Dynamic control circuit

• US 10,225,898 B2
• Filed: 06/08/2015
• Issued: 03/05/2019
• Est. Priority Date: 06/17/2014
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Philips Lighting BV (Koninklijke Philips N.V.)
• Inventors: Arulandu, Kumar, Malyna, Dmytro Viktorovych, Kurt, Ralph
• Primary Examiner(s): Owens, Douglas W
• Assistant Examiner(s): Sathiraju, Srinivas
• Application Number:
  US15/320,067
• Publication Number:
  US 20170164438A1
• Time in Patent Office: 1,366 Days
• Field of Search: None
• CPC Class Codes: F21K 9/238 Arrangement or mounting of circuit elements integrated in the light source
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/3575 by means of dummy loads or bleeder circuits, e.g. for dimmers
• CPC Class Codes: H05B 45/36 Circuits for reducing or suppressing harmonics, ripples or electromagnetic interferences [EMI]
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/44 with an active control inside an LED matrix
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

The invention describes a dynamic control circuit (1) realized for connection in series with an LED arrangement (2), characterized by a first switching element (Q1) realized to provide a path for the LED current (I_LED), and a monitoring arrangement (M) realized to control the first switching element (Q1) according to the level of the LED current (I_LED) SO that the dynamic control circuit (1) presents a series impedance (Z_dyn), which series impedance (Z_dyn) gradually increases in response to a decreasing LED current (I_LED) through the LED arrangement (2). The invention also describes a dimmable lighting arrangement (10) comprising an LED arrangement (2); a driver (3) realized to provide an input voltage (V_in) and an input current (I_LED) to the LED arrangement (2); and such a dynamic control circuit (1) connected in series with the LED arrangement (2). The invention further describes retrofit LED light-bulb (100); and a method of driving an LED arrangement.

Claims

1. A dynamic control circuit realized for connection in series with a Light Emitting Diode (LED) arrangement, characterized by a first switching element realized to provide a path for the LED current, and a monitoring arrangement realized to control the first switching element according to the level of the LED current so that the dynamic control circuit presents a series impedance which increases in response to a decreasing LED current through the LED arrangement, wherein the series impedance is inversely non-linearly proportional to the LED current.

2. The dynamic control circuit according to claim 1, wherein the monitoring arrangement comprises a second switching element arranged to generate a control signal to control the operation of the first switching element.

3. The dynamic control circuit according to claim 1, wherein the monitoring arrangement comprises a filter circuit portion arranged to filter the control signal of the first switching element.

4. The dynamic control circuit according to claim 1, wherein the dynamic control circuit comprises only discrete components arranged to operate on a voltage supplied at the output of the LED arrangement.

5. The dynamic control circuit according to claim 1, wherein the components of the dynamic control circuit are chosen on the basis of a desired series impedance at specific LED current levels.

6. The dynamic control circuit according to claim 1, wherein the first switching element comprises a bipolar junction transistor.

7. The dynamic control circuit according to claim 1, realized to present a series impedance of at least 10.00, for a phase-cut angle less than 45°

and at most 0.10, for a phase-cut angle greater than 135°

.

8. A dimmable lighting arrangement comprising:

an LED arrangement;

a driver realized to provide an input current to the LED arrangement; and

a dynamic control circuit according to claim 1 connected in series with the LED arrangement.

9. The lighting arrangement according to 8, comprising a bleeder circuit arrangement realized to bleed a portion of the input current according to a voltage at the output of the LED arrangement.

10. The lighting arrangement according to 9, wherein the bleeder circuit arrangement comprises an NPN bipolar junction transistor whose base is connected to an output of the LED arrangement.

11. The lighting arrangement according to claim 8, wherein the driver comprises a switched-mode power supply.

12. The lighting arrangement according to claim 8, comprising a buffer capacitor connected across the outputs of the driver.

13. A retrofit LED light-bulb, comprising:

a housing with a GU10 socket connector for connecting to a dimmable power supply;

an LED arrangement comprising a number of LEDs mounted on a circuit board in the housing; and

a dynamic control circuit according to claim 1 connected in series with the LED arrangement.

15. The dynamic control circuit according to claim 1, realized to present a series impedance of at least 1000.00 for a phase-cut angle less than 45°

and to present a series impedance of at most 100.00 for a phase-cut angle greater than 135°

.

14. A method of driving an LED arrangement, comprising the steps of:

connecting a dynamic control circuit in series with the LED arrangement, the dynamic control circuit comprising a switching element;

providing an LED current to the LED arrangement, wherein the switching element is arranged to provide a path for the LED current; and

operating the switching element of the dynamic control circuit to affect an increase in its series impedance in response to a decrease in LED current through the LED arrangement, wherein the series impedance is inversely non-linearly proportional to the LED current.