WO2004100611A1

WO2004100611A1 - Led lighting module and system

Info

Publication number: WO2004100611A1
Application number: PCT/CH2004/000272
Authority: WO
Inventors: Stephan Rosenberger; Heiner Kromer
Original assignee: Ilumera Group Ag
Priority date: 2003-05-06
Filing date: 2004-05-05
Publication date: 2004-11-18

Abstract

The invention is directed to a LED Lighting module system (10, 20) for precise color output control. The LED lighting module (10, 20) comprises multiple LEDs (14) having each a different visible light spectra. An optical lens system (11) is provided to direct and transfer radiated light from the LEDs (14) to a desired target and a color mixer (13) is provided to mix color light output of the LEDs (14).

Description

LED LIGHTING MODULE AND SYSTEM

BACKGROUND OF THE INVENTION

The present invention relates generally to lighting sources, and relates more particularly to 5 light sources using LED modules.

A further aspect of the present invention is generally related to transmitting and altering light through fiber optic media, and is related particularly to mixing LED light through a fiber optic light driver to produce a homogeneous light output.

i o DESCRIPTION OF RELATED ART

Light sources have been used for years that are based on incandescent lamps that supply light by heating a filament in a vacuum. It is possible to operate an incandescent lamp to provide different color light output for specific lighting applications. However, when used as a light source, especially over a long period of time, incandescent lamps consume a great 15 deal of energy and produce a large amount of heat, making the incandescent lamp inefficient for long term use as a variable type light source. When a color output of an incandescent lamp is modified, the lamp often becomes much more inefficient than when operated under standard conditions.

Gas discharge lamps, including fluorescent lamps, produce light by increasing the energy 20 levels of atoms of a substance capable of emitting photons. Accordingly, gas discharge lamps have a fixed spectral output chart with regard to the type of light that can be obtained.

A variable light output is desirable for a number of lighting applications, particularly in terms of setting specific characteristics for the light source. For example, it is useful to con-

5 trol a light source that is capable of generating multiple visible light spectra, which can be expressed in terms of correlated color temperature (CCT). Another parameter desirable to control in variable light applications is a color rendering index (CRI) to produce particular types of lighting effects visible to the human eye. In addition, it is useful to express multiple visible light spectra in terms of the output coordinates on a CIE (Commission International

T O de I'Eclairage) chromaticity diagram.

A useful aspect of measuring and quantifying light output pertains to chromaticity levels and luminous flux. In terms of white light output, a number of variables including lumen strength and movement along the black body curve for chromaticity levels are useful in specifying or determining particular light output. The black body curve is a line on a chro- 15 maticity diagram along which variable lumen strengths of white light are obtained. The black body curve is expressed in terms of degrees Kelvin and is drawn from a theoretical device such as a black body radiator. Practical light sources can be described in terms of CCT, also in degrees Kelvin. In the production of white light levels, it would be useful to express a desired output in terms of CCT along the black body curve.

20 As discussed above, incandescent lamps can be made to produce multiple visible light spectra, however, these lamps operate only with poor efficiency. The gas discharge lamps discussed above are unable to produce multiple visible light spectra, and therefore are not useful for variable light output applications. It is possible to produce a variable, multiple visible light spectra output using LED based lamps as a light source. However, it is often difficult to appropriately control the operational parameters of LEDs to produce high quality, variable light output, with multiple visible light spectra.

A further aspect of the present invention is related to transmitting and altering light through fiber optic media, particularly to mixing LED light through a fiber optic light driver to produce a homogeneous light output. In LED lighting applications, it is desirable to produce variable types of lighting that can range in color and intensity through the use of LED light output However, because LED light output is derived from discrete LED elements, LED lighting applications typically suffer from somewhat patchy or unmixed color and intensity light output. Various solutions have been proposed to overcome this difficulty, including lensing and optical coatings that diffuse light output from an LED and combine diffused light output from several LEDs to produce a mixed color output that can vary with intensity. However, these solutions typically have, depending on the field of application, a relatively low light output efficiency. Accordingly, it would be desirable to produce a well mixed color light output driven by LEDs that obtains an improved output efficiency.

