Keyboard device for keyboard instrument

A keyboard instrument which is capable of ensuring sufficient strength of neighboring portions of chassis and preventing generation of noise, while restricting lateral motion of hammers. Keys are pivotally supported by chassis arranged side by side in a left-right direction. Hammers are pivotally supported by the chassis, for each being pivotally moved in accordance with depression of the associated key. Guides are formed in the chassis and each have a pair of left and right sidewalls opposed to the associated hammer from opposite sides, for restricting lateral motion of the associated hammer. Out of the guides, one at a boundary of each adjacent two of the chassis has the pair of sidewalls formed by an end sidewall of one of the adjacent two chassis and an end sidewall of the other of the same.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a keyboard device for a keyboard instrument, such as an electronic piano.

2. Description of the Prior Art

Conventionally, this kind of keyboard device has been proposed e.g. in Japanese Laid-Open Patent Publication (Kokai) No. 2000-122654. This keyboard device is for use in an electronic piano, and as shown inFIG. 15, it includes a chassis assembly81, a plurality of keys82(only one of which is shown) and a plurality of hammers83(only one of which is shown). The chassis assembly81is comprised of six intermediate chassis81a(seeFIG. 16) each provided as a unit for one octave, a chassis (not shown) for the lowest pitch range, and a chassis (not shown) for the highest pitch range, which are formed by injection molding of a synthetic resin, such as an ABS resin. The intermediate chassis81aare identical in size and shape. These eight chassis are connected by four connecting bars91extending in the left-right direction, such that they are arranged side by side in the left-right direction, and supported on a keybed84. Each of the chassis has key supports85formed at a rear end thereof, hammer supports86formed at a central portion thereof, second hammer passage holes87formed through respective portions forward of the hammer supports86, and first hammer passage holes88formed through a front end thereof (seeFIG. 16). The key supports85, the hammer supports86, the second hammer passage holes87, and the first hammer passage holes88are formed in association with the respective keys82. Each adjacent two of the first hammer passage holes88are separated by a sidewall90.

The keys82are comprised of white keys82aand black keys82b. Each of the keys82has a rear end thereof pivotally supported by the associated key support85of the chassis assembly81, and extends in the front-rear direction on the upper side of the chassis assembly81. Each hammer83also extends in the front-rear direction, and the rear end thereof is mounted to two adjacent hammer supports86and86in a manner spanning these, and pivotally supported by them. Further, the hammer83passes through the associated second hammer passage hole87and extends forward below the chassis assembly81. The hammer83has weight plates89(only one of which is shown) attached to the respective left and right side surfaces of the front end thereof, for adding weight to the hammer83. Above the front end of the hammer83, there opens the associated first hammer passage hole88.

Fixed to the four connecting bars91connecting the chassis are ribs92(only one of which is shown) for reinforcing the rigidity of the chassis assembly81in the front-rear direction, which are arranged at respective predetermined locations on an octave-by-octave basis in a manner spanning the connecting bars91. The ribs92are each formed e.g. of a single steel plate, and extend below the associated sidewall90over substantially the entire length of the chassis assembly81in the front-rear direction such the ribs92do not come into contact with the hammers83.

With the arrangement described above, as a key82is depressed, the rear end of the associated hammer83is pressed downward by the key82, whereby the hammer83is pivoted clockwise, as viewed inFIG. 15, about the hammer supports86. In accordance with the pivotal motion, the front end of the hammer83passes through the first hammer passage hole88from below.

In the above-described conventional keyboard device, the hammer83has the rear end thereof supported by the hammer supports86, with the front end thereof being freely movable in the left-right direction. For this reason, when the electronic piano is stored in a vertically placed position in which the lateral sides thereof are turned into the respective top and bottom sides thereof, the hammer83largely hangs down from the hammer supports86, and there acts large bending moment caused by the weight of the hammer itself including the weight plates89positioned remote from the hammer supports86, so that there is a fear of the hammer83being deformed. If the hammer83is deformed, when the electronic piano is played in its horizontal or normal position, the hammer83passing through the first hammer passage hole88can come into contact with the sidewall90of the first hammer passage hole88, thereby hindering the musical performance.

To eliminate the above-described inconvenience, a method can be contemplated in which the left and right sidewalls90of each first hammer passage hole88are extended downward, as shown inFIGS. 17 and 18, and fixed on the keybed84, for example, for restriction of the lateral motion of the hammer83. In this case however, as shown inFIG. 18, to make the distance between the respective adjacent first hammer passage holes88and88of the opposed boundary portions of the intermediate chassis81aand81aequal to the distance between those of the other portions, it is required to make the respective adjacent outermost sidewalls90aand90aof the two boundary portions thinner than those of the other portions, so that the strength of the sidewalls90aand90ais reduced. Further, since the outermost sidewalls90aare thin and wider than the conventional ones, the sidewalls90aand90aare liable to undergo vibrations e.g. by contact with the associated hammers83, which can cause undesired noise. To eliminate this inconvenience, if the intermediate chassis81aand81aare bonded to each other, this increases the number of manufacturing steps, which increases the manufacturing costs, and makes it difficult to disassemble the chassis assembly81.

Further, since the sidewalls90are extended to the keybed84, there is no space for arranging the ribs92, and hence it is impossible to attach the ribs92to the chassis assembly81. As a result, the rigidity of the chassis assembly81in the front-rear direction is reduced, so that there is a fear of the chassis assembly81being bent e.g. due to the weight of the hammers83, thereby hindering a musical performance. To solve this problem, it can be considered that the ribs92or other reinforcing members are provided at locations other than the locations below the sidewalls90so as to reinforce the chassis assembly81, but in this case, there is a problem of the keyboard device being inevitably increased in size.

SUMMARY OF THE INVENTION

It is a first object of the present invention to provide a keyboard device for a keyboard instrument, which is capable of ensuring sufficient strength of boundary portions of chassis and preventing generation of noise, while restricting lateral motion of hammers.

It is a second object of the present invention to provide a keyboard device for a keyboard instrument, which is capable of sufficiently reinforcing the rigidity of chassis in the front-rear direction while restricting lateral motion of hammers, without increasing the size of the keyboard device.

To attain the first object, in a first aspect of the present invention, there is provided a keyboard device for a keyboard instrument, comprising:

a plurality of chassis arranged side by side in a left-right direction;

a plurality of keys pivotally supported by the chassis;

a plurality of hammers pivotally supported by the chassis, for each being pivotally moved in accordance with depression of an associated one of the keys; and

a plurality of guides formed in the chassis and each having a pair of left and right sidewalls which are opposed to an associated one of the hammers from opposite sides, for restricting lateral motion of the associated one of the hammers,

wherein out of the plurality of guides, one at a boundary of each adjacent two of the chassis has the pair of left and right sidewalls formed by an end sidewall of one of the adjacent two chassis and an end sidewall of the other of the adjacent two chassis.

With the arrangement of the keyboard device according to the first aspect of the present invention, even when the keyboard instrument is placed vertically e.g. for storage, the hammer attempting to hang down in a vertical direction (corresponding to a horizontal direction when the keyboard instrument is in a normal or horizontally placed position) due to its own weight abuts against the lower one of the sidewalls of the guide closely opposed to the hammer, whereby the further downward motion of the hammer is prevented. Thus, the hammer is supported by the sidewall without hardly hanging down, so that bending moment acting on the hammer due to its own weight is reduced, which makes it possible to prevent deformation of the hammer. As a consequence, musical performance on the electronic piano can be carried out without inconvenience when the keyboard instrument is in normal position.

Further, the pair of sidewalls of a guide at the boundary of the adjacent chassis are formed by an end sidewall of one of the chassis and an end sidewall of the other of the same. Therefore, it is possible to secure the same thickness for each of the sidewalls as that of the sidewalls at the other locations than the boundary. This makes it possible to ensure sufficient strength of the guide at the boundary similarly to the other guides. Further, the increased thickness of the sidewalls at the boundary makes the sidewalls difficult to vibrate, which makes it possible to prevent noise from being generated when the hammer is brought into contact with the sidewalls.

Preferably, the plurality of chassis include a plurality of chassis which are identical to each other and each provided as a unit for one octave.

In the keyboard instrument, white keys and black keys are in the same arrangement, and this arrangement is repeated on an octave-by-octave basis. Therefore, with the arrangement of this preferred embodiment, most of chassis can be formed by a plurality of chassis which are identical to each other and each provided as a unit for one octave, so that it is possible to reduce the cost of molds by using the common mold therefor. As a consequence, it is possible to largely reduce the manufacturing costs of chassis, and hence the manufacturing costs of the keyboard device.

Preferably, the guides are integrally formed with the chassis.

With the arrangement of this preferred embodiment, the operation of mounting the guides to the chassis can be dispensed with, which makes it possible to reduce the manufacturing costs of the keyboard device.

More preferably, the chassis are formed by molded articles of a synthetic resin.

With the arrangement of this preferred embodiment, it is possible to easily manufacture the chassis having a desired shape, a strength characteristic without undesired variation, and so forth.

To attain the second object, in a second aspect of the present invention, there is provided a keyboard device for a keyboard instrument, comprising:

a plurality of chassis arranged side by side in a left-right direction;

a plurality of keys pivotally supported by the chassis;

a plurality of hammers arranged side by side in the left-right direction, and pivotally supported by the chassis, for being pivotally moved in accordance with depression of an associated one of the keys; and

a plurality of sidewalls formed in the chassis such that the sidewalls are arranged side by side in the left-right direction at predetermined spaced intervals, each adjacent two of the sidewalls restricting lateral motion of an associated one of the hammers,

wherein at least one of the plurality of sidewalls is removed from each of the chassis, and

wherein the each chassis has a rib mounted therein such that the rib extends in a front-rear direction through a location where the at least one of the plurality of sidewalls is removed, for reinforcing the each chassis as well as for cooperating with two of the sidewalls located leftward and rightward of the rib to restrict lateral motion of an associated one of the hammers.

With the arrangement of the keyboard device for a keyboard instrument, according to the second aspect of the present invention, each chassis is formed with a plurality of sidewalls arranged side by side in the left-right direction, and each adjacent two of the sidewalls restricts lateral motion of an associated one of the hammers. As a result, in a case where the keyboard instrument is placed vertically e.g. for storage, the hammer attempting to hang down in a vertical direction (corresponding to a horizontal direction when the keyboard instrument is in a normal or horizontally placed position) due to its own weight abuts against the lower sidewall, whereby further downward motion of the hammer is prevented. Thus, the hammer is supported by the sidewall without hardly hanging down, so that bending moment acting on the hammer due to its own weight is reduced, which makes it possible to prevent deformation of the hammer. As a consequence, musical performance on the keyboard instrument can be carried out without inconvenience when the electronic keyboard is in normal position.

Further, since at least one of the sidewalls is removed from the chassis, and a rib extending in the front-rear direction is mounted where the sidewall is removed, it is possible to reinforce the rigidity of the chassis in the front-rear direction by the rib. Therefore, there is no need to secure new space for mounting the rib, which makes it possible to prevent the size of the keyboard device from being increased.

Moreover, the rib not only reinforces the rigidity of the chassis, but also cooperates, in place of the removed sidewall, with the sidewalls formed leftward and rightward thereof to restrict the lateral motion of the associated hammer. Since the rib has both the functions of reinforcing the chassis and serving as a sidewall as described above, the number of component parts can be reduced, which contributes to reduction of the manufacturing costs of the keyboard device.

Preferably, the chassis are formed by molded articles of a synthetic resin, with which the plurality of sidewalls are integrally formed, and the rib is formed of a metal.

With the arrangement of this preferred embodiment, the chassis are formed by molded articles of a synthetic resin, and therefore it is possible to easily produce chassis having a desired shape and a strength characteristic without undesired variation. Further, since the sidewalls are integrally formed with the chassis, the operation of mounting the sidewalls on the chassis can be dispensed with, which contributes to reduction of the manufacturing costs of the keyboard device. Furthermore, since the rigidity of the chassis is sufficiently reinforced by the metal rib, even when a large force is applied to the chassis from the key or the hammer, it is possible to prevent distortion of the chassis by the rib. As a consequence, musical performance on the keyboard instrument can be carried out without inconvenience.

More preferably, each of the sidewalls has left and right side surfaces thereof integrally formed with respective guide protrusions extending vertically, and the rib has guide protrusion members attached to left and right side surfaces thereof at respective locations corresponding to the guide protrusions, the guide protrusion members being formed of a synthetic resin and extending vertically.

With the arrangement of this preferred embodiment, even if the hammer laterally moves out of its proper path of motion during musical performance, the hammer comes into contact with only the guide protrusion or the guide protrusion member, which extends vertically and is formed of a synthetic resin, so that an area with which the hammer comes into contact is smaller and hence friction due to the contact is also smaller than when the hammer comes into contact with the sidewall or the side surface of the rib, which makes it possible to prevent degradation of the touch feeling of the key and generation of noise. In particular, since the hammer is prevented from being brought into contact with the rib formed of a metal or the like, generation of metallic sound can be prevented. Further, since the guide protrusions are integrally formed with the respective left and right side surfaces of the sidewall, the operation of attaching the guide protrusions to the sidewalls can be dispensed with, which contributes to reduction of manufacturing costs. Furthermore, since the guide protrusion members are formed of a synthetic resin similarly to the guide protrusions, each guide protrusion member can cooperate with the associated guide protrusion to guide the hammer in a well-balanced manner and prevent the same from being unevenly worn.

Preferably, the plurality of chassis include a plurality of basic chassis which are identical to each other and each provided as a unit for one octave, and the rib is mounted at a predetermined identical location of each of the plurality of basic chassis.

With the arrangement of this preferred embodiment, most of the chassis can be formed by a plurality of basic chassis which are identical to each other and each provided as a unit for one octave. Further, since the rib is mounted at an identical location of each of the plurality of basic chassis, locations of sidewalls to be removed of the basic chassis are also identical to each other. This makes it possible to use a common mold to produce the plurality of basic chassis with identical sidewalls removed, in advance, thereby further reducing the manufacturing costs of the keyboard device.

The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings wherein like reference characters in the various figures are used to designate like components.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 and 2show a keyboard device for an electronic piano, according to a first embodiment of the present invention. The keyboard device1is for use in an 88-key piano, and includes a chassis assembly2, 88 keys 3 comprised of white keys3a(only one which is shown) and black keys3b(only one which is shown) pivotally mounted on the rear end of the chassis assembly2, and hammers4pivotally mounted to the central portion of the chassis assembly2.

The chassis assembly2is constituted by a total of eight chassis: seven basic chassis2a(one of which is shown inFIG. 3, and two of which are shown inFIG. 5), and a chassis2b(seeFIG. 4) for the highest pitch range, and the eight chassis are supported on a keybed5in a state arranged side by side in the left-right direction.

As shown inFIG. 3A, each basic chassis2ais formed with rows of supports and holes, referred to hereinafter, for supporting the keys3and the hammers4. The rows of supports and holes are provided for the respective keys3and arranged side by side in the left-right direction. More specifically, there are formed twelve rows (key-specific rows): a row for an A key to a row for a G# key (hereinafter referred to as “the A-key row”, “the G#-key row”, and so on), i.e. rows for one octave, which are arranged in the mentioned order from the left. Further, as shown inFIG. 5, the basic chassis2ahave the same size and shape, and are formed by injection molded articles of a synthetic resin (ABS resin, for example) which are molded using the same mold. As shown inFIG. 4, the chassis2bfor the highest pitch range is formed by part of one basic chassis2a. More specifically, the chassis2bfor the lowest pith range is formed by a left part of the basic chassis2acut off along line X–X′ inFIG. 3A, and supports a total of four keys3, i.e. an A key to a C key.

The eight chassis are fixed by screws7to four connecting bars6extending in the left-right direction, whereby the chassis2ato2care assembled in a state arranged side by side on the connecting bars6in the left-right direction. Each connecting bar6is a thin angular member having a length covering the entire length of the chassis assembly2in the left-right direction, which is formed e.g. by bending a steel plate.

As shown inFIGS. 3A and 3B, each of the aforementioned rows (key-specific rows) of the basic chassis2ahas key pivot holes8formed in a rear end thereof, for supporting the associated key3, hammer pivot holes9formed in a central portion thereof, first to third hammer passage holes10ato10cformed respectively through a front part and portions frontward and rearward of the hammer pivot holes9, for allowing the associated hammer4in pivotal motion to move therethrough, and a key passage hole12formed at a location rearward of the first hammer passage hole10a, for allowing stopper portions11of the key3in pivotal motion to move therethrough. Further, on the basic chassis2a, there are erected white key guides13aat respective locations frontward of the first hammer passage holes10ain association with the respective white keys3a, and black key guides13bat respective locations rearward of the key passage holes12in association with the respective black keys3b.

Each adjacent pair of the first hammer passage holes10aand10aare separated by a sidewall14. The basic chassis2ais formed with such sidewalls14: one at the left side of an A-key row to one at the right side of a G-key row, such that they have the same thickness and are arranged side by side at identical spaced intervals. As a result, the first hammer passage holes10afor the A-key row to the G-key row are formed through the basic chassis2ain a state arranged side by side at predetermined spaced intervals, and the right side (higher pitch side) of the first hammer passage hole10aof a G#-key row is left open. As shown inFIG. 3B, each sidewall14extends vertically, and has an inverted-triangle shape in side view. Further, the basic chassis2ais provided with a guide-connecting bar15placed on the keybed5, for connecting the lower ends of the sidewalls14, i.e. the sidewall at the left side of the A-key row (hereinafter referred to as “left end sidewall14a”) to the sidewall at the right side of the G-key row (hereinafter referred to as “right end sidewall14b”), to each other. Further, the left and right side surfaces of each sidewall14are each formed with a guide protrusion16semi-circular in cross-section, which continuously extends from the guide-connecting bar15to the upper end of the sidewall14. The sidewalls14and14at the opposite sides of each first hammer passage hole10aand the guide protrusions16and16at the respective inner sides of these sidewalls14and14form a guide17for restricting the lateral motion of the hammer4. The guide-connecting bar15and the guide protrusions16are integrally formed with the basic chassis2a, and arranged slightly forward of the center of the first hammer passage hole10a.

Further, as shown inFIG. 6, the right end sidewall14bis disposed inward of the right end of the basic chassis2a, and a rear wall14cassociated therewith of the first hammer passage hole10aextends rightward, i.e. toward the G#-key row, by a length of approximately two thirds of the width of the first hammer passage hole10a, and a front wall14dassociated therewith of the first hammer passage hole10aextends rightward by a length of approximately half the width of the first hammer passage hole10a. On the other hand, the left end sidewall14ais disposed flush with the left end of the basic chassis2a, and the left end of a rear wall14cassociated therewith is flush with the left end sidewall14a, and a front14dassociated therewith extends leftward by a length of approximately half the width of the first hammer passage hole10a.

With the above arrangement, as shown inFIGS. 5 and 6, when basic chassis2aand2aare connected to each other, the right end sidewall14bof the basic chassis2aon the left side and the left end sidewall14aof the basic chassis2aon the right side are opposed to each other at the same distance as that between the sidewalls14and14of each of the first hammer passage holes10aother than that of the G#-key row, and the left end sidewall14aand the right end sidewall14bdefine the first hammer passage hole10afor the G#-key row at the boundary of the basic chassis2a. Similarly, between a basic chassis2aand the chassis2bfor the highest pitch range, a first hammer passage hole10afor a G#-key row is defined, and a guide17for guiding the hammer4associated with a G# key is formed by the left end sidewall14aand the right end sidewall14bof theses chassis and the protrusions16and16on the inner side surfaces of these sidewalls.

Further, as shown inFIG. 1, the chassis assembly2is provided with a white-key lower limit stopper21a,a black-key lower limit stopper21b, a key upper limit stopper22, a hammer lower limit stopper23, and a hammer upper limit stopper24, for restricting pivotal motions of the keys3and the hammers4. The black-key lower limit stopper21band the key upper limit stopper22are attached to the upper and lower surfaces of the chassis assembly2, respectively, at the same location between a lateral row of the key passage holes12and a lateral row of the associated black key guides13b,such that they sandwich the chassis assembly2. The hammer lower limit stopper23is attached to the lower end portion of the front connecting bar6. Further, the white-key lower limit stopper21a and the hammer upper limit stopper24are attached to the upper and lower surfaces of the chassis assembly2, respectively, at a location rearward of a lateral row of the white key guides13asuch that they sandwich the chassis assembly2. Each of the stoppers21to24is formed of a belt-like cushioning member extending over the entire length of the chassis assembly2in the left-right direction.

Further, at a location rearward of each pair of hammer pivot holes9, a key switch25is provided on the chassis assembly2, for detecting key-on information of the associated key3. The key switch25is comprised of a printed circuit board26fixed to the chassis assembly2by screws and a switch body27disposed on the top of the printed circuit board26. The switch body27faces the associated third hammer passage hole10cfrom below, and is connected to a control unit (not shown) for controlling tone generation of the electronic piano, via the printed circuit board26.

Each of the keys3(the white keys3aand the black keys3b) is formed e.g. by an injection molded article of an AS resin, and is comprised of two sidewalls3c(only one of which is shown) and a top wall3d, with an inverted U-shaped cross-section. Each of the sidewalls3cof the key3has a rear end thereof formed with a protrusion31protruding inward, and the protrusion31is fitted into the associated key pivot hole8formed in the rear end of the chassis assembly2, whereby the key3is pivotally supported by the chassis assembly2. Further, the key3is formed with the stopper portions11which are hook-shaped and extend downward from the front portions of the two sidewalls3c, respectively.

On the other hand, each hammer4is comprised of a hammer body32extending in the front-rear direction and two weight plates33(only one of which is shown) attached to the respective left and right side surfaces of the front end of the hammer body32. The hammer body32has a rear end thereof formed with pin-shaped protrusions34laterally protruding from the respective opposite side surfaces. The protrusions34are engaged in the respective adjacent hammer pivot holes9formed at the boundary of each adjacent two of the aforementioned rows (key-specific rows) of the chassis assembly2such that they span the adjacent two hammer pivot holes9, whereby the hammer4is pivotally supported by the chassis assembly2. The weight plates33, which are provided for adding touch weight similar to that of an acoustic piano to the hammer4, are formed of a heavy material, such as a steel plate. Further, each weight plate33has a rectangular cushioning member38attached to a lower portion of a side surface thereof at a location corresponding to the guide protrusion16. The cushioning member38serves to make the weight plate33slidable and prevent generation of noise when the weight plate33comes into contact with the guide protrusion16.

A portion of the hammer body32rearward of the hammer pivot holes9forms a switch pressing portion35. The switch pressing portion35is positioned in facing relation to the associated third hammer passage hole10cof the chassis assembly2, and opposed to the switch body27of the key switch25from above. An actuator portion36formed on the lower surface of the key3is in abutment from above with the switch pressing portion35. Further, the central portion of the hammer4passes through the associated second hammer passage hole10bof the chassis assembly2in a manner crossing the same from above and extends forward below the chassis assembly2, and the front end of the hammer4is formed with a hammer stopper portion37protruding forward.

With the arrangement described above, as a key3is depressed, the switch pressing portion35of the hammer4is pressed by the actuator portion36of the key3to cause the hammer4to pivotally move clockwise, as viewed inFIG. 1, and the weight plates33attached to the front end of the hammer4move through the first hammer passage hole10afrom below. During this operation, the lateral motion of the hammer4is restricted by the sidewalls14and the guide protrusions16of the guide17.

In accordance with the pivotal motion of the hammer4, the switch pressing portion35depresses the switch body27of the key switch25to turn on the same. As a result, key-on information of the key3is detected, and the tone generation of the electronic piano is controlled based on the result of the detection.

As described above, with the arrangement of the keyboard device1for an electronic piano, according to the present embodiment, it is possible to restrict the lateral motion of the hammer4by the guide17provided in the front end of the chassis assembly2. Therefore, when the electronic piano is placed vertically e.g. for storage, the guide17can prevent the hammer4from hanging down due to its own weight. Thus, the hammer4is supported by the guide17without hardly hanging down, and hence bending moment acting on the hammer4due to its own weight is reduced, which makes it possible to prevent deformation of the hammer4. As a consequence, musical performance on the electronic piano can be carried out without inconvenience when the electronic piano is in normal position. Further, even if the hammer4laterally moves out of its proper path of motion during musical performance, the hammer4comes into contact with only the guide protrusion16semicircular in cross section and extending vertically, so that an area with which the hammer4comes into contact is smaller and hence friction due to contact is also smaller than when the hammer4comes into contact with the sidewall14, which is larger in area. This makes it possible to prevent degradation of the touch feeling of the key3and generation of noise.

Further, since the guide17of the hammer4for the G# key at the boundary between a basic chassis2aand an adjacent basic chassis2aor the chassis2bfor the highest pitch range is formed by the left end sidewall14aof one of the chassis and the right end sidewall14bof the other of the same, it is possible to secure the same thickness for each of the sidewalls14aand14bas that of the sidewalls at the other locations than the boundary. This makes it possible to ensure sufficient strength of the guide17at the boundary similarly to the other guides17. Further, the increased thickness of the sidewall14sat the boundary makes the sidewalls14difficult to deform and vibrate, which makes it possible to prevent noise from being generated when the hammer4is brought into contact with the sidewall14. As a consequence, it becomes unnecessary to perform the process of bonding the boundary portions of the chassis2for prevention of generation of noise, which reduces the number of manufacturing steps, and makes it easy to decompose the chassis2.

Further, since the basic chassis2aare each formed by an identical unit for one octave, it is possible to reduce the cost of molds by using the common mold therefor. Further, for an 88-key electronic piano of a normal type, the chassis assembly2can be formed by seven basic chassis2aand one chassis2bfor the highest pitch range, which dispenses with the conventional chassis for the lowest pitch range. Further, since the sidewalls14and the guide protrusions16forming each guide7are integrally formed with the chassis assembly2, the operation of mounting the guides7to the chassis2can be dispensed with. From the above, it is possible to reduce the manufacturing costs of the electronic piano. Further, since the basic chassis2ais formed by a molded article of a synthetic resin, such as an ABS resin, it is possible to manufacture the basic chassis2ahaving a desired shape and a strength characteristic without undesired variation.

Next, a keyboard device for a keyboard instrument, according to a second embodiment of the present invention will be described in detail with reference toFIGS. 7 to 14.

FIGS. 7 and 8show a keyboard device for an electronic piano, according to the second embodiment of the present invention. The keyboard device1′ is for use in an 88-key piano, and includes a chassis assembly2′, 88 keys3comprised of white keys3a(only one which is shown) and black keys3b(only one which is shown) pivotally mounted on the rear end of the chassis assembly2′, and hammers4pivotally mounted to the central portion of the chassis assembly2′.

The chassis assembly2′ is constituted by a total of eight chassis: six basic chassis2a′ (only one of which is shown inFIG. 9A), a chassis2c, shown inFIG. 13, for the lowest pitch range, and a chassis2b′, shown inFIG. 14, for the highest pitch range, and the eight chassis are supported on a keybed5in a state arranged side by side in the left-right direction.

As shown inFIG. 9A, each basic chassis2a′ is formed with rows of supports and holes, referred to hereinafter, for supporting the keys3and the hammers4. The rows of supports and holes are provided for the respective keys3and arranged side by side in the left-right direction. More specifically, there are formed twelve rows: a row for an F key to a row for an E key (hereinafter referred to as “the F-key row”, “the E-key row”, and so on), i.e. rows for one octave, which are arranged in the mentioned order from the left, with the associated key3and hammer4mounted therein. Further, the basic chassis2a′ have the same size and shape, and are formed by injection molded articles of a synthetic resin (ABS resin, for example), which are molded using the same mold.

As shown inFIGS. 13 and 14, the chassis2b′ for the highest pitch range and the chassis2cfor the lowest pitch range are each formed by part of the basic chassis2a′. More specifically, the chassis2b′ for the highest pitch range is formed by a right part of the basic chassis2a′ cut off along line X–X′ inFIG. 9A. On the other hand, the chassis2cfor the lowest pitch range is formed by a left part of the basic chassis2a′ cut off along line Y–Y′ inFIG. 9A.

The eight chassis2ato2care fixed by screws7inserted through the chassis assembly2′ from above to four connecting bars6extending below the chassis assembly2′ in the left-right direction, as shown inFIG. 7, whereby the chassis2ato2care assembled in a state arranged side by side on the connecting bars6in the left-right direction. It should be noted that only the second connecting bar6as counted from the rear of the chassis assembly2′ (right-hand side as viewed inFIG. 7) is fixed to the chassis assembly2′ from below by the screws7. Each connecting bar6is a thin angular member having a length covering the entire length of the chassis assembly2′ in the left-right direction, which has a plurality of holes (not shown) formed therethrough and is formed e.g. by bending a steel plate.

As shown inFIGS. 9A and 9B, each of the aforementioned rows (key-specific lows) of the basic chassis2a′ has key pivot holes8formed in a rear end thereof, for supporting the associated key3, hammer pivot holes9formed in a central portion thereof, first to third hammer passage holes10ato10cformed respectively through a front part and portions frontward and rearward of the hammer pivot holes9, for allowing the associated hammer4in pivotal motion to move therethrough, and a key passage hole12formed at a location rearward of the first hammer passage hole10a, for allowing stopper portions11of the key3in pivotal motion to move therethrough. Further, on the basic chassis2a′, there are erected white key guides13aat locations frontward of the respective first hammer passage holes10ain association with the respective white keys3a, and black key guides13bat locations rearward of the respective key passage holes12in association with the respective black keys3b.

In the front end of the basic chassis2a′, there are formed twelve sidewalls14such that they are arranged side by side in the left-right direction at equally-spaced intervals, and each of the first hammer passage holes10ais defined between each adjacent two of the sidewalls14and14. A portion of the basic chassis2a′ between the B-key row and C-key row is formed with no sidewalls14, and in this portion, there is mounted a rib41, referred to hereinafter, in place of the sidewall14. Between the rib41and the respective sidewalls14leftward and rightward of the rib41, there are formed first hammer passage holes10a.

Further, leftmost and rightmost sidewalls (hereinafter referred to as “the end sidewalls14a/b”) of the plurality of the sidewalls14are formed such that they have approximately half the thickness of the other sidewalls14. One of the end sidewalls14a/band an end sidewall14a/bof an adjacent chassis connected to the basic chassis2a′ form one sidewall14. As a consequence, the first hammer passage holes10aare formed such that they are arranged side by side in the left-right direction at predetermined spaced intervals over the entire length of the chassis assembly2′.

As shown inFIG. 9B, the sidewalls14are integrally formed with the basic chassis2a′ and each extend vertically with an inverted triangular shape in side view. Further, the basic chassis2a′ is formed with two guide-connecting bars15: one for connecting the respective lower ends of sidewalls14, i.e. a left end sidewall14a/bto the left-side sidewall14of a B-key row, and the other for connecting the respective lower ends of sidewalls14, i.e. the right-side sidewall14of a C-key row to a right end sidewall14a/b. The two guide-connecting bars15extend on the same straight line, and are placed on the keybed5. Further, on the left and right side surfaces of each sidewall14and the inner side surface of each end sidewall14a/b, there extend respective guide protrusions16, semicircular in cross section, continuously from the guide-connecting bar15to the upper end of the sidewall14. The guide-connecting bars15and the guide protrusions16are integrally formed with the basic chassis2a′, and each located slightly forward of the center of the first hammer passage hole10a. Except for the B-key row and the C-key row, the sidewalls14and14on the opposite sides of the first hammer passage hole10aand the respective guide protrusions16and16on the inner side surfaces of the sidewalls14and14form a guide17for restricting the lateral motion of the hammer4.

Further, a portion of the basic chassis2a′ corresponding to the B-key row has four rib fixing holes18formed at respective locations corresponding to the four connecting bars6(seeFIG. 13) such that they are aligned in the front-rear direction. As shown inFIG. 10, the basic chassis2a′ has a reinforcing rib41mounted thereon via the rib fixing holes18, and the rib41extends in the front-rear direction between the B-key row and the C-key row. As shown inFIGS. 12A and 12B, the rib41is comprised of a rib body42extending in the front-rear direction, and guide protrusion members46mounted on the rib body42. The rib body42is formed e.g. by press bending of a steel plate such that it has the same thickness as that of the sidewall14. Further, the rib body42has the upper end thereof formed with four horizontal mounting portions43at respective predetermined locations spaced in the front-rear direction. Each mounting portion43is formed therethrough with a mounting hole44. The screws7are screwed into the respective rib fixing holes18of the basic chassis2a′ from below via the mounting holes44of the rib41and the respective holes of the associated connecting bars6, as shown inFIG. 7, whereby the rib41is mounted to the basic chassis2a′.

Further, a portion of the rib body42close to the front end thereof protrudes upward to form a hammer guide portion45. The hammer guide portion45, which plays the role of the sidewall14between the B-key row and the C-key row, has the same height as the sidewall14as shown inFIG. 7, and has left and right side surfaces thereof formed with a plurality of mounting holes (not shown).

As shown inFIGS. 11 and 12Aand12B, each guide protrusion member46is a rectangular plate extending vertically, and has a guide protrusion47integrally formed therewith which extends vertically in a central portion thereof. The guide protrusion member46is formed of the same synthetic resin as the guide protrusion16. The guide protrusion member46has the same height as the hammer guide portion45, and has a plurality of mounting protrusions (not shown) protruding from an opposite surface thereof to the guide protrusion47. These plurality of protrusions are fitted into the associated holes of the hammer guide portion45, respectively, whereby the guide protrusion member46is fixed to the hammer guide portion45. In this state, the respective guide protrusions47and47of the guide protrusion members46and46are opposed, respectively, to the respective guide protrusions16and16of the left and right sidewalls14and14. Further, the protruding length of the guide protrusion47from the rib41is equal to the protruding length of the guide protrusion16from the sidewall14.

As shown inFIG. 11, the first hammer passage holes10ain the respective B-key row and C-key row are formed between the rib41mounted as above and the sidewalls14and14on the left and right sides thereof. In the B-key row and the C-key row, these sidewalls14and the hammer guide portion45, and the guide protrusions16on the respective inner surfaces of the sidewalls14and the guide protrusion members46(including the guide protrusions47) on the opposite sides of the hammer guide portion45form two guides17for respectively restricting the lateral motion of the hammers4associated therewith.

Also in each of the chassis2b′ for the highest pitch range and the chassis2cfor the lowest pitch range, a rib41is mounted between a B-key row and a C-key row, and a guide17is formed as in the case of the basic chassis2a′.

Further, as shown inFIG. 7, the chassis assembly2′ is provided with a white-key lower limit stopper21a,a black-key lower limit stopper21b, a key upper limit stopper22, a hammer lower limit stopper23, and a hammer upper limit stopper24, for restricting pivotal motions of the keys3and the hammers4. The black-key lower limit stopper21band the key upper limit stopper22are attached to the upper and lower surfaces of the chassis assembly2′, respectively, at the same location between a lateral row of the key passage holes12and a lateral row of the associated black key guides13b,such that they sandwich the chassis assembly2′. The hammer lower limit stopper23is attached to the lower end portion of the front connecting bar6. Further, the white-key lower limit stopper21aand the hammer upper limit stopper24are attached to the upper and lower surfaces of the chassis assembly2′, respectively, at a location rearward of a lateral row of the white key guides13asuch that they sandwich the chassis assembly2′. Each of the stoppers21to24is formed of a belt-like cushioning member extending over the entire length of the chassis assembly2′ in the left-right direction.

Further, at a location rearward of each pair of hammer pivot holes9, a key switch25is provided on the chassis assembly2′, for detecting key-on information of the associated key3. The key switch25is comprised of a printed circuit board26fixed to the chassis assembly2′ by screws and a switch body27disposed on the top of the printed circuit board26. The switch body27faces the associated third hammer passage hole10cfrom below, and is connected to a control unit (not shown) for controlling tone generation of the electronic piano, via the printed circuit board26.

Each of the keys3(the white keys3aand the black keys3b) is formed e.g. by an injection molded article of an AS resin, and is comprised of two sidewalls3c(only one of which is shown) and a top wall3d, with an inverted U-shaped cross-section. Each of the sidewalls3cof the key3has a rear end thereof formed with a protrusion31protruding inward, and the protrusion31is fitted into the associated key pivot hole8formed in the rear end of the chassis assembly2′, whereby the key3is pivotally supported by the chassis assembly2′. Further, the key3is formed with the stopper portions11which are hook-shaped and extend downward from the front portions of the two sidewalls3c, respectively.

On the other hand, each hammer4is comprised of a hammer body32extending in the front-rear direction and two weight plates33(only one of which is shown) attached to the respective left and right side surfaces of the front end of the hammer body32. The hammer body32has a rear end thereof formed with pin-shaped protrusions34laterally protruding from the respective opposite side surfaces. The protrusions34are engaged in the respective adjacent hammer pivot holes9formed at the boundary of each adjacent two rows of the chassis assembly2′ such that they span the adjacent two hammer pivot holes9, whereby the hammer4is pivotally supported by the chassis assembly2′. The weight plates33, which are provided for adding touch weight similar to that of an acoustic piano to the hammer4, are formed of a heavy material, such as a steel plate. Further, each weight plate33has a rectangular cushioning member38attached to a lower portion of a side surface thereof at a location corresponding to the guide protrusion16and the guide protrusion member46. The cushioning member38serves to make the weight plate33slidable and prevent generation of noise when the weight plate33comes into contact with the guide protrusion16or the guide protrusion47.

