WO2016049759A1

WO2016049759A1 - Light blocking microshutter

Info

Publication number: WO2016049759A1
Application number: PCT/CA2015/050977
Authority: WO
Inventors: John MANCHEC; Mohamed BOUCHERIT
Original assignee: Aero-Shade Technologies Canada, Inc.
Priority date: 2014-09-29
Filing date: 2015-09-29
Publication date: 2016-04-07

Abstract

A switchable light-blocking micro-shutter array is provided. The array includes a transparent substrate having first and second sides; an electrode on said first side of the transparent substrate, said electrode being transparent; an insulator layered on the electrode; a plurality of micro-shutters, each micro-shutter comprising a fixed end and a mobile end, the fixed end being attached to the insulator and the mobile end being electrostatically actuable by the electrode between an open position in which the mobile end is curled away from the insulator to let light pass through, and a closed position in which the mobile end extends over the insulator to block light, the micro-shutters comprising gaps between adjacent ones of said micro-shutters while in the closed position; and opaque ribbons positioned to block light from passing through the gaps. Also provided is a method for fabricating the same.

Description

LIGHT BLOCKING MICROSHUTTER

RELATED PATENT APPLICATION

The present application claims priority from US provisional patent application no. US 62/056,835 filed on September 29, 2015. The contents of this application are incorporated herein by reference.

TECHNICAL FIELD

The technical field generally relates to light transmission control and more particularly to an improved switchable micro-shutter which can block light from passing through a transparent surface.

BACKGROUND

Electrically-switchable smart glass is often used to control the amount of light passing through a window. This technology assists in improving energy efficiency of structures, such as buildings and airplanes, by actively altering the light transmission properties of their windows according to varying conditions.

Electrically-switchable smart glass is often preferred over traditional blinds due to the fact that they take up less space, weigh less, are more reliable, are less costly to fabricate and are more visually appealing. There are several existing technologies which can be used to create switchable glass, including: suspended particle devices, electrochromic devices, polymer dispersed liquid crystal devices, nanocrystals and micro-shutters. Due to their rapid transition time, low fabrication cost, durability and maximum/minimum transmission properties, micro-shutters are often the preferred switchable glass technology.

Micro-shutters (also referred to as a light gate or light valve) are micro-electromechanical system (MEMS) devices which can be electrostatically actuated between an open state in which light can easily pass through an underlying substrate, and a closed state in which light is blocked from passing through the substrate. The technology is based on electrostatically controlled rolling electrodes, such as those disclosed in US Patents nos. 3,772,537 (CLIFFORD et al.) and 3,989,357 (KALT) in which a transparent insulating layer separates a fixed transparent electrode from an opaque resilient rolled electrode. The resilient electrode is fixed at one end and free at another end. When a voltage is applied across the electrodes, the free end of the resilient electrode unrolls over the insulating layer, effectively blocking light from passing through the underlying transparent layers. When no voltage is applied, the resilient electrode returns to its relaxed state in which it is curled, allowing light to pass through the transparent layers relatively unobstructed.

The micro-shutters are on the order of micrometers, and are thus virtually invisible to the naked eye when rolled. When unrolled, the opaque electrodes cover a large area of the substrate or window, effectively blocking most incoming light from passing through.

Disadvantageously, existing micro-shutter designs do not block enough light to be suitable for certain applications, such as aerospace or avionics for example, where a greater degree of light blockage is desirable. Existing technologies employing an array of micro-shutters are incapable of blocking 100% of incoming light, and in some cases can only block around 99% of light. This is due to side- effects during the fabrication process which cause gaps in the areas covered by the micro-shutters. For example, during the fabrication process, a strip of the opaque electrode must be removed from between each column of micro-shutters in order to release the opaque electrode from the underlying layer and become rolled. The removed strips of opaque electrode create gaps between each column of the micro-shutters which allow light to pass, even when the micro- shutters are in their closed state.

