Keyboard assembly for electronic musical instrument

A keyboard assembly for an electronic musical instrument comprises an integrally formed multikey unit and a keyboard frame. The multikey unit has a plurality of juxtaposed key bodies and is comprised of three subunits, a sharp key subunit, a C-E-G-B key subunit and a D-F-A key subunit, which are complementary to each other to provide a key unit for a complete one octave. The rear end of each of the key body is extended downward to form a deformable thickness-reduced member to allow a vertical swing of the key body when depressed by a player. The thickness-reduced members are connected into a common connecting member to horizontally align the key bodies in the direction of juxtaposition. The keyboard frame has a vertical rear wall member and a rear top wall member both extending in the direction of the key body alignment, and guide ribs connecting the rear top wall member and the vertical rear wall member. In assembling, the common connecting member is first placed over the rear top wall member, thereafter is slid along the guide ribs, and is temporarily held at the correct position just behind the vertical rear wall member, before being fixed to the vertical rear wall member.

TECHNICAL FIELD

The present invention relates to a keyboard assembly for an electronic musical instrument such as an electronic organ or an electronic piano in which the total depth (front to rear length) of the keyboard assembly is contrived to be minimal in view of the length of the playing areas of the keys.

BACKGROUND INFORMATION

In the field of electronic keyboard musical instruments and the like keyboard musical instruments, there have been known such keyboard assemblies as have a plurality of playing keys which are formed of a resin material and are swingably supported at their rear ends by a keyboard frame, as shown, for example, in unexamined Japanese patent publication No. 2001-215968. In such a keyboard assembly, each of a plurality of playing keys has a key body to be depressed by a player and an elastically deformable thickness-reduced member integrally extending vertically downward from the rear end of each key body, and the plurality of thickness-reduced members (for the plurality of key bodies each) are integrally connected to a common connecting member to horizontally align the key bodies in the direction of juxtaposition to constitute a multikey unit. The keyboard frame, on the other hand, has a vertical rear wall member to which is fixed the common connecting member of the multikey unit. Such a configuration is advantageous in minimizing the total depth of the keyboard assembly.

In such a conventional keyboard assembly, however, as the rear top wall member and the vertical rear wall member are formed perpendicular to each other, the configuration is disadvantageous in assembling the multikey unit to the keyboard frame, as the lower edge of the common connecting member of the multikey unit may bump against and be caught on the rear top wall member when the multikey unit is being mounted on the keyboard frame. Particularly in the case of a keyboard assembly which has swing mechanisms (e.g. swing weights) to simulate the key touch feeling of an acoustic piano, each of the key bodies is provided with an actuating member to actuate the associated swing mechanism, and accordingly the actuating members have to be engaged with the swing mechanisms in the course of mounting the multikey unit onto the keyboard frame. Such a procedure is likely to cause the lower edge of the common connecting member to bump against and be caught on the rear end of the rear top wall member. And further, the conventional keyboard assembly does not have a particular structure for accurately positioning the common connecting member during the assemblage of the multikey unit and the keyboard frame.

SUMMARY OF THE INVENTION

The present invention is, therefore, made to solve the aforementioned problems, and accordingly its primary object is to provide a keyboard assembly for an electronic musical instrument wherein the multikey unit can be easily assembled onto the keyboard frame.

According to the present invention, the object is accomplished by providing a keyboard assembly for an electronic musical instrument comprising: an integrally formed multikey unit having a plurality of juxtaposed key bodies each of which is extended downward from its rear end to form a deformable thickness-reduced member to allow vertical swing of the key body when depressed by a player, and having a common connecting member to which is connected the thickness-reduced members to horizontally align the key bodies in the direction of juxtaposition; and a keyboard frame having a vertical rear wall member and a rear top wall member positioned in front of and above the vertical rear wall member, the vertical rear wall member and the rear top wall member extending in the direction of the key body alignment, wherein the keyboard frame is provided with a guide member connecting the rear top wall member and the vertical rear wall member, whereby the multikey unit is to be mounted onto the keyboard frame by placing the common connecting member over the rear top wall member, thereafter sliding the common connecting member along the guide member, and finally fixing the common connecting member to the vertical rear wall member. In the above-mentioned structure, the guide member may preferably be provided in the form of ribs between the rear end of the rear top member and the top end of the vertical rear wall member. Alternatively, the guide member may be provided in the form of a slant wall connecting the rear end of the rear top member and the top end of the vertical rear wall member.

