EP0352104A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Magneto-optical memory apparatus and optical memory apparatus
Assignee: Sharp Corp
•
Filing: 1989-07-20
•
Granted: —
•
Expires: 2009-07-20
Abstract
Abstract The present invention discloses a magneto-optical memory apparatus comprising: an optical head; a magneto-optical recording medium relatively movable with respect to the optical head, into which recording marks, each having two ends, are recorded as information; the optical head being arranged such that, (i) at the time of recording into the magneto-optical recording medium, the recording marks are recorded such that the ends of each recording mark correspond to a second code of digital information composed of two different types of codes, (ii) at the time of reproduction, a light beam having a condensing spot is projected to the magneto-optical recording medium and, when a reproduction light containing reproduction information is entered to the optical head from the magneto-optical recording medium, a reproduction signal is supplied, and (iii) when the light beam is projected to a recording mark, an information pulse corresponding to the second code is generated in the reproduction signal, only when the reproduction light from the recording mark interferes with the reproduction light from the non-marking part; and a signal detector circuit for detecting the information pulse in the reproduction signal obtained from the optical head and for converting the reproduction signal into a digital reproduction signal. Each of the recording marks contains a number of information to enhance the recording density of the magneto-optical recording medium, thereby to increase the recording capacity. Further, the recording marks may be made in a large size and in a suitable shape. This facilitates the transfer of the recording marks made by plastic forming and the like. Futher, the optical system may be simplified in arrangement. The optical memory apparatus in accordance with the present invention includes the arrangement above-mentioned and is so arranged as to reproduce the recorded information by diffraction of the lights reflected from the optical information recording medium having recording marks formed therein.
Inventors
- 👤 Hiroshi Fuji
- 👤 Toshihisa Deguchi
- 👤 Kunio Kojima
- 👤 Takeshi Yamaguchi
- 👤 Shigeo Terashima
- 👤 Akira Takahashi
- 👤 Kenji Ohta
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 15:02
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/2407; G11B7/24085; G11B11/00; G11B11/10; G11B11/105; G11B11/10502; G11B11/10504; G11B11/10515; G11B11/10528; G11B13/00; G11B13/04; G11B7/004; G11B7/0045; G11B7/005; G11B7/007; G11B7/013
Claims Analysis
Total Claims: 41
Claim 1
Independent Claim
207 words
A magneto-optical memory apparatus comprising: an optical head; a magneto-optical recording medium relatively movable with respect to said optical head, into which recording marks, each having two ends, are recorded as information; said optical head being arranged such that, (i) at the time of recording into said magneto-optical recording medium, said recording marks are recorded by inverting the magnetization direction of said magneto-optical recording medium, such that the ends of each recording mark correspond to a second code of digital information composed of two different types of codes, (ii) at the time of reproduction, a light beam having a condensing spot is projected to said magneto-optical recording medium, and a reproduction signal is supplied when a reproduction light containing reproduction information is entered into said optical head from said magneto-optical recording medium, and (iii) when said light beam is projected to a recording mark, an information pulse corresponding to said second code is generated in said reproduction signal, only when the reproduction light from the recording mark inter feres with the reproduction light from the non-marking part; and a signal detector circuit for detecting said information pulse of said reproduction signal obtained from said optical head and for converting said reproduction signal into a digital reproduction signal.
Claim 2
Dependent Claim
207 words
A magneto-optical memory apparatus comprising: an optical head; a magneto-optical recording medium relatively movable with respect to said optical head, into which recording marks, each having two ends, are recorded as information; said optical head being arranged such that, (i) at the time of recording into said magneto-optical recording medium, said recording marks are recorded by inverting the magnetization direction of said magneto-optical recording medium, such that the ends of each recording mark correspond to a second code of digital information composed of two different types of codes, (ii) at the time of reproduction, a light beam having a condensing spot is projected to said magneto-optical recording medium, and a reproduction signal is supplied when a reproduction light containing reproduction information is entered into said optical head from said magneto-optical recording medium, and (iii) when said light beam is projected to a recording mark, an information pulse corresponding to said second code is generated in said reproduction signal, only when the reproduction light from the recording mark inter feres with the reproduction light from the non-marking part; and a signal detector circuit for detecting said information pulse of said reproduction signal obtained from said optical head and for converting said reproduction signal into a digital reproduction signal.
Claim 3
Dependent Claim
56 words
A magneto-optical memory apparatus as set forth in Claim 1, wherein the signal detector circuit includes a peak position detector circuit for detecting the peak positions of information pulses in the reproduction signal and/or an amplitude detector circuit for detecting the width and interval of information pulses having a level not greater than a reference value.
Claim 4
Dependent Claim
367 words
A magneto-optical memory apparatus comprising: an optical head; a magneto-optical recording medium relatively movable with respect to said optical head, into which first and second recording marks are recorded as information; said optical head being arranged such that, (i) at the time of recording to said magneto-optical recording medium, said first and second recording marks are recorded by inverting the magnetization direction of said magneto-optical recording medium, such that the ends thereof in the relative moving direction with respect to said optical head, correspond to a second code of digital information composed of two different types of codes, (ii) each of said second recording marks is recorded in a width smaller than that of each of said first recording marks such that the part between both ends of each second recording mark corresponds to said second code, (iii) at the time of reproduction, a light beam having a condensing spot having a diameter smaller than the width of each first recording mark and greater than the width of each second recording mark, is projected to said magneto-optical recording medium, (iv) upon reception of a reproduction light containing reproduction information from said magneto-optical recording medium, a reproduction signal is supplied, and only at the time of reception of the reproduction light generated by irradiation of a light beam to an end of a first or second recording mark, an information pulse corresponding to said second code is generated in said reproduction signal due to interference of the reproduction light from the first or second recording mark with the reproduction light from the non-marking part, and (v) when said light beam is projected to the part between both ends of a second recording mark, there is supplied a reproduction signal having a level lower than a reference value due to interference of the reproduction light from said second recording mark with the reproduction light from the non-marking part; and a signal detector circuit for detecting, as said second code, (i) the information pulses of the reproduction signal obtained from said optical head and (ii) the parts between information pulses having a level not greater than the reference value, and for converting said reproduction signal into a digital reproduction signal.
Claim 5
Dependent Claim
367 words
A magneto-optical memory apparatus comprising: an optical head; a magneto-optical recording medium relatively movable with respect to said optical head, into which first and second recording marks are recorded as information; said optical head being arranged such that, (i) at the time of recording to said magneto-optical recording medium, said first and second recording marks are recorded by inverting the magnetization direction of said magneto-optical recording medium, such that the ends thereof in the relative moving direction with respect to said optical head, correspond to a second code of digital information composed of two different types of codes, (ii) each of said second recording marks is recorded in a width smaller than that of each of said first recording marks such that the part between both ends of each second recording mark corresponds to said second code, (iii) at the time of reproduction, a light beam having a condensing spot having a diameter smaller than the width of each first recording mark and greater than the width of each second recording mark, is projected to said magneto-optical recording medium, (iv) upon reception of a reproduction light containing reproduction information from said magneto-optical recording medium, a reproduction signal is supplied, and only at the time of reception of the reproduction light generated by irradiation of a light beam to an end of a first or second recording mark, an information pulse corresponding to said second code is generated in said reproduction signal due to interference of the reproduction light from the first or second recording mark with the reproduction light from the non-marking part, and (v) when said light beam is projected to the part between both ends of a second recording mark, there is supplied a reproduction signal having a level lower than a reference value due to interference of the reproduction light from said second recording mark with the reproduction light from the non-marking part; and a signal detector circuit for detecting, as said second code, (i) the information pulses of the reproduction signal obtained from said optical head and (ii) the parts between information pulses having a level not greater than the reference value, and for converting said reproduction signal into a digital reproduction signal.
Claim 6
Dependent Claim
77 words
A magneto-optical memory apparatus as set forth in Claim 3, wherein the magneto-optical recording medium is made of plastic or glass formed in the shape of a disk or a card, and provided with a magnetic thin film having a magnetization facilitating axis in a direction at a right angle to the surface thereof, said magneto-optical recording medium being arranged such that the recording marks as information are recorded and erased by inversion of the magnetization direction.
Claim 7
Dependent Claim
49 words
A magneto-optical memory apparatus as set forth in Claim 3, wherein the optical head includes a polarization beam splitter to reduce the number of component elements of the optical system, and is arranged such that the detection polarization plane is at a right angle to the incident polarization plane.
