the beverage preparation machines 1 of fig1 and 2 each comprise a housing 2 containing the internal mechanisms of the machine such as a water reservoir , a pump , heating means and control means . the machine 1 of fig2 comprises a single brewer . the machine 1 of fig1 comprises a first brewer and a second brewer coupled together . each brewer of the machines 1 comprises a delivery head 3 provided towards an upper part of the housing 2 in which , in use , is received a cartridge containing one or more beverage ingredients . the delivery head or heads 3 are connected with a chassis of the machine 1 on assembly . the delivery heads 3 are preferably identical . beverage is dispensed from the brewer through an outlet spout 5 by pumping water from the reservoir of the brewer through the cartridge to form the beverage which is then directed through the outlet spout 5 into a cup 6 . as can be seen in fig1 , two outlet spouts 5 are provided for a machine with two brewers . as shown in fig3 , the delivery head 3 comprises a lower part 80 , an upper mechanism 90 and a cartridge guide 110 . some parts of the outer cowling of the delivery head have been omitted for clarity . in practice the outer cowling will comprise a number of mouldings shaped to contain and protect the internal components of the delivery head . the lower part 80 comprises a housing 81 formed from upper and lower mouldings . the housing 81 defines a motor cavity 88 towards a rear of the delivery head 3 , a piercer unit cavity 86 towards a front of the delivery head 3 and a barcode reader cavity 87 at a foremost portion of the delivery head 3 . a forward part of the upper surface of the housing 81 is provided with a flattened support surface 82 in which is located a piercer unit aperture 83 and a barcode window 84 . rearward of the support surface 82 the upper moulding is shaped to define an ejection chute 85 that is open to below the delivery head 3 . the upper mechanism 90 comprises a carriage frame 95 , a handle 92 , a clamping mechanism 93 , a lead screw 96 , and a motor 97 . the carriage frame 95 forms the core of the upper mechanism and provides a structural framework for the other components of the upper mechanism . the carriage frame 95 comprises an elongate frame extending from a front end 155 to a rear end 154 as shown in fig3 . the frame comprises two side members 151 and an upper member 152 joining the two side members 151 . the upper member 152 is provided with two upstanding webs 156 as most clearly shown in fig9 b . each side member 151 comprises an elongate side slot 106 and the upper member 152 comprises an elongate upper slot 153 as most clearly shown in fig5 . the carriage frame 95 is preferably formed from a single moulding and is symmetric about a midline of the delivery head 3 . the carriage frame 95 is pivoted to the lower part 80 by a pair of hinges 98 formed on the upstanding webs 156 at pivot points 150 as most clearly seen in fig9 b to 9 d . the hinges 98 are offset from the upper surface of the lower part 80 and positioned above the level of the support surface 82 . as most clearly shown in fig9 a by omission of certain parts of the housing 91 , the hinges 98 may comprise a cog 157 having teeth 158 which engage with a damping member during pivoting of the carriage frame 95 to thereby provide control over the pivoting speed of the carriage frame 95 . for example , the damping member may act to ensure that if the handle 92 of the delivery head 3 is released when the carriage frame 95 is in the raised position then the carriage frame 95 pivots downwardly in a controlled manner rather than free - falling into contact with the lower part 80 . the damping member may comprise a cog suitable for engaging the cog 157 and a damper , such as a rotatable vane , movable within a viscous damping fluid such as oil . the handle 92 is connected to the carriage frame 95 and extends around a front of the delivery head 3 . the handle 92 is pivotably connected to the carriage frame 95 by a mechanism such that with the carriage frame 95 in a lowered position the handle 92 can be depressed to engage hooks provided on the handle 92 with bosses provided on the lower part 80 in order to securely hold the carriage frame in the lowered position . an example of such a mechanism is described in ep1440644 . however , such a mechanism is not relevant to the present invention . the clamping mechanism 93 comprises a cup - shaped clamp member 100 and a cup - shaped socket 94 . the clamp member 100 is provided with a central spigot 101 . a plurality of flexible protrusions 102 are provided