Light measuring apparatus and a method for correcting non-linearity of a light measuring apparatus

A light measuring apparatus for measuring an illuminance level of light, the apparatus comprising:

• one or more correction light emitters which illuminate an optical sensor at predetermined illuminance levels, the illuminance levels having known illuminance ratios;
• a calculation controller configured to calculate correction values at the respective illuminance levels based on expected and actual sensor output levels at the respective illuminance levels;
• the calculation controller configured to successively turn-on the correction light emitter at the respective illuminance levels, and correct the sensor output level by the corresponding correction value to obtain a measurement output;
• and
• a monitoring optical sensor having linearity, disposed adjacent to the optical sensor, said monitoring optical sensor configured to receive the illumination light from the correction light emitter.

A light measuring apparatus for measuring an illuminance level of light, the apparatus comprising:

• a plurality of correction light emitters which illuminate an optical sensor at predetermined illuminance levels, the illuminance levels having known illuminance ratios;
• a calculation controller configured to calculate correction values at the respective illuminance levels based on expected and actual sensor output levels at the respective illuminance levels;
• the calculation controller configured to successively turn-on the correction light emitter at the respective illuminance levels, and correct the sensor output level by the corresponding correction value to obtain a measurement output;
• and
• wherein the calculation controller
• (a) calculates the sensor output levels when the optical sensor is individually illuminated by the respective correction light emitter and when the optical sensor is simultaneously illuminated by the respective correction light emitter;
• (b) calculates a signal ratio of a sum of the sensor output levels when the optical sensor is individually illuminated by the respective correction light emitter to the output level when the optical sensor is simultaneously illuminated by the respective correction light emitter;
• (c) performs steps (a)-(b) at the plurality of illuminance levels having the known illuminance ratios, and
• (d) calculates the correction values for the sensor output level of the light being measured based on the calculated sensor output levels and signal ratio data.

A light measuring apparatus for measuring an illuminance level of light, the apparatus comprising:

• one or more correction light emitters which illuminate an optical sensor at predetermined illuminance levels, the illuminance levels having known illuminance ratios;
• a calculation controller configured to calculate correction values at the respective illuminance levels based on expected and actual sensor output levels at the respective illuminance levels;
• the calculation controller configured to successively turn-on the correction light emitter at the respective illuminance levels, and correct the sensor output level by the corresponding correction value to obtain a measurement output;
• and
• a shield which shuts off the light being measured while the correction light emitter is on.

A light measuring apparatus for measuring an illuminance level of light, the apparatus comprising:

• one or more correction light emitters which illuminate an optical sensor at predetermined illuminance levels, the illuminance levels having known illuminance ratios;
• a calculation controller configured to calculate correction values at the respective illuminance levels based on expected and actual sensor output levels at the respective illuminance levels;
• and
• the calculation controller configured to successively turn-on the correction light emitter at the respective illuminance levels, and correct the sensor output level by the corresponding correction value to obtain a measurement output,
• wherein the illumination light from the correction light emitter directly reaches the optical sensor.

A method for correcting the non-linearity of a light measuring apparatus, comprising the steps of:

• successively turning one or more correction light emitters at a plurality of illuminance levels to illuminate an optical sensor at the illuminance levels corresponding to known illuminance ratios;
• calculating correction values at the respective illuminance levels based on expected and actual sensor output levels at the respective illuminance levels;
• and
• correcting the sensor output level by the corresponding correction value to obtain a measurement output,
• wherein the calculation controller measures the sensor output levels at the respective illuminance levels in accordance with a plurality of different gains, and calculates the correction value for the sensor output level based on a ratio of measurement results at the respective illuminance levels in accordance with the respective gains.