Method of and apparatus for detecting bubbles from hermetic container and method of detecting leak in hermetic container

An apparatus for detecting bubbles comprising:

• a bubble collecting section,
• bubble detecting means provided in a throttle section, and
• a bubble releasing section,
• wherein said bubble collecting section is more widely open toward the lower end portion thereof, and said throttle section is formed in such a manner as to continue from said bubble collecting section, said bubble detecting means being arranged such that a light beam is emitted from one of a pair of optical fibers arranged with a gap therebetween and that the other one of said pair of optical fibers receives said light beam, said bubble releasing section being formed in such a manner as to continue from said throttle section and having a widely open upper end portion.

A method of detecting a leak in a hermetic container, comprising the steps of:

• applying pressurized air to a hermetic container immersed in a liquid to cause bubbles to escape from said hermetic container;
• converting the bubbles thus formed into pulse signals to obtain bubble signals by passing the bubbles through a gap between a pair of optical fibers with a light beam emitted therebetween whereby the bubbles continually diffuse the beam to form the pulse signals;
• processing said bubble signals by a logical circuit to detect the number of said pulse signals (representing the number of bubbles) or the total of pulse widths (representing the volume of bubbles) during a set time;
• and
• comparing the detected value with a predetermined value to determine the presence or absence of a leak in said hermetic container.

A method of detecting a leak in a hermetic container, comprising the steps of:

• applying pressurized air to a hermetic container immersed in a liquid to cause bubbles to escape from said hermetic container;
• converting the bubbles thus formed into pulse signals to obtain bubble signals;
• inputting said bubble signals and timer pulses to a logical circuit to detect the total number of pulses of the bubble signals that are present during a period when said timer pulses continue;
• determining the amount of change in the total number of pulses of said bubble signals in the pulse widths of mutually adjacent timer pulses;
• and
• comparing the value thus determined with a preset value to determine the presence or absence of a leak in said hermetic container.