Display-driving device and display-driving method performing gradation control based on a temporal modulation system

Abstract

One selection period S and display cycles Td of a number corresponding to a maximum gradation level are allotted in one field, and the display cycle Td is composed of an unselection period U and a reset period R to perform the following control. A row electrode-driving circuit is used to output a selection pulse Ps during the selection period S, output an unselection signal Su during the unselection period U in the display cycle Td, and output a reset pulse Pr during the reset period R. A column electrode-driving circuit is used to output an ON signal during a light emission maintenance period, and output an OFF signal at least at an end timing of the light emission maintenance period, of the period other than the light emission maintenance period. Accordingly, it is possible to effectively reduce the electric power consumption, and it is possible to achieve the high brightness.

1. A display-driving device for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display-driving device comprising:
 a first driving circuit for selecting said picture elements at least in one row unit, a second driving circuit for outputting display information composed of an ON signal and an OFF signal to a selected row, and a signal control circuit for controlling said first and second driving circuits, wherein: 
 a display period for one image is defined as one field, and in order to perform gradation control based on a temporal modulation system, said signal control circuit determines, in said one field, a light emission start timing and a contiguous light emission maintenance period having a variable length, independent of a selection/unselection state of a predetermined picture element, depending on a gradation level of said predetermined picture element, wherein said contiguous light emission maintenance period is provided by a memory function of said predetermined picture element.  
 
 
     
     
       2. The display-driving device according to  claim 1 , wherein:
 one selection period and display cycles of a number corresponding to a maximum gradation level are allotted in said one field;  
 each of said display cycles is composed of an unselection period and a reset period; and  
 said signal control circuit is operated such that said predetermined picture element is in a light emission state when said ON signal indicating light emission is inputted during said selection period, or said predetermined picture element is in a light off state when said OFF signal indicating light off is inputted during said reset period in said display cycle.  
 
     
     
       3. The display-driving device according to  claim 2 , wherein:
 signal levels are determined for said unselection period and said reset period so that said light emission state of said predetermined picture element is maintained during said light emission maintenance period; and  
 signal levels are determined for said selection period and said unselection period so that said light off state of said predetermined picture element is maintained during any period other than said light emission maintenance period.  
 
     
     
       4. The display-driving device according to  claim 1 , wherein:
 display cycles of a number corresponding to a maximum gradation level and one reset period are allotted in said one field;  
 each of said display cycles is composed of a selection period and an unselection period; and  
 said signal control circuit is operated such that said predetermined picture element is in a light emission state when said ON signal indicating light emission is inputted during said selection period, or said predetermined picture element is in a light off state during said reset period.  
 
     
     
       5. The display-driving device according to  claim 4 , wherein signal levels are determined for said selection period and said unselection period so that said light emission state of said predetermined picture element is maintained during said light emission maintenance period. 
     
     
       6. The display-driving device according to  claim 1 , wherein:
 an odd/even-adjusting cycle including a unit unselection period having a predetermined length between two selection periods, and display cycles of a number corresponding to a maximum gradation level are allotted in said one field; and  
 each of said display cycles is provided with a redundant unselection period having a length which is twice said predetermined length and a reset period.  
 
     
     
       7. The display-driving device according to  claim 6 , wherein:
 when said gradation level of said predetermined picture element is odd, said light emission start timing is set to be substantially in synchronization with said  a head selection period of said odd/even-adjusting cycle; while  
 when said gradation level of said predetermined picture element is even, said light emission start timing is set to be substantially in synchronization with said  a rear end selection period of said odd/even-adjusting cycle.  
 
     
     
       8. The display-driving device according to  claim 1 , wherein:
 display cycles of a number corresponding to a maximum gradation level, and an odd/even-adjusting cycle including a unit unselection period having a predetermined length between two reset periods are allotted in said one field; and  
 each of said display cycles is provided with a selection period and a redundant unselection period having a length which is twice said predetermined length.  
 
