CN107035977B - Light emitting device - Google Patents

Abstract

A light emitting device comprising: an LED-based light source; a spherical, spheroidal, ovoid, egg-shaped, or toroidal diffuser that produces a lambertian light intensity distribution output at any point on a surface of the diffuser in response to illumination inside the diffuser; and a base including a base connector. The LED-based light source, diffuser, and base are secured together as a unitary LED lamp that can be installed in a lighting socket by connecting the base connector and the lighting socket. The base is operatively connected with the LED-based light source in the unitary LED lamp to power the LED-based light source with power received at the base connector.

Description

Light emitting device

The present application is a divisional application of a chinese patent application having an application number of 201080054756.4 entitled "Light Emitting Diode (LED) -based lamp" (international patent application having an international application date of 10/01/2010 and an international application number of PCT/US2010/051109, entering the chinese national phase at 06/01/2012).

Technical Field

The present application relates to the field of lighting, solid state lighting, and related fields, and more particularly to a light emitting device, such as a Light Emitting Diode (LED) based lamp.

Background

The integral incandescent and halogen lamps are designed as direct "plug-in" components that mate with the lamp socket via a threaded edison base connector (sometimes referred to as an "edison base" in the context of an incandescent light bulb), a bayonet base connector (i.e., a bayonet base in the case of an incandescent light bulb), or other standard base connector to receive a standard power source (e.g., 110 volt ac at 60Hz in the united states, or 220V ac at 50Hz in europe, or 12 or 24 or other dc voltages). The integrated lamp is constructed as an integrated package that includes any components required for operation by a standard power source received at the base connector. These components are minimal in the case of integral incandescent and halogen lamps, since the incandescent filament can typically be operated with standard 110V or 220V ac or 12V dc power supplies, and the incandescent filament operates at high temperatures, effectively releasing waste heat into the environment. In such lamps, the base of the lamp is simply a base connector, such as the edison base of an "a" incandescent bulb.

Some integral incandescent or halogen lamps are constructed as omni-directional light sources, intended to provide a substantially uniform intensity distribution versus angle in the optical far field, which is 5 or 10 times larger than the linear dimension of the light source, or which is typically more than 1 meter away from the lamp, and find different applications such as table lamps, decorative lamps, chandeliers, ceiling lamps, and other applications that require uniform distribution of light in all directions.

Referring to fig. 1, a coordinate system is described herein for describing the spatial distribution of illumination produced by a lamp for producing omnidirectional illumination. The coordinate system is a spherical coordinate system and a reference lamp L is shown in fig. 1, which lamp is an "a" -type incandescent lamp in the embodiment shown, having an edison base EB, which may be E25, E26 or E27, for example, wherein the numbers indicate the outer diameter of the thread windings on the base EB, expressed in millimeters. For purposes of describing the far field illumination distribution, the lamp L may be considered to be located at point L0, which coincides with the position of a incandescent filament, for example. Adopting a common spherical coordinate symbol in the geographic field, and passing through an elevation coordinate theta, a latitude coordinate theta and an azimuth coordinate or a longitude coordinate

The illumination direction will be explained. However, unlike the convention in the geographic arts, the elevation or latitude coordinate θ used herein ranges from 0 ° to 180 °, where: θ 0 ° corresponds to "geographical north" or "N". This is convenient because illumination in the direction θ of 0 ° is allowed to correspond to forward light. North, i.e., the direction from point L0 through geographical north, θ is 0 °, also referred to herein as the optical axis. With this notation, θ ═ 180 ° corresponds to "geographic south" or "S", or, in a lighting environment, to rearward light. The elevation or latitude θ 90 ° corresponds to the "geographic equator", or lateral light in a lighting environment.

With continued reference to FIG. 1, azimuth or longitude coordinates may also be defined for a specified elevation or latitude θ

Each of which is orthogonal to the elevation or latitude theta. By geographic symbol, orientation or longitude coordinate

Is in the range of 0 ° to 360 °. Just north or south, i.e. when θ is 0 ° or θ is 180 ° (in other words along the optical axis), the azimuth or longitude coordinate has no meaning or, more precisely, can be considered as degenerated. Another "special" coordinate is θ,90 °, which defines a plane transverse to the optical axis and containing the light source (or more precisely, the nominal position of the light source including far-field calculations, such as point L0 of the illustrative embodiment shown in fig. 1). Over the entire longitudinal span

It is generally easy to achieve a uniform light intensity because a light source is directly constructed which is rotationally symmetric around the optical axis (i.e. around the axis θ — 0 °). For example, incandescent lamp L suitably employs a incandescent filament located at coordinate center L0, which may be designed to emit substantially omnidirectional light, thereby providing a relative azimuth

A uniform illumination intensity distribution for any latitude. Providing relative orientation

A lamp that provides a uniform illumination intensity distribution for any latitude is sometimes referred to as providing an axisymmetric light distribution.

However, it is often not practical to achieve ideal omnidirectional illumination at corresponding elevation or latitude coordinates θ. For example, an "a" type incandescent bulb L includes a threaded edison base EB that is located on the optical axis "behind" the light source location L0, thereby blocking light emitted rearward, and therefore the incandescent bulb L cannot provide ideal omnidirectional light up to θ 180 ° relative to the latitude coordinate θ. Nevertheless, commercial incandescent lamps can provide a uniform intensity over the latitude span θ [0 °,135 ° ] within about ± 20% as specified in the recommended version of the energy star standard for monolithic LED lamps (draft 2, 5/9/2009; hereinafter "recommended version of the energy star standard"). It is generally considered to be an acceptable uniformity of the illumination distribution of an omnidirectional lamp, although there is still interest in extending this span, for example with and possibly with better ± 10% uniformity for a latitudinal span of θ ═ 0 °,150 °. Such lamps having substantial uniformity are generally considered in the art as omnidirectional lamps over a large range of latitudes (e.g., about θ ═ 0 °,120 ° ] or more preferably about θ ═ 0 °,135 ° ], or still more preferably about θ ═ 0 °,150 ° ], even if the range of uniformity is less than θ ═ 0 °,180 °.

There is interest in developing omnidirectional LED backup (replacement) lamps that are used as direct "plug-in" backup to an integral incandescent or halogen lamp. However, substantial challenges have heretofore hindered the development of LED back-up lamps with desirable omnidirectional intensity characteristics. One problem is that solid state lighting technologies such as Light Emitting Diode (LED) devices are highly directional in nature compared to incandescent and halogen lamps. For example, for packaged or unpackaged LED devices, light is typically emitted in a directional Lambertian spatial intensity distribution with intensity varying with cos (θ) in the range of θ > 0 °,90 °, and has zero intensity when θ > 90 °. Semiconductor lasers are more directional in nature and, in fact, emit a distribution that can be substantially said to be limited to a narrow cone of light around 0 °.

Another problem is that LED chips or other solid state light emitting devices are not typically efficiently operated using standard 110V or 220V ac power supplies, unlike incandescent filaments. In contrast, on-board electronics are typically configured to convert an ac input power source into a low voltage dc power source suitable for driving the LED chips. As an alternative, a sufficient number of strings of LED chips may be operated directly at a voltage of 110V or 220V, and a parallel arrangement of these strings with appropriate polarity control (e.g. zener diodes) may be operated at 110V or 220V ac power, albeit with greatly reduced power efficiency. In either case, the electronic device constitutes an additional component of the lamp holder compared to an edison lamp holder for an integral incandescent or halogen lamp.

Yet another problem with omni-directional LED back-up lamps is heat dissipation. Since the LED device is highly sensitive to temperature as compared with an incandescent lamp or a halogen lamp, heat is dissipated. LED devices cannot be used at the temperature of incandescent filaments (conversely, the operating temperature should be 100 ℃ or preferably lower). The lower operating temperature also reduces the effectiveness of the radiant cooling. In a common approach, the base of the LED back-up lamp further includes a mass of heat sink material placed in contact or good thermal contact with the LED device, in addition to the edison base connector and the electronic device.

The combination of electronics and heat sink creates a large base that prevents "back" illumination, which heretofore substantially limited the ability to produce omnidirectional illumination with LED backup lights. The heat sink is particularly preferred to have a large capacity and a large surface area to remove heat from the lamp by a combination of convection and radiation.

Disclosure of Invention

In some embodiments disclosed herein as illustrative examples, a light emitting apparatus comprises: an LED-based light source; a spherical, spheroidal, ovoid, egg-shaped, or toroidal diffuser that produces a light intensity distribution output in response to illumination inside the diffuser; and a base including a base connector. The LED-based light source, diffuser, and base are secured together as a unitary LED lamp that can be installed in a lighting socket by connecting the base connector and the lighting socket. The base is operatively connected with the LED-based light source in the unitary LED lamp to power the LED-based light source with power received by the base connector.

In some embodiments disclosed herein as illustrative examples, a light emitting apparatus comprises: a lamp assembly including an LED-based light source optically coupled to and disposed tangential to a spherical, spheroidal, ovoid, or egg-shaped diffuser; and a base including a base connector, the base configured to power the LED-based light source with power received at the base connector. The lamp assembly and the base are secured together as a unitary LED lamp that can be installed in a lighting socket by connecting the base connector and the lighting socket.

In some embodiments disclosed herein as illustrative examples, a light emitting apparatus comprises: a lamp assembly including an annular LED-based light source optically coupled to the toroidal diffuser; and a base including a base connector, the base configured to power the annular LED-based light source with power received by the base connector. The lamp assembly and the base are secured together as a unitary LED lamp that can be installed in a lighting socket by connecting the base connector and the lighting socket.

Drawings

The invention may take form in various components and arrangements of components, and in various process operations and arrangements of process operations. The drawings are only for purposes of illustrating embodiments and are not to be construed as limiting the invention.

Fig. 1 schematically illustrates a coordinate system used herein to describe the illumination distribution with reference to a conventional incandescent light bulb.

Figure 2 schematically shows a side view of an LED-based omnidirectional lamp employing an LED-based planar lambertian light source and a spherical diffuser.

Fig. 3 schematically illustrates the LED-based omnidirectional lamp of fig. 2, with the spherical diffuser lifted away to expose the LED-based planar lambertian light source.

Fig. 4 schematically illustrates, using a ray tracing diagram, how the LED-based omnidirectional lamp of fig. 2 and 3 produces a substantially omnidirectional illumination distribution.

Fig. 5 and 6 show side views of two illustrative LED-based lamps that employ the principles of the lamps of fig. 2-4 and each further includes an edison base that can be mounted in a conventional incandescent base, respectively.

Fig. 7 schematically shows a side view of a variant of the embodiment of fig. 2-4, in which the light source emits an oblong distorted (distorted) lambertian intensity distribution and the diffuser is an oblong spherical diffuser having a shape that is matched to the intensity of the light source, respectively.

Fig. 8 schematically shows a side view of a variant of the embodiment of fig. 2-4, in which the light source emits an oblate-distorted lambertian intensity distribution and the diffuser is an oblate spheroidal diffuser having a shape that is matched to the intensity of the light source, respectively.

FIG. 9 illustrates the effect of the position of the LED-based light source relative to the spherical diffuser on the blocking angle.

FIG. 10 illustrates the effect on latitude range of light uniformity of ratio of spherical diffuser diameter to LED-based light source size.

