Video rate ChLCD driving with active matrix backplanes
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IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
G09G-005/00
G09G-003/36
출원번호
US-0629243
(2009-12-02)
등록번호
US-8436847
(2013-05-07)
발명자
/ 주소
Marhefka, Duane
Huang, Xiao-Yang
출원인 / 주소
Kent Displays Incorporated
대리인 / 주소
Pearne & Gordon LLP
인용정보
피인용 횟수 :
0인용 특허 :
8
초록▼
A device and method providing a pixel architecture that, in at least one embodiment, contains both an on/off memory element and a switching element to utilize low-power liquid crystal displays for video or near-video applications. Such an embodiment can be implemented, for example, using a pair of T
A device and method providing a pixel architecture that, in at least one embodiment, contains both an on/off memory element and a switching element to utilize low-power liquid crystal displays for video or near-video applications. Such an embodiment can be implemented, for example, using a pair of TFTs for implementing the memory element and switching element on a common substrate. Other embodiments can utilize actual memory devices for the memory elements. This device and method are particularly useful for driving cholestric display elements for video or near video rate applications.
대표청구항▼
1. A display device comprising: a plurality of individually driven display elements; anda plurality of driving elements, each one of said driving elements for driving an associated one of said display elements, each one of said driving elements including: a storage element for storing an on/off stat
1. A display device comprising: a plurality of individually driven display elements; anda plurality of driving elements, each one of said driving elements for driving an associated one of said display elements, each one of said driving elements including: a storage element for storing an on/off state; anda switching element connected to the associated display element for connecting said associated display element to a source voltage, said connecting based on the state of said storage element, whereinsaid source voltage is varied between at least two different voltages during an update of a state of the associated display element. 2. The display device of claim 1, wherein said display device is a bistable display. 3. The display device of claim 1, wherein said display device is a cholesteric liquid crystal display. 4. The display device of claim 1, wherein when said storage element is storing an “ON” state, the switching element is applying a selected voltage source across said associated element of the display, whereas when said storage element is storing an “OFF” state, said switching element removes said selected voltage source from said associated element of the display. 5. The display device of claim 4, wherein said selected voltage source is varied during said “ON” state. 6. The display device of claim 4, wherein said selected voltage source is varied during said “OFF” state. 7. The display device of claim 1, wherein said selected voltage source is amplitude modulated such that the voltage amplitude is changed during said “ON” state. 8. The display device of claim 4, wherein said display is a cholesteric liquid crystal display, and wherein said selected voltage is about equal to or greater than ±14 volts. 9. The display device of claim 1, wherein said storage element is comprised of at least one transistor connected to a capacitor, and wherein said switching element is comprised of at least one transistor having an input directly connected to an output of said storage element. 10. The display device of claim 9, wherein said switching element connects and disconnects said corresponding display element to a voltage source based on the state of said storage element. 11. The display device of claim 1, wherein the storage elements of said plurality of driving elements are provided by a memory device. 12. The display device of claim 1, wherein said storage elements of said plurality of driving elements are arranged into at least one shift register. 13. The display device of claim 1, wherein the storage elements of said plurality of driving elements are arranged into a memory having states set using address and data inputs. 14. A display device comprising: a plurality of individually driven display elements; anda plurality of driving elements arranged as a matrix, each one of said driving elements for driving an associated one of said display elements, each one of said driving elements including: a first thin-film transistor for storing an “ON” or “OFF” state; anda second thin-film transistor connected to the associated display element for connecting said associated display element to a source voltage, said connecting based on the “ON” or “OFF” state stored by said first transistor. 15. The display device of claim 14, further comprising a capacitor attached to said first thin-film transistor, where said first thin-film transistor and said capacitor form a storage device for storing the “ON” or “OFF” state, where said connecting said associated display element to a source voltage by said second thin-film transistor is based on the current state of said storage device. 16. The display device of claim 15, wherein said individually driven display elements are comprised of a cholesteric liquid crystal material having bistable properties. 17. The display device of claim 14, wherein one or both of said first thin-film transistor and said second thin-film transistor is arranged as a dual-gate transistor to reduce leakage currents. 18. A display device comprising: a plurality of individually driven display elements; anda plurality of driving elements, each one of said driving elements for driving an associated one of said display elements, each one of said driving elements including: a first input;a second input;a storage element for storing an on/off state for at least a certain period of time, wherein said on/off state is based on data provided at said first input and second input; anda switching element including an input connected to a voltage source, said switching element for driving the associated display element based on the state of said storage element such that when said storage element transitions to an “ON” state, the switching element connects a voltage source to said associated display element to apply a charge to said associated display element, whereas when said storage element thereafter transitions to an “OFF” state, said switching element removes said voltage source from said associated element of the display while substantially maintaining the charge on said display element. 