     
     
       9. The display-driving device according to  claim 8 , wherein:
 when said gradation level of said predetermined picture element is odd, an end timing for said light emission maintenance period is set to be substantially in synchronization with said  a terminal end reset period of said odd/even-adjusting cycle; while  
 when said gradation level of said predetermined picture element is even, said end timing for said light emission maintenance period is set to be substantially in synchronization with said  a head reset period of said odd/even-adjusting cycle.  
 
     
     
       10. The display-driving device according to  claim 1 , wherein:
 at least one unit display cycle including a unit unselection period having a predetermined length, and at least one redundant display cycle are allotted in said one field; and  
 said redundant display cycle is provided with a redundant unselection period having a length which is n-times said predetermined length provided that n is an integer of not less than 2.  
 
     
     
       11. The display-driving device according to  claim 10 , wherein the following expressions are satisfied:
   Z=(quotient of X/n)−1  
   Y=X−Z×n  
   total number of subfields (Y+Z)=(X/n−1)+n  
 
       provided that a maximum gradation level is X, a number of unit display cycles is Y, and a number of redundant display cycles is Z. 
     
     
       12. The display-driving device according to  claim 11 , wherein “a” individuals of selection periods are allotted to said respective display cycles from a head of said one field, and “b” individuals of reset periods are allotted to said respective display cycles from a rear end of said one field, and wherein following expression is satisfied:
   a+b=Y+Z+1.  
 
     
     
       13. The display-driving device according to  claim 10 , wherein said unit display cycle and said redundant display cycle are allotted by using a combination which corresponds to a minimum total number of subfields of total numbers of subfields corresponding to a maximum gradation level obtained by arbitrarily combining said unit display cycle and said redundant display cycle. 
     
     
       14. The display-driving device according to  claim 10 , wherein:
 said one field includes therein a first subfield block composed of at least one redundant display cycle and a second subfield block composed of at least one unit display cycle; and  
 a forcible reset period is provided between said first and second subfield blocks.  
 
     
     
       15. The display-driving device according to  claim 14 , wherein said second subfield block is composed of at least one redundant display cycle and at least one unit display cycle. 
     
     
       16. The display-driving device according to  claim 1 , wherein said display comprises an optical waveguide plate for introducing light thereinto, and said driving section provided opposingly to one plate surface of said optical waveguide plate and including a number of actuator elements arranged corresponding to said large number of picture elements, for displaying, on said optical waveguide plate, said picture image corresponding to said image signal by controlling leakage light at a predetermined portion of said optical waveguide plate by controlling displacement action of each of said actuator elements in a direction to make contact or separation with respect to said optical waveguide plate in accordance with an attribute of said image signal to be inputted. 
     
     
       17. The display-driving device according to  claim 16 , wherein:
 said actuator element comprises a shape-retaining layer, an operating section having at least a pair of electrodes formed on said shape-retaining layer, a vibrating section for supporting said operation section, and a fixed section for supporting said vibrating section in a vibrating manner; and  
 said display comprises a displacement-transmitting section for transmitting said displacement action of said actuator element to said optical waveguide plate, said displacement action being generated by voltage application to said pair of electrodes.  
 
     
     
       18. The display-driving device according to  claim 16 , wherein:
 said driving section is formed with switching elements corresponding to said actuator elements respectively; and  
 said displacement action of said actuator element is controlled by means of ON/OFF control effected by said switching element.  
 
     
     
       19. The display-driving device according to  claim 18 , wherein said switching element is composed of a varistor. 
     
     
       20. The display-driving device according to  claim 17 , wherein said shape-retaining layer is a piezoelectric/electrostrictive layer. 
     
     
       21. The display-driving device according to  claim 17 , wherein said shape-retaining layer is an anti-ferroelectric layer. 
     
     
       22. A display-driving method for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal; said display-driving method comprising the step of:
 selecting said picture elements at least in one row unit;  
 outputting display information composed of an ON signal and an OFF signal to a selected row; and  
 performing gradation control based on a temporal modulation system, wherein: 
 a display period for one image is defined as one field, a light emission start timing and a contiguous light emission maintenance period having a variable length, independent of a selection/unselection state of a predetermined picture element, are determined in said one field depending on a gradation level of said predetermined picture element, and  
   wherein said contiguous light emission maintenance period is provided by a memory function of said predetermined picture element.    
 