Fig. 11 illustrates a side perspective view of a retrofit LED-based light bulb substantially similar to the light of fig. 5 but further including fins.

Fig. 12 shows the intensity versus latitude for two practical constructed embodiments of the retrofit LED-based light bulb of fig. 11.

Fig. 13 and 14 schematically illustrate side and perspective views, respectively, of a light source employing principles disclosed herein and having a toroidal diffuser. Fig. 14A depicts a variant embodiment.

Fig. 15, 16, 17, 18 and 19 show perspective, optionally shaded perspective, side, top and bottom views, respectively, of an LED-based light bulb.

Fig. 20 and 21 show the diffuser of the lamp of fig. 15-19, respectively, including a side view and a shaded side elevation view exposing the interior of the diffuser.

Fig. 22 and 23 show a side view of a diffuser with fins and an exploded view thereof, respectively.

FIGS. 24, 25, and 26 compare the ovoid diffuser of the embodiments of FIGS. 15-23 to a spherical diffuser, with FIG. 25 showing the difference in the length of the lines of incident light for the ovoid and spherical diffusers and FIG. 26 showing the scattering distribution of light emitted through the ovoid diffuser.

FIGS. 27-30 show additional illustrative ovoid diffuser embodiments.

Fig. 31 and 32 illustrate the embodiment of the lamp of fig. 15-23 further including optional secondary optics.

Detailed Description

Referring to fig. 2 and 3, the LED-based lamp includes an LED-based planar lambertian light source 8 and a light transmissive spherical diffuser 10. The LED-based planar lambertian light source 8 is best viewed in the partially broken-away view of fig. 3, where the diffuser 10 exits the field of view and the LED-based planar lambertian light source 8 enters the field of view. The LED-based planar lambertian light source 8 includes a plurality of Light Emitting Diode (LED) devices 12, 14, which in the illustrated embodiment include a first LED device 12 and a second LED device 14 each having a spectrum and intensity of white light mixed to exhibit a desired color temperature and CRI. For example, in some embodiments, the first LED device 12 outputs green-rendered white light (e.g., light that may be realized by using a blue-or violet-emitting LED chip coated with a suitable "white" phosphor), the second LED device 14 outputs red light (e.g., light that may be realized by using a GaAsP or AIGalnP or other epitaxial LED chip that naturally emits red light), and the light from the first and second LED devices 12, 14 mixes together to produce an improved white light rendering. On the other hand, it is also contemplated that the LED-based planar lambertian light source comprises a single LED device, which may be a white LED device or a saturated color LED device, or the like. The LED devices 12, 14 are mounted on a circuit board 16, which is optionally a Metal Core Printed Circuit Board (MCPCB). Optionally, the base element 18 provides support and is thermally conductive, such that the base element 18 also defines a heat sink 18 having a relatively high thermal conductivity for dissipating heat from the LED devices 12, 14.

The light transmissive spherical diffuser 10 is shown as being substantially hollow and having a spherical shape that diffusely reflects light. In some embodiments, the spherical diffuser is a glass element, but diffusers of another light transmissive material (e.g., plastic) or other materials are also contemplated. The surface of the diffuser 10 may itself diffuse the light, or it may be diffused in a different way, for example: matting or texturing to promote light diffusion; coated with a light diffusing coating such as enamel or Soft-White or Starcoat as a light diffusing coating on some incandescent or fluorescent bulbs^TMCoatings (available from general electric company, new york, usa); embedding light-scattering particles in the glass, plastic, or other material of the spherical diffuser 10; various combinations of the above; and so on.

The diffuser 10 may optionally further comprise, for example, a phosphor coated on a spherical surface to convert the light of the LEDs into another color, for example, to convert blue or Ultraviolet (UV) light from the LEDs into white light. In some such embodiments, the phosphor is expected to be the only integral part of diffuser 10. In such an embodiment, the phosphor should be a diffusive phosphor. In other contemplated embodiments, the diffuser includes phosphor plus additional diffusing elements, such as matting layers, enamels, coatings, and the like.

The light transmissive spherical diffuser 10 includes an aperture or opening 20 sized to receive or fit the LED-based planar Lambertian light source 8 such that the principle light emitting surface of the LED-based planar Lambertian light source 8 faces and enters the interior of the spherical diffuser 10 and emits light into the interior of the spherical diffuser 10. The spherical diffuser is larger compared to the area of the LED-based planar lambertian light source 8, such that the light source 8 is arranged at the periphery of the substantially larger spherical diffuser 10; in the illustrated embodiment, spherical diffuser 10 has a diameter d_DAnd the LED-based planar lambertian light source 8 (or equivalently, the mating hole or opening 20) has a diameter d_LArea of circle of (2), wherein d_D＞d_L. The LED-based planar lambertian light source 8 is mounted at or within a hole or aperture 20 having a planar light emitting surface disposed tangential to the curved surface of the spherical diffuser 10. It is understood that only d is present_L/d_DThe exact tangency is achieved only in the case of a near zero but with the ratio d_D/d_LIncreasing, i.e. the size of the LED-based planar lambertian light source 8 is reduced relative to the size of the spherical diffuser 10, the tangency becomes more nearly accurate.

With continuing reference to fig. 2 and 3, and with further reference to fig. 4, the LED-based lamp may likewise be described using the spherical coordinate system of fig. 1, wherein the LED-based planar lambertian light source 8 defines a coordinate system. Thus, the forward beam along the optical axis of the LED-based planar lambertian light source 8 is in the north direction (θ ═ 0 °), where the intensity is greatest (here with I ═ 0 °)_oRepresentation). According to the lambertian distribution, the intensity increases with increasing elevation or latitude away from the optical axis (conventional with the spherical coordinates of fig. 1), such that the intensity I ═ I at the latitude θ_oCos (θ). It should be noted that the LED-based lamps of fig. 2-4 are rotationally symmetric about the optical axis, and thus there is no relative symmetryIn azimuth or longitude coordinates

The intensity of (2) is varied.

With particular reference to fig. 4, the LED-based lights of fig. 2-4 are substantially greater than 0, 90 degrees]Produce omnidirectional illumination over a range of elevations or latitudes. Two points are identified herein. First, with the planar LED-based Lambertian light source 8 placed tangent to the spherical diffuser 10, the Lambertian illumination output by the planar LED-based Lambertian light source 8 is uniform across the entire (interior) surface of the spherical diffuser 10. In other words, the flux of light (lumens/area) impinging on the (inner) surface of the spherical diffuser 10 (this flux is typically in lux (lumens/m)²) Measured in units) at any point of the spherical diffuser 10 are the same. Thus, the inside surface of the diffuser coincides with the isoluminance surface of the LED light sources. This can be qualitatively seen from the following. At θ -0 °, the forward beam of the lambertian light source has a maximum value I_o(ii) a However, has an intensity I_oTravels furthest before striking the (inner) surface of the spherical diffuser 10. Intensity increases with the square of the distance, hence intensity and I_o/d_D ²Proportional (where the exact tangency of the light source 8 and the curvature of the diffuser 10 are assumed here to be simplistic). At any latitude θ, the intensity of the light source is low, i.e. I_oCos (θ); however, the distance d ═ d traveled before striking the spherical diffuser 10_DCos (θ) is reduced by an amount cos (θ), and the projected surface area that receives the intensity at the spherical diffuser is also reduced by a factor cos (θ). Thus, the flux density at the surface at any latitude θ is related to (I)_o.cos(θ).cos(θ))/(d_D.cos(θ))²Proportional to a constant, which is the same as when θ is 0. Thus, in the case of a lambertian intensity distribution emitted by an LED light source, the inside surface of the spherical diffuser (the LEDs lie tangentially on the surface of the spherical diffuser) coincides with the isoluminance profile of the intensity distribution of the LEDs.

The second point identified herein is that the diffuser 10 (assuming ideal light diffusion) responds inside the diffuser 10 by the LED-based light source 8Emits a lambertian light intensity distribution output at any point on the diffuser surface. In other words, the light intensity output of a spot on the surface of the diffuser 10 in response to illumination inside the spherical or spheroidal diffuser

Calibration of wherein

The viewing angle at this point relative to the orthogonal diffuser surface. A ray tracing diagram of seven direct rays emitted by the LED-based planar lambertian light source 8 is schematically shown in fig. 4. At the location where each direct ray hits the surface of the light-transmissive spherical diffuser 10, the ray is diffused to the lambertian output emitted from the (outer) surface of the spherical diffuser 10. As is known in the optical arts, lambertian distributed surface-emitted light appears to have the same intensity (or brightness) regardless of viewing angle, because at larger viewing angles, the lambertian reduction in output intensity is offset by just a smaller perceived viewing area due to the viewing angle tilt, relative to the orthogonal surface. Since the entire surface of the diffuser 10 is illuminated with the same intensity (the first point set forth in the preceding paragraph), the result is that the outside observer observes that the diffuser 10 emits light with a uniform intensity at all viewing angles and a spatially uniform source brightness over the diffusing spherical surface.

In embodiments where the diffuser 10 comprises a wavelength-converting phosphor, the phosphor should be a diffusely reflecting phosphor, i.e., a phosphor that emits wavelength-converted light in the Lambertian (or nearly Lambertian) mode shown in FIG. 4, regardless of the angle of incidence of the direct (excitation) illumination. The diffuse reflection property of the phosphor is controlled by parameters such as the thickness of the phosphor layer, the particle size of the phosphor, and the reflectivity (which affects the performance of the phosphor as a light scattering object). If the phosphor layer is not sufficiently scattering, the phosphor can be combined with additional diffusion components (e.g., a matte layer of glass or other substrate), including a layer of enamel or the like.

At the same time, the spherical diffuser 10 provides excellent color mixing characteristics during light diffusion without the need for passing additional lightMultiple bounces of the optical element, or no optical components that cause light loss or absorption. Further, since the LED-based planar Lambertian light source 8 is designed to be small compared to the spherical diffuser 10 (i.e., the ratio d)_D/d_LShould be larger) and therefore the back-light shadowing is greatly reduced compared to prior designs employing hemispherical diffusers, where the LED-based planar lambertian light source is placed at 90 ° to the equatorial plane θ and has the same diameter as the hemispherical diffuser (corresponding to d)_D/d_LLimit of 1).

The configuration of the base 18 also helps to provide omnidirectional illumination. As shown in FIG. 2, the spherical diffuser 10 illuminated by the LED-based Lambertian light source 8 may be viewed from a far-field perspective as producing a light beam originating from point P₀Of (2) is detected. In other words, the far-field point light source position P₀Defined by an omnidirectional light assembly comprising a light source 8 and a diffuser 10. The base 18 blocks a portion of the "backward" directed light so that the weft-blocking angle α is_BCan be formed by having a mean point P₀Is defined by the maximum latitude theta of the direct line of sight. This is illustrated in figure 2. For the blocking angle alpha_BAt a range of viewing angles, the base 18 provides most of the shading, thereby greatly reducing the illumination intensity. It will be appreciated that the weft blocking angle α_BThe concept of (a) is useful in far-field estimation, but not an accurate calculation-this is shown in fig. 2, e.g. the ray Rs at the blocking angle α_BDoes not emit light in the range of (1). Since it is estimated only as the light source P in the far field estimation₀The finite size of the diffuser 10, ray Rs, is present. The base also reflects a portion of the rearward light without blocking or absorbing it and redirects the reflected light into the light distribution pattern of the lamp, increasing the light distribution in the angular region just above the blocking angle. To accommodate the effect on the light distribution pattern due to light reflection off the heat sink and the base surface, the shape of the diffuser is only slightly changed near the intersection of the diffuser and the LED light sources to improve the uniformity of the distribution pattern in this corner region.

