Pixel current driver for organic light emitting diode displays
First Claim
1. A pixel current driver for an organic light emitting diode (OLED) having an OLED layer for emitting light, comprising:
- an address line;
a data line; and
a plurality of thin film transistors (TFTs) forming a current mirror, each having dual gates and driving for the OLED layer, the plurality of thin film transistors comprising;
a switch thin film transistor, a first node of the switch transistor being connected to the data line and a first gate of the dual gates of the switch transistor being connected to the address line;
a feedback thin film transistor, a first node of the feedback transistor being connected to the data line and a first gate of the dual gates of the feedback transistor being connected to the address line;
a reference thin film transistor, a drain of the reference transistor being connected to a second node of the feedback transistor, a first gate of the dual gates of the reference transistor being connected to a second node of the switch transistor and a source of the reference transistor being connected to a ground potential; and
a drive thin film transistor, a first gate of the dual gates of the drive transistor being connected to the gate of the reference transistor,a second gate of the dual gates of each thin film transistor being formed between a back electrode of the organic light emitting diode and the first gate of the respective thin film transistor.
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Accused Products
Abstract
A pixel current driver comprises a plurality of thin film transistors (TFTs) each having dual gates and for driving OLED layers. A top gate of the dual gates is formed between a source and a drain of each of the thin film transistors, to thereby minimize parasitic capacitance. The top gate is grounded or electrically tied to a bottom gate. The plurality of thin film transistors may be two thin film transistors formed in voltage-programmed manner or five thin film transistors formed in a current-programmed ΔVT-compensated manner. Other versions of the current-programmed circuit with different numbers of thin film transistors are also presented that compensate for δVT. The OLED layer are continuous and vertically stacked on the plurality of thin film transistors to provide an aperture ratio close to 100%.
278 Citations
7 Claims
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1. A pixel current driver for an organic light emitting diode (OLED) having an OLED layer for emitting light, comprising:
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an address line; a data line; and a plurality of thin film transistors (TFTs) forming a current mirror, each having dual gates and driving for the OLED layer, the plurality of thin film transistors comprising; a switch thin film transistor, a first node of the switch transistor being connected to the data line and a first gate of the dual gates of the switch transistor being connected to the address line; a feedback thin film transistor, a first node of the feedback transistor being connected to the data line and a first gate of the dual gates of the feedback transistor being connected to the address line; a reference thin film transistor, a drain of the reference transistor being connected to a second node of the feedback transistor, a first gate of the dual gates of the reference transistor being connected to a second node of the switch transistor and a source of the reference transistor being connected to a ground potential; and a drive thin film transistor, a first gate of the dual gates of the drive transistor being connected to the gate of the reference transistor, a second gate of the dual gates of each thin film transistor being formed between a back electrode of the organic light emitting diode and the first gate of the respective thin film transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification