Patent ID: 12205568

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will now be described in detail with reference to the drawings showing preferred embodiments thereof.FIG.1Ashows only one octave section of a keyboard device1for 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 device1and operation thereof, and then of an essential part of a first aspect and an essential part of a second aspect of the present invention.

FIG.1Bshows a state of the keyboard device1shown inFIG.1A, in which keys2other than a white key2aand a black key2bat the left end of the keyboard device1are omitted.FIG.2shows a state of the keyboard device1shown inFIG.1B, in which the white key2aand the black key2bare removed, together with respective key support mechanisms6therefor, from a keyboard chassis4.

This keyboard device1is comprised of the keyboard chassis4, the plurality of keys2including the white keys2aand the black keys2band arranged in a state arranged side by side in a left-right direction, the plurality of key support mechanisms6each pivotally mounted on the keyboard chassis4, for supporting an associated one of the keys2from below, and key switches3each for detecting key depression information of an associated one of the keys2.

The keyboard chassis4includes a chassis body4aformed 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 inFIGS.3A and3B, the chassis body4ahas a front portion11, an intermediate portion12, and a rear portion13, each extending in the left-right direction (in a left-right direction as viewed inFIG.3A) as a whole. The front portion11, the intermediate portion12, and the rear portion13are integrally formed with each other via a plurality of ribs14disposed 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 portion11, the intermediate portion12, and the rear portion13of the chassis body4aof the keyboard chassis4will be referred to as “the chassis front11”, “the chassis intermediate12”, and “the chassis rear13”, respectively.

The chassis front11is mainly for guiding the white key2aduring depression thereof and restricting the upper limit position and the lower limit position of a front end of the white key2a. On the chassis front11, there are erected a plurality of white key guides11a, each of which is inserted into each associated one of the white keys2afrom below so as to prevent lateral swing of the white key2a, in a state arranged side by side in the left-right direction. Further, the chassis front11has engagement holes11band11b, vertically extending therethrough, which are formed on the left and right sides of each of the white key guides11a, respectively. A pair of left and right upper limit position regulation portions21and21, referred to hereinafter, of the white key2aare engaged with the respective engagement holes11band11bin a state inserted therethrough. Furthermore, the chassis front11has a front end thereof formed with a stopper-mounting portion11cthat protrudes forward and extends along the entirety of the chassis body4ain the left-right direction. A key upper limit stopper16aand a key lower limit stopper16bfor the white key are mounted on a lower surface and an upper surface of the stopper-mounting portion11c, respectively, such that they extend in the left-right direction. Note that a stopper-mounting portion11dfor the black key, which extends along the entirety of the chassis body4ain the left-right direction, is provided at a predetermined location of the chassis front11, rearward of each white key guide11a, and that a key upper limit stopper17for the black key is mounted on the stopper-mounting portion11dsuch that it extends in the left-right direction.

The chassis intermediate12is mainly for guiding the black key2bduring depression thereof and swingably supporting a first arm31and a second arm32, described hereinafter, of each of a white key-associated key support mechanism6aand a black key-associated key support mechanism6b. The chassis intermediate12has a flat portion12ain the form of a flat plate extending in the left-right direction, and a plurality of black key guides12berected on the flat portion12aand disposed with an appropriate spacing therebetween in the left-right direction. Each black key guide12bis inserted into an associated one of the black keys2bfrom below to prevent lateral swing of the black key2b. Further, the chassis intermediate12has a front portion thereof provided with a first arm support portion18for supporting the first arms31of the key support mechanisms6. The first arm support portion18has a plurality of first pivot shafts (support shafts)18aeach of which is provided between each adjacent two of the ribs14and14such that the first pivot shaft18aextends in the left-right direction. The first arms31are swingably supported on associated ones of the first pivot shafts18a. Furthermore, the chassis intermediate12has a rear portion thereof provided with a second arm support portion19for supporting the second arms32of the key support mechanisms6. The second arm support portion19has a plurality of second pivot shafts (support shafts)19aeach of which is provided between each adjacent two of the ribs14and14such that the second pivot shaft19aextends in the left-right direction. The plurality of second pivot shafts19aare arranged on the same axis extending in the left-right direction at a location rearward of and higher than the first pivot shafts18a, and the second arms32are swingably supported on associated ones of the second pivot shafts19a. Note that a first arm lower limit stopper10bextending along the entirety of the chassis body4ain the left-right direction is provided at a predetermined location of a middle rail8, referred to hereinafter, disposed below the chassis intermediate12.

Further, the above-mentioned key switches3are provided on a lower portion of the keyboard chassis4between the above-described chassis front11and chassis intermediate12. The key switches3are formed by a laterally elongated printed circuit board3aextending in the left-right direction, and a plurality of switch bodies3bformed by rubber switches attached to the printed circuit board3aon a key-by-key basis, for being pressed by associated ones of the first arms31upon key depression.

