Color tunable hybrid LED-OLED illumination devices

A hybrid LED-OLED lighting device includes a waveguide layer, a light-emitting diode (LED) array optically coupled to the waveguide layer, and an organic light-emitting diode (OLED) array. Light emitted from the LED array is provided to an edge of the waveguide layer and light emitted from the OLED array is provided to a first surface of the waveguide layer. Light emitted from the LED array and light emitted from the OLED array passes through a second surface of the waveguide layer opposite the first surface of the waveguide layer, and light emitted from the lighting device comprises the light emitted from the LED array and the light emitted from the OLED array.

TECHNICAL FIELD

This invention relates to color tunable hybrid LED (light-emitting diode)-OLED (organic light-emitting diode) illumination devices with high efficiency and stability.

BACKGROUND

Efficient and stable light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs) available in some, but not all, colors. While LED and OLED based illumination devices have been developed, tunable indoor illumination with uniform planar emission and high efficiency and stability has not been achieved.

SUMMARY

In a first general aspect, a hybrid LED-OLED lighting device includes a waveguide layer, a light-emitting diode (LED) array optically coupled to the waveguide layer, and an organic light-emitting diode (OLED) array. Light emitted from the LED array is provided to an edge of the waveguide layer and light emitted from the OLED array is provided to a first surface of the waveguide layer. Light emitted from the LED array and light emitted from the OLED array passes through a second surface of the waveguide layer opposite the first surface of the waveguide layer, and light emitted from the lighting device comprises the light emitted from the LED array and the light emitted from the OLED array.

Implementations of the first general aspect may include one or more of the following features.

The light emitted from the LED array is in the blue range of the visible spectrum. The light emitted from the OLED array is in the yellow or amber range of the visible spectrum. The light emitted by the lighting device is white light (e.g., warm white light or cool white light). The light emitted by the lighting device is tunable. An intensity of the LED array and an intensity of the OLED array are independently controllable.

The edge of the waveguide layer extends between the first surface and the second surface of the waveguide layer. In some cases, the edge of the waveguide layer is approximately perpendicular to the first surface of the waveguide layer. The lighting device may include a reflective layer in direct contact with the first surface of the waveguide layer. In some cases, the lighting device includes a diffuser film in direct contact with the second surface of the waveguide layer. In certain cases, the lighting device of claim1includes an optical index matching adhesive between the diffuser film and the second surface of the waveguide layer.

The OLED array is coupled (e.g., optically coupled) to and configured to illuminate the first surface of the waveguide layer. In some implementations, a reflective metallic electrode of the OLED array is positioned between the waveguide layer and a substrate on which the OLED array is fabricated. In certain implementations, the waveguide layer and a light transmissive electrode of the OLED array are separated by a substrate on which the OLED array is fabricated. The OLED array may be fabricated on the waveguide layer. The LED array is typically edge-lit, and the OLED array is typically back lit.

A LED diffuser structure including the waveguide layer may further include a prism protecting film, a lenz film, a prism film, or any combination thereof. An OLED structure including the OLED array may further include an internal extraction layer, an external extraction layer, or both. In one example, the OLED structure includes an internal extraction layer, an external extraction layer, and a substrate between the internal extraction layer and the external extraction layer.

Each OLED in the OLED array typically has a cavity length selected to provide a resonance condition for emission of yellow or amber light. In some cases, each OLED in the OLED array includes an emitter represented by General Formula I:

In certain cases, each OLED in the OLED array includes an emitter represented by General Formulas II-IX:

DETAILED DESCRIPTION

Color tunable hybrid LED (light-emitting diode)-OLED (organic light-emitting diode) illumination devices for emitting cool white light and warm white light with high efficiency and stability are described. Electroluminescent (EL) spectra of these hybrid devices can be modified by individually controlling the driving current of the LED and OLED, thereby emitting light over a spectral range from cool white light with exclusive LED emission to warm white light with dominant OLED emission.

