{
  "patent_number": "US 4575330",
  "country": "US",
  "title": "How 3D Printers Build Objects Layer by Layer from Liquid",
  "original_title": "Apparatus for production of three-dimensional objects by stereolithography",
  "summary": "This patent describes the foundational method for 3D printing, where a machine builds a three-dimensional object layer by layer by hardening a liquid material with light or other energy.",
  "what_it_does": "The patent describes a system (Claim 1) that creates 3D objects by forming thin layers, called \"laminae,\" from a special fluid that hardens when exposed to specific energy. The system uses \"reaction means\" (Claim 2) like a beam of ultraviolet light (Claim 9) to draw each cross-section of the object on the liquid's surface. As each layer solidifies, an \"object support means\" (Claim 2) moves the partially built object away, allowing the next layer to form and attach. For example, a laser draws the bottom layer of a small plastic toy boat on a liquid resin, then the boat dips slightly, and the laser draws the next layer, building the boat up from the liquid.",
  "what_it_does_not_cover": [
    "3D printing methods that use powdered materials, like selective laser sintering (SLS), instead of a fluid medium.",
    "3D printing methods that extrude melted plastic filaments, like Fused Deposition Modeling (FDM).",
    "Systems that build objects by adding material from the side or top, rather than \"extracting\" them from a designated surface of a fluid.",
    "Methods that don't rely on a \"synergistic stimulation\" (e.g., light, electron beam, chemical jet) to change the material's state."
  ],
  "filed": "1984-08-08",
  "granted": "1986-03-11",
  "expires": "2004-08-08",
  "status": "expired",
  "holder": "UVP Inc",
  "holder_url": "https://patentbrief.org/company/uvp-inc",
  "inventors": [
    {
      "name": "Charles W. Hull",
      "url": "https://patentbrief.org/inventor/charles-w-hull"
    }
  ],
  "times_cited": 1094,
  "tags": [
    "manufacturing",
    "mechanical",
    "materials",
    "software",
    "consumer_electronics"
  ],
  "abstract": "A system for generating three-dimensional objects by creating a cross-sectional pattern of the object to be formed at a selected surface of a fluid medium capable of altering its physical state in response to appropriate synergistic stimulation by impinging radiation, particle bombardment or chemical reaction, successive adjacent laminae, representing corresponding successive adjacent cross-sections of the object, being automatically formed and integrated together to provide a step-wise laminar buildup of the desired object, whereby a three-dimensional object is formed and drawn from a substantially planar surface of the fluid medium during the forming process.",
  "url": "https://patentbrief.org/patent/us/4575330/stereolithography-3d-printing",
  "markdown_url": "https://patentbrief.org/patent/us/4575330/stereolithography-3d-printing/md",
  "google_patents_url": "https://patents.google.com/patent/US4575330",
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}