Bicycle shoe to pedal cleat shim and mounting

An improved bicycle shoe to pedal cleat shim comprises a shim body with mating faces on opposite sides of the shim body, each for mating with another surface, each mating face having two or more shim to shim keying features. There is also a cleat with two or more cleat to shim keying features. There is also a mounting screw with a convex curved seating face and a washer with a substantially matching mating concave curved seating face. The screw has one or more grooves incrementally cut along the length of the thread. The shim has thickness marks adjacent to the screw relief pocket on the shim. There is also a cleat with the cleat to shoe/shim mating face having one or more friction inducing pads that comprise a pocket to allow space for friction material to flow when the cleat is mated to the shoe, shim or another shim.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase application under 35 U.S.C. § 371 of International Application No. PCT/AU2015/050563 filed Sep. 19, 2015, which claims foreign priority to Australian Patent Application No. 2014903768 filed Sep. 20, 2014, Australian Patent Application No. 2015901478 filed Apr. 24, 2015, and Australian Patent Application No. 2015901479 filed Apr. 24, 2015, the entire disclosures of which are hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to shims used to adjust the angle and or height offset of a cyclist's shoe relative to a pedal cleat of a bicycle shoe and to mounting of the shoe to the cleat.

BACKGROUND

As people often have slightly asymmetrical bodies there is a need to adjust the angle and offset of a bicycle rider's foot in relation to the bicycle pedal. When the rider is using a bicycle shoe, cleat and pedal combination one way of adjusting to suit the rider is to move the cleat forward, backward, left and right and also rotating the cleat. To achieve this cleats are often made with slots and washers that are slotted to fit in the cleat slots to allow for the movement. Another option of adjusting to suit the rider is to shim the cleat angle and offset from the pedal. Shims need to fit both the left and right shoe to cleat interface which is often curved. To achieve this shims are often made of thin flexible plastic stacked to create the desired offset and angle. Additionally the cleat and shim stacks are susceptible to movement caused by slippage between the screw to washer, washer to cleat, shoe to cleat, shim to shoe, shim to shim and shim to cleat interfaces. This in turn allows the screws to loosen and thus altering the rider's settings. It also allows for damage to the shoe from excessive torque movement of the screws. To alleviate this shims are often glued in place with double sided tape.

Additionally when a shim stack is required it is often difficult to acquire the correct length screws. To alleviate this screw kits are often provided with many multiple different lengths screws.

An aspect of the present invention has been devised in order to provide an improved interface between the shoe to shim, shim to shim and shim to cleat interfaces to hold the shim stack firmly in place thereby alleviating undesirable slipping.

An aspect of the present invention has been devised in order to provide an improved interface between the screw and washer, and washer to cleat interfaces to hold the cleat or cleat and shim stack firmly in place thereby alleviating undesirable slipping. An offset washer thus allowing for adjustments in location of the cleat or cleat and shim pack whilst maintaining surface area between the washer and cleat. An adjustable length screw thus reducing the number of screws required in the kits. Dual use rubber-like friction inducing pads/pins on the cleat to reduce slippage between the cleat and shoe, or the cleat and shim. Rubber-like friction inducing pads on the cleat reduce slippage between the cleat and shoe, or the cleat and shim.

SUMMARY OF THE INVENTION

According to the present invention there is provided an improved bicycle shoe to pedal cleat shim comprising a shim body with mating faces on opposite sides of the shim body, each for mating with another surface, each mating face having two or more shim to shim keying features.

In an embodiment the mating faces are either parallel or angled with respect to each other.

In an embodiment the other surface is one of the following: a pedal cleat, a bicycle shoe, or another mating surface of another shim.

In an embodiment the faces further comprise one or more friction inducing pads.

In an embodiment the faces further comprise a non-slip texture on the remaining surface of the mating faces.

In an embodiment the keying features comprise two or more pins offset to the same side of a heel to toe centreline of the shim on one of the mating faces.

In an embodiment the keying features comprise two or more sockets on the other mating face for receiving pins of another shim, wherein the sockets are to the same side of the heel to toe centreline as the pins.

In an embodiment the keying features comprise two or more sockets on the same mating face as the face with the pins and are for receiving pins of another shim, wherein the sockets are on the opposite side of the heel to toe centreline as the pins.

