GB2519794A

GB2519794A - Dimming lighting apparatus

Info

Publication number: GB2519794A
Application number: GB1319190.3A
Authority: GB
Inventors: Wen Tao Kuang
Original assignee: KOSNIC UK Ltd
Current assignee: KOSNIC UK Ltd
Priority date: 2013-10-30
Filing date: 2013-10-30
Publication date: 2015-05-06
Also published as: GB201319190D0

Abstract

A lighting system comprises a control module 1, including a user operated switch 11 and a control circuit 12 connected to an AC power source, and a lighting apparatus 2, including a detection and control circuit 22 and a power supply 24 for an LED light source 25. In response to operation of the switch by a user, the control circuit provides a modified power supply signal to the lighting apparatus, including control instructions in the form of brief interruptions Tstop of the power source. The detection and control circuit samples the modified power supply signal and in response generates a pulse width modulated signal PWM. The power supply for the LED light source receives the pulse width modulated signal and supplies power to the LED light source at a level dependent on the duty cycle thereof.

Description

DIMMING LIGHTING APPARATUS

Description

A lighting system with solid state light source that comprises an operating console, also known as the switch board and a lighting apparatus that further comprises electrical control gear and solid state light source, wherein the AC power are fed to the lighting apparatus via the said switch board. With external operation, the switch board inserts a short stop period to the power supply. The stop period as a control signal is then detected and interpreted by the electronic control gear, which adjust light output, by varying the output current flowing through the solid state light source.

Background to the Invention

Most of the dimmer switches on the market are design to dim filament based lamp by varying the effective voltage. This is usually achieve using triac or thyristor to chop the sinusoidal waveform of the AC power source, reducing the conductive time of each cycle hence reducing the effective voltage. Unlike filament lamps, LED Lamps,luminaires with HF DC converter are nonlinear load which distorts the chopped wave form, results in unstable dimming effect. The dimming effect becomes worse when more LED Lamps/luminaires are added to the dimming switch.

Another dimming method commonly used for CFL and LED lamps is the so called switched dimming. Wherein the lamp dims to a different light level when a normal wall switch flips from "on" to "off" and back to "on" in a short period time. The dimming is achieved by the lamp's internal controlling circuit that detects "flips" at the switch and output various predefined driving cunent to the fluorescent tube/LED device accordingly. This sets the lamp to one of the a few predefined light levels. The method of dimming has disadvantages, a) The said lamp can only be set to a few predefined light level b)The said lamp under control is switched off and on every time when the lamp to set to a different level, causing disturbance to the user.

Detailed Description of Invention

This invention relates to unique circuit arrangement both at the operating console, known as the switch board as well as the lighting apparatus. Such arrangements overcome the disadvantages of both triac dimming and switched dimming as previously described.

According to an aspect of the invention there is provided a lighting system, comprising: a control module to receive user input and modify a power supply signal for the system on the basis of the input to provide a modified power supply signal including a control instruction portion; a detector to sample the modified power supply signal and generate a pulse width modulated (PWM) signal with a duty cycle selected in response to detection of a control instruction portion; and a power supply unit to supply a DC power supply signal to an LED load of the system at a value dependent on the duty cycle of the PWM signal.

The system may further comprise a rectifier to rectify the modified power supply signal prior to sampling by the detector.

The system may further comprise a secondary power supply for the system to provide a DC power supply in the event of an interruption in the power supply signals.

The detector may be operable to vary the duty cycle of the PWM signal.

The detector may be operable to vary the duty cycle between predetermined minimum and a maximum values.

The detector may be operable to vary the duty cycle cyclically.

The detector may be operable to vary the duty cycle continuously until further input is received at the control module.

The detector may be operable to maintain the duty cycle at a constant value.

A further aspect of the present invention provides a method for controlling the output of an LED lighting apparatus, comprising: modifying a power supply signal for the apparatus by including a control instruction portion in response to user input; generating a pulse width modulated (PWM) signal to control a DC power supply for an LED load of the apparatus with a duty cycle selected in response to detection of the control instruction portion; and supplying DC current to the LED load at a value proportional to the selected duty cycle.

The duty cycle may be varied cyclically between predetermined minimum and a maximum values.

The duty cycle may be maintained at a constant value.

The duty cycle may be varied until a control instruction portion is detected.

The confrol instruction portion may comprise an interruption of predefined duration in the power supply signal.

The method may further comprise providing a secondary power supply for the apparatus for providing a DC power supply for the apparatus in the event of an interruption in the power supply signal.

The control instruction portion may comprise multiple interruptions in or modifications to the power supply signal.

A further aspect provides a lighting system consists of an operating console and one or more lighting apparatus that are connected to the operating console, the AC power supplies to the lighting apparatus via the said operating console, characterized in that: a) the control instructions are sent form the operating console to the lighting apparatus via the power supply connection, using a stop pulse or combination of stop pulses that has predefined widths and amplitude modulated to the power supply. At the duration of the stop pulse, the power supply is either stopped or the amplitude being significantly reduced; and b) the lighting apparatus consist of means of detecting the stop pulse or combination of stop pulses and interpreting the control instruction; and c) the lighting apparatus consist of means of compensating the power losses during the stop pulses.

Different aspects and/or embodiments of the invention may be used separately or together.

Further particular and preferred aspects of the present invention are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with the features of the independent claims as appropriate, and in combination other than those explicitly set out in the claims.

The present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a functional block diagram of the operating console and lighting apparatus; and Figure 2 illustrates the functionality of the apparatus of Figure 1.

