A stopper rail of a silent piano, which can make collision noise generated when a hammer shank collides against the stopper rail, blurred in the sense of pitch thereof and difficult to be recognized by the human ear, in a silent performance mode. In this mode, the stopper rail is contacted by the hammer shank of a hammer being pivotally moved to stop pivotal movement of the hammer. The stopper rail includes a rail body having a predetermined flexural rigidity allowing vibration, a first cushion provided on one surface of the hammer shank, for being contacted by the hammer shank being pivotally moved, and a vibration suppressing portion provided on an opposite surface of: the rail body to the first surface so as to apply a load to the rail body to suppress vibration of the rail body when the hammer shank contacts the rail body.

A pressing surface of a hammer and a to-be-pressed surface of a key switch have relatively-concaved shapes in a longitudinal direction of the hammer. When a switch body is pressed by the hammer, an inclination caused by an overall curvature of the switch body that results from the fact that the switch body is pressed by the hammer from an oblique direction is canceled by an inclination of the switch body caused by partial compression and deformation that results from the relatively-concaved shapes, so that movable contacts in the switch body frontally face stationary contacts and come into contact with the stationary contacts, respectively.

A pressing surface of a hammer and a to-be-pressed surface of a key switch have relatively-concaved shapes in a longitudinal direction of the hammer. When a switch body is pressed by the hammer, an inclination caused by an overall curvature of the switch body that results from the fact that the switch body is pressed by the hammer from an oblique direction is canceled by an inclination of the switch body caused by partial compression and deformation that results from the relatively-concaved shapes, so that movable contacts in the switch body frontally face stationary contacts and come into contact with the stationary contacts, respectively.

A keyboard device includes: a frame; a plurality of keys including a first key and a second key, the plurality of keys rotating around the frame; and a plurality of guides for restricting an operation of each of the plurality of keys, at positions different in a vertical direction, each of the plurality of guides including a first member that is softer than the frame and the plurality of keys, and a second member that is harder than the first member, wherein each of the plurality of guides is in a first state where a corresponding one of the keys comes into contact with the first member, or in a second state where the corresponding one of the keys comes into contact with the second member.

A sensor includes: an upper electrode; a lower electrode provided facing the upper electrode; an upper electrode support portion provided in an upper portion of the upper electrode; a deforming portion provided at both ends of the upper electrode support portion and enabling a distance between the upper electrode and the lower electrode to be changed; a rotatable actuator arranged facing the upper electrode support portion; and a member arranged between the upper electrode support portion and the actuator, and capable of moving relative to at least one of the actuator and the upper electrode support portion when the actuator presses the upper electrode support portion.

A relationship of 0<.sub.1<2.sub.1 is satisfied, where .sub.1 is an angle formed between a first line which is vertical to a parallel line passing through a pivot center point and being parallel to a pivot extending direction, passes through a center point of a first portion from the center point of the first portion toward the parallel line, and a second line which is vertical, at the center point of the first portion, to a first portion extending direction, passes through the center point of the first portion toward a vertical line being vertical to the parallel line and passing through the pivot center point, and where .sub.1 is an angle formed between the first line and a third line connecting the pivot center point and the center point of the first portion from the center point of the first portion toward the pivot center point.

A relationship of 0<.sub.1<2.sub.1 is satisfied, where .sub.1 is an angle formed between a first line which is vertical to a parallel line passing through a pivot center point and being parallel to a pivot extending direction, passes through a center point of a first portion from the center point of the first portion toward the parallel line, and a second line which is vertical, at the center point of the first portion, to a first portion extending direction, passes through the center point of the first portion toward a vertical line being vertical to the parallel line and passing through the pivot center point, and where .sub.1 is an angle formed between the first line and a third line connecting the pivot center point and the center point of the first portion from the center point of the first portion toward the pivot center point.

A keyboard apparatus includes a first key assembly, a second key assembly, and a third key assembly. The first key assembly includes a first key being slidably in contact with a first member at a first position and a second member at a second position. A first minimum distance between the first key assembly and the second key assembly at the rear ends thereof is larger than a second minimum distance between the first key assembly and the second key assembly at the second position within a range of rotation of the first key assembly. A third minimum distance between the first key assembly and the third key assembly at the rear ends thereof being larger than a fourth minimum distance between the first key assembly and the third key assembly at the second position within the range of rotation of the first key assembly.

A keyboard apparatus includes a first key assembly, a second key assembly, and a third key assembly. The first key assembly includes a first key being slidably in contact with a first member at a first position and a second member at a second position. A first minimum distance between the first key assembly and the second key assembly at the rear ends thereof is larger than a second minimum distance between the first key assembly and the second key assembly at the second position within a range of rotation of the first key assembly. A third minimum distance between the first key assembly and the third key assembly at the rear ends thereof being larger than a fourth minimum distance between the first key assembly and the third key assembly at the second position within the range of rotation of the first key assembly.

A hammer assembly includes: a weight; and a pivot member including a first weight supporter configured to support the weight in a first direction, a second weight supporter configured to support the weight in a second direction opposite to the first direction, and a coupling portion configured to couple the first weight supporter and the second weight supporter to each other. A distance from the first weight supporter to the weight and a distance from the second weight supporter to the weight increase with decrease in distance to the coupling portion in at least a portion of a region of the weight.