KEYBOARD DEVICE FOR KEYBOARD INSTRUMENT

Abstract

A keyboard device for a keyboard instrument, which is capable of obtaining excellent touch feeling when key depression is performed and further is capable of increasing responsiveness when a key having been depressed performs pivotal return movement to its original position and thereby obtaining appropriate string striking repeatability. The keyboard device includes a keyboard chassis, a key disposed on the keyboard chassis, and a key support mechanism causing, upon depression of the key, the depressed key to operate such that the key pivotally moves about a virtual pivot located rearward of a rear end of the key. The key support mechanism includes a first arm swingably engaged with a first pivot shaft and a second arm swingably engaged with a second pivot shaft. The second arm is provided with a second arm weight made of a material having a larger specific gravity than the second arm.

Claims

1. A keyboard device for a keyboard instrument, comprising: a keyboard chassis; a key extending a predetermined length in a front-rear direction and disposed on the keyboard chassis; and a key support mechanism engaged with the keyboard chassis and provided so as to support the key from below, the key support mechanism causing, upon depression of the key, the depressed key to operate such that the key pivotally moves about a virtual pivot located rearward of a rear end of the key, wherein the key support mechanism includes: a first arm configured to extend a predetermined length in the front-rear direction and be swingably engaged with a first pivot shaft provided on the keyboard chassis, the first arm having a front end pivotally and slidably connected to a front portion of the key; and a second arm configured to extend a predetermined length in the front-rear direction and be swingably engaged with a second pivot shaft provided on the keyboard chassis at a location rearward of the first pivot shaft, the second arm having a rear end pivotally connected to a rear portion of the key, and including a second arm front-side connecting portion which is disposed forward of the second pivot shaft and is pivotally and slidably connected to a first arm rear-side connecting portion rearward of the first pivot shaft of the first arm, and wherein the second arm is provided with a second arm weight that is made of a material having a larger specific gravity than the second arm.

2. The keyboard device according to claim 1, wherein the second arm weight is provided forward of the second pivot shaft and/or around the second pivot shaft.

3. The keyboard device according to claim 1, wherein the second arm weight is mounted on at least one of left and right sides of the second arm.

4. The keyboard device according to claim 1, wherein the second arm includes a weight accommodating portion extending therethrough in a left-right direction, and wherein the second arm weight is mounted in the second arm in a state accommodated in the weight accommodating portion by being inserted into the weight accommodating portion from outside.

5. The keyboard device according to claim 4, wherein the second arm weight is accommodated in the weight accommodating portion in a state in which an outside of the second arm weight is covered with a predetermined synthetic resin.

6. The keyboard device according to claim 1, wherein the second arm is manufactured by molding a synthetic resin, and when the second arm is molded, the second arm is integrally formed with the second arm weight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIGS. 1A and 1B are perspective views of a part (one octave section) of a keyboard device for an electronic piano to which the present invention is applied, in which FIG. 1A shows the appearance of the keyboard device and FIG. 1B shows a state in which keys other than a white key and a black key at a left end of the keyboard device are omitted;

[0022] FIG. 2 is a perspective view of the keyboard device shown in FIG. 1B in a state in which the white key and the black key are removed, together with respective key support mechanisms therefor, from a keyboard chassis;

[0023] FIG. 3A is a plan view of the keyboard device from which the keys other than the white key and the black key at the left end of the keyboard device are omitted and FIG. 3B is a cross-sectional view taken along line A-A of FIG. 3A;

[0024] FIGS. 4A and 4B are perspective views of the white key and the key support mechanism therefor, in which FIG. 4A shows the white key and the key support mechanism in a connected state and FIG. 4B shows the white key and the key support mechanism in an exploded state;

[0025] FIGS. 5A and 5B are perspective views of the black key and the key support mechanism therefor, in which FIG. 5A shows the black key and the key support mechanism in a connected state and FIG. 5B shows the black key and the key support mechanism in an exploded state;

[0026] FIGS. 6A and 6B are views useful in explaining operation of the white key in the keyboard device, in which FIG. 6A shows a key-released state and FIG. 6B shows a key-depressed state;

[0027] FIGS. 7A and 7B are views useful in explaining operation of the black key in the keyboard device, in which FIG. 7A shows a key-released state and FIG. 7B shows a key-depressed state;

[0028] FIGS. 8A to 8C are views of a second arm according to a first embodiment of the present invention, in which FIG. 8A is a perspective view, FIG. 8B is a side view, and FIG. 8C is an exploded perspective view showing a state in which second arm weights are removed from the second arm;

