AU2005100501A4

AU2005100501A4 - LED lighting

Info

Publication number: AU2005100501A4
Application number: AU2005100501A
Authority: AU
Inventors: Dongning Zhang
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-06-19
Filing date: 2005-06-19
Publication date: 2005-07-14
Anticipated expiration: 2013-06-19

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT LED LIGHTING The following statement is a full description of this invention, including the best method of performing it known to me: LED LIGHTING SLED has high lighting efficiency. But the traditional LED circuit did not make full use of the total energy efficiency. The single LED has little power output. But thousands of the LEDs will light up a dark world. LED light also a colourful world. Technically, one thousand 3 normal small white LEDs consume only 60watts electrical power.

A LED light set in accordance with this invention comprises at least A- a LED series, and a LED current regulated switch mode DC power supply which output voltage may vary as a control result of the LED working current. And the LED light set may supply more optional similar LED series and regulate the individual working current of the LED series.

LED has constant voltage feature in normal working condition. But the constant voltage may affect by many issues: unit variation, current/voltage relation, working temperature and aging. The single LED voltage variation is small. But many LEDs in series may have big difference. Even two LEDs in direct parallel, their working current can be quite different.

The existing LED application normally uses a resistor in series with one or more LEDs and supplied by a regulated or unregulated voltage source or batteries. Some products even don't use the resistor and drive the LED by the batteries directly. Quite many white LED torches use 3 small button batteries (nominal 4.5V) drive the 3.3V LED directly. When the batteries are new, the LED draws excessive current and generates unnecessary heat in the LED. This reduces the lifetime of both batteries and LEDs. The better products use a series resistor to regulate the LED current. This may reduce the system efficiency too, especially when the batteries are new and good. Another problem of the torches with either non-resistor or resistor is that the light output (LED current) will reduce when the batteries are partially used.

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SThe LED lighting suits for many illumination applications, all battery Soperated light source like torch, bicycle light, automotive lamp, mining outdoor working light and safety light, emergency light, home office light, decoration light, etc. This invention is only for the application of the LED current regulated switch mode DC power supply to drive a LED series and more optional LED series.

SThe invention may be better understood with reference to the D illustration of embodiment of the invention which:- Figure 1 is a concept circuit of two batteries (2.4Volts rechargeable or 3V normal battery) operated working light.

Figure 2 is a concept circuit of PFC (Power Factor Correction) LED lighting and power supply system.

Figure 3 is a concept emergency LED lighting scheme as an expansion of Figure 2.

In Figure 1, MOSFET1, INDUCTOR and DIODE are worked as a boost converter to generate higher DC voltage in CAP and then to supply LED01, LED02, LEDOn and LED11, LED12, LEDln and LEDml, LEDm2, LEDmn. The LED current of the LED01, LED02 and LEDOn is regulated directly by the Control Logic. The DC voltage on CAP is just a control result of the LED current. The other LED series with same LED number and supplied by the same DC voltage may have same working current regulated by the individual current regulation circuit, the simply example like R1 and Rm in the LED series. The light output may be dimmed by the Dimming Control input to reduce the LED working current. The CAP voltage may be limited by the Control Logic for system safety, which is not showing in the Figure 1. The battery polarity protection is also important for system reliability, which is not showing in the Figure 1.

The actual circuit of the Figure 1 has 90% electrical efficiency at nominal 2.4V battery voltage and much higher lighting efficiency 3

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Sdue to the LED may always work under proper working current. The S LED will keep constant light output when the battery voltage is still Shigher than a certain voltage (for example: 1.8 Volts). The end working voltage can be setup to protect the rechargeable battery or the LED output may be reduced to extend the battery working hours.

More LED series can be added to the system as required. In D practical, 2 AA size batteries (2100mAH) may deliver 2Watts power Sfor 2.5 hours, which may suit for drive about 30 small white LEDs.

D The light output can be adjusted easily by control the LED working current. The LED current in different series are very similar while dimming due to the LED voltage is automatically regulated and all LEDs have similar working condition.

In Figure 2, L1, Q1, D1 and C2 with the PFC Control Logic work as a basic PFC scheme. The switch mode PFC circuit is very efficient in generating a high DC output voltage. For 240Vac input, the high DC voltage is normally 400 to 450 Volts. For 11 OVac input, the high DC voltage can be 200 to 450 Volts. The LED series may work very efficiently with this high DC voltage source. The PFC circuit is LED current directly controlled. The DC voltage is a control result of the working current in LEDsi (LEDsl, LEDs2,... LEDsl). The DC Output Voltage feedback to PFC Control Logic is only for system protection.

More LED series (LEDai, LEDbi,...LEDxi in Figure 2) can be added to the system. MOSFET (or transistors) Q2, Q3, Qx and resistors Rcs2, Rcs3, Rcsx are used as the active current regulators under the control of Active Current Regulation and Safety Logic. LEDsi will decide the DC voltage value. The minimum working voltage of LEDsi should be higher than the maximum peak AC input voltage.

LEDai, LEDbi, LEDxi should have less or equal working voltage like LEDsi. Different LED series may have different working current.

The system may be monitored or controlled through DALI (Digital Addressable Lighting Interface) or other simple control methods.

In Figure 3, the backup batteries (BATT) and a relay (RLY) are added in the system for emergency or camping light. The backup batteries are charged with the PFC supplementary circuit while the AC power is normal. When the PFC Emergency Control Logic detects a power failure, RLY will switch on the batteries to supply the system. The same switch mode PFC circuit L1, Q1, D1, C2 and 3 the PFC Emergency Control Logic may work on either AC or batteries inputs.

Figure 2 may be used for a decoration colour light. The lighting colour is generated by the three primary colours from different Red, Green and Blue LED series. The RGB lights are controlled by the RGB LEDs currents. The lighting colour may be adjusted from a remote computer or a control panel. Each LED series may have its own current control. Many different RGB groups may create multi colours in the same time.

Claims

2. A LED light set as claimed in claim 1 has more adding LED series and the LED series are supplied by the LED current regulated switch mode DC power supply, and the LED light set has individual active current regulation circuit for each adding LED series and individual status detection for any LED series being engaged to or disconnected from the LED light set safely.
3. A LED light set as claimed in claim 1 and claim 2 has a LED current regulated switch mode PFC (Power Factor Correction) DC power supply for AC input application.
4. A LED light set as claimed in claim 1 and claim 3 has a PFC supplementary circuit for charging a backup battery and the LED current regulated switch mode PFC (Power Factor Correction) DC power supply may work on either AC or the backup battery DC input. A LED light set substantially as herein before described with reference to the description and/or the accompanying drawings. DONGNING ZHANG 19 June 2005