| 摘要 |
<p>PROBLEM TO BE SOLVED: To make it possible to supply a stable internal power source even when electric current consumption increases by matching the timing of the switching of an internal power source circuit section and the changeover timing of the AC driving voltage of a driving circuit section. SOLUTION: A sawtooth wave 41 and an amplified voltage 48-1 are compared in a voltage comparison section 45-1 and a pulse signal 49-1 which rises to an H level while, for example, the sawtooth wave 41 is higher is outputted. The P channel transistor (TR) Q1 of a voltage switching section 46-1 is driven by the pulse signal 49-1. Energy is accumulated in an inductance element L1 in a voltage filter section 47-1 while the TR Q1 is on. In such a case, the TR Q1 goes on and the current meeting the duration of this on period flows to the coil L1 during the period where the sawtooth wave 41 is high in the voltage comparison section 45-1. An output terminal V1 is driven during the period right after resetting of the sawtooth wave 41 which is the duration meeting the magnitude of the current quantity.</p> |
