Anti-bird-collision light

Abstract

A helicopter anti-bird-collision system including a search light (2) and a control unit (35) which is configured for operating the search light (2) in a flash light mode by switching the search light periodically on and off.

Claims

1. A method of operating a helicopter search light, which may be operated in a flood light mode and a spot light mode, as an anti-bird-collision light wherein the method includes: operating the helicopter search light in a flash light mode by periodically switching the helicopter search light, operating in the spot light mode, on and off; and moving a direction of light emission of the helicopter search light along an elliptic pathway such that a combination of light cones emitted by the helicopter search light when switched on covers the elliptic pathway substantially completely; wherein said moving of the direction of light emission over a full cycle along the elliptic pathway takes at most one second, and wherein the helicopter search light is operated to flash between 2 and 14 times during the moving of the direction of light emission over the full cycle.

2. The method according to claim 1, wherein the elliptic cross section has a major axis and a minor axis and wherein the major axis is oriented horizontally.

3. The method according to claim 1, wherein the major axis of the of the elliptic cross section corresponds to an angle of 40°.

4. The method according to claim 1, wherein the helicopter search light is switched on and off while the direction of light emission of the helicopter search light moves along an elliptic pathway, wherein the helicopter search light in particular is switched on and off with a frequency such that the combination of light cones emitted by the helicopter search light covers the elliptic pathway substantially completely.

5. The method according to claim 2, wherein the major axis is at least five times larger than the minor axis.

6. A helicopter anti-bird-collision system including: a helicopter search light, which may be operated in a flood light mode and a spot light mode; and a control unit which is configured for operating the helicopter search light as an anti-bird-collision light in a flash light mode by periodically switching the helicopter search light, operating in the spot light mode, on and off; wherein the helicopter search light has an adjustable direction of light emission and wherein the helicopter anti-bird collision system further comprises a drive unit which is configured for moving the direction of light emission of the helicopter search light; wherein the drive unit is configured for moving the direction of light emission of the helicopter search light along an elliptic pathway so that said moving of the direction of light emission of a combination of light cones over a full cycle along the elliptic pathway takes at most one second; and wherein the control unit is configured for operating the helicopter search light to flash between 2 and 14 times during the moving of the direction of light emission over the full cycle.

7. The helicopter anti-bird-collision system according to claim 6, wherein the helicopter search light comprises at least one LED light source.

8. The helicopter anti-bird-collision system according to claim 6, wherein the helicopter search light is configured to provide a light intensity of at least 300,000 cd, in particular a light intensity of at least 300,000 cd in a peak intensity direction and a light cone having a half beam angle of about 3°.

9. The helicopter anti-bird-collision system according to claim 6, wherein the major axis of the elliptic cross section is oriented horizontally.

10. The helicopter anti-bird-collision system according to claim 6, wherein the control unit is configured to switch the helicopter search light on and off while the direction of light emission of the helicopter search light moves along an elliptic pathway, wherein the control unit in particular is configured for switching the helicopter search light on and off with a frequency such that the light cones emitted by the helicopter search light in combination cover the elliptic pathway substantially completely.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further exemplary embodiments are described with respect to the accompanying drawings, wherein:

(2) FIG. 1 shows a helicopter comprising a helicopter search light in accordance with an exemplary embodiment of the invention;

(3) FIG. 2 shows an exemplary embodiment of a drive unit of a helicopter search light in accordance with an exemplary embodiment of the invention;

(4) FIG. 3a shows a top view of a helicopter search light in accordance with an exemplary embodiment of the invention;

(5) FIG. 3b shows a cross-sectional view through the helicopter search light of FIG. 3a;

(6) FIG. 4 illustrates an exemplary angular intensity distribution of the light emitted by the helicopter search light according to an exemplary embodiment of the invention; and

(7) FIG. 5 schematically illustrates an elliptic cross section of the cone described by the direction of light emission of the helicopter search light.