Claim 8
Dependent Claim
85 words
A magneto-optical memory apparatus as set forth in Claim 3, wherein the magneto-optical recording medium is arranged such that each of the first recording mark is made in the form of an ellipse of which length and width are greater than the diameter of a condensing spot of a laser light used at the time of reproduction, and that each of the second recording mark has a length greater than the diameter of said condensing spot, thereby to facilitate the generation of the information pulses.
Claim 9
Dependent Claim
56 words
A magneto-optical memory apparatus as set forth in Claim 3, wherein the signal detector circuit includes a peak position detector circuit for detecting the peak positions of information pulses of the reproduction signal and an amplitude detector circuit for detecting the width and interval of information pulses having a level not greater than a reference value.
Claim 10
Dependent Claim
206 words
A magneto-optical memory apparatus comprising: an optical head; and a magneto-optical recording medium relatively movable with respect to the optical head, into which recording marks as information are recorded; said optical head having (i) an optical system unit for supplying inteference lights, in opposite phases, respectively obtained from the reproduction light from a recording mark as irradiated by a light beam and the reproduction light from the non-marking part, and (ii) a photo detector for converting the incident lights into electric signals, each having a level corresponding to the amount of each of said incident lights; said optical head being arranged such that, (i) at the time of recording into said magneto-optical recording medium, recording marks corresponding to a second code of digital information composed of two different types of codes, are recorded by inverting the magnetization direction of said magneto-optical recording medium; (ii) at the time of reproduction, a light beam having a condensing spot having a diameter greater than the width of each recording mark, is projected to said magneto-optical recording medium, from which supplied is a reproduction light containing reproduction information, and (iii) the inteference lights obtained from said reproduction lights are supplied to said photo detector, which then supplies a reproduction signal.
Claim 11
Dependent Claim
206 words
A magneto-optical memory apparatus comprising: an optical head; and a magneto-optical recording medium relatively movable with respect to the optical head, into which recording marks as information are recorded; said optical head having (i) an optical system unit for supplying inteference lights, in opposite phases, respectively obtained from the reproduction light from a recording mark as irradiated by a light beam and the reproduction light from the non-marking part, and (ii) a photo detector for converting the incident lights into electric signals, each having a level corresponding to the amount of each of said incident lights; said optical head being arranged such that, (i) at the time of recording into said magneto-optical recording medium, recording marks corresponding to a second code of digital information composed of two different types of codes, are recorded by inverting the magnetization direction of said magneto-optical recording medium; (ii) at the time of reproduction, a light beam having a condensing spot having a diameter greater than the width of each recording mark, is projected to said magneto-optical recording medium, from which supplied is a reproduction light containing reproduction information, and (iii) the inteference lights obtained from said reproduction lights are supplied to said photo detector, which then supplies a reproduction signal.
Claim 12
Dependent Claim
54 words
A magneto-optical memory apparatus as set forth in Claim 8, wherein the optical system unit is so arranged as to detect a decrease in the amount of received light resulting from interference of the reproduction light from a recording mark as irradiated by a light beam, with the reproduction light from the non-marking part.
Claim 13
Dependent Claim
50 words
A magneto-optical memory apparatus as set forth in Claim 8, wherein the optical system unit includes a polarization beam splitter to reduce the number of component elements of the optical system, and is arranged such that the detection polarization plane is at a right angle to the incident polarization plane.
Claim 14
Dependent Claim
60 words
A magneto-optical memory apparatus as set forth in Claim 8, wherein the optical head is arranged such that, at the time of reproduction, a condensing spot having a diameter greater than the width of each recording mark of the magneto-optical recording medium, is projected to said magneto-optical recording medium, and that the reflected light as a reproduction light is generated.
Claim 15
Dependent Claim
77 words
A magneto-optical memory apparatus as set forth in Claim 8, wherein the magneto-optical recording medium is made of plastic or glass formed in the shape of a disk or a card, and provided with a magnetic thin film having a magnetization facilitating axis in a direction at a right angle to the surface thereof, said magneto-optical recording medium being adapted such that the recording marks as information are recorded and erased by inversion of the magnetization direction.