[0029] FIGS. 9A to 9C are views of a second arm according to a second embodiment of the present invention, in which FIG. 9A is a perspective view, FIG. 9B is a side view, and FIG. 9C is an exploded perspective view showing a state in which the second arm weights are removed from the second arm;

[0030] FIGS. 10A to 10C are views of a second arm according to a third embodiment of the present invention, in which FIG. 10A is a perspective view, FIG. 10B is a side view, and FIG. 10C is an exploded perspective view showing a state in which the second arm weights are removed from the second arm;

[0031] FIGS. 11A to 11C are views of a second arm according to a fourth embodiment of the present invention, in which FIG. 11A is a perspective view, FIG. 11B is an exploded perspective view showing a state in which the second arm weights are removed from the second arm, and FIG. 11C is a perspective view showing a state in which the second arm weight is separated into a weight body and a weight cover; and

[0032] FIGS. 12A and 12B are views of a second arm according to a fifth embodiment of the present invention, in which FIG. 12A is a perspective view, and FIG. 12B is a side view.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0033] The present invention will now be described in detail with reference to the drawings showing preferred embodiments thereof. FIG. 1A shows only one octave section of a keyboard device 1 for an electronic piano to which the present invention is applied. Note that in the following, a description will be first given of the basic construction of the keyboard device 1 and operation thereof, and then of an essential part of the present invention.

[0034] FIG. 1B shows a state of the keyboard device 1 shown in FIG. 1A, in which keys 2 other than a white key 2a and a black key 2b at the left end of the keyboard device 1 are omitted. FIG. 2 shows a state of the keyboard device 1 shown in FIG. 1B, in which the white key 2a and the black key 2b are removed, together with respective key support mechanisms 6 therefor, from a keyboard chassis 4.

[0035] This keyboard device 1 is comprised of the keyboard chassis 4, the plurality of keys 2 including the white keys 2a and the black keys 2b and disposed in a side-by-side arrangement in a left-right direction, the key support mechanisms 6 each pivotally mounted on the keyboard chassis 4 for each key, for supporting an associated one of the keys 2 from below, and key switches 3 each for detecting key depression information of an associated one of the keys 2.

[0036] The keyboard chassis 4 includes a chassis body 4a formed as a resin molded article which is made e.g. by injection molding of a predetermined resin material (e.g. an ABS resin) into a predetermined shape. As shown in FIGS. 3A and 3B, the chassis body 4a has a front portion 11, an intermediate portion 12, and a rear portion 13, each extending in the left-right direction (in a left-right direction in FIG. 3A) as a whole. The front portion 11, the intermediate portion 12, and the rear portion 13 are integrally formed with each other via a plurality of ribs 14 disposed with a spacing therebetween in the left-right direction and each extending in the front-rear direction. Note that in the following description, the front portion 11, the intermediate portion 12, and the rear portion 13 of the chassis body 4a of the keyboard chassis 4 will be referred to as the chassis front 11, the chassis intermediate 12, and the chassis rear 13, respectively.

[0037] The chassis front 11 is mainly for guiding the white key 2a during depression thereof and restricting the upper limit position and the lower limit position of a front end of the white key 2a. On the chassis front 11, there are erected a plurality of white key guides 11a, each of which is inserted into each associated one of the white keys 2a from below so as to prevent lateral swing of the white key 2a, in a state arranged side by side in the left-right direction. Further, the chassis front 11 has engagement holes 11b and 11b, vertically extending therethrough, which are formed on the left and right sides of each of the white key guides 11a, respectively. A pair of left and right upper limit position regulation portions 21 and 21, referred to hereinafter, of the white key 2a are engaged with the respective engagement holes 11b and 11b in a state inserted therethrough. Furthermore, the chassis front 11 has a front end thereof formed with a stopper-mounting portion 11c that protrudes forward and extends along the entirety of the chassis body 4a in the left-right direction. A key upper limit stopper 16a and a key lower limit stopper 16b for the white key 2a are mounted on a lower surface and an upper surface of the stopper-mounting portion 11c, respectively, such that they extend in the left-right direction. Note that a stopper-mounting portion 11d for the black key, which extends along the entirety of the chassis body 4a in the left-right direction, is provided at a predetermined location of the chassis front 11, rearward of each white key guide 11a, and that a key upper limit stopper 17 for the black key is mounted on the stopper-mounting portion 11d such that it extends in the left-right direction.

