Patent ID: 8157342

Claim:
A liquid-jet device, comprising: a liquid-jet configured to jet liquid droplets; a pattern formation control unit configured to control the liquid-jet head and thereby to form a test pattern composed of separate liquid droplets on a water repellent part; a detecting unit including a light emitting element configured to illuminate the test pattern on the water repellent part and a light receiving element configured to receive specularly reflected light form the illuminated test pattern and to output a detection signal proportional to the received specularly reflected light; and a landing position adjusting unit configured to adjust landing positions of the liquid droplets base on the detection signal from the light receiving element, wherein the landing position adjusting unit is configured to obtain a first and second sections of the low-level portion of the detection signal, each of the first and second sections being between an upper threshold value and a lower threshold value, to obtain a first regression line of the first section and a section regression line of the second section, to obtain an intermediate position between the first and second regression lines, and to use the intermediate position as an edge of the test pattern.