MXPA99008628A - Dry powder inhaler - Google Patents

Abstract

A dry powder inhaler (1) has a lid (20) pivotally attached to an inhaler housing (5). The inhaler includes a mixing chamber (8), a medicine cartridge (60) and a pressure switch (19).

Description

DRY POWDER INHALER BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The field of the invention relates to inhalers. More specifically, the invention relates to dry powder inhalers for delivering drugs in a finely divided dry powder or in a fluid form. Inhalers are used to deliver drugs to a patient's lungs. Typically, an inhaler contains or provides a mixture of drugs and air or propellants. The mixture is supplied as the patient inhales from a mouthpiece over the inhaler, to treat various conditions, for example bronchial asthma. However, the distribution of drugs by inhalation can be used for many other treatments, including those that are not related to lung conditions. A well-known inhaler, described in PCT application No. PCT / US93 / 09751, contains individual medicine doses stored within a plurality of openings in a drug-containing cartridge. The cartridge is manually advanced for successful doses by rotating the medicine-containing cartridge. However, while the above-described device has met varying degrees of success, there are still disadvantages in spacing or advancing the cartridge within the inhaler, and in reliably distributing a precise quantity of drugs from the cartridge. The Patent of E.U.A. Nos. 5,327,883 and 5,577,497, both incorporated herein by reference, disclose an inhaler having a rotary impeller. The motor for rotating the impeller is connected by a wing switch. In the previous design, the wing switch has a wing or wing that moves by the air flow that occurs when the content is inhaled by the patient. The mechanical movement of the fin closes the switch, with that igniting the motor. The motor rotates an impeller within a mixing chamber, resulting in the drug / air mixture and deagglomeration of drug particles. Since the inhaler has a substantially independent flow velocity, and can be used at very low flow rates, the switch must be very sensitive to air flow. Although the wing switch has worked well in the past, improvements have still to be made in the operation of the switch. Inhalers have also used various techniques to store drugs that will be distributed. Some inhalers have used tanks and mechanisms for bulk drug storage to divide individual doses with each use. Other inhalers have used doses of separately packaged drugs, as in the patents of E.U.A. Nos. 4,778,054 and 5,327,883. However, the reliable and consistent supply of dry powder drug doses has remained an elusive goal. Accordingly, it is an object of the invention to provide an improved inhaler.

BRIEF DESCRIPTION OF THE INVENTION For these purposes, the inhaler herein includes a housing that contains a mixing or atomization chamber. A cartridge containing multiple dose medicament is advantageously attached to the upper part of the housing. The cartridge has individual doses radially spaced in a cartridge ring. A cap is advantageously pivotally secured to the housing and used to space or advance the cartridge ring to the next opening for delivery of successive doses of drugs. Also for these purposes, a dry powder inhaler includes a venturi air passage that is located within the inhaler housing. The venturi air passage preferably has a tapered inlet section, a throat section and a tapered outlet section. A pressure switch is advantageously located within the housing of the inhaler and activates a motor that rotates an impeller. When a patient inhales from the mouthpiece over the inhaler, a differential pressure develops through the venturi air passage. When the pressure inside the venturi reaches a predetermined value, the motor is turned on by means of the pressure switch. Accordingly, the inhaler accurately and reliably perceives the inhalation and starts the engine. Other objects will appear from here on.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, where the similar reference characters denote similar elements through several views: Figure 1 (a) is a perspective view of the inhaler with the removable nozzle portion removed; Figure 1 (b) is a front perspective view of the removable nozzle that was used in the inhaler shown in Figure 1 (a); Figure 1 (c) is a perspective view of the rear part of the detachable nozzle shown in Figure 1 (b); Figure 2 (a) is a perspective view of the inhaler shown in Figure 1 (a) with the cover of the inhaler in open position, and the nozzle covered; Figure 2 (b) is a perspective view of the inhaler shown in Figure 2 (a), where the lid is in a partially open position; Figure 3 is a schematic view with the separate parts of the inhaler of Figures 2 (a) and 2 (b); Figure 4 is a schematic view with the separated parts of the drug-containing cartridge assembly shown in Figure 2A; Figure 4A is a sectional view of the outer ring of the cartridge shown in Figure 4; Figure 4B is an enlarged sectional view of an individual hole in the central ring shown in Figure 4; Figure 4C is an enlarged top perspective view of the lower seal plate shown in Figure 4; Figure 4D is a bottom perspective view thereof; Figure 4E is an enlarged top perspective view of the upper seal plate shown in Figure 4; + Figure 4F is a bottom perspective view thereof; Figure 4G is an enlarged, top perspective view of the lower spring plate shown in Figure 4; Figure 4H is a bottom perspective view thereof; Figure 41 is an enlarged top perspective view of the top spring plate shown in Figure 4; and Figure 4J is a bottom view thereof; Figure 5 (a) is a perspective view of the assembly of the venturi air passage shown in Figure 3; Figure 5 (b) is a geometric venturi construction shown in Figure 5 (a); and Figure 6 is a partial sectional view taken along line 2-2 of Figure 2 (a).