The chassis rear13is mainly for guiding the keys2by their rear ends in the vertical direction while preventing lateral swing of the keys2and for restricting the upper limit positions of the rear ends of associated ones of the first arms31. As shown inFIGS.2and3A, the chassis rear13has a plurality of partition walls13aformed with a predetermined spacing therebetween in the left-right direction so as to separate each adjacent two of the keys2and2from each other. Further, as shown inFIG.3B, a first arm upper limit stopper10aextending along the entirety of the chassis body4ain the left-right direction is provided at a predetermined location of an upper portion of the chassis rear13. The first arm upper limit stopper10aand the first arm lower limit stopper10bprovided on the chassis intermediate12are for restricting the upper limit position and the lower limit position of the first arm31, respectively, when the first arm31having a function as a hammer for adding a touch weight to the key2pivotally moves upward and downward. Furthermore, a metal cover plate15extending in the left-right direction along the entirety of the chassis body4aand disposed to cover the rear ends of the keys2is mounted on the upper portion of the chassis rear13.

As shown inFIGS.2and3A, the chassis body4aof the keyboard chassis4constructed as described above is formed with a plurality of first openings5aopen upward and forward and a plurality of second openings5bopen upward. The first arms31of the key support mechanisms6are engaged with associated ones of the first pivot shafts18afrom outside via the above-mentioned first openings5a, respectively. Further, the second arms32are engaged with associated ones of the second pivot shafts19afrom outside via the above-mentioned second openings5b, respectively.

Further, in the above-described keyboard chassis4, a plurality of chassis bodies4aare connected to each other so as to be arranged side by side in the left-right direction, and are each screwed to a front rail7, the middle rail8, and a rear rail9in a state placed thereon, the rails7,8and9each extending in the left-right direction and arranged with a predetermined spacing therebetween in the front-rear direction. The keyboard chassis4is fixed to a keybed, not shown, of the electronic piano via the front rail7and the rear rail9.

Next, the keys2and the key support mechanisms6will be described.FIG.4Ashows the white key2aand the key support mechanism6atherefor on an enlarged scale, andFIG.4Bshows them in an exploded state. As shown inFIGS.4A and4B, the white key2ais 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 key2ahas the front end thereof formed with the pair of left and right upper limit position regulation portions21and21which protrude downward from respective side walls of the front end of the white key2aand each having a lower end thereof bent forward. As described hereinabove, the left and right upper limit position regulation portions21and21are engaged with the respective left and right engagement holes11band11bof the chassis front11in a state inserted therethrough.

Further, at a predetermined location of a front portion of the white key2a, rearward of the upper limit position regulation portions21, there is formed a key front-side connecting portion22connected to the first arm31of the key support mechanism6a. This key front-side connecting portion22includes a connecting recess (engagement recess)22awhich has a U shape having a slot-like shape in side view and open forward. Further, the connecting recess22ahas a cushioning member (key-side noise suppressing member)20attached thereto, which is formed to cover the whole inner peripheral surface of the connecting recess22a, for suppressing generation of noise when a connecting shaft35b, referred to hereinafter, of the first arm31slides in the inner peripheral surface of the connecting recess22a.

Furthermore, the white key2ahas a rear portion thereof provided with a key rear-side connecting portion23connected to the second arm32of the key support mechanism6a. The key rear-side connecting portion23has a plate-like connecting body portion23awhich hangs downward from a laterally central portion of the white key2aand has a predetermined thickness in the left-right direction, and a pair of left and right engagement protrusions23band23bwhich coaxially protrude from the left and right side surfaces of the connecting body portion23a, respectively. Further, a rear portion of the white key2ais formed with a tool insertion hole24which vertically extends through the rear portion, and is used to insert a predetermined tool from above for disconnecting the white key2afrom the second arm32of the key support mechanism6ae.g. for maintenance of the keyboard device1.

On the other hand, the key support mechanism6aincludes the first arm31and the second arm32which are engaged with each other and are connected to the key front-side connecting portion22and the key rear-side connecting portion23of the white key2a, respectively.

As shown inFIG.4B, the first arm31is comprised of an arm body33and two weights34and34attached to the arm body33. The arm body33is 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 body33extends a predetermined length in the front-rear direction, and has a front end thereof formed with a first arm front-side connecting portion35connected to the key front-side connecting portion22of the white key2a. The first arm front-side connecting portion35includes a box portion35ahaving a box-like shape open upward and forward, and the connecting shaft35bprovided 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 portion35ato each other. The connecting shaft35bis connected to the connecting recess22aof the key front-side connecting portion22of the white key2asuch that the connecting shaft35bis pivotally movable and is slidable in the front-rear direction.

Further, the arm body33has a bearing portion36formed at a predetermined location immediately rearward of the first arm front-side connecting portion35. The bearing portion36has an inverted U shape open downward in side view, and is pivotally engaged with the first pivot shaft18aof the keyboard chassis4. Furthermore, the arm body33has a first arm rear-side connecting portion37, which is connected to the second arm32, at a predetermined location rearward of the bearing portion36. Specifically, the first arm rear-side connecting portion37has a connecting shaft37awhich extends in the left-right direction with respective opposite ends thereof protruding outward from the left and right side surfaces of the arm body33. The opposite ends of the connecting shaft37aare engaged with connecting recesses45band45bof a second arm front-side connecting portion45, referred to hereinafter, of the second arm32.

The two weights34and34formed as elongated and narrow plates are mounted on a weight mounting portion38, which is a rear portion of the arm body33, in a state sandwiching the weight mounting portion38. Note that each weight34is made of a material (metal such as iron) having a larger specific gravity than the arm body33, and is formed e.g. by pressing a metal plate into a predetermined shape.

The second arm32is formed as a resin molded article having a predetermined shape by injection molding of the same resin material as that of the arm body33of the first arm31. The second arm32is shorter than the first arm31and extends a predetermined length in the front-rear direction. Further, the second arm32has a bearing portion41having a C shape open forward in side view at about a longitudinal center thereof. The bearing portion41is pivotally engaged with an associated one of the second pivot shafts19aof the keyboard chassis4.

Further, the second arm32has a rear portion thereof provided with a second arm rear-side connecting portion42connected to the key rear-side connecting portion23of the white key2a. The second arm rear-side connecting portion42is formed into a bifurcated shape, and has two left and right connecting arm portions43and43which extend a predetermined length parallel to each other along the longitudinal direction of the second arm32. Each connecting arm portion43has a rear end thereof formed with a connecting hole43aextending through the connecting arm portion43in the left-right direction. The two connecting arm portions43and43sandwich the connecting body portion23aof the key rear-side connecting portion23of the white key2abetween the rear ends thereof from the left and the right, and each connecting hole43ahas an associated one of the engagement protrusions23bof the key rear-side connecting portion23pivotally fitted therein.

Furthermore, the second arm32has a front portion thereof provided with the second arm front-side connecting portion45connected to the first arm rear-side connecting portion37of the first arm31. The second arm front-side connecting portion45has a pair of left and right connecting portions45aand45aarranged with a predetermined spacing in the left-right direction. The connecting portions45aand45aare each formed with the connecting recess45bwhich has a U shape having a slot-like shape in side view and open forward. The left and right connecting portions45aand45aof the second arm front-side connecting portion45are pivotally and slidably engaged with the respective opposite ends of the connecting shaft37aof the first arm31via the connecting recesses45band45bthereof.

FIG.5Ashows the black key2band the key support mechanism6btherefor on an enlarged scale, andFIG.5Bshows the black key2band the key support mechanism6bin an exploded state. The black key2bis formed e.g. by injection molding of the same resin material as that of the white key2ainto a hollow shape which extends in the front-rear direction by a predetermined length shorter than that of the white key2aand opens downward. The black key2bhas a front-side lower end thereof provided with a key front-side connecting portion26formed substantially similar to the key front-side connecting portion22of the white key2a. This key front-side connecting portion26has a connecting recess (engagement recess)26awhich has a U shape having a slot-like shape in side view and open forward. Further, the key front-side connecting portion26has an extension portion26bon a lower-side front end of the connecting recess26a. The extension portion26bextends a predetermined length forward of the front surface of the body of the black key2b. This extension portion26bfunctions as an upper limit position regulation portion of the black key2b. Note that in the following description, the components of the black key2band the key support mechanism6bhaving the same configurations as those of the above-described white key2aand key support mechanism6aare denoted by the same reference numerals and detailed description thereof will be omitted.

The key support mechanism6bsupporting the black key2bis constructed substantially similar to the above-described white key-associated key support mechanism6a. Specifically, the arm body33of the first arm31of the key support mechanism6band the second arm32of the same are constructed exactly similar in shape and size to the arm body33and the second arm32of the white key-associated key support mechanism6a. Note that two left and right weights34and34of the black key-associated key support mechanism6bdiffer from the weights34of the white key-associated key support mechanism6ain the shape of the rear portion thereof.

Next, a description will be given of the operation of the keys2and the key support mechanisms6of the keyboard device1constructed as described above.FIGS.6A and6Bare views useful in explaining the operation of the white key2aand the key support mechanism6aassociated therewith.FIGS.7A and7Bare views useful in explaining the operation of the black key2band the key support mechanism6bassociated therewith.

