JPH06333255A - Optical head device - Google Patents

Abstract

PURPOSE:To enable a device to be compatible with different kinds of disk- shaped optical recording media different in disk base material thickness and a refractive index. CONSTITUTION:A light converging means is constituted of plural kinds of objective lenses 3a, 3b having light converging characteristics respectively corresponding to plural kinds of the disk-shaped optical recording mediums 31, 41 arranging along a tracking direction T and on which luminous fluxes 17 are made incident simultaneously by spectrum. The objective lens corresponding to the kind of the disk-shaped optical recording mediums 31, 41 being the object of optical recording between these objective lenses 3a, 3b is discriminated by focusing error information, and the light converging means 3a, 3b are driven and controlled in the direction F of focusing and in the direction T of tracking based on the focusing error information and tracking error information related to the corresponding objective lens 3a or 3b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device for an optical disk memory which is a device for optically recording and reproducing information.

[0002]

2. Description of the Related Art In recent years, an optical disk has been attracting attention as a large capacity information memory. In addition, a device using an optical disk as an information medium has been proposed, researched, and commercialized in various fields along with its software environment. However, on the other hand, a so-called multimedia information processing apparatus capable of integrally processing applications developed in various fields has been actively proposed. That is, development of an optical head device capable of comprehensively processing optical disks having different purposes and different optical characteristics is emphasized.

An example of the above-mentioned conventional optical head device will be described below with reference to FIG. In FIG.
The light beam 37 emitted from the semiconductor laser 34 provided on the optical table 36 side is incident on the objective lens 23 via the beam splitter 33 and the mirror 32 on the optical table 36 side as well. The optical characteristics of the objective lens 23 are designed to have the optical characteristics of the base material 31a of the optical disc 31, in particular, the light collecting characteristics corresponding to the parameters such as the thickness and the refractive index thereof. Base material 31 of disk 31
It is refracted by a and is irradiated onto the recording film 31b on the back side of the substrate 31 in an optimum spot shape. A protective film 31c is provided on the back surface of the recording film 31b.

A light beam 37 reflected by the recording film 31b passes through a mirror 32 and a beam splitter 33, and an optical stand 36.
It is incident on the photodetector 35 provided on the side. The photodetector 35 detects the information signal recorded on the optical disc 31 from the incident light, and the focusing direction control signal of the lens holder 24 holding the objective lens 23,
The focusing direction error signal and the tracking direction error signal for generating the tracking direction control signal are detected.

A focusing coil 25 fixed to the lens holder 24 and tracking coils 26a, 2
Part of 6b is magnets 21a, 21b and magnetic yoke 2
2 is located in the gap of the magnetic circuit, and the four magnetic suspensions 27a to 27a-2 are generated by the electromagnetic force generated by the magnetic field of the magnetic circuit and the driving current of each coil according to the control signal.
A lens holder 24 supported by 7d so as to be able to translate in a focusing direction F and a tracking direction T.
Is driven in the focusing direction F and the tracking direction T to control the position so that optical recording is performed in an appropriate light collecting state and tracking state.

[0006]

However, there are differences in the optical characteristics of the recordable or reproducible disk-shaped optical recording medium, particularly in the thickness and refractive index of the substrate 31a of the optical disc 31. Therefore, the light beam 37 emitted from the semiconductor laser 34
In order to irradiate the recording film 31b located on the back surface of the base material 31a with a proper light spot, the objective lens 23 side is required to have a light collecting condition adapted to the thickness and the refractive index of the base material 31a.

However, since the position control by driving in the focusing direction F is for adjusting a minute light collection deviation, it cannot cope with a large light collection deviation due to a difference in the type of the optical disk 31.

Therefore, if only one objective lens 23 is used as in the conventional case, it is held via a plurality of metal suspensions 27a to 27d so that it can be translated in the focusing direction F and the tracking direction T,
Because of the holding structure that allows the position to be controlled by driving in the focusing direction F and the tracking direction T, it cannot be replaced with another objective lens 23.

Therefore, there is a problem in that an optical disk that can be an optical recording target is uniquely fixed depending on the type of objective lens used, and compatibility with optical disks having different purposes and different optical characteristics is difficult. .

