Hammer for electronic keyboard instrument

A hammer for an electronic keyboard instrument, constructed to ensure secure mounting of a weight to a hammer body and enable both assembly and disassembly of the hammer to be easily performed. The hammer includes a hammer body having a weight mounting portion that is open on one side in a left-right direction and a weight removably mounted to the hammer body via a mounting portion. The weight mounting portion has a housing portion that has an opening having a shape complementary to the mounting portion, and houses the mounting portion in a manner slidable between a fit-in position and a fixed position, latching portions for latching the mounting portion incapable of falling off from the opening when in the fixed position, and holding portions for holding the mounting portion non-slidable to the fit-in position.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Japanese Patent Application Number 169036/2009, filed on Jul. 17, 2009.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hammer for an electronic keyboard instrument, which is provided for each key in an electronic keyboard instrument, such as an electronic piano, so as to impart touch weight to each key during key depression.

2. Description of the Related Art

Conventionally, there has been known a hammer for an electronic piano, disclosed in Japanese Laid-Open Patent Publication No. 2006-3495 ([0029],FIGS. 1 and 3to5). The hammers are pivotally mounted in association with respective keys on a keyboard chassis supporting a keyboard, and each of the hammers pivotally moves in accordance with depression of an associated one of the keys to thereby impart a predetermined touch weight to the key. As a consequence, the electronic piano can provide a touch feeling closely analogous to that of an acoustic piano.

The hammer is disposed below the associated key, and comprises a metal hammer body extending along the length of the key, and a hammer holder made of a synthetic resin, which is mounted to a side surface of the hammer body and is pivotally supported by the keyboard chassis. The hammer body is formed by a metal plate having a predetermined shape. Specifically, the hammer body has a front end thereof formed in a rearwardly opening C shape in side view, and a rear end thereof formed in a relatively large triangular shape in side view.

On the other hand, the hammer holder is a molded article having a predetermined shape, and is mounted to the front end of the hammer body. Specifically, the hammer holder, when in a state mounted to the hammer body, has a bearing portion formed inside a C-shaped portion of the front end thereof, and a mounting portion to be mounted to the hammer body at respective locations upward and downward of the bearing portion. The mounting portion has a C shape in cross section, which is formed by a body portion formed in a shape corresponding to the shape, in side view, of a portion of the hammer body to which the mounting portion is to be mounted, and collar portions formed along the respective upper and lower edges of the body portion, with an end of each collar portion remote from the body portion being formed with a plurality of clipping pieces for cooperating with the body portion to clip the hammer body in the direction of thickness of the hammer body. Further, the body portion is formed with an engaging portion protruding inside the mounting portion. This engaging portion engages with an engaging hole formed at a predetermined location in the hammer body, whereby displacement and wobbling of the hammer holder with respect to the hammer body are suppressed.

The hammer holder constructed as above is mounted to the hammer body as follows: The body portion of the hammer holder is aligned to the portion of the hammer body to which the body portion is to be mounted, and then pressed toward the hammer body. In this case, a space between the clipping pieces of the hammer holder is opened up in the lateral direction (vertical direction) of the hammer body, and the clipping pieces pass over the respective upper and lower edges of the hammer body whereby they reach the remote side of the hammer body from the body portion, with the hammer body therebetween. Thus, the hammer holder is mounted to the hammer body in a state sandwiching the hammer body in the direction of the thickness of the same between the body portion and the clipping pieces.

