Patent Description:
In the construction and dental sectors, cartridges are frequently used to dispense liquids, for example, sealing components, components for chemical dowels or chemical anchors, adhesives, pastes or impression materials in the dental sector. Such kind of cartridges are known from for example <CIT>, <CIT>, <CIT>, <CIT> or <CIT>.

Conventional dispensers can be single-component systems in which the material to be dispensed is formed from one component and two-component or multicomponent systems in which at least two different components are stored in separate chambers of the same cartridge or in separate cartridges. The two-component or multicomponent systems, the components are mixed by a dynamic or static mixing apparatus. Examples of multicomponent systems include adhesives or chemical dowels which only harden after the mixing of the two components. Two-component systems can also be used in the industrial sector for paints which are often used to generate functional protective layers such as for corrosion protection.

Many conventional systems can include prefilled cartridges designed for a single use. In such systems a substantial amount of waste results both with regard to volume and to mass. An alternative to these cartridges are unfilled cartridges that can be transported by the cartridge manufacturers to the manufacturers of the filling materials who then fill the empty cartridges. Even though the unfilled cartridges have a relatively low weight, the costs for the transport of the empty cartridges from the cartridge manufacturers to the media manufacturers are relatively high since the empty cartridges have a relatively large volume and thus high space requirements on transport. The storage costs for the empty cartridges both at the cartridge manufacturers' and at the media manufacturers' are furthermore also relatively high due to the space requirements. These costs make up a not insubstantial portion of the total manufacturing costs of the cartridges.

It has been discovered that providing a system and method to improve the collapsing of the cartridge would be advantageous. In particular, it has been determined that an improvement in collapsing the cartridge can reduce the space need for storing and shipping purposes and reduces the waste of a component filing the cartridges.

Hence, it is one object of the invention to improve the collapsing of a cartridge.

This object is satisfied by a dispensing system comprising the features of claim <NUM> and the methods of claims <NUM> and <NUM>.

Referring now to the attached drawings which form a part of this original disclosure:.

Selected embodiments will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims.

Referring initially to <FIG> and <FIG>, a dispensing system <NUM> according to an embodiment of the present invention is illustrated. The dispensing system <NUM> includes a support cartridge system <NUM>, a two-component collapsible cartridge <NUM> and piston system <NUM>. As can be understood, the dispensing system <NUM>, when filled with a component, can be inserted into a dispensing device to dispense the component or components, as is known in the art.

As is understood, a dispensing system <NUM> for two-components, as described herein, is configured to hold, store and dispense two separate components. The two components can be mixed upon dispensing or at any suitable time. Such a two-component dispensing system enables materials or components that would otherwise be stored for a significant time period to be stored and used at a later time. It is noted that the piston and dispensing system <NUM> described herein can be used in a single component dispensing system, a two-component dispensing system or a multicomponent (more than two) system, if desired.

Turning to <FIG>, a two-component collapsible cartridge <NUM> is illustrated. The cartridge includes a first generally cylindrical reception chamber (or cartridge) 14a and a second generally cylindrical reception chamber (or cartridge) 14b. The reception chambers 14a and 14b are each defined by a cartridge wall 18a and 18b and a common head part <NUM>. The common head part <NUM> preferably forms an end-face or surface <NUM> and <NUM> of each of the reception chambers 14a and 14b. The ends 26a and 26b of the two cartridge walls 18a and 18b are disposed remote from the head part <NUM> and are each led together toward the center axis Ca and Cb of the respective reception chamber 18a and 18b and can be bound together by a respective clamping ring 28a and 28b, or in any other suitable manner, such that the ends are capable of being sealingly closed.

As shown in <FIG>, the first reception chamber 14a has a diameter D<NUM> that is larger than the diameter D<NUM> of the second reception chamber 14b; however, the reception chambers 14a and 14b can have the same or substantially the same diameter, or have any diameter desired. That is, the diameters can have any relative size to each other that would enable two separate components or materials to be mixed together in a suitable or desired ratio.

