DRIVING CIRCUIT CAPABLE OF SIMULTANEOUSLY DRIVING THREE-COLOR BISTABLE LIQUID CRYSTALS

• US 20090096738A1
• Filed: 08/12/2008
• Published: 04/16/2009
• Est. Priority Date: 10/12/2007
• Status: Abandoned Application

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: CHEN, Tai-Ann, HSIAO, Chih-Wen, CHEN, Chih-Jen
• Application Number:
  US12/189,994
• Publication Number:
  US 20090096738A1
• Time in Patent Office: Days
• US Class Current: 345/98
• CPC Class Codes: G09G 2310/0291 Details of output amplifiers or buffers arranged for use in a driving circuit
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals
• CPC Class Codes: G09G 3/3651 using multistable liquid crystals, e.g. ferroelectric liquid crystals
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: G09G 3/3692 suitable for passive matrices only

Abstract

This invention provides a driving circuit for simultaneously driving three-color bistable liquid crystals, which employs a voltage-shift circuit to provide different-color bistable liquid crystals with respective level-shift voltages. A grey-scale voltage is respectively added to the respective level-shift voltages. By this invention, the whole grey-scale voltages are capable of falling in the voltage ranges for displaying grey scales for the different-color bistable liquid crystals. The grey-scale display can be optimized.

Claims

1. A driving circuit capable of simultaneously driving three-color bistable liquid crystals, comprising:

a driving voltage input circuit for receiving an input voltage from the external so as to output a predetermined driving voltage; and

a voltage-shift circuit including a plurality of sub-voltage-shift circuit, wherein the predetermined driving voltage and a predetermined level-shift voltage required by a liquid crystal cell are inputted to one of said sub-voltage-shift circuit corresponding thereto via the same input terminal or different input terminals of said sub-voltage-shift circuit, and said sub-voltage-shift circuit via an output terminal thereof outputs a liquid crystal driving voltage to an electrode terminal of the liquid crystal cell.

2. The driving circuit capable of simultaneously driving three-color bistable liquid crystals of claim 1, which is served as a data voltage driving circuit of a bistable liquid crystal display device.

3. The driving circuit capable of simultaneously driving three-color bistable liquid crystals of claim 1, which is served as a scan voltage driving circuit of a passive matrix bistable liquid crystal display device.

4. The driving circuit capable of simultaneously driving three-color bistable liquid crystals of claim 1, wherein said driving voltage input circuit converts the input voltage into the predetermined driving voltage by a pulse width modulation driving method.

5. The driving circuit capable of simultaneously driving three-color bistable liquid crystals of claim 1, wherein each of said sub-voltage-shift circuits corresponding to the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein an input terminal of said operational amplifier is electrically coupled to one respective terminal of said second resistor and said first resistor, and the other input terminal of said operational amplifier is electrically coupled to one respective terminal of said third resistor and said fourth resistor, an output terminal of said operational amplifier is electrically coupled to said electrode terminal of the liquid crystal cell corresponding thereto, the other terminal of said first resistor is electrically coupled to the predetermined driving voltage, the other terminal of said second resistor is electrically coupled to the predetermined level-shift voltage, the other terminae of said third resistor is grounded, and the other terminal of said fourth resistor is electrically coupled to said output terminal of said operational amplifier.

6. The driving circuit capable of simultaneously driving three-color bistable liquid crystals of claim 1, wherein each of said sub-voltage-shift circuits corresponding to the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein an input terminal of said operational amplifier is electrically coupled to one respective terminal of said first resistor and said second resistor, the other input terminal of said operational amplifier is electrically coupled to one respective terminal of said third resistor and said fourth resistor, an output terminal of said operational amplifier is electrically coupled to said electrode terminal of the liquid crystal cell corresponding thereto, the other terminal of said first resistor is electrically coupled to said output terminal of said operational amplifier, the other terminal of said second resistor is electrically coupled to the predetermined driving voltage, the other terminal of said third resistor is grounded, and the other terminal of said fourth resistor is electrically coupled to the predetermined level-shift voltage.

