Optical device for led-based lamp

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DESCRIPTION

Optical device for LED-based lamp

Background of the invention

The present invention relates to light emitting diodes (LEDs), in particular to optical means for producing various distributions of far field light intensity for LEDs.

Conventional incandescent lamps with less than 100 lumens of output can be compared to the most recent white LEDs, although at a higher price. At this lower end of the lumens range, most incandescent applications are battery powered. It is desirable to have a LED suitable for direct installation instead of a fused flashlight bulb.

LEDs can offer superior luminous efficacy compared to conventional incandescent lamps used in battery operated flashlights. In addition, LEDs are much more tolerant of shocks, vibration and compression stress. Although, at present, its production costs more than those of incandescent type, its useful life is ten thousand times more durable. For greater efficiency, the flashlight bulbs get hot, so these usually last only a few hours until the filament breaks. In addition, the prices of LEDs continue to fall, along with those of electronic control components to manipulate variations in battery voltage.

In fact, LED flashlights are already commercially available, but their optics have to adapt to the geometry of the light-emitting diodes, which only emit to one hemisphere. Conventional LED lamps are unsuitable for direct installation in conventional flashlights, both electrically and optically. LED lamps are electrically inadequate because these are current-powered devices, while batteries are sources of voltage. Typical variations in the voltage of new batteries are sufficient to exceed a tolerable operating voltage range of an LED. This results in such high currents that the ohmic heating inside the tablet exceeds the thermal conduction's ability to eliminate it, resulting in an uncontrolled temperature rise that destroys the tablet. Therefore, a current control device must accompany the lamp.

Conventional LED lamps are optically unsuitable for direct installation in the parabolic reflectors of the flashlights. This is because its bullet-shaped lens configuration forms a narrow beam that would completely miss a nearby parabola. Using instead a non-directional hemispherical emission dome, centered on the light tablet, gives the maximum commercially available diffusion, a lambertian pattern, with a dependence on sen2 θ of the flow surrounded by an angle θ with respect to the axis of the lamp. Because θ for a typical parabolic flashlight reflector extends from 45º to 135º, an LED with a hemispherical pattern does not present a suitable correspondence because its emission drops to zero at only θ = 90º. This would result in a beam that would be very bright on the outside and completely dark halfway inwards. Even worse, this lower beam pattern from a hemispherical LED would need to remain at the focal point of the parabola, several millimeters above the socket in which a conventional incandescent bulb is installed.

Another type of battery-powered lamp uses cylindrical fluorescent lamps. Although the LEDs do not offer even better light efficiency, the fluorescent lamps are however relatively fragile and require dangerously high voltages. A cylindrical low voltage LED-based lamp could advantageously provide the same light output as a fluorescent lamp.

To address the needs set forth above, US Patent Application No. 10 / 461,557, "OPTICAL DEVICE FOR LED-BASED LIGHT-BULB SUBSTITUTE", filed on 12/6/2003, discloses such LED-based lamps with which the current fluorescent and incandescent bulb flashlights can be updated. However, it is often desirable that LED lamps, such as those described in US Patent Application No. 10 / 461,557, have other far-field intensity distributions of interest. Likewise, US Patent Application No. 10 / 461,557 mentions the color mixing function, to make the different wavelengths of the chips have the same relative intensities in all the light that leaves the section of ejection 12. This ensures that viewers will see only the intended metameric tone and not any color of the individual chips. Previously, rectangular mixing rods have been used to transform the round focal point of an ellipsoidal lamp into a uniformly illuminated rectangle, usually in film projectors. In general, polygonal mixing rods worked best with an even number of sides, particularly four and six. However, with color mixing for LEDs, such rods are poorly efficient because half of the lambertian emission of an LED will escape from the base of the rod.

An optical prior art fluid system is disclosed in US 5,555,493 A. US 2,848,601 discloses features that are within the preamble of claim 1.

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Therefore, there is a need in the art for effective and optically suitable LED lamps with various distributions of far-field intensity and having an appropriate conformation of their transfer sections enabling polygonal cross sections to be used.

Summary of the Invention

The present invention advantageously addresses the above needs as well as other needs by providing an optical device for LED-based lamps with configurations for various far-field intensity distributions. The optical device of the present invention is defined in independent claim 1. Additional aspects and preferred embodiments of this invention are defined in the dependent claims.

According to the invention, the ejection section has an upper surface with a profile of an equiangular spiral with a center at an upper edge of said transfer section. The ejection section includes a surface comprising a radial V-groove arrangement. Some embodiments provide that a surface of said transfer section comprises a V-groove arrangement. In addition, the transfer section may be polygonal, may be faceted and / or have other configurations.

