{
  "patent_number": "US 3501586",
  "country": "US",
  "title": "How James Russell Invented the Digital Optical Disc",
  "original_title": "Analog to digital to optical photographic recording and playback system",
  "summary": "A 1966 invention that replaced physical needles on vinyl records with a laser beam reading digital data from a spinning disc.",
  "what_it_does": "This patent describes a system that converts analog audio signals into digital data and encodes them onto a light-sensitive photographic disc. During playback, a light source scans the disc, and a detector converts the reflected light pulses back into an electrical signal. This process eliminates the physical contact between a needle and a record, preventing the wear and tear that degrades sound quality over time. By using digital encoding, the system ensures that the audio signal can be perfectly reconstructed without the noise or distortion inherent in analog playback.",
  "what_it_does_not_cover": [
    "Does not cover magnetic tape recording or playback systems.",
    "Does not cover the specific error-correction algorithms used in later commercial CDs.",
    "Does not cover non-optical storage media like hard disk drives.",
    "Does not cover the physical manufacturing process of mass-producing consumer CDs."
  ],
  "filed": "1966-09-01",
  "granted": "1970-03-17",
  "expires": "1987-03-17",
  "status": "expired",
  "holder": "Battelle Development Corp",
  "holder_url": "https://patentbrief.org/company/battelle-development-corp",
  "inventors": [
    {
      "name": "James T Russell",
      "url": "https://patentbrief.org/inventor/james-t-russell"
    }
  ],
  "times_cited": 52,
  "tags": [
    "consumer_electronics",
    "mechanical",
    "telecommunications"
  ],
  "abstract": null,
  "url": "https://patentbrief.org/patent/us/3501586/optical-digital-recording-russell",
  "markdown_url": "https://patentbrief.org/patent/us/3501586/optical-digital-recording-russell/md",
  "google_patents_url": "https://patents.google.com/patent/US3501586",
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}