7. The driving circuit capable of simultaneously driving three-color bistable liquid crystals of claim 1, wherein each of said sub-voltage-shift circuits corresponding to the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein an input terminal of said operational amplifier is electrically coupled to the predetermined driving voltage, the other input terminal of said operational amplifier is electrically coupled to one respective terminal of said first resistor and said second resistor, an output terminal of said operational amplifier is electrically coupled to said electrode terminal of the liquid crystal cell corresponding thereto, the other terminal of said first resistor is electrically coupled to said output terminal of said operational amplifier, the other terminal of said second resistor is electrically coupled to one respective terminal of said third resistor and said fourth resistor, the other terminal of said third resistor is grounded, and the other terminal of said fourth resistor is electrically coupled to the predetermined level-shift voltage.

8. The driving circuit capable of simultaneously driving three-color bistable liquid crystals of claim 1, wherein each of said sub-voltage-shift circuits corresponding to the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor and a third resistor, wherein an input terminal of said operational amplifier is electrically coupled to one respective terminal of said first resistor, said second resistor and said third resistor, the other input terminal of said operational amplifier is grounded, an output terminal of said operational amplifier is electrically coupled to said electrode terminal of the liquid crystal cell corresponding thereto, the other terminal of said first resistor is electrically coupled to said output terminal, the other terminal of said second resistor is electrically coupled to the predetermined driving voltage, and the other terminal of said third resistor is electrically coupled to the predetermined level-shift voltage.

9. The driving circuit capable of simultaneously driving three-color bistable liquid crystals of claim 2, wherein said driving voltage input circuit includes a data voltage driving circuit, a level shifter and a digital-to-analog converter, said data voltage driving circuit receives the input voltage in digital form, and then which is shifted to the predetermined driving voltage in digital form by said level shifter, and the predetermined driving voltage in digital form is converted to an equal value in analog form by said digital-to-analog converter.

10. A passive matrix three-color bistable liquid crystal display device, including:

a display area including plural rows of first color bistable liquid crystal cells aligned in the vertical direction, plural rows of second color bistable liquid crystal cells aligned in the vertical direction and plural rows of third color bistable liquid crystal cells aligned in the vertical direction, wherein each row of the first color liquid crystal cells includes a plurality of liquid crystal cells, each row of the second color liquid crystal cells includes a plurality of liquid crystal cells and each row of the third color liquid crystal cells includes a plurality of liquid crystal cells, and the first color liquid crystal cells, the second color liquid crystal cells and the third color liquid crystal cells are inter-disposed to each other in the parallel direction;

a scan voltage driving circuit including a plurality of scan lines sequentially and respectively providing a scan voltage to the liquid crystal cells corresponding thereto; and

a data voltage driving circuit with level-shift voltage including a driving voltage input circuit and a voltage-shift circuit, wherein said driving voltage input circuit receives an input voltage from the external so as to output a predetermined driving voltage, said voltage-shift circuit includes a plurality of sub-voltage-shift circuit, the predetermined driving voltage and a predetermined level-shift voltage required by a liquid crystal cell are inputted to one of said sub-voltage-shift circuit corresponding thereto via the same input terminal or different input terminals of said sub-voltage-shift circuit, and said sub-voltage-shift circuit via an output terminal thereof outputs a liquid crystal driving voltage to an electrode terminal of the liquid crystal cell.

11. The passive matrix three-color bistable liquid crystal display device of claim 10, wherein said driving voltage input circuit converts the input voltage into the predetermined driving voltage by a pulse width modulation driving method.

12. The passive matrix three-color bistable liquid crystal display device of claim 10, wherein each of said sub-voltage-shift circuits corresponding to the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein an input terminal of said operational amplifier is electrically coupled to one respective terminal of said second resistor and said first resistor, and the other input terminal of said operational amplifier is electrically coupled to one respective terminal of said third resistor and said fourth resistor, an output terminal of said operational amplifier is electrically coupled to said electrode terminal of the liquid crystal cell corresponding thereto, the other terminal of said first resistor is electrically coupled to the predetermined driving voltage, the other terminal of said second resistor is electrically coupled to the predetermined level-shift voltage, the other terminal of said third resistor is grounded, and the other terminal of said fourth resistor is electrically coupled to said output terminal of said operational amplifier.