on an exterior of the clamp member 101 which engage with an inwardly - directed flange 103 of the socket 94 so as to retain the clamp member 100 fixedly within the socket 94 on assembly . the socket 94 is provided on an upper surface with a cylindrical member 104 in which is seated a threaded nut 105 . the threaded nut 105 is engaged on the lead screw 96 . the socket 94 of the clamping mechanism 93 is also provided with a pair of bosses or similar which are engaged in , and slidable along the side slots 106 of the carriage frame 95 so as to maintain correct orientation of the socket 94 on operation of the lead screw 96 . consequently , rotation of the lead screw 96 can be used to move the socket 94 , and hence the clamp member 100 reciprocally along the longitudinal axis of the upper mechanism 90 from the front end 155 to the rear end 154 of the carriage frame 95 as will be described below when the operation of the delivery head 3 is discussed . as best shown in fig8 a and 8 b the socket 94 further comprises a pair of tail pieces 108 which extend rearwardly from either side of the cup - shaped body of the socket 94 . the tail pieces 108 are each provided with a pin 107 at or near a distal end thereof , the use of which will be described below . the lead screw 96 is mounted to the carriage frame 95 . the lead screw 96 is located towards a top of the carriage frame 95 in the opening provided by the upper slot 153 as shown in fig5 . thus , the lead screw 96 extends above the socket 94 and extends along the longitudinal axis of the upper mechanism 90 from the rear end 154 to the front end 155 of the carriage frame 95 . the motor 97 is operatively connected to a rear end of the lead screw 96 and is able to rotate the lead screw 96 both clockwise and counter - clockwise . as shown , the motor 97 is mounted to the carriage frame 95 and transverse the longitudinal axis of the upper mechanism 90 to save space and is connected to the lead screw 96 by means of a suitable gear arrangement such as bevel gears . the cartridge guide 110 is located inbetween the lower part 80 and the upper mechanism 90 . the cartridge guide 110 rests on and is slidable relative to the lower part 80 whilst being operatively interconnected with the upper mechanism 90 as described below . the cartridge guide 110 comprises an annular member 111 and two vertically extending webs 113 . the annular member 111 and webs 113 are formed as a single moulding from , for example , a plastics material . the annular member 111 comprises a ring defining an aperture 112 shaped to receive a cartridge 70 . the lower face of the cartridge guide 110 rests on the support surface 82 . whilst the aperture 112 closely conforms to the shape of the cartridge 70 in order to enable precise orientation and placement of the cartridge , it is slightly larger than the cartridge 70 such that a cartridge 70 placed within the aperture 112 rests on the support surface 82 of the lower part 80 rather than on the cartridge guide 110 itself . the aperture 112 is shaped also to accommodate a handle portion 71 of the cartridge 70 as shown in fig4 . the handle 71 is thereby orientated to a front of the delivery head 3 and positioned symmetrically on the midline of the delivery head 3 . the webs 113 are located on each side of the cartridge guide 110 and , as best shown in fig8 a and 8 b , are each provided with a slot 114 of arcuate form in which , on assembly , the pins 107 of the socket 94 are slidingly received . thus , the cartridge guide 110 and the clamping mechanism are interconnected . each slot 114 comprises a first portion 115 in the shape of an arc having a centre of rotation coincident with the pivot point 150 of the clamping mechanism 93 . each slot 114 also comprises a second portion 116 in the shape of an arc whose instantaneous centre of curvature is not co - incident with the pivot point 150 . the function of the slot 114 will be described below . the delivery head 3 further comprises a barcode reader 120 and a piercing mechanism 119 . the barcode reader 120 is located in the barcode reader cavity 87 and is orientated to be able to transmit and receive signals through the barcode window 84 . the piercing mechanism 119 comprises a piercer unit 121 , a motor 130 , a lead screw 131 and a linkage mechanism 133 . the piercing mechanism 119 is operative to raise and lower the piercer unit 121 . the piercer unit 121 is located in the piercer unit cavity 86 of the lower part 80 . as shown in fig1 a to 12 c , the piercer unit 121 comprises a body 122 having mounted therein an inlet piercer 123 and an outlet