Pixel structure of a sunlight readable display
First Claim
1. A pixel structure of a sunlight readable display, comprising:
- a first thin film transistor comprising a source electrode, a drain electrode and a gate electrode;
a second thin film transistor comprising a source electrode, a drain electrode and a gate electrode, said gate electrode of said second thin film transistor being electrically connected to said drain electrode of said first thin film transistor;
a first storage capacitor having one end electrically connected to said gate electrode of said second thin film transistor;
a third thin film transistor comprising a source electrode, a drain electrode and a gate electrode, said drain electrode of said third thin film transistor being electrically connected to said drain electrode of said first thin film transistor;
a second storage capacitor having one end electrically connected to said source electrode of said third thin film transistor and another end connected to a common bus, said second storage capacitor being a liquid crystal capacitor; and
an organic light emitting diode display device electrically connected to said drain electrode of said second thin film transistor, said organic light emitting diode display device comprising a half organic light emitting diode display structure and a half reflective liquid crystal display structure;
wherein said display is in an organic light emitting diode mode when said third thin film transistor is at an OFF state, and said display is in a liquid crystal mode when said third thin film transistor is at an ON state.
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Abstract
A display that is readable under direct sunlight comprises a half organic light emitting diode structure and a half reflective liquid crystal display structure. It uses a thin film transistor as a switch to solve the problem of crosstalk between the organic light emitting diode mode and the liquid crystal mode as well as the dc residual problem and has the advantages of both display structures. The data signals in organic light emitting diode mode and liquid crystal mode are controlled by different control systems. By properly selecting liquid crystal material and organic light emitting diode material such that the ranges of the data signals are similar, one data driver can be shared between the two modes.
130 Citations
11 Claims
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1. A pixel structure of a sunlight readable display, comprising:
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a first thin film transistor comprising a source electrode, a drain electrode and a gate electrode;
a second thin film transistor comprising a source electrode, a drain electrode and a gate electrode, said gate electrode of said second thin film transistor being electrically connected to said drain electrode of said first thin film transistor;
a first storage capacitor having one end electrically connected to said gate electrode of said second thin film transistor;
a third thin film transistor comprising a source electrode, a drain electrode and a gate electrode, said drain electrode of said third thin film transistor being electrically connected to said drain electrode of said first thin film transistor;
a second storage capacitor having one end electrically connected to said source electrode of said third thin film transistor and another end connected to a common bus, said second storage capacitor being a liquid crystal capacitor; and
an organic light emitting diode display device electrically connected to said drain electrode of said second thin film transistor, said organic light emitting diode display device comprising a half organic light emitting diode display structure and a half reflective liquid crystal display structure;
wherein said display is in an organic light emitting diode mode when said third thin film transistor is at an OFF state, and said display is in a liquid crystal mode when said third thin film transistor is at an ON state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
a lower glass substrate having top and bottom surfaces;
a quarter-wave film formed beneath said lower glass substrate;
a polarizer formed beneath said quarter-wave film;
a black matrix formed on said top surface of said lower glass substrate;
a buffer layer formed on said black matrix and said top surface of said lower glass substrate;
a poly-Si layer formed on said buffer layer for defining regions of said source and drain electrodes of said second and third thin film transistors;
a dielectric layer formed on said poly-Si layer;
a gate layer formed on said dielectric layer for defining regions of said gate electrodes of said second and third thin film transistors and for defining regions of one counter electrode of said first storage capacitor;
an intermediate layer formed on said gate layer and said poly-Si layer, said intermediate layer having a plurality of contact holes;
a metal layer formed on said intermediate layer;
a first passivation layer covering said metal layer;
an anode layer of transparent material formed on a portion of said first passivation layer, said anode layer being electrically connected to said drain electrode of said second thin film transistor;
a layer of organic light emitting diode material formed on said anode layer of transparent material and a portion of said first passivation layer;
a transparent cathode layer formed on said layer of organic light emitting diode material;
a second passivation layer covering said transparent cathode layer and said first passiviation layer;
a pixel electrode layer formed on said second passivation layer and connected to said drain electrode of said third thin film transistor;
an upper glass substrate having top and bottom surfaces;
a reflective metal layer formed beneath said bottom surface of said upper glass substrate;
a color filter formed beneath said reflective metal layer; and
a liquid crystal layer disposed between said color filter and said pixel electrode layer.
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7. The pixel structure of a sunlight readable display as claimed in claim 6, said pixel electrode layer being a transparent electrode layer.
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8. The pixel structure of a sunlight readable display as claimed in claim 6, wherein when said organic light emitting diode display device is at an ON state, light path in said layer of organic light emitting diode is downward and liquid crystal molecules in said liquid crystal layer are operated at a normally black mode;
- and when said organic light emitting diode display device is at an OFF state, said organic light emitting diode display device is transparent and liquid crystal molecules in said liquid crystal layer are operated normally.
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9. The pixel structure of a sunlight readable display as claimed in claim 1, said organic light emitting diode display device comprising:
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a lower glass substrate;
a reflective metal layer formed on said lower glass substrate;
a buffer layer formed on said reflective metal layer;
a poly-Si layer formed on said buffer layer for defining regions of said source and drain electrodes of said second and third thin film transistors;
a dielectric layer formed on said poly-Si layer;
a gate layer formed on said dielectric layer for defining regions of said gate electrodes of said second and third thin film transistors and for defining regions of one counter electrode of said first storage capacitor;
an intermediate layer formed on said gate layer and said poly-Si layer, said intermediate layer having a plurality of contact holes;
a metal layer formed on said intermediate layer;
a first passivation layer covering said metal layer and said intermediate layer;
an anode layer of transparent material formed on a portion of said first passivation layer, said anode layer being electrically connected to said drain electrode of said second thin film transistor;
a layer of organic light emitting diode material formed on said anode layer of transparent material and a portion of said first passivation layer;
a transparent cathode layer formed on said layer of organic light emitting diode material;
a second passivation layer covering said transparent cathode layer and said first passiviation layer;
a pixel electrode layer formed on said second passivation layer and connected to said drain electrode of said third thin film transistor;
an upper glass substrate having top and bottom surfaces;
a color filter formed beneath said bottom surface of said upper glass substrate;
a transparent electrode layer formed beneath said color filter;
a quarter-wave film formed on said top surface of said upper glass substrate;
a polarizer film formed on said quarter-wave film; and
a liquid crystal layer disposed between said transparent electrode layer and said pixel electrode layer.
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10. The pixel structure of a sunlight readable display as claimed in claim 9, said pixel electrode layer being a transparent electrode layer.
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11. The pixel structure of a sunlight readable display as claimed in claim 9, wherein when said organic light emitting diode display device is at an ON state, light path in said liquid crystal layer is upward, said liquid crystal layer is transparent and liquid crystal molecules in said liquid crystal layer are operated at a normally white mode;
- and when said organic light emitting diode display device is at an OFF state, said organic light emitting diode display device is transparent and liquid crystal molecules in said liquid crystal layer are operated normally.
Specification