OLED ACTIVE DRIVING SYSTEM WITH CURRENT FEEDBACK
First Claim
1. An organic light emitting diode active driving system with current feedback for driving an organic light emitting diode, comprising:
- a first transistor having a current carrying electrode connected to a cathode of said organic light emitting diode, a current carrying electrode connected to ground, and a gate electrode;
a second transistor having a current carrying electrode connected to a gate electrode of said first transistor, a current carrying electrode as a data signal input terminal, and a gate electrode as a scan signal input terminal;
a capacitor connected between said gate electrode of said first transistor and ground as a storage element;
a current comparator having two comparison terminals and an output terminal connected to said data signal input terminal;
a third transistor having a current carrying electrode connected to an anode of said organic light emitting diode, a current carrying electrode connected to a comparison terminal of said current comparator, and a gate electrode connected to said scan signal input terminal; and
a fourth transistor having a current carrying electrode connected to an anode of said organic light emitting diode, a current carrying electrode connected to a first supply voltage, and a gate electrode for receiving a reverse signal of said scan signal input terminal;
wherein said two comparison terminals of said current comparator respectively receive a reference current with a predetermined value and a driving current flowing through said organic light emitting diode, compare said reference current and said driving current, and output a voltage to said data input terminal in response to a comparison result, so that the value of said driving current equals to that of said reference current.
5 Assignments
0 Petitions
Accused Products
Abstract
The invention provides an organic light emitting diode active driving system with current feedback, thereby a driving current for organic light emitting diode is not affected by variation of characteristic parameters of thin film transistor under an active driving mode. The active driving system in accordance with the invention includes a transistor and a current comparator for driving an organic light emitting diode. The transistor has two current carrying electrodes respectively connected to a cathode of the organic light emitting diode and ground, and a gate controlled by a data signal. The current comparator has two input terminals respectively receive a reference current with predetermined value and a driving current flowing through the organic light emitting diode. The current comparator compares the reference current and the driving current, and then outputs a voltage to the gate of the transistor in response to the comparison result so as to make the value of the driving current equal to that of the reference current. Therefore, the active driving system for organic light emitting diode array or flat panel display in accordance with the invention can achieve a desirable light emission uniformity.
256 Citations
8 Claims
-
1. An organic light emitting diode active driving system with current feedback for driving an organic light emitting diode, comprising:
-
a first transistor having a current carrying electrode connected to a cathode of said organic light emitting diode, a current carrying electrode connected to ground, and a gate electrode;
a second transistor having a current carrying electrode connected to a gate electrode of said first transistor, a current carrying electrode as a data signal input terminal, and a gate electrode as a scan signal input terminal;
a capacitor connected between said gate electrode of said first transistor and ground as a storage element;
a current comparator having two comparison terminals and an output terminal connected to said data signal input terminal;
a third transistor having a current carrying electrode connected to an anode of said organic light emitting diode, a current carrying electrode connected to a comparison terminal of said current comparator, and a gate electrode connected to said scan signal input terminal; and
a fourth transistor having a current carrying electrode connected to an anode of said organic light emitting diode, a current carrying electrode connected to a first supply voltage, and a gate electrode for receiving a reverse signal of said scan signal input terminal;
wherein said two comparison terminals of said current comparator respectively receive a reference current with a predetermined value and a driving current flowing through said organic light emitting diode, compare said reference current and said driving current, and output a voltage to said data input terminal in response to a comparison result, so that the value of said driving current equals to that of said reference current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
Specification