With the present invention configured as above, the multikey unit is smoothly mounted onto the keyboard frame, as the common connecting member slides along the guide member and is led to the vertical rear wall member. Thus the lower edge of the common connecting member will not be caught by the rear top wall of the keyboard frame in the course of mounting. This facilitates the process of assembling the multikey unit onto the keyboard frame.

In an aspect of the present invention, a first protrusion may be provided on the vertical rear wall member protruding rearward therefrom, wherein the common connecting member abuts against the first protrusion when the multikey unit is mounted onto the keyboard frame. With this configuration, when the multikey unit is mounted on the keyboard frame, the lower edge of the common connecting member abuts against the first protrusion so that the common connecting member is temporarily held at a determined position for fixing. This will eliminate the need of a jig or a measuring device for determining the position of the common connecting member before final fixing, thus facilitating the assembling process of the multikey unit onto the keyboard frame.

In another aspect of the invention, the common connecting member may have a cutaway provided from the lower edge of the common connecting member to engage with the first protrusion when the common connecting member is fixed to the vertical rear wall member. In this aspect, the first protrusion may preferably be configured in the form of a boss for fixing the common connecting member to the vertical rear wall member. Then, by engaging the cutaway with the first protrusion, not only the vertical position but also the horizontal position of the common connecting member can be determined correctly. Where the first protrusion for determining the fixing position is configured in the form of a boss for fixing the multikey unit onto the keyboard frame, the structure of the keyboard frame will be simplified.

In a further aspect of the present invention, a second protrusion may be provided on the vertical rear wall member protruding rearward therefrom in the form of a ridge extending on the vertical rear wall member in the direction of the key body alignment, while the common connecting member may be provided with a groove to match the second protrusion, so that the groove in the common connecting member will engage with the second protrusion on the vertical rear wall member in the process of fixing the common connecting member to the vertical rear wall member. This configuration will secure the correct vertical positioning of the common connecting member with respect to the vertical rear wall member in fixing the common connecting member to the vertical rear wall member by engaging the groove of the common connecting member with the second protrusion of the vertical rear wall member. In other words, this will eliminate the need of a jig or a measuring device for finally determining the position of the common connecting member to fix to the vertical rear wall member, thus facilitating the assembling process of the multikey unit onto the keyboard frame.

In a still further aspect of the present invention, the second protrusion may be protruded from the vertical rear wall member by an amount which is smaller than the thickness of the common connecting member. With this configuration, the thickness of the wall members of the keyboard frame can be made virtually uniform without a need of providing the keyboard frame with some thickness reductions (hollows) for improving the formability of the keyboard frame. This will simplify the structure of the mold for forming the keyboard frame and will reduce the manufacturing cost.

In a still further aspect of the present invention, the second protrusion may have a certain length of part extending in the direction of the key alignment which part is formed to have a horizontal surface area. In general, if the keyboard frame should be integrally molded from resin, the second protrusion would be shaped with a draft so that the upper surface of the second protrusion would descend toward the tip of the protrusion. Thus, if the multikey unit would move rearward to some extent during the process of fixing the common connecting member to the vertical rear wall member of the keyboard frame, the common connecting member would likely to slip off from the second protrusion. But with the above-mentioned configuration according to the present invention in which a certain length of part of the second protrusion is formed to have a horizontal surface area extending in the direction of the key alignment, the common connecting member would not easily slip off the second protrusion, even if the multikey unit might move rearward by some amount. Thus, this configuration will facilitate the procedure of fixing the common connecting member to the vertical rear wall member of the keyboard frame.