In view of the above, the lighting omnidirectionality at large latitude angles is considered to be additionally dependent on controlling the blocking angle α_BThe size and geometry of the base 18. Although the ball can be enlargedDiameter d of the shaped diffuser 10 (explained with reference to ray Rs, for example)_DObtaining a blocking angle alpha_BSome of the illumination in (b), but the diameter is usually limited by practical considerations. For example, if a retrofit incandescent bulb is designed, the diameter d of the spherical diffuser 10 is adjusted_DLimited to less than or (at most) equal to the size of the incandescent bulb to be replaced. As seen in FIG. 2, one suitable base design has an angle formed to substantially conform to the blocking angle α_BThe side portion of (a). Having about the blocking angle alpha_BThe base of the angled side is designed as a blocking angle alpha_BA maximum chassis capacity is provided which in turn provides maximum capacity for the electronic device and the heat slug.

By way of review and extension, a method for designing an LED-based omnidirectional light is disclosed herein. In the disclosed embodiments of these methods, a small light source 8 is positioned to emit a substantially Lambertian distribution of light in the 2- π steradian half-space above the light source 8. A spherical (or more generally spheroidal) diffusion bulb 10 has a small optical input aperture 20 fitted with a small light source. The direct illumination is scattered at each point on the surface of the diffusion bulb 10 to produce a substantially lambertian output light intensity distribution outside the diffusion bulb 10. Providing a uniformly illuminated appearance on the surface of the bulb 10 and providing a nearly uniform intensity distribution for light emitted into 4 pi steradians that omnidirectionally surrounds the bulb, except in the backward direction along the optical axis (theta-180 deg.) of the illumination that is obscured by the light source 8 through the heat sink and electronics volume.

And further consider several aspects of this design. The first aspect is a generally lambertian distribution of light intensity from a typical LED device or LED package (e.g., LED light source 8) such that the light intensity remains nearly constant along the trajectory of the spherical diffuser 10 with the LED light sources 8 placed at any single location on or near the spherical surface (e.g., at the small aperture 20). The second aspect of the design is to intercept the lambertian light distribution pattern with a light diffuser 10, the diffusion of which takes place along a nearly constant luminous flux trajectory by placing the spherical or nearly spherical light diffuser 10 near the LED light sources 8, so that the LED light sources 8 are located on or near the surface of the spherical diffuser 10, with the LED light sources 8 correcting them along the optical axis (θ ═ 0)The directional illumination is directed to the opposite point of the spherical diffuser 10 that is farthest from the optical input aperture 20. This arrangement ensures that the illuminance (lumens/surface area) of the light impinging on the spherical light diffuser 10 remains almost constant over the entire (inner) surface of the spherical diffuser 10. The third aspect is a function of the substantially lambertian scattering distribution of the light diffuser 10, such that an intensity that is substantially lambertian with respect to angle is emitted from each (outer) point on the light diffuser 10. It is ensured that the light intensity (lumen/steradian) remains almost constant in all directions. The fourth aspect is the maximum lateral dimension d of the LED light source 8_LShould be substantially less than the diameter d of the spherical light diffuser 10_DIn order to maintain the first, second and third aspects close to idealisation. If the LED light sources 8 are too large in relation to the spherical diffuser 10, the first aspect will be affected such that the illuminance on the surface of the light diffusing sphere deviates significantly from the desired uniformity. Further, if the LED light sources 8 are too large relative to the spherical diffuser 10, the third aspect will be affected and the LED light sources 8 will block most of the potential 4 π steradians of light emitted by an ideal spherical light diffuser. (or in other words, if the LED light source 8 is too large, it will block a large portion of the light directed backwards, which is undesirable). The fifth aspect is that the base 8 should be designed such that the blocking angle α is_BMinimized and provide sufficient chassis capacity to provide adequate heat dissipation and space for the electronic device.

Referring to fig. 5 and 6, an embodiment of a design of an integral LED lamp configured to be suitable for replacing a conventional incandescent or halogen light bulb is shown. Each of the LED-based lamps in fig. 5 and 6 includes an edison screw base connector 30 formed as an edison base that directly replaces a conventional incandescent lamp. (more generally, the type of base connector should be the same as the base of the incandescent or halogen lamp to be replaced-for example, if the incandescent or halogen lamp employs a bayonet base, then the edison base connector 30 is suitably replaced by the required bayonet base connector). The integral LED lamp of fig. 5 (or fig. 6) is a self-contained omnidirectional light emitting device that does not rely on a lighting socket for heat dissipation. As such, the integral LED lamp of fig. 5 (or fig. 6) may replace a conventional integral incandescent or halogen lamp without concern for thermally overloading the socket or associated hardware, and without modifying the electrical configuration of the socket. The LED lamp of fig. 5 and 6 includes respective spherical or spheroidal diffusers 32, 34 and respective LED-based planar light sources 36, 38 disposed tangentially to the bottom of the respective spheroidal diffusers 32, 34. The LED-based light sources 36, 38 are constructed tangentially with respect to the spherical or spheroidal diffusers 32, 34 and include LED devices 40. In FIG. 5, the LED based light source 36 includes a smaller number of LED devices 40 (two shown) and provides a substantially Lambertian intensity distribution coupled with the spherical diffuser 32. In fig. 6, the LED-based light source 38 includes a relatively large number of LED devices 40 (two shown). The light source 38 produces a light output distribution that is distorted to a lambertian distribution because it is relatively dispersed in the plane of the LED-based light source 38 compared to an exact lambertian distribution. To accommodate distortion with respect to an accurate lambertian distribution, diffuser 34 of FIG. 6 is a spheroidal diffuser, i.e., different from a perfectly spherical diffuser. In the illustrated example of FIG. 6, the distorted Lambertian distribution output by the LED-based light source 38 may be described as a Lambertian distribution having an oblate distortion and is suitably captured by the diffuser 34 having an oblate spheroidal shape. Referring to fig. 7 and 8, further discussion is provided of accommodating an imprecise lambertian light distribution.

With continued reference to fig. 5 and 6, an electronic driver 44 is interposed between the planar LED light source 36 and the edison base connector 30, as shown in fig. 5. Similarly, an electronic driver 46 is interposed between the planar LED light source 38 and the edison base connector 30, as shown in fig. 6. The electronic drivers 44, 46 are contained in respective lamp sockets 50, 52, the balance of each base 50, 52 (i.e. the portion of each base 50, 52 not occupied by the respective electronic device 44, 46) preferably being made of a heat dissipating material so as to define a heat sink. The electronic drivers 44, 46 are themselves sufficient to convert the ac power received by the edison base electrical connector 30 (e.g., 110 volt ac commonly available to edison base sockets in U.S. homes and offices, or 220 volt ac commonly available to edison base sockets in European homes and offices, or 12 volt or 24 volt or other voltage dc) into a form-appropriate format to drive the LED-based light sources 36, 38. In embodiments where the LED light source is configured to be operated directly from 110 volts or 220 volts ac (e.g., if the LED-based light source includes a series of numbered LED devices that are optionally operated directly from ac with zener diodes to accommodate ac polarity switching), it may be desirable to omit the electronic drivers 44, 46.

The bases 50, 52 need to be made larger to accommodate the large volume of the electronic device and provide adequate heat dissipation, but are also preferably configured to minimize the blocking angle α_B. Furthermore, heat dissipation is primarily not conducted through the edison base 30, but rather primarily relies on a combination of convection and radiation to expel heat into the ambient air, and thus, the heat sink defined by the bases 50, 52 should have sufficient surface area to promote convective and radiative heat dissipation. On the other hand, it is further recognized herein that the LED-based light sources 36, 38 are preferably small diameter light sources due to the tangential arrangement with respect to the diffusers 32, 34. These different considerations are contained in the respective bases 50, 52 by employing a small receiving or mating area in connection with the LED-based light sources 36, 38, wherein the bases are substantially the same size as the LED-based light sources 36, 38 and have angled sides 54, 56 that are angled substantially at the blocking angle α_BThe same is true. The angled base sides 54, 56 extend away from the LED-based light sources 36, 38 a distance that causes the angled sides 54, 56 to align with the diameter d_baseCylindrical base portions large enough to accommodate the electronics 44, 46.

The geometrical shape of the base is designed by the blocking angle alpha_BThe blocking angle is in turn controlled by the desired latitude range of the substantially omnidirectional illumination. For example, if θ is required to be [0 °,150 ° ]]With substantially omnidirectional illumination over the range, the blocking angle α_BShould not be greater than 30 deg., and in some such designs the blocking angle is about 30 deg. in order to maximize the size of the base housing the heat sink and electronic device. In another aspect, the lamp assembly is operated at a temperature of at least θ ═ 0 °, X]Produce illumination that varies uniformly to 30% or less (e.g., more preferably 20%, or more preferably 10%), where X is latitude, and X ≧ 120. The pedestals 50, 52 are not extended to the latitude range θ ═ 0 °, X]But preferably is enlarged to have a relatively large surface area. This can be achievedOver-construction is achieved with bases 50, 52 having sides 54, 56 at latitude X.

In yet another aspect, the blocking angle α is maintained by ensuring that the base is minimized at the connection with the lighting assembly comprising the diffuser and the LED-based light source_BSmaller and when extended away from the lighting assembly the cross-sectional area (e.g., diameter) flares or increases to provide sufficient volume and surface area for convective and radiative heat dissipation and optionally for housing electronics. In some embodiments, such as the embodiment of fig. 5 and 6, the bases 50, 52 are sized at the connection with the lighting assembly to have the same area as the area of the LED-based light sources 36, 38, and the sides 54, 56 are at the maximum allowable angle (i.e., equal to the blocking angle α)_BAngle) to place a maximum volume of heat sink material proximate the LED-based light sources 36, 38 while meeting the block angle design constraints.

As shown in fig. 5 and 6, the lamp sockets 50, 52 include a heat sink portion proximate to the LED-based light sources 36, 38 and between the LED-based light sources 36, 38 and their drive electronics 44, 46. Accordingly, electrical pathways 58 are provided through the heat sink portion of the base to electrically connect the electronic devices 44, 46 and the light sources 36, 38. On the other hand, the electronic units 44, 46 are directly adjacent to the edison base connector 30 (or, in an alternative aspect, extend so as to include the edison base connector).

Referring to fig. 7, in some embodiments, the light source may produce other distributions than a lambertian intensity distribution. In the illustrative example of fig. 7, the light source 100 produces a substantially distorted lambertian intensity distribution 102. The intensity distribution 102 is similar to a lambertian intensity distribution in that it is strongest in the forward direction (i.e., along the optical axis or along θ ═ 0 °), and decreases as the latitude θ of zero intensity increases at θ ≧ 90 °. However, the reason for the large distortion of the intensity distribution 102 relative to the true lambertian distribution is that most of the total intensity is in the forward direction, as schematically shown by the ray trace in fig. 7. The type of distortion represented by the lambertian intensity distribution 102 shown in fig. 7 is sometimes referred to as oblong distortion. For such embodiments, the ratio d discussed with reference to the spherical diffuser embodiments (e.g., FIGS. 2-4)_D/d_LIs suitable for use with d_PMA/d_LIn which d is_PMAIs the minor axis of the oblong distorted spheroidal diffuser shown in fig. 7.