13. The passive matrix three-color bistable liquid crystal display device of claim 10, wherein each of said sub-voltage-shift circuits corresponding to the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein an input terminal of said operational amplifier is electrically coupled to one respective terminal of said first resistor and said second resistor, the other input terminal of said operational amplifier is electrically coupled to one respective terminal of said third resistor and said fourth resistor, an output terminal of said operational amplifier is electrically coupled to said electrode terminal of the liquid crystal cell corresponding thereto, the other terminal of said first resistor is electrically coupled to said output terminal of said operational amplifier, the other terminal of said second resistor is electrically coupled to the predetermined driving voltage, the other terminal of said third resistor is grounded, and the other terminal of said fourth resistor is electrically coupled to the predetermined level-shift voltage.

14. The passive matrix three-color bistable liquid crystal display device of claim 10, wherein each of said sub-voltage-shift circuits corresponding to the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein an input terminal of said operational amplifier is electrically coupled to the predetermined driving voltage, the other input terminal of said operational amplifier is electrically coupled to one respective terminal of said first resistor and said second resistor, an output terminal of said operational amplifier is electrically coupled to said electrode terminal of the liquid crystal cell corresponding thereto, the other terminal of said first resistor is electrically coupled to said output terminal of said operational amplifier, the other terminal of said second resistor is electrically coupled to one respective terminal of said third resistor and said fourth resistor, the other terminal of said third resistor is grounded, and the other terminal of said fourth resistor is electrically coupled to the predetermined level-shift voltage.

15. The passive matrix three-color bistable liquid crystal display device of claim 10, wherein each of said sub-voltage-shift circuits corresponding to the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor and a third resistor, wherein an input terminal of said operational amplifier is electrically coupled to one respective terminal of said first resistor, said second resistor and said third resistor, the other terminal of said operational amplifier is grounded, an output terminal of said operational amplifier is electrically coupled to said electrode terminal of the liquid crystal cell corresponding thereto, the other terminal of said first resistor is electrically coupled to said output terminal, the other terminal of said second resistor is electrically coupled to the predetermined driving voltage, and the other terminal of said third resistor is electrically coupled to the predetermined level-shift voltage.

16. A passive matrix three-color bistable liquid crystal display device, including:

a display area including plural rows of first color bistable liquid crystal cells aligned in the parallel direction, plural rows of second color bistable liquid crystal cells aligned in the parallel direction and plural rows of third color bistable liquid crystal cells aligned in the parallel direction, wherein each row of the first color liquid crystal cells includes a plurality of liquid crystal cells, each row of the second color liquid crystal cells includes a plurality of liquid crystal cells and each row of the third color liquid crystal cells includes a plurality of liquid crystal cells, and the first color liquid crystal cells, the second color liquid crystal cells and the third color liquid crystal cells are inter-disposed to each other in the vertical direction;

a scan voltage driving circuit with level-shift voltage including a plurality of scan lines sequentially and respectively providing a scan voltage to the liquid crystal cells corresponding thereto, wherein said scan voltage driving circuit including a driving voltage input circuit and a voltage-shift circuit, said driving voltage input circuit receives an input voltage from the external so as to output a predetermined driving voltage, said voltage-shift circuit includes a plurality of sub-voltage-shift circuit, the predetermined driving voltage and a predetermined level-shift voltage required by a liquid crystal cell are inputted to one of said sub-voltage-shift circuit corresponding thereto via the same input terminal or different input terminals of said sub-voltage-shift circuit, and said sub-voltage-shift circuit via an output terminal thereof outputs a scan voltage to an electrode terminal of one row of the liquid crystal cells corresponding thereto through one of the scan lines corresponding thereto; and

a data voltage driving circuit including a plurality of data lines respectively providing a data voltage to the row of liquid crystal cells corresponding thereto.