In one embodiment, the invention can be characterized as an optical device for distributing a radiant emission of a light emitter comprising a lower transfer section and an upper ejection section that is located on the lower transfer section. The lower transfer section can be operated for placement on the light emitter and can be operated to transfer the radiant emission to the upper ejection section. The upper ejection section is shaped such that the light inside is redistributed out of an outer surface of the upper ejection section at a solid angle substantially larger than a hemisphere, and that it approximates that of a light bulb. incandescent flashlight. The ejection section is located at the same height as the lit filament of the bulb it replaces. It is easier to optically move this emission point, using the transfer section, than to put the LED itself at such a height, which would make heat transfer difficult, among other problems that the present invention addresses advantageously.

A better understanding of the features and advantages of the present invention will be obtained by referring to the following detailed description of the invention and the accompanying drawings, which set forth an illustrative embodiment in which the principles of the invention are used.

Brief description of the drawings

The foregoing as well as other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, which is presented together with the following drawings, in which:

FIG. 1a to 38b are cross-sectional views of LED lamps having various configurations of transfer and ejection lens sections (hereinafter referred to as virtual filaments), where each cross-sectional view is accompanied, respectively, by the far field pattern of the individual configuration. FIG. 1 to 36 and 38 to 40 are not within the scope of claim 1. FIG. 39 It is a perspective view of a linear V-groove arrangement for an illustrative purpose. FIG. 40 is a diagram of the angles reflected by a linear V-groove arrangement. FIG. 41 is a perspective view of a radial V-groove arrangement. FIG. 42a is a perspective view of the configuration of FIG. 37a according to the present invention. FIG. 42b is a perspective view showing the list of vectors on the configuration of FIG. 42a in accordance with the present invention. FIG. 43 is a perspective view of the structure of a V groove on a curved surface in accordance with the present invention. FIG. 44 is a perspective view of a virtual filament with a radial arrangement of curved V-grooves arranged above in accordance with the present invention. FIG. Four. Five it is a perspective view of a virtual filament with a linear arrangement of V-grooves on its transfer section according to the present invention. FIG. 46 is a perspective view of a six-sided barrel-shaped virtual filament for an illustrative purpose. FIG. 47a and 47b are a side and perspective view, respectively, of a sixteen-sided virtual filament for an illustrative purpose. FIG. 47c -e show emission patterns of blue (465 nanometers), green (520 nanometers) and red (620 nanometers), respectively, of the examples of FIG. 47a-b, in the various cylindrical azimuths. FIG. 48a and 48b are a side and perspective view, respectively, of another sixteen-sided virtual filament, with a grooved ejection section for an illustrative purpose. FIG. 48c illustrates a 300 ° emission pattern that is produced by the collar of FIG. 48th

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FIG. 49a and 49b are a side and perspective view, respectively, of a faceted virtual filament that mixes the different wavelengths of a tricolor LED for an illustrative purpose.

Corresponding reference characters indicate corresponding components in all of the various views of the drawings, especially the explicit label in FIG. 1a of the LED packet 20 that is implied throughout FIG. 2nd to 38th.

Detailed description of the preferred embodiments

The following description of the best mode contemplated at present of practicing the invention is not to be taken in a limiting sense, but is simply offered in order to describe the general principles of the invention. The scope of the invention should be determined with reference to the claims.

The present embodiments provide light sources with previously defined far field intensities. The present embodiments can be used in numerous applications. For example, in some applications, the embodiments may be used to replace and / or replace other types of light sources, such as compact light sources, incandescent light sources, fluorescent light sources and other light sources. As an additional example, the present embodiments can be used to replace incandescent light sources in flight lights and other devices that use incandescent light sources.

The surface faceting configuration presented herein in FIG. 49A and FIG. 49B may be used in variations of all of the non-faceted embodiments shown herein in order to achieve color mixing and other benefits thereof.

FIG. 1a to 38b are cross-sectional views of LED lamps having various configurations of transfer and ejection lens sections (hereinafter referred to as virtual filaments), where each cross-sectional view is accompanied, respectively, by the far field pattern of the individual configuration.

Only FIG. 1b has the labels that are implicit in all of the output patterns of the preferred embodiments in the following figures: the semicircular polar representation 2700 shows the normalized far-field distribution 2701 on the semicircular angular scale 2702, with an angle outside the axis, where zero indicates the direction on the axis, and 180º the opposite direction, fully backwards. This is possible for those preferred embodiments that have a certain lateral extension so that the 180 ° are not hindered by the source.

Only in FIG. 1a, the light source is designated as the LED package 20 with the LED chips 22, 23, and 24, but the same package sketch is illustrated without labels in all subsequent virtual filament figures. This LED package only represents one possible way in which the present invention uses multiple light emitters. Such multiple chips may have identical or different wavelengths. For example, the different wavelengths may be red, green and blue color wavelengths that span a color gamut for human color vision, or amber, red and red wavelengths Infrared for night vision devices, or other combinations of different wavelengths.