There is therefore a need for an improved micro-shutter design which can be operated to block over 99% of light, and preferably approaches 100% light blockage, while also being preferably low in cost, and easy and reliable to fabricate. SUMMARY

The present provides an improved micro-shutter and method for fabricating the same. Electrically-switchable smart glass, in accordance with embodiments of the invention, is capable of blocking over 99% of light, and also possibly approaching 100% light blockage, and is thus more suitable for applications such as aerospace and avionics. The improved switchable glass retains the advantages of traditional micro-shutter designs, notably in that it is low in cost, and easy and reliable to fabricate.

According to an aspect, a switchable light-blocking micro-shutter array is provided. The array includes: a transparent substrate having first and second sides; an electrode on said first side of the transparent substrate, said electrode being transparent; an insulator layered on the electrode; a plurality of micro- shutters, each micro-shutter including a fixed end and a mobile end, the fixed end being attached to the insulator and the mobile end being electrostatically actuable by the electrode between an open position in which the mobile end is curled away from the insulator to let light pass through, and a closed position in which the mobile end extends over the insulator to block light, the micro-shutters including gaps between adjacent ones of said micro-shutters while in the closed position; and opaque ribbons positioned to block light from passing through the gaps.

In an embodiment, the opaque ribbons are provided in the insulator. In an embodiment, the ribbons are fixed.

In an embodiment, the ribbons are sized and spaced-apart so as to be invisible to the human eye.

In an embodiment, the ribbons have a width of less than 10 urn. In an embodiment, the micro-shutters are arranged in columns and at least some of the ribbons are positioned to cover gaps between adjacent columns of micro- shutters.

In an embodiment, the ribbons extend along a full length of the columns.

In an embodiment, the columns include a plurality of rows of micro-shutters, and at least some of the ribbons are positioned to cover gaps between adjacent rows of micro-shutters.

In an embodiment, the ribbons extend under at least one of the fixed end and the mobile end of the micro-shutters.

In an embodiment, the mobile end of the micro-shutters includes a distal tip and the fixed end of the micro-shutters includes a proximal tip, and the ribbons extend between adjacent micro-shutters, between the distal tip of a first one of the adjacent micro-shutters and the proximate tip of a second one of the adjacent micro-shutters.

In an embodiment, the ribbon extends at least partially past the distal tip of the first one of the adjacent micro-shutters, and at least partially past the proximate tip of the second one of the adjacent micro-shutters

In an embodiment, at least one of the micro-shutters and ribbons are reflective.

In an embodiment, at least one of the micro-shutters and ribbons are opaque to only some wavelengths of light.

In an embodiment, the micro-shutter array includes a single layer of micro- shutters. In an embodiment, the ribbons are evenly spaced along the substrate. In an embodiment, the ribbons include a thin metal layer.

In an embodiment, the micro-shutters include a film of electrically conductive material.

In an embodiment, the electrode includes a transparent film applied to the first side of the transparent substrate.

In an embodiment, the insulator includes a transparent insulating film coating a side of the electrode.

In an embodiment, the transparent substrate includes a flexible transparent substrate adherable to a rigid transparent substrate.

In an embodiment, the transparent substrate includes glass.

In an embodiment, in the closed configuration, light blockage is greater than or equal to approximately 99.96%.

In an embodiment, in the open configuration, light transmission is greater than or equal to approximately 75%.

It should be understood that the invention permits any combination of the above optional features.

According to an aspect, a switchable light-blocking micro-shutter array is provided. The array includes a plurality of micro-shutters arranged on a transparent substrate, each micro-shutter including: an electrode on a side of the substrate; a dielectric layered on the electrode; and a shutter having a fixed end and a mobile end, the fixed end being attached to the dielectric and the mobile end being electrostatically actuable by the electrode between an open position in which the mobile end is curled away from the insulating film, and a closed position in which the mobile end lays flat over the insulating film. The array also includes a plurality of opaque micro-ribbons positioned to cover gaps between adjacent micro-shutters.

