Method and apparatus for inspecting sealing defect of container

An apparatus for inspecting sealing defects in a sealed portion of a container sealed planewise using infrared light, comprising:

• a phototransmitter, which irradiates the infrared light in a wavelength range of 1450 nm±20 nm onto the sealed portion of the container, the container including a content therein, and the container being sealed after being filled with the content;
• a photoreceiver, which receives the infrared light reflected from or transmitted through the sealed portion of the container at an outside of the container;
• a voltage generating means, which outputs an analog voltage value according to an amount of the received infrared light;
• a threshold holding means, which sets a threshold based on an analog voltage value outputted from the voltage generating means in a case where the infrared light is irradiated onto a sealed portion of a sample container and being irradiated from an outside of the sample container, which sample container does not have a sealing defect;
• a comparing means, which compares an analog voltage value outputted from the voltage generating means in a case where the infrared light is irradiated onto the sealed portion of the container being inspected with the threshold;
• and
• a judging means, which judges that a sealing defect exists when the analog voltage value outputted from the voltage generating means in the case where the infrared light is irradiated onto the sealed portion of the container being inspected is smaller than the threshold.