Claim 16
Dependent Claim
239 words
A magneto-optical memory apparatus comprising: an optical head; a magneto-optical recording medium relatively movable with respect to said optical head, into which recording marks as information are recorded; said optical head being arranged such that, (i) at the time of recording into said magneto-optical recording medium, said recording marks are recorded by inverting the magnetization direction of said magneto-optical recording medium, such that the ends thereof in the relative moving direction with respect to said optical head, correspond to a second code sandwiched in between two first codes of digital information composed of two different types of codes, and (ii) at the time of reproduction, a light beam having a condensing spot having a diameter not greater than the width of each recording mark, is projected to said magneto-optical recording medium, and a reproduction signal is supplied upon reception of a reproduction light containing reproduction information from said magneto-optical recording medium, and an information pulse corresponding to said second code is generated in said reproduction signal due to interference of the reproduction light from a recording mark with the reproduction light from the non-marking part upon reception of the reproduction light generated when an end of the recording mark is irradiated by said light beam; and a signal detector circuit for detecting, as said second code, said information pulse in said reproduction signal obtained from said opticl head and for converting said reproduction signal into a digital reproduction signal.
Claim 17
Dependent Claim
239 words
A magneto-optical memory apparatus comprising: an optical head; a magneto-optical recording medium relatively movable with respect to said optical head, into which recording marks as information are recorded; said optical head being arranged such that, (i) at the time of recording into said magneto-optical recording medium, said recording marks are recorded by inverting the magnetization direction of said magneto-optical recording medium, such that the ends thereof in the relative moving direction with respect to said optical head, correspond to a second code sandwiched in between two first codes of digital information composed of two different types of codes, and (ii) at the time of reproduction, a light beam having a condensing spot having a diameter not greater than the width of each recording mark, is projected to said magneto-optical recording medium, and a reproduction signal is supplied upon reception of a reproduction light containing reproduction information from said magneto-optical recording medium, and an information pulse corresponding to said second code is generated in said reproduction signal due to interference of the reproduction light from a recording mark with the reproduction light from the non-marking part upon reception of the reproduction light generated when an end of the recording mark is irradiated by said light beam; and a signal detector circuit for detecting, as said second code, said information pulse in said reproduction signal obtained from said opticl head and for converting said reproduction signal into a digital reproduction signal.
Claim 18
Dependent Claim
77 words
A magneto-optical memory apparatus as set forth in Claim 13, wherein the magneto-optical recording medium is made of plastic or glass formed in the shape of a disk or a card, and provided with a magnetic thin film having a magnetization facilitating axis in a direction at a right angle to the surface thereof, said magneto-optical recording medium being adapted such that the recording marks as information are recorded and erased by inversion of the magnetization direction.
Claim 19
Dependent Claim
61 words
A magneto-optical memory apparatus as set forth in Claim 13, wherein the magneto-optical recording medium is arranged such that each of the recoridng marks is made in the form of an ellipse of which length and width are greater than the diameter of a condensing spot used at the time of reproduction, thereby to facilitate the generation of the information pulses.
Claim 20
Dependent Claim
54 words
A magneto-optical memory apparatus as set forth in Claim 13, wherein the optical head is arranged such that, when a light beam is projected to an end of a recording mark, the detection polarization plane components of the reflected lights from the recording mark and the non-marking parts, are shifted by 180° in phase.
Claim 21
Dependent Claim
50 words
A magneto-optical memory apparatus as set forth in Claim 13, wherein the optical system unit includes a polarization beam splitter to reduce the number of component elements of the optical system, and is arranged such that the detection polarization plane is at a right angle to the incident polarization plane.
Claim 22
Dependent Claim
56 words
A magneto-optical memory apparatus as set forth in Claim 13, wherein the signal detector circuit includes a peak position detector circuit for detecting the peak positions of information pulses of the reproduction signal, or an amplitude detector circuit for detecting the width and interval of information pulses having a level not greater than a reference value.
