Combined serial/parallel light configuration and single layer PCB containing the same
View Patent ↗An LED circuit using a combination of series and parallel arrangements for optimum current sharing between LEDs. The current paths allow an LED to fail while minimizing the effect on other LEDs and noticeable luminance variance across the circuit. Some embodiments use metallic PCB technology which permits optimal thermal regulation of heat generated by the LEDs. Exemplary embodiments can be used with a single-layer PCB where only one layer of conducting material must be placed on the substrate. A constricted convection plate may be positioned behind the rear surface of the PCB to define a channel. One or more fans may be positioned to force cooling air through the channel. An LCD assembly using the same is also disclosed.
1. An LED illumination assembly comprising:
a single-conducting-layer PCB having oppositely facing front and rear surfaces;
a first group of LEDs mounted on the front surface of the PCB and connected in both parallel and series with one another by the single conduction layer;
a second group of LEDs mounted on the front surface of the PCB and connected in both parallel and series with one another by the single conduction layer, where the second group is also connected in parallel to the first group by the single conduction layer;
a positive conduction line on the front surface of the PCB and connecting to the first and second groups, where the positive conduction line is defined by the single conduction layer;
a negative conduction line on the front surface of the PCB and connecting to the first and second groups, where the negative conduction line is defined by the single conduction layer;
a constricted convection plate positioned behind the rear surface of the PCB, the space between the constricted convection plate and the rear surface of the PCB defining a cooling channel; and
a fan positioned to force cooling air through the channel.
2. The LED illumination assembly of claim 1 wherein:
the fan is positioned to draw cooling air through the channel.
3. The LED illumination assembly of claim 1 wherein:
the PCB has an aluminum substrate.
4. The LED illumination assembly of claim 1 wherein:
the fan is positioned to push cooling air through the channel.
5. The LED illumination assembly of claim 1 wherein:
the rear surface of the PCB is metallic.
6. An LED illumination assembly comprising:
a PCB having oppositely facing front and rear surfaces;
a power source;
a positive conduction line connected to the power source;
a first group of LEDs connected in parallel with each other and connected to the positive conduction line;
a second group of LEDs connected in parallel with each other and connected to the first group of LEDs in series;
a third group of LEDs connected in parallel with each other and connected to the second group of LEDs in series;
a fourth group of LEDs connected in parallel with each other and connected to the positive conduction line;
a fifth group of LEDs connected in parallel with each other and connected to the fourth group of LEDs in series;
a sixth group of LEDs connected in parallel with each other and connected to the firth group of LEDs in series;
a negative conduction line connected to the third and sixth groups of LEDs and returning to the power source;
a constricted convection plate positioned behind the rear surface of the PCB, the space between the constricted convection plate and the rear surface of the PCB defining a cooling channel; and
a fan positioned to force cooling air through the channel.
7. The LED illumination assembly of claim 6 wherein:
the positive and negative conduction lines are defined by a single layer.
8. The LED illumination assembly of claim 6 further comprising:
a seventh group of LEDs connected in parallel with each other and connected in series with the third group of LEDs and the negative conduction line.
9. An LED illumination assembly comprising:
a substrate having front and rear sides;
a layer of dielectric material placed on the front side;
a single layer of conductive material placed atop the layer of dielectric material and electrically connecting:
a positive conduction line,
a first group of LEDs connected in parallel with each other and connected to the positive conduction line,
a second group of LEDs connected in parallel with each other and connected to the first group of LEDs in series,
a third group of LEDs connected in parallel with each other and connected to the second group of LEDs in series,
a fourth group of LEDs connected in parallel with each other and connected to the positive conduction line,
a fifth group of LEDs connected in parallel with each other and connected to the fourth group of LEDs in series,
a sixth group of LEDs connected in parallel with each other and connected to the firth group of LEDs in series, and
a negative conduction line connected to the third and sixth groups of LEDs;
a constricted convection plate positioned behind the rear side of the substrate, the space between the constricted convection plate and the rear side of the substrate defining a cooling channel; and
a fan positioned to draw cooling air through the channel.
10. The LED illumination assembly of claim 9 further comprising:
a power source in electrical communication with the positive and negative conduction lines.
11. The LED illumination assembly of claim 9 wherein:
the substrate is metallic.
12. The LED illumination assembly of claim 11 wherein:
the substrate is aluminum.
13. The LED illumination assembly of claim 9 further comprising:
a second fan positioned to push cooling air through the channel.
14. The LED illumination assembly of claim 13 wherein:
the second fan is pushing cooling air that has been air conditioned.
15. A liquid crystal assembly comprising:
an LCD;
a backlight assembly placed behind the LCD, the backlight assembly having:
a PCB having oppositely facing front and rear surfaces;
a positive conduction line on the PCB;
a power source electrically connected to the positive conduction line;
a plurality of LEDs attached to the front surface of the single-layer PCB and electrically connected such that:
a first group of LEDs connected in parallel with each other and connected to the positive conduction line,
a second group of LEDs connected in parallel with each other and connected to the first group of LEDs in series,
a third group of LEDs connected in parallel with each other and connected to the second group of LEDs in series,
a fourth group of LEDs connected in parallel with each other and connected to the positive conduction line,
a fifth group of LEDs connected in parallel with each other and connected to the fourth group of LEDs in series, and
a sixth group of LEDs connected in parallel with each other and connected to the firth group of LEDs in series,
a negative conduction line connected to the third and sixth group of LEDs and returning to the power source,
a constricted convection plate positioned behind the rear surface of the PCB, the space between the constricted convection plate and the rear surface of the PCB defining a cooling channel; and
a fan positioned to force cooling air through the channel.
16. The liquid crystal assembly of claim 15 wherein:
the PCB is a metal core PCB.
17. The liquid crystal assembly of claim 15 wherein:
the PCB is aluminum.
18. The liquid crystal assembly of claim 15 wherein:
the fan is positioned to draw cooling air through the channel.
19. The liquid crystal assembly of claim 18 further comprising:
the fan is positioned to push cooling air through the channel.