piercer 124 . the body 122 is provided with a conduit 125 linking the inlet piercer 123 with a fluid inlet 126 of the body 122 . the fluid inlet 126 is coupled by pipework to a supply of water on assembly of the delivery head with the remainder of the machine 1 . a seal member 128 is located on an upper face of the body 122 surrounding the inlet piercer 123 and the outlet piercer 124 . the seal member 128 is provided with raised annular portions 129 surrounding the piercing element of the inlet piercer 123 and the piercing element of the outlet piercer 124 . the piercer unit cavity 86 is also provided with a spout chute 89 as shown in fig3 into which the piercer unit 121 extends . the spout chute 89 acts as a funnel to channel beverage discharged through the outlet piercer 124 to the outlet spout 5 located at a bottom of the spout chute 89 . the motor 130 is located at a rear of the delivery head 3 remote from the piercer unit 121 . the motor 130 is orientated generally in line with a longitudinal axis of the lower part 80 but is angled downwardly slightly below the horizontal . the motor 130 is coupled to the lead screw 131 by means of a threaded , generally u - shaped , rear coupling member 138 as most clearly seen in fig1 . a distal end of the lead screw 131 is provided with an end stop . the motor 130 is able to rotate the lead screw 131 both clockwise and counter - clockwise in order to move the rear coupling member 138 reciprocally forwards and backwards relative to the lower part 80 . as shown in fig1 , the linkage mechanism 133 comprises a u - shaped primary link 135 having a pair of forward - extending arms 135 a , a pair of secondary links 136 , a pair of tertiary links 137 , the rear coupling member 138 and a forward coupling member 149 . the linkage mechanism is mounted to the lower part 80 by means of a rear mounting plate 160 , a front mounting plate 161 and two side mounting plates 162 which are all securely mounted to an underside of the upper moulding of the lower part 80 . a pair of first pivot points 139 are provided by the side mounting plates 162 . a pair of second pivot points 140 are provided by the front mounting plate 161 . as most clearly shown in fig1 , 11 a and 11 b , the u - shaped primary link 135 is rotatably coupled at a rear end to the rear coupling member 138 . the forward coupling member 149 comprises a generally u - shaped member having two arms 146 and an interconnecting bridge 147 . the distal ends of the arms 146 are rotatably coupled to the first pivot points 139 . the secondary links 136 are rotatably connected to the primary link arms 135 a at third pivot points 141 such that a forward end of each primary link arm 135 a is connected to a rear end of the respective secondary link 136 . the opposite end of each secondary link 136 is rotatably coupled to the forward coupling member 149 at fourth pivot points 148 . the tertiary links 137 are connected between the third pivot points 141 ( where the primary link arms 135 a and secondary links 136 are coupled ) and the second pivot points 140 on the front mounting plate 161 . the piercing unit 121 is rigidly mounted to the interconnecting bridge 147 of forward coupling member 149 as shown in fig1 alternatively the piercer unit 121 could be formed as one piece with the front coupling member 149 . as most clearly shown in fig1 , the linkage mechanism 133 transfers motive force from the motor 130 at the rear of the delivery head 3 to a front of the delivery head 3 . in addition , by using pairs of primary link arms 135 a , secondary links 136 and tertiary links 137 as well as u - shaped members 135 , 149 the linkage mechanism extends around the ejection chute 85 without impeding the chute as shown in fig5 . operation of the piercing mechanism 119 will be described below . the beverage preparation machine also comprises a controller for controlling operation of the machine including operation of components of each delivery head 3 such as the motors 95 , 130 , and the barcode reader 120 . the delivery head 3 may also be provided with interlock or sensing devices linked to the controller to provide data to the controller on the position of the socket 94 on its lead screw 96 , the position of the piercing mechanism 119 and the position of the upper mechanism 90 , for example whether the upper mechanism 90 is in the closed position . typically an interlock is provided to confirm closure of the handle 92 when the upper mechanism 90 is in the lowered position . operation of the delivery head 3 is prevented when this interlock indicates that the handle 92 is