In an embodiment the keying features comprise two or more sockets on the other mating face for receiving pins of another shim, wherein the sockets are to the same side of the heel to toe centreline as the pins.

In an embodiment the keying features comprise two or more sockets on the other mating face for receiving pins of another shim, wherein the sockets are spaced symmetrically about the heel to toe centreline of the shim.

In an embodiment each sockets is one of: a socket through the shim, back to back sockets or a socket on the other side of a pin.

In an embodiment the shim is stackable on another shim, wherein each pin of the shim is on the same side of the centre line, and the pins of the other shim are received in the sockets of the first shim.

In an embodiment the shim is stackable with another shim, wherein each pin of the first shim is on the opposite side of the pins of the other shim and all of the pins are receiving in respective sockets.

In an embodiment at least one of the pins of the shim is round. In an embodiment at least one of the sockets is round. In an embodiment at least one of the sockets is a rounded rectangle. In an embodiment the length of the rectangle is substantially parallel to the centreline of the shim. In an embodiment the length of the rectangle is aligned with a line through the pins.

In an embodiment each pin is positioned in line with a corresponding one of the sockets of the other mating face on the same side of centreline of the shim and is connected to the shim body by a thin section of material parallel to the mating face.

In an embodiment each pin is readily removable. In an embodiment each pin is susceptible to removable by application of a force substantially perpendicular to the mating face, or by application of a torque applying force to the pin.

In an embodiment each friction inducing pad comprises a protrusion above the mating faces. In an embodiment each friction inducing pad comprises a pocket to allow space for the friction material to flow when the shim is mated to the shoe, cleat or another shim.

In an embodiment the friction inducing pads are located within the cleat footprint and avoid pockets in the cleat. In an embodiment the friction inducing pads are rubber-like. In an embodiment the friction inducing pads are formed of a Thermoplastic Elastomer.

In an embodiment the non-slip texture is formed of pitting in the surface of the remaining surface of the shim faces.

In an embodiment the non-slip texture is formed by a thin rubberised surface to the shim faces that will substantially avoid creep under compression, but is flexible longitudinally.

According to the present invention there is provided an improved bicycle shoe to pedal cleat shim comprising a shim body with mating faces on opposite sides of the shim body, each for mating with another surface, each mating face having one or more friction inducing pads.

According to another aspect of the present invention there is provided a stack of improved bicycle shoe to pedal cleat shims comprising at least two shims, where each shim comprises a shim body with mating faces on opposite sides of the shim body, each for mating with another surface, each mating face having two or more shim to shim keying features.

In an embodiment the mating faces of each shim are either parallel or angled with respect to each other and collectively the external faces of the stack contact a pedal cleat and a bicycle shoe, respectively, such that the offset and angle between the shoe and the cleat is adjusted by the stack.

In an embodiment the keying features of at least one of the shims comprises two or more pins offset to the same side of a heel to toe centreline of the shim on one of the mating faces and one of the following is the case: each pin of at least two of the shims is on the same side of the centre line, and the pins of the other shim are received in the sockets of the first shim; oreach pin of a first of the shims is on the opposite side of the pins of another of the shims and all of the pins are received in respective sockets.

According to the present invention there is provided an improved bicycle shoe to pedal cleat mounting comprising a screw with a convex curved seating face and a washer with a substantially matching mating concave curved seating face. This allows for the seating face of the washer to be out of square to the screw hole centreline without applying a torque load to the head of the screw and point contact to the washer.

In an embodiment the curves have constant radii of curvature. In an embodiment the radii are substantially the same.

In an embodiment a centreline of the washer curved face (washer seat) is offset to the washer centreline, allowing for the washer to be turned in a slot of the cleat permitting greater movement of the cleat whilst maintaining surface area between the washer and cleat body, and keeping the load force over the centre point of the washer to screw interface.

In an embodiment the centreline of the washer seat and the washer body are the same.

In an embodiment the washer may be a plate having two or more seats pitched to match the screw holes of the mating shoe to accommodate multiple screws.

In an embodiment the washer is generally a polygon, preferably rectangular, in shape.

In an embodiment the washer is generally trapezoidal in shape.

In an embodiment the washer is round in shape giving the washer to cleat more movement without having to remove then turn the washer.

