GB1565829A - Record medium and method and apparatus for recording information from said record medium - Google Patents
Record medium and method and apparatus for recording information from said record medium Download PDFInfo
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- GB1565829A GB1565829A GB51505/76A GB5150576A GB1565829A GB 1565829 A GB1565829 A GB 1565829A GB 51505/76 A GB51505/76 A GB 51505/76A GB 5150576 A GB5150576 A GB 5150576A GB 1565829 A GB1565829 A GB 1565829A
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- disc
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- circular track
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- 238000000034 method Methods 0.000 title claims description 24
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- 229920002120 photoresistant polymer Polymers 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 4
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- 102000006479 Heterogeneous-Nuclear Ribonucleoproteins Human genes 0.000 claims 1
- 108010019372 Heterogeneous-Nuclear Ribonucleoproteins Proteins 0.000 claims 1
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- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
- G11B7/128—Modulators
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B23/00—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture
- G11B23/0014—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture record carriers not specifically of filamentary or web form
- G11B23/0021—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture record carriers not specifically of filamentary or web form discs
- G11B23/0028—Details
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
- G11B7/00736—Auxiliary data, e.g. lead-in, lead-out, Power Calibration Area [PCA], Burst Cutting Area [BCA], control information
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/085—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection
- G11B7/08547—Arrangements for positioning the light beam only without moving the head, e.g. using static electro-optical elements
- G11B7/08564—Arrangements for positioning the light beam only without moving the head, e.g. using static electro-optical elements using galvanomirrors
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B7/0901—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following only
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B7/095—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following specially adapted for discs, e.g. for compensation of eccentricity or wobble
- G11B7/0953—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following specially adapted for discs, e.g. for compensation of eccentricity or wobble to compensate for eccentricity of the disc or disc tracks
Description
(54) RECORD MEDIUM, AND METHOD AND APPARATUS FOR
RECORDING INFORMATION ON AND REPRODUCING
INFORMATION FROM SAID RECORD MEDIUM
(71) We, SONY CORPORATION, a
Japanese Body Corporate of 7-35 Kitashinagawa, 6-chome, Shingawa-ku, Tokyo,
Japan do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
This invention relates generally to a record medium and, more particularly, to a disc-like record medium, and a method and apparatus for recording information on and reproducing information from that record medium. In use, the record medium is rotated, and a particular concern of this invention is to permit accurate signal recording and reproduction from that medium despite eccentric rotation that might be present.
A rotatable record medium has been used for many years for the recording and reproduction of information. Examples of such a medium include the well-known phonograph disc wherein information is recorded thereon in the form of mechanical undulations which are sensed by a suitable transducer, such as a stylus, and converted into audible sounds. Information is recorded on the phonograph disc by creating a master disc and then stamping multiple copies therefrom. In the master disc, audible sounds are converted into corresponding electrical signals which, in turn, drive a suitable transducer, such as a recording stylus, to effect the various undulations in a generally spiral track about the axis of rotation of the master disc. Another example of a disc-like record medium is a magnetic disc which can be used to record video information, audio information or digital information on its surface. In the magnetic disc, signal information can re recorded either in a substantially continuous spiral track or in concentric circular tracks.
Yet another example of a disc-like record medium is the so-called video disc. In one embodiment of the video disc, video signals and audio signals are recorded in the form of an irregular surface modulation, such as pits or grooves. Such modulation being optically detectable. In another embodiment of the video disc, surface modulation is detected by a suitable stylus.
In general, when a disc-like record medium of the character described is used, it is rotated with respect to a transducer by a suitable driving mechanism, such as a turntable rotary shaft, or the like. Occasionally, the record medium undergoes a lateral displcement, that is, a shift in a generally radial direction, resulting in eccentric rotation. This lateral displacement may be caused by fluctuations in the rotoary drive mechanism. For example, if the record medium is provided with a central hole or apeprture along its axis of rotation, a significant amount of play between that hole and the drive shaft or guide shaft inserted therein will result in such a lateral shift and eccentric rotation.
When information is recorded in concentric circular tracks on the disc-like record medium, the transducer that scans the record medium for signal recording or reproduction ideally should scan a perfect circular track. However. eccentric rotation of the disc will result in corresponding deviations in the scanned track. In a similar manner, if the record medium is provided with a spiral information track of predetermined pitch, the transducer that scans the record medium for signal recording or reproduction should define a spiral track identical to that pitch.
However, eccentric rotation of the disc will result in an irregular pitch of the scanned track. Generally, deviations in the track actually scanned by the transducer from the ideal track are not readily noticeable in phonograph records. That is, eccentric rotation of the disc during manufacture of the master or during playback of a copy is not easily detected. This is because the width and pitch of the information track is relatively large in comparison to the eccentric rotation. Conversely, when information track density must be high, such as in a magnetic disc or in a video disc, an eccentric rotation is readily sensed as distortion in the recording or reproduction of information.
As an example, if the width of an information track is in the range of about 1 to 3 clam.
and if the pitch is about 2 to 3 clam, then lateral shifts in the disc, or eccentric rotation, should be restricted to between 0.1 and 0.5 llm.
Eccentric rotation due to fluctuations in the drive mechanism of the disc can, in many instances, be satisfactorily controlled.
Also, fluctuations in the transducer drive mechanism which will result in an irregular pitch likewise can be controlled satisfactorily in many instances. Unfortunately, an irregular pitch in the information track caused by fluctuations in the drive shaft for the disc heretofore has been controlled only by resorting to very expensive machining techniques in the construction of the drive mechanism.
According to a first aspect of the invention there is provided a record medium comprising a disc-like body adapted to be rotated about a center of rotation and having first and second surfaces. a first portion of at least said first surface having at least one signal information track recorded thereon, and the first surface having a single separate circular track thereon said circular track being distinct from said first portion and said separate circular track being sufficiently accurately concentric with said at least one signal information track as to enable, by scanning only of said circular track during scanning of any of the recorded signal information on said first surface, eccentricity information to be derived from laid separate circular track during eccentric rotation of the record medium and used to ensure proper scanning of said at last one signal information track.
