Abstract: A keyboard, having a plurality of keys arranged so as to be pivotable upward and downward and a plurality of light emitters arranged under the keys in one-to-one correspondence therewith, selectively causes the light emitters to emit light, thereby teaching keys to be depressed. A base resin, which forms each of the plurality of keys, has transparency and contains a pigment which colors the base resin and a light scattering agent having a light diffusion property. By virtue of the use of the pigment and the light scattering agent, a surface color which confers a refined feature on the keys can be realized, and accordingly a product with an excellent appearance can be attained. Moreover, by virtue of the blending of the pigment and the light scattering agent, the keys can shine uniformly without a difference in brightness when their corresponding light emitters are lighted, and a keyboard instrument player can fully recognize by his/her eyes that the keys shine.

Abstract: A thermoforming machine for thermoforming thermoplastic sheets wherein molding dies are used to apply pressure to a sheet to be thermoformed. A rectangular carriage carries a frame adapted to clamp the peripheral edge of a thermoforming thermoplastic sheet. One side of the frame that is positioned downstream of the carriage is adapted to open so as to have the carriage pass through the molding dies. The carriage is removed from the sheets so as to be pulled back upstream of the molding dies while the operation of the molding dies is carried out for the sheet. The fully pulled back carriage can be used for the following sheet.

Abstract: A device for removing foreign material from sand is disclosed. The device includes a rotary box which is driven such that sand is centrifuged therein. The box includes a circular bottom plate, a circumferential and inclined wall extending from the circular end of the bottom place, upwardly and outwardly, and ring portion which extends inwardly from the top of the inclined wall. A plurality of rollers are disposed in the box, each roller having a movable surface substantially parallel to and spaced apart from the circumferential and inclined wall of the box. Sand in the rotary box is centrifuged and circumferentially deposited on the inclined wall to form a sand layer which becomes progressively thicker and then contact the movable surface, subjecting the sand to shearing and compressive forces. Processed sand then overflows from the ring portion of the rotary box.