In a still further aspect of the present invention, the keyboard assembly can be provided with swing members which are supported by the keyboard frame, linked to the individual key bodies, respectively, and each of which swings according to the depression of each associated key body in order to simulate a key touch feeling of an acoustic piano. The configuration of the present invention will facilitate the procedure of assembling the multikey unit with the keyboard frame containing the swing members, while conventional configurations without the present invention would cause some difficulty in assembling the multikey unit onto the keyboard frame.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention will now be described in detail with reference to the drawings showing preferred embodiments thereof. It should, however, be understood that the illustrated embodiments are merely examples for the purpose of understanding the invention, and should not be taken as limiting the scope of the invention.

In the following description, the front side of the keyboard assembly means the side directing toward the player (leftward inFIG. 1a), the rear side means the side directing away from the player (rightward inFIG. 1a), the right side means the side directing rightward of the player (front of the paper inFIG. 1a), the left side means the side directing leftward of the player (back of the paper inFIG. 1a), the up side means the side directing upward vertically (upper direction of the paper inFIG. 1a), and the down side means the side directing downward vertically (lower direction of the paper inFIG. 1a). The right-to-left direction as viewed by the player is termed herein the width direction, and the front-to-rear direction the depth direction.

FIG. 1ais a right side view of a keyboard assembly in its assembled position according to an embodiment of the present invention, andFIG. 1bis a rear view of the keyboard assembly ofFIG. 1a. The keyboard assembly comprises a keyboard frame20and a multikey unit10A,10B,10C having a plurality of music playing keys fixed at their rear end parts to the keyboard frame20. The multikey unit is comprised of three multikey subunits10A,10B and10C as shown inFIGS. 2aand2bby exploded perspective and right side views, respectively. The multikey subunit10A has a C# key, a D# key, an F# key, a G# key and an A# key integrally formed of resin material. The multikey subunit10B has a C key, an E key, a G key and a B key integrally formed of resin material. The multikey subunit10C has a D key, an F key and an A key integrally formed of resin material. While the shown examples of the multikey subunits are formed with particular combinations of several playing keys included within an octave, the combination and the range of the keys may not necessarily be limited to the shown examples, but may be arbitrarily selected.

Each of the multikey subunits10A,10B,10C has a plurality of juxtaposed key bodies11, thickness-reduced members12and a common connecting member13, all formed integrally of resin material. The key body is a part of the key to be depressed by the player formed in the shape of a downward open hollow box having an elongate thin top wall member extending from front to rear, thin side wall members extending downward from the right and left edges of the top wall member, and a thin front member and a thin rear member extending downward from the front and rear ends of the top wall member. The thickness-reduced member12has a reduced thickness in the depth direction, and vertically extends downward from the rear wall member of the key body11. The thickness-reduced member12may not necessarily be extended downward vertically from the rear wall member of the key body11, but may be extended downward anyway from the rear part of the key body11. The thickness-reduced member12is elastically deformable to allow vertical swing of the key body11when depressed by the player.

The common-connecting member13is formed in a shape which is elongate in the width direction and relatively thin in the depth direction, having a top end to which are connected the respective bottom ends of the thickness-reduced members12. The common-connecting member13is provided with three cutaways13ain a reversed U-shape (open downward) penetrating in the depth (thickness) direction of the common-connecting member13. The three cutaways13aare provided at the left end, center and right end regions of the common-connecting member13, each commonly corresponding among the three multikey subunit10A,10B and10C to each other. The reverse U-shape has an upper semicircle and a lower rectangle opening having a width equal to the diameter of the semicircle. All the cutaways13aare open downward. The central cutaway13has the width of the opening a bit smaller than the width of the opening of the other cutaways13.