According to an aspect, a switchable light blocking micro-shutter is provided. The micro-shutter includes: a transparent substrate; an electrode applied to a side of the substrate; a dielectric covering a side of the electrode; an opaque, electrically conductive film having a fixed end and a mobile end, the fixed end being attached to the dielectric and the mobile end being electrostatically actuable by the electrode between an open position in which the mobile end is curled away from the dielectric to allow light to pass therethrough, and a closed position in which the mobile end extends over the dielectric to block light from passing therethrough; and an opaque ribbon positioned adjacent the fixed end, opposite the mobile end while in the closed position, to block light from passing through adjacent micro-shutters while in the closed position.

According to an aspect, a method for manufacturing a switchable light-blocking micro-shutter array on a transparent substrate is provided. The method includes the steps of: forming a transparent electrode layer on the transparent substrate; forming a transparent insulating layer on the electrode layer; patterning opaque micro-ribbons to cover the substrate where gaps between adjacent micro- shutters are to be located; forming an array of micro-shutters attached to the insulating layer; and configuring the micro-shutters to curl up to at least partially expose the substrate when no potential is applied to the electrode layer and to cover, together with the micro-ribbons, the substrate when a potential is applied to the electrode layer. According to an aspect, the electrically-switchable smart glass includes opaque micro-ribbons arranged in columns and positioned to cover gaps in the micro- shutters. The micro-ribbons do not block a noticeable amount of light when the micro-shutters are in their open state, but are sized and positioned so that they block nearly all the light that would otherwise pass through the gaps in the micro- shutters.

In a preferred embodiment, the a light blocking micro-shutter assembly is provided, the assembly including a transparent substrate, a transparent electrode layer, a transparent insulating layer, a layer of opaque rolling electrodes, and fixed light-blocking micro-ribbons positioned underneath gaps in the opaque rolling electrodes.

According to possible embodiments, the transparent substrate can include glass or a flexible plastic or film. In some embodiments, the micro-ribbons are provided directly on the transparent substrate. The micro-ribbons can be configured as columns which block light between the gaps of adjacent columns of micro- shutters, and can be made of any opaque organic or inorganic material.

According to alternate embodiments, the micro-ribbons can be provided on an additional thin or flexible substrate atop the transparent substrate. In possible variations, the micro-ribbons can be provided in the electrode layer, in the insulator layer, atop the insulator layer, or any combination thereof. The micro- ribbons can be alternatively or additionally configured in rows to cover gaps between adjacent rows of micro-shutters.

In another aspect of the present invention, a method of fabricating the micro- shutters of the present invention is provided. According to possible embodiments, the micro-ribbons can be patterned either by laser, printing, molding, or standard lithography processes such as electron-beam lithography or optical lithography.

In a preferred embodiment a method for fabricating a light blocking micro-shutter assembly is provided. The method includes the steps of (a) providing a transparent substrate; (b) patterning micro-ribbons; (c) depositing a transparent electrode layer; (d) depositing a transparent insulator layer; (e) patterning an array of opaque rolling electrodes. In other embodiments, step (b) can alternatively be performed after steps (c) or (d).

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1A is a schematic top view of a prior art micro-shutter array in the open state.

Figure 1 B is a cross section view of the micro-shutter array of Figure 1A taken along line 1 B-1 B.

Figure 1 C is a schematic top view of the micro-shutter array of Figure 1A in the closed state.

Figure 1 D is a cross section view of the micro-shutter array of Figure 1 C taken along line 1 D-1 D.

Figure 2A is a schematic top view of a micro-shutter array in the open state according to a first embodiment of the present invention employing micro-ribbons in columns.

Figure 2B is a cross section view of the micro-shutter array of Figure 2A taken along line 2B-2B.

Figure 2C is a top view of the micro-shutter array of Figure 2A in the closed state.

Figure 2D is a cross section view of the micro-shutter array of Figure 2C taken along line 2D-2D.

Figure 3 is a schematic cross section view of a micro-shutter array in the closed state according to a first alternate embodiment wherein the micro-ribbons are located atop the insulator layer.