Claim 23
Dependent Claim
289 words
A magneto-optical memory apparatus comprising: an optical head having a two-division photo detector; a magneto-optical recording medium relatively movable with respect to said optical head, into which recording marks as information are recorded by inverting the magnetization direction of said magneto-optical recording medium; said magneto-optical recording medium being arranged such that (i) each end of said recording marks in the relative moving direction with respect to said optical head, corresponds to a second code sandwiched in between two first codes of digital information composed of two different types of codes, and (ii) when a light beam from said optical head is projected to an end of a recording mark, the intensity distributions of the reproduction light in said two-division photo detector of said optical head, are asymmetric with each other due to light interference; said optical head being adapted to project a light beam to said magneto-optical recording medium, from which a reproduction light containing reproduction information is entered, said optical head being arranged such that, upon reception of a reproduction light generated at the time a light beam is projected to an end of a recording mark, the intensity distributions in two independent light receiving portions of said two-division photo detector, are asymmetric with each other due to the reproduction lights from the recording mark and the non-marking part; a differential amplifier for supplying a difference signal containing an information pulse corresponding to said second code, based on a difference between electric signals supplied from said light receiving portions of said two-division photo detector; and a signal detector circuit for detecting, as said second code, the information pulse of said difference signal supplied from said differential amplifier and for generating a digital reproduction signal from said difference signal.
Claim 24
Dependent Claim
289 words
A magneto-optical memory apparatus comprising: an optical head having a two-division photo detector; a magneto-optical recording medium relatively movable with respect to said optical head, into which recording marks as information are recorded by inverting the magnetization direction of said magneto-optical recording medium; said magneto-optical recording medium being arranged such that (i) each end of said recording marks in the relative moving direction with respect to said optical head, corresponds to a second code sandwiched in between two first codes of digital information composed of two different types of codes, and (ii) when a light beam from said optical head is projected to an end of a recording mark, the intensity distributions of the reproduction light in said two-division photo detector of said optical head, are asymmetric with each other due to light interference; said optical head being adapted to project a light beam to said magneto-optical recording medium, from which a reproduction light containing reproduction information is entered, said optical head being arranged such that, upon reception of a reproduction light generated at the time a light beam is projected to an end of a recording mark, the intensity distributions in two independent light receiving portions of said two-division photo detector, are asymmetric with each other due to the reproduction lights from the recording mark and the non-marking part; a differential amplifier for supplying a difference signal containing an information pulse corresponding to said second code, based on a difference between electric signals supplied from said light receiving portions of said two-division photo detector; and a signal detector circuit for detecting, as said second code, the information pulse of said difference signal supplied from said differential amplifier and for generating a digital reproduction signal from said difference signal.
Claim 25
Dependent Claim
61 words
A magneto-optical memory apparatus as set forth in Claim 19, wherein the magneto-optical recording medium is arranged such that each of the recording marks is made in the form of an ellipse of which length and width are greater than the diameter of a condensing spot used at the time of reproduction, thereby to facilitate the generation of the information pulses.
Claim 26
Dependent Claim
42 words
A magneto-optical memory apparatus as set forth in Claim 19, wherein the two-division photo detector has two divided light receiving portions and is arranged such that the division direction is identical with the direction of scanning tracks on the magneto-optical recording medium.
Claim 27
Dependent Claim
63 words
A magneto-optical memory apparatus as set forth in Claim 19, wherein the signal detector circuit includes a positive direction detector circuit for detecting a positive-direction information pulse in the information pulse of the difference signal supplied from the differential amplifier, a negative direction detector circuit for detecting a negative-direction information pulse, and an OR-gate for calculating a logical sum of said detector circuits.
Claim 28
Dependent Claim
33 words
A magneto-optical memory apparatus as set forth in Claim 22, wherein the positive direction detector circuit and the negative direction detector circuit include a peak position detector circuit and/or an amplitude detector circuit.
Claim 29
Dependent Claim
77 words
A magneto-optical memory apparatus as set forth in Claim 19, wherein the magneto-optical recording medium is made of plastic or glass formed in the shape of a disk or a card, and provided with a magnetic thin film having a magnetization facilitating axis in a direction at a right angle to the surface thereof, said magneto-optical recording medium being adapted such that the recording marks as information are recorded and erased by inversion of the magnetization direction.
Claim 30
Dependent Claim
56 words
A magneto-optical memory apparatus as set forth in Claim 19, wherein the optical head is arranged such that, when a light beam is projected to an end of a recording mark and the reproduction light is incident on the two-division photo detector, the intensity distributions of a light incident on said two-division photo detector are asymmetric.
Claim 31
Dependent Claim
49 words
A magneto-optical memory apparatus as set forth in Claim 19, wherein the optical head includes a polarization beam splitter to reduce the number of component elements of the optical system, and is arranged such that the detection polarization plane is at a right angle to the incident polarization plane.