17. The passive matrix three-color bistable liquid crystal display device of claim 16, wherein said driving voltage input circuit converts the input voltage into the predetermined driving voltage by a pulse width modulation driving method.

18. The passive matrix three-color bistable liquid crystal display device of claim 16, wherein each of said sub-voltage-shift circuits corresponding to the scan lines of the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein an input terminal of said operational amplifier is electrically coupled to one respective terminal of said second resistor and said first resistor, and the other input terminal of said operational amplifier is electrically coupled to one respective terminal of said third resistor and said fourth resistor, an output terminal of said operational amplifier is electrically coupled to one of the scan lines corresponding thereto, the other terminal of said first resistor is electrically coupled to the predetermined driving voltage, the other terminal of said second resistor is electrically coupled to the predetermined level-shift voltage, the other terminal of said third resistor is grounded, and the other terminal of said fourth resistor is electrically coupled to said output terminal of said operational amplifier.

19. The passive matrix three-color bistable liquid crystal display device of claim 16, wherein each of said sub-voltage-shift circuits corresponding to the scan lines of the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein an input terminal of said operational amplifier is electrically coupled to one respective terminal of said first resistor and said second resistor, the other input terminal of said operational amplifier is electrically coupled to one respective terminal of said third resistor and said fourth resistor, an output terminal of said operational amplifier is electrically coupled to one of the scan lines corresponding thereto, the other terminal of said first resistor is electrically coupled to said output terminal of said operational amplifier, the other terminal of said second resistor is electrically coupled to the predetermined driving voltage, the other terminal of said third resistor is grounded, and the other terminal of said fourth resistor is electrically coupled to the predetermined level-shift voltage.

20. The passive matrix three-color bistable liquid crystal display device of claim 16, wherein each of said sub-voltage-shift circuits corresponding to the scan lines of the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein an input terminal of said operational amplifier is electrically coupled to the predetermined driving voltage, the other input terminal of said operational amplifier is electrically coupled to one respective terminal of said first resistor and said second resistor, an output terminal of said operational amplifier is electrically coupled to one of the scan lines corresponding thereto, the other terminal of said first resistor is electrically coupled to said output terminal of said operational amplifier, the other terminal of said second resistor is electrically coupled to one respective terminal of said third resistor and said fourth resistor, the other terminal of said third resistor is grounded, and the other terminal of said fourth resistor is electrically coupled to the predetermined level-shift voltage.

21. The passive matrix three-color bistable liquid crystal display device of claim 16, wherein each of said sub-voltage-shift circuits corresponding to the scan lines of the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor and a third resistor, wherein an input terminal of said operational amplifier is electrically coupled to one respective terminal of said first resistor, said second resistor and said third resistor, the other input terminal of said operational amplifier is grounded, an output terminal of said operational amplifier is electrically coupled to one of the scan lines corresponding thereto, the other terminal of said first resistor is electrically coupled to said output terminal, the other terminal of said second resistor is electrically coupled to the predetermined driving voltage, and the other terminal of said third resistor is electrically coupled to the predetermined level-shift voltage.

22. An active matrix three-color bistable liquid crystal display device, including:

a display area including plural rows of first color bistable liquid crystal cells aligned in the vertical direction, plural rows of second color bistable liquid crystal cells aligned in the vertical direction and plural rows of third color bistable liquid crystal cells aligned in the vertical direction, wherein each row of the first color liquid crystal cells includes a plurality of liquid crystal cells, each row of the second color liquid crystal cells includes a plurality of liquid crystal cells and each row of the third color liquid crystal cells includes a plurality of liquid crystal cells, and the first color liquid crystal cells, the second color liquid crystal cells and the third color liquid crystal cells are inter-disposed to each other in the parallel direction;

