| 摘要 |
PURPOSE: To regulate the illuminance of a fluorescent lamp by controlling its lamp power. CONSTITUTION: A ballast 10 is constituted of an input control section 14 for controlling power fed to a fluorescent lamp 12, a lamp driving section 16, a power command interface 28 and a control section 18. In this constitution, an external power command input 26 is compared with a calculation power level P to be internally generated, and a precontroller output voltage V is multiplied by a lamp driver current I in order to obtain a signal indicating the lamp power. Furthermore, the command input 26 is isolated by the power command interface 28. The command input signal 26 is attenuated to reduce power transmitted to the lamp 12 to thereby accomplish the diminution of light intensity of the lamp 12. This performs substantial constant power operation in order that one ballast can be employed in various applications, and consequently, a lighting designer and an user have a high degree of flexibility. |
