Touch pad input device

1. A touch pad input device comprising:

a movable element having an upper surface that serves as an operation surface;

first sensor that senses a touch or proximity of an operating object on or to the operation surface;

a stationary element disposed under the movable element;

a rotation support mechanism rotatably supporting the movable element;

second sensor that senses rotation of the movable element; and

a retaining mechanism that retains the movable element,

wherein the rotation support mechanism includes

a fulcrum portion arranged on one of the movable element and the stationary element, the fulcrum portion being positioned under the movable element in an area covered by the operation surface when viewed from above, and

an abutment portion arranged on the other one of the movable element and the stationary element so as to contact with the fulcrum portion,

wherein the retaining mechanism is positioned under the movable element in the area covered by the operation surface when viewed from above, and

wherein the retaining mechanism urges the movable element downward to hold the fulcrum portion in pressure contact with the abutment portion.

2. The device according to claim 1 ,

wherein the stationary element has an opening at a predetermined position, the opening extending through the stationary element from an upper surface of the stationary element to a lower surface thereof at a predetermined position, and

wherein the retaining mechanism urges the movable element from under the stationary element through the opening.

3. The device according to claim 2 ,

wherein the retaining mechanism includes

a protrusion fastened to a lower surface of the movable element, the protrusion extending through the opening beyond the lower surface of the stationary element,

a screw member screwed on a lower end of the protrusion, the screw member including a head wider than the protrusion, and

an elastic member interposed between the stationary element and the head of the screw member, the elastic member elastically urging the protrusion downward.

4. The device according to claim 2 ,

wherein the retaining mechanism includes

a screw member extending from under the stationary element through the opening and being screwed on the movable element, and

an elastic member elastically urging the movable element downward,

wherein the screw member includes

a stem extending through the opening beyond the upper surface of the stationary element, and

a head wider than the stem, and

wherein the elastic member is interposed between the stationary element and the head of the screw member.

5. The device according to claim 1 , wherein the fulcrum portions are arranged on an axis of rotation of the movable element on opposite sides of the retaining mechanism.

6. The device according to claim 1 , wherein the fulcrum portions are downwardly projecting ridges formed by partly bending the movable element along an axis of rotation of the movable element.

7. The device according to claim 1 , wherein the fulcrum portions are upwardly projecting ridge formed by partly bending the stationary element along an axis of rotation of the movable element.