Claim 32
Dependent Claim
45 words
A magneto-optical memory apparatus as set forth in Claim 19, wherein the optical head is arranged such that, at the time of reproduction, there is produced a phase shift between the reproduction lights as the reflected lights from a recording mark and a non-marking part.
Claim 33
Dependent Claim
208 words
An optical memory apparatus comprising: an optical information recording medium in which recording marks as information are recorded in the form of physical concavo-convex portions, said recording marks being arranged such that the ends thereof in the relative moving direction with respect to an optical head, correspond to a second code sandwiched in between two first codes of digital information composed of two different types of codes, said optical information recording medium being arranged such that, when a light beam from said optical head is projected to an end of a recording mark, the reflected lights are diffracted due to said concavo-convex portions to decrease the amount of the light incident on said optical head, thereby to generate an information pulse in a reproduction signal supplied from said optical head; said optical head being arranged such that, when said optical head projects a light beam to said optical information recording medium, the reflected light is incident on said optical head to supply a reproduction signal containing an information pulse corresponding to said second code; and a signal detector circuit for detecting, as said second code, said information pulse in said reproduction signal supplied from said optical head, and for converting said reproduction signal into a digital reproduction signal.
Claim 34
Dependent Claim
208 words
An optical memory apparatus comprising: an optical information recording medium in which recording marks as information are recorded in the form of physical concavo-convex portions, said recording marks being arranged such that the ends thereof in the relative moving direction with respect to an optical head, correspond to a second code sandwiched in between two first codes of digital information composed of two different types of codes, said optical information recording medium being arranged such that, when a light beam from said optical head is projected to an end of a recording mark, the reflected lights are diffracted due to said concavo-convex portions to decrease the amount of the light incident on said optical head, thereby to generate an information pulse in a reproduction signal supplied from said optical head; said optical head being arranged such that, when said optical head projects a light beam to said optical information recording medium, the reflected light is incident on said optical head to supply a reproduction signal containing an information pulse corresponding to said second code; and a signal detector circuit for detecting, as said second code, said information pulse in said reproduction signal supplied from said optical head, and for converting said reproduction signal into a digital reproduction signal.
Claim 35
Dependent Claim
93 words
An optical memory apparatus as set forth in Claim 28, wherein the optical information recording medium has first and second recording marks, of which ends in the relative moving direction with respect to the optical head, correspond to the second code of digital information composed of two different types of codes, and which are formed in arcuate shapes having different curvatures, each arcuate end of each second recording mark being longer than that of each first recording mark such that each arcuate end of each second recording mark corresponds to two second codes.
Claim 36
Dependent Claim
353 words
An optical memory apparatus comprising: an optical information recording medium arranged such that (i) first and second recording marks as information are recorded, in the form of physical concavo-convex portions, in said optical information recording medium, (ii) each end of said recording marks in the relative moving direction with respect to an optical head, corresponds to a second code of digital information composed of two different types of codes, (iii) only when a light beam projected from said optical head is projected to an end of said recording marks, the reflected lights are diffracted due to said concavo-convex portions to decrease the amount of the light incident on said optical head, thereby to generate an information pulse in a reproduction signal supplied from said optical head, (iv) the intermediate part of both ends of each of said second recording marks corresponds to said second code, and (v) each of said second recording marks has a width smaller than that of each of said first recording marks such that, when a light beam from said optical head is projected to the intermediate part between both ends of a second recording mark, the reflected lights are diffracted due to said concavo-convex portions to decrease the amount of the light incident on said optical head so that a reproduction signal supplied from said optical head is lower in level than the reference value; said optical head being arranged such that, when said optical head projects, to said optical information recording medium, a light beam having a condensing spot of which diameter is smaller than the width of each of said first recording marks and greater than the width of each of said second recording marks, the light reflected from said optical information recording medium is incident on said optical head to supply a reproduction signal; and a signal detector circuit for detecting, as said second code, (i) the information pulses of the reproduction signals supplied from said optical head and (ii) the parts between information pulses having a level not greater than the reference value, and for converting said reproduction signal into a digital reproduction signal.
