Patent Publication Number: US-11047170-B2

Title: Slat assembly for roller shutter, roller shutter, and methods of manufacture thereof

Description:
RELATED APPLICATIONS 
     This application claims priority to PCT International Patent Application No. PCT/SG2019/050050 filed Jan. 30, 2019, which claims the priority benefit of Singaporean Patent Application Nos. 10201800852V filed Jan. 31, 2018 and 10201806540T filed Jul. 31, 2018. Each of these three applications is hereby incorporated by reference in their entireties. 
     TECHNICAL FIELD 
     Embodiments generally relate to a slat assembly for a roller shutter, a roller shutter, a method of manufacturing a slat assembly, and a method of manufacturing a roller shutter. 
     BACKGROUND 
     Roller shutter has been commonly installed at the entrance of various types of premises such as retail shops, warehouses, buildings, hangars, garages, etc. for controlling physical access into the enclosed space of the respective premises. When the shutter curtain of the roller shutter is down, it provides protection against environmental factors such as wind and/or rain. It also provides security protection against intrusion or breaking in. In certain applications, it is also required to act as a fire barrier to impede the spread of fire. Further, according to the fire codes of some countries, these fire shutters in compartment walls are also required to be insulated according to stringent standards. Since most of these shutters are made of metal such as steel which are good conductor of heat, in the event of a fire, while the shutter curtain of the roller shutter may physically prevent the flames from passing through for a period of time, the shutter curtain may not prevent the conduction of the heat which may also quickly lead to the spread of the fire to the other side of the shutter curtain. 
     In general, a common method of insulating a roller shutter is to place an insulation layer such as an insulation blanket or insulation mat or insulation sheet behind the shutter curtain of the roller shutter. For example, the insulation layer may be customized to the size of the shutter curtain of the roller shutter and be configured to be rolled together with the shutter curtain. To maintain the thermal insulation integrity of the insulation layer, the insulation layer may merely be placed flat against the shutter curtain. However, in such a configuration, the insulation layer may misalign or bulge or tear or over-stretch during rolling and unrolling with the shutter curtain. Accordingly, more recently, it has been proposed to secure the insulation layer to the shutter curtain via rivets or screws puncturing through the insulation layer and to provide additional insulating components to minimize the conduct of heat through the insulation layer via the rivets or screws. However, such configuration is usually complex, is not economical and may require high maintenance to ensure that the insulating components are effective in minimizing the conduct of heat through the insulation layer via the rivets or screws. 
     SUMMARY 
     According to various embodiments, there is provided a slat assembly for a roller shutter. The slat assembly may include a slat having a first receiving portion and a second receiving portion. The slat assembly may further include an insulation layer lined on the slat. The first and second receiving portions of the slat may be a pair of bent portions of the slat. Each of the pair of bent portions may form an acute angle. The slat assembly may further include a retaining mechanism disposed on the insulation layer to press a first portion of the insulation layer into the first receiving portion of the slat and to press a second portion of the insulation layer into the second receiving portion of the slat such that the retaining mechanism may cooperate with the first and second receiving portions of the slat to hold the insulation layer between the retaining mechanism and the slat. 
     According to various embodiments, there is provided a roller shutter. The roller shutter may include a plurality of slats pivotally interlocked one after another to form a shutter curtain. The roller shutter may further include an insulation layer lined across at least two adjacent pivotally interlocked slats of the plurality of slats. The roller shutter may further include at least one retaining mechanism disposed on the insulation layer to press a portion of the insulation layer into a first receiving portion of one of the at least two adjacent pivotally interlocked slats and to press a further portion of the insulation layer into a second receiving portion of the one of the at least two adjacent pivotally interlocked slats such that the at least one retaining mechanism may cooperate with the first and second receiving portions of the one of the at least two adjacent pivotally interlocked slats to hold the insulation layer between the at least one retaining mechanism and the at least two adjacent pivotally interlocked slats. According to various embodiments, the first and the second receiving portions of the one of the at least two adjacent pivotally interlocked slats may be a pair of bent portions of the one of the at least two adjacent pivotally interlocked slats. Each of the pair of bent portions may form an acute angle. 
     According to various embodiments, there is provided a method of manufacturing a slat assembly. The method may include providing a slat having a first receiving portion and a second receiving portion. The first and second receiving portions of the slat may be a pair of bent portions of the slat. Each of the pair of bent portions may form an acute angle. The method may further include lining an insulation layer on the slat. The method may further include disposing a retaining mechanism on the insulation layer to press a first portion of the insulation layer into the first receiving portion of the slat and to press a second portion of the insulation layer into the second receiving portion of the slat such that the retaining mechanism may cooperate with the first and second receiving portions of the slat to hold the insulation layer between the retaining mechanism and the slat. 
     According to various embodiments, there is provided a method of manufacturing a roller shutter. The method may include providing a plurality of slats pivotally interlocked one after another to form a shutter curtain. The method may further include lining an insulation layer across at least two adjacent pivotally interlocked slats of the plurality of slats. The method may further include disposing at least one retaining mechanism on the insulation layer to press a portion of the insulation layer into a first receiving portion of one of the at least two adjacent pivotally interlocked slats and to press a further portion of the insulation layer into a second receiving portion of the one of the at least two adjacent pivotally interlocked slats such that the at least one retaining mechanism may cooperate with the first and second receiving portions of the one of the at least two adjacent pivotally interlocked slats to hold the insulation layer between the at least one retaining mechanism and the at least two adjacent pivotally interlocked slats. According to various embodiments, the first and second receiving portions of the one of the at least two adjacent pivotally interlocked slats may be a pair of bent portions of the one of the at least two adjacent pivotally interlocked slats. Each of the pair of bent portions may form an acute angle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the description provided herein and the advantages thereof, reference is now made to the brief descriptions below, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts. In the drawings, figures are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments are described with reference to the following drawings. 
         FIG. 1A  shows an exploded view of a slat assembly for a roller shutter according to various embodiments; 
         FIG. 1B  shows an assembled view of the slat assembly of  FIG. 1A  according to various embodiments; 
         FIG. 1C  shows a perspective view of a portion of the slat of the slat assembly of  FIG. 1A  according to various embodiments; 
         FIG. 1D  shows a side view of the slat of  FIG. 1C  according to various embodiments; 
         FIG. 2A  shows an exploded view of a slat assembly for a roller shutter according to various embodiments; 
         FIG. 2B  shows an assembled view of the slat assembly of  FIG. 2A  according to various embodiments; 
         FIG. 3A  shows a perspective view of a shutter curtain assembly according to various embodiments; 
         FIG. 3B  shows a side view of the shutter curtain assembly of  FIG. 3A  according to various embodiments; 
         FIG. 3C  shows an enlarged side view of a section of the shutter curtain assembly of  FIG. 3A  according to various embodiments; 
         FIG. 4  shows a perspective view of a shutter curtain assembly according to various embodiments; 
         FIG. 5A  shows a side cross-sectional view of an upper portion of a vertical roller shutter according to various embodiments; 
         FIG. 5B  shows a side cross-sectional view of a lower portion of the vertical roller shutter, when in a lowered state, according to various embodiments; 
         FIG. 6  shows a side cross-sectional view of an upper portion of a vertical roller shutter according to various embodiments; 
         FIG. 7  shows a top cross-sectional view of a lateral roller shutter according to various embodiments; 
         FIG. 8  shows a top cross-sectional view of a lateral roller shutter according to various embodiments; 
         FIG. 9  shows a schematic side view of an upper portion of a vertical roller shutter according to various embodiments; 
         FIG. 10A  and  FIG. 10B  show a front view and a cross-sectional side view of a vertical roller shutter, in a lowered state, according to various embodiments; 
         FIG. 10C  shows the positions of motor assemblies from a top view of the vertical roller shutter of  FIG. 10A  according to various embodiments; 
         FIG. 10D  shows a photograph of an actual implementation of the vertical roller shutter of  FIG. 10A  according to various embodiments; 
         FIG. 11A  shows a schematic side view of an upper portion of a vertical roller shutter according to various embodiments; 
         FIG. 11B  shows a photograph of an actual implementation of the vertical roller shutter of  FIG. 11A  according to various embodiment; 
         FIG. 12A  shows a top cross-sectional view of a lateral roller shutter according to various embodiments; 
         FIG. 12B  shows a top cross-sectional view of a lateral roller shutter according to various embodiments; 
         FIG. 13  shows a schematic side view of an upper portion of a vertical roller shutter according to various embodiments; 
         FIG. 14A  shows a top cross-sectional view of a lateral roller shutter according to various embodiments; 
         FIG. 14B  shows a top cross-sectional view of a lateral roller shutter according to various embodiments; 
         FIG. 15A  and  FIG. 15B  show side views of two slats pivotably interlocked to each other in a suspended mode and in a stacked mode respectively according to various embodiments; 
         FIG. 15C  and  FIG. 15D  shows perspective views of the two slats in the suspended mode and in the stacked mode respectively according to various embodiments; 
         FIG. 16  shows a schematic side view of a vertical roller shutter  1600  according to various embodiments; 
         FIG. 17A  to  FIG. 17C  show a sequence of how the plurality of slats of the respective shutter curtain assembly of the vertical roller shutter of  FIG. 16  being stacked; and 
         FIG. 18  shows a schematic side view of a vertical roller shutter  1800  according to various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments described below in context of the apparatus are analogously valid for the respective methods, and vice versa. Furthermore, it will be understood that the embodiments described below may be combined, for example, a part of one embodiment may be combined with a part of another embodiment. 
     It should be understood that the terms “on”, “over”, “top”, “bottom”, “down”, “side”, “back”, “left”, “right”, “front”, “lateral”, “side”, “up”, “down” etc., when used in the following description are used for convenience and to aid understanding of relative positions or directions, and not intended to limit the orientation of any device, or structure or any part of any device or structure. In addition, the singular terms “a”, “an”, and “the” include plural references unless context clearly indicates otherwise. Similarly, the word “or” is intended to include “and” unless the context clearly indicates otherwise. 
     Various embodiments of a slat assembly for a roller shutter, a roller shutter, a method of manufacturing a slat assembly for a roller shutter and a method of manufacturing a roller shutter have been provided to address at least some of the issues identified earlier. 
     According to various embodiments, an insulation layer in the form of an insulation blanket or an insulation mat or an insulation sheet may be secured or attached or fastened to a slat of a shutter curtain of a roller shutter without puncturing or penetrating the insulation layer with fasteners. Accordingly, the insulation layer may be secured or attached or fastened to the shutter curtain of the roller shutter such that the slats of the shutter curtain may be free of any fasteners that may form a “thermal bridge” through the insulation layer. Hence, the insulation layer may be intact and the thermal insulation integrity of the insulation layer may be fully preserved such that the insulation layer may be effective in providing insulation to the shutter curtain. At the same time, the insulation layer may be properly secured, attached or fastened to the shutter curtain such that the insulation layer may be rolled or unrolled together with the shutter curtain in a manner which minimizes or eliminates misalignment or bulging or tearing or over-stretching of the insulation layer. 
       FIG. 1A  shows an exploded view of a slat assembly  100  for a roller shutter according to various embodiments.  FIG. 1B  shows an assembled view of the slat assembly  100  of  FIG. 1A  according to various embodiments. According to various embodiments, the slat assembly  100  may include a slat  110  having a first receiving portion  130  and a second receiving portion  140 . 
     According to various embodiments, the slat  110  may be a narrow flat strip of material, for example metal such as steel or aluminum. According to various embodiments, the first receiving portion  130  and the second receiving portion  140  of the slat  110  may include, for example, recess portions, indentations, slots, grooves, depressions, folded portions, bent portions, channels, cuts, furrows, trench, gutter or any suitable feature which provides a cavity, gap, hollow, void, or empty space configured for receiving, containing, accommodating, holding, or retaining an external insulation element or part or component, such as an insulation layer. 
       FIG. 1C  shows a perspective view of a portion of the slat  110  according to various embodiments.  FIG. 1D  shows a side view of the slat  110  according to various embodiments. The slat  110  may include a main portion  112  between a first longitudinal edge portion  114  and a second longitudinal edge portion  116 . The main portion  112  of the slat  110  may be the main body of the slat  110  for lining abreast or placing side by side with the main portion of adjacent slat so as to form a shutter curtain. 
     As shown, the first receiving portion  130  of the slat  110  may be an inward bend  132  (or inward fold) at the first longitudinal edge portion  114  of the slat  110 . According to various embodiments, the slat  110  may be formed or shaped or profiled or made or molded or pressed from an elongated sheet of material, such as an elongated sheet of metal. Accordingly, the inward bend  132  at the first longitudinal edge portion  114  may be formed from bending or folding a first longitudinal edge  113  of the sheet of material lengthwise inwardly towards a longitudinal axis  111  of the slat  110 . Hence, the inward bend  132  may be immediately adjacent to the main portion  112  of the slat  110 . As shown, a first elongate overhang portion  131  of the slat  110  may extend laterally from the inward bend  132  of the first longitudinal edge portion  114  such that the first elongate overhang portion  131  of the slat  110  may be angled less than 90° with respect to the main portion  112  of the slat  110 . Accordingly, the first elongate overhang portion  131  of the slat  110  and the main portion  112  of the slat  110  may form a groove with a V-shaped or U-shaped or a horse-shoe-shaped cross-section, and the inward bend  132  of the first longitudinal edge portion  114  may of an acute angle. As shown, the second receiving portion  140  of the slat  110  may be an inward bend  142  (or inward fold) at a second longitudinal edge portion  116  of the slat  110 . According to various embodiments, the inward bend  142  at the second longitudinal edge portion  116  may be formed from bending or folding a second longitudinal edge  115  of the sheet of material lengthwise inwardly towards the longitudinal axis  111  of the slat  110 . Accordingly, the inward bend  142  may be immediately adjacent to the main portion  112  of the slat  110 . As shown, a second elongate overhang portion  141  of the slat  110  may extend laterally from the inward bend  142  of the second longitudinal edge portion  116  such that the second elongate overhang portion  141  of the slat  110  may be angled less than 90° with respect to the main portion  112  of the slat  110 . Accordingly, the second elongate overhang portion  141  of the slat  110  and the main portion  112  of the slat  110  may form a groove with a V-shaped or U-shaped or horse-shoe-shaped cross-section, and the inward bend  142  of the second longitudinal edge portion  116  may of an acute angle. As shown, the pair of inward bends  132 ,  142  at the respective first longitudinal edge portion  114  and the second longitudinal edge portion  116  may extend through the entire length of the slat  110  and may be at least substantially parallel to each other. According to various other embodiments, the inward bend at the first longitudinal edge portion and the inward bend at the second longitudinal edge portion may extend along only a portion of the length of the slat. According to various other embodiments, the pair of inward bends may also be non-parallel to each other. 
     According to various embodiments, the inward bend  132  at the first longitudinal edge portion  114  and the inward bend  142  at the second longitudinal edge portion  116  may form a pair of grooves  134 ,  144 , which may be opposing each other and which may have a V-shaped or U-shaped or a horse-shoe-shaped cross-section. Accordingly, the pair of grooves  134 ,  144  may be a pair of inwardly bent portions (or folded portions) of the slat  110 . Each of the pair of inwardly bent portions of the slat  110  may be formed from bending inwardly towards the longitudinal axis of the slat so as to form the respective acute angle. 
     As shown in  FIG. 1C  and  FIG. 1D , the inward bend  132  at the first longitudinal edge portion  114  may be followed by an outward bend  118  (or outward fold) formed from subsequent bending or folding of the first longitudinal edge  113  of the elongated sheet of material lengthwise away from the longitudinal axis  111  of the slat  110 . Accordingly, from the first elongate overhang portion  131 , the sheet of material may be bent or folded outwardly away from the longitudinal axis  111  of the slat  110  to form the outward bend  118 . As shown, an elongate winged-like portion  119  of the slat  110  may extend laterally from the outward bend  118  such that the elongate winged-like portion  119  of the slat  110  may be angled less than 90° with respect to the first elongate overhang portion  131  of the slat  110 . Accordingly, the elongate winged-like portion  119  of the slat  110  and the first elongate overhang portion  131  of the slat  110  may form a V-shaped or U-shaped cross-section, and the outward bend  118  of the first longitudinal edge portion  114  may of an acute angle. Further, the outward bend  118  of the first longitudinal edge portion  114  may be followed by an inward curl  120  formed from subsequent curling of the first longitudinal edge  113  of the elongated sheet of material lengthwise inwardly towards the longitudinal axis  111  of the slat  110 . Accordingly, from the winged-like portion  119  of the slat  110 , the sheet of material may be curled inwardly towards the longitudinal axis  111  of the slat  110 . Hence, the inward curl  120  may form a first curled edge portion of the slat  110 . The first curled edge portion of the slat  110  may be a first interlocking element of the slat  110 . Accordingly, the first curled edge portion of the slat  110  may be configured for engaging, interlocking, or interacting with a corresponding interlocking element of another slat to pivotably join the two slats together. According to various embodiments, the first longitudinal edge portion  114  of the slat  110  may include the inward bend  132 , the first elongate overhang portion  131 , the outward bend  118 , the elongate winged-like portion  119 , and the inward curl  120 . 
     Further, as also shown, the inward bend  142  at the second longitudinal edge portion  116  may be followed by an outward curl  122  formed from subsequent curling of the second longitudinal edge  115  of the elongated sheet of material lengthwise outwardly away from the longitudinal axis  111  of the slat  110 . Accordingly, from the second elongate overhang portion  141 , the sheet of material may be curled outwardly away from the longitudinal axis  111  of the slat  110  to form the outward curl  122 . Hence, the outward curl  122  may form a second curled edge portion of the slat  110 . The second curled edge portion of the slat  110  may be a second interlocking element of the slat  110 . Similar to the first curled edge portion, the second curled edge portion of the slat  110  may be configured for engaging, interlocking, or interacting with a corresponding interlocking element of another slat to pivotably join the two slats together. According to various embodiments, the second longitudinal edge portion  116  of the slat  110  may include the inward bend  142 , the second elongate overhang portion  141 , and the outward curl  122 . 
     According to various embodiments, a curl radius of the inward curl  120  at the first longitudinal edge portion  114  may be smaller than a curl radius of the outward curl  122  at the second longitudinal edge portion  116 . Accordingly, two adjacent slats may be joined together by, for example, overlapping, fitting, interlocking, engaging, interacting or joining of an inward curl at a first longitudinal edge portion of a first slat to an outward curl at a second longitudinal edge portion of a second slat such that the first slat may be pivotably joined to the second slat. According to various embodiments, the slat  110  may be configured to overlap or fit or interlock or joined with a further slat  110 , one after another in a series, so as to form a shutter curtain. 
     Referring back to  FIG. 1A  and  FIG. 1B , the slat assembly  100  may further include an insulation layer  150  lined on the slat  110 . According to various embodiments, the insulation layer  150  may be in the form of an insulation blanket, an insulation mat, or an insulation sheet. According to various embodiments, the insulation layer  150  may be configured to provide thermal insulation. According to various embodiments, the insulation layer  150  may include a layer of insulation wool sandwiched between two layers of insulation cloths. According to various embodiments, the insulation wool may include ceramic fiber wool or rock wool etc. According to various embodiments, the insulation cloth may include silica fabric or fibre-glass fabric etc. 
     According to various embodiments, the insulation layer  150  may cover or lay or spread or stretch across a side of the slat  110  whereby the first receiving portion  130  and the second receiving portion  140  may be accessible. Accordingly, the side of the slat  110  on which the insulation layer  150  is lined may be opposite to the exterior side or surface of the slat  110  exposed to the exterior of the premises which the shutter may be installed. 
     As shown in  FIG. 1A  and  FIG. 1B , the slat assembly  100  may further include a retaining mechanism  160  (or at least one retaining mechanism) disposed on the insulation layer  150  to urge or press or push a first portion of the insulation layer  150  against the first receiving portion  130  of the slat  110  and to urge or press or push a second portion of the insulation layer  150  against the second receiving portion  140  of the slat  110  such that the retaining mechanism  160  may cooperate with the first receiving portion  130  and the second receiving portion  140  of the slat  110  to hold or clamp or grip or clench the insulation layer  150  between the retaining mechanism  160  and the slat  110  without puncturing or penetrating the insulation layer  150 . Accordingly, the insulation layer  150  may be sandwiched between the retaining mechanism  160  and the slat  110 . According to various embodiments, a first surface of the insulation layer  150  may be in contact with the slat while the retaining mechanism  160  may be placed or received or disposed on a second surface of the insulation layer  150 . The first surface and the second surface of the insulation layer  150  may be opposite surfaces. 
     While  FIG. 1A  and  FIG. 1B  show that one retaining mechanism  160  may be disposed to simultaneously urge the first portion of the insulation layer  150  against the first receiving portion  130  of the slat  110  and the second portion of the insulation layer  150  against the second receiving portion  140  of the slat  110 , it should be understood by those skilled in the art that various changes, modification, variation may be made. 
     According to various embodiments, the slat assembly  100  may include one or two or more or a plurality of retaining mechanisms  160 . Referring back to  FIG. 1A  and  FIG. 1B , according to various embodiments, the retaining mechanism  160  may include a first end  164  and a second end  166 . According to various embodiments, the first end  164  and the second end  166  may be opposite ends of the retaining mechanism  160 . The first end  164  may be configured for urging or pressing or pushing the first portion of the insulation layer  150  against the first receiving portion  130  of the slat  110 . Accordingly, the first portion of the insulation layer  150  may be sandwiched between the first end  164  of the retaining mechanism  160  and the first receiving portion  130  of the slat  110 . Further, the second end  166  may be configured for urging or pressing or pushing the second portion of the insulation layer  150  against the second receiving portion  140  of the slat  110 . Accordingly, the second portion of the insulation layer  150  may be sandwiched between the second end  166  of the retaining mechanism  160  and the second receiving portion  140  of the slat  110 . According to various embodiments, the first receiving portion  130  of the slat  110  and the second receiving portion  140  of the slat  110  may be at opposing longitudinal edge portions  114 ,  116  of the slat  110 . 
     According to various embodiments, the retaining mechanism  160  may be pre-loaded so as to supply an expansion force for urging, pressing, or pushing the first portion and the second portion of the insulation layer  150  against the respective first receiving portion  130  and the second receiving portion  140  of the slat  110 . Accordingly, the retaining mechanism  160  may be pre-compressed prior to being disposed on the insulation layer  150 , such that when the retaining mechanism  160  is disposed on the insulation layer  150 , the retaining mechanism  160  may apply a spreading force or expansion force on the insulation layer  150  such that the retaining mechanism  160  may urge or press or push respective portions of the insulation layer  150  against the respective first receiving portion  130  and the second receiving portion  140  of the slat  110 , which may be opposing facing relative to each other. Hence, the retaining mechanism  160  may be pre-loaded such that the first end  164  and the second end  166  of the retaining mechanism  160  may be biased away from each other so as to engage or contact or interact with the respective portions of the insulation layer  150  for urging or pressing or pushing the respective portions of the insulation layer  150  against the respective first receiving portion  130  and second receiving portion  140  of the slat  110 . 
     According to various embodiments, the retaining mechanism  160  may be configured to press the first portion of the insulation layer  150  into the first receiving portion  130  of the slat  110  and to press the second portion of the insulation layer  150  into the second receiving portion  140  of the slat  110 . Accordingly, the force exerted by the first end  164  of the retaining mechanism  160  may cause the first portion of the insulation layer  150  to be received, contained, accommodated, held, or retained in the first receiving portion  130  of the slat  110 . Similarly, the force exerted by the second end  166  of the retaining mechanism  150  may cause the second portion of the insulation layer  150  to be received, contained, accommodated, held, or retained in the second receiving portion  140  of the slat  110 . Hence, the first end  164  and the second end  166  of the retaining mechanism  160  may cooperate with the first receiving portion  130  and the second receiving portion  140  of the slat  110  to hold or clamp or grip or clench the insulation layer  150  therebetween without puncturing or penetrating the insulation layer  150 . 
     Referring back to  FIG. 1A  and  FIG. 1B , the retaining mechanism  160  may include an insert  162  in the form of a strip of resilient material. The resilient material may include high tensile steel or any other suitable materials. According to various embodiments, the insert  162  in the form of the strip of resilient material may have a length longer than a distance, such as a transverse distance or a perpendicular distance, between the first receiving portion  130  and the second receiving portion  140  of the slat  110 . Accordingly, the insert  162  may have to be bent elastically prior to disposing the insert  162  on the insulation layer  150  until a direct distance between the two ends  164 ,  166  of the insert  162  is smaller than the distance between the first receiving portion  130  and the second receiving portion  140  of the slat  110 . Subsequently, when the insert  162  is disposed on insulation layer  150 , the force applied to bend the insert  162  may be removed such that the insert  162  may reverse the bending and try to return to the unbended state. Accordingly, the tendency of the insert  162  to unbend may cause the respective ends  164 ,  166  of the insert  162  to urge or press or push the corresponding portions of the insulation layer  150  into the respective first receiving portion  130  and the second receiving portion  140  of the slat  110 . 
     As shown in  FIG. 1A  and  FIG. 1B , the slat assembly  100  may further include a first pusher member  170 . The first pusher member  170  may be disposed between the first portion of the insulation layer  150  and the retaining mechanism  160  (for example the first end  164  of the insert  162 ). The first pusher member  170  may be aligned with the first receiving portion  130  (for example a first groove  134  of the pair of grooves  134 ,  144  as shown). Accordingly, the retaining mechanism  160  may urge or push or press the first pusher member  170  at a portion of the first pusher member  170  which may then be translated into the first pusher member  170  urging or pushing or pressing the first portion of the insulation layer  150  evenly against or into the entire length of the first receiving portion  130  of the slat  110 . According to various embodiments, the first pusher member  170  may include a bar with a V-shaped cross-section or a U-shaped cross-section or a horse-shoe shaped cross-section or any suitable cross-section that may be accommodated in the first receiving portion  130  of the slat  110 . 
     As shown in  FIG. 1A  and  FIG. 1B , the slat assembly  100  may further include a second pusher member  172 . Similarly, the second pusher member  172  may be disposed between the second portion of the insulation layer  150  and the retaining mechanism  160  (for example the second end  166  of the insert  162 ). The second pusher member  172  may be aligned with the second receiving portion  140  (for example a second groove  144  of the pair of grooves  134 ,  144  as shown). 
     Accordingly, the retaining mechanism  160  may urge or push or press the second pusher member  172  at a portion of the second pusher member  172  which may then be translated into the second pusher member  172  urging or pushing or pressing the second portion of the insulation layer  150  evenly against or into the entire length of the second receiving portion  140  of the slat  110 . According to various embodiments, the second pusher member  172  may include a bar with a V-shaped cross-section or a U-shaped cross-section or a horse-shoe shaped cross-section or any suitable cross-section that may be accommodated in the second receiving portion  140  of the slat  110 . 
       FIG. 2A  shows an exploded view of a slat assembly  200  for a roller shutter according to various embodiments.  FIG. 2B  shows an assembled view of the slat assembly  200  of  FIG. 2A  according to various embodiments. The slat assembly  200  of  FIG. 2A  and  FIG. 2B  differs from the slat assembly  100  of  FIG. 1A  and  FIG. 1B  in that the slat assembly  200  include two side covers  280 ,  282  (or end-clips) attached to respective ends  124 ,  126  of the slat  110 . Accordingly, one side cover may be attached to one end of the slat  110 . The side covers  280 ,  282  may be configured to cover or contain or enclose or conceal or wrap around respective edge portion of the insulation layer  150  along the respective ends  124 ,  126  of the slat  110 . Accordingly, the side covers  280 ,  282  may prevent the insulation layer  150  from sliding out of the slat  110  via either ends  124 ,  126  of the slat  110 . Further, the side cover  280 ,  282  may be a three-sided rigid pressed-steel component (with substantially U-shaped cross section) enclosing or concealing or covering the edge portions of the insulation layer  150  to protect the respective edge portions of the insulation layer  150  from scuffing or scraping against the guide rails or shutter guide channels while rolling and unrolling of the shutter curtain during shutter operation. Such scuffing or scraping of the insulation layer  150  may cause the respective edge portions of the fabric forming the insulation layer  150  to fray, which may in turn lead to unraveling of the fabric resulting in loose fibre threads etc. These loose fibre threads may be caught or entangled in the roller shutter assembly (for example, protrusions or projections or features that are jutting out) to cause further tearing of the insulation layer  150 . Thus, the side covers  280 ,  282  may minimize or prevent damage and fraying of the insulation layer  150  due to wear and tear by enclosing the respective edge portions of the insulation layer  150  and prevent the respective edge portions of the insulation blanket from coming into contact with the guide rails or shutter guide channels. According to various embodiments, the side-cover  280 ,  282  in the form of the three-sided rigid pressed-steel component may include a flat rectangular base portion  283  and a pair of wall portions  285 ,  287  extending perpendicularly from two longitudinal edges of the flat rectangular base portion  283 . Accordingly, the respective edge portions of the insulation layer  150  may be slotted or fitted in or inserted between the pair of wall portions  285 ,  287  and aligned to the base portion  283 . 
       FIG. 3A  shows a perspective view of a shutter curtain assembly  300  according to various embodiments.  FIG. 3B  shows a side view of the shutter curtain assembly  300  of  FIG. 3A  according to various embodiments.  FIG. 3C  shows an enlarged side view of a section of the shutter curtain assembly  300  of  FIG. 3A  according to various embodiments. According to various embodiments, shutter curtain assembly  300  may be a component of a roller shutter. As shown, the shutter curtain assembly  300  may include a plurality of slats  310  pivotally interlocked one after another in a series to form a shutter curtain. According to various embodiments, one slat may be joined to another slat along its length. Accordingly, multiple slats may be joined in sequence, one after another in a series, to form the shutter curtain. 
     As shown, the shutter curtain assembly  300  may further include an insulation layer  350  lined across at least two adjacent pivotally interlocked slats of the plurality of slats  310 . According to various embodiments, the insulation layer  350  may be sized to line across a desired number of slats  310 . According to various embodiments, the insulation layer  350  may also be sized to line across the entire shutter curtain made up of the plurality of slats  310 . According to various embodiments, the insulation layer  350  may be formed by stitching or joining multiple pieces. According to various embodiments the insulation layer  350  may be weaved as a single piece. 
     According to various embodiments, the shutter curtain assembly  300  may further include at least one retaining mechanism  360  disposed on the insulation layer  350  to urge or press or push a portion of the insulation layer  350  against a first receiving portion  330  of one of the at least two adjacent pivotally interlocked slats  310  and to urge or press or push a further portion of the insulation layer  350  against a second receiving portion of the one of the at least two adjacent pivotally interlocked slats  310  such that the at least one retaining mechanism  360  may cooperate with the first receiving portion  330  and the second receiving portion  340  of the one of the at least two adjacent pivotally interlocked slats  310  to hold or clamp or grip or clench the insulation layer  350  between the retaining mechanism  360  and the at least two adjacent pivotally interlocked slats  350  without puncturing or penetrating the insulation layer  350 . The retaining mechanism  360  may, similar to the retaining mechanism  160  of  FIG. 1A  and  FIG. 1B , include a first end configured for urging or pressing or pushing the first portion of the insulation layer  350  against the first receiving portion  330  of the slat  310 . The retaining mechanism  360  may, similar to the retaining mechanism  160  of  FIG. 1A  and  FIG. 1B , also include a second end configured for urging or pressing or pushing the second portion of the insulation layer  350  against the second receiving portion  340  of the slat  310 . 
     As shown in  FIG. 3A  and  FIG. 3B , the shutter curtain assembly  300  may include one or two or more or a plurality of retaining mechanisms  360 . Further, each slat  310  of the plurality of slats  310  may also include respective first receiving portion  330  and second receiving portion  340 . Accordingly, the insulation layer  350  may be lined across the plurality of slats  310  and corresponding portions of the insulation layer  350  may be hold or clamp or grip or clench between the respective retaining mechanism  360  and the respective slat  310 . 
     Similar to the slat assembly  100  of  FIG. 1A  and  FIG. 1B , the first receiving portion  330  and the second receiving portion  340  of the slat  310  may be a pair of parallel opposing grooves which may be a pair of bent portions of the slat  310 . Further, the at least one retaining mechanism  360  may be pre-loaded to supply an expansion force for biasing the first end and the second end of the retaining mechanism  360  away from each other so as to urge or press or push the respective portions of the insulation layer against the respective first receiving portion  330  and second receiving portion  340  of the respective slat  310 . The at least one retaining mechanism  360  may also be configured to press respective portions of the insulation layer  350  into the respective first receiving portion  330  and second receiving portion  340  of the respective slat  310 . Furthermore, the retaining mechanism  360  may be an insert  362  in the form of a strip of resilient material which has a length longer than a distance between the respective first receiving portion  330  and second receiving portion  340  of the respective slat. In addition, the insulation layer  350  may include a layer of insulation wool sandwiched between two layers of insulation cloths. According to various embodiments, the insulation wool may include ceramic fiber wool or rock wool etc. According to various embodiments, the insulation cloth may include silica fabric or fibre-glass fabric etc. 
     According to various embodiments, the shutter curtain assembly  300  may further include at least one pusher member  370 . The at least one pusher member  370  may be disposed between the insulation layer  350  and the at least one retaining mechanism  360 . The at least one pusher member  370  may be aligned with one of the first receiving portion  330  or the second receiving portion  340  (for example a groove of the pair of parallel opposing grooves) of at least one slat  310 . The at least one pusher member  370  may include a bar with a V-shaped cross-section or a U-shaped cross-section or horse-shoe shaped cross-section or any suitable cross-section for accommodating in the respective receiving portions  330 ,  340  of the slat  310 . 
     As shown in  FIG. 3A  and  FIG. 3B , the shutter curtain assembly  300  may include one or two or more or a plurality of pusher members  370 . According to various embodiments, there may be two pusher members  370  aligned to the two receiving portions  330 ,  340  of each slat  310 . Accordingly, respective retaining mechanism  360  may urge or press or push the respective two pusher members  370  such that corresponding portions of the insulation layer  350  may be urged or pressed or pushed into the respective receiving portions  330 ,  340  of each slat  310  so as to be held or clamp or grip or clench between the respective pusher member  370  and the respective receiving portion  330 ,  340  of the slat  310 . 
       FIG. 4  shows a perspective view of a shutter curtain assembly  400  according to various embodiments. The shutter curtain assembly  400  of  FIG. 4  differs from the shutter curtain assembly  300  of  FIG. 3A  and  FIG. 3B  in that the shutter curtain assembly  400  may include at least two side covers  480  attached to respective ends of at least one slat  310 . As shown in  FIG. 4 , the shutter curtain assembly  400  may include a plurality of side covers such that one side cover  480  is attached to one end of each slat  310 . 
       FIG. 5A  shows a side cross-sectional view of an upper portion  502  of a vertical roller shutter  500  according to various embodiments.  FIG. 5B  shows a side cross-sectional view of a lower portion  504  of the vertical roller shutter  500 , when in a lowered state, according to various embodiments. As shown, the vertical roller shutter  500  may include a pair of shutter curtain assemblies  506 ,  508 . The vertical roller shutter  500  may be configured such that the pair of shutter curtain assemblies  506 ,  508  may be raised up and lowered down vertically. Accordingly, when in the lowered state, the pair of shutter curtain assemblies  506 ,  508  may be spaced apart and parallel to each other such that the pair of shutter curtain assemblies  506 ,  508  may be facing each other. According to various embodiments, each of the pair of shutter curtain assemblies  506 ,  508  may be the shutter curtain assembly  300  of  FIG. 3A  &amp;  FIG. 3B , and/or the shutter curtain assembly  400  of  FIG. 4 . According to various embodiments, the respective insulating layers of the respective shutter curtain assemblies  506 ,  508  may be lined on respective surfaces of the respective shutter curtain assemblies  506 ,  508  such that they are facing each other. According to various embodiments, a first shutter curtain assembly  506  of the pair of shutter curtain assemblies may be coupled to a first drum  507  with the plurality of slats of the first shutter curtain assembly  506  arranged at least substantially parallel to a longitudinal axis of the first drum  507  such that the first shutter curtain assembly  506  may be rolled on and off the first drum  507 . Similarly, a second shutter curtain assembly  508  of the pair of shutter curtain assemblies may be coupled to a second drum  509  with the plurality of slats of the second shutter curtain assembly  508  arranged at least substantially parallel to a longitudinal axis of the second drum  509  such that the second shutter curtain assembly  508  may be rolled on and off the second drum  509 . 
     The roller shutter  500  may further include a housing  503  configured to be mounted to a wall or a beam or an overhanging structure. The housing  503  may be configured to enclose the pair of drums  507 ,  509  and a motor assembly  505 . The motor assembly  505  and the pair of drums  507 ,  509  may be arranged such that the motor assembly  505  may drive the rotation of the pair of drums  507 ,  509  synchronously. For example, as shown, the pair of drums  507 ,  509  and the motor assembly  505  may be arranged in a lateral arrangement (or horizontally) with their rotational axes lying on a horizontal plane. In this arrangement, a belt or a chain mechanism may couple the pair of drums  507 ,  509  to the motor assembly  505  such that the motor assembly  505  may simultaneous drive the rotation of both the drums  507 ,  509  in a coordinated manner to roll in or roll out both the shutter curtain assemblies  506 ,  508  at the same time in a synchronized manner. Accordingly, the motor assembly  505  may drive both the drums  507 ,  509  to rotate in a same first direction (for example, clockwise direction from the view as shown in  FIG. 5A ) for rolling in both the shutter curtain assemblies  506 ,  508 , and drive both the drums  507 ,  509  to rotate in a same second direction (for example, anti-clockwise direction from the view as shown in  FIG. 5A ) for rolling out both the shutter curtain assemblies  506 ,  508 . 
     Further, according to various embodiments, guide rails  599  (or shutter guide channels) may be provided along the sides of the wall, which the roller shutter  500  may be mounted to, such that the side edges of the pair of shutter curtain assemblies  506 ,  508  may be inserted or slotted or placed into the guide rails  599  (or shutter guide channels) so as to be raised up or lowered down in a guided manner. 
     In  FIG. 5B , the lower portion  504  of the pair of shutter curtain assemblies  506 ,  508  is shown. The first shutter curtain assembly  506  may have a foot component  590  connected to the last slat of the first shutter curtain assembly  506 . The second shutter curtain assembly  508  may also have a foot component  592  connected to the last slat of the second shutter curtain assembly  508 . The respective foot components  590 ,  592  of the respective shutter curtain assemblies  506 ,  508  may have a substantively ‘inverted-T’ shape cross-section. Accordingly, each foot component  590 ,  592  may have a lateral base portion  591 ,  593  and a connecting portion  594 ,  595  extending perpendicularly from a middle or centerline or longitudinal axis of the respective lateral base portion  591 ,  593 . As shown, a longitudinal edge portion of the respective connecting portions  594 ,  595  of the respective foot components  590 ,  592  may be curled inwardly towards the respective lateral base portion  591 ,  593  to form respective curled edge portions  594 ′,  595 ′ so as to engage with the outward curled edge portion of the last slat of the respective shutter curtain assemblies  506 ,  508 . 
     As shown in  FIG. 5B , according to an example implementation, the foot component  590 ,  592  may include two elongated L-shaped bars, wherein the vertical portions of the respective elongated L-shaped bars are arranged back-to-back. Further, the foot component  590 ,  592  may include a half-slat element with an inwardly curled portion along one of the longitudinal edge and a flat portion along the other longitudinal edge. Accordingly, the flat portion of the half-slat element may be sandwiched between the vertical portions of the respective elongated L-shaped bars and joined together to form the respective foot components  590 ,  592 . The joining may be via bolt and nut or any other suitable fasteners. 
     According to various embodiments, the insulating layer of the respective shutter curtains  506 ,  508  may also extend over and cover the connecting portions  594 ,  595  of the respective foot components  590 ,  592 . Accordingly, the respective connecting portions  594 ,  595  of the respective foot components  590 ,  592  may be lined with the respective insulating layers. According to various embodiments, the foot components  590 ,  592  of the pair of shutter curtain assemblies  506 ,  508  may include an insulating seal arrangement to seal a gap between the foot component  590  of the first shutter curtain assembly  506  and the foot component  592  of the second shutter curtain assembly  508 . 
     For example, as shown in  FIG. 5B , each of the foot components  590 ,  592  may further include an insulating block  596 ,  598  laid on the respective lateral base portions  591 ,  593 . According to various embodiments, the insulating block  596 ,  598  may be laid on the part of the respective lateral base portions  592 ,  593  that is extending towards the other shutter curtain assemblies  506 ,  508 . As shown, the insulating block  596  of the foot component  590  of the first shutter curtain assembly  506  may be laid on the part of the lateral base portion  591  extending towards the second shutter curtain assembly  508 . Similarly, the insulating block  598  of the foot component  592  of the second shutter curtain assembly  508  may be laid on the part of the lateral base portion  593  extending towards the first shutter curtain assembly  506 . 
     According to various embodiments, an overlapping insulating block  597  may be attached to either the insulating block  596  of the foot component  590  of the first shutter curtain assembly  506  or the insulating block  598  of the foot component  592  of the second shutter curtain assembly  508 . In this configuration, the overlapping insulating block  597  may seal off a gap between the foot component  590  of the first shutter curtain assembly  506  and the foot component  592  of the second shutter curtain assembly  508 . Accordingly, an enclosed void or space between the first shutter curtain assembly  506  and the second shutter curtain assembly  508  may be insulated to form an insulating air gap which may enhance the fire insulation of the roller shutter  500 . 
       FIG. 6  shows a side cross-sectional view of an upper portion  602  of a vertical roller shutter  600  according to various embodiments. The vertical roller shutter  600  of  FIG. 6  differs from the vertical roller shutter  500  of  FIG. 5A  in that the first drum  607  of the first shutter curtain assembly  606  of roller shutter  600  may be driven by a first motor  605  and the second drum  609  of the second shutter curtain assembly  608  may be driven by a second motor  605 ′. Accordingly, in this configuration, the first drum  607  and the second drum  609  may be arranged such that the first drum  607  may be above the second drum  609  within the housing  603 . Hence, the space between the first shutter curtain assembly  606  and the second shutter curtain assembly  608 , when in the lowered state, may be reduced as compared to the vertical roller shutter  500  of  FIG. 5A . As shown, the first motor  605  may drive the first drum  607  of the first shutter curtain assembly  606  of roller shutter  600  in a first direction (for example, clockwise direction from the view as shown in  FIG. 6 ) for rolling in the first shutter curtain assembly  606 , and the second motor  605 ′ may drive the second drum  609  of the second shutter curtain assembly  608  of roller shutter  600  in the same first direction (for example, clockwise direction from the view as shown in  FIG. 6 ) for rolling in the second shutter curtain assembly  608 . Further, the first motor  605  may drive the first drum  607  of the first shutter curtain assembly  606  of roller shutter  600  in a second direction (for example, anti-clockwise direction from the view as shown in  FIG. 6 ) for rolling out the first shutter curtain assembly  606 , and the second motor  605 ′ may drive the second drum  609  of the second shutter curtain assembly  608  of roller shutter  600  in the same second direction (for example, anti-clockwise direction from the view as shown in  FIG. 6 ) for rolling out the second shutter curtain assembly  608 . In addition, the first motor  605  and the second motor  605 ′ may simultaneous drive the rotation of both the drums  607 ,  609  in a coordinated manner to roll in or roll out both the shutter curtain assemblies  606 ,  608  at the same time in a synchronized manner. 
       FIG. 7  shows a top cross-sectional view of a lateral roller shutter  700  according to various embodiments. The lateral roller shutter  700  of  FIG. 7  differs from the vertical roller shutters  500  of  FIG. 5A  and the roller shutter  600  of  FIG. 6  in that the pair of shutter curtain assemblies  706 ,  708  of the lateral roller shutter  700  are arranged to be rolled in and out sideways instead of up and down. Accordingly, the respective drums  707 ,  709  and motors may be arranged with their respective rotational axis in a vertical orientation. Further, the lateral ends of the pair of shutter curtain assemblies  706 ,  708  may also differ from the foot components  590 ,  592  of the vertical roller shutter  500  of  FIG. 5A  in that the lateral ends of the pair of shutter curtain assemblies  706 ,  708  may be joined together by an insulating block  796 . Furthermore, on the wall which the lateral roller shutter  700  closes, a striker  796 ′ with recess to receive the insulating block may be provided. 
       FIG. 8  shows a top cross-sectional view of a lateral roller shutter  800  according to various embodiments. The lateral roller shutter  800  of  FIG. 8  differs from the lateral roller shutter  700  of  FIG. 7  in that two pairs of shutter curtain assemblies  806 ,  808 ,  806 ′,  808 ′ are provided. The first pair of shutter curtain assemblies  806 ,  808  may be arranged to close sideways from left to right, and the second pair of shutter curtain assemblies  806 ′,  808 ′ may be arranged to close sideways from right to left. The first pair of shutter curtain assemblies  806 ,  808  may, similar to the pair of shutter curtain assemblies  706 ,  708  of  FIG. 7 , include an insulating block  896  joining the lateral ends of the pair of shutter curtain assemblies  806 ,  808 . On the other hand, the second pair of shutter curtain assemblies  806 ′,  808 ′ may include a latch  896 ′ configured to receive the joined lateral ends of the first pair of shutter curtain assemblies  806 ,  808 . The latch  896 ′ may include one or more insulating blocks  897 ,  898  between the jaws of the latch  896 ′. 
       FIG. 9  shows a schematic side view of an upper portion  902  of a vertical roller shutter  900  according to various embodiments. As shown, the vertical roller shutter  900  may include a pair of shutter curtain assemblies  906 ,  908 . The vertical roller shutter  900  may be configured such that the pair of shutter curtain assemblies  906 ,  908  may be raised up and lowered down vertically. Accordingly, when in the lowered state, the pair of shutter curtain assemblies  906 ,  908  may be spaced apart and parallel to each other such that the pair of shutter curtain assemblies  906 ,  908  may be facing each other. According to various embodiments, each of the pair of shutter curtain assemblies  906 ,  908  may be the shutter curtain assembly  300  of  FIG. 3A  &amp;  FIG. 3B , and/or the shutter curtain assembly  400  of  FIG. 4 . According to various embodiments, the respective insulating layers of the respective shutter curtain assemblies  906 ,  908  may be lined on respective surfaces of the respective shutter curtain assemblies  906 ,  908  such that they are facing each other. According to various embodiments, the vertical roller shutter  900  of  FIG. 9  differs from the vertical roller shutter  500  of  FIG. 5A  in that the vertical roller shutter  900  of  FIG. 9  includes two counter-rotating drums  907 ,  909  arranged side-by-side. Accordingly, the first shutter curtain assembly  906  may be attached to and wound round the first counter-rotating drum  907  in a first direction (for example, wound round in a clockwise direction) and the second shutter curtain assembly  908  may be attached to and wound round the second counter-rotating drum  909  in a second direction (for example, wound round in an anti-clockwise direction). The first direction and the second direction are opposite directions. Hence, in this configuration, the first and second counter-rotating drums  907 ,  909  may be configured to rotate in a first set of opposite directions (for example, the first drum  907  in clockwise direction and the second drum  909  in anti-clockwise direction) for rolling in both the shutter curtain assemblies  906 ,  908 . Further, both the first and second counter-rotating drums  907 ,  909  may rotate in a second set of opposite directions (for example, the first drum  907  in anti-clockwise direction and the second drum  909  in clockwise direction) for rolling out both the shutter curtain assemblies  906 ,  908 . According to various embodiments, the vertical roller shutter  900  may include a roller  901  disposed below the first drum  907 . Accordingly, the second shutter curtain assembly  908  on the second drum  909  may run from the second drum  909  and around the roller  901  such that a space between the first shutter curtain assembly  906  and the second shutter curtain assembly  908 , when in the lowered state, may be reduced as compared to the vertical roller shutter  500  of  FIG. 5A . 
       FIG. 10A  and  FIG. 10B  show a front view and a cross-sectional side view of the vertical roller shutter  900 , in a lowered state, according to various embodiments.  FIG. 10C  shows the positions of motor assemblies  905   a ,  905   b  from a top view of the vertical roller shutter  900  according to various embodiments.  FIG. 10D  shows a photograph of an actual implementation of the vertical roller shutter  900  according to various embodiments. As shown, the vertical roller shutter  900  may include two motor assemblies  905   a ,  905   b  arranged in a housing  903  (or a door head section) of the vertical roller shutter  900 . The first motor assembly  905   a  may be on one end of the housing  903  of the vertical roller shutter  900  and the second motor assembly  905   b  may be on an opposite end of the housing  903  of the vertical roller shutter  900 . According to various embodiments, the first motor assembly  905   a  may be configured to drive the first drum  907  and the second motor assembly  905   b  may be configured to drive the second drum  909 . According to various embodiments, a belt or a chain mechanism may couple each of the drums  907 ,  909  to the respective motor assemblies  905   a ,  905   b . According to various embodiments, the first and second motor assemblies  905   a ,  905   b  may be configured to simultaneously drive the rotation of both the drums  907 ,  909  in a coordinated manner to roll in or roll out both the shutter curtain assemblies  906 ,  908  at the same time in a synchronized manner. 
       FIG. 11A  shows a schematic side view of an upper portion  1102  of a vertical roller shutter  1100  according to various embodiments.  FIG. 11B  shows a photograph of an actual implementation of the vertical roller shutter  1100  according to various embodiments. As shown, the vertical roller shutter  1100  may include a pair of shutter curtain assemblies  1106 ,  1108 . The vertical roller shutter  1100  may be configured such that the pair of shutter curtain assemblies  1106 ,  1108  may be raised up and lowered down vertically. Accordingly, when in the lowered state, the pair of shutter curtain assemblies  1106 ,  1108  may be spaced apart and parallel to each other such that the pair of shutter curtain assemblies  1106 ,  1108  may be facing each other. According to various embodiments, each of the pair of shutter curtain assemblies  1106 ,  1108  may be the shutter curtain assembly  300  of  FIG. 3A  &amp;  FIG. 3B , and/or the shutter curtain assembly  400  of  FIG. 4 . According to various embodiments, the respective insulating layers of the respective shutter curtain assemblies  1106 ,  1108  may be lined on respective surfaces of the respective shutter curtain assemblies  1106 ,  1108  such that they are facing each other. According to various embodiments, the vertical roller shutter  1100  may include one single drum  1107 . Accordingly, both the first shutter curtain assembly  1106  and the second shutter curtain assembly  1108  may be attached to and wound round the drum  1107 . The first shutter curtain assembly  1106  and the second shutter curtain assembly  1108  may be arranged such that the respective insulating layers are facing each other when both the first shutter curtain assembly  1106  and the second shutter curtain assembly  1108  are wound round the drum  1107 . According to various embodiments, the first shutter curtain assembly  1106  and the second shutter curtain assembly  1108  may be attached to the drum  1107  in a manner such that both the shutter curtain assemblies  1106 ,  1108  may be rolled in or rolled out at the same time in a synchronized manner. According to various embodiments, the first shutter curtain assembly  1106  and the second shutter curtain assembly  1108  may be attached to the drum  1107  in a staggered manner (for example, at different positions along a circumference of the drum  1107  one after another) to facilitate rolling in or rolling out in a synchronized manner. 
     According to various embodiments, the vertical roller shutter  1100  may include a motor assembly  1105 . According to various embodiments, a belt or a chain mechanism may couple the drum  1107  to the motor assembly  1105  such that the motor assembly  1105  may drive the rotation of the drums  1107  to roll in or roll out both the shutter curtain assemblies  1106 ,  1108  at the same time in a synchronized manner. Accordingly, the motor assembly  1105  may drive the drum  1107  to rotate in a first direction (for example, clockwise direction) for rolling in both the shutter curtain assemblies  1106 ,  1108 , and drive the drum  1107  to rotate in a second direction (for example, anti-clockwise direction) for rolling out both the shutter curtain assemblies  1106 ,  1108 . 
       FIG. 12A  shows a top cross-sectional view of a lateral roller shutter  1200   a  according to various embodiments. The lateral roller shutter  1200   a  of  FIG. 12A  differs from the lateral roller shutters  700  of  FIG. 7  in that the lateral roller shutter  1200  includes only one single drum  1207  on which the two curtain assemblies  1206  and  1208  are attached in a manner so as to be rolled in and out sideways. The other components of the lateral roller shutter  1200  is the same as that of the lateral roller shutters  700  of  FIG. 7 . 
       FIG. 12B  shows a top cross-sectional view of a lateral roller shutter  1200   b  according to various embodiments. The lateral roller shutter  1200   b  of  FIG. 12B  differs from the lateral roller shutter  1200   a  of  FIG. 12A  in that two pairs of shutter curtain assemblies  1206 ,  1208 ,  1206 ′,  1208 ′ are provided. The first pair of shutter curtain assemblies  1206 ′,  1208 ′ is provided on a first drum  1207 ′. The second pair of shutter curtain assemblies  1206 ,  1208  is provided on a second drum  1207 . The first pair of shutter curtain assemblies  1206 ′,  1208 ′ may be arranged to close sideways from left to right by rotating the first drum  1207 ′ in a first direction (for example, a clockwise direction from the view as shown in  FIG. 12B ), and the second pair of shutter curtain assemblies  1206 ,  1208  may be arranged to close sideways from right to left by rotating the second drum  1207  in a second direction (for example, an anti-clockwise direction from the view as shown in  FIG. 12B ). The second pair of shutter curtain assemblies  1206 ,  1208  of  FIG. 12B  may be similar to the pair of shutter curtain assemblies  1206 ,  1208  of  FIG. 12A . 
       FIG. 13  shows a schematic side view of an upper portion  1302  of a vertical roller shutter  1300  according to various embodiments. The vertical roller shutter  1300  of  FIG. 13  is similar to the vertical roller shutter  1100  of  FIG. 11A  except that the vertical roller shutter  1300  includes three shutter curtain assemblies  1306   a ,  1306   b ,  1308 , attached to and wound round one single drum  1307 .  FIG. 14A  shows a top cross-sectional view of a lateral roller shutter  1400   a  according to various embodiments. The lateral roller shutter  1400   a  of  FIG. 14A  is similar to the lateral roller shutter  1200  a of  FIG. 12A  except that the lateral roller shutter  1400   a  of  FIG. 14A  includes three shutter curtain assemblies  1406   a ,  1406   b ,  1408 , attached to and wound round one single drum  1407 .  FIG. 14B  shows a top cross-sectional view of a lateral roller shutter  1400   b  according to various embodiments. The lateral roller shutter  1400   b  of  FIG. 14B  is similar to the lateral roller shutter  1200   b  of  FIG. 12B  except that the lateral roller shutter  1400   b  includes two sets of three shutter curtain assemblies  1406   a ,  1406   b ,  1408 ,  1406   a ′,  1406   b ′,  1408 ′, wherein each set of three shutter curtain assemblies is attached to and wound round one single drum  1407 ,  1407 ′. 
       FIG. 15A  and  FIG. 15B  show side views of two slats  1510   a ,  1510   b  pivotably interlocked to each other in a suspended mode and in a stacked mode respectively according to various embodiments.  FIG. 15C  and  FIG. 15D  shows perspective views of the two slats  1510   a ,  1510   b  in the suspended mode and in the stacked mode respectively according to various embodiments. According to various embodiments, interlocking elements of each slat  1510   a ,  1510   b  may be configured such that some lateral leeway (or freedom of lateral movement or side-way movement) may be provided when two slats  1510   a ,  1510   b  are pivotably interlocked to each other in a side-by-side manner. Accordingly, the lateral leeway may allow the two slats  1510   a ,  1510   b  to be extended laterally from each other while remaining interlocked in the suspended mode. The lateral leeway may also allow the two slats  1510   a ,  1510   b  to close in laterally on each other while being interlocked so as to be stacked together in the stacked mode. According to various embodiments, lateral leeway may be freedom of movements allowed in a direction perpendicular to respective longitudinal axis of the respective slat. 
     As shown, each of the slat  1510   a ,  1510   b  may, similar to the slat  110  of  FIG. 1C  and  FIG. 1D , include a main portion  1512   a ,  1512   b  between a first longitudinal edge portion  1514   a ,  1514   b  and a second longitudinal edge portion  1516   a ,  1516   b . Accordingly, the main portion  1512   a  of the slat  1510   a  may be the main body of the slat  1510   a  for lining abreast or placing side by side with the main portion  1512   b  of the adjacent slat  1510   b  so as to form a shutter curtain. According to various embodiments, a shutter curtain assembly may include a plurality of slats  1510   a ,  1510   b  pivotally interlocked one after another. 
     As shown, each of the slat  1510   a ,  1510   b  may include a first receiving portion  1530   a ,  1530   b  which may be an inward bend  1532   a ,  1532   b  (or inward fold) at the first longitudinal edge portion  1514   a ,  1514   b  of the respective slat  1510   a ,  1510   b . According to various embodiments, each slat  1510   a ,  1510   b  may be formed or shaped or profiled or made or molded or pressed from an elongated sheet of material, such as an elongated sheet of metal. Accordingly, the inward bend  1532   a ,  1532   b  at the first longitudinal edge portion  1514   a ,  1514   b  may be formed from bending or folding a first longitudinal edge  1513   a ,  1513   b  of the sheet of material lengthwise inwardly towards a longitudinal axis  1511   a ,  1511   b  of the respective slat  1510   a ,  1510   b . Hence, the inward bend  1532   a ,  1532   b  may be immediately adjacent to the main portion  1512   a ,  1512   b  of the respective slat  1510   a ,  1510   b . As shown, a first elongate overhang portion  1531   a ,  1531   b  of the respective slat  1510   a ,  1510   b  may extend laterally from the inward bend  1532   a ,  1532   b  of the first longitudinal edge portion  1514   a ,  1514   b  such that the first elongate overhang portion  1531   a ,  1531   b  of the respective slat  1510   a ,  1510   b  may be angled less than 90° with respect to the main portion  1512   a ,  1512   b  of the respective slat  1510   a ,  1510   b . Accordingly, the first elongate overhang portion  1531   a ,  1531   b  of the respective slat  1510   a ,  1510   b  and the main portion  1512   a ,  1512   b  of the respective slat  1510   a ,  1510   b  may form a groove with a V-shaped or U-shaped or a horse-shoe-shaped cross-section, and the inward bend  1532   a ,  1532   b  of the first longitudinal edge portion  1514   a ,  1514   b  of the respective slat  1510   a ,  1510   b  may be of an acute angle. 
     As shown, each of the slat  1510   a ,  1510   b  may include a second receiving portion  1540   a ,  1540   b  which may be an inward bend  1542   a ,  1542   b  (or inward fold) at a second longitudinal edge portion  1516   a ,  1516   b  of the respective slat  1510   a ,  1510   b . According to various embodiments, the inward bend  1542   a ,  1542   b  at the second longitudinal edge portion  1516   a ,  1516   b  may be formed from bending or folding a second longitudinal edge  1515   a ,  1515   b  of the sheet of material lengthwise inwardly towards the longitudinal axis  1511   a ,  1511   b  of the respective slat  1510   a ,  1510   b . Accordingly, the inward bend  1542   a ,  1542   b  may be immediately adjacent to the main portion  1512   a ,  1512   b  of the respective slat  1510   a ,  1510   b . As shown, a second elongate overhang portion  1541   a ,  1541   b  of the respective slat  1510   a ,  1510   b  may extend laterally from the inward bend  1542   a ,  1542   b  of the second longitudinal edge portion  1516   a ,  1516   b . As shown, a first segment  1541   a ′,  1541   b ′ of the second elongate overhang portion  1541   a ,  1541   b  may extend laterally from the inward bend  1542   a ,  1542   b  of the second longitudinal edge portion  1516   a ,  1516   b  such that the first segment  1541   a ′,  1541   b ′ of the second elongate overhang portion  1541   a ,  1541   b  of the respective slat  1510   a ,  1510   b  may be angled less than 90° with respect to the main portion  1512   a ,  1512   b  of the respective slat  1510   a ,  1510   b . Further, a second segment  1541   a ″,  1541   b ″ of the second elongate overhang portion  1541   a ,  1541   b  may extend laterally from the first segment  1541   a ′,  1541   b ′ of the second elongate overhang portion  1541   a ,  1541   b  such that the second segment  1541   a ″,  1541   b ″ of the second elongate overhang portion  1541   a ,  1541   b  may be angled between 90° to 180° (or form an obtuse angle) with respect to the first segment  1541   a ′,  1541   b ′ of the second elongate overhang portion  1541   a ,  1541   b  of the respective slat  1510   a ,  1510   b . Accordingly, the first segment  1541   a ′,  1541   b ′ of the second elongate overhang portion  1541   a ,  1541   b  of the slat  1510   a ,  1510   b  and the main portion  1512   a ,  1512   b  of the respective slat  1510   a ,  1510   b  may form a groove with a V-shaped or U-shaped or horse-shoe-shaped cross-section, and the inward bend  1542   a ,  1542   b  of the second longitudinal edge portion  1516   a ,  1516   b  of the respective slat  1510   a ,  1510   b  may of an acute angle. According to various embodiments, the second segment  1541   a ″,  1541   b ″ of the second elongate overhang portion  1541   a ,  1541   b  may be parallel to the main portion  1512   a ,  1512   b  of the respective slat  1510   a ,  1510   b.    
     As shown, the pair of inward bends  1532   a ,  1542   a ,  1532   b ,  1542   b  at the respective first longitudinal edge portion  1514   a ,  1514   b  and the second longitudinal edge portion  1516   a ,  1516   b  may extend through the entire length of the respective slat  1510   a ,  1510   b  and may be at least substantially parallel to each other. According to various other embodiments, the inward bend at the first longitudinal edge portion and the inward bend at the second longitudinal edge portion may extend along only a portion of the length of the respective slat. According to various other embodiments, the pair of inward bends may also be non-parallel to each other. 
     According to various embodiments, the inward bend  1532   a ,  1532   b  at the first longitudinal edge portion  1514   a ,  1514   b  and the inward bend  1542   a ,  1542   b  at the second longitudinal edge portion  1516   a ,  1516   b  may form a pair of grooves  1534   a ,  1544   a ,  1534   b ,  1544   b  which may be opposing each other and which may have a V-shaped or U-shaped or a horse-shoe-shaped cross-section. Accordingly, the pair of grooves  1534   a ,  1544   a ,  1534   b ,  1544   b  may be a pair of inwardly bent portions (or folded portions) of the respective slat  1510   a ,  1510   b . Each of the pair of inwardly bent portions of the respective slat  1510   a ,  1510   b  may be formed from bending inwardly towards the longitudinal axis of the respective slat  1510   a ,  1510   b  so as to form the acute angle. 
     As shown in  FIG. 15A  and  FIG. 15B , the inward bend  1532   a ,  1532   b  at the first longitudinal edge portion  1514   a ,  1514   b  of the respective slat  1510   a ,  1510   b  may be followed by an outward bend  1518   a ,  1518   b  (or outward fold) formed from subsequent bending or folding of the first longitudinal edge  1513   a ,  1513   b  of the elongated sheet of material lengthwise away from the longitudinal axis  1511   a ,  1511   b  of the respective slat  1510   a ,  1510   b . Accordingly, from the first elongate overhang portion  1531   a ,  1531   b , the sheet of material may be bent or folded outwardly away from the longitudinal axis  1511   a ,  1511   b  of the respective slat  1510   a ,  1510   b  to form the outward bend  1518   a ,  1518   b . As shown, a first elongate winged-like portion  1519   a ,  1519   b  of the respective slat  1510   a ,  1510   b  may extend laterally from the outward bend  1518   a ,  1518   b . A first segment  1519   a ′,  1519   b ′ of the first elongate winged-like portion  1519   a ,  1519   b  of the respective slat  1510   a ,  1510   b  may extend laterally from the outward bend  1518   a ,  1518   b  such that the first segment  1519   a ′,  1519   b ′ of the first elongate winged-like portion  1519   a ,  1519   b  of the respective slat  1510   a ,  1510   b  may be angled less than 90° with respect to the first elongate overhang portion  1531   a ,  1531   b  of the respective slat  1510   a ,  1510   b . Accordingly, a first segment  1519   a ′,  1519   b ′ of the first elongate winged-like portion  1519   a ,  1519   b  of the respective slat  1510   a ,  1510   b  and the first elongate overhang portion  1531   a ,  1531   b  of the respective slat  1510   a ,  1510   b  may form a V-shaped or U-shaped cross-section, and the outward bend  1518   a ,  1518   b  of the first longitudinal edge portion  1514   a ,  1514   b  of the respective slat  1510   a ,  1510   b  may be of an acute angle. Further, a second segment  1519   a ″,  1519   b ″ of the first elongate winged-like portion  1519   a ,  1519   b  of the respective slat  1510   a ,  1510   b  may extend laterally from the first segment  1519   a ′,  1519   b ′ of the first elongate winged-like portion  1519   a ,  1519   b  such that the second segment  1519   a ″,  1519   b ″ of the first elongate winged-like portion  1519   a ,  1519   b  may be angled between 90° to 180° (or form an obtuse angle) with respect to the first segment  1519   a ′,  1519   b ′ of the first elongate winged-like portion  1519   a ,  1519   b  of the respective slat  1510   a ,  1510   b.    
     According to various embodiments, the first elongate winged-like portion  1519   a ,  1519   b  of the first longitudinal edge portion  1514   a ,  1514   b  of the respective slat  1510   a ,  1510   b  may be followed by an inward curl  1520   a ,  1520   b  formed from subsequent curling of the first longitudinal edge  1513   a ,  1513   b  of the elongated sheet of material lengthwise inwardly towards the longitudinal axis  1511   a ,  1511   b  of the respective slat  1510   a ,  1510   b . Accordingly, from the first elongate winged-like portion  1519   a ,  1519   b  of the slat  1510   a ,  1510   b , the sheet of material may be curled inwardly towards the longitudinal axis  1511   a ,  1511   b  of the respective slat  1510   a ,  1510   b . Hence, the inward curl  1520   a ,  1520   b  may form a first curled edge portion of the respective slat  1510   a ,  1510   b . The first curled edge portion of the respective slat  1510   a ,  1510   b  may be a first interlocking element of the respective slat  1510   a ,  1510   b . Accordingly, the first curled edge portion of the first slat  1510   a , may be configured for engaging, interlocking, or interacting with a corresponding interlocking element of the second slat  1510   b  to pivotably join the two slats  1510   a ,  1510   b  together. According to various embodiments, the first longitudinal edge portion  1514   a ,  1514   b  of the respective slat  1510   a ,  1510   b  may include the inward bend  1532   a ,  1532   b , the first elongate overhang portion  1531   a ,  1531   b , the outward bend  1518   a ,  1518   b , the first elongate winged-like portion  1519   a ,  1519   b , and the inward curl  1520   a ,  1520   b.    
     Further, as also shown, the second elongate overhang portion  1541   a ,  1541   b  at the second longitudinal edge portion  1516   a ,  1516   b  of the respective slat  1510   a ,  1510   b  may be followed by an at least substantially semi-circular outward curl  1522   a ,  1522   b  formed from subsequent curling of the second longitudinal edge  1515   a ,  1515   b  of the elongated sheet of material lengthwise outwardly away from the longitudinal axis  1511   a ,  1511   b  of the respective slat  1510   a ,  1510   b . Accordingly, from the second elongate overhang portion  1541   a ,  1541   b , the sheet of material may be curled outwardly away in a semi-circular manner from the longitudinal axis  1511   a ,  1511   b  of the respective slat  1510   a ,  1510   b  to form the semi-circular outward curl  1522   a ,  1522   b . Further, a second elongate winged-like portion  1521   a ,  1521   b  of the respective slat  1510   a ,  1510   b  may extend laterally from the semi-circular outward curl  1522   a ,  1522   b  such that the second elongate winged-like portion  1521   a ,  1521   b  may be parallel to the main portion  1512   a ,  1512   b  of the respective slat  1510   a ,  1510   b . Furthermore, the second elongate winged-like portion  1521   a ,  1521   b  at the second longitudinal edge portion  1516   a ,  1516   b  of the respective slat  1510   a ,  1510   b  may be followed by a backward curl  1523   a ,  1523   b  formed from subsequent curling of the second longitudinal edge  1515   a ,  1515   b  of the elongated sheet of material lengthwise away from the longitudinal axis  1511   a ,  1511   b  and looping backwards towards the longitudinal axis  1511   a ,  1511   b  of the respective slat  1510   a ,  1510   b . Accordingly, from the second elongate winged-like portion  1521   a ,  1521   b , the sheet of material may be curled away and then looped from the back towards the longitudinal axis  1511   a ,  1511   b  of the respective slat  1510   a ,  1510   b  to form the backward curl  1523   a ,  1523   b . The semi-circular outward curl  1522   a ,  1522   b , the second elongate winged-like portion  1521   a ,  1521   b , and the backward curl  1523   a ,  1523   b  may, together, form a second curled edge portion of the respective slat  1510   a ,  1510   b . The second curled edge portion of the slat  1510   a ,  1510   b  may be a second interlocking element of the respective slat  1510   a ,  1510   b . According to various embodiments, the second curled edge portion of the first slat  1510   a  may be configured for engaging, interlocking, or interacting with the first curled edge portion of the second slat  1510   b  to pivotably join the two slats  1510   a ,  1510   b  together. According to various embodiments, the second longitudinal edge portion  1516   a ,  1516   b  of the respective slat  1510   a ,  1510   b  may include the inward bend  1542   a ,  1542   b , the second elongate overhang portion  1541   a ,  1541   b , the semi-circular outward curl  1522   a ,  1522   b , the second elongate winged-like portion  1521   a ,  1521   b , and the backward curl  1523   a ,  1523   b.    
     According to various embodiments, a curl radius of the inward curl  1520   a ,  1520   b  at the first longitudinal edge portion  1514   a ,  1514   b  may be smaller than a curl radius of the semi-circular outward curl  1522   a ,  1522   b  at the second longitudinal edge portion  1516   a ,  1516   b . Further, a curl radius of the backward curl  1521   a ,  1521   b  at the second longitudinal edge portion  1516   a ,  1516   b  may be smaller than the curl radius of the inward curl  1520   a ,  1520   b  at the first longitudinal edge portion  1514   a ,  1514   b . Accordingly, two adjacent slats  1510   a ,  1510   b  may be joined together by, for example, overlapping, fitting, interlocking, engaging, interacting or joining of an inward curl at a first longitudinal edge portion of a first slat to an outward curl at a second longitudinal edge portion of a second slat and a backward curl at the second longitudinal edge portion of the second slat to the inward curl at the first longitudinal edge portion of the first slat such that the first slat may be pivotably joined to the second slat. According to various embodiments, each slat may be configured to overlap or fit or interlock or joined with a further slat, one after another in a series, so as to form a shutter curtain. 
     As shown in  FIG. 15A  and  FIG. 15C , in use, the joined slats  1510   a ,  1510   b  may be in a suspended mode whereby the second slat  1510   b  (or the lower slat) may hang from the first slat  1510   a  (or the upper slat). This may occur, for example, when a shutter curtain formed from interlocking two or more slats  1510   a ,  1510   b  in the manner as described with reference to  FIG. 15A to 15D  is being rolled in or rolled out from a drum of a shutter assembly. According to various embodiments, in the suspended mode, the inward curl  1520   b  of the first longitudinal edge portion  1514   b  of the second slat  1510   b  may be in engagement with the backward curl  1523   a  of the second longitudinal edge portion  1516   a  of the first slat  1510   a . Accordingly, the second slat  1510   b  may be pivotably hung from the first slat  1510   a.    
     As shown in  FIG. 15B  and  FIG. 15D , in use, the joined slats  1510   a ,  1510   b  may be in a stacked mode whereby the first slat  1510   a  (or the upper slat) may be stacked or sit or rested on the second slat  1510   b  (or the lower slat). This may occur, for example, when a shutter curtain formed from interlocking two or more slats  1510   a ,  1510   b  in the manner as described with reference to  FIG. 15A to 15D  is fully rolled out from a drum of a shutter assembly such that the shutter curtain is in the lowered state and resting on a ground. According to various embodiments, in the stacked mode, the outward curl  1520   a  of the second longitudinal edge portion  1516   a  of the first slat  1510   a  may be stacked or sit or rested on the inward curl  1520   b  of the first longitudinal edge portion  1514   b  of the second slat  1510   b  such that the first slat  1510   a  is being supported by the second slat  1510   b.    
       FIG. 16  shows a schematic side view of a vertical roller shutter  1600  according to various embodiments. As shown, the vertical roller shutter  1600  may include a pair of shutter curtain assemblies  1606 ,  1608 . The vertical roller shutter  1600  may be configured such that the pair of shutter curtain assemblies  1606 ,  1608  may be raised up and lowered down vertically. Accordingly, when in the lowered state, the pair of shutter curtain assemblies  1606 ,  1608  may be spaced apart and parallel to each other such that the pair of shutter curtain assemblies  1606 ,  1608  may be facing each other. According to various embodiments, each of the pair of shutter curtain assemblies  1606 ,  1608  may be a shutter curtain assembly formed by the slats  1510   a ,  1510   b  of  FIG. 15A  to  FIG. 15D . Accordingly, a plurality of slats  1510   a ,  1510   b  may be pivotally interlocked one after another to form the respective shutter curtain assembly  1606 ,  1608 . According to various embodiments, respective insulating layers  1650 ,  1650 ′ of the respective shutter curtain assemblies  1606 ,  1608  may be lined on respective surfaces of the respective shutter curtain assemblies  1606 ,  1608  such that they are facing each other. 
     According to various embodiments, respective retaining mechanism  1660 ,  1660 ′ (similar to the retaining mechanism  160  of  FIG. 1A  and  FIG. 1B ) may be disposed on the respective insulation layer  1650 ,  1650 ′ to press a portion of the respective insulation layer  1650 ,  1650 ′ into respective first receiving portion of one of at least two adjacent pivotally interlocked slats and to press a further portion of the respective insulation layer  1650 ,  1650 ′ into respective second receiving portion of the one of the at least two adjacent pivotally interlocked slats such that the respective retaining mechanism  1660 ,  1660 ′ may cooperate with the respective first and second receiving portions of the one of the at least two adjacent pivotally interlocked slats to hold the respective insulation layer  1650 ,  1650 ′ between the respective retaining mechanism  1660 ,  1660 ′ and the at least two adjacent pivotally interlocked slats. According to various embodiments, the respective first and the second receiving portions of the one of the at least two adjacent pivotally interlocked slats may be a pair of bent portions of the one of the at least two adjacent pivotally interlocked slats. Each of the pair of bent portions may form an acute angle. 
     According to various embodiments, respective pusher members (similar to the first pusher member  170  and the second pusher member  172  of  FIG. 1A  and  FIG. 1B ) may be disposed between the respective insulation layer  1650 ,  1650 ′ and the respective retaining mechanism  1660 ,  1660 ′. 
     According to various embodiments, the vertical roller shutter  1600  may include one single drum  1607 . Accordingly, both the first shutter curtain assembly  1606  and the second shutter curtain assembly  1608  may be attached to and wound round the drum  1607 . The first shutter curtain assembly  1606  and the second shutter curtain assembly  1608  may be arranged such that the respective insulating layers  1650 ,  1650 ′ are facing each other when both the first shutter curtain assembly  1606  and the second shutter curtain assembly  1608  are wound round the drum  1607 . According to various embodiments, the first shutter curtain assembly  1606  and the second shutter curtain assembly  1608  may be attached to the drum  1107  in a manner such that both the shutter curtain assemblies  1106 ,  1108  may be rolled in or rolled out at the same time in a synchronized manner. 
     According to various embodiments, the pair of shutter curtain assemblies  1606 ,  1608  may be configured such that the pair of shutter curtain assemblies  1606 ,  1608  operable may be operable or movable as one (or like a single unitary article). 
     According to various embodiments, the first shutter curtain assembly  1606  and the second shutter curtain assembly  1608  may be joined to each other at respective bottom ends by a foot component  1690  such that the pair of shutter curtain assemblies  1606 ,  1608  may be joined in such a way so as to form a single unit. In this manner, the pair of shutter curtain assemblies  1606 ,  1608  may be operable such that the pair of shutter curtain assemblies  1606 ,  1608  may be moved as one (or like a single unitary article). According to various embodiments, the foot component  1690  may be a substantially U-shaped channel wherein a first longitudinal side is attached to the free end of the first shutter curtain assembly  1606  and a second longitudinal side is attached to the free end of the second shutter curtain assembly  1608 . According to various embodiments, the first shutter curtain assembly  1606  and the second shutter curtain assembly  1608  may be joined to each other in the manner as shown in  FIG. 5B . 
     According to various embodiments, each of the pair of shutter curtain assemblies  1606 ,  1608  may be formed by the slats  1510   a ,  1510   b  of  FIG. 15A  to  FIG. 15D . Accordingly, there may be some lateral leeway (or some degree of freedom to move laterally) between any two adjacent (or side-by-side) slats  1510   a ,  1510   b  of the respective plurality of slats such that respective two adjacent slats  1510   a ,  1510   b  may be in the suspended mode or the stacked mode (see  FIG. 15A  to  FIG. 15D ) during rolling in and rolling out depending on the position and orientation of the respective two adjacent slats  1510   a ,  1510   b . According to various embodiments, the lateral leeway between any two adjacent slats  1510   a ,  1510   b  may provide the stackability of the plurality of slats of the respective shutter curtain assembly  1606 ,  1608  so as to facilitate rolling in or rolling out of the pair of curtain assemblies  1606 ,  1608  as a single unit. According to various embodiments, the stackability of the plurality of slats of the respective shutter curtain assembly  1606 ,  1608  may allow the respective shutter curtain assembly  1606 ,  1608  to lengthen or shorten independently so as to accommodate for the difference in length of the respective shutter curtain assembly  1606 ,  1608  during rolling in and rolling out due to constantly changing diameter. In particular, as one of the pair of shutter curtain assemblies  1606 ,  1608  may be on top of the other when wound round the drum  1607 , respective length of the respective shutter curtain assembly  1606 ,  1608  released from the drum  1607  has to be different from each other in order for the pair of curtain assemblies  1606 ,  1608  to be operable or movable as a single unitary article. For example, as shown in  FIG. 16 , two slats  1510   a ,  1510   b  of the first shutter curtain assembly  1606  near the foot component  1690  may be in the suspended mode and two slats  1510   a ′,  1510   b ′ of the second shutter curtain assembly  1608  near the foot component  1690  may be in the stacked mode. As shown, a length of the first shutter curtain assembly  1606  hanging from the drum  1607  may be longer than a length of the second shutter curtain assembly  1608  hanging from the drum  1608 . Accordingly, in order to maintain the unity of the pair of shutter curtain assemblies  1606 ,  1608 , some of the slats of the second shutter curtain assembly  1608  has to be stacked so as to accommodate the difference in length. Accordingly, the pair of shutter curtain assemblies  1606 ,  1608  formed by the slats  1510   a ,  1510   b  of  FIG. 15A  to  FIG. 15D  may facilitate rolling in or rolling out of the pair of curtain assemblies  1606 ,  1608  as a single unit. 
     According to various embodiments, the vertical roller shutter  1600  may include a motor assembly (not shown). According to various embodiments, a belt or a chain mechanism may couple the drum  1607  to the motor assembly such that the motor assembly may drive the rotation of the drums  1607  to roll in or roll out both the shutter curtain assemblies  1606 ,  1608  at the same time in a synchronized manner. Accordingly, the motor assembly may drive the drum  1607  to rotate in a first direction (for example, clockwise direction) for rolling in both the shutter curtain assemblies  1606 ,  1608 , and drive the drum  1607  to rotate in a second direction (for example, anti-clockwise direction) for rolling out both the shutter curtain assemblies  1606 ,  1608 . 
     According to various embodiments, a guide rail  1699  (or a shutter guide channel) may be provided along each sides of a wall opening in which the vertical roller shutter  1600  is installed. According to various embodiments, the pair of shutter curtain assemblies  1606 ,  1608  may be inserted or slotted or placed into the single guide rail  1699  (or shutter guide channel) on each sides of the wall opening such that the pair of shutter curtain assemblies  1606 ,  1608  may travel together as a single unit along a single guide rail  1699  on each sides of the wall opening. 
       FIG. 17A  to  FIG. 17C  show a sequence of how the plurality of slats of the respective shutter curtain assembly  1606 ,  1608  of the vertical roller shutter  1600  may continue to stack even after the foot component  1690  has reached a floor  1755  according to various embodiments. As shown in  FIG. 17A , the plurality of slats of the respective shutter curtain assembly  1606 ,  1608  near the respective foot component  1690  may be in the suspended mode as it approaches the floor  1755 . In  FIG. 17B , as the respective foot component  1690  touches the floor  1755 , the bottommost slats may start to stack. In  FIG. 17C , as more slats are released from the drum  1607 , the plurality of slats of the respective shutter curtain assembly  1606 ,  1608  of the vertical roller shutter  1600  may continue stacking one on top another until the respective shutter curtain assembly  1606 ,  1608  may form a rigid panel of firmly stacked and interlocked slats. In this manner whereby the plurality of slats are firmly stacked and interlocked, the shutter&#39;s ability to resist (or withstand) impact and/or higher wind forces may be enhanced. 
     According to various embodiments, while  FIG. 16  and  FIG. 17A  to  FIG. 17C  show embodiments of a roller shutter with a pair of shutter curtain assemblies  1606 ,  1608 , it is understood that a roller shutter may include two or three or more shutter curtain assemblies and may function in a fashion similar to that of the vertical roller shutter  1600  of  FIG. 16 . Further, it is also understood that the features of the vertical roller shutter  1600  of  FIG. 16  may be applicable to lateral roller shutters. 
       FIG. 18  shows a schematic side view of a vertical roller shutter  1800  according to various embodiments. The vertical roller shutter  1800  of  FIG. 18  differs from the vertical roller shutter  1600  of  FIG. 16  in that the vertical roller shutter  1800  of  FIG. 18  does not include the insulating layers  1650 ,  1650 ′ and/or the retaining mechanism  1660 ,  1660 ′ and/or the pusher members. According to various embodiments, the vertical roller shutter  1800  of  FIG. 18  may be a variant of the vertical roller shutter  1600  of  FIG. 16  without fire insulation. According to various embodiments, the vertical roller shutter  1800  of  FIG. 18  may, similar to the vertical roller shutter  1600  of  FIG. 16 , include a pair of shutter curtain assemblies  1806 ,  1808 . Similarly, each of the pair of shutter curtain assemblies  1806 ,  1808  may be a shutter curtain assembly formed by the slats  1510   a ,  1510   b  of  FIG. 15A  to  FIG. 15D . Accordingly, a plurality of slats  1510   a ,  1510   b  may be pivotally interlocked one after another to form the respective shutter curtain assembly  1806 ,  1808 . According to various embodiments, the first shutter curtain assembly  1806  and the second shutter curtain assembly  1808  of the vertical roller shutter  1800  of  FIG. 18  may, similar to the vertical roller shutter  1600  of  FIG. 16 , be joined to each other at respective bottom ends. According to various embodiments, the stackability of the respective plurality of slats of the respective shutter curtain assembly  1806 ,  1808  of the vertical roller shutter  1800  of  FIG. 18  may allow the respective plurality of slats to be stacked into a rigid panel of firmly stacked and interlocked slats which may enhance the shutter&#39;s ability to resist (or withstand) impact and/or higher wind forces. 
     According to various embodiments, there is provided a slat assembly for a roller shutter. The slat assembly may include an insulation layer. The slat assembly may further include a slat having a first receiving portion and a second receiving portion. The slat may be lined with the insulation layer. The slat assembly may further include a (or at least one) retaining mechanism disposed on the insulation layer to urge a first portion of the insulation layer against the first receiving portion of the slat and to urge a second portion of the insulation layer against the second receiving portion of the slat such that the retaining mechanism may cooperate with the first and second receiving portions of the slat to hold the insulation layer between the retaining mechanism and the slat without puncturing or penetrating the insulation layer. 
     According to various embodiments, the first and second receiving portions of the slat may be a pair of bent portions of the slat. Each of the pair of bent portions may form an acute angle. According to various embodiments, the pair of bent portions of the slat may form a pair of grooves having a V-shaped cross-section or a U-shaped cross-section or a horse-shoe-shaped cross-section. 
     According to various embodiments, the retaining mechanism may press the first portion of the insulation layer into the first receiving portion of the slat and to press the second portion of the insulation layer into the second receiving portion of the slat such that the retaining mechanism cooperates with the first and second receiving portions of the slat to hold the insulation layer between the retaining mechanism and the slat. 
     According to various embodiments, the first and second receiving portions of the slat may extend longitudinally along the slat and may be parallel to each other. 
     According to various embodiments, the first and the second receiving portions of the slat may be a pair of grooves. According to various embodiments, the pair of grooves may be opposing each other. According to various embodiments, the pair of grooves is a pair of bent portions of the slat. 
     According to various embodiments, the slat assembly may further include a first pusher member. The first pusher member may be disposed between the first portion of the insulation layer and the retaining mechanism. The first pusher member may be aligned with a first groove of the pair of grooves. According to various embodiments, the first pusher member may include a bar with a V-shaped cross-section or a U-shaped cross-section or a horse-shoe shaped cross-section. 
     According to various embodiments, the slat assembly may further include a second pusher member. The second pusher member may be disposed between the second portion of the insulation layer and the retaining mechanism. The second pusher member may be aligned with a second groove of the pair of grooves. According to various embodiments, the second pusher member may include a bar with a V-shaped cross-section or a U-shaped cross-section or a horse-shoe shaped cross-section. 
     According to various embodiments, the retaining mechanism may be pre-loaded to supply an expansion force for urging the first and second portions of the insulation layer against the respective first and second receiving portions of the slat. 
     According to various embodiments, the retaining mechanism may be configured to press the first portion of the insulation layer into the first receiving portion of the slat and to press the second portion of the insulation layer into the second receiving portion of the slat. 
     According to various embodiments, the retaining mechanism may include an insert in the form of a strip of resilient material which may have a length longer than a distance between the first and second receiving portions of the slat. 
     According to various embodiments, a first longitudinal edge portion of the slat may be curled inwardly towards a longitudinal axis of the slat to form a first curled edge portion and a second longitudinal edge of the slat may be curled outwardly away from the longitudinal axis of the slat to form a second curled edge portion. According to various embodiments, the first curled edge portion may have a smaller curl radius than the second curled edge portion. 
     According to various embodiments, the insulation layer may include a layer of insulation wool sandwiched between two layers of insulation cloths. The insulation wool may include ceramic fiber wool or rock wool etc. The insulation cloth may include silica fabric or fibre-glass fabric etc. 
     According to various embodiments, the slat assembly may further include two side covers. One side cover may be attached to one end of the slat. Each side cover may be configured to cover respective edge portion of the insulation layer along the respective end of the slat. 
     According to various embodiments, there is provided a roller shutter. The roller shutter may include a plurality of slats pivotally interlocked one after another to form a shutter curtain. The roller shutter may further include an insulation layer lined across at least two adjacent pivotally interlocked slats of the plurality of slats. The roller shutter may further include at least one retaining mechanism disposed on the insulation layer to urge a portion of the insulation layer against a first receiving portion of one of the at least two adjacent pivotally interlocked slats and to urge a further portion of the insulation layer against a second receiving portion of the one of the at least two adjacent pivotally interlocked slats such that the at least one retaining mechanism may cooperate with the first and second receiving portions of the one of the at least two adjacent pivotally interlocked slats to hold the insulation layer between the at least one retaining mechanism and the at least two adjacent pivotally interlocked slats without puncturing or penetrating the insulation layer. 
     According to various embodiments, the first and second receiving portions of the one of the at least two adjacent pivotally interlocked slats may be a pair of bent portions of the one of the at least two adjacent pivotally interlocked slats. Each of the pair of bent portions may form an acute angle. According to various embodiments, the pair of bent portions of the one of the at least two adjacent pivotally interlocked slats may form a pair of parallel opposing grooves having a V-shaped cross-section or a U-shaped cross-section or a horse-shoe-shaped cross-section. 
     According to various embodiments, the at least one retaining mechanism may press a portion of the insulation layer into a first receiving portion of one of the at least two adjacent pivotally interlocked slats and press a further portion of the insulation layer into a second receiving portion of the one of the at least two adjacent pivotally interlocked slats such that the at least one retaining mechanism cooperates with the first and second receiving portions of the one of the at least two adjacent pivotally interlocked slats to hold the insulation layer between the at least one retaining mechanisms and the at least two adjacent pivotally interlocked slats. 
     According to various embodiments, the first and the second receiving portions of the one of the at least two adjacent pivotally interlocked slats may be a pair of parallel opposing grooves. According to various embodiments, the pair of parallel opposing grooves may be a pair of bent portions of the one of the at least two adjacent pivotally interlocked slats. 
     According to various embodiments, the roller shutter may further include at least one pusher member. The at least one pusher member may be disposed between the insulation layer and the at least one retaining mechanism. The at least one pusher member may be aligned with a groove of the pair of parallel opposing grooves of the one of the at least two adjacent pivotally interlocked slats. According to various embodiments, the at least one first pusher member may include a bar with a V-shaped cross-section or a U-shaped cross-section or horse-shoe shaped cross-section. 
     According to various embodiments, the at least one retaining mechanism may be pre-loaded to supply an expansion force for urging the respective portions of the insulation layer against the respective first and second receiving portions of the one of the at least two adjacent pivotally interlocked slats. 
     According to various embodiments, the at least one retaining mechanism may be configured to press respective portions of the insulation layer into the respective first and second receiving portion of the one of the at least two adjacent pivotally interlocked slats. 
     According to various embodiments, the at least one retaining mechanism may include an insert in the form of a strip of resilient material which may have a length longer than a distance between the first and second receiving portions of the one of the at least two adjacent pivotally interlocked slats. 
     According to various embodiments, the insulation layer may include a layer of insulation wool sandwiched between two layers of insulation cloths. The insulation wool may include ceramic fiber wool or rock wool etc. The insulation cloth may include silica fabric or fibre-glass fabric etc. 
     According to various embodiments, the roller shutter may include two sets of the plurality of slats to form two shutter curtains. When in the lowered state, the two shutter curtains may be spaced apart and may be directly facing each other. 
     According to various embodiments, foot portions of the two shutter curtains may be configured to cooperate to insulate and seal a gap between the foot portions of the two shutter curtains. According to various embodiments, the foot portions of the two shutter curtains may include insulating blocks in an overlapping arrangement to seal a gap between the foot portions of the two shutter curtains. Accordingly, one or more insulating blocks on the foot portion of a first shutter curtain may overlap one or more insulating blocks on the foot portion of a second shutter curtain. 
     According to various embodiments, a first shutter curtain of the two shutter curtains may be attached to a first drum which is driven by a first motor, and a second shutter curtain of the two shutter curtains may be attached to a second drum which is driven by a second motor. According to various embodiments, simultaneous driving the rotation of both the drums in a same direction in a coordinated manner may roll in or roll out both the shutter curtains at the same time in a synchronized manner. 
     According to various embodiments, a first shutter curtain of the two shutter curtains may be attached to a first drum which is driven by a first motor, and a second shutter curtain of the two shutter curtains may be attached to a second drum which is driven by a second motor. According to various embodiments, simultaneous driving the rotation of both the drums in opposite directions in a coordinated manner may roll in or roll out both the shutter curtains at the same time in a synchronized manner. 
     According to various embodiments, the two shutter curtains may be attached to one single drum which is driven by a first motor, and the two shutter curtains may be attached to the one single drum in a manner in which driving the rotation of the drum may roll in or roll out the two shutter curtains at the same time in a synchronized manner. According to various embodiments, interlocking elements of each of the plurality of slats of each shutter curtain may be configured to interlock in a manner so as to provide lateral leeway between the at least two adjacent pivotally interlocked slats (in a side-by-side configuration) such that the at least two adjacent pivotally interlocked slats may be in a suspended mode or a stacked mode. In the suspended mode, the at least two adjacent pivotally interlocked slats may be extended laterally from each other such that the respective shutter curtain may be lengthened. In the stacked mode, the at least two adjacent pivotally interlocked slats may be closed in laterally on each other such that the respective shutter curtain may be shortened. According to various embodiments, bottom ends of the two shutter curtains may be fixedly joined together such that the two shutter curtains may be joined in such a way so as to form a single unit. 
     According to various embodiments, there is provided a roller shutter. The roller shutter may include one single drum. The roller shutter may include two shutter curtains attached to the one single drum in a manner in which the two shutter curtains may be wound round the one single drum. Each of the two shutter curtains may include a plurality of slats pivotally interlocked one after another. Interlocking elements of each of the plurality of slats of each shutter curtain may be configured to interlock in a manner so as to provide lateral leeway between at least two adjacent pivotally interlocked slats (in a side-by-side configuration) such that the at least two adjacent pivotally interlocked slats of the respective plurality of slats may either be in a suspended mode (wherein the two slats are extended laterally from each other) or in a stacked mode (wherein the two slats are closed in laterally to stack on each other). According to various embodiments, the two shutter curtains may be fixedly joined together at respective bottom ends of respective shutter curtain. 
     According to various embodiments, the roller shutter may further include an insulation layer lined across the plurality of slats of the respective shutter curtain. According to various embodiments, the roller shutter may further include at least one retaining mechanism disposed on the insulation layer to urge a first portion of the insulation layer against a first receiving portion of one of the plurality of slats of the respective shutter curtain and to urge a second portion of the insulation layer against a second receiving portion of the one of the plurality of slats of the respective shutter curtain such that the at least one retaining mechanism may cooperate with the first and second receiving portions of the one of the plurality of slats of the respective shutter curtain to hold the insulation layer between the at least one retaining mechanism and the plurality of slats of the respective shutter curtain without puncturing or penetrating the insulation layer. 
     According to various embodiments, the roller shutter may further include a first pusher member disposed between the first portion of the insulation layer and a first end of the at least one retaining mechanism. According to various embodiments, the roller shutter may further include a second pusher member disposed between the second portion of the insulation layer and a second end of the at least one retaining mechanism. 
     According to various embodiments, the first and the second receiving portions of the one of the at least two adjacent pivotally interlocked slats may be a pair of bent portions of the one of the at least two adjacent pivotally interlocked slats. Further, each of the pair of bent portions may be of an acute angle. According to various embodiments, the pair of bent portions of the one of the at least two adjacent pivotally interlocked slats may form a pair of parallel opposing grooves. According to various embodiments, the first and the second pusher member may be aligned to corresponding grooves. 
     According to various embodiments, there is provided a method of manufacturing a slat assembly. The method may include providing a slat having a first receiving portion and a second receiving portion. The method may further include lining an insulation layer on the slat. The method may further include disposing a (or at least one) retaining mechanism on the insulation layer to urge a first portion of the insulation layer against the first receiving portion of the slat and to urge a second portion of the insulation layer against the second receiving portion of the slat such that the retaining mechanism may cooperate with the first and second receiving portions of the slat to hold the insulation layer between the retaining mechanism and the slat without puncturing or penetrating the insulation layer. 
     According to various embodiments, the first and second receiving portions of the slat may be a pair of bent portions of the slat. Each of the pair of bent portions may form an acute angle. 
     According to various embodiments, the retaining mechanism may press a first portion of the insulation layer into the first receiving portion of the slat and press a second portion of the insulation layer into the second receiving portion of the slat such that the retaining mechanism cooperates with the first and second receiving portions of the slat to hold the insulation layer between the retaining mechanism and the slat. 
     According to various embodiments, the method may further include configuring the slat assembly according to the various embodiments as described herein. 
     According to various embodiments, there is provided a method of a roller shutter. The method may include providing a plurality of slats pivotally interlocked one after another to form a shutter curtain. The method may further include lining an insulation layer across at least two adjacent pivotally interlocked slats of the plurality of slats. The method may further include disposing at least one retaining mechanism on the insulation layer to urge a portion of the insulation layer against a first receiving portion of one of the at least two adjacent pivotally interlocked slats and to urge a further portion of the insulation layer against a second receiving portion of the one of the at least two adjacent pivotally interlocked slats such that the at least one retaining mechanism may cooperate with the first and second receiving portions of the one of the at least two adjacent pivotally interlocked slats to hold the insulation layer between the retaining mechanism and the at least two adjacent pivotally interlocked slats without puncturing or penetrating the insulation layer. 
     According to various embodiments, the first and second receiving portions of the one of the at least two adjacent pivotally interlocked slats may be a pair of bent portions of the one of the at least two adjacent pivotally interlocked slats. Each of the pair of bent portions may form an acute angle. 
     According to various embodiments, the at least one retaining mechanism may press a portion of the insulation layer into a first receiving portion of one of the at least two adjacent pivotally interlocked slats and may press a further portion of the insulation layer into a second receiving portion of the one of the at least two adjacent pivotally interlocked slats such that the at least one retaining mechanism cooperates with the first and second receiving portions of the one of the at least two adjacent pivotally interlocked slats to hold the insulation layer between the at least one retaining mechanism and the at least two adjacent pivotally interlocked slats. 
     According to various embodiments, the method may further include configuring the roller shutter according to the various embodiments as described herein. 
     Various embodiments have provided a fire-insulated shutter curtain assembly or a fire-insulated roller shutter which include an insulation layer secured or attached or fastened to a shutter curtain of a roller shutter without puncturing or penetrating the insulation layer with fasteners. Accordingly, the fire-insulated shutter curtain assembly or the fire-insulated roller shutter may be free of any fasteners that may form a “thermal bridge” through the insulation layer. Hence, the insulation layer may be intact and the thermal insulation integrity of the insulation layer may be fully preserved such that the insulation layer may be effective in providing insulation to the shutter curtain or the roller shutter. At the same time, the insulation layer may be properly secured, attached or fastened to the shutter curtain such that the insulation layer may be rolled or unrolled together with the shutter curtain in a manner which minimizes or eliminates misalignment or bulging or tearing or over-stretching of the insulation layer. 
     While the invention has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes, modification, variation in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims. The scope of the invention is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.