| 摘要 |
PROBLEM TO BE SOLVED: To provide a key switch device capable of adequately detecting a user's operation of the key top. SOLUTION: Four protrusions 18a to 18d in touch with the lower brim 43 of the opening 42 are provided around the outer circumference of the trunk 14 to be unitized with the trunk 14 and the guard 15. Also, these protrusions 18a to 18d are installed at an intermediate position of the two compression parts adjacent to each other on the plan view, namely at the points of approximately 45 deg. deviating from the compression parts 12a to 12d. When the compression part 12a is depressed, the compression part 12c facing the depressed compression part 12a across the center A1 of the operating face (prescribed circumference C1) and the two protrusions 18b, 18c located between the compression parts 12b and 12d adjacent to both sides of the compression part 12a, abut on the lower brim of the opening of the case itself. Just at this point where the two protrusions 18b, 18c abut on the lower brim of the opening, the swinging fulcrum F1 of the key top 11 is formed.
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