Automatically adjusting headgear for patient interface

Abstract

To provide an interface providing at least useful options to the industry and a user.SOLUTION: A headgear for securing a mask to a user's face is described. The headgear requires a first load force to elongate the headgear and, when fitted to a user, applies a balanced fit force that substantially equals a load force applied to the headgear during respiratory therapy. In some embodiments, the headgear includes an elastic portion configured to provide a retraction force, a non-elastic portion configured to be inelastic in comparison to the elastic portion, and a restriction mechanism connected to the non-elastic portion and to the elastic portion. The restriction mechanism is configured to apply a first resistance force to the user's head on elongation of the headgear and a second resistance force to the user's head on retraction of the headgear.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Incorporation by Reference of Priority Application Any application to which foreign or domestic priority is claimed that is listed in an Application Data Sheet filed with this application is hereby incorporated by reference and made a part of this disclosure.

[0002] The present invention relates generally to structures used to secure a respiratory mask interface to the head, and more particularly to a generally automatic adjustable structure having at least one of an adjustment mechanism and an arrangement for providing a predetermined wear length and at least one longer wear length. [Background technology]

[0003] Obstructive sleep apnea (OSA) is a sleep condition in which the back of the throat relaxes so much during sleep that it narrows or even completely blocks the airway. This narrowing or blockage can cause breathing to stop or become very shallow for several seconds or more.

[0004] Continuous positive airway pressure (CPAP) is used to treat OSA. CPAP delivers a stream of pressurized air that opens the airways. The stream of pressurized air can be delivered to the user using a respiratory mask interface, which can include a mask with inelastic or elastic straps and headgear.

[0005] When wearing an interface with elastic straps, the elastic straps stretch to allow the headgear to slide over the user's head, and when released, the elastic straps tend to pull the interface toward the user's face.

[0006] When elastic straps are used, the straps that secure the mask to the face are elastic, so as the pressure inside the mask increases (e.g., from about 4 cmH2O to about 12 cmH2O), the mask will tend to move away from the user's face. The force that tries to move the mask away from the face can be defined as the "blow-off force."

[0007] In some masks, as the force of inhalation stretches the elastic straps, the force exerted by the mask on the user's face decreases. Therefore, these masks may develop leaks as the pressure increases. Also, while a mask may seal properly at higher pressures (e.g., approximately 12 cmH2O), the elasticity of the straps can cause undesirably high pressures on the user's face at lower treatment pressures (e.g., approximately 4 cmH2O) when the pressure is not at the high pressure level. While interfaces with adjustable, non-elastic straps can reduce the occurrence of leaks, such headgear is often overly restrictive, applying unnecessary force to the user's face and / or head.

[0008] Similar problems can occur with therapeutic interfaces other than CPAP. For example, respiratory mask interfaces are used for non-invasive ventilation (NIV) in hospital settings. NIV typically provides a pressure range of approximately 20 to 50 cmH2O. Therefore, the large difference between the minimum and maximum therapeutic pressures in NIV therapy can exacerbate the problems described above with CPAP. Another common respiratory disorder therapy is called bilevel positive airway pressure (Bi-level PAP), in which the patient is provided with an inspiratory pressure (IPAP) and an expiratory pressure (EPAP). The difference between IPAP and EPAP can vary from approximately 1 cmH2O to approximately 10 cmH2O, which also produces a cyclical blowdown.

[0009] Elastic straps are also commonly used in conjunction with nasal cannulae for use in High Flow Therapy (HFT), in which cannulae are used to deliver high flows of breathing gas, often containing increased amounts of oxygen.

[0010] A common problem experienced when using nasal cannulae is that extension of the headgear puts a strong pull on the gas delivery tubing, causing the cannula prongs to fall out of the patient's nose. If the prongs fall out of the nose, loss of therapy can occur. Even if they don't fall out, the hose can pull on the tubing, causing the cannula to rest in a bent position on the patient's face. This can cause patient discomfort and a cosmetic effect that reduces effectiveness. Traditionally, cannulae have a lateral horizontal tubing connection. With this connection, tension on the tubing can cause the cannula to pull unevenly away from the patient's nose because the force is transmitted directly to one side of the cannula. Summary of the Invention [Problem to be solved by the invention]

[0011] It is an object of the present invention to provide an interface that at least provides useful choices to the industry and users. [Means for solving the problem]

[0012] Some aspects of the present invention relate to providing an automatic adjustment mechanism that secures a respiratory mask interface or other type of sealed or substantially sealed interface (e.g., nasal pillows) to a user's face while achieving a balanced fit. As used herein, "achieving a balanced fit" means that the headgear applies only enough force to overcome "inhalation force" and, in some configurations, some or all of anticipated hose pull forces or other external forces. "Inhalation force" may be defined as the CPAP pressure multiplied by the mask's sealing area. An automatic adjustment mechanism that achieves a balanced fit minimizes the force exerted by the interface mask on the user's face, and this minimal level of force maintains a level of force sufficient to seal the interface mask against the user's face. This can therefore increase user comfort. Preferably, once the interface assembly is donned, any adjustments to address leaks can be made by gently rocking, pushing, or pulling the mask interface rather than manipulating buckles, clips, straps, etc., of the headgear assembly. When aspects of the invention are applied to non-sealing or substantially non-sealing interfaces, such as cannula devices, a "balanced fit" is achieved when the length of the headgear cannula loop matches the circumference of the user's head and provides some resistance to stretching. Because the cannula system is not pressurized, there is no "breathing force," so the headgear is only required to hold the cannula in place and handle any anticipated hose tension. Adjustments can be made similarly to applications with CPAP masks or other pressurized or sealing interfaces.

[0013] The automatic adjustment mechanism combines some of the advantages of extensible and substantially non-extensible headgear assemblies, while in some configurations eliminating the need to manually adjust the headgear assembly to suit an individual user. As used herein, "manual adjustment of a headgear assembly" means directly manipulating the headgear assembly to make larger adjustments to the headgear assembly, such as the circumferential length defined by the headgear assembly.

[0014] Extensible headgear assemblies are known for their ease of donning because they can be elastically stretched to the length required to fit a user's head and then returned to a shorter length to fit the user's head circumference. Non-extensible headgear assemblies, on the other hand, apply only the minimum force required to secure the interface mask in place, thereby reducing or eliminating the preload that occurs when the extensible headgear assembly remains somewhat stretched while fitting around the user's head. In other words, to fit a wide range of head circumferences, extensible headgear assemblies are designed to provide sufficient force to secure the mask interface in place when a user has the smallest conceivable head circumference and the largest conceivable CPAP pressure. Unfortunately, such designs apply a large force to the face of a user with the largest conceivable head circumference and the lowest conceivable CPAP pressure due to the preload resulting from the extension of the extensible headgear assembly. In cannula systems, extension headgear devices are traditionally manually adjustable and / or designed to fit the smallest possible head circumference, which can result in multiple repeated adjustments by the user and / or a tight fit for users with larger head circumferences.

[0015] One aspect includes headgear configured to extend and retract to fit a user's head, where the headgear requires the application of a first load force to extend the headgear, and once the headgear fits the user's head, the headgear exhibits a second load force and does not extend.

[0016] In some configurations, the first loading force is greater than the second loading force and / or the expected loading force applied to the headgear during respiratory therapy. The expected loading force may include a combined force including CPAP pressure and hose drag. The first loading force may be greater than the expected loading force by a reserve amount. The first loading force may be greater than the expected loading force across various extended lengths of the headgear, and / or the second loading force may be less than the expected loading force across a range of extended lengths of the headgear.

[0017] One aspect includes headgear for securing a mask to a user's face, the headgear including an elastic portion configured to provide a retraction force, an inelastic portion configured to be inelastic relative to the elastic portion, and a limiting mechanism coupled to the inelastic portion and the elastic portion, the limiting mechanism configured to require a first resisting force to allow extension of the headgear and a second resisting force in response to retraction of the headgear.

[0018] In some configurations, the first resistance force is greater than the second resistance force. The first resistance force can be greater than a combined force including the force due to CPAP pressure and the hose drag. The second resistance force can be less than a combined force including the force due to CPAP pressure and the hose drag.

[0019] One embodiment includes headgear configured to expand and contract to fit a user's head, the headgear having a first resistance to expansion in the absence of radial tension and a second resistance to expansion in response to radial tension.

[0020] In some configurations, the first extension resistance force is less than the second extension resistance force. In some configurations, the second extension resistance force occurs as a result of engagement of two portions of the headgear. The second extension resistance force can be greater than a resultant force including the force due to the CPAP pressure and the hose drag.

[0021] One aspect includes headgear for securing a mask to a user's face, the headgear including an elastic portion configured to provide a retraction force, an inelastic portion configured to be inelastic relative to the elastic portion, and a limiting mechanism coupled to the inelastic portion and the elastic portion, the limiting mechanism configured to apply an elongation resistance force when the headgear is subjected to radial tension.

[0022] One aspect includes a patient interface system including an interface portion sized and shaped to surround a user's nose and / or mouth and configured to form at least a substantial seal with the user's face. The system also includes a coupling that allows the patient interface system to be coupled to a gas delivery system. The system also includes a headgear system that allows the interface portion to be positioned and retained on the user's head, the headgear system providing a deformation-locking behavior capable of deforming from an elastic-type extensional behavior to a substantially inextensible behavior when the patient interface system is in use.

[0023] In some configurations, the deformation locking behavior is provided by a mechanically based orientation lock.

[0024] In some configurations, the headgear system provides a non-extensional behavior in the range of about 0.5N to about 65N.

[0025] In some configurations, the deformation locking behavior is provided by a mechanical directional lock including a lock housing, a movable locking member, and a core member. The cross-sectional dimensions of the core may range from about 0.1 mm to about 8 mm. The locking member may be movable relative to the core member through an angular range of about 0° to about 45°. A biasing mechanism may act on the locking member and control the lock retention force. The directional lock may incorporate a friction promoter to facilitate actuation of the lock.

[0026] In some configurations, the core member is a cord. In some configurations, the core member is a strap.

[0027] In some configurations, deformation locking behavior is provided by directional locking using mechanical adhesion, which is provided by Van der Walls forces through the use of nanofiber materials.

[0028] In some configurations, the deformation locking behavior is provided by directional locking using mechanical adhesion, and the mechanical adhesion is provided by microstructures.

[0029] In some configurations, elastic extension is provided by an elastic extension system that includes a fabric spring with embedded elastic elements. The fabric spring can be configured as a braid that combines elastic and non-elastic elements such that the non-elastic elements provide a physical end stop for extension before the elastic elements plastically deform. The amount of elastic elements in the braid can be selected to achieve the desired force-to-extension characteristics of the fabric spring.

[0030] In some configurations, the deformation locking behavior is provided by a mechanical directional lock including a housing, a movable locking member within the housing, and a core member, where the housing guides the movement of the core member and both the housing and the locking member are formed by a single integral module.

[0031] In some configurations, the deformation locking behavior is provided by a mechanical directional lock that includes a locking module, a non-resilient portion, and a resilient portion, where the locking module, the non-resilient portion, and the resilient portion form a modular adjustment assembly.

[0032] In some configurations, the interfacing portion is a mask and the modular adjustment assembly is coupled to a frame of the mask. The frame can include one or more walls that define a space to receive the locking module.

[0033] In some configurations, the modular adjustment assembly is coupled to a portion of a headgear system, the portion of the headgear system being a rear portion that may include at least one of a lower rear strap and a crown strap.

[0034] In some configurations, the headgear system includes a section that passes over or under the occipital protuberance, which incorporates features that provide uneven loading to the rear portion of the head.

[0035] In some configurations, the portion passing over or below the occipital protuberance includes an interrupted strap. The interrupted strap may include a first strap section and a second strap section connected by a coupling. The coupling may allow relative movement between the first strap section and the second strap section. The relative movement may include rotational movement about a longitudinal axis of the interrupted strap.

[0036] In some configurations, the headgear system may include a section that passes over the occipital protuberance, which incorporates features that provide uneven loading on the crown of the head.

[0037] In some configurations, the headgear system includes a portion that passes on or above the occipital protuberance, which incorporates features that provide uneven loading on the head.

[0038] In some configurations, the headgear system includes a rear portion and at least one side strap on each side of the interface system that connects the rear portion to the interface portion. In use, the at least one side strap can be connected to the rear portion of the headgear system at a location that is in front of and at or near the top of the user's outer ear. The rear portion of the headgear system can include an upper strap and a lower strap. A rear projection of the at least one side strap passes between the upper strap and the lower strap. The at least one side strap can include a pair of side straps arranged in a triangular configuration.

[0039] In some configurations, the deformation behavior is provided by a locking mechanism that acts on one or more inextensible elements contained within the headgear system to substantially decouple the elastic portions of the headgear system.

[0040] In some configurations, the headgear system incorporates a mechanism that allows it to fit a variety of head sizes, the mechanism including both elastic and generally inextensible elements configured alongside one another.

[0041] In some configurations, the headgear system incorporates a mechanism that allows it to fit a variety of head sizes, the mechanism including one or more generally inextensible elements that substantially surround the user's head. In some configurations, a first portion of the inextensible element overlaps a second portion of the inextensible element in the longitudinal direction of the headgear system. The first and second portions can be first and second ends of the inextensible element. The first and second portions can be part of one end of the inextensible element.

[0042] In some configurations, the deformation locking behavior is provided by a manual lock, a pneumatically actuated lock, an electrically actuated lock, a piezoelectrically actuated lock, a hydraulically actuated lock, or a thermo-mechanically actuated lock.

[0043] In some configurations, the modified locking behavior has a first locking stage providing a first locking force and a second locking stage providing a second locking force, the second locking force being greater than the first locking force. In some configurations, the first locking stage can be converted to a generally non-extensional behavior having a smaller extension movement compared to the second locking stage.

[0044] One aspect includes a headgear for respiratory therapy configured to extend and retract to fit a user's head. The headgear requires the application of a first load force to extend the headgear. When the headgear fits the user's head, the headgear provides a balancing force equal to the load force applied to the headgear during respiratory therapy. The first load force is greater than the balancing force.

[0045] In some configurations, the load force applied to the headgear during respiratory therapy includes a force due to CPAP pressure and a hose drag force. In some configurations, the first load force is greater than the load force applied to the headgear during respiratory therapy by a reserve amount. In some configurations, an elastic element applies a retraction force tending to retract the headgear. The retraction force can be less than the load force applied to the headgear during respiratory therapy.

[0046] The term "comprising" as used in this specification and claims means "consisting at least in part of." When interpreting a statement in this specification and claims containing "comprising," there may be features present other than those preceding the term. Related terms such as "comprise" and "comprises" are considered equivalent.

[0047] Where reference is made herein to patent specifications, other external documents, or other sources of information, this is generally to provide a context for discussing features of the present invention. Unless otherwise expressly stated, the reference to such external documents should not be construed as an admission that such documents or such sources are prior art in any jurisdiction or form part of the common general knowledge in the art.

[0048] These and other features, aspects, and advantages will be described with reference to various embodiments arranged and configured in accordance with certain features, aspects, and advantages of the present invention, which embodiments are used for illustrative purposes only and are not intended to limit the present invention. [Brief explanation of the drawings]

[0049] [Figure 1] 1 is a perspective view of a user interface usable with headgear arranged and configured in accordance with certain features, aspects and advantages of the present invention; [Figure 2] 1 is a schematic diagram of the three phases of headgear donning and adjustment, along with the force profile associated with each phase. [Figure 3] FIG. 1 is a schematic diagram of the first phase of headgear donning and adjustment, also showing the force profile associated with the first phase. [Figure 4] FIG. 10 is a schematic diagram of the second phase of headgear donning and adjustment, also showing the force profile associated with the second phase. [Figure 5] FIG. 10 is a schematic diagram of the third phase of headgear donning and adjustment, also showing the force profile associated with the third phase. [Figure 6] FIG. 1 is a graphical representation of a force profile associated with headgear having a resistance to demand mechanism. [Figure 7A] FIG. 10 is a schematic diagram of an embodiment of headgear having a resistance to demand mechanism. [Figure 7B] 7B is a diagram of the headgear embodiment shown in FIG. 7A. [Figure 8] FIG. 10 is a schematic diagram of a second embodiment of headgear having a resistance to demand mechanism. [Figure 9] FIG. 10 is a schematic diagram of a third embodiment of headgear having a resistance to demand mechanism. [Figure 10] FIG. 10 is a schematic diagram of a fourth embodiment of headgear having a resistance to demand mechanism. [Figure 11A] FIG. 10 is a schematic diagram of a fifth embodiment of headgear having a resistance to demand mechanism. [Figure 11B] 11B is a schematic diagram of extension and retraction of the headgear shown in FIG. 11A. [Figure 11C] FIG. 11B is a diagram of one embodiment of the headgear shown in FIG. 11A. [Figure 11D] FIG. 11B is a diagram of a second embodiment of the headgear shown in FIG. 11A. [Figure 12] FIG. 10 is a schematic diagram of a sixth embodiment of headgear having a resistance to demand mechanism. [Figure 13] FIG. 10 is a schematic diagram of a seventh embodiment of headgear having a resistance to demand mechanism. [Figure 14] FIG. 10 is a graphical illustration of a force profile associated with headgear having high resistance to actuation of the extension mechanism. [Figure 15A] 10 is a schematic diagram of an embodiment of headgear having high resistance to actuation of the extension mechanism. FIG. [Figure 15B] 10 is a schematic diagram of a second embodiment of headgear having high resistance to actuation of the extension mechanism. FIG. [Figure 16] 10 is a schematic diagram of a third embodiment of headgear having high resistance to actuation of the extension mechanism. [Figure 17] FIG. 12 is a graphical illustration of a force profile associated with headgear having high repetitive resistance to an extension mechanism. [Figure 18A] FIG. 10 is a schematic diagram of an embodiment of headgear having a high repetitive resistance to extension mechanism shown with a mechanism that resists extension. [Figure 18B] 18B is a schematic diagram of a headgear embodiment having a high resistance to repeated extension mechanism as shown in FIG. 18A with the mechanism shown allowing retraction. [Figure 19A] FIG. 18B is a diagram of the embodiment of FIG. 18A. [Figure 19B] FIG. 18B is a second view of the embodiment of FIG. 18A. [Figure 20] FIG. 1 is a graphical illustration of a force profile associated with headgear having a large hysteresis mechanism. [Figure 21A] FIG. 10 is a schematic diagram of one embodiment of headgear with a large hysteresis mechanism shown with a mechanism that allows free movement. [Figure 21B]FIG. 21B is a schematic diagram of the headgear embodiment shown in FIG. 21A with a mechanism that provides high frictional resistance to movement. [Figure 22] FIG. 21B is a diagram of one embodiment of the headgear shown in FIGS. 21A and 21B. [Figure 23] 10A-10D are schematic diagrams of second, third and fourth embodiments of headgear having large hysteresis mechanisms. [Figure 24] FIG. 10 is a schematic diagram of a fifth embodiment of headgear having a large hysteresis mechanism. [Figure 25A] FIG. 10 is a schematic diagram of a sixth embodiment of headgear having a large hysteresis mechanism. [Figure 25B] FIG. 25B is another schematic diagram of the headgear embodiment shown in FIG. 25A shown with a mechanism that allows for free movement. [Figure 25C] FIG. 25B is a third schematic diagram of the headgear embodiment shown in FIG. 25A shown with a mechanism that provides high frictional resistance to movement. [Figure 26A] 10A-10C illustrate an embodiment of headgear having a large hysteresis mechanism. [Figure 26B] FIG. 27 is a second view of the headgear shown in FIG. 26. [Figure 27A] FIG. 10 is a schematic diagram of a seventh embodiment of headgear having a large hysteresis mechanism. [Figure 27B] FIG. 27B is a view of the embodiment shown in FIG. 27A in retraction mode. [Figure 27C] FIG. 27B is a second view of the embodiment shown in FIG. 27A in extension-limiting mode. [Figure 28A] FIG. 10 is a schematic diagram of an eighth embodiment of headgear having a large hysteresis mechanism. [Figure 28B] FIG. 28B is a diagram of the embodiment shown in FIG. 28A. [Figure 28C] FIG. 13 is a schematic diagram of a ninth embodiment of headgear having a large hysteresis mechanism. [Figure 29] FIG. 16 is a schematic diagram of a tenth embodiment of headgear having a large hysteresis mechanism. [Figure 30]FIG. 12 is a graphical representation of the force profile of a headgear that allows adjustment for a looser or tighter fit. [Figure 31A] FIG. 1 is a graphical representation of the force applied to a user's head at various CPAP pressures by headgear having one of the balanced fit mechanisms described herein. [Figure 31B] FIG. 1 is a graphical representation of the force applied to a user's head at various CPAP pressures by headgear without one of the balanced fit features described herein. [Figure 31C] FIG. 1 is a graphical representation of the difference in force applied to a user's head at various CPAP pressures between headgear having one of the balanced fit features described herein and headgear without one of the balanced fit features described herein. [Figure 32] FIG. 10 is a partial cross-sectional view of a directional lock using a movable locking member within a locking chamber of a housing and a core member engaged by the locking member. [Figure 33] Figure 33 shows a local cross-sectional view of a directional lock similar to the lock of Figure 32. The directional lock of Figure 33 includes a release mechanism that acts on the slip force and provides the lock with a secondary locked position. [Figure 34] 34 is a graph illustrating the relationship between the locking angle of the locking member and the slip force of a directional lock such as the directional lock of FIGS. 32 and 33. [Figure 35] 34 is a graph illustrating the change in slip force that can be attributed to a change in a release element of a directional lock having a secondary locking position, such as the directional lock of FIG. 33. [Figure 36] 1 is a cross-sectional view of an interface assembly having a microstructured orientation locking mechanism. FIG. [Figure 37] FIG. 37 is an enlarged view of a portion of the interface assembly of FIG. 36 showing two portions of the interface assembly including microstructures. [Figure 38] FIG. 38 is a diagram of a microfiber or nanofiber that can be used as the microstructure of the interface assembly of FIGS. 36 and 37. [Figure 39]FIG. 38 is a diagram of a plurality of protrusions that can be used as microstructures in the interface assembly of FIGS. 36 and 37. [Figure 40] 1 is a side view of a directional lock using a flat strap and a locking plate supported by a housing, with the locking plate in the released position. [Figure 41] FIG. 41 is a side view of the directional lock of FIG. 40 with the locking plate in the locked position. [Figure 42] FIG. 41 is a cross-sectional view of the locking plate and strap of the directional lock of FIG. 40 showing an actuation mechanism that strengthens the engagement between the locking plate and strap. [Figure 43] FIG. 1 is a perspective view of an interface assembly incorporating at least one orientation locking mechanism attached to a user. [Figure 44] FIG. 44 is a perspective view of the interface assembly of FIG. 43 in a position close to a fully installed position. [Figure 45] FIG. 44 is a perspective view of the interface assembly of FIG. 43 worn on a user. [Figure 46] FIG. 44 is a side view of the directional locking mechanism of the interface assembly of FIG. 43 in a relaxed position. [Figure 47] FIG. 47 is a side view of the directional locking mechanism of FIG. 46 in an extended position. [Figure 48] FIG. 47 is a side view of the directional locking mechanism of FIG. 46 in an operating position. [Figure 49] FIG. 49 shows a portion of the braid forming the elastic strap of the directional locking mechanism of FIGS. 46-48. [Figure 50] 49 shows the braid of FIG. 49 in a compressed position. [Figure 51] 49 shows the braid of FIG. 49 in an extended position. [Figure 52] 50 shows a machine and method for making the braid of FIG. 49. [Figure 53] FIG. 1 is a cross-sectional view of a braid incorporating elastic fibers. [Figure 54] FIG. 54 is a diagram of the braid of FIG. 53 in a flat orientation. [Figure 55]FIG. 10 is a rear perspective view of the rear portion of a headgear assembly having an interrupted strap arrangement attached to a user. [Figure 56] FIG. 10 is a rear perspective view of a rear portion of a headgear assembly having an interrupted strap arrangement attached to a user, with some of the straps joined by articulating couplings. [Figure 57] FIG. 10 is a side view of an interface assembly fitted to a user, with side straps between a rear portion of the headgear assembly and the user interface. [Figure 58] FIG. 10 is a side view of an interface assembly fitted to a user, the interface assembly having a pair of side straps in a triangular arrangement between the rear portion of the headgear assembly and the user interface. [Figure 59] FIG. 49 is a side view of a locking mechanism similar to that of FIGS. 46-48 which may form part of a modular directional locking mechanism. [Figure 60] FIG. 60 is a perspective view of the locking mechanism of FIG. 59 assembled on a mask. [Figure 61] FIG. 1 is a perspective view of a headgear mechanism having elastic and non-elastic portions, defining a complete loop. [Figure 62] FIG. 62 is a top view of the headgear mechanism of FIG. [Figure 63] FIG. 62 is a top view of the headgear mechanism of FIG. 61 in a relatively retracted position. [Figure 64] FIG. 62 is a top view of the headgear mechanism of FIG. 61 in a relatively extended position. [Figure 65] FIG. 62 is a top view of the headgear mechanism of FIG. 61 showing a first exemplary arrangement of the directional lock. [Figure 66] FIG. 62 is a top view of the headgear mechanism of FIG. 61 showing a second exemplary arrangement of the directional lock. [Figure 67] FIG. 1 is a perspective view of a headgear mechanism having elastic and non-elastic portions and defining an interrupted loop. [Figure 68] FIG. 68 is a top view of the headgear mechanism of FIG. [Figure 69]FIG. 68 is a top view of the headgear mechanism of FIG. 67 in a relatively retracted position. [Figure 70] FIG. 68 is a top view of the headgear mechanism of FIG. 67 in a relatively extended position. [Figure 71] FIG. 68 is a top view of the headgear mechanism of FIG. 67 showing a first exemplary arrangement of the directional lock. [Figure 72] FIG. 68 is a top view of the headgear mechanism of FIG. 67 showing a second exemplary arrangement of the directional lock. [Figure 73] 10 is a graph showing force profiles for a CPAP balanced fit, a cannula balanced fit, a high force elastic strap, and a low force elastic strap for a CPAP operating envelope. [Figure 74] FIG. 1 is a partial cross-sectional view of a multi-stage directional lock. [Figure 75] 10 is a graph showing the force profile of a multi-stage directional lock. [Figure 76] 1 is a diagram of the forces associated with certain types of respiratory therapy involving a sealing patient interface. DETAILED DESCRIPTION OF THE INVENTION

[0050] 1, an interface assembly 100 is shown. The interface assembly 100 can have any suitable configuration. While the interface assembly 100 shown is a nasal mask, in some configurations, certain features, aspects, and advantages of the present invention can be used in any type of interface, including, but not limited to, full face masks, nasal masks, nasal pillows, nasal-oral masks, oral masks, and cannulas.

[0051] The illustrated interface assembly 100 generally includes a frame 102 that supports a seal 104. The frame 102 and / or the seal 104 may be coupled to a supply conduit 106. In some configurations, the supply conduit 106 may be coupled to the frame by an elbow 110. The supply conduit 106 may be used to supply breathing gas to a user through the seal 104. The seal 104, or the combination of the seal 104 and the frame 102, may define a chamber that receives breathing gas from the supply conduit 106.

[0052] Interface assembly 100 includes attachment points 112. Attachment points 112 may be formed on at least one of frame 102, seal 104, conduit 106, and elbow 110. Any suitable attachment points 112 may be used to facilitate coupling between interface assembly 100 and one or more headgear assemblies, as described below. In some configurations, attachment points 112 facilitate coupling and decoupling of the headgear assembly and interface assembly 100. In some configurations, the headgear assembly and interface assembly 100 may be joined such that the headgear assembly is generally not detachable from one or more components of interface assembly 100. In some configurations, the headgear assembly and interface assembly 100 may be integrally formed with interface assembly 100.

[0053] Referring to FIG. 76, a diagram 2300 is provided to facilitate a description of the forces associated with certain types of positive pressure airway therapy using a sealing patient interface. For patient interfaces that seal on a user's face, the interface (e.g., a mask) cooperates with the user's face to create a sealed chamber, as shown in block 2302. Pressurized breathing gas is delivered to the sealed chamber, generating a force that tends to move away from the user's face. This force is approximately equal to the (projected) seal area multiplied by the positive pressure and is often referred to as a "blow" force, as shown in block 2304. The function of the headgear is to respond to the blow-out force to constrain the mask and maintain an equilibrium seal against the user's face, as shown in block 2306. The blow-out force stresses the headgear, tending to stretch it and placing tension on the headgear, as shown in block 2308. Additionally, the headgear applies a force to the area of ​​the user's head where it contacts, as shown in block 2310. The force applied to the contact area may be referred to as the "skin pressure" of the headgear. As air pressure increases within the chamber defined by seal 104, or the combination of seal 104 and frame 106, the force applied by the headgear attempts to restrain interface assembly 100 from lifting off the face. Thus, the force applied by the headgear generally increases to counteract the increasing force caused by the increasing pressure within the mask. The blow-out force varies for various types and sizes of interfaces at any particular pressure. Nevertheless, at lower pressures, or, in the case of a cannula, at no pressure, the force required to counter the blow-out force decreases.

[0054] Therefore, and as explained, the headgear assemblies described herein may preferably be designed to achieve a "balanced fit." In some configurations, the headgear assembly generally includes, for example, but not limited to, a stretching component (also referred to as elastic), a non-stretching component (also referred to as non-elastic or non-elastic), a mechanism for limiting headgear stretch, and a coupling that may couple the headgear assembly to the attachment points 112. In at least some configurations, a balanced fit may be achieved by creating a substantially non-stretching path to distribute stresses within the headgear in response to in-use or normal operating forces (e.g., blow-in force and / or hose tension, plus reserve force, if desired). At forces higher than those exhibited in use, the headgear may exhibit a stretch-like behavior for donning. In some configurations, the headgear assembly may not include a stretching component. For example, the headgear may be manually extended and retracted. Various headgear embodiments are described below.

[0055] The extension component, if present, can have any suitable configuration. The extension component can be any component with a tensile modulus less than about 30 MPa. The tensile modulus mathematically describes a material's tendency to be elastically (i.e., non-permanently) deformed along an axis when a force is applied along that axis; the tensile modulus is the ratio of stress to corresponding strain when the material behaves elastically. In some configurations, the extension component can be a coated spun yarn material, and the extension component can include materials such as, but not limited to, rubber and spantex or elastane (e.g., LYCRA). In some configurations, the extension component can be a strap or a combination of straps. In some configurations, the extension component can be formed of a stretchable or elastic material. In some configurations, the extension component allows the headgear to be stretched or extended, and the extension component also provides a retraction force that functions to contract or shorten the headgear. The contraction or shortening can occur due to the elastic properties of the extension component. The contraction or shortening allows the headgear to fit more snugly to the user's head circumference (as well as the mask size). Generally, headgear length is defined by a relaxed length, to which the headgear will tend to return. Unless otherwise specified, contraction refers to this return to the relaxed length after elongation.

[0056] The non-extensible component can function as an extension limiter. The non-extensible component can have any suitable configuration. In some configurations, the non-extensible component has a higher modulus of elasticity than the extensible component. The extensible component can be any component with a tensile modulus greater than about 30 MPa. In some configurations, the non-extensible component limits extension of the headgear due to forces lower than a specified yield force. In some configurations, the yield point of the non-extensible material is higher than any load expected to be applied to the headgear. In some configurations, the non-extensible component resists extension of the headgear when the headgear is attached to the head. In some configurations, the non-extensible component resists extension of the headgear when the headgear is attached to the head and CPAP pressure is applied to the mask. Thus, in some configurations, the non-extensible component (possibly in combination with a mechanism described below) can prevent extension of the extensible component or resist extension of the extensible component, at least when CPAP pressure is applied. In the case of a cannula, the non-extensible component can resist movement of the cannula under an external force, such as pulling on a hose.

[0057] The mechanism may be any suitable mechanism capable of limiting the extension or stretching of the headgear when a force less than a specified yield force is applied to the headgear. In some configurations, the mechanism is operated effortlessly by the user (e.g., the mechanism is automatic). That is, in at least some configurations, the mechanism may be automatically activated or switched to a mode in which extension or stretching is limited below a specified yield force. However, donning the mask may require user effort, such as effort greater than the yield force, to extend the headgear. In some configurations, the mechanism may apply a motion resistance force capable of limiting the extension or stretching of the headgear when a force less than the specified yield force is applied to the headgear. In some such configurations, the motion resistance force may be a frictional force. The specified yield force, i.e., the force required to overcome the headgear mechanism's motion resistance and allow headgear extension, may be determined by (1) the maximum possible blowout force for a particular mask during use, given an expected range of approximately 4-20 cmH2O, and (2) the difference between the reserve force to allow for any tension on the CPAP hose and the user's fit preference. The reserve force, generally defined as the difference between the extension or stretch force and the maximum balanced fit force, can provide a buffer against which additional forces can be applied to the headgear without causing substantial headgear extension beyond the balanced fit force. The reserve force component can compensate for any additional forces, such as hose tension, that may act to pull the headgear away from the user's head. In some configurations, a motion resistance force can be applied to limit headgear extension while relaxing to allow headgear retraction or contraction. In some configurations, the mechanism can use one-way friction to lock or otherwise secure the headgear length. For example, the length can be locked using a frictional force that can only be overcome by a force greater than the blowout force due to minimum extension. Such a mechanism may be referred to herein as an orientation locking mechanism or orientation lock.As used herein, the term "lock" is intended to include mechanisms that secure the headgear length in response to certain forces, such as blow-out force and / or hose pull. The "lock" does not necessarily secure the headgear length in response to all forces. Preferably, in some configurations, the retaining force of the lock ("locking force") can be overcome, such as by a manually applied force during the attachment portion of the application process.

[0058] As described above, the headgear can be stretched or elongated to fit the mask around the user's head. The mechanism provides a means for fixing the length of the headgear so that, while allowing for stretching or elongation of the headgear, the seal is generally held in place when CPAP pressure is applied and the headgear does not stretch substantially. In some configurations, a small amount of stretching may occur while the mechanism is engaged.

[0059] In some configurations, one-way friction headgear can incorporate mechanisms designed to provide the user with all of the benefits of non-extension headgear, with the same ease of use as existing extension headgear with little to no manual adjustment.

[0060] Stretching of elastic headgear is generally not useful in maintaining a seal. A mask sealing against the face always generates an insufflation force, which in turn generates a headgear reaction force. This force stretches the headgear and affects the fit of the seal. Stretching headgear must therefore be overtightened to anticipate and compensate for this change, resulting in an unbalanced fit at lower pressures, whereas an equilibrium fit at higher pressures is achieved without headgear adjustment.

[0061] The one-way friction mechanism can stop the non-extensible strap components of the headgear from changing length once the seal is established. When the CPAP machine is turned on and the seal is established, individual user variables such as fit preferences, face shape, etc. create a blow-out force that tends to push the mask away from the user's face. This blow-out force may be countered by the one-way friction mechanism, which reduces or eliminates the possibility of the non-extensible straps changing length and creates an equilibrium fit at various pressures.

[0062] A mask sealed against the face is essentially a pressure vessel. The mask must press against the face to maintain an airtight seal. The absolute minimum force required is equal to the (projected) sealing area multiplied by the positive pressure. This force is a blow-out force because its direction is away from the face. Balancing this force is the primary function of the headgear. A balanced fit is achieved when the headgear's reaction force substantially matches the blow-out force. In cannula embodiments, there is generally no blow-out force because there is no seal between the patient and the cannula. A balanced fit can therefore be achieved when the headgear assembly circumference matches the user's head circumference and provides some resistance to stretching or extension. In cannula systems, the self-fitting headgear described herein allows for quick and easy donning without the excessive tightness and force that can occur with manually adjustable and retractable headgear, respectively.

[0063] Projected sealing area (even at the same specific pressure) varies from person to person and depends on facial features and personal fit preferences. Consider the difference between a person with a flat face and a more "convex" face. Providing a seal on a flat face is likely easier due to the smaller sealing area and corresponding lower blow-out force. Similarly, the same person can achieve and maintain a seal with different fits, such as either a loose or tight fit, at the same pressure. This is especially true for masks with inflatable seals. A looser fit results in a smaller area and a corresponding lower blow-out force.

[0064] With a balanced fit, the force between the headgear and the user's head is equal to the amount of force required to achieve a seal. With standard headgear designs, the situation can be complicated by the nature of CPAP, which varies pressure throughout the night to provide comfort to the user. By varying pressure throughout the night, the amount of blowout force varies throughout the night. With headgear incorporating a balanced fit mechanism, the counterforce decreases in concert with the decrease in CPAP pressure.

[0065] Hose pull is the additional force caused by the drag of the CPAP or cannula hose when the user changes sleep position. Hose drag temporarily increases the force on the headgear. If this force exceeds the resistance to the mechanism's extension, the fit may change, which can result in leakage and / or discomfort.

[0066] As a user changes sleeping position while wearing the headgear described below, it may be necessary to change the fit of the headgear. At this point, the natural interaction of pushing or rocking the seal toward the face will cause the straps to automatically retract any excess length to maintain the new fit. In some situations, the mask or seal may be pulled away from the face to increase the length of the headgear.

[0067] To remove the interface while wearing the headgear described below, the seal can be pulled forward with a force greater than the maximum holding force of the mechanism. This allows the headgear to extend and pull the seal off the user's face and head. Once removed, the lack of force on the headgear causes the headgear to automatically retract to its relaxed size.

[0068] In some configurations, the headgear applies a three-phase force extension fit profile, as shown generally in FIG. 2. In the attachment phase 200, the headgear is extended over the user's head. The graph shows the resistance during extension. Load curve 202 shows a steep increase in load during the initial extension of the headgear, followed by a generally constant, flat extension curve as the headgear further extends to accommodate the larger head circumference. In the adjustment phase 204, the headgear retracts and recovers from the extension state until the desired fit is achieved. Load curve 206 shows an initial decrease in load as the headgear retracts to fit over the user's head, followed by a lower load force as the headgear further retracts to fit the user's head circumference. In the third phase, the equilibrium fit phase 208, the headgear adjusts to maintain its position on the user's head as CPAP pressure is applied. Load curve 210 shows that the CPAP pressure causes the headgear load force to increase, balancing the blow-out force and resisting further forces, such as hose pull. For cannula embodiments, balanced fit is achieved at the end of phase 2, and phase 3 generally begins only when an external force, such as hose pull, is applied. Further details of the components of balanced fit are provided below.

[0069] 3, further details of the attachment phase 200 and associated load curve 202 are shown. As noted above, the load curve 202 exhibits a steep rise 220 because the headgear experiences an initial resistance to extension as it is extended to attach to the user's head. The initial resistance may be related to overcoming resistance to extension. Once the load reaches the yield force of the headgear mechanism, the load curve transitions to a substantially flat, approximately constant extension curve 222 as the headgear extends further, with little increase in load force over the majority of the headgear extension.

[0070] FIG. 4 shows the second phase, or adjustment phase 204, in more detail. In this phase, the headgear is fully extended or stretched to fit over the user's head, and the headgear is released and in place. Once the desired position is reached, the headgear returns from the extended state (e.g., an over-extended position), and the load force drops sharply 224, as shown by load curve 206. After this drop in force due to the headgear being retracted to fit the user's head, the load curve remains low 226 as the headgear remains fitted to the user's head. As shown, headgear representative of many features, aspects, and advantages of the present invention is characterized by a first, high load required to cause extension and a second, lower load at which the headgear contracts. In other words, the headgear contracts at a lower load than required to cause extension, providing an effect of hysteresis. In some configurations, the headgear experiences a delay in length change during the large change in force when changing from an extension mode to a contraction mode. In some configurations, the change in length of the interface perimeter (including the headgear assembly) lags behind the change in load (i.e., force) as the interface length changes from extension to contraction. Further, in some configurations, as force increases during extension, the increase in length exceeds the decrease in length as force decreases (e.g., the slope is less for 220 than for 224).

[0071] In FIG. 5 , the balanced fit is achieved in the balanced fit phase 208, where the headgear force balances the blowout force of the CPAP pressure. As mentioned above, the headgear adjusts to maintain its length as CPAP pressure is applied. The load curve 210 shows the increase in load force that balances the blowout force. As shown in the balanced fit section 230 of the detailed load curve 210, the balanced fit generates a load higher than the headgear retraction force 226. The balanced fit component is an increasing force in the headgear straps, providing an equal and opposite force to the blowout force. However, this force is also less than the extension or stretch curve 222. In some configurations, the slope of the balanced fit section 230 can be related to, influenced by, or substantially the same as the increase 220 and / or decrease in load force 224 upon headgear retraction. In some configurations, the slope of the balanced fit section 230 is steeper than the slope of the decrease in load force 224. In some configurations, the slope of the balanced fit section 230 is greater than the slope of the initial rise 220 upon extension of the headgear.