Each of the common-connecting members13has a groove or channel13bof a predetermined width (height as viewed by the player) extending along the length (in the width direction as viewed by the player) on the front surface of the member13, and a ridge or rail13cof a predetermined width extending along the length on the rear surface of the member13. The width of the groove13bon the multikey subunit10C is made equal to the width of a rib20a2to be described herein later, and the width of the ridge13cof the multikey subunit10C is determined based on the width of its groove13bso that the common-connecting member13is formed in a uniform thickness. As will be described herein later, the width of the groove13bon the multikey subunit10B is made a bit smaller than the width of the ridge13con the multikey subunit10C, so that the groove13bof the multikey subunit10B and the ridge13cof the multikey subunit10C are tight fit to each other. The width of the ridge13con the multikey subunit10B is determined based on the width of its groove13bso that the common-connecting member13is formed in a uniform thickness. The width of the groove13bon the multikey subunit10A is made a bit smaller than the width of the ridge13con the multikey subunit10B, so that the groove13bof the multikey subunit10A and the ridge13cof the multikey subunit10B are tight fit to each other. The width of the ridge13con the multikey subunit10A is determined based on the width of its groove13b. As all the grooves13bare made in the same depth, all the ridges13care made in the same height. As the multikey subunits10A,10B and10C are assembled together by lapping one common connecting member13on another successively, the ridge13cof the multikey subunit10C fits in the groove13bof the multikey subunit10B and the ridge13cof the multikey subunit10B fits in the groove13bof the multikey subunit10A to make an integrated multikey unit for an octave. Alternatively, several pins may be provided integrally on the rear surface of the common connecting member13of the multikey subunit10C protruding rearward and the corresponding number of through holes may be provided in the common connecting members13of the multikey subunits10A and10B at the positions to receive the pins of the multikey subunit10C in order to integrate the multikey subunits10A,10B and10C into one piece by fitting the pins into the corresponding through holes.

The keyboard frame20is formed of resin by integral molding and is elongate in the width direction. The keyboard frame20has a vertical rear wall member20astanding vertically and extending elongate in the width direction, and a middle upper wall member20band a rear top wall member, each lying approximately horizontal and extending elongate in the width direction. The rear top wall member20cis positioned in front of and above the vertical rear wall member20a. The middle upper wall member20bis positioned in front of and lower than the rear top wall member20c. The rear end of the middle upper wall member20band the frond end of the rear top wall member20care connected by a vertical wall member20d, which is also elongate in the width direction. Thus, a stepped configuration is formed by the middle upper wall member20band the rear top wall member20cin the upper region of the keyboard frame20.

From the rear end of the rear top wall member20cis extended a slant wall member20eextending rearward and downward. The lower end of the slant wall member20eis positioned in front of the upper end of the vertical rear wall member20a. A horizontal wall member20fis provided extending rearward from the lower end of the slant wall member20e, and the rear end of the horizontal wall member20fis connected to the upper end of vertical rear wall member20a. Over the slant wall member20eand the horizontal wall member20fare provided a plurality of ribs21at intervals in the width direction, not necessarily at regular intervals but can be at different intervals. The upper surface of the rib21cis formed as a slope linking the rear end of the rear top wall member20cand the upper end of the vertical rear wall member20a. The slant wall member20eand the horizontal wall member20fmay be omitted, as long as the ribs21connect the vertical rear wall member20aand the rear top wall member20c. In such a case, however, the number of ribs21had better be increased in order to secure the strength of the keyboard frame20, as compared with the case in which the slant wall member20eand the horizontal wall member20fare both provided.

On the rear surface of the vertical rear wall member20aare provided bosses20a1as first protrusions in the right end part, the center part and the left end part in the width direction. The diameter of the boss20a1is equal to the width the cutaway13ain the center part among other parts of the multikey subunit10A,10B,10C. When the multikey subunits10A,10B and10C are assembled on the keyboard frame20, the cutaways13aare slip fit over the bosses20a1.

Also on the rear surface of the vertical rear wall member20aare provided ribs20a2as second protrusions extending in the width direction. The ribs20a2are provided at a bit higher position than the center of the bosses20a1. The ribs20a2are not provided in the vicinity of the bosses20a1, but are provided apart from the bosses20a1with some intervals in the width direction of the keyboard frame20. The width of the rib20a2is smaller than the diameter of the boss20a1, and is of the order of a half of the thickness of the keyboard frame20. The ribs20a2are formed with a draft angle to facilitate the release of the molded keyboard frame20from the mold. In this connection, the rib20a2is shaped narrower toward its tip (i.e. rearward). In other words, the upper surface is inclined downward toward the tip, and the lower surface is inclined upward toward the tip. The height (size in the depth direction) of the rib20a2is made equal to the thickness of the common connecting member13(i.e. depth of the groove13b) of the multikey subunit10C. The ribs20a2are to fit in the groove13bof the multikey subunit10C when the multikey subunits10A,10B and10C are assembled on the keyboard frame20.