As described above, the hammer holder is mounted to the hammer body during assembly of the hammer by opening up the space between the clipping pieces of the hammer holder. Therefore, when the hammer holder is formed of a relatively hard synthetic resin material, a relatively large urging force is required. Further, in the case of disposing of an electronic piano provided with the hammers constructed as above, work for disassembling each of the hammers into the metal hammer body and the hammer holder formed of the synthetic resin material is very complicated and troublesome when a sequence reverse to the above-described sequence is employed. The hammer described above suffers from the problem that work for assembly and disassembly of the hammer comprising the hammer body and the hammer holder is thus complicated and troublesome. Further, there is a fear that a gap is formed between the hammer body and the inner surface of the mounting portion of the hammer holder e.g. due to inevitable size error in manufacturing the hammer body and the hammer holder, causing wobbling and resultant noises during pivotal motion of the hammer performed in accordance with key depression.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a hammer for an electronic keyboard instrument, in which the hammer including a hammer body and a weight has a construction that ensures secure mounting of the weight to the hammer body and makes it possible to facilitate not only assembly of the hammer from the two parts, but also disassembly of the same.

To attain the above object, the present invention provides a hammer for an electronic keyboard instrument, which pivotally moves in accordance with depression of a key to thereby impart touch weight to the key, comprising a hammer body that is formed by a resin molded article and having a weight mounting portion extending in a front-rear direction, and a weight that is formed of a material larger in specific gravity than the hammer body and has a mounting portion to be mounted to the weight mounting portion, the weight being removably mounted to the hammer body via the mounting portion, wherein the weight mounting portion of the hammer body comprises a housing portion that has an opening open on one side in a left-right direction and having a shape complementary to the mounting portion of the weight, and houses the mounting portion in a manner slidable between a fit-in position in which the mounting portion is fitted via the opening and a fixed position shifted from the fit-in position in a direction different from the left-right direction, a latching portion that is formed on a rim of the opening and latches the mounting portion in a state undetachable from the opening when the mounting portion is positioned in the fixed position, and a holding portion that holds the mounting portion in a state incapable of sliding to the fit-in position when the mounting portion is positioned in the fixed position.

With this arrangement, the hammer body formed by a resin molded article has the weight mounting portion extending in the front-rear direction, while the weight formed of a material larger in specific gravity than the hammer body has the mounting portion to be mounted to the weight mounting portion of the hammer body. Further, the weight mounting portion of the hammer body includes the housing portion that has the opening open on one side in the left-right direction and has a shape complementary to the mounting portion of the weight. The housing portion is configured to house the mounting portion of the weight in a manner slidable between the fit-in position in which the mounting portion is fitted via the opening and the fixed position shifted from the fit-in position in a direction different from the left-right direction.

When assembling the hammer, first, the mounting portion of the weight is fitted in the housing portion via the opening of the housing portion of the hammer body. Then, the mounting portion in the fit-in position is slid to the fixed position. As a consequence, the mounting portion in the fixed position is latched by the latching portion formed on the rim of the opening of the hammer body and held in a state in which it is prevented from falling off from the opening. Further, the mounting portion is held by the holding portion in a state incapable of sliding to the fit-in position. As described above, it is possible to easily assemble the hammer by simple work, and mount the weight securely to the hammer body. On the other hand, when disassembling the hammer into the hammer body and the weight, the mounting portion in the fixed position is slid to the fit-in position while releasing hold of the mounting portion by the holding portion or after releasing the hold. Then, the mounting portion of the weight is dismounted from the weight mounting portion of the hammer body via the opening. Thus, the disassembly of the hammer can be performed with ease.

Preferably, the holding portion comprises a hook engaged with the mounting portion to inhibit the mounting portion from sliding to the fit-in position when the mounting portion is positioned in the fixed position, but allow the mounting portion to slide to the fit-in position when an external force not smaller than a predetermined magnitude acts on the mounting portion in a direction toward the fit-in position.

With this arrangement, the holding portion has the hook engaged with the mounting portion of the weight, and the hook inhibits the mounting portion positioned in the fixed position from sliding to the fit-in position, so that it is possible to securely hold the mounting portion in the fixed position. Further, when an external force not smaller than the predetermined magnitude acts on the mounting portion positioned in the fixed position in the direction toward the fit-in position, the hook allows the mounting portion to slide to the fit-in position. Therefore, when disassembling the hammer, it is possible to easily dismount the weight from the hammer body simply by sliding the mounting portion of the weight to the fit-in position while causing the external force to act on the mounting portion.