Referring to FIG. 8, as another example, the light source 110 produces a distorted Lambertian intensity distribution 112 having a generally oblate distortion. The reason why the generally oblate distorted Lambertian intensity distribution 112 is distorted relative to a true Lambertian distribution is that a small fraction of the total intensity is in the forward direction, as schematically illustrated by the ray traces in FIG. 8. Oblate spheroidal diffuser 114 is provided to diffuse the oblate distorted Lambertian intensity distribution 112. For such embodiments, the ratio d discussed with reference to the spherical diffuser embodiments (e.g., FIGS. 2-4)_D/d_LIs suitable for use with d_OMA/d_LIn which d is_OMAIs the long axis of the oblate distorted spheroidal diffuser shown in FIG. 8.

In general, the distortion of an ideal spherical (lambertian) distribution can be described as a spheroidal shape, such as an elongated elliptical spheroidal distribution 102 (fig. 7) or a flattened oblate spheroidal distribution (fig. 8). The design principles presented herein are easily generalized to these cases. Referring back illustratively to the embodiment of FIGS. 2-4, the spherical diffuser 10 is selected because the Lambertian light source 8 uniformly illuminates the spherical diffuser 10 over its entire (inside) surface. In other words, the spherical diffuser 10 follows the isoluminance curve of the lambertian light source 8. Summarizing this observation, as long as the light-transmissive diffuser is chosen to conform to the isolux surface of the corresponding light source, it is ensured that the entire surface of the diffuser is illuminated with a uniform intensity by the light source. Furthermore, because the diffuser provides lambertian scattering, shown in the example of fig. 4, the light from each point of the diffusing surface (outside) has a lambertian distribution. The resulting lamp output intensity will therefore be substantially omnidirectional. Since these shapes are different from the ideal spherical shape, deviations from the ideal omnidirectionality are observed in the case of the oblong or oblate spheroidal diffusers 104, 114; however, this deviation is relatively small for light source intensity distributions that deviate not too far from the lambertian distribution.

Applying these general design principles to the embodiment of FIG. 7, the spherical diffuser 10 of the embodiment of FIGS. 2-4 is replaced in the embodiment of FIG. 7 by an oblong spheroidal diffuser 104 that is matched to the isoluminance surface of the oblong distorted Lambertian intensity 102 produced by the light source 100. Qualitatively, the prolate spheroidal diffuser 104 can be viewed as compensating for the higher intensity portions along the positive (θ ═ 0) direction of the output intensity 102 by moving the diffuser surface further away from the light source 100 along the positive (θ ═ 0) direction.

For the embodiment of fig. 8, the spherical diffuser 10 of the embodiment of fig. 2-4 is replaced in the embodiment of fig. 10 by an oblate spheroidal diffuser 114 that is matched to the isoluminance surface of the oblate distorted lambertian intensity 112 produced by the light source 110. Qualitatively, the oblate spheroidal diffuser 114 may be viewed as compensating for the lower intensity portion in the forward (θ ═ 0) direction of the output intensity 112 by moving the diffuser surface closer to the light source 100 in the forward (θ ═ 0) direction.

More generally, it should be understood that substantially any source illumination distribution can be equally accommodated by selecting a diffuser having a surface corresponding to the isolux surface of the source. In practice, the azimuth or longitude direction is defined by specifying the plane of the like

Change in direction of, azimuth or longitude

The variations in this are also accommodated in the same manner. As mentioned before, the light distribution may also be influenced by secondary factors such as reflection from the base. The minor distortions can be accommodated by slightly adjusting the diffuser shape. In some embodiments, for example, the light source produces a light distribution pattern that may be Lambertian with very slight oblong distortion, but a spherical diffuser with slightly oblate distortion may be selected to provide the best lamp intensity distribution in view of the secondary effects of pedestal reflections.

Some illustrative embodiments are described with reference to fig. 2-8, and some further disclosure as well as a description of actual reductions to achieve and characterize are set forth below.

The following aspects of the omnidirectional LED lamp design are set forth herein. The first design aspect relates toDistribution of the intensity of light emitted by the LED light source. The distribution of the most typical LED light source is a lambertian distribution, but other distributions, such as a distorted lambertian distribution, may exist for the LED light source (e.g., fig. 7 and 8). Intensity distribution of LED light source in azimuth or longitude

Generally uniform, or nearly uniform in direction (i.e., it is desirable that the intensity distribution be substantially axisymmetric). A first design aspect entails identifying the intensity distribution of the LED light sources so that the transparent diffuser can be configured to conform to the isolux surface of the LED light sources. For a lambertian intensity distribution, the intensity with respect to the latitude angle (θ) is proportional to cos (θ), where θ is the angle measured from the optical axis shown in fig. 1. The ideal Lambertian distribution

Is uniform in direction, and

the directional distribution is in practice usually almost uniform for a typical LED light source. The resulting isoluminance surface is spherical. Some typical distortions of an ideal lambertian distribution include oblong distortions with relatively high intensity in the forward direction (as shown in fig. 7) or oblate distortions with relatively low intensity in the forward direction (as shown in fig. 8). Oblong distortion produces a long oval spheroidic isoluminance surface, while oblate distortion produces an oblate spheroidic isoluminance surface. With a relatively high intensity in the forward direction (oblong distribution, as shown in fig. 7), the long axis of the spheroid is aligned with the optical axis. With a relatively low intensity in the forward direction (oblate distribution, as shown in FIG. 8), the minor axis of the spheroid is aligned with the optical axis.

A second design aspect is to construct a light transmissive diffuser that conforms to an isolux surface. If the intensity distribution of the LED light sources is exactly Lambertian, the isoluminance surface is spherical (and thus the diffuser is spherical), and the ideal position of the light emitting surfaces of the LED light sources is located at a tangent to the spherical diffuser surface. In solid LED light sources, particularly those employing multiple LED chips or multiple LED packages, discrete LED devices are typically mounted on a planar circuit board, and the LEDs may be individually packaged or packaged in an array with an index matching material to improve the efficiency of light extraction from the LED semiconductor material. The LED light source may also be surrounded by reflective, refractive, scattering or transmissive optical elements to improve the uniformity of the luminous flux of the light source or its color. To accommodate spatially extended LED light sources, the exit aperture (i.e., the light output surface) of the LED light source is suitably positioned tangentially to the surface of the light diffuser so that the light diffuser can receive a uniform illumination.

If the intensity distribution of the LED light sources deviates substantially from a pure lambertian distribution, the diffuser is not exactly spherical, but a shape that matches the shape of the light intensity distribution, such that the illuminance (lumen/area) remains constant at every position on the diffuser surface, and the light emitting surfaces of the LED light sources are located at positions tangential to the diffuser surface. For example, if the intensity distribution 102 of the LED light source 100 is concentrated in a forward protrusion (lobe) extending along the optical axis, as shown in fig. 7, the diffuser 104 should be elongated along the optical axis to match the shape of the intensity distribution.

Although a surface diffuser is shown here, a volume diffuser may also be employed. In a volumetric diffuser, light diffusion occurs throughout the volume of the diffuser, rather than being concentrated at the surface. In this case, the shape of the diffuser also takes into account the variation in the intensity distribution due to scattering inside the diffuser volume.

A third design aspect is to provide lambertian or nearly lambertian light scattering by a light diffuser. Even in the extreme case of a collimated beam as input, an ideal lambertian scatterer produces a lambertian intensity distribution at the output for any possible input distribution. When the input intensity distribution of light to the diffuser is lambertian or substantially lambertian with respect to the optical axis of the LED light source, the effect of the diffuser is to redirect the intensity distribution to a lambertian distribution with respect to the normal (i.e., the perpendicular unit vector) of the diffuser surface. Lambertian scatterers or relatively strong near-lambertian scatterers are generally sufficient to accomplish this task. Various materials commonly used in existing omnidirectional lamps, such as transparent or translucent glass, quartz, ceramic, plastic, paper, composite materials, or other light transmissive materials with low optical absorption, may provide lambertian or sufficiently strong scattering. The scattering is produced by roughening or matting (e.g., by chemical etching, or mechanical abrasion, or cutting with a mechanical tool or laser, etc.) the surface of the scattering medium. Additionally or alternatively, scattering may be produced by a scattering coating or paint or laminate applied to the surface, or by scattering in a bulk medium by suspending scattering particles in a medium, or by grain boundaries or inclusions in a medium (for heterogeneous media), or by other scattering mechanisms, or a combination of the above.

A fourth design aspect is to minimize the deviation of the actual intensity distribution from the ideal uniform isotropic distribution resulting from the ideal application of the three aspects described previously. The main source of deviation from an ideal lamp configuration is the placement of the light sources with respect to an inaccurate tangency of the transparent diffuser surface. By taking into account the ratio of diffuser size to LED light source size, e.g. the ratio d as in the embodiments of FIGS. 2-4_D/d_LAs stated, non-idealities may be limited. From the results of the optical ray tracing model, and by measurement confirmation of a prototype lamp of about 2-3/8 "or about 60mm in lamp diameter, which is typically used to replace the A1 size incandescent light bulb, the ideal range was quantified for the model and corresponding prototype, where the LED light source comprises a symmetrical array of a large number of closely spaced LEDs on a relatively small circular circuit board having a diameter d_LIn the range of 10-20mm and set at a diameter d_DThe "south pole" (i.e., θ ═ 180 °) of the spherical glass bulb of (a), its inside surface is covered with lambertian scatterers.

