Abstract:
A piece of luggage, rucksack or satchel is provided having a pair of spaced shoulder straps. At least one strap has a stress/strain unit to monitor the stress/strain in the strap as the piece is worn on the shoulder of a user. The at least one strap also has an indicator that provides a visual indication when the stress/strain of the strap has exceeded a predetermined threshold.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of application Ser. No. 10/515,214, filed May 20, 2005, now U.S. Pat. No. 7,156,918, which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to weighing devices and in particular relates to devices that provide a ready indication of the weight of a piece of luggage. 
     BACKGROUND OF THE INVENTION 
     Commercial aircraft have to place strict controls on the amount and weight of luggage that passengers carry on the aircraft. Tourists and international travelers often experience difficulties in ascertaining the weight of their luggage and this can result in fines and surcharges for being overweight. Whilst the check-in counters have scales that accurately weigh luggage it is often then too late for a passenger to re-organize his or her luggage. What is needed and what is apparently absent from the marketplace today is a simple means of providing an indication of the weight of a piece of luggage so that passengers can determine the weight of the luggage before they reach the airport. 
     The issue of overweight luggage also has serious ramifications with regard to health and safety considerations. Heavy suitcases, rucksacks or satchels can cause serious spinal injuries. Research has indicated that children, and/or adults, should not over lengthy periods transport more than 10% of their weight. 
     It is these needs that have brought about the present invention. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention there is provided a weighing device for providing a ready indication of the weight of a piece of luggage comprising load bearing means adapted to be placed through a carry handle of the piece of luggage and indicator means associated with the load bearing means whereby when the luggage is lifted via the load bearing means or carry handle the load bearing means is subjected to the mass of the piece of luggage and the indicator means provides an indication if a predetermined threshold mass has been exceeded. 
     According to a further aspect of the present invention there is provided a piece of luggage having a carry handle assembly comprising a handle connected to the piece of luggage, a pressure plate under the handle, a load cell between the pressure plate and the handle and means to provide an indication of weight coupled to the load cell wherein when the piece of luggage is lifted by the handle, the weight of the piece of luggage is transmitted to the load cell by contact with the pressure plate. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: 
         FIG. 1  illustrates a first embodiment of a weighing device which is inserted under a handle of a suitcase; 
         FIG. 2  shows the device when placed under load; 
         FIGS. 3   a ,  3   b  and  3   c  are side view of the device under varying loads; 
         FIG. 4  illustrates a second embodiment of a weighing device supported by a hand; 
         FIG. 5  shows the device of  FIG. 4  when held under the handle of a suitcase to weigh the suitcase; 
         FIG. 6  illustrates a third embodiment in which a weighing device is also supported by a user&#39;s hand; 
         FIG. 7  shows the device of  FIG. 6  when inserted under the handle of a suitcase to weigh the suitcase; 
         FIG. 8  illustrates a fourth embodiment in which a weighing device is incorporated into the handle of suitcase; 
         FIG. 9  is an exploded view of the handle assembly of  FIG. 8 ; 
         FIGS. 10   a  and  10   b  are schematic side elevational views of the handle of  FIG. 8  when free standing and under load; 
         FIG. 11  is an illustration of a variation of the fourth embodiment; and 
         FIG. 12  is an exploded view of the handle assembly in accordance with a fifth embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The first embodiment of the weighing device  10  shown in  FIGS. 1 to 3  comprises an elongate flat strip  11  of sturdy yet flexible material usually plastics or metal having a central waisted portion  12  with enlarged end portions  13  and  14  each containing apertures  16  and  17 . An upstanding flange  18  is attached to the underside of the central portion of the waisted portion. The flange has an upward projection  20  having a calibrated forward face  19 . 
     To use the device to weigh suitcase S the elongate strip  11  is placed under the handle H of the suitcase S as shown in  FIGS. 1 and 3   a.    
     By gripping the strip  11  by pressing fingers through the apertures  16  and  17  the suitcase S can be lifted via the strip  11 . As shown in  FIGS. 2 ,  3   b  and  3   c , the mass of the suitcase causes the ends  13 ,  14  to bend upwards against the calibrated scale  19  which then provides a ready indication of the weight of the suitcase S. It is envisaged that the calibrated scale  19  would include prominent marks that show the weight levels as determined by airlines for both economy and business class travel. Once the adjacent edge of the elongate strip has moved past one of these lines the user will be aware that the suitcase is above the prescribed limit. 
       FIG. 3   a  shows the strip  11  carrying no load,  FIG. 3   b  shows a ready indication of a light load whilst  FIG. 3   c  illustrates the effect of a heavy load. The thickness and flexibility of the strip is selected to ensure the regular degree of movement against the calibrated scale. 
     The device  10  is about the size of an airline ticket and thus takes up very little room so that it can be simply carried in hand luggage. 
     Instead of the mechanical device described with reference to  FIGS. 1 and 3 , it is understood that the strip  11  could carry suitably positioned strain gauges which would provide an electrical signal that could be correlated to the weight to which the strip is subjected. The strip  11  could also include a pressure sensitive chamber positioned directly under the handle to absorb the mass of the suitcase. The chamber could include a chemical substance that changes color under load so that a change to a selected color would indicate that the weight of the piece of luggage has exceeded a particular threshold. 