More preferably, the holding portion further comprises an engaging protrusion protruding inward from an inner surface of the housing portion, for engagement with the mounting portion.

With this arrangement, not only the above-mentioned hook but also the engaging protrusion protruding inward from the inner surface of the housing portion engages, as the holding portion, with the mounting portion of the weight. This makes it possible to hold the mounting portion more securely in the fixed position.

Preferably, the inner surface of the housing portion is formed with a protrusion that is brought into pressure contact with the mounting portion to thereby suppress wobbling of the mounting portion.

With this arrangement, the protrusion formed on the inner surface of the housing portion of the hammer body is brought into pressure contact with the mounting portion of the weight. For example, in a case where the hammer is constructed such that the surface of the mounting portion and the inner surface of the housing portion are held in surface contact with each other, when a gap is formed between the two surfaces e.g. due to inevitable size error in manufacturing, the weight can wobble relative to the hammer body during pivotal motion of the hammer. Therefore, by employing the above arrangement of the present invention, it is possible to effectively suppress wobbling of the weight against the hammer body.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will now be described in detail with reference to the drawings showing a preferred embodiment thereof.FIGS. 1A and 1Bshow a keyboard device for an electronic piano, including a hammer according to a first embodiment of the present invention. As shown inFIGS. 1A and 1B, the keyboard device1includes a keyboard chassis2, a plurality of (e.g. eighty-eight) keys3pivotally mounted on the keyboard chassis2and including white keys3aand black keys3b, and a plurality of hammers4(only one of which is shown) each provided for an associated one of the keys3and pivotally mounted on the keyboard chassis2.

In the following, a description will be given of the outline of the arrangement and operation of the keyboard device1first, and then the construction of the hammer4and a method of assembling the same will be described, with reference toFIGS. 1A and 1B.

The keyboard chassis2is a resin molded article in a predetermined shape which is formed by injection molding of a predetermined resin material (e.g. ABS resin). The keyboard chassis2has a front part (left part as viewed inFIGS. 1A and 1B)11thereof, a central part12thereof, and a rear part (right part as viewed inFIGS. 1A and 1B)13thereof integrally formed in a state connected to each other by ribs (not shown), and is rigidly secured on a keybed of an electronic piano, not shown, via a front mounting rail14, a central mounting rail15, and a rear mounting rail16each extending in a left-right direction (depth direction as viewed inFIGS. 1A and 1B). It should be noted that in the following description, the front part11, the central part12, and the rear part13of the keyboard chassis2will be referred to as “the chassis front part11”, “the chassis central part12”, and “the chassis rear part13”, respectively.

The chassis front part11has a plurality of pairs of engaging holes11a, each pair of which comprises two engaging holes11aleft and right (only one of which is shown inFIGS. 1A and 1B) vertically extending through the chassis front part11and is provided for an associated white key3a. Through the left and right engaging holes11aare inserted respective left and right upper limit position-restricting portions21, referred to hereinafter, of the associated white key3a. Further, the chassis front part11has a key stopper11bformed e.g. of felt and attached to the bottom of a front-portion of a rim of each of the engaging hole11a. The upper limit position-restricting portions21of the white key3aare brought into abutment with the key stopper11bfrom below when in a key-released state, whereby the upper limit position of the white key3ais restricted. Furthermore, the chassis front part11has a plurality of front guides11c(only one of which is shown inFIGS. 1A and 1B) erected therefrom in association with the respective white keys3aso as to prevent lateral swing of the white keys. Each of the front guides11chas approximately the same width as the lateral inner width (width in the left-right direction) of the white key3a, and is inserted in the associated white key3afrom below.