According to a second aspect of the invention there is provided a method of recording signal information on a rotatabledisc-like record medium having a detectable circular track thereon comprising the steps of rotating said record medium about an axis thereof; recording said signal information on a portion of said record medium separate from said circular track during rotation of the medium thereby to form an information track; repetitively detecting only said circular track during recording of all of the signal information to sense eccentric rotation of the record medium; and adjusting the formation of said record track in response to said sensed eccentric rotation of said record medium to compensate for said eccentric rotation.
According to a third aspect of the invention there is provided a method of making a recorded record disc having a predetermined detectable circular track on a surface of said disc and a layer of transformable material separate from sad circular track and provided over substantially the entire said surface, comprising the steps of: rotating said disc about an axis thereof; modulating a carrier with signal information; exposing said transformable layer with the modulated carrier as said disc rotates to record the signal information as an information track on said disc; repetitively detecting only said circular track during the recording of all of the signal information to sense eccentric rotation of the disc; adjusting the formation of said information track by shifting the location at which said modulated carrier impinges said transformable layer in response to said sensed eccentric rotation of said disc to compensate for said eccentric rotation; and developing and foxing said exposed transformable layer on said surface of said record disc to form an irregular surface corresponding to said signal information.
According to a fourth aspect of the invention there is provided a method of reproducing information recorded on a record disc having a predetermined detectable circular track thereon and a separate portion of said disc provided with said information; comprising the steps of: rotating said disc about an axis thereof; scanning said separate portion of said disc to pick up said recorded information; repetitively scanning only said circular track during scanning of any of said recorded information for sensing eccentric rotation of said disc; and adjusting the scanning of said separate portion in response to said sensed eccentric rotation of said disc to compensate for said eccentric rotation.
According to a fifth aspect of the invention there is provided apparatus for recording information on and/or reproducing information from a disc-like record medium having a predetermined detectable circular track thereon and a signal information portion separate from said circular track, the apparatus comprising: means for rotating said record medium about an axis thereof; means for scanning said signal information portion of said record medium along a predetermined path; means for repetitively scanning only said circular track to sense eccentric rotation of said record medium during recording or reproduction of any of said signal information; and means responsive to said sensed eccentric rotation of said record medium to vary the path along which said first-mentioned slanning means scans said signal information portion, whereby said first scanning means scans said signal information portion along a path spaced from said circular track in accordance with a predetermined relation despite eccentric rotation of said record medium relative to said first scanning means.
According to a sixth aspect of the invention there is provided a method of scanning a record disc having a predetermined detectable circular track formed on a surface of said disc and having a signal information portion separate from said circular track, comprising the steps of: rotating said disc about an axis thereof; scanning said signal information portion as said disc rotates; repetitively detecting only said circular track as said disc rotates to sense eccentric rotation thereof during scanning of any of the signal information recorded on the disc; and adjusting the scanning of said signal information portion in response to said sensed eccentric rotation of said record medium, in accordance with the detecting of said circular track, to compensate for said eccentric rotation.
The invention will be further described with reference to the accompanying drawings, in which:
Figure 1 is a plan view of one embodiment of the record medium according to the present invention;
Figure 2 is a block diagram of signal recording apparatus which can be used with the record medium of Figure 1;
Figures 3A-3D are schematic diagrams which are useful in understanding the operation of a portion of the apparatus depicted in Figure 2;
Figure 4 is a graphical illustration which is helpful in understanding the control techni que used with the apparatus shown in Figure ;
Figure 5 is a block diagram of signal reproducing apparatus which can be used with the record medium of Figure 1; and
Figure 6 is another embodiment of a reference track that can be provided on the record medium shown in Figure 1 and used with the apparatus shown in Figures 2 and 5.
Referring now to the drawings, wherein like reference numerals are used throughout, and in particular to Figure 1, there is illustrated one embodiment of a disc-like record medium 1. Disc 1 is provided with a circular bore of hole 2 adapted to receive a drive or guide shaft about which the disc rotates. The disc also is provided with top and bottom surfaces, one or both of which having a portion 3 adapted to have signal information recorded therein and reproduced therefrom and a circular track 4 concentric with the rotary axis of disc 1 and adapted to have reference information therein, described in greater detail below.
In the embodiment illustrated in Figure 1, circular track 4 circumscribes informationbearing portion 3. In an alternative embodiment, information-bearing portion 3 circumscribes the circular track. If disc 1 is similar to a phonograph record disc, a substantially spiral information track is provided in information-bearing portion 3. This track has surface undulations which are sensed by a suitable stylus and converted into corresponding electrical signals which, in turn, are transformed into audible sounds during playback. If disc 1 comprises a magnetic disc, information-bearing portion 3 is provided with a substantially spiral information track on which signal information is magnetically recorded in conventional manner; or, alternatively, such signal information is magnetically recorded in successive, concentric circular magnetic tracks.
In yet another embodiment, if disc 1 is a video disc, then information-bearing portion 3 is formed of a spiral track formed with pits or grooves representing video signal information. As mentioned previously, these pits or grooves are sensed either optically or by a suitable stylus to recover the signal information represented as such pits or grooves.
Circular track 4 is distinct from information-bearing portion 3 and the reference information contained therein is in the form of a detectable predetermined pattern. This pattern is formed of suitable indicia, such as a light-reflective or otherwise optically detectable pattern, or a magnetically recorded reference signal.
As will now be described. the information track or tracks recorded in informationbearing portion 3 is related to circular track 4 such that the distance between any point in the information-bearing portion and circular track 4 is fixed in accordance with a predetermined relation notwithstanding eccentric rotation, or lateral shift, of disc 1 during a signal information recording operation. For the purpose of the present description, it will be assumed that circular track 4 is provided with a light-reflective pattern.
