Electrooptical apparatus and driving method therefor, liquid crystal display apparatus and driving method therefor, electrooptical apparatus and driving circuit therefor, and electronic equipment

• US 20020175887A1
• Filed: 07/09/2002
• Published: 11/28/2002
• Est. Priority Date: 02/09/1998
• Status: Active Grant

• Current Assignee: 138 East LCD Advancements Limited (Vector Capital Corporation)
• Original Assignee: Suguru Yamazaki
• Inventors: Yamazaki, Suguru
• Granted Patent: US 6,900,788 B2
• Time in Patent Office: Days
• US Class Current: 345/87
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/028 Generation of voltages supplied to electrode drivers in a matrix display other than LCD
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/2092 Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto suitable for both CRT and flat panel G09G5/003; specific for a CRT G09G1/165
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: G09G 3/3622 using a passive matrix G09G3/3674 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3644 with the matrix divided into sections
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3666 with the matrix divided into sections
• CPC Class Codes: G09G 3/367 with a nonlinear element in series with the liquid crystal cell, e.g. a diode, or M.I.M. element
• CPC Class Codes: G09G 3/3681 suitable for passive matrices only
• CPC Class Codes: G09G 3/3692 suitable for passive matrices only
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

In an electrooptical apparatus having a function allowing part of a display screen to be in a display state and allowing the other to be in a non-display state, for a non-display region, application voltages for scanning electrodes are fixed at non-selection voltages, and application voltages for signal electrodes are fixed at voltages similar to the case of a full-screen ON-display or a full-screen OFF-display at least in a predetermined period. Therefore, power consumption in the partial display state can be reduced.

Claims

1. A driving method for an electrooptical apparatus, in which a plurality of scanning electrodes and a plurality of signal electrodes are arranged to cross with each other and comprises a function partially causing a display screen to be a display region;

the driving method comprising;

applying a selection voltage applied in a selection period and non-selection voltage in a non-selection period to the scanning electrodes in the foregoing display region; and

setting the display screen to be in the partial display state, by fixing voltages applying to all the scanning electrodes in said display region and voltages applying to all the signal electrodesat least in a predetermined period, in a period other than the selection period.

2. A driving method for an electrooptical apparatus according to claim 1, wherein the voltages applied to the scanning electrodes in the period when the voltages applied to all the scanning electrodes are fixed are to be said non-selection voltages.

3. A driving method for an electrooptical apparatus according to claim 2, wherein said non-selection voltages are one level.

4. A driving method for an electrooptical apparatus according to any one of claims 1 to 3, wherein a forming circuit for driving voltages to be applied to said scanning electrodes and said signal electrodes stops its operation in the period when the individual application voltages for all the scanning electrodes and all the signal electrodes are fixed.

5. A driving method for an electrooptical apparatus according to claim 4, wherein said driving-voltage forming circuit comprises a charge-pump circuit that switches among a plurality of capacitor connections according to clocks to generate boosted voltages and dropped voltages, and operation of said charge-pump circuit is stopped in the period when the individual application voltages for all the scanning electrodes and all the signal electrodes are fixed.

6. A driving method for an electrooptical apparatus according to any one of claims 1 to 5, wherein a first display mode causing the full portion of said display screen to be in a display state and a second display mode causing one partial region of the display screen to be in a display state and the other to be a non-display region, and the length of the period when the selection voltages are applied to the individual scanning electrodes in said display region is not changed for said first display mode and said second display mode.

7. A driving method for an electrooptical apparatus according to claim 6, wherein the potentials to be applied to said signal electrodes in the period other than the selection period for the scanning electrodes in said display region are set so that effective voltages to be applied to a liquid crystal for pixels in said display region in the display state are the same in said first display mode and said second display mode.

8. A driving method for an electrooptical apparatus according to claim 7, wherein the potentials to be applied to said signal electrodes in the period other than the selection period for the scanning electrodes in said display region are set so as to be the same as the application voltages for said signal electrodes in the case of an ON-display or an OFF-display in said first display mode.

9. A driving method for an electrooptical apparatus according to claim 8, wherein it is driven so that said plurality of scanning electrodes are simultaneously selected in the unit of a predetermined number and are sequentially selected on the basis of a predetermined number of units, and the application voltages for said signal electrodes in the case of the ON-display or the OFF-display in said second display mode are set so as to be the same as the application voltages for said signal electrodes in the case of full-screen ON-display or full-screen OFF-display in said first display mode.