When the front end of the white key2ais depressed by a player with his/her finger from a key-released state shown inFIG.6A, the key front-side connecting portion22of the white key2ais moved downward, whereby the first arm31is pivotally moved in a counterclockwise direction about the first pivot shaft18a. Further, in accordance with the pivotal movement of the first arm31, the second arm front-side connecting portion45, which is engaged with the connecting shaft37aof the first arm31via the connecting recesses45band45b, is moved upward. With this, the second arm32is pivotally moved in a clockwise direction about the second pivot shaft19a. Then, in accordance with this pivotal movement of the second arm32, the key rear-side connecting portion23, which is connected to the second arm32via the second arm rear-side connecting portion42formed at the rear end of the second arm32, is pulled down, whereby the rear end of the white key2ais moved downward.

Note that during the above-mentioned pivotal movement of the first arm31, the box portion35aof the first arm front-side connecting portion35is moved downward, and accordingly, the switch body3bof one of the key switches3, which is associated with the depressed key2, is pressed from above by the bottom wall of the box portion35a. As a consequence, in the electronic piano, key depression information of the depressed key2is detected, and based on the detected key depression information, sound is generated from a speaker, not shown.

As described hereinabove, in the case where the white key2ais depressed, in accordance with the counterclockwise pivotal movement of the first arm31, the weight34of the first arm31is tilted such that the weight34becomes higher as it extends rearward, whereby the rear end of the weight34is brought into contact with the first arm upper limit stopper10afrom below, as shown inFIG.6B. This prevents further pivotal movement of the first arm31. When the front end of the white key2ais depressed to its lowest position, the front end of the white key2ais brought into contact with the key lower limit stopper16b, which blocks further depression of the white key2a.

The white key2adepressed 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 key2abecomes approximately twice as long as the length of the white key2aitself, for example. With this, when the front end of the white key2ais depressed to the lowest position, compared with the case where the white key2ais in the key-released state shown inFIG.6A, the front end of the white key2ais positioned lower by a predetermined key stroke (e.g. 10 mm) and the rear end of the white key2ais located lower by a distance (e.g. 5 mm), which is approximately half of the above key stroke.

On the other hand, when the finger is released from the white key2abeing depressed, the first arm31of the key support mechanism6apivotally moves in a direction opposite to the above-mentioned direction, by the own weight of the weight34, and in accordance therewith, the second arm32as well pivotally moves in a direction opposite to the above-mentioned direction. In accordance with this pivotal movement of the second arm32, the white key2apivotally moves upward about the virtual pivot P. Then, a predetermined portion of the first arm31, rearward of the first pivot shaft18a, moves into contact with the first arm lower limit stopper10bfrom above, and both of the upper limit position regulation portions21and21of the white key2amove into contact with the key upper limit stopper16afrom below, whereby further pivotal movement of the white key2ais blocked and the white key2areturns to its original key-released state.

Further, operation in response to depression of the black key2bis performed similar to the above-described operations of the white key2aand the key support mechanism6ain response to depression of the white key2a. More specifically, when a front end of the black key2bis depressed from a key-released state shown inFIG.7A, the first arm31is pivotally moved in the counterclockwise direction about the first pivot shaft18a, and the second arm32is pivotally moved in the clockwise direction about the second pivot shaft19a. With this, the black key2boperates such that it pivotally moves 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 key2a, the location of the virtual pivot Q is set such that a distance from the front end of the black key2bbecomes approximately twice as long as the length of the black key2bitself, for example. Therefore, when the front end of the black key2bis depressed to its lowest position, compared with a case where the black key2bis in the key-released state shown inFIG.7A, the front end of the black key2bis positioned lower by a predetermined key stroke and the rear end thereof is positioned lower by a distance which is approximately half of the above key stroke.

On the other hand, when the finger is released from the black key2bhaving been depressed, the first arm31and the second arm32of the key support mechanism6bpivotally move in respective directions opposite to the above-mentioned directions, and in accordance therewith, the black key2bpivotally moves upward about the virtual pivot Q. Then, the extension portion26bof the key front-side connecting portion26of the black key2bmoves into contact with the key upper limit stopper17from below, whereby further pivotal movement of the black key2bis blocked, and the black key2breturns to its original key-released state.

Next, the essential part of the first aspect of the present invention will be described with reference toFIGS.8A to14C. The essential part of the first aspect of the present invention is that the angle of pivotal movement of the first arm31(hammer) caused by depression of the key2is set such that it varies depending on the type of the depressed key2. More specifically, for the white key2a(second key) and the black key2b(first key), or for a key2in a higher-pitched range (second key) and a key2in a lower-pitched range (first key), the angles of pivotal movement of the first arms31of the associated key support mechanisms6, caused by key depression, are set such that they differ from each other.

