GB2499684A

GB2499684A - PFM-based LED illuminator and light network

Info

Publication number: GB2499684A
Application number: GB1211200.9A
Authority: GB
Inventors: Zhaowei Zhen
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-02-23
Filing date: 2012-06-25
Publication date: 2013-08-28
Also published as: CN202587472U; GB201211200D0

Abstract

A pulse frequency modulation (PFM) based LED illuminator includes a plurality of light sources 210, 220, 230 of at least two colours. The light sources are coupled to a power circuit which includes a power supply 100, a driver 510 for driving the light sources to emit light, and a controller 500. The controller has a variable address for identifying the illuminator and responds to an input signal addressed to the controller. The controller is used for generating PFM signals which correspond to individual colours of the plurality of light sources. A plurality of such illuminators may be used in a light network having a central controller operating on the DMX standard.

Description

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PFM-based LED illuminator and light network thereof

The invention relates to the field of illumination.

At present, with the continuous development of LED industry and the constant innovation of LED control mode, large quantities of various LED products are brought to market, more stringent requirements are proposed for the LED control mode, and the brightness control of the currently used monochromatic LED already cannot satisfy the demands of the people. In order to meet the user demands, using colour LED technology of mixed light of more than one monochromatic LED has become an important topic in the development of LED industry. But in order to gain the mixed light of LEDs which is more gorgeous in colour and more ideal in colour light emitting, more requirements for strictness and precis eness are put forward for light emitting control of each of the monochromatic LEDs in the colour LEDs. At present, a light mixing method and apparatus of multi-colour LEDs are disclosed by MUELLER.G in European Patent EP1016062B1. Mainly a PWM (Pulse Width Modulation) scheme is adopted to control the colour of mixed light of the LEDs. The PWM control is simple and flexible and has many advantages in the LED field. But in some cases, the PWM is not a best choice for LED control, for example, in case of light load and low current, the PFM is more efficient than PWM.

An embodiment seeks to provide an improved illuminator and a light network thereof.

There is disclosed an illuminator comprising a plurality of LED light sources of at least two colours, coupled to a power supply circuit, a driver, and a controller, the driver being configured to drive the light sources to emit light and comprising at least two switches connected respectively with the light

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sources, whereby in use the power supply circuit provides a different current path for each of the LED light sources; the controller having a variable address for identifying itself and responding to an input signal assigned to the controller; the data flow being assigned to the controller for describing the characteristic of each of the LED light sources for generating plural of PFM signals, each of which corresponds to an individual colour of the various colours of the LEDs, wherein each of the PFM signals instructs an independent switch to be on and off according to a specific and relevant frequency, wherein the data flow includes a plurality of data for at least two LED colours.

The embodiments adopts the PFM scheme to control the mixed light of the LED light sources, wherein the PFM is a technology for realizing stable voltage output by regulating pulse frequency, and the pulse width of the PFM is fixed while the internal vibration frequency is changing; the PWM is of controlling signal output by using wave pulse width and is of a change in frequency size, while the PFM is of a change of frequency existence and is more efficient than PWM in case of light load and low current.

The controller may include at least two memories configured for the LEDs for at least two colours; these memories are used for storing data values of the data flows; the controller determines pulse frequency of each of the LEDs for different colours by using these data to define the colour of each of the LEDs; and the controller sends corresponding PFM signals to the LEDs for different colours in the light sources according to the received data and the stored data in the memories so as to control each of the LEDs for different colours in the light sources.

The light sources may include a red LED, a green LED and a blue LED which are connected with the power supply and the driver respectively; the driver is provided with a first switch, a second switch and a third switch which

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are corresponding to the red LED, the green LED and the blue LED and are used for controlling the red LED, the green LED and the blue LED to emit light respectively; the controller includes an address interface for receiving an external DMX512 light control signal; the controller sends PFM control signals to the first switch, the second switch and the third switch in the driver respectively according to the received DMX512 signal; each of the PFM signals instructs the switch corresponding to the PFM signal; and the switch is on and off according to the frequency of the PFM signal output by the controller to control the light sources for at least two colours to emit light so as to realize the aim of regulating the colour and brightness of the light sources.

The controller may include a storage control module, a storage module, a decoding module for receiving and decoding the external DMX512 address control signal, and a PFM control module for generating the PFM control signal, wherein the decoding module is used for receiving and decoding the external DMX512 address information; the storage control module and the storage module are used for storing part of data values of the decoded data flows; and the PFM control module sends pulse frequency signals of the LEDs for different colours to the first switch, the second switch and the third switch in the driver respectively according to these data values to control the light emitting situations of the red LED, the green LED and the blue LED in the light sources so as to accurately control the colours of the light sources.

