POLYMER DISPERSED LIQUID CRYSTAL GLASS CONSTRUCTION

Abstract

Disclosed is a polymer dispersed liquid crystal (PDLC) glass construction which is suitable for use in automotive applications, and a method for forming a PDLC glass construction suitable for use in automotive applications. Exemplary embodiments of a PDLC glass construction include at least one darkened layer on a top side of a PDLC film, and at least one darkened layer on a bottom side of the PDLC film, for reducing visibility of an opaque PDLC material through the PDLC glass construction while reducing the transmission of visible light and/or energy through the PDLC glass construction. Exemplary embodiments of a PDLC glass construction may include additional interlayers such as polymer films, infrared reflecting (IR) coatings/layers, paint(s), low-emissivity (low-E) coatings, ultraviolet (UV) blocking materials, and/or anti-condensation layers.

Claims

1. A glass construction, comprising: a first glass substrate layer; a second glass substrate layer; a polymer dispersed liquid crystal (PDLC) film layer between the first glass substrate layer and the second glass substrate layer, the PDLC film layer comprising a PDLC material layer, a first polymer film layer between the first glass substrate layer and the PDLC material layer, and a second polymer film layer between the second glass substrate layer and the PDLC material layer; a first intermediate film layer between the first glass substrate layer and the PDLC film layer; and a second intermediate film layer between the second glass substrate layer and the PDLC film layer; wherein at least one of the first glass substrate layer, the first intermediate film layer and the first polymer film layer is a darkened layer having a darkness for reducing the transmission of at least one of visible light and energy, and, at least one of second glass substrate layer, the second intermediate film layer and the second polymer film layer is a darkened layer having a darkness for reducing the transmission of at least one of visible light and energy.

2. The glass construction according to claim 1, wherein the first and the second polymer film layers are the darkened layers.

3. The glass construction according to claim 1, wherein a total light transmission (LTa) through the glass construction, as measured according to United Nations Economic Commission for Europe Regulation No. 43 (ECE-R43) is approximately 20% or less of the total visible solar light that arrives at an outside surface of the first glass substrate layer in daylight, when the PDLC film layer is in an ON state.

4. The glass construction according to claim 1, wherein a total energy transmission (TTS) through the glass construction as measured according to International Organization for Standardization Standard ISO 13837:2008 (ISO 13837:2008) is approximately 25% or less of the total solar energy that arrives at an outside surface of the first glass substrate layer in daylight when the PDLC film layer is in an ON state.

5. The glass construction according to claim 1, wherein a total light transmission (LTa) through the glass window as measured according to United Nations Economic Commission for Europe Regulation No. 43 (ECE-R43) is approximately 20% or less of the total visible solar light that arrives at an outside surface of the first glass substrate layer in daylight when the PDLC film layer is in an ON state, and a total energy transmission (TTS) through the glass window as measured according to International Organization for Standardization Standard ISO 13837:2008 (ISO 13837:2008) is approximately 25% or less of the total solar energy that arrives at the outside surface of the first glass substrate layer in daylight when the PDLC film layer is in the ON state.

6. The glass construction according to claim 1, wherein the darkened layers have a dark gray hue.

7. The glass construction according to claim 1, wherein the first and the second intermediate film layers are made of polyvinyl butyral (PVB).

8. The glass construction according to claim 7, wherein at least one of the first and the second intermediate film layers is a privacy PVB film layer which reflects and/or absorbs infrared (IR) or ultraviolet (UV) light.

9. The glass construction according to claim 1, wherein the glass construction is an automotive laminated glass window.

10. An automotive glass window comprising: a first glass substrate layer; a second glass substrate layer; a polymer dispersed liquid crystal (PDLC) film layer comprising a PDLC material layer, a first polymer film layer between the first glass substrate layer and the PDLC material layer, and a second polymer film layer between the second glass substrate layer and the PDLC material layer, the PDLC film layer being disposed between the first glass substrate layer and the second glass substrate layer, a first intermediate film layer between the first glass substrate layer and the PDLC film layer; and a second intermediate film layer between the second glass substrate layer and the PDLC film layer; wherein at least one of the first glass substrate layer, the first intermediate film layer and the first polymer film layer is a darkened layer having a darkness for reducing the transmission of at least one of visible light and energy, and, at least one of second glass substrate layer, the second intermediate film layer and the second polymer film layer is a darkened layer having a darkness for reducing the transmission of at least one of visible light and energy.

