Image display device having memory property, driving control device and driving method to be used for same

• US 8,446,358 B2
• Filed: 04/16/2009
• Issued: 05/21/2013
• Est. Priority Date: 04/16/2008
• Status: Active Grant

• Current Assignee: NLT Technologies, Ltd. (Tianma Microelectronics Company Limited)
• Original Assignee: NLT Technologies, Ltd. (Tianma Microelectronics Company Limited)
• Inventors: Sakamoto, Michiaki
• Primary Examiner(s): BOLOTIN, DMITRIY
• Application Number:
  US12/425,020
• Publication Number:
  US 20090267969A1
• Time in Patent Office: 1,496 Days
• Field of Search: 345/107, 345/55, 345/84, 345/105, 345/108, 345/211, 345/214, 345690-693, 359/296
• US Class Current: 345/107
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 3/2081 with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• CPC Class Codes: G09G 3/344 based on particles moving in a fluid or in a gas, e.g. electrophoretic devices electrophoretic devices per se G02F1/167

Abstract

There is provided an image display device capable of obtaining a renewed screen giving normal feelings by simple LUT (Look Up Table) adjustment even at a time of displaying with multiple gray levels. A screen of the electronic paper section making up the display device is renewed by driving for a period of time corresponding to a plurality of frames according to input gray level data of a renewed screen. The renewed screen is displayed with a coarse gray level during a first displaying period in a renewing period corresponding to a plurality of frames at an output voltage specified by a high-order bit of its gray level data and, thereafter, is displayed with a fine gray level during a second displaying period in the renewing period at an output voltage specified by a low-order bit of its gray level data.

Claims

1. An image display device having a memory property comprising:

a display section comprising a plurality of display elements each having a memory property;

a driving unit to drive said display section at a specified output voltage; and

a control unit to control said driving unit;

wherein a screen of said display section is renewed by driving for a period of time corresponding to a plurality of frames according to input gray level data of a renewed screen;

wherein said control unit controls said driving unit to sequentially drive each display element with a coarse gray level at said specified output voltage specified by a high-order bit of gray level data of said renewed screen during a first displaying period in a renewing period corresponding to said plurality of frames and with a fine and minute gray level at said specified output voltage specified by a low-order bit of gray level data of said renewed screen during a second displaying period in said renewing period.

2. An image display device having a memory property comprising:

a display section comprising a plurality of display elements each having a memory property;

a driving unit to drive said display section at a specified output voltage; and

a control unit to control said driving unit;

wherein a screen of said display section is renewed by driving for a period of time corresponding to a plurality of frames according to input gray level data of a renewed screen;

wherein said control unit controls said driving unit to sequentially drive each display element with a coarse gray level at said specified output voltage specified, for every frame, by a high-order bit of gray level data of said renewed screen during a first displaying period in a renewing period corresponding to said plurality of frames and with a fine and minute gray level at said specified output voltage specified, for every frame, by a low-order bit of gray level data of said renewed screen during a second displaying period in said renewing period.

3. The image display device having the memory property according to claim 2, wherein said control unit makes a response speed of said display element during said second displaying period become slower compared with a response speed of said display element during said first displaying period by operating said driving unit at an output voltage being lower than an output voltage during said first displaying period.

4. The image display device having the memory property according to claim 2, wherein said control unit operates said driving unit during said second displaying period at a frame frequency being higher than a frame frequency during said first displaying period.

5. The image display device having the memory property according to claim 2, further comprising a look up table determined for every frame which is a table describing a group of specified conversion coefficients required for calculating driving data to determine an output voltage for said driving unit for every frame and said output voltage for every frame is determined by referring to said look up table.

6. The image display device having the memory property according to claim 2, further comprising a look up table determined for every frame which is a table describing a group of specified conversion coefficients required for calculating driving data to determine an output voltage for said driving unit for every frame based on gray level data of a previous screen and gray level data of a renewed screen, and configured to determine said specified output voltage for every frame by referring to said look up table.

7. The image display device having the memory property according to claim 2, wherein said displaying section comprises an electrophoretic display element having a memory property.

8. A driving method for driving an image display device having a memory property, the image display device having a display section comprising a plurality of display elements each having a memory property, a driving unit to drive said display section at a specified output voltage, and a control unit to control said driving unit and for renewing a screen of said display section by driving for a period of time corresponding to a plurality of frames according to input gray level data of a renewed screen, said driving method comprising:

dividing a renewing period corresponding to said plurality of frames into, at least, a first displaying period and a second displaying period;

controlling said driving unit to sequentially drive each display element with a coarse gray level at said specified output voltage specified by a high-order bit of gray level data of said renewed screen during said first displaying period and with a fine and minute gray level at said specified output voltage specified by a low-order bit of gray level data of said renewed screen during said second displaying period.