Figure 4A is a schematic top view of a micro-shutter array in the open state according to a second alternate embodiment, employing micro-ribbons in the form of rows and columns. Figure 4B is a top view of the micro-shutter array of Figure 4A in the closed state.

It should be noted that the appended drawings illustrate only exemplary embodiments, and are therefore not to be construed as limiting the scope of the invention, for the invention can admit to other equally effective embodiments.

It should also be appreciated that the drawings are schematic representations of exemplary embodiments. The features shown in the drawings are not necessarily to scale, and their relative sizes may have been adjusted so that they can be more easily represented.

DETAILED DESCRIPTION

While the general inventive concepts are susceptible of embodiments in many different forms, there are shown in the drawings and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the general inventive concepts. Accordingly, the general inventive concepts are not intended to be limited to the specific embodiments illustrated herein.

In the figures, the same numerical references refer to similar elements. Similar number series are used to refer to similar components in different embodiments. Furthermore, for the sake of simplicity and clarity, namely so as to not unduly burden the figures with several references numbers, not all figures contain references to all the components and features, and references to some components and features may be found in only one figure, and components and features of the present disclosure which are illustrated in other figures can be easily inferred therefrom.

Referring to Figures 1A and 1 B, an array 101 of micro-shutters 2 is shown in the open position 20. The array 101 comprises a plurality of adjacent micro-shutters 2, which can be arranged in columns 14 having individual rows 16 of micro- shutters 2. The micro-shutters 2 comprise a transparent substrate 4, on top of which reside a transparent electrode layer 6 and transparent insulator layer 8. An opaque electrode strip 12 is fixed at an outer end 10, with the other end 1 1 being mobile and biased to curl away from the insulator layer 8. In this open state, light is free to travel through the space between the columns of micro-shutters 14.

The strip 12 can be operate to uncurl to cover most of the space between the micro-shutters 2, as shown in the closed state 21 in Figures 1 C and 1 D. The electrode strip 12 is made from an opaque material and therefore blocks most light from passing through. However, even when uncurled, the electrode strips 12 cannot cover the entire surface area above the layers 4, 6, 8. Light is able to pass through some uncovered areas, so the micro-shutter array 101 is not capable of blocking 100% of incoming light.

Some of these uncovered area as a result of gaps formed during the fabrication process. During fabrication, a strip of opaque material may need to be removed to separate the electrode strips 12 from one another. This removed material leaves a gap 18 between adjacent columns 13 micro-shutters 2 which cannot be covered by the micro-shutters 2 and through which light can pass.

In the micro-shutter array 101 , there may also be gaps between rows 16 of micro-shutters 2 which further account for the surface area which cannot be covered. During the fabrication process, the layer which is to form the electrode strip 12 is under stress. When the layer is released, the stress causes the electrode strip 12 to curl, but also causes it to deform slightly at its sides. This deformation leaves a narrow V-shaped cleave between adjacent rows of micro- shutters 16, defining gaps 19 between rows 16 of micro-shutters 2 which incoming light can pass through.

Improved Micro-Shutter Array with Micro-Ribbons

Referring to Figures 2A and 2B, an array 201 of micro-shutters 202 is shown in the open position 220. The array 201 comprises a plurality of adjacent columns 214, with each column 214 containing rows 216 of micro-shutters 202. Although in the present embodiment the rows 216 in a column 214 are aligned along an axis, it should be appreciated that in other embodiments, the rows 216 can be aligned differently. For example, the rows 216 in a column 214 can be staggered. Similarly, although in the present embodiment each row 216 of micro-shutters

202 in a column 214 extend on a same side thereof, in alternate embodiments the micro-shutters 202 in each row 216 can extend alternatingly on different sides of the same column 214.

Each micro-shutter 202 is part of a stack of layers comprising a substrate layer 204, an electrode layer 206, an insulating layer 208 and a micro-shutter layer 209. Although not illustrated, it should be appreciated that in other embodiments, other layers can also be provided, for example layers which facilitate the manufacturing of the micro-shutters, such as sacrificial layers or release layers.

