GB2138991A - High density information record - Google Patents
High density information record Download PDFInfo
- Publication number
- GB2138991A GB2138991A GB08409690A GB8409690A GB2138991A GB 2138991 A GB2138991 A GB 2138991A GB 08409690 A GB08409690 A GB 08409690A GB 8409690 A GB8409690 A GB 8409690A GB 2138991 A GB2138991 A GB 2138991A
- Authority
- GB
- United Kingdom
- Prior art keywords
- dimethylpolysiloxane
- high density
- record
- density information
- thermoplastic resin
- 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.)
- Granted
Links
- 235000013870 dimethyl polysiloxane Nutrition 0.000 claims abstract description 29
- 239000004205 dimethyl polysiloxane Substances 0.000 claims abstract description 29
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 claims abstract description 29
- 239000000314 lubricant Substances 0.000 claims abstract description 15
- 239000011342 resin composition Substances 0.000 claims abstract description 15
- 229920005992 thermoplastic resin Polymers 0.000 claims abstract description 14
- 239000004020 conductor Substances 0.000 claims abstract description 10
- 239000000758 substrate Substances 0.000 claims abstract description 10
- 239000006229 carbon black Substances 0.000 claims description 5
- 229920005989 resin Polymers 0.000 abstract description 4
- 239000011347 resin Substances 0.000 abstract description 4
- 238000000034 method Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 230000006866 deterioration Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000000465 moulding Methods 0.000 description 4
- 239000000654 additive Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 2
- 238000013019 agitation Methods 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 239000008188 pellet Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- TVEXGJYMHHTVKP-UHFFFAOYSA-N 6-oxabicyclo[3.2.1]oct-3-en-7-one Chemical compound C1C2C(=O)OC1C=CC2 TVEXGJYMHHTVKP-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004709 Chlorinated polyethylene Substances 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 241001422033 Thestylus Species 0.000 description 1
- 229920002433 Vinyl chloride-vinyl acetate copolymer Polymers 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229920000800 acrylic rubber Polymers 0.000 description 1
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009395 breeding Methods 0.000 description 1
- 230000001488 breeding effect Effects 0.000 description 1
- KRGNPJFAKZHQPS-UHFFFAOYSA-N chloroethene;ethene Chemical group C=C.ClC=C KRGNPJFAKZHQPS-UHFFFAOYSA-N 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- -1 dibutyl tin mercapto ester Chemical class 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 229920001038 ethylene copolymer Polymers 0.000 description 1
- 150000002191 fatty alcohols Chemical class 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 239000012760 heat stabilizer Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 238000005453 pelletization Methods 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 description 1
- 229920005670 poly(ethylene-vinyl chloride) Polymers 0.000 description 1
- 229920005671 poly(vinyl chloride-propylene) Polymers 0.000 description 1
- 229920001197 polyacetylene Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/54—Silicon-containing compounds
- C08K5/541—Silicon-containing compounds containing oxygen
- C08K5/5415—Silicon-containing compounds containing oxygen containing at least one Si—O bond
- C08K5/5419—Silicon-containing compounds containing oxygen containing at least one Si—O bond containing at least one Si—C bond
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
- C08K3/04—Carbon
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B9/00—Recording or reproducing using a method not covered by one of the main groups G11B3/00 - G11B7/00; Record carriers therefor
- G11B9/06—Recording or reproducing using a method not covered by one of the main groups G11B3/00 - G11B7/00; Record carriers therefor using record carriers having variable electrical capacitance; Record carriers therefor
- G11B9/061—Record carriers characterised by their structure or form or by the selection of the material; Apparatus or processes specially adapted for the manufacture of record carriers
- G11B9/063—Record carriers characterised by their structure or form or by the selection of the material; Apparatus or processes specially adapted for the manufacture of record carriers characterised by the selection of the material
- G11B9/068—Moulding resin compositions
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Lubricants (AREA)
Abstract
A high density information record of the electrostatic capacitance type which comprises a record substrate on which signal information is recorded as geometric variations. The substrate is made of a conductive resin composition comprising a thermoplastic resin, a conductive material, and a defined amount of dimethylpolysiloxane lubricant having a viscosity smaller than 50 cps at 25 DEG C. Specific resins and conductive materials are specified, as are concentrations and preparation.
