GB1307415A - Sealed watch-case with leakage indicator - Google Patents

Abstract

1307415 Watches E PIQUEREZ 4 June 1970 [4 June 1969 28 Nov 1969] 27071/70 Heading G3T An indicator for monitoring the seal in a sealed watch case comprises a members which is displaceable in the event of a change in the pressure differential between the interior of the case and a secondary, sealed compartment. Fig.3 shows an evacuated watch case in which the displaceable member is a piston 15 slidably mounted in a tube 14 which is screwed into the case. The interior of tube 14 is sealed at a low-pressure by a glass 16 and loss of vacuum in the case causes the piston 15 to move upwardly so that a battery 19 comes into contact with a lamp 18. If seal 24 is non- conducting, the circuit is completed through a spring blade contacting the tube and piston. The lamp and battery may be omitted and the indication given by a coloured neck (11) Fig.1 (not shown) on the piston. Alternatively the indicator may comprise a membrane (32) Figs.5, 6 (not shown) whose curvature is altered by loss of vacuum or which becomes distorted by pressure from a plastics piston (29) Fig.4 (not shown) to change a pattern of Newton's rings. Other indicators are referred to in which the displaceable member is a plug of liquid in a capillary tube within the watch case, the position of the plug providing an indication in a window.