Current supply for luminescent diodes

• US 8,063,575 B2
• Filed: 01/04/2005
• Issued: 11/22/2011
• Est. Priority Date: 07/04/2002
• Status: Expired due to Term

• Current Assignee: Tridonic Jennersdorf GMBH (Zumtobel Group AG)
• Original Assignee: Tridonic AG (Zumtobel Group AG), Tridonic Jennersdorf GMBH (Zumtobel Group AG)
• Inventors: Zimmermann, Michael, Tasch, Stefan, Tobler, Felix
• Primary Examiner(s): Lie; Angela
• Application Number:
  US11/028,297
• Publication Number:
  US 20050218836A1
• Time in Patent Office: 2,513 Days
• Field of Search: 315/291, 315/209.R, 315/219, 315/297, 362/555
• US Class Current: 315/291
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/36 Circuits for reducing or suppressing harmonics, ripples or electromagnetic interferences [EMI]
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 45/382 with galvanic isolation between input and output
• 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

The present invention is based on a regulation circuit (200a, 200b) for making available a constant current supply on the basis of a transformer principle, in which there flows through the luminescent diodes (D1, . . . ,DN) a triangular a.c. current (I_D) varying periodically around a d.c. current value. With this method it is afforded by means of a circuitry provision that both the charging and also the discharging current (I_L1) of an inductive reactance (X_L1) connected in series to the luminescent diodes (D1, . . . ,DN), functioning as a storage choke (L1) for filtering of mains harmonics, flows as diode current (I_D) through the luminescent diodes (D1, . . . ,DN). The advantage of this method consists in a significant reduction of the overall power loss (P_{V, ges}) of the LED illumination module (100). According to one exemplary embodiment of the invention the ceramic circuit board (102) of the LED illumination module (100) in accordance with the invention has a direct mains current supply (104, 108), which for protection from mechanical damage is accommodated in a transparent housing (106) having a highly transparent polymer mass (110) serving as optically active lens surface.

Claims

1. A current supply circuitry for at least one luminescent diode supplied with a.c. current via a current supply mains, comprising:

at least one inductive reactance connected as a storage choke in series with the luminescent diode,

switching stages for switching over between a charging or a discharging process occurring in the storage choke upon over-shooting or under-shooting of threshold values of respective control voltages of the switching stages;

a free running current path, connected parallel to the series connection of the luminescent diode and the storage choke, for at least a part of the discharge current released by the storage choke to the luminescent diode upon blocking of one of the switching stages;

a first shunt measurement resistance for detecting the diode current flowing through the luminescent diodes during a charging process occurring in the storage choke; and

a second shunt measurement resistance for detecting the diode current flowing through the luminescent diode during the discharging process occurring in the storage choke.

2. The circuitry according to claim 1,

wherein the first shunt measurement resistance is settable for dimming the at least one luminescent diode.

3. The circuitry of claim 1, further comprising a signal transfer element for feeding back the current flowing through the at least one luminescent diode, tapped off at the second shunt measurement resistance, to a control input of the at least one switching stage, the signal transfer element serving for galvanic de-coupling of a voltage dropping at the second shunt measurement resistance and a control voltage of the at least one switching stage.

4. The circuitry according to claim 3,

wherein the signal transfer element employed for potential separation is an opto-coupler diode.

5. The circuitry according to claim 3,

wherein the signal transfer element employed for potential separation is a level offset stage.

6. The circuitry according to claim 1, further comprising a Zener diode as a voltage limiter tapped off at output terminals of an opto-coupler diode for stabilizing a control voltage of a first electronically controllable semiconductor power transistor.

7. The circuitry of claim 1,

wherein a free-running diode is the free-running current path connected parallel to the series connection of the at least one luminescent diode and the storage choke.

8. The circuitry of claim 1, further comprising a potentiometer as a series resistor in a control circuit of a first semiconductor power transistor for dimming a light intensity of radiation emitted from the at least one luminescent diode, which intensity is proportional to the diode current.

9. The circuitry of claim 1,

further comprising a time dependent controller for switching between the charging process and the discharging process occurring in the storage choke.

10. The circuitry according to claim 1, further comprising a Zener diode as a voltage limiter tapped off at output terminals of a level offset stage for stabilizing a control voltage of a first electronically controllable semiconductor power transistor.

11. The circuitry according to claim 1, further comprising a Zener diode as a voltage limiter tapped off at output terminals of a potential offset stage for stabilizing a control voltage of a first electronically controllable semiconductor power transistor.

12. A method for supplying at least one luminescent diode with a.c. current, comprising the steps of:

connecting at least one inductive reactance as a storage choke in series with the at least one luminescent diode;

switching switching stages between a charging process and a discharging process occurring in the storage choke upon over-shooting or under-shooting of threshold values of the respective control voltages of the switching stages;

releasing at least a part of the discharge current to the luminescent diode upon blocking of one of the switching stages, wherein the discharge current is released along a free running current path, connected parallel to the series connection of the luminescent diode and the storage choke;

detecting a diode current flowing through the luminescent diode during the discharging process occurring in the storage choke by using a first shunt measurement resistance; and

detecting the diode current flowing through the luminescent diode during a charging process occurring in the storage choke by using a second shunt measurement resistance.