However, as will be readily apparent, the reference information provided in this circular track may, alternatively, be constituted by a predetermined magnetic signal. It will also be assumed that information-bearing portion 3 is provided with a spiral signal information track; and that this spiral track is provided with recorded signal information in the form of irregular surface modulations, such as pits or grooves. Disc 1 thus may comprise a phonograph disc or a video disc.
As an alternative, information-bearing portion 3 of disc 1 may be provided with magnetically recorded signal information in the form of a spiral track.
Referring now to Figure 2, a block diagram is shown of apparatus for recording signal information on information-bearing portion 3 of disc 1. In the illustrated embodiment, disc 1 is to be used as the master disc from which multiple copies are stamped. Disc 1 comprises a base 5 upon which a metal film 6, such as aluminum or other light-reflective material, is deposited such as by evaporation. It is appreciated that film 6 corresponds to circular track 4 shown in Figure 1. This circular track has a width of approximately 1 mm. and a thickness of about 0.1 Fm. A slit 7, such as illustrated in Figure 3A, is formed in the upper surface of film 6, this slit having a
V-shaped groove, as illustrated, or any other suitable configuration to provide a circular discontinuity in the upper surface of the film. This slit has a width of approximately 4 Fm. As will be understood, if light is transmitted to impinge upon the upper surface of film 6, it will be reflected therefrom along a predetermined path except for that portion of the light that impinges slit 7.
This will be explained in greater detail below.
The top surface of base 5 is provided with a transformable layer 10 of uniform thickness. Disc 1, formed as aforedescribed, is placed upon a turntable 9 having a rotary shaft 8. This rotary shaft is adapted to be inserted into central bore 2 of the disc.
Suitable recording apparatus, enclosed within block B, deforms transformable layer 10 with a carrier modulated with signal information as disc 1 rotates. As will be described below, the transformable layer may be a photoresist which is exposed to a light beam modulated with signal information, thereby to form a latent image on the photoresist layer of the information to be recorded.
In the illustrated embodiment, recording apparatus B comprises a transducer 22 adapted to scan the upper surface of disc 1 along a predetermined spiral track. To this effect, a suitable drive mechanism, not shown, displaces transducer 22 in a radially inward direction as disc 1 rotates about its axis formed of rotary shaft 8. Although the scanning movement of transducer 22 is related to the rotary movement of disc 1, fluctuations in rotary shaft 8 will result in eccentric rotation of the disc to cause a lateral shift between a given point on the upper surface of the disc and the transducer.
This could result in the formation of an information track that deviates from the predetermined spiral track. In accordance with the apparatus now to be described, the formation of the spiral track by transducer 22 is compensated in the event of eccentric rotation of disc 1.
Apparatus enclosed within block A is adapted to sense a lateral shift in disc 1 during its rotation. In acordance with ilustrated embodiment, this apparatus comprises a light source 11, optical elements 12, 15 and 16 to focus the light emitted from source 11 onto metal film 6 forming circular track 4, and optical elements 14, 15 and 17 to detect light reflected from the metal film and to sense a lateral shift of disc 1 as a function of a characteristic of the reflected light. Preferably, light source 11 is a He-Ne laser which emits a linearly polarized laser beam. This beam is transmitted to a beamsplitter 12 such that a portion of the emitted beam is transmitted through the beamsplitter to a light detector 13 and another portion of the emitted laser beam is reflected by beam-splitter 12 through a polarized beam-splitter 14, a quarter-wavelength plate 15 and a condenser lens 16. Polarized beam-splitter 14 is matched to the linear polarized direction of laser beam b1 is transmitted through beam-splitter 14 to quarter wavelength plate 15. The quarter wavelength plate is conventional and is adapted to transmit a circular polarized beam in response to the linear polarized beam applied thereto bv beam-splitter 14.
Condenser lens 16 focuses beam b1 onto metal film 6 in the vicinity of slit 7. The focused beam spot produced by lens 16 is approximately 4 Fm diameter.
As will be described, at least a portion of the focused beam is reflected from the surface of metal film 6 through lens 16 and through quarter wavelength plate 15. This reflected light beam is circularly polarized and, consequently, quarter wavelength plate 15 acts upon this circularly polarized beam to produce linear polarization thereof in a direction which is perpendicular to the linear polarization of beam bl that had been transmitted initially to plate 15. The direction of polarization of the reflected beam which now impinges upon beam-splitter 14 is blocked from being transmitted through this beam-splitter and, instead, now is reflected thereby to light detector 17. By properly selecting the polarizing directions of the transmitted and reflected light beams, the same optical elements 14, 15 and 16 can be used to transmit beam b1 onto metal film 6 and to reflect the beam that is reflected from this metal film onto light detector 17.
Thus, the light transmission and reflection paths traversed between beam-splitter 14 and metal film 6 are coincident. In an alternative embodiment, separate light transmission and light reflection paths are used.
Light detector 17 is adapted to produce a control signal having a particular characteristic proportional to the intensity of the light beam reflected from metal film 6 and impinging thereon. In a preferred embodiment, the magnitude of the control signal is proportional to the intensity of light impinging upon light detector 17. With particular reference to Figures 3B-3D, the magnitude of the control signal produced by the light detector is a representation of the magnitude and direction of a lateral shift of disc 1 during its rotation. More particularly, let it be assumed that beam bi impinges upon metal film 6 in the vicinity of slit 7 thereon such that a portion bl' is reflected from the top surface of the metal film and another portion bl" impinges upon the slit proper and, consequently, is not reflected along the incident light path. When disc 1 rotates properly, a predetermined portion b1, (Figure 3B) is reflected from metal film 6. That is, the position o slit 7 during rotation of disc 1 relative to a fixed reference point, such as a reference point defined by optical elements 12, 14, 15 and 16 is a predetermined position. If disc 1 is shifted in a lateral direction, such as in a radially inward direction, slit 7 is displaced relative to the fixed reference point, as shown in Figure 3C. Consequently, a greater portion b,' of indicent beam bl is reflected from metal film 6. Therefore, the reflected beam impinging upon light detector 17 has a greater intensity, resulting in a control signal of higher magnitude. Conversely, if disc 1 is laterally shifted in a radially outward direction such that slit 7 is displaced relative to the fixed reference point as shown in Figure 3D, substantially none of the incident light beam bl is reflected from metal film 6. Thus, the intensity of reflected light impinging upon light detector 17 is at a minimum, and the corresponding control signal magnitude also is a minimum value.