DETAILED DESCRIPTION OF THE MODALITIES Now in more detail in relation to the drawings, as shown in Figures 1-3, a dry powder inhaler 1 includes a cap 20 pivotally mounted by means of a hinge 7 a housing 5. The cap 20 includes a transparent window 22 for observing doses of individual drugs 67 within a medicine-containing cartridge 60 supported on the housing 5. A sliding groove assembly 24 which is located in the lower part of the lid 20 includes a groove G located between the first vertical face 26 and the second vertical face 28, as shown in Figure 2 (a) and 3. Both the first vertical face 26 and the second vertical face 28 extend at an angle relative to the longitudinal centerline of the inhaler. The ribs 29 and the vertical support wall 30 support the vertical face 28 and, a vertical support wall 31 supports the first vertical face 26. The extensions 21 help to hold the cartridge 60 down on the housing 5, when the cover 20 is closed. Turning to Figures 1 (a), 1 (b), 1 (c) and 3, the housing 5 includes a mixing or atomization chamber 8. The mixing chamber 8 is formed at the rear by a molded rear wall 9 in the housing 5, and in front of the rear wall 101 of a removable nozzle 100, as shown in Figure 1 (c). As shown in Figure 3, a port for drug 10 on top of the housing 5 extends into the mixing chamber 8. An opening 1 1 in the rear wall 9 inside the mixing chamber 8, allows air to flow into the mixing chamber during patient inhalation. An impeller 13 inside the mixing chamber 8 is connected to an axis of an electric motor 15. With reference still to FIG. 3, the housing 5 also includes a pair of light emitting diodes (LEDs) 16 and 17 is its surface higher. LED 16 is advantageously red in color and when turned on it indicates to the patient that the batteries (not shown) which are used to light the dry powder inhaler need to be replaced. LED 17 is preferably of different color to LED 1 16, for example, green, and indicates that the energy of the battery is sufficient and that the number of inhalation cycles of the device (for example 1500 cycles) has not been exceeded. A flashing light indicates that the inhaler has enough battery power and remaining life cycles to distribute drug doses of two or more cassettes. A circuit board 65 attached to the bottom of the housing 5 is joined to LEDs 16 and 17, and to the batteries and the motor, to control these functions. Continuing with Figure 3, a lever depression 21 is located within the upper surface of the housing 5. A vertical post 23 extends from the upper surface of the housing 5, and is a pivot point for the ratchet lever 70. The Ratchet lever 70 includes a forked end 71, an end of the cylinder 73, and a tooth 75. The ratchet lever 70 is pivotable about the vertical post 23. Its movement is mimicked by the edges of the lever depression 21. A spring of blade 72 on the housing 5 pushes the ratchet lever 70 radially inward and keeps the forked end 71 against the post 23. The ratchet lever 70 slides along the spring of the blade while the lid is opened and close A pressure switch 19 is located in the lower part of the housing 5 to operate the impeller 13 by means of the electric motor 15. The pressure switch 19, which is shown in imaginary line in Figure 3, is preferably an MPL- 502-0.15 V available at Micro Pneumatic Logic, Inc., Ft. Lauderdale, Florida. The pressure switch 19 is attached to the motor 15. Referring to Fig. 3, 5 (a), and 5 (b), the dry powder inhaler includes an assembly of the venturi air passageway 40 preferably as a molded component of separate way. When the dry powder inhaler is assembled, as shown in Figures 2 (a) and 2 (b), the assembly of the venturi air passage 40 is joined for example adhered, heat sealed, or welded by ultrasound, to the bottom of the housing 5, forming a generally watertight passage from the inlet holes 85 to the mixing chamber 8. The venturi passage assembly 40 allows a consistent and reproducible activation of the pressure switch 19. With regard to Fig. 5 (b), the venturi section of the assembly 40 includes a tapered section 42 that initially receives atmospheric air when a patient inhales over the nozzle 100. The tapered inlet section 42 preferably has an angle? convergent within the scale of approximately 20-30 degrees, preferably around 25 °. The tapered entry section 42 may have a variety of cross-sectional profiles, including circular, semicircular, parabolic and the like. The venturi air passage further includes a throat section 44 which is continuous with the tapered inlet section 42 and has a constant axial cross sectional area. Like the inlet section 42, the throat section 44 can have a variety of cross-sectional profiles. Preferably the throat section 44 has a throat diameter as in the scale of