Abstract: An upright keyboard musical instrument has an open/close board attached to the top position of a case, wherein the lower surface of the open/close board is subjected to mirror surface finishing and is supported by a lid prop, which is rotatably arranged in proximity to the top board to rotate about a support axis and is formed in an L-shape to have a plurality of support surfaces, realizing different angles for the open/close board being opened. The mirror surface of the open/close board projects images representing internal members of the case, such as an emblem and actions. By appropriately rotating the lid prop, it is possible to realize a desired angle for the open/close board, thus realizing tone volume control and visually entertaining effects in musical performance.

Abstract: A speaker edge is made of a thermosetting composition consisting of a polyurethane prepolymer and an inactivated solid polyamine as a latent hardener. A gas is dispersed in the thermosetting composition, prior to feed into a mold, so that it can foam and solidify to give the speaker edge. In a method of making the speaker edge, the composition will be injected into a female mold segment heated below the critical thermosetting temperature, foaming the composition. Then placed in the female segment is a male segment heated above the critical temperature, causing the ingredients to react with each other to solidify in the mold.

Abstract: A keyboard musical instrument includes a keyboard, key action mechanisms and hammer assemblies as similar to an acoustic piano; however, strings are replaced with a beaten member so that a player practices a fingering on the keyboard without an acoustic sound; each of the hammer assemblies has a cylindrical hammer head formed of metal or synthetic rubber/synthetic resin, and no twisting moment is exerted on the hammer shank regardless of relative angular position between the hammer head and the hammer shank.

Abstract: A keyboard musical instrument includes: a keyboard; an acoustic musical tone production mechanism for generating an acoustic musical tone; a tone generator for generating an electronic musical tone; a solenoid driver for inhibiting generation of the acoustic musical tone from the acoustic musical tone production mechanism; and an operation panel for designating a musical tone to be inhibited. When a player designates a musical tone to be inhibited via the operation panel in advance and then depresses a key on the keyboard, the generation of the acoustic musical tone is inhibited by means of the solenoid driver.