Matrix display systems and methods of operating such systems

• US 5,912,651 A
• Filed: 01/06/1997
• Issued: 06/15/1999
• Est. Priority Date: 06/30/1993
• Status: Expired due to Term

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Fernando, Gerard M. X., Bitzakidis, Stefanos
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): CHANG, KENT WU
• Application Number:
  US08/779,175
• Time in Patent Office: 890 Days
• Field of Search: 345/94, 345/95, 345/99, 345/84, 345/208, 345/58, 345/77, 345/102, 345/88, 345/7
• US Class Current: 345/58
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: G09G 5/399 using two or more bit-mapped memories, the operations of which are switched in time, e.g. ping-pong buffers
• CPC Class Codes: H04N 3/127 using liquid crystals

Abstract

A matrix display system, comprising a display panel (10) having a row and column array of light modulating picture elements (12), for example liquid crystal picture elements, and panel illuminating means (19), is operated by driving the rows of picture elements such that the display information of successive fields of an applied video signal is written into the panel in respective panel display information address periods that are substantially less than the applied video signal field period and separated by a time interval, and such that successive periods in which display fields are presented to a viewer are separated by intervals in which substantially no display output is produced. The resulting dark intervals lead to an improvement in perceived resolution of moving images. The illumination means can be controlled so as to produce a display output during at least a part of the interval and substantially no display output during at least a part of the address period. Alternatively, the picture elements can be driven to their substantially non-transmissive display states during the interval between successive display information address periods and the illumination means may be turned off for a part of that interval.

Claims

1. A video display system comprising a matrix display panel having a row and column array of picture elements for modulating light which are drivable to at least substantially transmissive and substantially non-transmissive states, a light source for illuminating the display panel to produce a display output, and drive means for driving the picture elements according to a video signal, the video signal divided into successive fields of display information, and each field divided into successive lines of display information, the video signal also having a given field and line rate applied to the drive means, the drive means being operable to address the rows of picture elements sequentially at least once during successive display address periods such that the display information of each successive display field of the applied video signal is written into the display panel in a display information address period, characterised in that the display information of each display field of the applied video signal is written into the display panel in substantially less than a display information address period, and during the remainder of the display address period substantially no display output is produced, whereby dark intervals are introduced between the presentation to a viewer of successive display fields of the panel, which leads to an improvement in the perceived sharpness of moving images in the display.

2. A matrix display system according to claim 1, characterised in that the drive means include a control circuit for the illuminating means which is arranged to control light output from the illuminating means in relation to the driving of the picture elements such that a display output is produced from the display panel for at least a part of the time interval and substantially no display output is produced during at least a part of the display information address period.

3. A matrix display system according to claim 2, characterised in that the illuminating means is controlled by the control circuit to illuminate the panel only during said time intervals.

4. A matrix display system according to claim 2, characterised in that the illuminating means is controlled by the control circuit to illuminate the display panel during a latter part only of said time intervals.

5. A matrix display system according to claim 2, characterised in that the drive means are operable to drive the picture elements again during the interval following a respective display information address period to write into the array of picture elements the same display information as written into the display panel during said respective display information address period.

6. A matrix display system according to claim 3, characterised in that the illuminating means is controlled by the control circuit to illuminate the display panel during a latter part only of said time intervals.

7. A matrix display system according to claim 3, characterised in that the drive means are operable to drive the picture elements again during the interval following a respective display information address period to write into the array of picture elements the same display information as written into the display panel during said respective display information address period.

8. A matrix display system according to claim 4, characterised in that the drive means are operable to drive the picture elements again during the interval following a respective display information address period to write into the array of picture elements the same display information as written into the display panel during said respective display information address period.

9. A matrix display system according to claim 1, characterized in that the drive means are operable to drive the picture elements of the array to their substantially non-transmission display states in the intervals between successive display information address periods.

10. A matrix display system according to claim 9, characterised in that the drive means is operable to drive the rows of picture elements in sequence to their substantially non-transmissive display states during the interval and with the driving of the first row of picture elements of the array coinciding substantially with the beginning of the interval.