[0038] The chassis intermediate 12 is mainly for guiding the black key 2b during depression thereof and swingably supporting a first arm 31 and a second arm 32, described hereinafter, of each of a white key-associated key support mechanism 6a and a black key-associated key support mechanism 6b. The chassis intermediate 12 has a flat portion 12a in the form of a flat plate extending in the left-right direction, and a plurality of black key guides 12b erected on the flat portion 12a and disposed with an appropriate spacing therebetween in the left-right direction. Each black key guide 12b is inserted into an associated one of the black keys 2b from below to prevent lateral swing of the black key 2b. Further, the chassis intermediate 12 has a front portion thereof provided with a first arm support portion 18 for supporting the first arms 31 of the key support mechanisms 6. The first arm support portion 18 has a plurality of first pivot shafts 18a each of which is provided between each adjacent two of the ribs 14 and 14 such that the first pivot shaft 18a extends in the left-right direction. The first arms 31 are swingably supported on associated ones of the first pivot shafts 18a. Furthermore, the chassis intermediate 12 has a rear portion thereof provided with a second arm support portion 19 for supporting the second arms 32 of the key support mechanisms 6. The second arm support portion 19 has a plurality of second pivot shafts 19a each of which is provided between each adjacent two of the ribs 14 and 14 such that the second pivot shaft 19a extends in the left-right direction. The plurality of second pivot shafts 19a are arranged on the same axis extending in the left-right direction at a location rearward of and higher than the first pivot shafts 18a, and the second arms 32 are swingably supported on associated ones of the second pivot shafts 19a. Note that a first arm lower limit stopper 10b extending along the entirety of the chassis body 4a in the left-right direction is provided at a predetermined location of a middle rail 8, referred to hereinafter, disposed below the chassis intermediate 12.

[0039] Further, the above-mentioned key switches 3 are provided on a lower portion of the keyboard chassis 4 between the above-described chassis front 11 and chassis intermediate 12. The key switches 3 are formed by a laterally elongated printed circuit board 3a extending in the left-right direction, and a plurality of switch bodies 3b formed by rubber switches attached to the printed circuit board 3a on a key-by-key basis, for being pressed by associated ones of the first arms 31 upon key depression.

[0040] The chassis rear 13 is mainly for guiding the keys 2 by their rear ends in the vertical direction while preventing lateral swing of the keys 2 and for restricting the upper limit positions of the rear ends of associated ones of the first arms 31. As shown in FIGS. 2 and 3A, the chassis rear 13 has a plurality of partition walls 13a formed with a predetermined spacing therebetween in the left-right direction so as to separate each adjacent two of the keys 2 and 2 from each other. Further, as shown in FIG. 3B, a first arm upper limit stopper 10a extending along the entirety of the chassis body 4a in the left-right direction is provided at a predetermined location of an upper portion of the chassis rear 13. The first arm upper limit stopper 10a and the first arm lower limit stopper 10b provided on the chassis intermediate 12 are for restricting the upper limit position and the lower limit position of the first arm 31, respectively, when the first arm 31 having a function as a hammer for adding a touch weight to the key 2 pivotally moves upward and downward. Furthermore, a metal cover plate 15 extending in the left-right direction along the entirety of the chassis body 4a and disposed to cover the rear ends of the keys 2 is mounted on the upper portion of the chassis rear 13.

[0041] As shown in FIGS. 2 and 3A, the chassis body 4a of the keyboard chassis 4 constructed as described above is formed with a plurality of first openings 5a open upward and forward and a plurality of second openings 5b open upward. The first arms 31 of the key support mechanisms 6 are engaged with associated ones of the first pivot shafts 18a from outside via the above-mentioned first openings 5a, respectively. Further, the second arms 32 are engaged with associated ones of the second pivot shafts 19a from outside via the above-mentioned second openings 5b, respectively.

[0042] Further, in the above-described keyboard chassis 4, a plurality of chassis bodies 4a are connected to each other in a state arranged side by side in the left-right direction, and are each screwed to a front rail 7, the middle rail 8, and a rear rail 9, each made of metal, in a state placed thereon, the rails 7, 8 and 9 each extending in the left-right direction and arranged with a predetermined spacing therebetween in the front-rear direction. The keyboard chassis 4 is fixed to a keybed, not shown, of the electronic piano via the front rail 7 and the rear rail 9.