19. The display device of claim 18, wherein said voltage source is held substantially constant during said “ON” state. 20. The display device of claim 18, wherein said voltage source is varied during said “ON” state. 21. The display device of claim 20, wherein said voltage source is amplitude modulated such that the voltage amplitude is changed during said “ON” state. 22. The display device of claim 18, wherein said voltage source is amplitude modulated such that the voltage amplitude is changed during said “OFF” state 23. The display device of claim 18, wherein said voltage source is toggled between a positive value during a first “ON” state and a negative value during a second “ON” state with at least one intervening “OFF” state being provided between said first “ON” state and said second “ON” state. 24. The display device of claim 18, wherein, during a refresh period, a regular series of voltage pulses is provided to said first input, and wherein an series of differently spaced voltage pulses are provided to said second input. 25. A display device comprising: a plurality of cholesteric liquid crystal display elements arranged as a matrix of columns and rows; anda plurality of driving elements, each one of said driving elements for driving an associated one of said display elements, each one of said driving elements including: a storage element for storing an “ON”/“OFF” state for at least a certain period of time, said storage element having a column input and a row input, wherein said on/off state is based on a signal provided at said column input and a different signal provided at said row input; anda switching element for driving the associated display element based on the state of said storage element, such that when said storage element is storing an “ON” state, the driving element applies a selected voltage source across said associated element of the display, whereas when said storage element is storing an “OFF” state, said switching element removes said selected voltage source from said associated element of the display;wherein the column inputs of the storage elements of said plurality of driving elements that are in the same column are tied to a common column signal source, andwherein the row inputs of the storage elements of said plurality of driving elements that are in the same row are tied to a common row signal source, andwherein the row signal sources and column signal sources are used to set the state of the storage elements to set a reflectance and/or transmittance of the associated display elements to generate a display image on said display. 26. The display device of claim 25, wherein said row, column, and voltage sources are provided in a manner such that said reflectance and/or transmittance of each of the display elements are varied for providing a plurality of gray scales by controlling a transition of the liquid crystal of the display element from a homeotropic to a planar state. 27. The display device of claim 25, wherein said row, column, and voltage sources are provided in a manner such that said reflectance and/or transmittance of each of the display elements are varied by varying a voltage applied to the liquid crystal of the display element while the liquid crystal is primarily maintained in a planar state. 28. The display device of claim 25, wherein said row, column, and voltage sources are provided in a manner such that said reflectance and/or transmittance of each of the display elements are varied by varying a voltage applied to the liquid crystal to control transitions between the planar state and the homeotropic state. 29. The display device of claim 25, wherein said display device is arranged on a backplane with said display elements and associated driving elements arranged in a plurality of rows, and wherein while a first set of N rows are in an idle time to allow the cholesteric liquid crystal material to relax, addressing a second set of N rows during said idle time. 30. The display device of claim 29, wherein during said idle time, addressing a third set of N rows. 31. The display device of claim 25, wherein said row, column, and voltage sources are provided in a manner such that said reflectance and/or transmittance of each of the display elements are varied by applying corresponding sequences of voltage pulses to each of said display elements whose root mean square amplitudes are adjusted to select the desired gray scale levels of the associated display elements. 32. The display device of claim 31, wherein the root mean square amplitudes of the pulses are controlled through amplitude modulation. 33. The display device of claim 31, wherein the root mean square amplitudes of the pulses are controlled through pulse width modulation. 34. A display device comprising: a plurality of individually driven display elements; anda plurality of driving elements, each one of said driving elements for driving an associated one of said display elements, each one of said driving elements including: a first input;a second input;a storage element for storing an on/off state for at least a certain period of time, wherein said on/off state is based on data provided at said first input and second input; anda switching element including an input connected to a voltage source, said switching element for driving the associated display element based on the state of said storage element such that when said storage element transitions to an “ON” state, the switching element connects a voltage source to said associated display element to set a state of the associated display element, whereas when said storage element thereafter transitions to an “OFF” state, said switching element removes said voltage source from said associated element of the display while substantially maintaining the state of the display element.
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이 특허에 인용된 특허 (8)
Fish, David A.; Bird, Neil C., Bistable chiral nematic liquid crystal display and method of driving the same.
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