11. A matrix display system according to claim 9, characterised in that the illuminating means is arranged to illuminate the display panel continuously during operation.

12. A matrix display system according to claim 9, characterised in that the drive means include a control circuit connected to the illuminating means which switches the illuminating means off or to a comparatively low light output level for a part of said intervals.

13. A matrix display system according to claim 12, characterised in that the drive means is operable to drive the rows of picture elements in sequence to their substantially non-transmissive display states during the interval and with the driving of the first row of picture elements commencing a predetermined time delay after the beginning of the interval, and in that the illumination means is operable by the control circuit to illuminate the display panel during said delay.

14. A matrix display system according to claim 12, characterised in that the drive means is operable to drive the rows of picture elements in sequence to their substantially non-transmissive display states during the interval and with the driving of the first row of picture elements of the array coinciding substantially with the beginning of the interval.

15. A matrix display system according to claim 12, characterised in that the control circuit switches the illuminating means off, or to a comparatively low light output level, for a period comprising a latter part of the interval and an initial part of the following display information address period.

16. A matrix display system according to claim 15, characterised in that the drive means is operable to drive the rows of picture elements in sequence to their substantially non-transmissive display states during the interval and with the driving of the first row of picture elements commencing a predetermined time delay after the beginning of the interval, and in that the illumination means is operable by the control circuit to illuminate the display panel during said delay.

17. A matrix display system according to claim 15, characterised in that the drive means is operable to drive the rows of picture elements in sequence to their substantially non-transmissive display states during the interval and with the driving of the first row of picture elements of the array coinciding substantially with the beginning of the interval.

18. A matrix display system according to claim 1, characterised in that the duration of a display information address period and a succeeding time interval combined corresponds to a field period of an applied video signal.

19. A matrix display system according to claim 18, characterised in that the duration of a display information address period and the duration of an interval are each approximately equal to one half of a field period of an applied video signal.

20. A matrix display system according to claim 1, characterised in that the display panel comprises an active matrix addressed display panel in which each of the picture elements is driven via a respective switching device.

21. A matrix display system according to claim 1, characterised in that the picture elements comprise liquid crystal picture elements.

27. A method according to claim 1, characterised in that the illuminating means is switched off, or to a comparatively low light output level, for a part of the interval.

28. A method according to claim 27, characterised in that the illuminating means is switched off, or to a comparatively low light output level, for a period comprising a latter part of the interval and an initial part of the following display information address period.

22. A method of operating a video display system comprising a matrix display panel having a row and column array of picture elements for modulating light which are drivable to at least substantially transmissive and substantially non-transmissive states, a light source for illuminating the display panel to produce a display output, and drive means for driving the picture elements according to a video signal, the video signal divided into successive fields of display information, and each field divided into successive lines of display information, the video signal also having a given field and line rate applied to the drive means, in which the rows of picture elements are sequentially addressed at least once during successive display address periods such that the display information of each successive display field of the applied video signal is written into the display panel in a display information address period, characterised in that the display information of each display field of the applied video signal is written into the display panel in substantially less than a display information address period, and during the remainder of the display address period substantially no display output is produced, whereby dark intervals are introduced between the presentation to a viewer of successive display fields of the panel, which leads to an improvement in the perceived sharpness of moving images in the display.

23. A method according to claim 22, characterised in that the illumination of the display panel by the illumination means is controlled such that a display output is produced during at least a part of said time interval and such that substantially no display output is produced during at least a part of a said address period.

24. A method according to claim 23, characterised in that the display panel is illuminated only during said time intervals.

25. A method according to claim 23, characterised in that the display panel is illuminated during a latter part only of said time intervals.

26. A method according to any one of claim 23, characterised in that the display information written into the array of picture elements during a respective display information address period is again written into the array of picture elements during the time interval following that address period.

29. A method according to claim 22, characterized in that the picture elements of the array are driven to their substantially non-transmissive display states in the interval between successive display information address periods.

30. A method according to claim 29, characterised in that the duration of a display information address period together with a time interval corresponds to a field period of an applied video signal.

31. A method according to claim 30, characterised in that the durations of an address period and an interval are each approximately one half of a field period of an applied video signal.