FIG.1Adepicts color tunable hybrid LED-OLED device100. Hybrid device100includes LED array102. LED array102includes one or more LEDs104arranged in optical housing106. Each LED104can emit cool white light with a color temperature of over 5000 K or blue light in a range of about 440 nm to about 500 nm. LED array102includes electrodes108,110. Optical housing106is configured to direct light from LEDs104toward waveguide layer112in hybrid device100with minimum spacing between LED array102and waveguide layer112to optimize the efficiency of the LED diffuser light source depicted inFIG.2. Waveguide layer112is an optical waveguide, typically made of a glass, polymer, or semiconductor material, and having a planar, strip, or fiber configuration for guiding visible radiation. As depicted, LED array102is edge-lit, such that light from LED array102is optically coupled to waveguide layer112in hybrid device100. Hybrid device100may include two or more LED arrays102optically coupled to two or more sides of hybrid device100.

In some implementations, waveguide layer112may serve as a substrate for OLED fabrication. In some implementations, hybrid device100includes a separate substrate114in contact with (e.g., in direct contact with) waveguide layer112on which OLED array116is fabricated. Substrate114is typically formed of glass or plastic. OLED array116includes one or more OLEDs118. Each OLED118typically emits yellow or amber light exhibiting a broad emission spectrum ranging from about 480 nm to about 700 nm. OLED array116is back-lit and includes opaque and reflective metallic electrode120and light transmissive electrode122. In some implementations, OLED array116includes one or more of an internal extraction layer and an external extraction layer. LED array102and OLED array116can be independently controlled.

During operation of LED array102, light travels from LEDs104through waveguide layer112and exits hybrid device100through diffuser film124. Diffuser film124is typically a thin film of translucent material, such as ground glass, TEFLON, holographs, opal glass, and greyed glass that diffuses or scatters light in some manner to transmit soft light. A reflective film between waveguide layer112and substrate114can inhibit light from LED array102from entering substrate114. Waveguide layer112typically includes an optical medium and nanoparticles126. During operation of OLED array116, light travels from OLEDs118toward substrate114, passes through waveguide layer112and through diffuser film124to exit hybrid device100. As described in more detail with respect toFIG.2, hybrid device100can include one or more of a prism film, a lenz film, and a prism protective film on diffuser film124. Nanoparticles126in waveguide layer112facilitate scattering of light128in a selected visible spectrum. When LED array102emits blue light and OLED array116emits amber or yellow light, hybrid device100emits tunable white light.

FIG.1Bdepicts color tunable hybrid LED-OLED device130. Hybrid device130includes LED array102. LED array102includes one or more LEDs104arranged in optical housing106. Each LED104can emit cool white light with a color temperature of over 5000 K or blue light in a range of about 440 nm to about 500 nm. LED array102includes electrodes108,110. Optical housing106is configured to direct light from LEDs104toward waveguide layer112in hybrid device130. As depicted, LED array102is edge-lit, such that light from LED array102is optically coupled to waveguide layer112in hybrid device130.

Hybrid device130may include two or more LED arrays102optically coupled to two or more sides of hybrid device130. OLED array116, positioned between waveguide layer112and substrate114, includes one or more OLEDs118. Substrate114is typically formed of glass or plastic. Each OLED118typically emits yellow or amber light. OLED array116is back-lit and includes opaque and reflective metallic electrode120and light transmissive electrode122. As described in more detail with respect toFIG.3, OLED array116can include one or more of an internal extraction layer and an external extraction layer to enhance outcoupling of light from OLED array116. LED array102and OLED array116can be independently controlled.

During operation of LED array102, light travels from LEDs104through waveguide layer112and exits hybrid device130through diffuser film124. Waveguide layer112typically includes an optical medium and nanoparticles126. During operation of OLED array116, light travels from OLEDs118through waveguide layer112and through diffuser film124to exit hybrid device130. Thus, light from OLED array116exits hybrid device130without losses associated with passing through substrate114. As described in more detail with respect toFIG.3, OLED array116can include one or more of an internal extraction layer and an external extraction layer to enhance outcoupling of light from OLED array116. Nanoparticles126in waveguide layer112facilitate diffusion of light128in a selected visible spectrum. When LED array102emits blue light and OLED array116emits amber or yellow light, hybrid device130emits tunable white light.