[0043] Next, the keys 2 and the key support mechanisms 6 will be described. FIG. 4A shows the white key 2a and the key support mechanism 6a therefor on an enlarged scale, and FIG. 4B shows them in an exploded state. As shown in FIGS. 4A and 4B, the white key 2a is formed e.g. by injection molding of a predetermined resin material (e.g. an AS resin) into a hollow shape which extends a predetermined length in the front-rear direction and opens downward. The white key 2a has the front end thereof formed with the pair of left and right upper limit position regulation portions 21 and 21 which protrude downward from respective side walls of the front end of the white key 2a and each having a lower end thereof bent forward. As described hereinabove, the left and right upper limit position regulation portions 21 and 21 are engaged with the respective left and right engagement holes 11b and 11b of the chassis front 11 in a state inserted therethrough.

[0044] Further, at a predetermined location of a front portion of the white key 2a, rearward of the upper limit position regulation portions 21, there is formed a key front-side connecting portion 22 connected to the first arm 31 of the key support mechanism 6a. This key front-side connecting portion 22 includes a connecting recess 22a formed into a U shape having a slot-like shape in side view and open forward. Further, the connecting recess 22a has a cushioning member 20 attached thereto, which is formed to cover the whole inner peripheral surface of the connecting recess 22a, for suppressing generation of noise when a connecting shaft 35b, referred to hereinafter, of the first arm 31 slides in the inner peripheral surface of the connecting recess 22a.

[0045] Note that in the front portion of the white key 2a, between the above-mentioned upper limit position regulation portions 21 and key front-side connecting portion 22, there is mounted a key weight 30 (see FIG. 3B) for adding a desired touch weight to the white key 2a during depression thereof.

[0046] Furthermore, the white key 2a has a rear portion thereof provided with a key rear-side connecting portion 23 connected to the second arm 32 of the key support mechanism 6a. The key rear-side connecting portion 23 has a plate-like connecting body portion 23a which hangs downward from a laterally central portion of the white key 2a and has a predetermined thickness in the left-right direction, and a pair of left and right engagement protrusions 23b and 23b which coaxially protrude from the left and right sides of the connecting body portion 23a, respectively. Further, the rear portion of the white key 2a is formed with a tool insertion hole 24 which vertically extends through the rear portion, and is used to have a predetermined tool inserted therein from above for disconnecting the white key 2a from the second arm 32 of the key support mechanism 6a e.g. at the time of maintenance of the keyboard device 1.

[0047] On the other hand, the key support mechanism 6a includes the first arm 31 and the second arm 32 which are engaged with each other and are connected to the key front-side connecting portion 22 and the key rear-side connecting portion 23 of the white key 2a, respectively.

[0048] As shown in FIG. 4B, the first arm 31 is comprised of an arm body 33 and two weights 34 and 34 attached to the arm body 33. The arm body 33 is formed as a resin molded article which is made e.g. by injection molding of a predetermined resin material (e.g. polyacetal resin) into a predetermined shape. This arm body 33 extends a predetermined length in the front-rear direction, and has a front end thereof formed with a first arm front-side connecting portion 35 connected to the key front-side connecting portion 22 of the white key 2a. The first arm front-side connecting portion 35 includes a box portion 35a having a box-like shape open upward and forward, and the connecting shaft 35b provided such that it extends in the left-right direction in a state connecting the front-side upper ends of left and right side walls of the box portion 35a to each other. The connecting shaft 35b is connected to the connecting recess 22a of the key front-side connecting portion 22 of the white key 2a such that the connecting shaft 35b is pivotally movable and is slidable in the front-rear direction.

[0049] Further, the arm body 33 has a bearing portion 36 formed at a predetermined location immediately rearward of the first arm front-side connecting portion 35. The bearing portion 36 has an inverted U shape open downward in side view, and is pivotally engaged with the first pivot shaft 18a of the keyboard chassis 4. Furthermore, the arm body 33 has a first arm rear-side connecting portion 37 formed at a predetermined location rearward of the bearing portion 36, for connection to the second arm 32. Specifically, the first arm rear-side connecting portion 37 has a connecting shaft 37a which extends in the left-right direction with respective opposite ends thereof protruding outward from the left and right sides of the arm body 33. The opposite ends of the connecting shaft 37a are engaged with connecting recesses 45b and 45b of a second arm front-side connecting portion 45, referred to hereinafter, of the second arm 32.

[0050] The two weights 34 and 34 formed as elongated and narrow plates are mounted on a weight mounting portion 38, which is a rear portion of the arm body 33, in a state sandwiching the weight mounting portion 38. Note that each weight 34 is made of a material (metal such as iron) having a larger specific gravity than the arm body 33, and is formed e.g. by pressing a metal plate into a predetermined shape.