11. The automotive glass window according to claim 10, the first and the second polymer film layers are the darkened layers.

12. The automotive glass window according to claim 10, wherein a total light transmission (LTa) through the glass construction as measured according to United Nations Economic Commission for Europe Regulation No. 43 (ECE-R43) is approximately 20% or less of the total visible solar light that arrives at an outside surface of the first glass substrate layer in daylight, when the PDLC film layer is in an ON state.

13. The automotive glass window according to claim 10, wherein a total energy transmission (TTS) through the glass construction as measured according to International Organization for Standardization Standard ISO 13837:2008 (ISO 13837:2008) is approximately 25% or less of the total solar energy that arrives at an outside surface of the first glass substrate layer in daylight when the PDLC film layer is in an ON state.

14. The automotive glass window according to claim 10, wherein a total light transmission (LTa) through the glass window as measured according to United Nations Economic Commission for Europe Regulation No. 43 (ECE-R43) is approximately 20% or less of the total visible solar light that arrives at an outside surface of the first glass substrate layer in daylight when the PDLC film layer is in an ON state, and a total energy transmission (TTS) through the glass window as measured according to International Organization for Standardization Standard ISO 13837:2008 (ISO 13837:2008) is approximately 25% or less of the total solar energy that arrives at the outside surface of the first glass substrate layer in daylight when the PDLC film layer is in the ON state.

15. The automotive glass window according to claim 10, wherein the darkened layers have a dark gray hue.

16. The automotive glass window according to claim 10, wherein the first and the second intermediate film layers are made of polyvinyl butyral (PVB).

17. The automotive glass window according to claim 10, wherein at least one of the first and the second intermediate film layers is a privacy PVB film layer which reflects and/or absorbs infrared (IR) or ultraviolet (UV) light.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0031] The features and advantages of the exemplary embodiments may be better and more completely understood with reference to the attached drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0032] FIG. 1 shows an exemplary embodiment of a PDLC glass construction;

[0033] FIG. 2 shows an exemplary embodiment of a PDLC film for a PDLC glass construction;

[0034] FIG. 3 shows an exemplary busbar arrangement for a PDLC glass construction; and,

[0035] FIG. 4 shows an exemplary embodiment of a PDLC glass construction as in FIG. 1, further incorporating a low-emissivity (low-E) layer.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0036] FIG. 1 shows an exemplary embodiment of a PDLC glass construction 101 according to this disclosure. A first and a second glass substrate may be a clear glass, a pale green glass, or dark green glass of soda-lime silicate glass, preferably manufactured by a float process. The first glass substrate layer 102, which can be an outside of a glass window, can comprise a coating layer 103 such as an infrared (IR) reflective coating, IR absorbing coating, or UV-cutting coating on a side of an inner surface 121. The second glass substrate layer 109, which can be a room side (inside) of a glass window, can also comprise such a coating layer. In a case that the first glass substrate layer 102 is placed at the outside of the glass window, the coating layer 103 may be an IR reflective coating or IR absorbing coating, because such coatings can help resist direct sunlight, debris, contaminants, and other damaging influences to a PDLC film layer 106. The first and the second glass substrate may comprise other coating layer(s) reflecting and/or absorbing visible light and/or energy.

[0037] The IR reflective coating may be formed from known materials such as silver, gold, tin oxide, zinc, silicon oxide, silicon nitride, or other comparable materials and/or combinations thereof. In an exemplary embodiment, IR reflective coating is silver based. The IR reflective coating may be applied by known methods such as magnetron sputtered vacuum deposition (MSVD), flow coating, spray coating, or other comparable processes.