Referring to FIGS. 9 and 10, d_D/d_LMainly determines the range of the weft angle over which the intensity distribution remains constant. (Note that in FIG. 9, the symbol "D" represents the diameter D of the LED-based planar Lambertian light source 8_LAnd the symbol "S" denotes the diameter d of the diffuser 10_D. In FIG. 10, the ratio d_D/d_LIs denoted by D_D/D_L). When d is_LIncrease becomes with d_DWhen relevant (and thus more severely deviating from exact tangency),the position of the LED light sources should be shifted away from the south pole of the spherical diffuser towards the equator (i.e., the plane defined by θ ═ 90 °), and the intensity distribution should decrease uniformly from a range of 0 ° to 180 ° to a range of 0 ° to 90 °. Another way to look at this problem is that for perfect tangency, the light source should meet a spherical or spheroidal diffuser at a single point. However, there is a finite dimension d_LWith respect to the light source 8, the "point" of encounter becomes a strip of length d with respect to the spherical or spheroidal diffuser 10_LThe chord of (a). Thus, relative to the diameter d of the diffuser 10_DChord length d of_L(or the inverse thereof) is a measurement close to the ideal tangent. By way of example, if d_D/d_L< 1.15, the maximum possible range of uniform intensity distribution is approximately θ ═ 0 °,120 °](ii) a Or if d_D/d_L< 1.5, the maximum possible range of uniform intensity distribution is approximately θ ═ 0 °,138 °]. To change theta to [0 DEG ], 150 DEG]Providing a uniform intensity, the ratio should be increased to d_D/d_LIs greater than 2.0. Even if d_D/d_LAt an angle close to 150 °, the intensity distribution is still not uniform, since the distribution misses the illumination contribution of light emitted from a spherical surface at latitudes in the range of 150 ° to 180 °. In order to provide an almost uniform intensity distribution in the range of 0 ° to 150 °, d_D/d_LShould be greater than 2.0, depending on the scattering distribution function of the spherical diffuser and on the reflective properties of the lamp components (e.g., heat sink, heat fins, and electronics) placed under the LED light sources. In experiments carried out in practice on LED spare lamps for incandescent lamp use, it was found that d_D/d_L> 2.5 is generally suitable to provide intensity uniformity within +/-10% mean intensity over the range of 0 ° to 150 °. If uniform intensity is required over only the range of 0 to 135 and/or a large tolerance of +/-20% is deemed acceptable (e.g., to meet the energy Star Specification set forth by the U.S. department of energy), then d is required according to FIG. 10_D/d_L> 1.41, d is preferred in the practical lamp embodiment_D/d_L＞1.6。

A fifth design aspect is to minimize the impact of the pedestal. First, one may wish to do so with a small base, however, this is doneHeat dissipation is negatively impacted which in turn limits the light output intensity and may also negatively impact the space available for the lighting electronics. As disclosed herein, the improvement resides in a relatively narrow base at the junction with a lighting assembly comprising an LED light source and a spherical or spheroidal diffuser (the base preferably having the same cross-sectional area at the junction as a substantially LED-based planar light source), and having a blocking angle α less than or substantially equal to that selected according to the latitude range desired for omnidirectional lighting_BThe angled side of (a). For example, if the desired latitude range θ is [0 °,150 ° ]]Then angle of block α_BShould be no greater than 30 deg., and in some designs the blocking angle is about 25 deg. in order to maximize the size of the base to accommodate the heat sink and electronic device. The angle of the angled side of the submount should not be greater than 30 °, and preferably 25 ° in order to provide maximum submount volume for a heat sink proximate to the LED-based light source.

Referring again to fig. 5 and 6, the heat dissipation illustrated is a passive heat dissipation that relies on the conduction of heat from the LED-based light sources 36, 38 to the adjacent base 50, 52, and then to radiate and convect into the air or other ambient environment via the surface of the heat sink defined by the bases 50, 52. Heat dissipation by convection and radiation may be enhanced by providing additional thermal management devices, such as heat pumps or thermoelectric coolers, or by increasing active cooling, such as by using fans, synthetic jets, or other means of enhancing cooling air flow. Convective and radiative heat dissipation may also be enhanced by increasing the surface area of the heat sink. One way to achieve this is to crease or otherwise modify the surface of the base heat sink element (which is the base 50, 52 in the embodiment of fig. 5 and 6). Fins or other heat dissipating elements may also be added to the base, if these elements extend outwardly beyond the blocking angle α_BThe light output may be disturbed.

Referring to fig. 11, a modified embodiment is disclosed that includes the embodiment of fig. 5 in addition to heat fins 120 that enhance the transfer of radiant and convective heat from the base 50 to the air or other ambient environment. In another aspect, the heat sink of the base 50 includes a barrier angle α disposed in the latitudinal direction_BInner (illustrative embodiment of FIG. 5)Within the base 50 or co-existing with the base 50) and a heat dissipating element comprising the illustrated fins 120 in thermal communication with the base heat dissipating element and extending over the diffuser 32 to further enhance heat release to the ambient air by convection and radiation. That is, heat is transferred from the LED chips of the LED-based lighting unit 36 at the location 36' represented in fig. 11 to the base heat sink element and conductively diffused to the heat sink fins 120 where the heat is transferred to the environment by convection and/or radiation. The fins 120 of the lamp of fig. 11 extend latitudinally to almost θ equal to 0 °, so that the fins 120 extend just beyond the blocking angle α_BThe range of (1). However, fins 120 are at longitude

The direction has a greatly limited range; thus, the fins 120 have no significant effect on the omnidirectional illumination distribution produced by the lamp of fig. 11. In other words, each fin is located at substantially a constant longitude

And thus does not have a significant negative impact on the omnidirectional nature of the illumination distribution. More generally, as long as the heat spreading elements extend outwardly and are oriented transverse to the surface of the spherical or spheroidal diffuser, they do not have a significant negative impact on the omnidirectional nature of the illumination distribution. The fins 120 are also shaped to conform to the desired shape (i.e., profile) of an "a" type incandescent bulb. Such outward shaping is optional but advantageous because consumers are familiar with conventional "a" type incandescent bulbs. The improved heat dissipation provided by the fins 120 can further reduce the size of the LED-based planar light source, which in turn enables the design to further enhance the omnidirectionality of the output light intensity distribution.

Referring to fig. 12, an embodiment of the retrofit LED-based lamp shown in fig. 11, which includes six fins 120, was actually constructed and their longitudinal intensity distribution was measured. The actual constructed retrofit LED-based lamp was constructed according to the standards for the a19 lamp. Blocking angle alpha_BIs 23 deg.. The fins 120 are 1.5mm thick and the alignment is at a constant longitude (constant) as shown in FIG. 11

) In-plane. One embodiment (lamp a) used a G12 enamel lamp cover (available from general electric company, new york, usa) as a diffuser, while another embodiment (lamp B) used a 40mm plastic sandblasted globe as a diffuser. Both lamps have an edison base connector 30 as shown in fig. 11. FIG. 12 illustrates a far field point source position P defined in terms of relative to the omnidirectional light assemblies 32, 36₀Lamp a is shown by a solid line and lamp B is shown by a dashed line. For lamp a using an enamel lamp envelope as diffuser, the latitude span θ ═ 0 °,150 °]Intensity measurement in (a) is 35 ± 7cd, which corresponds to a uniformity of ± 20% variation range, where the latitude span θ ═ 0 °,135 °]The uniformity is better. Orientation

It is also good, with an intensity variation of ± 15%, thus achieving a latitude span θ ═ 0 °,150 °,]omnidirectional illumination within range.

On the other hand, lamp B shows a substantially poor uniformity over a range of latitude spans θ ═ 0 °,150 °. This can be attributed to sandblasted plastic providing insufficient light diffusion. In other words, referring back to fig. 4 simply, the light from each incident ray is not itself lambertian to lamp B, as shown in fig. 4, but continues to have a strong deviation in the direction of the incident ray. This generates a relatively large amount of light in the forward direction (θ is 0 °) shown in fig. 12 for the lamp B. In other words, the insufficient diffusion provided by the sandblasted plastic of lamp B does not remove the strong forward illumination bias of light source 36 in lamp B.

The fins 120 or other heat dissipating elements shown have incorporated other integral LED lamps, such as the LED backup lamp of fig. 6. Use of such fins facilitates coupling the base with a smaller lighting assembly (LED-based light source or spherical or spheroidal diffuser), which in turn facilitates a larger d_D/d_LRatio, which further facilitates large span latitude angles (e.g., latitude span θ ═ 0 °,150 °)]) The omni-directionality in the inner direction. Further, by retaining the finsIs planar and is located at a constant longitude (constant)

) In-plane, the fins have less effect on the uniformity of longitudinal strength. More generally, the heat dissipating elements should extend outwardly away from and be oriented transverse to the surface of the diffuser.

To obtain higher light output intensity, a large number of high power LED devices are preferred. However, this is in conjunction with holding d_D/d_LThe requirement of a larger ratio to provide a large range of latitude angles over which the intensity distribution can be kept constant is contradictory, since more LED devices tend to increase the cross-sectional dimension d of the LED-based light source_L. Furthermore, the additional heat generated by high power LED devices and larger numbers of such devices may be too great in some particular embodiments to be suitable for utilizing passive heat dissipation.

A linear lamp embodiment is described next with reference back to the spherical embodiment of fig. 2-4. A spherical embodiment may be modified to a straight line lamp by removing rotational symmetry around the north (θ ═ 0 °) axis. In this linear embodiment, fig. 4 can be seen as a cross-sectional view taken along the linear axis of the linear lamp: the diffuser 10 is in this variant cylindrical with its cylindrical axis transverse to the drawing sheet, and the light sources 8 are elongated LED-based light sources extending parallel to the cylindrical axis of the (cylindrical) diffuser 10 and positioned tangentially to the surface of the (cylindrical) diffuser 10. The lambertian light intensity distribution shown in fig. 4 is only a one-dimensional lambertian distribution in this linear lamp variant embodiment, that is, a lambertian distribution in the plane of the drawing sheet if the LEDs are spaced appropriately close together. Thus, the lambertian intensity pattern produced by the (elongated) LED based light source 8 is suitably captured by the (cylindrical) diffuser 10 conforming to the cylindrical isoluminance surface of the lambertian intensity of the (elongated) LED based light source output. In order to use this embodiment to provide an isotropic cylindrical light source of uniform illumination, the LED devices 40 should be relatively closely spaced in a direction perpendicular to the drawing sheet, for example by an amount equivalent to the diameter of the diffuser cylinder.

Referring to fig. 13 and 14, yet another embodiment is disclosed. This embodiment is not a linear lamp, but is a LED lamp suitable for replacing an incandescent bulb and including an edison base connector 30 that facilitates use of the lamp as a retrofit incandescent bulb. An annular LED-based light source 150 is disposed on a cylindrical form or chimney (chimney)152 to emit light outwardly from the cylindrical form or chimney 152. This is actually a linear lamp as described herein and wrapped around a cylindrical form or chimney 152 to form a ring. The illumination intensity 154 produced by the annular light source 150 has a lambertian distribution in any plane perpendicular to the annular path of the ring (as shown in fig. 13), thereby producing an annular isoluminance surface with a circular cross-section if the LEDs are spaced appropriately closely. A toroidal diffuser 156 having a circular cross-section (best seen in fig. 13) is disposed to conform to the toroidal isoluminance surface of the illumination intensity 154. (Note that in FIG. 14, toroidal diffuser 156 is schematically shown in phantom to expose LED-based light source 150).

The annular LED-based light source 150 is disposed tangential to the inside surface of the toroidal diffuser 156 and transmits a lambertian illumination intensity into the toroidal diffuser 156. The toroidal diffuser 156 preferably has a lambertian diffusing surface, as schematically illustrated in fig. 13, such that the incident illumination 154 is diffusely reflected at every point on the surface to produce a lambertian intensity output pattern from the exterior from points on the surface of the toroidal diffuser 156. Thus, the lighting assembly comprising the annular LED-based light source 150 and the toroidal diffuser 156 of circular path cross-section is substantially omnidirectional in both latitudinal and longitudinal directions.

In fig. 13 and 14, toroidal diffuser 156 has a circular cross-section at any point along its toroidal path, such that toroidal diffuser 156 is a true torus. Similar to fig. 7 and 8, if the annular LED-based light source 150 has its lambertian intensity distribution distorted substantially in an oblong or oblate manner, then the circular cross-section of the toroidal diffuser 156 is suitably oblong or oblate circular to conform to an isoluminance surface, accordingly.