SUMMARY OF THE INVENTION

In accordance with the present invention, a multiple visible light spectra light source is pro- vided with LED light. The LED light source provides advantages in terms of increased efficiency of light output and variable operational parameters to permit targeted color production through the use of multiple visible light spectra that can be controlled according a desired CCT, CRI and coordinate in the C1E chromoticity diagram. The LED light source system preferably is arranged in a module that can be precisely controlled in terms of voltage and current. The precise control of the module permits a targeted color output to be produced, while the efficiency of the operation of the module is optimized for the selected color output. That is, using the modular system with precise control, the light output of the module can be optimized for any coordinate in the CIE chromoticity diagram, while providing free movement along the black body curve for any selected CCT. In addition, the module can be controlled to achieve an optimized CRI in any selected color output. Modular design also permits modular combination and clustering to allow free form connectivity and illumination designs to achieve a particular luminance that is significantly improved over that produced in incandescent or gas discharge lamps.

The precise color output control for each module of the LED light source is achieved with multiple LEDs on each module, with each of the LEDs having a different visible light spectra. By controlling the power supply to the various LEDs, any multiple spectra visible light can be produced.

For example, the LED module can be set to output a light level in accord with a selected CCT or a coordinate in the CIE chromoticity diagram. An algorithm for controlling the LEDs to provide the set light output calculates appropriate electrical inputs to each LED to obtain the desired light level and quality. In addition, the algorithm obtains optimized luminance performance give the circuit parameters and the desired light output. For example, with any selected color output, the current and voltage to each of the LEDs is controlled to optimize the CRI and luminance of the module to produce maximum efficiency light output.

Each module preferably has a closed loop temperature control system so that LED junction temperatures can be measured, and the LEDs can be controlled to keep the lowest possible temperature output for the selected operating point. This closed loop temperature control operation increases the life span of the LEDs to permit an entire module to have a maximum life span. The module itself is constructed to have excellent thermal performance and take advantage of natural convection. Each module preferably employs heat transfer technology that can include one or more of, for example, a heat pipe, specialized heat sinks and particu- lar heat transfer materials to further improve thermal performance. In addition, each module is constructed to have a small footprint so that the number of modules can be arrayed together while maintaining appropriate heat dissipation for the arrayed modules.

In addition to temperature feedback and closed loop control, a light sensor is preferably provided to obtain lumen feedback for precise light level control. The lumen sensor can sup- ply a variable feedback representative of light level or light quality or can be a discrete level sensor that provides a signal for a particular lighting level, for example.

Each LED module is equipped with an optical lens system or an equivalent mean to maximize LED luminance output. The optical lens is constructed to maximize the light transfer from the LED source to the desired target, rather than maintain optical precision or image transfer. The luminance output produced with the optical lens is highly efficient, and transfers an optimized light radiation from the LEDs.

The modular system for the LED light source preferably permits connectivity between each module in four directions. That is, a number of modules can be joined side-to-side and derive appropriate power, control and heat transfer individually or through each other. Accordingly, light systems can be constructed in a modular array according to a desired application.

Each LED module connection with another module can include a control connection in the form of a bus interface. That is, the interjoined LED modules can share a single bus system for control and power purposes. The bus system preferably is capable of addressing one or more modules to provide selective individual or grouped lighting effects. The interjoined modules can indirectly communicate with popular commercial protocols to interact with external devices on a locale and remote basis.

The modules can be formed as a network of interconnected and individually addressable components. The module interconnectivity permits the use of a user interface for program- ming and controlling the various modules individually or as groups. A connection to any particular set of modules can be provided from a computer to permit real time control and status feedback. In addition, the modular system can be controlled programmatically, such as by setting particular light output scenarios and given times for sequences. Programmable changes in visible light character or intensity can be achieved through the user interface with simple and intuitive controls to permit ease of use and simplicity in programming. A software system permits the user interface to be flexible and user friendly while continuing to achieve algorithmic optimization of lighting output characteristics for each module and each LED on a module. For example, the user interface can be a PDA, PC, tablet or remote control. A Java based software structure is used to permit many different systems and user interfaces to interact with the LED lighting systems.

The LED module preferably is constructed with a printed circuit board (PCB) composed of heat sinking material that is advantageous for producing high thermal conductivity. The PCB board preferably is arranged in an aluminum sandwich construction to provide low resistance, high speed and good thermal conductivity properties. The PCB board supports precision resistors that can be trimmed for individual LED compensation. The resistors can be composed of thick film and thin film type structures, and trimmed with a laser, for example. By appropriately trimming the resistors on the PCB board, adjustments can be made to the operating characteristics of the circuit that includes individual LEDs, to permit precise control of LED parameters and temperature compensation. The LED module optical lens preferably is provided with a color mixing material through which the LED light is projected. The color mixing material contains, for example, a micro- structure in an acrylic material to improve color mixing performance and obtain high luminance efficiency output. The color mixing material can also be supplied as a holographic coating on the module lens to again improve luminance output efficiency while obtaining appropriate color mixing performance.

The LED module cooling system can, in addition or alternative to being composed of a heat pipe, heat sink and material with good thermal conductivity, also be provided as a mesh or braid of copper wires. By providing the cooling system as braided or woven copper wire, a flexible heat sink is produced to permit greater flexibility in controlling module temperature.

In accordance with the further aspect of the present invention for producing a well mixed color light output having an improved output efficiency a light driver is provided instead or in addition to the optical lens system.

The light driver is provided suitable for receiving LED light derived from a plurality of LED light sources and outputting a well mixed color light output. A preferred embodiment of the device incorporates a plurality of fiber optic wires that have a high light transmission efficiency, and also serve to mix light input in accordance with their configuration. The fibers are positioned in a light driver in a particular configuration to accept input LED light, spread the light into an evenly portioned output, whereupon the output light is well mixed with different characteristics of individual fiber outputs contributing to a homogeneous light output. The color mixing preferably takes place with a number of thin fibers spread out and sorted to provide an even distribution of output light based on discrete input light. The fiber output preferably is provided to a conical mirror that can obtain various output diameter light output. The light driver is compact and lightweight and useful with a number of appli- cations, including LED, fiber optic and other type of light source conduction. The present aspect of the invention also provides a method for mixing the light output of a number of LEDs, such as three or more LEDs with red, green and blue color output to provide a homogeneous colored light pattern output. The light sources need not be LED, but can be any type of different colored light sources. Color mixing is obtained through the use of a number of thin fiber optic wires provided in a distributed arrangement in the light driver. The light source feeds the thin fiber optic wires, which conduct the light in a distributed pattern equally over the output area.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood from the following description with reference to the accompanying drawings, in which:

Fig. 1 is a block diagram illustrating overall organization of an LED module;

Fig. 2 is an diagram of module layout;

Fig. 3 is a diagram of a typical control and power setup for a number of interconnected LED modules;

Figs. 4a, 4b illustrate the lensing system for an LED;

Fig. 5 is an illustration of a chromaticity diagram with a black body curve;

Fig. 6 is an illustration of a chromaticity diagram with a range of operation for an LED module according to the present invention; Fig. 7 is an illustration of a chromaticity diagram showing ranges of operation between available LED output and the black body curve;

Figs. 8a - 8e illustrate spectral graphs according to various operating conditions;

Fig. 9 shows a diagram of an application for the present invention;

Fig. 10 is a diagram of the light driver according to the present invention; and

Fig. 1 1 is a diagram of an arrangement of fiber optic wires for producing a mixed light output in accordance with the present invention;

Fig. 12 shows a power LED with adjustable colour temperature (CCT);

Fig. 13 shows an illumination with LED and fibre optics.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to Fig. 1 , a block diagram of an LED module system is shown generally as module system 10. Module system 10 includes an LED driver 12 that is connected between a color controller and LEDs 14. LED driver 12 is also connected to a temperature feedback 16 that senses the LED junction temperature and provides signals to LED driver 12 representative of the LED junction temperature. LED driver 12 converts the temperature feedback signals 16 to provide an indication of temperature feedback to the color controller.