As shown inFIG. 1, a key guide22provided in the front region of the keyboard frame20comes into the hollow space at the middle part of the key body11from below to guide the key body11to swing vertically when depressed and released, restricting its widthwise deviation. An actuating member23is provided extending downward from the front part of the key body11. The actuating member23is formed in a hollow channel shape open rearward having a front thin wall extending downward from the key body11and side thin walls extending downward from the key body11and rearward from the left and right ends of the front thin wall. The lower end of the actuating member23is closed with a bottom wall.

Below the key body11is provided a swing lever25as a member which swings in accordance with the swing movement of the key body11and exerts an inertia force to the key body11in order to simulate the key touch feeling on the acoustic piano. The swing lever25is comprised of a lever body25amade of synthetic resin and a weight piece25bmade of metal. The lever body25ais a member in the shape of a plate having a hook member25a1in its lower part and is supported by a lever fulcrum26having a pin26aso that the lever body25ais rotatable around the axis of the pin26a. The lever body25ais further provided in its front part with a pair of upper and lower fork members25a2and25a3, the upper one25a2being formed shorter than the lower one25a3. Between the fork members25a2and25a3is inserted the bottom wall of the actuating member23of the key body11. A shock absorbing member made of rubber, urethane, felt or the like is attached to the bottom wall of the actuating member23to mediate an impact caused by a collision between the bottom wall of the actuating member23and the upper surface of the lower fork member25a3and a collision between the bottom wall of the actuating member and the lower surface of the upper fork member25a2. While the key body11is released, the front part of the swing lever25displaces upward due to the own weight of the swing lever25and of the weight piece25b. Under this condition, the actuating member23is urged upward by means of the fork member25a3, and the front part of the key body11is displaced upward. On the other hand, when the key body11is depressed, the bottom wall of the actuating member23pushes the upper surface of the fork member25a3downward, and the front part of the swing lever25is displaced downward.

The weight piece25bis formed in the shape of a plate and is fixed to the rear end of the lever body25a. All of the weight pieces25bmay be of the same weight for all the key bodies11, but may be of lighter weight successively from the lowest note key toward the highest note key, key by key or key region by key region, in order to faithfully simulate the key touch feeling on the acoustic piano.

To the lower surface of the front part of the keyboard frame20is fixed an elongate upper stopper27constituted by a shock absorbing material such as felt extending in the width direction. The upper stopper27restricts an upward displacement of the front part of the swing lever25, which in turn restricts an upward displacement of the front part of the key body11while released. To the lower surface of the middle upper wall member20bof the keyboard frame20is fixed an elongate lower stopper28constituted by a shock absorbing material such as felt extending in the width direction. The lower stopper28restricts an upward displacement of the rear part of the swing lever25, which in turn restricts a downward displacement of the front part of the key body11when depressed.

On the lower surface of the middle part of the key body11is formed a switch-actuating part29. The switch-actuating part29abuts the upper surface of a key switch30aarranged on a circuit board30. The key switch30ais provided for every key body11, and detects the depressed or released condition of the corresponding key body11by being actuated in accordance with the swing movement of the corresponding key body11. The keyboard frame20is integrally formed with a solid support32and an elastic support33for fixedly support the circuit board30. The solid support32is provided in the front part of the middle upper wall member20b. The elastic support33is provided at the stepped part formed by the middle upper wall member20band the rear top wall member20cof the keyboard frame20, having a deformable member33awhich is elastically deformable in the depth direction. The deformable member33ais elastically deformed, when the circuit board30is fixed, pressing the circuit board30to the solid support32. Thus the circuit board30is held between the solid support32and the elastic support33. There are a plurality of solid supports32and elastic supports33provided, respectively, at intervals in the width direction, not necessarily at regular intervals but can be at different intervals.