The chassis central part12has a support shaft12aextending in the left-right direction, and the hammers4are pivotally supported on the support shaft12a. Further, key switches17extending toward the chassis front part11are mounted on the chassis central part12, for detecting key depression information on the respective associated keys3. Each of the key switches17comprises a printed circuit board17aand a switch body17bwhich is formed by a rubber switch and attached to the printed circuit board17a, for an associated one of the keys3. The key switch17is mounted to the keyboard chassis2with the rear end of the printed circuit board17ainserted in the chassis central part12and the front end of the same screwed to the chassis front part11.

The chassis rear part13has a key support section13athat supports a pivot shaft23, referred to hereinafter, provided on the rear end of each key3, to thereby support the key3in a manner pivotally movable about the axis of the pivot shaft23. Further, a hammer stopper13bformed e.g. of felt is attached to the rear end of the lower surface of the key support section13a. Furthermore, the chassis rear part13has two rear guides13cleft and right (only one of which is shown inFIGS. 1A and 1B) located forward of the key support section13aand erected at respective locations leftward and rightward of the rear end of each key3so as to prevent lateral swing of the key3.

Between the chassis rear part13and the chassis central part12, there is disposed a flat plate18extending substantially horizontally between the keys3and the hammers4. This flat plate18has a plurality of front guides18a(only one of which is shown inFIGS. 1A and 1B) erected from the front end thereof in association with the respective black keys3bso as to prevent lateral swing of the black keys3b. Similarly to the front guide11cfor each white key3a, each of the front guides18ahas approximately the same width as the lateral inner width of the black key3b, and is inserted in the associated black key3bfrom below.

It should be noted that a plurality of let-off members19(only one of which is shown inFIGS. 1A and 1B) each formed of an elastic material are mounted to the flat plate18in association with the respective hammers4in a manner protruding obliquely downward and forward from the lower surface of the same. When a hammer4that pivotally moves along with key depression comes into temporary engagement with an associated one of the let-off members19during the pivotal motion, let-off feeling is added to the touch feeling of the depressed key3.

Each key3is formed e.g. by injection molding of a predetermined resin material (e.g. AS resin) such that it has a hollow shape extending in the front-rear direction and opening downward. The white key3ahas a front end thereof formed with the pair of left and right upper limit position-restricting portions21and21(only one of which is shown inFIGS. 1A and 1B). The left and right upper limit position-restricting portions21and21extend downward from the respective left and right side walls of the white key3aand each have a lower end thereof bent forward. The left and right upper limit position-restricting portions21and21are engaged with the respective left and right engaging holes11aand11aof the chassis front part11, in respective states extending therethrough. Further, the white key3ahas an actuator portion22formed at a predetermined location thereof rearward of the upper limit position-restricting portions21in a manner protruding downward, and the actuator portion22is engaged with an engaging recess26b, referred to hereinafter, of the hammer4in a state received therein. Furthermore, the key3has the rear end thereof provided with the pivot shaft23extending in the left-right direction. It should be noted that in each black key3b, portions corresponding to the upper limit position-restricting portions21and the actuator portion22of the white key3aare integrally formed with respective lower portions of the front end thereof.

Each hammer4comprises a hammer body24and a weight25removably attached to the hammer body24. The hammer body24is a resin molded article in a predetermined shape formed e.g. by injection molding of a predetermined resin material (e.g. POM (polyacetal resin)). The hammer body24extends in the front-rear direction and has a shaft bearing portion26aformed at a predetermined location in a front half (left half as viewed inFIGS. 1A and 1B)26thereof and having an inverted U shape in side view, and the shaft bearing portion26ais pivotally engaged with the support shaft12aof the chassis central part12. The engaging recess26bfor engagement with the actuator portion22of the key3is formed in the front half26of the hammer body24at a location forward of the shaft bearing portion26a. The engaging recess26bis open upward and forward, and the lower part of the actuator portion22of the key3is received in the engaging recess26bin a state where the lower end of the actuator portion22is held in contact with the bottom surface of the engaging recess26b. Further, formed under the engaging recess26bin the front half26of the hammer body24is a switch pressing portion26cfor pressing the switch body17bof the key switch17.