LEDs 14 can be mounted to a support, or printed circuit board (PCB) 18 that serves a number of functions. In addition to supporting LEDs 14, PCB 18 provides good thermal conduc- tivity to dissipate heat generated by operation of LEDs 14. PCB 18 is also suitable for connection to a heat pipe 19 to further enhance thermal conductivity of PCB 18 to conduct generated heat away from LEDs 14. Heat pipe 19 can be connected to a heat sink 17 to permit rapid dissipation of heat drawn away from PCB 18 and LEDs 14 through heat pipe 19. Heat sink 17 can be provided as a standard commercially available heat sink, or can be composed of other material, such as braided or woven copper wire that permits a flexible shape. In addition, PCB 18 can be composed of a material with good thermal conductivity properties, such as is provided, for example, with aluminum sandwich construction. It should be apparent that various combinations of heat dissipation elements can be made, for exam- pie a heat sink can be directly thermally coupled to PCB! 8.

LEDs 14 can be composed of high power LEDs that operate in a range of one watt or higher. As a result, heat dissipation is an important operational parameter in obtaining optimal performance for producing desired color output. As a result, LEDs 14 are spaced a nominal distance to permit appropriate operation without significant unwanted heat buildup. Refer- ring to Fig. 2, LEDs 14 are shown positioned in a module 20 with spacing between LEDs 14 to prevent inappropriate heat buildup resulting from operation of LEDs 14. For example, LEDs 14 can be arranged to be separated by a distance of 20 mm from LED center-to-center. The distance between LEDs 14 is minimized based on consideration such as power rating, module heat dissipation, electrical and thermal compensation and lighting application. Module 20 is designed to have as small a footprint as possible given the above design considerations to permit efficient operation with appropriate thermal control while meeting the needs of the particular application.

Referring again to Figs. 1, 4a and 4b, module system 10 preferably includes an optical lens

1 1 used to optimize luminance produced by LEDs 14 in a miniature scale and to direct and transfer all radiated light from LEDs 14 to a particular desired target. The light radiated by lens 1 1 is in this embodiment on a 15 degree haveangle and permits a central focal point for the module of 10mm. A typical arrangement for a lens is to provide good optical imaging throughput, as is the case with lenses in microscopes and cameras, for example. These types of lenses redistribute light so that an entire set of light rays emanating from one point of a source meets again in one image point at a target location. However, for non-imaging optical applications, the light source is homogenous with regard to a target. That is, all points of the source are equivalent with regard to image value, and it is therefore unnecessary to distinguish among those points. Rather, it is more desirable that all the radiation from the source that is intercepted by the optical system is transferred to the desired target. Accordingly, there is no requirement that lens 1 1 directs specific light from individual LEDs to the desired source with optical clarity. That is, lens 1 1 is not necessarily designed to transfer an optically optimized image, but rather preferably captures all radiated light from LEDs 14 and transmits the radiated light with maximum efficiency to the desired target. Lens 1 1 thus permits a high level of radiated efficiency directed to a desired target, which is not necessarily the case with other lighting applications that require high quality imaging optics. Because module system 10 is used for illumination purposes, the output of the module is designed to be as efficient as possible, while being precisely controlled to produce the desired light type.

Lens 1 1 preferably directs emitted light output through a color mixer 13. Color mixer 13 is preferably made of an acrylic material, and contains a microstructure to contribute to increasing luminance in addition to providing high performance color mixing action. Alternately, or in addition, lens 1 1 is coated with a holographic material that provides improved luminant efficiency and excellent color mixing performance. It should be apparent that color mixer 13 can be applied directly to lens 1 1 , or in various combinations with LEDs 14 to achieve the desired efficiency in luminance output and color mixing performance. Module system 10 thus produces illumination output with an efficient and optimized flux density that can be directed toward a specific target through an improved lensing system. It should be noted that the module output does not require a direct correspondence between the light emission origin and the desired light output target, and thus permits luminance to improved while enabling the module to be constructed in a minute size.

Temperature feedback 16 in module system 10 is used to measure the junction temperature of LEDs 14 and provide a related signal to LED driver 12. LED temperature measurements through temperature feedback 16 are constantly updated to permit precise LED temperature control. The signals generated in temperature feedback 16 are conditioned by LED driver 12 to provide a normalized measurement of LED junction temperature for feedback and control purposes. Temperature feedback 16 can be used to close a control loop through LED driver 12 to provide direct, on module closed loop control of operational parameters of LEDs 14. In addition, or alternately, conditioned signals related to temperature feedback 16 is transmitted by LED driver 12 to a color controller, which can supply LED driver 12 with appropriate control instructions based on further criteria or an external frame of reference. Accordingly, the control loop for controlling the operational parameters of LEDs 14 can be closed locally or remotely to obtain precise output given a potentially widely ranging set of operational parameters. This flexibility in controlling module system 10 and LEDs 14 allows a number of optimized lighting applications to be realized in a very simple and efficient manner.

