Patent Grant
9446709
The present invention generally relates to vehicle lighting systems, and more particularly, to vehicle lighting systems employing photoluminescent structures.
Illumination arising from photoluminescent structures offers a unique and attractive viewing experience. It is therefore desired to incorporate such photoluminescent structures in a vehicle lighting system to provide ambient and task lighting.
According to one aspect of the present invention, a vehicle backlit assembly is provided and includes a support member and at least one backlit interactive member at least partially extending through an opening in the support member. An excitation source is operable to emit a primary emission for backlighting the at least one backlit interactive member. A photoluminescent structure is coupled to the at least one backlit interactive member and is formulated to convert the primary emission into a secondary emission. An opaque layer is coupled to the photoluminescent structure and defines an opening through which the secondary emission is transmitted.
According to another aspect of the present invention, a vehicle backlit assembly is provided and includes an interactive member configured to be supported in a trimplate and has a light conducting body. A photoluminescent structure is coupled to the light conducting body and configured to receive through an input surface a primary emission comprising at least one of a first inputted electromagnetic radiation, a second inputted electromagnetic radiation, and a third inputted electromagnetic radiation. The photoluminescent structure contains a red-emitting photoluminescent material formulated to convert the first inputted electromagnetic radiation into a first outputted electromagnetic radiation, a green-emitting photoluminescent material formulated to convert the second inputted electromagnetic radiation into a second outputted electromagnetic radiation, and a blue-emitting photoluminescent material formulated to convert the third inputted electromagnetic radiation into a third outputted electromagnetic radiation.
According to another aspect of the present invention, a vehicle backlit assembly is provided and includes a support member for supporting at least one interactive member. A photoluminescent structure is coupled to the at least one interactive member and formulated to convert at least one inputted electromagnetic radiation into at least one outputted electromagnetic radiation expressing a color sensation found in an RGB color space.
These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.
In the drawings:
As required, detailed embodiments of the present invention are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to a detailed design and some schematics may be exaggerated or minimized to show function overview. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
As used herein, the term “and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.
The following disclosure describes a vehicle lighting system in which a vehicle fixture receives a photoluminescent structure for converting a primary emission into a secondary emission generally having a new color. For purposes of this disclosure, a vehicle fixture refers to any interior or exterior piece of vehicle equipment, or part thereof, suitable for receiving the photoluminescent structure described herein. While the implementation of the vehicle lighting system described herein is primarily directed towards automotive vehicle use, it should be appreciated that the vehicle lighting system may also be implemented in other types of vehicles designed to transport one or more passengers such as, but not limited to, watercrafts, trains, and aircrafts.
Referring to
Referring to
The energy conversion layer 18 may be prepared by dispersing the photoluminescent material in a polymer matrix to form a homogenous mixture using a variety of methods. Such methods may include preparing the energy conversion layer 18 from a formulation in a liquid carrier medium and coating the energy conversion layer 18 to a desired planar and/or non-planar substrate of a vehicle fixture. The energy conversion layer 18 coating may be deposited on the selected vehicle fixture by painting, screen printing, spraying, slot coating, dip coating, roller coating, and bar coating. Alternatively the energy conversion layer 18 may be prepared by methods that do not use a liquid carrier medium. For example, a solid state solution (homogenous mixture in a dry state) of one or more photoluminescent materials in a polymer matrix may be converted to the energy conversion layer 18 by extrusion, injection molding, compression molding, calendaring, and thermoforming. In instances where one or more energy conversion layers 18 are rendered as particles, the single or multi-layered energy conversion layers 18 may be implanted into the chosen vehicle fixture instead of applying it as a coating. When the energy conversion layer 18 includes a multilayer formulation, each layer may be sequentially coated, or the layers can be separately prepared and later laminated or embossed together to form an integral layer. Alternatively, the layers may be coextruded to prepare an integrated multi-layered energy conversion structure.
Referring back to
The stability layer 20 and/or the protection layer 22 may be combined with the energy conversion layer 18 to form an integrated photoluminescent structure 16 through sequential coating or printing of each layer, or by sequential lamination or embossing. Alternatively, several layers may be combined by sequential coating, lamination, or embossing to form a substructure, and the required substructure then laminated or embossed together to form the integrated photoluminescent structure 16. Once formed, the photoluminescent structure 16 may be applied to a chosen vehicle fixture. Alternatively, the photoluminescent structure 16 may be incorporated into the chosen vehicle fixture as one or more discrete multilayered particles. Alternatively still, the photoluminescent structure 16 may be provided as one or more discrete multilayered particles dispersed in a polymer formulation that is subsequently applied to the chosen vehicle fixture as a contiguous structure. Additional information regarding the construction of photoluminescent structures is disclosed in U.S. Pat. No. 8,232,533 entitled “PHOTOLYTICALLY AND ENVIRONMENTALLY STABLE MULTILAYER STRUCTURE FOR HIGH EFFICIENCY ELECTROMAGNETIC ENERGY CONVERSION AND SUSTAINED SECONDARY EMISSION,” the entire disclosure of which is incorporated herein by reference.