Hereinafter will be explained the procedure of fixing the multikey subunits10A,10B and10C to the keyboard frame20in the keyboard assembly structured as described above. To begin with, the three multikey subunits10A,10B and10C are combined together to constitute an integrated multikey unit for one octave, by fitting the ridge13cof the multikey subunit10C in the groove13bof the multikey subunit10B, and the ridge13cof the multikey subunit10B in the groove13bof the multikey subunit10A. As the corresponding ridges13cand grooves13bof the multikey subunits10A,10B and10C are tight fit together, the integrated multikey unit would not separate easily from each other, even if some amount of force should be applied to the multikey subunits10A,10B and10C. As will be understood, the combined multikey subunits10A,10B and10C constitute an integrated multikey unit for one octave with the seven natural (white) keys and the five sharp (black) keys juxtaposing one after another in the width direction.

In assembling the combined multikey unit10A,10B,10C to the keyboard frame20, the combined multikey unit10A,10B,10C is held aslant with its front part positioned lower than its rear part as shown inFIG. 4, the lower end of the actuating member23is brought closer to the upper surface of the fork member25a3of the swing lever25. In this position, the lower edge of the integrated common connecting member13is just above the ribs21. And then, as shown inFIG. 5, the integrated multikey unit10A,10B,10C is slid rearward with the bottom wall of the actuating member23entering between the fork members25a2and25a3and with the rear part of the integrated multikey unit10A,10B,10C being lowered. The integrated common connecting member13is guided down to the vertical rear wall member20awith its lower edge sliding along the upper surface of the ribs21.

Thereafter, as shown inFIGS. 6aand6b, the cutaways13aof the integrated common connecting member13which have been guided down to the vertical rear wall member by means of the ribs21are coupled to the bosses20a1on the vertical rear wall member20a. Thus, the integrated multikey unit10A,10B,10C is temporarily placed at the correct vertical position just before getting assembled. Further, as the width of the cutaway13provided in the middle part of the common connecting member13is made equal to the diameter of the boss20a1, the integrated multikey unit10A,10B,10C is correctly positioned also in the width direction. Under this condition, the groove13bof the multikey subunit10C is positioned a bit apart rearward and downward from the ribs20a2.

Next, the integrated common connecting member13is pulled a bit forward and upward to bring the ribs20a2into the groove13bof the multikey subunit10C. Then, a screw35is screwed through a washer36into each of the bosses20a1to fix the integrated common connecting member13to the keyboard frame20. In this way, the integrated common connecting member13is finally set at the correct position, and the integrated multikey unit10A,10B,10C has got assembled onto the keyboard frame20.

According to the above-described embodiment, the integrated common connecting member13is guided by the ribs21down to the vertical rear wall member20a, when the integrated multikey unit10A,10B,10C is being mounted on the keyboard frame20. The assembling process will be facilitated, as the common connecting member13would not abut or hitch on the upper portion of the keyboard frame20. The integrated multikey unit10A,10B,10C can be assembled to the keyboard frame20by simply engaging the groove13bwith the rib20a2and screwing the screws35into the bosses20a1, which process will dispense with precise adjustment of the assembling position using a particular jig or measuring device. The bosses20a1are used also as the protrusions for temporarily resting the integrated common connecting member13. This is advantageous in that the structure of a metal mold for manufacturing the keyboard frame20will be simplified, cutting down the manufacturing cost, as compared with the case where separate protrusions are provided for temporary resting or positioning the multikey unit. Further in the above-described embodiment, the height of the rib20a2is designed as small as the thickness of the thin common connecting member13of one multikey subunit. Thus the thickness of the vertical rear wall20aof the keyboard frame20is virtually uniform and there would be no need of providing a thickness-reduced portion (hollow) on the front surface of the keyboard frame20opposite to (i.e. behind) the rib20a2. This also serves to cut down the manufacturing cost, as the structure of a metal mold will be simplified.

The present invention is not necessarily limited to the above described embodiment, but may be variously modified without departing from the spirit of the invention.