First, a description is given of a case where for the white key2aand the black key2b, the angles of pivotal movement of the first arms31and31of the respective associated key support mechanisms6aand6b, caused by key depression, are set such that they differ from each other.FIG.8Ais a side cross-sectional view of the white key2a, andFIG.8Bis a view of the connecting recess22aof the key front-side connecting portion22of the white key2aon an enlarged scale. On the other hand,FIG.8Cis a side cross-sectional view of the black key2b, andFIG.8Dis a view of the connecting recess26aof the key front-side connecting portion26of the black key2bon an enlarged scale. Note that as described hereinabove, although the cushioning members20for suppressing generation of noise during key depression are attached to the respective connecting recesses22aand26aof the white key2aand the black key2b, the following description is given by omitting the description of the cushioning members20.

As shown inFIG.8B, the connecting recess22aof the white key2aincludes an upper surface61and a bottom surface62which are opposed to each other in the vertical direction with a predetermined distance therebetween and extend parallel to each other in the front-rear direction (in a left-right direction as viewed inFIG.8B). This connecting recess22ais formed by the above-mentioned the upper surface61and the bottom surface62such that the connecting recess22aextends in the front-rear direction along a reference line L which substantially horizontally extends in the key-released state. That is, the inclination of the connecting recess22ain an extension direction thereof coincides with the reference line L. Note that inFIG.8B, to make it easy to understand the inclination of the connecting recess22ain the extension direction thereof, the reference line L is shown in a state aligned with the upper surface61, and the same applies to other figures described hereinafter.

On the other hand, as shown inFIGS.8C and8D, the connecting recess26aof the black key2bincludes an upper surface63and a bottom surface64similar to the upper and bottom surfaces61and62of the connecting recess22aof the white key2a. Further, the connecting recess26aof the black key2bis configured to slope downward as it extends forward (slope downward to the left as viewed inFIG.8D) at a predetermined angle (e.g. one to two degrees) with respect to the above-mentioned reference line L. That is, the extension direction of the connecting recess26ais more inclined downward toward the front than that of the connecting recess22aof the white key2a.

FIG.9Ais a side cross-sectional view of the keyboard device1with the focus on the white key2a,FIG.9Bshows the connecting recess22aof the white key2aon an enlarged scale. As described above, during key depression, the white key2aoperates such that it pivotally moves about the virtual pivot P appearing inFIG.9A. In this case, the virtual pivot length, which is a length from the rear end of the white key2ato the virtual pivot P, is a length D.

On the other hand,FIG.9Cis a side cross-sectional view of the keyboard device1with the focus on the black key2b, andFIG.9Dshows the connecting recess26aof the black key2bon an enlarged scale. As described above, during key depression, the black key2boperates such that it pivotally moves about the virtual pivot Q appearing inFIG.9C. In this case, a virtual pivot length E, which is a length from a rear end of the black key2bto the virtual pivot Q, is longer than the virtual pivot length D of the white key2asince the extension direction of the connecting recess26ais more inclined downward toward the front than that of the connecting recess22aof the white key2a(E>D).

Here, the operating principle of the keyboard device1in which the virtual pivot length E of the black key2bis longer than the virtual pivot length D of the white key2aas described above, will be described with reference to schematic views ofFIGS.10A and10BandFIGS.11A and11B.FIGS.10A and10Bshow the white key2aand the key support mechanism6atherefor and the black key2band the key support mechanism6btherefor, when in the key-released state, respectively. Note that in these schematic views, for the connecting recess22aof the white key2aand the connecting recess26aof the black key2b, only the upper surfaces61and63are illustrated which function as points of action when the first arms31are pivotally moved in a counterclockwise direction. Further, to make it easy to understand a difference between the inclinations of the two upper surfaces61and63, the inclination of the upper surface63is illustrated larger than actual inclination.

As shown inFIGS.10A and10B, in the key-released states, the first arms31and the second arms32of the respective key support mechanisms6aand6bfor the white key2aand the black key2bare maintained in the same posture. When the front end of the white key2ais depressed from this state, the connecting shaft35bis depressed via the upper surface61, whereby the first arm31is pivotally moved in the counterclockwise direction about the first pivot shaft18a. On the other hand, the connecting shaft37ais moved upward in accordance with the above-mentioned pivotal movement of the first arm31, whereby the second arm32is pivotally moved in the clockwise direction about the second pivot shaft19a. Then, when the white key2ais depressed to the lowest position, the first arm31is pivotally moved to a position shown inFIG.11A.

