1. Field of the Invention
The present invention relates to a keyboard device for an electronic keyboard instrument including swingable keys and a hammer device having hammers each of which pivotally moves by being pushed up by a depressed key.
2. Description of the Related Art
Conventionally, as a hammer device for an electronic keyboard instrument, there has been known one disclosed e.g. in Japanese Patent Publication No. 3270693. The electronic keyboard instrument includes a chassis, a plurality of swingable keys provided on the chassis, wippens provided for the respective keys, and a center rail having the hammer device mounted thereon. The hammer device includes a plurality of hammers each made of a synthetic resin. The hammers are arranged side by side in association with the respective keys. Each of the hammers has a front end thereof integrally formed with a pivotal shaft.
On the other hand, the center rail has a bearing member and a bearing member fixing plate, and the bearing member is formed with a U-shaped hole. The bearing member fixing plate is secured to the bearing member with screws with the pivotal shaft of each hammer fitted in the hole of the bearing member, whereby the hammer is supported by the bearing member and the bearing member fixing plate such that the hammer can pivotally move about the pivotal shaft. In this electronic keyboard instrument, when one of the keys is depressed, a wippen associated with the depressed key pivotally moves, and an associated hammer pivotally moves in accordance with the pivotal movement of the wippen.
Further, as a keyboard device for an electronic keyboard instrument of the above-mentioned type, there has also been known one disclosed in Japanese Patent Publication No. 3591579. This keyboard device includes swingable keys, pivotally movable hammers, and switches for detecting key depression information on the respective keys, and each hammer has a capstan screw screwed therein. The hammer is placed on an associated one of the keys via the capstan screw. When depressed, the key pushes up the hammer via the capstan screw. As a consequence, the hammer pivotally moves to press the switch, whereby key depression information is detected and a musical tone is generated based on the detected key depression information. The angle of the capstan screw, as viewed laterally, with respect to a vertical direction is set to be larger in a fully depressed state of the key (i.e. in a state where a key depression has been completed) than when the key is in a key-released state.
According to the hammer device for an electronic keyboard instrument disclosed in Japanese Patent Publication No. 3270693, the hammer is made of a synthetic resin, and therefore, in the case of manufacturing the hammer e.g. by injection molding, it is required to use two molds B1 and B2 such that the center of a hammer pivot shaft A1 is positioned on a parting line between the molds B1 and B2, as shown in FIG. 16. In this case, there is a fear that parting line marks and molding burrs are generated on the outer peripheral surface of the pivot shaft A1.
If the hammer is used with the above-mentioned parting line marks and molding burrs left on the pivot shaft A1, the parting line marks and the molding burrs will interfere with the inner peripheral surface of the hole of the bearing member during pivotal movement of the hammer, which hinders smooth pivotal movement of the hammer. For this reason, it is required to perform cutting during manufacturing of the hammer so as to remove the parting line marks and the molding burrs, which increases the number of manufacturing steps and manufacturing costs.
Further, in the hammer device disclosed in Japanese Patent Publication No. 3270693, each hammer is supported by the bearing member and the bearing member fixing plate fixed to the bearing member with screws, so that when removing a hammer from the center rail and mounting the hammer to the center rail e.g. for maintenance, it is required to carry out screw-out and screw-in operations, which causes degradation of workability.
On the other hand, in a keyboard device of the type disclosed in Japanese Patent Publication No. 3591579, since the tone volume of a musical tone is controlled according to the pivotal speed of a hammer that presses the switch, it is preferred that the pivotal speed of each hammer can be finely adjusted so as to achieve musical performance rich in expression. For example, a weak tone, such as a pianissimo tone, can be obtained by temporarily causing a hammer to pivotally move to a location close to the switch and then further pivotally moving the hammer from this state to thereby reduce the pivotal speed of the hammer when the hammer presses the switch.
Further, to make it easy for a player to adjust the pivotal speed of a hammer so as to ensure excellent musical performance capability of the keyboard device, it is important to set the touch weight (load applied on a player's finger) of each key to an appropriate magnitude. In particular, in order to obtain an appropriate weak tone, it is important to appropriately set a touch weight occurring when an associated hammer having pivotally moved close to the switch is further pivotally moved, i.e. a touch weight immediately before termination of a key depression. The hammer is placed on the key via the capstan screw, so that the touch weight is determined by a reaction force of the hammer acting on the key via the capstan screw, and other factors. The hammer reaction force is generated by the weight of the hammer itself, and basically acts vertically.
In the keyboard device disclosed in Japanese Patent Publication No. 3591579, the angle of the capstan screw with respect to the vertical direction is set to be larger in the state where a key depression has been completed than when the key is in the key-released state. For this reason, a force component, which acts in a direction perpendicular to the axis of the capstan screw, of the reaction force of the hammer which acts vertically, is increased immediately before termination of a key depression, which hinders appropriate transmission of the reaction force of the hammer to the key via the capstan screw, resulting in reduction of touch weight. In the conventional keyboard device, the touch weight thus provided immediately before termination of a key depression becomes insufficient, so that it is impossible to appropriately adjust the pivotal speed of the hammer, and in turn impossible to provide excellent musical performance capability.