Abstract:
A folded sheet article comprising a sheet material having a first set of folds defining segments of the sheet material and an electrically conductive pattern on a segment of the sheet material that does not extend across a fold in an unfolded state.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to folded sheet articles, whether in a folded or unfolded condition and to methods of manufacturing the same. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is known from European Patent No. EP-B-0 288 472 to provide a folded sheet article comprising a first and second set of concertina folds, which sets of folds are transverse to one another. Provision of such folded sheets with stiff portions at segments of the sheet in the region of diagonally opposite corners of the sheet provides a means of easily unfolding and refolding the sheet material. 
         [0003]    It is an aim of preferred embodiments of the present invention to overcome problems associated with the prior art, whether mentioned herein or otherwise. 
       SUMMARY OF THE INVENTION 
       [0004]    Generally, unless otherwise stated herein, the phrase “sheet material” is hereby defined as a material that takes folds at which is can be unfolded without the folds disappearing and refolded. It may be paper, or a paper-like material such as plastics sheet on which books are commonly printed, or may be very thin card or any other suitable material. It is conceivable that the sheet material may be stiff (e.g. card, semi-rigid paper or plastic) except at the folds, e.g. very thin stiff cards interconnected by paper, flexible plastic sheet or cloth, but this is deprecated as not allowing full realisation of the advantages of the invention. 
         [0005]    The present invention in a first aspect provides a folded sheet article comprising a sheet material having a first set of folds defining segments of the sheet material and an electrically conductive pattern on a segment of the sheet material that does not extend across a fold in an unfolded state. 
         [0006]    An electrically conductive pattern may be on several segments of the sheet, in which case at least one electrically conductive pattern does not extend across a fold and, preferably, none of the electrically conductive patterns extend across a fold. 
         [0007]    Suitably, the electrically conductive pattern comprises a conductive printable ink. 
         [0008]    The electrically conductive pattern may be a radio frequency identification tag. 
         [0009]    In this specification the term radio frequency identification is abbreviated to RFID. 
         [0010]    Suitably, the RFID tag is an active RFID tag. These can include semi-active RFID tags. 
         [0011]    Alternatively, the RFID tag is a passive RFID tag. A passive RFID tag has no internal power source. 
         [0012]    Suitably, the RFID tag is a chipless tag. 
         [0013]    Suitably, the article comprises a stiff portion. Suitably, the first set of folds define segments in the sheet material and the stiff portion is located at a peripheral segment of the sheet material. Thus, if the sheet comprises a single row of segments, the stiff portion is suitably located at an end segment of the row. 
         [0014]    Suitably, the stiff portion is located at or near a corner segment of the sheet. 
         [0015]    Suitably, a first stiff portion and a second stiff portion are located at substantially diagonally opposite corners of the sheet. 
         [0016]    Suitably, the stiff portion is attached (directly or indirectly) to the sheet material and the electrically conductive pattern is at least partly between the stiff portion and the sheet material. Suitably, the electrically conductive pattern is entirely between the stiff portion and the sheet material. Suitably, the stiff portion comprises a first layer and a second layer, wherein the electrically conductive pattern is at least partly between the first layer and the second layer. Suitably, the electrically conductive pattern is entirely between the first layer and the second layer. Suitably, the electrically conductive pattern is laminated between the first layer and the second layer. 
         [0017]    The stiff portion may comprise one or more folds. Suitably, the one or more folds are parallel to an edge of the stiff portion. If the stiff portion comprises a plurality of folds, the plurality is suitably parallel to one another. Suitably the plurality of folds forms a spine when folded. 
         [0018]    If the stiff portion is folded, each section of the folded stiff portion may be attached to the same or a different segment of the sheet. Alternatively, one section of the folded stiff portion may be attached to the sheet and the other section may be unattached to the sheet. 
         [0019]    The same effect may be achieved by joining two separate stiff portions together along an edge thereof, thus replacing the fold line. 
         [0020]    A stiff portion may be provided by a segment of the sheet that has been treated to make it stiffer than the rest of the sheet. For example, a segment may be soaked in a UV curable resin and then cured to provide the stiff portion. 
         [0021]    If the folded sheet material comprises a stiff portion, the stiff portion suitably provides an outside cover of the sheet when the sheet is in a folded condition. 
         [0022]    If a sheet in accordance with the present invention comprises two stiff portions, both of the stiff portions suitably provide a cover of the sheet when the sheet is in a folded condition. 
         [0023]    Suitably, the stiff portions are made of card. 
         [0024]    Generally, when the RFID tag is located in a stiff portion, an RFID tag is only in one of the stiff portions. 
         [0025]    Suitably, the first set of folds is a set of concertina folds. 
         [0026]    The folded sheet material may further comprise a second set of folds, which second set of folds are transverse to said first set of folds when said sheet is in a folded condition. Suitably, said second set of folds comprises a set of concertina folds. 
         [0027]    Suitably, the first set of folds comprises an odd number of folds. Suitably, the second set of folds comprises an even number of folds. 
         [0028]    Although one or both sets of folds may be non-parallel, e.g. convergent, and/or one or both of the stiff portions may, when the sheet is folded, not be outer portions, in a preferred embodiment the sheet is rectangular, the sets of folds being mutually perpendicular and parallel to the respective edges of the sheet, and the stiff portions being such as to be at the outside of the sheet when it has been folded by the first and second set of folds and being at least as large as the respective corner segments of the sheet. 
         [0029]    Suitably, in the folded condition, there are at least 3 layers of folded sheet, preferably at least 8 layers and more preferably at least 16 layers. 
         [0030]    According to the present invention in a second aspect, there is provided a method of manufacturing a folded sheet article according to the first aspect of the invention, the method comprising the step of providing a folded sheet article with an electrically conductive pattern that does not extend across a fold in an unfolded state. 
         [0031]    The present invention in a third aspect provides a folded sheet article comprising a sheet material and a radio frequency identification tag, the sheet material having a first set of folds. 
         [0032]    In this specification the term radio frequency identification is abbreviated to RFID. 
         [0033]    Suitably, the RFID tag is an active RFID tag. These can include semi-active RFID tags. 
         [0034]    Alternatively, the RFID tag is a passive RFID tag. A passive RFID tag has no internal power source. 
         [0035]    Suitably, the RFID tag comprises a conductive printable ink. 
         [0036]    Suitably, the RFID tag is a chipless tag. 
         [0037]    Suitably, the article comprises a stiff portion. Suitably, the first set of folds define segments in the sheet material and the stiff portion is located at a peripheral segment of the sheet material. Thus, if the sheet comprises a single row of segments, the stiff portion is suitably located at an end segment of the row. 
         [0038]    Suitably, the stiff portion is located at or near a corner segment of the sheet. Suitably, a first stiff portion and a second stiff portion are located at substantially diagonally opposite corners of the sheet. 
         [0039]    Suitably, the stiff portion is attached (directly or indirectly) to the sheet material and the RFID tag is at least partly between the stiff portion and the sheet material. Suitably, the RFID tag is entirely between the stiff portion and the sheet material. Suitably, the stiff portion comprises a first layer and a second layer, wherein the RFID tag is at least partly between the first layer and the second layer. Suitably, the RFID tag is entirely between the first layer and the second layer. Suitably, the RFID tag is laminated between the first layer and the second layer. 
         [0040]    The stiff portion may comprise one or more folds. Suitably, the one or more folds are parallel to an edge of the stiff portion. If the stiff portion comprises a plurality of folds, the plurality is suitably parallel to one another. Suitably the plurality of folds forms a spine when folded. 
         [0041]    If the stiff portion is folded, each section of the folded stiff portion may be attached to the same or a different segment of the sheet. Alternatively, one section of the folded stiff portion may be attached to the sheet and the other section may be unattached to the sheet. 
         [0042]    The same effect may be achieved by joining two separate stiff portions together along an edge thereof, thus replacing the fold line. 
         [0043]    A stiff portion may be provided by a segment of the sheet that has been treated to make it stiffer than the rest of the sheet. For example, a segment may be soaked in a UV curable resin and then cured to provide the stiff portion. 
         [0044]    If the folded sheet material comprises a stiff portion, the stiff portion suitably provides an outside cover of the sheet when the sheet is in a folded condition. 
         [0045]    If a sheet in accordance with the present invention comprises two stiff portions, both of the stiff portions suitably provide a cover of the sheet when the sheet is in a folded condition. 
         [0046]    Suitably, the stiff portions are made of card. 
         [0047]    Generally, when the RFID tag is located in a stiff portion, an RFID tag is only in one of the stiff portions. 
         [0048]    Suitably, the first set of folds is a set of concertina folds. 
         [0049]    The folded sheet material may further comprise a second set of folds, which second set of folds are transverse to said first set of folds when said sheet is in a folded condition. Suitably, said second set of folds comprises a set of concertina folds. 
         [0050]    Suitably, the first set of folds comprises an odd number of folds. Suitably, the second set of folds comprises an even number of folds. 
         [0051]    Although one or both sets of folds may be non-parallel, e.g. convergent, and/or one or both of the stiff portions may, when the sheet is folded, not be outer portions, in a preferred embodiment the sheet is rectangular, the sets of folds being mutually perpendicular and parallel to the respective edges of the sheet, and the stiff portions being such as to be at the outside of the sheet when it has been folded by the first and second set of folds and being at least as large as the respective corner segments of the sheet. 