A weight mounting portion27forming the rear half of the hammer body24includes a housing portion35having an opening28open rightward (frontward as viewed inFIGS. 1A and 1B), and the weight25is removably mounted to the hammer body24via the opening28. Further, an engaging protrusion27afor engagement with the let-off member19during key depression is formed on the weight mounting portion27of the hammer body24at a predetermined location in a manner protruding upward from the weight mounting portion27.

On the other hand, the weight25is formed of a material (steel or the like material) having a larger specific gravity than that of the hammer body24. The weight25is formed into a predetermined shape by pressing a metal plate having a smaller thickness than the thickness (thickness in the depth direction as viewed inFIGS. 1A and 1B) of the hammer body24. The weight25extends in the front-rear direction and has a front half thereof formed as a mounting portion29mounted in the weight mounting portion27of the hammer body24. The weight25extends rearward from the mounting portion29to a location near the rear end of the chassis rear part13, and has a rear end thereof formed to have a relatively large vertical width (width in an up-down direction).

In the keyboard device1constructed as above, when a key3(the white key3ainFIG. 1A) is depressed in the key-released state shown inFIG. 1A, the key3pivotally moves counterclockwise, as viewed inFIG. 1A, about the axis of the pivot shaft23of the rear end of the key3, as shown inFIG. 1B. In accordance with this pivotal motion of the key3, the actuator portion22of the key3presses the engaging recess26bof the hammer4downward. As a consequence, the hammer4presses the switch body17bof the key switch17from above by the switch pressing portion26cwhile pivotally moving counterclockwise about the support shaft12aof the chassis central part12. In this case, the rear end of the hammer4(i.e. the rear end of the weight25) is brought into abutment with the hammer stopper13bof the chassis rear part13from below, whereby further pivotal motion of the hammer4is prevented. The key depressing operation described above makes it possible to impart a predetermined touch weight corresponding to the weight and torque of the hammer4to the key3and detect key depression information on the key3via the key switch17at the same time.

On the other hand, when the depressed key3is released, the hammer4pivotally moves clockwise, as viewed inFIG. 1B. In accordance with this pivotal motion of the hammer4, the key3is pushed upward via the actuator portion22and pivotally moves clockwise. As a consequence, each of the key3and the hammer4returns to its key-released position as shown inFIG. 1A. In this case, the upper limit position-restricting portions21of the front end of the key3are brought into abutment with the key stopper11bof the chassis front part11from below, whereby further pivotal motion of the key3is prevented.

Next, the construction of the hammer4and the method of assembling the same will be described with reference toFIGS. 2A to 4C. More specifically, a description will be given of the mounting structure of the weight25in the hammer body24and the method of mounting the weight25to the hammer body24.

As shown inFIGS. 2A,2B, and3, the weight mounting portion27to which the weight25is mounted comprises a left side wall31having a predetermined shape and extending in the front-rear direction, an upper wall32and a lower wall33extending along the respective upper and lower edges of the left side wall31and protruding rightward from the left side wall31, in facing relation to each other, and a front wall34continuous with the left side wall31, the upper wall32, and the lower wall33. The weight25is mounted to the hammer body24, with the mounting portion29of the weight25housed in the housing portion35defined by the left side wall31, the upper wall32, the lower wall33, and the front wall34and extending in the front-rear direction.

Each of the upper wall32and the lower wall33has a substantially uniform predetermined thickness, and has two protrusions front and rear having a relatively large width in the front-rear direction. Specifically, the upper wall32has a front protrusion36and a rear protrusion37formed in a manner spaced from each other in the front-rear direction and protruding upward, while the lower wall33has a front protrusion38and a rear protrusion39each protruding downward. The front protrusion36of the upper wall32is formed at a location spaced rearward from the front wall34of the weight mounting portion27by a predetermined distance, whereas the front protrusion38of the lower wall33is formed in a manner continuous with the front wall34. In short, the front protrusions36and38are formed at the locations displaced from each other in the front-rear direction. On the other hand, the rear protrusions37and39are formed at the locations vertically symmetrical to each other.