LED power efficiency be increased by selecting an efficient LED light source, reducing or minimizing the air gap between LEDs104and waveguide layer112, reducing or minimizing trapping of light inside substrate114, reducing or minimizing light scattering from substrate114(e.g., by including an internal extraction layer), matching optical indices between layers of hybrid devices100,130in direct contact (e.g., waveguide layer112and diffuser film124), or any combination thereof. Matching of optical indices can be achieved by providing an optical index matching glue or adhesive between layers in direct contact. Suitable optical index matching adhesives include polysilanes or other appropriate transparent viscous polymers having a refractive index between about 1.4 and about 1.7. Examples of suitable optical index matching adhesives include Optical Couplant (Matching Gel) (available from SYOPTEK INTERNATIONAL LIMITED), optical gel from Norland and Index Matching Gel (available from Corning Incorporated).

FIG.2depicts LED diffuser structure200including edge-lit LED array102in optical housing106of hybrid devices100,130, and optically coupled to waveguide layer112. As depicted inFIGS.1A and1B, LED array102is optically coupled to waveguide layer112. Reflective film202may be in direct contact with a first surface of waveguide layer112. The reflectivity of reflective film202may be selected to achieve a desired amount of internal reflection of light from the LED and also allow maximum transmittance of amber OLED emission, such that light from LED array102is inhibited from traveling toward the OLED array. Diffuser film124may be in direct contact with waveguide layer112. Hybrid devices100,130may include one or more of prism film204, lenz film206, and prism protective film208on diffuser film. Prism film204is typically a polymeric film (e.g., polyester) having fine prism structures that condense light from a light source. Prism protective film208is typically a transparent thin film which can protect prism film204from physical damage. In one example, prism film204is between and in direct contact with diffuser film124and lenz film206is in direct contact with prism film204and prism protective film208. Prism protective film208may form an outer layer of hybrid device100,130.

FIG.3depicts OLED structure300including OLED118of hybrid devices100,130. OLED118includes reflective electrode (metal cathode)120, light transmissive electrode (anode)122. Reflective electrode120typically includes Al, Ag, Au, or an alloy thereof. A typical thickness of reflective electrode120is between about 20 nm and about 300 nm. Light transmissive electrode122typically includes indium tin oxide (ITO), zinc tin oxide (ZTO), tin oxide (SnOx), indium oxide (InOx), molybdenum oxide (MoOx), carbon nanotubes, or a combination thereof. A typical thickness of light transmissive electrode122is between about 10 nm and about 100 nm. Between reflective electrode120and light transmissive electrode122, OLED118has electroluminescent layer302that typically includes electron injecting layer304, electron transporting layer306, hole blocking layer308, emissive layer310, electron blocking layer312, hole transporting layer314, and hole injecting layer316between reflective electrode120and light transmissive electrode122. Emissive layer318is a yellow or amber organic emissive layer, and can include a phosphorescent excimer with the emission wavelength covering the range of about 480 nm to about 700 nm, or green-emitting and red-emitting phosphorescent emitters with overall emission wavelength covering the range of about 480 nm to about 700 nm. Electroluminescent layer300can include a host material selected from aryl amines and aryl-substituted carbazole compounds, aryl substituted oxadiazoles, aryl-substituted triazoles, aryl substituted phenanthrolines and metal quinoxolates, and at least one phosphorescent emitter material dispersed in the host material and selected from phosphorescent dyes including derivatives of cyclometalated metal complexes. Planarizing layer318may be in direct contact with light transmissive electrode122. Planarizing layer318is typically a transparent film made of organic or inorganic materials and serves to reduce surface roughness of internal extraction layer320. Internal extraction layer320may be in direct contact with planarizing layer318. Internal extraction layer320is typically a thin film that includes an optical medium and nanoparticles that can scatter incident light in all angles. Overall, the surface roughness of planarizing layer318and internal extraction layer320is typically less than about 10 nm or less than about 5 nm. Substrate322may be between and in direct contact with internal extraction layer320and external extraction layer324. External extraction layer324is an external polymeric film attached to the surface of substrate322which facilitates extraction of photons trapped inside substrate322.