         [0052]    Suitably, in the folded condition, there are at least 3 layers of folded sheet, preferably at least 8 layers and more preferably at least 16 layers. 
         [0053]    Surprisingly, it has been found that an RFID tag incorporated in a folded sheet article as described above has a lower failure rate than would otherwise be the case. On further investigation, it significantly appears that this is because the additional layers provided by the folded sheets and/or the stiff portions provide increased resistance to the type of deformation of the RFID tag that tends to lead to failure. This is particularly the case in folded sheet articles that are pocket sized or credit card sized because they tend to be kept in a user&#39;s pocket where they are susceptible to day to day damage. It is believed that bending of an RFID tag about one axis tends not to cause a high rate of failure, whereas bending about two axes in contrast does significantly increase the failure rate. 
         [0054]    According to the present invention in a fourth aspect, there is provided a method of manufacturing a folded sheet article according to the third aspect of the invention, the method comprising the step of providing a folded sheet article with a RFID tag. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0055]    The present invention will now be described, by way of example only, with reference to the following drawings, in which: 
           [0056]      FIG. 1  shows a plan view of a first embodiment of a folded sheet article in accordance with the present invention in a folded condition. 
           [0057]      FIG. 2  shows a plan view of the article of  FIG. 1  in a partially unfolded condition. 
           [0058]      FIG. 3  shows the article of  FIGS. 1 and 2  in an unfolded condition. 
           [0059]      FIG. 4A  shows an exploded view of a corner of the article of  FIGS. 1 ,  2  and  3 . 
           [0060]      FIG. 4B  shows an exploded view of an alternative corner construction of the article of  FIGS. 1 ,  2  and  3 . 
           [0061]      FIG. 5  shows a front plan view of a second embodiment of a folded sheet material in accordance with the present invention in a substantially unfolded condition. 
           [0062]      FIG. 6  shows a rear plan view of the sheet of  FIG. 5 . 
           [0063]      FIG. 7  shows a side view of a third embodiment of a folded sheet material in accordance with the present invention, in a folded condition. 
           [0064]      FIG. 8  shows an enlarged view of a further embodiment of the present invention showing part of a sheet article. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0065]      FIGS. 1 ,  2 ,  3  and  4  show a first embodiment of a folded sheet article  2  in accordance with the present invention. 
         [0066]    The folded sheet material  2  of  FIGS. 1 ,  2 ,  3  and  4  comprises a first stiff portion  4 , a second stiff portion  6 , a first set of folds  10  (represented by broken lines in  FIG. 4 ) and a second set of folds  12  (represented by dotted lines in  FIG. 4 ). In this embodiment, folded sheet is of paper and the stiff portions are made of card that is relatively stiffer than the paper. 
         [0067]    Both of the first set of folds  10  and the second set of folds  12  comprise a set of concertina folds. The folds define segments of the sheet. 
         [0068]    The first stiff portion  4  is located at a corner segment  14  of the sheet  2 . The second stiff portion  6  is located at a corner segment  16  of the sheet  2 . The corner segments  14  and  16  are at diagonally opposite corner segments of the sheet. 
         [0069]    With particular reference to  FIG. 4A  of the accompanying drawings, the first stiff portion  4  comprises a first layer  4 A, a second layer  4 B and a RFID tag  20  sandwiched between the first layer  4 A and the second layer  4 B. 
         [0070]    The RFID tag  20  comprises an antenna portion  40 , a battery portion  42  and a microprocessor portion  44 . The antenna portion is made from an electrically conductive pattern. 
         [0071]    The first layer  4 A is glued to the second layer  4 B by an adhesive. Alternatively, the first layer  4 A can be laminated to the second layer  4 B. 
         [0072]    For ease of application, the RFID tag  20  can be applied to an intermediate carrier layer  22  which is then sandwiched between the first layer  4 A and the second layer  4 B. The RFID tag  20  can be printed onto such a layer  22  using a conductive ink. 
         [0073]    The RFID tag  20  can be a passive tag or an active tag. In the illustrated embodiment it is an active tag because it includes an internal battery power source. 
         [0074]    Advantageously, but not necessarily, the RFID tag can be printed using conductive ink onto one of the first or second layers  4 A,  4 B, or onto a carrier. Currently this requires the RFID tag  20  to be a chipless RFID tag but it is envisaged that RFID tags with chips using conductive ink may be possible in the future. 
         [0075]    The stiff portion  4 , carrying the RFID tag  20  is then adhered to the corner section  16  of the sheet. 
         [0076]      FIG. 4B  shows an alternative construction of the corner section of the article. In  FIG. 4B , the first stiff portion  4  comprises a first layer  24  and a RFID tag  20 . There is no second layer of the stiff portion in this embodiment. 