On the other hand, when the front end of the black key2bis depressed from the state shown inFIG.10B, the first arm31and the second arm32are pivotally moved, similar to the white key2a. In the black key2b, however, since the inclination of the upper surface63(the connecting recess26a) is larger than the inclination of the upper surface61(the connecting recess22a) of the white key2a, when the black key2bis depressed to the lowest position, the connecting shaft35bof the first arm31, which is slid forward along the upper surface63, is positioned lower than that of the first arm31for the white key2a. As a consequence, the angle of pivotal movement of the first arm31for the black key2bbecomes larger than that of the first arm31for the white key2a. In addition, the angle of pivotal movement of the second arm32for the black key2balso becomes larger than that of the second arm32for the white key2a. With this, the engagement protrusions23bof the rear end of the black key2bare pulled down lower than the engagement protrusions23bof the white key2a, so that the virtual pivot length E of the black key2bbecomes longer than the virtual pivot length D of the white key2a.

Next, with reference toFIGS.12A to13B, a description will be given of the keyboard device1configured such that, for the key2in the higher-pitched range and the key2in the lower-pitched range, the angles of pivotal movement of the first arms31therefor, caused by key depression, are made different from each other, whereby the touch weights of the keys2are made different from each other.FIGS.12A to12Dare views similar toFIGS.9A to9D.FIG.12Ais a side cross-sectional view of the keyboard device1with the focus on a white key2in the higher-pitched range, andFIG.12Bshows a connecting recess22aof the white key2appearing inFIG.12Aon an enlarged scale. As shown inFIG.12B, the connecting recess22aof the white key2in the higher-pitched range is configured to extend in the front-rear direction along the reference line L when in the key-released state.

On the other hand,FIG.12Cis a side cross-sectional view of the keyboard device1with the focus on a white key2ain the lower-pitched range, andFIG.12Dshows a connecting recess22aof the white key2aappearing inFIG.12Con an enlarged scale. As shown inFIG.12D, the connecting recess22aof the white key2ain the lower-pitched range includes an upper surface61A and a bottom surface62A, and is formed by the upper surface61A and the bottom surface62A such that in the key-released state, the connecting recess22aslopes downward as it extends forward (slopes downward to the left as viewed inFIG.12D) at a predetermined angle (e.g. one to two degrees) with respect to the reference line L. Thus, the extension direction of the connecting recess22aof the white key2ain the lower-pitched range is more inclined downward toward the front than that of the connecting recess22aof the white key2a.

FIGS.13A and13Bare schematic views showing key-depressed states of the white keys, which correspond toFIG.12AandFIG.12c, respectively. As shown inFIG.13B, in the key support mechanism6athat supports the white key2ain the lower-pitched range, the angle of the pivotal movement of the first arm31, caused by key depression, is larger than that of the first arm31of the key support mechanism6a, shown inFIG.13A, which supports the white key2ain the higher-pitched range. With this, the touch weight of the white key2ain the lower-pitched range becomes heavier than the touch weight of the white key2ain the higher-pitched range.

FIGS.14A to14Care views useful in explaining another embodiment, which is configured such that the angle of pivotal movement of the first arm31, caused by key depression, varies depending on the type of the key2.FIG.14Ais a side cross-sectional view of the keyboard device1with the focus on the white key2a. In this keyboard device1, the second pivot shaft19athat supports the second arm32of each key support mechanism6and the first pivot shaft18athat supports the first arm31of each key support mechanism6are provided in a state displaced from each other in a predetermined direction by a predetermined length, between the white key2aand the black key2band between the key2in the higher-pitched range and the key2in the lower-pitched range.

FIG.14Bshows an example in which the two second pivot shafts19aand19athat support the second arms32, respectively, are provided at respective locations different from each other. InFIG.14B, the two second pivot shafts19aand19aare provided in a state displaced from each other in the front-rear direction by a diameter of the second pivot shaft19a.

Further,FIG.14Cshows an example in which the two first pivot shafts18aand18athat support the first arms31, respectively, are provided at respective locations different from each other. InFIG.14C, the two first pivot shafts18aand18aare provided in a state displaced from each other in the front-rear direction by a diameter of the first pivot shaft18a.

As described above, by setting the locations of the second pivot shafts19adepending on the type of the key2, and in addition by setting the locations of the first pivot shafts18adepending on the type of the key2, the angle of pivotal movement of the first arm31caused by key depression can be adjusted, whereby it is possible to adjust the virtual pivot length and the touch weight according to the type of the key2.

Next, the essential part of the second aspect of the present invention will be described with reference toFIGS.15A to18B.FIGS.15A and15Bshow the bearing portion36of the arm body33of the first arm31and the first pivot shaft18athat supports the bearing portion36, on an enlarged scale. Note that to make it easy to understand the configuration,FIGS.15A and15Bschematically show a guide groove36bby illustrating the same as a groove slightly longer than actual length, and so forth.

