| 摘要 |
<p>PURPOSE:To provide a light source which can reliably hold a light source temperature at a constant level and which is not likely to be affected by ambient temperature. CONSTITUTION:A heat generating body 8 whose resistance value varies depending on temperature is formed on a ceramic substrate 14 to provide a light source body, a change in resistance of the heat generating body 8 is detected by a bridge circuit 18 including the heat generating body 8, and current flowing to the heat generating body 8 is controlled based on the detection, thereby holding the temperature of the heat generating body 8 at a constant level.</p> |
