CA1091804A - Multi-layered optical data records and playback apparatus - Google Patents
Multi-layered optical data records and playback apparatusInfo
- Publication number
- CA1091804A CA1091804A CA342,948A CA342948A CA1091804A CA 1091804 A CA1091804 A CA 1091804A CA 342948 A CA342948 A CA 342948A CA 1091804 A CA1091804 A CA 1091804A
- Authority
- CA
- Canada
- Prior art keywords
- data
- light
- record
- distributor
- light beam
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
- G11B27/102—Programmed access in sequence to addressed parts of tracks of operating record carriers
-
- 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
- G11B7/002—Recording, reproducing or erasing systems characterised by the shape or form of the carrier
- G11B7/0033—Recording, reproducing or erasing systems characterised by the shape or form of the carrier with cards or other card-like flat carriers, e.g. flat sheets of optical film
-
- 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
-
- 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
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
-
- 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
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
Abstract
Abstract Multi-layered optical data records and playback apparatus are des-cribed in which a plurality of optical data layers are provided on at least one side of a record substrate and the playback apparatus scans data tracks on such layers with a light beam to produce an electrical readout signal corresponding to the data in the scanned tracks. The playback apparatus includes selection means for selectively playing back data tracks on different ones of the data layers. The data track may be formed by lines of data spots of binary coded digital information or such spots may be frequency modulated or pulse length modulated analog information which are photographically re-corded at extremely high data density so that they may be used to record audio or video signals including television signals. While the optical data records may be light transparent, they are preferably light reflective so that the playback light source and associated focusing and scanning means may be sup-ported on the same side of the record as the light detector to provide a more compact playback apparatus. This also enables at least some of the same optical elements to be used for transmitting the reflected light beam to the detector that are used for transmitting the playback light beam from the light source to the record. Selection of one data track for playback may be accom-plished by changing the focus of the light beam from one data layer to another, or by making the data tracks of optically different materials, such as using different color dyes or different photoluminescent materials, and selectively positioning corresponding color filters in front of the light detectors.
Description
,~ 1091804 The subject matter of the present invention relates generally to multiple layer optical data records and associated playback apparatus, and in particular to such records which include a plurality of data information tracks in different data layers provided on at least one side of the record sub~strate or base member, and to such playback apparatus which includes selec-tion means for selectively reading out one of such data tracks with a scanning light beam to produce an electrical readout signal corresponding to the data ; on the scanned track. The multi-layered records and playback apparatus of the present invention are extremely useful for high density information stor-age. For example, one application of the present invention is the recording . ., ~, and playing back of audio and video signals used in television programs.
,,, Previously it has been suggested in United States Patent 3,430,966 of D.P. Gregg, granted March 4, 1969, and United States Patent 3,518~442 of K.0, Johngon, granted June 30, 1970, to provide an optical data record in which data is recorded by notches in two tracks on opposite sides of a light transmissive substrate member. However, such prior art records and their associated playback apparatus have several disadvantages since the records only have one data layer per side and are read out by transmitting a light .:, beam through the record including a light diffusing layer provided between .~. , ,r 20 the two data layers. As a result, these records cannot store as much data I` as the record of the present invention and are more expensive and difficult ~. .
,,'! to manufacture. Also, the playback apparatus requires separate focusing J optical systems for the light detector and for the light source because they '''! are on opposite sides of the record. mus, the playback apparatus is not as ....
compact as the embodiment of the present invention employing reflective records .,, ' - .
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because in the latter the detector is positioned on the same side of the record as the light source.
It has been proposed by K, Compaan and P. Kramer in Philips Technical Review, Volume 33, pages 178 to 180, 1973 No. 7, to employ light reflecting optical data records so that the detector and light source may be positioned on the same side of the record and may use common optical elements. However, this record has the disadvantage that optical data is recorded as pits or notches in a single layer which is formed in a conventional manner by pressing the records from a master. As a result, only about thirty minutes of tele-. ...
vision programs can be recorded on a large record of 30 centimeters in dia-,, meter, the size of a conventional long playing phonograph record. The entire surface of the record, including the data pits, is coated with metal for re-flecting the light beam so that several data layers could not be recorded on the same side of the record in the manner of the present invention. The data pits, unlike the background surface, reflect the light beam away from the detector and are detected by the absence of light at the detector 90 that there is a lower signal to noise ratio in the ele~trical readout signal than ,.~,, .
~xi that of the present invention.
- Also of interest as a background on optical data records and play-back systems for fixed records in United States patent 3,501,586, granted ~: March 17, 1970, to J,T. Russell. However, this patent does not disclose multi-layered data records in the manner of the present invention.
` According to one aspect of the invention there is provided a light .- ' beam scanner apparitus comprising: a rotating scanner wheel supported on a rotor shaft; a plurality of lenses and associated first mirrors mounted in , ., j -2-: :,.,;
-;., .... . , ~ . - .. , :. . ~ - - :. ~- . . . . .
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10918(~4 lenx_~irror pairs on said scanner wheel; and distributor means mounted on the rotor shaft for distributing a light beam to one of the lens-mirror pairs at a time, ~aid distributor means including a plurality of distributor mirrors spaced around said shaft for reflecting the light beam from one distributor mirror to one of the first mirrors which first reflects said beam through its associated lens.
. According to another aspect of the invention there is provided a : light beam scanner apparatus comprising: a rotating scanner wheel supported on a rotor shaft; a plurality of lenses mounted on said scanner wheel; and distributor means mounted on said rotor shaft for distributing a light beam to oneof said lenses at a time, said dis.tributor means including a plurality : of distributor mirrors spaced around the shaft axis for reflecting the light beam from one distributor mirror to one of ~aid lenses.
