JPH02308428A - Optical memory device - Google Patents

Abstract

PURPOSE:To eliminate the need of a permanent magnet for an actuator and to make a movable part light in weight and small in size by leading a part of a magnetic flux of a linear motor for moving an objective lens of an optical head in the disk radial direction into a magnetic circuit of a focus motion. CONSTITUTION:An actuator 2 of an objective lens 1 for reducing a laser spot onto a disk is fed in the disk radial direction by a linear motor 3 and brought to access motion. Also, in order to cause a focus motion of the actuator 2, a yoke 13 is brought close to a permanent magnet 4 of the linear motor 3 and a focus coil 14 is inserted into a magnetic space existing between them. A line of magnetic force runs vertically to the coil 14 having a current flowing in the longitudinal direction of the magnet 4 and generates a focus motion. The yoke 13 moves together in the seek direction by following the movement of the actuator 2 but there is no variation as a magnetic circuit and no functional problem is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical memory device. More specifically, the present invention relates to the configuration of a linear motor and a lens actuator of an optical memory device.

[Prior Art] FIG. 4 is a plan view of a conventional optical memory device showing the main parts related to the present invention, and FIG. 5 is a side view thereof. This conventional example shows only the movable parts of a separate head in which the main optical system is fixed. That is, only the lens actuator 2 that drives the objective lens 1 that focuses the laser beam onto the disk in the focusing direction and the tracking direction is accessed in the radial direction of the disk by the linear motor 3.

In this way, only the tip of the lightweight head is driven as needed, so access time can be shortened and high-speed driving can be achieved. The linear motor shown in FIG. 4 consists of a permanent magnet 4, a yoke 5, and a moving coil 6. This coil and the lens actuator unit 2 mentioned above are fixed, and are moved on a slide shaft 7 by a bearing 8 without resistance. It has become. FIG. 6 shows one example of the structure of a lens actuator. The lens 1 is integrated with a focusing and tracking coil 9 (for example, as shown in FIG. 3), and a permanent magnet 10 and a yoke 1.
It is inserted into the gap of a magnetic circuit consisting of 1. Therefore, due to the force generated by Fleming's left hand law ill, the lens 1 supported by the four wires 17 can simultaneously move in the focus direction (Fe2) and the tracking direction (TRK) as shown in FIG. It becomes possible.

Note that the coil and magnetic circuit around the lens are omitted in this figure. Further, reference numeral 12 in FIG. 6 is a mirror that bounces up the laser beam traveling horizontally, and the lens actuator is provided with a hole 16 through which the laser passes.

[Problems to be Solved by the Invention] In such an optical memory device, the lighter the movable part of the optical head, the lighter the access time. In some cases, the weight of the magnets and coils included in the actuator is significant, and the size of the actuator itself is also large. The purpose of this is to make the movable parts of the separate head light and small, thereby providing a head capable of high-speed access.

[Means for Solving Problem C] The optical memory device of the present invention moves the lens actuator of the optical head in the radial direction of the disk, and in the linear motor, the yoke part of the magnetic circuit that causes the focusing movement of the objective lens is moved as described above. It is characterized in that it is movable in the radial direction of the disk near the linear motor, and has a structure in which a part of the magnetic flux of the linear motor is introduced into the magnetic circuit for focus movement.

[Function] By sharing the magnetic circuit of the actuator that causes the focus movement of the objective lens with the magnetic circuit of the linear motor, a part of the magnetic flux of the linear motor is introduced into the magnetic circuit for the focus movement. The permanent magnet required for the actuator is no longer required, making the moving part lighter and smaller.

[Example] FIG. 1 is a plan view illustrating the present invention in detail. Also,
FIG. 2 is a side view thereof. The actuator 2 of the objective lens 1 narrows down the laser spot on the disk.
It is sent in the radial direction of the disk by a linear motor 3 to perform an access movement. The linear motor consists of a permanent magnet 4 magnetized in the horizontal direction and an iron-based yoke 5.
The movable coil 6 is fixed to the lens actuator 2. In this example, two moving coils are used.
This is because consideration was given so that the point of application of the force coincides with the center of gravity of the actuator 2. Lens actuator 2
slides on the slide shaft 7 with little resistance by six bearings 8.

Now, in the present invention, in the above lens actuator, the yoke 13 (corresponding to 11 in FIG. 6) is brought close to the permanent magnet 4 of the linear motor 3 in order to cause the focusing movement, and the gap between the permanent magnet 4 and the yoke 13 is The magnetic space created in this case is used as the insertion place for the focusing coil 14. In this way, the lines of magnetic force run perpendicular to the longitudinal direction of the permanent magnet, and the current flows through them in the longitudinal direction of the magnet, so the movement of the coil is perpendicular to the plane of the paper in Figure 1, that is, a focus movement. . This principle is shown in FIG.

The yoke 13 on the actuator side moves in the theta direction together with the movement of the lens actuator, but there is no functional problem since there is no change in the magnetic circuit. Further, in the present invention, in order to make effective use of the magnets used in the linear motor, the magnetic gap of the motor is moved to the outside, contrary to the conventional example. but,
In the present invention, the size of the lens actuator itself can be reduced, so the length of the coil does not become excessively large.

Furthermore, according to the present invention, it is also possible to cause the lens actuator to perform a tracking movement. That is, as shown in FIG. 3, when rectangular coils 15 are attached to the four corners of the focus coil 14 and a current is passed in a direction perpendicular to the magnetic field compared to the focus case, a force in the direction of the arrow TRK is generated. Therefore, the present invention can be extended to systems other than tracking using galvano mirrors.

[Effects of the Invention] As described above, the present invention improves the efficiency and miniaturizes the device configuration by sharing the magnetic circuit of the linear motor, which is the feeding mechanism of the optical head in optical memory snowmaking, and the lens actuator. It was planned. As a result, a magnet for the objective lens actuator is no longer required, making it possible to reduce the weight of the movable part during access, contributing to a reduction in access time. Furthermore, the present invention can be applied to a lens actuator that only causes a focusing movement, and a two-dimensional actuator that also causes a tracking movement, allowing for a wide range of applications.

[Brief explanation of the drawing]

1 and 2 are configuration diagrams of the present invention, the former being a plan view and the latter being a side sectional view. FIG. 3 is a diagram showing the principle of generating focus and tracking movements. FIGS. 4 and 5 are configuration diagrams of conventional examples. FIGS. 6 and 7 are configuration diagrams of the lens actuator. 1... Objective lens 2... Lens actuator 3... Linear motor 4... Permanent magnet 5... Yoke 6... Moving coil 7... Slide shaft 8... Bearing 13... Actuator Yoke 14... Focus coil and above Applicant Seiko Epson Co., Ltd. agent Patent attorney Kizobe Suzuki Ike 1 name now, fictitious person 1 - λ Stone, Su; -7 14, Four Sword Suyui IV 111 Bennikui 2.1Σ T ¥-hi) 3) Sword 4th Day Pengode (] ¥7 1D

Claims (1)

[Claims] In a linear motor that moves a lens actuator of an optical head in a radial direction of the disk, a yoke portion of a magnetic circuit that causes a focus movement of an objective lens is movable in the radial direction of the disk near the linear motor, and An optical memory device characterized by having a structure in which a part of the magnetic flux of a linear motor is introduced into a magnetic circuit for focus movement.