Abstract:
A die having a regular polyhedral form, at least one opening face of the die being hinged to an adjacent hinge face such that the at least one opening face can be opened by pressing on at least one pressure face adjacent to the at least one opening face.

Description:
RELATED APPLICATION 
   This is a §371 of International Application No. PCT/GB2005/002125, with an international filing date of May 27, 2005 (WO 2005/118091 A1, published Dec. 15, 2005), which is based on British Patent Application No. GB 0412176.0, filed Jun. 1, 2004. 
   TECHNICAL FIELD 
   The disclosure relates to a die having a regular polyhedral form. 
   BACKGROUND 
   It is well known to provide a polyhedral die in which when the die is thrown the probability of any of the faces facing upwards when the die come to rest is equal. U.S. Pat. No. B2-6,659,459 describes a die capable of being opened. However, an opening mechanism for the die comprises a button on the face to be opened first, which button destroys the symmetry of the die. 
   It could therefore be helpful to provide an openable die in which an object can be concealed and subsequently revealed to allow for novel and amusing games. 
   SUMMARY 
   I provide a die having a regular polyhedral form, at least one opening face of the die being hinged to an adjacent hinge face such that the at least one opening face can be opened by pressing on at least one further pressure face adjacent to the at least one face. 
   The at least one opening face and the at least one pressure face adjacent thereto may be provided with interacting cam surfaces to force the at least one opening outwards when the at least one pressure face is pressed inwards. 
   The die may comprise a latch for retaining the at least one opening face closed. Biasing means for biasing the at least one opening face outwards may be provided, such as a helical spring at the hinge with the hinge face. 
   The die may include a cavity for containing an object, opened when the opening face is opened and may be substantially hollow. 
   Representative embodiments of dice include dice substantially having the form of a cube, an octahedron, a dodecahedron and an icosahedron, for example. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the disclosure may be more readily understood, a specific embodiment thereof will now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which: 
       FIG. 1  is an exploded view of a die; 
       FIG. 2  is a perspective view showing the die of  FIG. 1  assembled and open; 
       FIG. 3  is a perspective view showing the die in the closed state; and 
       FIGS. 4   a  and  4   b  show schematically how the die is opened. 
   

   DETAILED DESCRIPTION 
   The figures show a die substantially in the form of a cube, but having circular faces and radiused corners and edges. In the following description, reference to the “front”, “back”, “sides” and “base” of the die are non-limiting and merely refer to certain faces of the die in the position shown in  FIGS. 1 ,  2  and  3 . 
     FIG. 1  shows three component parts of a die, namely a front-and-base  1 , a back-and-sides  2  and an opening face or lid  3 . 
   The front-and-base  1  comprises a base face  4  and a front face  5  at right angles thereto. Vertical sides of the front face  5  are provided with cam surfaces  6 , shown in  FIGS. 4   a  and  4   b . A tongue  7  extends inwardly from the upper edge of front face  5 . A flat projection  8  extends upwardly from the rear of the base face  4  and a recess  9  is formed in the upper edge of the projection. 
   The back-and-sides  2  comprises a back face  10  and pressure faces or side faces  11  at right angles thereto. The back face  10  has a horizontal elongate recess  12  in its upper edge. Ends of the recess  12  are provided with indentations  13 , only one of which is visible in  FIG. 1 . Side faces  11  have cam surfaces  14  as shown in  FIGS. 4   a  and  4   b.    
   The lid  3  comprises an axle  15  at a rear edge thereof (the lowermost edge as shown in  FIG. 1 ), the axle carrying a coil spring  16 . Ends of the axle are formed as hinge pins  17 . A latch plate  18  depends from the front edge of lid  3  and comprises a hole  19 . 
     FIG. 2  shows the die in its assembled state. The die is hollow and an object, such as a prize in the form of a toy, charm, trophy or the like, can be inserted into the die. Hinge pins  17  engage in indentations  13 . An end of spring  16  bears against the inside of back face  10  within recess  9  so that the spring biases lid  3  into the open position shown. 
     FIG. 3  shows the dice in the closed position in which tongue  7  engages in hole  19  so as to retain lid  3  closed. The die is symmetrical and the gaps between the parts  1 ,  2 ,  3  are disguised in that they follow the edges of the circular faces where possible. Where the edges of lid  3  cross the corners of the die, lines  20  are engraved to draw attention away from the joint. 
   As shown schematically in  FIGS. 4   a  and  4   b , pressure applied to side faces  11  causes cam surfaces  14  inwardly which in turn push cam surfaces  6  and front face  5  outwardly. This releases tongue  7  from hole  19 , freeing lid  3  which springs open to the position shown in  FIG. 2 . 
   It will be appreciated that games can be devised involving the die. In a simple game, using the die shown in the figures, the lid  3  is the “six” face of the die showing that throwing a “six” will win a player a prize concealed within the die. However, the die can bear symbols other than the numbers shown. 
   Alternative dice may have the form of an octahedron, a dodecahedron, an icosahedron or the like.