JPH041936A - Optical signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce the weight of a movable part and to make the part thin structive in the thickness direction by applying a separate optical system, disposing a galvanomirror on a fixed part and conforming the oscillating direction with the same plane as the surface of a medium. CONSTITUTION:A shaft 16b for oscillating the galvanomirror 16 is arranged in the vertical direction to the medium surface of a recording medium 6. Consequently, the shape and size of the galvanomirror 16 itself can be formed thin in the vertical direction. On the other hand, a reflected light beam emitted from the galvanomirror 16 is oscillated in a parallel plane 19 to the aforementioned medium surface, whereas this oscillating direction is converted into the moving direction (direction of an arrow A) of an objective lens 5 by an optical element having two reflecting surfaces. By this method, the weight of the movable part is reduced, and also thicknesswise thin formation is feasible.

Description

[Detailed Description of the Invention] [Summary] This invention relates to an optical signal recording/reproducing device, and in particular to a separate type optical head for realizing miniaturization of the optical head. The purpose of the present invention is to provide a structure that uses a semiconductor laser as a light source and tracks the surface runout and eccentricity of a rotating recording medium of a device that records/reproduces signals on a recording medium and tracks a predetermined track through an objective lens. As an actuator for irradiating a minute spot, a focus-controllable part is mounted on a carriage, and an information detection mechanism including a galvanometer mirror and a light source that follows the track direction is disposed on a fixed part, and the carriage and the In an optical signal recording and reproducing device of a separation optical type in which a fixed part is optically coupled to a fixed part, a required distance with respect to a first perpendicular plane to the medium surface of the recording medium including the moving direction of the objective lens. A reflected optical axis emitted from the galvano mirror is arranged to swing within the parallel plane Ql, centering on a line of intersection formed by a second perpendicular plane separating the two planes and a plane parallel to the recording medium. An optical system for making the light beam emitted from - enter the objective lens is constituted by an optical element having two reflective surfaces within the carriage.

[Industrial application field]

The present invention relates to an optical signal recording/reproducing device, and particularly to a separate type optical head for realizing miniaturization of the optical head.

Optical disk devices record and reproduce information on a recording medium using a minute spot focused on the wavelength, and therefore are capable of higher density recording than conventional recording devices. In addition, because it is a non-contact recording method in which the objective lens that focuses the laser beam and the recording medium surface are separated by about 1+a+, there is a risk of head crashes in magnetic disks, which are currently widely used as external storage devices for large computers to small machines. In comparison, high reliability can be ensured.

It also has the same interchangeability as the Fronbi disk and magnetic tape, which were the main reason for the spread of the current WS (workstation)/PC (personal computer).

Therefore, it is expected to have a wide range of applications, from large general-purpose computers to WS/PCs.

Additionally, with the advancement of optical disk technology, there has been a shift from conventional write-once type optical disks, where users can write data only once, to rewritable types, such as magnetic disks and floppy disks, where data can be recorded and erased as many times as needed. Ta. Along with this, the field of application is also becoming much broader.

However, regarding access performance and data transfer performance,
There is still room for improvement. Basically, data transfer speeds need to be addressed by increasing the output of semiconductor lasers and increasing the sensitivity of media.

On the other hand, regarding access performance, there is a strong desire to reduce the weight of the movable parts. In the future, the development of optical disk devices will tend to be polarized into higher performance and lower cost, similar to the progress that has been made in the development of magnetic disk devices.

[Conventional technology]

FIG. 3 shows a block diagram of main parts of a conventional optical signal recording/reproducing device. Note that, in order to make the explanation of the configuration and operation easier to understand, the same parts are given the same reference numerals throughout all the figures, and repeated explanation thereof will be omitted.

