{
  "patent_number": "US 3946398",
  "country": "US",
  "title": "How Piezoelectric Inkjet Printing Works",
  "original_title": "Method and apparatus for recording with writing fluids and drop projection means therefor",
  "summary": "A 1970 patent describing how to print images by using electrical pulses to bend a tiny crystal plate, squeezing individual ink drops out of a nozzle on demand.",
  "what_it_does": "This patent describes a drop-on-demand inkjet printing mechanism. Instead of spraying a continuous stream of ink, it ejects individual droplets only when needed. The system features a fluid chamber connected to a constant ink supply and a nozzle orifice. One wall of the chamber contains a piezoelectric actuator made of two plates bonded together. When an electrical pulse is applied, these plates expand in opposite directions, causing the actuator to bend inward. This sudden volume reduction squeezes exactly one droplet of ink out of the nozzle at a rate of 100 to 3,000 drops per second.",
  "what_it_does_not_cover": [
    "Does not cover continuous inkjet printing where a constant stream of droplets is electrostatically deflected.",
    "Does not cover thermal inkjet printing, which uses heat resistors to vaporize ink and create a bubble to eject drops.",
    "Does not cover printing rates outside the claimed range of 100 to 3,000 droplets per second.",
    "Does not cover single-layer piezoelectric actuators that do not use two transversely expanding plates secured together to bend."
  ],
  "filed": "1970-06-29",
  "granted": "1976-03-23",
  "expires": "1993-03-23",
  "status": "expired",
  "holder": "SILONICS Inc",
  "holder_url": "https://patentbrief.org/company/silonics-inc",
  "inventors": [
    {
      "name": "Stephan B. Sears",
      "url": "https://patentbrief.org/inventor/stephan-b-sears"
    },
    {
      "name": "Edmond L. Kyser",
      "url": "https://patentbrief.org/inventor/edmond-l-kyser"
    }
  ],
  "times_cited": 448,
  "tags": [
    "consumer_electronics",
    "mechanical",
    "materials"
  ],
  "abstract": "A recording apparatus and method is disclosed which includes a writing fluid source feeding a drop projection means which ejects a series of droplets of writing fluid from a nozzle in a discontinuous stream with sufficient energy to traverse a substantially straight trajectory to a recording medium. The volume of each droplet is individually controlled by electrical pulses applied to the projection means from an electronic driver. A plurality of such projection means may be employed and connected to control means whereby to print or form predetermined graphical intelligence patterns on a record medium.",
  "url": "https://patentbrief.org/patent/us/3946398/drop-on-demand-inkjet",
  "markdown_url": "https://patentbrief.org/patent/us/3946398/drop-on-demand-inkjet/md",
  "google_patents_url": "https://patents.google.com/patent/US3946398",
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}