Cross-coil measuring meter driving device having a period range judging means and an after-change supply prevention means

A cross-coil measuring meter driving device which (1) calculates an angle of deflection corresponding to a running speed of a vehicle on the basis of a period of a running pulse generated with running of said vehicle, (2) generates a driving pulse signal of a duty ratio corresponding to said angle of deflection, and (3) supplies said driving pulse signal to a cross coil to rotate a magnet rotor, so that a pointer connected to said magnet rotor points at a point corresponding to said angle of deflection;

• said driving device comprising:
• a period range judging means for judging whether or not said period of said running pulse is within a predetermined range, after an input state of said running pulse is shifted from an input state when said vehicle is at a stop to an input state when said vehicle is running;
• and
• an after-change supply prevention means for preventing said cross coil from being supplied with said driving pulse signal of a duty ratio corresponding to said angle of deflection calculated based on said period of said running pulse whenever said period range judging means judges that said period of said running pulse is not within said predetermined range;
• wherein said driving pulse signal of a duty ratio corresponding to said angle of deflection calculated based on said period of said running pulse when said vehicle is at a stop is supplied to said cross coil, while said after-change supply prevention means is preventing said cross coil from being supplied with said driving pulse signal of a duty ratio corresponding to said angle of deflection calculated based on said period of said running pulse.