OLED118includes a microcavity having a selected cavity length defined over substrate322. The selected cavity length of OLED118is tuned to provide a resonance condition for emission of yellow or amber light through light transmissive electrode122. The light extraction efficiency of OLED118can be tuned by adjusting the spacing between reflective electrode120and light transmissive electrode122, and the selected cavity length can modified by adjusting a thickness of light transmissive electrode122, a thickness of electroluminescent layer302, or both.

FIG.4illustrates cool and warm white emission spectra generated by hybrid LED-OLED devices, such as those depicted inFIGS.1A and1B. Cool emission spectrum400can be obtained with high LED driving currents. Warm emission spectrum402can be obtained with low LED driving currents.

Examples of phosphorescent excimers with yellow and amber emission (e.g., having a wavelength in a range of or covering the range of about 480 nm to about 700 nm) suitable for emissive layer308include complexes represented by General Formula I.

In General Formula I:

Examples of complexes represented by General Formula 1 are shown below.

Suitable square planar tetradentate platinum and palladium complexes also include complexes represented by General Formulas II-IX.

Examples of complexes of Formula II-IX are shown below.

In defining various terms, “R1”, “R2”, “R3”, “R4”, etc. are used herein as generic symbols to represent various specific substituents. These symbols can be any substituent, not limited to those disclosed herein, and when they are defined to be certain substituents in one instance, they can, in another instance, be defined as some other substituents.

The term “C1-C4alkyl” as used herein is a branched or unbranched saturated hydrocarbon group of 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, and t-butyl. The alkyl group can also be substituted or unsubstituted. For example, the alkyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, amino, ether, halide, hydroxy, nitro, or thiol.

The terms “alkoxy” and “alkoxyl” as used herein to refer to an alkyl or cycloalkyl group bonded through an ether linkage; that is, an “alkoxy” group can be defined as —OA1where A1is alkyl or cycloalkyl.

The term “aryl” as used herein is a group that contains any carbon-based aromatic group including, but not limited to, benzene, naphthalene, phenyl, biphenyl, phenoxybenzene, and the like. The term “aryl” also includes “heteroaryl,” which is defined as a group that contains an aromatic group that has at least one heteroatom incorporated within the ring of the aromatic group. Examples of heteroatoms include, but are not limited to, nitrogen, oxygen, sulfur, and phosphorus. Likewise, the term “non-heteroaryl,” which is also included in the term “aryl,” defines a group that contains an aromatic group that does not contain a heteroatom. The aryl group can be substituted or unsubstituted. The aryl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol as described herein.

The term “halide” as used herein includes fluoride, chloride, bromide, and iodide.

The term “azide” as used herein is represented by the formula —N3.

The term “cyanide” as used herein is represented by the formula —CN.

which is understood to be equivalent to a formula:

wherein n is typically an integer. That is, R is understood to represent up to five independent non-hydrogen substituents, Rn(a), Rn(b), Rn(c), Rn(d), Rn(e). By “independent substituents,” it is meant that each R substituent can be independently defined. For example, if in one instance Rn(a)is halogen, then Rn(b)is not necessarily halogen in that instance.

EXAMPLES

A small area OLED (OLED A) having the following structure was prepared: ITO (100 nm)/HATCN (10 nm)/NPD (70 nm)/Tris-PCZ (10 nm)/Pd3O8-P (20 nm)/BAlq (10 nm)/BPyTP (50 nm)/Liq (2 nm)/Al (100 nm), where ITO is indium tin oxide, HATCN is 1,4,5,8,9,12-hexaazatriphenylene-hexacarbonitrile, NPD is N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine, Tris-PCz is 9,9′,9″-triphenyl-9H,9′H,9″H-3,3′:6′,3″-tercarbazole, Pd3O8-P is one of selected palladium-based phosphorescent emitters with a full chemical name of palladium (II) 7-(3-(pyridin-2-yl-κN)phenoxy-κC)(benzo[4,5]imidazo-κN)([1,2-f]phenanthridine-κC), BAlq is bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum, and BPyTP is 2,7-bis(2,2′-bipyridine-5-yl)triphenylene 2,7-di(2,2′-bipyridin-5 yl) triphenylene, Liq is 8-quinolinolato lithium, and Al is aluminum. The device active area was 2 mm×2 mm. The thickness of the charge transport layers (hole-transporting layer, electron-transporting layer, or both) was selected to enhance emission at wavelengths between 570 nm and 610 nm.