The chimney 152 shown in FIGS. 13 and 14 has a circular cross-section, and the annular light source 150 thus follows a circular path. Referring to FIG. 14A, in other embodiments, the chimney 152 has a polygonal cross-section (not shown) such as a triangular cross-section, a square cross-section, a hexagonal cross-section or an octagonal cross-section, in which case the ring-shaped light source suitably follows a corresponding polygonal (e.g., triangular, square, hexagonal or octagonal) path consisting of three adjacent planar circuit boards (for a triangle), four adjacent planar circuit boards (for a square), six adjacent planar circuit boards (for a hexagon) or eight adjacent planar circuit boards (for an octagon) or more commonly N adjacent planar circuit boards (for an N-sided polygonal chimney cross-section). For example, FIG. 14A shows a chimney 152 ' having a square cross-section, and a ring-shaped light source 150 ' conforming to a square path made up of four circuit boards spaced at 90 ° angles to form a square ring conforming to the rectangular cross-section of the chimney 152 '. A corresponding toroidal diffuser 156 '(again shown schematically in phantom to expose the light sources 150') is also substantially four-sided, but includes rounded corner transitions between adjacent sides of the four-sided ring to facilitate manufacturing and smooth light output.

Referring back to fig. 13 and 14, the lamp includes a base 160 that includes or supports a chimney 152 at one end and an edison base connector 30 at an opposite end. As shown in the cross-sectional view of fig. 13, the base 160 includes electronics that energize the annular LED-based light source 150 to emit illumination 154. As further shown in the cross-sectional view of fig. 13, the chimney 152 is hollow and houses a heat sink embodied as a coolant circulation fan 166 disposed inside the chimney 152. The electronics 162 also drive a coolant circulation fan 166. The fan 166 drives circulating air 168 through the chimney 152 and thus the near-ring shaped LED-based light source 150 cools the ring-shaped light source 150. Optionally, a heat sink element 170 (e.g., fins, pins, etc.) extends from the annular LED-based light source 150 to the interior of the hollow chimney 152 to further facilitate active cooling of the light source. Optionally, the chimney includes an air inlet to facilitate the flow of circulating air 168 (see FIG. 14).

The active heat removal provided by the coolant fan 166 may optionally be replaced by passive cooling, such as by fabricating a chimney of metal or other thermally conductive material, optionally with the addition of fins, pins, slots, or other features to increase its surface area. In other contemplated embodiments, the chimney is replaced with a similarly sized heat pipe, the "cool" end of which is disposed in a metal block contained in the base 160. In contrast, in the embodiments of fig. 5 and 6 and elsewhere, the passive heat dissipation described is optionally replaced with active heat dissipation using a fan or the like. Further, it is contemplated that the base heat sink element in these embodiments is an active heat sink element, such as a cooling fan, or other type of heat sink element (e.g., a heat pipe).

The lamp shown in fig. 13 and 14 is an integrated LED backup lamp that can be installed in a lighting socket (not shown) by connecting the base connector 30 and the lighting socket. The integrated LED backup lamp of fig. 13 and 14 is a self-contained omnidirectional LED backup lamp that does not rely on a socket to dissipate heat but can be driven by 110V or 220V ac, or 12V or 24V or other voltage dc supplied via the socket of the edison base connector 30.

To achieve omnidirectional illumination over a large range of latitudinal spans (e.g., over a range of latitudinal spans θ ═ 0 °,150 °), it is advantageous that the base 160 be relatively narrow, such as in the case of the cylindrical base 160 shown in fig. 13 and 14. Active heat dissipation through the fan 166 and hollow chimney 152 facilitates making the pedestal 160 relatively narrow while still providing adequate heat dissipation. In addition, FIG. 13 shows that the toroidal diffuser 156 extends outward in a plane transverse to the axis of the cylindrical chimney 152 and further expands the illumination to larger angles, for example, angles approaching θ ═ 180 °.

The LED back-up lamp of fig. 13 and 14 (with optional modifications such as that shown in fig. 14A) is particularly useful for retrofitting high wattage incandescent bulbs, for example, 60W to 100W or higher. Operating active cooling fan 166 desirably uses a wattage of one to several watts or less, which is negligible for these high wattage lamps, while active heat dissipation is capable of transferring heat and dissipating heat at the level of several tens of watts, so that high power LED devices operating with a drive current of one to several amps can be used. The cooling of the lamp of fig. 13 and 14 does not rely primarily on the edison base connector 30 to transfer heat to the socket, and therefore the LED back-up lamp of fig. 13 and 14 can be used with any standard screw socket regardless of the thermal load of the socket or corresponding hardware. The toroidal arrangement of the lamp assembly also facilitates spreading the LEDs along the toroidal path of the toroidal light source 150 to utilize a greater number of LEDs.

Referring to fig. 15-30, further embodiments are disclosed in which the diffuser is shaped and arranged relative to the LED-based light sources in the unitary LED lamp to provide uniform omnidirectional illumination of the LED-based light sources. These embodiments take into account the optical effect of the heat sink fins.

Referring to fig. 15, 16, 17, 18 and 19, illustrative examples of lamp embodiments suitable as LED-based light bulbs are shown. The lamp comprises a diffuser 200, a finned heat sink 202, and a base 204 (which is an edison base in the illustrated embodiment, but GU, bayonet, or other types of bases are also contemplated). Fig. 15, 16, 17, 18 and 19 show a perspective view, an alternative perspective view, a side view, a top view and a bottom view, respectively. FIGS. 20, 21, and 22 show side views of diffuser 200, diffuser 200 with its interior 206 exposed, and finned diffuser 200 with its fins 202, respectively, separately. The fins are part of a heat sink, extending over a portion of ovoid diffuser 200. The heat sink also includes a body portion 208 that houses power conditioning electronics (not shown) that convert the 110 vac input power (or 220 vac, or other selected input power) into a power suitable for driving the LEDs that input light into the aperture 210 of the diffuser 200.

As indicated in fig. 20, diffuser 200 is oval in shape with a single axis of symmetry 212 corresponding to "geographic north" or "N" along an elevation or latitude coordinate θ of 0. (see FIG. 1 and associated text for further description of an illustrative coordinate system employing either elevation or latitude coordinates θ). Ovoid diffuser 200 is rotationally symmetric about an axis of symmetry 212. In some embodiments, the rotational symmetry is continuous, i.e. the diffuser cross-section transverse to the axis of symmetry is circular (as shown). In other embodiments, the rotational pair of ovoid diffusers is referred to as N-fold symmetry, i.e., the ovoid diffuser cross-section transverse to the axis of symmetry (by way of some illustrative examples) is hexagonal (N-6) or octagonalShaped (N-8), and so on, optionally rounded at N vertices. A disadvantage of a low value of N for the symmetries is that they are relative to the azimuth or longitude (i.e. the coordinates as defined herein with reference to fig. 1)

) Potentially introducing an N-fold change. However, some advantages of using N-fold symmetry are ease of manufacture, handling and installation of the LED light bulb. Diffuser 200 is also referred to herein as an ovoid diffuser, even with N-fold rotational symmetry. In some N-fold rotational symmetry diffuser embodiments, the respective heat sink further comprises N fins aligned with the N-fold rotational symmetry diffuser.

Hole 210 is centered on axis of symmetry 212 at one end of ovoid diffuser 200. (Note that aperture 210 may include multiple sub-apertures 210 in some embodiments_SUBAs shown in the inset of fig. 20 looking at the aperture 210 along the axis of symmetry 212. For example, there may be one sub-aperture 210 per LED device_SUB. In this case, as shown in the inset, the apertures 210 are represented or approximated by these sub-apertures 210_SUBCumulative or total area spanned). The term "aperture" refers to the area where light is input into the ovoid diffuser 200 from an LED-based light source (e.g., a Lambertian or substantially Lambertian light source in some embodiments). The aperture 210 may be a solid open portion that receives or aligns with an LED-based light source, or may be a transparent window, light diffuser plate, or the like.

As shown in fig. 21, the illustrative ovoid diffuser 200 includes an ovoid housing 220 having or defining a hollow interior 206. Hollow ovoid diffuser 200 is suitably made of glass, transparent plastic, or the like. Alternatively, the ovoid diffuser may be contemplated as a solid component comprising a transparent material (e.g., glass, transparent plastic, etc.). Ovoid diffuser 200 may also optionally include a wavelength converting phosphor disposed on or within diffuser 200, or inside 206 of diffuser 200. Ovoid shell 220 is made to diffusely reflect light using suitable methods, such as surface texturing, and/or light scattering particles dispersed within the material of ovoid shell 220, and/or light scattering particles disposed on the surface of ovoid shell 220, and the like.

Referring to fig. 20-22, ovoid diffuser 200 optionally includes a neck region 222 that mounts diffuser 200 to the lamp body (e.g., to heat sinks 202, 208 in the illustrative embodiment, as best shown in fig. 22). In the neck region 222, ovoid diffuser 200 deviates from its ovoid shape. The neck region 222 in some embodiments is recessed within the cavity 224 of the lamp body 208 (see fig. 22 and 23) and thus does not emit light (or emits light that is absorbed by the heat sink lamp body 208 and thus does not produce omnidirectional illumination). Alternatively, the neck region may extend partially or entirely outside the lamp body for partial or overall light emission to produce omnidirectional illumination.

With continued reference to FIG. 20, ovoid diffuser 200 has an egg-shape with a relatively narrow proximal portion along length X of axis of symmetry 212 and a relatively wide distal portion along length Y of axis of symmetry 212. By "proximal" and "distal", it is illustrated that the proximal portion of length X is relatively more proximal to the aperture 210, while the distal portion of length Y is relatively more distal to the aperture 210. The illustrative ovoid diffuser 200 has a maximum diameter D transverse to the axis of symmetry 212 at the location where the proximal and distal ends or portions of respective lengths X and Y join or meet_max. Expected maximum diameter D_maxAlso referred to herein as the equatorial plane 230, is located above or below the location where the proximal and distal portions or portions join or meet. Axis of symmetry 212 and maximum diameter D_maxIs referred to herein as the origin 232. Ovoid diffuser 200, on the other hand, has a maximum diameter D transverse to axis of symmetry 212 for a transverse equatorial plane 230 containing an origin 232_max。

The total length of ovoid diffuser 200 in the direction of axis of symmetry 212 (i.e., along the direction of axis of symmetry 212) is X + Y. In some embodiments, the following conditions are satisfied: x > Y and X + Y > D_max. For the illustrative ovoid diffuser 200, the proximal portion of length X has a truncated prolate semi-ellipsoid shape, while the distal portion of length Y has an oblate semi-ellipsoid shape. More generally, X > Y is preferred. In some embodiments, X ≧ 1.5Y. In some embodiments, X ≧ 2Y. In some embodiments, X ≧ 3Y.

As best seen in fig. 22 and 23, the fins 202 of the heat sinks 202, 208 are not concave fins, which means that the tips of the fins 202 do not curve inward toward the axis of symmetry 212. By employing non-recessed fins, ovoid diffuser 200 and heat sinks 202, 208 may be manufactured and assembled separately. The non-recessed fins of heat sinks 202, 208 allow ovoid diffuser 200 to be inserted inside fins 202 until neck 222 mates with recessed cavity 224 of heat sinks 202, 208. A benefit of manufacturing is that diffuser 200 and heat sinks 202, 208 may be manufactured separately and optionally from different materials in order to optimize the light transmission and light scattering or diffusing properties of ovoid diffuser 200 and the thermal (optionally light reflecting) properties of heat sinks 202, 208.