The control loop for controlling the output and junction temperature of LEDs 14 can be algorithmic in nature and based on a number of operational characteristics. For example, using temperature feedback 16, LED driver 12 can control parameters such as voltage and current supplied to individual LEDs 14 to maintain a particular color output while also controlling LED junction temperature to avoid operation in unwanted ranges. In practice, an algorithm and control system preferably is implemented on an integrated circuit that is in- corporated into an electronic chip that is dedicated to the control of each LED 14 on module 20. The chip can be created as an application specific IC, such as that provided by Melexis Company. With long term operation of module 20 heat can increase and collect in the module components, leading to a decrease in efficiency. However, by controlling the temperature feedback loop using temperature feedback 16 and appropriate current and voltage control, the individual LED 14 efficiency can be maintained at a high level, contributing to overall module efficiency. This type of individual temperature feedback and compensation can obtain extremely high precision output matching that specified by a user. If module system 10 is provided with an active cooling system, such as, for example, a fan or other switchable cooling apparatus, LED driver 12 can signal the fan to change operation to modify thermal dissipation of heat generated by LEDs 14. By appropriately controlling the power, voltage and current supply to LEDs 14, LED driver 12 can cause LEDs 14 to output a specified light type while maintaining a desired LED junction temperature based on temperature feedback 16 and specified operating or algorithmic parameters. Accordingly, any desired CCT or coordinate in a CIE chromaticity diagram can be obtained as desired with an optimized CRI and without operating LEDs 14 in an inappropriate temperature range. Temperature feedback 16 further provides module system 10 with the ability to maintain a high efficiency light output while continuing to precisely control the output light type to produce desired light emission luminance.

In addition to temperature feedback 16, module 20 can also include a light sensor feedback (not shown) that obtains light level input to provide a lumen feedback for precise light level control. The light level sensor can be located on light module 20, or remotely, depending on the application. The light level sensor can supply a variable feedback, representative of light levels or light quality, or can be a discrete level sensor that provides a signal for a particular lighting level set point, for example. With the discrete light level sensor, a lighting set point can be obtained and maintained with precision due to feed back from the light level sensor. Module 20 may also feature customizable trimming of circuit parameters to match LED characteristics with operational control parameters. For example, the circuits associated with each LED 14 that are responsive to variations in power, current, voltage and heat parameters can be set to have certain characteristics that are dependent upon physical characteris- tics of the LEDs to which they are connected. During manufacture, for example, PCB 18 is provided with thin film and thick film resistors that are used in the circuitry connecting LEDs 14 to the module circuitry and external circuits. Each of the LEDs 14 connected to PCB 18 can have different fundamental characteristics regarding operational parameters. For example, two different LEDs may have differing luminance output given a same electrical input. Similarly, the different LEDs may have different thermal characteristics when operated at a particular luminance. Accordingly, the thin film and thick film resistors on PCB 18 can be laser trimmed to adjust their resistivity to compensate individual LEDs 14 such that they can be normalized with regard to electrical input and responsiveness, or an LED junction temperature given a specific operating characteristic. Alternatively, each individual LED can be tuned with the associated laser trimmable thick film and thin film resistors to overcome manufacturing tolerances or individual characteristics of the given LED 14 to achieve a certain operating parameter range. In this way, each LED 14 on a given module 20 can operated within a tolerance range to provide precise output based on specific input parameters. This trimmable resistor configuration contributes to precision module control while assisting in lengthening the useful life of LEDs 14. In addition, an individual controller for each LED 14 can provide compensation for the different spectral output range that is possible with each LED 14 due to manufacturing tolerances. That is, each LED 14 can be controlled, for example, using an application specific IC that can provide individual compensation for each LED, based on its particular output range and manufacturing tolerances so that improved efficiency and optimization can be obtained. Referring now to Figs. 2 and 3, interconnectivity and module network operation for different modules 20 preferably is provided through a color controller 31. A bus system 32 is used to address individual modules 20 to send and receive data, instructions and control signals for power and operation. Each module 20 includes a bus connection 22 available on intercon- nectivity portions of module 20. That is, each module 20 is constructed to be interconnected with any other module 20 on a number of different portions, preferably in four different directions. The connectors arranged to couple one module 20 to another module 20 provide a mechanical coupling to ensure the modules maintain their physical relationship. However, it is possible to maintain connectivity between the modules with flexible connectors so that each module 20 can move somewhat independently of any adjoining modules 20. For example, modules 20 can be formed together to provide a contour of a particular curved surface.

