Photomagnetic disc device

[Detailed Description of the Invention]

+ The technical field of a invention The present invention relates to optical-magnetic disc equipment, and relates to the bias magnetic field impressing device of the optical-magnetic disc equipment which makes phase connection and performs elimination, record, and reproduction in more detail. (The background of bl art) With improvement in the speed and large-scale-izing of an electronic computer, the memory storage which is the principal part is also high-density increasingly, and to large-scale-ize is demanded. Although magnetic storage devices u, such as a magnetic disk with easy magnetic record playback, occupy the mainstream, the optical disc which performs record playback of information optically can obtain storage density higher a single figure than the present magnetic disk theoretically, especially is beginning to be used for record playback of an image now. The magneto-optical disc which eliminates information and can carry out repetitive record playback is on the character of the recording medium, It has the storage density markedly higher than a magnetic disk as an amount storage of patents frequently characterized by rewriting, and is observed as a recording medium which can carry out snow of about the same low A bit cost as magnetic tape to about the same access time as a magnetic disk. tc) Conventional technology and problem The magneto-optical recording method developed now is what is called the heat mode recording method that makes laser beams a heat source also like the light-and-heat magnetism recording method. As shown in the characteristic line figure of coercive force 11c of a magnetooptical medium and curie temperature Tc as shown in Drawing 1, the writing of magneto-optical recording is performed using a rapid change of coercive force Hc in near curie temperature Tc of a magneto-optical disc medium. Namely, Drawing 2 (when it is magnetized in the direction of an upward arrow and optical magnetic media layer 2 on substrate 1 is placed in external magnetic field H of the direction of a downward arrow like al.) If laser beams 3 are condensed with lens 4 like 2nd [ The ] figure fbl and it irradiates with the magnetic media layer 2 concerned by spot image 5, When the temperature of the irradiated plane rises and coercive force Hc of the portion concerned falls below in a record magnetic field (sum of an external magnetic field and a demagnetizing field), magnetization is reversed and it is Drawing 2 (as shown in C1, a cylindrical magnetic domain is recorded.). This process is changes of a magnetic state, and since it does not need any thermal energy, it has the strong point in which record sensitivity is also high. It is obvious to reverse the direction of external magnetic field H for elimination of information, and to irradiate with the record part of the magnetooptical medium concerned with laser beams. When making optical magnetic media layer 2 penetrate and making reproduction of information storage Faraday effect 2 anti-A laser beams, the optical magnetic effect of a Kerr effect is used for it. It is based on the method of light polarizer detecting rotation of the plane of polarization of the projection laser beams by magnetization, and reading information. Since this rotation angle is an about 0.3-degree delicate thing. Efforts are paid to improvement in a signal noise ratio. Drawing 3 is a figure showing the conventional composition of the optical-magnetic disc equipment as optical information storage playback equipment. The laser beams carried out Depart A1 [ semiconductor laser / 6 ] in the figure are Collimating Les, It becomes parallel laser optical beam 9 which has a circle section through An 7. perfect circle Fairness prism 8, and linear polarization is carried out with light polarizer 10, and through beam splitter 111 reflector 12, it enters into object lens 13, it is projected on magneto-optical disc 14, and minute spot image 5 is formed. Information is recorded by bias magnetic field H impressed with electromagnet 27 as mentioned above at this time. The light reflected by magneto-optical disc 14 among laser optical beams 9 which entered through the same Optical path as the above-mentioned at the time of playback is separated from incidence light by the above-mentioned beam splitter 11, and catoptric light 15 separated five times is separated into the object for information playback, and Zabo signals by 2nd Beams brick 16. Laser optical beam 15a which penetrated Chi and heme Sprigota 16 immediately is divided by reflector 17 which served as the mask. After entering into condenser 18, it is projected by 2 division optical power detector 20, and a focal error signal is acquired from the difference of 2 division optical power detector 20. Similarly it is projected on laser optical beam 15a which was reflected in another side 9 reflector 17, and entered into condenser 19 by 2 division optical power detector 21, and a tracking signal is acquired as difference. After passing light analysis child 22 for detecting change of the plane of polarization, it is condensed with condenser 23, laser optical beam 15b for signal regeneration reflected by beam splitter 16 enters into optical power detector 24, and photoelectric conversion is carried out to an electric signal from a lightwave signal. Here, information is read as rotation of the plane of polarization by the reversal magnetizing part of optical magnetic media layer 2 of magneto-optical disc I4. Elimination of information reverses bias magnetic field 1] as