10. A driving method for an electrooptical apparatus according to any one of claims 1 to 9, wherein the potentials to be applied to said signal electrodes in the period other than the selection period for the scanning electrodes in said display region are set by alternately switching every said predetermined period for one-screen scanning, between the application potential when the ON-display is performed and the application potential when the OFF-display is performed in the full screen display state.

11. A driving method for an electrooptical apparatus according to any one of claims 6 to 10, wherein in the period other than the selection period for the scanning electrodes in said display region in said second display mode, the polarity of the voltage difference between said scanning electrodes and said signal electrodes is inverted in every frame.

13. A driving method for an electrooptical apparatus according to claim 12, wherein the application voltages for said signal electrodes are alternately switched between a potential when an ON-display is performed and a potential when an OFF-display is performed in the full-screen display state, every period which is at least longer than the same-polarity driving period in the polarity inversion driving state and the full-screen display state.

14. A driving method for an electrooptical apparatus is characterized in that the electrooptical apparatus stated in any one of claims 1 to 13 is a simple-matrix liquid crystal display apparatus.

15. A driving method for an electrooptical apparatus is characterized in that the electrooptical apparatus stated in any one of claims 1 to 13 is an active-matrix liquid crystal display apparatus.

16. An electrooptical apparatus characterized to be driven by the driving method stated in any one of claims 1 to 15.

18. An electrooptical apparatus according to claim 17 is characterized to be a simple-matrix liquid crystal display apparatus.

19. An electrooptical apparatus according to claim 17 is characterized to be an active-matrix liquid crystal display apparatus.

33. An electronic equipment utilizing any one of the electrooptical apparatus and the liquid crystal display apparatus according to any one of claims 16 to 19, 23 to 26, and 32 as a display apparatus.

12. A driving method for an electrooptical apparatus, in which a plurality of scanning electrodes and a plurality of signal electrodes are arranged to cross with each other and comprises a function partially causing a display screen to be a display region, the driving method comprising:

applying selection voltages in a selection period and non-selection voltages in a non-selection period to the scanning electrodes in said display region; and

setting the display screen to be in the partial display state, by applying not the selection voltages but said non-selection voltages to the scanning electrodes in a region other than the display region of said display screen and fixing the application voltage for all the signal electrodes at least in a period longer than a same-polarity driving period in a polarity-inversion driving state and a full-screen display state.

17. An electrooptical apparatus including a plurality of scanning electrodes and a plurality of signal electrodes which are arranged to cross with each other and a function partially causing a display screen to be a display region, comprising:

a scanning-electrode driving circuit for applying selection voltages to the plurality of scanning electrodes in a selection period and applying non-selection voltages to the plurality of scanning electrodes in a non-selection period;

a signal-electrode driving circuit for applying signal voltages according to display data to the plurality of signal electrodes;

setting means for setting positional information regarding a partial display region in the display screen; and

control means for outputting a partial display control signal that controls said scanning-electrode driving circuit and said signal-electrode driving circuit based on the positional information set by the setting means;

wherein said scanning-electrode driving circuit and said signal-electrode driving circuit driving said scanning electrodes and said signal electrodes according to said partial display control signal, so that said scanning electrodes and said signal electrodes in the display region in the display screen are driven so as to cause display according to the display data and the non-selection voltages are applied continuously to said scanning electrodes in the non-selection region in the display screen;

whereby a non-display state is caused.

20. A driving circuit for an electrooptical apparatus, in which a plurality of scanning electrodes and a plurality of signal electrodes are arranged to cross with each other and comprises a function partially causing a display screen to be a display region, comprising:

first driving means applying voltages to said plurality of scanning electrodes; and

second driving means comprising a storing circuit to store display data and applying voltages selected according to the display data read from said storing circuit to said plurality of signal electrodes, said first driving means having a function that applies selection voltages in a selection period and applies non-selection voltages in a non-selection period to the scanning electrodes in said display region, and applies only said non-selection voltages to the scanning electrodes in other region of said display screen, and said second driving means having a function that reads the display data from said storing circuit in a period corresponding to the selection period for the scanning electrodes in said display region and fixes address for reading the display data from said storing circuit in other periods.

21. A driving circuit for an electrooptical apparatus according to claim 20, wherein, a shift register in said first driving means stops its shift operations in a period other than the selection period.

