Ambient light sensor circuit and flat panel display device having the same

A flat panel display device, comprising:

• an ambient light sensor circuit which includes:
• a transistor electrically coupled to a first power source;
• a first capacitive element electrically coupled between the transistor and a first reference power source;
• a second capacitive element electrically coupled between the first power source, the first capacitive element and a second reference power source;
• a first light receiving element electrically coupled between the first and third reference power sources and controlling a coupling voltage of the first capacitive element and charge/discharge voltages of the second capacitive element by conducting current in response to ambient light;
• a first switch electrically coupled to the transistor and enabling the transistor to output current from the first power source according to the coupling voltage of the first capacitive element;
• and a second switch electrically coupled between the first light receiving element and the first capacitive element and interrupting a leakage current of the first light receiving element, thereby preventing the coupling voltage of the first capacitive element from being changed;
• an ambient light control processor receiving an analog output signal from the ambient light sensor circuit as an input signal and calculating a present ambient light and outputting it as a digital value;
• a timing controller receiving the output signal from the ambient light control processor as an input signal and outputting a control signal corresponding to the present ambient light;
• and
• an organic electroluminescence panel receiving the control signal corresponding to the present ambient light applied from the timing controller and light-emitting with a brightness corresponding to the present ambient light.

A flat panel display device, comprising:

• an ambient light sensor circuit which includes:
• a transistor electrically coupled to a first power source;
• a first capacitive element electrically coupled between the transistor and a first reference power source;
• a second capacitive element electrically coupled between the first power source, the first capacitive element and a second reference power source;
• a first light receiving element electrically coupled between the first and third reference power sources and controlling a coupling voltage of the first capacitive element and charge/discharge voltages of the second capacitive element by conducting current in response to ambient light;
• a first switch electrically coupled to the transistor and enabling the transistor to output current from the first power source according to the coupling voltage of the first capacitive element;
• and a second switch electrically coupled between the first light receiving element and the first capacitive element and interrupting a leakage current of the first light receiving element, thereby preventing the coupling voltage of the first capacitive element from being changed;
• an ambient light control processor receiving an analog output signal from the ambient light sensor circuit as an input signal and calculating a present ambient light and outputting it as a digital value;
• a timing controller receiving the output signal from the ambient light control processor as an input signal and outputting a control signal corresponding to the present ambient light;
• an inverter receiving the output signal from the timing controller as an input signal and boosting the power voltage to a level corresponding to the present ambient light and outputting it;
• a backlight turned on/off by a voltage supplied from the inverter;
• and
• a liquid crystal display panel displaying a screen by the backlight.