Hinge mechanism

A foldable device, comprising:

• a housing;
• a flip, pivoting on the housing;
• and
• a hinge mechanism, for pivotally connecting the flip onto the housing so that the flip capable to rotate around a pivoting axis, the hinge mechanism comprising:
• a bush having a sidewall, a protrusion, and a receiving space defined by the sidewall, the protrusion being protruded from the sidewall;
• a release button having a first end, a second end, and a shaped notch, the shaped notch having a concave portion, a stop portion, and a convex portion formed between the concave portion and the stop portion, the stop portion extending substantially parallel to the pivoting axis, the protrusion slidably received within the shaped notch, the first end of the release button slidably coupled to the bush, and the second end of the release button restrictedly coupled to the housing, so that the release button is only slidable relative to the housing substantially along the pivoting axis;
• and
• a compression spring disposed within the receiving space and pressed by the release button and the bush;
• wherein when the flip pivots from an opened position to a closed position, the bush simultaneously rotates around the pivoting axis so that the protrusion moves from the concave portion to the stop portion;
• wherein only when the release button is moved toward the bush till the protrusion moves out of the stop portion and reaches the convex portion, the flip is capable to pivot from the closed position to the opened position.