Similarly, only in FIG. 1a, the focus position of the ellipse segment 271 is shown by a star 271f. In all subsequent figures, the focus of the profile of the transfer section is also close to the bottom point of the same curve on an opposite side of a central axis.

FIG. 1a shows a virtual filament 270 comprising a transfer section of compound elliptical concentrator (hereinafter CEC, compound elliptical concentrator) 271, and an ejection section comprising a lower cone inclined outward 272 and an upper cone inclined inward 273 FIG. 1b shows that the far-field distribution of this preferred embodiment reaches the maximum in the forward direction with an amplitude of ± 20 °.

FIG. 2a shows a virtual filament 280 comprising a CEC transfer section 281, multiple stacked toroids 282 and an ejection section 283, which is shaped as an equiangular spiral with the origin at point 283f. FIG. 2b shows that the maximum far field strength of this preferred embodiment is at angles of about 50 ° to 60 ° off the axis, a so-called bat-wing distribution.

FIG. 3a shows a virtual filament 290, comprising the transfer section of CEC 291, cones 292 and 293, and equiangular spirals 294 and 295. The predominantly horizontal equiangular spiral 294 has its center at center point 294f. The equiangular spiral profile 295 has an opposite center 295f. FIG. 3b shows the far-field distribution of this preferred embodiment, reaching the maximum at 40 ° off the axis and for the most part confined to the range of 10 to 70 °, also with a secondary lobe of 150 to 170 °.

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FIG. 4a shows a virtual filament 300 comprising a section of CEC 301, a flat part 302, an equiangular spiral in a lateral direction 303 with its center at point 303f, and an upper equiangular spiral 304 with the center at point 304f. FIG. 4b shows a subtle adjustment of the far field resulting from the perceptible modification of the profile, as shown in FIG. 4a, of the preferred embodiment shown in FIG. 3rd. FIG. 4b shows that the far-field distribution of this preferred embodiment has a primary maximum over a main lobe between 40 ° and 60 ° outside the axis, and a secondary maximum over a secondary posterior lobe that extends between 160 ° and 170 °, almost backward. The next preferred embodiment is a modification of this.

FIG. 5a shows a virtual filament 310 with a CEC transfer section 311, a flat ring 312, an equiangular spiral 313 with the center at the axial point 313f, and an upper equiangular spiral 314 with the center at the opposite point 314f. In addition to the elements in correspondence with those of FIG. 4a, an abrupt cone inclined inward 315, a shallow cone inclined upward 316, and a flat top circle is shown

317 The normalized far-field pattern of this preferred embodiment differs significantly from the previous one, as shown in FIG. 5b, with a fluctuating forward lobe and a backward lobe with half intensity.

Further deepening the subject of minor modifications, FIG. 6a shows a virtual filament 320 comprising a CEC transfer section 321, a flat ring 322, an equiangular spiral 323 with an axial position of its center as shown by the star 323 f, an upper equiangular spiral 324 with the center at the opposite point 324f, and a new element - the central upper equiangular spiral 327, also with the center at 324f. Similar to FIG. 5a, the virtual filament 320 also comprises an abrupt cone tilted inward 325 and a shallow cone upward 326. By FIG. 6b shows that the standardized far-field pattern of the preferred embodiment of FIG. 6a is mainly between 30 ° and 50 ° off-axis, with a posterior lobe of 120 ° to 170 °, with a reduced forward emission compared to FIG. 5b

FIG. 7a illustrates a comparative example that is the result of minor modifications of virtual filament 320 of FIG. 6a. FIG. 7a is a cross section of the virtual filament 330, which comprises a CEC transfer section 331, an inclined conical section 332, a horizontal equiangular spiral 333 with the center at the axial point 333f, an abrupt conical edge 335, a vertical equiangular spiral 334 with the opposite center 334f, and a central cone 336. FIG. 7b shows its far-field intensity concentrated in a forward lobe within ± 20 ° of the axis, with an intense backward lobe reaching the maximum at 150 °.

Continuing with the subject of component modifications, FIG. 8a illustrates a virtual filament 340 comprising a CEC transfer section 341, a flat ring 342, an abrupt cone tilted inward 335, a shallow cone tilted down 346, an outer edge 348, a horizontal equiangular spiral 343 with the center at the point outside the axis 343f, a vertical equiangular spiral 344 with the center at the opposite point 344f, and an upper equiangular spiral 347, also with the center at the opposite point 344f. FIG. 8b shows that its far-field pattern has a collimated anti-axial beam and a forward beam of ± 30 °, wider.

