A MANS-POWERED DEVICE AND DRIVE METHOD

Abstract

A mains-powered module and a driving method are provided, in which the voltage and/or frequency of received mains power is detected. A disabling circuit is used to disable a driver circuit if the mains power profile characteristics do not match those for which the module has been designed.

Claims

1. A mains-powered module for driving a load, comprising: an input for receiving mains power; a detection circuit for detecting the voltage and frequency of the mains power, thereby to determine a mains power profile wherein the determined mains power profile corresponds to a geographical region wherein the module is used; a driver circuit for driving the load, the driver circuit being adapted for use with a particular mains power profile which corresponds to a geographical region for which the driver is adapted to be used; and a disabling circuit for disabling the driver circuit if the determined mains power profile does not match the particular mains power profile.

2. A module as claimed in claim 1, comprising the load, wherein the load comprises a lighting element such as a high intensity discharge lamp or an LED arrangement, and the mains-powered module is a lighting module.

3. A module as claimed in claim 1, wherein the particular geographical region is one from a list which comprises at least the US and Europe and the determined geographical region is one from a list which comprises at least the US or Europe.

4. A module as claimed in claim 1, wherein the detection circuit comprises a frequency detector.

5. A module as claimed in claim 4, wherein a detected frequency below 55 Hz is a first determined mains power profile which corresponds to a first geographical region which includes Europe, and a detected frequency above 55 Hz is a second determined mains power profile which correspond to a second geographical region which includes the US.

6. A module as claimed in claim 1, wherein the detection circuit comprises a voltage detector.

7. A module as claimed in claim 6, wherein a detected voltage in the range from a first threshold which is greater than 120V to a second threshold which is below 277V is a first determined mains power profile which corresponds to a first geographical region which includes Europe and a detected voltage outside the range is a second determined mains power profile which corresponds to a second geographical region which includes the US.

8. A module as claimed in claim 1, wherein the disabling circuit comprises a processor or an analog circuit.

9. A module as claimed in claim 1, wherein the driver circuit comprises an EMI filter, a rectifier, and a driver output stage.

10. A method of controlling a mains-powered module, comprising: receiving mains power; detecting the voltage and frequency of the mains power, thereby to determine a mains power profile wherein the determined mains power profile corresponds to a geographical region wherein the module is used; controlling a driver circuit which is adapted for use with a particular mains power profile, which corresponds to a geographical region for which the driver is adapted to be used, by: powering a load if the determined mains power profile matches the particular mains power profile; and disabling the driver circuit if the determined mains power profile does not match the particular mains power profile.

11. A method as claimed in claim 10 for controlling a mains-powered lighting module, wherein powering a load comprises driving a current through a lighting element such as a high intensity discharge lamp or an LED arrangement.

12. A method as claimed in claim 10, comprising detecting a frequency below 55 Hz as a first determined mains power profile which corresponds to a first geographical region which includes Europe, and detecting a frequency above 55 Hz as a second determined mains power profile which correspond to a second geographical region which includes the US.

13. A method as claimed in claim 10, comprising detecting a voltage which is in a range from a first threshold which is greater than 120V to a second threshold which is below 277V as a first determined mains power profile which corresponds to a first geographical region which includes Europe, and detecting a voltage outside the range as a second determined mains power profile which corresponds to a second geographical region which includes the US.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Examples of the invention will now be described in detail with reference to the accompanying drawings, in which:

[0046] FIG. 1 shows a lighting module; and

[0047] FIG. 2 shows a method of driving a lighting module.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The invention provides a mains-powered module and a driving method, in which the voltage and/or frequency of received mains power is detected. A disabling circuit is used to disable a driver circuit if the mains power profile characteristics do not match those for which the module has been designed. The invention is of particular interest for lighting modules, although it can be applied to other mains-powered modules.

[0049] FIG. 1 shows a lighting system 10 which is powered by a mains supply 12. The lighting system comprises a rectifier 14 and EMI filtering stage 16. The rectified and filtered mains is provided to a lighting driver circuit 18. In the example shown, the driver comprises a power factor correction (PFC) stage 20, a buffer 22 and an output stage 24. The PFC stage is optional, or it could instead be integrated into a single stage driver. The output stage 24 drives a load in the form of a lighting element 26 such as a high intensity discharge lamp, an LED or an LED arrangement.

[0050] The driver circuit 18 is adapted for use with a particular mains power profile, such as a particular frequency and/or range of voltages. The mains power profile corresponds to a geographical region, such as Europe (and other regions with equivalent supply) or the US (and other regions with equivalent supply).

