and one end of the holder 1 is connected to the holder side support part 10, and the other end is connected to the casing 12.
is connected to the housing side support part 11. Two pairs of tracking magnets 7 are provided in the housing 12 at positions facing each of the tracking coils 6.

Next, the operation will be explained. Holder 1 is
The tracking coil 6 and the tracking magnet 7 perform driving in the tracking direction, and the focusing coil 8 and a focusing magnet (not shown) perform driving in the focusing direction. Therefore, the holder 1 is driven in a controlled manner in the focusing and tracking directions with respect to the support shaft 5 to move the objective lens 2 to a desired position and direct the laser light passing through the objective lens 2 onto the optical disc surface. irradiate to record and reproduce digital information.

[0008]

The problem to be solved lies in the fact that, as described above, the conventional optical pickup device uses two tracking coils and two tracking magnets for driving in the tracking direction. Therefore, there were problems such as a large number of parts, a complicated manufacturing process, a long assembly time, high costs, and poor product accuracy.

The present invention has been made to solve this problem, and aims to simplify the manufacturing process by reducing the number of parts, thereby obtaining an inexpensive and high-quality optical pickup device.

0010

[Means for Solving the Problems] The optical pickup device according to the present invention reduces the weight of the holder, supports it slidably in consideration of dynamic balance, and includes a tracking coil and a tracking magnet each having an enhanced driving force. The most important feature is that it is individually provided.

[0011]

[Operation] In the present invention, the number of parts can be reduced by reducing the weight of the holder, supporting it slidably in consideration of dynamic balance, and using one tracking coil and one tracking magnet each with enhanced driving force. This also makes it possible to reduce the manufacturing process.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing an embodiment of the present invention, and FIG. 2 is a sectional view of a main part thereof. In each figure, 1 is a holder, 2 is an objective lens integrated into the holder 1 with an adhesive 3, and 4 is a bearing hole formed through the holder 1, into which a support shaft 5 is inserted. There is. Furthermore, one tracking coil 6 is provided at one end of the holder 1 on the side opposite to the damper 9 with respect to the central bearing hole 4 (on the objective lens 2 side), and as shown in FIG. One tracking magnet 7 is provided on the casing 12 facing the coil 6.

Further, as shown in FIG. 2, a focusing coil 8 is provided at the bottom of the holder 1 to drive the holder 1 in the focusing direction, and the holder 1 and the housing 12 are connected via a damper 9. There is. This damper 9
is made of a viscoelastic body such as silicone rubber that provides a predetermined brake on the movement of the holder 1, and one end of the holder 1 is connected to the holder side support part 10, and the other end is connected to the casing 12.
is connected to the housing side support part 11.

In addition, in the state shown in FIGS. 1 and 2 with the necessary parts assembled, the driving force required to rotate the holder 1 by 4 degrees, which is the required rotation angle, is 0.5 g at the tracking coil 6. The total weight of the holder 1 when parts 1 to 8 are assembled is 1.5g.
In the following, the center of gravity in the horizontal direction is located at the center of the bearing hole 4, and the center of gravity in the vertical direction is located on a line (not shown) passing through the center of the tracking coil 6.

Next, the operation will be explained. The holder 1 in this embodiment is driven in the tracking direction by one tracking coil 6 and one tracking magnet 7, respectively. That is, in this embodiment, the tracking coil 6 and tracking magnet 7 on the damper 9 side, which were provided in the conventional device, are omitted. Even in this case, as described above, by reducing the weight of the holder 1, increasing its driving force, and supporting it with dynamic balance in mind, it is possible to ensure the same driving performance as the conventional one.

Furthermore, driving in the focusing direction is performed by the focusing coil 8 and a focusing magnet (not shown). Therefore, the holder 1 is freely driven in the focusing direction and the tracking direction with respect to the support shaft 5 to move the objective lens 2 to a desired position.
A laser beam transmitted through an objective lens 2 is accurately irradiated onto the surface of an optical disk to record and reproduce digital information.

[0017]

As explained above, the optical pickup device of the present invention reduces the weight of the holder and supports it slidably in consideration of driving force and dynamic balance. There are advantages such as being able to obtain a device of high quality at low cost.

[Brief explanation of drawings]

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

FIG. 2 is a sectional view of a main part showing an embodiment of the present invention.

FIG. 3 is a plan view showing the structure of a conventional lens holder.

FIG. 4 is a sectional view of a main part showing the structure of a conventional lens holder.

[Explanation of symbols]

1 Holder 2 Objective lens 4 Bearing hole 5 Support shaft 6 Tracking coil 7 Tracking magnet 9 Damper

Claims (1)

[Claims] 1. An objective lens that focuses a laser beam on an optical disk surface, a holder that holds this objective lens, and a support portion that supports this holder so as to be slidable in a tracking direction and a focusing direction on a housing. In an optical pickup device having a tracking coil provided on the holder and a tracking magnet provided on the casing opposite to the tracking coil, the holder can be freely slid on the support portion in consideration of dynamic balance. An optical pickup device, characterized in that the tracking coil and the tracking magnet are each comprised of one piece.