Description
SPECIFICATION
High density information record
This invention relates to playback systems of a variable electrostatic capacitance form and more particularly to, high density information records, such as video disc or digital audio discs, on which signal information is recorded as geometric variations.
In certain information playback systems, signal information is encoded as geometric variations or pits in a spiral plane or groove or in concentric planes or grooves on an information recording medium. The medium on which the signal information has been recorded is reproduced as follows. When a pickup stylus such as of diamond having an electrode is scanned relative to a recorded track of the medium, capative variations are established between the pickup stylus and the medium due to the geometric variations in the plane or groove.
Several types of information records have been proposed for use in the above-described type of electrostatic capacitance playback system. In one such record medium, an electrode is provided on the surface of a record substrate on which geometric variations are press molded according to signal information. This permits formation of an electrostatic capacitance to be established between the record electrode and the stylus electrode. For instance, the record substrate is covered with a thin metallic film of several hundreds angstrom in thickness and a several hundred angstrom thick dielectric layer overlying the metallic film. The dielectric layer serves to prevent short circuiting of the electrodes and increase the dielectric constant between the electrodes.The record of the above-described type needs a number of fabricating steps including a press molding of the recording medium substrate, steps of depositing the thin metallic film and the dielectric layer, and the like. Thus, the fabrication is complicate and troublesome with the need of a relatively large-scale manufacturing apparatus. Thus, production cost becomes very high.
Another type of known information record of the electrostatic capacitance form is one which is obtained by press molding a conductive plastic composition comprising a resin such as polyvinyl chloride in admixture with a conductive material such as carbon black so that signal information is recorded as geometric variations. This record is fabricated without needing the step of depositing a thin metallic film because the record itself is conductive and an electrostatic capacitance is formed between the electrode of a pickup stylus and the record. Moreover, fine carbon black powder is substantially covered with the resin, so that any dielectric layer is not necessary. In view of the above, this type of record is very simple in manufacture and can be manufactured at low cost.
However, when the record made of the conductive resin composition is mounted in a playback system and reproduced over a long term, its surface is worn by means of the pickup stylus contacting therewith. This results in deformation of the geometric variations or pits formed on the record, causing capative variations to change. Thus, reliable playback is not possible. Especially, when a video disc is subjected to still reproduction or freeze frame, a given portion of the disc is repeatedly contacted with a pickup stylus at a pressure of 400 to 500 Kg/cm2 at a rate of 15 times/second, causing the disc surface to be considerably worn.
In addition, the existing conductive resin composition is not so high in moldability.
We have made extensive studies on conductive resin compositions suitable for high density information record and particularly on lubricants being added to the resin compositions. It was found that some lubricants do not show satisfactory effects of lubrication and cause breeding, thus leading to a lowering in quality of the playback image. Alternatively, some lubricants produce several disadvantages in that resin compositions comprising such lubricants are not satisfactorily kneaded in continuous kneaders or extruders now suitably molded in press molding machines.
It is accordingly an object of the invention to provide high density information records which are made of a conductive resin composition comprising a specific type of lubricant.
It is another object of the invention to provide high density information records of the electrostatic capacitance type in which signal information is recorded by means of geometric variations and in which the geometric variations are rarely deformed because the record is resistant to wear and thus reliable playback of the signal information is ensured.
It is a further object of the invention to provide high density information records made of conductive resin compositions comprising dimethylpolysiloxane which are readily press molded into video or digital audio discs.