In the figure, ■ is a semiconductor laser used as a light source, and 2 is a semiconductor laser used as a light source.
is a collimating lens that shapes the emitted light of the semiconductor laser l into parallel light 7, and the parallel light 7 passes through the beam splitter 3,
The light is reflected by the reflection mirror 4 and enters the objective lens 5. The objective lens 5 follows the surface deflection and eccentricity of the recording medium 6, which is rotated at a constant speed by the spindle 8, and irradiates a laser beam as a minute spot on a predetermined track. (However, the driving and moving mechanism of the objective lens 5 is not shown.) The reflected light containing the information component on the recording medium 6 travels backward along the same optical path as when it was incident, is reflected by the beam splitter 3, and is halved. By passing through the wavelength plate 9, the polarization plane is rotated by 45 degrees, and the polarization beam splitter 10 separates the light into transmitted light and reflected light, which are sent to the photodetector 1 via condensing lenses lla and llb, respectively.
2a and 12b, and a reproduction signal and a focus/track error signal for driving the objective lens 5 in the optical axis direction and the track direction are detected.

The minute spot narrowed down to the diffraction limit by the objective lens 5,
The biggest issue that determines the reliability of an optical signal recording/reproducing device is how to stably and precisely focus on a predetermined track. The principle and objective lens driving method are not directly related to the present invention, so they will be omitted here.

Conventional (for example, image data filing system,
The 5-inch optical disk drive (5-inch optical disk drive, which has been standardized by the International Organization for Standardization (International Organization for Standardization) and is already on the market) integrates all the systems shown in Fig. Recording medium 6 with an access mechanism such as
The predetermined track on was being accessed. Therefore, the weight of the movable part is several tens of grams, and the standard access time is several tens of nanoseconds to 100 wIs. Furthermore, for magnetic disks and floppy disks, the shape of the drive is within a size called half-hide, but in the case of optical disks, it has been the best to fit within a size called full-hide. A separation optical system is one of the means to solve these problems.

FIG. 4 shows a block diagram of the main parts of a conventional separation optical system.

In the figure, reference numeral 13 denotes a carriage that is reciprocated in the radial direction of the recording medium 6 (in the direction of arrow A) by a VCM (not shown), and an actuator 14 that minutely drives the objective lens 5 is mounted on the carriage 13. The optical system and fixed part 15 mounted on this carriage 13
and are connected only by the parallel light 7 emitted from the fixed part I5. With this configuration, the weight of the movable part (the entire carriage 13) can be significantly reduced, but if you aim to further reduce the size and weight, the two-dimensional actuator (focusing actuator 14) mounted on the carriage 13 may be used.
A configuration has been considered in which a galvanometer mirror (not shown) is used as the tracking actuator and is disposed on the fixed part 15.

FIG. 5 shows a main part configuration diagram of a separation optical system in which a conventional tracking control section is provided on the fixed section side. Moving part carriage 1
3, an objective lens 5, a focusing actuator 14a and a reflecting mirror 4, which constitute a one-dimensional actuator.
It is configured with the following. Further, the galvanometer mirror 16 constituting the tracking actuator provided on the fixed part side is arranged in a plane perpendicular to the medium surface of the recording medium 6 with reference to the shaft 16a (bearing fittings are not shown) (in other words, the shaft 16a
the axial direction of a is parallel to the medium surface of the recording medium 6),
The reflective surface of the galvanometer mirror 16 swings in the direction of arrow B (perpendicular to the medium surface).

[Problem to be solved by the invention]

However, in this configuration, the plane formed by the swing range of the reflection optical axis of the galvanometer mirror 16 is in the moving direction of the objective lens 5 (
The shape of the galvanometer mirror 16 is within the first perpendicular plane 17 with respect to the recording medium 6 including the direction of arrow A), and the shape of the galvanometer mirror 16 is
6a in the swing direction, and the height direction (full hide dimension), which is the main theme of miniaturizing the optical head, is thinner.
<I can't. In order to make it thinner, it is better to be able to swing the galvanometer mirror 16 in a plane parallel to the surface of the recording medium.

However, with the structure shown in Fig. 5, the shaft 16a of the galvano mirror 16
If the spot is oscillated in a plane parallel to the surface of the recording medium, the spot moves not in the track direction of the recording medium surface but in the circumferential direction, which has the drawback that normal track following control is impossible.

The present invention has been made in view of the above-mentioned conventional drawbacks, and an object of the present invention is to provide a structure that makes it possible to reduce the thickness of an optical head using a galvano mirror.