FIG. 9a illustrates a virtual filament 350 comprising a transfer section of CEC 351, double tapered flanges 352 and an upper tapered notch 353. FIG. 9b shows that its far-field pattern has intense forward and backward lobes, but a certain lateral emission.

FIG. 10a illustrates a virtual filament 360 comprising a CEC transfer section 361, a conical flange 362, an upper equiangular spiral notch 363 with the center at the proximal point 363f, and a cylindrical flange 364. FIG. 10b shows how the backward emission of FIG. 9b has been removed.

FIG. 11a illustrates another variation of FIG. 10th A virtual filament 370 comprises the CEC transfer section 371, double conical flanges 372, a central conical notch 373, located in the central cylinder 374. The far-field pattern of FIG. 11b shows a main lobe of ± 30 ° forward and a small secondary lobe at 125 °.

FIG. 12a illustrates a variation of the proportions of components in the comparative example of FIG. 11a. The virtual filament 380 comprises a CEC transfer section 381, double conical flanges 382, ​​and a central conical notch 383. The far field intensity pattern of FIG. 12b shows the same global forward and backward prominence of FIG. 9b, with differentiated details.

FIG. 13a illustrates a virtual filament 390 comprising a CEC transfer section 391, a spherical section 392, and a central conical notch 393. Both surfaces 392 and 393 are diffusers, since the rays coming from the interior and passing through them are dispersed from diffuse shape in the air. FIG. 13b shows an intense forward lobe of ± 40 ° superimposed on a weaker emission that is almost omnidirectional.

FIG. 14a illustrates a virtual filament 400 comprising the transfer section of CEC 401, an abruptly inclined cone 402, the outer equiangular spiral 403 with the center axially located at 403f, and an inner equiangular spiral 404 with the center at the 404f proximal point. As shown in FIG. 14b, its far-field intensity pattern has no backward energy, and approximates to some extent a

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Lambertian pattern.

In a variant of the previous figure, FIG. 15a illustrates a virtual filament 410 comprising a CEC transfer section 411, a cylindrical stack 412 of multiple toroidal sections 412t, an inner equiangular spiral 414 with the center at the proximal point 414f, and an upper curve 413 that is adapted to refract rays that come from 414f and that are reflected in 414 and direct them tangentially to 413. FIG. 15b shows that the resulting far-field pattern is mostly forward, within ± 30 °.

FIG. 16a illustrates a virtual filament 420, comprising a CEC transfer section 421, a cylinder 422, a tapered notch 423 in the shallower upper cone 424. FIG. 16b shows that its far-field pattern is mostly between 10º and 20º off the axis.

FIG. 17a illustrates a virtual filament 430, comprising a CEC transfer section 431, an outer cone 432, and an inner conical notch 433. Despite the small differences with respect to FIG. 16a, the far field pattern of FIG. 17b is considerably different from that of FIG. 16b

FIG. 18a illustrates a virtual filament 440, comprising a CEC transfer section 441, an outer cone 442, and an inner conical notch 443. Despite the small differences of this example with respect to that of FIG. 17a, the far field pattern of FIG. 18b is narrower than that of FIG. 17b

FIG. 19a illustrates a virtual filament 450 comprising a CEC transfer section 451, a spline type adjustment curve 452, a central equiangular spiral 453 with the center at the proximal point 453f, and a surrounding upper conical notch 454. FIG. 19b shows that its far-field pattern is predominantly forward, with ± 20º at the point at medium power.

FIG. 20a illustrates a virtual filament 460 comprising a CEC transfer section 461, a spherical section 462 with a radius 462r that is equal to 0.38 times the height of section 461, and a central equiangular spiral 463 with the center at the proximal point 463f. FIG. 20b shows that its far-field pattern is between 10 ° and 60 ° outside the axis.

FIG. 21a illustrates another similar configuration, a virtual filament 470 comprising a CEC transfer section 471, a spherical section 472 with a radius 472r that is 0.7 times the height of section 471, and a central equiangular spiral 473 with the center at the proximal point 473f. FIG. 21b shows that the far field pattern has narrowed significantly with respect to the previous one.