Other objects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments thereof and from the attached drawings of which:
Figure 1 is a schematic diagram oP one embodiment of a playback apparatus for a.reflective type of multi-layer optical data record in accord-ance with the present invention;
- 20 Figure 2 is an elevation view taken along the line 2-2 of Figure l;
-. Figure 3 is a schematic diagram of a second embodiment.of a playback - apparatus similar to that of Figure 1 but modified for light tran~missive .
type multi-layer optical data records;
Figure 3A is an elevation view taken along the line 3A-3A of Figure 3.
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gi804 Figure 4 is an enlarged section view of a portion of a multi-layer optical data record with spacer layers between the data layers which may be used in the playback apparatus of Figures 1 or 3;
Figure 5 is an enlarged section view of a portion of another embodiment of the multi-layer optical data record of the present invention with a reflection layer separate from the data layers;
Figure 6 is an enlarged section view of a portion of a third embodi-ment of a multi-layer optical data record without spacer layers; and ' Figure 7 is an enlarged section view of a portion of a fourth embodi-ment of the multi-layer optical data record without spacer layers.
As shown in Figures 1 and 2, a multi-layered cptical data record 10 of the reflective'type, such as that shown in Figure 4 which employs light reflecting material for the data spots or for the background regions surround-ing transparent data spots, is played baek with a playbaek apparatus including a light source 12 d a light deteetor 14 positioned on the same side of the , record. This reflective playback apparatus has the advantages of providing ' a more compact apparatus and enabling the use of at least some of the optieal , elements including the objective lenses 16 in the same light paths for the ; light reflected from the reeord 10 to the detector 14 and for the light trans-~, 20 mitted from souree 12 to the record. This reduees the eost and eauses some of the defeets of the optical system, sueh as lens aberration, to be cancelled `~ as a result of the light beam traversing the elements twiee in opposite dir-,, ' '~ eetions.
The light souree 12 may be a laser whieh produee~ "eoherent" light of one or more narrow freque~ey b~nds, or a suitable souree of intense non-;~ _4-;:~
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1~91804 coherent "white" light of many frequencies, including ultraviolet light, in-frared light, as well as visible light. A light beam 18 is transmitted from source 12 through a primary lens 20 and an apertured light mask commonly re-ferred to as a "pin hole" element 22. Lens 20 focuses the light beam to a sma11 spot at the circular aperture of the pin hole element so that such aperture shapes the light spot and forms the object that is imaged onto the record by the ob.jective lenses 16. me light beam 18 is transmitted through a be~n splitting mirror 24 onto a rotating distributor mirror member 26 whose outer surface is in the form of a five-sided polygon having five mirrors pro-vided thereon which correspond to five objective lenses 16 which are carried on a rotating scanner wheel 28. The distributor mirror member 26 is mounted on the shaft 30 of the scanner wheel 28 so that i~ is rotated with such wheel at a constant speed by an electrical motor 32 coupled thereto. As a result, the distributor mirror member 24 rotates at the same speed as the objective ~ lenses 16 so that one of the mirrors of such distributor member is always ; aligned with its associated objective lens. Thus, the distributor mirror ; member 26 distributes the light beam to the objective lenses 16 one at a time as such lenses rotate across the record 10 to playback one of the data track lines 35 on such record as shown in Figure 2.
The light beam 18 is reflected from one of the distributor mirrors onto one of five objective mirrors 34 mounted on the scanner wheel 28 imme-diately beneath each objective lens 16. As a result, the light beam is re-flected from the objective mirror 34 through its associated objective lens 16 onto the multi-layer optical data record 10. The light beam is focused by lenses 20 and 16 to a small spot in a focus plane on one of the data layers , , ., ,.,- -. :
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~ 1091804 of the record, such spot being of a diameter which is substantially the same size as the ~idth of one of the data track lines 35 of data spots provided on such record.
A selection means is provided for moving the focus plane from one data layer to another to selectively playback the selected data track on such layers. This change in the fo¢us plane may be accomplished by moving the pin hole light mask 22 and the primary lens 20 longitudinally along the beam axis by means of an electromagnetic coil 36 and associated electrical control circuit. The coil 36 attracts or repels a magnetic armature 38 on which the pin hole mask 22 is mounted 30 that it and the lens 20 coupled thereto move toward and away from the record 10. A spring biasing element 40 may be used for mounting the pin hole light mask 22 which resists the electromagnetic force of the coil 36 for more accurate adjustment of the mask.
However, it should be noted that in view of the great distance of the light mask 22 from the record 10, the motion of the object formed by the pin hole in mask 22 relative to the motion of the light spot image in the focus plane is equal to the square of the magnification which is approximately 10. m ere-fore, the mask 22 must move about 100 times farther than the resulting move-ment of the focus plane of the light spot on the record. This enables accurate adj~stment of the focus plane which is required for selective playback of one of the data layers in view of the extremely small distances between data layers.
The light spot focused on the record is scanned along one line 35 of the data track without overlapping adjacent track lines. This scanning in a longitudinal or "X" direction along the track lines is accomplished by ., . .. . . - . .................. . ..... . .
`' lO~slsn4 rotation of the scanner wheel 28 at a speed of about 2500 RPM for a four and one-half inch radius to the center of the objective lenses. To scan from line to line in the transverse or "Y" direction, the data record 10 is moved glowly downward in the direction of arrow 41 in any suitable manner, such as by a worm gear apparatus 42 which moves a carriage 44 supporting the record and is suitably geared to the motor 32. The speed of longitudinal movement of the record 10 is about 420 microns per second for playing back a television signal on a record five inches wide. As a result, each objective lens 16 scans a separate data track line 35 of the data track on one data layer of the record 10 as the scanner wheel 28 is rotated in the direction of arrow 43.
me scanning light beam 18 is reflected from the data spots or the surrounding background as a modulated readout light beam back through the objective lens 16 to the objective mirror 34 and distributor mirror 26 to the beam splitter mirror. The beam splitter mirror 24 reflects the modulated readout light beam 46 to the detector 14 which is a photoelectric cell that produces an electrical output signal corresponding to the modulated light beam. This electrical readout signal is transmitted to the video input of the television receiver or other utilizat~n device connected to the output of the detector through a suitable amplifier and decoder system (not shown).