 
     
     
       23. The display-driving method according to  claim 22 , wherein:
 one selection period and display cycles of a number corresponding to a maximum gradation level are allotted in said one field;  
 each of said display cycles is composed of an unselection period and a reset period; and  
 said predetermined picture element is in a light emission state when said ON signal indicating light emission is inputted during said selection period; or  
 said predetermined picture element is in a light off state when said OFF signal indicating light off is inputted during said reset period in said display cycle.  
 
     
     
       24. The display-driving method according to  claim 23 , wherein:
 signal levels are determined for said unselected period and said reset period so that said light emission state of said predetermined picture element is maintained during said light emission maintenance period; and  
 signal levels are determined for said selection period and said unselection period so that said light off state of said predetermined picture element is maintained during any period other than said light emission maintenance period.  
 
     
     
       25. The display-driving method according to  claim 22 , wherein:
 display cycles of a number corresponding to a maximum gradation level and one reset period are allotted in said one field;  
 each of said display cycles is composed of a selection period and an unselection period; and  
 said predetermined picture element is in a light emission state when said ON signal indicating light emission is inputted during said selection period; or  
 said predetermined picture element is in a light off state during said reset period.  
 
     
     
       26. The display-driving method according to  claim 25 , wherein signal levels are determined for said selection period and said unselection period so that said light emission state of said predetermined picture element is maintained during said light emission maintenance period. 
     
     
       27. The display-driving method according to  claim 22 , wherein:
 an odd/even-adjusting cycle including a unit unselection period having a predetermined length between two selection periods, and display cycles of a number corresponding to a maximum gradation level are allotted in said one field; and  
 each of said display cycles is provided with a redundant unselection period having a length which is twice said predetermined length and a reset period.  
 
     
     
       28. The display-driving method according to  claim 27 , wherein:
 when said gradation level of said predetermined picture element is odd, said light emission start timing is set to be substantially in synchronization with said  a head selection period of said odd/even-adjusting cycle; while  
 when said gradation level of said predetermined picture element is even, said light emission start timing is set to be substantially in synchronization with said  a rear end selection period of said odd/even-adjusting cycle.  
 
     
     
       29. The display-driving method according to  claim 22 , wherein:
 display cycles of a number corresponding to a maximum gradation level, and an odd/even-adjusting cycle including a unit unselection period having a predetermined length between two reset periods are allotted in said one field; and  
 each of said display cycles is provided with a selection period and a redundant unselection period having a length which is twice said predetermined length.  
 
     
     
       30. The display-driving method according to  claim 29 , wherein:
 when said gradation level of said predetermined picture element is odd, an end timing for said light emission maintenance period is set to be substantially in synchronization with said  a terminal end reset period of said odd/even-adjusting cycle; while  
 when said gradation level of said predetermined picture element is even, said end timing for said light emission maintenance period is set to be substantially in synchronization with said  a head reset period of said odd/even-adjusting cycle.  
 
     
     
       31. The display-driving method according to  claim 22 , wherein:
 at least one unit display cycle including a unit unselection period having a predetermined length, and at least one redundant display cycle are allotted in said one field; and  
 said redundant display cycle is provided with a redundant unselection period having a length which is n-times said predetermined length provided that n is an integer of not less than 2.  
 
     
     
       32. The display-driving method according to  claim 31 , wherein the following expressions are satisfied:
   Z=(quotient of X/n)−1  
   Y=X−Z×n  
   total number of subfields (Y+Z)=(X/n−1)+n  
 
       provided that a maximum gradation level is X, a number of unit display cycles is Y, and a number of redundant display cycles is Z. 
     