[0072] The reserve force component 232, defined as the difference between the extension or stretching force 222 and the instantaneous or current balance fit force 234, is a buffer by which additional force can be applied to the headgear without substantial headgear stretch beyond the balance fit force. The reserve force component can compensate for any additional forces, such as hose tension, that may act to pull the headgear away from the user's head. As external forces, such as hose tension, increase, the headgear reaction force also increases. Only when the external force exceeds the yield point will the headgear stretch, potentially leading to leakage. The reserve force component is preferably large enough to accommodate the actual external forces that may be applied to the mask by hose tension during normal use. This reserve force component or buffer also takes into account the user's preference for the engagement of the mask seal with the user's face, such as a tighter or looser fit. When used with a cannula system, the entirety of Phase 3 can be allocated to the reserve force. Because there is no blowing force, a balanced fit is achieved at the end of Phase 2, and therefore Phase 3 generally needs to be determined solely by any external forces, such as hose tension, and the user's preference in terms of tightness of fit. As a result, the yield force of a cannula device can be significantly lower than that of a CPAP device. In general, the forces within the headgear when a balanced fit is achieved can also be lower for a cannula device than for a CPAP device.

[0073] The graphs in Figures 3-5 also include perimeters that enclose and define certain regions. The perimeters shown are generally rectangular in shape and indicate the operating envelope of the interface assembly relative to the user's head circumference (extension) and the forces (loads) applied by the CPAP system, which may, but need not, include external forces such as hose pull. The distance between the left end 212 and right end 214 of the region's length or perimeter along the x-axis indicates the desired or usable range of user head sizes. That is, the left end 212 is positioned at smaller head sizes (circumference or extension) and the right end 214 is positioned at larger head sizes. The smaller and larger head sizes can be minimum and maximum head sizes for a particular interface assembly that may be a universal fit or may be intended for a specific subset of head sizes (e.g., small, medium, large) or user (e.g., pediatric, adult).

[0074] The length of the region along the y-axis, or the distance between the lower and upper perimeter ends 216 and 218, indicates the desired or usable range of force or load to be applied to the interface assembly during use. The lower perimeter end 216 is positioned at a lower force (e.g., a force resulting from a low CPAP value) and the upper perimeter end 218 is positioned at a higher force (e.g., a force resulting from a high CPAP value). Similar to head size, the lower and higher forces may be for a CPAP system or protocol in general, or may be for a particular subset of CPAP systems or protocols. As noted above, the force range may be based solely on CPAP force or may include external forces, such as, for example, hose tension. Preferably, the instantaneous or current equilibrium fit force 234 is within the operating envelope.

[0075] For a stretching or elastic system to provide adequate performance throughout the operating envelope, the system must provide a resistance greater than that available to the interface assembly from one or both of the CPAP pressure forces and external forces. Therefore, the force-extension curve of the stretching or elastic system should be positioned above the operating envelope and, if necessary, spaced above the operating envelope a sufficient distance to accommodate external forces and / or provide reserve force to accommodate unusual or unexpected forces. Thus, the stretching or elastic system applies a higher level of force to the user than is necessary to accommodate the actual forces (e.g., CPAP and external forces) applied to the interface assembly. This greater-than-necessary force tends to reduce user comfort.

[0076] Various force profile configurations for the headgear assembly are possible, and preferably include an equilibrium fit region. The force profiles described herein are applicable to both CPAP and cannula systems, although the point at which an equilibrium fit is achieved is typically different. The force levels associated with maintaining interface fit are generally significantly lower in cannula systems. In addition, some or all of the headgear embodiments can be modified to function in cannula systems, with an equilibrium fit being achieved when the headgear circumference matches the head circumference and, preferably, provides a certain amount of resistance to headgear extension. Increased CPAP pressure and / or insufflation force generally correlates with the external force applied to the cannula system. Figure 6 shows one force profile 240 in which resistance in the headgear straps develops on demand. This configuration requires minimal effort to stretch the headgear to fit. In this configuration, the user only needs to overcome the headgear's elasticity, as indicated by curve 242, which typically requires less than about 1.5 N of force. The balanced fit component of this configuration, represented by curve 244, provides a force equal to and opposite to the blow-out force and also compensates for any additional external forces that may act to pull the headgear away from the user's head. Curve 246 represents the balanced fit portion 244 plus a buffer.

[0077] 7A-B illustrate one embodiment of headgear with the on-demand resistance profile shown in FIG. 6. The configuration shown includes a layered extension assembly 304. In the layered extension embodiment 304 shown in FIG. 7A, two straps 306 and 308 can be stacked one on top of the other, with their extension sections 310, 316, and 320 alternating with their inextensible sections 312, 314, and 318, respectively. As shown, the two straps 306 and 308 can be folded over one another, as indicated by arrow 324, so that the inextensible section of one strap overlaps at least the extension section of the other strap. As shown, the inextensible segment 314 of strap 306 overlaps the extension segment 316 of strap 308. Preferably, the inextensible segment 314 is longer than the extension segment 316, so that at least a portion of the inextensible segment 314 overlaps at least a portion of the inextensible segment 312, forming a continuous non-extension path. Also shown is the overlap of similar inextensible segment 312 with inextensible segment 318. Additionally, straps 306 and 308 may have some form of "grip," such as rubber webbing or other adhesive substance, on the inextensible sections. When placed over one another, as shown by overlapping gripping sections 322, the gripping sections overlap and engage, reducing or eliminating the possibility of further stretching of the headgear straps until the motion resistance force between the straps is overcome. When the headgear is placed on a user's head, the radial force between the extensible and inextensible layers causes the gripping sections to engage, forming a complete inextensible section and limiting further stretching of the headgear straps. Figure 7B shows two photographs of the layered strap embodiment shown in Figure 7A.

[0078] Another embodiment of a layered extension strap configuration is shown in FIG. 8. The layered grip strap configuration 400 includes two straps, one of which has a grip pattern in one or more locations, and the other strap has a series of alternating extension segments or sections 414 and non-extension segments or sections 412, 416, similar to the configuration shown in FIG. 7A. While one extension segment and two non-extension segments are shown, other numbers of extension and non-extension segments can be provided. The first, or inner, strap 406 is shown with two grip pattern segments 410 located at opposite ends of the strap 406, but a different number of grip pattern segments 410, including the grip pattern, can be provided along substantially the entire length of the strap 406. The grip segment 410 overlaps the non-extension segments 412, 416 of the second, or outer, strap 408 to provide a bidirectional gripping section that selectively couples to at least a portion of the straps 406, 408. However, this arrangement can be reversed between the inner strap 406 and the outer strap 408. In some configurations, the inner strap 406 is a non-extensible member that allows the headgear to form a completely non-extensible section when the straps 406, 408 are coupled, limiting further extension of the headgear as described above. However, in other configurations, the inner strap 406 can be made of an elastic or stretchable material. In such a configuration, the headgear includes an extension section even when the straps 406, 408 are coupled, the length of which can be defined by the elastic portion 414 of the outer strap 408. Preferably, the extension section is provided behind the user's head and the non-extensible section is located to the side of the user's head. Locating the extension section behind the user's head may result in less extension movement for a particular force than having the extension section located to the side of the user's head. When a load is applied to the headgear, such as by an insufflation force or an external force, the section behind the user's head is pulled against the user's head, thereby increasing friction between the headgear and the user's head.In some configurations, friction can be sufficient to substantially prevent extension of the extension section of the headgear. Features to increase friction between the headgear and the user's head, such as silicone or other types of gripping elements, can be used. A stretchable inner strap 406 can facilitate extension of the headgear before donning. In some configurations, such as when substantially the entire inner strap 406 is stretchable, the material of section 414 of outer strap 408 has a significantly lower elongation modulus than the material of inner strap 406 to accommodate a length of extension section 414 that is significantly shorter than the length of inner strap 406. Inner strap 406 can be a thin strap with a gripping pattern applied to one or both sides of strap 406. A similar gripping pattern can be applied to strap 408 as to non-extending segments 412 and 416. In some configurations, the gripping pattern is applied to the portion of the strap facing away from the user. In the configuration shown, the second strap 408 may have a slot through which the inner strap 406 is attached to maintain strap alignment and facilitate use of the headgear assembly. For example, the second strap 408 may include a passageway through which the first strap extends. The passageway may be formed through most of the length of the second strap. Alternatively, the passageway may be defined by multiple loops (e.g., similar to belt loops used on clothing).

[0079] FIG. 9 illustrates a third embodiment of a layered strap configuration. In this configuration, the layered strap 500 includes alternating extensible and non-extensible segments, similar to the previous embodiments. In the configuration shown in FIG. 9, the strap segments are folded over. When folded over, the gripping portions of the non-extensible segments can be aligned, thereby reducing or eliminating the possibility of further stretching of the headgear. In some configurations, the strap segments are folded over after the headgear has been stretched to fit the user's head and the user has achieved the desired tension in the interface assembly. In some configurations, the strap segments are folded over before the start of pressure application.

[0080] A further layered strap configuration is shown in FIG. 10. In this configuration, layered strap 600 has an extension segment 614 layered on a non-extensible segment 610. The extension segment 614 connects two non-extensible segments 612 (one shown), which overlap the non-extensible segment 610 as shown. The non-extensible segment 612 may take the form of a wrapped segment or a loop or pocket into which the center or rear non-extensible segment 610 may be inserted. As mentioned above, each non-extensible segment may have a gripping portion that, when aligned, reduces or eliminates the possibility of further stretching of the headgear.

[0081] When a force is applied to stretch headgear with a demand-resistance force profile, such as the non-extension path headgear shown in Figures 7A-B and 8-10, minimal force is applied between the two strap layers except where the headgear is held. Therefore, the grip sections do not interact with each other, allowing the extension component to extend without significant resistance. When the headgear is released from the extended position, the extension component is relaxed until the headgear substantially conforms to the user's head circumference. At this point, the non-extension component and the grip sections of the two strap layers should overlap. Radial forces applied to the headgear by the user's head allow the grips to interact with each other, fixing the headgear length and limiting further extension or retraction without significant force. The interaction of the grips and the overlapping extension / non-extension sections create a continuous non-extension path in the headgear. This path limits further extension of the headgear when CPAP pressure is applied. The headgear applies a force equal to and opposite to the CPAP pressure applied to the user's face, creating an equilibrium fit. To adjust the fit of the mask, the interaction of the gripping sections can be released or reduced.

[0082] Another custom resistance configuration may be shown in FIGS. 11A-D. Referring to FIG. 11A, in this configuration, a tunnel strap configuration 700 has two relatively inextensible strap segments 704. In some configurations, the inextensible strap segments may be formed of a thermoformed compression material such as Breath-o-Prene. Each strap segment 704 may be coupled to a flexible shuttle 712. Each flexible shuttle 712 may be coupled to a segment 704 and a low-force elastic member 714. The flexible shuttle 712 and elastic member 714 may be generally surrounded by a curved-head-shaped tunnel 706 having a smooth interior surface made of a soft, inextensible (at least in circumference / length) material. Several non-slip pads 708 (two are shown) may be positioned on the surface of the shuttle 712 closest to the user. The non-slip pads may be made of silicone or another non-slip or adhesive material. One end of each shuttle 712 may be aligned with an end of an elastic member 714 so that the elastic rides over the entire length of each shuttle 712. The layered elastic 714 and shuttle 712 configuration may be attached end-to-end to the relatively inextensible strap segment 704. The strap assembly may be housed within a tunnel, although in other configurations the tunnel may have one open side.

[0083] The flexible shuttle 712 provides a gripping force that ensures a balanced fit of the headgear. As shown in FIG. 11B, the shuttle 712 changes shape depending on the extension or retraction of the straps and the amount of force applied. As the straps 704 are pulled, the shuttle 712 conforms to the shape of the tunnel 706 and grip, reducing or eliminating the possibility of further extension of the headgear. As the straps 704 are released or retracted, the shuttle 712 peels away from the surface of the tunnel 706, breaking the grip and allowing the straps to retract. FIGS. 11C and 11D provide further illustrations of one embodiment of the tunnel concept 700 shown in FIGS. 11A and 11B. FIG. 11C shows the tunnel strap configuration by itself, and FIG. 11D shows another embodiment of the tunnel strap configuration attached to a mask. In FIG. 11D, a second strap is shown. The second strap (or set of straps) can be positioned under or over the tunnel 706 and / or straps 704. In some configurations, the second strap can be coupled to the straps 704. The second strap can be grasped by the user and thus can serve as a handle when putting on or taking off the headgear. In some configurations, the second strap can assist in orienting the headgear in a particular direction when put on. In some configurations, the second strap can be positioned generally below the maximum occipital point.

[0084] A more customizable resistance configuration is shown in FIG. 12. In this configuration, another tunnel strap configuration 800 has a tunnel 802 configured to expose two shuttles 804 to allow for some manual interference and fit adjustment. By exposing the shuttles 804, the user has more control over the initial fit of the headgear. Tabs 806 (one shown) may also be configured to provide a convenient way for the user to adjust the fit of the headgear. In some configurations, for example, pulling the tab may shorten the strap. In some configurations, the tab 806 may be located near the end of the tunnel 802.

[0085] When a force is applied to extend headgear having a tunnel mechanism and exhibiting a demand-responsive force profile, such as the headgear shown in FIGS. 11A-D and 12, the elastic members freely extend until a radial force is applied to the mechanism. Until the radial force is applied, the applied axial force need only be large enough to overcome the strength of the elastic straps. When the headgear is released from the extended position, the elastic straps retract until the headgear conforms to the user's head circumference, and a radial force (e.g., across the straps) is then applied. At this point, the user's head applies a radial force to the headgear. The radial force, combined with the curvature of the tunnel, forces the non-slip pads on the underside of the shuttle into contact with the inner wall of the tunnel, forming a grip that secures the length of the headgear and limits further extension or retraction. Because the shuttle is preferably a flat piece of plastic, its natural response is to align tangent to the curve of the user's head. This allows the front end of the headgear, to which the elastic is permanently attached and which has the property of being positioned away from the inner wall of the tunnel, to release the non-slip pad when minimal radial tension is applied to the headgear, and the friction between the non-slip pad and the tunnel is usually not sufficient to prevent the elastic from retracting within the tunnel.

[0086] When tension is applied to the headgear by application of CPAP pressure, the front of the shuttle is pulled into contact with the inner wall of the tunnel. The shuttle is pulled into contact with the inner wall of the tunnel. In this configuration, as tension applied to the headgear increases, the non-slip pads interact with the tunnel, increasing the force required to extend the headgear. This effectively locks the length of the headgear, limiting further extension and retraction unless a force greater than a certain applied force is applied.

[0087] FIG. 13 illustrates yet another embodiment of a resistance-on-demand configuration. In this configuration, pneumatically actuated locking straps 900 provide a balanced fit for the headgear. One or more pneumatically actuated locking assemblies 902 may be provided, one on each side of the mask 914. The pneumatically actuated locking assemblies may be coupled to, or positioned within, or along, elastic straps, etc. In some configurations, the elastic straps may be coupled to the mask, the mask seal, and / or the mask frame. In some configurations, the elastic straps may be coupled to an pneumatically actuated lock. Each pneumatically actuated locking assembly may have an pneumatically actuated lock 904 housed by a lock casing 906. An air delivery tube 908 extends from the mask 914 to each pneumatically actuated locking assembly 902. A close-up view 910 of one of the pneumatically actuated locking assemblies 902 shows that a core strap 912 extends to the center of each pneumatically actuated locking assembly 902. As noted above, headgear retention is only needed in the presence of CPAP pressure. In this embodiment, air pressure to maintain the air-actuated locks is provided by the mask air pressure. When the air-actuated lock assemblies 902 are activated to provide headgear retention, such as after a fit is achieved, air is supplied from the mask 914 to each air-actuated lock 904. This air pressure causes the air-actuated locks 904 to expand and grip the core straps 912, reducing or eliminating the possibility of further headgear strap stretch. Because the air-lock assemblies 902 are in fluid communication with the mask chamber, the pressure in the air-lock assemblies 902 increases as the pressure in the mask increases. Therefore, as the force attempts to lift the mask off the face, the force resisting strap stretch also increases. This demand-resistance embodiment is generally not applicable to cannula devices because the presence of air pressure is required to activate the air-locks, which generally cannot be provided in unsealed cannula systems. A manually-activated external air pressure source can be provided for the air-locks to provide the retention force necessary to prevent headgear stretch due to external forces.

[0088] FIG. 14 illustrates a second force profile incorporating a balanced fit. In this figure, a high resistance to movement profile 250 is shown. Headgear configured with this force profile may have a locking mechanism that releases at a predetermined force. When the headgear is stretched onto the user's head and then retracted for fit, the load force remains low until force is again applied to stretch the headgear straps. As shown, the load-extension curve 252 may initially have an upward slope at low extension, indicating high resistance to initial headgear extension. After reaching a predetermined force, significantly less force is required to further extend the headgear. Similar to the demand-resistance force profile described above, the high resistance to initiation of extension force profile also includes a balanced fit with two components. First, a balanced fit component 254 provides high resistance to further extension within a narrow range of extension to offset the blowout force of the CPAP pressure. Further resistance to extension is provided by a reserve force component 256 that counteracts any external forces, such as tension on the hoses, that may act to stretch or loosen the headgear. In the configuration shown, the slope of the initial extension portion of the curve is substantially the same as the slope of the equilibrium fit component 254 of the curve. In some configurations, the slopes of the initial extension portion of the curve and the equilibrium fit portion are the same or substantially the same because they result from attempting to overcome the same mechanism of FIG. 14.

[0089] One embodiment of a configuration incorporating a high resistance to initiation of elongation profile is shown in Figures 15A-B. Figure 15A shows a cross section of a roller ball locking mechanism 1000. In this configuration, a locking chamber 1002 includes a roller ball 1004 and a switch 1006. The switch 1006 may be a wedge-shaped member having a top surface 1012 that is positioned adjacent to the upper interior surface of the locking chamber 1002 when the switch engages the core strap 1010. When the switch 1006 engages the core strap 1010, friction between the roller ball 1004 and the core strap 1010 substantially prevents further elongation of the core strap 1010, as shown in Figure 15A. At a predetermined force, the roller ball 1004 and switch 1006 change positions, with the switch 1006 pivoting about pivot point 1008 to release the core strap 1010, allowing it to move freely in either direction and allowing the headgear to freely extend or retract. If the direction of movement of the core strap 1010 is reversed, such as when the headgear returns to a smaller circumference, the roller ball 1004 moves to the free side of the locking chamber 1002 (to the left in FIG. 15A ), and the switch 1006 is reset. If the core strap 1010 is subsequently pulled, the mechanism 1000 again functions as a roller ball lock to resist further extension of the headgear, as described above.

[0090] The locked and unlocked positions of another roller ball locking mechanism 1020 are shown in FIG. 15B . In this configuration, the locking chamber includes a roller ball 1024 and a switch 1026. The switch 1026 may be a wedge-shaped member having a top surface 1036 disposed adjacent to an upper interior surface 1038 of the locking chamber 1022. The switch 1026 may also include a portion 1040 shaped to trap the roller ball 1024 within the locking chamber 1022. In some configurations, the portion 1040 may also be configured to engage the core strap 1030 to reduce or eliminate the possibility of further stretching of the headgear when the roller ball locking mechanism 1020 is in the locked position. In some configurations, the mechanism 1020 may include a magnet 1032 and a magnetic member 1034. The magnet 1032 may be located within the housing of the roller ball locking mechanism 1020, while the magnetic member 1034 may be located at one end of the switch 1026 adjacent the surface 1036.

[0091] As shown in the bottom diagram of FIG. 15B , when the switch 1026 engages the core strap 1030, friction between the roller ball 1004 of the switch 1026 and the core strap 1030 substantially resists further extension of the core strap 1030. Similar to the configuration described with reference to FIG. 15A , at a predetermined force that overcomes the friction between the roller ball 1004 of the switch 1026 and the core strap 1030, acting to extend the headgear, the switch 1026 changes position by pivoting about pivot point 1028 to release the core strap 1030 and allow it to move freely. With the switch in this position, the headgear is substantially free to extend or retract. If the direction of movement of the core strap 1030 is reversed, such as when the headgear returns to a smaller circumference, the roller ball 1024 moves to the free side of the locking chamber 1022 (to the left in FIG. 15B ) and the switch 1026 is reset. If the core strap 1030 is subsequently pulled, the mechanism 1020 again functions as a roller ball lock to resist further extension of the headgear as described above. The magnet 1032 and magnetic member 1034 may function to hold and reset the switch 1026.

