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 Title: |
US3872240:
Pickup apparatus for capacitive video disc players with transmission line tuned circuit
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Carlson, David John; Indianapolis, IN
Hilliker, Stephen Earl; Tempe, AZ
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| Assignee: |
RCA Corporation, New York, NY
other patents from RCA CORPORATION (466175) (approx. 7,929)
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| Published / Filed: |
1975-03-18
/ 1974-03-14
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| Application Number: |
US1974000451103
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| IPC Code: |
Advanced:
G11B 9/00;
G11B 9/06;
H04N 5/93;
Core:
more...
IPC-7:
G11B 9/06;
H04N 5/76;
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| U.S. Class: |
Current:
369/126;
369/129;
369/244.1;
386/E05.028;
G9B/009.014;
Original:
178/006.6R;
179/100.1B;
179/100.4M;
179/100.41G;
274/037;
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| Field of Search: |
178/6.6 R,6.6 A,6.6 DD,6.7 A
179/100.3 V,100.1 B,100.4 R,100.4 M,100.41 G,100.41 H
235/61.11 H,61.12 R
274/037
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| Priority Number: |
| 1973-03-26 |
GB1973000014395 |
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| Abstract: |
A video disc player, employing a stylus electrode to form a variable capacitance with a conductive disc coating, as geometry variations in the disc groove pass beneath the stylus, has a conductive stylus support arm which forms a transmission line with a surrounding arm housing of conductive material. The transmission line is capacity end loaded at the arm end remote from the stylus by a series combination of capacitances which include an air dielectric capacitor and a voltage variable capacitor. The air dielectric capacitor has a first set of plates suspended from the movable stylus support arm, and a second set of plates fixedly mounted on the housing and interleaved with the first set. The transmission line and associated capacitances form a tuned circuit with a resonant frequency subject to variation as the stylus-disc capacitance varies. The tuned circuit is excited with UHF oscillations from a fixed frequency oscillator operating at a frequency within an ISM-allocated band. As the resonant frequency of the tuned circuit varies, the resultant UHF oscillation amplitude variations are detected to recover the recorded information. A tuning control circuit responsive to the detector output adjusts the voltage variable capacitance to maintain a desired spacing between the oscillator output and the tuning range of the transmission line resonant circuit. The stylus support arm is subject to replacement in the housing without wiring disconnection or connection.
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| Attorney, Agent or Firm: |
Whitacre, Eugene M. ;
Meagher, William H. ;
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| Primary / Asst. Examiners: |
Cardillo, Jr., Raymond F.;
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| INPADOC Legal Status: |
None
Family Legal Status Report
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| Family: |
Show 20 known family members
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First Claim:
Show all 10 claims |
1. In a disc playback system including a stylus having a conductive electrode for establishing a variable capacitance with a disc record during playback the combination comprising:
- a stylus support arm of conductive material providing at one end thereof support for said stylus;
- a conductive housing for said arm having an aperture through which said one support arm end extends during disc playback;
- means for pivotally supporting the other end of said stylus support arm within said housing;
- means electrically coupled to said other end of said stylus support arm for capacity end loading a transmission line formed by said support arm and said housing, to form a tuned circuit including said transmission line, said capacity end loading means and said variable capacitance, said tuned circuit having a resonant frequency nominally subject to variation over a given range of frequencies in response to the variations of said stylus-disc capacitance;
- a source of oscillations at a nominal frequency in the immediate vicinity of said given range of frequencies;
- means for supplying oscillations from said source to said tuned circuit;
- amplitude detecting means coupled to said tuned circuit for developing signals representative of recorded information; and
- wherein said conductive stylus support arm has a length greater than a quarter-wavelength and less than a half-wavelength at said oscillation
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 9 U.S. patent(s) that reference this one
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