mentioned above, and should just project laser (turning upward in figure) optical beam 9 on the 14th page of a magneto-optical disc continuously. After eliminating, placing and recording information beforehand for recording on magneto-optical disc 14, usually is reproduced and checks record 111# news. Although it is possible to perform elimination, record, and playback individually in the optical-magnetic disc equipment of composition of to have explained previously, of course, since an optical system and the direction of a bias magnetic field need to be switched and rotation of magneto-optical disc 14 is needed for the change of every each time, the rapidity of record playback falls remarkably. In order to compensate Re, it is kneading which should just be provided with the same optical system and bias magnetic field impressing device, but generation of heat of a bias coil increases, and the control timing of a change, etc. become complicated. It looked forward to a certain measure at the To sake which W Erases this problem. (The object of di invention) The present invention was made in view of the above-mentioned point, and tends to constitute the bias magnetic field impressing device which is needed in order to make phase connection and to perform elimination of optical-magnetic disc equipment, record, and reproduction from a single magnet. (Constitution of Ql invention) the object of the above-mentioned invention -- light sources, such as a semiconductor laser, The Linear polarization(ed) optical beam is condensed with the optical lens by which position control was carried out by the focusing actuator. It has a tracking actuator which guides two optical systems and the above-mentioned light spot of A and B which project the light spot on a magneto-optical disc on the predetermined track of the above-mentioned magneto-optical disc, Information was eliminated by the light spot and the bias magnetic field which it resembled to the optical system and on which it was projected more, and it was projected by the above-mentioned optical system B. It is elimination of information by recording information by light spot and a bias magnetic field, detecting the catoptric light from the above-mentioned magneto-optical disc simultaneously, and playing information. In the optical information storage playback equipment which phase connection is made and can perform record and reproduction, It is easily attained by using as a component the electromagnet or permanent magnet of car - which has sm pole face and N magnetic pole side which the magnetic field impression device which impresses the bias magnetic field of the mutually opposite direction corresponding to the above-mentioned optical system B to the above-mentioned optical system turned to in the same direction, and was provided with the character type magnetic core. (The example of fl invention) With reference to drawings, it explains per example of the present invention below. Drawing 4 is a lineblock diagram shown again typically for comparison of the optical system of the conventional optical-magnetic disc equipment explained in Drawing 3, and the composition of a bias magnetic field impressing device. In a figure, R shows the optical circuit for taking the control signal of a tracking actuator and a focusing actuator. On the other hand, Drawing 5 is a lineblock diagram showing typically one example of optical-magnetic disc equipment based on the present invention in a similar manner. In this example, the optical system comprises two lines, A and B. Optical system A is used for elimination of information, and the Wrede semiconductor 31 is a light source, a laser optical beam should pass collimating lens 32 (a perfect circle amendment prism is included) as well as the conventional example -- it becomes parallel laser optical beam 31b, and connects light spot 5e to optical magnetic media layer 2 with object lens 35 through beam sprinter 33*2 wavelength plate 34. the catoptric light from optical magnetic media layer 2 returns to object lens 35.z wavelength plate 34 -- beam splitter 33 -- reflection -- it becomes * Re and optical beam R1, and is used for the control signal of the tracking actuator of object lens 35, and a focusing actuator. As for optical system B, it becomes a parallel optical beam with collimating lens 38, and is reflected with filter 39, and laser optical beam 37b which is reproduced by having recorded and followed elimination by optical system A succeedingly, and came out of semiconductor laser 37 is a passage about light polarizer 40. beam splitter 41. Light spot 5 Hata is connected on the surface of optical magnetic media layer 2 with object lens 42. The catoptric light beam from optical magnetic media layer 2 is reflected with back filter 45 which returned to object lens 42 and was reflected by one beam splitter 41. Semiconductor laser 43 is a light source for reproduction, and laser optical beam 43b turns into a parallel optical beam with collimating lens 44, and after it penetrates filter 39, it connects light spot 5r to optical magnetic media layer 2 with 9 object lenses 42 through light polarizer 40 and beam sprinter 41. Receive and object lens 42 are returned in rotation of the plane of polarization which Suitableed in the magnetic domain which polarity reversed by recording operation according to the Kerr effect, it is reflected by beam splitter 41, and laser optical beam 43b reflected in this optical magnetic media layer 2 penetrates filter 45, and is equally divided into two by half mirror 46. Light analysis child 47 is passed, one