ILLUMINATION DEVICE FOR A MOTOR VEHICLE, MORE PARTICULARLY HIGH-RESOLUTION HEADLAMP

Abstract

An illumination device having a light-emitting diode field and an adjustable current source for each LED. The current source delivers a pulse width modulated current having a pulse height. An open-loop/closed-loop controller is provided for the open-loop/closed-loop control of the brightness of the LEDs. A setpoint value for the pulse height can be produced for the current source. A brightness value can be specified for each LED in accordance with the setpoint value, encoded in a video signal, and provided at a video signal output. The light-emitting diode field has a decoder, which is connected to the video signal input and via which the brightness value can be decoded from the video signal and converted into a duty cycle with which the pulse height can be produced;

Claims

1. An illumination device for a motor vehicle, the illumination device comprising: a light-emitting diode field having n LEDs; and an adjustable current source for at least two of the LEDs, each adjustable current source providing a pulse width modulated current having a pulse height to power the associated LED; an open-loop and/or closed-loop controller for the open-loop and/or closed-loop control of the brightness of the LEDs of the light-emitting diode field, wherein the open-loop and/or closed-loop controller provides a setpoint value for the pulse height of the pulse width modulated current at least for each adjustable current source, wherein a brightness value is specified with the open-loop and/or closed-loop controller for each LED in accordance with the setpoint value for the pulse height of the adjustable current source associated with the LED and encoded in a video signal and provided at a video signal output, wherein the light-emitting diode field has a video signal input, which is connected to the video signal output of the open-loop and/or closed-loop controller, wherein the light-emitting diode field has a decoder which is connected to the video signal input and via which the brightness value is decoded from the video signal for each LED and converted into a duty cycle with which the pulse width modulated current is produced by the adjustable current source associated with the LED with the pulse height in accordance with the setpoint value predetermined for the current source by the open-loop and/or closed-loop controller, and wherein the setpoint values for the pulse height of the current are adapted to be encoded in the video signal by the open-loop and/or closed-loop controller and also adapted to be decoded from the video signal by the decoder and used by the adjustable current sources to set the level of the current or the pulse height of the pulse width modulated current.

2. The illumination device according to claim 1, wherein the video signal is an RGB signal.

3. The illumination device according to claim 1, wherein the setpoint values for the pulse height of the current are encoded in the area not used for the brightness values or a blanking area of the video signal.

4. The illumination device according to claim 1, wherein the adjustable current sources operate according to a master-slave principle, wherein at least one of the adjustable current sources as a master specifies the pulse height of the current and transmits it to the remaining adjustable current sources.

5. The illumination device according to claim 1, further comprising a constant brightness value for each LED of the light-emitting diode field, and a simultaneous change of the setpoint values for the pulse height of the pulse width modulated current and the duty cycles is possible.

6. A motor vehicle comprising an illumination device according to claim 1.

7. A method for operating an illumination device according to claim 1, the method comprising: producing, via the open-loop and/or closed-loop controller, a setpoint value for a pulse height of the pulse width modulated current at least for each adjustable current source associated with an LED; providing the setpoint value and specifying a brightness value for each LED in accordance with the setpoint value for the pulse height; encoding, via the open-loop and/or closed-loop controller, the setpoint value for the pulse height of the pulse width modulated current and the brightness value for each LED in a video signal and providing the encoded setpoint value at a video signal output; decoding, via a decoder connected to the video signal input of the light-emitting diode field, the brightness value from the video signal for each LED and converting it into a duty cycle; decoding, via the decoder, the setpoint values for the pulse height of the current; and using, by the adjustable current sources, the decoded setpoint values to set the level of the current or the pulse height of the pulse width modulated current.

8. The method according to claim 7, wherein, with constant brightness values for each LED of the light-emitting diode field, a substantially simultaneous change of the setpoint values for the pulse height of the pulse width modulated current and the duty cycles is possible.

9. The illumination device according to claim 1, wherein the illumination device is a high-resolution headlight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0017] FIG. 1 is a schematic structure of an illumination device of the invention; and

[0018] FIG. 2 is a schematic structure of a single video image of the video signal.

DETAILED DESCRIPTION

[0019] Illumination device 1 of the invention shown in FIG. 1 comprises a light-emitting diode field 2 formed of five series circuits. Each series circuit comprises a light-emitting diode 3 and an adjustable current source 4. Each adjustable current source 4 delivers a pulse width modulated current with a pulse height to power the associated LED 3. The series circuits are connected in parallel. Furthermore, light-emitting diode field 2 comprises a decoder 8, which is connected at its output to each adjustable current source 4.

[0020] In addition to light-emitting diode field 2, illumination device 1 comprises an open-loop and/or closed-loop controller 5. Open-loop and/or closed-loop controller 5 is connected via a video output 6 to a video signal input 7 of the light-emitting diode field and to the decoder 8.

[0021] Open-loop and/or closed-loop controller 5 is used to produce a setpoint value 22 for a pulse height of the pulse width modulated current for each adjustable current source 4. Furthermore, open-loop and/or closed-loop controller 5 determines a brightness value for each LED 3 in accordance with setpoint value 22 for the pulse height of the adjustable current source 4 assigned to each LED 3. Both setpoint value 22 for the pulse height of the current and the brightness value for each LED 3 are encoded in a video signal and provided at video signal output 6 of open-loop and/or closed-loop controller 5.

[0022] Decoder 8 decodes the brightness value from the video signal for each LED 3 and converts it into a duty cycle. Similarly, setpoint values 22 for the pulse height of the current are decoded from the video signal by decoder 8. Both the duty cycles and setpoint values 22 for the pulse height of the current are provided at the output of the decoder and are used by the adjustable current sources 4 to set the current level, i.e., the pulse height of the pulse width modulated current supplying the respective associated light-emitting diode 3.

[0023] FIG. 2 shows the schematic structure of a single video frame 9 of the video signal used to transmit setpoint values 22 for the pulse height of the current to light-emitting diode field 2.

[0024] Video image 9 has a total height 10 and a total width 11. Total height 10 is divided into four regions 13, 15, 17, 19. The first region indicates the active height 13. Vertical front porch 19 is adjacent to the first region in the lower region of the image, and vertical back porch 17 in the upper region of the image. Furthermore, a region of vertical synchronization 15 adjoins vertical back porch 17.

[0025] The total width 11 is also divisible into four regions 12, 14, 16, 18. The first region indicates the active width 12; this is enclosed in the right part of the image by horizontal front porch 18 and in the left part of the image by horizontal back porch 16. A region of horizontal synchronization 14 is adjacent to horizontal back porch 16.

[0026] The useful information of the video signal is transmitted in the region spanned by the active height 13 and active width 12. This region is in turn divisible into a first video field 20 and a second video field 21. The brightness values of the individual LEDs 3 are encoded in 16383 pixels for each video field 20, 21.

[0027] The unused area of the video image, the blanking area, is outside the area spanned by the active height 13 and active width 12. Vertical back porch 17, in which setpoint values 22 for the pulse height of the current are transmitted, also belongs to this blanking area.

[0028] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.