EP2753876B1

EP2753876B1 - Improved led luminaire cooling system

Info

Publication number: EP2753876B1
Application number: EP12788653.9A
Authority: EP
Inventors: Pavel Jurik; Josef Valchar
Original assignee: Robe Lighting sro
Current assignee: Robe Lighting sro
Priority date: 2011-09-05
Filing date: 2012-09-05
Publication date: 2019-11-06
Anticipated expiration: 2032-09-05
Also published as: EP2753876A2; WO2013036539A3; WO2013036539A2

Description

RELATED APPLICATIONS

This application is a full utility patent application claiming priority of US provisional patent application(s) 61/531,066 filed 5 September 2011 .

TECHNICAL FIELD OF THE INVENTION

The present invention generally relates to an automated luminaire, specifically to a luminaire utilizing a high intensity light emitting diode (LED) light source. More specifically to a system and method for cooling the light source.

BACKGROUND OF THE INVENTION

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.
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 automated luminaire 12 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 automated luminaires 12 typically include electronic circuitry as part of the electromechanical control system for controlling the automated lighting parameters.
Figure 2 illustrates a prior art automated luminaire 12 utilizing a high intensity discharge (HID) lamp 21. The 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 27 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.
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 correct operating temperature limits. Figure 3 illustrates one example of a typical prior art lamp cooling system in an automated luminaire 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 30 or bounced from reflector 31. One or more fans 41 are blowing ambient air across lamp 30 to cool it.
Figure 4 illustrates a further prior art lamp 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 43 and/or 44 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.
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 such as disclosed for example in WO 2011/076219 A1 may work but are noisy and large.
Figure 5 illustrates a prior art cooling system for an automated luminaire 12 using LEDs 54 as the light source. LEDs 54 are mounted to a heat conducting substrate board 56 which, in tum, is mounted to a heat sink 52. Heat from the LEDs passes through the substrate board 56 into the heat sink 52 from where it is dissipated into the surrounding air. The heat dissipation from the heat sink 52 may be improved by adding a fan to the system blowing air across heat sink 52. Such systems often require large heat sinks to dissipate the heat from LEDs and are constrained by the necessity to site the heat sink adjacent to the LEDs. This may be particularly difficult when it is desired to position the LEDs 54 within a reflector 57 as illustrated in Figure 6 . The optical and physical requirements of reflector 57 are often in conflict with the thermal requirements of heat sink 52 and force engineering compromise in the design of one or the other.
Figure 7 illustrates a further prior art cooling system where three arrays of LEDs 54a, 54b and 54c are arranged around dichroic beam combiners 58 and 59. Each array of LEDs 54a, 54b and 54c is mounted to heat conducting substrate boards 56a, 56b and 56c which, in turn, are mounted to heat sinks 52a, 52b and 52c. The need and use of multiple LED arrays 54a, 54b and 54c further limits the space available for heat sinks 52a, 52b and 52c and constrains their size and thus efficiency.
A further disadvantage of all the illustrated prior art cooling systems is that the heat dissipated through heat sinks is always close to the heat source itself - the LEDs. It would be advantageous if the heat could be dissipated at a distant point to the LEDs.
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 and with the heat dissipation occurring remote to the LEDs.

BRIEF DESCRIPTION OF THE DRAWINGS

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:

FIGURE 1 illustrates a typical multiparameter automated luminaire system;
FIGURE 2 illustrates a prior art automated luminaire;
FIGURE 3 illustrates a typical prior art lamp cooling system in an automated luminaire;
FIGURE 4 illustrates a further prior art lamp cooling system for an automated luminaire;
FIGURE 5 illustrates a prior art cooling system for an automated luminaire;
FIGURE 6 illustrates a prior art cooling system;
FIGURE 7 illustrates a further prior art cooling system;
FIGURE 8 illustrates an embodiment of an improved luminaire cooling system, and;
FIGURE 9 illustrates a further embodiment of the luminaire cooling system of Figure 8 .