of these reaches optical power detector 48, and photoelectric conversion processing is carried out and it is changed into an electric signal. It is used for control of the focusing actuator of laser optical beam R2 An objective lens 42 of another side, and 1-ranking actuator. light spot 5w for the above-mentioned record and light spot 5r for reproduction adjust the optic axis of optical system B -- about 10 micrometers -- When -- it can image in the mutually distant position. therefore, it arranges on one track in order of elimination, record, and playback at hand-of-cut Direction of cut line shown by the arrow of target magneto-optical disc 14 -- it can carry out for * obtaining. As above-mentioned, although a bias magnetic field is needed for the projecting point of light spot 5e concerned and 5- at elimination and record of magneto-optical disc 14, the direction of a magnetic field of 1 both is an opposite direction mutually. In this example, both the above-mentioned magnetic fields are impressed with the bias magnetic field impressing device which comprised electromagnet 51 consisting of magnetic core 59 which carried out U character type, and magnetization coil 50 wound around this, and a yoke which is not illustrated. N magnetic pole side 52N and S magnetic pole side 52S have turned to the same direction, and it has countered the optical system of the above-mentioned laser optical beam from curvature and 1 side at magneto-optical disc 14. Since the direction of the bias magnetic field to elimination and record is being fixed in the optical-magnetic disc equipment based on the present invention, respectively and reversal of the magnetization direction is not required. A permanent magnet can also be used instead of the above-mentioned electromagnet 51, and there is an advantage of not being accompanied by generation of heat at all in this case. It is not necessary to make so small the gap of a magnetic pole side and a magnetic-disk side from the object of length which only impresses a bias magnetic field, and it has become one of the points which were very excellent as compared with the magnetic disk. Drawing 6 is time Char1- which shows the temporal relationship of operation of one example of the present invention stated above. Each horizontal axis is Drawing 6 (a+ is the amount of laser optical beams of semiconductor laser 31 for elimination, and Drawing 6 (the amount of laser optical beams of semiconductor laser 37 for bl Record.)), although time is shown. Drawing 6 (C) shows the amount of Wrede optical beams of semiconductor laser 43 for reproduction, respectively, and 6th [ The ] figure fdl shows the exciting current of magnetization coil 50 of a bias magnetic field impressing device. It is continuously projected on laser optical beam 43b for playback by magneto-optical disc 14 with the 1/several about low value of the object for elimination, and laser optical beams 31b and 37b for record. Although the focusing actuator of the above-mentioned object lenses 35 and 42 needs to operate independently mutually, a tolan king actuator can also be used common to both object lenses. (The effect of gl invention) Ming et al. from the above explanation -- it is - adopting the optical-magnetic disc equipment which is provided with the bias magnetic field impressing device based on the 9 present invention for obtaining, and has an optical system of the object for elimination, record, and two laser optical beams for reproduction. Operation is possible, without being accompanied by large generation of heat only with one magnet, and the operating ratio is improved by supposing that it is possible to make phase connection of elimination, record, and the playback operation, and to perform a magneto-optical disc simultaneously at the time of the same rotation, and it is .. It is effective in the ability to constitute the memory storage of high-speed input and output.

[Brief Description of the Drawings]

Drawings 2 are a diagram in which Drawing 1 shows the temperature characteristics of coercive force Hc of optical magnetic media, and an explanatory view showing the principle of the information storage of a magneto-optical disc, The lineblock diagram in which Drawing 3 shows the composition of one example of optical-magnetic disc equipment based on the present invention in the lineblock diagram of optical-magnetic disc equipment, the mimetic diagram showing typically the composition of the optical-magnetic disc equipment of the former [ Drawing / 4 ], and Drawing 5, and Drawing 6 are time charts which show the temporal relationship of operation of each part of the example. As for Lons and 5, in laser beams and 4, in a figure, a light spot image, 6, and 3L37.43 are [ 11 / the substrate of a magneto-optical disc and 2 / an optical magnetic media layer and 3 ] semiconductor lasers. 7.32, 38.44 The collimating Lance, and 8 are perfect circle amendment Flismism, As for 9, 15, 15b, 31b, 37b, and 43b, a laser optical beam and 10.40 are light polarizers, IL As for a heme splitter and 12, in 16.41, a reflector, 13, and 35.42 are object Lons, the reflector in which, as for 14, a magneto-optical disc and 17.46 served as the mask, 18, and 19.23 -- condensing Lons and 20.21 -- 2 division optical power detector and 22.47 -- a light analysis child and 24.48 -- an optical power detector and 34 -- x wavelength plate and 2.9.49 -- a magnetic core and 28.50 -- a magnetization coil. As for 27 and 51, a filter and 46 show a magnetic pole side an electromagnet and 39.45, respectively, as for half mirror 952. Drawing 1 Drawing 2 IC T->