[0051] The second arm 32 is formed as a resin molded article having a predetermined shape by injection molding of the same resin material as that of the arm body 33 of the first arm 31. The second arm 32 is shorter than the first arm 31 and extends a predetermined length in the front-rear direction. Further, the second arm 32 has a bearing portion 41 having a C shape open forward in side view at about a longitudinal center thereof. The bearing portion 41 is pivotally engaged with an associated one of the second pivot shafts 19a of the keyboard chassis 4.

[0052] Further, the second arm 32 has a rear portion thereof provided with a second arm rear-side connecting portion 42 connected to the key rear-side connecting portion 23 of the white key 2a. The second arm rear-side connecting portion 42 is formed into a bifurcated shape, and has two left and right connecting arm portions 43 and 43 which extend a predetermined length parallel to each other along the longitudinal direction of the second arm 32. Each connecting arm portion 43 has a rear end thereof formed with a connecting hole 43a extending through the connecting arm portion 43 in the left-right direction. The two connecting arm portions 43 and 43 sandwich the connecting body portion 23a of the key rear-side connecting portion 23 of the white key 2a between the rear ends thereof from the left and the right, and each connecting hole 43a has an associated one of the engagement protrusions 23b of the key rear-side connecting portion 23 pivotally fitted therein.

[0053] Furthermore, the second arm 32 has a front portion thereof provided with the second arm front-side connecting portion 45 connected to the first arm rear-side connecting portion 37 of the first arm 31. The second arm front-side connecting portion 45 has a pair of left and right connecting portions 45a and 45a arranged with a predetermined spacing in the left-right direction. The connecting portions 45a and 45a are each formed with the connecting recess 45b which has a U shape having a slot-like shape in side view and open forward. The left and right connecting portions 45a and 45a of the second arm front-side connecting portion 45 are pivotally and slidably engaged with the respective opposite ends of the connecting shaft 37a of the first arm 31 via the connecting recesses 45b and 45b thereof.

[0054] FIG. 5A shows the black key 2b and the key support mechanism 6b therefor on an enlarged scale, and FIG. 5B shows the black key 2b and the key support mechanism 6b in an exploded state. The black key 2b is formed e.g. by injection molding of the same resin material as that of the white key 2a into a hollow shape which extends in the front-rear direction by a predetermined length shorter than that of the white key 2a and opens downward. The black key 2b has a front-side lower end thereof provided with a key front-side connecting portion 26 formed substantially similar to the key front-side connecting portion 22 of the white key 2a. This key front-side connecting portion 26 has a connecting recess 26a formed into a U shape having a slot-like shape in side view and open forward. Further, the key front-side connecting portion 26 has an extension portion 26b on a lower-side front end of the connecting recess 26a. The extension portion 26b extends a predetermined length forward of the front surface of the body of the black key 2b. This extension portion 26b functions as an upper limit position regulation portion of the black key 2b. Note that in the following description, the components of the black key 2b and the key support mechanism 6b having the same configurations as those of the above-described white key 2a and key support mechanism 6a are denoted by the same reference numerals and detailed description thereof will be omitted.

[0055] The key support mechanism 6b supporting the black key 2b is constructed substantially similar to the above-described white key-associated key support mechanism 6a. Specifically, the arm body 33 of the first arm 31 of the key support mechanism 6b and the second arm 32 of the same are constructed exactly similar in shape and size to the arm body 33 and the second arm 32 of the white key-associated key support mechanism 6a. Note that although in FIGS. 5A and 5B, the two left and right weights 34 and 34 of the key support mechanism 6b for the black key 2b are illustrated exactly the same as the weights 34 and 34 of the key support mechanism 6afor the white key 2a, the shapes and lengths of the weights 34 and 34 of the key support mechanisms 6a and 6b are changed as deemed appropriate according to touch weights required for the keys 2 or the like.

[0056] Next, a description will be given of the operation of the keys 2 and the key support mechanisms 6 of the keyboard device 1 constructed as described above. FIGS. 6A and 6B are views useful in explaining the operation of the white key 2a and the key support mechanism 6a associated therewith. FIGS. 7A and 7B are views useful in explaining the operation of the black key 2b and the key support mechanism 6b associated therewith.

[0057] When the front end of the white key 2a is depressed by a player with his/her finger from a key-released state shown in FIG. 6A, the key front-side connecting portion 22 of the white key 2a is moved downward, whereby the first arm 31 is pivotally moved in a counterclockwise direction about the first pivot shaft 18a. Further, in accordance with the pivotal movement of the first arm 31, the second arm front-side connecting portion 45, which is engaged with the connecting shaft 37a of the first arm 31 via the connecting recesses 45b and 45b, is moved upward. With this, the second arm 32 is pivotally moved in a clockwise direction about the second pivot shaft 19a. Then, in accordance with this pivotal movement of the second arm 32, the key rear-side connecting portion 23, which is connected to the second arm 32 via the second arm rear-side connecting portion 42 formed at the rear end of the second arm 32, is pulled down, whereby the rear end of the white key 2a is moved downward.

