Electrophotochromic smart windows and methods

• US 6,297,900 B1
• Filed: 01/21/2000
• Issued: 10/02/2001
• Est. Priority Date: 07/22/1997
• Status: Expired due to Term

• Current Assignee: Dyesol Ltd.
• Original Assignee: Ultrapay Ltd.
• Inventors: Skryabin, Igor Lvovich, Tulloch, Gavin Edmund
• Primary Examiner(s): Dang, Hung Xuan
• Application Number:
  US09/463,424
• Time in Patent Office: 620 Days
• Field of Search: 359/257, 359/258, 359/259, 359/260, 359/261, 359/262, 359/263, 359/264, 359/265, 359/266, 359/252, 359/253, 359/254, 359/245, 359/267, 359/275, 359/274, 359/273, 359/272, 359/271
• US Class Current: 359/275
• CPC Class Codes: E06B 2009/2464 featuring transparency control by applying voltage, e.g. LCD, electrochromic panels
• CPC Class Codes: E06B 9/24 Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blindsoperating, guiding or securing devices or arrangements for roll-type closures E06B9/56; free-hanging flexible screens A47H23/00
• CPC Class Codes: G02F 1/163 Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor

Abstract

A smart window comprising a regenerative photolectrochomic (RPEC) photovoltaic element (108) juxtaposed with an electrochromic (EC) element (110). Microprocessor-based control mechanism (200) connecting the RPEC element to the EC element for controlling the current delivered to and from the EC element. The controller (200) including look-up tables (204 and 206) for determining the safe current to or from the EC element having regard to the amount of charge to be delivered or removed and the charge status of the EC element, the determination of charge status, charge still required and current to be delivered being made frequently to ensure that the current is kept within safe limits while minimizing switching times. New smart windows are also disclosed.

Claims

1. A smart window wherein:

a transparent regenerative photoelectrochemical (PE) element extends over substantially the whole area of the window,

a normally transparent electrochromic (EC) element also extends over substantially the whole area of the window,

control means are provided for interconnecting said PE and EC elements and for regulating the flow of current therebetween to effect the darkening or bleaching of the EC element when light falls on the PE element,

said control means is operable to connect the PE element to the EC element with one polarity to effect the darkening of the EC element and to connect the PE element to the EC element with the reverse polarity to effect the bleaching of the EC element.

2. A smart window according to claim 1 wherein:

said PE element comprises a plurality of separate PE cells arranged side-by-side to extend across the window,

at least two of said cells are adapted to be connected in series,

electrical leads are arranged to provide external connections to said cells whereby two different voltages are available therefrom when the cells are illuminated, and

said control means is adapted to apply one of said voltages to the EC element to effect darkening thereof and the other of said voltages to the EC element to effect the bleaching thereof.

3. A smart window according to claim 1:

three transparent panes arranged in close-spaced parallel relationship to one another, the panes comprising;

a center pane having first and second faces,

a first outer pane having an inner and an outer face, the first outer pane being arranged so that said inner face and said first face are juxtaposed,

and a second outer pane having an inner and an outer face, the second outer pane being arranged so that said inner face of the second pane and

said second face are juxtaposed,

said PE element formed between said first outer pane and said center pane, and

said EC element formed between said second outer pane and said center pane.

4. A smart window according to claim 3 wherein:

said first and second faces of the center pane have transparent conducting coatings formed thereon,

said inner faces of the first and second outer panes have transparent conducting coatings formed thereon,

said PE element comprises a plurality of elongate PE cells arranged in side-by-side array and extending substantially across said the window,

each of said PE cells comprises an inner elongate electrode formed on the transparent conducting coating of the first face of the center pane, a outer elongate electrode formed on the inner transparent coating of the first outer pane and arranged opposite said inner electrode, and a liquid electrolyte contained between said electrodes,

the electrolyte of one of said cells is prevented from mixing laterally with the electrolyte of an adjacent cell by a longitudinally-extending wall of conducting polymer,

said wall is arranged to electrically connect the inner electrode of one cell to the outer electrode of an adjacent cell so that said one and said adjacent cells are electrically arranged in series.

5. A smart window according to claim 1 wherein said control means comprises:

a microprocessor-based controller adapted to compute the charge status of the window and adapted to control current flow to and from the window,

read only memory means storing look-up tables relating maximum safe current for the window with respect to the charge status of the window such that an input indicative of the present charge status of the window will generate an output from the memory means indicative of the current to be applied to the window to achieve a desired target charge status.

6. A smart window according to claim 5 wherein said control means is incorporated within the window together with a battery that is arranged to be charged by the PE element and, when desired, to be connected to effect the charging or discharging of the EC element.

7. A smart window wherein:

a transparent regenerative photoelectrochemical (PE) element extends over substantially the whole area of the window,

a normally transparent electrochromic (EC) element also extends over substantially the whole area of the window,

said EC element comprises a plurality of series-connected PE cells arranged in substantially coplanar side-by-side juxtaposition, and electrical leads are arranged to form externally accessible electrical connections to more than one of said cells so that, when the window is exposed to light, at least one higher and one lower voltage will be present on said leads, said higher voltage being suitable for charging said EC cell and said lower voltage being suitable, with appropriate polarity, for discharging said EC cell.

8. A smart window wherein:

a first transparent pane and a second transparent pane are arranged in close-spaced parallel relationship to one another,

said first pane has an inner and an outer face, a transparent conductive coating being formed on the inner face of the first pane,

said second pane has an inner and an outer face, a transparent conductive coating, being formed on the inner face of the second pane,

the panes are arranged so that their inner faces are juxtaposed opposite one another but spaced from one another,

layers comprising the working electrode and electrolyte and the counter electrode of a transparent regenerative photoelectrochemical (RPEC) cell formed on the transparent coating of the first pane,

layers comprising the working electrode, electrolyte and the counter electrode of a transparent electrochromic (EC) cell formed on the transparent conductive coating of the second pane,

a central transparent conductive layer connecting and extending between the innermost electrode layers of the RPEC and EC cells over substantially their entirety,

and electrical leads providing separate external electrical access to said transparent conductive coating on the inner face of the first pane, said transparent conductive coating on the inner face of the second pane and to said central conductive layer.

9. A smart window according to claim 8 wherein:

the working electrode and the counter electrode of the RPEC cell are separated by a polymer layer which is capable of conducting the charge carriers of the cell but is an electronic insulator, and

said central transparent conductive layer is formed from a deformable or castable polymer.