opened . as an alternative to providing an interlock on the lead screw 96 to indicate the position of the socket 94 current sensing control may be used . in current sensing the current drawn by the motor 97 is monitored and the controller interprets an increase in the drawn current above a pre - set threshold to be indicative of the socket 94 having reached one of its end stops at either the front end 155 or rear end 154 of the carriage frame 95 . in use , the delivery head 3 is first opened to allow insertion of a cartridge 70 of the type having a bowl - shaped upper portion 76 sealed by a flexible lower membrane 77 around a peripheral flange 78 by moving the upper mechanism 90 into the raised position as shown in fig3 . opening of the upper mechanism is achieved by first opening the handle 92 to disengage the hooks from the bosses of the lower part 80 and then lifting the handle 92 . as shown in fig3 and in fig9 a , in the raised position of the upper mechanism 90 , the cartridge guide 110 is positioned in a forward - most position to ease loading of the cartridge 70 and the clamping member 100 is raised as part of the upper mechanism 90 . the cartridge guide 110 is thus positioned because of the interaction of the pins 107 of the tail pieces 108 in the slots 114 of the cartridge guide 110 . in particular in the raised position each pin 107 is moved to a top of the first portion 115 of the slot 114 as shown in fig9 a . the cartridge 70 is then inserted into the aperture 112 of the cartridge guide 110 such that the cartridge 70 rests on the support surface 82 as shown in fig4 . in fig4 the delivery head 3 is shown with a cartridge 70 having a relatively shallow profile . the handle portion 71 of the cartridge 70 is aligned towards a front of the delivery head 3 and lies on the midline of the delivery head 3 . the upper mechanism 90 is then closed into the position shown in fig5 by pressing down on the handle 92 . closure of the upper mechanism 90 causes the cartridge guide 110 and the cartridge 70 to slide rearwardly over the support surface 82 into a dispensing position wherein the cartridge 70 is correctly aligned with the piercer aperture 83 and the barcode window 84 . the rearward movement of the cartridge guide 110 is caused by the interaction of the pins 107 and slots 114 . as shown in fig8 a , 8 b and fig9 a to 9 d downward rotation of the upper mechanism 90 causes the clamping mechanism 93 also to rotate downwardly moving the pins 107 first along the first portion 115 of the slots 114 and then along the second portion 116 . movement of the pins 107 along the first portion 115 of the slots to the position shown in fig9 c does not cause any movement of the cartridge guide 110 since the centre of curvature of the first portion 115 is coincident with the point of rotation of the clamping mechanism 93 . however , further downward rotation of the clamping mechanism 93 does cause rearward sliding of the cartridge guide 110 due to the pins 107 bearing against a rearmost face of the slots 114 to thereby force the cartridge guide 110 to move to accommodate the pin &# 39 ; s movement into the position shown in fig9 d . in the closed position of the clamping mechanism 93 the cartridge guide 110 has moved in a rearward direction by between 7 . 8 and 10 mm . in the closed position the spigot 101 of the clamping member 100 is engaged in a relatively shallow central well 75 formed in the upper portion 76 of the cartridge 70 . the clamping member 100 is also provided with a formation 79 aligned with an inlet region of the cartridge 100 . the lower rim of the clamping member 100 is aligned with and is designed to make a light contact with the peripheral flange 78 of the cartridge 70 in the closed position . thus , in the closed or clamped , position the clamping member 100 applies a clamping force on the cartridge 70 . this force is mainly applied to the central region of the cartridge 70 by the spigot 101 and to the inlet region of the cartridge 70 by the formation 79 . however , if required the lower rim of the clamping member 100 may apply a relatively small force to the peripheral flange 78 . at this point the piercer unit 121 is still lowered . therefore the force applied to the cartridge 70 urges the cartridge into contact with the support surface 82 . thus , the lower membrane 77 carries some of the applied load in the area immediately surrounding the piercer aperture 83 . in addition , the remainder of the load applied to the cartridge 70 is carried through the peripheral flange 78 where it contacts the support surface 82 . closure of the