WO2013036538A1

WO2013036538A1 - Led cooling system

Info

Publication number: WO2013036538A1
Application number: PCT/US2012/053805
Authority: WO
Inventors: Pavel Jurik; Josef Valchar
Original assignee: Robe Lighting, Inc.
Priority date: 2011-09-05
Filing date: 2012-09-05
Publication date: 2013-03-14
Also published as: EP2753877A1; CN103890489A; EP2753877B1

Abstract

Described is a cooling system for LED light source modules with a heat exchanger designed for automated luminaires cooling fans and efficienctly cool the LED light source module.

Description

LED COOLING SYSTEM

RELATED APPLICATIONS

[0001] This application is a full utility patent application claiming priority of US provisional patent application(s) 61/531,059 filed 5 September 2011.

TECHNICAL FIELD OF THE INVENTION

[0002] The present invention generally relates to an automated luminaire, specifically to luminaires utilizing high intensity LED light source(s). More specifically to system(s) and method(s) for cooling the light source(s).

BACKGROUND OF THE INVENTION

[0003] Luminaires with automated and remotely controllable functionality are well known in the entertainment and architectural lighting markets. Such products are commonly used in theatres, television studios, concerts, theme parks, nightclubs and other venues. A typical product will provide control over the pan and tilt functions of the luminaire allowing the operator to control the direction the luminaire is pointing and thus the position of the light beam on the stage or in the studio. This position control is often done via control of the luminaire 's position in two orthogonal rotational axes usually referred to as pan and tilt. Many products provide control over other parameters such as the intensity, color, focus, beam size, beam shape and beam pattern. The beam pattern is often provided by a stencil or slide called a gobo which may be a steel, aluminum or etched glass pattern. The products manufactured by Robe Show Lighting such as the ColorSpot 700E are typical of the art. [0004] Figure 1 illustrates a typical multiparameter automated luminaire system 10. These systems commonly include a plurality of multiparameter automated luminaires 12 which typically each contain on-board a light source (not shown), light modulation devices, electric motors coupled to mechanical drives systems and control electronics (not shown). In addition to being connected to mains power either directly or through a power distribution system (not shown), each luminaire is connected in series or in parallel via data link 14 to one or more control desks 15. The automated luminaire system 10 is typically controlled by an operator through the control desk 15. Consequently, to affect this control both the control desk 15 and the individual luminaires typically include electronic circuitry as part of the electromechanical control system for controlling the automated lighting parameters.

[0005] Figure 2 illustrates a prior art automated luminaire 12 utilizing a high intensity discharge (HID) lamp. An HID lamp 21 contains an arc or plasma light source 22 which emits light. The emitted light is reflected and controlled by reflector 20 through an aperture or imaging gate 24. The resultant light beam may be further constrained, shaped, colored and filtered by optical devices 26 which may include dichroic color filters, dimming shutters, and other optical devices well known in the art. The final output beam may be transmitted through output lenses 28 and 31 which may form a zoom lens system. Typically luminaires employing a HID type lamp employ a hot mirror 46 which is a window which transmits visible light and reflects non-visible energy radiating energy.

[0006] Such prior art automated luminaires use a variety of technologies as the light sources for the optical system. For example it is well known to use incandescent lamps, high intensity discharge (HID) lamps, plasma lamps and LEDs as light sources in such a luminaire. Many of these light sources need cooling to maintain them within acceptable operating temperature limits. Figure 3 illustrates one example of a prior art lamp light source 30 and its major components. Lamp 30 may comprise a sealed quartz envelope 37 with two contained electrodes 34 and 35 which are typically manufactured of tungsten. In operation an electrical arc is struck between electrodes 34 and 35 thus creating high temperature plasma and producing light. The specific mechanism and chemistry for the light production is beyond the scope of this patent and does not relate to the novelty of the invention. The luminaire designer must develop a cooling system which maintains the desired temperatures for the components of lamp 30. A further constraint is the need for any cooling systems to avoid interfering with the reflector 31 or with any of the light beams emitted from the lamp or bounced from reflector 31.

[0007] Figure 4 illustrates a further prior art cooling system for an automated luminaire which seeks to maintain correct temperatures of the lamp 30 in particular the lamp envelope 37 and lamp pinches 32 and 33. In this design one or more fans 41 are directed into the reflector 31 in such a manner as to direct external cool air around the lamp 30. The cooling air may be directed directly on to the lamp as illustrated or may be directed at an angle so as to form a vortex of air around the lamp.

[0008] None of these prior art systems work well with a light source comprising an array of high powered LED emitters. Such arrays cover a wide area, rather than the single point light source provided by prior art lamps, and are not contained within a single reflector. Designs using simple fans blowing over the LED arrays may work but are noisy and large.

[0009] There is a need for a cooling system for high powered LED arrays in an automated luminaire which offers improved cooling of such arrays in a compact system with good control of the noise emitted by the cooling system. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numerals indicate like features and wherein:

[0011] FIGURE 1 illustrates a typical automated lighting system;

[0012] FIGURE 2 illustrates a prior art system;

[0013] FIGURE 3 illustrates a typical prior art lamp cooling system in an automated luminaire;

[0014] FIGURE 4 illustrates a prior art lamp cooling system;

[0015] FIGURE 5 illustrates an embodiment of the invention;

[0016] FIGURE 6 illustrates a perspective view of an embodiment of the invention;

[0017] FIGURE 7 illustrates a perspective view of one of the two side heat exchanger subsystems 106 of Figure 6;

[0018] FIGURE 8 illustrates a perspective view of the LED light source of an

embodiment off the invention;

[0019] FIGURE 9 illustrates a top view of the airflow over the top of one of the fins of the side heat exchanger of Figure 7;

[0020] FIGURE 10 illustrates the cooling system illustrated in Figure 6 with the side heat exchanger subsystems 106 and 116 removed.

[0021] FIGURE 11 illustrates a perspective view of a heat exchanger of an embodiment of the invention; [0022] FIGURE 12 illustrates a perspective view of another heat exchanger subsystem

107 of an embodiment of the invention; and

[0023] FIGURE 13 illustrates a top view of the airflow over the top of one of the fins of the side heat exchanger of Figure 3.

DETAILED DESCRIPTION OF THE INVENTION

[0024] Preferred embodiments of the present invention are illustrated in the FIGURES, like numerals being used to refer to like and corresponding parts of the various drawings.

[0025] The present invention generally relates to an automated luminaires, specifically toluminaires utilizing a high intensity LED light source and the lamp cooling systems contained therein.

[0026] Figure 5 illustrates an automated luminaire 100 using an embodiment of the invention utilizing a high powered LED array. Automated luminaire 100 contains a light source module 102 which emits light through optical devices 150 and 152 which may include gobo wheels, rotating gobo wheels, effects wheels, irises, frost systems, dichroic color filters, dimming shutters, and other optical devices well known in the art. The final output beam may be transmitted through output lenses 154 and 156 which may form a zoom lens system.

[0027] Figure 6 illustrates an embodiment of the invention. Light source module 102 comprises an LED array module 104 with light output aperture 105. LED array module 104 is surrounded by a pair of side heat exchanger subsystems: a first side heat exchanger subsystem 106 with associated fins 113 and cooling fan 114, and a second heat exchanger subsystem 116 with associated fins 109 and fan 110.

[0028] Figure 8 also illustrates a combined multi-surface heat exchanger subsystem 107 with associated fins (not shown in Figure 6), and fans 108 and 112. Fans 108, 110, 112 and 114 may direct air through their associated heat exchanger subsystems. Fans 108, 110, 112 and 114 may be low speed fans such that the noise produced is low.

Further, fans 108, 110, 112 and 114 are positioned such that airflow is directed 140 and 144 into the heat exchanger subsystems 106, 116, 107 which also serve to baffle and attenuate the fan noise. The air flow 140, 144 into the heat exchanger subsystems 106, 116 107 results in airflow 142 146 (airflow out of subsytems 116 and 107 not shown in Figure 6).

[0029] Figure 7 illustrates one of the side heat exchangers 106 with its fins 113 and fan 104.

[0030] Figure 8 illustrates an LED array module of an embodiment of the invention. LED array module 104 contains high-powered LED arrays and optical combining systems which direct light through light output aperture 105. LED arrays may be mounted within LED array module 104 on the internal sides of faces 120, 122, 124, 126 and 128. Faces 120, 122, 124, 126 and 128 are thermally conductive surfaces designed to transfer heat from the internal arrays to the outside of the LED array module from where it is transferred to the heat exchangers.

[0031] Figure 9 is a top view illustration of the airflow 150 generated by fan 114 across one of the fins 113 of the heat exchanger subsystem illustrated in Figure 7. The airflow enters the fins as turbulent 152 and depending on the speed of the fan 114 and volume of airflow 150 the turbulent flow 152 converts to laminar flow 154. Since the fins 113 are tapered at the exit end 151, the air on the tap end 115 begins to curve away from the light source 104 and create a Bernoulli effect 156 158 drawing the air increasingly away from the light source 104. The benefits of the turbulence at the entry and at higher speeds is more efficient heat transfer to the air. The benefits of the laminar flow at lower speeds is quieter operation. Since the turbulent flow is more efficient the cooling at the light output 105 end 160 of the light source increases the temperature differential at the output side 160 relative to the side 162 closer to the source surface 126 - encouraging wicking of heat in direction 164. At the same time depending on operating temperatures the efficiency of the turbulent flow may be offset by a greater temperature differential at the side 162 closer to the source surface 126.

[0032] Figure 10 illustrates the heat exchanger system illustrated in Figure 6 with the side heat exchanger subsystems removed - leaving the light source 104 and heat exchanger subsystem 107 including its fans 108 and 112.

[0033] Figure 11 illustrates a heat exchanger of an embodiment of the invention. Thermally conductive surfaces 134 are in intimate contact with a thermally conductive surface of the LED array module such as surface 128 of Figure 8. The transferred heat is then transferred into radiant fins 132. Radiant fins 132 and thermally conductive surfaces 134 may be constructed of copper, aluminum or other material with high thermal conductivity. In the example shown in Figure 8, the radiant fins 132 extend throughout the heat exchanger 140 and include three thermally conductive surfaces, each of which is in contact with a different thermally conductive surface of the LED array module. The majority of radiant fins 132 are enclosed by cover 130, with the exception of incoming air apertures for the fans 108 and 112, and exiting air aperture 136. Cover 130 thus forms an air duct directing cool ambient air 140 in to the heat exchanger through fans 108 and 112. This air flows over and between the radiant fins 132 constrained by cover 130. Heat is transferred to the air from the radiant fins and finally hot air 142 exits the heat exchanger at 136. Exiting hot air 142 may be directed outside the automated luminaire. The ducting of the air from the fans through the ducted heat exchanger serves to both cool the LED module, and baffle and silence the fans.

[0034] A 'C shaped heat exchanger in contact with three surfaces of the LED module is illustrated here, however the invention is not so limited and any number of surfaces of the LED module may be in contact with the heat exchanger. Although two fans 108 and 112 are illustrated here the invention is not so limited and any number of fans may be utilized.

[0035] Figure 12 illustrates a heat exchanger of an embodiment of the invention with the top and side of the ducting covers removed. It can be seen how the radiant fins 132 extend around the inside of the heat exchanger to provide a large surface area for heat transfer. Heat is transferred from conductive surfaces 134 into the radiant fins 132 as previously described.

[0036] Figure 13 is a top down illustration of the airflow 170 across the fins 132 of the heat exchanger subsystem illustrated in Figure 10. Higher incidence of turbulent flow areas are illustrated 172 and 174. As are Bernoulli force effects 176 due to the exit flow dynamics at the airflow exit 136.

[0037] Although the figures shown here are of embodiments with imaging optics that are capable of producing projected images from gobo wheels and other pattern producing optical devices, the invention is not so limited and the light output from the optical system may be imaging where a focused or defocused image is projected, or non-imaging where a diffuse soft edged light beam is produced, without detracting from the spirit of the invention. The invention may be used as an LED array cooling system with optical systems commonly known as spot, wash, beam or other optical systems known in the art.

[0038] In yet further embodiments, the cooling system may be actively controlled using feedback from the lamp control system and temperature probes measuring the ambient temperature in and around the lamp and/or lamp house and controlling the speed of fans 108, 110, 112 and 114 accordingly. Separate sensors may be used to sense temperatures at each LED array and/or the LED module and/or other locations inside and outside the luminaire house. Such systems may also use the power provided to LED module 104 to control the speed of cooling fans. For example, if the user commands the lamp to dim down to 20% output through the control console and link as shown in Figure 1 then the cooling system may respond to this by reducing fan speeds to a level commensurate with the power level being provided to LED module 140. The

commensurate level of fan speed is determined as a function of the heat power to heat generation curve of the source taken together with the cooling to fan speed curve(s) of for an internal external temperature differential. The fan speed may also be controlled based on the temperature input from the various sensors or the differential of temperatures across sensors.

[0039] In other embodiments the lamp cooling and fan speeds may be controlled through commands received over the communication link 14 shown in Figure 1. Such commands may be transmitted over protocols including but not limited to industry standard protocols DMX512, RDM, ACN, Artnet, MIDI and/or Ethernet.

[0040] While the disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as disclosed herein. The disclosure has been described in detail, it should be understood that various changes, substitutions and alterations canbe made hereto without departing from the spirit and scope of the disclosure.

Claims

WHAT IS CLAIMED IS: Claims could relate to:

1 . A luminaire comprising: an LED array which generates light and heat; fan(s) for driving a flow of air;

Heat exchanger drawing heat away from the LED array by ducting air in a manner that utilizes turbulent flow for cooling efficiency and converts the turbulent flow to laminar flow thereby decreasing airflow noise.