In an embodiment the washer has protrusions to bite into the cleat body so the washer is less likely to slip.

In an embodiment the screw material is Alloy steel. In an embodiment the screw material is Titanium. In an embodiment the washer material is High Carbon steel. In an embodiment the washer material is Titanium.

In an embodiment screw comprises one or more grooves cut along the length of the thread for creating marks for the screw to be cut to length whilst maintaining a clean thread start.

According to the present invention there is provided an improved bicycle shoe to pedal cleat mounting comprising a screw with one or more grooves incrementally cut along the length of the thread thus creating marks for the screw to be cut to length whilst maintaining a clean thread start.

In an embodiment the grooves incrementally cut along the length of the screw are coloured, preferably in a contrasting colour to the screw, thus making them more visible.

In an embodiment the screw material is Alloy steel. In an embodiment the screw material is Titanium.

According to the present invention there is provided an improved bicycle shoe to pedal cleat mounting comprising a shim with thickness marks adjacent to the screw relief pocket on the shim so the length of screw required can be easily calculated.

In an embodiment the shim angle is marked on the shim for easy identification and so the total angle of the stack can be easily calculated.

According to the present invention there is provided an improved bicycle shoe to pedal cleat mounting comprising a cleat with the cleat to shoe/shim mating face having one or more friction inducing pads that comprises a pocket to allow space for friction material flow when the cleat is mated to the shoe, shim or another shim.

In an embodiment the friction inducing pads are formed of a Thermoplastic Elastomer.

According to the present invention there is provided an improved bicycle shoe to pedal cleat mounting comprising a cleat with the cleat to shoe or shim mating face having two or more cleat to shim keying features.

In an embodiment the keying features comprise two or more pins.

In an embodiment the keying features comprise two or more sockets.

In an embodiment the keying feature is dual use being made from rubber-like material to create friction inducing pads or pins. Each pad or pin is readily removable.

In an embodiment the friction inducing pads comprise a pocket to allow space for the friction material to flow when the cleat is mated to the shoe, shim or another shim.

In an embodiment each pad or pin is susceptible to removable by application of a cutting force substantially parallel to the mating face.

In an embodiment the dual use keying feature or friction inducing pads are formed of a Thermoplastic Elastomer

In this specification the terms “comprising” or “comprises” are used inclusively and not exclusively or exhaustively.

Any references to documents that are made in this specification are not intended to be an admission that the information contained in those documents form part of the common general knowledge known to a person skilled in the field of the invention, unless explicitly stated as such.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Referring toFIGS. 1 to 10there is shown a 2 mm thick parallel improved bicycle shoe to pedal cleat shim100comprising a shim body102having opposed mating faces104and106. The preferred base material for the shim body102is Polyamide (PA), however other materials can also be used.

The faces104and106are parallel for this shim100. The shim100is generally “heart” shaped or “fox” shaped with a narrower end at the bottom of the figure (toe end) and with lobes or “ears” at the top ofFIG. 1(heel end). The body102may have apertures there through. Extending heel to toe wise is a centre line101. The body102is symmetrical about the centre line101.

The face104comprises shim keying features. The shim to shim keying is of such a design as to allow for assembly of shim to shim with the keying features either facing each other or facing the same direction. In this embodiment the keying features are in the form of pins112and sockets114and115, and132and134. Preferably there are only two pins112offset to the same side of the centreline101. Adding more may increase the chance of misalignment and thus increase manufacturing costs and increase the reject rate. The face106comprises shim keying features in the form of sockets114,115,132and134. Face106does not have pins.

The faces104and106also comprise one or more friction inducing pads110. The faces104and106further comprise a non-slip texture on their respective remaining surface area.

The sockets132and134are for receiving pins of another shim and are to the same side of the centreline101as the pins112. The sockets114and115of face104are for receiving pins of another shim and the sockets114and115are on the opposite side of the centreline101as the pins112.

The sockets114and115of face106are for receiving pins of another shim and the sockets114and115are on the opposite side of and are spaced symmetrically about the centreline101as the sockets132and134.

Sockets114and115may be back to back sockets, but are preferably formed from a hole through the shim body102. Sockets132and134are on the other side of the body102for the correspondingly positioned pin112on the face104.