upper mechanism 90 also triggers operation of the barcode reader 120 to read the barcode on the cartridge 70 by transmitting through the barcode window 84 . the received detected signal is then fed to the controller which thereby determines the correct dispense parameters for the inserted cartridge , such as water temperature , volume , steeping time , etc . opening of the upper mechanism 90 after a dispense cycle and ejection have taken place results in a reversal of the movement of the cartridge guide 110 described above . a particular advantage of this movement of the cartridge guide 110 is to allow accommodation of cartridges having a relatively deep profile , such as the type of cartridge 70 shown in fig9 a to 9 d . as shown in fig9 a to 9 d maintaining the cartridge guide 110 in the loading position of fig9 a until the clamping mechanism 93 has rotated partially down to the point shown in fig9 c allows the lower rim of the clamping member 100 to clear the upper rear point 73 of the cartridge 70 . the subsequent rearward movement of the cartridge 70 allows for a clamping member 100 that closely conforms to the diameter of the cartridge to be used whilst avoiding fouling of the clamping member &# 39 ; s rim on a front face 74 of the cartridge or of the spigot 101 on the sides of the relatively deep central well 75 of the cartridge 70 . in this way the size of the clamping member 100 is minimised without requiring a substantially vertical movement of the clamping mechanism 93 to be used to allow insertion of cartridges of varying depth . as shown in fig5 , at this point the piercer unit 121 is in the lowered position such that the inlet piercer 123 and outlet piercer 124 are fully below the level of the support surface 82 . on receipt of a start command from the user ( by for example , pressing a start / stop button ), the controller of the machine 1 operates the motor 130 to raise the piercing mechanism 119 into the raised position shown in fig6 such that the inlet piercer 123 and outlet piercer 124 are raised proud of the level of the support surface 82 . in the raised position the piercer unit 121 is raised to the point where the seal member 128 is orientated substantially horizontally with the general level of the seal member 128 being level with the support surface 82 . however , in this position the raised annular portions 129 of the seal member 128 lie slightly above the level of the support surface 82 . in this way the raised annular portions 129 are able to distort slightly and thereby tension the flexible lower membrane 77 of the cartridge 70 . the peripheral flange 78 of the cartridge 70 remains in contact with the support surface 82 due to the constraining contact of the lower rim of the clamping member 100 . in addition , the upward movement of the piercer unit 121 urges the cartridge 70 more tightly against the spigot 101 and the formation 79 of the clamping member 100 to increase the clamping force which holds the cartridge 70 in position between the clamping member 100 and the piercer unit 121 . thus , the combination of the action of the clamping member 100 and the piercer unit 121 creates a minimum clamping force of 30n at the inlet of the cartridge and a force of between 75 and 130n at the outlet . the movement of the piercing mechanism 119 from lowered to raised position is most clearly seen in fig1 a and 11 b and involves a rotation of the piercer unit 121 about its pivot point of between 5 and 10 degrees and preferably greater than 7 . 5 degrees . on operation of the motor 130 , the rear coupling member 138 is moved forwards by approximately 20 mm by rotation of the lead screw 131 . as a result of the coupling of the rear coupling member 138 with the primary link 135 the primary link 135 is moved substantially in a direction in line with the longitudinal axis of the primary link although this may be accompanied by a slight rotational movement of the primary link 135 relative to the rear coupling member 138 . at the same time the primary link arms 135 a push on the lower ends of the secondary links 136 . due to the constraint of the tertiary links 137 , which couple the primary link arms 135 a and the secondary links 136 to the second pivot points 140 , the pushing movement of the primary link arms 135 a causes the secondary links 136 to rotate in a clockwise sense as viewed in fig1 b . this rotation results in upward rotation of the front coupling member 149 due to the coupling of the secondary links 136 to the front coupling member 149 and the coupling of the arms 148 of the front coupling member 149 to the first