The ends 30a and 30b of the reception chambers 14a and 14b facing the head part <NUM> are sealingly and unreleasably connected to the head part <NUM>. In one embodiment, the head part <NUM> is injection molded to the ends of the reception chambers 14a and 14b. The head part <NUM> can be formed from a stable-shape plastic, and the cartridge walls 18a and 18b can be formed as multilayer films which are each rolled to a cylindrical shape in their predominantly center regions and are welded or otherwise connected to form a seam <NUM> at their longitudinal edges thus forming together with the head part <NUM> the cylindrical reception chambers 18a and 18b.

The head part <NUM> preferably includes two outlets 20a and 20b which are connected to the reception chambers 18a and 18b for filling the reception chambers with a filling component or material and for dispensing the filling component or material out of the reception chambers. A screw cap <NUM> can be used to close the outlets.

As can be understood, <FIG> illustrates the reception chambers 14a and 14b in an empty state. In other words, the reception chambers 14a and 14b, as shown in <FIG> have not yet filled with a component, i.e. with the material to be dispensed. However, as shown in this embodiment, the cartridge walls 18a and 18b have a substantially cylindrical shape due to the stiffness of the used film material. It is noted that this cylindrical shape represents the expanded state of the reception chambers 14a and 14b with a maximum volume of the reception chambers.

As shown in <FIG>, the cartridge walls 18a and 18b can pushed together or compressed in the longitudinal direction of the reception chambers 14a and 14b before filling with the component. When the collapsed state is accomplished as described herein, this state has been determined to reduce the space need for storing and shipping purposes and reduces the waste of a component filing the reception chambers 14a and 14b.

Turning back to <FIG> and <FIG>, the support cartridge system <NUM>, includes first and second support cartridges 12a and 12b that include first and second hollow cylinders 34a and 34b, respectively. The first and second hollow cylinders 34a and 34b are sized and configured to receive the first and second reception chambers 14a and 14b and of the two-component collapsible cartridge <NUM>, respectively. The first and second hollow cylinders 34a and 34b each have a first opening 36a and 36b and a second opening 38a and 38b. The first openings 36a and 36b are configured to receive a respective reception chamber 14a and 14b and the second opposite openings 38a and 38b are configured to receive a respective piston 16a and 16b. As will be described herein, the first and second reception chambers 14a and 14b and can be pushed into a respective reception opening 36a and 36b until the head part <NUM> contacts the end of the respective support cartridge12a and 12b.

The piston system <NUM> includes first and second pistons 16a and 16b, which generally have the same configuration, with the main difference being size or relative diameter. Thus, only the first piston 16a will be described in detail in view of <FIG> illustrate a first embodiment of the present invention. The piston 16a is preferably generally cylindrical, and sized and configured to tightly fit within the inner peripheral surface <NUM> of the support cartridge 12a. It is noted that in this embodiment, the piston 16a does not need to form a seal with the support cartridge 12a. However, the piston 16a preferably forms a tight fit with the support cartridge 12a to prevent the reception chamber 14a from being pinched between the support cartridge 12a and the piston 16a.

The piston 16a has a first portion <NUM> and a second portion <NUM>. The first portion <NUM> is a rigid portion having a first diameter D<NUM>, a first end <NUM> and a second end <NUM>. The first end <NUM> of the rigid portion is disposed in the material dispensing direction DD (i.e., the direction in which the component is dispensed), and the second end <NUM> is disposed in the opposite direction (filling direction FD). The second end <NUM> of the rigid portion <NUM> can receive the pressure or force that is required to move the piston through the support cartridge 12a. The rigid portion <NUM> is preferably formed from any suitable plastic or metal that is rigid and does not flex under pressure. However, the rigid portion <NUM> can be formed from any suitable material.