In this embodiment the pins112are round and the sockets115and132are round. Sockets114and134are elongate and are preferably formed of a rectangle adapted with rounded corners or rounded ends. In an embodiment the length of the rectangle is substantially parallel to the centreline101. In an embodiment the length of the rectangle is aligned with a line through the pins112.

Each friction inducing pad110comprises a protrusion122above the mating faces104and106. In an embodiment each of the friction inducing pads comprises a pocket124. The friction inducing pads are of such a design to allow friction material to protrude above the mating faces and also have pockets to allow space for the friction material flow when the shim100is mated to the shoe, cleat or another shim, thus allowing the shim to resist forces applied parallel to the mating face with minimum force at 90 degrees to the mating face.

In an embodiment the friction inducing pads110are located within the cleat footprint and avoid pockets in the cleat. In an embodiment the friction inducing pads110are rubber-like. In an embodiment the friction inducing pads are formed of a Thermoplastic Elastomer, however other materials can also be used.

In an embodiment the non-slip texture is formed with pitting in the surface of the remaining surface of the shim faces104and106.

In an embodiment the non-slip texture is formed by a thin rubberised surface to the shim faces104and106that will substantially avoid creep under compression, but is flexible longitudinally to accommodate the shoe and cleat interfaces. The preferred rubberised friction inducing material is Thermoplastic Elastomer (TPE), however other materials can also be used.

In an embodiment the shim is stackable on another shim. When assembling the stack, it is optimal for the pins to face away from the mating face on the shoe. Preferably the first shim is oriented so that each pin112of the first shim is on the opposite side of the pins of the other shim and all of the pins are receiving in respective sockets.

However in some cases each pin112of the shim is on the same side of the centre line101, and the pins212of the other shim(s) are received in the sockets of the first shim.

In an embodiment each pin112is connected to the shim body104by a thin section136of material parallel to the mating face104so that it is readily removable by application of a force substantially perpendicular to the mating face104, or by application of a torque applying force to the pin112. In circumstances such as when the end pin comes in contact with the shoe or the cleat, the pins are of such a design to allow for easy removal of the pin112by means of breaking the pin112and removing it from the shim100.

The pin112may also be drilled out using the corresponding socket as a guide. For optimal configuration a corresponding socket would be applied to the shoe and cleat.

Other forms of improved bicycle shoe to pedal cleat shim may be any thickness, such as but not limited to 1 mm, 2 mm, 3 mm and 5 mm and any angle such as 1 Degree, 2 Degree, 3 Degree and 5 Degree with 1 mm to 2 mm thickness being optimal to allow the shims to flex to fit the shape of the shoe to cleat interface.

Further example of shims according to embodiments of the invention and stacks of such shims are described in the examples below.

FIGS. 11 to 15show a 2 mm thick, 2 Degree angled shim140. The shim140is similar to shim100, with the principal difference being the angle between the faces104and106is 2 Degrees, such that the shim is wedge shaped in the end view ofFIG. 12. This allows for correction of the angle of the shoe to the pedal cleat according to the orientation of shim140. That is, the orientation may be as shown inFIG. 12, or it may be inverted, in which case the angle of correction will be in the opposite direction.

FIGS. 16 to 20show a 6 mm 3 Degree stack200of shims comprising of one 2 mm thick parallel shim100, one 2 mm thick 2 degree angled shim140, one 1 mm thick parallel shim150and one 1 mm thick 1 degree angled shim160. The shim150is oriented in the stack (inverted) so that the stack200is arranged with the thickness increasing to the right and there are no pins protruding from the external faces204and206of the stack200.FIG. 19shows shim150is inverted due the pattern of pads110being on opposite sides of the centre line101than the pattern of pads on the other shims. In this way the pins of shim150(unseen on the underside) are inserted into sockets114and115of shim100, and pins112of shim100are inserted into the sockets214and215of shim150.

FIGS. 21 to 25show a 6 mm 3 Degree stack250of shims comprising of one 2 mm thick parallel shim100, one 2 mm thick 2 degree angled shim240, one 1 mm thick parallel shim150and one 1 mm thick 1 degree angled shim260. The stack is arranged with the thickness increasing to the left and no pins protruding. Shims240and260are inverted relative to the orientation of the other shims100and150as seen from the pattern of pads110.

