Method for judging directionality by utilizing a gravity sensor

摘要

A method for judging directionality of a housing having two parallel panels by a gravity sensor is disclosed. The method is used for a handheld apparatus to judge which of the panels is upward. The method first obtains a set of component quantity of gravity on three coordinate axes from a three dimensional gravity sensor. When −0.5 gg_z≧−1 g and 1 g≧g_z0.5 g, a first direction status and a second direction status is acquired, respectively. When 0.5 g≧g_z≧−0.5 g, the method further reposes on two parameters, polarity of g_z and magnitude of the component quantity on y-axis (g_y), to judge. When g_z0 and −0.5 gg_y≧−1 g or when g_z0 and 1 g≧g_y0.5 g, the judging result is the first direction status. When g_z0 and −0.5 gg_y≧1 g or when g_z0 and 1 g≧g_y0.5 g, it is the second one. The rest will be judged to be “don't care”.