In view of the above-mentioned conventional problems, the present invention is compatible with devices for disc-shaped optical recording media having different purposes and different optical characteristics, particularly disc-shaped optical recording media having different thicknesses or refractive indexes of disc substrates. The optical head device is provided.

[0011]

In order to solve the above-mentioned problems, an optical head device of the present invention comprises an optical means for emitting a light beam for optical recording, and a light beam emitted from this optical means for disc-shaped light. Focusing error of the optical spot with respect to the disc-shaped optical recording medium due to a reflected light beam from the disc-shaped optical recording medium during the optical recording by collecting and irradiating the recording medium so as to form a light spot. And means for detecting a tracking error, and driving the light collecting means in the focusing direction and the tracking direction based on the focusing and tracking error information.
In the optical head device provided with a means for controlling, the light collecting means has light collecting characteristics respectively corresponding to the plurality of kinds of disc-shaped optical recording media and is arranged in the tracking direction,
In addition, the light flux is composed of a plurality of types of objective lenses that are made to enter simultaneously by spectroscopy, and one of these objective lenses that corresponds to the type of the disk-shaped optical recording medium that is the optical recording target is determined by the focusing error information. The driving and controlling of the light collecting means in the focusing direction and the tracking direction are performed based on the corresponding focusing error information and tracking error information of the objective lens.

In this case, the optical means can make the quantity of the emitted light beam incident on the light collecting means in correspondence with the optical characteristics of the disk-shaped optical recording medium which is the object of optical recording.

[0013]

In the above structure of the present invention, when the optical recording is performed by irradiating the light flux from the optical means through the light collecting means to form a light spot on the disc-shaped optical recording medium, the disc-shaped optical recording medium is irradiated. Focusing error and tracking error of the light spot with respect to the disc-shaped optical recording medium are detected by the detected light flux by the detecting means, and the light collecting means is driven by focusing, driving in each direction of tracking, and control means according to these focusing error and tracking error. Since the position is controlled by being driven in the scanning direction and the tracking direction, optical recording can be performed in an appropriate focusing state and tracking state.

In particular, the light collecting means is composed of a plurality of types of objective lenses having light collecting characteristics corresponding to the type of the disc-shaped optical recording medium. The light flux input to the disk-shaped optical recording medium, which is an optical recording target and is set at the recording position, is simultaneously irradiated. At this time, since the focusing error of the light spot of the light beam emitted by the objective lens having the light collecting condition suitable for the type of the disc-shaped optical recording medium as the optical recording target is smaller than that of other objective lenses. It can be determined from the focusing error information signal detected by the detecting means.

Then, the focusing and tracking directions are driven and controlled on the basis of the focusing error information signal and the tracking error information signal of the objective lens having a light collecting condition suitable for the type of the disk-shaped optical recording medium which is an optical recording target. As a result, the corresponding objective lens is brought into an appropriate focusing state, while the focusing error of the light flux passing through the other objective lens exceeds the recordable range, so that the recording is not affected, and each objective By arranging the lenses in the tracking direction, the corresponding objective lens that has been driven and controlled in the tracking direction is set to the proper tracking position, and as a result, optical recording using the corresponding objective lens is automatically performed. Can be achieved.

In this case, when the optical means makes the quantity of the emitted light beam incident on the light collecting means in correspondence with the optical characteristics of the disc-shaped optical recording medium which is the optical recording object, the disc-shaped light which is the optical recording object. Optical recording can be performed on the recording medium with a light flux having an appropriate amount of light.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical head device according to an embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is an exploded perspective view of an optical head device according to a first embodiment of the present invention. As shown in detail in FIG. 2, the optical disc 31 or 41 as a disc-shaped optical recording medium which is set at the recording position and is an optical recording target has base materials 31a and 41a made of a transparent resin or the like and a recording film 31b.
And 41b, protective films 31c and 41c, etc. are laminated, and have different optical characteristics as shown in FIGS. 2 (a) and 2 (b) depending on the thickness and refractive index of the base materials 31a and 41a. There is one.

