Patent ID: 6264298
Filing Date: 2001-07-24
Classification: B41J,G06K

Abstract:
A method of printing an image on a recording medium with a liquid ink printhead moving in a scanning direction having drop ejectors depositing ink drops on the recording medium at a given default frequency and in a plurality of pixel locations spaced by a predetermined resolution, the method comprising the steps of:(a) determining a pixel size drop volume of liquid ink necessary at the predetermined resolution to fill one of the pixel locations;(b) determining a reduced subpixel size drop volume of liquid ink for subpixel drops to be printed by dividing the pixel size drop volume by a factor of at least three;(c) determining a frequency for firing and printing the subpixel drops in a fast scan direction such that after printing a given subpixel drop, a succeeding subpixel drop lands on the recording medium before; and(d) firing and depositing multiple subpixel drops each having the determined reduced volume of liquid ink, at the determined frequency, and in a shingled overlapping manner in which adjacent subpixel drops overlap by at least one third of a diameter of an overlapped subpixel drop, thereby resulting in a synergistic slow scan direction combined spreading, and thereby enabling a relatively high number of gray scale levels, and high quality printed images.