As shown in <FIG>, the rigid portion <NUM> includes a first rigid portion 42a and a second rigid portion 42b. The first rigid portion 42a is disposed externally of the second portion <NUM>, and the second rigid portion 42b is disposed within the second portion <NUM>. The first rigid portion 42a includes a radial outer surface <NUM> adjacent the second end <NUM> and the second rigid portion 42b includes a protrusion <NUM> adjacent the first end <NUM>. The radial outer surface <NUM> includes a skirt <NUM> or sealing lip extending therefrom in the dispensing direction. The skirt <NUM> preferably extends around the entire circumference of the first rigid portion 42a, but can extend in any suitable or desired manner. The skirt <NUM> preferably extends radially outwardly from the end <NUM> of the radial outer surface <NUM> and has a diameter about the same size as the inner diameter of the support cartridge 12a. Accordingly, the skirt <NUM> is sized and configured to slide within the inner surface of the support cartridge 12a. In this connection, it should be noted that the skirt <NUM> is configured to fit within the support cartridge 12a in such a way that it does not tilt relative to the dispensing direction DD but also does not seal against the inner surface so that the piston 16a can move within the support cartridge 12a. In one embodiment, a hole <NUM> or a plurality of holes can be disposed in the skirt <NUM> or the rigid body <NUM> to enable air to pass in a direction opposite to the dispensing direction DD during dispensing. It is to be understood that the hole <NUM> may also be used to allow air to pass in the dispensing direction DD during filling of the respective reception chambers 14a and 14b, i.e. the air is allowed to pass in an direction opposite to the filling direction FD. Such a structure prevents air from being trapped between the piston 16a and the reception chamber 14a, while allowing a tight fit between the skirt <NUM> and the inner peripheral surface <NUM> of the support cartridge 12a. Moreover, the skirt <NUM> preferably extends in the material dispensing direction so to be capable of fitting a portion of or the entire cartridge wall 18a (in the collapsed state) between an inner surface <NUM> thereof and the second portion <NUM> (See <FIG>).

In one embodiment, the radial outer surface <NUM> of the first rigid portion 42a and the outer surface <NUM> of the skirt <NUM> also includes a plurality of integrated ribs or tabs <NUM> spaced radial therearound. The tabs <NUM> generally protrude from the radial outer surface <NUM> of the rigid portion <NUM> and the outer surface <NUM> of the skirt <NUM> and extend in a longitudinal direction of the dispensing direction DD. In one embodiment, the radial outer surface <NUM> and the outer surface <NUM> of the skirt <NUM> includes four tabs <NUM> evenly spaced therearound; however, it is noted that there can be any suitable number of tabs <NUM>, and the tabs <NUM> can be spaced in any suitable manner. As shown in <FIG>, the tabs <NUM> can be rectangular in shape and can extend from the second end <NUM> of the rigid portion <NUM> to the end <NUM> of the skirt <NUM>. The tabs <NUM> prevent the cartridge wall 18a, when being compressed, to pass over the end <NUM> of the skirt <NUM> of the piston 16a. When the cartridge wall 18a passes over the end <NUM> of the skirt <NUM>, portions of the cartridge wall 18a can be pinched and broken between the piston 16a and the support cartridge 12a. If the cartridge wall 18a is compromised in this manner, a new flow path for the component or material can be formed, creating an undesirable ballooning effect behind the piston 16a.

The protrusion <NUM> is preferably cylindrical and has a diameter that is less than the diameter of the end <NUM> of the skirt <NUM>. The protrusion <NUM> can include an arcuate edge <NUM> that extends from the edge formed by the first end <NUM> and the upper radial surface <NUM> of the second rigid portion 42b. This protrusion <NUM> increases the support at the edge <NUM> and guides the cartridge wall 18a to allow the cartridge wall 18a to fit the piston geometry, furthering the amount of material to be dispensed out of the two-component collapsible cartridge <NUM>.

