KR930005780B1 - Optical head - Google Patents

Abstract

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Description

Magnetic and optical heads for magneto-optical disk drivers

1 is a block diagram of an existing optical head for a magneto-optical device.

2 is a magnetic optical head configuration diagram according to the present invention.

3 is an enlarged view of the permanent magnet portion in FIG.

* Explanation of symbols for main parts of the drawings

10: recording magnetic and optical head 10 ': erasing magnetic and optical head

11: recording light source 11 ': erasing light source

12,12 ': Photoelectric conversion element for beam pull force detection 13,13', 13 ", 13" ': Half mirror

14,14 ': objective lens 15,15', 15 ", 15" ': photodetection lens

16,16 ', 16 ", 16"': Photodetector 17,17 ': Collimator

18: electromagnetic coil 18 ': permanent magnet

19: central axis 20: optical disc

According to the present invention, the erasing head and the recording head are provided together in order to reduce the time required for recording and erasing the magneto-optical information, so that the erasing and rewriting of the information can be performed almost simultaneously, and the erasing magnetic field is used as a permanent magnet. The present invention relates to a magnet and an optical head for a magneto-optical disk driver, which can provide a high-function magneto-optical device by saving energy and stabilizing the output by checking the output of the erasing light source and the recording light source.

Existing apparatuses for recording, reproducing and erasing magneto-optical information can be largely divided into three partial magnetic field modulators, a light source oscillator, and a reproduced reflection light source detector.

When described in conjunction with each of the parts as follows.

When recording, the magneto-optical recording material is irradiated with a semiconductor laser with an output of 15mw or more and heated to a temperature above the Curie temperature or the magnetic compensation temperature of the recording material to lose the magnetism (the original magnetic recording material is vertically upward and vertically downward). It is magnetized in one of two ways.) In this moment, the recording is done by reversing the direction of magnetization by applying a magnetic field from the outside.

The reproduction of the recorded signal is performed at several mw, which is much weaker than the laser output at the time of recording, in which the "Kerr effect" is mainly used. The Kerr effect is that when the light is reflected in different parts of the magnetic domain, the reflected wave is rotated with respect to the existing reflected wave and can be detected by a detector.

The erasing of the recording information is performed in the opposite way to the recording time.

The conventional apparatus for recording, reproducing, and erasing such magneto-optical information is shown in FIG. 1, and the disc mainly uses a pregrooved disc, in which recording is performed on a grooved pland.

Referring to the existing apparatus in more detail with reference to FIG. 1, the light emitted from the light source (2) enters the half mirror (3) via the collimator lens (2), where the light is transmitted straight and to the right. The beam that is reflected and bent to the right is also reflected immediately before transmission and right through the half mirror 3 '. At this time, the right reflected beam is incident to the photodetector 5 through the objective lens 4 'and the beam is used for focusing servo, and the beam transmitted straight from the half mirror 3' is the analyzer ( 7) and the beam incident on the photodetector 5 'through the objective lens 4 "is used for tracking servo. In addition, the beam passing through the half mirror 3 in a straight line is the objective lens. Beams (4) enter the disk (6) and the reflected beams are fed back to the photodetectors (5) 5 '.

6 shows an optical disk, 6a is ON-LAND, 6b is pre-prooved, and 6c is a recording bit.

In order to erase the already recorded information and to rewrite the information, the conventional apparatus needs to scan the portion to be rewritten in advance, delete the information, and then rewrite the information, which is quite cumbersome in time. The output of the light source cannot be checked.

As a result, in order to erase and rewrite the recorded information in the existing technology, since all the erase operations must be performed once and then the desired rewrite is performed, the work time becomes very long and complicated. As such a process, a computer interface is used. Not only is it easy, but also the output of the light source is checked, so that there is a defect in the safety of the optical system and the magnetic field when the device is operated.

In order to solve the above-mentioned conventional defects, the present invention is provided with the erasing magnetic and optical heads and the recording magnetic and optical heads positioned forward and backward along the tracks of the optical disc so that the information can be erased and rewritten almost simultaneously. The time required for erasing and recording the magneto-optical information is shortened, and the magnetic field of the erasing is a permanent magnet to save energy. Also, a laser beam oscillated backward from the light source behind the erasing light source and the recording light source. The present invention has been made to create a high-function magneto-optical device by installing a photoelectric conversion element for output detection and checking the output of two light sources to stabilize output. same.

As shown in FIG. 2 and FIG. 3, the present invention provides that the erasing magnetic and optical heads 10 'and the recording magnetic and optical heads 10 are arranged in order before and after along the track of the optical disc 20. FIG. It is an installed configuration.

The erasing magnetic and optical head 10 'and the recording magnetic and optical head 10 are each provided with an erasing light source 11' and a recording light source 11, which are semiconductor lasers, respectively. 11, the laser beam forward oscillated is incident on the optical disk 20 through the collimator lens 17 ', 17, the half mirror 13 ", 13, and the objective lens 14', 14, The reflected light is incident on the half mirrors 13 '"and 13' through the objective lenses 14 'and 14 and the half mirrors 13" and 13, and is reflected in the rectilinear transmission and the orthogonal directions.

The straight transmission beam is detected by the photodetectors 16 "and 16 through the photodetecting lenses 15 '" and 15' for tracking control, and the reflected beam is used as the photodetecting lens for focusing control. 15 " and 15 " are detected by the photodetectors 16 " and 16 ", and erased and recorded by the permanent magnet 18 'and the electromagnet coil 18, respectively. The permanent magnet 18 'is rotatably installed on the basis of the rotation shaft 19. Further, behind the erasing light source 11 'and the recording light source 11, there are provided photoelectric conversion elements 12' and 12 for detecting the output of the laser beam oscillated back therefrom. The recording magnetic and optical head 10 and the erasing optical head 10 'are connected via an interface 21. In the figure, 20a is an on land, 20b is a free groove groove, and 22 is a moving direction of the disk 20.

Referring to the effects of the present invention as described above are as follows.

The laser beam oscillated in the front and rear directions in the recording light source 11 and oscillated backward is detected by the output detection photoelectric conversion element 12.

The laser beam forward oscillated by the recording light source 11 of the recording magnetic and optical head 10 passes through the collimator lens 17, and then the beam that passes straight through the half mirror 13 enters the objective lens 14. The beam incident on the optical disk 20, and the beam reflected from the optical disk 20, enters the half mirror 13 ′ through the objective lens 14 and the half mirror 13, and the beam that passes through there is a photodetecting lens. The incident light to the photodetector 16 via (15) and the right-reflected beam from the half mirror 13 'enters another photodetector 16' via the photodetector lens 15 '. Once light is incident, a current is applied to the electromagnet coil 18 to generate a magnetic field, and recording is performed by reversing the existing magnetic field. The photodetecting lens 15 is for tracking control and the photodetecting lens 15 'is for focusing control.

On the other hand, the laser beam backward oscillated by the erasing light source 11 'of the erasing magnetic and optical head 10' is detected by the output detecting photoelectric conversion element 12, and the forward oscillating laser beam is a collimator lens ( 17 '), the half mirror 13 " and the objective lens 14' enter the optical disk 20 and the beam reflected from the optical disk 20 passes through the objective lens 14 'half mirror 13 " The beam incident on the mirror 13 '"and transmitted straight therein is incident on the photodetector 16" via the photodetector lens 15' "and left-failed in the half mirror 13 '". The beam is incident on the photodetector 16 '"via the photodetecting lens 15".

The erasing light source 11 'is ahead of the recording light source 11 along the track so that the portion to be rewritten can be erased in advance, and the outputs of the erasing light source 11' and the recording light source 11 are It is in the range of about 15mw-25mw and can be used as a semiconductor laser of 830mm or 780mm. In addition, an output difference between the light sources 11 and 11 'may occur within the output range. The cylindrical permanent magnet 18 'configured to have the pole surface of the N pole / S pole parallel to the optical disk surface can change the magnetic field applied pole as needed based on the rotation axis 19 of the cylinder. Magnetic field strength should be over 500 Oe.

As described above, the present invention can be connected to a computer or the like by erasing and rewriting the information at about the same time, so that the output of the light source for recording, reproducing, erasing, and rewriting can be checked and controlled to stabilize the output. In addition, the use of the erased magnetic field as a permanent magnet has the advantage of reducing the material cost and energy.

Claims (4)

In the magnetic and optical head for a magneto-optical disk driver, an erasing magnetic optical head 10 'and a recording magnetic and optical head 10 are provided to be positioned back and forth along the track of the optical disk 20, and the head 10 '10' is a half mirror 13 " after the laser beam, which is oscillated by the erasing light source 11 'and the recording light source 11, which are semiconductor lasers, passes through collimator lenses 17' and 17, respectively. The beam passing straight at 13 enters the objective lens 14 'and 14 and is incident on the optical disk 20 and the beam reflected at the optical disk 20 is the objective lens 14' and 14, the half mirror 13 A beam incident on the half mirrors 13 '" 13 ' via the " 13 " and passing straight therethrough passes through a photodetector (15' ") 15 for tracking control. 16 " and 16 ", as well as being reflected in half mirror 13 " ", 13 ', beams are passed through another photodetector (15 " and 15 ') for optical focusing control. 16 '") and 16', respectively, Magnet 18 'and the magneto-optical disk driver and a magnetic-optical head according to the features that are configured such that each of erasing and recording performed by the electromagnet coil 18. A photoelectric conversion element (12 ') (12) for detecting the output of a laser beam oscillated backwards thereon is provided behind the light sources (11') (11) of the head (10 ') (10). Magnetic and optical heads for magneto-optical disk drivers, characterized in that installed. 2. The magnetic and optical head for a magneto-optical disk driver according to claim 1, wherein the permanent magnet (18 ') of the erasing magnetic head is cylindrical and provided rotatably with respect to the central axis (19). The magnet and optical head for a magneto-optical disk driver according to claim 1, wherein the permanent magnet (18 ') is made of a magnetic material having a magnetic field strength of 500 Oe or more.

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