DETAILED DESCRIPTION

(8) FIG. 1 shows a helicopter 100 flying in a height H above a ground 200. The helicopter 100 is equipped with a helicopter search light 2 providing an adjustable light source and mounted to a front bottom portion of the helicopter 100. A line 70 indicates the main direction of the light emission of the helicopter search light 2.

(9) The helicopter search light 2 comprises a light head 4 mounted to the fuselage of the helicopter 100 by means of a drive unit 3 which is configured to allow rotating the light head 4 around two axes, in particular around two axes extending perpendicular to each other, in order to direct the main light emission direction 70 in the desired direction. The drive unit 3 may be a conventional drive unit 3, as it is disclosed for example in US 2013/0182449 A1, which is incorporated herein by references.

(10) An example of such a conventional drive unit 3 is schematically shown in FIG. 2. In this embodiment, the light head 4 is supported by a mounting arm 7, the mounting arm 7 being pivotable around two axes AR, AP extending perpendicularly to each other. In the exemplary embodiment shown in FIG. 2, the first axis AR extends vertically in the plane of FIG. 2, while the second axis extends horizontally orthogonally to the plane of FIG. 2. The mounting arm 7 is pivotally mounted to a tubular housing 9 for pivoting about the first axis AP between a retracted position in which the light head 4 is inside the housing 9, and a deployed position in which the light head 4 emerges at least in part from the housing 9. The mounting arm 7 is drivable for pivoting about the first axis AP using a first motor 31 for enabling the light head 4 to be pointed in elevation relative to the helicopter 100. In order to point the light head 4 in azimuth relative to the helicopter 100, the housing 9 is rotatable about the second axis by means of a second motor 32. In consequence, the main light emission direction 70 of the helicopter search light 2 may be oriented in the desired direction by appropriately controlling the two motors 31, 32, with the two motors forming the drive unit 3 of the helicopter search light 2 in the exemplary embodiment of FIG. 2. The housing 9 may be received in a cavity formed in an outside wall of the helicopter 100.

(11) In an alternative embodiment, which is not shown in the Figures, the drive unit 3 employs an inverse differential gear assembly for rotating/pivoting the light head. An example of such an inverse differential gear assembly is disclosed by EP 2 832 647 A1, which is also incorporated herein by reference. Many other embodiments of the drive unit are possible as well.

(12) The helicopter search light 2 may have at least two modes of operation, namely a flood light mode and a spot light mode. The spot light mode sometimes is called “search mode” or “pencil mode”. When the helicopter search light 2 is operated in the spot light mode, a narrow beam of light 75, as it is schematically depicted by the dashes lines in FIG. 1, is emitted from the helicopter search light 2 substantially in the direction of the line representing the main light emission direction 70. In the spot light mode, the light emitted from the helicopter search light 2 is bundled along the main light emission direction 70. As a result, the ground 200 in an area A around a position P, at which the line representing the main light emission direction 70 meets the ground 200, is brightly illuminated thereby allowing for a close and thorough inspection by the pilot.

(13) In the flood light mode, the lighting power of the helicopter search light 2 is distributed in a broader cone (not shown) arranged around the main light emission direction 70. Employing the flood light mode, the pilot may inspect a larger portion of the ground than in the spot light mode without adjusting the direction of light emission. Since in the flood light mode the lighting power provided by the helicopter search light 2 is distributed over a larger angular region and thus over a larger area than in the spot light mode, the illuminance of the ground is less than in the spot light mode. Therefore the flood light mode usually is used only when the helicopter 100 is flying in a low height H close to the ground 200. Due to the reduced distance form the ground 200, in this situation, the amount of light reaching the ground 200 in the flood light mode is sufficient for inspection.

(14) FIG. 3a depicts a top view of a light head 4 of a helicopter search light 2 in accordance with an exemplary embodiment of the invention.

(15) The light head 4, whose upper edge is shown as a circle in the top view of FIG. 3a, comprises a cylindrical side wall 5. Six first light emitting elements 10 and six second light emitting elements 20 are arranged within the light head 4, respectively.

