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Ink jet sensor method and apparatus

  • US 4,410,895 A
  • Filed: 10/26/1981
  • Issued: 10/18/1983
  • Est. Priority Date: 10/26/1981
  • Status: Expired due to Fees
First Claim
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1. In an ink printer having one or more nozzles for directing one or more ink streams toward a recording medium, apparatus for sensing the presence of individual droplets from said one or more ink streams toward a recording medium, apparatus for sensing the presence of individual droplets from said one or more ink streams in their trajectory toward said medium comprising:

  • at least one input optical fiber for each nozzle having a first end coupled to a light source, said input optical fiber directing light from said source to an associated planar sensing site from a second end, so that droplets following certain trajectories over the planar sensing site intercept said light;

    two output optical fibers being provided for each input optical fiber, the output fibers having receiving ends for receiving light from their associated input optical fiber, the receiving ends of each of the two output fibers being adjacent each other and located in the planar sensing site of their associated input fiber, the receiving ends of the output fibers being positioned in spaced relation to said input fiber second ends, each of said two output fibers having ends opposite the receiving ends which terminate at a separate photodetector, so that changes in light intensity caused by passage of said droplets past said planar sensing sites may be detected; and

    a mask being interposed between said output fiber receiving ends and the region of ink droplet travel above the planar sensing site to mask light received from the input fiber and define two circular optical receiving sites for each sensing site, one receiving site for each receiving end of the two output fibers and each receiving site having an area less than the receiving ends of the output fibers, the receiving ends of the output fibers abutting said mask, so that only a portion of the output fiber receiving ends is exposed to light directed to that particular sensing site by the input fiber.

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