DETAILED DESCRIPTION OF THE INVENTION

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.
The present invention generally relates to an automated luminaire, specifically to a luminaire utilizing a high intensity LED light source and the cooling systems contained therein.
Figure 8 illustrates an embodiment of an improved luminaire cooling system of the invention utilizing a high-powered LED array. LED array 54 is mounted to a heat conducting substrate board 56 which in tum is mounted to first heat exchanger 62. First heat exchanger 62 contains a thermal transfer coil through which is passed a thermal transmission liquid. In one embodiment a transmission liquid was chosen with a boiling point outside the range of operating temperature of the system, with a low coefficient of thermal expansion, a high capacity to absorb heat. Heat from LEDs 54 passes through heat conducting substrate board 56 to first heat exchanger 62. The thermal transmission liquid picks up heat from first heat exchanger 62. Pump 64 circulates the thermal transmission liquid, as indicated by arrows 63, around pipes 61 to second heat exchanger 66 which is being cooled by fan 68 and air flow 65. The cooled thermal transmission fluid then passes back to the first heat exchanger 62 via pipes 67 to complete the circuit. Second heat exchanger 66 is sited remotely from the first heat exchanger 62 and thus remotely from LEDs 54. Second heat exchanger 66 is not constrained in size and position by the optical requirements of the LEDs 54 and thus may be sited advantageously in an area with good access for cool, ambient air. Second heat exchanger 66 may also be larger than first heat exchanger 62 and may use a large, slow speed, fan 68 which may operate at a low noise level. The use of an active pump 64, as opposed to a non-pumped heat-pipe cooling system, ensures that the cooling system is not orientation dependent and will operate at any orientation of the system. This is critical with automated luminaires as the luminaire may be operated in any orientation. The connecting pipes 61 and 67 may be solid pipes or flexible pipes of metal or high temperature rubbers or plastics depending on the systems design. The connecting pipes 61 and 67 in some embodiments may pass through the rotating joints of the pan and tilt mechanism of the automated luminaire. For these designs high temperature flexible materials are desirable.
Although the system illustrated uses a reflector 57 to direct the light output from LEDs 54 the invention is not so limited and light collection and direction may be through any means as known in the art including but not limited to, total internal reflector (TIR) lenses, elliptical reflector, parabolic reflector, spherical reflector, and light pipes. LEDs 54 may be a densely packed array of LEDs and may all be of a single color, such as white, or may be an array of different colors such as red, green, blue or red, green, blue and white or red, green, blue, amber and white or other color mixes as well known in the art.
The invention may be used in any optical design of automated luminaire, including but not limited to, spot lights, wash lights and beam lights. Such designs may use lenses such as Fresnel lenses or arrays of lenses. Automated luminaires according to the invention may contain optical devices including but not limited to gobos, color mixing systems, rotating gobos, iris, prisms, beam shapers, variable frost, effects systems and moving reflectors to provide hot-spot control.
In further embodiments of the invention the thermal transmission fluid and pump may be replaced with a phase change heat pump system using a volatile refrigerant and compressor and evaporator coils in place of the first and second heat exchangers.
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.
In yet further embodiments, as illustrated in Figure 9 , 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 fan 68 and pump 64 accordingly. In Figure 9 master control circuit 70 receives input 76 of temperature sensors (not shown) near the LEDs 54 and input 75 of temperature senses of the effluent from second heat exchanger 66 and controls the speed and operation of pump 64 via control signal 74 and fan 68 via control signal 72. Further sensors may be used to sense temperatures at multiple locations in the 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 LEDs 54 to control the speed of pump 64 and fan 68. For example, if the user commands the LEDs 54 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 and pump speeds to a level commensurate with the power level being provided to LEDs54. The pump and fan speeds may also be controlled based on the temperature input from the various sensors or the differential of temperatures across sensors.
In other embodiments the pump and fan speeds may be controlled through commands received over the data 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.
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 invention as defined by the appended claims.

Claims

An automated moving head luminaire comprising:
an LED array (54) mounted in a remotely controllable moving head to change the direction of an emanated light beam, the LED array (54) generating light and heat;

one or more heat conductive elements (56) adapted to conduct the heat from the LED array (54) into a first heat exchanger (62);

characterized in that it further comprises

a second remotely sited heat exchanger (66) where the heat is dissipated; and

a pump (64) adapted to pump fluid between the first heat exchanger (62) and the second heat exchanger (66).
The automated moving head luminaire of claim 1, wherein the first heat exchanger (62) comprises a thermal transfer coil through which the fluid is passable.
The automated moving head luminaire of claim 1 or 2, wherein the second heat exchanger (66) is cooled by a fan (68) and an air flow (65).
A luminaire cooling system comprising:
an automated moving head luminaire (12) according to any one of claims 1-3; and

a control circuit (70) configured to receive input (75, 76) from temperature sensors and to control the speed of the pump (64) of the automated moving head luminaire (12) based on the received input (75, 76).
The luminaire cooling system of claim 4, wherein the control circuit (70) is further configured to control the speed of the fan (68) of the automated moving head luminaire (12).
The luminaire cooling system of claim 4 or 5, wherein the speed of the pump (64) and/or the speed of the fan (68) are further controllable through commands received over a data link (14).