JPS62205539A - Optical system driving device - Google Patents

Abstract

PURPOSE:To suppress vibration due to driving of an optical system holder by providing two bearings in the optical system holder in the direction of optical axis and coupling a supporting shaft rotatably and slidably to the bearing. CONSTITUTION:A permanent magnet 17 is fixed to a base stand 19 and a columnar member 2b wound by a coil on outer periphery, an objective 1 and an objective holder 2 consisting of an objective holding member 2a having two cylindrical bearings 3, 4 arranged in the direction of optical axis in the direction of optical axis of the lens 1 (Y direction) and perpenducular direction (X direction) to make inner peripherals part of the magnet 17 and the coil 18 face each other. Ferromagnetic supporting shafts 5, 6 are coupled rotatably and slidably to bearings 3, 4, and guides 7, 8 and 9, 10 are provided at the end of shafts 5, 6. An end of each of supporting members 11-14 is fixed appropriately to guides 7-10, and the other end of the members is fixed to erected part of the base stand 19. A coil 16 is fixed to the side face of the holder 2 opposite to the erected part of the base stand 19, and a permanent magnet 15 is fixed to a back plate 20 to face the coil 16. Thus, inclination of optical axis due to movement of the optical system holder in the direction of optical axis is prevented, and control of high accuracy can be performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical system and a driving device, and particularly relates to an optical system driving device that allows an optical system to move between optical axes and in a direction perpendicular to the optical axis. . INDUSTRIAL APPLICATION This invention is suitably used for optical information recording/reproducing apparatuses, such as an original disc.

[Prior art]

In recent years, with the development of the information society, research and development of optical information recording and reproducing devices that can store a large amount of information and record or reproduce desired information in a short time have been actively conducted.

A source disk device will be described below as an example of an optical information recording/reproducing device.

Generally, in a source disk device, information bits having a width of about 1 to 2 μm and a length of about 1 to 3 μm are formed on an information recording medium. To reproduce information from this information pit, first, the original beam is focused onto a minute spot using an objective lens.
Irradiates the information pit.

At this time, the reflected light or transmitted light from the information recording medium optically changes depending on the presence or absence of information bits.

By detecting this change with a photodetector, a reproduced signal corresponding to the information bit can be obtained.

In such a source disk device, it is extremely important that the minute spot always accurately scan the information kit array on the information recording medium.

For this purpose, an autofocus function that corrects a focus shift caused by the tilting of the information recording medium, and an autotracking function that corrects the irradiation position shift caused by the eccentricity of the information recording medium are required.

As a method of realizing this autofocus function and autotracking function, there is a driving method that supports the objective lens with a spring-like structure and uses the effect of electromagnetic force from an electromagnetic coil and a permanent magnet. It was taken by the objective lens drive device of the device.

FIG. 5 is a perspective view of a conventional objective lens driving device.

As shown in FIG. 5, the base 35 has a U-shaped yoke 3.
A permanent magnet 31 and a yoke 32 are fixed inside the yoke 36.

One end of the support springs 25 and 26 is fixed to a yoke 36, and the other end is fixed to a surface of a relay plate 33 having a substantially square cross section perpendicular to the base 35. One end of the support springs 23 and 24 is connected to the relay plate 33.
On the upper and lower surfaces relative to the zero base 35, the other end is fixed to an objective lens holder 22 having an objective lens 21. The objective lens 21 illuminates the laser beam onto the surface of the information recording medium. A coil 30 is fixed between the support springs 23,24. This coil 30 is provided so as not to be in contact with the yoke 32 and to surround the yoke 32. The support springs 23 and 24 of the objective lens holder 22 are fixed, and the coil 28 is fixed on the surface opposite to the next surface. . A permanent magnet 27 and a U-shaped yoke 29 are fixed to the base 35, the coil 28 faces the permanent magnet 27, and the yoke 29 is fixed to the base 35.
It is provided so as to wrap around one of the upright portions of 9. Base 3
A through hole 34 is formed in the portion facing the 50 objective lens 21.

