Abstract: The invention relates to a hinge mechanism for a foldable device. The previously known devices of this type do not stay in the open position in the desired manner, but they either open too much or close too easily. The hinge mechanism according to the invention locks the device in the open position, from which it does not open further even by using more force. Closing takes place using little force, whereby the amount of the force required is easy to adjust by altering the shape of the hinge pins. The hinge pin is divided into two parts (10a, 10b). The first hinge pin (10a) is locked in axial transition to the first hinge lug (8a), and the second hinge pin (10b) is locked into the second lug (8b) correspondingly. One end surface of the hinge pin has ridges (12a, 12b), and the other end surface has corresponding slots (11a, 11b). In the open position of the device the ridges and slots are matching.