In the above embodiment, the cutaways13aon the common connecting member13are engaged with the bosses20a1to temporarily positioning the common connecting member13. However, separate protrusions for temporary positioning may be provided on the vertical rear wall member20ain addition to the boss20a1, so that the cutaways13awould engage such separate protrusions for temporary positioning. The shape of such separate protrusions may not necessarily be limited to a circular column like the bosses20a1but may be of other arbitrary shape (e.g. square pole) as long as they are protruded rearward from the vertical rear wall member20a, and the shape of the cutaways13ais formed to match the shape of such protrusions for temporary positioning. In such a case, the cutaways13amay be formed a little bit larger than the above-described embodiment so that the bosses20a1would not touch the cutaways13a, when the integrated multikey unit10A,10B,10C is mounted on the keyboard frame20. In other words, the temporary positioning of the common connecting member13is realized by the separate protrusions for the temporary positioning, and the bosses20a1are used only for fixing (i.e. screwing) the common connecting member13. In such a way, the temporary positioning of the common connecting member13can be effected as in the above-described embodiment. The separate protrusions for temporary positioning may not receive the cutaways13abut may simply receive the lower edge of the common connecting member13. With such a configuration, the temporary positioning, in the vertical direction, of the common connecting member13can be accomplished as in the case of the above-described embodiment. In such a case, however, the positioning in the width direction will be effected by matching the cutaway13awith the boss20a1.

In the above-described embodiment, the ribs21are provided over the slant wall member20eand the horizontal wall member20fto guide the lower edge of the common connecting member13sliding along the upper edge of the ribs21down to the vertical rear wall member20a. However, the slant wall member20e, the horizontal wall member20fand the ribs21may be replaced by a single slant wall member20gin the shape of a plain plate connecting the rear end of the rear top wall member20cand the top end of the vertical rear wall member20a, as shown inFIG. 7. The slant wall member20gmay not necessarily be in the shape of a flat plane, but may be of a curved plate as long as it is inclined downward (i.e. descending) toward the rear direction. With such a configuration, the lower edge of the common connecting member13can slide along the slant wall member20fto reach the vertical rear wall member20a, so that the integrated multikey unit10A,10B,10C can be easily assembled onto the keyboard frame20.

Further in the above-described embodiment, the ribs20a2are formed with a draft angle to facilitate the release of the molded keyboard frame20from the mold. Accordingly, the upper surface of the rib20a2is descending rearward (toward its tip). With such a configuration, if the integrated multikey unit10A,10B,10C is displaced rearward when the groove13bof the multikey subunit10C engages with the rib20a2, the integrated multikey unit10A,10B,10C is apt to slip off the rib20a2. To prevent such a possibility, some parts of the rib20a2in a predetermined length (in the width direction) are formed with a horizontal upper surface and a horizontal lower surface as shown by X inFIGS. 8aand8b. In such a case, the corresponding parts of the groove13bof the multikey subunit10C is also formed with a horizontal upper and lower surfaces. With this configuration, even if the integrated multikey unit10A,10B,10C is displaced rearward when the groove13bof the multikey subunit10C engages with the rib20a2, the integrated multikey unit10A,10B,10C will move horizontally and would not easily slip off the rib20a2. While the modified example shown inFIGS. 8aand8bemploys the rib20a2having a horizontal upper and lower surfaces at the parts of a predetermined length in the width direction, only the upper surface may be formed flat and the lower surface may be formed with a draft angle. With such a further modification, the same effects will be obtained as with the above modification shown inFIGS. 8aand8b.

The present invention has been described in connection with an embodiment which comprises swing levers25for simulating the key touch feeling on an acoustic piano. The present invention is, of course, applicable to a keyboard assembly for an electronic musical instrument which need not simulate the key touch feeling on an acoustic piano. For such an electronic musical instrument, the above-described swing levers25may be omitted and some urging members (e.g. springs) may be provided instead to urge the front part of the key bodies11upward. In such an electronic musical instrument also, the multikey unit10A,10B,10C can be easily assembled to the keyboard frame.

While several preferred embodiments have been described and illustrated in detail herein above with reference to the drawings, it should be understood that the illustrated embodiments are just for preferable examples, that the present invention may not necessarily be limited to the illustrated embodiments, and that the present invention can be practiced with various modifications, improvements and combinations without departing from the spirit of the present invention.