| 摘要 |
PURPOSE:To enable adjustment to optional one of plural stages including one with a duty factor of 100%, through a simple construction, by using plural pairs of cam followers and cam surfaces and a single switch to enable control to the plural stages. CONSTITUTION:Push bottons 16a-16c are so provided that a pressed button is returned and a state corresponding to another newly pressed button is set when the latter button is pressed as the former is pressed. While the push botton 16a is pressed, a switch 5 is closed or opened by only a cam follower 15b and operation is performed with a duty factor of T2/T where T denotes the opening/closing period of the switch. While the push botton 16b is pressed, the switch 5 is closed or opened by only a cam follower 15a and operation is performed with a duty factor of T1/T. While the push button 16c is pressed, the switch 5 is actuated by the cam flollowers 15a, 15b. At that time, operation is effected with a duty factor of 100% because the beginning of each closing period is in the other closing period. |
