Headgear tensioning for respiratory mask

1. A patient interface assembly configured to deliver pressurized gas to a patient's airways, the patient interface assembly comprising:

a patient interface structure configured to sealingly engage the patient's face and including a receptacle; and

headgear configured to support the patient interface structure on the patient's head, the headgear including a clip that is receivable by the receptacle,

wherein the receptacle and the clip together form a multiple stage connection arrangement in which each of the multiple stages corresponds to an interlocked position of the clip in the receptacle, and

wherein each stage is associated with a corresponding range of headgear tension, and

wherein the clip is configured to be pulled from one stage to an adjacent stage in response to a headgear tension reaching a first threshold tension.

2. The patient interface assembly of claim 1 , wherein the clip is configured to provide an audible and/or tactile feedback as the clip moves from one stage to another stage.

3. The patient interface assembly of claim 1 , wherein the receptacle includes opposed sides, each opposed side comprising an inward projection, and wherein the clip includes at least one spring arm having a plurality of projections that form adjacent recesses.

4. The patient interface assembly of claim 3 , wherein the multiple stage connection arrangement is configured so that when the clip and the receptacle are engaged, the inward projections of the opposed sides of the receptacle move between adjacent recesses in response to a change in headgear tension.

5. The patient interface assembly of claim 1 , wherein the multiple stage connection arrangement is configured so that the clip and the receptacle separate when headgear tension is greater than a second threshold tension that is greater than the first threshold tension.

6. A patient interface assembly configured to deliver pressurized gas to a patient's airways, the patient interface assembly comprising:

a patient interface structure configured to sealingly engage the patient's face and including a receptacle; and

headgear configured to support the patient interface structure on the patient's head, the headgear including a clip that is receivable by the receptacle,

wherein the receptacle and the clip together form a two-stage connection arrangement in which a first stage corresponds to a first interlocked position of the clip in the receptacle and a second stage correspond to a second interlocked position of the clip in the receptacle,

wherein the first and second interlocked positions are arranged so that when the clip exits the first stage, the clip must enter the second stage, and

wherein the clip is configured to be pulled from the first stage to the second stage in response to a headgear tension reaching a first threshold tension.

7. The patient interface assembly of claim 6 , wherein the clip is configured to provide an audible and/or tactile feedback as the clip moves from the first stage to the second stage.

8. The patient interface assembly of claim 6 , wherein the first stage is associated with a first headgear tension and the second stage is associated with a second headgear tension that is greater than the first headgear tension.

9. The patient interface assembly of claim 6 , wherein the two-stage connection arrangement is configured so that the clip and the receptacle separate when headgear tension is greater than a second threshold tension that is greater than the first threshold tension.

10. The patient interface assembly of claim 6 , wherein the clip is inserted further into the receptacle when the clip is in the first stage than when the clip is in the second stage.

11. The patient interface assembly of claim 6 , wherein the first and second interlocking positions are arranged so that the two-stage connection arrangement must be in the second stage before entering the first stage.

12. A patient interface assembly configured to deliver pressurized gas to a patient's airways, the patient interface assembly comprising:

a patient interface structure configured to sealingly engage the patient's face and comprising a receptacle with opposed sides that each includes an inward projection; and

headgear configured to support the patient interface structure on the patient's head, the headgear comprising a clip that is receivable by the receptacle and includes at least one spring arm having a first projection and a second projection that respectively form first and second recesses,

wherein the receptacle and the clip together form a two-stage latch arrangement that is in a first stage when the inward projections of the opposed sides of the receptacle are in the first recess,

wherein the two-stage latch arrangement is in a second stage when the inward projections of the opposed sides of the receptacle are in the second recess, and

wherein the two-stage latch arrangement is configured to be pulled from the first stage to the second stage in response to a headgear tension reaching a first threshold tension.

13. The patient interface assembly of claim 12 , wherein the clip is configured to provide an audible and/or tactile feedback as the two-stage latch arrangement moves from the first stage to the second stage.

14. The patient interface assembly of claim 12 , wherein the at least one spring arm is configured to resiliently flex inwardly when the inward projections of the opposed sides of the receptacle engage any of the first and second projections.

15. The patient interface assembly of claim 14 , wherein the second projection prevents the inward projections of the opposed sides of the receptacle from entering the second recess when headgear tension is less than the first threshold tension.

16. The patient interface assembly of claim 15 , wherein the second projection prevents the inward projections of the opposed sides of the receptacle from exiting the second recess when headgear tension is less than a second threshold tension that is greater than the first threshold tension.

17. The patient interface assembly of claim 15 , wherein the first and second recesses are arranged so that the inward projections of the opposed sides of the receptacle must enter the second recess after exiting the first recess.

18. The patient interface assembly of claim 12 , wherein the clip is inserted further into the receptacle when the inward projections of the opposed sides are in the first recess than when the inward projections of the opposed sides are in the second recess.

19. The patient interface assembly of claim 12 , wherein the first and second recesses are arranged so that the inward projections of the opposed sides of the receptacle must enter the second recess before entering the first recess.

20. The patient interface assembly of claim 12 , wherein the first projection on the at least one spring arm has a different shape than the second projection on the at least one spring arm.