A "tipping" plate 45 which laterally displaces the light beam 18 by refraction of such beam is provided between the pin hole mask 22 and the beam splitter mirror 24. The tipping plate is pivoted by a galvonometer type motor 47 in response to a tracking signal applied to its input for changing the magnitude and direction of the lateral displacement of the light beam 18 ~.. ..
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1~91~3Q4 in order to cause such beam to stay on the data track being scanned. The tracking signal is produced by a servo system connected to the output of the detector 14, as i9 shown in United States patent application Serial No.
483,131, filed June 26, 1974, by R.A. Walker, now United States Patent 3,9]9,697, issued November 11, 1975.
It should be noted that the light beam 18 is not coaxial with the distributor shaft 30 but strikes the distributor mirrors 26 at a slight back angle which is less than the angle between the reflecting surfaces of such `-mirrors and the shaft axis. As a result the reflected light beam rotates at a speed slightly less than that of shaft 30 and ~ully illuminates the , objective lenses with a substantially uniform intensity over the entire data line 35. This is necessary because if the light beam is parallel to the shaft axis when it strikes the distributor mirrors 26, the reflected beam will rotate at the same speed as the objectire lenses. This would cause the objective lenses to be illuminated with only about one-half the beam ~ intensity at their switching positions where the beam is transferred from one ; lens to another by the distributor.
As shown in Figure 4, one embodiment of the multi-layer optical data record 10 includes a record substrate or base member 48 of a suitable plastic material, glass, ceramic or metal, which may be light opaque for reflective type records or light transparent for light transmission type records. 4 plurality of data layers 50A, 50B, 50C and 50D are provided on one or both sides of the substrate member 48. The data layers are separated by transparent plastic spacer layers 52 which may be made of the same material as the substrate member 48. Each of the data layers has a series track or ~'r~
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',. . ~ ~ .; ' ' parallel tracks of data spots 54 formed by spaced track lines 35 on the record, as shown in Figure 2. The data spots are separated by spaces and may represent binary coded digital information or frequency modulated or pulse width modulated analog information.
The data layers SOA to 50D may be made of photosensitive material, such as photographic film, in which case the spacer layers are provided as the film backing. However, the data layers may also be made by other suitable recording material including printing ink, in which case the data spots 54 could be made of light opaque black material and the background made of transparent material for light transmissive type records. However, the data spots 54 may also be made of light reflecting metal material formed by vapor deposition through a mask having apertures corresponding to the data spots, or by etching through a photoresist mask formed by exposure to a light image of the data spots in a conventional manner such as is used to form etched electrical circuit boards. The thickness of the spacer layers 52 is greater than the depth of focus of the objective lenses 16 so that when the light beam 18 is focused on one of the data layers, the remaining data layers are out of focus and do not block the light beam appreciably, as shown in Figure 4. A protective layer 56 of transparent plastic is provided over the outermost data layer 50A to provide protection against mechanical abrasion of the data layers and to prevent the dust which settles on the surface of the record from blocking light to the data layers, by spacing the dust from such data layers. Thus, any dust which collects on the outer su~rface of the protective layer 56 is out of focus with respect to the light spot focused on any of the data layers. For this reason, the protective _g_ . .
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109180~
coating 56 may ha~e a coating of about lO mils while the spacer layers 52 may have a thickness of about 5 mils and the substrate base member 48 has a thickness of about l/8 inch, depending upon the material used for such sub-strate.
When the record of Figure 4 is of a light transmissive type record, the data spots 54 are preferably made of light opaque material, while the surrounding background areas of the data layers are made of light transparent material, as is the record substrate 48. This light transmissive type record may be played back by modifying the playback apparatus of Figure l, as shown :: lO in Figure 3. Thus, the light detector 14 is moved to the opposite side of the record lO from the light source 12 and aligned with the light beam trans-mitted through the record ]0 by the objective lens 16. An arcuate lens seg-ment 58 is positioned between the detector 14 and the record, such lens segment having a short focal length on the order of six inches and a field of view which covers the ontire width of the record element lO, as shown in Figure 3A, so that such lens may be held in a fixed position during scanning.
The arcuate lens segment 58 is cut from a large circular lens shown by dashed lines 59 in Figure 3A. It should be noted that the beam splitting mirror 24 is eliminated in the embodiment of Figure 3.
While the selection means including coil 36 and its control circuit 37 may be employed to change the focus of the light beam 18 onto different data layers in the playback apparatus of Figure 3 just as in the embodiment of Figure l, another selection means consisting of a plurality of different colored filters 60 and 62 equal in number to the data layers is shown in Figure 3. In this case, the light source 12 is not a laser, but a suitable , - :
' ' ~ ' ' .':' ' -- 10~91804 source of intense "white" light of many frequencies, and the record element lO includes data layers of different optical properties, such as different colored dyes or different colored photoluminescent materials, as shown by record lO' in Figure 6.
The record lO' of Figure 6 includes data layers 64A, 64B and 64C
which are directly layered on each other without the use of spacer layers, similar to layers 52 of Figure 4, between such data layers. This is possible because selection of the data layers is not accomplished by changing the focus plane, but by the color filters 60 and 62 in the selection means shown in Figure 3. As stated earlier, the data layers 64A, 64B and 64C are of different optical properties. Thus the data spots in the three data layers may be made of different colored dyes including the subtractive wav~length ;; dyes used in color photographic film or of different light emission wave-length photoluminescent materials in plastic binder layers. The data layers 64A, 64B and 64C are of extremely small thickness on the order of .l mil or less, since they are all within the same field of focus of the light beam.
The filters 60 and 62 equal in number to the data layers are selectively positioned in front of the detector 14 by an electric motor 66 which may be a step motor controlled by a suitable control circuit 68 for properly indexing the filters which are carried on a rotating support plate 70 attached to the motor shaft 72. The filters can be of the additive or band pass type which transmit light of the wave lengths blocked by the colored data spots in the data layers which are formed of subtractive or band reject color dyes. The data spots of different colored dyes can be formed by multiple exposure and development of color photographic film with :. . : ~ : . .
