Patent Application
20080028697
Referring to
Although this description describes using the window defroster assembly 12 as a rear window, the invention is equally applicable to other areas of the automobile 10. For example, the window defroster assembly 12 may be appropriately located and dimensioned to be used as a driver side window, a passenger side window, rear windows, a front windshield and/or any other windows the automobile 10 may have.
Referring to
The bus bars 20, 22 are respectively designated as positive and negative bus bars. The bus bars 20, 22 each are accordingly coupled in one or more places to leads 24, 26. Lead 24 is coupled to a positive terminal 30 of a voltage source 28, while lead 26 is coupled to a negative (ground) terminal 32 of the a voltage source 28, thereby establishing an electric circuit. The voltage source 28 may be the electrical system of the automobile 10. Such an electrical system is typically a 12 volt system. Upon the application of voltage to the heater grid 16, a current will flow through the grid lines 18 from the positive bus bar 20 to the negative bus bar 22 and, as a result, the grid lines 18 will heat up via resistive heating.
Referring to
Located above the first side 36 of the substrate 34 is a light control assembly 39. In this embodiment, the light control assembly 39 includes a light control layer 42, a first plastic film 40 and/or a second plastic film plastic film 41. In one embodiment, the light control assembly 42 is sandwiched between the first plastic film 40 and the second plastic film plastic film 42. Generally, the first and second plastic films 40, 41 are made of at least PC, PMMA polyester, TPU, and combinations thereof.
The light control layer 42 may be made of a photochromic, an electrochromic or a thermochromic device, or a solar control device. The photochromic material is a material that changes from being transparent to less transparent or even opaque when the photochromic material is exposed to light and reverts to transparency when the light is dimmed or blocked. The electrochromic layer may be multi-layer system, is at least one of liquid-crystal based, suspended particle device (SPD) based, inorganic, organic, or hybrid based materials.
The electrochromic device consists of a sandwich of materials. One embodiment of this sandwich but not limited to this, comprises two electrode layers sandwiching an ion storage layer, an ion conductor/electrolyte layer and an electrochromic material layer. The photochromic can be single or multi-layer, it is at least one of TPU, PC, PMMA, polyester or other transparent thermoplastic or thermosetting material/component further comprising photochromic dyes or pigments or additives. When a voltage is applied to the electrochromic device a small electric charge consisting of ions flows from the ion storage layer into the electrochromic material layer via the ion conductor/electrolyte layer thus causing a chemical reaction in the electrochromic material layer which results in a change from transparent to less transparent or even opaque. When the voltage direction is reversed the ions flow back to the ion storage layer so that the electrochromic device reverts to transparency.
The thermochromic device contains materials change reversibly color with changes in temperature, or allow for a visual response to changes in temperature. When the temperature is raised to a specified temperature the pigment goes from colorless or light color to colored or dark color. The pigment returns to the original color as it cools down. The thermochromic material can be made as semi-conductor compounds, from liquid crystals or using metal compounds, or organic pigments which are composed of micro capsules.
The solar control device may utilize solar absorbing pigment/additive or solar reflective coating/ink/pigment to control the amount of infrared light into the occupant compartment of the vehicle. A solar control layer suitable for incorporation in the present invention is described in U.S. application Ser. No. 11/450,732, which is herein incorporated by reference and is commonly owned.
Located between the light control assembly 39 and the first side 36 of the substrate 34 is the heater grid 16. The heater grid 16 may include all or a portion of the grid lines 18 and the bus bars 20, 22 as best shown in
The heater grid 16 may be formed from any conductive material including conductive pastes, inks, paints, coatings, wires/thin wires, or films known to those skilled in the art. If the conductive element is a paste, ink, or paint, it is preferred that they include conductive particles (and nano-particles), flakes, or powders dispersed in a polymeric matrix. This polymeric matrix is preferably an epoxy resin, a polyester resin, a polyvinyl acetate resin, a polyvinylchloride resin, a polyurethane resin or mixtures, blends, and copolymers of the like.
The conductive particles, flakes or powders may be of a metal including, but not limited to, silver, copper, zinc, aluminum, magnesium, nickel, tin, or mixtures and alloys of the like, as well as any metallic compound, such as a metallic dichalcongenide. These conductive particles, flakes, or powders may also be any conductive organic material known to those skilled in the art, such as polyaniline, amorphous carbon, carbon-graphite and carbon nanotubes. Although the particle size of any particles, flakes, or powders may vary, a diameter of less than about 40 μm is preferred with a diameter of less than about 1 μm being specifically preferred. Any solvents, which act as the carrier medium in the conductive pastes, inks, or paints, may be a mixture of any organic that provides solubility for the organic resin. Examples of metallic pastes, inks, or paints include silver-filled compositions commercially available from DuPont Electronic Materials, Research Triangle Park, N.C. (5000 Membrane Switch, 5029 Conductor Composition, 5021 Silver Conductor, and 5096 Silver Conductor), Acheson Colloids, Port Huron, Mich. (PF-007 and Electrodag SP-405), Methode Engineering, Chicago, Ill. (31-1A Silver Composition, 31-3A Silver Composition), Creative Materials Inc., Tyngsboro, Mass. (118-029 2k Silver), and Advanced Conductive Materials, Atascadero, Calif. (PTF-12).