FIG. 22a illustrates another similar configuration, a virtual filament 480 comprising a CEC transfer section 481, a spherical section 482 with a radius 482r that is 0.8 times the height of section 481, and a central equiangular spiral 483 with the center at the proximal point 483f. The spherical section 482 is partially covered with multiple convex toroidal microlenses 482t. FIG. 22b shows that the far-field pattern experiences only a minor change from the previous one, with a narrowing of the central beam compared to that seen in FIG. 21b

FIG. 23a illustrates a virtual filament 490 comprising a CEC transfer section 491, a spherical section 492 with a radius 492r that is 0.62 times the height of section 491, a section 492 that is completely coated by multiple toroidal microlenses 492t, and a central equiangular spiral 493 with the center at the proximal point 493f. FIG. 23b shows how these microlenses greatly widen the far-field pattern with respect to that of FIG. 22b

FIG. 24a illustrates a virtual filament 500 comprising a CEC transfer section 501, a spherical section 502 with a radius 502r that is 0.76 times the height of section 501, a section 502 that is coated by multiple convex toroidal microlenses 502t, and a central equiangular spiral 503 with the center at the proximal point 503f. FIG. 24b shows that the far field pattern is not greatly changed with respect to that of FIG. 23b, with section 502 having a radius somewhat larger than that of section 492 of FIG. 23rd

FIG. 25a illustrates a virtual filament 510 comprising a transfer section of CEC 511, a spherical section 512 with a radius 512r that is equal to the height of section 511, a section 512 that is coated by multiple convex toroidal microlenses 512t, and a central equiangular spiral 513 with the center at the proximal point 513f. FIG. 25b shows that the far field pattern is now considerably changed with respect to that of FIG. 24b, due to the radius of section 512, larger than that of section 502 of FIG. 24th

FIG. 26a illustrates a virtual filament 520 comprising a CEC transfer section 521, a lower spline type adjustment curve section 522, a central equiangular spiral 523 with the center at the proximal point 523f, and an outer cylindrical section 524 which is cover with multiple convex toroidal microlenses 524t. FIG. 26b shows a very broad pattern that does not vary much up to 130 ° and is only halved to 180 °.

FIG. 27a illustrates a virtual filament 530 comprising a transfer section of CEC 531, a section

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conical 532, a central equiangular spiral 533 with the center at the proximal point 533f, and a cylindrical cell 534 that is lined by multiple convex toroidal microlenses 534t. FIG. 27b shows that this replacement of a spline-type adjustment curve adapted by a cone results in the far-field pattern falling at angles near the axis, compared to FIG. 26b. In the following figure, there is no microlens of this type.

FIG. 28a illustrates a virtual filament 540 comprising a CEC transfer section 541, a conical section 542, a central equiangular spiral 543 with the center at the proximal point 543f, and an outer cylinder 544. FIG. 28b shows that the far-field pattern of this preferred embodiment is much narrower without the microlenses 534t of FIG. 27a.

FIG. 29a illustrates a virtual filament 550 comprising a CEC transfer section 551, a shallow upward cone 552, a central equiangular spiral 553 with the center at the proximal point 553f, and an outer concave spline-type adjustment curve 554. FIG. 29b shows its far-field pattern, with substantial axial emission.

FIG. 30a illustrates a virtual filament 560 comprising a CEC transfer section 561, a flat ring 562, a central equiangular spiral 563 with the center at the proximal point 563f, and an outer cylinder 564. FIG. 30b shows its far field pattern.

FIG. 31a illustrates a virtual filament 570 comprising a CEC transfer section 571, a flat ring 572, a central equiangular spiral 573 with the center at the proximal point 573f, and an outer tapered edge 574. FIG. 31b shows that the far field emission is predominantly forward.

FIG. 32a illustrates a virtual filament 580 comprising the CEC transfer section 581, a flat ring 582, an upper equiangular spiral 583 with the center at the proximal point 583f, an outer cylinder 584 that is coated with concave toroidal microlenses 584t, and a upper central cone 585. FIG. 32b shows that its far-field pattern is predominantly forward, with full intensity within ± 30 °.

FIG. 33a illustrates a virtual filament 590 comprising an equiangular spiral transfer section 591 with the center at the opposite point 591f, an outward cone 592, a central notch 593 that is shaped as a higher order polynomial, and an abrupt outer cone 594, and surfaces 595, 596 and 597 that form a groove. Its far field pattern is shown in FIG. 33b, with a sharp cut at 150º off the axis and only a 2: 1 variation with respect to a uniform intensity at smaller angles.

FIG. 34a illustrates a virtual filament 600 comprising an equiangular spiral transfer section 601 with the center on the opposite point 601f, an adjustment curve of the protruding cubic spline type 602, and a central equiangular spiral 603 with the center at the proximal point 603f . Its far field pattern is shown in FIG. 34b, and will be compared with those of the following two comparative examples, in which the cubic spline type adjustment curve stands out more.