As illustrated in <FIG>, the second portion <NUM> is a flexible portion having a second diameter D<NUM> that is less than the diameter D<NUM> of the first rigid portion 42a, a first end <NUM> disposed in the material dispensing direction DD and a second end <NUM> disposed in the opposite direction (filling direction FD). The flexible portion <NUM> is disposed on the first end <NUM> of the rigid portion <NUM> such that the second end <NUM> of the flexible portion <NUM> is disposed to face the first end <NUM> of the rigid portion <NUM>.

The flexible portion <NUM> is formed from a material that is capable of radially expanding and longitudinally compressing upon a force applied to the first end <NUM> of the flexible portion <NUM> so as to compress the collapsible cartridge between the flexible portion <NUM> and the surface <NUM> of the support cartridge 12a. Thus, the flexible portion <NUM> can be formed any material suitable to accomplish sufficient radial expansion. Suitable materials can include, but are not limited to thermoplastic elastomer (TPE), silicone, any other elastomeric material or any suitable flexible material. In one embodiment, the flexible portion <NUM> is formed from a material having a durometer between about <NUM> and <NUM> on the durometer A scale. Preferably, the flexible material is formed from a material having a durometer around <NUM> shore A.

The flexible portion <NUM> includes an internal cavity <NUM> and at least a portion of the rigid portion <NUM> extends into the internal cavity <NUM>. In other words, the flexible portion <NUM> has a recessed portion that defines an integral cavity <NUM> that is sized and configured to receive the rigid portion <NUM>. As described above, this embodiment increases the support at the edge and guides the cartridge wall 18a to allow the cartridge wall 18a to fit the piston geometry, furthering the amount of material to be dispensed out of the two-component collapsible cartridge <NUM>.

The overall height of the flexible portion <NUM> relative to the cartridge wall 18a length should be determined such that the flexible portion <NUM> makes initial contact with the end surface <NUM> of the head part <NUM> about <NUM>-<NUM> prior to the cartridge wall 18a reaching its compressed height. Such a compression distance will generally result in sufficient radially expansion to compress the cartridge wall 18a. However, the deflection of the flexible portion <NUM> close to the edges is reduced due to the protrusion <NUM> as discussed above, otherwise the tension of the cartridge wall 18a in this area may cause a larger than desired diameter. Such an increased diameter can trap material and air on the inside of the cartridge wall 18a which is undesirable.

As can be seen best from the cross sectional view of <FIG>, the cavity <NUM> of the flexible portion <NUM> forms a recess <NUM> that receives the protrusion <NUM> of the rigid portion <NUM>. Preferably, the protrusion <NUM> is received in the recess <NUM> in a form fit manner. Receiving the protrusion <NUM> in the recess <NUM> allows for a secure seating of the flexible portion <NUM> on the rigid portion <NUM>. Furthermore, on compression of the flexible portion <NUM> in the dispensing direction DD, the protrusion <NUM> received in the recess <NUM> prevents that the flexible portion <NUM> excessively expands in the radial direction. Simultaneously, the flexible portion <NUM> is directed into the dispensing direction DD and exerts a force on the cartridge <NUM> so that more material is dispensed therefrom.

As the flexible portion <NUM> is compressed against the end surface <NUM> of the head part <NUM>, the flexible material or the flexible portion <NUM> is longitudinally compressed and radially expanded. In other words, the flexible portion <NUM> can be flattened against the end surface <NUM> of the head part <NUM>, which results in expansion of the diameter of the flexible portion <NUM> in the radial direction. Preferably, the flexible material of the flexible portion <NUM> increases in diameter by about <NUM>-<NUM> in the radial direction RD when a force of approximately 250N is applied to the first end <NUM>. Preferably, the diameter of the flexible portion (<NUM>, <NUM>) increases from <NUM> to <NUM> % when a force of <NUM> N is applied to the flexible portion (<NUM>, <NUM>), in particular with the force being applied to the flexible portion in a direction that is at least approximately parallel to the dispensing direction DD. In one embodiment, the flexible portion <NUM> increases in diameter about <NUM> in the radial direction RD. This radial expansion compresses the cartridge wall 18a of the compressed cartridge between a radial outer surface <NUM> of the flexible portion <NUM> and the inner surface <NUM> of the support sleeve 12a, and/or the inner surface <NUM> the skirt <NUM>. This structure reduces residual waste or air entrapment in the cartridge.