FIG.5Ashows current density versus voltage for OLED A.FIG.5Bshows EL spectra of OLED A before and after lifetime testing. The initial EL spectrum and the EL spectrum after the EL intensity dropped to 95% of the initial value at the constant driving current of 20 mA/cm2(about 180 hours) are substantially the same, confirming that there is no notable change in the emission color before and after lifetime testing, thus demonstrating excellent color stability.FIG.5Cshows external quantum efficiency (EQE) versus luminance for OLED A. The lower plot (open circles) shows EQE versus luminance for OLED A with air between OLED A and the detector (no outcoupling). OLED A has a peak EQE of 34.8% and a brightness of 16,650 cd m−2at 20 mA cm−2, and a remarkably high EQE of close to 30% at the brightness of 10000 cd m−2. The upper plot (solid stars) shows EQE versus luminance for OLED A with the insertion of optical index matching glue between the substrate of OLED A and the detector.FIG.5Dshows power efficiency (PE) versus luminance for OLED A. The lower plot (open circles) shows that the low voltage characteristic of the undoped Pd3O8-P emissive layer results in a power efficiency (PE) of 101 Lm W−1at 1,000 cd/m−2and a PE of 67 Lm W−1at 10,000 cd m−2with air between OLED A and the detector. The upper plot (solid stars) demonstrates the potential to further improve the PE with external extraction layers by matching optical indices between the substrate of OLED A and the detector, with the ideal external extraction layer achieving a PE of 188 Lm W−1at 1,000 cd m−2and 142 Lm W−1at 10,000 cd m−2. The EQE, low roll-off, and high PE of this amber OLED demonstrates the capability of satisfying strict high brightness performance needs of the lighting industry.

A large area OLED (OLED B) having the following structure was prepared: ITO (100 nm)/HATCN (10 nm)/NPD (70 nm)/Tris-PCZ (10 nm)/Pd3O8-P (20 nm)/BAlq (10 nm)/BPyTP (50 nm)/Liq (2 nm)/Al (100 nm), where the device active area is 20×50 mm. The lower plot (solid squares) inFIG.6Ashows EQE versus current density for OLED B. The upper plot (open squares) inFIG.6Ashows EQE versus current density for OLED B having an external extraction layer. The lower plot is reproduced inFIG.6B. The upper plot (solid triangles) inFIG.6Bshows EQE versus current density for OLED B optically coupled to a waveguide layer. The lower plot (open triangles) inFIG.6Bshows EQE versus current density for OLED B optically coupled to a waveguide layer and having a diffuser film. Data inFIGS.6A and6Bcorrespond to the presence of an air gap between OLED B and the detector. The lower plot (solid squares) inFIG.6Ais reproduced inFIG.6C. The middle plot (solid circles) inFIG.6Cshows EQE versus current density for OLED B optically coupled to a waveguide layer with the insertion of optical index matching glue between the substrate of OLED B and the waveguide layer. The upper plot (open circles) inFIG.6Cshows EQE versus current density for OLED B optically coupled to a waveguide layer and having a diffuser film with optical index matching glue between the substrate of OLED B and the waveguide layer and between the waveguide layer and the diffuser.

The device efficiency of OLED B (FIG.6A) is somewhat less than that of OLED A (FIG.5C), due at least in part to a difference in charge balance inside of the OLEDs, and may be related to the high resistance of ITO layer used in the large area OLED B. As shown inFIG.6A, device EQE can be improved with the increase of conductivity of anode layer by adding sub nano-grid Ag layer between the ITO and the substrate. An external extraction layer can enhance device EQE by at least about 50%. The device EQE decreased when the waveguide layer or a combination of waveguide layer and diffuser film were simply coupled to the opposite side of the substrate, believed to be due to air gaps between the substrate and the waveguide layer and between the waveguide layer and the diffuser film. However, the insertion of an optical index matching adhesive (e.g., polysilanes or other appropriate transparent viscous polymers) with a refractive index between about 1.4 and about 1.7 typically eliminates such air gaps and enhances the device efficiency, as shown inFIG.6C. Comparison ofFIGS.6A and6Creveals that the combination of index-matched waveguide layer and diffuser film can work as effectively as a commercial EEL layer.