Variations in the intensity of the control signal produced by light detector 17 as a function of a detected displacement in slit 7 relative to the fixed reference point, such as occurs during eccentric rotation of disc 1 is graphically depicted in Figure 4. When the distance between the center-point of slit 7 and the fixed reference point is equal to S, such as when disc 1 rotates properly as depicted in Figure 3B, the magnitude of the control signal reproduced by light detector 17 is represented as the level T. When the center-point of slit 7 is shifted so as to coincide with the fixed reference point, substantially no portion of the incident beam bl is reflected from metal film 6 (Figure 3D), resulting in a control signal whose magnitude is a minimum. It is appreciated that, during normal rotation of disc 1, a portion bl' of indicent beam bl should be reflected so that the direction of displacement of the disc can be determined by sensing a decrease or increase in the intensity of the reflected beam.
To avoid variations in the control signal produced by light detector 17 as a function of a change in the intensity of the light beam emitted by laser 11, the control signal is "normalized" with respect to the emitted laser beam intensity. Essentially, this is performed by a divider circuit 18 coupled to receive the control signal produced by light detector 17 and to divide the magnitude of this cotrol signal with the magnitude of a detected output signal produced by light detector 13. In this manner, deviations in the control signal produced by light detector 17 attributed to variations in the intensity of the laser beam emitted by laser 11 are cancelled because such deviations also will appear in the detected output signal produced by light detector 13. This "normalized" output signal produced by dvider circuit 18 is amplified by a preamplifier 19 and supplied to the recording apparatus in block B for the purpose of adjusting the track along which transducer 22 scans so as to compensate for lateral shifts in disc 1 caused by eccentric rotation thereof.
In the embodiment of the recording apparatus included within block B, signal information is applied to an input terminal 24a to modulate a carrier, whereby transducer 22 records the information-modulated carrier onto disc 1. If transducer 22 comprises a stylus, the information-modulated carrier corresponds to mechanical vibration of the stylus as determined by the signal information. Thus. the stylus will cut a corresponding groove in the upper surface of disc 1 as the disc rotates and as the stylus scans the disc in. for example, a substantially spiral track. For the embodiment wherein disc 1 comprises a magnetic disc, the carrier is a suitable bias signal that is modulated with signal information. and transducer 22 comprises a conventional magnetic recording head. In the illustrated embodiment under discussion, transducer 22 comprises an optical, or light-recording, head wherein the carrier is a light beam which is modulated by the signal information applied to input terminal 24a. This signal-modulated light suitably exposes photoresist layer 10 to form a latent image of the signal information, this image subsequently being developed and fixed in accordance with conventional techniques.
As shown in the illustrated embodiment, a suitable light source, such as an Ar laser 23 emits a laser beam which is transmitted to a conventional light modulator 24 whereat signal information applied to input terminal 24a modulates the laser beam carrer. The modulated laser beam b2 is reflected from a suitable reflecting surface, such as mirror 21, and is focused by a condenser lens 25 to form an information-modulated light spot onto the upper surface of photoresist layer 10 on disc 1. This information-modulated laser beam thus scans a substantially spiral track as transducer 22 moves in a generally radially inward direction while disc 1 rotates about its axis. As mentioned previously in the event of a radial displacement of disc 1 during its rotation, resulting in eccentric rotation of the disc, the actual information track scanned across the surface of the disc by transducer 22 will vary from its ideal spiral track. Consequently, when information is reproduced from the record disc, or when the record disc is used to make multiple copies from which information is reproduced, such deviations in the recorded information track will deleteriously affect the reproduced signals, particularly if the disc is not subjected to an identical eccentric rotation during a signal reproducing operation.
This problem is substantially overcome by adjusting the formation of the signal information record track during recording by shifting the location at which the modulated laser beam impinges photoresist layer 10 of disc 1 in response to sensed eccentric rotation of the dsc. This is achieved by applying the amplified control signal produced by preamplifer 19 through an additional amplifier 20 to a positioning device for mirror 21.
As an example, mirror 21 may be mounted on a D'Arsonval movement so that the path along which modulated laser beam bo is directed is a function of the amplified control signal applied to the D'Arsonval coil. Thus, it may be appreciated that the combination of circular track 4 having metal film 6 and slit 7 therein, together with the sensing apparatus including light detector 17, and adjustable mirror device 21 function as a servo system to maintain the information-modulated laser beam b2 at a proper location on the surface of disc 1 despite any radical displacement or eccentric rotation of the disc.
The servo control function of the illustrated apparatus will best be understood if it is assumed, in the interest of simplification, that information-modulated laser beam b2 is adapted to scan a circular information track only. If disc 1 is displaced in a radially outward direction by an amount Ar the intensity of light reflected to light detector 17 is reduced, as seen in Figure 3D. This shift Ar in disc 1 would deviate the circular track scanned by information-modulated beam b2 by a corresponding amount Ar.
However, the detected change in light intensity, as sensed by light detector 17, applied a control signal to, for example, the D'Arsonval movement to which mirror 21 is mounted, thereby changing the reflecting path along which information-modulated beam b2 is transmitted, resulting in a displacement of the information beam spot on the surface of disc 1 by an amount Ar.
Hence, even though disc 1 may be subjected to eccentric rotation, the information track scanned across the surface of the disc is substantially maintained at a correct distance from circular track 4 in accordance with a predetermined relation. Although the foregoing has assumed that this predetermined relation is a fixed distance, that is, the information track is a circular track, it now should be fully appreciated that the instantaneous distance between the point of incidence of information-modulated beam b2 from circular track 4 may vary in accordance with a predetermined function so as to scan a spiral information track across the surface of the disc.