The present invention is characterized by use of dimethylpolysiloxane as a lubricant in conductive resin compositions for high density information record. More particularly, the present invention provides a high density information record of the electrostatic capacitance type which comprises a record substrate on which signal information is recorded as geometric variations, the substrate being made of a conductive resin composition comprising a thermoplastic resin, a conductive material used in an amount of 5 to 30 percent by weight based on the thermoplastic resin and a dimethylpolysiloxane lubricant having a viscosity smaller than 50 cps at 25 C, the lubricant being used in an amount of 0.3 to 2.9 percent by weight based on the thermoplastic resin. The term 'high density information record' used herein is intended to mean video or digital audio discs.
As described above, the conductive resin composition of for high density information records comprises dimethylpolysiloxane as a lubricant. The dimethylpolysiloxane used in the practice of the invention should have a viscosity smaller than 50 cps at a temperature of 25"C. Preferably, the viscosity is not larger than 40 cps and most preferably in the range of 10 to 30 cps. To satisfy the viscosity requirement, the dimethylpolysiloxane should have a degree of polymerization of not larger than 60. Dimethylpolysiloxane is used in an amount of 0.3 to 2.0 percent by weight, preferably 0.45 to 1.5 percent by weight, on the basis of a thermoplastic resin contained in the conductive resin composition.
If the viscosity of dimethylpolysiloxane is larger than the above-defined value, a satisfactory wear resistance cannot be obtained. Especially, when the composition is used to make a video disc, the disc deteriorates in signal-to-noise ratio in several tens minutes when subjected to a freeze frame or still reproduction test and may sometimes cause tracking errors. On the contrary, when dimethylpolysiloxane has too small a viscosity of, for example, 2 cps, the resulting information record becomes poor in wear resistance.
As defined above, the amount of the lubricant is from 0.3 to 2.0 percent by weight of thermoplastic resin used. Larger amounts may improve the wear resistance to a slight extent but upon press molding, dimethylpolysiloxane exudes and attaches to stamper surfaces. Geometric variations being formed on a record substrate may not be formed accurately, causing tracking errors. On the other hand, smaller amounts result in a smaller effect of addition of dimethylpolysiloxane.
The thermoplastic resins useful for the purposes of the invention include, for example, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, vinyl chloride-ethylene copolymers, vinyl chloride-propylene copolymers, vinyl chloride-alkyl acrylate copolymers, acrylonitrile-styrene-vinyl chloride copolymers, ethylene-vinyl acetate copolymers grafted with vinyl chloride, and the like.
The conductive material used in the conductive resin composition is typically carbon black. Other materials including metals such as copper, gold, platinum and organic materials such as polyacetylene may be also used in powder form. In order to impart a suitable electric conductivity to the composition, the conductive material is generally used in an amount of from 5 to 30 percent by weight of thermoplastic resin though the amount may depend on the type of conductive material, the type of thermoplastic resin and the purpose.
Aside from the essential three components described above, additives ordinarily used for these purposes may be also added to the composition in amounts not impeding the effects of the essential components.
Examples of such additives include heat stabilizers, plasticizers, other lubricants, and the like.
The conductive resin composition is prepared by a usual manner. For instance, a predetermined amount of a thermoplastic resin is mixed with predetermined amounts of dimethylpolysiloxane and other additives in a mixer or blender at high agitation speed until the system is heated to from 80 to 135 followed by adding a predetermined amount of carbon black or the like conductive material and further mixing. The resulting mixture is pelletized by a suitable pelletizer. The pellets are used to press a video or audio disc. These mixing, pelletizing and pressing techniques are well known in the art and are not further described herein.
The present invention is described in detail by way of examples.
