Rotating speed control device of a rotary type electrostatic spray painting device

Claim 1

A rotary type electrostatic spray painting device, comprising: a housing; a rotary shaft rotatably supported within said housing and having a front end and a rear end face which forms a reflecting face portion and a non-reflecting face portion thereon; a spray head fixed onto the front end of said rotary shaft; detecting means arranged to alternately face said reflecting face portion and said non-reflecting face portion and for receiving receiving light reflected from said reflecting face portion, said detecting means producing an output signal representing the rotating speed of said rotary shaft; an air turbine for providing a rotational force for said rotary shaft; a pressurized air source; an air supply conduit connecting said pressurized air source to said air turbine; valve means arranged in said air supply conduit to control the amount of air fed into said air turbine; and control means for actuating said valve means in response to the output signal of said detecting means to equalize the rotating speed of said rotary shaft to a predetermined rotating speed wherein said control means comprises timer means for calculating a time elapsed after said control device produces said output signal, and an alarm device operated when said elapsed time exceeds a predetermined time and when the difference between the rotating speed of said rotary shaft and said desired rotating speed is larger than a predetermined speed.