a scan voltage driving circuit including a plurality of scan lines sequentially and respectively providing a scan voltage to the liquid crystal cells corresponding thereto; and

a data voltage driving circuit with level-shift voltage including a driving voltage input circuit and a voltage-shift circuit, wherein said driving voltage input circuit receives an input voltage from the external so as to output a predetermined driving voltage, said voltage-shift circuit includes a plurality of sub-voltage-shift circuit, the predetermined driving voltage and a predetermined level-shift voltage required by a liquid crystal cell are inputted to one of said sub-voltage-shift circuit corresponding thereto via the same input terminal or different input terminals of said sub-voltage-shift circuit, and said sub-voltage-shift circuit via an output terminal thereof outputs a liquid crystal driving voltage to an electrode terminal of the liquid crystal cell with the other electrode terminal thereof electrically coupled to a lower voltage source.

23. The active matrix three-color bistable liquid crystal display device of claim 22, wherein said driving voltage input circuit converts the input voltage into the predetermined driving voltage by a pulse width modulation driving method.

24. The active matrix three-color bistable liquid crystal display device of claim 22, wherein each of said sub-voltage-shift circuits corresponding to the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein an input terminal of said operational amplifier is electrically coupled to one respective terminal of said second resistor and said first resistor, and the other input terminal of said operational amplifier is electrically coupled to one respective terminal of said third resistor and said fourth resistor, an output terminal of said operational amplifier is electrically coupled to said electrode terminal of the liquid crystal cell corresponding thereto, the other terminal of said first resistor is electrically coupled to the predetermined driving voltage, the other terminal of said second resistor is electrically coupled to the predetermined level-shift voltage, the other terminal of said third resistor is grounded, and the other terminal of said fourth resistor is electrically coupled to said output terminal of said operational amplifier.

25. The active matrix three-color bistable liquid crystal display device of claim 22, wherein each of said sub-voltage-shift circuits corresponding to the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein an input terminal of said operational amplifier is electrically coupled to one respective terminal of said first resistor and said second resistor, the other input terminal of said operational amplifier is electrically coupled to one respective terminal of said third resistor and said fourth resistor, an output terminal of said operational amplifier is electrically coupled to said electrode terminal of the liquid crystal cell corresponding thereto, the other terminal of said first resistor is electrically coupled to said output terminal of said operational amplifier, the other terminal of said second resistor is electrically coupled to the predetermined driving voltage, the other terminal of said third resistor is grounded, and the other terminal of said fourth resistor is electrically coupled to the predetermined level-shift voltage.

26. The active matrix three-color bistable liquid crystal display device of claim 22, wherein each of said sub-voltage-shift circuits corresponding to the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein an input terminal of said operational amplifier is electrically coupled to the predetermined driving voltage, the other input terminal of said operational amplifier is electrically coupled to one respective terminal of said first resistor and said second resistor, an output terminal of said operational amplifier is electrically coupled to said electrode terminal of the liquid crystal cell corresponding thereto, the other terminal of said first resistor is electrically coupled to said output terminal of said operational amplifier, the other terminal of said second resistor is electrically coupled to one respective terminal of said third resistor and said fourth resistor, the other terminal of said third resistor is grounded, and the other terminal of said fourth resistor is electrically coupled to the predetermined level-shift voltage.

27. The active matrix three-color bistable liquid crystal display device of claim 22, wherein each of said sub-voltage-shift circuits corresponding to the same color liquid crystal cells includes an operational amplifier, a first resistor, a second resistor and a third resistor, wherein an input terminal of said operational amplifier is electrically coupled to one respective terminal of said first resistor, said second resistor and said third resistor, the other input terminal of said operational amplifier is grounded, an output terminal of said operational amplifier is electrically coupled to said electrode terminal of the liquid crystal cell corresponding thereto, the other terminal of said first resistor is electrically coupled to said output terminal, the other terminal of said second resistor is electrically coupled to the predetermined driving voltage, and the other terminal of said third resistor is electrically coupled to the predetermined level-shift voltage.