~91804 different colored light beams so that the data layers are provided by the different emulsion layers of such film. However, the data spots of different photoluminescent materials may also be formed by printing or by photoresist etching techniques in a similar manner to the data spots of the record of Figure 4. Also, the record 10' of Figure 6 can be made as a reflective type record and used in the playback apparatus of Figure 1 if a reflective layer i9 provided between the substrate 48 and the bottom data layer 64C in a similar manner to Figure 5.
The record 10" of Figure 5 is a reflective type record similar to that of Figure 4, except that the data bits 54 are made of light opaque material, and a light reflecting metal layer 74 is provided between the sub-strate 48 and a spacer layer 52 beneath the bottom data layer. Thus, the record 10" of Figure 5 is a reflective type record even though neither the data bits 54nor the surrounding background material of the data layers i9 of light reflecting material Of course, the reflecting layer 74 can be pro-vided by the surface of the substrate if such substrate is made of metal, rather than plastic, which may be preferred for dimensional stability.
A fourth embodiment of the multi-layered optical data record 10"' is shown in Figure 7 to be of the direct layered type like that of Figure 6, which does not use spacer layers between its data layers 76A, 76B and 76C, but is formed differently than the embodiment of Figure 6. Thus, the data layers 76A, 76B and 76C in the record of Figure 7 may be formed by evaporating the different colored dyes or photoluminescent material of the data spots through a mask, by mechanical printing or by using a photoresist etching process The lower data layer 76C is applied to the surface of the substrate -. - . . : . . .
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first, then the data layer 76B and finally the upper data. For this reason, the data layer 76B contacts layer 76C and the surface of the substrate through holes in layer 76C in some places, while layer 76A contacts the substrate and both the other layers 76B and 76C. These data layers are formed of materials of different optical properties similar to that of record 10' of Figure 6, including subtractive color dyes or photoluminescent materials which emit different colored light when struck by the readout light beam.
Selective readout of the data layers in the records of Figures 6 and 7 may be accomplished simultaneously by using a plurality of detectors 10 and associated filters and providing beam splitting mirrors in a similar manner to that disclosed in United States Patent 3,891,794, issued June 24, 1975, by J. T. Russell. On those records in which the data spots are trans-parent and the surrounding background areas are opaque or reflective, it will be necessary to make the background areas partially transparent, for example approximately 50% transparent, so that sufficient light can reach the lower data layer to enable playback.
I'he data layers 50 and spacer layers 52 of Figures 4 and 5 can be formed in separate sheéts and glued together and to the substrate member by .j a suitable solvent for the plastic material. However, photographic film 20 strips exposed with different data tracks and developed may be used as both the data layers and the spacer layers since the latter are formed by the transparent film backing layers. The film strips are transmitted through a tank of glue or solvent and then attached to the substrate member and passed through pressure rollers prior to drying. It should be noted that color slide photographic film has a plurality of different color emulsion layers . ... . .
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- . . .: -lO9i804 which can be used directly as the data layers to form a record like that of Fi~ure ~, since chemical development and processing can be carried out through the upper layers. However, in this case, there would be multiple exposures of the film to different colored light beams to form the data tracks on the different data layers. Finally, it should be roted that for records using photoluminescent material of different light emission proper-ties to distinguish between the data layers, the playback light beam may preferably be of ultraviolet light since most conventional photoluminescent materials are more sensitive to ultraviolet.
It will be obvious to those having ordinary skill in the art that many changes may be made in the details of the above-described preferred embodiments of the invention without departing from the basis of the inven-tion. Therefore, the scope of the present invention should only be determined by the following claims.
;-- -14-
,,, Previously it has been suggested in United States Patent 3,430,966 of D.P. Gregg, granted March 4, 1969, and United States Patent 3,518~442 of K.0, Johngon, granted June 30, 1970, to provide an optical data record in which data is recorded by notches in two tracks on opposite sides of a light transmissive substrate member. However, such prior art records and their associated playback apparatus have several disadvantages since the records only have one data layer per side and are read out by transmitting a light .:, beam through the record including a light diffusing layer provided between .~. , ,r 20 the two data layers. As a result, these records cannot store as much data I` as the record of the present invention and are more expensive and difficult ~. .
,,'! to manufacture. Also, the playback apparatus requires separate focusing J optical systems for the light detector and for the light source because they '''! are on opposite sides of the record. mus, the playback apparatus is not as ....
compact as the embodiment of the present invention employing reflective records .,, ' - .
~ ,. . .
. . . . .
,': : . -: ~
because in the latter the detector is positioned on the same side of the record as the light source.
It has been proposed by K, Compaan and P. Kramer in Philips Technical Review, Volume 33, pages 178 to 180, 1973 No. 7, to employ light reflecting optical data records so that the detector and light source may be positioned on the same side of the record and may use common optical elements. However, this record has the disadvantage that optical data is recorded as pits or notches in a single layer which is formed in a conventional manner by pressing the records from a master. As a result, only about thirty minutes of tele-. ...
vision programs can be recorded on a large record of 30 centimeters in dia-,, meter, the size of a conventional long playing phonograph record. The entire surface of the record, including the data pits, is coated with metal for re-flecting the light beam so that several data layers could not be recorded on the same side of the record in the manner of the present invention. The data pits, unlike the background surface, reflect the light beam away from the detector and are detected by the absence of light at the detector 90 that there is a lower signal to noise ratio in the ele~trical readout signal than ,.~,, .
~xi that of the present invention.
- Also of interest as a background on optical data records and play-back systems for fixed records in United States patent 3,501,586, granted ~: March 17, 1970, to J,T. Russell. However, this patent does not disclose multi-layered data records in the manner of the present invention.