The substrate layer 204 acts as a base or a support for the remaining layers 206, 208 and 209. The substrate layer 204 can comprise a transparent material, such as glass or plastic for example, with a top side 203 and a bottom side 205. The remaining layers 206, 208, 209 are preferably stacked on the top side 203. The substrate layer 204 can have a thickness which varies depending on the particular application. For example, the substrate layer 204 can be a window pane comprising thick glass. Alternatively, the substrate layer 204 can be thin and possibly flexible piece of plastic or glass. In such a scenario, the bottom side

203 can be provided with an adhesive, allowing the substrate 204 to be applied to another, thicker substrate, such as an existing window pane.

The electrode layer 206 is preferably layered on top of the substrate 204. The electrode 206 is preferably electrically conductive, allowing it to be electrostatically charged. It can, for example, comprise an electrically conductive film, or layers of film, applied to the substrate 204. Preferably, the electrode 206 is transparent or semitransparent, and can comprise ITO, SnO, ZnO, a thin Ag layer or a semi-transparent stack of Ti and Au. Other materials are of course possible.

The insulating layer 208 is preferably provided on top of the electrode layer 204. It can, for example, comprise an insulating film coating the electrode 204. Preferably, the insulating layer 208 comprises a transparent or semi-transparent film of S1O2, Si3N , C2N2, SiC, ΤΊΟ2, AI2O3, or other material. The insulating layer 208 serves as a dielectric, separating the electrode layer 206 from the micro- shutter layer 209 and allowing the two to form a capacitor together. In this sense, the insulating layer 208 can also be referred to as a dielectric layer.

The micro-shutter layer 209 comprises a micro-shutter 202 which is attached to the insulating layer 208. It should be appreciated that the micro-shutter 202 can be attached indirectly to the insulating layer 208, for example through an intermediate layer, depending on the fabrication method. The micro-shutter 202 comprises an opaque or reflective electrode strip 212 fixed at its outer end 210 (also referred to its fixed end) to the insulating layer 208, while the other end, i.e. the mobile end 21 1 , is mobile. The micro-shutter 202 is biased such that it can move between an open position 220 and a closed position (221 , as shown in figures 2C and 2D). In the present embodiment, the electrode strip 212 is biased such that in a relaxed state, the mobile end 21 1 curls away from the insulating layer 208. In this open position 220, light is free to travel relatively unobstructed between the micro-shutters 214, and through the underlying transparent layers 204, 206, 208.

When a voltage is applied between the electrode layer 206 and the electrode strip 212, the strip 212 uncurls to cover most of the space between the columns 214, as shown in the closed state 221 in Figures 2C and 2D. The electrode strip 212 is made from an opaque material and therefore blocks most light from passing through the transparent layers 204, 206, 208. When the voltage is removed, the strip 212 can relax, allowing it to return to the curled or relaxed position (220 as shown in figures 2A and 2B), allowing light to pass again. In this sense, the micro-shutter array 201 can be referred to as a switchable light- blocking array, in that it can be electrostatically actuated to switch between a light transmission and a light blocking state. The micro-shutter array 201 is provided with a mechanism for covering areas which cannot be covered by the micro-shutters 202 alone. Referring to Figures 2A and 2B, the micro-shutter array 201 includes ribbons 222 which are preferably fixed, i.e. do not move when a potential is applied to the electrode 206. The ribbons 222 are preferably made from an opaque or reflective material, allowing them to block light from passing through the insulator layer 208 and therefore through the remaining transparent layers 206, 204. The ribbons 222 are thin, i.e. on the order of m and preferably less than 10 m, such that they are invisible to the naked eye and do not block a significant amount of light while the micro- shutter array 201 is in the open state 220. In this sense, the ribbon 222 can also be referred to as a micro-ribbon. Preferably, for example to reduce manufacturing costs and to increase light transmission in the open position, only one layer 209 of micro-shutters is provided.