The illuminator may include a housing for enclosing the LED, the driver and the controller; and this design not only can reduce the volume of the illuminator but also has high integrity and better effect of light emitting.

The illuminator may include a current regulator for regulating the value of the current supplied to the LED to be a maximum current value so as to maintain the constant maximum value of the maximum current all the time; and

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the current regulator is used for controlling the current of each of the LEDs for different colours in the light sources and regulating the current supplies of the LEDs to be the constant maximum value to ensure the light emitting effects of the light sources.

The illuminator may include a current regulator for controlling the current supplied to the LED through the current path to be the maximum value so as to maintain the constant maximum value of the maximum current all the time; the housing also encloses the current regulator in addition to the LED, the driver and the controller; and the current regulator is arranged in the housing, so that the illuminator can be further improved in integrity and has better practicality.

The LEDs may be organic LEDs which are not only more environment-friendly and low in production cost but also helpful for reducing the weight of the illuminator.

Further, the controller may be in charge of identifying and responding to the data flow; the data recited here is in full accordance with the DMX (Direct Memory Exchange) data format; and by using the format in full accordance with the DMX data the development cost can be reduced and the response speed can be faster and the control effect can be better.

Further, each part of the input data flow may be provided with an independent byte for each of the LEDs, which has 8-bit, so that levels for controlling the LED colours are in a range from 0 to 255; the controller controls pulse frequency of each PFM according to content of the bits of each independent byte; because the levels of the LED colours can be set from 0 to 225 in brightness according to the 8-bit byte, the colours of the light sources can be further increased, so that more LED colours can be produced to realize better light emitting effect.

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Further, the LEDs may include three types of LEDS for red, green and blue; the LEDs for red, green and blue have good effect in light-mixing; different colours can be produced by regulating the internal LEDs; and the LEDs are more convenient for control.

Further, the connection mode of the LEDs may include serial connection or parallel connection.

Further, the storage control module may be also connected with a control memory for caching, resetting, controlling and timing; the control memory ry outputs a timing and resetting signal to the controller in an I C transmission scheme, so that the stability of the invention is improved; and the control memory is implemented as an AT24C02 control integrated chip.

Further, the LED illuminator may also includes an input communication interface module for receiving a control signal from the outside and an output communication interface module for outputting a control signal to the outside; the input communication interface module and the output communication interface module are connected with the controller, wherein the input communication interface module is connected with an input connection interface and the decoding module respectively and is used for transmitting the DMX512 address control signal to the controller; and the output communication interface module is connected with the controller and the output connection interface respectively and is used for outputting a control address signal to the illuminator at next stage.

Preferably, both the input communication interface module and the output communication interface module may be implemented as MAX485 interface chips.

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Further, the voltage circuit may also include a voltage stabilization module for providing a stable (5V) power supply for the input communication interface module; and the voltage stabilization module is connected with the power supply and the input communication interface module respectively; and the voltage stabilization module is implemented as a 78M05 voltage stabilization chip.

A light network applying the illuminator includes a central controller for generating an input data stream and a plurality of LED illuminators based on PFM, wherein each of the illuminators is used for receiving the data flow and responding to different parts of the input data flow by using different configurations of its variable address.

The invention has the beneficial effects that: the PFM-based LED illuminator and the light network thereof adopted by the invention perform the light mixing process by using a variety of light sources for at least two colours; the light sources for at least two colours have current paths respectively and are controlled by the driver; the driver includes at least two switches corresponding to the light sources; the switches are used for controlling the light sources corresponding to them; the controller send multiple groups of PFM control signals to the driver according to the received address information and the control information; each group of the PFM control signals control the switches in the driver and the light sources connected with the switches so as to control the multiple light sources; the mode of mixing lights from the light sources is controlled so as to accurately regulate the colour and brightness of the colour LED illuminator; and in case of light load and low current, the efficiency by PFM control driver is higher than those by PWM.

In the drawing, Figure 1 is a block diagram of an embodiment of an

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illuminator.

As shown in Figure 1, an illuminator includes: three light sources (210-230) for plural colours, which are coupled to a power supply circuit including a power supply (100), a conventional reference voltage (490); a driver circuit (510), and a controller (500).