(16) Each of the first and second light emitting elements 10, 20 is associated with a corresponding optical system 12, 22. Each of the first light emitting elements 10 has a respective first optical system 12 associated therewith, and each of the second light emitting elements 20 has a respective second optical system 22 associated therewith.

(17) In the exemplary embodiment of FIG. 3a, the first optical systems 12 are of identical design. The respective combinations of the light emitting elements 10, 20 and the optical systems 12, 22 are also cylindrical in shape.

(18) The combinations of the first light emitting elements 10 and the corresponding optical systems 12 have a size that allows for arranging six of these combinations within the light head 4 forming the corners of an equilateral (virtual) hexagon, which is indicated by a dotted line in FIG. 3a.

(19) Six second light emitting elements 20 are arranged in spaces provided between said six combinations, respectively consisting of said first light emitting elements 10 and the associated optical systems 12, and the cylindrical side wall 5 of the light head 4. Each of the second light emitting elements 20 is associated with a respective second optical system 22.

(20) The first light emitting elements 10 and the associated optical systems 12 provide for the highly collimated output light intensity distribution in the spot light mode. The second light emitting elements 20 and the associated optical systems 22 provide for the wider output light intensity distribution in the flood light mode.

(21) The helicopter search light 2 further may comprise a light detector 30, which is arranged at the center of the (virtual) hexagon formed by the first light emitting elements 10. In an alternative configuration, a seventh first light emitting element 10 or a third light emitting element emitting a different kind of light, e.g. light having a different wavelength than the first light emitting elements 10, may be arranged at the center of the hexagon formed by the first light emitting elements 10.

(22) FIG. 3b depicts a cross-sectional view of the helicopter search light 2 shown in FIG. 3a. The cross-sectional plane of FIG. 3b is oriented along line S drawn in FIG. 3a. The cross-sectional view of FIG. 3b in particular illustrates the straight extension (in the top/bottom dimension) of the cylindrical side wall 5 of the light head 4. The helicopter search light 2 has a light emission side LE, depicted as the top side in the viewing plane of FIG. 3b, and a heat discharge side HD, depicted as the bottom side in the viewing plane of FIG. 3b. For said heat discharge, the light head 4 is equipped with a cooling rib structure 6, which forms a heat sink for the light emitting elements arranged within the light head 4.

(23) A first light emitting element 10 is illustrated in the center of the cross-sectional view shown in FIG. 3b. A first optical system 12 is arranged above and around the first light emitting element 10. The first optical system 12 comprises a collimating lens and/or a collimating reflector. As illustrated by the exemplary light rays 13 of FIG. 3b, the collimating lens and the collimating reflector alter the direction of the light rays 13, emitted by the first light emitting element 10, in such a way that they all leave the helicopter search light 2 in substantially the same direction, namely towards the top in the viewing plane of FIG. 3b.

(24) Two second light emitting elements 20 that are arranged adjacent the cylindrical side wall 5 of the light head 4 on opposite sides of the light head 4 are visible in the cross-sectional view of FIG. 3b. In other words, one second light emitting element 20 is arranged adjacent the side wall 5 of the light head 4 on the right side of the helicopter search light 2 in the viewing plane of FIG. 3b, while the other second light emitting element 20 is arranged adjacent the side wall 5 of the light head 4 on the left side of the helicopter search light 2 in the viewing plane of FIG. 3b.

(25) Each of the two second light emitting elements 20 comprises a second optical system 22 associated therewith. The second optical systems 22 are arranged above and around the second light emitting elements 20 in the viewing plane of FIG. 3b. In the exemplary embodiment of FIGS. 3a and 3b, each second optical system 22 comprises a reflector. The reflector is configured for reflecting a portion of the light emitted by the respective second light emitting element 20 towards the main light emission direction, i.e. towards the direction normal to the light head 4, i.e. normal to the whole light head 4. Much of the light of the second light emitting elements 20, however, leaves the light head 4 in an unaltered manner. Overall, the second optical system 22 is designed in such a way that a controlled stray light distribution leaves the light head 4. This is illustrated by the exemplary light rays 23 of FIG. 3b. It is also possible to provide second optical systems 22 that each have a lens for shaping the output light intensity distribution in the flood light mode and for reaching a controlled stray light distribution.