[0058] Note that during the above-mentioned pivotal movement of the first arm 31, the box portion 35a of the first arm front-side connecting portion 35 is moved downward, and accordingly, the switch body 3b of one of the key switches 3, which is associated with the depressed key 2, is pressed from above by the bottom wall of the box portion 35a. As a consequence, in the electronic piano, key depression information of the depressed key 2 is detected, and based on the detected key depression information, sound is generated from a speaker, not shown.

[0059] As described hereinabove, in the case where the white key 2a is depressed, in accordance with the counterclockwise pivotal movement of the first arm 31, the weight 34 of the first arm 31 is inclined such that the weight 34 becomes higher as it extends rearward, whereby the rear end of the weight 34 is brought into contact with the first arm upper limit stopper 10a from below, as shown in FIG. 6B. This prevents further pivotal movement of the first arm 31. When the front end of the white key 2a is depressed to its lowest position, the front end of the white key 2a is brought into contact with the key lower limit stopper 16b, which blocks further depression of the white key 2a.

[0060] The white key 2a depressed as above operates such that it pivotally moves about a virtual pivot P located rearward of the rear end thereof. The location of the virtual pivot P is set such that a distance from the front end of the white key 2a is approximately twice as long as the length of the white key 2a itself, for example. With this, when the front end of the white key 2a is depressed to the lowest position, compared with the case where the white key 2a is in the key-released state shown in FIG. 6A, the front end of the white key 2a is positioned lower by a predetermined key stroke (e.g. 10 mm) and the rear end of the white key 2a is located lower by a distance (e.g. 5 mm) which is approximately half of the predetermined key stroke.

[0061] On the other hand, when the finger is released from the white key 2a being depressed, the first arm 31 of the key support mechanism 6a pivotally moves in a direction opposite to the above-mentioned direction, by the own weight of the weight 34, and in accordance therewith, the second arm 32 as well pivotally moves in a direction opposite to the above-mentioned direction. In accordance with this pivotal movement of the second arm 32, the white key 2a pivotally moves upward about the virtual pivot P. Then, a predetermined portion of the first arm 31, rearward of the first pivot shaft 18a, moves into contact with the first arm lower limit stopper 10b from above, and both of the upper limit position regulation portions 21 and 21 of the white key 2a move into contact with the key upper limit stopper 16a from below, whereby further pivotal movement of the white key 2a is blocked and the white key 2a returns to its original key-released state.

[0062] Further, when the black key 2b is depressed, operations are performed similar to the above-described operations of the white key 2a and the key support mechanism 6a. More specifically, when a front end of the black key 2b is depressed from a key-released state shown in FIG. 7A, the first arm 31 is pivotally moved in the counterclockwise direction about the first pivot shaft 18a, and the second arm 32 is pivotally moved in the clockwise direction about the second pivot shaft 19a. With this, the black key 2b is operated such that it is pivotally moved about a virtual pivot Q located rearward of the rear end thereof. Note that similar to the above-mentioned virtual pivot P of the white key 2a, the location of the virtual pivot Q is set such that a distance from the front end of the black key 2b is approximately twice as long as the length of the black key 2b itself, for example. Therefore, when the front end of the black key 2b is depressed to its lowest position, compared with a case where the black key 2b is in the key-released state shown in FIG. 7A, the front end of the black key 2b is positioned lower by a predetermined key stroke and the rear end thereof is positioned lower by a distance which is approximately half of the predetermined key stroke.

[0063] On the other hand, when the finger is released from the black key 2b having been depressed, the first arm 31 and the second arm 32 of the key support mechanism 6b pivotally move in respective directions opposite to the above-mentioned directions, and in accordance therewith, the black key 2b pivotally moves upward about the virtual pivot Q. Then, the extension portion 26b of the key front-side connecting portion 26 of the black key 2b moves into contact with the key upper limit stopper 17 from below, whereby further pivotal movement of the black key 2b is blocked, and the black key 2b returns to its original key-released state.

[0064] Next, the essential part of the present invention will be described with reference to FIGS. 8A to 8C to FIGS. 12A and 12B. The essential part of the present invention consists in that in the keyboard device 1, the second arm 32 of the key support mechanism 6 is provided with second arm weights made of a material (metal such as iron) having a larger specific gravity than the second arm 32.

