MONOLITHIC OPTICAL READING CIRCUIT, ESPECIALLY RELATED TO INTERFACES FOR OPERATING LIGHT EMITTING DIODES(LEDS) IN ASSOCIATION WITH OPTICAL DIODES REALIZED BY INTEGRATED-CIRCUIT TECHNOLOGIES

摘要

PURPOSE: A monolithic optical reading circuit is provided to realize a loudness control of an earpiece of a mobile phone in a method of avoiding unpleasant and harmful loudness levels by using an optical approximation sensing method, thereby reducing power consumption and manufacturing cost. CONSTITUTION: A circuit starts driving a sound generation loud speaker system, and forms a stable sound level threshold value(710). The circuit sets and drives LEDs with pulses(720). The circuit forms and drives two different photon sensing channels with synchronized pulses(730). If the LEDs are turned on, the circuit compares input signals for optical channels, and measures a distance from a reflecting surface(740). The circuit evaluates the signals, and effectively compensates for all unpleasant secondary influences(750). The circuit compares the measured distance with an equivalent amount of the threshold value(760), and determines whether a telephone is near to a user's ear(770). The circuit avoids unpleasant and harmful loudness levels, and generates sound output signals(780).