         [0077]    The first layer  24  is glued or laminated to the corner section  16  of the sheet  2  with the RFID tag sandwiched therebetween. 
         [0078]    For ease of application, the RFID tag  20  can be applied to an intermediate carrier layer  22 . The RFID tag  20  can be printed onto such a layer  22  using a conductive ink. For ease of manufacture a side of the carrier layer  22  can be adhesive to assist in locating it between the stiff portion  24  and the sheet  2 . 
         [0079]      FIGS. 5 and 6  illustrate a second embodiment of the invention. 
         [0080]    The folded sheet material  30  illustrated in  FIGS. 5 and 6  comprises a first stiff portion  32  and a first set of folds  33  (represented by broken lines). The first stiff portion  32  contains ( FIG. 4A ) or overlies ( FIG. 4B ) the RFID tag  20  as described above. 
         [0081]      FIG. 7  illustrates a third embodiment of a folded sheet material  50  in accordance with the present invention. 
         [0082]    The folded sheet material  90  comprises a folded sheet  92 , comprising a first set of concertina folds and a stiff portion  94 . 
         [0083]    The stiff portion  94  comprises a fold  98 . 
         [0084]    In a folded condition, the stiff portion  94  folds about fold line  98  to provide a cover for the folded sheet  92 . 
         [0085]    The stiff portion  94  contains ( FIG. 4A ) or overlies ( FIG. 4B ) the RFID tag  20  as described above. 
         [0086]    By keeping the electrically conductive pattern of the RFID tag  20  on a segment without crossing a fold line of the folded sheet, it avoids lines of weakness being formed in the electrically conductive pattern that can lead to failures of the FRID tag in use. 
         [0087]    Folded sheet articles according to embodiments of the present invention can be used in a wide variety of applications, including, but not limited to the following:
       Ski pass/piste map—in this case the RFID tag can act as a form of identification.   Railway (or other form of transport) ticket/map   Bus (or other form of transport) pass/timetable—a record can be kept of which RFID tags are associated with which timetables so that if a timetable is changed, the user of the old timetable can be alerted when they next try to use their pass.   Loyalty card/shop details   Pharmaceuticals identification/drugs information   City cards—museum tickets, theatre tickets       
 
         [0094]    It will be appreciated that there are many other diverse applications to which embodiments of the present invention can be applied. 
         [0095]    In an alternative embodiment of the present application shown in  FIG. 8  of the accompanying drawings, which is a modification of the embodiment shown in  FIG. 4 , using the same reference numerals for corresponding parts. In  FIG. 8  an electrically conductive pattern  100  is formed from a conductive ink on a carrier layer  102  which is applied to a non-corner segment  104  of the sheet, without the electrically conductive pattern crossing a fold line of the sheet. 
         [0096]    Such an electrically conductive patter, without an RFID tag in this case, can be used for a variety of applications, such as augmented reality (“AR”) applications. 
         [0097]    AR enables the real world to merge with virtual computer generated imagery, creating a mixed reality. 
         [0098]    This is achieved by image registration of the optical information from print generated registration patterns, such as, but not limited to grids of black and white squares. (like a checkerboard not unlike a barcode). 
         [0099]    Once the registration pattern is detected by a camera this is automatically displayed as a 3D image generated from these printed patterns. 
         [0100]    Consequently feature detection is crucially depended on corner and edge detection, thresholding and other image processing methods. 
         [0101]    One of the key difficulties in developing AR applications has been the problem of image disruption and distortion, due to the degradation of the target image caused by crease lines corrupting the pattern. Anyone who has experienced delays at supermarket checkout counters because of creases in packaging barcodes will be familiar with the problem. 
         [0102]    To solve this problem, it has been found that providing the target AR image pattern within the fold lines i.e. in one segment of a folded sheet preserves the virginity of the pattern and significantly increases the detection rate. This is achieved by ensuring the AR patterns are more stable and as clear and uncontaminated as possible, providing the highest possible performance recognition by a camera. 
         [0103]    This in turn opens up the easy development of a wide range of commercial AR applications. This is achieved by making the user experience interactive e.g. user guides, gallery guides, product information, etc. by holding the folded sheet article against a webcam which shows a 3D image and enables the user to interact with the product and select personalized variations if desired. 
         [0104]    If desired electrically conductive patterns can be applied to a plurality of segments of the sheet, in which case the article falls within the scope of the present claims provided there is one electrically conductive pattern that does not cross a fold line, but it is preferable that a plurality of such electrically conductive patterns do not cross fold lines of the sheet, and more preferable that none of such electrically conductive patterns cross a fold line. 
         [0105]    The reader&#39;s attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. 
         [0106]    All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. 
         [0107]    Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. 
         [0108]    The invention is not restricted to the details of the foregoing embodiment(s). The invention extend to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.