The driver circuit is used for driving the light sources to emit light and is composed of switches (640,650,660) in the same number as the light sources (210-230). The power supply circuit provides different current paths for each of the light sources. The controller (500) has a variable address for identifying the illuminator itself arid responds to an input signal assigned to the controller (500) to which the data flow is assigned for describing the characteristic of each of the light sources and is used for generating a variety of PFM signals, each of which corresponds to an individual colour of the various colours of the light sources. Each of the PFM signals instructs an independent switch to be on and off according to a specific and relevant frequency. The data flow includes a variety of data for at least two light source colours. In this embodiment the light sources are LEDS; in other arrangements other light sources may be employed.

The invention adopts the PFM scheme to control the mixed light of the LED light sources. PFM is a technology for realizing stable voltage output by regulating pulse frequency, and the pulse width of the PFM is fixed while the frequency is changing. By contrast, PWM controls signal output by using wave pulse width and is of a change in frequency size (i.e. wider or narrower). PFM uses change of frequency existence (i.e. Yes or No) and is more efficient than PWM in case of light load and low current.

The controller (500) includes one memory area configured for each of the

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LEDs for at least two colours. Alternatively separate memories may be provided. The memory areas or memories are used for storing data values of the data flows. The controller (500) sets the pulse frequency of each of the LEDs for different colours by using the data values to define the colour or brightness of each of the LEDs. And the controller (500) sends corresponding PFM signals to the LEDs for different colours in the light sources according to the received data and the stored data in the memories so as to control each of the LEDs for different colours in the light sources.

In this embodiment the light sources include a red LED (210), a green LED (220) and a blue LED (230) which are connected with the power supply (100) and the driver (510) respectively. The driver (510) has a first switch (640), a second switch (650) and a third switch (660) corresponding to the red LED (210), the green LED (220) and the blue LED 230 used for controlling the red LED (210), the green LED (220) and the blue LED (230) to emit light respectively. The controller (500) includes an address interface for receiving an external DMX512 light control signal, and sends respectively PFM control signals to the first switch (640), the second switch (650) and the third switch (660) in the driver (510) according to the received DMX512 signal. Each of the PFM signals instructs the switch corresponding to the PFM signal, and the switch is on and off at the frequency of the PFM signal output by the controller (500) to control the light sources to emit light, so as to realize the aim of regulating the colour and brightness of the light sources.

In this embodiment, the controller (500) includes a memory control module (600), a memory module (610), a decoding module (620) for receiving and decoding the external DMX512 light control signal, and a PFM control module (630) for generating the PFM control signal. The decoding module (620) is used for receiving and decoding the external DMX512 address information. The memory control module (600) and the memory module (610) are used for

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storing part of data values of the decoded data flows. The PFM control module (630) sends pulse frequency signals for the LEDs for different colours to the first switch (640), the second switch (650) and the third switch (660) in the driver (510) respectively according to these data values to control the light emitting situations of the red LED (210), the green LED (220) and the blue LED (230) in the light sources, so as to accurately control the colours of the light sources.

In this embodiment, the LED illuminator also includes a housing for enclosing the LEDs, the driver (510) and the controller (500). This design not only can reduce the size of the illuminator but also has high integrity and better effect of light emitting.

In this embodiment, the LED illuminator also includes a current regulator for regulating the value of the current supplied to the LED to be a maximum current value so as to maintain the constant maximum value of the maximum current all the time. The current regulator is used for controlling the current of each of the LEDs for different colours in the light sources and regulating the current supplies of the LEDs to be the constant maximum value to ensure the light emitting effects of the light sources.

In this embodiment, the LED illuminator also includes a current regulator for controlling the current supplied to the LED through the current path to be the maximum value so as to maintain the constant maximum value of the maximum current all the time. The housing also encloses the current regulator in addition to the LED, the driver (510) and the controller (500). And because the current regulator is arranged in the housing, the illuminator is improved in integrity and has better practicality.

In this embodiment, the LED is an organic LED, which is not only more

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environment-friendly and low in production cost but also helpful for reducing the weight of the illuminator.

In this embodiment, the controller (500) is in charge of identifying and responding to the data flow which is in full accordance with the DMX (Direct Memory Exchange) data format. And by using the format in full accordance with the DMX data, the development cost can be reduced, the response speed can be faster and the control effect can be better.

