Abstract: The present disclosure discloses a contact angle measuring device, including a light source, a container, a photodetector, a bubble generating unit, and a processing unit. The container includes a first and a second side walls that are opposite. The first side wall is made of a light-transmitting material, the container is filled with a liquid with light transmission inside. The monochromatic light emitted by the light source passes through the first side wall and enters an interface between the first side wall and the liquid. The bubble generating unit is configured for generating a bubble that is in contact with an inner surface of the first side wall. The photodetector is configured for detecting light intensity distribution of the monochromatic light through the liquid.

Abstract: There is disclosed a wireless sound equipment including a body which is wearable on a user's body, a first hole formed in an upper portion of the body, a second hole formed in a lower portion of the body toward the user's body when the user wears the wireless sound equipment, a first speaker configured to output sound via the first hole, and a second speaker configured to output sound via the second hole.

Abstract: There is disclosed a wireless sound equipment including a body which is wearable on a user's body, a first hole formed in an upper portion of the body, a second hole formed in a lower portion of the body toward the user's body when the user wears the wireless sound equipment, a first speaker configured to output sound via the first hole, and a second speaker configured to output sound via the second hole.