Tracking control of the conventional objective lens drive device with the above configuration is performed by configuring a magnetic circuit with a permanent magnet 31, a yoke 32, and a yoke 36. This is done by generating an electromagnetic force with the flowing current and moving the objective lens holder 22 in a direction parallel to the base 35.

For focus control, a magnetic circuit is configured by a permanent magnet 27 and a yoke 29, and an electromagnetic force is generated by the magnetic field formed between the permanent magnet 27 and the yoke 29 and the current flowing through the coil 28 to hold the objective lens. This is done by moving the body 22 in a direction perpendicular to the base 35.

[Problem that the invention seeks to solve]

However, in the conventional objective lens and drive described above, when performing focus control and tracking control in a high frequency range, sub-resonance occurs in the support spring because the objective lens holder is held by a plate-shaped support spring. However, there was a problem that accurate focus control and tracking sensor could not be performed.The present invention was made for the purpose of solving the problems of the above conventional example,
The present invention aims to provide an optical system driving device that can drive an optical system stably and with high precision.

[Means for solving the problem']

The above problem is caused by an optical system holder that holds an optical system and has two bearings arranged side by side in the direction of the optical axis of the optical system, a coil that is fixed to this optical system holder, and a coil that is rotated around the bearing. A support shaft of the g1 magnetic material fitted so as to be movable and slidable, a support member attached to this support shaft and supporting the optical system holder movably in the optical axis direction, and a support member extending across the coil. This problem is solved by the optical system and drive device of the present invention, which comprises a magnetic circuit forming means for forming a magnetic field.

[For production]

1. The optical system of the present invention is constructed by holding and holding the optical system (two bearings are arranged side by side in one direction of the light beam, and a support shaft is rotatably and slidably fitted into the bearings. As a result, in order to ensure that the direction perpendicular to the optical axis direction of the optical system holder is not affected by the support member having a spring discharge, vibrations due to the small size of the optical system holder should be reduced. By attaching a support member to the support shaft, it is possible to suppress the movement of the optical axis in the optical axis direction due to the movement of the optical system holder in the optical axis direction. By making the support shaft a strong magnetic field, the strength of the magnetic field crossing the coil can be increased, and the response and pressure oil can be improved.

〔Example〕

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

The optical system and drive device of the present invention will be explained using an objective lens drive device as an example.

FIG. 1 is a perspective view showing an embodiment of the objective lens driving device of the present invention.

As shown in FIG. 1, the objective lens holder 2 is provided with a cylindrical member 2b around which a coil 18 is wound, and an upper part of the cylindrical member 2b, and collects radar light onto an information recording medium. It has an objective lens 1 that emits light, and a direction perpendicular to the optical axis direction (the Y direction shown in FIG. 1, hereinafter referred to as the Y direction) (the X direction shown in FIG. 1, hereinafter referred to as the X direction). )
Two 7t cylindrical bearings 3#4 are arranged in parallel in the optical axis direction.
', and an objective lens holding member 2a. A cylindrical permanent magnet 17 is fixed to an L-shaped base 19, and the objective lens holder 2 is arranged so that the inner circumference of the permanent magnet 17 faces the coil 18. .

The bearings 3 and 4 are machined so that their inner surfaces have lubricating properties, and the ferromagnetic support 1 is rotatably and slidably supported. III (hereinafter referred to as shafts) 5 and 6 are inserted. Figure 2 is a perspective view of the shaft 5. The shaft 5 is coated with a Teflon resin over the 5 m portion M that contacts the bearing 3. This reduces shaft friction between the shaft 5 and the bearing 3. There is. Note that the shaft 6 has the same structure as the shaft 5. At the ends of the shafts 5 and 6, there are guides 7.8 and 9.
, 1o are provided to restrict movement of the objective lens holder 2 in the X direction. On a part of the outer circumference of each guide 7*8m9-10, there is a support member 11, 12°13.
One end of 14 is fixed. The other end of the support member 1l-=14 is fixed to an upright portion of the base 19. Objective lens holder 2
A substantially rectangular coil 16 is fixed to the side surface of the base structure 9 facing the upright portion.

A permanent magnet 15 is fixed to a back plate 20 so as to face this coil 16, and this back plate 20 is fixed to a base 19.