The first end <NUM> of the flexible portion <NUM> can have any suitable configuration. For example, the first end <NUM> can be generally or substantially flat or planar, it can also have an arcute or curved configuration or it can have a peaked or angled configuration. The radial outer surface <NUM> of the flexible portion <NUM> can be generally parallel to the longitudinal axis L of the piston 16a or in can form an angle with the longitudinal axis L. That is, the diameter D<NUM> of the flexible portion <NUM> at the radial outer surface <NUM> can decrease in the dispensing direction. That is the diameter D<NUM> of the flexible portion <NUM> can decrease in the dispensing direction DD. Preferably the height Hi of the flexible portion <NUM> (from the point where the skirt meets the radial outer surface <NUM> of the rigid member) is between about <NUM> and <NUM>, and preferably about <NUM>. Moreover, the thickness T<NUM> of the flexible portion from the radial outer surface <NUM> of the first rigid portion 42a (i.e., the radial inner surface of the flexible portion <NUM>) to the radial outer surface <NUM> of the flexible portion <NUM> is about <NUM> to about <NUM>, and preferably about <NUM>. The thickness T<NUM> of the flexible portion <NUM> from the protrusion <NUM> of the second rigid portion 42a to the first end <NUM> of the flexible portion <NUM> is between about <NUM> and <NUM>. The thickness T<NUM> of the flexible portion <NUM> from the first end <NUM> of the rigid portion <NUM> to the first end <NUM> of the flexible portion <NUM> is between about <NUM> and <NUM>. Thus, the ratio of a height Hi of the flexible portion <NUM> to the distance from the first end <NUM> of the rigid portion <NUM> to the first end <NUM> of the flexible portion <NUM> is between about <NUM> to <NUM>.

The height H<NUM> of the flexible portion <NUM> from the end <NUM> of the skirt <NUM> to the first end <NUM> of the flexible portion is about <NUM>-<NUM>. However, it is noted that the dimensions are merely examples and the dimensions of the flexible portion <NUM> relative to the rigid portion <NUM>, and any other dimension can be any suitable dimension.

Turning to <FIG>, the manner in which the two-component collapsible cartridge <NUM> can be filled is illustrated. In one embodiment, the two-component collapsible cartridge <NUM> is shipped to the distributor or user in an empty state. As shown in <FIG>, the empty two-component collapsible cartridge <NUM> is connected to the support cartridge system <NUM>, and then as shown in <FIG>, inserted into a filling device D. The filling device D includes a mounting mechanism M that is configured to attach to the head part <NUM> to hold the two-component collapsible cartridge <NUM> in a desired and proper position. Once in position, the piston system <NUM> is inserted into the support cartridge system <NUM>. A shown in <FIG>, the piston system <NUM> is acted upon by force from a plurality of plungers P. The force F exerted by each plunger P can be any suitable amount (e.g., <NUM> N), and supplied in any manner desired, for example using compressed air, a mechanical force or any other suitable device. The piston system <NUM> moves in the dispensing direction toward the end surface of the head part <NUM>. As the piston system <NUM> moves in this direction, each piston 16a in the piston system <NUM> enters the open end <NUM> of a respective cartridge wall 18a and 18b. The edge <NUM> of each of the cartridge wall 18a and 18b is collected in the area between the skirt <NUM> and the outer radial surface <NUM> of the flexible portion <NUM>. The heights H<NUM> and H<NUM> can be important here, since such heights can affect the amount air or component that is dispensed or expelled from the reception chambers 14a and 14b. As the piston system <NUM> continues to move and collect the cartridge walls 18a and 18b air is expelled from the cartridges.