An ink layer 44 may be disposed between the heater gird 16 and the first plastic film 40 and/or the light control layer 42. The ink layer 44 may be disposed such that to cover areas of the heater grid 16, such as the bus bars 20, 22 from view. Additionally, the ink layer 44 may be stylized in such a way to provide for manufacturers to differentiate their window defroster assembly 12 from competitors. As such, the ink layer 44 may be stylized in any one of a number of patterns.
Placed above the light control assembly 39 are an optional first weathering layer 46 and a first plasma layer 48 respectively. The first weathering layer 46 may be a material that includes the basic chemistry of acrylic, polyurethane, siloxane, or a combination of these materials to provide high weatherablity and long term ultraviolet. Further, the first weathering layer 46 may also include a material having lonomer or flouropolymer chemistry or similar material. Moreover, in another embodiment of the present invention silicon/nanoparticles may be blended into the material of the first weathering layer 46 or a silioxyane copolymer is formed into the weathering layer 46 by polymerization. The weathering layer 46 may be applied by one method selected from the group of flow coating, dip coating, spray coating, in-mold coating, curtain coating, and the like. If it's a weathering film, the weathering layer 46 is produced by extrusion, co-extrusion, lamination, extrusion-lamination, extrusion-coating, roller-coating, and the like. The weathering layer 46 may include ultraviolet absorbers.
The first plasma layer 48 is a “glass-like” coating deposited on the weathering layer 46 by plasma enhanced chemical vapor deposition (PECVD) process, expanding thermal plasma PECVD, plasma polymerization, photochemical vapor deposition, ion beam deposition, ion plating deposition, cathodic arc deposition, sputtering, evaporation, hollow-cathode activated deposition, magnetron activated deposition, activated reactive evaporation, thermal chemical vapor deposition, and a sol-gel coating process or the like. An optional second weathering layer 46′ and a second plasma layer 48′ may be deposited on the second side 38 of the substrate 34. The plasma layers 48, 48′ may be multiple layers and may contain an ultraviolet absorber.
The plasma layers 48, 48′ may be made of aluminum oxide, barium fluoride, boron nitride, hafnium oxide, lanthanum fluoride, magnesium oxide, scandium oxide, silicon monoxide, silicon dioxide, silicon nitride, silicon oxy-nitride, silicon oxy-carbide, hydrogenated silicon oxy-carbide, silicon carbide, tantalum oxide, titanium oxide, tin oxide, yttrium oxide, zinc oxide, zinc selenide, zinc sulphide, zirconium oxide, and zirconium titanate. Furthermore, the plasma layers 58, 60 may comprise multiple sub-layers differing in composition or structure.
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As shown in block 64, an ink layer and heater grid may be applied to the light control assembly. The stylized ink layer and the heater grid may be applied by screen printing, pad printing, membrane image transfer printing, transfer printing, ink jet printing, digital printing, robotic dispensing, or mask and spray. Optionally, as indicated by block 66, the light control assembly may be thermoformed. This thermoforming process may be done by vacuum thermoforming, pressure assisted thermoforming, drape forming or cold forming.
Thereafter, as shown in blocks 68 and 70, the light control assembly is then trimmed and positioned to fit in a mold cavity. Once in the mold cavity, as shown in block 72, the light control assembly is back molded with a substrate material. This may be accomplished by utilizing injection molding, compression molding, injection-compression molding, multi-component molding, multi-color molding or multi-material molding process. The same method may apply when incorporating a light emissive layer.
Afterwards, as indicated by blocks 74 and 76, the light control assembly and substrate material are hot melted, thereby forming the window panel, which is then removed from the mold cavity. As shown in block 78, an optional weathering layer may be applied to the window assembly. Thereafter, a plasma coating is applied to the window assembly via a PECVD process as shown in block 80.
The method 60 may also be executed when incorporating a light emissive layer. This act would include the steps of the forming a light emissive assembly, trimming the light emissive assembly, position the light emissive assembly in the mold cavity, back molding the light emissive assembly to the plastic substrate material, melt bonding the light emissive assembly to form the window assembly, removing the window assembly from the mold cavity, and applying a plasma coating on at least one side of the window assembly.
As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles of this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from spirit of this invention, as defined in the following claims.
