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:
Dec. 05, 1995
Filed:
Aug. 15, 1994
Brian L Helterline, Salem, OR (US);
John H Dion, Corvallis, OR (US);
Michael D Whitmarsh, Tigard, OR (US);
Hewlett-Packard Corporation, Palo Alto, CA (US);
Abstract
Method and apparatus for regulating print density in a printer of the type of an ink-jet printer having a print cartridge including nozzles which each fire ink therefrom responsive to a voltage pulse applied to a resistor in the nozzle. An optical sensor senses line width printed by the nozzles. Circuitry determines the difference between a predetermined optimum line width and the printed line width. Look-up tables relate the line width to the energy of a pulse applied to each resistor and use this signal to control ink drop volume, and therefore printed dot size. In another embodiment, a nozzle includes 2400 addressable nozzles per inch. Sensed line width is used to vary the dpi by selecting different ones of the nozzles for firing thereby maintaining appropriate relative positioning of the dots when their size varies from the predetermined line width. In the direction of paper movement, the speed of a paper carrier is varied to match the printing frequency of the X-axis to produce square images.