US 2009/0015166 A1Published application

Ambient light sensing circuit and flat panel display including ambient light sensing circuit

AssigneesSamsung SDI Co., Ltd., Iucf-Hyu (Industry-University Cooperation Foundation Hanyang University)

InventorOhkyong Kwon

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Abstract

An ambient light sensing circuit includes a transistor, a first storage capacitor coupled to the transistor and adapted to compensate for a threshold voltage of the transistor, a second storage capacitor coupled to the first storage capacitor, a photodiode coupled to the first storage capacitor and the second storage capacitor and adapted to change a coupling voltage of the first and second storage capacitors based on ambient light incident thereon, a first switch adapted to selectively apply the first power supply voltage to the output load coupled to the transistor, and a second switch coupled to a first electrode of the transistor and the output load, and adapted to allow a charge stored in the storage capacitor to be discharged through the transistor based on the coupling voltage of the first storage capacitor and the second storage capacitor.

Claims20

Dependent claims

An ambient light sensing circuit adapted to be electrically coupled to a first power supply for supplying a first power supply voltage and an output load coupled to a storage capacitor, the ambient light sensing circuit comprising:

a transistor;
a first storage capacitor coupled to the transistor and adapted to compensate for a threshold voltage of the transistor;
a second storage capacitor coupled to the first storage capacitor;
a photodiode coupled to the first storage capacitor and the second storage capacitor, the photodiode being adapted to change a coupling voltage of the first storage capacitor and the second storage capacitor based on ambient light incident thereon;
a first switch adapted to selectively apply the first power supply voltage to the output load coupled to the transistor;
and
a second switch including a first electrode coupled to a first electrode of the transistor, and a second electrode coupled to the output load and a first electrode of the first switch, the second switch being adapted to allow a charge stored in the storage capacitor to be discharged through the transistor based on the coupling voltage of the first storage capacitor and the second storage capacitor.

4 more elements

A flat panel display, comprising:

an ambient light sensing circuit adapted to be electrically coupled to a first power supply for supplying a first power supply voltage and an output load coupled to a storage capacitor, the ambient light sensing circuit including:
a transistor;
a first storage capacitor coupled to the transistor and adapted to compensate for a threshold voltage of the transistor;
a second storage capacitor coupled to the first storage capacitor;
a photodiode coupled to the first storage capacitor and the second storage capacitor, and adapted to change a coupling voltage of the first storage capacitor and the second storage capacitor based on ambient light incident thereon;
a first switch adapted to selectively apply the first power supply voltage to the output load coupled to the transistor;
and
a second switch including a first electrode coupled to a first electrode of the transistor, and a second electrode coupled to the output load and a first electrode of the first switch, the second switch being adapted to allow a charge stored in the storage capacitor to be discharged through the transistor based on the coupling voltage of the first storage capacitor and the second storage capacitor;
an ambient light control processor coupled to the second electrode of the second switch of the ambient light sensing circuit, and adapted to calculate an amount of present ambient light based on an analog signal supplied from the first electrode of the transistor and to output a digital value corresponding to the amount of present ambient light;
and
a timing controller that outputs a control corresponding to the present ambient light based on the digital value output by the ambient light control processor.

8 more elements

Dependencies are inferred from the claim text.