pivot points 139 of the side mounting plates 162 . upward rotation of the front coupling member 149 consequently results in upward rotation of the piercer unit 121 due to the rigid connection of the piercer unit 121 to the front coupling member 149 . in the raised position , the tertiary links 137 are substantially vertical and also aligned with the secondary links 136 which are also vertically aligned . in this position the secondary and tertiary links are best able to resist the downward loads applied by the clamping member 100 to the cartridge 70 . the movement of the secondary and tertiary links also acts in the manner of a toggle clamp wherein the secondary and tertiary links snap into , and have a propensity to remain in , the position of fig1 b until a positive retraction force is applied by the motor 130 . raising of the piercing mechanism 119 causes piercing of the cartridge 70 by the inlet piercer 123 and the outlet piercer 124 to form respectively an inlet and an outlet in the underside of the cartridge 70 . once the controller detects that the piercer unit 121 is in the raised position dispensation of a beverage from the cartridge 70 begins . as with operation of the lead screw current sensing of the motor 130 may be used by the controller to determine the position of the piercer unit 121 . heated water is channelled from the fluid inlet 126 through the conduit 125 and inlet piercer 123 and into the cartridge . the resultant beverage is discharged through the outlet piercer 124 , spout chute 89 and out of outlet 5 into a waiting receptacle 6 . once dispensation has stopped the piercer unit 121 is lowered by reversing the operation described above by operating the motor 130 in a reverse direction . this clears the inlet piercer 123 and the outlet piercer 124 out of the ejection path of the cartridge 70 and also removes a portion of the loading applied to the cartridge 70 . the controller then operates motor 97 to eject the cartridge 70 by movement of the cartridge 70 to an ejection position . operation of the motor 97 rotates the lead screw 96 causing the clamping socket 94 and clamping member 100 to slide rearwards into the position shown in fig7 . the clamping member 100 moves the cartridge 70 along with it thereby dragging the cartridge 70 over the ejection chute 85 . during this movement the cartridge 70 is still under some loading from the socket 94 of the upper mechanism 90 . once the cartridge 70 is substantially or wholly aligned with the chute 85 it falls under gravity down the chute 85 into a waste bin in a lower part of the machine 1 . it is to be noted that during this movement the outer part of the housing 91 of the upper mechanism 90 remains stationary such that the motion of the clamping mechanism 93 remains internal to the delivery head 3 . a particular advantage is that the delivery head 3 does not need to be opened in order to eject the cartridge 70 . in addition , the clamping mechanism 93 affects not only clamping of the cartridge 70 during dispensation of beverage but also ejection of the cartridge 70 . the motor 97 is then reversed to move the clamping mechanism 93 back into the forward position ready for the next dispensing cycle . optionally a steam purge may be used to clean the piercer unit cavity 86 , support surface 82 , and clamping member 100 . steam is directed through the inlet piercer 123 . the steam purge may be carried out with the piercer body 121 in the raised or lowered position . in addition , it may be carried out automatically after each dispensation cycle and or carried out from time to time under either manual user control or automatic control of the controller . a steam purge may also be used during the dispensation cycle when the cartridge 70 is in the dispensation position to dry out the cartridge 70 and to help drive out any remaining liquid in the cartridge 70 .
a delivery head for a beverage preparation machine comprising a clamping member and a base , wherein the clamping member is movable relative to the base , the clamping member being sequentially movable from an open position , through a clamping position to an ejection position , the clamping position being intermediate the open position and the ejection position , in the open position the clamping member being positioned to enable loading of a cartridge into the delivery head , the clamping member being clampable against said cartridge in the clamping position , the clamping member being movable relative to the base from the clamping position to the ejection position to enable transportation and ejection of said cartridge .