US Patent No. 9,647,020

LIGHT SENSING CIRCUIT AND CONTROL METHOD THEREOF


Patent No. 9,647,020
Issue Date May 09, 2017
Title Light Sensing Circuit And Control Method Thereof
Inventorship Ting-Chang Chang, Kaohsiung (TW)
Hua-Mao Chen, Kaohsiung (TW)
Ming-Yen Tsai, Kaohsiung (TW)
Min-Chen Chen, Kaohsiung (TW)
Assignee NATIONAL SUN YAT-SEN UNIVERSITY, Kaohsiung (TW)

Claim of US Patent No. 9,647,020

1. A light sensing circuit, comprising:
a photo transistor having a gate, a drain and a source;
a first transistor electrically connecting between the gate and the source of the photo transistor;
a first capacitor electrically connecting between the gate and the drain of the photo transistor;
a second transistor electrically connecting with the drain of the photo transistor, the first capacitor, and a data signal;
a second capacitor electrically connecting between the source of the photo transistor and a ground contact;
a third transistor electrically connecting with the photo transistor, the first transistor, and the second capacitor; and
a switch adapted to alternatively connect the third transistor with a buffer or a zero signal;
wherein a bias situation of the photo transistor is controlled by a negative voltage signal, the first transistor is turned
on or off by a first signal, the second transistor is turned on or off by a second signal, and the third transistor is turned
on or off by a third signal, so that the buffer outputs a light sensing signal generated by the photo transistor.