Patent ID: 8237394
Filing Date: 2012-08-07
Classification: G01D,G01R

Abstract:
1. A method for initializing an indicating instrument for a vehicle, wherein the instrument includes: a pointer that is rotatable in a zero-reset direction to return to a zero position, which indicates a zero value of a vehicle state value of the vehicle; a step motor that includes a field winding and is configured to rotate the pointer upon application of a drive signal, which alternates in accordance with an electrical angle, to the field winding; a rotary drive system that ranges from the step motor to the pointer; a stopper mechanism that is configured to stop the pointer, which rotates in the zero-reset direction, at a stopper position located within a predetermined range from the zero position in the zero-reset direction; and a control means for controlling the drive signal based on a zero point, which is the electrical angle that corresponds to the stopper position, the method comprising: performing zero-reset processing that includes making the control means control the drive signal to rotate the pointer in the zero-reset direction in order to force the step motor to lose synchronization; performing synchronization loss detection processing that includes: performing zero point setting processing that includes setting the electrical angle, which is phase-shifted from the synchronization loss electrical angle in an indication value increasing direction by 180 degrees or less, as the zero point which is stored in the control means, the indication value increasing direction being opposite from the zero-reset direction.