| 摘要 |
PURPOSE:To prevent the hanging down of a tungusten coil and/or the damage of an outer tube caused by the overheating of a resistor while a lamp is being turned on by providing a heat screening body around the resistor. CONSTITUTION:Normally, at the first opening of a bimetal switch 3, a lamp comes on, but if the high voltage pulses generated in this case are in sufficient for the start of the lamp, the lamp cannot come on. When the bimetal switch 3 is closed again, current flows again in a carbon coat resistor 17, a heater 16, and the bimetal switch 3 and the bimetal switch 3 is actuated and high voltage pulses are regenerated. When the actuation of the bimetal switch 3 is repeated several times at the start of the lamp like this, the temperature of the carbon coat resistor 17 rises gradually from normal temperatures and an outer tube 10 is heated by this heat and may be cracked. Since a heat screening body 18 is provided around the carbon coat resistor 17 in this invention, the heating of the outer tube 10 is reduced by this heat screening body 18. |