FIG. 35a illustrates a virtual filament 610 comprising an equiangular spiral transfer section 611 with the center at the opposite point 611f, an adjustment curve of the protruding cubic spline type 612, and a central equiangular spiral 613 with the center at the proximal point 613f . FIG. 35b shows that its far field pattern has a reduced axis intensity compared to FIG. 34b

FIG. 36a illustrates a virtual filament 620 comprising an equiangular spiral transfer section 621 with the center at the opposite point 621f, an adjustment curve of the protruding cubic spline type 622, and a central equiangular spiral 623 with the center at the proximal point 623f . FIG. 36b shows that its far-field pattern has a reduced axis intensity compared to FIG. 35b

FIG. 37a illustrates a virtual filament 630 comprising an equiangular spiral transfer section 631 with the center at the opposite point 631f, a flat ring 632, a central equiangular spiral 633 with the center at the proximal point 633f, and an outer cylinder 634. FIG. 37b shows that its far field pattern has no axis intensity. FIG. 37b can be compared with FIG. 30b, given the similarity of FIG. 37a with FIG. 30th

FIG. 38a illustrates a virtual filament 640 comprising the equiangular spiral transfer section 641 with the center at the opposite point 641f, a lower conical section 642, an upper conical section 643, and an outer spline type adjustment curve 644. FIG . 38b shows the far field pattern. Cone 642 is a white diffuse reflector with lambertian dispersion, such that, unlike diffuse transmissive surface 392 of FIG. 13a, this only reflects the light that falls on it.

Previous examples have a complete circular symmetry, because these are formed by a 360º cylindrical profile sweep. Therefore, these do not have any azimuthal variation, only the radial variation of the profile. This is because the 360º output patterns of the real world do not require azimuthal variation. However, there is a type of azimuthal variation that does not have any azimuth intensity variation in its light output. This is the V groove.

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The geometry of a linear V-groove arrangement is shown in FIG. 39. The arrangement of V-slits at 90 ° reflective 650 is limited by the plane x -z 651 and the plane y -z 652. The incoming beam 653 is reflected in the first slit wall 650a to become a bouncing beam 654 , and then reflected in the second slit wall 650b to become a projecting beam 655. The incoming beam 653 has a projection 653yz on the boundary plane 652 and a projection 653xz on the boundary plane 651. Bounce beam 654 has a projection 654yz on the boundary plane 652 and a projection 654xz on the boundary plane 651 The projecting beam 655 has a 655yz projection on the boundary plane 652 and a 655xz projection on the boundary plane 651.

FIG. 39 also shows the normal macrosurface N, which is perpendicular to the plane of the V-groove arrangement 650, which in the case of FIG. 39 is the xy plane. The directions of the projected rays 653xz and 655xz obey the law of reflection from a flat mirror with the same surface normal. But on the yz plane 652, the outgoing projection 655yz has the opposite direction of the incoming projection 653yz, which has an angle Ψ of incidence on the plane. Therefore, the linear V-groove arrangement 650 acts as a combination of a retroreflector and a conventional reflector. That is, when the incoming ray 653 has the direction vector (p, q, r), then the outgoing ray 655 has the direction vector (p, -q, -r). However, this condition is only valid for those rays that experience two reflections. Of all the possible input beam directions, the fraction that is reflected twice is 1 -tan (Ψ).

The relevant configuration for the present invention is when the surface 650 is the separation surface between a transparent dielectric, such as acrylic or polycarbonate, which is above the surface (i.e., positive z) and the air below it. . The particular case shown in FIG. 39 It is also valid for a total internal reflection, which takes place whenever the angle of incidence θ of a beam on the separation surface of the electric-air exceeds the local critical angle.

θc = arcsen (1 / n) for the refractive index n. Because the normal unit vectors on the 2 sides of the slits are (0, √ 0.5, √0.5) and (0, -√ 0.5, √ 0.5), the condition for internal reflection total can be expressed in vector form as

(p, q, r) · (0, ± √ 0.5, √ 0.5) <cos θc

that can be rearranged to give

| q | + √ (1-p2-q2) <√ [2 (1-1 / n2)]

FIG. 40 shows a contour plot 660 with the abscissa p and the ordinate q. Legend 661 shows the fraction of the rays that are retroreflected by total internal reflection. For p = 0, the maximum value of q for which there is a total internal reflection for the 2 reflections is

| cos -1 q | <45º -θc

which is equivalent to a vertical width of ± 2,8º for acrylic (n = 1,492) and ± 6º for polycarbonate (n = 1,585). These small angles are how much such incoming rays are not in the 651 plane.

More relevant to the present invention is the radial V-groove arrangement 670 shown in FIG.

41. The crest lines 671 and the valley lines 672 are the boundaries of the flat triangles 673, which meet at the crest lines and the valley lines with angles that include 90 ° 674.

In FIG. 37a, the generatrix curve of the upper surface 633 has an equiangular spiral shape. It is possible to impose a radial V-groove arrangement on such a surface, such that the crest lines 671 of FIG. 41 would become curved down, sinking the center point.