As described hereinabove, the first pivot shaft18ais integrally formed with the chassis intermediate12(not shown inFIGS.15A and15B) of the keyboard chassis4, extends horizontally, and is circular in cross-section with a predetermined diameter F. The bearing portion36has a circular shaft hole36aformed in the vicinity of a lower surface of the arm body33, and the guide groove36bwhich opens in the lower surface of the arm body33, extends obliquely upward therefrom, and is continuous with the shaft hole36a.

The guide groove36bhas a groove width W slightly smaller than the diameter F of the first pivot shaft18a, and the shaft hole36ahas a diameter which is set to be approximately equal to the diameter F of the first pivot shaft18asuch that the shaft hole36ais pivotally fitted on the first pivot shaft18a. Further, an inclination angle A of the guide groove36bwith respect to horizontal in the key-released state is preferably within a range of 45±15 degrees for a reason described hereinafter, and is set to approximately 45 degrees in the example illustrated inFIG.15A.

With this construction, the first arm31is mounted on the first pivot shaft18aas described below. First, the first arm31is, after being positioned as inFIG.15A, moved obliquely downward (in a direction indicated by an arrow X) toward the first pivot shaft18a, and a tip end of the guide groove36bis pressed against the first pivot shaft18afor engagement therewith. Then, when the first arm31is further pressed in the same direction, the first arm31is moved obliquely downward while being guided by the guide groove36b, in a state where the guide groove36bhaving a narrow width is elastically pushed laterally outward by the first pivot shaft18a. Then, when the guide groove36bovercomes the first pivot shaft18a, the guide groove36belastically returns to an original state thereof and at the same time the shaft hole36ais fitted (snap-fitted) on the first pivot shaft18a. With this, as shown inFIG.15B, the first arm31is mounted on the first pivot shaft18avia the shaft hole36aand is pivotally supported thereon.

As described above, the first arm31is snap-fitted on the first pivot shafts18avia the bearing portion36. Further, the guide groove36bextends obliquely from the lower surface of the first arm31to the shaft hole36a. For this reason, e.g. during transportation of a keyboard device as a manufactured product, when impact in the front-rear direction or in the vertical direction acts on the keyboard device1, a direction of inertial force due to the impact is largely different from a direction of the guide groove36b, whereby the inertial force is dispersed. As a result, when impact acts on the keyboard device1, it is possible to effectively suppress disengagement of the first arm31from the first pivot shaft18a.

For example, when the electronic piano including the keyboard device1of the present embodiment is transported as a manufactured product, normally, as shown inFIG.16, it is received in a container box G made of e.g. cardboard in a state where four corners of the electronic piano are covered by a cushioning material C, such as styrofoam. Therefore, in many cases, impact on the keyboard device1during transportation thereof acts in a front-rear direction (H) or in a vertical direction (V).

When the impact on the keyboard device1acts in the front-rear direction, in the above-described keyboard device disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 2016-191832, since the hammer is fitted on the support shaft from the front side and the direction of inertial force due to the impact and the direction of fitting the hammer are almost the same, there is a fear that the hammer is disengaged from the support shaft. Further, when the impact on the keyboard device acts in the vertical direction, in the keyboard device disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 2015-87591, since the hammer is fitted on the support shaft from above and the direction of inertial force due to the impact and the direction of fitting the hammer are almost the same, there still is a fear that the hammer is disengaged from the support shaft.

On the other hand, in the keyboard device1of the present embodiment, as described hereinabove, when the impact in the front-rear direction or in the vertical direction acts, the direction of inertial force due to the impact is largely different from the direction of the guide groove36b, whereby the inertial force is dispersed, so that it is possible to effectively suppress disengagement of the first arm31from the first pivot shaft18a.

Note that as shown inFIG.16, when the impact on the keyboard device1acts in an oblique direction (I), the direction of inertial force due to the impact is sometimes equal to the direction of the guide groove36b. In this case, however, the container box G is crushed to absorb part of the impact, and the first arm upper limit stopper10awith which the pivotally-moved first arm31is brought into contact supports part of the impact, which prevents disengagement of the first arm31.

Next, a recessed and protruded portion for removing the first arm31will be described with reference toFIGS.17A to17DandFIGS.18A and18B. As shown inFIG.17A, the recessed and protruded portion, denoted by reference numeral51, is formed on the arm body33(weight mounting portion38) of the first arm31. More specifically, as shown inFIG.17B, the recessed and protruded portion51is formed by a protrusion51awhich is integrally formed on a rear end of an upper surface of the arm body33and protrudes upward from along the entirety width of the rear end of the upper surface of the arm body33.