[0065] FIGS. 8A to 8C show a second arm 32A according to a first embodiment of the present invention, in which FIG. 8A is a perspective view, FIG. 8B is a side view, and FIG. 8C is an exploded perspective view. As shown in FIGS. 8A to 8C, the second arm 32A has two left and right second arm weights 52 and 52 mounted in a connecting portion 51 which is provided so as to connect between the bearing portion 41 formed at about the center of the second arm 32A and the second arm front-side connecting portion 45 formed at a front end of the second arm 32A. The connecting portion 51 has a partition wall 51a formed at the center thereof in the left-right direction, and on the left and right sides of the partition wall 51a, there are provided two left and right weight mounting portions 51b and 51b (only one of which is shown in FIGS. 8A to 8C) which are formed into a recessed shape open leftward and rightward. The partition wall 51a is formed with a through hole 51c for inserting a rivet 53, referred to hereinafter, therethrough.

[0066] The two second arm weights 52 and 52 are both made of a material (metal such as iron; same applies hereafter) having a larger specific gravity than the second arm 32A, and are each formed into an elongated and narrow plate shape extending in the front-rear direction and having the same shape as each other. Each second arm weight 52 has a mounting hole 52 formed therethrough at the center thereof. The two second arm weights 52 and 52 are inserted into the left and right weight mounting portions 51b and 51b of the second arm 32A from outside, respectively, and are fixed thereto in a state in which the rivet 53 is inserted into the two mounting holes 52a and 52a and the through hole 51c of the partition wall 51a.

[0067] According to the second arm 32A of the present embodiment, since the second arm weights 52 and 52 made of a material having a larger specific gravity than the second arm 32A are mounted therein, the inertia moment of the second arm 32A is increased by increasing the weight of the second arm 32A. This makes it possible to provide sufficient response to key depression, whereby it is possible to obtain excellent touch feeling during key depression. Further, it is possible to obtain excellent touch feeling by increasing the weight of the second arm 32A, whereby it is possible to suppress an increase in the weight of the first arm 31. With this, compared with a case where only the weight of the first arm 31 is increased, it is possible to improve the responsiveness of a key 2 having been depressed when the key 2 performs pivotal return movement to its original position, whereby it is possible to obtain appropriate string striking repeatability of the key 2.

[0068] In addition, the second arm weights 52 are provided forward of the bearing portion 41, i.e. forward of one of the second pivot shafts 19a, with which the bearing portion 41 is engaged, and hence, the second arm 32A becomes easy to be pivotally moved in a direction in which the second arm front-side connecting portion 45 formed at the front end of the second arm 32A and having been moved upward by depression of the key 2 moves downward in accordance with release of the key 2. As a consequence, the first arm 31, of which the first arm front-side connecting portion 35 formed at the front end thereof has been depressed by depression of the key 2, is further promoted to perform pivotal return movement to its original position. From the above, it is possible to further improve the touch feeling and the responsiveness of the key 2 when the key 2 is depressed.

[0069] FIGS. 9A to 9C show a second arm 32B according to a second embodiment of the present invention, in which FIG. 9A is a perspective view, FIG. 9B is a side view, and FIG. 9C is an exploded perspective view. The second arm 32B of the present embodiment includes, in addition to the above-describe second arm weights 52 of the first embodiment, L-shaped weights 54 (second arm weights) which are mounted in the vicinity of the bearing portion 41 of the second arm 32B. The second arm 32B has two left and right L-shaped weight mounting portions 41a and 41a (only one of which is shown in FIGS. 9A to 9C) provided on respective left and right sides thereof, which are each formed into a recessed shape open leftward and rightward and extending continuously from the rear of the bearing portion 41 to under the same.

[0070] The two L-shaped weights 54 and 54 are each made of a material having a larger specific gravity than the second arm 32B and formed into a substantially L shape, and both have the same shape as each other. The two L-shaped weights 54 and 54 are fitted in the respective left and right L-shaped weight mounting portions 41a and 41a of the second arm 32B from the outside and are fixed by bonding to the weight mounting portions 41a and 41a.

[0071] According to the second arm 32B of the present embodiment, it is possible not only to obtain the same advantageous effects as provided by the above-described second arm 32A of the first embodiment but also to relatively easily increase the weight of the second arm 32B.