FIG. 42a is a perspective view of the preferred embodiment of FIG. 37a. The virtual filament 680 comprises an equiangular spiral transfer section 681, an upper equiangular spiral surface 683, and a cylindrical side surface 684, whose apparently polygonal shape is a pictorial artifact. Twelve crest curves 683c are shown, to correspond with the crest lines 671 of FIG. 41.

FIG. 42b is another perspective view of the same preferred embodiment, but with surfaces 683 and 684 of FIG. 42nd withdrawals. Twelve crest curves 683c are shown, one shown with a tangent vector t, a normal vector n, and its vector product, the binormal vector b = tx n. If a peak curve is the path followed by a particle at a uniform velocity, then its velocity vector is along the tangent vector t and its acceleration vector is the opposite of the normal vector n. The latter is such that it will coincide with the normal surface area. Because each crest curve is in a plane, the binormal vector b is constant, which means that the crest curves have zero torsion.

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FIG. 43 is a perspective view of the construction of a V groove on a curved surface in accordance with the present invention.

By modifying surface 683 of FIG. 42a so that it becomes like the radial groove arrangement 670 of the

5 FIG. 41, the curvature of the crest lines would cause the groove surfaces to become flat. In fact, such surfaces would be the envelopes of elementary planes that come from each point on the curve at an angle of 45 °, as shown in FIG. 43. The incompletely swept equiangular spiral surface 690 is identical to the surface 683 of FIG. 42a. Part of the sweep is not finished, so that the crest curve 691 can be clearly seen. Three 692 elementary flat crests are tangent to it with about

10 interior angles of 90º. A crest curve is specified by the parametric function P (t), in which t is the length of the path along said crest curve, with a normal vector n (t) and a binormal vector b (t) . Any point X on a 45º plane that touches the crest curve at P (t) is specified by

(X -P (t)) · (n (t) ± b (t)) = 0 (1)

fifteen where '±' refers to that there are two planes at 45 ° of this type that correspond to the walls of a V-groove at 90 °. The variation of t gives a family of such planes. In order to calculate the envelope surface for this family of planes, equation (1) is differentiated from the parameter t, giving

<figref>image 1</figref>

The tern of orthogonal vectors that is formed by the unit vectors specified parametrically t (t), n (t) and b (t) is called the Frenet frame of the curve that follows as t varies. Each of these three vectors has a definition that is based on various derivatives of the equation for P (t). The differentiation of

25 these definitions with respect to the Frenet equations, which are well known in differential geometry. A laborious combination of Frenet's equations with equation (2), and the elimination of t, finally gives

(X -P (t)) · t (t)) = 0 (3)

30 Equation (3) and equation (1) must be fulfilled simultaneously for each point X of the envelope surface. Equation (3) states that the same XP vector is normal with respect to the tangent vector t, while equation (1) implies that the XP vector is normal with respect to ±. Therefore, XP, for a point that satisfies equations (1) and (3), must be in the nb direction, because n and b are orthogonal unit vectors such that (nb) · (n + b) = 0, that is,

35 X -P (t) = s (-n (t) ± b (t)) (4)

This is the parametric equation of the two envelope surfaces of the crest. The radial parameter is t and the transverse parameter is s, with a crest for + b (t) and the other for -b (t). The curves 683c of FIG. 42b will be

40 Crest curves if s> 0 is taken for both ridges (with s = 0 for the crest curves) and these will be valley curves if s <0 (with s = 0 for the valley curves in the present case). More pertinently,

X (t, s) = P (t) + s (-n (t) ± b (t)) (5)

Four. Five it is the envelope surface equation as a function of the crest equation P (t), and its normal and binormal vectors. The parameter s extends to the value of s that occurs at the bottom of the slit, where it meets the corresponding point on the next ridge.

The result of this differential geometry test is that each of the planes of FIG. 43 contributes with

fifty thick lines 693 to the envelope surface of the curved V-groove. The thick lines 693 of FIG. 43 represent, in fact, the second term in equation (5). If the successive lines 693 intersect as they leave very close points, then the resulting envelope surface may have undulations or even caustics (which are physically unworkable). In the present invention, any mathematical anomaly of this type would be too far from the crest curve to be relevant.

55 FIG. 44 is a perspective view of a virtual filament 700, comprising an equiangular spiral transfer section 701, radial V-grooves 702, and a cylindrical side wall 703. For clarity, only twelve V-grooves are shown, but a device Real can have many more. The usefulness of such indentations is that they allow the designer to avoid using a coated reflector.

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FIG. 45 shows a virtual filament 710, comprising a transfer section 711 with longitudinal V grooves, and an ejection section 703. As shown in FIG. 45, V grooves can also be used on the transfer section of the present invention, allowing a cylindrical shape to be used.