[0051] The other parts of the driver are also adapted for use with the particular mains profile. For example, standards associated with the different regions may dictate the use of different types of filtering and/or rectification, or indeed other aspects of the overall product design.

[0052] The system further comprises a detection circuit 28. In the example shown, there is a frequency detector 30 and a voltage detector 32.

[0053] The frequency detector 30 analyzes the mains input and/or the rectified mains signal in order to determine the frequency. It may operate with a threshold of between 50 Hz and 60 Hz so that 50 Hz regions can be distinguished from 60 Hz regions. For example, below 55 Hz is interpreted as a first determined mains power profile which corresponds to a first geographical region which includes Europe, and above 55 Hz is interpreted as a second determined mains power profile which correspond to a second geographical region which includes the US.

[0054] The voltage detector 32 also may analyze the mains input and/or the rectified mains signal in order to determine the mains voltage. A detected voltage in the range 120V to 277V is interpreted as a first determined mains power profile which corresponds to a first geographical region which includes Europe and a detected voltage outside the range is interpreted as a second determined mains power profile which corresponds to a second geographical region which includes the US. Thus, a voltage of 120V (or below) or 277V (or above) is interpreted as a US system voltage whereas a voltage between, e.g. close to 230V, is interpreted as a European system.

[0055] The voltage detection may be based on a first lower threshold, and a second higher threshold, together defining a voltage range. The thresholds are for example 150V and 270V so that the range 150V to 270V is for the European region, whereas below 150V or above 270V is for the US region.

[0056] The detection may instead take place after rectification but before filtering (shown as dotted lines in FIG. 1).

[0057] Note that the voltage levels are root mean square voltage values.

[0058] The system is in this way able to detect if it is being used in an area having a mains power profile for which it was designed (which is termed the “particular mains profile”). The system has a disabling circuit 34 for disabling the driver circuit 18 if the determined mains power profile does not match the particular mains power profile. The disabling circuit may be a digital processor or an analogue circuit.

[0059] In this way, region-specific, low cost module designs may be used, each for a dedicated geographical region (which may be a set of countries, for example), having a particular common mains power profile. The module disables its function when an inappropriate mains supply is detected. There may be one design for the US (and other regions with which the US design is compatible such as Canada) and another design for Europe (and other regions with which the European design is compatible). However, there may be more than two product designs so that more geographical regions may be covered, such as Japan.

[0060] The determined geographical region thus also comprises the US (or other areas with equivalent mains power profile) or Europe (or other areas with equivalent mains power profile).

[0061] The disabling circuit 34 for example comprises a processor which performs an enable or disable function. For example, it controls the operation of the PFC stage and/or the driver output stage.

[0062] It may interface with any part of the circuitry in order to prevent operation of the lighting element 26 but remain in a safe condition. There may be a dedicated disable switch in addition to the normal driver circuitry, or the disabling circuit may interface with the normal driver circuitry.

[0063] FIG. 2 shows a method of controlling a mains-powered lighting module. In step 40, mains power is received. In step 42, the voltage and/or frequency of the mains power is detected, thereby to determine a mains power profile.

[0064] In step 44 it is determined whether or not the determined mains power profile matches a particular mains power profile for which the lighting module is designed.

[0065] In step 46 a current is driven through a lighting element of the module if the determined mains power profile matches the particular mains power profile.

[0066] In step 48 the driver circuit is disabled if the determined mains power profile does not match the particular mains power profile.

[0067] This method actively disables a module when it is being used with a mains power profile for which it has not been designed, and therefore does not necessarily meet local standards.

[0068] As mentioned above, the detection of the mains power profile may be based on voltage measurement or frequency measurement or both.

[0069] Circuitry for implementing the required detection is well known, for example within universal mains devices, which instead control the circuit operation in dependence on the detected mains power profile.

[0070] Frequency detection can be performed based on detecting zero crossings of the mains voltage and by measuring the time difference between two consecutive zero-crossing. Other frequency detection methods are available, for example by using band pass filters or low pass and high pass filters. Frequency detection based on a current flowing through a reactive component is also possible

[0071] A comparator with a known reference voltage can be used for voltage detection, based on expected ranges of voltages to be received in different systems.

[0072] The idea may be used in any lamp design and is not limited to high intensity discharge lamps or to LED technology.

[0073] Furthermore, the invention is not limited to lighting modules. Any low-cost mass produced module may have different versions for different regions. An example is a mobile phone charger, for which the mobile phone functions as the load. There are of course many other examples of power adaptor (i.e. mains to DC converters) which may be disabled when not connected to the appropriate supply.

[0074] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.