The housing portion35of the weight mounting portion27has inwardly-opening recesses formed by the front protrusions36and38and the rear protrusions37and39of the upper wall32and the lower wall33, respectively. Specifically, as shown inFIG. 2B, the housing portion35has a front recess36aand a rear recess37acorresponding to the front protrusion36and the rear protrusion37of the upper wall32, at respective upper locations therein, and a front recess38aand a rear recess39acorresponding to the front protrusion38and the rear protrusion39of the lower wall33, at respective lower locations therein.

Further, each of the front protrusions36and38and the rear protrusions37and39of the upper wall32and the lower wall33has a front end thereof formed with an engaging portion for preventing fall-off of the weight25. Specifically, as shown inFIGS. 2B and 3, the front end of the front protrusion36and that of the rear protrusion37of the upper wall32have a latching portion36band a latching portion37b, respectively, formed on an opening-side end of the housing portion35in a manner slightly protruding inside the housing portion35, while the front end of the front protrusion38and that of the rear protrusion39of the lower wall33have respective latching portions38band39bsimilar to the latching portions36band37b.

The upper wall32and the lower wall33have rear ends thereof formed with a pair of respective hooks41and41upper and lower for preventing the weight25mounted to the hammer body24from sliding rearward. Each of the hooks41comprises a hook piece41aextending further rearward than the rear end of the left side wall31by a predetermined length and a hook-shaped hook body41bformed on the rear end of the hook piece41ain a manner protruding inward. It should be noted that the hook piece41aof each hook41is formed to be thinner than the upper wall32and the lower wall33located in front of the hooks41, and is slightly vertically flexible.

The housing portion35of the weight mounting portion27has inner surfaces thereof formed with projections for suppressing wobbling of the mounting portion29of the weight25by pressure contact with the same when the hammer body24is mounted on the weight25. Specifically, as shown inFIG. 2B, on an inner surface of the left side wall31, there are formed two projections31aand31afront and rear spaced from each other in the front-right direction and slightly protruding inward. Further, on an inner surface of the upper wall32between the front protrusion36and the rear protrusion37, there are formed two projections32aand32afront and rear spaced from each other in the front-rear direction, in a manner extending in the left-right direction and slightly protruding inward. Similarly, on an inner surface of the lower wall33between the front protrusion38and the rear protrusion39, there are formed two projections33aand33afront and rear. Further, at the vertical center of the inner surface of the front wall34, there is formed a projection34asimilar to the projections32aand33aof the upper and lower walls32and33.

On the inner surfaces of the respective upper and lower walls32and33, there are formed a pair of respective engaging protrusions42and42upper and lower, which cooperate with the pair of hooks41and41to prevent the weight25mounted to the hammer body24from sliding rearward. The two engaging protrusions42and42are formed in vertically symmetrical relation to each other. The upper engaging protrusion42is located approximately at a center between the front and rear projections32aand32aof the upper wall32, while the lower engaging protrusion42is located between the front and rear projections33aand33aof the lower wall33and formed in a manner vertically symmetrical to the upper engaging protrusion42. Further, each of the engaging protrusions42is formed in a wedge shape in side view by a front sloping surface with a relatively large inclination angle with reference to the inner surface of the upper wall32or the lower wall33and a rear sloping surface with a relatively small inclination angle with reference to the same.

In the weight mounting portion27of the hammer body24constructed as above, the rim of the opening28of the housing portion35is defined by respective right-side ends of the upper wall32, the lower wall33, and the front wall34as viewed inFIG. 3.

