Patent ID: 7475957
Filing Date: 2009-01-13
Classification: B41J

Abstract:
1. A method of controlling an ink jet recording apparatus which ejects ink droplets toward a recording medium to record an image on said recording medium by causing an electrostatic force to act on ink containing charged colorant particles, comprising: applying continuously a predetermined constant D.C. voltage to ink ejecting means such that spontaneous ejection of said ink droplets in which said ink droplets are ejected spontaneously and continuously from said ink ejecting means occurs; detecting a spontaneous ejection property of the ejected ink droplets which are ejected spontaneously and continuously from said ink ejecting means by said spontaneous ejection; and controlling ejecting conditions for said ink droplets in accordance with the detected spontaneous ejection property, wherein said ejection property is a spontaneous ejection frequency of said ink droplets or the number of spontaneous ejections of said ink droplets per predetermined time, and wherein said ejecting conditions include at least one of a potential difference between a recording medium and an ink ejecting means for ejecting said ink droplets, a distance between said ink ejecting means and a counter electrode provided opposite to said ink ejecting means, and a temperature of said ink wherein said distance, said temperature and said potential difference are set as an initial distance, an initial temperature and a detection potential difference at which spontaneous ejection of said ink droplets occurs, respectively, said spontaneous ejection frequency or said number of spontaneous ejections is detected at said detection potential difference; a detected value of said ejection frequency or said number of spontaneous ejections is compared with a desired value of the ejection frequency or the number of spontaneous ejections to obtain a comparison result; said potential difference, said distance and said temperature of said ink are updated according to the comparison result; said spontaneous ejection frequency or said number of spontaneous ejections is repeatedly detected while updating said potential difference, said distance and said temperature of said ink until said detected value coincides with the desired value or falls within a tolerance of the desired value; said updated potential difference, said updated distance and said updated temperature of said ink are set as a potential difference for drive, a distance for drive, and a temperature for drive, respectively, when said detected value coincides with the desired value or falls within a tolerance of the desired value; an ejection potential difference and a non-ejection potential difference between which a critical potential difference as a critical value at which spontaneous ejection of the ink droplets occurs exists are obtained by decreasing said updated potential difference; a potential difference lower than said critical potential difference, or a potential difference equal to or lower than said non-ejection electric potential is set as a bias electric potential to be applied across said ink ejecting means and said recording medium; and a difference between said potential difference for drive and said bias potential difference is set as a drive pulse potential difference.