| 摘要 |
PURPOSE:To make it possible to easily carry out the confirmation or the adjustment of a zero level, by converting a sweep signal generating circuit to a second sweep mode generating a sweep signal by self-excitation in response with a zero level state setting operation when a trigger signal is absent. CONSTITUTION:When a trigger signal is generated in such a state that an input selecting switch 9 is switched to a D.C. selecting contact and a sweep system selecting switch 12 is switched to a sweep mode selecting contact (a), a saw tooth wave is generated from a sweep signal generating circuit 21 and the wave form of an input signal is drawn on the tube surface of CRT but, when the trigger signal is not obtained, the generation of the saw tooth wave is also stopped. When a zero level confirming switch 19 is turned ON during this first sweep mode selection, a sweep mode indication control signal transmission line 11 comes to a low level and a low level second sweep mode indication control signal is inputted in the sweep signal generating circuit 21 which in turn generates a saw tooth wave by self-excitation to display a zero level on the tube surface of CRT4. |