[0092] A second embodiment of a high resistance to initiation of movement configuration is shown in FIG. 16. In this embodiment, the self-limiting washer friction holds the core strap in place until the friction is overcome and the core strap is released to extend or retract under a low load force, reducing or eliminating the possibility of further extension. FIG. 16 includes a self-limiting washer mechanism 1100 that provides a balanced fit, a concept described above. The self-limiting washer mechanism 1100 includes an S-shaped friction member 1104 having a bendable curve 1110 and a self-limiting washer 1106 adjacent the bendable curve 1110 portion of the S-shaped member 1104. The friction member 1104 and curve 1110 can be disposed within a housing 1111, and for example, but not limited to, an extension component 1113 can be secured to the housing 1111. The headgear core strap 1108 also passes through an orifice in the S-shaped member 1104 and the washer 1106. The core strap 1108 may pass through or be positioned next to at least a portion of the extension component 1113 .

[0093] When the washer 1106 and S-shaped member 1104 are at an angle α (shown at 1112 in FIG. 16 ) with respect to the longitudinal axis of the core strap 1108, the core strap 1108 resists elongation due to frictional forces between the washer 1106 and the core strap 1108 and between the S-shaped member 1104 and the core strap 1108. These frictional forces may be overcome by additional load forces applied to the core strap 1108. When sufficient force is applied to the S-shaped member, the orifices in the S-shaped member 1104 and the orifices in the washer 1106 become better aligned due to deflection of the S-shaped member. The deflection causes the self-limiting washer mechanism 1100 to assume the shape shown in the bottom panel of FIG. 16 . In this configuration, the bendable curve 1110 and the washer 1106 are at an angle β (shown at 1114 in FIG. 16 ) with respect to the longitudinal axis. Angle 1114 is closer to 90 degrees than angle 1112, allowing the core strap 1108 to pass more easily through the openings in the S-shaped member 1104 and washer 1106. In this configuration, the frictional force acting on the core strap 1108 is reduced, allowing the core strap 1108 to extend and retract with less required load force. When the direction of pulling on the core strap 1108 is reversed, the bendable member 1110 of the S-shaped frictional member 1104 and the washer 1106 return to an orientation similar to that of the top panel of FIG. 16 . As discussed above, in this configuration, the frictional force on the core strap 1108 limits the extension of the core strap 1108 until a sufficiently high load is applied, which is typically greater than that encountered during normal therapeutic use of a CPAP device.

[0094] FIG. 17 illustrates a third force profile incorporating a balanced fit feature. This figure shows a profile 270 of repeated high resistance to extension loads. Headgear constructed using this force profile has a locking mechanism that releases at a predetermined force before resetting. This release and reset sequence is repeated throughout the headgear extension. As shown in FIG. 17, a load curve 272 consists of a series of repeated high load force peaks as the headgear extends. As indicated by the lower portion of curve 272, the force required for retraction decreases in load curve 272. Similar to the previous force profiles, a balanced fit component 274 and a reserve force component 276 compensate for the blowout force and prevent further extension of the headgear due to external forces, such as hose pull. Furthermore, as shown, the balanced fit component 274 can have a load-extension slope that approximates the load-extension slope of the increasing load portion of load curve 272.

[0095] A ratchet mechanism 1200 that provides repeated high resistance to stretching is shown in FIGS. 18A-B. The illustrated ratchet mechanism 1200 includes a housing 1204 having an internal cavity 1206 that houses a spring-loaded clip 1208. The clip 1208 is configured to interact with the serrated edge of a non-stretching core strap 1212 that extends within the housing 1204. As the core strap 1212 is pulled or stretched, the clip 1208 engages the serrated edge of the core strap 1212 to resist further stretching. The grip of the clip 1208 on the strap 1212 is overcome when the clip 1208 bends away, releasing the grip of its single tooth. The spring-loaded clip 1208 is then ready to engage the next tooth on the serrated core strap 1212. Again, when sufficient load force is applied, the clip 1208 releases and captures the next sawtooth on the core strap 1212. In this way, a repeating, high resistance to extension force profile is obtained, such as that shown in Figure 17. The clip 1208 shown can be perpendicular to the sawtooth core strap 1212 as the core strap 1212 is extended, and angled as the core strap 1212 is retracted.

[0096] The core strap 1212 can be housed within an extension sheath (not shown) and can extend beyond both ends of the sheath into a plastic tube. The loose ends are housed in the plastic tube. The extension sheath provides a retraction force to return the headgear to the size of the user's head. The Young's modulus of the extension sheath is preferably adjusted so that the sheath applies a force to the user's head that is less than the minimum expected blowout force, so that the sheath provides an initial counterbalancing force. At higher blowout forces, non-extending components may provide additional counterbalancing force.

[0097] The core strap 1212 preferably has stops at its ends to reduce or eliminate the possibility of the end of the strap 1212 being pulled out of the housing tube. The core strap 1212 forms a closed loop with the housing. The tubular housing can be clipped to the mask frame. A clip housing (not shown) can connect the extension sheath and housing together.

[0098] When a stretching force is applied to the headgear, the core strap 1212 pulls the clip 1208 flush against the rectangular interior wall of the housing 1204. This causes the clip 1208 to further engage the teeth of the core strap 1212. This engagement is overcome as the clip 1208 bends away, releasing its grip on its single tooth and preparing to engage the next tooth. The force required to overcome each tooth of the core strap and stretch the headgear is equal to or greater than a certain applied force.

[0099] When the headgear is released from the extended position, the clips 1208 rotate within their housing 1204 and become flush with the angled walls of the housing 1204. This allows the clips 1208 to disengage the teeth of the core straps 1212, which in turn allows the headgear to retract freely.

[0100] Initially, the CPAP pressure is counterbalanced by a low force applied to the user's head by the elastic element. As the force applied by the CPAP pressure increases, the non-stretching core strap 1212 provides additional resistance to extension, pushing the spring clip 1208 against the vertical housing wall to engage the teeth, thereby providing the remaining counterbalancing force. Because the force applied by the CPAP pressure preferably does not exceed the specified yield force to overcome the teeth of the core strap 1212, the length of the headgear remains substantially constant unless altered by the user.

[0101] Retraction of the core strap 1212 is shown in Figure 18B. In this figure, the core strap 1212 retracts into the housing 1204, which allows the clip 1208 to rotate within the housing 1204, thereby disengaging the clip 1208 from the teeth of the core strap 1212. In this configuration, the strap 1212 can be retracted with very little resistance.

[0102] 19A and B show a ratchet mechanism incorporated into one embodiment of the strap design 1218. An elastic sleeve 1220 surrounds the ratchet mechanism for automatically retracting the headgear.

[0103] A fourth force profile incorporating an equilibrium fit is shown in FIG. 20. In this figure, a large hysteresis load profile 290 is shown. Headgear constructed using this force profile has a high load force resistance to extension or stretching. Referring to FIG. 20, a large buildup of force is shown in the extension section 292 of the load curve. During this headgear extension phase, the extension force may be approximately 7-8 N, determined by the sum of the blow-out force and an estimated 3 N hose pull force. As the headgear retracts, the returning force is preferably approximately 2.5 N or less, as shown in the retraction section 294 of the load curve. This returning force is primarily the force exerted on the user's face by the elastic elements of the headgear.

[0104] The headgear's equilibrium fit may include two components, as described above: an equilibrium fit component and a reserve force component. The equilibrium fit component 296 of the load curve shown in FIG. 20 compensates for the blowout force applied by the CPAP pressure. The reserve force component 298 of the load curve may include a range of load forces, ranging from the load force during the large hysteresis section of the extension curve 292. In some embodiments, the amount of extension during the equilibrium fit phase is about 10 mm or less. As shown, in some configurations, the equilibrium fit component 296 has a slope similar to or the same as the initial extension slope. In some configurations, the equilibrium fit component 296 has a slope less than the slope of the retraction section 294. Other configurations are possible.

[0105] 21A and 21B show a cross section of one embodiment of a headgear mechanism incorporating the high hysteresis load profile described above. In this embodiment, the washer concept headgear mechanism 1300 includes a housing 1304 having an internal cavity 1306. The internal cavity 1306 is configured with a free motion surface 1310 that is substantially perpendicular to and orthogonal to a longitudinal axis defined by a core strap 1316. The internal cavity 1306 is also configured with a locking surface 1312 that is angled relative to the longitudinal axis defined by the core strap 1316. A washer 1308 is disposed within the internal cavity 1306. An orifice through both the housing 1304 and the washer 1308 allows the non-extensible core strap 1316 to pass through the orifice. The housing 1304 forms the end of a tube that receives the end of the non-extensible core strap 1316. In some configurations, the tube is generally elastic. This tube allows the headgear to be closed in a loop and fastened to the mask frame (not shown).

[0106] 21A, there is shown the free motion of the core strap 1316. When the washer 1308 is aligned with the free motion surface 1310 of the housing 1304, there is little friction between the washer 1308 and housing 1304 and the core strap 1316. Thus, in this configuration, the core strap 1316 has a substantially straight path through the washer 1308 and housing 1304 and is substantially free to move in the free motion direction indicated by arrow 1318.

[0107] Referring now to FIG. 21B, the high frictional resistance to movement of the core strap 1316 is shown. When the core strap 1316 is pulled in the direction opposite to the free movement direction indicated by arrow 1320, the washer 1308 is forced to collapse and rest adjacent to the angled locking surface 1312 of the housing 1304. This orientation of the washer 1308 within the housing 1304 creates an angled path for the core strap 1316. This angled path increases friction between the washer 1308 and the core strap 1316. The increased friction limits the movement of the core strap 1316 and resists extension of the headgear. FIG. 22 illustrates one embodiment of a washer concept headgear mechanism incorporated into a headgear assembly. As shown in FIG. 22, each headgear assembly can include two washer mechanisms on the non-extending core strap. The midsection of the core strap can be housed within an extension sheath. The core string preferably has stops at its ends to reduce or eliminate the possibility of the core string being pulled out of the housing tube. The extension sheath is preferably coupled to the housing tube at both ends. Figure 22 also shows the free motion configuration at 1330. Figure 22 also shows the high friction motion configuration at 1332.

[0108] Three additional embodiments of washer concepts that provide high friction resistance to core strap movement are shown in FIG. 23. As shown in each of concepts 1340, 1350, and 1360, the washer shape may vary from a flat washer 1342 to an angled washer 1352 or an angled washer 1362, depending on the configuration of the housing. In each case, alignment of the washer 1342, 1352, or 1362 along the housing's free-motion surface 1344, 1354, or 1364 allows the core strap 1348, 1358, or 1368 to move substantially freely within the washer and housing. However, when the washer 1342, 1352, or 1362 rotates within the housing and aligns with the housing's locking surface 1346, 1356, or 1366, the core strap flexes, creating an angled, high-friction path of movement that limits further extension of the headgear.

[0109] A further embodiment of the washer concept mechanism is shown in FIG. 24. In this embodiment, mechanism 1370 includes a washer 1372 disposed within a housing 1374. A rotatable member 1376 is also disposed within housing 1374. As discussed above with respect to the other washer embodiments, movement of washer 1372 from one end of the housing to the other affects whether a free-motion or high-friction motion condition exists. The rotatable member 1376 within washer mechanism 1370 provides the added benefit of being less sensitive to changes in the angle at which mechanism 1370 pulls core strap 1378.

[0110] In any of the above embodiments, the housing may be made of one or more pieces. The housing and washer may be made of the same or different materials. In some configurations, the housing and / or washer may be made of a generally rigid material. In some configurations, the housing and / or washer may be made of a rigid plastic. In some configurations, the housing and / or washer may be made of a polycarbonate, polypropylene, acetyl, or nylon material. In some configurations, the housing and / or washer may be made of a metal.

[0111] When headgear having any of the washer mechanisms described above with reference to Figures 21A-B, 22, 23, and 24 is extended, a small amount of friction between the washer and core strap pulls the washer toward the angled end wall of the housing. This positions the washer at an angle within the housing, creating a curved path for the core strap to pass through. This curved path creates a tension force within the core strap, increasing resistance to movement between the core strap and the washer mechanism. The resistance is such that a force greater than the specified yield force is required to extend the headgear.

[0112] When there is no tension on the headgear containing the washer mechanism, the washer returns to its neutral position adjacent the vertical end wall. In this position, the washer exerts minimal friction on the core strap. When the headgear is released, the core strap is free to retract within the housing and washer. The elastic sheath provides the retraction force necessary to shorten the headgear.

[0113] The elastic sheath also allows the headgear to stretch when a force greater than the specified yield force is applied. The Young's modulus of the elastic sheath is preferably adjusted so that the sheath can only apply forces to the user's head that are less than the minimum expected blow-out force. Thus, in these configurations, the elastic provides an initial counterbalance force for low CPAP pressures.

[0114] Initially, the CPAP pressure is counterbalanced by a low level of force applied to the user's head by the elastic element. As the force applied by the CPAP pressure increases, the non-stretching core strap, along with the washer mechanism, limits further stretching. The headgear's natural response to increasing CPAP pressure is to stretch to accommodate the increased pressure, which pushes the washer toward the angled end of the housing, locking the non-stretching core strap in place due to increased friction. Once core strap movement is restricted, the core strap provides the remaining counterbalancing force. Because the force applied by the CPAP pressure generally does not exceed the specified yield force to overcome the washer's resistance against the core strap, the length of the headgear remains substantially constant unless changed by the user.

[0115] Another embodiment of a large hysteresis mechanism is shown in FIGS. 25A-C. A cross section of a C-ring mechanism 1400 is shown in FIG. 25A. The mechanism 1400 includes a rigid tubular housing 1404, which may be formed continuously with the strap member 1410 or may be a separate piece. The housing 1404 includes an orifice through which the inextensible section of the core strap 1408 may pass. The housing 1404 also includes the free end of the core strap (not shown). Within the housing is a resilient washer having a C-shaped cross section 1406. The washer 1406 is oriented so that the opening of the washer 1406 faces toward the mask. The flexible C-shaped washer 1406 may be made of silicone or rubber. Referring to FIG. 25A, the opening defined in the C-shaped member 1406 is oriented in a direction substantially similar to the longitudinal axis of the core strap 1408. At least one leg of each C-shaped member 1406 is adjacent to the core strap 1408. The C-shaped section of the washer 1406 drags on the surface of the inextensible section of the core strap 1408 that passes through the housing 1404. As explained in more detail below, the housing 1404 and washer 1406 are configured so that the washer 1406 provides significant friction when the core strap 1408 moves in one direction, while allowing the core strap 1408 to move substantially freely in the other direction.

[0116] Referring now to FIGS. 25B and 25C, free and high-friction movement of the core strap 1408 is shown. Depending on the direction of movement, the washer 1406 responds differently. When the core strap 1408 moves in the free-motion direction 1414, the center of the washer 1406 tends to "unroll," as shown in FIG. 25B. As the center of the washer 1406 unrolls, friction on the core strap 1408 decreases. When the core strap 1408 moves in the other direction, the high-friction movement direction 1416, the center of the washer 1406 in contact with the core strap 1408 contracts or compresses, as shown in FIG. 25C. This deformation increases friction on the core strap 1408 and increases the force required to extend the headgear. FIGS. 26A and 26B show two views of one embodiment of a headgear assembly having a C-ring mechanism as described above. The midsection of the core strap 1408 is housed within an extension sheath. The extension sheath can be coupled to the housing 1404 at both ends. The extension sheath provides a retraction force to return the headgear to the size of the user's head. The Young's modulus of the extension sheath can be adjusted so that the sheath can apply a force to the user's head that is less than the minimum expected blow-out force. This means that the extension sheath provides an initial counterbalancing force. In a cannula system, to maximize comfort, the Young's modulus can be adjusted to be the lowest possible or practicable required to hold the cannula on the user's head. At high blow-out forces (or external forces of the cannula system), the non-extending component provides an additional counterbalancing force. The core straps 1408 preferably have stops at their ends to reduce or eliminate the possibility of the ends being pulled out of the housing 1404. By receiving the ends of the core straps 1408, the headgear forms a closed loop. The housing 1404 is preferably fastened to the mask frame to couple the headgear to the mask.

[0117] In the embodiment shown in FIGS. 25A-C, when an extension force is applied to the headgear, the core strap 1408 pulls the rounded section of the washer 1406 against the inner wall of the housing 1404. This crushes the washer 1406, increasing the friction on the core strap 1408. The friction provided by the washer 1406 is such that the force required to extend the headgear is greater than the specified yield force. When the headgear is released from the extended position, the washer 1406 returns to its natural shape, allowing the core strap 1408 to pass through the housing 1404 and washer 1406 with significantly less resistance. When the open side of the washer 1406 is pulled against the wall of the housing 1404, the washer 1406 does not crush or deform, and the friction on the core strap 1408 remains low.

[0118] Initially, the CPAP pressure is counterbalanced by a low level of force applied to the user's head by the elastic or extensible component. As the force applied by the CPAP pressure increases, the inextensible core strap 1408 acts to limit further stretching. The headgear's natural response is to stretch to accommodate the increased CPAP pressure, which forces the rounded sides of the washer 1406 against the wall of the housing 1404, increasing friction and "locking" the inextensible core strap 1408 in place. Once the movement of the core strap 1408 is restricted, a remaining counterbalancing force is provided. Because the force applied by the CPAP pressure generally does not exceed the specified yield force to overcome the friction of the washer 1406 on the core strap 1408, the length of the headgear remains substantially constant unless altered by the user.

[0119] Another embodiment of a high hysteresis mechanism is shown in Figures 27A-C. In Figure 27A, an alternative washer mechanism 1500 includes a housing 1504 incorporating a crushable core member 1506. The crushable core member 1506 may be configured with a conical shape such that the cone can be crushed or deformed to increase friction on the core strap 1508. When the core strap 1508 moves in the free motion direction indicated by arrow 1510, friction on the core strap 1508 is minimized, and the crushable core member 1506 does not substantially resist the free motion of the core strap 1508, as shown in Figure 27B. When the core strap 1508 moves in the high friction motion direction indicated by arrow 1512, the crushable core member 1506 is deformed or "snugs up" to the left, as shown in Figure 27C.

[0120] 27A, graph 1520 shows that resistance to movement of core strap 1508 increases rapidly as resistance increases due to deformation of crushable core member 1506. As core strap 1508 is further stretched, resistance to movement remains high, which is consistent with a large hysteresis force profile such as that described with reference to FIG.

[0121] Yet another embodiment of the large hysteresis mechanism is shown in Figures 28A and 28B. In Figure 28A, a roller ball locking mechanism 1600 includes a rigid tubular housing 1604 having an internal chamber 1608. The internal chamber 1608 is tapered so that one end is larger than the other. The internal tapered chamber 1608 houses a roller ball 1606. The roller ball 1606 is housed between the wall of the internal tapered chamber 1608 and a non-stretching core strap 1610. The housing 1604 further includes an orifice to allow the core strap 1610 to pass through the housing and also houses the free end of the core strap 1610 to form a closed loop. The core strap 1610 preferably has a stop at its end to prevent the end from being pulled out of the housing 1604. The housing 1604 can then be fastened to a mask frame. In this configuration, when the roller ball 1606 is at one end of the internal cavity 1608, it presses against the core strap 1610, increasing friction and the load force required to further stretch the core strap 1610. Continuing to refer to FIG. 28A , when the core strap 1608 is pulled in the direction indicated by arrow 1612, the roller ball 1606 is forced toward the smaller end of the internal cavity 1608. Due to the angled shape of the internal cavity 1608, when the core strap 1608 moves in the opposite direction, the roller ball 1606 is forced toward the “high ceiling” end of the internal cavity 1608, where there is more space for the roller ball 1606. Thus, the roller ball 1606 has minimal interference with the core strap 1608, thereby reducing friction exerted by the ball. An example of this roller ball locking mechanism incorporated into a headgear assembly is shown in FIG. 28B. The midsection of the core strap 1610 is housed within an extension sheath 1612. The extension sheath 1612 may be coupled at both ends to the housing 1604. The extension sheath 1612 provides a retraction force to return the headgear to the size of the user's head. The Young's modulus of the extension sheath 1612 is preferably adjusted so that the sheath 1612 can apply only a force to the user's head that is less than or equal to the minimum expected blowout force.This means that the extension sheath 1612 provides an initial counterbalancing force. In a cannula system, to maximize comfort, the Young's modulus can be tuned to be the lowest possible or practicable required to hold the cannula on the user's head. At higher insufflation forces, the non-extending component provides an additional counterbalancing force.

