GB779943A - Improvements relating to respiratory masks - Google Patents

Abstract

779,943. Respiratory masks. BRITISH OVERSEAS AIRWAYS CORPORATION. Feb. 10, 1955 [Feb. 16, 1954; July 27, 1954], Nos. 4552/54 and 21936/54. Class 81(2) A respiratory mask is held against the face by having at each side a toggle composed of two pivoted links extending forwards from points of attachment to the farepiece and a support on the wearer's head respectively. relative movement between the links being limited by a stop which prevents breaking of the toggle by downward movement of the links but allows the toggle to be broken by upward movement of the lower end of the links to detach the mask from the face. The facepiece 1 is secured to a head harness comprising earpieces 16 and flexible head bands 25, by links, one pair of links being in the. form of a U-shaped rod 7 hinged at its ends to brackets 6 on the facepiece 1 and passing through a sleeve member 9 through which a second U-shaped rod 11 forming the second pair of links also passes. The ends of the second U-shaped rod 11 are secured by eyes 13 to spring catches 14 on attachment plates 15 rotatable on the earpieces 16. A turnbuckle 12 is provided near each end of the second rod 11. An earphone 19 is provided on each earpiece 16. A counterpressure band 28 passes across the back of head between the earpieces 16. A microphone 3 is provided in the facepiece 1. A second microphone 22 rotatably secured to one earpiece is used when the facepiece 1 is not in use. The facepiece 1 falls away from the face when the toggle is broken by pushing the sleeve 9 past its dead-centre position. Microphone and earphone leads 29 are connected with one earpiece and a lead 30 runs from the earpiece to the microphones 3, 22. Plugs 32, 34 alternatively connect either microphone with the earpiece. In an alternative construction the sleeve 9, Fig. 3, is replaced by a short connecting member 41 having a finger piece and one U-shaped rod 43 is hinged to a plastic support 45 for a moulded rubber facepiece 46. The connecting member 41 may be arranged in two alternative positions so that two alternative pressures are exerted on the facepiece by the toggle linkage. In an alternative arrangement the sleeve 9, Fig. 6, or short connecting member 41 is replaced by two members 50, 51 through each of which a U-shaped rod passes. A shaft 55 having a helical groove 56 is journalled in these members 50, 51 and a pin 57 in one member 50 is moved along the groove 86 as required to vary the pressure applied to the facepiece.