| 摘要 |
PURPOSE: To limit the maximum speed of rotation of an electric hand tool to a value preset by operating a key to reduce cost by providing matrix type displaying elements, and providing the key corresponding to the type of material to be machined and the value of the tool diameter at an end edge of the matrix area. CONSTITUTION: A key 3 for selecting material to be machined is connected to a supply voltage through one terminal, and is connected each time to a conductor of a row 6 through the other terminal. Further, a key 4 for selecting the diameter of a drill is connected to another pole of the voltage source on one end, and its another end is connected to a conductor on a column 7. The free ends of the conductors on the row 6 and the column 7 are respectively connected to a logical memory 2. The logical memory 2 locks or stores the positions of the keys 3 and 4 to operate the keys to each other each time, controls a digital/analog converter 8, and controls light emitting diodes 5 corresponding to the keys. With the converter 8, a control voltage Ust is taken out from a moving contact of a latch potentiometer 9 to be supplied to an electronic adjusting device. |