[0122] When an extension force is applied to headgear having the roller ball mechanism described above with reference to Figures 28A-C, the core strap 1610 pulls the roller ball 1606 toward the narrow end of the tilt chamber of the housing 1604. This then drives the roller ball 1606 toward the core strap 1610, increasing the friction on the core strap 1610. The increased friction is such that the force required to extend the headgear is greater than the specified yield force.

[0123] When the headgear is released from the extended position, the roller balls 1606 are forced towards the wider end of the tilted chamber of the housing 1604, thus reducing friction on the core strap 1610 and allowing the core strap 1610 to pass through the chamber with significantly less resistance.

[0124] Initially, the CPAP pressure is counterbalanced by a low level of force applied to the user's head by the expandable sheath component 1612. As the force applied by the CPAP pressure increases, the non-expandable core strap 1610 acts to resist further stretching. The headgear naturally attempts to stretch to accommodate the CPAP pressure, which pushes the roller ball 1606 toward the narrow end of the tilted chamber 1608, "locking" the core strap 1610 in place. Resisting movement of the core strap 1610 provides the remaining counterbalancing force. Because the force applied by the CPAP pressure generally does not exceed the specified yield force to overcome the friction of the roller ball 1606 on the core strap 1610, the length of the headgear remains substantially constant unless altered by the user.

[0125] A second roller ball locking mechanism 1620 with a high hysteresis force profile is shown in FIG. 28C . In this figure, the mechanism 1620 includes a housing 1624 with an internal chamber 1628 containing a separate wedge or switch member 1632. The wedge member 1632 functions as a hinged release switch housed between the roller ball 1626 and the chamber 1628. In this embodiment, the wedge member 1632 is included to enhance quick release of the roller ball 1626 from the core strap 1630. The wedge member 1632 has angled surfaces that form a slanted chamber when engaged and a rectangular chamber when released. The midsection of the core strap 1630 is housed within an extension sheath similar to the sheath 1612 shown in FIG. 28B . The extension sheath can be coupled at both ends to the housing 1624. The extension sheath provides a retraction force to return the headgear to the size of the user's head. The Young's modulus of the extensible sheath is preferably adjusted so that the sheath can only apply a force to the user's head that is less than or equal to the minimum expected insufflation force. This means that the extensible sheath provides an initial counterbalancing force. To maximize comfort in the cannula system, the Young's modulus may be adjusted to be the lowest possible or practicable required to hold the cannula on the user's head. At higher insufflation forces, the non-extensible components provide additional counterbalancing forces.

[0126] Upon reversal of direction to the free movement direction as indicated by arrow 1634, wedge 1632 and roller ball 1626 move together a small distance before wedge 1632 disengages within cavity 1628, instantly releasing the grip between core strap 1630 and roller ball 1626. Core strap 1630 is then free to move.

[0127] The switch 1632 is naturally in the engaged position, forming a tilted chamber. When a stretching force is applied to the headgear, the core strap 1630 pulls the roller ball 1626 toward the end of the chamber 1628 narrowed by the switch 1632. As the ball 1626 is forced toward the switch 1632, the compressive force increases until the roller ball 1626 is directly over the axis of rotation of the switch 1632, at which point the switch 1632 is released. Releasing the switch 1632 creates a rectangular chamber 1628, reducing the resistance between the switch 1632, ball 1626, and core strap 1630, allowing the ball 1626 to move within the chamber 1628 and allowing the headgear to easily stretch with only the force required to overcome the elastic extension sheath and some friction between the components of the mechanism.

[0128] When switch 1632 is released and ball 1626 rolls to the extended end of chamber 1628, core strap 1630 can move in both directions within mechanism 1620 with minimal resistance. A reset of switch 1632 occurs after core strap 1630 reverses its direction of movement, returning ball 1626 to the other (retracted) end of chamber 1628. When ball 1626 rolls back over the axis of rotation of switch 1632, switch 1632 is reset and chamber 1628 tilts again.

[0129] When the headgear is released from the extended position and allowed to retract, the roller ball 1626 is forced back toward the extended or more open side of the chamber 1628. The change in position of the roller ball 1626 re-engages the switch 1632, but also maintains a low level of resistance between the components, allowing the core strap 1630 to pass through the chamber 1628 with less resistance.

[0130] Initially, the CPAP pressure is counterbalanced by a low level of force applied to the user's head by the elastic sheath component. As the force applied by the CPAP pressure increases, the non-stretching core strap 1630 provides additional resistance to stretching. The natural response of the headgear is to stretch to accommodate the CPAP pressure, which pushes the roller ball 1626 toward the angled surface of the switch 1632, thereby increasing friction between the ball 1626, core strap 1630, and switch 1632. The force applied by the air pressure is preferably not sufficient to overcome the friction and cause the switch 1632 to release, thus limiting further stretching of the headgear. The switch force is preferably approximately equal to the specified yield force.

[0131] FIG. 29 shows an alternative embodiment of a roller ball mechanism for large hysteresis. The collet mechanism 1700 includes a two-piece housing 1704, 1706 with a conical end. The housing members 1704, 1706 are the ends of a rigid tubular housing that accommodate the free end of a non-stretching core strap 1710. The housing contains a collet member 1708 that forms a collar around the core strap 1710. The collet member 1708 preferably has a frusto-conical shape, as in the illustrated embodiment, and may have one or more kerfs along its length to allow expansion and contraction of the collet member 1708. When the collet member 1708 is retracted in the direction indicated by arrow 1712, i.e., into the conical chamber formed in the housing, the collet member 1708 exerts a strong clamping force on the non-stretching core strap 1710. Similar to the roller ball mechanism described above, when the collet member 1708 is pulled into the conical chamber of the housing, the core strap 1710 is subjected to a high frictional force. When pulled in the opposite direction, the core strap 1710 is substantially free to move.

[0132] As described above with reference to other embodiments, the mid-section of the core strap 1710 is housed within an extension sheath that is coupled to a housing at both ends. The non-extending core strap 1710 preferably has stops at its ends to reduce or eliminate the possibility of the free end being pulled out of the housing, forming a closed-loop headgear assembly. The housing tube can be clipped to the mask frame.

[0133] When a stretching force is applied to the headgear, the core strap 1710 pulls the collet member 1708 into the conical end of the housing. This compresses the collet member 1708 onto the core strap 1710, increasing friction between the two components. The friction provided by the compressed collet member 1708 is such that the force required to stretch the headgear is greater than the specific applied force.

[0134] When the headgear is released from the extended position, the collet member 1708 returns to its neutral position, allowing the core strap 1710 to pass more freely through the collet member 1708. The elastic sheath provides a retraction force to return the headgear to the size of the user's head. The Young's modulus of the elastic sheath may be adjusted so that the sheath can only apply forces to the user's head that are less than the minimum expected blow-out force. In this configuration, the elastic provides an initial counterbalancing force. At higher blow-out forces, the non-extending component provides an additional counterbalancing force.

[0135] Initially, the CPAP pressure is counterbalanced by a low level of force applied to the user's head by the elastic element. As the force applied by the CPAP pressure increases, the inextensible core strap 1710 limits further stretching. The headgear's natural response is to stretch to accommodate the CPAP pressure, which forces the collet member 1708 toward the conical end of the housing, thereby locking the inextensible core strap 1710 in place. The restraint on movement of the core strap 1710 provides a remaining counterbalancing force. Because the force applied by the CPAP pressure preferably does not exceed a specified yield force to overcome the friction of the collet member 1708 on the core strap 1710, the length of the headgear remains constant unless changed by the user.

[0136] For headgear that provides a high hysteresis force extension profile in conjunction with a mask, the force required to extend the headgear for donning is preferably not too high compared to the specified yield force to allow the user to easily recognize the adjustability. Very high extension forces can be disorienting to the user because the required high force may feel unnatural to the user and may pose a risk of fracture of headgear components.

[0137] The headgear also preferably allows for adjustable fit to suit the user's preferences. Figure 30 shows the force profile of a large hysteresis mechanism headgear that includes a section that allows the user to select how they want the mask seal to fit. This force profile also accounts for different facial shapes among users. Further retraction of the straps allows the user to press the mask against their face to create a larger contact area and a tighter fit with the seal. This increases the force applied by the headgear, but not more than is required to overcome the friction mechanism and stretch the headgear as described above. For users who prefer a looser fit, non-stretching or low-stretching components of the headgear allow the mask to be held in place, requiring minimal force to offset blowout forces while still maintaining a seal with the user's face, or to offset the weight of the cannula and hold it in place.

[0138] The force profiles at various pressures are shown in Figures 31A and 31B. Figure 31B shows the force profile for the Pilairo elastic strap headgear. It is clear that the force is fairly constant and largely unaffected by the CPAP pressure. This figure also shows the wide variance between subjects due to the different head sizes of each test user.

[0139] In contrast, the graph shown in FIG. 31A is obtained using a one-way-friction head strap. In this example, headgear using the tunnel concept is used, but similar results can be obtained with the inventor's other concepts, as described above. This figure demonstrates the advantage of a balanced fit. At low pressures, this headgear generates significantly less force on the user's head compared to the Pilairo elastic strap headgear. FIG. 31A also shows a smaller variance in measurements across different users. The variance is due to the way the seal is formed, as some people require or prefer a stronger engagement than others.

[0140] Figure 31C shows the difference between the respective means of the first two graphs shown in Figures 31A and 31B. In this graph, a large force difference at the low end of the CPAP pressure scale is evident. Headgear incorporating one of the mechanisms described above can improve user comfort. This is especially true when combined with an intelligent supply of CPAP, such as pressure ramping or pressure variation technology.

[0141] Note that Figure 31C shows average values, however, each counterbalanced fit mechanism is designed to optimize performance for each individual user.

[0142] FIG. 32 illustrates an adjustment mechanism 1800 with variable directional characteristics for use in a self-fitting interface assembly. The illustrated adjustment mechanism 1800 provides a directional locking function and may therefore be referred to as a directional locking mechanism or simply a directional lock. The directional lock 1800 allows relative movement between two components in a first direction with a first level of resistance and provides a second, preferably higher, level of resistance in response to relative movement (or attempted relative movement) in a second direction, thereby preventing or impeding relative movement in the second direction in response to at least some loading conditions. In some configurations, the directional lock 1800 prevents relative movement in the second direction in response to normal operating forces, such as one or more of CPAP-generating blowout forces and external forces (e.g., hose pull). The directional lock 1800 can also prevent relative movement in the second direction in response to additional forces beyond the hose pull to provide expected or normal blowout forces and / or reserve forces, as described above. Thus, the directional lock 1800 can be configured to provide a locking function only in response to a normal operating force (and a reserve force, if desired), and can allow relative movement between two components in response to a force greater than the normal operating force (and a reserve force, if desired), for example, allowing extension of the headgear portion of the interface assembly during the attachment phase of the donning process. Thus, a headgear mechanism incorporating such a directional lock 1800 can “convert” from an extensional behavior to a non-extensional behavior, or from an elastically extensional behavior to a non-extensional behavior. As used herein, extension is not necessarily limited to meaning movement in an extensional direction, but can generally mean an extensional or elastic behavior as opposed to a non-extensional or non-elastic / inelastic behavior. The directional lock 1800 (and other directional locks described herein) can also be referred to as a deformation lock that provides a deformation locking behavior.

[0143] The directional lock 1800 of FIG. 32 is generally similar in principle of operation to the arrangements of FIGS. 16 and 21 in that a floating or movable locking component or member 1802 (e.g., a lock washer or lock plate) is movable between a first, low-resistance or released position and a second, high-resistance or locked position. Features or details not described with respect to the directional lock 1800 of FIG. 32 may be the same or similar to corresponding features of the arrangements of FIGS. 16 and 21 or may be of another suitable configuration. The illustrated directional lock 1800 includes a core member 1804, such as a core strap or core wire / cord, that passes through an opening in the lock washer 1802. The lock washer 1802 is supported within an enclosure or housing 1806 for movement between a first position and a second position. Preferably, the housing 1806 includes a first wall 1810 having a first stop surface 1812 that supports the lock washer 1802 in a first position. The first position is preferably the low-resistance or released position. The housing 1806 preferably also includes a second wall 1814 having a second stop surface 1816 that supports the lock washer 1802 in a second position. The second position is preferably a high-resistance or locked position. Preferably, the stop surfaces 1812, 1816 are sized, shaped, or positioned to support the lock washer 1802 in a desired position. Thus, the stop surfaces 1812, 1816 may be continuous surfaces that contact all or substantially all of the mating surfaces of the lock washer 1802, as shown. Alternatively, the stop surfaces 1812, 1816 may be intermittent or discontinuous surfaces or may contact one or more portions of the lock washer 1802, such as, for example, the upper and lower end portions of the lock washer 1802.

[0144] Preferably, the lock washer 1802 is positioned generally perpendicular to the longitudinal axis of the portion of the core member 1804 that is positioned in the first, low resistance or released position within the lock cavity of the housing 1806 such that the opening or hole in the washer 1802 is positioned generally parallel or aligned with the core member 1804. Preferably, the lock washer 1802 is positioned at an angle to the longitudinal axis of the portion of the core member 1804 that is positioned in the second, high resistance or locked position within the lock cavity of the housing 1806 such that the opening or hole in the washer 1802 is positioned at an angle to the core member 1804. Thus, in some configurations, the first stop surface 1812 can be generally perpendicular to the portion of the core member 1804 disposed within the locking cavity of the housing 1806 (and / or the opening in the housing 1806 through which the core member 1804 passes), and the second stop surface 1816 can be disposed at an oblique angle Θ relative to the portion of the core member 1804 disposed within the locking cavity of the housing 1806 (and / or the opening in the housing 1806 through which the core member 1804 passes). As described below, the angle of the second stop surface 1816 or the lock washer 1802 when in contact with the second stop surface 1816 can be selected to obtain a desired amount of locking or yield force or resistance when the lock washer 1802 is in the locked position.

[0145] The housing 1806 can be coupled to one component of the interface assembly, and the core member 1804 can be coupled to another component of the interface assembly, such that relative movement between the housing 1806 and the core member 1804 occurs when the headgear portion of the interface assembly is extended or retracted during the donning process. Frictional engagement between the core member 1804 and the lock washer 1802 causes the lock washer 1802 to move between a first position and a second position depending on the direction of relative movement between the core member 1804 and the housing 1806, or to hold the lock washer 1802 in one of the first and second positions depending on the direction of force applied to the core member 1804 and / or the housing 1806. Thus, similar to other embodiments described herein, with such an arrangement, the directional lock 1800 can be used to provide variable directional resistance characteristics of the self-fitting interface assembly.

[0146] FIG. 33 illustrates a directional lock 1820 that is similar to directional lock 1800. Accordingly, the same reference numbers or letters are used to indicate the same or corresponding components or features. Directional lock 1820 incorporates a release mechanism 1822 that releases or reduces resistance to movement of core member 1804 when a certain force is applied to core member 1804 to limit the locking force of directional lock 1820. That is, release mechanism 1822 allows lock washer 1802 to move from a locked position to a secondary locked position closer to perpendicular to core member 1804 or closer to the released position in response to a force applied in a direction that tends to move lock washer 1802 toward the locked position. Thus, release mechanism 1822 somewhat influences the locking force or yield strength of the locking function of directional lock 1802.

[0147] In the arrangement shown, the release mechanism 1822 includes a biasing member or mechanism, such as a spring 1824. The spring 1824 supports the lock washer 1802 (together with a portion of the second surface 1816 of the housing 1806) in the locked position and prevents or impedes relative movement between the core member 1804 and the housing 1806 in response to an expected or normal operating force. Preferably, the spring characteristics (e.g., spring constant, preload, etc.) are selected such that the lock washer 1802 can move toward or into the secondary locked position against the biasing force of the spring 1824 in response to a desired force magnitude. The force magnitude can be greater than the expected or normal operating force (including one or more of the blow-off force, the hose tension force, and the reserve force). In the arrangement shown, the lock washer 1802 abuts a second surface 1816 of the housing 1806 substantially opposite the spring 1824 in the locked position and pivots about its pivot surface or pivot point 1826 when moving toward the secondary lock position. The distance between the pivot point 1826 and the position of the spring 1824 (or the effective position of any other biasing mechanism) may be referred to as the lever length of the lock washer 1802 and may dictate the load required to move the lock washer 1802 from the locked position toward the secondary lock position. A portion 1828 of the second surface 1816 may define a stop that limits movement of the lock washer 1802 toward the secondary lock position (and in some configurations may define the secondary lock position). In the arrangement shown, the stop portion 1828 is located substantially opposite the pivot point 1826 and / or near the spring 1824.

[0148] There are several properties, characteristics, or dimensions (e.g., materials or geometric shapes / proportions) that affect the actuation length, locking strength, and durability of the directional locking mechanism 1800. Some of these may include relative component separation distances (e.g., from the lock washer 1802 to the core member 1804 or from the core member 1804 to the housing 1806, etc.), the contact area between the lock washer 1802 and the core member 1804, the angle of the locking wall 1814 or locking surface 1816, or the force and lever length associated with the release mechanism 1822. In some configurations, friction promoters are used to facilitate initial engagement of the lock washer 1802 and the core member 1804. Friction promoters may be used to improve initial locking actuation. The friction promoters may be obtained using any suitable technique, including, but not limited to, the use of soft materials to provide increased friction between the lock washer 1802 and the core member 1804, the use of slightly angled release surfaces 1812 on the release walls 1810 of the lock chamber in the housing 1806, or the use of close tolerances between the holes in the lock washer 1802 and the core member 1804. In some configurations, the core member 1804 may have a diameter or cross-sectional dimension of about 0.1 mm to about 8 mm, or any value or subrange within that range. In some configurations, the core member 1804 may have a diameter or cross-sectional dimension greater than 8 mm.

[0149] FIG. 34 illustrates the relationship between slip force and lock angle for directional locks (e.g., directional locks 1800 and 1820) that use angled locking members (e.g., locking plates or lock washers 1802). As shown, other factors being equal, the slip force required to achieve relative motion between the core member 1804 and the housing 1806 increases as the angle Θ of the locking washer 1802 in the locked position increases. In at least some configurations, this relationship is approximately linear. By way of example, the graph in FIG. 34 illustrates the change in slip force for lock angles from 10 degrees to 25 degrees. The slip force varies from approximately 2-2.5 Newtons at 10 degrees to approximately 9 Newtons at 25 degrees, with an approximately linear relationship between these endpoints. The relationship between lock angle and slip force is one factor that can be used to achieve desired locking and / or slip characteristics of a directional lock. The locking angles illustrated in FIG. 34 are merely exemplary. In some configurations, the locking angle can vary from just over zero degrees to about 45 degrees or more. In some configurations, the locking angle is about 10 degrees to about 25 degrees, as shown in the graph of FIG. 34, or any particular value or subrange therein. The slip force or maximum locking force of the directional lock 1800 or any other similar mechanism described herein can be sufficient to prevent undesired slipping of the lock (e.g., due to blow-out force or normal or unexpected forces), but not so great that desired slipping of the lock (e.g., to allow attachment of an interface assembly) is prevented. As described herein, the slip force can be selected to exceed a particular operating envelope of the headgear attachment, which may be related to the type of interface and / or type of therapy used, among other factors. In some configurations, the slip force exceeds the operating envelope by a reserve amount. In some configurations, the slip force can be about 65 Newtons or less, about 45 Newtons or less, about 25 Newtons or less, about 9 or 10 Newtons or less, or any particular value or subrange within these ranges.In some configurations, the slip force can be at least about 0.5 Newtons. In some configurations, the slip force can be at least about 0.5 Newtons and up to about 9, 10, 25, 45, or 65 Newtons, or any specific value or subrange within these ranges. In some configurations, the slip force can be from about 0.5 Newtons to about 65 Newtons, from about 1 Newton to about 45 Newtons, from about 2 Newtons to about 25 Newtons, or from about 2.5 Newtons to about 9 or 10 Newtons, or any specific value or subrange within these ranges.

[0150] FIG. 35 illustrates variations in slip force resulting from variations in the biasing mechanism 1824. Other characteristics being equal, the slip force can be varied by varying the characteristics of the biasing mechanism 1824 to increase or decrease the resistance of the lock washer 1802 to movement from the locked position toward the secondary locked position. For example, if the biasing mechanism includes a spring 1824, the spring constant and / or preload can be selected to vary the slip force of the directional locks 1800, 1820. FIG. 35 illustrates four different variations in the biasing mechanism 1824 that result in four different slip forces (e.g., approximately 2 Newtons, approximately 4 Newtons, approximately 8 Newtons, and approximately 10-11 Newtons). These slip forces are merely exemplary and can be adjusted to any suitable level. While FIG. 33 illustrates a compression coil spring, other suitable types of springs or spring-like elements (among other biasing mechanisms) may also be used. Additionally, biasing mechanism 1824 may be adjustable after manufacture (e.g., by a caregiver or user) to allow for post-manufacturing adjustment of the slip force, such as to accommodate user preference. For example, an adjustment mechanism may be provided to adjust the preload on spring 1828.

