Apparatus for dynamically circumventing faults in the light emitting diodes (LEDs) of a pixel in a graphical display

• US 9,342,266 B2
• Filed: 08/08/2007
• Issued: 05/17/2016
• Est. Priority Date: 08/08/2007
• Status: Active Grant

• Current Assignee: Landmark Screens, LLC
• Original Assignee: Landmark Screens, LLC
• Inventors: Scheibe, Paul O.
• Primary Examiner(s): Edwards, Carolyn R
• Application Number:
  US11/836,122
• Publication Number:
  US 20090040197A1
• Time in Patent Office: 3,205 Days
• Field of Search: 345/90, 345/204, 345 76- 78, 345 82- 83, 315/169.3, 313/463
• US Class Current: 1/1
• CPC Class Codes: G06F 3/1446 display composed of modules, e.g. video walls
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2360/148 the light being detected by light detection means within each pixel
• CPC Class Codes: G09G 3/14 Semiconductor devices, e.g. diodes
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant

Abstract

An apparatus dynamically circumvents faults in the light emitting diodes (LEDs) of a pixel in a graphical display. The LEDs are organized into groups of one or more LEDs. The apparatus includes drivers for generating a current to an associated group of LEDs of the pixel and fault detectors associated with each group of LEDs. The drivers may be driven, for example, by pulse-modulated signals specifying average currents for the groups of LEDs. The fault detectors each detect fault in an associated group of LEDs and asserts a fault signal when a fault is detected. In addition, an encoder is provided to receive the fault signals from the fault detectors and to provide signals encoding the faults detected and identifying the associated groups of LEDs. A controller that receives the encoded signals may adjust the driver signals for the groups of LEDs for which no fault is detected, in order to compensate for the detected faults.

Claims

1. An apparatus for dynamically circumventing faults in the light emitting diodes (LEDs) of a pixel in a graphical display, the LEDs being organized into groups, each group having one or more LEDs, the apparatus comprising:

a plurality of drivers each provided for generating a current to an associated group of LEDs of the pixel, each driver being driven by a pulse-modulated signal specifying an average current for the associated group of LEDs;

a plurality of fault detectors each electrically coupled to an output terminal of the group of LEDs associated with a corresponding one of the drivers, each fault detector being provided for detecting a fault in the group of LEDs associated with that corresponding driver by detecting a current or voltage at the output terminal and for asserting a fault signal when a fault is detected in that associated group of LEDs;

an encoder receiving the fault signals from the plurality of fault detectors and providing signals encoding the fault detected and identifying the associated group of LEDs; and

a controller receiving the encoded signals and signals indicating a color to be displayed by the pixel, and providing the pulse-modulated signals for driving the groups of LEDs for which no fault is detected.

2. An apparatus as in claim 1, wherein the plurality of drivers include drivers for redundant groups of LEDs, the controller activating each redundant group of LEDs in accordance with the encoded signals.

3. An apparatus as in claim 1, wherein the fault detectors detect short circuits in the associated groups of LEDs.

4. An apparatus as in claim 1, wherein each fault detector comprises a voltage threshold detector which detects a drop in voltage at the output terminal.