Device for driving a load

• US 8,354,805 B2
• Filed: 11/03/2008
• Issued: 01/15/2013
• Est. Priority Date: 11/05/2007
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Jacobs, Joseph Hendrik Anna Maria, Shen, Jie, Hente, Dirk
• Primary Examiner(s): TRAN, THUY V
• Application Number:
  US12/740,125
• Publication Number:
  US 20100259194A1
• Time in Patent Office: 1,534 Days
• Field of Search: 315/291, 315/307, 315/308, 315/360
• US Class Current: 315/360
• CPC Class Codes: H05B 45/24 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/375 using buck topology

Abstract

Devices (10) for driving loads (20) such as organic/inorganic light emitting diodes are provided with drivers (11) for driving the loads (20), with converters (12) for converting first parameter signals defining parameters of the loads (20) into second parameter signals each being defined by one bit per time interval, and with digital controllers (13) for controlling the drivers (11) in response to the second parameter signals. The converter (12) may comprise a comparator circuit (40) and a timer circuit (41) for comparing the first parameter signal with a reference signal and for generating the second parameter signal having a respective first or second value of two possible values in case of a respective first or second comparison result. The parameter may be a current flowing through or light emitted by at least a part of the load (20). The driver (11) may be a buck/boost/buck boost/fly back converter.

Claims

1. A method, comprising:

driving a load,

converting a first parameter signal defining a parameter of the load into a second parameter signal, wherein the second parameter signal is a binary signal having, during each time interval of a group of time intervals, one value out of only two possiblw values, and

digitally controlling the driving in response to the second parameter signal,

wherein driving the load activating a switch in response to the second parameter signal having a first value of the two possible values and deactivating the switch in response to the second parameter signal having a second value of the two possible values.

2. The method of claim 1, wherein converting the first parameter signal into the second parameter signal comprises:

comparing the first parameter signal to a reference signal to produce a comparison result; and

sampling the comparison result with a clock signal to generate the second parameter signal,

wherein the one value of the second parameter signal in each time interval corresponds to the comparison result when the clock signal last sampled the comparison result.

3. The method of claim 2, wherein the reference signal is an increasing signal having a decreasing slope.

4. The method of claim 1, wherein the first parameter signal is a digital signal having two or more bits and four or more possible values, and wherein converting the first parameter signal into the second parameter signal comprises converting the digital signal having two or more bits and four or more possible values into the second parameter signal having, during each time interval of a group of time intervals, one value out of only two possible values.

5. The method of claim 1, wherein the load comprises one or more inorganic and/or organic light emitting diodes, and wherein the parameter is a current flowing through at least a part of the load and/or light emitted by at least a part of the load.

6. A device for driving a load, comprising

a driver configured to drive the load,

a converter configured to convert a first parameter signal defining a parameter of the load into a second parameter signal, wherein the second parameter signal is a binary signal having, during each time interval of a group of time intervals, one value out of only two possible values, and

a digital controller configured to control the driver in response to the second parameter signal,

wherein the converter comprises:

a comparator configured to receive the first parameter signal and to receive a reference signal, to compare the first parameter signal to the reference signal, and in response to the comparison to output a comparison result; and

a timing circuit configured to receive a clock signal and the comparison result and to sample the comparison result in each clock period of the clock signal to generate the second parameter signal.

7. The device of claim 6, wherein the second parameter signal has a frequency equal to or less than a predefined maximum frequency.

8. The device of claim 6, wherein the load comprises one or more inorganic and/or organic light emitting diodes, and wherein the parameter is a current flowing through at least a part of the load and/or light emitted by at least a part of the load.

9. The device of claim 6, wherein the digital controller is configured to further control the driver in response to one or more user signals and/or one or more further parameter signals defining one or more further parameters of the load.

10. The device of claim 9, wherein the digital controller is one micro processor and/or one digital signal processor and/or one integrated circuit and/or one field programmable gate array and/or one complex programmable logic device and/or one personal computer and/or one programmable logic array, at least a part of the converter being an external circuit coupled to the digital controller or being an internal circuit forming part of the digital controller.

11. The device of claim 6, wherein the driver comprises a switch that is activated in response to the second parameter signal having a first value of the two possible values and that is deactivated in response to the second parameter signal having a second value of the two possible values.

12. The device of claim 11, wherein the driver is a buck converter or a boost converter or a buck boost converter or a fly back converter.

13. The device of claim 6, wherein the reference signal is an increasing signal having a decreasing slope.

14. A device for driving a load, comprising

a driver configured to drive the load,

a converter configured to convert a first parameter signal defining a parameter of the load into a second parameter signal, wherein the second parameter signal is a binary signal having, during each time interval of a group of time intervals, one value out of only two possible values, and

a digital controller configured to control the driver in response to the second parameter signal,

wherein the first parameter signal is a digital signal having two or more bits and four or more possible values, and wherein the converter is configured to convert the first parameter signal into the second parameter signal by converting the digital signal having two or more bits and four or more possible values into the second parameter signal having, during each time interval of a group of time intervals, one value out of only two possible values.