the invention is described in more detail hereinbelow by means of nonlimiting examples illustrated in the following figures , in which : fig1 illustrates a simplified view of a first example of a capsule according to the invention , fig2 illustrates the capsule from fig1 inside an extraction device in the rest mode , fig3 shows an enlarged view of the lower part of the capsule from fig2 , fig4 and 5 show perspective views of the capsule from fig2 and 3 , fig6 illustrates the capsule from fig1 inside an extraction device in the extraction mode , fig7 shows an enlarged view of the lower part of the capsule from fig6 , fig8 and 9 show perspective views of the capsule from fig6 and 7 , fig1 shows an embodiment of a relief having an attachment point , and fig1 shows different shapes of reliefs that can be used in the scope of the present invention . 1 . hollow body 2 . side wall 3 . injection face 4 . extraction wall 5 . self - piercing relief 6 . semipermeable element 7 . capsule housing 8 . annular element 9 . spike 10 . capsule holder 11 . serving , for example of coffee 12 . protuberance 13 . weakening zone 14 . extraction zone 15 . orifice fig1 to 5 illustrate one variant among others of a capsule according to the invention in the rest position . the capsule is composed of a hollow element 1 formed by a side wall 2 , an upper wall 3 and a lower wall 4 . the lower wall 4 is relatively rigid . it consists preferably of a biodegradable material . any form of material suitable for the envisioned , use can be used . if it is a biodegradable material , use can be made , for example , of a mixture comprising starch (& gt ; 70 %), fibers , proteins , lipids and at least one biodegradable resin . of course , the upper wall 3 and / or the side wall 2 can likewise be made of a biodegradable material . the outer face of the lower wall 4 has a self - piercing relief 5 in the form of a boss ( portion of a sphere ) in the example illustrated . this boss is in fact an overthickness of the lower wall 4 . around the boss there is disposed a peripheral zone , called weakening zone 13 , having a thickness less than the thickness of the rest of the lower wall 4 . inside the capsule , on the lower wall 4 , there is disposed an optional , for example knitted , semipermeable element 6 which allows liquid to pass through but holds back solid substances such as coffee grounds . still inside the capsule , the relief 5 is extended in the form of a spike 9 . the presence of the latter is optional . specifically , it makes it possible to keep the relief 5 centered when the latter moves toward the inside of the capsule . the optional annular element 8 is preferably formed from a material , for example paper , that makes it easier to remove the capsule once it has been used . its presence can prove useful if the , for example biodegradable , material which forms the capsule tends to adhere to the capsule holder when it is heated . fig6 to 9 illustrate the same capsule as the one shown in fig1 to 5 but in the extracting position , i . e . after the device around the capsule has been closed . in this configuration , the relief 5 has butted against a protuberance 12 located on the capsule holder 10 , the effect of this being to drive the relief 5 into the capsule , in this way breaking the weakening zone 13 . at this point , a passage for the liquid is formed , this passage being called the extraction zone 14 and having an annular form in the present case . it will be noted that the presence of the semipermeable element 6 keeps the solid material ( grounds ) inside the capsule . the liquid passing through the extraction zone passes through the capsule holder 10 through orifices 15 provided to this end . the liquid ( water - coffee mixture ) is finally collected in a cup ( not illustrated ) located under the capsule holder 10 . the invention is not limited to the example illustrated in fig1 to 9 . any form of relief can be envisioned . the same applies to the distribution and number of reliefs . fig1 and 11 show a number of variants among others . similarly , the base of the capsule holder 10 does not necessarily have a protuberance 12 . it is possible for it not to contain one , or conversely it can contain a plurality thereof , for example a number equal to the number of reliefs located on the extraction wall . advantageously , the weakening zone can be rendered asymmetrical with respect to the center of the relief , thereby minimizing the risk of the relief accidentally clogging the extraction zone . the extraction face 4 is advantageously coincident with the lower wall of the capsule . according to another variant of the invention ( not illustrated ), the extraction face is coincident with the upper wall of the capsule . similarly , see in particular fig1 , self - piercing reliefs can be located on that wall of the capsule which is opposite the extraction wall . in this case , the self - piercing reliefs ensure that water enters / is injected into the capsule . it should be noted , finally , that , the invention is not limited to a specific form of capsule . any form suitable for use ( for example conical , cylindrical or cubic ) can be used .
the invention relates to a capsule for preparing a beverage , for example coffee , including a hollow element for containing a metered amount of ground coffee , for example , said hollow element including a side wall , an injection surface and an extraction wall for extracting a mixture of water and coffee ; said capsule including at least one self - piercing raised pattern arranged on said extraction wall . the invention also relates to a device for using said capsule .