FIELD OF THE INVENTION

This disclosure relates to variable transmission windows which are used for architectural and transportation applications. VLTPs may be fabricated using electrochromic and other technologies. In this disclosure, the appearance of such windows is addressed when the buildings and vehicles are viewed from outside.

BACKGROUND

The light transmission properties of variable light transmission panels (VLTPs) change by application of an electrical stimulus. In this invention, the principles of novelty will be explained using electrochromic (EC) technology although these principals will also be valid for other types of VLTPs such as those using liquid crystalline materials and suspended particles. When electrically controlled VLTP devices are fabricated using transparent substrates, these devices upon application of an electric voltage change their optical state, i.e., color, opacity, and/or transparency (light transmission or reflection). A user (or a user defined control system) can select and switch from one transmission state to the other. VLTP devices are referred to as “smart glass” or “smart windows” as the optical characteristics of the windows with these elements adapt to the weather or user defined conditions. Used in buildings, these smart windows may provide shade, glare reduction, energy savings, privacy, partitions and so forth. There is a great interest in the use of EC devices containing VLTPs for at least one of the above reasons in building windows, and in windows for transportation including cars, buses, trains, boats/ships and airplanes.

Used in construction of windows for residential and commercial buildings and in transportation, these windows with EC VLTPs result in energy efficient building envelopes and increased comfort by regulating the solar energy penetration through the windows. These windows include windows located within the door including transoms and sidelights. These windows may be fixed or movable, where the latter includes double-hung and casement windows and sliding windows and sliding glass doors. Building glass exteriors are designed by considering several parameters which include aesthetics, environment, location, etc., while also providing proper indoor daylighting, glare control so as to consume less energy for lighting, heating, ventilation and air-conditioning (HVAC). While use and characteristics of VLTP have been extensively investigated, but much attention has not been paid to its external appearance. For windows with VLTP panels such as EC technology where a user (or a person inside the building) makes a selection of the light transmission properties of these windows, this action inadvertently changes the exterior appearance of the window, i.e., windows in different optical states lead to differences in appearance which results in a checkerboard effect when such a building is viewed during the day. In most situations this is undesirable.

SUMMARY OF THE INVENTION

In a first aspect, the present disclosure includes an electrochromic variable light transmission panel (VLTP). In some aspects, a VLTP of the present disclosure may include (a) two transmissive substrates arranged in a parallel configuration; (b) the first substrate having two sides wherein the second side is coated with a coating stack comprising of at least two layers, followed by a coating of a transparent conductor and further followed by an EC layer; and (c) an electrolyte layer disposed between the two substrates, wherein the electrolyte layer contacts the said EC layer. In some aspects, a VLTP of the present disclosure may show a color difference ΔET* of greater than 40 in transmitted color when measured in the bleached and the colored optical states, and in these optical states show a color difference ΔER* of less than 6 when reflection is viewed from a side of the VLTP. In some aspects, the side of the VLTP is a side that faces the outside of a building.

In one aspect, the present disclosure includes an insulated glass unit (IGU) assembly comprising the VLTP of the present disclosure. In some aspects, the IGU assembly contains at least one low-e coated panel in addition to the VLTP; and the IGU show a color difference ΔET* of greater than 40 in transmitted color when compared in the bleached and the colored optical states of the VLTP, and these optical states show a color difference ΔER* of less than 8 when reflection is viewed from the first side of the VLTP.

In one aspect, the present disclosure includes a window including the VLTP, which further has a film bonded to the second substrate on the side that is not facing the electrochromic medium, and the said film having a low-e surface.

In one aspect, the present disclosure includes an electrochromic variable light transmission panel (VLTP) comprising a first transmissive substrate and a second transmissive substrate arranged in a parallel configuration, wherein the first transmissive substrate has a first side and a second side, wherein the second side is coated with a stack of coatings comprising at least two layers, followed by a coating of a transparent conductor, wherein the second transmissive substrate has a first side and a second side, wherein the first side of the second transmissive substrate is coated with a transparent conductor, wherein the substrates are disposed in an assembly such that an electrochromic medium is disposed between the conductive sides of the two substrates. In one aspect, the VLTP shows a color difference ΔET* of greater than 40 in transmitted color when measured in the bleached and the colored optical states, and shows a color difference of ΔER* of less than 6 when reflection is viewed from the first side of the first substrate.

In one aspect, the present disclosure includes an insulated glass unit (IGU) assembly having a VLTP, wherein the said IGU assembly comprises at least one low-e coated panel in addition to the said VLTP; and the said IGU assembly shows a color difference ΔET* of greater than 40 in transmitted color when compared in the bleached state and the colored optical states of the VLTP, and in these optical states of the VLTP, the IGU assembly shows a color difference in reflected color ΔER* of less than 8 when reflection is viewed from the first side of the VLTP.

In one aspect, the present disclosure includes an electrochromic variable light transmission panel (VLTP) comprising a first transmissive substrate and a second transmissive substrate arranged in a parallel configuration; wherein the first substrate comprises a first side and a second side, wherein the second side is coated with a stack of coatings comprising at least two layers, followed by a coating of a transparent conductor; wherein the second substrate comprises a first side and a second side, wherein the first side of the second substrate is coated with a transparent conductor; wherein the substrates are configured in an assembly such that an electrochromic medium is disposed between conductive sides of the first and second substrates; wherein the said VLTP shows a transmission ratio of greater than 2.5 at 550 nm when measured in the bleached and the colored states, and, in these optical states, shows ΔER* of less than 6 when reflection is viewed from the first side of the first substrate.

In one aspect, the present disclosure includes an insulated glass unit (IGU) assembly comprising at least one low-e coated panel and a VLTP separated by a gap, wherein the VLTP comprises: a first transmissive substrate and a second transmissive substrate arranged in a parallel configuration; wherein the first substrate comprises a first side and a second side, wherein the second side is coated with a coating stack comprising at least two layers, followed by a coating of a transparent conductor and further followed by a EC layer; and an electrolyte layer disposed between the first and second substrates, wherein the electrolyte layer contacts the said EC layer; wherein the said IGU assembly shows a color difference ΔET* of greater than 40 in transmitted color when compared in the bleached and the colored optical states of the VLTP, and in these optical states, shows a color difference ΔER* of less than 8 when reflection is viewed from the first side of the first substrate.

In one aspect, the present disclosure includes an insulated glass unit (IGU) assembly comprising at least one low-e coated panel and a VLTP separated by a gap, wherein the VLTP comprises: a first transmissive substrate and a second transmissive substrate arranged in a parallel configuration; wherein the first transmissive substrate comprises a first side and a second side, wherein the second side is coated with a stack of coatings comprising at least two layers, followed by a coating of a transparent conductor; wherein the second transmissive substrate comprises a first side and a second side, wherein the first side is coated with a transparent conductor; wherein the first and second substrates are configured in an assembly such that an electrochromic medium is disposed between conductive sides of the first and second substrates; and the said IGU assembly shows a color difference ΔET* of greater than 40 in transmitted color when compared in the bleached and the colored optical states of the VLTP, and, in these optical states, shows a color difference ΔER* of less than 8 when reflection is viewed from the first side of the first substrate.

Other features and characteristics of the subject matter of this disclosure, as well as the methods of operation, functions of related elements of structure and the combination of parts, and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims, all of which form a part of this specification.