A portion of the hammer body32rearward of the hammer pivot holes9forms a switch pressing portion35. The switch pressing portion35is positioned in facing relation to the associated third hammer passage hole10cof the chassis assembly2′, and opposed to the switch body27of the key switch25from above. An actuator portion36formed on the lower surface of the key3is in abutment from above with the switch pressing portion35. Further, the central portion of the hammer4passes through the associated second hammer passage hole10bof the chassis assembly2′ in a manner crossing the same from above and extends forward below the chassis assembly2′, and a front end of the hammer4is formed with a hammer stopper portion37protruding forward.

With the arrangement described above, as a key3is depressed, the switch pressing portion35of the hammer4is pressed by the actuator portion36of the key3to cause the hammer4to pivotally move clockwise, as viewed inFIG. 7, and the weight plates33attached to the front end of the hammer4move through the first hammer passage hole10afrom below. During this operation, the lateral motion of the hammer4is restricted by the guide17. More specifically, the motion is restricted by the sidewalls14, the hammer guide portion45, the guide protrusions16, and the guide protrusion member46including the guide protrusion47.

In accordance with the pivotal motion of the hammer4, the switch pressing portion35depresses the switch body27of the key switch25to turn on the same. As a result, key-on information of the key3is detected, and the tone generation of the electronic piano is controlled based on the result of the detection.

As described above, according to the keyboard device1′ for an electronic piano, according to the present embodiment, it is possible to restrict the lateral motion of the hammer4by the guide17provided in the front end of the chassis assembly2′. Therefore, when the electronic piano is placed vertically e.g. for storage, the guide17can prevent the hammer4from hanging down due to its own weight. Thus, the hammer4is supported by the guide17without hardly hanging down, and hence bending moment acting on the hammer4due to its own weight is reduced, which makes it possible to prevent deformation of the hammer. As a consequence, musical performance on the electronic piano can be carried out without inconvenience. Further, even if the hammer4laterally moves out of its proper path of motion during musical performance, the hammer4comes into contact with only the guide protrusion16semicircular in cross section and extending vertically or the guide protrusion47, so that an area with which the hammer4comes into contact is smaller and hence friction due to contact is also smaller than when the hammer4comes into contact with the sidewall14or the hammer guide portion45, which is larger in area than the guide protrusion16or47, which makes it possible to prevent degradation of the touch feeling of the key3and generation of noise. In particular, since the steel weight plates33of the hammer4do not come into contact with the rib41formed of a steel plate, generation of metallic sound can be prevented.

Similarly to the guide protrusion16, the guide protrusion member46including the guide protrusion47is formed of a synthetic resin, so that the guide the guide protrusion47can cooperate with the guide protrusion16to guide the hammer4in a well-balanced manner and prevent the same from being unevenly worn.

Further, since the rib41is disposed such that it extends in the front-rear direction between the B-key row and the C-key row of each chassis at a location where the sidewall14is removed, the rigidity of the chassis assembly2′ in the front-rear direction can be reinforced. Therefore, even when a large force is applied to the chassis from a key3or a hammer4, it is possible to prevent distortion of the chassis by the rib41which is formed of a steel plate. Furthermore, there is no need to secure new space for mounting the ribs41, which makes it possible to prevent the size of the keyboard device1′ from being increased.

The rib41not only reinforces the rigidity of the chassis, but also cooperates, in place of the removed sidewall14, with the sidewalls14formed on the respective left and right sides thereof, to restrict the lateral motion of the associated hammer4. Since the rib41has both the functions of reinforcing the chassis and serving as a sidewall14as described above, the number of component parts can be reduced, which contributes to reduction of the manufacturing costs of the keyboard device1′.

Further, since the sidewalls14, the guide-connecting bar15, and the guide protrusions16are integrally formed with the chassis2a′,2b′ and2c, the operation of mounting these on the chassis2a′,2b′ and2c, can be dispensed with, which contributes to reduction of the manufacturing costs. Moreover, since each chassis is formed by a synthetic resin molded article, it is possible to easily produce a chassis assembly2′ having a desired shape and a strength characteristic without undesired variation.

Moreover, since each of the basic chassis2a′ is designed to have the rib41mounted between the B-key row and the C-key row, it is possible to produce basic chassis2a′ each as a unit for an octave, in which the sidewall14between the B-key row and C-key row is removed in advance. Therefore, a common mold can be used to produce the basic chassis2a′. Further, the chassis2b′ for the highest pitch range and the chassis2cfor the lowest pitch range are produced by cutting off the basic chassis2a′ along the respective predetermined lines. Therefore, all the chassis2ato2ccan be produced using the single common mold, which makes it possible to further reduce the manufacturing costs of the keyboard device1′.

It should be noted that the present invention is by no means limited to the embodiments described above, but can be practiced in various ways. For example, although in the first embodiment, the guides17are integrally formed with the basic chassis2aand the like, the guides17may be formed separately from the basic chassis2aand the like, and then attached to the same. Further, although in the second embodiment, each guide protrusion member46is fixed by being fitted in the hammer guide portion45, an adhesive may be used to fix the same. Further, the material for the guide protrusion member46is not limited to a synthetic resin, but may be formed of rubber, for example. Furthermore, it is possible to remove the sidewall14and mount the rib41at a location other than the location between the B-key row and the C-key row, which is shown by way of example in the second embodiment. For example, it is possible to remove the left and right end sidewalls14a/band14a/bof the basic chassis2aand mount the ribs41at the respective locations. Moreover, although the above-described embodiments are examples of application of the present invention to the electronic piano, this is not limitative, but it goes without saying that the present invention can be applied to electronic musical instruments of other types, such as a synthesizer.

It is further understood by those skilled in the art that the foregoing is a preferred embodiment of the invention, and that various changes and modifications may be made without departing from the spirit and scope thereof.