| 摘要 |
PURPOSE:To make a discharge tube glowable in a responsive manner irrespective of a voltage drop, by connecting a space between both input and output terminals in a transistor circuit, in case of the discharge tube for permeable type crystalline liquid display unit. CONSTITUTION:When an ignition switch IG is closed, a filter circuit 20 produces filter voltage according to feed voltage cut of a DC power source, while a constant voltage circuit 30 generates transient constant voltage due to charging voltage in a condenser 34 being quickly charged, lighting a discharge tube 10 by means of a driving circuit 40 in response to the said transient constant voltage. In this case, even if the DC power source B is unnecessarily dropped due to starter operation, the constant voltage circuit 30 is in no case subject to the influence of the voltage drop by a transistor circuit 31 and since the filter voltage is generated as the constant voltage via the condenser 34 so that the discharge tube 10 can be timely lighted in response to IG closure without entailing any delay. Thus, display details on a display unit are responsively sightable without fail. |