Claim 37
Dependent Claim
353 words
An optical memory apparatus comprising: an optical information recording medium arranged such that (i) first and second recording marks as information are recorded, in the form of physical concavo-convex portions, in said optical information recording medium, (ii) each end of said recording marks in the relative moving direction with respect to an optical head, corresponds to a second code of digital information composed of two different types of codes, (iii) only when a light beam projected from said optical head is projected to an end of said recording marks, the reflected lights are diffracted due to said concavo-convex portions to decrease the amount of the light incident on said optical head, thereby to generate an information pulse in a reproduction signal supplied from said optical head, (iv) the intermediate part of both ends of each of said second recording marks corresponds to said second code, and (v) each of said second recording marks has a width smaller than that of each of said first recording marks such that, when a light beam from said optical head is projected to the intermediate part between both ends of a second recording mark, the reflected lights are diffracted due to said concavo-convex portions to decrease the amount of the light incident on said optical head so that a reproduction signal supplied from said optical head is lower in level than the reference value; said optical head being arranged such that, when said optical head projects, to said optical information recording medium, a light beam having a condensing spot of which diameter is smaller than the width of each of said first recording marks and greater than the width of each of said second recording marks, the light reflected from said optical information recording medium is incident on said optical head to supply a reproduction signal; and a signal detector circuit for detecting, as said second code, (i) the information pulses of the reproduction signals supplied from said optical head and (ii) the parts between information pulses having a level not greater than the reference value, and for converting said reproduction signal into a digital reproduction signal.
Claim 38
Dependent Claim
217 words
A magneto-optical memory apparatus comprising: a magneto-optical recording medium which previously contains, as recording marks, physical concavo-convex portions presenting track address information and the like, and which also contains recording areas for recording in formation by inverting the magnetization direction of said magneto-optical recording medium; an optical head arranged such that (i) at the time of recording into said magneto-optical recording medium, said recording marks are recorded by inverting the magnetization direction of said magneto-optical recording medium such that the ends of said recording marks correspond to a second code of digital information composed of two different types of codes, (ii) at the time of reproduction, said optical head projects a light beam having a condensing spot to said magneto-optical recording medium, and said magneto-optical recording medium supplies a reproduction light containing reproduction information to said optical head to supply a reproduction signal, and (iii) when said light beam is projected to a recording mark, an information pulse corresponding to said second code is generated in said reproduction signal, only when the reproduction light from the recording mark interferes with the reproduction light from the non-marking part; and a signal detector circuit for detecting said information pulse in said reproduction signal supplied from said optical head and for converting said reproduction signal into a digital reproduction signal.
Claim 39
Dependent Claim
217 words
A magneto-optical memory apparatus comprising: a magneto-optical recording medium which previously contains, as recording marks, physical concavo-convex portions presenting track address information and the like, and which also contains recording areas for recording in formation by inverting the magnetization direction of said magneto-optical recording medium; an optical head arranged such that (i) at the time of recording into said magneto-optical recording medium, said recording marks are recorded by inverting the magnetization direction of said magneto-optical recording medium such that the ends of said recording marks correspond to a second code of digital information composed of two different types of codes, (ii) at the time of reproduction, said optical head projects a light beam having a condensing spot to said magneto-optical recording medium, and said magneto-optical recording medium supplies a reproduction light containing reproduction information to said optical head to supply a reproduction signal, and (iii) when said light beam is projected to a recording mark, an information pulse corresponding to said second code is generated in said reproduction signal, only when the reproduction light from the recording mark interferes with the reproduction light from the non-marking part; and a signal detector circuit for detecting said information pulse in said reproduction signal supplied from said optical head and for converting said reproduction signal into a digital reproduction signal.
Claim 40
Dependent Claim
81 words
An optical memory apparatus in which digital data comprising first and second kinds of data code portion is recorded onto an optical recording medium in the form of elongate recording marks of which the ends each represent one of said kinds of data code portion and are reproduced by detecting modulations in a beam reflected by or transmitted through the medium, caused by interference between beam portion impinging on the medium at said mark ends and at portions adjacent the marks.
Claim 41
Dependent Claim
81 words
An optical memory apparatus in which digital data comprising first and second kinds of data code portion is recorded onto an optical recording medium in the form of elongate recording marks of which the ends each represent one of said kinds of data code portion and are reproduced by detecting modulations in a beam reflected by or transmitted through the medium, caused by interference between beam portion impinging on the medium at said mark ends and at portions adjacent the marks.
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