A similar control operation is performed to adjust the point of indicence of information-modulated beam b, on the surface of disc 1 in the event that the disc is subjected to a radially inward displacement by an amount Ar, such as depicted in Figure 3C.
In the interest of brevity, description of this operation is not provided.
Once the signal information light, it is appreciated that the surface of disc 1 may be provided with a layer of other transformable material and a compatible carrier can be modulated to deform such material to form irregular surface undulations representing such information. For example, the deformable material may be a thermoplastic material, and the carrier used therewith may be thermal energy that is modulated with information to be recorded.
As another alternative, the transformable material may be an electrostatic- or electrophotostatlc-sensitive medium, and the carrier may be an electric charge that is modulated with signal information to be recorded or may be an informationmodulated light beam adapted to selectively dissipate a charge provided on the surface of such a medium.
Turning now to Figure 5, there is illustrated a preferred embodiment of signal reproducing apparatus capable of reproducing the signal information that had been recorded on the information-bearing portion 3 of disc 1 by the apparatus depicted in
Figure 2 and described above. Accordingly, disc 1 is provided with surface irregulaties in the form of undulations, such as pits or grooves, at information-bearing portion 3 and also is provided with a circular track having slit 7 therein. In use, disc 1 is placed upon a turntable 27 and a rotary shaft 26 is inserted into the central bore of the disc for rotating the record medium. Displacement of disc 1 in the radial direction, as during eccentric rotation, is sensed by the apparatus enclosed within block A. This apparatus is substantially identical to that previously described in conjunction with Figure 2. Hence, in the interest of brevity, duplicative explanation here is avoided. Suffice it to say that radial displacement of disc 1 is sensed by detecting the corresponding movement of slit 7 which, as described previously, affects the intensity of the light beam reflected from the circular track to light detector 17, as depicted in Figures 3B-3D. Consequently, an amplified control signal is produced by preamplifier 19 having a magnitude proportional to the sensed radial displacement of disc 1.
It is understood that the signal information reproducing apparatus must be compatible with the signal recording apparatus described previously in conjunction with the embodiment shown in Figure 2. Accordingly, such signal information reproducing apparatus is adapted to sense the signal information recorded as surface irregularities on disc 1 by transmitting a light beam, such as a laser beam, onto the surface of the disc and detecting modulations in. the reflected light from the disc. To this effect, a light source, such as a He-Ne laser 28 emits a linearly polarized laser beam that is transmitted to a beam-splitter 29. Beamsplitter 29 is substantially similar to aforedescribed beam-splitter 14 and is adapted to transmit light therethrough having a linear polarization in a predetermined direction, but to reflect substantially all light that is transmitted thereto having a perpendicularly disposed linearly polarized direction.
The laser beam emitted by laser 28 passes through beam-splitter 29 and through a quarter wavelength plate, this plate being substantially similar to aforedescribed quarter wavelength plate 15. Hence, quarter wavelength plate 30 changes the polarization pattern of the emited laser beam from a linear polarization to a circular polarization, as is conventional. This circularly polarized light is reflected from a mirror 21 along path b3 and is focused by a condenser lens 31 to a beam spot on the surface of disc 1. Light beam b3 impinging upon the surface irregularities of disc 1 is reflected from the disc to traverse the same light path through condenser lens 31 and mirror 21, now in the opposite direction. This reflected light beam is modulated in accordance with the signal information recorded on disc 1, and is reflected by mirror 21 to pass through quarter wavelength plate 30. The circular polarization of this modulated beam is converted by the quarter wavelength plate into a linear polarization which now is in a direction substantially perpendicular to the linearly polarized direction of the laser beam emitted from laser 28. Consequently, this information-modulated light beam is substantially entirely reflected by beam splitter 29 to a light detector 32 whereat the modulated signal information is recovered.
For the embodiment wherein mirror 21 and condenser lens 31 comprise a transducer 33 adapted to scan a spiral track across the surface of information-bearing portion 3 of disc 1. a suitable drive mechanism (not shown) is provided to advance the transducer in a radial direction as the disc rotates.
Similarly, if transducer 33 is adapted to scan concentric circular tracks across the surface of disc 1, a suitable driving mechanism is provided to advance the transducer in a radial direction.
As in the previously described recording apparatus, in the event of a radial displacement of slit 7 in circular track 4 caused by eccentric rotation of disc 1, as by fluctuations in rotary shaft 26, the amplified control signal produced by preamplifier 19 and further amplified by amplifier 20 serves to vary the position of mirror 21 so as to correspondingly displace the point of incidence of beam b3 on the surface of disc 1 so as to compensate for such radial displacement. Hence, mirror 21 may be secured to a
D'Arsonval movement such that the angular position of the mirror is adjusted as a function of the magnitude of the control signal. Thus, beam b3 impinges upon the surface of disc 1 at a location that is relatively fixed from slit 7 of circular track 4 in accordance with a predetermined relation. As is recognized, for the embodiment wherein signal information is recorded in a spiral track, this 'pwdetermind relation" establishes a spiral scanning track of beam b3.
It is appreciated that the control over the location at which beam b3 impinges upon the surface of disc 1 during a signal reproduction operation is substantially identical to the control over beam b2 described previously with respect to a signal recording operation. Hence, further description of the reproducing apparatus shown in Figure 5 need not be described.
It should be recognized that the reproducing apparatus which is used to recover the previously recorded signal information should be compatible with the nature of disc 1. For example. if disc I is a phonograph disc, transducer 33 is a suitable stylus.
Alternatively, if disc 1 is a magnetic disc, transducer 33 is a conventional magnetic reproducing head.