     It is understood that the chemical make-up of pressure sensitive pads or chemical substances that change color under load would be known to those skilled in the art. 
     In the second and third embodiments shown in  FIGS. 4 to 7 , the weighing device  30  is handheld and is in the form of a substantially flat credit card shaped unit. The unit incorporates a sensor panel  31  on its upper surface that senses downward pressure on the panel. The panel incorporates a load cell that is coupled to a liquid-crystal display (LCD)  32  and a suitable battery power source. The load cell senses the pressure on the sensor panel and converts the pressure to an indication of weight. 
     In the embodiment shown in  FIGS. 6 and 7 , the device is placed on the palm of a hand as shown in  FIG. 6 . The hand is then placed under the handle  4  of the suitcase S as shown in  FIG. 7  and the suitcase is lifted so that the weight of the suitcase presses down on the sensor panel  31  on the upper surface of the device. This pressure is then transmitted as a weight on the liquid crystal display  32 . In the embodiment shown in  FIGS. 4 and 5 , instead of a liquid crystal display a series of lights  33 ,  34 ,  35 ,  36  representing recommended weights such as 20 kg, 30 kg, 40 kg or 50 kg are provided. The lights are preferably light emitting diodes. When the device is slid under the handle as shown in  FIG. 5 , the appropriate light  34  is illuminated showing that the suitcase is at least as shown in  FIG. 5  30 kg. Alternatively, the 20 kg, 40 kg or 50 kg lights  33 ,  35  or  36  can illuminate. The device  30  thus provides a ready and simple means of showing that a predetermined weight has been exceeded. The device of both of these embodiments is very small, runs on a small watch battery and takes up very little space. It is understood that the pressure sensitive panel would be one of a number of proprietary items that provide an electrical signal that is proportional to pressure. 
     In the fourth and fifth embodiments shown in  FIGS. 8 to 12 , a weighing device  40  is incorporated into the handle  4  of the suitcases. 
     In the exploded view of  FIG. 9 , the handle assembly  40  comprises an upper housing  41  with an aperture  42 . The housing is of an arcuate shape and supports end portions  43 ,  44 . The housing  41  is arranged to contain a circuit board assembly  45  that includes a pressure sensitive mechanism  46  and a liquid crystal readout  47 . The assembly would also incorporate a battery to power the weighing device. The assembly terminates on the underside with an arcuate displaceable pressure plate  48  that has a central spigot  49  that rides on the pressure sensitive mechanism  46  of the circuit board  45 . As shown in  FIGS. 10   a  and  10   b , the pressure plate  48  is pulled up into the assembly  40  against the pressure sensitive plate  46  as the handle H is gripped and the suitcase S lifted off the ground. In this way, the weight of the suitcase S is transferred through the pressure sensitive plate to be recorded and indicated at the LCD readout  47 . The final assembly of the handle is shown in  FIG. 8  from which it can be seen that the weighing device  40  is elegantly integrated into the design of a suitcase S so that travelers can buy a range of luggage each of which has its own built-in weighing device. 
     The assembly is molded in plastics and is light and substantially the same size as a conventional handle. In order to prolong the life of the batteries that power the unit, it is understood that an on/off switch may be provided somewhere on the handle to prevent use of the assembly whenever the suitcase is carried. 
     In the embodiment shown in  FIG. 11 , a very similar device  40  is incorporated except in this case instead of a single LCD readout  47 , four space lights  50 ,  51 ,  52 ,  53  are provided across the top of the handle H, each light representing a threshold weight such as 10 kg, 20 kg, 30 kg or 40 kg. 
     The load cell between the pressure plate  48  and the top of the handle  41  would send electrical signal to each light in dependence on the weight of the suitcase. 
     In the embodiment shown in  FIG. 12 , the load cell is replaced by a colored indicator  60  which locates in an aperture  61  in the external cover  62  of the handle. The colored indicator  60  is mounted on a support plate  63  and a pressure plate  64  has a single upstanding spigot  65  that acts against the underside of the colored indicator  60  in the same manner as the spigot acts on the load cell in the embodiment of  FIGS. 9 to 11 . However, in this embodiment the colored indicator is in the form of a disc that changes color under pressure and thus changes color proportional to the weight of the suitcase. As the pressure increases the color of the disc can be calibrated so that a change to a particular color indicates that the luggage weighs more than a particular threshold. 
     Other embodiments not illustrated also incorporate the use of pressure sensitive chemicals that change color in dependence on pressure. A card or plastics sheet could be provided with bands of such chemicals. The card or sheet could be placed under the handle of the suitcase and the suitcase lifted via the card or sheet. In this way, the weight of the suitcase would place pressure on the chemical laminate causing a change of color and the color would be calibrated to indicate whether airline thresholds have been exceeded. 
     The invention is also applicable to rucksacks or satchels especially those used by school children to carry their text books and laptops. The common practice of school children transporting excessively heavy loads in satchels and/or rucksacks is well known.