     
       33. The display-driving method according to  claim 32 , wherein:
 “a” individuals of selection periods are allotted to said respective display cycles from a head of said one field, and “b” individuals of reset periods are allotted to said respective display cycles from a rear end of said one field, and wherein following expression is satisfied: 
   a+b=Y+Z+1.  
 
 
     
     
       34. The display-driving method according to  claim 31 , wherein said unit display cycle and said redundant display cycle are allotted by using a combination which corresponds to a minimum total number of subfields of total members of subfields corresponding to a maximum gradation level obtained by arbitrarily combining said unit display cycle and said redundant display cycle. 
     
     
       35. The display-driving method according to  claim 31 , wherein:
 said one field includes therein a first subfield block composed of at least one redundant display cycle and a second subfield block composed of at least one unit display cycle; and  
 a forcible reset period is provided between said first and second subfield blocks.  
 
     
     
       36. The display-driving method according to  claim 35 , wherein said second subfield block is composed of at least one redundant display cycle and at least one unit display cycle. 
     
     
       37. The display-driving method according to  claim 22 , wherein said gradation control is performed for said picture element by means of ON/OFF control effected by a switching element. 
     
     
       38. The display-driving method according to  claim 37 , wherein a varistor is used as said switching element. 
     
     
       39. A display-driving device for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display-driving device comprising:
 a first driving circuit for selecting said picture elements at least in one row unit, a second driving circuit for outputting display information composed of an ON signal and an OFF signal to a selected row, and a signal control circuit for controlling said first and second driving circuits, wherein: 
 a display period for one image is defined as one field, and in order to perform gradation control based on at least a temporal modulation system, said signal control circuit determines, in said one field, a light emission start timing and a light emission maintenance period having a variable length, independent of a selection/unselection state of a predetermined picture element, depending on a gradation level of said predetermined picture element;  
 at least one unit display cycle including a unit unselection period having a predetermined length and at least one redundant display cycle are allotted in said one field, said redundant display cycle being provided with a redundant unselection period having a length which is n-times said predetermined length provided that n is an integer of not less than 2; and  
 the following expressions are satisfied: 
   Z=(quotient of X/n)−1  
   Y=X−Z×n  
   total number of subfields (Y+Z)=(X/n−1)+n  
 
  provided that a maximum gradation level is X, a number of unit display cycles is Y, and a number of redundant display cycles is Z.  
 
 
     
     
       40. The display-driving device according to  claim 39 , wherein “a” individuals of selection periods are allotted to said respective display cycles from a head of said one field, and “b” individuals of reset periods are allotted to said respective display cycles from a rear end of said one field, and wherein following expression is satisfied:
   a+b=Y+Z+1.  
 
     
     
       41. A display-driving method for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal; said display-driving method comprising the step of:
 selecting said picture elements at least in one row unit;  
 outputting display information composed of an ON signal and an OFF signal to a selected row; and  
 performing gradation control based on at least a temporal modulation system, wherein: 
 a display period for one image is defined as one field, a light emission start timing and a light emission maintenance period having a variable length, independent of a selection/unselection state of a predetermined picture element, are determined in said one field depending on a gradation level of said predetermined picture element;  
 at least one unit display cycle including a unit unselection period having a predetermined length and at least one redundant display cycle are allotted in said one field, said redundant display cycle being provided with a redundant unselection period having a length which is n-times said predetermined length provided that n is an integer of not less than 2; and  
 the following expressions are satisfied: 
   Z=(quotient of X/n)−1  
   Y=X−Z×n  
   total number of subfields (Y+Z)=(X/n−1)+n  
 
  provided that a maximum gradation level is X, a number of unit display cycles is Y, and a number of redundant display cycles is Z.  
 
 
     
     
       42. The display-driving method according to  claim 41 , wherein:
 “a” individuals of selection periods are allotted to said respective display cycles from a head of said one field, and “b” individuals of reset periods are allotted to said respective display cycles from a rear end of said one field, and wherein the following expression is satisfied: 
   a+b=Y+Z+1.  
 