Next, the operation of the objective lens drive device having the above configuration will be explained.

First, tracking control involves sliding the objective lens holder 2 in the X direction on the support 5°6 via the bearings 3 and 4 using the current flowing in the Y direction of the coil 16 and the electromagnetic force of the permanent magnet 15. carried out by

At this time, since there is little friction between the bearings 3, 4 and the shafts 5, 6, the supporting means 11-14 are hardly deformed.

That is, since the tracking drive has almost no effect on the supporting members 11 to 14, occurrence of unnecessary sub-resonance etc. is suppressed in the high frequency range, and highly accurate tracking serve can be applied.

Furthermore, in the present invention, by using ferromagnetic materials as l@5 and 6, a magnet opposite to the permanent magnet 15 for tracking drive is provided, and the strength of the magnetic field crossing the coil 16 is increased in total.

FIG. 3 is an explanatory diagram showing the effect when the shafts 5 and 6 are made of ferromagnetic material, where (,) shows the case where they are made of non-magnetic material, and (b) shows the case where they are made of ferromagnetic material.

If @5.6 is a non-magnetic material, the magnetic force of 1 JHa emitted from the permanent magnet 15 will diverge as shown in Figure 3(a), and leakage magnetic flux will occur, but if it is ferromagnetic, as shown in Figure 3(a). As shown in Fig. 3), the axes 5 and 6 are opposite magnetic poles of the permanent magnet 15, and the magnetic glands Hb converge in the direction of the axes 5 and 6, suppressing the generation of leakage magnetic flux and perpendicular to the Y direction of the coil 16. Since the strength of the magnetic field in the direction increases, the response performance of tracking control can be improved.

Next, focus control is performed by moving the objective lens holder 2 in the Y direction by the magnetic force of the current flowing through the coil 18 and the magnetic field generated by the permanent magnet 17. At this time, the objective lens holder 2 moves on the shafts 5, 6 through the bearings 3, 4 while rotating about the axes of the bearings 3, 4 and with deformation of the supporting means 11-14. At that time, the objective lens holder 2 has four supporting members 11 to
14, the support member and the objective lens holder constitute a so-called parallel link, and the objective lens 1
0 No optical axis tilt occurs.

〔Effect of the invention〕

As explained in detail above, according to the optical system drive device according to the present invention, two bearings are arranged in parallel in the optical axis direction on the optical system holder, and a support shaft is attached to the bearings so as to be rotatable and one to be movable. By fitting the optical system holder into the optical system holder, the support member, which has spring properties in the direction perpendicular to the optical axis direction, is not affected, so vibrations accompanying the 8 movements of the optical system holder are suppressed, while the optical axis By attaching a support member to the support shaft, it is possible to suppress inclination of the optical axis due to movement of the optical system holder in the optical axis direction, so that highly accurate focus control and tracking control can be performed. The response performance can be improved by using a ferromagnetic material as the supporting material to increase the strength of the magnetic field that crosses the coil.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the objective lens actual operating device of the present invention. FIG. 2 is a perspective view of the shaft used in the above embodiment. FIG. 3 is an explanatory diagram showing the effect when the shaft is made of ferromagnetic material. FIG. 4 is a perspective view of a conventional objective lens driving device. DESCRIPTION OF SYMBOLS 1... Objective lens, 2... Objective lens holder, 3° 4... Bearing, 52, 6... Shaft, 7e8e9t10.
...Guide, 11, 12, 13.14...Support member,
15°17...Permanent magnet, 16.18...Coil,
19... Base. Agent Patent Attorney Ms. Yamashita Figure 3 (b) Figure 4

Claims (1)

[Claims] an optical system holder that holds an optical system and has two bearings arranged in parallel in the optical axis direction of the optical system; a coil fixed to the optical system holder; and a coil that is rotatable and slidable on the bearing. A support shaft made of ferromagnetic material is fitted, and a support shaft is attached to this support shaft.
An optical system driving device comprising: a support member that supports the optical system holder movably in the optical axis direction; and a magnetic circuit forming means that forms a magnetic field across the coil.