` According to one aspect of the invention there is provided a light .- ' beam scanner apparitus comprising: a rotating scanner wheel supported on a rotor shaft; a plurality of lenses and associated first mirrors mounted in , ., j -2-: :,.,;
-;., .... . , ~ . - .. , :. . ~ - - :. ~- . . . . .
- .
10918(~4 lenx_~irror pairs on said scanner wheel; and distributor means mounted on the rotor shaft for distributing a light beam to one of the lens-mirror pairs at a time, ~aid distributor means including a plurality of distributor mirrors spaced around said shaft for reflecting the light beam from one distributor mirror to one of the first mirrors which first reflects said beam through its associated lens.
. According to another aspect of the invention there is provided a : light beam scanner apparatus comprising: a rotating scanner wheel supported on a rotor shaft; a plurality of lenses mounted on said scanner wheel; and distributor means mounted on said rotor shaft for distributing a light beam to oneof said lenses at a time, said dis.tributor means including a plurality : of distributor mirrors spaced around the shaft axis for reflecting the light beam from one distributor mirror to one of ~aid lenses.
Other objects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments thereof and from the attached drawings of which:
Figure 1 is a schematic diagram oP one embodiment of a playback apparatus for a.reflective type of multi-layer optical data record in accord-ance with the present invention;
- 20 Figure 2 is an elevation view taken along the line 2-2 of Figure l;
-. Figure 3 is a schematic diagram of a second embodiment.of a playback - apparatus similar to that of Figure 1 but modified for light tran~missive .
type multi-layer optical data records;
Figure 3A is an elevation view taken along the line 3A-3A of Figure 3.
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gi804 Figure 4 is an enlarged section view of a portion of a multi-layer optical data record with spacer layers between the data layers which may be used in the playback apparatus of Figures 1 or 3;
Figure 5 is an enlarged section view of a portion of another embodiment of the multi-layer optical data record of the present invention with a reflection layer separate from the data layers;
Figure 6 is an enlarged section view of a portion of a third embodi-ment of a multi-layer optical data record without spacer layers; and ' Figure 7 is an enlarged section view of a portion of a fourth embodi-ment of the multi-layer optical data record without spacer layers.
As shown in Figures 1 and 2, a multi-layered cptical data record 10 of the reflective'type, such as that shown in Figure 4 which employs light reflecting material for the data spots or for the background regions surround-ing transparent data spots, is played baek with a playbaek apparatus including a light source 12 d a light deteetor 14 positioned on the same side of the , record. This reflective playback apparatus has the advantages of providing ' a more compact apparatus and enabling the use of at least some of the optieal , elements including the objective lenses 16 in the same light paths for the ; light reflected from the reeord 10 to the detector 14 and for the light trans-~, 20 mitted from souree 12 to the record. This reduees the eost and eauses some of the defeets of the optical system, sueh as lens aberration, to be cancelled `~ as a result of the light beam traversing the elements twiee in opposite dir-,, ' '~ eetions.
The light souree 12 may be a laser whieh produee~ "eoherent" light of one or more narrow freque~ey b~nds, or a suitable souree of intense non-;~ _4-;:~
!
`, ,;.. .. . . . .
:`. . ',. : .:
.`.: ;., . . ~ , . . .
. `. ,: . , ,.-.`
: ;: . -. . - .
1~91804 coherent "white" light of many frequencies, including ultraviolet light, in-frared light, as well as visible light. A light beam 18 is transmitted from source 12 through a primary lens 20 and an apertured light mask commonly re-ferred to as a "pin hole" element 22. Lens 20 focuses the light beam to a sma11 spot at the circular aperture of the pin hole element so that such aperture shapes the light spot and forms the object that is imaged onto the record by the ob.jective lenses 16. me light beam 18 is transmitted through a be~n splitting mirror 24 onto a rotating distributor mirror member 26 whose outer surface is in the form of a five-sided polygon having five mirrors pro-vided thereon which correspond to five objective lenses 16 which are carried on a rotating scanner wheel 28. The distributor mirror member 26 is mounted on the shaft 30 of the scanner wheel 28 so that i~ is rotated with such wheel at a constant speed by an electrical motor 32 coupled thereto. As a result, the distributor mirror member 24 rotates at the same speed as the objective ~ lenses 16 so that one of the mirrors of such distributor member is always ; aligned with its associated objective lens. Thus, the distributor mirror ; member 26 distributes the light beam to the objective lenses 16 one at a time as such lenses rotate across the record 10 to playback one of the data track lines 35 on such record as shown in Figure 2.
The light beam 18 is reflected from one of the distributor mirrors onto one of five objective mirrors 34 mounted on the scanner wheel 28 imme-diately beneath each objective lens 16. As a result, the light beam is re-flected from the objective mirror 34 through its associated objective lens 16 onto the multi-layer optical data record 10. The light beam is focused by lenses 20 and 16 to a small spot in a focus plane on one of the data layers , , ., ,.,- -. :
. ',,.:. ~, ' : :,. ~
..... ' , :~. .
.. , /~. :
~ 1091804 of the record, such spot being of a diameter which is substantially the same size as the ~idth of one of the data track lines 35 of data spots provided on such record.
A selection means is provided for moving the focus plane from one data layer to another to selectively playback the selected data track on such layers. This change in the fo¢us plane may be accomplished by moving the pin hole light mask 22 and the primary lens 20 longitudinally along the beam axis by means of an electromagnetic coil 36 and associated electrical control circuit. The coil 36 attracts or repels a magnetic armature 38 on which the pin hole mask 22 is mounted 30 that it and the lens 20 coupled thereto move toward and away from the record 10. A spring biasing element 40 may be used for mounting the pin hole light mask 22 which resists the electromagnetic force of the coil 36 for more accurate adjustment of the mask.
However, it should be noted that in view of the great distance of the light mask 22 from the record 10, the motion of the object formed by the pin hole in mask 22 relative to the motion of the light spot image in the focus plane is equal to the square of the magnification which is approximately 10. m ere-fore, the mask 22 must move about 100 times farther than the resulting move-ment of the focus plane of the light spot on the record. This enables accurate adj~stment of the focus plane which is required for selective playback of one of the data layers in view of the extremely small distances between data layers.