 
     
     
       43. A display- driving device for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display driving device comprising:      a first driving circuit for selecting picture elements at least in one row unit, a second driving circuit for outputting display information composed of an ON signal and an OFF signal to a selected row, and a signal control circuit for controlling said first and second driving circuits, wherein:      a display period for one image is defined as one field, and in order to perform gradation control based on a temporal modulation system, said signal control circuit turns a predetermined picture element ON only once in said one field and turns said picture element OFF only once in said one field, and the ON/OFF state of said picture element is maintained by a memory function of said picture element.       
     
     
       44. The display- driving device according to    claim 43    wherein:      a plurality of display cycles are allotted in said one field;        said picture element is turned ON only in a first display cycle in said one field; and        said picture element is turned OFF in one of said display cycles other than said first display cycle in said one field.     
     
     
       45. The display- driving device according to    claim 44   , wherein:      said display cycles other than said first display cycle have a row scanning period for performing row selection in order to input a control signal to turn said picture element OFF; and        the ON/OFF state of said picture element is maintained in an unselection period of the row which includes said picture element in said row scanning period.     
     
     
       46. The display- driving device according to    claim 43   , wherein:      a plurality of display cycles are allotted in said one field;        said picture element is turned OFF only in a last display cycle in said one field; and        said picture element is turned ON in one of said display cycles other than said last display cycle in said one field.     
     
     
       47. The display- driving device according to    claim 46   , wherein:      said display cycles other than said last display cycle have a row scanning period for performing row selection in order to input a control signal to turn said picture element ON; and        the ON/OFF state of said picture element is maintained in an unselection period of the row which includes said picture element in said row scanning period.     
     
     
       48. The display- driving device according to    claim 43   , wherein:      a plurality of display cycles are allotted in said one field; and        said picture element is turned ON in one of said display cycles and turned OFF in another of said display cycles.     
     
     
       49. The display- driving device according to    claim 48   , wherein:      said display cycles have a row scanning period for performing row selection in order to input a control signal to turn said picture element ON or OFF; and        the ON/OFF state of said picture element is maintained in an unselection period of the row which includes said picture element in said row scanning period.     
     
     
       50. A display- driving method for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display driving method comprising the steps of:      selecting picture elements at least in one row unit;        outputting display information composed of an ON signal and an OFF signal to a selected row; and        performing gradation control based on a temporal modulation system, wherein:      a display period for one image is defined as one field, and said signal control circuit turns a predetermined picture element ON only once in said one field and turns said picture element OFF only once in said one field, and the ON/OFF state of said picture element is maintained by a memory function of said picture element.       
     
     
       51. The display- driving method according to    claim 50   , wherein:      a plurality of display cycles are allotted in said one field;        said picture element is turned ON only in a first display cycle in said one field; and        said picture element is turned OFF in one of said display cycles other than said first display cycle in said one field.     
     
     
       52. The display- driving method according to    claim 51   , wherein:      said display cycles other than said first display cycle have a row scanning period for performing row selection in order to input a control signal to turn said picture element OFF; and        the ON/OFF state of said picture element is maintained in an unselection period of the row which includes said picture element in said row scanning period.     
     
     
       53. The display- driving device according to    claim 50   , wherein:      a plurality of display cycles are allotted in said one field;        said picture element is turned OFF only in a last display cycle in said one field; and        said picture element is turned ON in one of said display cycles other than said last display cycle in said one field.     
     
     
       54. The display- driving method according to    claim 53   , wherein:      said display cycles other than said last display cycle have a row scanning period for performing row selection in order to input a control signal to turn said picture element ON; and        the ON/OFF state of said picture element is maintained in an unselection period of the row which includes said picture element in said row scanning period.     
     
     
       55. The display- driving method according to    claim 50   , wherein:      a plurality of display cycles are allotted in said one field; and        said picture element is turned ON in one of said display cycles and turned OFF in another of said display cycles.     
     
     
       56. The display- driving method according to    claim 55   , wherein:      said display cycles have a row scanning period for performing row selection in order to input a control signal to turn said picture element ON or OFF; and        the ON/OFF state of said picture element is maintained in an unselection period of the row which includes said picture element in said row scanning period.     
     