In the present embodiment, as more clearly illustrated in Figures 2C and 2D, the micro-ribbons 222 are arranged in a column configuration 224 and positioned underneath the gaps 218 between columns 214 of micro-shutters 202. In this configuration, the micro-ribbons 222 block incoming light that would otherwise travel through the space between the fixed end 210 of an electrode strip 212 and the mobile end 21 1 of an adjacent electrode strip 212 while the micro-shutter array 201 is in the closed state 221 . The width of the micro-ribbon 222 should therefore be selected to be wide enough so that it can cover the entire gap 218 between columns 214 of micro-shutters 202 while the array is in the closed state 221 . Preferably, the ribbons 222 should be sufficiently spaced-apart and thin enough so that they do not block a significant amount of light and are invisible to the eye while the array is in the open state 220. For example, in a typical micro- shutter array, the gaps 218 between columns 214 can range between 3 m to 6 Mm, and appropriate width for the micro-ribbons 222 would be in a range of between 6 Mm to 10 Mm. This can result, for example, in having light transmission approximately 75% or greater in the open state 220, while having light blockage of approximately 99.96% in the closed state 221 . To aid in blocking light more effectively, the micro-ribbons 222 can be sized and positioned so that they partially overlap with an area already covered by the outer end of an electrode strip 210 and/or the free end of an adjacent electrode strip 212. In other words, the ribbons 222 can be configured to extend between adjacent micro-shutters 202, 202', between a distal tip 215 of the first shutter 202, and a proximate tip 213 of the second micro-shutter 202'. The ribbons 222 can extend past the distal tip 215 and/or past the proximate tip 213.

The micro-ribbons 222 can be made of any opaque organic or inorganic material, and are preferably provided in a layer below the electrode strips 212. For example, they could be a thin metal layer, or could comprise of nanoparticles or nanocrystals. The micro-ribbon 222 material can be selected based on the desired transmission properties of the micro-shutter array. For example different materials can be used if the array is designed to block all light, or only specific wavelength ranges such as infrared or ultraviolet.

In the present embodiment, the micro-ribbons 222 are provided within the insulator layer 208. Although in the illustrations the micro-ribbons 222 extend only partially along the height of the insulator layer 208, it should be appreciated that in some embodiments, the ribbons 222 can extend along the full height of the layer 208. The ribbons 222 can, for example, be etched in to a film forming the insulator layer 208 to any desired depth. Of course, other possible configurations are also possible in accordance with the presently disclosed invention. For example, as illustrated in an alternate embodiment of a micro-shutter array 301 in Figure 3, the micro-ribbons 222 can be located on top of the insulator layer 208. Other variations can include the micro-ribbons 222 being located in, on top of, or under any one of the transparent electrode layer 206, insulator layer 208, or transparent substrate 204, or any combination thereof. In some configurations, the micro-ribbons can be patterned or etched in an existing layer, or could be provided in a distinct layer. In some embodiments, an additional insulator layer can be located directly above the micro-ribbon layer. In some embodiments, for example when the transparent substrate 204 is a thin plastic, glass or film which is to be applied to another thicker substrate, the micro-ribbons 222 can be additionally or alternatively applied directly to or provided directly in the transparent substrate 204. The position of the micro-ribbon 222 can be selected based on fabrication requirements.

In the embodiments presented above, the micro-ribbons 222 were provided in only a column configuration 224. However, in accordance with the presently disclosed invention, in order to block additional light from passing through exposed areas of a micro-shutter array, many different patterns of micro-ribbons 222 and combinations thereof are also possible. For example, as illustrated in the possible embodiment of a micro-shutter array 401 of Figures 4A and 4B, the micro-ribbons 222 can be configured in a row configuration 225 complementary to the column configuration 224. In this embodiment, the rows of micro-ribbons 225 are positioned so that they are directly underneath the gaps 219 between rows 216 of micro-shutters 202. This configuration of ribbons blocks the remaining exposed areas, approaching 100% light blockage by the micro-shutter array 401 . According to varying fabrication needs, the micro-ribbons in the row configuration 225 can be patterned in the same layer as those in the column configuration 224, or in a different layer. In some embodiments, the micro-ribbons 222 can be provided in only the row configuration 225. In yet further embodiments, the micro-ribbons 222 can be sparse and only cover a certain number of gaps 218 or 219, or be positioned to cover other gaps which may exist in a micro-shutter array.