[0151] 36 and 37 illustrate a self-fitting interface assembly 1850 that exhibits resistance on demand. The illustrated interface assembly 1850 provides directional locking functionality using mechanical adhesion between a first portion of the assembly and a second portion of the assembly. Preferably, the interface assembly 1850 is constructed in a manner similar to interfaces described herein, such as those of FIGS. 7 and 8, in that the two portions of the interface assembly 1850 interact to provide a first force in response to extension of the interface assembly 1850 and a second, preferably lower, retraction force. However, the interface assembly 1850 of FIGS. 36 and 37 preferably provides such directional locking using microstructures that provide mechanical adhesion, mechanical interlocking, Van der Waals forces, or other intermolecular forces in one or both portions.

[0152] Referring to FIG. 36 , the interface assembly 1850 preferably includes an interface or mask portion 1852 and a headgear portion 1854. The mask portion 1852 preferably contacts the user's face and forms at least a substantial seal therewith. The headgear portion 1854 extends around the user's head and supports the mask portion 1852 on the user's face. Referring to FIG. 37 , a portion of the interface assembly 1850 is shown having a first portion 1856 and a second portion 1858 that are movable relative to one another to vary the length of the headgear portion 1854. The portions 1856 and 1858 may each be defined by one or more of the mask portion 1852 or the headgear portion 1854, or any other component of the interface assembly 1850. In some configurations, the portions 1856 and 1858 are both defined by a portion of the headgear portion 1854.

[0153] Preferably, one or both of portions 1856 and 1858 include microstructures 1860 that allow portions 1856, 1858 to selectively engage with one another to provide a directional locking force (FIGS. 38 and 39). Preferably, the locking force is a function of one or more of expected or normal operating forces F, such as blow-off force, hose pull force, other external forces, and reserve forces. N , sufficient to prevent or impede relative movement of portions 1856, 1858 or maintain the current length of headgear portion 1854. The locking force is a force F applied in a direction generally perpendicular to the direction of relative movement between portions 1856 and 1858, or in a direction generally radial to the direction of relative movement between portions 1856, 1858 when interface assembly 1850 is assumed to be or is generally circular (such as when worn by a user). P Thus, the locking force can be increased when the user's head applies an outward force against the inner one of the portions 1856, 1858.

[0154] As described above with the other interface assemblies, the interface assembly 1850 may exhibit a first level of resistance to extension in the absence of a normal or radial force on the portions 1856, 1858, and may exhibit a second, preferably higher, level of resistance to extension in the presence of a normal or radial force on the portions 1856, 1858. Thus, the headgear portion 1854 may be extended at the first level of resistance and then fitted to a user's head. Once fitted, the headgear portion 1854 may provide a second, higher level of resistance to extension. This resistance functions to resist blowing or other forces tending to extend the headgear portion 1854. Preferably, the force tending to resist retraction of the headgear portion 1854 (and therefore the force applied to the user's head) is at least less than the second level of resistance, and may be less than the first level of resistance to extension to improve user comfort.

[0155] The microstructures 1860 can be in any suitable arrangement to provide a desired level of resistance to relative movement of the portions 1856, 1858 in either or both extension and retraction. Preferably, in some configurations, the microstructures 1860 are directional or provide different levels or resistance depending on the direction of relative movement. As shown in FIG. 38 , one suitable microstructure arrangement 1860 can include a plurality of fibers, such as microfibers or nanofibers, which can be made using an electrospinning method and any suitable material such polymeric material. Other suitable methods and / or materials may also be used. The fibers can be oriented in a suitable manner to provide directional properties, if desired.

[0156] As shown in FIG. 39 , another suitable microstructure can include a plurality of geometric shapes, such as a plurality of ridges, teeth, or scale-like projections 1862. Each projection 1862 can have a base 1864 and an edge 1866 generally opposite the base 1864. Such projections 1862 can be used on each portion 1856, 1858. Alternatively, one portion 1856, 1858 can use a projection 1862, while the other portion 1856, 1858 can use another type of complementary structure suitable for engaging the projection 1862. Preferably, the projections 1862 are oriented with respect to the portions 1856, 1858 to provide a directional lock or resistance to relative movement. For example, the projections 1862 can be oriented at an oblique angle relative to the surface on which the projections 1862 support and / or relative to the direction of movement. Thus, in response to movement in one direction, the protrusions 1862 can slide over one another with a low level of resistance, and in response to movement in the other direction, the protrusions 1862 can engage one another to block or impede relative motion and provide a locking function. The protrusions 1862 can be arranged in any suitable manner (e.g., in one or more rows). The protrusions 1862 can be made from any suitable material (e.g., a polymer) and by any suitable process (e.g., micromachining or micromolding techniques).

[0157] 40-42 illustrate another adjustment mechanism 1900 having variable directional characteristics that can be used in a self-fit interface assembly. Because the illustrated adjustment mechanism 1900 provides a directional locking function, it can be referred to as a directional locking mechanism, or simply a directional lock. The directional lock 1900 of FIGS. 40-42 generally operates similarly to the mechanisms of FIGS. 16, 21, 32, and 33 in that a locking component or member 1902 (e.g., a locking plate) is movable between a first, low-resistance or released position and a second, high-resistance or locked position. Features or details not described with respect to the directional lock 1900 of FIGS. 40-42 may be the same as or similar to corresponding features of the mechanisms of FIGS. 16, 21, 32, and 33, or may be of another suitable configuration.

[0158] The directional lock 1900 preferably includes a core member in the form of a flat strap 1904 that functions similarly to the core member of the mechanism described above. The directional lock 1900 also preferably includes an enclosure or housing 1906, which may be similar in structure and function to the housing of the mechanism described above. Accordingly, the locking plate 1902 is supported within the housing 1906 for movement between a first position and a second position. The housing 1906 preferably includes a first wall 1910 having a first stop surface 1912 that supports the locking plate 1902 in the first position. The first position is preferably a low resistance or released position. The housing 1906 also preferably includes a second wall 1914 having a second stop surface 1916 that supports the locking plate 1902 in the second position. The second position is preferably a high resistance or locked position.

[0159] Preferably, the locking plate 1902 is positioned within the locking cavity of the housing 1906 generally perpendicular to the longitudinal axis of the strap 1904 that is positioned in the first, low resistance or released position, such that the opening or hole in the locking plate 1902 is positioned generally parallel or aligned with the strap 1904. Preferably, the locking plate 1902 is positioned within the locking cavity of the housing 1906 at an angle to the longitudinal axis of the portion of the strap 1904 that is positioned in the second, high resistance or locked position, such that the opening or hole in the locking plate 1902 is positioned at an angle to the strap 1904. Thus, in some configurations, the first stop surface 1912 can be generally perpendicular to the strap 1904 disposed within the locking cavity of the housing 1906 (and / or the opening in the housing 1906 through which the strap 1904 passes), and the second stop surface 1916 can be disposed at an oblique angle Θ relative to the strap 1904 (and / or the opening in the housing 1906 through which the core member 1904 passes). As described below, the angle of the second stop surface 1916 or the locking plate 1902 when in contact with the second stop surface 1916 can be selected to obtain a desired maximum locking force or amount of resistance when the locking washer 1902 is in the locked position. If desired, a release mechanism similar to the release mechanism 1822 of FIG. 33 can be provided.

[0160] Similar to the above mechanisms, the strap 1904 can be coupled to or form a first portion of an associated interface assembly, and the housing 1906 can be coupled to or form a second portion of the interface assembly, such that relative movement between the strap 1904 and the housing 1906 allows adjustment of the length or circumference of the interface assembly. Advantageously, the strap 1904 is anisotropic with respect to one or more properties. For example, the strap 1904 is more flexible when bending or bending in its width direction than when bending in its height direction. Thus, the strap 1904 can bend to conform to the user's head but resist bending in its height direction to provide support to the interface assembly and prevent undesired movement of the mask portions. Additionally, the directional lock 1900 including the strap 1904 is suitable for use in portions of the interface assembly that contact the user's head, such as the side, rear, or top portions of a headgear strap, and potentially provides greater comfort than interfaces having a generally cylindrical core member. However, the orientation lock 1900 may also be used on other parts or locations of the interface assembly, such as on one or both sides of the headgear between rather than in contact with the user's head and mask portions.

[0161] The illustrated direction lock 1900 includes an actuation mechanism 1920 that facilitates movement of the locking plate 1902 to increase the sensitivity of the direction lock 1900. Such an actuation mechanism 1920 can speed movement of the locking plate 1902 to or from a locked or released position, improving the time or distance of relative movement required to transition the direction lock 1900 between its locked and released positions. Additionally or alternatively, the actuation mechanism 1920 can reduce the sensitivity of the direction lock 1900 to changes in component dimensions (e.g., dimensions of interacting portions of the locking plate 1902 or strap 1904) so ​​as to allow for greater component tolerances while maintaining a desirable level of functionality, thereby reducing the cost of the direction lock 1900.

[0162] In some configurations, one of the locking plate 1902 and the strap 1904 may include an engagement feature 1922 that facilitates engagement of the locking plate 1902 and the strap 1904 with the other of the locking plate 1902 and the strap 1904. In the arrangement shown, the strap 1904 includes an engagement feature 1922 that facilitates frictional engagement with the locking plate 1902. The engagement feature 1922 may include a portion of the strap 1904 having particular dimensions, surface characteristics, or material that enhances engagement with the locking plate 1902. For example, with reference to FIG. 42 , the width of the engagement feature 1922 may be greater than the width of the remainder of the strap 1904. Additionally or alternatively, the engagement feature 1922 may include a different material or surface finish with improved frictional properties relative to the remainder of the strap 1904 to enhance frictional engagement between the locking plate 1902 and the strap 1904. In the arrangement shown, the engagement feature 1922 is a silicone material portion secured to the remainder of the strap 1904, which may be made of a suitable plastic material. However, other suitable materials may also be used for the engagement feature 1922 or the remainder of the strap 1904. Separation of the dissimilar materials is prevented by mechanical interference between the interacting lobes of the engagement feature 1922 and the remainder of the strap 1904. Other suitable arrangements, materials, or configurations of the strap 1904 with the engagement feature 1922 may also be used.

[0163] Preferably, the engagement feature 1922 acts on a different surface of the locking plate 1902 than the surface that provides the primary locking function. For example, the engagement feature 1922 has an increased width relative to the remainder of the strap 1904, so that the substantial or primary locking function is provided by the top and bottom (width) surfaces, while the engagement feature 1922 acts substantially or primarily on the side (height) surfaces of the strap 1904. At least partial separation of the locking and engagement functionality allows each to be optimized separately. Thus, the sensitivity of the directional lock 1900 can be varied to obtain a desired level of sensitivity, and the locking force can be varied separately to obtain a desired level of locking without significantly negatively affecting each other.

[0164] Figures 43-45 show an interface assembly 1950 having self-fitting features similar to other interface assemblies described herein. Figures 43-45 show the interface assembly 1950 in various positions during the fitting process. Figure 43 shows the interface assembly 1950 partially fitted to a user. Figure 45 shows the interface assembly 1950 fully fitted to a user, and Figure 44 shows the interface assembly 1950 in a position between those shown in Figures 43 and 45.

[0165] Generally, the interface assembly 1950 includes an interface portion 1952, such as a mask, and a headgear portion 1954. The headgear portion 1954 contacts the user's head and may include a rear portion 1956 that includes one or more straps. In the arrangement shown, the rear portion 1956 includes multiple straps, namely, a strap that passes around the rear of the head and a strap that passes over the crown of the head. However, any suitable number of straps may be provided. The headgear portion 1954 also includes a pair of side straps 1958 that extend between and preferably connect the rear portion 1956 and the mask 1952. In the arrangement shown, each side strap 1958 includes some or all of a directional locking mechanism 1960 that provides or otherwise facilitates a self-fitting feature. The mask 1952 may carry or include some of the directional locking mechanism 1960. In other arrangements, other portions of the interface assembly 1950 (e.g., rear portion 1956 of headgear portion 1954 and / or mask 1952) may include some or all of the directional locking mechanism in addition to or instead of side straps 1958. Each side strap 1958 may be substantially similar or identical in structure and operation.

[0166] As described above with respect to the other interface assemblies, the interface assembly 1950 preferably provides a self-fitting or directional feature in that it allows the interface assembly 1950 to extend for application, retract to adjust to a particular user's head size, and then lock to prevent or impede extension in response to expected or normal forces, such as one or more of CPAP output, hose tension, and reserve force. Preferably, the directional lock 1960 has a lower resistance to forces tending to retract the interface assembly 1950, headgear portion 1954, or side straps 1958, and a higher resistance to forces tending to extend the interface assembly 1950, headgear portion 1954, or side straps 1958, such that the holding force applied by the interface assembly 1950 to the user's head is lower than the locking force that prevents extension of the interface assembly 1950. As described herein with reference to FIGS. 2-5, in some configurations, the interface assembly 1950 has a holding force below the operating envelope and a locking force above the operating envelope.

[0167] 46-48 show a directional locking mechanism 1960 incorporating the side strap 1958 separated from the interface assembly 1950 of FIGS. 43-45. The directional locking mechanism 1960 generally includes a locking portion or lock 1962, a core member 1964, and an elastic strap 1966. The elastic strap 1966 and at least a portion of the core member 1964 form at least a portion of the side strap 1958. The lock 1962 may form part of the side strap 1958 and may preferably be attached to or be part of the mask 1952.

[0168] The core member 1964 may be coupled at one end to an elastic strap 1966. Preferably, the core member 1964 passes through the lock 1962. The free end of the core member 1964 may be disposed within a conduit or tube 1968. The conduit or tube 1968 may be disposed within the mask 1952, supported by the mask 1952, or formed by the mask 1952. The elastic sleeve 1966 preferably provides a force tending to urge the core member 1964 within the lock 1962 in a direction such that a larger portion of the core member 1964 is disposed within the tube 1968. Thus, the elastic sleeve 1966 (or a pair of elastic sleeves 1966 assuming the pair of side straps 1958) preferably provides some or all of the force tending to retract the interface assembly 1950. Preferably, the core member 1964 has sufficient rigidity or column strength to be pushed within the lock 1962 without significant buckling. In some configurations, other retraction mechanisms may be provided in addition to or in place of the elastic straps 1966 to provide a retraction force. For example, a biasing element may be coupled to the free end of the core member 1964 to pull the core member 1964 within the lock 1962. This may provide the entire retraction force (in which case the straps 1966 may be omitted or may be non-elastic) or may work in combination with the elastic straps 1966. In some configurations, a biasing element may couple the free ends of both core members 1964 to apply some or all of the retraction force to both side straps 1958. In yet other configurations, the associated headgear may not provide a retraction force. For example, the headgear may be manually retracted to a desired circumference to fit the user's head.

[0169] Lock 1962 operates according to the general principles described above with reference to other directional locking mechanisms, such as those of Figures 16, 21, 32, 33, and 40-42, and therefore details not described in conjunction with Figures 46-48 may be assumed to be similar or identical to the same or corresponding features of those mechanisms, or may be that of any other suitable mechanism.

[0170] Lock 1962 preferably includes a housing 1970 and a locking member or element 1972. In the mechanism shown, locking element 1972 is formed as a single piece, integral structure with at least a portion of housing 1970 and preferably a portion that defines an opening through which core member 1964 passes within housing 1970. Housing 1970 may have additional portions to, for example, house or protect locking element 1972 or to facilitate attachment to mask 1952 and / or elastic strap 1966.

[0171] The locking element 1972 functions in a manner similar to the locking members (e.g., lock washers and locking plates) described elsewhere herein. That is, preferably, the locking element 1972 defines an opening through which the core member 1964 passes. The locking element 1972 is movable between a released position and a locked position to vary the resistance to movement of the core member 1964 relative to the housing 1970. Preferably, the resistance to movement of the core member 1964 attempting to extend the length of the elastic straps 1966 is greater than the resistance to movement of the core member 1964 attempting to retract the length of the elastic straps 1966. Thus, the retraction force provided by the elastic straps 1966 (or other components of the interface assembly 1950) can be relatively small or of a relatively low magnitude to improve patient comfort, and the locking element 1972 can allow the interface assembly 1950 to resist extension without relying on the force generated by the elastic straps 1966. Thus, the holding force of the elastic strap 1966 can be adjusted for patient comfort without having to counteract blow-out forces or other external forces tending to stretch the interface assembly 1950 .

[0172] Similar to the mechanisms described elsewhere herein, preferably, a surface of the locking element 1972 that defines or surrounds the opening through which the core member 1964 passes engages the core member 1964 in the locked position, providing a level of resistance to movement of the core member 1964 that inhibits or prevents stretching of the elastic strap 1966. However, instead of being controlled by a surface of the housing, the locking element 1972 is coupled to the housing 1970 by a curved portion or living hinge 1974, and movement of the locking element 1972 is controlled by the properties of the living hinge 1974. That is, the locking element 1972 and living hinge 1974 are defined by a curved arm that extends from the housing 1970 and has a free end. The relaxed position of the locking element 1972 can define a released position. The released position can be affected by the presence of the core member 1964 passing through the locking element 1972. That is, the released position may not be the same as the relaxed position of the locking element 1972 in an unassembled state without the core member 1964. Movement or attempted movement of the core member 1964 in a direction that attempts to stretch the length of the elastic strap 1966 (to the left in the orientation shown) will cause the locking element 1972 to reorient toward the locked position, preventing or impeding stretching of the elastic strap 1966. The dimensions, material properties, or other characteristics of the living hinge 1974 affect the locking force of the lock 1962. In some configurations, the locking force is related to the angle of the locking element 1972, as described elsewhere herein (see, e.g., FIG. 34 and related disclosure).

[0173] In some configurations, limited movement of the core member 1964 may occur as the locking element 1972 transitions from the released position to the locked position. Thus, the retraction force provided by the elastic strap 1966 (or other biasing element) preferably provides sufficient force to maintain at least a substantial seal with the mask 1952 or other interface after movement of the core member 1964 due to movement of the locking element 1972 to the locked position. Preferably, the lock 1962 is configured such that the distance the core member 1964 can move is relatively short.

[0174] Figures 46-48 show the directional locking mechanism 1960 in various positions. Figure 46 shows the directional locking mechanism 1960 in a relaxed or resting position, with the elastic strap 1966 retracted and the maximum amount of core member 1964 pressed into tube 1968. The locking element 1972 is in the released position.

[0175] 47 shows the directional locking mechanism 1960 in an extended position, which may occur during the attachment phase of the installation process. The extension of the elastic strap 1966 causes a portion of the core member 1964 to be withdrawn from the tube 1968 such that a minimal amount of the core member 1964 is disposed within the tube 1968, against the resistance provided by the lock 1962 as the locking element 1972 moves to or toward the locked position. Once the extended position is reached and relative motion between the housing 1970 and the core member 1964 terminates, the locking element 1972 may remain in the locked position, return to the released position, or be disposed anywhere between the locked and released positions, depending on various factors, such as the spring force of the living hinge 1974, the relative proportions of the openings in the core member 1964 and the locking element 1972, and the frictional forces between the core member 1964 and the locking element 1972.

[0176] FIG. 48 shows the directional locking mechanism 1960 in an operative position, having a length between a relaxed position and an extended position, such as when worn on a user's head. Compared to the extended position, in the operative position, the retaining force of the elastic strap 1966 forces a greater amount of the core member 1964 into the tube 1968, against the resistance to extension preferably significantly less than that provided by the locking element 1972 in the released position. As described above, the locking element 1972 can be in the locked position, the released position, or positioned anywhere between the locked and released positions. However, in response to the extension of the directional locking mechanism 1960 or a force tending to extend the directional locking mechanism 1960, the locking element 1972 moves to or remains in the locked position (depending on its initial position), providing resistance to extension due to anticipated or normal operating forces. The directional locking mechanism 1960 can be further extended in response to a force applied by the user, for example, to allow removal of the interface assembly 1950.