     
       57. A display driving device for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display driving device comprising:
   a first driving circuit for selecting picture elements at least in one row unit, a second driving circuit for outputting display information composed of an ON signal and an OFF signal to a selected row, and a signal control circuit for controlling said first and second driving circuits, wherein:      a display period for one image is defined as one field and a first display cycle group and a second display cycle group are allotted in said one field, said first and second display cycle groups comprising one display cycle or at least two continuously allotted display cycles, wherein each of said first and second display cycle groups are arranged in a different period within said one field and said second display cycle group is arranged following said first display cycle group, and in order to perform gradation control based on a temporal modulation system, a predetermined picture element is turned ON in only one of said display cycles in said first display cycle group and the ON state of said picture element is maintained by a memory function of said picture element until said picture element is turned OFF in only one of said display cycles in said second display cycle group.       
     
     
       58. A display- driving device for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display driving device comprising:      a first driving circuit for selecting picture elements at least in one row unit, a second driving circuit for outputting display information composed of an ON signal and an OFF signal to a selected row, and a signal control circuit for controlling said first and second driving circuits, wherein:      a display period for one image is defined as one field and a first display cycle group and a second display cycle group are allotted in said one field, said first and second display cycle groups comprising one display cycle or at least two continuously allotted display cycles, wherein each of said first and second display cycle groups are arranged in a different period within said one field and said second display cycle group is arranged following said first display cycle group, and in order to perform gradation control based on a temporal modulation system, a predetermined picture element is turned ON in one of said display cycles in said first display cycle group and the ON state of said picture element is maintained by a memory function of said picture element until said picture element is turned OFF in one of said display cycles in said second display cycle group, wherein said display cycles at least in said second display cycle group have a row scanning period for performing row selection in order to input a control signal to turn said picture element OFF, and wherein said picture element emits light in the ON state until the end of said row scanning period.       
     
     
       59. A display driving method for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display driving method comprising the steps of:
   selecting picture elements at least in one row unit; and        outputting display information composed of an ON signal and an OFF signal to a selected row, wherein a display period for one image is defined as one field and a first display cycle group and a second display cycle group are allotted in said one field, said first and second display cycle groups comprising one display cycle or at least two continuously allotted display cycles, wherein each of said first and second display cycle groups are arranged in a different period within said one field and said second display cycle group is arranged following said first display cycle group, and in order to perform gradation control based on a temporal modulation system, a predetermined picture element is turned ON in only one of said display cycles in said first display cycle group and the ON state of said picture element is maintained by a memory function of said picture element until said picture element is turned OFF in only one of said display cycles in said second display cycle group.     
     
     
       60. A display- driving method for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display driving method comprising the steps of:      selecting picture elements at least in one row unit; and        outputting display information composed of an ON signal and an OFF signal to a selected row, wherein a display period for one image is defined as one field and a first display cycle group and a second display cycle group are allotted in said one field, said first and second display cycle groups comprising one display cycle or at least two continuously allotted display cycles, wherein each of said first and second display cycle groups are arranged in a different period within said one field and said second display cycle group is arranged following said first display cycle group, and in order to perform gradation control based on a temporal modulation system, a predetermined picture element is turned ON in one of said display cycles in said first display cycle group and the ON state of said picture element is maintained by a memory function of said picture element until said picture element is turned OFF in one of said display cycles in said second display cycle group, wherein said display cycles at least in said second display cycle group have a row scanning period for performing row selection in order to input a control signal to turn said picture element OFF, and wherein said picture element emits light in the ON state until the end of said row scanning period.     
     