In the foregoing embodiments. it has been assumed that the reference information provided in circular track 4 is constituted by slit 7 disposed in a light-reflective material, such as metal film 6. As an alternative embodiment, this reference information may consist merely of a narrow light-reflective track, such as a track whose width is about 4 Ktm. Still another embodiment of circular track 4 is illustrated in
Figure 6 as comprising a first circular pattern 5A of uniformly spaced light-reflective elements having a first periodicity. and a second adjacent circular pattern 5B of uniformly spaced light-reflective elements having a second periodicity. Superimposed on these adjacent circular patterns of lightreflective elements is beam spot 34 corresponding to the focused light beam b As is seen, a portion of beam spot 34 impinges upon circular pattern 5A and another portion of the beam spot impinges upon circular pattern 5B. Hence the intensity of light reflected to light detector 17 includes a first component corresponding to the periodicity of light-reflective elements 5A and a second component corresponding to the periodicity of light-reflective elements 5B. In accordance with the illustrated embodiment shown in Figure 6, the first component of the light intensity is of a higher frequency than the second component thereof. When disc 1 rotates properly such that circular track 4 is located in proper relation with respect to the fixed reference point defined by beam spot 34, the first, or higher frequency component of reflected light will exhibit a first predetermined intensity and the second, or lower frequency component of the reflected light will exhibit a second predetermined intensity. Any shift in the relative position of circular track 4 with respect to fixed beam spot 34, as by eccentric rotation of disc 1, will alter the respective intensities of the higher and lower frequency components of the light reflected to light detector 17. This change in the respective light intensities is used to produce a control signal corresponding to the direction and magnitude of a radial shift in disc 1. As before, this control signal is used to adjust the track scanned by transducer 22 or by transducer 33 so as to compensate for eccentric rotation of disc 1.
While the present invention has been particularly shown and described with reference to certain preferred embodiments thereof, it should be readily apparent that various changes and modifications in form and details, such as those suggested hereinabove. as well as others. will be readily apparent to those of ordinary skill in the art.
For example, the detectable pattern of indicia forming the reference information provided in circular track 4 may be a predetermined magnetically-recorded signal, or optically detectable indicia. Also, recording transducer 22 as well as reproducing transducer 33 mav exhibit the various alternative embodiments described above, or may be differently constructed. For example, these respective transducers may generate an electron beam suitable for recording and detecting information on disc 1. Therefore, it is intended that the appended claims be interpreted as including all of the foregoing changes and modifications in structure and in use of the aforedescribed invention.
WHAT WE CLAIM IS:
1. A record medium comprising a disclike body adapted to be rotated about a center of rotation and having first and second surfaces. a first portion of at least said first surface having at least one signal information track recorded thereon, and the first surface having a single separate circular track thereon, said circular track being distinct from said first portion and said separate circular track being sufficiently accuratelv concentric with said at least one signal information track as to enable. by scanning only of said circular track during scanning of any of the recorded signal information on said first surface, eccentricity information to be derived from said separate circular track during eccentric rotation af the record medium and used to ensure proper scanning of said at least one signal information track.
2. The record medium of Claim 1 wherein said circular track circumscribes
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (36)
1. A record medium comprising a disclike body adapted to be rotated about a center of rotation and having first and second surfaces. a first portion of at least said first surface having at least one signal information track recorded thereon, and the first surface having a single separate circular track thereon, said circular track being distinct from said first portion and said separate circular track being sufficiently accuratelv concentric with said at least one signal information track as to enable. by scanning only of said circular track during scanning of any of the recorded signal information on said first surface, eccentricity information to be derived from said separate circular track during eccentric rotation af the record medium and used to ensure proper scanning of said at least one signal information track.
2. The record medium of Claim 1 wherein said circular track circumscribes
said first portion.
3. The record medium of Claim 1 wherein said circular track is circumscribed by said first portion.
4. The record medium of Claim 1 wherein said first portion comprises a spiral track within which said signal informatin is recorded.
5. The record medium of Claim 1 wherein said circular track comprises a predetermined pattern of a detectable characteristic.
6. The record medium of Claim 5 wherein said predetermined pattern is light reflective.
7. The record medium of Claim 4 wherein the distance between any point on said spiral track and said circular track is fixed in accordance with a predetermined relation notwithstanding eccentric rotation of said record medium during recording of signal information.
8. A method of recording signal information on a rotatable disc-like record medium having a detectable circular track thereon comprising the steps of rotating said record medium about an axis thereof; recording said signal information on a portion of said record medium separate from said circular track during rotation of the medium thereby to form an information track; repetitively detecting only said circular track during recording of all of the signal information to sense eccentric rotation of the record medium; and adjusting the formation of said record track in response to said sensed eccentric rotation of said record medium to compensate for said eccentric rotation.
9. The method of Claim 8 wherein said step of detecting said circular track to sense eccentric rotation of said record medium comprises generating a control signal having a characteristic that varies as a function of the amount and direction of eccentric rotation of said record medium.
10. The method of Claim 9 wherein said step of adjusting the formation of said information track to compensate for said eccentric rotation comprises deviating said information track from a predetermined path in response to said control signal.
11. The method of Claim 9 wherein said circular track is a light reflective track and said control signal is generated by transmitting a light beam onto said light reflective back, reflecting said light beam from said track onto a light detector, and generating a control signal having a magnitude proportional to the intensity of the light beam impinging upon said light detector.
12. A method of making a recorded record disc having a predetermined detectable circular track on a surface of said disc and a layer of transformable material separate from said circular track and provided over substantially the entire said surface, comprising the steps of: rotating said disc about an axis thereof; modulating a carrier with signal information; exposing said transformable layer with the modulated carrier as said disc rotates to record the signal information as an information track on said disc; repetitively detecting only said circular track during the recording of all of the signal information to sense eccentric rotation of the disc; adjusting the formation of said information track by shifting the location at which said modulated carrier impinges said transformable layer in response to said sensed eccentric rotation of said disc to compensate for said eccentric rotation; and developing and fixing said exposed transformable layer on said surface of said record disc to form an irregular surface corresponding to said signal information.
13. The method of Claim 12 wherein said circular track is light reflective and is detected by transmitting a light beam from a fixed source to a predetermined location with respect to said circular track, reflecting said light beam from said circular track to a light detector, and generating a control signal proportional to the intensity of said light beam reflected to said light detector, said intensoity varying from a predetermined level when said light beam impinges on said circular track at a location that varies from said predetermined location due to eccentric rotation of said disc.
