Electro-optical device and method for driving the same, liquid crystal device and method for driving the same, circuit for driving electro-optical device, and electronic device

• US 6,522,319 B1
• Filed: 10/07/1999
• Issued: 02/18/2003
• Est. Priority Date: 02/09/1998
• Status: Expired due to Term

• Current Assignee: 138 East LCD Advancements Limited (Vector Capital Corporation)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Yamazaki, Suguru
• Primary Examiner(s): Mengistu, Amare
• Application Number:
  US09/402,625
• Time in Patent Office: 1,230 Days
• Field of Search: 345/100, 345/98, 345/103, 345/94
• US Class Current: 345/103
• 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. The 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 a partial display state occurs in which a display screen is partially displayed in a display region, the driving method comprising:

applying a selection voltage to one scanning electrode in the display region, for a first period used to select the one scanning electrode in a frame period;

applying a non-selection voltage to the one scanning electrode in a second period used to select scanning electrodes other than the one scanning electrodes in the display region in the frame period;

applying voltages similar to the non-selection voltage to the plurality of scanning electrodes in the screen for a third period other than the first period and the second period in the frame period, respectively, and

applying voltages similar to each other to the plurality of signal electrodes in the screen for a predetermined period equal to or less than the third period in a polarity-inversion driving state and a full-screen display state.

2. The driving method for an electrooptical apparatus according to claim 1, the application voltages for the signal electrodes being alternately switched between a potential when an ON-display is performed and a potential when an OFF-display is performed in the fall-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.

3. An electrooptical apparatus, comprising:

a plurality of scanning electrodes and a plurality of signal electrodes which are arranged to cross with each other, a partial display state occurring when a display screen is partially displayed as a display region;

a scanning-electrode driving circuit that applies a selection voltage to one scanning electrode in the display region, for a first period used to select the one scanning electrode in a frame period and applies a non-selection voltage to the one scanning electrode in a second period used to select scanning electrodes, other than the one scanning electrode in the display region in the frame period and applies voltages similar to the non-selection voltage to the plurality of scanning electrodes in the display screen for a third period other than the first period and the second period in the frame period respectively;

a signal-electrode driving circuit that applies voltages similar to each other to the plurality of signal electrodes in the display screen for a predetermined period equal to or less than the third period; and

a control circuit that outputs a partial display control signal that controls the scanning-electrode driving circuit and the signal-electrode driving circuit, the scanning-electrode driving circuit and the signal-electrode driving circuit driving the scanning electrodes and the signal electrodes according to the partial display control signal, so that the scanning electrodes and the 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 the scanning electrodes in the non-selection region in the display screen, thus, causing a non-display state.

4. The electrooptical apparatus according to claim 3, the electrooptical apparatus being a passive-matrix liquid crystal display apparatus.

5. The electrooptical apparatus according to claim 3 the electrooptical apparatus being an active-matrix liquid crystal display apparatus.

6. Electronic equipment comprising:

the electrooptical apparatus of claim 3.

7. 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 a partial display state occurs in which a display screen is partially displayed as a display region, comprising:

a first driving circuit that applies voltages to the plurality of scanning electrodes; and

a second driving circuit comprising;

a storing circuit that stores display data, the second driving circuit applying voltages selected according to the display data read from the storing circuit to the plurality of signal electrodes, the first driving circuit applies, a selection voltage to one scanning electrode in the display region, for a first period used to select the one scanning electrode in a frame period and applies a non-selection voltage to the one scanning electrode in a second period used to select scanning electrodes, other than the one scanning electrode in the display region in the frame period and applies voltages similar to the non-selection voltage to the plurality of scanning electrodes in the display screen for a third period other than the first period and the second period in the frame period respectively and the second driving circuit reading the display data from the storing circuit in a period corresponding to the selection period for the scanning electrodes in the display region and fixing an address for reading the display data from the storing circuit in other periods.

8. The driving circuit for an electrooptical apparatus according to claim 7, a shift register in the first driving circuit, the shift register stopping shift operations in a period other than the selection period.

9. An electrooptical apparatus, comprising:

the driving circuit of claim 7; and

scanning electrodes and signal electrodes to be driven by the driving circuit.

10. The electrooptical apparatus according to claim 9, further comprising:

a driving-voltage forming circuit that forms application voltages for the scanning electrodes or the signal electrodes to supply application voltages to the first and second driving circuits, the driving-voltage forming circuit including a contrast adjustment circuit for adjusting the application voltage, the operations of the contrast adjustment circuit stopping in a period other than the period of selection of the scanning electrodes in the display region.

11. 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 a partial display state occurs in which a display screen is partially displayed as a display region, comprising:

a scanning-electrode driving circuit that applies selection voltages sequentially to the plurality of scanning electrodes according to shift operations by a shift register, the scanning-electrode driving circuit applies a selection voltage to one scanning electrode in the display region of the display screen according to shift operations by the shift register, for a first period used to select the one scanning electrode in a frame period and applies a non-selection voltage to the one scanning electrode in a second period used to select scanning electrodes, other than the one scanning electrodes in the display region in the frame period and applies voltages similar to the non-selection voltage to the plurality of scanning electrodes in the display screen for a third period other than the first period and the second period in the frame period respectively, wherein the scanning-electrode driving circuit applies voltage similar to non-selection voltage by stopping shift operation by the shift register,

and the scanning-electrode driving circuit comprising;

an initial setting circuit that resets the shift register to an initial state when the display screen changes from a partial-screen state to a full-screen display state.