(26) The first and second light emitting elements 10, 20 may comprise LEDs, in particular LEDs emitting light in the visible light range, i.e. light that is visible to the human eye.

(27) The helicopter search light 2 is electrically connected to a control unit 35 (see FIG. 1) including a switching circuit. The switching circuit is electrically coupled to an electrical power source (not shown), as well as to the first and second light emitting elements 10, 20. The switching circuit allows to selectively switch the first and second light emitting elements 10, 20 on and off. The switching circuit in particular allows to selectively switch between the spot light mode, in which the first light emitting elements 10 are switched on and the second light emitting elements 20 are switched off; and the flood light mode, in which the second light emitting elements 20 are switched on and the first light emitting elements 10 are switched off. The switching circuit further may allow to operate the helicopter search light 2 in a combined mode in which both, the first and second light emitting elements 10, 20, are switched on simultaneously. It is also possible that the control unit 35 is integrated into the helicopter search light 2 and that high level command signals, such as “spot light on”, “flood light on” or “anti-bird-collision mode on”, are transmitted from the pilot or from the board computer. The control of the individual light emitting elements 10, 20 is then carried out within the helicopter search light 2.

(28) FIG. 4 illustrates an angular intensity distribution of the light emitted by the helicopter search light 2 according to an exemplary embodiment of the invention operated in the spot light mode.

(29) The light cone emitted by the light source 2 has a half beam angle of approximately 3° and a peak intensity at the center of the beam (at an angle α of 0°) of 310,000 to 320,000 cd. Thus, FIG. 4 shows that the light emitted by the light source 2 is concentrated in a narrow beam having an opening angle of approximately 6°.

(30) When operated as an anti-bird-collision light, the exemplary helicopter search light 2 is operated in the spot light mode for extending the range of light distribution, which is sufficiently bright for scaring away the birds, as far as possible.

(31) For enhancing the effect and for covering an increased area in front the of the helicopter 100, the direction of light emission 70 of the helicopter search light 2 may be moved by operating of the drive unit 3 for moving the direction of light emission 70 along a cone 72, in particular a cone 72 having an elliptic cross section 74 (see FIG. 1). The drive unit 3 in particular may be driven by the control unit 35. Again, the control unit 35 may also be integrated into the helicopter search light 2.

(32) A schematic view of said elliptic cross section 74 in polar coordinates in depicted in FIG. 5. In particular, two extremes of possible pathways 40, 50 are illustrated in FIG. 5.

(33) A first pathway 50 has a horizontal extension (major axis of the ellipse along the x-axis) of +/−20°, and a vertical extension (minor axis of the ellipse along the y-axis) of ⅕ of the horizontal extension, i.e. a vertical extension of +/−4°:

(34) In the example shown in FIG. 5, the light cones 51, 52, 53, 54 of the helicopter search light 2 have an opening angle of 6°, respectively. In order to cover the whole first pathway 50, the helicopter search light 2 is operated to flash 14 times during each cycle of the direction of light emission 70 along the pathway 50.

(35) In an embodiment, the direction of light emission 70 completes a full cycle along the pathway 50 in one second. In case, however, the drive 3 which is used for moving the direction of light emission 70 is not fast enough in order to fulfill this requirement, the dimensions of the cone 72 may be reduced.

(36) An exemplary second pathway 40, which is shown in FIG. 5 extends from −3° to +3° in the horizontal direction (x-axis) and from −1.5° to +1.5° in the vertical direction (y-axis). In this case, only two flashes 41, 42 of the helicopter search light 2 are necessary for covering the whole pathway 40.

(37) It is pointed out that other pathways are possible as well. In particular, elliptic pathways with extensions between the exemplary first pathway 50 and the exemplary second pathway 40 are possible, with the number of light flash positions being adjusted accordingly. Moreover, pathways having shapes that are not elliptic are possible as well.

(38) While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.