A light beam 1 is applied to these optical disks 31 and 41.
Two objective lenses 3a and 3b are provided as means for collecting the light.
Are arranged along the tracking direction T and are fixed to one lens holder 4. The lens holder 4 is located between the magnets 1a and 1b arranged on the magnetic yoke 2 which is connected to the fixing member 8 at one end, and is arranged in the focusing direction F through the four metal suspensions 7a, 7b, 7c and 7d. , Are supported so that they can be translated in the tracking direction T.

The focusing coil 5 for driving the lens holder 4 in the focusing direction F to control the position is directly wound around the lens holder 4, and drives the lens holder 4 in the tracking direction T to control the position.
6b is fixed to the lens holder 4. Magnet 1
The letters a and 1b are fixed to the magnetic yoke 2 and form a magnetic circuit.

The beam separating mirror 1 is provided on the optical table 16 side.
2, a beam splitter 13, a semiconductor laser 14, and a photodetector 15 are arranged. The magnetic yoke 2 is fixed to the optical table 16 by means of screws or the like. The optical table 16 is held by a carrier (not shown), can move in the tracking T direction, and can perform optical recording on the entire recording range of the optical disks 31 and 41.

The operation of the optical head device configured as above will be described. The optical disc 31 and the optical disc 41 shown in FIGS.
There is a difference in thickness between a and 41a, and it is assumed that the base material 31a is thinner than the base material 41a. Further, the objective lenses 3a, 3
The light beam collecting characteristic which is the optical characteristic of b is designed according to the thickness of the base material of the optical disc. In this embodiment, the objective lens 3a is the base material 31a of the optical disc 31, and the objective lens 3b is This is the case where the optical disc 41 is designed corresponding to the base material 41a. FIG. 2A shows a light collecting state of the above-mentioned objective lenses 3a and 3b and the optical disc 31. In FIG. 1, a light beam 17 emitted from a semiconductor laser 14 is split into two light beams 17a and 17b by a light beam splitting mirror 12, and both objective lenses 3a and
3b is incident on the recording film 31b at the same time and is irradiated onto the recording film 31b as convergent light.

Since the objective lens 3a is designed so as to correspond to the optical disc 31, the converged light thereof is recorded by the recording film 31.
The optimum light spot is formed at the position of b, but the objective lens 3
In b, the optical characteristics, that is, the light collecting characteristics, are not appropriate between the optical disk 31 and the optical disk 31, so that the converged light is not sufficiently converged.

At this time, the light beams 17a and 17 irradiated onto the optical disk 31 through the objective lenses 3a and 3b.
The difference in the light collection state of b is that these light beams 17a and 17b
The reflected light beam from the optical disc 31 is detected as a difference in focusing error due to the difference in the state of being incident on the photodetector 15 via the beam splitting mirror 12 and the beam splitter 13, and the objective lens 3a having a smaller error is detected. It can be determined that the optical disc 31 is compatible.

Then, the focusing direction F and the tracking direction T of the lens holder 4 due to the electromagnetic force generated by the magnetic field in the gap of the magnetic circuit composed of the magnets 1a and 1b and the magnetic yoke 2 and the drive current of each coil according to the control signal. The signals for driving and controlling the light are generated based on the information of the reflected light flux from the objective lens 3a which is determined to correspond to the optical disc 31.

As a result, driving and position control in the focusing direction F and the tracking direction T are performed based on the focusing error information signal and the tracking error information signal for the corresponding objective lens 3a.
Therefore, while the corresponding objective lens 3a is brought into an appropriate focusing state, the focusing error of the light flux passing through the other objective lens 3b exceeds the recordable range for the optical disc 31, and thus there is no influence on the recording. Moreover, since the respective objective lenses 3a and 3b are arranged along the tracking direction T and the corresponding objective lens 3a subjected to the driving and position control in the tracking direction is set to the proper tracking position, as a result, the corresponding objective lens Optical recording using the selected 3a is automatically achieved.

Further, in FIG. 2B, the objective lens 3
Since b is designed in accordance with the optical characteristics of the optical disc 41, the convergent light from the objective lens 3b is generated by the recording film 41.
The optimum light spot is formed at the position of b, but the objective lens 3
Since a is unsuitable for the optical characteristics of the optical disc 41, its converged light is not sufficiently converged.

As a result, in the same manner as described above, the objective lens 3
It is determined that b is more suitable for the optical disc 41 that is the optical recording target, and driving and control of the objective lens 3b in the focusing direction F and the tracking direction T are performed. Optical recording using the lens 3b is automatically achieved.

As described above, according to this embodiment, the optical discs 31 and 41 having different optical characteristics, especially the thickness of the substrate are provided.
Is compatible with.

Further, in FIGS. 2 (a) and 2 (b),
The beam splitting mirror 12 is formed with two mirror surfaces 12a and a half mirror surface 12b for splitting the light beam 17 into two light beams 17a and 17b. The half mirror surface 12b is designed so as not to reflect the light beam 17 by 100% and has a transmittance that obtains the power of the light beam 17a suitable for being input to the optical disc 31 through the objective lens 3a, and is reflected by the half mirror surface 12b. The light beam 17b is adapted to obtain a power suitable for being input to the optical disc 41 via the objective lens 3b.

As a result, the two objective lenses 3a and 3b are provided corresponding to the optical disks 31 and 41 having different optical characteristics.
In addition to selectively using the two objective lenses 3a,
With the selective use of 3b, those optical disks 31, 41
It is possible to perform optical recording with a light beam having an amount of light corresponding to the optical characteristics, and to exhibit compatibility performance in accordance with more difference in optical characteristics than in the case where only the objective lenses 3a and 3b are selectively used. You can

[0032]

As described above, according to the present invention, among the plurality of types of objective lenses having the light collecting characteristics corresponding to the type of the disc-shaped optical recording medium, the disc-shaped optical recording medium to be the optical recording target is Since an objective lens having a light collecting condition suitable for the type is discriminated and optical recording is performed by the compatible objective lens, compatibility with a disc-shaped optical recording medium having different optical characteristics can be obtained. Moreover, the selective use of a plurality of objective lenses can be achieved by the drive and control functions in the focusing direction and the tracking direction required for normal optical recording in the simultaneous use state, so that the configuration is simple and can be realized at low cost.

In this case, by making it possible to obtain a luminous flux having a light amount suitable for the disc-shaped optical recording medium to be the optical recording target, compatibility performance corresponding to a larger number of different optical characteristics of the disc-shaped optical recording medium can be obtained. As a result, it is possible to stabilize and improve the recording characteristics.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an optical head device as an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating the operation of the apparatus of FIG.

FIG. 3 is an exploded perspective view of a conventional optical head device.

[Explanation of symbols]

 1a Magnet 1b Magnet 2 Magnetic yoke 3a, 3b Objective lens 4 Lens holder 5 Focusing coil 6a, 6b Tracking coil 7a, 7b, 7c, 7d Metal suspension 8 Fixing member 12 Beam separation mirror 12b Half mirror surface 15 Photodetector 17, 17a, 17b Light beam 31, 41 Optical disc 13 Beam splitter 14 Semiconductor laser 16 Optical stand

Claims (2)

[Claims] 1. Optical recording for emitting an optical beam for optical recording, and irradiating the optical beam emitted from this optical unit by collecting and irradiating the optical beam on a disc-shaped optical recording medium so as to form a light spot. Based on the focusing means and means for detecting a focusing error and a tracking error of the light spot on the disc-shaped optical recording medium by the reflected light flux from the disc-shaped optical recording medium at the time of this optical recording, based on these focusing and tracking error information. An optical head device comprising means for driving and controlling the light collecting means in a focusing direction and a tracking direction, wherein the light collecting means has light collecting characteristics corresponding to a plurality of kinds of disc-shaped optical recording media, and a tracking direction. And a plurality of types of objective lenses arranged so that the light beams are simultaneously incident by spectroscopy, Among these objective lenses, the one corresponding to the type of the disk-shaped optical recording medium which is the optical recording target is discriminated by the focusing error information, and the light collecting means based on the focusing error information and the tracking error information on the corresponding objective lens side. An optical head device characterized by being driven and controlled in the focusing direction and the tracking direction. 2. The optical means is adapted to be incident on the light collecting means in such a manner that the light quantity of the emitted light beam is made to correspond to the optical characteristics of the disk-shaped optical recording medium which is an optical recording target.
The optical head device described.