In this embodiment, each part of the input data flow is provided with an independent byte for each of the LEDs, which has 8-bits, so that levels for controlling the LED colours are in a range from 0 to 255. The controller (500) controls pulse frequency of each PFM according to content of the bits of each independent byte. Because the levels of the LED colours can be set from 0 to 225 in brightness according to the 8-bit byte, the colours of the light sources can be further increased, so that more LED colours can be produced to realize better light emitting effect.

In this embodiment, the LEDs include three types of LEDs for red, green and blue; the LEDs for red, green and blue colours have good effect in light-mixing; different colours can be produced by regulating the internal LEDs; and the LEDs are more convenient for control.

In this embodiment, the connection mode of the light sources is parallel. In other embodiments the light sources are in series.

In this embodiment, the memory control module (600) is also connected with a control memory (400) for caching, resetting, controlling and timing. The control memory (400) outputs a timing and resetting signal to the controller p00) in an I C transmission scheme, so that the stability of the invention is

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improved; and the control memory (400) is implemented as an AT24C02 control integrated chip.

In this embodiment, the LED illuminator also includes an input communication interface module (410) for receiving a control signal from the outside and an output communication interface module (420) for outputting a control signal to the outside; the input communication interface module (410) and the output communication interface module (420) are connected with the controller (500), wherein the input communication interface module (410) is connected with an input connection interface (430) and the decoding module (620) respectively and is used for transmitting the DMX512 address control signal to the controller (500); and the output communication interface module (420) is connected with the controller (500) and the output connection interface (440) respectively and is used for outputting a control address signal to the illuminator at next stage.

In this embodiment, both the input communication interface module (410) and the output communication interface module (420) are implemented as MAX485 interface chips.

In this embodiment, the voltage circuit also includes a voltage stabilization module (110) for providing a stable 5 V power supply for the input communication interface module (410). The voltage stabilization module 110 is connected with the power supply (100) and the input communication interface module (410) respectively. The voltage stabilization module (110) is implemented as a 78M05 voltage stabilization chip.

A light network applying the illuminator includes a central controller for generating an input data stream and a plurality of the LED illuminators based on PFM, wherein each of the illuminators is used for receiving the data flow

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and responding to different parts of the input data flow by using different configuration of its variable address.

The invention is not restricted to the specific features of the described embodiment but extends to the full scope of the appended claims.

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Claims

1. An illuminator comprising a plurality of LED light sources of at least two colours, coupled to a power supply circuit, a driver, and a controller,

the driver being configured to drive the light sources to emit light and comprising at least two switches connected respectively with the light sources, whereby in use the power supply circuit provides a different current path for each of the LED light sources;

the controller having a variable address for identifying itself and responding to an input signal assigned to the controller; the data flow being assigned to the controller for describing the characteristic of each of the LED light sources for generating plural of PFM signals, each of which corresponds to an individual colour of the various colours of the LEDs, wherein each of the PFM signals instructs an independent switch to be on and off according to a specific and relevant frequency, wherein the data flow includes a plurality of data for at least two LED colours.

2. An illuminator according to claim 1, wherein the controller includes at least two memories configured for the LEDs; the memories in use storing data values of the data flows; and the controller determining a pulse frequency of each of the LEDs by using said data to define the colour of each of the LEDs.

3. An illuminator according to claim 1, wherein the illuminator includes a housing for enclosing the LED, the driver and the controller.

4. An illuminator according to claim 1, wherein the illuminator includes a current regulator for regulating the value of the current supplied to the LED to be a maximum current value so as to maintain the constant maximum value of

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the maximum current all the time.

5. An illuminator according to any of claims 1 to 4, wherein each LED is an organic LED.

6. An illuminator according any one of claims 1 to 4, wherein the controller is configured to identify and respond to the data flow; and the said data is in full accordance with the DMX (Direct Memory Exchange) data format.

7. An illuminator according any one of claims 1 to 4, wherein each part of the input data flow is provided with an independent byte for each of the LEDs, which has 8-bits, so that levels for controlling the LED colours are in a range from 0 to 255; and the controller controls pulse frequency of each PFM according to content of the bits of each independent byte.

8. An illuminator according any one of claims 1 to 4, wherein the LEDs include red, green and blue LEDs.

9. An illuminator according any one of claims 1 to 4, wherein the connection mode of the LEDs includes serial connection or parallel connection.

10. A light network having a central controller for generating an input data stream and a plurality of LED illuminators based on PFM, wherein each of the illuminators is used for receiving the data flow and responding to different parts of the input data flow by using different configuration of its variable address.