about 2-3 mm and preferably about 2.5 mm. The throat section may have a variable length within the scale of about 0.8 to 1.8 mm, preferably about 1.3 mm. A pressure plug 48 is located within the throat section 44, wherein the pressure switch 19 measures the pressure in the throat section 44 during inhalation. Continuing with Figure 5 (b), the venturi air passage assembly 40 includes a tapered outlet section 46 that is continuous with the mixing chamber 8. The tapered outlet section 46 preferably has a diverging angle f within the approximate scale of 5-10 °, preferably 7o. The tapered exit section 46 can have a variety of cross sections, including circle, semicircular, parabolic and the like. In the preferred embodiment, the entrance, the throat and the exit are semicircular. Preferably, the maximum internal diameters of both the tapered exit section 46 and the tapered entry section 42 are equivalent. The ratio ß, which is defined as the ratio of the diameter of the throat section to the maximum diameter of the tapered inlet section, may vary between 1/4 and 1/2, and is preferably about 1/2. When ß falls within the range specified above, the pressure switch 19 can reliably and firmly activate the motor 15 under operational flow conditions. Referring now to Figures 3 and 4 a cartridge containing medicament 60 includes a cartridge ring 63 having serrated edges 65 located circumferentially around its perimeter. The holes 67 in the ring 63 are filled with dry powder medicaments. The cartridge ring 63 is sandwiched between the upper seal plate 68 and the lower seal plate 69. Both the upper and lower seal plates 68, 69 are preferably made of transparent plastics and prevent contamination or dispersion of the powder from the openings 67. A plate of the upper spring 1 10 having a slotted central hub 112 is placed on top of the sealing plate 68. A lower spring plate 114 having a receptacle 116 is placed under the lower plate 69. receptacle 1 16 is adapted to receive and lock by hopping in hub 112 of receptacle 116, to keep the ring and plates together in an interleaved construction. The anti-rotation holes 62 and 64 extend through the entire medicine-containing cartridge 60, preventing plates 1 10,68,69 and 1 14 from moving during spacing. The lower seal plate 69 has a hole 1 18 and two through-plate posts 120 that connect to the anti-rotation hole in the lower spring plate 14, and keep the hole 1 18 aligned over the opening 66. The upper surface 124 of the lower seal plate 69 also has two short blind posts 128 that extend from the upper surface 124, but do not come out below the lower seal plate 69. The upper surface 124 is otherwise flat and smooth. The receptacle 116 extends through a large space hole 126 and in the inner seal plate 69. A third short blind post 129 extends up and down the plate 69. An opening in the conduit 66 in the lower plate 69 is provided so that the openings 67 can be accessed when aligned with the drug port 10 during use. The posts 120 on the lower seal plate 69 extend through the holes 62 and 64 in the upper plate 68. A stepped post 130 extends from the upper surface of the upper plate and joins an orifice 132 in the upper outer plate 110, thereby aligning the plates 110, 68,69 and 114. The cartridge ring 63 is preferably made of Delrin. The upper plate 68 and the lower plate 69 are preferably made of polycarbonate. These materials provide proper lubricity between their sliding surfaces while the ring 63 is turned inside the interleaved plates, and better prevents the accumulation of dust outside the holes for drug storage 67. As shown in Figures 4A and 4B, the ring 63 has a depression 101 in its upper and lower part, with a diameter D. The seal plates have a coincident diameter (nominally smaller) and are centered on the ring 63 when they are assembled. A lip or ridge R is formed around each hole 67, as shown in Figure 4B. The holes 67 are sealed by means of seal plates connecting the ridges R, which rise above the base surface of the ring B by means of a distance H, about 0.2 mm (.008 inches). The width W of the ridge R is also about 0.2 mm. The rim R acts as a cleaner or scraper on the seal plates, and helps seal the dust in the holes 67, before, during, and after each movement of the ring. The spring plates 110 and 114 are independent of the seal plates. The spring plates exert a clamping or normal force on the seal plates, to keep the seal plates flat against the ring 63, and specifically against the rims R, at the top and bottom. This force is created and maintained by means of the coupling by means of a jump of the hub 12 in the receptacle 116 during the assembly. Therefore, the 5-layer intercalator cartridge can reliably contain and provide exact doses of drug powders.