[0072] FIGS. 10A to 10C are views of a second arm 32C according to a third embodiment of the present invention, in which FIG. 10A is a perspective view, FIG. 10B is a side view, and FIG. 10C is an exploded perspective view. This second arm 32C is provided with a weight accommodating portion 56 formed such that it extends through the connecting portion 51 in the left-right direction so as to mount a single second arm weight 55 in the second arm 32C in a state accommodated therein. In this weight accommodating portion 56, a total of four latching lugs 57 are formed two by two at respective upper and lower locations of an opening on a right side of the weight accommodating portion 56, and a total of two latching lugs 58 and 58 are formed one by one at respective upper and lower locations of an opening on a left side of the weight accommodating portion 56.

[0073] The second arm weight 55 of the present embodiment is made of a material having a larger specific gravity than the second arm 32C and is formed into a block shape extending in the front-rear direction. This second arm weight 55 is accommodated in the weight accommodating portion 56 by being inserted into the weight accommodating portion 56 from the left. Further, in this case, the second arm weight 55 within the weight accommodating portion 56 is fixed in the weight accommodating portion 56 in a state latched with the latching lugs 57 and 58 on the left and right sides of the weight accommodating portion 56 from the left-right direction.

[0074] According to the second arm 32C of the present embodiment, it is possible not only to obtain the same advantageous effects as provided by the second arm 32A of the first embodiment but also to easily mount the second arm weight 55 in the second arm 32C only by inserting the second arm weight 55 into the weight accommodating portion 56.

[0075] FIGS. 11A to 11C are views of a second arm 32D according to a fourth embodiment of the present invention, in which FIG. 11A is a perspective view, FIG. 11B is an exploded perspective view, and FIG. 11C is an exploded perspective view of a second arm weight. This second arm 32D is different from the above-described second arm 32C of the third embodiment only in a second arm weight 59. That is, this 1 second arm weight 59 is comprised of a block-shaped weight body 59a made of the same material as that of the second arm weight 55 of the third embodiment and extending in the front-rear direction, and a square tubular weight cover 59b mounted on the weight body 59a such that the square tubular weight cover 59b covers the outside of the weight body 59a, specifically, part other than a front end and a rear end thereof. This weight cover 59b is made e.g. of a soft synthetic resin or an elastic synthetic resin.

[0076] According to the second arm 32D of the present embodiment, during the operation of the second arm 32D in accordance with key depression, the second arm weight 59 (weight body 59a) is prevented from rattling or vibrating in the weight accommodating portion 56. This makes it possible to prevent noise from being generated by the second arm weight 59 during the operation of the second arm 32D.

[0077] FIGS. 12A and 12B show a second arm 32E according to a fifth embodiment of the present invention, in which FIG. 12A is a perspective view, and FIG. 12B is a side view. Most part of the second arm 32E is made of a synthetic resin, and part thereof is formed by a second arm weight. Specifically, in the connecting portion 51, a second arm weight 61 is provided such that it hangs downward from a lower surface of a top board 60 extending flat in the front-rear direction. The second arm weight 61 is formed into a plate shape having a predetermined thickness and is provided such that it extends from a central portion of the lower surface of the top board 60 in the front-rear direction.

[0078] When the second arm 32E is manufactured, it is possible to obtain the second arm 32E integrally formed with the second arm weight 61, by insert molding in which the second arm weight 61 is set in a mold and molten synthetic resin is injected into the mold.

[0079] According to the second arm 32E of the present embodiment, it is possible to obtain the same advantageous effects as provided by the above-described second arm 32A of the first embodiment. Moreover, it is possible to omit a step of mounting the second arm weight 61 during manufacturing the second arm 32E, which makes it possible to relatively easily manufacture the second arm 32E provided with the second arm weight 61.

[0080] Note that the second arm 32 of the keyboard device 1 according to the present invention is by no means limited to the first to fifth embodiments, described hereinabove, but can be practiced in various forms. For example, although in the respective second arms 32A and 32B of the first and second embodiments, the second arm weights 52 and the L-shaped weights 54 are mounted on the left and right sides of the second arms 32A and 32B, it is also possible to mount the second arm weights 52 and the L-shaped weights 54 on one of the left and right sides of the second arms 32A and 32B, as required. Further, although metal such as iron is mentioned, by way of example, as the material of the second arm weights, the present invention is not limited to this, but any suitable material can be used insofar as it has a larger specific gravity than the second arm 32, and it is possible to employ various materials, such as metal other than iron and a composite material made of metal and synthetic resin.

[0081] Further, details of the constructions of the second arms 32A to 32E sown in the first to fifth embodiments are given only by way of example, and they can be modified as appropriate within the scope of the subject matter of the present invention.