| 摘要 |
PURPOSE:To extend the time required for a rise to temperature where the quantity of light is decreased below a specific quantity and to prolong the life of a light source by switching the reference value of temperature of the detected light source according to an external control signal. CONSTITUTION:This device consists of the light source which projects light on a body to be read, a heating means which heats the light source, a detecting means which detects the temperature of the light source, a switching means which switches the reference value of temperature of the light source detected by the detecting means according to the external control signal, and a control means which controls the temperature of the heating means according to the detection result of the detecting means based upon the reference value switched by the switching means. Then when the light source is heated by the heating means, the reference value of the detecting means which detects the temperature of the light source is switched according to the external control signal and the temperature of the heating means is controlled according to the detection result of the detecting means based upon the reference value. Consequently, the time required for a rise up the temperature where the quantity of light is decreased below the specific quantity. |