[0038] As the intermediate film layers (105, 108), polyvinyl butyral resin (PVB), ethylene vinyl acetate resin (EVA), or polyurethane resin (PU) can be used. In the exemplary embodiment shown by FIG. 1, the layer 105 is a privacy (dark) layer that provides a darkened layer on top of PDLC film layer 106 (detailed in FIG. 2). The layer 105 thus reduces visibility of an opaque PDLC material 201 (FIG. 2) when viewed through the top of the PDLC glass construction 101, i.e., down through surface 120. In addition, the layer 105 may reflect and/or absorb infrared (IR), ultraviolet (UV), or other forms of energy, e.g., that may cause failure of the PDLC switching function or permanent damage to the PDLC film layer 106 or PDLC material 201 (shown in FIG. 2). The other layer(s) may be a privacy (dark) layer(s).

[0039] As shown in FIG. 2, PDLC film layer 106 generally comprises PDLC material 201 sandwiched between a transparent conductive oxide (TCO) coating 203 on each of a first (top) and a second (bottom) polymer (polyethylene terephthalate (PET)) film layers 202, 204. As previously discussed, excess heat and/or radiation may cause, among other things, failure of the PDLC switching function or permanent damage to the PDLC film layer 106 or materials. The layer 105 with a privacy function reduces the amount of damaging heat and radiation that impinges the PDLC film layer 106, by reflecting and/or absorbing at least some of the heat and radiation. At least one of the first and the second polymer film layers 202, 204 may be a privacy (dark) layer(s).

[0040] A layer with a privacy function also decreases the overall amount of visible light and/or energy transmission through the PDLC glass construction 101, thereby decreasing the amount of visible light and/or energy that enters, for example, the passenger compartment of an automobile. This may obviate the need for a separate blind or shade to keep out or reduce unwanted visible light and/or radiation.

[0041] In an exemplary embodiment such as that shown in FIG. 1, the layer 105 with privacy function may be formed from PVB. The layer 105 with privacy function may also be formed from other suitable materials such as ethylene-vinyl acetate (EVA) or polyurethane (PU), or combinations thereof. Further, in the exemplary or other embodiments, the first glass substrate layer 102 or the first polymer film layer 202 may be a darkened layer(s) instead of, or in conjunction with a dark interlayer, for reducing visibility of an opaque PDLC material 201, protecting the PDLC film layer 106 from damaging effects from radiation and other energy, and/or reducing the amount of visible light and/or energy that passes, e.g., into the passenger compartment of an automobile.

[0042] Moreover, as previously discussed, other interlayers such as coated PET films, low-emissivity (low-E) layers, tinted layers, polarized layers, or other materials suitable for reducing visible light and/or energy transmission between a first glass substrate layer 102 and a PDLC film layer 106 may be used for the purposes disclosed above. The general selection and placement of materials in the PDLC glass construction 101 may vary based on the design and desired properties of particular glass constructions.

[0043] The exemplary embodiment of a PDLC glass construction 101 in FIG. 1 further addresses the shortcomings of current PDLC glass constructions by using a darkened substrate (darkened second glass substrate layer 109) on an inside (bottom) portion of the PDLC glass construction 101. In the exemplary embodiment of FIG. 1, the darkened material is darkened second glass substrate layer 109 that reduces visibility of an opaque PDLC material 201 when viewed through bottom surface 123 of PDLC glass construction 101. The darkened glass substrate layer 109 may further reflect and/or absorb unwanted visible light and/or energy that permeates through the upper layers of PDLC glass construction 101, and reduce the amount of visible light and/or energy that ultimately enters, e.g., the passenger compartment of an automobile. These properties are particularly useful for eliminating or reducing the need for a shade, blind, or other separate, physical component for accomplishing the same purposes.

[0044] In FIG. 1, darkened second glass substrate layer 109 is beneath a clear layer 108 which may be a typical layer in a PDLC glass construction for preventing the glass from rupturing during an impact. In the same or other embodiments, clear layer 108 may be substituted with a darkened layer such as a layer similar to layer 105. Clear layer 108 may formed of PVB, but may also be formed from other suitable materials such as EVA or PU, and these materials may also be darkened to achieve certain properties in particular designs of a PDLC glass construction.

[0045] Moreover, as previously discussed, other interlayers such as PET films, low-E layers, tinted layers, polarized layers, or other materials suitable for reducing visible light and/or energy transmission between a first glass substrate layer 102 and a second glass substrate layer 109 may be used for the purposes disclosed above. The disclosed and comparable materials may be selected and positioned in any way suitable for use according to this disclosure.

