JP2758232B2 - Optical pickup device and optical information recording / reproducing device using the same - Google Patents

Description

Description: Object of the Invention (Field of Industrial Application) The present invention relates to an optical pickup device and an optical information recording / reproducing device using the same, and more specifically, to optically record an information signal on an optical information recording medium. More specifically, the present invention relates to an optical pickup device and an optical information recording / reproducing device capable of recording / simultaneous erasure, recording error detection, erasure check, and reducing the size and weight of the entire device.

(Prior Art) An optical pickup device of a conventional optical information recording / reproducing apparatus which optically records a required information signal on an optical information recording medium or erases or optically reproduces the recorded information,
It is configured as shown in FIG. However, for simplification of the technical content, a description will be given of a case where a semiconductor laser is used as a light beam radiation source as a representative example. That is, the semiconductor laser 1a is used as a light beam radiation source, the collimator lens 2 for converting the light emitted from the semiconductor laser into parallel light, the beam splitter 3, and the optical deflector 4 for deflecting the optical path of the laser light.
And a condenser lens 5 for condensing the incident light beam on the optical information recording medium 6.

In the above-described optical pickup device, a TE (lateral electric field) mode (or TM (horizontal magnetic field) mode) light beam emitted from the semiconductor laser 1 is collimated by the collimator lens 2 and is incident on the beam splitter 3. The incident surface 3a of the beam splitter 3 has an anisotropic cross-sectional shape of a light beam whose output light has been made parallel (the beam cross-sectional shape of the output laser light has a short diameter in a direction parallel to the bonding surface of the semiconductor laser, The beam cross-section of the light beam transmitted through the beam splitter 3 is formed so as to have a necessary angle for converting an ellipse having a long diameter in the direction into an isotropic shape (a beam cross-sectional shape of the light beam is circular). It is circular.

Thus, the light beam having a circular beam cross-sectional shape is reflected by the reflection mirror 4 and is condensed on the recording surface of the optical information recording medium 6 by the condenser lens 5. The optical information recording medium 6
The light beam incident on the recording surface is reflected by the recording surface, passes through the condenser lens 5 and the reflection mirror 4, and is further reflected by the reflection surface 3 b of the beam splitter 3. The light passes through 9 and is given astigmatism, and is incident on a quadrant (made of a photodiode) photodetector 10.

In the four-divided photodetector 10, a difference signal of the sum of the outputs of the two photodetectors becomes a tracking error signal with a dividing line parallel to the information track on the optical information recording medium 6 as a tracking error signal. The focus error signal is obtained by taking the difference signal of the sum of the outputs of the photodetectors arranged at the diagonal positions of the detector 10.

The above-mentioned tracking error signal passes through a tracking control circuit (not shown), and moves the converging lens 5 in the direction of the rotation axis (perpendicular to the recording medium surface) of the optical information recording medium 6 so as to follow the surface deflection of the optical information recording medium. I do.

When recording or erasing a required information signal on the optical information recording medium by using the above-described optical pickup device, the information is recorded or erased in the first rotation of the optical information recording medium 1, and The recording information is reproduced by the rotation of, and a recording error is detected or erased. For this reason,
The time required for recording and erasing becomes extremely long, resulting in a memory device with poor data processing efficiency.

As a method of improving the processing efficiency of information recording and erasing of recorded information of such an optical information recording / reproducing apparatus to the same level as a magnetic disk memory device, for example, a collection of lecture proceedings at the Optical Memory Symposium hosted by the Institute of Telecommunications, "Optical Memory Symposium" Real-time error detection is possible by using two semiconductor lasers that emit laser beams of different wavelengths described in the “Two-beam write-once optical head” reported in the '86 Transactions ”p.113-120 And a two-beam optical pickup device, and the Japanese Journal of Applied Physics published by the Japan Society of Applied Physics, Vol. 26 (198
7 years) A paper published in Supplement 26.p.117-120, "Co
mpact two−Beam Head with a Hybrid Two−Wavelength
2 that emit laser beams of different wavelengths, as disclosed in "Laser Array for Magne to-optic Recording"
It has been considered that a two-beam type optical pickup device including a hybrid type semiconductor laser in which one semiconductor laser is installed in one package is used.