The operating console [1] consists of: a) a switch that is operated by user, generating control signal (i.e. a pulse) to the control circuit [12], b) a control circuit that connects to the AC power source. The AC cunent flows through the control circuit. Upon receiving the control signal from the switch [11], the control circuit insert a stop pulse with preclefined width the output of the control circuit connects to the light apparatus 121.

The lighting apparatus [2] consists of: a) rectifier that covert AC voltage to pulsating DC voltage, that connects to the other functional blocks as illustrated in the diagram; b) A electricity storage, a circuit arrangement that is charged during normal operation. It discharges during the duration of the stops pulse, providing power supply to functional blocks 1231 & [241; c) A one directional circuit [26] (e.g. diode) that sits between connection d and p of the detection and control circuit [22j. d) A detection and control circuit [22] that samples the output voltage of the rectifier via connection d. The power for the detection and control circuit are fed via connection p. when detecting the stop pulse, the detection and control circuit varies the duty cycle of the PWM signal connecting to the LED power supply [241; e) DC power supply that are configured to provide variable DC current to the LED load. The output current varies according to the duty cycle of the PWM signal received.

At the operating console, when the switch is operated by a user it generates a pulse signal that connects to the control circuit. If the pulse width is longer than a predefined time say 1 sec. it is regarded as a switch pule otherwise a dim pulse. The control circuit further consists of a microcontroller and a relay. When receMng the switch pulse, if the operating console is off, the microcontroller turns on the relay and allows AC current to flow to the lighting apparatus; otherwise it turns off the relay. When the control circuit receives a dim pulse, it inserts a stop pulse with predefined width to the AC power supply by turning the relay off and on.

At the lighting apparatus, the rectifier converts the input AC current to pulsating DC current that connects to connection d of the detection and control circuit, where there is a stop pulse, the electricity storage in the form of a RC circuit discharges, providing continuous dc supply the detection and control circuit, implemented as a microcontroller. The discharging current also supplies the LED power supply, so that the LEDs maintain th light level during the stop pulse.

The lighting apparatus controlled by the detection and control circuit may be in one of the two statuses: 1. Stable status: The detection and control circuit provide PWM signal with constant duty cycle. The PWM signal is fed to the LED power supply which output DC current that is proportional to the duty cycle of the PWM signal. As a result, the lighting apparatus has a stable and consistent light level.

2. Dimming status: The detection and control circuit provide varies the duty cycle of the PWM signal continuously in repetitive cycles, from minimum to maximum and maximum to minimum. This in turn changes current output of the LED power supply therefore the light output level changes continuously and repetitively.

When a stop pulse is detected by the detection and control circuit: -if the lighting apparatus is in stable status, it starts varying the duty cycle of the PWM signal, entering the light apparatus into dimming status. At this status the light output changes continuously and repetitively.

-if the lighting apparatus is in the dimming status, it stops varying the PWM signal's duty cycle, which stays at a consistent level. Subsequently the output current hence the light output of LEDs stays unchanged. In other words, the light apparatus enters stable status.

Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiments shown and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

Claims

CLAIMS1. A lighting system, comprising: a control module to receive user input and modify a power supply signal for the system on the basis of the input to provide a modified power supply signal including a control instruction portion; a detector to sample the modified power supply signal and generate a pulse width modulated (PWM) signal with a duty cycle selected in response to detection of a control instruction portion; and a power supply unit to supply a DC power supply signal to an LED load of the system at a value dependent on the duty cycle of the PWM signal.
2. A lighting system as claimed in claim 1, further comprising: a rectifier to rectify the modified power supply signal prior to sampling by the detector.
3. A lighting system as claimed in claim 1 or 2, further comprising; a secondary power supply for the system to provide a DC power supply in the event of an interruption in the power supply signals.
4. A lighting system as claimed in any of claims 1 to 3, wherein the detector is operable to vary the duty cycle of the PWM signal.
5. A lighting system as claimed in claim 4, wherein the detector is operable to vary the duty cycle between predetermined minimum and a maximum values.
6. A lighting system as claimed in claim 5, wherein the detector is operable to vary the duty cycle cyclically.
7. A lighting system as claimed in claim 5 or 6, wherein the detector is operable to vary the duty cycle continuously until further input is received at the control module.
8. A lighting system as claimed in claim 1, wherein the detector is operable to maintain the duty cycle at a constant value.
9. A method for controlling the output of an LED lighting apparatus, comprising: modifying a power supply signal for the apparatus by including a control instruction portion in response to user input; generating a pulse width modulated (PWM) signal to control a DC power supply for an LED load of the apparatus with a duty cycle selected in response to detection of the control instruction portion; and supplying DC current to the LED load at a value proportional to the selected duty cycle.
10. A method as claimed in claim 9, wherein the duty cycle is varied cyclically between predetermined minimum and a maximum values.
11. A method as claimed in claim 9, wherein the duty cycle is maintained at a constant value.
12. A method as claimed in claim 9 or 10, wherein the duty cycle is varied until a control instruction portion is detected.
13. A method as claimed in any of claims 9 to 12, wherein the control instruction portion comprises an interruption of predefined duration in the power supply signal.
14. A method as claimed in any of claims 9 to 13, further comprising: providing a secondary power supply for the apparatus for providing a DC power supply for the apparatus in the event of an interruption in the power supply signal.
15. A method as claimed in any of claims 9 to 14, wherein the control instruction portion comprises multiple interruptions in or modifications to the power supply signal.
16. A lighting system substantially as hereinbefore described with reference to, and as shown in, the accompanying drawing.
17. A method substantially as hereinbefore described with reference to, and as shown in, the accompanying drawing