Referring to
The excitation source 26 is generally shown in an external location relative to the photoluminescent structure 16 and is operable to emit a primary emission having a light content defined by a first inputted electromagnetic radiation represented as directional arrow 28, a second inputted electromagnetic radiation represented as directional arrow 30, and/or a third inputted electromagnetic radiation represented as directional arrow 32. The contribution of each inputted electromagnetic radiation 28, 30, 32 in the primary emission depends on an activation state of a corresponding light emitting diode (LED) configured to output light at a unique peak wavelength. In both configurations, the first inputted electromagnetic radiation 28 is emitted from blue LED 34 at a peak wavelength λ1 selected from a blue spectral color range, which is defined herein as the range of wavelengths generally expressed as blue light (˜450-495 nanometers). The second inputted electromagnetic radiation 30 is emitted from blue LED 36 at a peak wavelength λ2 also selected from the blue spectral color range and the third inputted electromagnetic radiation 32 is emitted from blue LED 38 at a peak wavelength λ3 further selected from the blue spectral color range.
By virtue of peak wavelengths λ1, λ2, and λ3 having different lengths, blue LEDs 34, 36, and 38 may each be primarily responsible for exciting one of the red, green, and blue-emitting photoluminescent materials X1, X2, X3. Specifically, blue LED 34 is primarily responsible for exciting the red-emitting photoluminescent material X1, blue LED 36 is primarily responsible for exciting the green-emitting photoluminescent material X2, and blue LED 38 is primarily responsible for exciting the blue-emitting photoluminescent material X3. For more efficient energy conversion, the red-emitting photoluminescent material X1 is selected to have a peak absorption wavelength corresponding to the peak wavelength λ1 associated with the first inputted electromagnetic radiation 28. When excited, the red-emitting photoluminescent material X1 converts the first inputted electromagnetic radiation 28 into a first outputted electromagnetic radiation represented as directional arrow 46 and having a peak emission wavelength E1 that includes a wavelength of a red spectral color range, which is defined herein as the range of wavelengths generally expressed as red light (˜620-750 nanometers). Likewise, the green-emitting photoluminescent material X2 is selected to have a peak absorption wavelength corresponding to the peak wavelength λ2 of the second inputted electromagnetic radiation 30. When excited, the green-emitting photoluminescent material X2 converts the second electromagnetic radiation 30 into a second outputted electromagnetic radiation represented as directional arrow 48 and having a peak emission wavelength E2 that includes a wavelength of a green spectral color range, which is defined herein as the range of wavelengths generally expressed as green light (˜526-606 nanometers). Lastly, the blue-emitting photoluminescent material X3 is selected to have a peak absorption wavelength corresponding to the peak wavelength λ3 of the third inputted electromagnetic radiation 32. When excited, the blue-emitting photoluminescent material X3 converts the third inputted electromagnetic radiation 32 into a third outputted electromagnetic radiation represented as arrow 50 and having a peak emission wavelength E3 that includes a longer wavelength of the blue spectral color range.
Given the relatively narrow band of the blue spectral color range, it is recognized that some spectral overlap may occur between the absorption spectrums of the red, green, and blue-emitting photoluminescent materials X1, X2, X3. This may result in the inadvertent excitement of more than one of the red, green, and blue-emitting photoluminescent materials X1, X2, X3 despite only one of the blue LEDs 34, 36, 38 being active, thereby producing unexpected color mixtures. Thus, if desiring greater color separation, the red, green, and blue-emitting photoluminescent materials X1, X2, X3 should be selected to have narrow band absorption spectrums for minimizing any spectral overlap therebetween and peak wavelengths λ1, λ2, and λ3 should be spaced apart to enable sufficient separation between the peak absorption wavelengths of the red, green, and blue-emitting photoluminescent materials X1, X2, X3. In this manner, depending on which of the red, green, and blue-emitting photoluminescent materials X1, X2, X3 are excited, a secondary emission having a more predictable light content may be produced. The secondary emission may express a variety of colors found in a typical RGB color space, including colors that are predominately red, green, blue, or any combination thereof. For example, when blue LEDs 34, 36, and 38 are activated simultaneously, the secondary emission may contain an additive light mixture of red, green, and blue light, which is generally perceived as white light. Other color sensations found in the RGB color space may be produced by activating blue LEDs 34, 36, and 38 in different combinations and/or changing the output intensity associated with the blue LEDs 34, 36, 38 through current control, pulsewidth modulation (PWM), or other means.