Referring now to Figure 3, to load the cartridge containing medicine 60, the patient aligns the anti-rotation holes 62 and 64 on the slotted anti-rotation pins 25 and 26 and presses down the cartridge. The plugs at the ends of the pins 25 and 26 are raised outward after clearing the upper spring plate 110 of the cartridge 60, and securely adjusting the cartridge 60 to the housing 5. Referring still to Figure 3, an assembly of the cover of the housing 80 is attached to the lower part of the housing 5, surrounding the motor 15, the assembly of the venturi air passage 40, the batteries and the circuit board 65. An ejector button depression 82 containing a ejection button 90 is located on the lower surface of the housing cover assembly 80. The eject button 90 includes a pair of ejection pins 92 for ejecting the cartridge assembly 60 from the housing. To eject the cartridge 60, a patient must only press the ejection button 90 with sufficient force to free the cartridge 60 from the pins 25 and 26. The pins 92 are pressed against the solid flat bottom surface of the lower spring plate 1 14. Referring now to Figures 1 (a), 1 (b) and 1 (c), a removable nozzle 100 includes a tapered mouth portion 103. The rear wall 101 is located at the rear of the removable nozzle. 100. A plurality of holes 105 in the rear wall 101 allow the air-drug mixture to flow from the mixing chamber 8 to the nozzle 100 during inhalation. The radial holes 107 are positioned circumferentially around the rear portion of the removable nozzle 100. Briefly with respect to Figures 2 (a) and 2 (b), a removable nozzle cover 108 is press fit onto the nozzle 100 when The inhaler is not used. Radial pins 109 on the back of the mouthpiece 100, which join the slots 30 on the housing 5 allow a patient to easily remove and reattach the mouthpiece 100 to the housing 5, to be cleaned. To advance, or space the cartridge 60 to a next, successful dose, a patient first opens, then closes the lid 20 of the dry powder inhaler. With reference to Figures 2 (a), 2 (b) and 3, when a patient begins to open the lid 20 to the position shown in Figure 2 (a), the ratchet lever 70 begins to rotate pivotally about of the vertical post 23 on the housing 5 due to the mechanical coupling of the end of the cylinder 73 with the sliding groove assembly 24 contained in the lid 20. While the lid is opened, the end of the cylinder 73 is pushed progressively in the direction of the arrow A in Figure 3 by means of the sliding contact with the first vertical face 26 of the lid 20. The ratchet lever 70 simultaneously moves radially outward against the force of effect inward of the spring 72, while the tooth 75 goes up and over a saw on the cartridge ring. The forked end 71 allows a radial movement away from the post 23. The friction prevents the ring from moving with the tooth 75 on the ratchet lever 70. When the lid 20 is fully open in a position shown in Fig. 2 (a), the tooth 75 has passed over a saw and moves back radially inward to form a mating or mating fit with a serrated edge 65 of the cartridge ring 63. The spring 72 carries the tooth portion inwardly. behind the sawing after having cleared the sawing. Once the pairing connection has been made, the patient closes the lid 20, to the position shown in Figure 1 (a). When the lid 20 is rotated to the closed position pivotally, the tongue 73 of the ratchet lever 70 is progressively pushed in the direction of the arrow B due to the sliding contact with the second vertical face 28. Since the tooth 75 of the ratchet lever 70 is now in mating contact with the serrated edge 65, the serrated edge 65 and the cartridge ring 63 further rotate in the direction of the arrow B which is handled by the interaction of the tongue 73 in the sliding groove 24. The plates 68,69,110 and 114 of the cartridge 60 remain fixed in at any time on the pins 25 and 26. When the lid 20 is closed to the position shown in Fig. 1 (a), the cartridge ring 63 is spaced, or an opening 67 is advanced, so that it can be distribute the next dose to the patient.