In alternate embodiments, for example when the array comprises micro-shutters 202 of varying sizes, the micro-ribbons can be configured in varying patterns, such as a step or zigzag pattern, and can be provided with varying widths depending on the size of gaps being covered. As can be further appreciated, although the micro-ribbons illustrated above were shown in conjunction with uniform columns and rows of micro-shutters, it should be appreciated that the micro-ribbons can also be used in other configurations of micro-shutters. For example, micro-ribbons can also be used in configurations having columns with rows of micro-shutters extending on alternating sides. Method for Fabricating

A further aspect of the present invention provides a method for fabricating the improved micro-shutter array with micro-ribbons disclosed hereinabove. Depending on the material used, the micro-ribbons can be patterned using known techniques such as by laser, printing or molding, or by electron beam or optical lithography processes. Depending on the desired layer/location of the micro-ribbons, the patterning of the micro-ribbons can be done during the appropriate step of known processes for fabricating micro-shutter arrays.

According to an exemplary embodiment, the method comprises the steps of (a) providing a transparent substrate; (b) patterning micro-ribbons; (c) depositing a transparent electrode layer; (d) depositing a transparent insulator layer; (e) patterning an array of opaque rolling electrodes. In other embodiments, step (b) can alternatively be performed after steps (c) or (d). In yet other embodiments, an additional step of depositing an additional transparent insulator layer can occur after step (b).

Of course, other processing steps can be performed prior, during or after the above described steps. Also, the order of the steps can also differ, and some of the steps can be combined or omitted. The figures illustrate only exemplary embodiments of the invention and are, therefore, not to be considered limiting of its scope, for the invention can admit to other equally effective embodiments. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

Claims

1 . A switchable light-blocking micro-shutter array comprising:

- a transparent substrate having first and second sides;

- an electrode on said first side of the transparent substrate, said electrode being transparent;

- an insulator layered on the electrode;

- a plurality of micro-shutters, each micro-shutter comprising a fixed end and a mobile end, the fixed end being attached to the insulator and the mobile end being electrostatically actuable by the electrode between an open position in which the mobile end is curled away from the insulator to let light pass through, and a closed position in which the mobile end extends over the insulator to block light, the micro-shutters comprising gaps between adjacent ones of said micro-shutters while in the closed position; and

- opaque ribbons positioned to block light from passing through the gaps.

2. The switchable light-blocking micro-shutter array according to claim 1 , wherein the opaque ribbons are provided in the insulator.

3. The switchable light-blocking micro-shutter array according to claims 1 or 2, wherein the ribbons are fixed.

4. The switchable light-blocking micro-shutter array according to any one of claims 1 to 3, wherein the ribbons are sized and spaced-apart so as to be invisible to the human eye.

5. The switchable light-blocking micro-shutter array according to any one of claims 1 to 4, wherein the ribbons have a width of less than 10 urn.

6. The switchable light-blocking micro-shutter array according to any one of claims 1 to 5, wherein the micro-shutters are arranged in columns and wherein at least some of the ribbons are positioned to cover gaps between adjacent columns of micro-shutters.

7. The switchable light-blocking micro-shutter array according to claim 6, wherein the ribbons extend along a full length of the columns.

8. The switchable light-blocking micro-shutter array according to claims 6 or 7, wherein the columns comprise a plurality of rows of micro-shutters, and wherein at least some of the ribbons are positioned to cover gaps between adjacent rows of micro-shutters.

9. The switchable light-blocking micro-shutter array according to any one of claims 1 to 8, wherein the ribbons extend under at least one of the fixed end and the mobile end of the micro-shutters.

10. The switchable light-blocking micro-shutter array according to any one of claims 1 to 9, wherein the mobile end of the micro-shutters comprises a distal tip and the fixed end of the micro-shutters comprises a proximal tip, and wherein the ribbons extend between adjacent micro-shutters, between the distal tip of a first one of the adjacent micro-shutters and the proximate tip of a second one of the adjacent micro-shutters.

1 1 . The switchable light-blocking micro-shutter array according to claim 10, wherein the ribbon extends at least partially past the distal tip of the first one of the adjacent micro-shutters, and at least partially past the proximate tip of the second one of the adjacent micro-shutters

12. The switchable light-blocking micro-shutter array according to any one of claims 1 to 1 1 , wherein at least one of the micro-shutters and opaque ribbons are reflective.

13. The switchable light-blocking micro-shutter array according to any one of claims 1 to 12, wherein at least one of the micro-shutters and opaque ribbons are opaque to only some wavelengths of light.

14. The switchable light-blocking micro-shutter array according to any one of claims 1 to 13, wherein the micro-shutter array comprises a single layer of micro-shutters.

15. The switchable light-blocking micro-shutter array according to any one of claims 1 to 14, wherein the ribbons are evenly spaced along the substrate.

16. The switchable light-blocking micro-shutter array according to any one of claims 1 to 15, wherein the ribbons comprise a thin metal layer.

17. The switchable light-blocking micro-shutter array according to any one of claims 1 to 16, wherein the micro-shutters comprise a film of electrically conductive material.

18. The switchable light-blocking micro-shutter array according to any one of claims 1 to 17, wherein the electrode comprises a transparent film applied to the first side of the transparent substrate.

19. The switchable light-blocking micro-shutter array according to any one of claims 1 to 18, wherein the insulator comprises a transparent insulating film coating a side of the electrode.

20. The switchable light-blocking micro-shutter array according to any one of claims 1 to 19, wherein the transparent substrate comprises a flexible transparent substrate adherable to a rigid transparent substrate.

21 . The switchable light-blocking micro-shutter array according to any one of claims 1 to 19, wherein the transparent substrate comprises glass.

22. The switchable light-blocking micro-shutter array according to any one of claims 1 to 21 , wherein in the closed position, light blockage is greater than or equal to approximately 99.96%.

23. The switchable light-blocking micro-shutter array according to any one of claims 1 to 22, wherein in the open position, light transmission is greater than or equal to approximately 75%.

24. A switchable light-blocking micro-shutter array comprising:

- a plurality of micro-shutters arranged on a transparent substrate, each micro-shutter comprising:

o an electrode on a side of the substrate;

o a dielectric layered on the electrode; and

o a shutter having a fixed end and a mobile end, the fixed end being attached to the dielectric and the mobile end being electrostatically actuable by the electrode between an open position in which the mobile end is curled away from the dielectric, and a closed position in which the mobile end lays flat over the dielectric; and

- a plurality of opaque micro-ribbons positioned to cover gaps between adjacent micro-shutters.

25. A switchable light blocking micro-shutter comprising:

- a transparent substrate; - an electrode applied to a side of the substrate;

- a dielectric covering a side of the electrode;

- an opaque, electrically conductive film having a fixed end and a mobile end, the fixed end being attached to the dielectric and the mobile end being electrostatically actuable by the electrode between an open position in which the mobile end is curled away from the dielectric to allow light to pass therethrough, and a closed position in which the mobile end extends over the dielectric to block light from passing therethrough; and

- an opaque ribbon positioned adjacent the fixed end, opposite the mobile end while in the closed position, to block light from passing through adjacent micro-shutters while in the closed position.

26. A method for manufacturing a switchable light-blocking micro-shutter array on a transparent substrate, the method comprising the steps of:

- forming a transparent electrode layer on the transparent substrate;

- forming a transparent insulating layer on the electrode layer;

- patterning opaque micro-ribbons to cover the substrate where gaps between adjacent micro-shutters are to be located;

- forming an array of micro-shutters attached to the insulating layer; and

- configuring the micro-shutters to curl up to at least partially expose the substrate when no potential is applied to the electrode layer and to cover, together with the micro-ribbons, the substrate when a potential is applied to the electrode layer.