Accurate color mixing attempts to make different wavelengths from chips have the same relative intensities in all the light that exits the ejection section 12. This ensures that viewers will see only the intended metameric tone and not any color of the individual chips. Previously, rectangular mixing rods have been used to transform the round focal point of an ellipsoidal lamp into a uniformly illuminated rectangle, usually in film projectors. In general, polygonal mixing rods worked best with an even number of sides, particularly four and six. However, with color mixing for LEDs, such rods are poorly efficient because half of the lambertian emission of an LED will escape from the base of the rod.

The following comparative examples correct this lack by appropriately shaping its transfer section. This conformation allows polygonal cross sections to be used in the present invention.

FIG. 46 illustrates a virtual filament 720, comprising a hexagonal transfer section 721 and a hemispherical ejection section 722. Inside a package 723 are a red LED chip 723r, a green chip 723g and a chip 723b blue. The transfer section 721 comprises a lower expansion section 721b, a middle section 721m with a constant cross section, and an upper contraction section 721u. The shape of sections 721b and 721u acts to prevent the escape of lightning that would allow a constant cross-section if it extended over the entire length of transfer section 721. Similar to the slits in FIG. 44 and FIG. 45, a polygonal transfer section would constitute a deviation from complete rotational symmetry.

FIG. 47a is a side view of a virtual filament 730 comprising a six-sided off-axis ellipsoid 731, a conical ejection section 732, and mounting brackets 734. FIG. 47b is a perspective view of the same preferred embodiment, which also shows an upper surface of spline type adjustment curve 733. FIG. 47c shows the blue emission pattern (465 nanometers) of this preferred embodiment, to the various cylindrical azimuths, an azimuth at 0 ° which is indicated by reference number 735, an azimuth at 45 ° which is indicated by the reference number 736, an azimuth at 90 ° which is indicated by reference number 737, and an azimuth at 135 ° which is indicated by reference number 738, and as indicated in the legend in the upper right corner. FIG. 47d shows the green emission pattern (520 nanometers) of this preferred embodiment, to the various cylindrical azimuths 735-738 and as indicated in the legend in the upper right corner. FIG. 47E shows the red emission pattern (620 nanometers) of this preferred embodiment, to the various cylindrical azimuths 735-738 and as indicated in the legend in the upper right corner.

FIG. 48a is a side view of a virtual filament 740 comprising a six-sided off-axis ellipsoid 741, a conical ejection section 742, a conical collar 744, and a cylindrical connector 745. FIG. 48b is a perspective view of the same example 743. The objective of narrowing by means of collar 744 is to produce the emission pattern of 300 ° 747 shown in FIG. 48c

FIG. 49a is an exploded side view of a faceted virtual filament 750 and a tricolor 755 LED package that is inserted in and optically coupled to filament 750. The transfer sections beyond the polygonal shape are more complex deviations from circular symmetry The virtual filament 750 comprises an exit section encompassed by arrow 751, a transfer section 752 and mounting brackets 753. The virtual faceted filament 750 is an individual piece of plastic, such as acrylic, whose surface is covered by flat facets 754. The two mounting brackets 753 are designed to be close to the outer surfaces of the LED package 755, to aid in the alignment and bonding of virtual filament 750 to package 755. An adhesive is applied to the inner side walls of brackets 753 for connection with LED package 755. In this case, the inner side wall of each support 753 has a surface that is substantially parallel to the proximal edge surface of the LED package 755. An optical coupling of the lower part of the virtual filament 750 with the upper surface of the LED package 755 can be achieved by various means, such as the use of optical adhesives, optical curing and non-curing gels (such as those provided by Nye Optical Fairhaven, Ma) products or index adaptation liquids (such as those provided by Cargille Laboratories of Cedar Grove, NJ).

FIG. 49b is a perspective view of an exploded part showing the rectangular LED package 755 removed from the virtual filament 750. Inside the reflector cup 757 there is a red chip 758r, a green chip 758g and a blue chip 758b. Cup 757 is loaded with a transparent epoxy resin (not shown) to the top 756 of package 755. The upper part 756 is optically joined with the lower part of the faceted virtual filament 750. This three-chip configuration can be used with the present invention incorporating multiple light sources. The three chips shown too

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They could be amber, red and infrared, suitable for illuminators compatible with night vision devices, and other combinations.

In general, the base of a virtual mixing filament is larger than the emission surface of the LED of

5 RGB that illuminates it. In one example, the inside diameter of the six-sided polygonal base of the mixing optics 750 is 20% larger than the diameter of the circular outlet opening of the RGB 755 LED. In case the LED of RGB 755 has a non-circular exit opening, the virtual filament base becomes large enough to completely cover the LED exit opening.

10 Although the invention disclosed herein has been described by means of specific embodiments and applications thereof, those skilled in the art could make numerous modifications and variations therein without departing from the scope of the invention as set forth in The claims.