Temperature sensor and temperature measuring method

A temperature sensor for measuring temperature in accordance with the time-of-life of a fluorescent light that is produced by a phosphor, comprising:

• a light source emitting an excitation light;
• a phosphor producing a fluorescent light through the excitation light;
• a photodetector device detecting the fluorescent light and outputting a fluorescent light signal in accordance with the intensity of the fluorescent light;
• and
• a processing portion calculating the temperature based on the fluorescent light signal from the photodetector device, wherein:
• the processing portion is configured to:
• calculate an integral value for the fluorescent light signal in each of at least three time periods set in advance during the decay of the fluorescent light signal, wherein the three time periods have identical time durations;
• calculate a first difference value based on the integral values of the first and second time periods, of the three time periods;
• calculate a second difference value based on the integral values of the first and third time periods, of the three time periods;
• calculate from the ratio of the first and second difference values, a variable that varies depending on the measurement temperature;
• and
• reference a relationship between the temperature and the ratio of difference values, stored in advance, to convert the calculated variable into a temperature.

A temperature measuring method for measuring a temperature in accordance with a fluorescent light time-of-life of a fluorescent light that is produced by an excitation light, comprising the steps of:

• illuminating a phosphor with an excitation light;
• detecting fluorescent light that is produced by the phosphor by the excitation light;
• calculating, using a processing portion, an integral value for a fluorescent light signal in each of three or more time periods that are set in advance during the decay of the fluorescent light signal;
• calculating, using the processing portion, a first difference value from the integral values for a first and a second time period having a first time duration;
• calculating, using the processing portion, a second difference value from the integral values for a third and a fourth time period having a second time duration;
• calculating, using the processing portion, from a ratio of the first and second difference values, a variable that varies depending on the measurement temperature;
• and
• referencing, using the processing portion, the relationship between the temperature and the ratio of the first and the second difference values, stored in advance, to convert the variable that has been calculated into a temperature.

A temperature measuring method for measuring a temperature in accordance with a fluorescent light time-of-life of a fluorescent light that is produced by an excitation light, comprising the steps of:

• illuminating a phosphor with an excitation light;
• detecting fluorescent light that is produced by the phosphor by the excitation light;
• calculating, using a processing portion, an integral value for a fluorescent light signal in each of three or more time periods that are set in advance during the decay of the fluorescent light signal, wherein the three time periods have identical time durations;
• calculating, using the processing portion, a first difference value based on the integral values of the first and second time periods, of the three time periods;
• calculating, using the processing portion, a second difference value based on the integral values of the first and third time periods, of the three time periods;
• calculating, using the processing portion, the variable from the ratio of the first and second difference values;
• and
• referencing, using the processing portion, the relationship between the temperature and the ratio of the first and second difference values, stored in advance, to convert the variable that has been calculated into a temperature.