In practice, modules 20 are preferably coupled together with a butt fit to provide a good mechanical bond in addition to structural rigidity. The configuration of the module size and shape is maintained to permit any number of modules to be joined together to form an illumination system in varying shapes and light output strength. The modules can be arrayed together to custom fit the particular application for which they are used, including indoor and outdoor applications. This very flexible modular construction permits the demands of an illumination application to be met based on lumen demand, by simply coupling together an appropriate number of modules 20 in an appropriately shaped arrangement.

Interconnection between modules preferably is provided as the basis of a communication network that allows each module 20 to be individually addressed and accessed. For example, the bus system 32 connects to each module 20 to provide a communication medium for instructions, power, data, statuses and the like. An example of a hardware bus system that permits interconnection of the modules 20 is a three wire system (not shown) that includes signals of (1 ) v+, (2) GND and (3) serial control. Interaction between color controller 31 and a given module 20 takes place as direct signalling, or through the use of a specific protocol. Modules 20 can in addition be influenced by external devices and events through standard communication and control protocols such as DMX512, DALI and TCP/IP. Color controller 31 includes a gateway mechanism for receiving and sending information through standard communication protocols and providing appropriate signals to specified modules based on external commands or information. In the same way, information from modules 20 can be transferred to external or remote device through the gateway mechanism in color controller 31. Accordingly, the gateway in color controller 31 provides translation services between specified modules and external devices or interfaces. In addition, color controller 31 can maintain information obtained from various modules 20, and provide the same to external devices or interfaces through the gateway.

In accordance with a further preferred embodiment, color controller 31 is located with module 20 to provide module system 10. According to this embodiment, color controller 31 can provide network services on an individual module basis, as well as power control compensation, temperature feedback control and any other local module services. In this way, module 20 can take advantage of commercially available data and power buses, in addition to sophisticated network operations.

Referring still to Figure 3, an MMI (man-machine-interface) is provided to control each module or an array of modules according to user inputs. For example, the MMI can be a PDA, PC, tablet or remote control. The MMI can also be part of a larger system or network for lighting control, for example, in a building or local area network setting. A feature provided by the use of the MMI is programming and software based instruction and data collection. For example, a Java based software structure can be used to permit interfacing with a number of computer systems that may operate on different software platforms. In addition, a number of systems can interact with user interfaces that can provide control or feedback transmission through the MMI.

Color controller 31 also provides regulated power to each of the interconnected modules through bus 32. Any standard power supply can be used to supply power to color controller 31 , such as 100 - 240 VAC or nominal DC power. Color controller 31 converts or regulates input power as required for the modules 20 connected to bus 32.

Voltage and current supplied to each LED 14 is controllable for user set output. For example, a user sets a CCT or a coordinate in the CIE chromaticity diagram. Each module 20 contains circuitry to optimize the CRI of the output and maximize the output luminance while con- trolling current and voltage to each LED 14 to achieve the desired color and light type output.

Each module 20 has LEDs 14 with colors of cyan, blue, amber and white for a total of four LEDs. In addition, a supplemental LED 14 can be provided with another color to provide a particular lighting effect or decorative color. Referring to Figs. 5-7, a chromaticity diagram, also referred to as a "color shoe", is shown with the various RGB portions noted at vertices of the diagram. The chromaticity diagrams in the Figures indicate the black body curve moving from the red spectrum of the light in about 780 nanometers to a middle portion of the chromaticity diagram. Figure 5 illustrates values in terms of correlated color temperature !:S (CCT) or expressed in degrees Kelvin. For example, Figure 5 illustrates the black body curve with values marked from 800K to 200,000K.

Referring to Figure 6, a triangle is specified within the chromaticity diagram having vertices noted as cyan, amber and blue. It is within this triangle that the module according to the present invention can operate to provide color output, in addition to free movement along the black body curve contained within the triangle. Module 20 according to the present invention is equipped with LEDs having colors of cyan, blue and amber to achieve any kind of color mix within the noted triangle in Figure 6. The contents of the triangle also include a white light spectrum, that is indicated by the black body curve, for example. By producing appropriate modulation of the LEDs 14, color combinations along the black body curve can be achieved to produce white light output. Module 20 also includes a white light LED to increase the intensity of the white light output provided by the module. By providing a color mixing module with these four LEDs, a soft white light can be produced in a variety of intensity ranges along the black body curve.

When a point on the black body curve is selected for an output light level and quality, mod- ule 20 optimized the circuit operating parameters based on desired luminance and generated heat. The output light has high quality luminance and precise quality, while any inappropriate operating ranges for module 20 are avoided.

An algorithm for determining circuit operating parameters is employed by module 20 to produce the appropriate power and control signals for LEDs 14. The algorithm inputs items such as desired light quality and luminance levels, and outputs particular signals for controlling LEDs 14 on a circuit optimized basis, in addition to optimizing the CRI and luminance output of module 20.

Referring again to Figure 3, a user interface is connected to color controller 31 to permit interaction between a user and module system 10. The user interface can be as simple as an ordinary dimming knob for conventional lighting applications, or can be a computer interface with software for specific lighting control and feedback recordation. For example, using a computer interface, a user can select a particular light spectra, a lighting sequence or program and set particular operating parameters. The user interface can also be used to collect data and act to transmit information over a network, for example. Referring to Figs. 8a - 8e, various spectral charts are illustrated. The charts show various spectral comparisons between the output light of the present invention, and visible light, as well as black body spectral light, at various illumination intensities.

A number of applications for the present invention are readily feasible, including signage, signaling, street lighting, optical communication systems and miniature light applications, including, for example, endoscopes. Some features and applications of the present invention are shown in Figures 12, 13 (Appendices A and B) and Figure 9. A particular feature of the present invention permits high quality color mixing to produce even colors in selected ranges without loss of efficiency. For example, module 20 can be used as a light source in a fiber optic light output system to supply light to a bundle of fibers 90 that is mixed prior to being received in the fiber bundle. An output of the fiber bundle will have the same well mixed color output in each fiber. Accordingly, a single source of controlled light can be supplied to a number of different points through a fiber optic system, with each of the various remote points having the same quality light with good color mixed qualities. This applica- tion is accomplished by supplying a fiber bundle 92 and optical plate 94 between lighting module 20 and the output fiber bundle. The fiber bundle associated with the module output provides cross-mixed color output from each LED 14 to plate 94 that disperses the module 20 and fiber bundle 92 light, so that the output fiber bundle 90 receives a high quality color mix light output for supply to the remote outputs of the fiber optic bundle. Accordingly, as the intensities or color ranges of each LED is adjusted, the fiber bundle output sees only a single well mixed soft color output without crossover or fadeout points. This type of lighting application provides a high quality light that can be distributed over broad ranges for industrial, commercial and residential uses.

Regarding the further aspect of the present invention, referring now to Fig. 10, a diagram according to the present invention shows generally a light driver 1 1 1. Light driver 1 1 1 is composed of two sections, a fiber optic section 1 10 and a conical mirror 1 1 2. Fiber optic section 1 10 includes thin fiber optic wires 1 14 that run from optical inputs 1 13 to a collecting collar 1 1 5. Light introduced through optical inputs 1 13 is conducted by fiber optics 1 14 to conical mirror 1 12, where a mixed light output of a specified diameter is provided.

Referring now to Fig. 1 1 , an illustration of the light paths provided by optical fibers 1 14 is illustrated generally as light path diagram 120. Diagram 120 has inputs 123 representing discrete light input sources, and light output 126. The number of light pathways, illustrated as path 124 conducts light from discrete sources at light inputs 123 to a distributed light output at output 126. Because light paths 1 24 are distributed across light output 126, a light or a color mixing action occurs where light from discrete light inputs 123 is interwoven and output as a single light transmission at output 126. The fiber selected to provide pathways 124 can be variable, depending upon the application, and are preferably thin to permit a good color mixing result. Any number of inputs can be processed with this light driver to produce a well mixed color output. For example, a number of light sources can be pro- vided at any discrete light input 123 to provide a further light mixing operation. A variety of mixing operations can be obtained, for example, by selecting various width fibers and providing a greater or lesser number of fibers at discrete light inputs 123. Furthermore, various intensities of light output can be obtained depending upon the selection of fibers and the light input provided to discrete light inputs 123.