14. The method of Claim 13 wherein said carrier is a second light beam and said transformable material is a photo-resist, and wherein the location at which said modulated carrier impinges said transformable layer at which said modulated carrier impinges said transformable layer is shifted by reflecting the modulated second light beam onto the photoresist layer along a predetermined path, and varying the reflecting path of said modulated second light beam as a function of said control signal.
15. A method of reproducing information recorded on a record disc having a predetermined detectable circular track thereon and a separate portion of said disc provided with said information; comprising the steps of: rotating said disc about an axis thereof; scanning said separate portion of said disc to pick up said recorded information; repetitively scanning only said circular track during scanning of any of said recorded information for sensing eccentric rotation of said disc: and adjusting the scanning of said separate portion in response to said sensed eccentric rotation of said disc to compensate for said eccentric rotation.
16. The method of Claim 15 wherein said step of scanning said circular track to sense eccentric rotation of said disc compris es rotating said circular track with respect to fixedly disposed detecting means; generating a control signal that is a function of the detected position of the circular track; and varying said control signal in accordance with the detected position of the circular track.
17. The method of Claim 16 wherein said separate portion of said disc is scanned along a predetermined path and said step of adjusting said scanning of said separate portion comprises altering said predetermined path as a function of the deviation of said control signal from a predetermined value.
18. The method of Claim 17 wherein said circular track is light reflective, and said step of detecting said circular track comprises impinging a light beam onto said circular track; reflecting at least a portion of said light beam from slaid circular track onto a fixedly disposed light detector; and generating said control signal as a function of the amount of said light beam that is reflected to said light detector.
19. The method of Claim 18 wherein said separate portion of said disc is scanned along a predetermined spiral track. the spiral configuration thereof being modified as said control signal deviates from said predetermined value.
20. Apparatus for recording information on and/or reproducing information from a disc-like record medium having a predetermined detectable circular track thereon and a signal information portion separate from said circular track, the apparatus comprising: means for rotating said record medium about an axis thereof; means for scanning said signal information portion of said record medium along a predetermined path; means for repetitively scanning only said circular track to sense eccentric rotation of said record medium during recording or reproduction of any of said signal information; and means responsive to said sensed eccentric rotation of said record medium to vary the path along which said first-mentioned scanning means scans said signal information portion. whereby said first scanning means scans said signal information portion along a path spaced from said circular track in accordance with a predetermined relation despite eccentric rotation of said record medium relative to said first scanning means.
21. The apparatus of Claim 20 wherein said means for scanning said circular track comprises fixedly disposed detecting means for detecting said circular track as said record medium rotates: and control signal generating means coupled to said detecting means for generating a control signal whose value deviates from a predetermined value in the event that said circular track is shifted relative to said detecting means because of eccentric rotation.
22. The apparatus of Claim 21 wherein said first-mentioned scanning means comprises transducer means, and means for moving said transducer means and said record medium relative to each other in a radial direction with respect to said axis of rotation; and wherein said means to vary the path along which said first-mentioned scanning means scans said signal information portion comprises means responsive to said control signal for adjusting the position of said transducer relative to said record medium.
23. The apparatus of Claim 21 wherein said circular track is light reflective and said detecting means comprises a light source for transmitting a light beam to said circular track and light sensing means disposed to receive light reflected from said circular track to produce an output signal proportional to said reflected light.
24. The apparatus of Claim 23 wherein said circular track is a strip of light reflective material; said light source includes means for normally impinging a portion of said light beam onto said strip; and said light sensing means produces an output signal proportional to the intensity of said reflected light.
25. The apparatus of claim 24 wherein said control signal generating means normally generates a control signal of predetermined value when a predetermined portion of said light beam impinges onto said strip.
26. The apparatus of claim 25 wherein said control signal generating means comprises light detecting means optically coupled to said light source to produce a detected signal proportional to the intensity of the light emitted bv said light source, and means coupled to said light detecting means and to said light sensing means for normalizing said output signal with said detected signal to produce said control signal, so as to cancel deviations in said control signal attributed to variations in the intensity of said light emitted by said light source.
27. The apparatus of Claim 23 wherein said circular track comprises a first circular pattern of periodic light reflective elements having a first spacial periodicity and an adjacent second circular pattern of periodic light reflective elements having a second spatial periodicity: said light source includes means for normally impinging a first portion of said light beam onto said first circular pattern and a second portion of said light beam onto said second circular pattern; and said light sensing means produces an output signal proportional to the intensities of first and second periodic components of said reflected light corresponding to said periodicities of said light reflective elements.
28. The apparatus of Claim 22 wherein said transducer comprises a light source for emitting a light beam, optical means couled to said light source for transmitting said light beam onto said record medium, and modulating means for modulating said light beam with said signal information; said means for moving said transducer and said record medium relative to each other defines a spiral signal information track on said record medium; and said means for adjusting the position of said transducer comprises means for adjusting said optical means to correspondingly adjust the location at which said light beam impinges upon said record medium.
29. The apparatus of Claim 22 wherein said transducer comprises a light source for emitting a light beam, optical means couled to said light source for transmitting said light beam onto said record medium whereat said light beam is modulated with information recorded on said medium, and detecting means optically coupled to said record medium along a light reflective path to receive said modulated light beam reflected from said medium for producing an information signal corresponding to said recorded information; said means for moving said transducer and said record medium relative to each other defines a spiral track on said record medium; and said means for adjusting the position of sad transducer comprises means for adjusting said optical means to correspondingly adjust the location at which said light beam impinges upon said record medium.
30. A method of scanning a record disc having a predetermined detectable circular track formed on a surface of said disc and having a signal information portion separate from said circular track, comprising the steps of: rotating said disc about an axis thereof; scanning said signal information portion as said disc rotates: repetitively detecting only said circular track as said disc rotates to sense eccentric rotation thereof during scanning of any of the signal information recorded on the disc; and adjusting the scanning of said signal information portion in response to said sensed eccentric rotation of said record medium, in accordance with the detecting of said circular track, to compensate for said eccentric rotation.
