ILLUMINATION SENSOR CAPABLE OF NOT DEPENDING THE ILLUMINATION HEIGHT OF INCIDENT-LIGHT

摘要

PURPOSE: An illumination sensor is provided to prevent from depending on the illumination height of incident-light by depending on the current in which the constant-current source of the subtraction circuit flows.;CONSTITUTION: An illumination sensor comprises first and second photo-detection devices(15, 16), a subtraction circuit(25), a capacity(11-14), a switch(26-29) and a sample hold circuit(30). The first and second photo-detection devices output the photo voltage based on the incident light. The subtraction circuit is driven to the constant-current source. The subtraction circuit outputs the difference voltage of the output voltage of the first and second photo-detection devices. One end of the capacity is formed in the output terminal of the subtraction circuit and the other end is formed in the input terminal of the sample hold circuit. The switch is formed between the other end of the capacity and the node in which the reference voltage is provided. The sample hold circuit enforces the sample of the voltage of the other end of the capacity based on the difference voltage or hold.;COPYRIGHT KIPO 2012