[0177] FIGS. 49-51 show a portion of the elastic strap 1966 of the directional locking mechanism 1960 of FIGS. 46-48. The elastic strap 1966 shown is of tubular construction and includes an internal passageway that can accommodate the core member 1964. Thus, the core member 1964 can move within the elastic strap 1966 without rubbing against the user or other objects. Preferably, the elastic strap is a braid of multiple individual strands or threads (fibers) made of any suitable material in any suitable type of weave. The individual fibers can be woven such that adjacent fibers or groups of fibers have a specific initial angular orientation relative to one another, as shown in FIG. 49. Preferably, the initial angular orientation allows the braid to compress and stretch relative to the initial angular orientation, as shown in FIGS. 50 and 51, respectively. Thus, the initial angular orientation can be referred to as an intermediate angular orientation. The amounts of compression and stretch relative to the initial orientation can be the same or different from one another.

[0178] Preferably, as described above, the strap 1966 includes a biasing mechanism that biases the strap 1966 toward or into a compressed position. Accordingly, the strap 1966 is referred to as an elastic strap 1966. The biasing mechanism can be of any suitable construction, such as incorporating one or more elastic fibers within a braid. Preferably, the maximum elongation of the braid is selected to be less than the maximum elongation (or other operating range) of the biasing mechanism to avoid failure of the biasing mechanism at maximum elongation. In some configurations, the braid limits the maximum elongation of the biasing mechanism from reaching plastic deformation, maintaining the elongation operating range within the elastic range of operation of the biasing mechanism, such as the elastic elongation of the elastic fibers. The braid can also provide an end stop for the movement of the core member 1964, preventing the core member 1964 from being retracted into the lock 1962. That is, preferably, a portion of the core member 1964 remains within the lock 1962 when the braid is fully extended.

[0179] Referring to Figures 52-54, in some configurations, one or more elastic fibers 1980 can be incorporated into the braid during the weaving process. Figure 52 is a schematic diagram of a machine and process for making a braided elastic strap 1966. The machine includes multiple spindles 1982 having multiple cavities defined between radial projections or teeth. Adjacent spindles 1982 rotate in opposite directions, as indicated by the arrows, feeding a preferably relatively inelastic fiber or group of fibers 1984 from one spindle 1982 to the next. Another fiber or group of fibers 1984 moves in the opposite direction from one spindle 1982 to the next, interweaving the two fibers or group of fibers 1984. As shown in Figure 53, the elastic fiber 1980 can be threaded through the center of the spindles 1982 so that the elastic fiber 1980 is incorporated into the braid. FIG. 54 shows the elastic strap 1966 when the tubular member is cut longitudinally and laid flat.

[0180] FIG. 55 shows a rear portion 1956 of a headgear assembly 1954 that may be used with interface assembly 1950, other interface assemblies disclosed herein, or any other suitable interface. The rear portion 1956 of headgear assembly 1954 shown in FIG. 55 includes a lower rear section 1990 in the form of an interrupted or segmented strap that separates the load or provides an uneven load acting on the user's head, as opposed to a non-segmented strap that distributes the load along the entire length of the strap. That is, the lower rear section 1990 has a first portion 1990a and a second portion 1990b that are preferably interrupted and / or spaced apart and that can be joined by a coupling 1992, such as one or more straps or laces or a weakened portion of section 1990. The coupling 1992 can be relatively or substantially inelastic to substantially fix the relative position of the first and second portions 1990a, 1990b with respect to the longitudinal axis of the section 1990 (the length of the section 1990), but allow relative movement of the first and second portions 1990a, 1990b, either perpendicularly or rotationally, with respect to the longitudinal axis. Such a mechanism may be referred to as an articulating connector. Preferably, the first and second portions 1990a, 1990b form an occipital pad that engages on or near the occipital bone of the user's head. The space between the first and second portions 1990a, 1990b may be generally circumferentially disposed about the occipital protuberance, and the lower real section 1990 may be at or below the occipital protuberance in height. Preferably, the rear portion 1956 also includes an upper rear section 1994 that extends over the crown of the user's head. The ends of the lower rear section 1990 and the upper rear section 1994 join together at positions generally above the user's ears.

[0181] FIG. 56 shows a rear portion 1956 of a headgear assembly similar to the rear portion 1956 of FIG. 55 . Accordingly, details of the rear portion 1956 of FIG. 56 that are not described can be assumed to be the same as or similar to corresponding elements of the rear portion 1956 of FIG. 55 , or can be of any other suitable arrangement. The coupling 1992 of the rear portion 1956 of FIG. 56 includes an articulating connector, such as a material strap that can be elastic or substantially inelastic. Preferably, the coupling 1992 allows relative rotational movement between the first portion 1990 a and the second portion 1990 b about the longitudinal axis of the strap, allowing the lower rear section 1990 to better conform to the shape of the user's head, particularly the occipital bone shape.

[0182] Advantageously, the rear portion 1956 of FIGS. 55 and 56 provides user comfort while also securing a mask or other patient interface in place on the user's head. The interrupted lower rear section 1990 avoids excessive pressure on the occipital protuberance. Such an interrupted arrangement may also or alternatively be provided on the upper rear section 1994. The rear portion 1956 of either of FIGS. 55 and 56 may also incorporate one or more directional locking assemblies, such as any of those disclosed herein. For example, the coupling 1992 may be configured as a directional locking assembly. Directional locking assemblies may also be incorporated into either or both the lower rear section 1990 and the upper rear section 1994. For example, the flat strap arrangement of FIGS. 40-42 may be incorporated into either or both the first portion 1990a and the second portion 1990b.

[0183] FIGS. 57 and 58 illustrate two styles of interface assemblies that may be substantially similar to the interface assembly 1950 and related components described in conjunction with FIGS. 43-56. Accordingly, details of the rear portion interface assembly 1950 in FIGS. 57 and 58 that are not described can be assumed to be the same or similar to the corresponding elements of the interface assembly 1950 and related components described in conjunction with FIGS. 43-56. Alternatively, any other suitable arrangement may be used. In each interface assembly 1950, each side strap 1958 (which may incorporate a directional lock or be of a fixed length) is coupled to the rear portion 1956 of the headgear assembly 1954 at a point 1996 located near the user's ear. Preferably, point 1996 is in front of the ear and at or near (e.g., generally in line with) the ear and above where the outer ear joins the head (top of the base of the outer ear). The side strap 1958 extends from point 1996 to a mask 1952 or other interface. In the interface assembly 1950 of FIG. 57 , a single side strap 1958 on each side of the interface assembly 1950 extends from point 1996 to the mask 1952. In the interface assembly 1950 of FIG. 58 , a pair of side straps 1958 on each side of the interface assembly 1950 extend from point 1996 to spaced apart locations on the mask 1952 to provide a triangular arrangement. The triangular arrangement increases the stability of the mask 1952 in at least some cases. Preferably, the rearward projections of the side straps 1958 pass between the upper and lower straps of the rear portion 1956 of the headgear assembly 1954 so that the load is separated between the upper and lower straps. Examples of such arrangements and further details are disclosed in commonly-owned U.S. Patent Application Publication No. 2013 / 0074845, which is incorporated herein by reference in its entirety. As noted above, if desired, one or more directional locks may be incorporated into the interface assemblies 1950 of FIGS. 57 and 58 , such as those described herein, at any suitable location.

[0184] In any of the headgear embodiments described above, additional straps may be included to provide additional stability, such as, but not limited to, a crown strap or additional back straps.

[0185] Figure 59 shows a locking mechanism 1962 that is substantially similar to the locking mechanism 1962 of Figures 46-48. Accordingly, details of the locking mechanism 1962 of Figure 59 that are not described can be assumed to be the same as or similar to corresponding elements of the locking mechanism 1962 of Figures 46-48, or may be of any other suitable arrangement. The locking mechanism 1962 of Figure 59 is of a modular design that allows the directional locking technology to be easily incorporated into a variety of respiratory masks or other user interfaces.

[0186] The locking mechanism 1962 includes a housing or body portion 1970, a locking element 1972, and a living hinge 1974 connecting the locking element 1972 to the body portion 1970. The body portion 1970 includes a first end portion 2000 and a second end portion 2002. A generally U-shaped connecting bridge 2004 extends between the first and second end portions 2000, 2002 to provide space between the first and second end portions 2000, 2002 for receiving the locking element 1972. Preferably, each end portion 2000, 2002 is generally tubular or cylindrical in shape and defines a longitudinal passageway for receiving a core member. The locking element 1972 also includes a bore 2006 that allows for passage of the core member. Preferably, the end portions 2000, 2002, connecting bridge 2004, locking element 1972 and living hinge 1974 are of unitary construction.

[0187] FIG. 60 shows the locking mechanism 1962 of FIG. 59 incorporated into a patient interface assembly, such as a mask 1952. The depicted mask 1952 includes a wall 2010 that defines a pocket 2012 that receives the locking mechanism 1962. The wall 2010 may include a recess or opening that receives an end portion 2000, 2002 of the locking mechanism 1962, such as a male / female coupling. In the arrangement shown, the end portions 2000, 2002 define a male portion that can be received in a female portion (e.g., a recess or opening) of the mask 1952. Thus, the wall 2010 and / or pocket 2012 can hold the locking mechanism 1962 in place and can provide additional support to the body portion 1970. In other words, the wall 2010 can function as a structural housing or enclosure for the locking mechanism 1962. The first end portion 2000, the mask 1952, or both, can be configured to couple to a strap 1966, such as an elastic strap. The second end portion 2002, the mask 1952, or both, may be configured to support a tube 1968 that accommodates the free end of the core member 1964. Preferably, the mask 1952 is configured to accommodate the tube 1968, which may include being specifically configured to receive the tube 1968 (or having an integral tube), or simply accommodating the presence of the tube 1968 (such as having sufficient open or available space to receive the tube 1968).

[0188] The interface assemblies disclosed herein can employ generally elastic and generally inelastic portions that cooperate to define at least a portion of the loop or periphery of the interface assembly. The elastic portions allow for size variations in the interface assembly. The inelastic portions can form a structural portion of the loop or periphery, or can simply be used for orientation locking purposes, or both. Nevertheless, it is often necessary or desirable to allow for stretching or extension of the interface assembly, followed by accumulation of the inelastic portions upon retraction. For example, in the interface assemblies of FIGS. 43-54 , the core member 1964 moves with the extension of the elastic strap 1966, and the tube 1968 functions as an accumulator to accommodate the excess core member 1964 depending on the instantaneous amount of extension.

[0189] Other arrangements for providing tension and storage for a combined elastic / inelastic interface assembly or headgear mechanism are possible. Figures 61 and 62 show a headgear mechanism 2050 including a tubular elastic element 2052 that defines a portion of the loop or periphery of the headgear mechanism 2050 and has a first end 2054 and a second end 2056. The tubular elastic element 2052 shown makes up approximately one-half the length of the loop, although in other configurations the elastic tubular element 2052 can make up a smaller or larger percentage of the loop.

[0190] The headgear mechanism 2050 also includes a generally non-elastic element 2060 that forms at least a portion of the loop and that is preferably arranged in parallel with the elastic element 2052. In the arrangement shown, the non-elastic element 2060 extends over the entire length of the loop. That is, preferably, a first end 2062 of the non-elastic element 2060 is secured to the first end 2054 of the elastic element 2052 and a second end 2064 of the non-elastic element 2060 is secured to the second end 2056 of the elastic element 2052. From the first end 2062, the non-elastic element 2060 extends around the exterior of the elastic element 2052 to the second end 2056 of the elastic element 2052, through the interior of the elastic element 2052, and out the first end 2054 of the elastic element, before the second end 2064 of the non-elastic element 2060 is secured to the second end 2056 of the elastic element 2052, as described above. Thus, two overlapping lengths or sections of inelastic element 2060 are provided outside of elastic element 2052. Headgear mechanism 2050 preferably includes a connector 2066 that couples headgear mechanism 2050 to an interface, such as a mask. In the arrangement shown, connector 2066 is a tubular member through which both outer sections of inelastic element 2060 extend. Connector 2066 may be coupled to the mask in any suitable manner, including, for example, by being clipped to or incorporated into the mask.

[0191] To extend the length, more of the non-elastic element 2060 is pulled into the elastic element 2052 (or, in another aspect, the elastic element 2052 stretches to cover a greater portion of the non-elastic element 2060). As a result, the length of the overlapped section of the non-elastic element 2060 decreases, such that the effective perimeter of the non-elastic element 2060 (and headgear mechanism 2050) increases. To retract the length, a smaller portion of the non-elastic element 2060 is positioned within the elastic element 2052, performing the opposite action such that the length of the overlapped section of the non-elastic element 2060 increases. The relatively retracted and relatively extended positions are shown in FIGS. 63 and 64.

[0192] If directional locks are desired, one or more directional locks, such as any of those described herein, can be incorporated into the headgear mechanism 2050. FIG. 65 shows one example placement of directional locks at one or both ends 2054, 2056 of the elastic element 2052. The directional locks can affect relative movement between the ends 2054, 2056 and the non-elastic element 2060. FIG. 66 shows an alternative or additional placement of directional locks, such as at either end of the connector 2066, affecting relative movement between the non-elastic element 2060 and the connector 2066.

[0193] 67 and 68 show another headgear mechanism 2070 including an elastic element 2052 and a non-elastic element 2060. However, while the headgear mechanism 2050 is an endless loop or uninterrupted hoop, the headgear mechanism 2070 is an interrupted design having a first end portion 2072 and a second end portion 2074 that can be coupled to either side of a patient interface, such as a mask 2076 (FIG. 68). As such, the first end portion 2072 and the second end portion 2074 may each define an engagement portion, such as a hook or clip, that allows the end portion 2072 or 2074 to be coupled to the mask 2076 or other interface. However, because the ends of the interrupted design are interconnected by the patient interface, each of these arrangements can be considered to substantially encircle the user's head.

[0194] In the headgear mechanism 2070 of FIGS. 67 and 68 , the outer sections of the non-elastic elements 2060 are folded over and secured to the same side of the elastic elements 2052, instead of overlapping each other and being secured to opposite sides of the elastic elements 2052 as in the headgear mechanism 2050 of FIGS. 61 and 62 . Each of the end portions 2072, 2074 may include a pulley, which may be fixed or free (rotatable), or another suitable mechanism for reversing the direction of the outer sections of the non-elastic elements 2060. The operation of the headgear mechanism 2070 is substantially similar to the headgear mechanism 2050 in that the length of the outer sections may be increased, as shown in FIG. 69 , to decrease the length of the headgear mechanism 2070, or decreased, as shown in FIG. 70 , to increase the length of the headgear mechanism 2070. Additionally, the change in the overall length of the headgear mechanism 2070 results in more or less of the non-elastic elements 2060 being exposed or covered by the elastic elements 2052.

[0195] If directional locking is desired, one or more directional locks, such as any of those described herein, can be incorporated into the headgear mechanism 2070. FIG. 71 shows one example arrangement of directional locks at one or both ends 2054, 2056 of the elastic element 2052. The directional locks can affect relative movement between the ends 2054, 2056 and the non-elastic element 2060. FIG. 72 shows an alternative or further arrangement of directional locks, such as at either one or both of the first end portion 2072 and the second end portion 2074. In such an arrangement, the directional locks can affect relative movement between the non-elastic element 2060 and the first end portion 2072 or the second end portion 2074.

[0196] As described herein, embodiments of the present interface assemblies with balanced fit features may be used or modified for use with cannulas or other similar interfaces that do not form a seal with the user's face and therefore do not generate an insufflation force. FIG. 73 compares several force profiles, showing the equilibrium fit point of a cannula 2090 versus the equilibrium fit point of a CPAP mask 2092 within a unidirectional friction force profile 2098. The unidirectional friction force profile 2098 is an exemplary force profile that may be provided by the interface assemblies described herein. As shown, the equilibrium fit generally occurs at different forces for CPAP and cannula systems. With a cannula or similar non-sealing system, the equilibrium fit point 2090 occurs when the head circumference matches, because no insufflation force, or at least no significant insufflation force, occurs. With a CPAP system, the equilibrium fit point 2092 occurs when the head circumference matches the insufflation force. In a CPAP system, the headgear preferably provides an equilibrium fit point 2092 that can occur anywhere within the CPAP mask system operating envelope 2080. In a cannula system, the equilibrium fit point 2090 preferably occurs somewhere on a cannula equilibrium fit line 2082 defined by the line of lower force of the unidirectional friction force profile 2098. The cannula equilibrium fit line 2082 indicates that the force required to hold the cannula in place on the user's face is preferably less than the minimum force required to hold the CPAP mask in place, and generally falls within a narrower range due to the lack of blow-out force.

[0197] FIG. 73 also compares the force profiles of high-force elastic straps 2094 and low-force elastic straps 2096 with a high-hysteresis unidirectional friction force profile 2098. Low-force elastic straps may be used with a cannula to provide the user with a comfortable fit capable of overcoming the weight of the cannula alone. However, such an arrangement generally cannot accommodate any large external forces, such as hose pull. High-force elastic straps are generally required to accommodate external forces or, in the case of CPAP therapy, insufflation force. The force applied by high-force elastic strap headgear generally should be sufficient to accommodate the expected maximum force expected to be applied to the mask while also accommodating the expected minimum head size (indicated by the shaded mask system operating envelope 2080). However, this has the disadvantage of applying a minimum force that is higher than that required for low and / or no insufflation force, which may cause user discomfort. The unidirectional friction force profile 2098 shows that it offers the benefits of both high-force and low-force elastic straps. That is, the unidirectional friction force profile 2098 provides high resistance to extension and low force in the absence of blowing or external forces.

[0198] FIG. 74 illustrates a directional lock 2100 incorporating similar operating principles to other directional locks disclosed herein, such as, but not limited to, the directional locks of FIGS. 16, 21, 32, 33, 40-42, and 43-51. However, the directional lock 2100 illustrated in FIG. 74 is a two-stage directional lock incorporating two distinct locking stages 2102, 2104. Preferably, the two locking stages 2102, 2104 have different locking behaviors or characteristics. For example, the first locking stage 2102 may be a quick-acting lock that moves between the released and locked positions more quickly than the second locking stage 2104. The second locking stage 2104 may be a high-force lock that provides a stronger locking or yield force than the first locking stage 2102. Such an arrangement may allow for optimization of both the actuation force and locking force characteristics of the directional lock 2100. Features or details not described with respect to directional lock 2100 may be the same as or similar to the corresponding features or details of the arrangements of Figures 16, 21, 32, 33, 40-42 or 43-51, or may be of another suitable configuration.

[0199] The illustrated directional lock 2100 includes a core member 2110 (e.g., a core wire) passing through a lock body, which may be any suitable enclosure or housing 2112. The housing 2112 defines two lock chambers 2114 and 2116. Each lock chamber 2114, 2116 has a lock member 2120, 2122 (e.g., a lock washer) disposed therein. As described above, the core member 2110 passes through openings in the lock members 2120, 2122. Each lock chamber 2114, 2116 has a first stop surface 2114a, 2116a spaced from a second stop surface 2114b, 2116b in the direction of movement of the core member 2110 for limiting movement of the respective lock member 2120, 2122. The stop surfaces 2114a, 2116a, 2114b, 2116b may be defined by walls of the housing 2112 or any other structure suitable for limiting movement of the locking members 2120, 2122.

[0200] The locking members 2120, 2122 are movable between a locked position, in which resistance to movement of the core member 2110 is increased, and an released position, in which resistance to movement of the core member 2110 is decreased. In some configurations, movement of the core member 2110 causes the locking members 2120, 2122 to move between the locked and released positions. In the arrangement shown, unlike the arrangements previously described, the stop surfaces 2114a, 2116a, 2114b, 2116b are flat or planar, and the locking members 2120, 2122 are curved to define an effective locking angle that functions in a manner similar to the arrangements previously described. In particular, the openings in the locking members 2120, 2122 through which the core member 2110 passes are generally aligned with the axis of the core member 2110 in the released position, which can reduce friction and therefore locking force, and the openings can be angled or tilted in the locked position, which can increase friction and therefore locking force. In the arrangement shown, the locked position is when the locking members 2120, 2122 are moved to the left with a portion of the locking members 2120, 2122 flat against the stop surfaces 2114a, 2116a, and the released position is when the locking members 2120, 2122 are moved to the right with an edge of the locking members 2120, 2122 abutting the stop surfaces 2114b, 2116b. However, this arrangement can be reversed.

[0201] In either arrangement, angles α and β are defined by the difference between the unlocked and locked positions of the locking members 2120, 2122, respectively. Preferably, angle α is different from angle β. In some configurations, angle α is less than angle β. As noted above, in some configurations, the core member can move relative to the housing while the locking member moves from the unlocked position to the locked position, in the case of a single lock, or when the locking member moves from the locked position to the unlocked position. In some cases, the movement of the core member is related to the angle of the locking member between the unlocked and locked positions. Also as noted above, in some configurations, the locking force is related to the locking angle, and the locking force increases with the locking angle. Thus, there may be a trade-off between providing a high locking force and providing a small core member movement between the unlocked and locked positions. The amount of core member movement required to move between the unlocked and locked positions may be applied in terms of the lock's actuation length (amount of core movement) or actuation speed (time required to transition between the unlocked and locked positions), which may depend on the force tending to move the core member (e.g., headgear retraction force).

