| 摘要 |
PURPOSE:To provide a driving circuit for cold cathode discharge tube, which can control gradation of luminance at multiple gradations at a low cost. CONSTITUTION:Direct current voltage, which is rectified by a rectifying circuit 21 or 23, is outputted to a transistor TR1, or an electrode K1 or K2 of a cold cathode discharge tube 1a and a collector of a transistor TR3 or a collector of a transistor TR4 through the transistor TR1. These transistors TR1-TR4 form an inverter circuit for converting the direct current voltage to the alternating current voltage. ON/OFF of the transistors TR3, TR4 is controlled by the signal X1 for changing ON-width and ON-time of pulse on the basis of the gradation of a board surface, correction of gradation and gradation of display, and the gradation of luminance of the cold cathode discharge tube 1a is controlled on the basis of this signal X1. |