[Means to solve the problem]

FIG. 1 is a principle diagram of the present invention, and FIG. 2 is an embodiment of the present invention. Using a semiconductor laser 1 as a light source, a device for recording/reproducing signals on a recording medium 6 produces a minute spot on a predetermined track through an objective lens 5, following the surface deflection and eccentricity of the rotating recording medium 6. A focus controllable part is mounted on the carriage 13 as an actuator for irradiation,
An information detection mechanism including a galvanomirror 16 for tracking in the track direction and a light source is disposed in the fixed part 15, and the carriage 13 and the fixed part 15 are optically coupled to each other to provide an optical signal of a separated optical system. In the recording/reproducing apparatus, a second perpendicular plane 1B is parallel to the recording medium 6 and is separated by a predetermined distance from a first perpendicular plane 17 to the medium surface of the recording medium 6, which includes the moving direction of the objective lens 5. The reflection optical axis emitted from the galvano mirror 16 is arranged to swing within the parallel plane 19 around an intersection line 19a formed by the plane 19, and the light flux emitted from the galvano mirror 16 is An optical system for making the light incident on the objective lens 5 is constituted by an optical element having two reflective surfaces in the carriage 13. The first reflecting surface 20a that reflects first is arranged so as to be bent in a perpendicular direction within a plane parallel to the medium surface of the recording medium 6, and the second reflecting surface 20b that reflects next It is arranged so that the reflected light from the surface 20a is reflected in a direction perpendicular to the medium surface.

[For production]

The shaft 16b that swings the galvanometer mirror 16 is connected to the recording medium 6.
Since the galvanometer mirror 16 is disposed in a direction perpendicular to the medium surface, there is an advantage that the inner body of the galvanomirror 16 can be made thinner with respect to the perpendicular direction. As a result, the reflected light beam emitted from the galvano mirror 16 is oscillated within a plane 19 parallel to the medium surface. An optical element having at least two reflective surfaces is used to convert this swinging direction into the direction of movement of the objective lens 5 (direction of arrow A). The parallel light 7 emitted from the fixed part 15 is reflected by the galvanometer mirror 16 so as to be oscillated in a plane parallel to the medium surface 19, and then reflected at a right angle within the parallel plane 19 by the first reflecting surface 20a. can be folded into

Next, the light is further bent by the second reflecting surface 20b in a direction perpendicular to the medium surface (perpendicular direction), and enters the objective lens 5. As a result, the light flux that was swinging in the galvanometer mirror I6 within a plane parallel to the medium surface is removed from the objective lens 5.
a first perpendicular plane 1 with respect to the medium plane including the direction of movement of
The light spot that is converted to oscillate within the lens 7 and focused by the objective lens 5 can be accurately track-followed.

〔Example〕

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

FIG. 1 is a diagram showing the principle of the present invention, and FIG. 1(a) is a perspective view, and FIG. Indicates the axis for movement. This shaft 16b and galvano mirror
The 16 reflective surfaces are arranged in a direction perpendicular to the medium surface of the recording medium 6.

Reference numeral 17 is referred to as a first vertical plane, and indicates a plane perpendicular to the medium surface including the moving direction (direction of arrow A) of the objective lens 5 that moves in the radial direction of the recording medium 6.

Reference numeral 18 refers to a second vertical plane, which is a plane separated from the first vertical plane 17 by a required distance. The required distance indicates the distance between the central optical axis between the first reflective surface 20a and the second reflective surface 20b, which will be described later.

Reference numeral 19 indicates a plane parallel to the recording medium 6, which includes the center line of the swing range of the reflection optical axis emitted from the galvanometer mirror 16. Reference numeral 19a indicates a line of intersection between the second vertical plane 18 and the parallel plane 19, and the direction in which the reflected optical axis emitted from the galvano mirror 16 swings is within the parallel plane 19 with this intersection line 19a as the center. A galvanometer mirror 16 is arranged so as to swing.

Reference numeral 20a designates a first reflecting surface, which first reflects the light beam emitted from the galvanometer mirror 16, and is arranged so as to bend it in a perpendicular direction within a plane parallel to the medium surface of the recording medium 6. .

