Electroluminescent display devices

• US 8,497,819 B2
• Filed: 10/05/2004
• Issued: 07/30/2013
• Est. Priority Date: 10/10/2003
• Status: Active Grant

• Current Assignee: Beijing Xiaomi Mobile Software Co., Ltd. (Xiaomi Corp.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Hoppenbrouwers, Jurgen J. L., Budzelaar, Franciscus P. M., Van Der Vaart, Nijs C.
• Primary Examiner(s): Lao, Lun-Yi
• Assistant Examiner(s): Sadio, Insa
• Application Number:
  US10/572,866
• Publication Number:
  US 20070008250A1
• Time in Patent Office: 3,220 Days
• Field of Search: 345 76- 83, 345/36, 345/45, 345/204, 315/169.3, 313/463, 715784-787, 715/830
• US Class Current: 345/76
• CPC Class Codes: G09G 2310/0208 using active addressing
• CPC Class Codes: G09G 2310/0227 related to multiple interlacing, i.e. involving more fields than just one odd field and one even field
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• 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 3/3225 using an active matrix
• CPC Class Codes: G09G 5/395 Arrangements specially adapted for transferring the contents of the bit-mapped memory to the screen G09G5/399 takes precedence

Abstract

In an active matrix electroluminescent display, a plurality of rows of pixels are illuminated, defining at least two bands of rows separated by a non-illuminated band. The bands of rows of pixels scroll in the column direction over time, and at most 75% of the rows are illuminated at any point in time. This method is in essence a double bar scrolling method. By scrolling two bars, the required peak brightness is reduced as the effective overall duty cycle is increased. However, the period of illumination can still remain short, so that motion perception remains improved. The scrolling speed can be halved for the same frame rate or else the frame rate can be increased to reduce flicker.

Claims

1. A method of illuminating an active matrix electroluminescent display device comprising an array of display pixels arranged in rows and columns, the method comprising acts of:

at any point in time;

forming at least two scrolling bands of a plurality of simultaneously illuminated rows o pixels;

forming a second scrolling band of a plural of non-illuminated rows of pixels for separating the at least two bands;

scrolling the at least two bands in the column direction over time such that they simultaneously change horizontal position from one time to a next time; and

displaying image data for different frames of video in different of the at least two bands so that different parts of two adjacent frames are displayed at any one time,

wherein not more than 75% of the rows of pixels are illuminated at any point in time.

2. The method as claimed in claim 1, wherein each of the at least two bands comprises a plurality of adjacent rows of pixels.

3. The method as claimed in claim 1, wherein each of the at least two bands comprise a plurality of sequential alternate row of pixels.

4. The method as claimed in claim 3, wherein one of the at least two bands comprises only odd rows and another of the at least two bands comprises only even rows.

5. The method as claimed in claim 1 wherein at most 50% of the rows are illuminated at any point in time.

6. The method as claimed in claim 5, wherein at most 30% of the rows are illuminated at any point in time.

7. An active matrix electroluminescent display device comprising:

an array of display pixels arranged in rows and columns; and

row driver circuitry for

forming at least two scrolling bands of a plurality of simultaneously illuminated rows of pixels, forming a second scrolling band of a plurality of non-illuminated rows of pixels for separating the at least two bands, the row driver circuitry illuminating each row of pixels for not more than 75% of a frame period,

wherein the at least two bands

scroll in the column direction over time such that they simultaneously change horizontal position from one time to a next time, and

image data for different frames of video is displayed in different ones of the at least two bands so that different parts of two adjacent frames are displayed at any one time.

8. The device as claimed in claim 7, further comprising a frame buffer for storing image data.

9. The device as claimed in claim 8, wherein the frame buffer stores an amount of data corresponding to a single frame of the image data.

10. The device as claimed in claim 9, wherein the image data is written into the frame buffer progressively frame by frame in sequence, such that the frame buffer stores partial image data for two adjacent frames, and wherein the image data is read out from the frame buffer at two locations simultaneously.

11. The device as claimed in claim 10, wherein the two locations include image data from different adjacent frames of image data.