FIGS. 26 to 30show a 4 mm 4 Degree stack300of shims comprising of two 2 mm thick 2 degree angled shims140. The stack300is arranged with the thickness increasing to the right and pins112protruding. These pins112may need to be removed if they interfere with the shoe or cleat.

FIGS. 31 to 35show a 5 mm 4 Degree stack350of shims comprising of two 2 mm thick 2 degree angled shims140and one 1 mm thick parallel shim150. The stack is arranged with the thickness increasing to the right and no pins protruding. It can be seen shim150have been inverted relative to the other shims140.

Referring toFIGS. 36 to 40there is shown a screw170with a spherical seating mating face113and a washer180with a spherical seat mating face117thus allowing a washer seating face144to be out of square to a screw centreline143. The preferred base material for the screw170is alloy steel however other materials can also be used. The preferred base material for the washer180is high carbon steel however other materials can also be used.

In an embodiment a centreline103of the spherical seat mating face117is offset to a washer centreline105allowing for the washer180to be turned thus increasing the positional options of the washer180in relation to a mating component, such as a slot, of the cleat.

In an embodiment the washer180has a number of protrusions118to bite into the mating component so the washer is less likely to slip. As the angle between the centreline of the screw143and the washer seating face144increases the chances of slip along the washer seating face144increases.

FIG. 41shows the assembly of the screw170with washer180.

FIGS. 42 to 43shows the assembly of the screw170with the washer180with the washer seating face144being square to the centreline of the screw143.

FIGS. 44 to 45show the assembly of screw170with washer180with the washer seating face144being 5 degrees off square to the centreline of the screw143.

FIGS. 46 to 49show the screw170assembled to various washer shapes shown as washers180,181,182and183.

In an embodiment the washer180is generally trapezoidal in shape (its sides are trapezoidal, with rounded corners) giving the washer180more movement with only a small loss in the washer seating face144surface area. In an embodiment the centreline103of the washer spherical seat is offset to the washer centreline104allowing for the washer180to be turned thus increasing the positional options of the washer180in relation to the mating component.

In an embodiment the washer181is generally rectangular in shape (its sides are rectangular, with rounded corners) giving the washer181more seating face surface area but limiting movement. In an embodiment the centreline107of the washer spherical seat144is offset to the washer centreline108allowing for the washer to be turned thus increasing the positional options of the washer in relation to the mating component.

In an embodiment the washer182is round in shape giving the washer more movement without having to remove then turn the washer. This is the least desirable option as it has the least surface area between the washer and the mating component. In an embodiment the centreline109of the washer spherical seat is offset to the washer centreline111allowing for the washer to be turned thus increasing the positional options of the washer in relation to the mating component.

In an embodiment the washer183may be a plate having two or more spherical seats pitched to match the screw holes of the mating shoe to accommodate multiple screws170.

FIG. 50shows a screw171with a number of grooves119incrementally cut along the length of the thread thus creating marks for the screw to be cut to length whilst maintaining a clean thread start.

In an embodiment the groove faces120are coloured, preferably in a contrasting colour to the screw thus making them more visible.

FIG. 51shows a screw172which has been cut from screw171. The cut is made immediately to the right of the third groove121centre so as to maintain a clean thread start.

FIGS. 52 to 53show a 2 mm thick 2 degree angled shim140. The shim is marked with the average thickness of 1.3 mm127measured at the centreline123of the screw relief hole. The shim140is also marked with the average thickness of 2 mm128measured at the centreline125of the screw relief hole. The shim140is also marked with the average thickness of 2.7 mm129measured at the centreline126of the screw relief hole. The marks are adjacent to the screw relief pockets on the shim140so the length of screws required can be easily calculated.

In an embodiment the shim140is marked with the angle of 2°142for easy identification and so the total angle of the shim stack can be easily calculated.

FIGS. 54 to 58show a bicycle shoe to pedal cleat190with the cleat to shoe/shim mating face145having one or more friction inducing pads133and130that comprises a pocket135and131to allow space for the friction material flow when the cleat is mated to the shoe, shim or another.

In an embodiment the friction inducing pads133and130are formed of a thermoplastic elastomer.

In another aspect of the improved bicycle shoe to pedal cleat190the cleat to shoe/shim mating face145has two or more cleat to shim keying features130.

In an embodiment the keying features comprise two or more pins130.

