摘要:
An optical disk has a lead-in region provided at the inner circumference side and a user region provided at the outer circumference side. Pit string 3 of pits of different depths-is-formed-in-the-lead-in-region. Light beam reflected from the pit string is detected by detector and TPP and RF signals are output by differential amplifier and addition amplifier. A ternary signal is restored from pits based on the TPP and RF signals. Information is recorded by pits of the same depth in the user region. Recording information in the depth direction in the lead-in region increases the recording capacity thereof The information recorded in the depth direction in the lead-in region cannot be transferred to a user region of another optical disk.
摘要:
An optical disk has a lead-in region provided at the inner circumference side and a user region provided at the outer circumference side. Pit string 3 of pits of different depths is formed in the lead in region. Light beam reflected from the pit string is detected by detector and TPP and RF signals are output by differential amplifier and addition amplifier. A ternary signal is restored from pits based on the TPP and RF signals. Information is recorded by pits of the same depth in the user region. Recording information in the depth direction in the lead-in region increases the recording capacity thereof. The information recorded in the depth direction in the lead-in region cannot be transferred to a user region of another optical disk.
摘要:
An optical disk has a lead-in region provided at the inner circumference side and a user region provided at the outer circumference side. Pit string 3 of pits of different depths is formed in the lead-in region. Light beam reflected from the pit string is detected by detector and TPP and RF signals are output by differential amplifier and addition amplifier. A ternary signal is restored from pits based on the TPP and RF signals. Information is recorded by pits of the same depth in the user region. Recording information in the depth direction in the lead-in region increases the recording capacity thereof. The information recorded in the depth direction in the lead-in region cannot be transferred to a user region of another optical disk.
摘要:
On an optical disk, a string of a plurality of pits having two different depths is formed. Quantity of light reflected from the pit string is detected by a photoreceptor element, and based on the detected quantity of reflected light, a pit depth detecting unit detects depth of each pit. Based on the detected quantity of reflected light, a servo signal generating unit generates a tracking servo signal. An output control unit supplies the generated tracking servo signal when a pit of such depth that is to be reproduced is tracked, and holds and supplies an immediately preceding tracking servo signal when a pit of different depth is being tracked, based on the result of detection by the pit depth detecting unit.
摘要:
A magneto-optical recording medium is composed of a base which has a property that a light can be transmitted therethrough, a readout layer formed on the base, which has in-plane magnetization at room temperature, whereas, a transition occurs from in-plane magnetization to perpendicular magnetization as the temperature thereof is raised and a recording layer formed on the readout layer for recording information magneto-optically. A recording and reproducing method and the optical head are designed for the magneto-optical recording medium. By the recording and reproducing method using the optical head, information recorded at high density can be reproduced.
摘要:
A magneto-optical recording medium is arranged so that (1) a first transparent dielectric layer, (2) a reproduction layer showing in-plane magnetization at room temperature while showing perpendicular magnetization in response to temperature rise, (3) a second transparent dielectric layer, (4) a recording layer made of perpendicular magnetization film; and (5) a protective layer are laminated on a substrate in this order. The reproduction layer has a thickness of 5 nm to 30 nm, the second transparent dielectric layer has a thickness of 6 nm to 40 nm, and the recording layer has a thickness of 20 nm to 80 nm. It is possible to separately reproduce individual recording bit even when one or more adjacent recording bits exist within the diameter of the light beam converged onto a target recording bit. This is because the information of a recording magnetic domain of a portion showing in-plane magnetization is masked.
摘要:
A magneto-optical recording medium has a recording layer whereon information is magneto-optically recorded. A readout layer is provided on the recording layer. The readout layer has a compensating temperature that is located between room temperature and the Curie temperature. In the readout layer, upon an application of a light beam, the in-plane magnetization occurs at room temperature and a transition from the in-plane magnetization to vertical magnetization occurs as the temperature of the irradiated area of the readout layer rises above a predetermined temperature. By employing this magneto-optical recording medium, with an application of a light beam that is intensity modulated into two levels, only a spot having a temperature not less than a predetermined temperature is involved in the reproduction; therefore, a recorded bit with a size smaller than the diameter of the light beam can be reproduced, thereby greatly increasing the recording density. Further, the level of the reproduced signals is increased, and crosstalk from the adjoining tracks is reduced; thus, information recording and overwriting can be conducted more easily.
摘要:
A magneto-optical disk has a recording layer whereon recorded bits are formed by the magnetic field modulation method and a readout layer whose axis of easy magnetization is parallel to the recording layer at room temperature, and varies to be perpendicular to the recording layer within a predetermined temperature range between room temperature and the Curie temperature. During reproduction of the recorded bits the first semiconductor laser emits a heating-use light beam to form the first light spot on the readout layer Thus, a ring-shaped region corresponding to the predetermined temperature range exhibits perpendicular magnetic anisotropy and the recorded bits are copied from the recording layer onto the ring-shaped region. As the first light spot is shifted, the ring-shaped region as a readout window of recorded bits is also shifted. Further, the second semiconductor laser emits a reproduction-use light beam such that the second light spot is formed on the readout layer to overlap the first light spot at a rear portion thereof. Consequently, only one recorded bit copied onto the rear portion of the ring-shaped region can be reproduced; therefore, high-quality reproduced signals can be obtained from the magneto-optical disk having information recorded with high density.
摘要:
A magneto-optical storage device having a configuration wherein a first AlN film, a Pt/co multi-layer film formed by alternately depositing Pt and Co, a second AlN film, and an Al reflective film are successively laminated on a substrate in this order. Assuming that respectively the thickness of the first AlN film is .delta.AlN (1); that of the second AlN film is .delta.AlN (2); that of the Pt single layer is .delta.Pt; that of the Co single layer is .delta.Co; and the total thickness of the Pt/Co multi-layer film is .delta.Pt/Co, each thickness of those layers is set to range within: 50 nm .ltoreq..delta.AlN (1).ltoreq.200 nm; 120 nm.ltoreq..delta.AlN (2).ltoreq.140 nm; 0.6 nm.ltoreq..delta.Pt.ltoreq.1.0 nm; 0.3 nm.ltoreq..delta.Co.ltoreq.0.6 nm; and 15 nm.ltoreq..delta.Pt/Co.ltoreq.20 nm. In accordance with the above arrangement, it is possible to greatly widen the tolerances of the film thicknesses of the first and second dielectric layers for obtaining a predetermined reflective index as well as a maximum Kerr rotation angle. Consequently, without strictly controlling the film thicknesses of the first and second AlN films, a magneto-optical storage device with stable performance suitable for practical use can be produced easily.
摘要:
A magneto-optical recording medium comprising a readout layer and a recording layer has a relationship that an external magnetic field H1 is smaller than an external magnetic field H4, where the H1 is a minimum external magnetic field necessary to make a magnetization direction of the readout layer direct to the direction reverse to a magnetization direction of the recording layer substantially at the room temperature, and the H4 is a maximum external magnetic field necessary to make the magnetization direction of the readout layer direct to the direction same as the magnetization direction of the recording layer at an high temperature not lower than a predetermined temperature. Moreover, the magneto-optical disk is provided, between the readout layer and the recording layer, with an intermediate layer which inhibits an effective bias magnetic field from the recording layer to the readout layer at the room temperature. Since it is possible to reproduce only the information in the high-temperature area close to the center of the laser beam irradiated during reproducing, recording density is improved. Furthermore, since an initializing magnetic field at reproducing is not necessary and the reproducing magnetic field can be made smaller, the apparatus can be made smaller and the electric power consumption can be decreased.