Stroke adjustment device for keyboard instrument

Patent metadata

Field	Value
Publication number	US-10134371-B2
Application number	US-201715706459-A
Country	US
Kind code	B2
Filing date	Sep 15, 2017
Priority date	Sep 30, 2016
Publication date	Nov 20, 2018
Grant date	Nov 20, 2018

Abstract

A stroke adjustment device for a keyboard instrument, which can finely adjust key depression stroke and hammer stroke to obtain sufficient controllability of weak tones during musical performance and make the dynamic range even wider. This device includes a lifting mechanism for lifting up and down a keyboard pillow on which rear ends of keys are placed, an operation mechanism manually operated for driving the lifting mechanism, and a driving force transmission mechanism for transmitting a driving force generated by operation of the operation mechanism to the lifting mechanism. The lifting mechanism has a rotating shaft body rotatably provided below the keyboard pillow, vertically movable rack parts in mesh with gear portions that rotate in unison with the rotating shaft, and a lifting part extending over the rack parts and vertically moving in unison with the rack parts to lift up and down the keyboard pillow.

First claim

What is claimed is:

1. A stroke adjustment device for a keyboard instrument including a keyboard having a plurality of keys arranged side by side in a left-right direction thereof, each extending in a front-rear direction thereof and configured to be swingable about a pivot provided in the vicinity of a center of the key in a longitudinal direction thereof, a plurality of actions each placed on an upper surface of an associated one of the keys at a location rearward of the pivot and configured to move in accordance with key depression of the associated key, and a plurality of hammers provided in association with the respective actions and each configured to pivotally move in accordance with motion of an associated one of the actions to thereby strike a stretched string, the stroke adjustment device being configured to adjust a keyboard pillow which extends along the left-right direction of the keyboard and on which rear ends of the keys in a key-released state are placed, to a predetermined level to thereby adjust a key depression stroke of the keys and a hammer stroke of the hammers,
the stroke adjustment device comprising:
a keyboard pillow-lifting mechanism configured to lift up and down the keyboard pillow between a predetermined reference level and a pushed-up level higher than the predetermined reference level by a predetermined height;
an operation mechanism configured to be manually operated so as to drive the keyboard pillow-lifting mechanism; and
a driving force transmission mechanism configured to transmit a driving force generated by operation of the operation mechanism to the keyboard pillow-lifting mechanism,
wherein the keyboard pillow-lifting mechanism comprises:
a rotatable shaft extending below the keyboard pillow along the entire length of the keyboard pillow, the rotable shaft being connected to the driving force transmission mechanism;
a plurality of gear portions provided on the rotatable shaft at respective predetermined locations in a longitudinal direction of the rotable shaft and configured to rotate in unison with the rotable shaft;
a plurality of rack parts that are in mesh with the respective gear portions and are vertically movable; and
a lifting part extending over the rack parts, and in contact with a lower surface of the keyboard pillow, the lifting part being configured to vertically move in unison with the rack parts in accordance with rotation of the rotatable shaft through a predetermined angle to lift up and down the keyboard pillow.

2. The stroke adjustment device according to claim 1 , wherein the operation mechanism comprises:
a rotary operation part provided on a lower surface side of a keybed of the keyboard instrument in a manner rotatable about a vertically extending axis,
a gear portion formed on an outer peripheral surface of the rotary operation part, and
a rack slider provided on the lower surface side of the keybed in a horizontally slidable manner and being in mesh with the gear portion of the rotary operation part, and
wherein the driving force transmission mechanism comprises:
an outer portion having a tube shape and disposed in a manner extending between the operation mechanism and the keyboard pillow-lifting mechanism, and
an inner portion having a wire shape and slidably accommodated in the outer portion, with one end connected to the rack slider and another end connected to a hook provided on the rotating shaft in a radially protruding manner.

3. The stroke adjustment device according to claim 2 , further comprising a lock mechanism for locking the rotating shaft at a plurality of rotation angles so as to set the keyboard pillow at a plurality of levels,
wherein the lock mechanism comprises:
a lock bar extending over a predetermined length in a radial direction of the rotary operation part and having a base end thereof secured to the rotary operation part,
a ball latch provided at a tip end of the lock bar and having a ball that can project and retract, and
a lock member having a plurality of engagement recesses arranged along a passage trajectory of the tip end of the lock bar in a manner spaced from each other, and each formed such that the ball can be engaged therewith and disengaged therefrom, the lock member being configured to immovably lock the rotating shaft by engagement of the ball with any one of the engagement recesses according to a rotating operation of the rotary operation part.

Assignees

• Kk Kawai Gakki Seisakusho

Inventors

• Higasa Hirotaka

Classifications

• G10C3/04

  Frames; Bridges; Bars · CPC title

• G10C3/225

  Physics · mapped topic

• G10C3/12 Primary

  Keyboards; Keys · CPC title

• G10C9/00

  Methods, tools or materials specially adapted for the manufacture or maintenance of musical instruments covered by this subclass · CPC title

• G10C3/23

  with hammers mounted above the strings, striking downwards · CPC title