The piston system <NUM> continues to move in the dispensing direction DD and contacts the end surfaces <NUM> and <NUM> of the head part <NUM>. As the piston system <NUM> contacts these surfaces <NUM> and <NUM>, the force F is maintained in the dispensing direction DD, thereby causing the flexible portion <NUM> of each of the pistons 16a and 16b to be compressed in the longitudinal direction L against the surfaces <NUM> and <NUM> of the head part <NUM>. This compression causes the flexible portion <NUM> of each piston to radial expand in the radial direction. As described herein the radial expansion can be about <NUM>-<NUM> (or more preferably about <NUM>) when a force of approximately 250N is applied to the first end <NUM>; however, it is noted that the radial expansion can be any suitable amount. As shown in <FIG>, the radial expansion occurs in the area in which the cartridge wall 18a has been gathered, thus compressing the cartridge wall 18a between the radial outer surface <NUM> of the flexible portion <NUM> and the inner surface <NUM> of the support sleeve 16a, and/or the inner surface <NUM> of the skirt <NUM>. This compression expels additional air from the collapsed cartridge.

As shown in <FIG>, the filing nozzle N is then attached to the head part <NUM> and the desired components can be injected or dispensed into the cartridge walls 18a and 18b. The force F of the filling nozzle N expands the cartridge walls 18a and 18b and pushes the piston system <NUM> in the filling direction FD (opposite the dispensing direction), as shown in <FIG>. As is understood, the force F of the plungers P can be removed, such that the filling nozzle N is only required to overcome the static force of the plungers P and expansion of the cartridge walls 18a and 18b. Once the plungers P contact the limit switches LS the filling nozzle N can be stopped. The dispensing system <NUM> can then be removed and closed.

To dispense, the two-component collapsible cartridge <NUM> is simply inserted into the dispensing device and dispensed. If desired, the dispensing can be performed using the piston system <NUM> described herein, which would gather the cartridge walls 18a and 18b in the area between the skirts 54a and the radial outer surfaces <NUM> and dispense the components in a similar manner to the filing described above. That is, as the piston system <NUM> continues to move through the support cartridge system <NUM>, the collapsible cartridge walls 18a and 18b are collected, and the components are dispensed through the head part <NUM>. The piston system <NUM> then continues to move in the dispensing direction DD and contacts the end surfaces <NUM> and <NUM> of the head part <NUM>. As the piston system <NUM> contacts these surfaces, the force F (e.g., <NUM> N) is maintained in the dispensing direction DD, thereby causing the flexible portion <NUM> of each piston 16a and 16b to be compressed in the longitudinal direction L against the surfaces <NUM> and <NUM> of the head part <NUM>. This compression causes the flexible portion <NUM> of each piston 16a and 16b to radial expand. As described herein the radial expansion can be about <NUM>-<NUM> (or more preferably about <NUM>) when a force of approximately 250N is applied to the first end <NUM>; however, it is noted that the radial expansion can be any suitable amount. The radial expansion occurs in the area in which the cartridge walls 18a and 18b have been gathered, thus compressing the cartridge walls 18a and 18b between the radial outer surface <NUM> of the flexible portion <NUM> and the inner surface <NUM> of the support sleeves 12a and 12b, and/or the inner surface <NUM> of the skirts <NUM>. This compression expels additional component from the collapsed cartridge.

The piston structure described herein improves the amount of component that can be dispensed by both removing excess air during the filling procedure and expelling additional component during the dispensing procedure. Such a system reduces waste of components, thereby reducing cost and environmental impact.