The light spot focused on the record is scanned along one line 35 of the data track without overlapping adjacent track lines. This scanning in a longitudinal or "X" direction along the track lines is accomplished by ., . .. . . - . .................. . ..... . .
`' lO~slsn4 rotation of the scanner wheel 28 at a speed of about 2500 RPM for a four and one-half inch radius to the center of the objective lenses. To scan from line to line in the transverse or "Y" direction, the data record 10 is moved glowly downward in the direction of arrow 41 in any suitable manner, such as by a worm gear apparatus 42 which moves a carriage 44 supporting the record and is suitably geared to the motor 32. The speed of longitudinal movement of the record 10 is about 420 microns per second for playing back a television signal on a record five inches wide. As a result, each objective lens 16 scans a separate data track line 35 of the data track on one data layer of the record 10 as the scanner wheel 28 is rotated in the direction of arrow 43.
me scanning light beam 18 is reflected from the data spots or the surrounding background as a modulated readout light beam back through the objective lens 16 to the objective mirror 34 and distributor mirror 26 to the beam splitter mirror. The beam splitter mirror 24 reflects the modulated readout light beam 46 to the detector 14 which is a photoelectric cell that produces an electrical output signal corresponding to the modulated light beam. This electrical readout signal is transmitted to the video input of the television receiver or other utilizat~n device connected to the output of the detector through a suitable amplifier and decoder system (not shown).
A "tipping" plate 45 which laterally displaces the light beam 18 by refraction of such beam is provided between the pin hole mask 22 and the beam splitter mirror 24. The tipping plate is pivoted by a galvonometer type motor 47 in response to a tracking signal applied to its input for changing the magnitude and direction of the lateral displacement of the light beam 18 ~.. ..
~ -7-~ .......... ~ ................... . . .
:
1~91~3Q4 in order to cause such beam to stay on the data track being scanned. The tracking signal is produced by a servo system connected to the output of the detector 14, as i9 shown in United States patent application Serial No.
483,131, filed June 26, 1974, by R.A. Walker, now United States Patent 3,9]9,697, issued November 11, 1975.
It should be noted that the light beam 18 is not coaxial with the distributor shaft 30 but strikes the distributor mirrors 26 at a slight back angle which is less than the angle between the reflecting surfaces of such `-mirrors and the shaft axis. As a result the reflected light beam rotates at a speed slightly less than that of shaft 30 and ~ully illuminates the , objective lenses with a substantially uniform intensity over the entire data line 35. This is necessary because if the light beam is parallel to the shaft axis when it strikes the distributor mirrors 26, the reflected beam will rotate at the same speed as the objectire lenses. This would cause the objective lenses to be illuminated with only about one-half the beam ~ intensity at their switching positions where the beam is transferred from one ; lens to another by the distributor.
As shown in Figure 4, one embodiment of the multi-layer optical data record 10 includes a record substrate or base member 48 of a suitable plastic material, glass, ceramic or metal, which may be light opaque for reflective type records or light transparent for light transmission type records. 4 plurality of data layers 50A, 50B, 50C and 50D are provided on one or both sides of the substrate member 48. The data layers are separated by transparent plastic spacer layers 52 which may be made of the same material as the substrate member 48. Each of the data layers has a series track or ~'r~
:r~ -8-.. . .
,, .
',. . ~ ~ .; ' ' parallel tracks of data spots 54 formed by spaced track lines 35 on the record, as shown in Figure 2. The data spots are separated by spaces and may represent binary coded digital information or frequency modulated or pulse width modulated analog information.
The data layers SOA to 50D may be made of photosensitive material, such as photographic film, in which case the spacer layers are provided as the film backing. However, the data layers may also be made by other suitable recording material including printing ink, in which case the data spots 54 could be made of light opaque black material and the background made of transparent material for light transmissive type records. However, the data spots 54 may also be made of light reflecting metal material formed by vapor deposition through a mask having apertures corresponding to the data spots, or by etching through a photoresist mask formed by exposure to a light image of the data spots in a conventional manner such as is used to form etched electrical circuit boards. The thickness of the spacer layers 52 is greater than the depth of focus of the objective lenses 16 so that when the light beam 18 is focused on one of the data layers, the remaining data layers are out of focus and do not block the light beam appreciably, as shown in Figure 4. A protective layer 56 of transparent plastic is provided over the outermost data layer 50A to provide protection against mechanical abrasion of the data layers and to prevent the dust which settles on the surface of the record from blocking light to the data layers, by spacing the dust from such data layers. Thus, any dust which collects on the outer su~rface of the protective layer 56 is out of focus with respect to the light spot focused on any of the data layers. For this reason, the protective _g_ . .
:
.. . ..
109180~
coating 56 may ha~e a coating of about lO mils while the spacer layers 52 may have a thickness of about 5 mils and the substrate base member 48 has a thickness of about l/8 inch, depending upon the material used for such sub-strate.
When the record of Figure 4 is of a light transmissive type record, the data spots 54 are preferably made of light opaque material, while the surrounding background areas of the data layers are made of light transparent material, as is the record substrate 48. This light transmissive type record may be played back by modifying the playback apparatus of Figure l, as shown :: lO in Figure 3. Thus, the light detector 14 is moved to the opposite side of the record lO from the light source 12 and aligned with the light beam trans-mitted through the record ]0 by the objective lens 16. An arcuate lens seg-ment 58 is positioned between the detector 14 and the record, such lens segment having a short focal length on the order of six inches and a field of view which covers the ontire width of the record element lO, as shown in Figure 3A, so that such lens may be held in a fixed position during scanning.
The arcuate lens segment 58 is cut from a large circular lens shown by dashed lines 59 in Figure 3A. It should be noted that the beam splitting mirror 24 is eliminated in the embodiment of Figure 3.