9. A driving method for driving an image display device having a memory property, the image display device having a display section comprising a plurality of display elements each having a memory property, a driving unit to drive said display section at a specified output voltage, and a control unit to control said driving unit and for renewing a screen of said display section by driving for a period of time corresponding to a plurality of frames according to input gray level data of a renewed screen, said driving method comprising:

dividing a renewing period corresponding to said plurality of frames into, at least, a first displaying period and a second displaying period;

controlling said driving unit to sequentially drive each display element with a coarse gray level at said specified output voltage specified, for every frame, by a high-order bit of gray level data of said renewed screen during said first displaying period and with a fine and minute gray level at said specified output voltage specified, for every frame, by a low-order bit of gray level data of said renewed screen during said second displaying period.

10. The driving method for driving an image display device having a memory property according to claim 9, making a response speed of said display element during said second displaying period become slower compared with a response speed of said display element during said first displaying period by operating said driving unit at an output voltage being lower than an output voltage during said first displaying period.

11. The driving method for driving an image display device having a memory property according to claim 9, operating said driving unit during said second displaying period at a frame frequency being higher than a frame frequency during said first displaying period.

12. The driving method for driving an image display device having a memory property according to claim 9, determining said specified output voltage for every frame by referring to a look up table determined for every frame, the look up table describing a group of specified conversion coefficients required for calculating driving data to determine an output voltage for said driving unit for every frame.

13. The driving method for driving an image display device having a memory property according to claim 9, determining said specified output voltage for every frame by referring to a look up table determined for every frame, the look up table describing a group of specified conversion coefficients required for calculating driving data to determine an output voltage for said driving unit for every frame based on gray level data of a previous screen and gray level data of a renewed screen.

14. The driving method for driving an image display device having a memory property according to claim 9, wherein said displaying section comprises an electrophoretic display element having a memory property.

15. A driving control device to be used for an image display device having a memory property comprising a display section comprising a plurality of display elements each having a memory property, a driving unit to drive said display section at a specified output voltage, and a control unit to control said driving unit, the driving control device which functions as said control unit, wherein, at time when a screen of said display section is renewed by driving for a period of time corresponding to a plurality of frames according to input gray level data of a renewed screen, said driving unit sequentially drives each display element with a coarse gray level at said specified output voltage specified by a high-order bit of gray level data of said renewed screen during a first displaying period in a renewing period corresponding to a plurality of frames and with a fine and minute gray level at said specified output voltage specified by a low-order bit of gray level data of said renewed screen during a second displaying period in said renewing period.

16. A driving control device to be used for an image display device having a memory property comprising a display section comprising a plurality of display elements each having a memory property, a driving unit to drive said display section at a specified output voltage, and a control unit to control said driving unit, the driving control device which functions as said control unit, wherein, at time when a screen of said display section is renewed by driving for a period of time corresponding to a plurality of frames according to input gray level data of a renewed screen, said driving unit sequentially drives each display element with a coarse gray level at said specified output voltage specified, for every frame, by a high-order bit of gray level data of said renewed screen during a first displaying period in a renewing period corresponding to a plurality of frames and with a fine and minute gray level at said specified output voltage specified, for every frame, by a low-order bit of gray level data of said renewed screen during a second displaying period in said renewing period.

17. The driving control device according to claim 16, further comprising a function for making a response speed of said display element during said second displaying period become slower compared with a response speed of said display element during said first displaying period by operating said driving unit at an output voltage being lower than an output voltage during said first displaying period.

18. The driving control device according to claim 16, configured to operate said driving unit during said second displaying period at a frame frequency being higher than a frame frequency during said first displaying period.

19. The driving control device according to claim 16, further comprising a look up table determined for every frame which is a table describing a group of specified conversion coefficients required for calculating driving data to determine an output voltage for said driving unit for every frame, and configured to determine said output voltage for every frame by referring to said look up table.

20. The driving control device according to claim 16, further comprising a look up table determined for every frame which is a table describing a group of specified conversion coefficients required for calculating driving data to determine an output voltage for said driving unit for every frame based on gray level data of a previous screen and gray level data of a renewed screen, and configured to determine said specified output voltage for every frame by referring to said look up table.