31. A rotatable record medium substantially as hereinbefore described with reference to and as shown bv the accompanying drawings.
32. A method of recording signal information on a rotatable record medium substantially as hereinbefore described with reference to the accompanying drawings.
33. Apparatus for recording information on and/or reproducing information from a rotatable record medium substantially as hereinbefore described with reference to the accompanying drawings.
34. A method of making a recorded record disc substantially as hereinbefore described with reference to the accompanying drawings.
35. A method of reproducing information recorded on a record disc substantially as hereinbefore described with reference to the accompanying drawings.
36. A method of scanning a record disc substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP50157200A JPS5280007A (en) | 1975-12-26 | 1975-12-26 | Video disc |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1565829A true GB1565829A (en) | 1980-04-23 |
Family
ID=15644380
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB51505/76A Expired GB1565829A (en) | 1975-12-26 | 1976-12-09 | Record medium and method and apparatus for recording information from said record medium |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5280007A (en) |
| CA (1) | CA1085050A (en) |
| DE (1) | DE2658677A1 (en) |
| FR (1) | FR2336766A1 (en) |
| GB (1) | GB1565829A (en) |
| NL (1) | NL7614450A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0082337A2 (en) * | 1981-12-23 | 1983-06-29 | International Business Machines Corporation | Assembly including a flexible disk and a diskdrive therefor |
| GB2188474A (en) * | 1986-03-27 | 1987-09-30 | Philips Electronic Associated | Electronic digital storage apparatus |
| GB2196467A (en) * | 1986-10-11 | 1988-04-27 | London Weekend Television | Optical disc with added magnetic record/playback facility |
| EP0507304A2 (en) * | 1991-04-02 | 1992-10-07 | Sony Corporation | Optical disc and optical disc reproducing apparatus |
| EP0516125A2 (en) * | 1991-05-31 | 1992-12-02 | Sony Corporation | Rewritable disk and disk apparatus |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4074085A (en) * | 1976-03-31 | 1978-02-14 | Eli S. Jacobs | Multiple beam optical record playback apparatus for simultaneous scan of plural data tracks |
| DE3066828D1 (en) * | 1979-07-16 | 1984-04-12 | Discovision Ass | Video player/recorder for recording on a blank disk and method for home recording |
| JPS57130240A (en) * | 1981-02-05 | 1982-08-12 | Olympus Optical Co Ltd | Optical information recording and reproducing device and information recording medium for it |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1183948B (en) * | 1961-01-12 | 1964-12-23 | Telefunken Patent | Memories, especially micro memories for information |
| US3361873A (en) * | 1962-05-07 | 1968-01-02 | Minnesota Mining & Mfg | Disc recording system |
| US3479664A (en) * | 1965-12-28 | 1969-11-18 | Data Products Corp | Servo positioning system |
| NL174591C (en) * | 1973-02-09 | 1984-07-02 | Philips Nv | DISC REGISTRATION CARRIER BODY. |
| DE2453364C3 (en) * | 1973-11-09 | 1979-02-22 | Hitachi, Ltd., Tokio | Automatic focusing device |
| US3881184A (en) * | 1974-05-28 | 1975-04-29 | Ibm | Adaptive digital servo system |
| FR2315142A1 (en) * | 1975-06-17 | 1977-01-14 | Pyral Soc | Transducer head guide system - using additional guide track associated with magnetic recording track |
-
1975
- 1975-12-26 JP JP50157200A patent/JPS5280007A/en active Pending
-
1976
- 1976-12-09 GB GB51505/76A patent/GB1565829A/en not_active Expired
- 1976-12-22 CA CA268,574A patent/CA1085050A/en not_active Expired
- 1976-12-23 DE DE19762658677 patent/DE2658677A1/en not_active Ceased
- 1976-12-24 FR FR7639100A patent/FR2336766A1/en active Granted
- 1976-12-27 NL NL7614450A patent/NL7614450A/en not_active Application Discontinuation
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0082337A2 (en) * | 1981-12-23 | 1983-06-29 | International Business Machines Corporation | Assembly including a flexible disk and a diskdrive therefor |
| EP0082337A3 (en) * | 1981-12-23 | 1983-10-26 | International Business Machines Corporation | Control system for flexible disk file |
| GB2188474A (en) * | 1986-03-27 | 1987-09-30 | Philips Electronic Associated | Electronic digital storage apparatus |
| GB2196467A (en) * | 1986-10-11 | 1988-04-27 | London Weekend Television | Optical disc with added magnetic record/playback facility |
| EP0507304A2 (en) * | 1991-04-02 | 1992-10-07 | Sony Corporation | Optical disc and optical disc reproducing apparatus |
| EP0507304A3 (en) * | 1991-04-02 | 1993-05-19 | Sony Corporation | Optical disc and optical disc reproducing apparatus |
| EP0516125A2 (en) * | 1991-05-31 | 1992-12-02 | Sony Corporation | Rewritable disk and disk apparatus |
| EP0516125A3 (en) * | 1991-05-31 | 1993-09-29 | Sony Corporation | Rewritable disk and disk apparatus |
| US5297131A (en) * | 1991-05-31 | 1994-03-22 | Sony Corporation | Eccentricity detection and compensation of a disk by a preformatted encoding pattern |
| KR100255735B1 (en) * | 1991-05-31 | 2000-05-01 | 이데이 노부유끼 | Disc type signal recording medium, and signal recording apparatus and signal reproducing apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2336766A1 (en) | 1977-07-22 |
| CA1085050A (en) | 1980-09-02 |
| DE2658677A1 (en) | 1977-07-14 |
| FR2336766B1 (en) | 1984-09-14 |
| JPS5280007A (en) | 1977-07-05 |
| NL7614450A (en) | 1977-06-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |