The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 05, 1983
Filed:
Mar. 15, 1982
Ned J Seachman, Penfield, NY (US);
Edgar E Price, Webster, NY (US);
Xerox Corporation, Stamford, CT (US);
Abstract
An ink jet printer having improved droplet sensing apparatus for calibrating the printer. The improved apparatus defines a number of sensing sites each having first and second light sources for directing light signals through a sensing zone and a single fiber optic light pipe leading away from the sensing zone to circuitry for detecting the presence of ink droplets in that sensing zone. The preferred apparatus includes two light emitting diodes, each of which generate visible light signals of different wavelengths. These two light signals are received by an output light pipe and travel together along the right pipe to means for detecting the intensity of the two signals and determining droplet positioning in the sensing zone as a function of the two intensities. One apparatus for differentiating between the two light intensities comprises first and second photo detectors which respond to the wavelength light generated by the two light sources. The output from these two detectors are then routed to a difference amplifier which gives an indication of droplet position as a function of time. A second way of sensing the intensities is to time multiplex the sources so that only one source illuminates the droplet at a given time. These intensities are then stored in a sample and hold circuit and compared with a difference amplifier in a manner identical to the multiple wavelength sensing embodiment.