23. An electrooptical apparatus characterized by comprising the driving circuit stated in any one of claims 20 to 22 and scanning electrodes and signal electrodes to be driven by said driving circuit.

26. An electrooptical apparatus according to any one of claims 23 to 25, comprising:

a driving-voltage forming circuit for forming application voltages for said scanning electrodes or said signal electrodes to supply them to said driving means, said driving-voltage forming circuit including a contrast adjustment circuit for adjusting said application voltage, the operations of said contrast adjustment circuit stopping in a period other than the period of selection of the scanning electrodes in said display region.

22. A driving circuit for an electrooptical apparatus, in which a plurality of scanning electrodes and a plurality of signal electrodes are arranged to cross with each other and comprises a function partially causing a display screen to be a display region, comprising:

a scanning-electrode driving circuit for applying selection voltages sequentially to the plurality of scanning electrodes according to shift operations by a shift register, said scanning-electrode driving circuit applying selection voltages in a selection period to the scanning electrodes in the display region of said display screen according to shift operations by said shift register and applying only said non-selection voltages to the scanning electrodes in other region of said display screen by stopping the shift operations by said shift register on a way when partially causing the display screen to be to the display region, and said scanning-electrode driving circuit comprising an initial setting means to reset said shift register to an initial state when changing a state in which the display screen is caused to be in the partial display state to in a full-screen state.

25. An electrooptical apparatus according to claim 24, wherein said second driving means alternately changes, in a period other than the selection period for scanning electrodes in the display region, the application voltages for said signal electrodes between a potential when an ON-display is performed and a potential when an OFF-display is performed in a full-screen display state, every of period which is at least longer than a same-polarity driving period in a polarity inversion driving state and the full-screen display state.

28. A driving method for a liquid crystal display apparatus according to claim 27, wherein said liquid crystal display panel is a simple-matrix liquid crystal panel in which only non-selection voltages are applied to scanning electrodes in said non-display region in said partial display state.

30. A driving method for a liquid crystal display apparatus according to claim 27, said liquid crystal display panel is an active-matrix type liquid crystal panel, the voltages equal to or lower than the OFF-voltage are applied to the liquid crystal for pixels in said non-display region at least in the first frame changing to said partial display state, and only non-selection voltages are applied to scanning electrodes in said non-display region in and from the following frame.

24. An electrooptical apparatus in which a plurality of scanning electrodes and a plurality of signal electrodes are arranged to cross with each other and comprises a function partially causing a display screen to be a display regions, comprising:

first driving means applying voltages to said plurality of scanning electrodes; and

second driving means comprising a storing circuit to store display data and applying voltages selected according to the display data read from said storing circuit to said plurality of signal electrodes, said first driving means having a function that applies selection voltages in a selection period and applies non-selection voltages in a non-selection period to the scanning electrodes in said display region of the display screen and applies only said non-selection voltages to the scanning electrodes in other region of said display screen, and said second driving means having a function that applies voltages to the plurality of signal electrodes in a selection period of the scanning electrodes of the display region on the basis of display data read from the storing circuit and applies voltages to the plurality of signal electrodes in the other period on the basis of the same display data.

27. A driving method for a liquid crystal display apparatus which is a reflective type or a transflective type allowing a partial display state by enabling a partial region in a full screen of a liquid crystal display panel to be turned to a display state and the other to be turned a non-display state, characterized in that said liquid crystal display panel is a normally-white type and effective voltages equal to or lower than the OFF-voltage are applied to a liquid crystal in said non-display region in said partial display state.

29. A driving method for a liquid crystal display apparatus according to any one of claims 27 and 28, wherein said liquid crystal display panel is a simple-matrix liquid crystal panel in which only voltages turning to OFF-displays are applied to signal electrodes in said non-display region in said partial display state.

31. A driving method for a liquid crystal display apparatus according to any one of claims 27 and 30, wherein said liquid crystal display panel is an active-matrix type liquid crystal display panel, the voltages equal to or lower than the OFF-voltage are applied to the liquid crystal for pixels in said non-display region at least in the first frame changing to said partial display state, and only voltages equal to or lower than the OFF-voltage are applied to said signal electrodes in an access period for said non-display region in and from the following frame.

32. A liquid crystal display apparatus characterized to be driven by the driving method stated in any one of claims 27 to 31.