(Problems to be Solved by the Invention) However, each of the above-described optical pickup devices separates the laser beam of the semiconductor laser for information recording or erasing of recorded information from the laser beam of the semiconductor laser for error detection or remaining erase check. The optical system must be detected, and the configuration of the optical system becomes complicated. In addition, there is a problem that the number of optical elements is greatly increased.

Therefore, the present invention eliminates the disadvantages of a conventional optical pickup device and an optical information recording / reproducing device using such an optical pickup device, such as low data processing efficiency, complicated device configuration, and large size, and is inexpensive and simple. It is an object of the present invention to provide an optical pickup device capable of real-time data check and an optical information recording / reproducing device capable of realizing a data processing speed comparable to that of a magnetic disk memory device by using an optical system having such a configuration.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above object, an optical pickup device according to the present invention includes a light beam radiation source and an optical deflection device for deflecting an optical path of a light beam emitted from the light beam radiation source. Means, collimator lens means disposed between the light beam radiation source and light deflecting means, and convergent optical means for condensing a light beam whose optical path is deflected by the light deflecting means on an optical information recording medium. An optical pickup device comprising: a TE mode light having a constant oscillation wavelength difference and a TM;
A semiconductor laser that simultaneously emits mode light and has a function of controlling the light amount of these TE mode light and TM mode light is used. A diffraction grating is used as a light deflecting means. Are condensed at different positions by convergent optical means.

Further, one of the optical information recording / reproducing apparatuses according to the present invention is an optical information recording medium, and a light beam for optically recording an information signal or erasing recorded information on the optical information recording medium according to a predetermined information signal. An optical information recording / reproducing device comprising: an optical pickup device for irradiating the optical pickup device; wherein the optical pickup device according to the present invention is used as the optical pickup device, and the oscillation wavelength difference emitted from the semiconductor laser of the optical pickup device is constant.
The TE mode light and the TM mode light are focused on the same track of the optical information recording medium, and the information signal is optically recorded or the recorded information is erased by one of these focused lights, and the other focused light is focused. In this configuration, error detection or erasure detection of recorded information is performed by light.

Another aspect of the optical information recording / reproducing apparatus according to the present invention is an optical information recording medium, and an optical information recording medium for optically recording an information signal or erasing recorded information on the optical information recording medium according to a predetermined information signal. An optical information recording / reproducing apparatus comprising: an optical pickup device for irradiating a beam; wherein the above-described two-beam optical pickup device according to the present invention is used as the optical pickup device;
TE mode light and TM mode light having a constant oscillation wavelength difference emitted from the semiconductor laser of the beam type optical pickup device are positioned on different tracks of the optical information recording medium, and an information signal is optically recorded or recorded in parallel. It is configured to perform a reproducing operation.

(Operation) As described above, in the optical pickup device according to the present invention, the semiconductor laser and the diffraction grating having the simultaneous oscillation function of the TE mode light and the TM mode light with a constant oscillation wavelength difference and the function of controlling the light quantity of both mode lights are used. Since TE light and TM light with a constant oscillation wavelength difference are reflected by a diffraction grating, the TE mode light and TM mode light change the diffraction angle of the diffracted light according to the wavelength difference, and enter the condenser lens. The angle changes. Accordingly, a plurality of mode lights are generated at regular intervals on the optical information recording medium, and can be used for recording or erasing with one mode light and error detection or erasing detection with the other mode light on the same track. . In this optical pickup device, since the polarization directions of the TE mode light and the TM mode light are different from each other by 90 °, one optical element such as a polarization beam splitter can be used.
Since the apparatus can be easily separated and detected, the entire apparatus can be easily reduced in size and weight.

Further, the optical information recording / reproducing apparatus of the present invention utilizes a phenomenon that a diffraction angle of light diffracted by a diffraction grating is different at a wavelength of incident light, and only a laser structure is used as a beam radiation source of an optical pickup device. An optical information recording / reproducing apparatus having a real-time data error detection function can be easily realized by using a semiconductor laser that simultaneously emits TE mode light and TM mode light having a constant wavelength difference determined by the following equation.

(Example) Next, a typical example of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a main part of an embodiment of an optical pickup device according to the present invention. In the figure, 1a is a distributed feedback type having a function of oscillating a TE mode light and TM mode light of the oscillation wavelength difference 4nm simultaneously (hereinafter "DFB") G _a I _{n A
s} P semiconductor laser, 2 is a collimator lens, 3 and 8 are beam splitters, 5 and 7 are focusing lenses, 4 is a reflection type diffraction grating, 6a is an optical disc whose recording medium layer is made of a write-once (or phase transformation type) material, Reference numeral 9 denotes a cylindrical lens, reference numeral 10 denotes a four-division photodetector, and reference numeral 11 denotes a photodetector separately provided from the photodetector 10.

In this two-beam type optical pickup device, the semiconductor laser 1a is used.
The TE mode light 1A (solid line in the figure) emitted from the device is used as a signal recording or erasing light beam, and the TM mode light 1B (dashed line in the figure) is used as a recording signal error detecting beam or unerased detection during erasing operation. The case of using as a beam will be described. First, the TE mode light 1A for recording or erasing is converted into parallel light by the collimator lens 2, and the beam splitter 3 (for example, as a polarization characteristic, P-polarized light transmittance Tp = 0.7, S-polarized light transmittance T
s = 0.4) is reflected by the reflection type diffraction grating 4, and the reflected diffraction light is condensed by the focusing lens 5, and
A minute spot is formed on an information track on the medium surface (write-once type medium or phase change type medium) 6a.

The reflected light beam from the optical disk 6a passes through the converging lens 5 and the reflection type diffraction grating 4 again, and a part of the light beam is reflected by the beam splitter 3 and guided to a photodetection system. The light beam separated from the backlight system passes through the second polarizing beam splitter 8 while being converged through the condenser lens 7, and then the light beam given astigmatism by the cylindrical lens 9 is split into four light detectors 10. To receive light. The difference signal between the sum output of the two photodetectors in the four-split photodetector and the sum output of the other two photodetectors becomes a tracking error signal with a dividing line parallel to the information track of the optical disk 6 as a tracking error signal. A focus error signal is obtained by taking a difference signal between the sum output and the sum output arranged at the angular position.

On the other hand, the TM mode light 1B (having a constant oscillation wavelength difference from the TE mode light 1A) for detecting the error of the recording signal or detecting the residual signal amount during the erasing operation passes through the same backlight system as the TE mode light 1A. After being reflected by the reflection type diffraction grating 4 with a diffraction angle deviation corresponding to the wavelength difference from the TE mode light 1A, the light enters the focusing lens 5. Therefore, the TM mode light 1B forms a minute spot on the information track of the optical disc 6 at a position separated from the TE mode light focusing position by a certain distance. TM mode light
A part of the reflected light beam from the 1B optical disk 6 is reflected by the beam splitter 3, and after passing through the condenser lens 7,
The light is reflected by the second beam splitter 8 and guided to the photodetector 11.

The optical disk 6a has a wavelength of light incident on the reflection type diffraction grating 4.
The principle by which the light spot position on the medium surface changes will be described with reference to FIG. When a light beam incident on the reflection type diffraction grating 4 having a repetition period P of the diffraction grating at an incident angle θ ₁ is reflected and diffracted in a direction of θ ₀ with respect to a normal N of the surface of the diffraction grating, as is well known, Equation (1) holds between the angles θ ₁ and θ ₀ , the period P, and the wavelength λ of light.

P (sin θ ₁ −sin θ ₀ ) = inλ (m = 1, 2,...) (1) Here, m represents the diffraction order. Now, the wavelength of light λ
_{If the} incident light is bent at a right angle by diffraction at the time of ₁ (solid line in the figure), the expression (2) is established.

θ ₁ + θ ₀ = π / 2 (2) At this time, the incident angle of the light beam on the focusing lens 5 is 0 °.

On the other hand, when the light wavelength is λ ₂ (λ ₁ <λ ₂ , broken line in the figure), the angle θ ₁ and the period P do not change, so the diffraction angle changes to θ ₀ + Δθ. At this time, Δθ is expressed by equation (3).

Δθ = (λ ₂ −λ ₁ ) / P (3) The incident angle on the focusing lens 5 is Δθrad, and the light spot movement amount on the medium of the optical disk 6 is Δd = Δθ · f (4) where f is the focusing lens Represents the focal length.

That is, the optical wavelength difference λ ₂ −λ ₁
The light spot on the medium surface 6a moves by Δd.

 Specific numerical examples are shown below.

θ ₁ = 65.16 ° θ ₀ = 24.84 ° When m = 1 (first-order diffracted light) and λ ₁ = 780 nm, P = 1.6 μm from equation (1). If λ ₂ = 784 nm here, then Δθ = 2.5mra
d If the focal length f of the focusing lens is 4 mm, then from equation (4), Δd = 10 μm. If the oscillation wavelength difference between the TE mode light and the TM mode light of the semiconductor laser of the light source is 4 nm, two light beams separated by 10 μm can be formed on the optical disk.

An example of the semiconductor laser 1a having a simultaneous oscillation function of the TE mode light and the TM mode light having a constant oscillation wavelength difference used in the optical pickup device of the present embodiment is given in 1988 Autumn Meeting of the Japan Society of Applied Physics. Proceedings 4p-ZC-1 D833 of p833
There is a laser.

The divergence angle of the light beam emitted from the semiconductor laser chip is often anisotropic. Spreading angle θ‖ of laser chip parallel direction and spreading angle θ⊥ of laser chip vertical direction
Is that θ‖ <θ⊥ and the aspect ratio θ⊥ / θ２〜 is 2-3. When the direction of the light beam incident on the reflection diffraction grating is matched with the direction of the laser chip bonding surface, the light beam in the bonding direction is expanded by the difference between the incident angle θ ₁ and the diffraction angle θ ₀ to become an isotropic light beam. Can be converted.

In the diffraction grating shown in the previous example, θ ₁ = 65.16 °, θ ₀ = 24.
Since it is 84 °, the light beam expansion rate M is M = cos θ ₀ / cos θ ₁ = 2.16. The ratio of the divergence angle (aspect ratio) of the semiconductor laser used is set to θ ₁ , θ ₀ so as to be equal to the light beam expansion ratio.
Is determined, beam shaping of the conventional optical pickup device becomes unnecessary, and the configuration of the optical system can be further simplified.

As described above, by combining a semiconductor laser and a reflective diffraction grating that simultaneously oscillate TE light and TM light with a constant oscillation wavelength difference, an optical pickup device that can easily detect errors in real time can be obtained. Further, since the oscillation wavelength difference is uniquely determined only by the laser structure such as the length of the laser resonator, precise optical system adjustment is not required unlike the related art, and the cost of the optical pickup device can be reduced.

Next, FIG. 3 shows an embodiment of the real-time error detecting section in the circuit block diagram of the optical information recording / reproducing apparatus using the optical pickup device 20 of the present invention described above.

In the recording signal generation circuit section 21, the recording signal modulated in accordance with the recording information is sent to the laser driving circuit section 22, and modulates, for example, the TE mode light amount to record data on the medium surface of the optical disk 6a. On the other hand, the recorded data is transmitted to the data reproducing circuit unit 24 using the TM mode light focused on the same track and at a fixed distance from the TE mode light spot position focused on the medium surface of the optical disk 6a. To play.

To detect an error in the recording data, the recording signal from the recording signal generating circuit unit 21 is used for recording on the optical disc and recording TE mode light on the optical disc.
This is performed by comparing the signal obtained by delaying the time corresponding to the TM mode inter-light distance by the delay circuit unit 23 with the signal binarized in the data reproduction circuit unit 24 by the comparison circuit unit 25.

Here, when an error exceeding the preset number of errors occurs between both signals, an error flag is sent to the data control unit 26, and a replacement process operation to a predetermined track is performed.

In the above embodiment, error detection during signal recording has been described.In the case of an optical information recording / reproducing apparatus having an erasing function, both TE and TM mode light beams are respectively applied to different tracks for detection of remaining erasure during signal erasure. In the case of following, a parallel reproduction operation becomes possible. Similar effects can be obtained by using a laser having a TE mode and TM mode simultaneous oscillation function other than that described in the above embodiment. Although the example of application to the optical disk 6a has been described in the embodiment of FIGS. 1 and 3, the present invention is also applicable to an apparatus using an optical information recording medium other than the optical disk.

In the above embodiment, an example in which a reflection type diffraction grating is used as the diffraction grating has been described. However, the present invention can be realized by using not only such a reflection type diffraction grating but also a transmission type diffraction grating.

〔The invention's effect〕

In the optical pickup device according to the present invention, by using a light beam radiation source having a simultaneous oscillation function of the TE mode light and the TM mode light having a constant oscillation wavelength difference with the diffraction grating, the light with the error detection function in real time can be obtained. A pickup device and an optical information recording / reproducing device can be easily realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of the essential parts of an embodiment of an optical pickup device according to the present invention, FIG. 2 is a diagram illustrating the principle of operation of the diffraction grating of the optical pickup of FIG. 1, and FIG. FIG. 4 is a block diagram showing a schematic configuration of a real-time error detection circuit of the recording / reproducing apparatus, and FIG. 4 is a schematic configuration diagram of an optical pickup device of a conventional optical information recording / reproducing apparatus. DESCRIPTION OF SYMBOLS 1 ... Light beam radiation source 1a ... Semiconductor laser 2 ... Collimator lens 3 ... Beam splitter 5 ... Condensing lens 6 ... Optical information recording medium 6a ... Optical disk 10, 11 ... Photodetector

Claims (5)

(57) [Claims] 1. A light beam radiation source, light deflecting means for deflecting an optical path of a light beam emitted from the light beam radiation source, and a collimator lens disposed between the light beam radiation source and the light deflecting means. And a converging optical means for converging a light beam whose optical path has been deflected by the light deflecting means on an optical information recording medium, wherein the light beam radiation source is provided with a TE having a constant oscillation wavelength difference. A semiconductor laser that emits mode light and TM mode light at the same time and has a function of controlling the amount of TE mode light and TM mode light is used. A diffraction grating is used as a light deflecting means, and the TE mode diffracted by the diffraction grating is used. And an optical pickup device for converging the TM mode light to two different positions by convergent optical means. 2. A semiconductor laser according to claim 1, further comprising a carrier confinement layer made of a semiconductor material of opposite conductivity type and having a larger band gap width than that of the active layer on the lower surface of the active layer. An optical pickup device comprising a carrier confining layer having a diffraction grating engraved groove and a distributed feedback laser structure. 3. A semiconductor laser having a distributed feedback laser structure according to claim 2, wherein the direction of extension of the grating line of the diffraction grating engraved groove formed in the carrier confinement layer of the semiconductor laser is perpendicular to the junction surface of the semiconductor laser. An optical pickup device, which is provided. 4. An optical information recording medium comprising: an optical information recording medium; and an optical pickup device for irradiating the optical information recording medium with a light beam for optically recording an information signal or erasing the recorded information according to a predetermined information signal. In the recording / reproducing apparatus, as an optical pickup device, a light beam radiation source, light deflecting means for deflecting an optical path of a light beam emitted from the light beam radiation source, and a light beam radiating means are disposed between the light beam radiation source and the light deflecting means. An optical pickup device comprising: a collimator lens means provided; and a converging optical means for converging a light beam whose optical path is deflected by the light deflecting means onto an optical information recording medium. Using a semiconductor laser having a constant difference TE mode light and TM mode light simultaneously, and having a function of controlling the light amount of these TE mode light and TM mode light, Using a diffraction grating, and using an optical pickup device that focuses the TE mode light and the TM mode light diffracted by the diffraction grating to two different positions by convergent optical means, and converts the TE mode light and the TM mode light into While focusing on the same track of the optical information recording medium,
A light characterized in that an information signal is optically recorded or recorded information is erased with one of these two condensed lights, and an error or erasure of the recorded information is detected with the other condensed light. Information recording and playback device. 5. An optical information recording medium comprising: an optical information recording medium; and an optical pickup device for irradiating the optical information recording medium with a light beam for optically recording an information signal or erasing the recorded information according to a predetermined information signal. In the recording / reproducing apparatus, as an optical pickup device, a light beam radiation source, a light deflecting unit for deflecting an optical path of a light beam emitted from the light beam radiation source, and between the light beam radiation source and the light deflecting unit. An optical pickup device comprising: a collimator lens means provided; and a converging optical means for converging a light beam whose optical path is deflected by the light deflecting means on an optical information recording medium. A light deflecting means using a semiconductor laser that simultaneously emits TE mode light and TM mode light having a constant wavelength difference and has a function of controlling the light amount of these TE mode light and TM mode light. Using a diffraction grating, and using an optical pickup device that focuses the TE mode light and the TM mode light diffracted by the diffraction grating to different positions by convergent optical means, respectively, focuses the TE mode light and the TM mode light. An optical information recording / reproducing apparatus, wherein the optical information recording / reproducing apparatus is configured to be positioned on different tracks of the optical information recording medium and to perform an optical signal recording / reproducing operation in parallel.