In an embodiment the keying feature130is dual use being made from rubber-like material to create friction inducing pads/pins130. Each pad/pin is readily removable.

In an embodiment the friction inducing pads130comprise a pocket131to allow space for the friction material flow when the cleat is mated to the shoe, shim or another.

In an embodiment each pad/pin130is susceptible to removable by application of a cutting force substantially parallel to the mating face145.

In an embodiment the dual use keying feature/friction inducing pads130are formed of a thermoplastic elastomer.

FIGS. 59 to 60show the improved bicycle shoe to pedal cleat mounting assembly consisting of a three hole137bike shoe197and a bike shoe cleat190and three spherical seat washers180and 3 spherical seat screws170.

FIGS. 61 to 64show the improved bicycle shoe to pedal cleat mounting assembly consisting of a three hole137bike shoe197and a bike shoe cleat190, and three spherical seat washers180and three spherical seat screws170with the cleat190positioned centrally. The centreline143of the screw170is square to the washer180seating face144. The washer180protrusions118are biting into the mating component in the form of a slot in the cleat body190so the washer is less likely to slip. The mating surface area141between the washer180and cleat190has seating face centre of load139. Either side of the centre of load centreline139the force on the face will be about equal. The further seating face138extends from the centre of load139and the greater the surface area141, the less creep will occur in the cleat body from the load applied. If the material of the cleat body is not able to support the load, then a rectangular washer may be required to increase the loaded surface area with the disadvantage of limiting the adjustment of the cleat position.

FIGS. 65 to 66show the improved bicycle shoe to pedal cleat mounting assembly consisting of a three hole137bike shoe197and a bike shoe cleat190, and three spherical seat washers180and three spherical seat screws170with the cleat190positioned left of centre. The mating surface area141between the washer180and cleat190has seating face centre of load139. Either side of the centre of load centreline139the force on the face will be about equal.

FIGS. 67 to 68show the improved bicycle shoe to pedal cleat mounting assembly consisting of a three hole137bike shoe197and a bike shoe cleat190, and three spherical seat washers180and three spherical seat screws170with the cleat190positioned fully left and washers turned 90 degrees.

FIGS. 69 to 72show the improved bicycle shoe to pedal cleat mounting assembly consisting of a three hole137bike shoe197and a bike shoe cleat190, and three spherical seat washers180and three spherical seat screws170with the cleat positioned fully back. The centreline143of the screw170is 2 degrees off square to the washer180seating face144. The washer180protrusions118are biting into the cleat body190so the washer is less likely to slip.

FIGS. 73 to 74show the improved bicycle shoe to pedal cleat mounting assembly consisting of a three hole137bike shoe197and a bike shoe cleat190, and three spherical seat washers180and three spherical seat screws170with the cleat positioned fully forward.

FIGS. 75 to 76show the improved bicycle shoe to pedal cleat mounting assembly consisting of a three hole137bike shoe197, a 2 mm thick parallel shim100with keying pins facing away from the shoe, a 2 mm thick 2 degree angled shim140with keying pins facing away from the shoe, a 1 mm thick 1 degree angled shim with keying pins removed360and a 1 mm thick parallel shim150with keying pins facing towards the shoe, a bike shoe cleat190, and three spherical seat washers180, 2 spherical seat screws173and 1 spherical seat screws172.

FIGS. 77 to 81show the improved bicycle shoe to pedal cleat mounting assembly consisting of a three hole137bike shoe197, a 2 mm thick parallel shim100with keying pins facing away from the shoe, a 2 mm thick 2 degree angled shim140with keying pins facing away from the shoe, a 1 mm thick 1 degree angled shim with keying pins removed360and a 1 mm thick parallel shim150with keying pins facing towards the shoe, a bike shoe cleat190, and three spherical seat washers180, two spherical seat screws173and one spherical seat screws172. In the shoe197heal to toe direction the centreline146of the Screw173is 2 Degrees off square to the washer180seating face144. Square to the shoe197heal to toe direction the centreline146of the screw173is 3 degrees off square to the washer180seating face144. The washer180protrusions118are biting into the cleat body190so the washer is less likely to slip.

Modifications may be made to the present invention within the context of that described and shown in the drawings. Such modifications are intended to form part of the invention described in this specification.