A medium area OLED (OLED C) having the following structure was prepared: ITO (100 nm)/HATCN (10 nm)/NPD (70 nm)/Tris-PCZ (10 nm)/Pd3O8-P (20 nm)/BAlq (10 nm)/BPyTP (50 nm)/Liq (2 nm)/Al (100 nm), where the device active area is 10×20 mm. The lower plot (solid squares) inFIG.7Ashows EQE versus current density for OLED C having an internal extraction layer. The upper plot (open squares) inFIG.7Ashows EQE versus current density for OLED C having an internal extraction layer and an external extraction layer. The lower plot (solid squares) is reproduced inFIG.7B. The middle plot (solid triangles) inFIG.7Bshows EQE versus current density for OLED C having an internal extraction layer and optically coupled to a waveguide layer. The lower plot (open triangles) inFIG.7Bshows EQE versus current density for OLED C having an internal extraction layer and optically coupled to a waveguide layer and having a diffuser film. Data inFIGS.7A and7Bcorrespond to the presence of an air gap between the substrate of OLED C and the detector. The lower plot (solid squares) inFIG.7Ais reproduced inFIG.7C. The lower plot (solid circles) inFIG.7Cshows EQE versus current density for OLED C optically coupled to a waveguide layer with matching optical glue between the substrate of OLED C and the waveguide layer. The upper plot (open circles) inFIG.7Cshows EQE versus current density for OLED C optically coupled to a waveguide layer and having a diffuser film, with matching optical glue between the substrate of OLED C and the waveguide layer and between the waveguide layer and the diffuser film.

As shown inFIG.7A, the presence of an internal extraction layer and an external extraction layer enhances device EQE of OLED C by about 10-15% compared to OLED C having only an internal extraction layer. Comparison ofFIGS.7A and7Bshows that device EQE decreased when the waveguide layer or a combination of waveguide layer and diffuser film were simply added coupled to opposite side of substrates, believed to be due to air gaps between the substrate and the waveguide layer and between the waveguide layer and the diffuser film. However, the insertion of an optical index matching adhesive (e.g., polysilanes or other appropriate transparent viscous polymers) with a refractive index between about 1.4 and about 1.7 typically eliminates such air gaps and enhances the device efficiency, as shown inFIG.7C. Comparison ofFIGS.7A and7Creveals that combination of index-matched waveguide layer and diffuser film can work almost as effectively as a commercial EEL layer.

FIGS.8A and8Bshow EL spectra for a white LED and a blue LED, respectively.FIG.8Cshows EL spectra for a white LED (open squares) and for hybrid LED/amber OLED devices. The OLED device (OLED D) was prepared with the following structure: ITO (100 nm)/HATCN (10 nm)/NPD (70 nm)/Tris-PCZ (10 nm)/Pd3O8-P (20 nm)/BAlq (10 nm)/BPyTP (50 nm)/Liq (2 nm)/Al (100 nm), where the device active area is 20×50 mm. The hybrid devices have a waveguide layer and a diffuser film, with optical matching glue between the substrate and the waveguide layer and between the waveguide layer and the diffuser film. The various OLED devices have a driving current density of 0.1 mA/cm2(solid circles), 0.2 mA/cm2(open triangles), 0.5 mA/cm2(solid diamonds), and 0.7 mA/cm2(solid squares). As shown inFIG.8C, the device EL spectra can be modified by individually controlling driving current of LED and amber OLED, which can be changed from cool white with exclusive LED emission (open squares) to warm white with dominant amber OLED emission (solid squares).

Particular embodiments of the subject matter have been described. Other embodiments, alterations, and permutations of the described embodiments are within the scope of the following claims as will be apparent to those skilled in the art. While operations are depicted in the drawings or claims in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed (some operations may be considered optional), to achieve desirable results.

Accordingly, the previously described example embodiments do not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure.