A modular rolling shutter for store windows and doors, comprised of vertically alternating rows of buckles and slats. Each slat is linked with the lower and upper buckles, allowing limited movement of the slats and buckles so that the modular shutter may be rolled and unrolled along tracks. The slats may be made of a transparent material allowing visibility without sacrificing weather resistance or security. Rolling shutters of various sizes which have the advantages of corrosion resistance, ease of transport, manufacture and repair can be easily formed.

BACKGROUND OF THE INVENTION 
     This invention relates to a rolling shutter, more particularly to a rolling shutter used for protection of store windows or doors. 
     Traditional metal rolling shutters are installed to guard stores against possible break-in and vandalism when the store is closed. Generally, a pair of tracks are provided on either side of the window or door. The shutter is rolled up along tracks to leave the window exposed during business hours, and unrolled down and secured upon closing, thereby covering and protecting the opening. 
     Conventional metal shutters are comprised of a plurality of shutter slats made of aluminum or steel. Conventional shutters present difficulties in manufacture, delivery, installation and repair. Moreover, when the conventional shutter is lowered, goods cannot be seen through the shutter. To make showcased goods visible, openings may be left in a conventional shutter. Unfortunately, openings expose goods to the elements and the possibility of damage or theft. Therefore, it is absolutely necessary to provide a shutter through which interior articles can be observed when the shutter is unrolled, and which is simple to manufacture, repair, deliver and install as well. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a rolling shutter for store windows and doors, which can be easily assembled into various sizes. 
     Another object of the invention is to provide a rolling shutter for store windows and doors which is formed from materials less susceptible to corrosion than the shutters formed entirely of a metallic material. 
     A further object of the invention is to provide a rolling shutter, which is simple to repair and clean while allowing articles behind the shutter to remain visible in the unrolled position. 
     Still another object of the invention is to provide a more weather resistant rolling shutter. 
     The objects of the invention are accomplished by providing a modular rolling shutter, which is comprised of alternating rows of buckles and slats. Upper and lower channels are provided on the upper and lower sections of each buckle. Upper and lower articulate edges are provided on the upper and lower sections of each slat. The interior dimensions and shape of the buckle channels are adapted to hold the articulate edges of the slats, while allowing enough movement so that the shutter can be rolled or unrolled. The left and right sides of adjacent slats abut each other, and may be rigidly joined. 
     The advantages of the rolling shutter of the invention relate to the ease with which the components can be assembled into an appropriate size, along with considerable strength, simplicity in manufacture, repair and delivery as well as improved corrosion resistance and transparency. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention shall be described by referring to the accompanying drawings, wherein like reference numerals indicate like elements throughout the views. 
     FIG. 1 is a schematic view, in perspective, showing the general arrangement of part of a rolling shutter of the invention; 
     FIG. 2 is a sectional end view, showing the structure and connection for a section of the rolling shutter of the invention; 
     FIG. 3 is a schematic, sectional view of one embodiment of a buckle, showing a convex outer surface; 
     FIG. 4 is a schematic, sectional view, showing a flat outer surface of another embodiment of the buckle with a reinforcing rod (shown in phantom) inserted within the buckle body; 
     FIG. 5 is a perspective view of the slats of the rolling shutter according to one embodiment of the invention; 
     FIG. 6 is a fragmentary top view of one embodiment, showing the interconnection between the left side and the right side of adjacent slats; 
     FIG. 7 is an illustration in perspective showing semi-cylindrical left and right side couplers for a slat; 
     FIG. 8 is an illustration in perspective showing dovetailed left and right side couplers for a slat; 
     FIG. 9 is an illustration in perspective showing the left and right female couplers for a slat, and a complimentary insert by which adjacent couplers can be joined; 
     FIG. 10 is an illustration in perspective showing planar left and right couplers for a slat; 
     FIG. 11 is a sectional view, similar to FIG. 2, showing an embodiment of a slat having more than one dasher; 
     FIG. 12 is a sectional, schematic view, showing another embodiment of the buckle adapted so that the shutter can be rolled outwardly; and 
     FIG. 13 is a frontal schematic view of an embodiment of the rolling shutter of the invention with plastic and metallic slats. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, the rolling shutter comprises alternating rows of buckles  100  and slats  200 , interconnected piece by piece. The width of the buckle  100  is designed to correspond to the width of the shutter tracks (not shown) on either side of a window or door. A row of adjacent slats are provided between, and linked with, the buckles  100  above and below. These alternating rows are repeated as necessary to form a modular rolling shutter of any required size. The upper and lower ends of the rolling shutter may be buckles  100 , slats  200  or some other fitting (not shown). 
     The construction of the rolling shutter and its operation are illustrated in FIG.  2 . The shutter is rolled and unrolled between two parallel tracks  300 . The heavy and light arrows indicate the respective viewing direction from inside and outside of the rolling shutter. The buckle  100  is an integral member, comprising an inner surface  110 , an outer surface  120   a,  an upper channel  130  and a lower channel  140 . The inner surface  110  and the outer surface  120   a  at the ends of the buckle are in sliding contact with the track  300 . The upper channel  130  and the lower channel  140  have openings that allow the buckle  100  to link at opposing locations (upper and lower as illustrated in FIG. 2) with corresponding parts of adjacent slats  200 . 
     Each slat  200 , comprises an integral slat body  210 , an upper articulate edge  220  and a lower articulate edge  230 . The slat may also include reinforced sides  240 ,  250  and a dasher  260 . 
     The upper and lower buckles  100  are linked with intermediate, upper and lower slats  200 . As shown in FIG. 2, the slat upper articulate edge  220  is linked with the lower channel  140  of the buckle  100  vertically above it. The lower articulate edge  230  is linked with the upper channel  130  of the buckle  100  vertically below it. 
     Configurations of the channels  130 ,  140  are complementary to the articulate edges  230 ,  220  and may be varied for different applications. The opening, formed in both the upper and lower channels, gives the slat  200  a restricted range of rotation within the channels, thus allowing the shutter to be rolled or unrolled. 
     The buckle  100  of the invention is made of metal, preferably aluminum. Other metals, such as steel, stainless steel, etc. may be used depending upon considerations of corrosion-resistance, strength, rigidity, price and aesthetics. The cross-sectional area of the buckle in one embodiment can be 30 mm×15 mm, although buckles of other dimensions will fall within the scope of this invention. 
     Referring to FIG. 3, an embodiment of the buckle  100  of the rolling shutter is shown. It has a tubular-shaped, thin shell structure. The inner surface  110  and the outer surface  120   b  are curved. The curvature results in a small sliding contact area between the track  300  and the buckle inner and outer surfaces  110 ,  120   b  sliding therein, so that the rolling shutter can be more easily raised or lowered. The configurations of the upper channel  130  and the lower channel  140  are illustrated in the drawing. The channels are circular in cross section, and have defined openings. 
     The portion of the outer surface  120   b  adjacent to the upper channel  130  of the buckle is angled obliquely inwardly and the portion of the outer surface  120   b  adjacent to the lower channel  140  is planar, so that rainwater will flow down the outer surface of the buckle body. The buckle base  160  is angled obliquely upwards, to prevent rainwater from flowing to the inner surface  110 . 
     The portion of the outer surface  120   b  adjacent to the lower channel  140  is also substantially perpendicular to the base surface  160 , forming a strengthening fillet  150  at the intersection. The use of curved sections for the structure of the buckle  100  greatly enhances its strength. 
     Another embodiment of the buckle  100  is shown in FIG.  4 . This embodiment has an outer surface  120   a  that is substantially flat. The flat outer surface increases contact with, and thereby stability within, the track  300 . The portion of the outer surface  120   a  which is adjacent to the upper channel  130  is angled obliquely inwardly and the portion of the outer surface  120   a  which is adjacent to the lower channel  140  is planar, as in the embodiment shown in FIG.  3 . 
     In some embodiments, a hollow space is defined within the body of the buckle, as shown in FIG. 4. A cylindrical metal rod can be inserted into this space, as shown by the dotted circle. The strength of the buckle is enhanced by this method. 
     The buckle embodiment shown in FIG. 12 differs from previous embodiments in the orientation and position of the openings of the upper channel  130   a  and lower channel  140   a.  In FIG.  3  and FIG. 4, the upper and lower openings face the inner surface  110 , so that the shutter can be rolled inwardly. In the embodiment shown in FIG. 12, the upper and lower openings face the outer surface  120   c,  so that the shutter can be rolled outwardly. 
     Each slat  200  is preferably made of a nonmetallic material, such as plastic, or glass-fiber reinforced plastic in order to obtain the advantages of lightweight and transparency. Transparent materials are preferable because articles behind the closed shutter can be seen. However, all or some of the slats can also be made from metal, such as aluminum. 
     The slats are preferably all identical to ease maintenance and assembly. The slat  200  may be rectangular or square, with dimensions, as an example, of about 10 cm×20 cm, and a thickness in the middle of the main portion ranging from 2 mm to 5 mm. These dimensions are exemplary and rolling shutters of other dimensions will fall within the scope of the invention. 