During use, the dry powder inhaler is kept upright as shown in Figure 1 (a). Prior to inhalation, a patient advances, or spaces the medicine-containing cartridge 60 to move the next dose to the dispensing position upon opening and closing the lid 20. A new opening 67 containing the powder drug moves in alignment on the drug port 10. The opening 67 and the powder drug contained therein are no longer interposed between the upper plate 68 and the lower plate 69 since the hole of the conduit 66 and the lower plate 69 allow access to the chamber of mixing 8. After advancing the cartridge, the user places the tapered nozzle 103 of the demontable nozzle 100 in the mouth and inhales. While the user inhales, air is drawn through the inlet ports 85 in the venturi air passage assembly 40. The velocity of the air flowing through the throat section 44 increases, causing a corresponding decrease in air flow. pressure in the throat section 44 according to the Bernoulli's principle. Figures 5 (a) and 6 illustrate the air path through the inhaler and venturi 40. Arrow C in Figure 5 (a) shows the path of air from the atmosphere through the venturi air passage assembly. 40. Figure 6 illustrates the same flow path by means of arrow D, this view only shows a cross-sectional view of the flow throughout the inhaler.

The pressure deduced in the throat section 44 is detected by means of a pressure plug 48 or tube connecting the throat section 44 to the pressure switch 19. Accordingly, when the pressure falls through the throat section 44 reaches a sufficient magnitude, the pressure switch 19 is closed, thereby igniting the motor 15. The rotary impeller attached to the motor shaft 15 starts to rotate inside the mixing chamber 8. Preferably, the pressure switch is closed when the flow rate at nozzle 100 exceeds the approximate scale of 4-8 liters / minute, a very low threshold that virtually all patients can reach or exceed using the inhaler. The venturi design allows an independent selection of the flow velocity that activates the 15 motor. Venturi also serves as a control point for the flow resistance of the inhaler, preferably creating a resistance of about 0.1-0.2 (cm H2 °) 1/2 The value of the venturi pressure drop can also be used to determine the inhalation flow velocity. This information can be recorded, manifested or used to inform the patient if the appropriate speed was achieved. Both the inhalation and the turbulence created by the rotary impeller 13 push the air leaving the tapered outlet section 46 into the mixing chamber 8 by means of an opening 11 located in the rear wall 9 of the mixing chamber 8. In addition , the same inhalation and turbulence cause the powder drug to be stored within the opening 67 to be transferred to the mixing chamber 8 via the drug port. Both the air and the drug are mixed in the mixing chamber by means of the rotary impeller. Referring now to Fig. 1 (c) the air charged with powder passes out of the mixing chamber 8 through the dripping holes 105 located in the rear wall 101 of the nozzle 100 and inside the nozzle 100 and there to the patient's lungs. Accordingly, a novel inhaler was shown and described. Of course, various changes and modifications may be made and various equivalents and substitutions may be used, without departing from the spirit and scope of the present invention. Therefore, the invention should not be restricted, except for the following claims.

Claims (28)

NOVELTY OF THE INVENTION CLAIMS

1. - An inhaler comprising: a housing; a mixing chamber in said housing; a pressure switch inside said housing; a venturi air passage within said housing; and a venturi pressure cap that is connected to the pressure switch.

2. The inhaler according to claim 1, further characterized in that it comprises an electric motor that is inside said housing that is actuated by said pressure switch.

3. The inhaler according to claim 2, further characterized in that it comprises an impeller fixedly attached to an axis of the electric motor, where the impeller is located inside said mixing chamber.

4. The inhaler according to claim 1, further characterized in that said pressure switch that is inside said housing is a pressure transducer.

5. The inhaler according to claim 1, further characterized in that it comprises a cartridge ring rotatably mounted on said housing, wherein the cartridge ring contains a plurality of openings filled with powder.

6. - The inhaler according to claim 5, further characterized in that it comprises an ejection button inside said housing for ejecting the cartridge ring.

