| 摘要 |
To maintain the surface temperature of a light source (1), such as a halogen lamp, a thermometer (5) is arranged on the light source and is adapted to emit a signal to a differential unit in response to the surface temperature of the light source, said differential unit receiving on another input a reference signal which is representative of the optimum temperature of the light source. An output from the differential unit emits a signal to a controller (4) which is adapted to control a cooling unit, such as a fan, via a power stage (3), whereby the cooling power to the light source may be controlled in response to the temperature on said source. The invention provides a considerable extension of the service life of the light source, which is advantageous in connection with expensive light sources, such as halogen lamps of great power, for reprographic equipment. |