The fins 202 create relatively little optical loss to the distal end compared to the proximal end. Because the fins 202 of the heat sinks 202, 208 are longitudinal

With a greatly limited range of directions, the fins 202 are expected not to strongly influence the omnidirectional illumination distribution in the longitudinal direction. However, measurements made by the inventors have shown that the fins 202 reduce the light output, particularly the angle below the equatorial plane 230. Without being bound to any particular theory of operation, these optical losses are considered to be due to light absorption, light scattering, or a combination thereof caused by the fins 202. In addition, the body portion 208 of the heat sink 202, 208 (and more generally, the body portion of the lamp) further limits the amount of omnidirectional illumination below the equatorial plane 230.

Referring to FIGS. 24, 25, and 26, the oblong/oblate design of oval diffuser 200 is utilized to reduce or eliminate the optical losses caused by the fins. FIG. 24 shows a comparison of the profile of ovoid diffuser 200 with the profile of an ideal spherical diffuser. Ovoid diffuser 200 is in the shape of a truncated prolate ellipsoid below equatorial plane 230 and an oblate ellipsoid above equatorial plane 230. FIG. 25 shows a comparison of the length of rays emitted from the LED array to the surface of the ideal spherical diffuser 240 and the length of rays to the ovoid diffuser 200. FIG. 26 illustrates identifying a normal angle with respect to the surface of ovoid diffuser 200. If the scatterer is ideally lambertian in the angular distribution, the scattered light from one point of the surface is at a maximum at an angle transverse to the surface. It will be noted in fig. 26 that the omnidirectional illumination below the equatorial plane 230 is largely from the proximal portion of length X, while the distal portion of length Y produces substantially omnidirectional illumination above the equatorial plane 230. Thus, the effect of relatively increasing the length X of the proximal portion of the oblong ellipse is to increase a portion of the light emitted below the equatorial plane 230 so as to compensate for optical losses below the equatorial plane 230 due to the fins 202 and/or body portion 208 of the heat sink. More than 50% of the total light emission surface area of the ovoid diffuser 200 is below the equatorial plane 230 for both the proximal (truncated) oblong semi-ellipsoid end and the distal oblate semi-ellipsoid end.

The distal portion of length Y has a lesser effect on light distribution at angles below equatorial plane 230 in comparison. Instead, the oblateness of the distal portion of the oblate may be adjusted to control the light distribution at angles above the equatorial plane 230. For example, the flatter oblate distal end portion of diffuser 200 may enhance light distribution at angles near geographic north N (i.e., near 0). The flattening may also be adjusted for other reasons to ensure that the overall length of the bulb falls within any of the maximum length ranges specified by applicable standards, such as the a-19 bulb standard. The total length of the LED bulb includes: (1) the summed length X + Y of ovoid diffuser 200, plus (2) the length of body portion 208 of the heat sink along axis of symmetry 212, and (3) the length of edison base 204 along axis of symmetry 212. Wherein the length of the edison base 204 is fixed by the applicable electrical connector standard, while the length of the body portion 208 of the heat sink is at least partially determined by the minimum size for accommodating the voltage regulating electronics. Thus, the summed length X + Y of ovoid diffuser 200 is the primary adjustable parameter to adjust the overall length of the LED bulb.

In some embodiments, the geometry of the ovoid diffuser has X + Y > D_maxAnd X > Y. In some embodiments, X ≧ 1.5Y, in some embodiments, X ≧ 2Y, in some embodiments, X ≧ 3Y. It can also be expressed by a surface area ratio. The surface area of the proximal portion of length X is denoted A_proxThe surface area of the distal end portion of length Y is denoted A_distAnd identifying the total surface area as A_totalAdvantageously A_prox/A_total> 0.5, and in some embodiments A_prox/A_total≧ 0.65, and in some embodiments A_prox/A_totalNot less than 0.75. More generally, ovoid diffuser 200 preferably tapers away from the wider end of aperture 210 to an egg shape adjacent the narrower end of aperture 210. The proximal end may be truncated by the aperture 210 as shown, but it is also contemplated that the aperture is small enough for the truncation to be negligible or non-existent.

In diffuser 200, to compensate for optical losses due to the thermal fins 202 and/or body portions 208 of the heat sink, the oblong proximal end of diffuser 200 increases the light flux directed from below the equatorial plane 230 of ovoid diffuser 200. The oblate distal portion is selected to tailor the light distribution at angles above the equatorial plane 230 and/or to preserve or set the desired overall height of the diffuser 200 (or LED light bulb as a whole), which in some applications is limited by ANSI regulations for applicable standards such as a-19 type light bulbs. Ovoid diffuser 200 provides a greater surface area having angles normal to the surface below the equatorial plane 230 relative to a surface area having angles normal to the surface at points above the equatorial plane 230. This compensates for the absorption and scattering of light by the thermal fins 202, which is more important for light emitted below the equatorial plane 203 than for light emitted above the equatorial plane 230.

Ovoid diffuser 200 has a geometry wherein the proximal portion having a length X has a truncated prolate ellipsoidal hemi-ellipsoid shape while the distal portion having a length Y has an oblate hemi-ellipsoid shape. Oval diffusers with variations in shape are contemplated. While the shape of the diffuser portions is shown in FIGS. 24, 25 and 26 as portions of oblong and oblate ellipsoids resulting in an oval shape, more generally, the proximal portion of the diffuser is characterized by a gradually increasing diameter (or lateral dimension according to distance away from the LED light sources) along the axis of symmetry 212, reaching a maximum diameter D at the equatorial plane 230_maxAnd the diffuser is characterized by having a decreasing diameter along the axis of symmetry 212 (or according to the distance from the LED light sources above the equatorial plane 230)The lateral dimension of the distance) to the farthest position at the top of the diffuser. The actual shape of the surfaces of the proximal and distal portions of the diffuser need not match the geometry of an ellipse, an oblong or oblate, or a hemisphere or sphere.

Fig. 27, 28, 29, and 30 show illustrative examples of some variations. FIG. 27 shows an ovoid diffuser 200a having the same oblong hemi-ellipsoid proximal end as diffuser 200, but with the oblate hemi-ellipsoid distal end replaced by a hemispherical distal end. FIG. 28 shows ovoid diffuser 200b having the same oblate hemi-ellipsoidal distal portion as diffuser 200, but a differently shaped proximal portion. The proximal portion of ovoid diffuser 200b is divided into two portions: a more proximal portion of frustoconical shape having a length X1 along axis of symmetry 212; and a slightly distal portion of an oblong shape having a length X2 along axis of symmetry 212. FIG. 29 shows ovoid diffuser 200c having the same (truncated) oblong hemi-ellipsoid proximal and oblate hemi-ellipsoid distal ends as diffuser 200, but further including a diffuser having a cylindrical shape and a height (or thickness) d disposed between the proximal and distal ends_transitionThe transition zone of (a). In this embodiment, the equatorial plane 230 is suitably provided with a thickness d_transitionInstead of a thin equatorial "panel" 230'. FIG. 30 shows ovoid diffuser 200d having the same (truncated) proximal portion of an oblong hemi-ellipsoid as diffuser 200, but having a distal portion of an oblate of length Y less than a fully oblate hemi-ellipsoid. Accordingly, ovoid diffuser 200d is abruptly interrupted at the junction and meeting of the proximal and distal portions or portions of lengths X and Y, respectively, at equatorial plane 230.

For a given LED-based light source, the large latitude range of interest θ ═ 0 °, θ_max]Substantially omnidirectional illumination in (b) is obtained by suitably adjusting the geometry of the ovoid diffuser, for example by having suitably chosen dimensions X, Y, d_maxOf the diffusers 200a, 200b, 200c, 200d, (and depending on the geometry of the template, such as d of the diffuser 200 c)_transitionOne or more additional dimensions of, or sub-lengths X1 and X2 of diffuser 200 b), and a relatively elongated proximal end and a relatively flat distal endOr a specific curvature of a part, where θ_maxMay be 120 deg. or 135 deg., etc. (maximum latitude angle theta of interest)_maxFor example, may be determined by the lighting standard that it is desired to meet). In this way, a lamp with a high omnidirectional lamp output is achieved, which likewise consists of relatively few parts. For example, the lamp component may include four main components: (1) a diffuser 200; (2) heat sinks 202, 208 (heat sink body 208 and fins 202 suitably comprise a single device); (3) an electronic module; and (4) a light engine comprising one or more LED devices mounted on a circuit board or other support.

However, depending on the particular light sources and tolerances of the manufacturing process, and the tolerances dictated by the lighting standard to which the lamp is to be subjected, it may be difficult to obtain a highly efficient standard-compliant lamp using only the diffuser 200 for achieving an omnidirectional illumination distribution. In this case, the oval diffuser 200, the bodies 200a, 200b, 200c, 200d may be combined with one or more secondary optical components to achieve a desired omnidirectional illumination distribution that is highly efficient in a mass production setting.

Referring to fig. 31, in one approach, a secondary optical element is provided. An illustrative method is based on the lamp of FIGS. 15-23 and includes ovoid diffuser 200 and finned heat sinks 202, 208. Fig. 31 also schematically illustrates a suitable light engine 250 that includes a circuit board on which one or more LED devices (not shown) are disposed. The secondary optical element includes a reflective, refractive, or optically transmissive light-scattering post 252 extending upwardly from the light engine 250 along the axis of symmetry 212, and optionally also includes a reflective, refractive, or optically transmissive light-scattering cap 254 at an end of the post 252 remote from the light engine 250. In some embodiments, the light engine 250 includes a central mounting hole that secures the light engine 250 in the lamp, in which case the post 252 may be implemented as a threaded shaft that also serves to secure (or help secure) the light engine 250 in the lamp. The light scattering posts 252 have the effect of scattering a portion of the light, either reflected or refracted or transmitted, that would otherwise be directed to a greater latitude angle at or near the "north" latitude (i.e., theta-0 deg.). The optional cap 254, which reflects or refracts or transmissively scatters light, further serves to scatter light into larger angles, particularly angles greater than 90 °. In embodiments where the components 252, 254 are fastening elements that secure (or help secure) the light engine 250, the cap 254 may also serve as a bolt head or screw head or other useful component of the fastener. The sides of the post 252 and/or the cap 254 may be angled or otherwise shaped to adjust the light distribution.