While the selection means including coil 36 and its control circuit 37 may be employed to change the focus of the light beam 18 onto different data layers in the playback apparatus of Figure 3 just as in the embodiment of Figure l, another selection means consisting of a plurality of different colored filters 60 and 62 equal in number to the data layers is shown in Figure 3. In this case, the light source 12 is not a laser, but a suitable , - :
' ' ~ ' ' .':' ' -- 10~91804 source of intense "white" light of many frequencies, and the record element lO includes data layers of different optical properties, such as different colored dyes or different colored photoluminescent materials, as shown by record lO' in Figure 6.
The record lO' of Figure 6 includes data layers 64A, 64B and 64C
which are directly layered on each other without the use of spacer layers, similar to layers 52 of Figure 4, between such data layers. This is possible because selection of the data layers is not accomplished by changing the focus plane, but by the color filters 60 and 62 in the selection means shown in Figure 3. As stated earlier, the data layers 64A, 64B and 64C are of different optical properties. Thus the data spots in the three data layers may be made of different colored dyes including the subtractive wav~length ;; dyes used in color photographic film or of different light emission wave-length photoluminescent materials in plastic binder layers. The data layers 64A, 64B and 64C are of extremely small thickness on the order of .l mil or less, since they are all within the same field of focus of the light beam.
The filters 60 and 62 equal in number to the data layers are selectively positioned in front of the detector 14 by an electric motor 66 which may be a step motor controlled by a suitable control circuit 68 for properly indexing the filters which are carried on a rotating support plate 70 attached to the motor shaft 72. The filters can be of the additive or band pass type which transmit light of the wave lengths blocked by the colored data spots in the data layers which are formed of subtractive or band reject color dyes. The data spots of different colored dyes can be formed by multiple exposure and development of color photographic film with :. . : ~ : . .
~91804 different colored light beams so that the data layers are provided by the different emulsion layers of such film. However, the data spots of different photoluminescent materials may also be formed by printing or by photoresist etching techniques in a similar manner to the data spots of the record of Figure 4. Also, the record 10' of Figure 6 can be made as a reflective type record and used in the playback apparatus of Figure 1 if a reflective layer i9 provided between the substrate 48 and the bottom data layer 64C in a similar manner to Figure 5.
The record 10" of Figure 5 is a reflective type record similar to that of Figure 4, except that the data bits 54 are made of light opaque material, and a light reflecting metal layer 74 is provided between the sub-strate 48 and a spacer layer 52 beneath the bottom data layer. Thus, the record 10" of Figure 5 is a reflective type record even though neither the data bits 54nor the surrounding background material of the data layers i9 of light reflecting material Of course, the reflecting layer 74 can be pro-vided by the surface of the substrate if such substrate is made of metal, rather than plastic, which may be preferred for dimensional stability.
A fourth embodiment of the multi-layered optical data record 10"' is shown in Figure 7 to be of the direct layered type like that of Figure 6, which does not use spacer layers between its data layers 76A, 76B and 76C, but is formed differently than the embodiment of Figure 6. Thus, the data layers 76A, 76B and 76C in the record of Figure 7 may be formed by evaporating the different colored dyes or photoluminescent material of the data spots through a mask, by mechanical printing or by using a photoresist etching process The lower data layer 76C is applied to the surface of the substrate -. - . . : . . .
' ` ', `''`''' ', ' ''' : `. ~ '-. . .
:
first, then the data layer 76B and finally the upper data. For this reason, the data layer 76B contacts layer 76C and the surface of the substrate through holes in layer 76C in some places, while layer 76A contacts the substrate and both the other layers 76B and 76C. These data layers are formed of materials of different optical properties similar to that of record 10' of Figure 6, including subtractive color dyes or photoluminescent materials which emit different colored light when struck by the readout light beam.
Selective readout of the data layers in the records of Figures 6 and 7 may be accomplished simultaneously by using a plurality of detectors 10 and associated filters and providing beam splitting mirrors in a similar manner to that disclosed in United States Patent 3,891,794, issued June 24, 1975, by J. T. Russell. On those records in which the data spots are trans-parent and the surrounding background areas are opaque or reflective, it will be necessary to make the background areas partially transparent, for example approximately 50% transparent, so that sufficient light can reach the lower data layer to enable playback.
I'he data layers 50 and spacer layers 52 of Figures 4 and 5 can be formed in separate sheéts and glued together and to the substrate member by .j a suitable solvent for the plastic material. However, photographic film 20 strips exposed with different data tracks and developed may be used as both the data layers and the spacer layers since the latter are formed by the transparent film backing layers. The film strips are transmitted through a tank of glue or solvent and then attached to the substrate member and passed through pressure rollers prior to drying. It should be noted that color slide photographic film has a plurality of different color emulsion layers . ... . .
..
~ ~,' '' '~"': ''` ' : ' '`
- . . .: -lO9i804 which can be used directly as the data layers to form a record like that of Fi~ure ~, since chemical development and processing can be carried out through the upper layers. However, in this case, there would be multiple exposures of the film to different colored light beams to form the data tracks on the different data layers. Finally, it should be roted that for records using photoluminescent material of different light emission proper-ties to distinguish between the data layers, the playback light beam may preferably be of ultraviolet light since most conventional photoluminescent materials are more sensitive to ultraviolet.
It will be obvious to those having ordinary skill in the art that many changes may be made in the details of the above-described preferred embodiments of the invention without departing from the basis of the inven-tion. Therefore, the scope of the present invention should only be determined by the following claims.