With this construction, the first arm31is removed from the first pivot shaft18aby using the protrusion51aas described below. First, as shown inFIG.18A, after the key2is removed from the keyboard device1in an assembled state, a rod-like tool R, such as a screwdriver, is inserted from above to apply a tip end of the tool R on (engage the same with) the front surface of the protrusion51a. Then, an intermediate portion of the tool R is pressed against an appropriate portion S of the keyboard chassis4(chassis rear13), the portion S existing in the vicinity and forward of the intermediate portion, and the tool R is turned using the portion S as a fulcrum in a direction indicated by an arrow Y inFIG.18B. With this, as indicated by an arrow Z, the first arm31is driven along the guide groove36bobliquely upward and rearward, whereby it is removed from the first pivot shafts18a.

As described above, the rod-like tool R, which is applied to the protrusion51aformed on the upper surface of the first arm31, is turned using the portion S of the keyboard chassis4as a fulcrum based on the principle of leverage, whereby the first arm31is removed. With this, the first arm31, which is snap-fitted and is difficult to remove, can be easily removed from the first pivot shaft18awithout using a special tool.

As described hereinabove, according to the keyboard device1to which is applied the essential part of the first aspect of the present invention, the angle of pivotal movement of the first arm31which is pivotally moved in a manner interlocked with depression of an associated key2is set such that the angle varies depending on the type of the key2, whereby the touch weight and the virtual pivot length of the key2during depression of the key can be adjusted according to the type of the key2, and consequently it is possible to obtain the same key operation as that of an acoustic grand piano.

Note that the first aspect of the present invention is not limited to the above-described embodiment, but it can be practiced in various forms. For example, although in the above-described embodiment, while the key front-side connecting portions22and26of the key2are formed with the connecting recesses22aand26a, respectively, the first arm front-side connecting portion35of the first arm31is formed with the connecting shaft35b, it is also possible to reverse the positional relationship between the connecting recesses22aand26aand the connecting shaft35bwhich are engaged with each other, that is, it is possible to form the connecting recesses in the first arm31and form the connecting shaft on the key2.

Further, in the above-described embodiment, as the inclinations of the connecting recesses22aand26aof the key2in the extension directions thereof, only two types are described, by way of example. However, in the keyboard device1, it is also possible to set three or more types of inclinations as the inclinations of the connecting recesses22aand26ain the extension directions thereof. With this, the angle of pivotal movement of the first arm31caused by depression of the key2can be finely set according to a larger number of types of keys2(including e.g. keys in a middle-pitched range in addition to the keys in the lower-pitched range and the higher-pitched range).

Furthermore, although in the above-described embodiment, the description is given of a case where the present invention is applied to the keyboard device1in which the keys2depressed operate such that they pivotally move about the virtual pivots P and Q located rearward of the rear ends of the keys2, respectively, the present invention is not limited to this, but as a matter of course, the present invention can be applied to a general keyboard device in which keys are pivotally moved about the rear ends of their own, respectively, and each of which is not provided with the second arm32. Further, details of the constructions of the keys2and the key support mechanisms6shown in the embodiment 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.

Further, the second aspect of the present invention is not limited to the above-described embodiment, but it can be practiced in various forms. For example, although in the above-described embodiment, the inclination angle A of the guide groove36bof the first arm31with respect to horizontal in the key-released state is set to approximately 45 degrees, the inclination angle A is only required to be within the range of 45±15 degrees. This is because if the inclination angle A is larger than 60 degrees, the inclination of the guide groove36bis close to vertical, which causes insufficient dispersion of inertial force when the impact in the vertical direction acts, whereas if the inclination angle A is smaller than 30 degrees, the inclination of the guide groove36bis close to horizontal, which causes insufficient dispersion of inertial force when the impact in the front-rear direction acts. Therefore, if the inclination angle A is within the range of 45±15 degrees, inertial force caused by impact is sufficiently dispersed, whereby it is possible to effectively suppress disengagement of the first arm31and obtain the same advantageous effects as provided by the inclination angle A of approximately 45 degrees.

Further, although in the above-described embodiment, the protrusion51ashown inFIG.18Bis provided as the recessed and protruded portion51for removing the first arm31, any desired configuration of the corresponding portion can be employed insofar as the portion enables the tool R to be engaged therewith and the first arm31to be thereby turned.FIGS.17C and17Dshow other examples of the recessed and protruded portion51which are configured as such. In the example illustrated inFIG.17C, the recessed and protruded portion51is formed by a recessed portion51bformed along the entire width of the upper surface of the arm body33, whereas in the example illustrated inFIG.17D, the recessed and protruded portion51is formed by a pair of cutouts51cwhich are formed in the upper surface of the arm body33at respective locations spaced from each other in a width direction of the upper surface. With these configurations, similar to the case of the above-described protrusion51a, by engaging an appropriate tool R with the concave portion51bor the cutouts51cand turning the first arm31, it is possible to easily remove the first arm31from the first pivot shaft18a.

Further, details of the construction of the embodiment, for example, the configuration and dimensional relationship between components of the bearing portion36of the first arm31shown inFIGS.15A and15B, 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.