Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/30—Driver circuits
  • H05B45/37—Converter circuits
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/30—Driver circuits
  • H05B45/32—Pulse-control circuits

Definitions

• the present invention relates to a method for driving at least one LED which is performed in the following steps, by generating a pulsating current through the LED, controlling the voltage drop over at least the LED and generating pulses with at least a raising flange and a falling flange.
• LEDs are getting more and more popular and used extensively in general lighting applications due to high efficiently and low power consumption of LEDs.
• Other application where LEDs still are used in limited scope is within strobe and flash applications; this is because LEDs are still not capable of achieving high-peak intensities compared to conventional discharge tubes etc. It is the object of the present invention to solve this problem.
• EP 201561 1 Al discloses a method for driving a LED and an illumination system comprising at least one LED.
• the LED is supplied with a driving pulse signal at a cycle equal to a unit of time, wherein said driving pulse signal has a peak value equal to n times of a prescribed current value and a duration of T/n', and n/n' ⁇ 1.
• said driving pulse signal has a peak value equal to n times of a prescribed current value and a duration of T/n', and n/n' ⁇ 1.
• the driving circuit comprises a filtration circuit for filtration of EMI/EMC in order to reduce noise from the electronic components.
• the circuit comprises a special circuit for reducing the effect of the phase difference between voltage and current.
• the object can be achieved by generating the pulses with a sloping rising flange.
• very high-peak intensities can be achieved malting LED suitable for strobe and flash applications by which this driver technology opens a whole new world of applications where LEDs can be implemented. It is possible to increase the peak intensities in all applications where flashing can be accepted.
• the falling flange is generated as a sloping curve.
• a slow discharge of passive components in a driving circuit can be achieved.
• the pulse is generated as a sinus half pulse.
• the half sinus curve has the advantage that all capacities or coils that exist in a serial connection of LEDs will reach a charging and a build-up of current relatively slowly, so these components have less influence on the current when the current starts flowing from serial up to the maximum value.
• By a fast racing slope capacities that always exist, also with LEDs will have very low impedance according to the high fi-equency contents of the rising edge of a square-formed curve.
• coils which are only veiy small in value could exist at least in the connecting lines, or if the lines are having sharp turns, they will be operating as a veiy small coil.
• the present invention it is possible to increase the light emission of LEDs for all kinds of circuits where pulsation is used.
• strobe lighting in light shows it is important that the power of the LEDs can be increased.
• other kinds of LED light for example street lighting where it is accepted that LEDs are perform a pulsation maybe with a net frequency, is it possible to increase the light that is achieved from the LED.
• street lighting where it is accepted that LEDs are perform a pulsation maybe with a net frequency
• car headlights it should be possible to have fast pulsating LEDs and in mat way also to increase the power of the LEDs.
• Figure 1 shows a possible embodiment for a serial connection of LEDs
• figure 2 shows curvature of pulses known from traditional state of die art
• figure 3 shows a possible curvature for pulses used by the present invention
• figure 4 shows one possibility for driving the LEDs in figure 1 with a sinus half wave.
• Figure 1 shows a circuit comprising a serial connection of LEDs, 2a, 2b, 2c, 2d-2n.
• the lines 10 and 12 are connected to a control circuit 14 which control circuit is connected to a power source 16.
• the circuit 14 will generate the pulses to drive the LEDs.
• Figure 2 shows a coordinate system 100 having an access 102 indicating the current, and a time axis 104. Curves are shown with a rising flange 106 and a falling flange 108. The curve 1 10 indicates the light that is emitted from LEDs which are subjected to these current curves for activation.
• Figure 3 shows a coordinate system 200 having a current axis 102 and a time axis 204.
• the pulses have a rising flange 206 and a falling flange 208.
• the light emission is indicated with a curvature 210. It can be seen that sufficiently more light has been achieved, because the pulses, and thereby the current and also the power dissipated in the LEDs, are much higher than indicated in figure 2.
• Figure 4 shows a coordinate system having a current axis 302 and a time axis 304.
• the curvature is a sinus half wave having a rising slope 306 and a falling slope 308.
• the figure also indicates the light emission 310 from the LEDs.
• Fig. 5 shows a coordinate system having a current axis 402 and a time axis 404 and two curves.
• Curve 406 represents the current applied to a LED light source
• curve 410 shows responding output of light of the same LED. A standard normal current value being applied to an LED thus results in a corresponding nominal light output.
• Fig 6 shows a coordinate system having a current axis 502 and a time axis 504 and two curves.
• Curve 506 represents the current applied to a LED light source
• curve 510 shows responding output of light of the same LED.
• Fig 6 shows the same LED under test being given a 10 times nominal current. The resulting light output actually reaches nearly 10 times output but falls quickly depending on LED type. However, this creates a very high-peak light output which is very useful in a flash lighting application. If the current not is turned off after the LED has lowered its intensity, it will eventually fail.
• Fig 7 shows a coordinate system having a current axis 602 and a time axis 604 and two curves.
• Curve 606,608 represents the current applied to a LED light source
• curve 610 shows responding output of light of the same LED.
• Fig. 7 shows how this invention, through the steps of testing in a lab from Fig 5 and 6, has created a way of solving this issue by increasing the current at a rate that creates maximum flash intensity without destroying the LED and its surrounding components, and this slow increase, Fig. 7-606, illuminates the capacitance influence and thereby ensures an equal distribution of the current inside the LED and components ensuring that flash and be cycled again and again at 10 time nominal value without destroying the LED.
• This problem can be eliminated by driving the LEDs in a completely different way than what is normally specified by manufacturers, by using a sloped increase of the current of such length that the capacitance internally of each LED and other surrounding components can be rendered of no importance, or less than 2 times of the RMS current of the pulse
• This technology is probably also suitable for other light sources as well, such as OLED etc.

Landscapes

• Circuit Arrangement For Electric Light Sources In General (AREA)
• Led Devices (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=45992572

Family Applications (1)

Country Status (2)

Family Cites Families (8)

• 2012
  • 2012-04-03 EP EP12715729.5A patent/EP2695486A2/de not_active Withdrawn
  • 2012-04-03 WO PCT/IB2012/051623 patent/WO2012137130A2/en not_active Ceased

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events