An input device with an adjustable force level is provided. The input device includes a circuit board and a key structure. The key structure includes a key body, a casing and a pressure-adjustable elastic receptacle. The pressure-adjustable elastic receptacle is partially or completely accommodated within the casing and sustaining the key body. When the key body is moved downwardly, a resisting force to resist the key body is provided by the pressure-adjustable elastic receptacle and the force level of the resisting force is adjusted by the user. When a force with the force level is applied to the key body by the user, a switch of the circuit board is triggered.

An input device includes at least one key structure and a film circuit board disposed below the key structure. The key structure includes a top cover, a plunger, a sleeve, a rod, a first elastic element, a second elastic element and a bottom cover. The plunger is assembled on the top cover and has a protruding portion protruding from a first opening of the top cover and a guiding portion. The sleeve is assembled inside the plunger. The rod is movably disposed in the sleeve. The first elastic element is disposed in the rod, wherein the guiding portion passes through the first elastic element so that a first end of the first elastic element leans against the plunger. The bottom cover having a second opening locks the top cover. A second end and a third end of the second elastic element respectively lean against the sleeve and the bottom cover.

Problem To maintain a low internal resistance value and adjust spring characteristics by using a movable contact made of a multilayered material. Means for Solving Problem A thermosensitive pellet-type thermal fuse includes, in an interior of a cylindrical case having electrical conductivity, a thermosensitive pellet that melts or softens at a temperature, a strong compression spring configured to press the thermosensitive pellet, an insulating cover closing the cylindrical case, a weak compression spring abutting against the insulating cover, a first lead extending through the insulating cover and including an inner end as a fixed contact, a movable contact electrically connecting to the first lead and the cylindrical case, a sealing resin provided surrounding a portion of the first lead and covering an outer end portion of the insulating cover, and sealing an open end portion of the cylindrical case, and a second lead disposed at one end of the cylindrical case. The movable contact includes a conductive base material and a conductive member covering a predetermined surface of the conductive base material. The conductive member is provided to contact portions with the fixed contact and an inner wall surface of the cylindrical case, and is made of a material having a Young's modulus and a rigidity different from those of the conductive base material.