[0046] Depending on, among other things, the number, type, and arrangement of interlayers in the PDLC glass construction, the materials used, and the darkness of dark layers and/or substrates, various LTa levels and/or TTS levels through the glass construction may be achieved. For the exemplary embodiments disclosed herein, LTa is preferably about 20% or less of the total visible solar light that arrives at the outside surface 120 of the first glass substrate layer 102 in daylight when the PDLC material 201 is in the ON state, as measured according to United Nations Economic Commission for Europe Regulation No. 43 (ECE-R43) definitions (standard illuminant A) for automotive safety glazing. More preferably, LTa is approximately 9% or less of the total visible solar light that arrives at the outside surface 120 of the first glass substrate layer 102 in daylight when the PDLC material 201 is in the ON state. Even more preferably, LTa for the exemplary embodiments is approximately 5% or less of the total visible solar light that arrives at the outside surface 120 of the first glass substrate layer 102 in daylight when the PDLC material 201 is in the ON state.

[0047] TTS for the exemplary embodiments is preferably about 25% or less of the total solar energy that arrives at the outside surface 120 of first glass substrate layer 102 in daylight when the PDLC material 201 is in the ON state, as measured according to the International Organization for Standardization Standard ISO 13837:2008, Road vehiclesSafety glazing materialsMethod for the determination of solar transmittance (ISO 13837:2008). More preferably, TTS is approximately 18% or less of the total solar energy that arrives at the outside surface 120 of the first glass substrate layer 102 in daylight when the PDLC material 201 is in the ON state. Even more preferably, TTS for the exemplary embodiments is approximately 15% or less of the total solar energy that arrives at the outside surface 120 of the first glass substrate layer 102 in daylight when the PDLC material 201 is in the ON state.

[0048] Any exemplary or comparable embodiment of a PDLC glass construction as disclosed herein does not necessarily limit both LTa and TTS. Depending on preferences for a particular PDLC glass, either one or both of LTa and TTS may be limited. For example, in some applications light may be preferable but not heat. The number, type, and arrangement of interlayers, the materials used, and the darkness of dark layers, among other things, may be varied to achieve the optimal balance between visible light and energy transmission.

[0049] In general, the layers described herein are assembled according to known methods for manufacturing automotive safety glass products. For example, with respect to the embodiment described by FIG. 1, prefabricated and commercially available flat glass substrates are bent to desired dimensions, and PDLC films and other interlayers are stacked between the substrates in the exemplary configuration. The assembly is then processed according to known methods for forming final glass constructions.

[0050] In an exemplary method, a polymer sheet such as PVB is laid over a bent inner glass substrate, and a PDLC film is deposited on top of the clear layer. Another layer, which may be formed of PVB, may be laid over the PDLC film and covered by a bent outer glass substrate, The stack is then de-aired and laminated according to known industry processes. The laminated safety glass may then be autoclaved to soften the PVB material and wet-out the glass substratesi.e., contact all areas of the glass with the PVB, before the clear, laminated safety glass is cooled.

[0051] Exemplary materials of construction include, among other things, proprietary PDLC materials and films that are well-known and commercially available. In the exemplary embodiment, polymer film layers 202, 204 are formed from PET. In other embodiments, the polymer film layers may be formed from other polymers or comparable materials, or combinations thereof, consistent with this disclosure. TCO coatings 203 may be formed from, for example and without limitation, indium tin oxide (ITO), fluorine doped tin oxide (FTO), zinc oxide, or any combination of these or other transparent conducting oxides or materials consistent with this disclosure.

[0052] With continuing reference to the exemplary embodiment shown in FIG. 1, black paint 104 may be used alone or in conjunction with dark layers, e.g., layer 105, for reducing visibility of ends of PDLC film layer 106, ring 107 (discussed below), busbar 301 (FIG. 3, discussed below), and/or other features appearing through the outside surface 120 of first glass substrate layer 102. Black paint 104 may be applied, for example and without limitation, to surface 121 of outside first glass substrate layer 102, coating layer 103, and/or layer 105 according to known techniques such as silk screen printing and laser deposition.