7. The inhaler according to claim 1, further characterized in that it comprises a light-emitting diode in said housing, wherein the light-emitting diode indicates to a user when the battery needs to be changed.

8. The inhaler according to claim 1, further characterized in that it comprises a nozzle, the nozzle is removably attached to said housing on said mixing chamber.

9. The inhaler according to claim 8, further characterized in that the pressure switch is closed when a flow velocity in the nozzle exceeds approximately 4.0 liters / minute.

10. An inhaler comprising: a housing; a mixing chamber in said housing; a pressure switch that is inside said housing; a cartridge ring mounted so that it can rotate on said housing; said cartridge ring containing a plurality of openings filled with powder; means for advancing said cartridge ring from the first powder-filled opening to an adjacent opening filled with powder. The inhaler according to claim 10, further characterized in that the means for advancing the cartridge ring comprise: a ratchet lever having a first end and a second end with the first end pivotally fixed to the housing and having a tooth that attaches to the cartridge ring; and a lid pivotally fixed to the housing and includes a first and second separated curved wall, with the second end of the ratchet lever positioned between the first and the second wa

ll.

12. The inhaler according to claim 10, further characterized in that the cartridge ring has a serrated edge and the ratchet lever has a portion of the tooth for engaging the serrated edge.

13. The inhaler according to claim 10, further comprising: an upper plate and a lower plate slidably positioned on the cartridge ring; and an anti-rotation post on the housing extending through the lower and upper plates.

14. A dry powder inhaler comprising: a housing; a mixing chamber in said housing; a pressure switch that is inside said housing; and a venturi air passage located within said housing for activating said pressure switch, said venturi air passage comprising: (a) a tapered inlet section; (b) a throat section and (c) a tapered outlet section.

15. The inhaler according to claim 14, further characterized in that said throat section of said venturi air passage has an internal diameter between the scale of about 0.20 cm to 0.33 cm.

16. The inhaler according to claim 14, further characterized in that the tapered inlet section and said tapered outlet section have a maximum diameter of approximately twice the internal diameter of said throat section.

17. The inhaler according to claim 14, further characterized in that it comprises an electric motor that is inside said housing, where the electric motor is activated by said pressure switch.

18. The inhaler according to claim 14, further characterized in that it comprises a cartridge ring rotatably mounted on said housing, wherein the cartridge ring contains a plurality of openings filled with powder; a plurality of separate holes in the cartridge ring to contain a dry powder; an upper seal plate on the upper side of the cartridge ring; a lower seal plate on the underside of the cartridge ring; an upper spring plate which is on the upper seal plate; and a lower seal plate that is on the lower seal plate.

19. A cartridge containing medicament for use with an inhaler, comprising: a cartridge ring having an upper side and a lower side; a plurality of separate holes in the cartridge ring to contain a dry powder; an upper seal plate on the upper side of the cartridge ring; a lower seal plate on the underside of the cartridge ring; an upper spring plate which is on the upper seal plate; and a lower seal plate that is on the lower seal plate.

20. The cartridge according to claim 19, further characterized in that it comprises serrated edges located circumferentially around the perimeter of the cartridge ring.

21. The cartridge according to claim 19, further characterized in that the upper and lower seal plates and the spring plates are made of transparent plastic.

22. The cartridge according to claim 19, further characterized in that one of the upper and lower spring plates has a bucket and the other has a receptacle adapted to a closure by jumping in the bucket, to hold together the cartridge ring , to the seal plates, and to the spring plates in an interleaved construction.

23. The cartridge according to claim 19, further characterized in that it comprises a pair of anti-rotation holes extending through the seal plates and the holding plates.

24. The cartridge according to claim 19, further characterized in that it comprises a dispensing orifice in the lower seal plate and an opening in the conduit in the lower spring plate.

25. The cartridge according to claim 19, further characterized in that the cartridge ring comprises Delrin and the upper and lower seal plates comprise polycarbonate, to provide an appropriate lubricity between their sliding surfaces.

26. The cartridge according to claim 19, further characterized in that the cartridge ring includes an upper depression and a lower depression adapted to receive the upper and lower seal plates.

27. The cartridge according to claim 25, further characterized in that it comprises a lip formed around each hole on the upper side and the lower side of the cartridge ring.

28. The cartridge according to claim 27, further characterized in that the lip has a height of approximately 0.2 mm and a width of approximately 0.2 mm.