;-- -14-
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A light beam scanner apparatus comprising:
a rotating scanner wheel supported on a rotor shaft;
a plurality of lenses and associated first mirrors mounted in lens-mirror pairs on said scanner wheel; and distributor means mounted on the rotor shaft for distributing a light beam to one of the lens-mirror pairs at a time, said distributor means including a plurality of distributor mirrors spaced around said shaft for reflecting the light beam from one distributor mirror to one of the first mirrors which first reflects said beam through its associated lens.
a rotating scanner wheel supported on a rotor shaft;
a plurality of lenses and associated first mirrors mounted in lens-mirror pairs on said scanner wheel; and distributor means mounted on the rotor shaft for distributing a light beam to one of the lens-mirror pairs at a time, said distributor means including a plurality of distributor mirrors spaced around said shaft for reflecting the light beam from one distributor mirror to one of the first mirrors which first reflects said beam through its associated lens.
2. Scanner apparatus in accordance with claim 1 which also includes a light means for directing a light beam onto the distributor mirrors at an angle less than the angle formed by the shaft axis with the planes of said distributor mirrors.
3. Scanner apparatus in accordance with claim 1 which also includes light detector means for receiving light reflected from a record being scanned after said reflected light is transmitted back through the same lens-mirror pair through which the light is directed to said record.
4. A light beam scanner apparatus comprising:
a rotating scanner wheel supported on a rotor shaft;
a plurality of lenses mounted on said scanner wheel; and distributor means mounted on said rotor shaft for distributing a light beam to one of said lenses at a time, said distributor means including a plurality of distributor mirrors spaced around the shaft axis for reflecting the light beam from one distributor mirror to one of said lenses.
a rotating scanner wheel supported on a rotor shaft;
a plurality of lenses mounted on said scanner wheel; and distributor means mounted on said rotor shaft for distributing a light beam to one of said lenses at a time, said distributor means including a plurality of distributor mirrors spaced around the shaft axis for reflecting the light beam from one distributor mirror to one of said lenses.
5. Scanner apparatus in accordance with claim 4 which includes another mirror means in the light path between said distributor mirrors and said lenses.
6. Scanner apparatus in accordance with claim 4 which also includes a light means for directing the light beam onto the distributor mirrors at an angle less than the angle formed by the shaft axis with the planes of said distributor mirrors.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US51645374A | 1974-10-21 | 1974-10-21 | |
| US516,453 | 1974-10-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1091804A true CA1091804A (en) | 1980-12-16 |
Family
ID=24055665
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA232,631A Expired CA1078060A (en) | 1974-10-21 | 1975-07-31 | Multi-layered optical data records and playback apparatus |
| CA342,948A Expired CA1091804A (en) | 1974-10-21 | 1980-01-03 | Multi-layered optical data records and playback apparatus |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA232,631A Expired CA1078060A (en) | 1974-10-21 | 1975-07-31 | Multi-layered optical data records and playback apparatus |
Country Status (5)
| Country | Link |
|---|---|
| JP (2) | JPS5231610A (en) |
| CA (2) | CA1078060A (en) |
| DE (1) | DE2546941A1 (en) |
| GB (1) | GB1516413A (en) |
| NL (1) | NL7510462A (en) |
Families Citing this family (12)
| 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 |
| NL7803069A (en) * | 1978-03-22 | 1979-09-25 | Philips Nv | MULTI-LAYER INFORMATION DISK. |
| FR2488711B1 (en) * | 1980-08-13 | 1985-06-28 | Thomson Csf | THERMO-OPTICAL INFORMATION RECORDING PROCESS AND INFORMATION MEDIUM FOR CARRYING OUT SAID METHOD |
| JPS59210544A (en) * | 1983-05-16 | 1984-11-29 | Nec Corp | Optical recording medium |
| US4639745A (en) * | 1984-01-11 | 1987-01-27 | Pioneer Electronic Corporation | Optical recording medium |
| US4745484A (en) * | 1986-07-30 | 1988-05-17 | Drexler Technology Corporation | Method and apparatus for stepped imaging in reading data |
| EP0434230B1 (en) * | 1989-11-22 | 1996-05-22 | Sharp Kabushiki Kaisha | Optical recording medium and method of recording and reproducing information thereon |
| US5373499A (en) * | 1993-07-22 | 1994-12-13 | International Business Machines Corporation | Multilayer optical disk and system having multiple optical paths include identical total disk substrate thickness |
| US5644555A (en) * | 1995-01-19 | 1997-07-01 | International Business Machines Corporation | Multiple data surface magneto-optical data storage system |
| JPH09161320A (en) * | 1995-12-08 | 1997-06-20 | Nippon Columbia Co Ltd | Stuck type optical information recording medium |
| FR2765716B1 (en) * | 1997-07-02 | 1999-07-30 | Commissariat Energie Atomique | OPTICAL TWO-LEVEL OPTICAL RECORDING MEDIUM, CORRESPONDING RECORDING DEVICE AND READING METHOD |
| GB2428130A (en) * | 2005-07-06 | 2007-01-17 | Univ Basel | Photographic storage of digital information |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5229603B2 (en) * | 1971-08-10 | 1977-08-03 | ||
| JPS5828652B2 (en) * | 1972-12-25 | 1983-06-17 | 萬世工業株式会社 | Yomitori Sochi |
-
1975
- 1975-07-31 CA CA232,631A patent/CA1078060A/en not_active Expired
- 1975-08-04 GB GB32589/75A patent/GB1516413A/en not_active Expired
- 1975-09-04 NL NL7510462A patent/NL7510462A/en not_active Application Discontinuation
- 1975-10-20 DE DE19752546941 patent/DE2546941A1/en not_active Ceased
- 1975-10-21 JP JP50126026A patent/JPS5231610A/en active Granted
-
1980
- 1980-01-03 CA CA342,948A patent/CA1091804A/en not_active Expired
-
1984
- 1984-02-17 JP JP59027369A patent/JPS59223949A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59223949A (en) | 1984-12-15 |
| GB1516413A (en) | 1978-07-05 |
| CA1078060A (en) | 1980-05-20 |
| NL7510462A (en) | 1976-04-23 |
| JPS6118392B2 (en) | 1986-05-12 |
| JPS5231610A (en) | 1977-03-10 |
| DE2546941A1 (en) | 1976-04-29 |
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