[0053] Ring 107 compensates for the thickness of the PDLC film layer 106, which does not extend the full width of the exemplary PDLC glass construction 101. In an exemplary embodiment, PDLC film layer 106 and ring 107 are approximately 0.4 mm thick. In other embodiments, PDLC film layer 106 and ring 107 may be of other thicknesses consistent with particular designs for a PDLC glass construction. In one embodiment, ring 107 is formed from PVB, although other materials or combinations of materials, e.g., EVA, PU, may be used within the scope of this disclosure.

[0054] FIG. 1 further discloses black paint 110 on a periphery of surface 123 of second glass substrate layer 109 for reducing visibility of certain features, such as ends of PDLC film layer 106, ring 107, and busbar 301 (FIG. 3, discussed below), through surface 123 of second glass substrate layer 109. Black paint 110 may be applied in similar fashion as black paint 104, and may be applied in any location and by any method consistent with this disclosure.

[0055] With reference now to FIG. 3, an exemplary embodiment of PDLC film layer 106 includes one or more busbars 301 adjacent to PDLC material 201 for providing an applied electric field to PDLC material 201. Busbars 301 may comprise, for example and without limitation, copper tape attached to the TCO coatings 203 via known conductive glues or a lacquer such as a silver lacquer. In the exemplary embodiment two busbars 301 are respectively connected to the TCO coating 203 on each polymer (PET) film layer 202, 204. Each busbar 301 has a width such as to extend from the end of the PDLC material 201 to the end of respective polymer (PET) film layers 202, 204, which may be approximately 10 mm. As shown in FIG. 3, a gap should exist between PDLC film layer 106 and busbar 301, and busbar 301 should not extend beyond polymer (PET) film layer 202, 204. In other embodiments, one or more busbars 301 having different sizes may be formed in different orientations consistent with this disclosure.

[0056] An exemplary method for forming the disclosed configuration for a busbar 301 comprises cutting each polymer (PET) film layer 202, 204 to form areas for exposing busbar 301 to the opposite side polymer (PET) film layer 202 or 204 and respective TCO coating 203. Methods of cutting the polymer (PET) film layer 202, 204 may include laser cutting, die cutting, chemical etching, or any suitable means. The busbars 301 may then be applied to the exposed opposite surfaces of TCO coating(s) 203 using, for example and without limitation, conductive glue or lacquer. Other embodiments may include, for example, forming grooves in polymer (PET) film layers 202, 204 and/or layer 105 and/or clear layer 108, and bonding a busbar(s) 301 in the grooves and in contact with TCO coating(s) 203 using a conductive glue or lacquer.

[0057] The busbars 301 are connected to an AC voltage source (not shown) and may be further connected to a controlling switch (not shown). In exemplary embodiments, an applied voltage is between about 30V to 110V, although other voltages may be suitable depending on particular PDLC glass constructions. Exemplary embodiments require an alternating current (AC) to activate the switching function of the PDLC material 201.

[0058] With reference now to FIG. 4, another exemplary embodiment of a PDLC glass construction 400 is shown incorporating a low-E coating 401 between the second glass substrate layer 109 and black paint 110 of the PDLC glass construction 101 shown in FIG. 1. Low-E coating 401 may be used, among other things, to absorb energy (e.g., UV radiation) and act as an anti-condensation layer for preventing the occurrence of condensation on a surface 123 of the second glass substrate layer 109 while maintaining the transmission of visible light. Low-E coating 401 may also be used to prevent the cold-wall effect, wherein, for example, the temperature of a window drops while a vehicle sits idle and the temperature of an area next to the window correspondingly drops. The low-E coating 401 absorbs energy to prevent these phenomena.

[0059] Exemplary low-E coatings 401 are formed from, for example and without limitation, silver, or metal oxides and/or other dielectric materials. In an exemplary embodiment low-E coating 401 may be silver and is MSVD coated onto glass substrate surface 123. Other methods for depositing low-E coating 401 may include flow coating or other known techniques consistent with this disclosure.

[0060] Although certain example embodiments have been described in relation to various applications, the present disclosure is not limited thereto. The techniques of certain example embodiments may be applied to any glass and/or window-like application, for example and without limitation, automotive sunroofs and separation windows.

[0061] Also, the features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.

[0062] Further, the current disclosure covers various modifications and equivalent arrangements included within the spirit and scope of the appended claims.