Electroluminescent display devices

• US 20070008250A1
• Filed: 10/05/2004
• Published: 01/11/2007
• 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, Van Der Vaart, Nijs, Budzelaar, Franciscus
• Granted Patent: US 8,497,819 B2
• Time in Patent Office: Days
• 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 (10) of rows separated by a non-illuminated band (12). The bands (10) 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, at any point in time, illuminating a plurality of rows of pixels, the plurality of rows defining at least two bands (10) of rows separated by a non-illuminated band (12), the at least two bands (10) of rows of pixels scrolling in the column direction over time, and wherein at most 75% of the rows are illuminated at any point in time.

2. A method as claimed in claim 1, wherein each band (10) of rows of pixels comprises a plurality of adjacent rows of pixels.

3. A method as claimed in claim 1, wherein image data for different frames of the image to be displayed are displayed in the different bands.

4. A method as claimed in claim 1, wherein each band (10) of rows of pixels comprises a plurality of sequential alternate rows of pixels.

5. A method as claimed in claim 4, wherein one band of rows comprises only odd rows and another band of rows comprises only even rows.

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

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

8. An active matrix electroluminescent display device comprising an array of display pixels (1) arranged in rows and columns, and row driver circuitry (8) for illuminating a plurality of rows of pixels simultaneously, the plurality of rows defining at least two bands (10) of rows separated by non-illuminated bands (12), wherein the row driver circuitry comprises means for illuminating each row for at most 75% of the frame period, such that the illuminated rows define at least two bands (10) of rows of pixels which scroll in the column direction over time.

9. A device as claimed in claim 8, further comprising a frame buffer (22) for storing image data.

10. A device as claimed in claim 9, wherein the frame buffer (22) stores an amount of data corresponding to a single frame of image data.

11. A device as claimed in claim 10, wherein data is written into the frame buffer (22) progressively frame by frame in sequence, such the frame buffer (22) stores partial data for two adjacent frames, and wherein data is read out from the frame buffer at two locations simultaneously.

12. A device as claimed in claim 11, wherein the two locations contain data from different adjacent frames of image data.