| 摘要 |
PURPOSE:To obtain always specified easy visibility without being affected by external brightness by providing a sensor which senses illumination, an automatic volume control, a switching regulator, and a back light of the luminance changing according to the output value of a regulator. CONSTITUTION:The illuminance sensor 4 senses the external brightness and a control section 5 executes the electrical relaying of the sensor 4 and the automatic volume 8. A manual volume control 6 executes the manual adjustment of illumination. The energy supplied from a power source lights a fluorescent lamp 3 via the switching regulator 1 consisting of a DC-DC converter and a DC-AC inverter 2. A user regulates the brightness by using the volume control 6 according to his own use environment. The sensor 4 is directly coupled to the volume 8 of the regulator 1 and regulates the output voltage of the regulator in the direction where the luminance of the fluorescent lamp 3 is increased, i.e. the sensor increases the output voltage of the regulator 1 when the outside field brightens. |
