Optical vehicle display

• US 6,396,466 B1
• Filed: 12/01/1999
• Issued: 05/28/2002
• Est. Priority Date: 12/03/1998
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Agilent Technologies Europe BV (Agilent Technologies, Inc.)
• Inventors: Pross, Gerhard, Maile, Markus, Seher, Jens-Peter
• Primary Examiner(s): Wu, Xiao
• Application Number:
  US09/452,609
• Time in Patent Office: 909 Days
• Field of Search: 345/82,83,39,40,44,690,691 340/815.4,525,479,468,469 303/7
• US Class Current: 345/82
• CPC Class Codes: H05B 45/347 Dynamic headroom control [DHC]
• CPC Class Codes: H05B 45/37 Converter circuits
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• CPC Class Codes: H05B 45/56 involving measures to prevent abnormal temperature of the LEDs
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

Optical vehicle display having a set of LEDs arranged in a matrix and having a control circuit which acts as a controllable current source and as controllable voltage source, so that a constant current can be applied for each LED and the respective voltage is established accordingly. An optical vehicle display designed in this way permits a design as a taillight, brake light, flashing indicator and the like in a motor vehicle with favorable production at the same time due to reduced faulty assembly and simple adjustment of the light values.

Claims

1. An optical vehicle display having a set of LEDs connected to a first logic circuit, said optical vehicle display comprising:

a matrix of LEDs including said set of LEDs having at least one column of at least one LED, with said at least one LED in said at least one column being connected in series, wherein each of said at least one columns are connected in parallel;

first control circuit, connected to said at least one column, which acts as a controllable current source to produce a set current through said at least one column; and

second control circuit, connected to said matrix of LEDs, which acts as a voltage source for adjusting a voltage across said matrix of LEDs as a function of said set current.

2. An optical vehicle display according to claim 1, wherein said second control circuit establishes a lowest possible voltage required for proper functioning of the LEDs with minimal power consumption.

3. An optical vehicle display according to claim 1, wherein said first control circuit includes a second logic circuit which is connected to said second control circuit.

4. An optical vehicle display according to claim 1, wherein said voltage across said matrix of LEDs is set in the second control circuit by pulse width modulation.

5. An optical vehicle display according to claim 1, wherein said first logic circuit delivers a signal when one or more LEDs fail.

6. An optical vehicle display according to claim 1, wherein said first control circuit has connection means and control means for setting current through said LEDs dependent on an ambient light and/or ambient condition.

7. An optical vehicle display according to claim 1, further comprising a measuring device to measure a forward voltage of at least one LED in order to set the set current such that a junction temperature of said at least one LED is below the maximum allowed.

8. An optical display device according to claim 1, wherein said first logic circuit switches said LEDs cyclically at a frequency that is not visible to the human eye to set the brightness in day and night operation.