     
       61. A display- driving device for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display driving device comprising:      a first driving circuit for selecting picture elements at least in one row unit, a second driving circuit for outputting display information composed of an ON signal and an OFF signal to a selected row, and a signal control circuit for controlling said first and second driving circuits, wherein:      a display period for one image is defined as one field and a first display cycle group and a second display cycle group are allotted in said one field, said first and second display cycle groups comprising one display cycle or at least two continuously allotted display cycles, wherein said second display cycle group is arranged following said first display cycle group, and in order to perform gradation control based on a temporal modulation system, a predetermined picture element is turned ON in one of said display cycles in said first display group and the ON state of said picture element is maintained by a memory function of said picture element until said picture element is turned OFF in one of said display cycles in said second display cycle group, wherein said display cycles at least in said second display cycle group have a row scanning period for performing row selection in order to input a control signal to turn said picture element OFF, and wherein said picture element emits light in the ON state until the end of said row scanning period.       
     
     
       62. A display- driving method for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display driving method comprising the steps of:      selecting picture elements at least in one row unit;        outputting display information composed of an ON signal and an OFF signal to a selected row, wherein a display period for one image is defined as one field and a first display cycle group and a second display cycle group are allotted in said one field, said first and second display cycle groups comprising one display cycle or at least two continuously allotted display cycles, wherein said second display cycle group is arranged following said first display cycle group, and in order to perform gradation control based on a temporal modulation system, said picture element is turned ON in one of said display cycles in said first display cycle group and the ON state of said picture element is maintained by a memory function of said picture element until said picture element is turned OFF in one of said display cycles in said second display cycle group, wherein said display cycles at least in said second display cycle group have a row scanning period for performing row selection in order to input a control signal to control whether to turn said picture element OFF, and wherein said picture element emits light in the ON state until the end of said row scanning period.     
     
     
       63. A display- driving device for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display - driving device comprising:      a first driving circuit for selecting said picture elements at least in one row unit, a second driving circuit for outputting display information composed of an ON signal and an OFF signal to a selected row, and a signal control circuit for controlling said first and second driving circuits, wherein:      a display period for one image is defined as one field, and in order to perform gradation control based on a temporal modulation system, said signal control circuit determines, in said one field, a contiguous light emission maintenance period having a variable length, independent of a selection/unselection state of a predetermined picture element, depending on a gradation level of said predetermined picture element.       
     
     
       64. A display- driving device for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display - driving device comprising:      a first driving circuit for selecting said picture elements at least in one row unit, a second driving circuit for outputting display information composed of an ON signal and an OFF signal to a selected row, and a signal control circuit for controlling said first and second driving circuits, wherein:      a display period for one image is defined as one field, and in order to perform gradation control based on a temporal modulation system, said signal control circuit determines, in said one field, a light emission start timing and a contiguous light emission maintenance period having a variable length, independent of a selection/unselection state of a predetermined picture element, depending on a gradation level of said predetermined picture element, wherein said light emission start timing is fixed in said one field.       
     
     
       65. A display- driving device for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display - driving device comprising:      a first driving circuit for selecting said picture elements at least in one row unit, a second driving circuit for outputting display information composed of an ON signal and an OFF signal to a selected row, and a signal control circuit for controlling said first and second driving circuits, wherein:      a display period for one image is defined as one field, and in order to perform gradation control based on a temporal modulation system, said signal control circuit determines, in said one field, a light emission start timing and a contiguous light emission maintenance period having a variable length, independent of a selection/unselection state of a predetermined picture element, depending on a gradation level of said predetermined picture element, wherein said light emission start timing is variable in said one field.       
     
     
       66. A display- driving device for a display comprising a driving section including a large number of picture elements arranged in a matrix form for displaying a picture image corresponding to a supplied image signal, said display - driving device comprising:      a first driving circuit for selecting said picture elements at least in one row unit, a second driving circuit for outputting display information composed of an ON signal and an OFF signal to a selected row, and a signal control circuit for controlling said first and second driving circuits, wherein:      a display period for one image is defined as one field, and in order to perform gradation control based on a temporal modulation system, said signal control circuit determines, in said one field, a light emission start timing and a contiguous ON state period having a variable length, indepnednet of a selection/unselection state of a predetermined picture element, depending on a gradation level of said predetermined picture element.