     One embodiment of the slat  200  is shown in FIG.  5 . The slat has a generally rectangular shape, and may be integrally molded to comprise a slat body  210 , an upper articulate edge  220 , a lower articulate edge  230 , inner reinforced sides  240 , outer reinforced sides  250  and a dasher  260 . Each articulate edge  220 ,  230  preferably extends the length of the slat and has a substantially uniform cross-section defined by a connecting shape. As shown in FIG. 5 the connecting shape is circular, although different connecting shapes are possible. The inner reinforced sides  240  and outer reinforced sides  250  are provided on the inside and outside faces, respectively, at both ends of the slat body  210 . The inner and outer reinforced sides  240 ,  250  are in the shape of a narrow strip and function as ribs, which considerably increase slat strength. In order to connect adjacent slats, a coupler  270  and  280  can be provided at the left and right sides of the slat  200 . The couplers may be integrally molded with the slat body or separately attached. In some embodiments, the adjacent couplers have complementary mating shapes enabling the left side and right side of adjacent slats to interconnect. Further detail of the interconnection between two adjacent slats is shown in FIG.  6 . This Figure shows portions of adjacent slats  210 , along with their inner reinforced side  240 , outer reinforced side  250 , a male dovetail coupler  270   b  and the mating female dovetail coupler  280   b.    
     FIG. 7 shows the left and right couplers for another embodiment of slat interconnection. The adjacent slat sides are connected by male and female semi-cylindrically shaped couplers  270   a,    280   a.  In this configuration, adjacent slats are connected, but not rigidly joined. 
     FIG. 8 shows a different embodiment of the slat interconnection, similar to that of FIG.  6 . One coupler is a male dovetail  270   b,  and the mating coupler is a female dovetail  280   b.  The dovetailed couplers lock adjacent slats into a rigid row. 
     FIG. 9 is a further embodiment of slat interconnection. The left coupler  280   c  and the right coupler  280   c  are the same. Both have similar cylindrical recesses, with opening widths that are smaller than the diameter of the cylindrical recess. By mating the insert  290  with the recesses of adjacent slats, the adjacent slats are rigidly joined. 
     FIG. 10 shows another embodiment for slat interconnection. The left and right couplers  280   d  are the same, with both couplers having planar surfaces. The planar surface of the left side coupler  280   d  and the right side coupler  280   d  butt against each other. In this embodiment, adjacent slats are not connected and may move with respect to each other. 
     The dasher  260  of the slat  200  is shown in FIGS. 2 and 5. The dasher is an elongated member extending along the outside lower portion of the slat body  210 . The projecting edge of the dasher acts as a drip edge, enabling rainwater flowing down the slat body to drip off the outer edge of dasher and away from the slat body. The dasher  260  may be manufactured as an integral part of the slat  200 , or may be manufactured as a separate component and attached to the slat. 
     In other embodiments, the slat has no dasher. Since the materials and construction of the rolling shutter are waterproof and corrosion resistant, the dasher  260  may be removed to make the slat  200  simpler and more cost effective. 
     Alternatively, the slat may have more than one dasher, as shown in FIG.  11 . In addition to a dasher  260  at the outer lower section of the slat, a dasher may also optionally be provided at the outer upper section, at the inner upper section and at the inner lower section. These optional dashers all have the same configuration. Although the slat becomes more complicated with the addition of multiple dashers, the resulting slat is more resistant to severe weather conditions and stronger. 
     A different embodiment of the invention is shown in FIG.  13 . The rolling shutter of this embodiment comprises slats and buckles, similar in structure and operation to previous embodiments, with the exception that the slats are made of plastic  200  and metal  200   a.  The metal slats  200   a  are positioned between the nonmetallic slats  200 . The metal slat  200   a  is structurally similar to the plastic slat  200 , but may have a smaller width, for example, 25-50 mm. The metal slat  200   a  can be positioned at any interval in the row of slats  200 . Despite this hybrid structure, the transparency of the rolling shutter is only slightly affected while strength is enhanced, thus a more secure rolling shutter is obtained. 
     Since the slats and buckles are common, modular rolling shutters of various sizes can be quickly assembled and their parts can be easily repaired, cleaned and replaced. The drawbacks of conventional shutters, such as difficulty of repair, low light transmission, susceptibility to corrosion, etc., will be overcome by use of the inventive modular rolling shutter. 
     While preferred embodiments of the foregoing invention have been set forth for purposes of illustration, the foregoing descriptions should not be deemed a limitation of the invention herein. Accordingly, various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit and scope of the invention.