Referring to fig. 32, in an alternative approach, the secondary optic may be integrated with the light source. The illustrative method is again based on the lamp of fig. 15-23 and includes ovoid diffuser 200 and finned heat sinks 202, 208, and also includes light engine 250 of a circuit board on which one or more LED devices (not shown) are disposed. In the embodiment of fig. 32, the light engine 250 also includes (or alternatively, the light is considered to also include) a light scattering remote dome 260 disposed over the LED devices of the light engine, and optionally having an open perimeter secured to the circuit board of the light engine 250. The dome 260 may be inflated, or may be partially or entirely filled with silicone or other sealant. The dome 260 is optionally roughened or configured to provide optical diffusion, and/or optionally includes a non-contact phosphor (remotephosphor) disposed on an interior or exterior surface of the dome or embedded in the dome material. Some suitable light engines that include one or more LED devices covered by a dome mounted on a circuit board are described in U.S. patent No. 7,224,000 to Aanegola et al, U.S. patent No. 7,800,121 to Aanegola et al, U.S. patent No. 7,479,662 to Soules et al, and U.S. patent No. 2008/0054280a1 to Reginelli et al, which are incorporated herein by reference in their entirety. Some suitable light sources that include one or more LED devices covered by a dome mounted on a circuit board also include those available from general electric company

High brightness LED light engine. In addition to the shaping of the light distribution provided by ovoid diffuser 200, dome 260 also provides shaping of the light distribution. For example, when a light source including one or more lambertian light emitting LED chips disposed on a planar circuit board is at 90 ° θWhen there is substantially no light intensity, conversely,

the high brightness LED light engine has a substantial light intensity distribution component at θ 90 ° that cooperates with the ovoid diffuser 200 to provide an omnidirectional illumination distribution that is closer to the ideal omnidirectional distribution.

The secondary optic 252, 254, 260 shown in fig. 31 and 32 are illustrative examples. One or more of the illustrative secondary optics 252, 254, 260 or other secondary optics may be combined with one of the illustrative ovoid diffusers 200, 200a, 200b, 200c, 200d or with a spherical or ellipsoidal diffuser (such as shown in fig. 5-8 or 11) to provide an omnidirectional illumination distribution that more closely approximates a desired omnidirectional distribution. By way of another illustrative example, a cap or other additional coating or diffuser may be included to shape the light distribution.

The preferred embodiments have been shown and described. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (32)

1. A light emitting device comprising:

an LED-based lambertian light source;

an ovoid diffuser that produces a light intensity distribution output in response to illumination inside the ovoid diffuser, the ovoid diffuser including a lambertian diffuser such that the light intensity distribution is a lambertian distribution; the ovoid diffuser having an aperture sized to receive or mate with the LED-based Lambertian light source such that a principle emission surface of the LED-based Lambertian light source faces an interior of the ovoid diffuser and to pass light from the LED-based Lambertian light source into the ovoid diffuser through the aperture and provide an at least substantially uniform luminous flux impinging on an interior surface of the ovoid diffuser to produce at least substantially omnidirectional illumination from the device; and

a base including a base connector;

the LED-based Lambertian light source, the ovoid diffuser, and the base are secured together as a unitary LED lamp that is mountable in a lighting socket by connecting the base connector and the lighting socket;

the base operatively connects with the LED-based Lambertian light source in the unitary LED lamp to power the LED-based Lambertian light source with power received at the base connector;

wherein the ovoid diffuser has an aperture optically coupled to the LED-based Lambertian light source, a proximal portion disposed proximate to the aperture, and a distal portion disposed distal from the aperture, the proximal and distal portions having different shapes, wherein the proximal portion has a truncated oblong hemi-ellipsoidal shape;

wherein the ovoid diffuser is an egg-shaped diffuser comprising a relatively narrow proximal portion along a length X of its axis of symmetry and a relatively wide distal portion along a length Y of the axis of symmetry, the ovoid diffuser having a maximum diameter D transverse to the axis of symmetry at the location where the proximal and distal portions join_maxWherein the ovoid diffuser has a total length X + Y in a direction along the axis of symmetry, wherein X > Y and X + Y > D_max。

2. The light emitting apparatus as set forth in claim 1, wherein the ovoid diffuser has a single axis of rotational symmetry.

3. The light emitting apparatus as set forth in claim 2, wherein the ovoid diffuser has continuous or N-fold rotational symmetry about the single axis of rotational symmetry.

4. The light emitting apparatus as set forth in claim 1, wherein the ovoid diffuser is hollow and has an axis of rotational symmetry and an aperture centered on the axis of rotational symmetry, the LED-based Lambertian light source being disposed to illuminate inside the ovoid diffuser through the aperture.

5. The light emitting apparatus as set forth in claim 4, wherein the ovoid diffuser includes a proximal portion adjacent the aperture and having a length X along the axis of rotational symmetry and a distal portion distal from the aperture and having a length Y along the axis of rotational symmetry, where X > Y.

6. The light emitting apparatus as set forth in claim 5, wherein X ≧ 1.5Y.

7. The light emitting apparatus as set forth in claim 5, wherein X ≧ 2Y.

8. The light emitting apparatus as set forth in claim 5, wherein X ≧ 3Y.

9. The light emitting apparatus as set forth in claim 4, wherein the ovoid diffuser includes a proximal portion adjacent the aperture having a first shape and a distal portion distal from the aperture having a second shape, wherein the first shape is different than the second shape.

10. The light emitting apparatus as set forth in claim 9, wherein the proximal portion has a larger surface area than the distal portion.

11. The light emitting apparatus as set forth in claim 9, wherein a ratio of a surface area of the proximate portion to a total light emitting surface area of the ovoid diffuser is at least 0.65.

12. The light emitting apparatus as set forth in claim 9, wherein a ratio of a surface area of the proximate portion to a total light emitting surface area of the ovoid diffuser is at least 0.75.

13. The light emitting apparatus as set forth in claim 1, wherein the ovoid diffuser is egg-shaped with an aperture optically coupled with the LED-based Lambertian light source disposed at a narrower end of the egg-shape and a wider end of the egg-shape distal from the aperture.

14. The light emitting apparatus as set forth in claim 1, wherein the distal end portion has an oblate shape.

15. The light emitting apparatus as set forth in claim 14, wherein the distal portion has an oblate semi-ellipsoidal shape.

16. The light emitting apparatus as set forth in claim 1, wherein the distal end portion has a spherical shape.

17. The light emitting apparatus as set forth in claim 16, wherein the distal end portion has a hemispherical shape.

18. The light emitting apparatus as set forth in claim 1, wherein the ovoid diffuser has an axis of symmetry about which both the proximate and distal portions have rotational symmetry.

19. The light emitting apparatus as set forth in claim 18, wherein the ovoid diffuser has a maximum dimension transverse to the axis of symmetry at an equatorial plane or panel located at or between the proximate and distal portions.

20. The light emitting apparatus as set forth in claim 19, wherein the ovoid diffuser is smoothly continuous across an equatorial plane at the intersection of the proximate and distal portions.

21. The light emitting apparatus as set forth in claim 19, wherein the ovoid diffuser is discontinuous across an equatorial plane at the intersection of the proximate and distal portions.

22. The light emitting apparatus as set forth in claim 19, wherein the ovoid diffuser further comprises a transition zone disposed at an equatorial plane between the proximal and distal ends.

23. The light emitting apparatus of claim 22 wherein the transition region at the equatorial panel has a cylindrical shape.

24. The light emitting apparatus of claim 1, further comprising:

a heat sink element extending over the proximal end disposed adjacent the aperture.

25. The light emitting apparatus as set forth in claim 24, wherein the heat sink element is a fin.

26. The light emitting apparatus as set forth in claim 24, wherein the heat sink element does not extend over the distal end.

27. The light emitting apparatus as set forth in claim 24, wherein the heat sink element is part of an integral heat sink separate from the ovoid diffuser, and the ovoid diffuser is sized and shaped to enable the ovoid diffuser to be secured to the integral heat sink while positioned inside the heat fins.

28. A light emitting device comprising:

an LED-based lambertian light source;

a base comprising a base connector, the base configured to power the LED-based Lambertian light source with power received by the base connector; and

an ovoid diffuser comprising a lambertian diffuser having a light input aperture sized to receive or mate with the LED-based lambertian light source such that a principle emission surface of the LED-based lambertian light source faces an interior of the ovoid diffuser, light from the LED-based lambertian light source passing through the light input aperture into the ovoid diffuser, the ovoid diffuser comprising: (i) a first portion disposed adjacent to the light input aperture and having an outer surface area and having an increasing maximum lateral dimension away from the light input aperture, and (ii) a second portion disposed away from the light input aperture and having an outer surface area and having a decreasing maximum lateral dimension away from the light input aperture, and (iii) a mid-plane location at which the maximum lateral dimension is equal to or greater than the dimensions of the first portion and the second portion;

wherein the first portion has an outer surface area that is greater than an outer surface area of the second portion; and is

Wherein the LED-based Lambertian light source provides an at least substantially uniform luminous flux impinging on the interior surface of the ovoid diffuser to produce at least substantially uniform omnidirectional illumination from the apparatus; and is

Wherein the LED-based Lambertian light source, the base, and the diffuser housing are secured together as a unitary LED lamp that is mountable in a lighting socket by connecting the base connector and the lighting socket;

wherein the ovoid diffuser has an aperture optically coupled to the LED-based Lambertian light source, a proximal portion disposed proximate to the aperture, and a distal portion disposed distal from the aperture, the proximal and distal portions having different shapes, wherein the proximal portion has a truncated oblong hemi-ellipsoidal shape;

wherein the ovoid diffuser is an egg-shaped diffuser comprising a relatively narrow proximal portion along a length X of its axis of symmetry and a relatively wide distal portion along a length Y of the axis of symmetry, the ovoid diffuser having a maximum diameter D transverse to the axis of symmetry at the location where the proximal and distal portions join_maxWherein the ovoid diffuser has a total length X + Y in a direction along the axis of symmetry, wherein X > Y and X + Y > D_max。

29. A light emitting device comprising:

an LED-based lambertian light source;

a base comprising a base connector, the base configured to power the LED-based Lambertian light source with power received by the base connector; and

an ovoid diffuser comprising a lambertian diffuser having a light input aperture sized to receive or mate with the LED-based lambertian light source such that a principle surface of the LED-based lambertian light source faces an interior of the diffuser, the ovoid diffuser being an egg-shaped diffuser comprising the light input aperture at a narrower end of the egg-shaped diffuser; and is

Wherein the LED-based Lambertian light source provides an at least substantially uniform luminous flux impinging on the interior surface of the diffuser to produce at least substantially uniform omnidirectional illumination from the device; and is

Wherein the LED-based Lambertian light source, the base, and the diffuser housing are secured together as a unitary LED lamp that is mountable in a lighting socket by connecting the base connector and the lighting socket;

wherein the ovoid diffuser has an aperture optically coupled to the LED-based Lambertian light source, a proximal portion disposed proximate to the aperture, and a distal portion disposed distal from the aperture, the proximal and distal portions having different shapes, wherein the proximal portion has a truncated oblong hemi-ellipsoidal shape;

wherein the ovoid diffuser includes a relatively narrow proximal portion along a length X of its axis of symmetry and a relatively wide distal portion along a length Y of the axis of symmetry, the ovoid diffuser having a maximum diameter D transverse to the axis of symmetry at the point where the proximal and distal portions join_maxWherein the ovoid diffuser has a total length X + Y in a direction along the axis of symmetry, wherein X > Y and X + Y > D_max。

30. The apparatus as set forth in claim 29, further comprising an LED-based lambertian light source optically coupled into the light input aperture at the narrower end of the egg-shaped diffuser.

31. The light emitting apparatus as set forth in claim 30, further comprising a post disposed in the egg-shaped diffuser distal from and extending along an optical axis of the LED-based lambertian light source.

32. The light emitting apparatus as set forth in claim 30, further comprising a dome-shaped light transmissive diffuser or a non-contact phosphor disposed above the LED-based lambertian light source and inside the egg-shaped diffuser.

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