Photometric apparatus and photometric method

A photometric apparatus comprising:

• at least one optical sensor for generating a photocurrent according to an amount of incident light;
• at least one integrator capacitor for integrating the photocurrent from said optical sensor;
• a voltage detection means for detecting a voltage across said integrator capacitor;
• an integration time-measuring means for measuring an integration time for which said integrator capacitor integrates the photocurrent;
• resetting-and-controlling means for resetting said integrator capacitor whenever the voltage across said integrator capacitor exceeds a given voltage value;
• a totalizing means for finding a total voltage value integrated into said integrator capacitor during a given time;
• and
• a photometric means for finding a photometric value based on said total voltage value and on said integration time from said integration time-measuring means;
• wherein the integration time after a lapse of said given time measured by said integration time-measuring means is equal to the given time subtracted by a time for which said resetting-and-controlling means are resetting said integrator capacitor within said given time.

The photometric apparatus, comprising:

• at least one optical sensor for generating a photocurrent according to an amount of incident light;
• at least one integrator capacitor for integrating the photocurrent from said optical sensor;
• a voltage detection means for detecting a voltage across said integrator capacitor;
• an integration time-measuring means for measuring an integration time for which said integrator capacitor integrates the photocurrent;
• resetting-and-controlling means for resetting said integrator capacitor whenever the voltage across said integrator capacitor exceeds a given voltage value;
• a totalizing means for finding a total voltage value integrated into said integrator capacitor during a given time;
• and
• a photometric means for finding a photometric value based on said total voltage value and on said integration time from said integration time-measuring means;
• wherein said totalizing means adds up the difference between a voltage value developed across said integrator capacitor at a start of integration and a voltage value developed across said integrator capacitor immediately prior to resetting by the resetting-and-controlling means after the start of said integration on each resetting to thereby obtain a sum value, and wherein a difference between a voltage value developed across said integrator capacitor after a lapse of said given time and a voltage value developed across said integrator capacitor at the start of said integration is added to said sum value, thus deriving said total voltage value.

A photometric method for measuring the amount of incident light, comprising the steps of:

• (a) producing a photocurrent according to an amount of incident light;
• (b) integrating said photocurrent to produce an integrated voltage;
• (c) detecting said integrate voltage corresponding to said integrated photocurrent;
• (d) resetting the integration during a reset period at least once when said integrated voltage exceeds a given voltage and repeating the steps (b), (c), and (d);
• (e) finding a total voltage value of said integrated voltage values integrated during a given time;
• (f) measuring a total time for which said photocurrent is integrated excluding a time for said reset period;
• and
• (g) finding a photometric value based on said integration time and on said total voltage value.