Example 7 One hundred parts by weight of ethylene-vinyl chloride copolymer having an average degree of polymerization of 430 and an ethylene content of 1.5% (VE-N, by Tokuyama Sekisui Ind, Co., Ltd.), 5 parts by weight of chlorinated polyethylene (Elaslen 301A, by Showa Denko Co., Ltd.), 5 parts by weight of dibutyl tin mercapto ester stabilizer (STAN N JF-95K, by Sankyo Organic Chemicals Co., Ltd.), 1.5 parts by weight of a polyester lubricant (Loxiol G-70, by Nippon Henkel Co., Ltd.), 0.5 part by weight of a fatty alcohol and dibasic acid ester (Loxiol G-60, Nippon Henkel Co., Ltd.), and 0.4 part by weight of dimethylpolysiloxane (KF-96, by
Shinetsu Chem.Co., Ltd.) having a viscosity of 30 cps at 25"C were placed in a 20 liter Henschel mixer and blended at high agitation speed until the blend was heated to 110 C. Subsequently, the mixer was operated at low speed to cool the content down to 700C, followed by adding 20 parts by weight of conductive carbon black (Ketjen Black EC, by Japan EC, Ltd.) and blending at 11 00C for 15 minutes. Thereafter, the mixer was operated at low speed until the content was cooled down to 500C. The resulting blend was pelletized by means of a kneader PR46 available from Buss Co., Ltd. Switzerland. The resulting pellets were press molded in a press machine for video disc to obtain video discs having video singal information in a spiral groove on the surface thereof.
Example 2
The general procedure of Example 1 was repeated using 0.4 part by weight of dimethylpolysiloxane having a viscosity of 20 cps at 25"C instead of the dimethylpolysiloxane used in Example 1, thereby obtaining video discs.
Example 3
The general procedure of Example 1 was repeated using 0.4 part by weight of dimethylpolysiloxane having a viscosity of 10 cps at 250C instead of the dimethylpolysiloxane used in Example 1, thereby obtaining video discs.
Example 4
The general procedure of Example 2 was repeated except that the amount of the dimethylpolysiloxane was 0.7 part by weight, thereby obtaining video discs.
Example 5
The general procedure of Example 2 was repeated except that the amount of the dimethylpolysiloxane was 1.5 parts by weight, thereby obtaining video discs.
Example 6
The general procedure of Example 1 was repeated using 0.4 part by weight of dimethylpolysiloxane having a viscosity of 2 cps a 25 C instead of the dimethylpolysiloxane used in Example 1, thereby obtaining video discs.
Comparative Example 1
The general procedure of Example 1 was repeated using 0.4 part by weight of dimethylpolysiloxane having a viscosity of 50 cps a 250C instead of the dimethylpolysiloxane used in Example 1, thereby obtaining video discs.
Comparative Example 2
The general procedure of Comparative Example 1 was repeated using 1.5 parts by weight of the dimethylpolysiloxane, thereby obtain video discs.
The video discs obtained in the above examples and comparative examples were checked with respect to moldability. Moreover, the discs were each subjected to an one hour still reproduction test to determine a degree of wear or a degree of deterioration of signal-to-noise ratio. During the test, there was measured a Y signal-to-noise ratio of each disc at gray 501RE recorded at a position thereof where it took 54 minutes from the outermost track of the video disc. The degree of deterioration of signal-to-noise ratio was determined such that ten to twelve video discs of the respective examples and comparative examples were provided.
Each disc was tested three times while changing the track every hour. Thirty to thirty six measurements were effected, in total, on the video discs of each of the examples and comparative examples. The discs whose degree of deterioration was within 3dB were determined as acceptable, whereas determined as unacceptable were discs whose degree was over 3 dB or in which the jump of the styl us took place. The degree of deterioration is shown in Table as acceptance rate by percent.
TABLE
Dimethylpolysiloxane Acceptance Moldability
Amount Viscosity Rate
(parts by (cps) (%)
weight)
Example 1 0.4 30 61 Moderate
Example 2 0.4 20 72 Good
Example3 0.4 10 45 Good
Example 4 0.7 20 100 Good
Example 5 1.5 20 100 Moderate
Example 6 0.4 2 28 Good
Com.Ex.1 0.4 50 25 Moderate
Com.Ex.2 1.5 50 Non-measurable Poor
As will be seen from the above results, use of dimethylpolysiloxane is effective in making high density information records within defined ranges with respect to the viscosity and amount.