Regarding the vehicle lighting system 24 disclosed herein, blue LEDs 34, 36, and 38 are chosen as the excitation source 26 to take advantage of the relative cost benefit attributed therewith when used in vehicle lighting applications. Another advantage of using blue LEDs 34, 36, and 38 is the relatively low visibility of blue light, which may present less of a distraction to a vehicle driver and other occupants in instances where the primary emission must propagate in plain view before reaching the photoluminescent structure 16. Nevertheless, it should be appreciated that the vehicle lighting system 24 may also be implemented using other lighting devices as well as sunlight and/or ambient light. Furthermore, given the range of vehicle fixtures capable of receiving the photoluminescent structure 16, it should also be appreciated that the location of the excitation source 26 will naturally vary depending on the makeup of a particular vehicle fixture and may be external or internal to the photoluminescent structure 16 and/or the vehicle fixture. It should further be appreciated that the excitation source 26 may provide the primary emission directly or indirectly to the photoluminescent structure 16. That is, the excitation source 26 may be positioned such that the primary emission propagates towards the photoluminescent structure 16 or positioned such that the primary emission is distributed to the photoluminescent structure 16 via a light pipe, optical device, or the like.
The energy conversion process used by each of the red, green, and blue-emitting photoluminescent materials X1, X2, X3 described above may be variously implemented given the wide selection of energy conversion elements available. According to one implementation, the energy conversion process occurs through a single absorption/emission event driven by one energy conversion element. For instance, the red-emitting photoluminescent material X1 may include a phosphor exhibiting a large Stokes shift for absorbing the first inputted electromagnetic radiation 28 and subsequently emitting the first outputted electromagnetic radiation 46. Likewise, the green-emitting photoluminescent material X2 may also include a phosphor exhibiting a large Stokes shift for absorbing the second inputted electromagnetic radiation 48 and emitting the second outputted electromagnetic radiation. One benefit of using a phosphor or other energy conversion element exhibiting a large Stokes shift is that greater color separation may be achieved between an inputted electromagnetic and an outputted electromagnetic radiation due to a reduction in spectral overlap between the corresponding absorption and emission spectrums. Similarly, by exhibiting a single Stokes shift, the absorption and/or emission spectrums for a given photoluminescent material are less likely to have spectral overlap with the absorption and/or emission spectrums of another photoluminescent material thereby providing greater color separation between the selected photoluminescent materials.
According to another implementation, the energy conversion process occurs through an energy cascade of absorption/emission events driven by a plurality of energy conversion elements with relatively shorter Stokes shifts. For example, the red-emitting photoluminescent material X1 may contain fluorescent dyes, whereby some or all of the first inputted electromagnetic radiation 28 is absorbed to emit a first intermediate electromagnetic radiation having a longer wavelength and a color that is not characteristic of the first inputted electromagnetic radiation 28. The first intermediate electromagnetic radiation is then absorbed a second time to emit a second intermediate electromagnetic radiation having yet a longer wavelength and a color that is not characteristic of the first intermediate electromagnetic radiation. The second intermediate electromagnetic radiation may be further converted with additional energy conversion elements exhibiting the appropriate Stokes shifts until the desired peak emission wavelength E1 associated with the first outputted electromagnetic radiation 46 is obtained. A similar energy conversion process may also be observed for the green-emitting photoluminescent material X2. While energy conversion processes implementing energy cascades may produce broad color spectrums, increasing the number of Stokes shifts may result in less efficient down conversions due to a greater likelihood of spectral overlap between the associated absorption and emission spectrums. In addition, if desiring greater color separation, additional consideration should be exercised such that the absorption and/or emission spectrums of a photoluminescent material have minimal overlap with the absorption and/or emission spectrums of another photoluminescent material also implementing an energy cascade or some other energy conversion process.
Regarding the blue-emitting photoluminescent material X3, successive conversions of the third inputted electromagnetic radiation 32 via an energy cascade are unlikely to be necessary since the inputted electromagnetic radiation 32 and the outputted electromagnetic radiation 50 are both predisposed to have relatively close peak wavelengths in the blue spectral color range. Thus, the blue photoluminescent material X3 may include an energy conversion element exhibiting a small Stokes shift. If desiring greater color separation, the blue photoluminescent material X3 should be selected with an emission spectrum having minimal spectral overlap with the absorption spectrums of the red and green-emitting photoluminescent materials X1, X2. Alternatively, an ultraviolet LED may replace blue LED 38 to enable an energy conversion element exhibiting a larger Stokes shift to be used and to provide more flexible spacing opportunities for the emission spectrum of the blue-emitting photoluminescent material X3 within the blue spectral color range. For front-lit configurations, the photoluminescent structure 16 may alternatively include a narrowband reflective material configured to reflect the third inputted electromagnetic radiation 32 emitted from blue LED 38 in lieu of performing an energy conversion thereto to express blue light, which obviates the need for including the blue-emitting photoluminescent material X3. Alternatively, the aforementioned reflective material may be configured to reflect a selected amount of the first and second inputted electromagnetic radiations 28, 30 to express blue light, thereby obviating the need for including the blue-emitting photoluminescent material X3 and blue LED 38. For back-lit configurations, blue light may alternatively be expressed by merely relying on some amount of the third inputted electromagnetic radiation 32 passing through the photoluminescent structure 16, wherein the blue-emitting photoluminescent material X3 has been omitted.
