Keyboard device for keyboard musical instrument

A keyboard device for a keyboard musical instrument, comprising:

• a key which extends by a predetermined length in a front-rear direction and is swingable with a vicinity of a center in a length direction as a fulcrum;
• an action unit which is provided at a rear portion of the key and executes a predetermined action in conjunction with key depression of the key;
• a hammer support which is disposed on a rear side of the key;
• and
• a hammer which extends by a predetermined length in the front-rear direction, is turnably supported at a rear end portion via a hammer support shaft extending in a right-left direction of the hammer support, is placed on the action unit via a hammer protrusion portion provided so as to protrude downward immediately on a front side of the hammer support shaft, and is driven upward via the action unit along with the key depression of the key, wherein
• the action unit includes
• a holder which is fixed to a rear end portion of the key,
• a repetition lever which is formed to have a predetermined shape extending in the front-rear direction, is turnably attached to the holder, places the hammer protrusion portion on an upper surface provided with a jack guide hole penetrating in an up-down direction and extending in the front-rear direction, and pushes up the hammer via the hammer protrusion portion to turn the hammer upward by moving upward along with the key depression of the key,
• a repetition spring which biases the repetition lever to return the repetition lever to an original position in a key release state,
• a jack which includes a hammer push-up portion extending in the up-down direction and a rear arm extending rearward from a vicinity of a lower end of the hammer push-up portion, and is turnably attached to the holder, and in which an upper end portion of the hammer push-up portion is inserted into the jack guide hole of the repetition lever from below and engaged with the jack guide hole of the repetition lever to be movable in the front-rear direction, and which pushes up the hammer via the hammer protrusion portion by the hammer push-up portion in a middle of upward moving of the repetition lever along with the key depression of the key to turn the hammer upward, and
• a jack spring which biases the jack so as to return the jack to an original position in the key release state,
• the hammer support includes
• a repetition stopper which stops the repetition lever as a rear end portion of the repetition lever abuts on the repetition stopper from below while the repetition lever is pushing up the hammer, and
• a jack stopper which stops the jack as a rear end portion of the rear arm abuts on the jack stopper from below while the jack is pushing up the hammer, and turns the jack with the rear end portion of the rear arm that has abutted as a fulcrum to cause the hammer push-up portion of the jack to come out of the hammer protrusion portion of the hammer,
• a spring constant of the jack spring has a predetermined spring constant, and
• a spring constant of the repetition spring is set to be higher than the spring constant of the jack spring.