Claims (3)
1. A high density information record of the electrostatic capacitance type which comprises a record substrate on which signal information is recorded as geometric variations, the substrate being made of a conductive resin composition comprising a thermoplastic resin, a conductive material used in an amount of from 5 to 30 percent by weight based on the thermoplastic resin and a dimethylpolysiloxane lubricant having a viscosity smaller than 50 cps at 25 C, the lubricant being used in an amount of 0.3 to 2.0 percent by weight based on the thermoplastic resin.
2. The high density information record according to Claim 1, wherein said conductive material is carbon black.
3. The high density information record according to Claim 1, wherein said dimethylpolysiloxane has a viscosity ranging from 10 to 30 cps at 250C and is used in an amount of 0.45 to 1.5 wt% based on said thermoplastic resin.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6444083A JPS59191152A (en) | 1983-04-14 | 1983-04-14 | Recording medium for high density information signal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2138991A true GB2138991A (en) | 1984-10-31 |
| GB2138991B GB2138991B (en) | 1986-12-10 |
Family
ID=13258338
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08409690A Expired GB2138991B (en) | 1983-04-14 | 1984-04-13 | High density information record |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS59191152A (en) |
| DE (1) | DE3414053A1 (en) |
| FR (1) | FR2544533B1 (en) |
| GB (1) | GB2138991B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0181753A3 (en) * | 1984-11-02 | 1987-06-16 | Victor Company Of Japan, Limited | High density information record medium |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0524399U (en) * | 1991-09-02 | 1993-03-30 | コクヨ株式会社 | Picture frame |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2037054A (en) * | 1978-11-13 | 1980-07-02 | Rca Corp | Video discs and moulding compositions therefor |
| GB1574595A (en) * | 1977-03-15 | 1980-09-10 | Rca Corp | Video disc |
| EP0029519A2 (en) * | 1979-10-29 | 1981-06-03 | Nippon Zeon Co., Ltd. | Information signal record medium of the capacitance type |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2810367C2 (en) * | 1977-03-15 | 1984-12-20 | Rca Corp., New York, N.Y. | Information storage disk |
| IT1118212B (en) * | 1977-03-15 | 1986-02-24 | Rca Corp | UNCOATED VIDEO DISK |
| IT1123480B (en) * | 1978-08-29 | 1986-04-30 | Rca Corp | LUBRICANTS FOR VIDEO DISKS |
| US4355062A (en) * | 1981-02-05 | 1982-10-19 | Rca Corporation | Bis(hydroxyalkyl)disiloxanes and lubricant compositions thereof |
| JPS57191845A (en) * | 1981-05-22 | 1982-11-25 | Toshiba Corp | Resin composition for video disk |
-
1983
- 1983-04-14 JP JP6444083A patent/JPS59191152A/en active Pending
-
1984
- 1984-04-13 FR FR8405920A patent/FR2544533B1/en not_active Expired
- 1984-04-13 DE DE19843414053 patent/DE3414053A1/en active Granted
- 1984-04-13 GB GB08409690A patent/GB2138991B/en not_active Expired
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1574595A (en) * | 1977-03-15 | 1980-09-10 | Rca Corp | Video disc |
| GB2037054A (en) * | 1978-11-13 | 1980-07-02 | Rca Corp | Video discs and moulding compositions therefor |
| EP0029519A2 (en) * | 1979-10-29 | 1981-06-03 | Nippon Zeon Co., Ltd. | Information signal record medium of the capacitance type |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0181753A3 (en) * | 1984-11-02 | 1987-06-16 | Victor Company Of Japan, Limited | High density information record medium |
| US4906499A (en) * | 1984-11-02 | 1990-03-06 | Victor Company Of Japan, Ltd. | High density information record medium comprising a polymer material having a lubricant uniformly dispersed therein |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3414053C2 (en) | 1988-03-03 |
| FR2544533A1 (en) | 1984-10-19 |
| DE3414053A1 (en) | 1984-10-25 |
| FR2544533B1 (en) | 1988-03-25 |
| JPS59191152A (en) | 1984-10-30 |
| GB2138991B (en) | 1986-12-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19930413 |