DYNAMIC CONTROL CIRCUIT

• US 20170164438A1
• Filed: 06/08/2015
• Published: 06/08/2017
• Est. Priority Date: 06/17/2014
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Philips Lighting Holding BV (Signify N.V.)
• Inventors: ARULANDU, KUMAR, MALYNA, DMYTRO VIKTOROVYCH, KURT, RALPH
• Granted Patent: US 10,225,898 B2
• Time in Patent Office: Days
• 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 an 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 series impedance gradually increases in response to a decreasing LED current through the LED arrangement.

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

3. A 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. A 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. A 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. A dynamic control circuit according to claim 1, wherein the switching elements comprise bipolar junction transistors.

7. A dynamic control circuit according to claim 1, realized to present a series impedance of at least 10.0Ω

, more preferably at least 1000.0Ω

for a phase-cut angle less than 45° and

to present a series impedance of at most 0.1Ω

, more preferably at most 100.0Ω

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

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

12. A 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.

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

connecting a dynamic control circuit according to claim 1 in series with the LED arrangement;

providing an LED current to the LED arrangement; and

operating the dynamic control circuit to effect an increase in its series impedance in response to a decrease in LED current through the LED arrangement.