[0202] In the arrangement shown, the first lock stage 2102 is a quick-acting lock that moves between the released and locked positions with less movement of the core member 2110 or more quickly than the second lock stage 2104. The movement of the lock member 2120 or core member 2110 between the released and locked positions is indicated by the distance "a" in FIG. 74. The relatively small movement distance allows the first lock stage 2102 to move between the released and locked positions in response to small adjustment movements of the associated interface assembly. Some applications focus on movement from the released to the locked position because the lock 2100 allows movement of the core member 2110 (and extension of the associated headgear) until the lock 2100 moves to the locked position. However, movement in other directions may also require movement of the core member, which may be a feature of interest in some applications.

[0203] In use, a user may attempt to fine-tune the interface assembly by rocking or pushing the mask / interface to pressurize the seal and thereby retract the headgear, or by moving the core member 2110 in a direction that attempts to move the locking member 2120 toward the released position (right in FIG. 74 ). The first locking stage 2102 rapidly moves to the locked position when the user removes pressure from the mask / interface, preferably allowing a small amount of corresponding headgear extension. As a result, the directional lock 2100 responds to small movements of the mask / interface and locks the mask / interface very close to the desired adjustment position. As described above, the first locking stage 2102 can move quickly to the locked position due to the relatively small locking angle α. However, the first locking stage 2102 may provide a maximum locking force that is lower than the desired locking force, again due to the relatively small locking angle α.

[0204] However, the second lock stage 2104 can be a high-force lock that can provide the desired maximum locking force for the directional lock 2100. The second lock stage 2104 can have a movement of the lock member 2122 or core member 2110 between the released and locked positions, indicated by distance "b" in FIG. 74 . In some configurations, distance "b" is greater than distance "a" of the first lock stage 2102. As noted above, the locking angle β of the second lock stage 2104 can be greater than the locking angle α, which can result in the second lock stage 2104 having a stronger locking force than the first lock stage 2102 in some configurations. The first lock stage 2102 and second lock stage 2104 combined can result in a directional lock 2100 that is responsive to small adjustment movements of the corresponding headgear / interface while also providing sufficient locking or yield force to handle normal or anticipated operating forces.

[0205] In some configurations, distance "a" is approximately 1 millimeter or less to provide fine adjustment of the corresponding headgear / interface. However, in some configurations, distance "a" can be greater than 1 millimeter. Distance "a" can be selected based on the locking distance that can be tolerated in a particular application. In other words, distance "a" can be selected based on the level of fine adjustment required or desired in a particular application. As described above, the interface assembly can include more than one directional lock, for example, one on each side of the interface assembly. Thus, the total locking distance can be greater than the locking distance of a single directional lock and, in some cases, can be the sum of the individual locking distances. Distance "b" can be selected to achieve a desired maximum locking force. In some configurations, distance "b" can be at least approximately 2 times larger, at least approximately 5 times larger, at least approximately 10 times larger, or at least approximately 20 times larger than distance "a." The ratio of angle α to angle β can be the same as or similar to the ratio of distance "a" to distance "b."

[0206] FIG. 75 shows a force profile 2200 for a headgear or interface assembly including at least one two-stage directional lock, such as directional lock 2100 of FIG. 74. Force profile 2200 may be generally similar to the force profiles described in conjunction with FIGS. 2-5. Accordingly, force profile 2200 includes an initial steep rise 2220 indicating resistance to initial extension. The force profile also includes a substantially flat, generally constant extension curve 2222 indicating further extension of the headgear and a decrease 2224 as the headgear retracts to fit the user's head. However, in contrast to the force profiles of FIGS. 2-5, force profile 2200 includes a stepped balanced fit section 2230 indicating the transition between first locking stage 2102 and second locking stage 2104.

[0207] In particular, the counterbalanced fit section 2230 may include a first portion 2230a and a second portion 2230b. The first portion 2230a may be related to a characteristic of the first locking stage 2102, and the second portion 2230b may be related to a characteristic of the second locking stage 2104. The second portion 2230b may also be affected by the resistance provided by the first locking stage 2102 in conjunction with the second locking stage 2104. As shown, the second portion 2230b is offset from the first portion 2230a by a transition 2230c, which may reflect the transition from the first locking stage 2102 to the second locking stage 2104. That is, this offset may reflect the difference between distance "b" and distance "a" in FIG. 74.

[0208] The balance fit section 2230 includes a solid line that indicates the extension of the headgear up to an equilibrium fit point 2234. A dashed line above the equilibrium fit point 2234 indicates the additional extension that the headgear may experience in response to additional force. In the illustrated configuration, the equilibrium fit point 2234 is within the performance range of the first locking stage 2102. That is, the equilibrium fit point 2234 is less than the maximum locking force of the first locking stage 2102. However, in some cases, such as with high treatment pressures, the balance fit point 2234 may exceed the maximum locking force of the first locking stage 2102 and may be within the second portion 2230b of the balance fit section 2230. Preferably, the balance fit point 2234 is less than the maximum locking force of the second locking stage 2104. The yield point 2236 may be defined by the intersection of the equilibrium fit section 2230 and the constant extension curve 2222.

[0209] The initial actuation length 2240 is defined as the extension distance between the beginning of the balanced fit section 2230 and the balanced fit point 2234. The initial actuation length 2240 may be related to the distance "a" of the first lock stage 2102. The secondary actuation length 2242 may be defined as the extension distance between the balanced fit point 2234 and the end of the transition portion 2230c / beginning of the second portion 2230b of the balanced fit section 2230. The secondary actuation length 2242 may be related to the distance "b" of the second lock stage 2104. Force profile 2200 is merely an example of a force profile that may be provided by a two-stage directional lock such as lock 2100. Directional locks having a variety of different force profiles to suit particular applications or desired performance criteria can be realized based on the teachings of the present disclosure. For example, a two-stage or multi-stage lock can be created by combining multiple individual locks of any type disclosed herein. The individual locks can be of the same type or different types within a single, two-stage, or multi-stage lock.

[0210] While certain mechanical orientation locking mechanisms are specifically illustrated herein, other mechanical and non-mechanical methods and devices for achieving self-fit, high hysteresis, or orientation locking may also be used. For example, electrical, piezoelectric, pneumatic, hydraulic, or thermo-mechanical devices may be configured to provide functionality similar to the interface assemblies disclosed herein. In some configurations, such methods or devices may selectively grip or release the inelastic core in a manner similar to the devices disclosed herein.

[0211] In one example of an electrical device, a solenoid clutch can be used to provide a directional locking function. For example, an electrical coil around a plunger can move the plunger when energized. This movement can be used to directly or indirectly pinch or grip a non-extensible member of a self-adjusting headgear to retain the non-extensible member. A retention mechanism can release the non-extensible member to allow extension. The solenoid clutch can be controlled by any suitable device, such as a button. Alternatively, a sensor can determine when the headgear is positioned and / or when CPAP pressure is activated and the retention mechanism can be activated.

[0212] Alternatively, a stepper motor or servo motor may be used to actively hold the position of an adjustable headgear member, such as a non-extending member. Retraction and / or extension may be performed by a motor. In some configurations, an electromagnetic force generator may be used to act on an adjustable headgear member having magnetic sections or properties. Retraction may be performed by a linear motor. In some configurations, an electro-active polymer may be used to create a clutch or pinching mechanism in response to an electric current that acts on and holds the adjustable headgear member. Alternatively, an electromagnetic force may be applied to a magnetic liquid to create a clutch or pinching mechanism that can hold the adjustable headgear member.

[0213] In one example of a piezoelectric device, a piezoelectric clutch or clamp can be used to release free movement of non-extending headgear. Examples of piezoelectric mechanisms include piezo membranes (buzzers), diesel engine valves, and inkjet nozzles. Each of these mechanisms uses a piezoelectric element to generate movement / displacement. Such piezo mechanisms can be used directly or to drive a retaining clutch to selectively hold an adjustable member of a self-fitting headgear. Several piezoelectric components can be configured to create a so-called inchworm motor. Inchworm motors (or similar) devices are particularly useful for linear motion. Such motion can be utilized to adjust a self-fitting headgear mechanism.

[0214] In pneumatic devices, a clutch or gripping mechanism may be operated by a pneumatic cylinder or pneumatic bellows, actuated by CPAP pressure or an auxiliary air / gas supply. The clutch or gripping mechanism may directly or indirectly hold the adjustable member of the self-fitting headgear. Similarly, in hydraulic devices, a hydraulic cylinder or bladder may be used to hold the adjustable member of the self-fitting headgear. For example, CPAP pressure may be used to pressurize the hydraulic fluid. Alternatively, a piston may be mechanically actuated to pressurize the hydraulic fluid.

[0215] In thermomechanical devices, a heat-sensitive substance (e.g., wax) can be used to actuate a clutch or retention mechanism to retain an adjustable member of a self-fitting headgear. Activation of the clutch or retention mechanism can be achieved by contact with the user's skin or another suitable heat source, such as the heated breather tube of a CPAP system, or by proximity to the warmth of the user's skin or another suitable heat source, such as the heated breather tube of a CPAP system. Thermostatic valves typically use wax-filled cartridges. The wax expands or contracts with temperature changes, which is then translated into, for example, plunger movement. In the absence of sufficient heat, the clutch releases its grip, allowing the headgear to fit the user. When the headgear is in place and the thermomechanical clutch is exposed to a heat source, the clutch can engage and inhibit expansion of the headgear. Another example of a heat-sensitive substance is a bimetallic member that deforms under the influence of heat, and this displacement can be used to actuate a retention clutch or lock on a self-fitting headgear.

[0216] While various embodiments have been described, it should be noted that any adjustment mechanism can be combined with any other assembly. Additionally, an adjustment mechanism can be used without a break-fit assembly, and a break-fit assembly can be used without an adjustment mechanism. Furthermore, any interface (i.e., mask and headgear) can be used with either or both of the adjustment mechanisms and / or break-fit assemblies described herein. Break-fit assemblies can include, but are not limited to, those described in U.S. Provisional Patent Application No. 61 / 681,024, filed August 8, 2012, which is incorporated herein by reference in its entirety.

[0217] Although the present invention has been described in terms of specific embodiments, other embodiments apparent to those skilled in the art are also within the scope of the present invention. Accordingly, various changes and modifications may be made without departing from the scope and spirit of the present invention. For example, various components may be rearranged as desired. Moreover, not all features, aspects, and advantages are necessary to practice the present invention. Accordingly, the scope of the present invention is to be defined only by the following claims.

Claims

1. 1. A respiratory therapy headgear configured to extend and retract to fit a user's head, the headgear requiring a first load force to be applied to extend the headgear and a second load force to be applied to retract the headgear to fit the user's head, the first load force being greater than an expected load force applied to the headgear during respiratory therapy, and the second load force being less than the expected load force.

2. The headgear of claim 1 , wherein the expected load forces include a resultant force including a force due to CPAP pressure and a hose drag force.

3. 3. The headgear of claim 1 or 2, wherein the first load force is greater than the expected load force by a reserve amount.

4. The headgear of any one of claims 1 to 3, further comprising an elastic element applying a retraction force to the headgear, the retraction force being greater than the second load force.

5. 1. A headgear for securing a mask to a user's face, the headgear comprising: an elastic portion configured to provide a retraction force; an inelastic portion configured to be inelastic relative to the elastic portion; and a limiting mechanism coupled to the inelastic portion and the elastic portion, the limiting mechanism configured to require a first resistance force to allow extension of the headgear and a second resistance force in response to retraction of the headgear.

6. The headgear of claim 5 , wherein the first resistance force is greater than the second resistance force.

7. 7. Headgear according to claim 5 or 6, wherein the first resistance force is greater than a combined resistance force including a force due to CPAP pressure and a hose drag force.

8. The headgear of any one of claims 5 to 7, wherein the second resistance force is smaller than a resultant force including a force due to CPAP pressure and a hose drag force.

9. Headgear configured to extend and retract to fit a user's head, the headgear having a first extension resistance force in the absence of radial tension and a second extension resistance force in response to radial tension.

10. The headgear of claim 9 , wherein the first elongation resistance force is less than the second elongation resistance force.

11. 11. Headgear according to claim 9 or 10, wherein the second extension resistance force is generated as a result of engagement of two portions of the headgear.

12. 12. Headgear according to any one of claims 9 to 11, wherein the second extension resistance force is greater than a resultant force including a force due to CPAP pressure and a hose drag force.

13. 1. Headgear for securing a mask to a user's face, the headgear comprising: an elastic portion configured to provide a retraction force; an inelastic portion configured to be inelastic relative to the elastic portion; and a limiting mechanism coupled to the inelastic portion and the elastic portion, the limiting mechanism configured to apply an elongation resistance force when the headgear is subjected to radial tension.

14. 1. A patient interface system comprising: an interface portion sized and shaped to surround a user's nose and / or mouth and configured to form at least a substantial seal with the user's face; a coupling allowing the patient interface system to be coupled to a gas delivery system; a headgear system that allows the interface portion to be positioned and retained on the user's head, the headgear system providing a deformation-locking behavior that is capable of deforming from an elastic-type extensional behavior to a substantially inextensible behavior when the patient interface system is in use; 1. A patient interface system comprising:

15. The patient interface system of claim 14 , wherein the deformation locking behavior is provided by a mechanically based orientation lock.

16. 16. A patient interface system according to claim 14 or 15, wherein the headgear system provides an inextensible behavior in the range of about 0.5N to about 65N.

17. A patient interface system according to any one of claims 14 to 16, wherein the deformation locking behavior is provided by a mechanical directional lock including a lock housing, a movable locking member, and a core member.

18. 18. The patient interface system of claim 17, wherein the core member has a cross-sectional dimension ranging from about 0.1 mm to about 8 mm.

19. 19. A patient interface system according to claim 17 or 18, wherein the locking member is movable relative to the core member through an angular range of about 0° to about 45°.

20. A patient interface system according to any one of claims 17 to 19, further comprising a biasing mechanism acting on the locking member and controlling a locking retention force.

21. A patient interface system according to any one of claims 17 to 20, wherein the directional lock incorporates a friction promoter to facilitate actuation of the lock.

22. A patient interface system according to any one of claims 17 to 21, wherein the core member is a cord.

23. A patient interface system according to any one of claims 17 to 21, wherein the core member is a strap.

24. 15. The patient interface system of claim 14, wherein the deformation locking behavior is provided by directional locking using mechanical adhesion, the mechanical adhesion being provided by van der Walls forces through the use of nanofiber material.

25. 15. The patient interface system of claim 14, wherein the deformation locking behavior is provided by a directional lock using mechanical adhesion, the mechanical adhesion being provided by a microstructure.

26. 26. A patient interface system according to any one of claims 14 to 25, wherein the elastic tension is provided by an elastic tension system including a fabric spring having an embedded elastic element.

27. 27. A patient interface system according to claim 26, wherein the fabric spring is configured as a braid in which the elastic and non-elastic elements are interlaced such that the non-elastic elements provide a physical end stop to elongation before the elastic elements plastically deform.

28. 28. A patient interface system according to claim 27, wherein the amount of elastic element in the braid is selected to achieve desired force versus extension characteristics of the cloth spring.

29. 15. A patient interface system according to claim 14, wherein the deformation locking behavior is provided by a mechanical directional lock including a housing, a movable locking member within the housing, and a core member, wherein the housing guides movement of the core member, and wherein both the housing and the locking member are formed by a single integral module.

30. 15. The patient interface system of claim 14, wherein the deformation locking behavior is provided by a mechanical directional lock including a locking module, a non-resilient portion, and a resilient portion, the locking module, the non-resilient portion, and the resilient portion forming a modular adjustment assembly.

31. 31. The patient interface system of claim 30, wherein the interfacing portion is a mask, and the modular adjustment assembly is coupled to a frame of the mask.

32. 32. The patient interface system of claim 31 , wherein the frame includes one or more walls that define a space that receives the locking module.

33. 31. The patient interface system of claim 30, wherein the modular adjustment assembly is coupled to a portion of the headgear system.

34. 32. The patient interface system of claim 31 , wherein the portion of the headgear system is a rear portion including at least one of a lower rear strap and a crown strap.

35. 35. A patient interface system according to any one of claims 14 to 34, wherein the headgear system includes a portion that passes over or under the occipital protuberance, said portion incorporating features that provide uneven loading on a posterior portion of the head.

36. 36. A patient interface system according to claim 35, wherein the portion passing over or below the occipital protuberance comprises an interrupted strap.

37. 37. A patient interface system according to claim 36, wherein the interrupted strap includes a first strap section and a second strap section joined by a coupling.

38. 38. A patient interface system according to claim 37, wherein the coupling allows relative movement between the first strap section and the second strap section.

39. 39. A patient interface system according to claim 38, wherein the relative movement comprises rotational movement about a longitudinal axis of the interrupted strap.

40. 40. A patient interface system according to any one of claims 35 to 39, wherein the headgear system further includes a portion that passes over the occipital protuberance, said portion incorporating features that provide uneven loading on a crown portion of the head.

41. 35. A patient interface system according to any one of claims 14 to 34, wherein the headgear system includes a portion that passes on or above the occipital protuberance, said portion incorporating features that provide uneven loading on the head.

42. 35. A patient interface system according to any one of claims 14 to 34, wherein the headgear system includes a rear portion and at least one side strap on each side of the interface system connecting the rear portion to the interface portion.

43. 43. A patient interface system according to claim 42, wherein, in use, the at least one side strap is coupled to the rear portion of the headgear system at a location that is located in front of and at or near an upper portion of the user's outer ear.

44. 44. A patient interface system according to claim 42 or 43, wherein the rear portion of the headgear system includes upper and lower straps, the rear projection of the at least one side strap passing between the upper and lower straps.

45. 45. A patient interface system according to any one of claims 42 to 44, wherein the at least one side strap comprises a pair of side straps arranged in a triangular configuration.

46. 15. A patient interface system according to claim 14, wherein the deformation locking behavior is provided by a locking mechanism that acts on one or more inextensible elements contained within the headgear system to substantially separate elastic portions of the headgear system.

47. 47. A patient interface system according to any one of claims 14 to 46, wherein the headgear system incorporates a mechanism that allows it to fit a variety of head sizes, the mechanism including both elastic and generally inextensible elements arranged in juxtaposition to one another.

48. 47. A patient interface system according to any one of claims 14 to 46, wherein the headgear system incorporates a mechanism that allows it to fit a variety of head sizes, the mechanism including one or more generally non-extensible elements that substantially encircle the user's head.

49. 49. A patient interface system according to claim 48, wherein a first portion of the inextensible element overlaps a second portion of the inextensible element longitudinally of the headgear system.

50. 50. A patient interface system according to claim 49, wherein the first and second portions are first and second ends of the non-extensible element.

51. 50. A patient interface system according to claim 49, wherein the first portion and the second portion are part of one end of the non-extensible element.

52. 15. The patient interface system of claim 14, wherein the deformation locking behavior is provided by a manual lock, a pneumatically actuated lock, an electrically actuated lock, a piezoelectrically actuated lock, a hydraulically actuated lock, or a thermo-mechanically actuated lock.

53. 53. A patient interface system according to any one of claims 14 to 52, wherein the deformation locking behavior has a first locking stage providing a first locking force and a second locking stage providing a second locking force, the second locking force being greater than the first locking force.

54. 54. A patient interface system according to claim 53, wherein the first locking stage converts to the generally non-extending behavior having a smaller extension movement compared to the second locking stage.

55. A respiratory therapy headgear configured to extend and retract to fit a user's head, the headgear requiring the application of a first load force to extend the headgear, and when the headgear fits the user's head, the headgear provides a balancing force equal to a load force applied to the headgear during respiratory therapy, the first load force being greater than the balancing force.

56. 56. The headgear of claim 55, wherein the load forces applied to the headgear during respiratory therapy include CPAP pressure forces and hose drag forces.

57. 57. The headgear of claim 55 or 56, wherein the first loading force is greater than the loading force applied to the headgear during respiratory therapy by a reserve amount.

58. 58. Headgear according to any one of claims 55 to 57, further comprising an elastic element that applies a retraction force tending to retract the headgear.

59. 59. The headgear of claim 58, wherein the retraction force is less than the loading force applied to the headgear during respiratory therapy.

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