Reference numeral 20b indicates a second reflecting surface, and the reflected light that is bent at right angles within the parallel plane 19 by the first reflecting surface 20a is further reflected by the second reflecting surface 20b in a direction perpendicular to the medium surface (perpendicular direction). It has the function of bending the beam into the objective lens 5 and making it incident on the objective lens 5.

Therefore, the light beam that was oscillated by the galvanometer mirror 16 in a plane parallel to the medium surface finally oscillates in a plane perpendicular to the medium surface and in the direction of movement of the objective lens 5 (in the direction of arrow A). This enables accurate track following.

FIG. 2 is a diagram showing an embodiment of the present invention, and shows a layout diagram of the entire fixing part 15 in comparison with the principle diagram of FIG. 1. Since the galvanometer mirror 16 is swung in the direction of arrow C around the shaft 16b, it can be easily formed to be thin in the direction perpendicular to the medium surface. In this figure, a mechanism (VCM) that drives the carriage 13 is shown.

guide rails, etc.) are omitted.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the weight of the movable part is reduced by employing a separating optical system, arranging the galvanometer mirror in a fixed part, and making the swinging direction in the same plane as the medium surface. This solves the problem of thinning in the thickness direction. Therefore, it is possible to improve the access time and downsize the device, which have been pointed out as points to be improved in conventional optical disk devices.

Figure 3 is a diagram showing the main parts of a conventional optical signal recording/reproducing device, Figure 4 is a diagram showing the main parts of a conventional separation optical system, and Figure 5 shows a conventional separation system in which the tracking control section is provided on the fixed part side. The main part configuration diagram of the optical system is shown.

1 and 2, l is a semiconductor laser, 5 is an objective lens, 6 is a recording medium, 13 is a carriage, 15 is a fixed part, 16 is a galvanometer mirror 1) 7 is a first vertical plane, 1
8 is a second vertical plane, 19a is an intersection line, 20a is a first reflective surface, and 20b is a second reflective surface.

[Brief explanation of drawings]

Figure 1 is a diagram of the principle of the present invention. FIG. 2 is a first embodiment of the present invention. ．． 6il Hi Blunt 1 Dedicated \,of (b) Plan view 7F missing barrier map Figure 1 Engineering 1;3 Diagram

Claims (3)

[Claims] (1) A semiconductor laser (1) is used as a light source, and a recording medium (6)
As an actuator for irradiating a minute spot onto a predetermined track via an objective lens (5) by following the surface deflection and eccentricity of the rotating recording medium (6) of a device for recording/reproducing signals on the recording medium (6). , a focus controllable part is mounted on the carriage (13), an information detection mechanism including a galvanometer mirror (16) for tracking in the track direction and a light source is disposed on the fixed part (15), and the carriage (13) In the optical signal recording and reproducing apparatus of the separation optical system, which is formed by optically coupling the fixed part (15) and the fixed part (15), an intersection line (19a) formed by a second vertical plane (18) separated by a required distance from the first vertical plane (17) and a plane parallel to the recording medium (6);
An optical signal recording/reproducing device characterized in that the optical signal recording/reproducing device is arranged such that a reflection optical axis emitted from the galvano mirror (16) is oscillated within the parallel plane (19) about the center. (2) an optical system for making the light flux emitted from the galvano mirror (16) enter the objective lens (5);
2. The optical signal recording and reproducing apparatus according to claim 1, wherein said carriage (13) is comprised of an optical element having two reflective surfaces. (3) Among the two reflecting surfaces, the galvano mirror (1
The first reflecting surface (20a) that first reflects the light beam emitted from the recording medium (6) is arranged so as to bend it in a perpendicular direction within a plane parallel to the medium surface of the recording medium (6), and then reflects it. The second reflective surface (20b) is the first reflective surface (
2. The optical signal recording and reproducing apparatus according to claim 1, wherein the optical signal recording and reproducing apparatus is arranged so that the reflected light from the medium 20a) is reflected in a direction perpendicular to the medium surface.