<FIG> is a partial cross-sectional view of a second embodiment or a piston <NUM>. In this embodiment, the skirt <NUM> is attached to the flexible portion <NUM>. That is, the flexible portion <NUM> includes a first portion 144a and second portion 144b. The first portion 144a is tubular and is connected to the rigid portion <NUM> at an outer radial <NUM> surface thereof. The second portion 144b generally comprises the compressible/flexible portion <NUM> that operates in the same manner as the flexible portion <NUM> described herein. The skirt <NUM>, in this embodiment, is attached to a transverse portion <NUM> between the first and second portions 144a and 144b and extends in the dispensing direction DD. Here the second portion 144b preferably has a height between about <NUM> and <NUM>. The piston <NUM> operates in the same manner as described herein for the pistons 16a and 16b of the first embodiment.

Although the rigid portion <NUM> as shown in <FIG> has no protrusion <NUM> like the rigid portion <NUM> shown in <FIG>, one could also envisage that the rigid portion <NUM> may comprise a protrusion <NUM> similar to that of the rigid portion <NUM>, with such a protrusion <NUM> being received in the cavity <NUM> of the flexible portion <NUM>.

It is noted that any description of one piston described herein can be applied to multiple pistons.

The dispensing device, into which the present dispensing system is inserted to affect dispensing and the filling device are conventional components that are well known in the art. Since the dispensing device and the filling device are well known in the art, these structures will not be discussed or illustrated in detail herein. Rather, it will be apparent to those skilled in the art from this disclosure that the components can be any type of structure and/or include any programming that can be used to carry out the present invention.

In understanding the scope of the present invention, the term "comprising" and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, "including", "having" and their derivatives. Also, the terms "part," or "portion," when used in the singular can have the dual meaning of a single part or a plurality of parts. Also as used herein to describe the above embodiment(s), the following directional terms refer to those directions of a system equipped with the piston for a collapsible cartridge. Accordingly, these terms, as utilized to describe the present invention should be interpreted relative to a system equipped with the piston for a collapsible cartridge.

The term "configured" as used herein to describe a component, section or part of a device includes hardware and/or software that is constructed and/or programmed to carry out the desired function.

The terms of degree such as "substantially", "approximately" and "about" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed.

Claim 1:
A dispensing system (<NUM>), comprising:
a cartridge (<NUM>) having a head part (<NUM>) and a cartridge wall (18a, 18b) which define a reception chamber (14a, 14b) configured to retain a medium to be dispensed, the head part (<NUM>) including a surface (<NUM>, <NUM>) and an outlet (20a, 20b) in the surface (<NUM>, <NUM>), the outlet (20a, 20b) configured to enable the material to be dispensed therethrough, the cartridge wall (18a, 18b) configured to be collapsible; and
a piston (16a, 16b, <NUM>) configured to collapse the cartridge (<NUM>) and dispense the medium, the piston (16a, 16b, <NUM>) including a rigid portion (<NUM>, <NUM>) having a first diameter (D<NUM>), a first end (<NUM>) and a second end (<NUM>), the first end (<NUM>) configured to be disposed in a material dispensing direction (DD), and a flexible portion (<NUM>, <NUM>) having a second diameter (D<NUM>) less than the first diameter (D<NUM>), a first end (<NUM>) disposed in the material dispensing direction (DD) and the second end (<NUM>) disposed in an opposite direction, the flexible portion (<NUM>, <NUM>) being disposed on the first end (<NUM>) of the rigid portion (<NUM>, <NUM>) such that the second end (<NUM>) of the flexible portion (<NUM>, <NUM>) is disposed to face the first end (<NUM>) of the rigid portion (<NUM>, <NUM>), and the flexible portion (<NUM>, <NUM>) configured to radially expand upon a force being applied to the piston (16a, 16b, <NUM>) in the material dispensing direction (DD) such that the first end (<NUM>) of the flexible portion (<NUM>, <NUM>) contacts the surface (<NUM>, <NUM>) of the head part (<NUM>).