12. An electrooptical apparatus in which a plurality of scanning electrodes and a plurality of signal electrodes are arranged to cross with each other, and a partial display state occurs in which a display screen is partially displayed as a display region, comprising:

a first driving circuit that applies voltages to the plurality of scanning electrodes; and

a second driving circuit comprising;

a storing circuit that stores display data, and the second driving circuit applying voltages selected according to the display data read from the storing circuit to the plurality of signal electrodes, the first driving circuit applies a selection voltage to one scanning electrode in the display region, for a first period used to select the one scanning electrode in a frame period and applies a non-selection voltage to the one scanning electrode in a second period used to select scanning electrodes, other than the one scanning electrodes in the display region in the frame period and applies voltages similar to the non-selection voltage to the plurality of scanning electrodes in the display screen for a third period other than the first period and the second period in the frame period respectively, and the second driving circuit applying 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 applying voltages to the plurality of signal electrodes in the other period on the basis of the same display data.

13. The electrooptical apparatus according to claim 12, the second driving circuit alternately changing, in a period other than the selection period for scanning electrodes in the display region, the application voltages for the 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.

14. A method for displaying for a frame period in a display region that is a partial region of a screen in a display apparatus, the screen including a plurality of electrooptical elements each disposed between a plurality of scanning lines and a plurality of signal lines, the method comprising:

applying a selection voltage to one scanning line in the display region, for a first period used to select the one scanning line in a frame period;

applying a non-selection voltage to the one scanning line in a second period used to select scanning lines other than the one scanning line in the display region in the frame period;

applying voltages similar to the non-selection voltage to the plurality of scanning lines in the screen for a third period other than the first period and the second period in the frame period, respectively, and

applying voltages similar to each other to the plurality of signal lines in the screen for a predetermined period equal to or less than the third period.

15. The display method for a display apparatus according to claim 14, the voltages being applied to the scanning lines in the period when the voltages applied to all the scanning lines are fixed are to be the non-selection voltages.

16. The display method for a display apparatus according to claim 15, the non-selection voltages being one level.

17. The display method for a display apparatus according to claim 14, a driving-voltage forming circuit for forming driving voltages to be applied to the scanning lines and the signal lines, stopping the driving-voltage forming circuit operation in the period when individual application voltages for all the scanning lines and all the signal lines are fixed.

18. The display method for a display apparatus according to claim 17, the driving-voltage forming circuit comprising 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 the charge-pump circuit being stopped in the period when individual application voltages for all the scanning lines and all the signal lines are fixed.

19. The display method for a display apparatus according to claim 14, a first display mode causing the full portion of the 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 being applied to individual scanning lines in the display region not changing for the first display mode and the second display mode.

20. The display method for a display apparatus according to claim 19, the potentials to be applied to the signal lines in a period other than a selection period for the scanning lines in the display region being set so that effective voltages to be applied to a liquid crystal for pixels in the display region in the display state are the same in the first display mode and the second display mode.

21. The display method for a display apparatus according to claim 20, the potentials to be applied to the signal lines in the period other than the selection period for the scanning lines in the display region being set so as to be the same as the application voltages for the signal lines in the case of an ON-display or an OFF-display in the first display mode.

22. The display method for a display apparatus according to claim 21, the plurality of scanning lines being simultaneously selected in a unit of the predetermined number and are sequentially selected on the basis of the predetermined number of units, and the application voltages for the signal lines in the case of the ON-display or the OFF-display in the second display mode being set so as to be the same as the application voltages for the signal lines in the case of full-screen ON-display or full-screen OFF-display in the first display mode.

23. The display method for a display apparatus according to claim 19, the polarity of the voltage difference between the scanning lines and the signal lines being inverted in every frame in the period other than the selection period for the scanning lines in the display region in the second display mode.

24. The display method for a display apparatus according to claim 14, the potentials to be applied to the signal lines in a period other than a selection period for the scanning lines in the display region being set by alternately switching every 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.

25. The display method for a display apparatus according to claim 14, the display apparatus being a passive-matrix liquid crystal display apparatus.

26. The display method for a display apparatus according to claim 14, the display apparatus being an active-matrix liquid crystal display apparatus.

27. A display apparatus driven by the display method as claimed in claim 14.

28. The method as set forth in claim 14, wherein the display apparatus is an active-matrix type, the method further comprising:

in a transition from displaying in the whole region of the screen to displaying in the partial region thereof, applying the selection voltage to a scanning line for one electrooptical element of the plurality of electrooptical elements in a region that should be a non-display region in the screen; and

applying a non-selection voltage to a signal line for the one electrooptical element.

29. A driving circuit for displaying for a frame period in a display region that is a partial region of a screen in a display apparatus, the screen including a plurality of electrooptical elements each disposed between a plurality of scanning lines and a plurality of signals lines, the driving circuit comprising:

a scanning line driving device that applies a selection voltage to one scanning line in the display region, for a first period used to select the one scanning line in a frame period, and applies a non-selection voltage to the one scanning line in a second period used to select scanning lines other than the one scanning line in the display region in the frame period, and

the scanning line driving device further applies voltages similar to the non-selection voltage to the plurality of scanning lines in the screen for a third period other than the first period and the second period in the frame period, respectively, and applies voltages similar to each other to the plurality of signal lines in the screen for a predetermined period equal to or less than the third period.

30. An electrooptical apparatus for displaying for a frame period in a display region that is a partial region of a screen in a display apparatus, the electrooptical apparatus comprising:

a scanning line driving device that applies a selection voltage to one scanning line in the display region, for a first period used to select the one scanning line in a frame period, and applies a non-selection voltage to the one scanning line in a second period used to select scanning lines other than the one scanning line in the display region in the frame period, and

the scanning line driving device further applies voltages similar to the non-selection voltage to the plurality of scanning lines in the screen for a third period other than the first period and the second period in the frame period, respectively, and applies voltages similar to each other to the plurality of signal lines in the screen for a predetermined period equal to or less than the third period.