Display device

• US 8,933,973 B2
• Filed: 08/03/2010
• Issued: 01/13/2015
• Est. Priority Date: 08/07/2009
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Inventors: Mizukoshi, Seiichi, Kohno, Makoto, Mori, Nobuyki
• Primary Examiner(s): Cheng, Joe H
• Application Number:
  US13/387,649
• Publication Number:
  US 20120268501A1
• Time in Patent Office: 1,624 Days
• Field of Search: 345/58, 345/76, 345/84, 345/89, 345/92, 345/214, 345/690, 349/61
• US Class Current: 345/690
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

There is provided a display device in which disadvantageous effects due to unnecessary operations of an image lag alleviating function are minimized. In a display device of active matrix type, for each of the pixels arranged in a matrix, a current-driven emissive element is provided, and the current of the emissive element is controlled using a drive TFT so as to perform display. While a black display period during which an opposite bias voltage is applied between the gate electrode and the source electrode of the drive TFT is inserted in order to alleviate image lag, this insertion is performed only when a predetermined condition is satisfied, and is performed for a certain duration according to a command by a microcomputer (10).

Claims

1. An active matrix type display device in which a current-driven emissive element is provided in each of a plurality of pixels arranged in a matrix, and a current of the emissive element is controlled using a drive TFT so as to perform sequential display of a plurality of images having a predetermined frame period, the display device comprising:

an image lag alleviating function that, when turned on, applies an opposite bias voltage between a gate electrode and a source electrode of the drive TFT;

a first detector for detecting whether or not a first image of the plurality of images includes a uniform portion having an intermediate tone;

a second detector for detecting motion of the first image from a previous image of the plurality of images; and

a microcomputer to turn on the image lag alleviating function for a preset time when the first detector detects that the first image of the plurality of images includes a uniform portion having an intermediate tone and the second detector detects motion of the first image from a previous image of the plurality of images,

wherein when the image lag alleviating function is turned on, a signal level of the first image is increased by multiplying the signal when the image lag alleviating function is turned off by a ratio of (one frame period/lights-on period within one frame period).

2. The display device of claim 1, the display device comprising a digital photo frame and the frame period is several seconds to several tens of seconds.

3. The display device of claim 1, wherein one or more of the plurality of images comprise a menu screen.

4. The display device of claim 3, wherein one or more of the plurality of images comprise icons with high brightness portions displayed on a background of intermediate tone.