Since many energy conversion elements are Lambertian emitters, the resulting secondary emissions may be propagated in all directions, including directions pointing away from a desired output surface 52 of the photoluminescent structure 16. As a result, some or all of the secondary emissions may be trapped (total internal reflection) or absorbed by corresponding structures (e.g. the vehicle fixture 42), thereby reducing the luminosity of the photoluminescent structure 16. To minimize the aforementioned phenomenon, the photoluminescent structure 16 may optionally include at least one wavelength-selective layer 54 formulated to redirect (e.g. reflect) wayward propagating secondary emissions towards the output surface 52, which also behaves as an input surface 56 with respect to front-lit configuration shown in
In both configurations, the wavelength-selective layer 54 is positioned between the substrate 40 and the energy conversion layer 18 so that at least some secondary emissions propagating towards the substrate 40 are redirected towards the output surface 52 to maximize the output of the secondary emission from the photoluminescent structure 16. To this end, the wavelength-selective layer 54 should at the very least be prepared from materials that scatter, but do not absorb, the peak emission wavelengths E1, E2, E3 associated with the first, second, and third outputted electromagnetic radiations 46, 48, 50, respectively. The wavelength-selective layer 54 may be rendered as a coating and is optically coupled to the energy conversion layer 18 and adhered to both the energy conversion layer 18 and the substrate 40 using some of the previously described methods, or other suitable methods.
Referring to
Referring to
Referring to
According to the present embodiment, the excitation source 26 is positioned to provide a primary emission in the form of backlighting, as represented by directional arrow 84 to the backlit interactive member 70a. The primary emission 84 may be provided directly from the excitation source 26 or indirectly via a light pipe, optical device, or the like and may contain one or more inputted electromagnetic radiations, each having a uniquely associated peak wavelength and each being emitted from a corresponding LED.
The primary emission 84 is supplied to the front side 78 of the backlit interactive member 70a and is transmitted therethrough. The primary emission 84 is then received in the photoluminescent structure 16, which may convert substantially all of the primary emission into a secondary emission containing one or more outputted electromagnetic radiations, each having a uniquely associated peak emission wavelength. Alternatively, the photoluminescent structure 16 may convert some of the primary emission into the secondary emission and transmit the rest as an unconverted outputted electromagnetic radiation. In any event, one or more outputted electromagnetic radiations, collectively represented by arrow 86, exit through the output surface 52 of the photoluminescent structure 16 and express a color sensation found in an RGB color space.
To bolster the luminosity of the photoluminescent structure 16, a wavelength-selective layer 54 may be provided therein for redirecting any backscattered secondary emissions 86 towards the output surface 52. Optionally, an opaque layer 88 is coupled to at least the photoluminescent structure 16 and defines an opening 90 that is characteristic of an insignia through which the secondary emission 86 is transmitted, thereby illuminating the insignia.
Referring to
In the illustrated embodiment, excitation sources 26a-26d are each operably coupled to an associated headrest 98a-98d and optically configured to illuminate a corresponding corner area 96a-96d of the photoluminescent structure 16 in a generally circular pattern. Excitation sources 26e and 26f are each optically coupled to an associated b-pillar 100e, 100f and are each optically configured to illuminate a corresponding side area 96e, 96f of the photoluminescent structure 16 in a generally half-circular pattern. Lastly, excitation source 26g is operably coupled to the vehicle headliner 94 and optically configured to illuminate a corresponding central area 96g in a generally circular pattern. As can be seen in
Accordingly, a vehicle lighting system 24 has been described herein. The vehicle lighting system 24 advantageously employs a photoluminescent structure 16 capable of converting a primary emission into a secondary emission to provide a variety of color sensations, thereby enhancing a driving experience and/or general appearance of a vehicle fixture.
It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.
This application is a Continuation-In-Part of U.S. patent application Ser. No. 14/086,442, filed Nov. 21, 2013, and entitled “VEHICLE LIGHTING SYSTEM WITH PHOTOLUMINESCENT STRUCTURE,” the entire disclosure of which is incorporated herein by reference.
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