| 摘要 |
PURPOSE:To facilitate the high-luminance illumination by installing both the filter which reflects the heat rays and transmits other rays and the filter which absorbs the heat rays and transmits other rays each in combination into the illuminating optical path given from the illuminating light source. CONSTITUTION:Filter holder 4 doubling the heat dissipating part is provided near light emitting system 3 comprising illuminating light source 1 and reflector 2. Then reflective filter A1 having an inclination of 45 deg. and the 70% infrared reflection factor each which reflects and eliminates thd infrared rays and then transmits other rays is installed on optical axis 7 of holder 4. Furthermore, absorption-type filter B having the 95% infrared absorption factor which absorbs and reduces the infrared rays and then transmits other rays is installed vertically to the optical axis. Thus for the light given from system 3, the infrared ray component is reflected by filter A1. And the light is branch-radiated to holder 4 to be dissipated. The rest of the infrared rays and other rays transmit through the filter and then illuminate information reading screen 6 through condenser lens 5. Thus the infrared rays are reduced for the transmitted rays which illuminate screen 6 to eliminate the scorching on screen 6. As a result, the lowering of the image resolution can be solved for the sensor even under the high-luminance illumination. |