Figure 12 (Appendix A) shows an embodiment of a LED light system modules 20 with adjustable colour temperature (CCT) for white light adjustable from 1500 K to l O'OOO K and optimised colour rendering (CRI). The colour choice is programmable for all colours. The shown embodiments comprise a build in thermal protection and power control. A further embodiment shows a down light with choice of light-colour by StellarColor™ 4 Watt Power LED to assemble flat or accentuation stick out. The shown embodiment has an aluminium case dampness and humidity protection.

Figure 13 (Appendix B) shows an embodiment of an illumination with LED and fibre optics, e.g. for showcases, museums, boats, caravan, etc. The LED light driver is suitable for various light outputs, e.g. a star field. In the shown embodiment no ventilation noise, no UV- or IR- radiations, no electricity on the leads or on the light output is present. The shown embodiment is designed for 6 Watt total power consumption, colour rendering and fading time, programmable by DMX Systems. The shown embodiment is vibration resistant and provides long lifetime of the light source. The compact size is length 198 mm, width 65 mm, height 55 mm. The dimensions of the fibre window (example: 200 fibres with a diameter of 1 mm) are 25 mm in diameter, 479 mm².

Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.

Claims

1 LED Lighting module system (10, 20) for precise color output control comprising multiple LEDs (14) having each a different visible light spectra.

2 LED Lighting module system (10, 20) according to claim 1 , characterized in that at least one LED (14) emits light with the color of cyan, at least one LED (14) emits light with the color of blue, at least one LED (14) emits light with the color of amber and at least one LED (14) emits white light.

3 LED Lighting module system (10, 20) according to one of the previous claims, characterized by an optical lens system (1 1 ) to direct and transfer radiated light from the LEDs (14) to a desired target.

4 LED Lighting module system (10, 20) according to claim 3, characterized in that the lens system (1 1 ) contains a microstructure to increase luminance.

5 LED Lighting module system (10, 20) according to one of the previous claims, characterized by a color mixer (13) to mix color light output of the LEDs (14).

6 LED Lighting module system (10, 20) according to claim 5, characterized in that the color mixer (13) is made of an acrylic material.

7 LED Lighting module system (10, 20) according to claim 5 or 6, characterized in that the color mixer (13) is applied directly to lens (1 1 ).

8 LED Lighting module system (10, 20) according to one of the claims 5 or 6, charac- terized in that the color mixer comprises optical fibres (92).

9 LED Lighting module system (10, 20) according to one of the previous claims, characterized in that a LED driver (12) is connected between a color controller (15) and LEDs (14). LED Lighting module system (10, 20) according to claim 9, characterized in that a temperature sensor (16) provides temperature feedback to LED driver (12).

LED Lighting module system (10, 20) according to one of the previous claims, characterized by a closed loop temperature control system for measuring the temperatures of the LEDs.

LED Lighting module system (10, 20) according to one of the previous claims, characterized in that an algorithm for controlling the LEDs (14) is implemented on an integrated circuit that is dedicated to control each LED 14 of a module (20).

LED Lighting module system (10, 20) according to one of the previous claims, characterized by a light sensor for lumen feedback for light level control.

LED Lighting module system (10, 20) according to claim 13, characterized in that the sensor is located on the light module (20) or remotely.

LED Lighting module system (10, 20) according to one of the previous claims characterized by a bus interface for connection with another module (20).

LED Lighting module system (10, 20) according to one of the previous claims characterized by a printed circuit board comprising precision resistors trimmable for individual LED compensation.

LED Lighting module system (10, 20) according to one of the previous claims characterized by a printed circuit board composed of heat sink material.

LED Lighting module system (10, 20) according to claim 17, characterized in that the heat sink material comprises an aluminium sandwich construction or mesh or braid of copper wires.