The mounting portion29of the weight25has a shape complementary to the opening28of the housing portion35of the weight mounting portion27of the hammer body24. Specifically, as shown inFIG. 2B, the mounting portion29has an upper portion thereof formed with a front protrusion51and a rear protrusion52corresponding to the respective front and rear recesses36aand37aof the upper wall32of the weight mounting portion27. Further, the upper portion of the mounting portion29is formed with an engaging recess53corresponding to the engaging protrusion42of the inner surface of the upper wall32and having an upwardly opening V shape in side view, and an upwardly opening C-shaped latching recess54located immediately rearward of the engaging recess53. Furthermore, the rear end of the upper portion of the mounting portion29is formed with an engaging recess55corresponding to the hook body41bof the rear end of the upper wall32and having an upwardly opening V shape in side view, and a hook latching portion56located immediately rearward of the engaging recess55.

On the other hand, the mounting portion29has a lower portion thereof formed with a front protrusion61and a rear protrusion62corresponding to the respective front and rear recesses38aand39aof the lower wall33of the weight mounting portion27, and the latter62of the rear protrusions61and62is formed in a manner vertically symmetrical to the rear protrusion52. Further, the lower portion of the mounting portion29is formed with an engaging recess63and a latching recess64corresponding to the engaging protrusion42of the inner surface of the lower wall33and vertically symmetrical to the engaging recess53and the latching recess54respectively. Furthermore, the rear end of the lower portion of the mounting portion29is formed with an engaging recess65and a hook latching portion66corresponding to the hook body41bof the lower wall33and vertically symmetrical to the engaging recess55and the hook latching portion56, respectively.

Next, the method of mounting the weight25to the hammer body24will be described with reference toFIGS. 4A to 4C. First, the hammer body24and the weight25constructed as above are prepared, as shown inFIG. 4A, and the mounting portion29of the weight25is fitted in the housing portion35(fit-in position) of the weight mounting portion27of the hammer body24via the opening28as shown inFIG. 4B. In this case, the front end of the mounting portion29is held with a gap having a predetermined distance from the front wall34of the hammer body24. Further, in this case, the projections32aand33aof the respective upper and lower walls32and33of the weight mounting portion27are held in pressure contact with the respective upper and lower end surfaces of the mounting portion29in a state slightly crushed by these. Thus, the mounting portion29is held immovable in the vertical direction thereof.

It should be noted that when fitting the mounting portion29in the housing portion35, the mounting portion29can be properly fitted in the housing portion35without confusing between the front and back sides of the weight25. This is because the mounting portion29has the front protrusions51and61formed in vertically asymmetrical relation, though the rear protrusions52and62are vertically symmetrical, so that only when the front and back sides of the weight25face properly, the mounting portion29is allowed to be fitted in the housing portion35via the opening28.

Then, one of the hammer body24and the weight25is fixed, and then the other of the two is slid to thereby bring the front wall34of the weight mounting portion27and the front end of the mounting portion29close to each other. For example, inFIG. 4B, if the hammer body24is fixed, the weight25is slid forward (leftward as viewed inFIG. 4B). In this case, the rear end of the mounting portion29pushes the upper and lower hooks41and41of the weight mounting portion27to open up the space between the two hooks41and41, whereby the hook pieces41aand41aare slightly bent in respective opposite directions, and the hook bodies41band41bpass over the rear walls of the respective upper and lower engaging recesses55and65of the mounting portion29to be engaged with the respective upper and lower hook engaging portions56and66. Thus, the mounting portion29of the weight25is held in a fixed position shifted forward of the fit-in position as shown inFIG. 4C, and the assembly of the hammer4is completed.

In the hammer4, each of the upper and lower front protrusions51and61and the upper and lower rear protrusions52and62of the mounting portion29of the weight25has its front end sandwiched between the left side wall31of the weight mounting portion27of the hammer body24and an associated one of the latching portions36band38bof the respective upper and lower front recesses36aand38aand the latching portions37band39bof the respective upper and lower rear recesses37aand39a. As a consequence, the mounting portion29is prevented from falling off from the opening28by the four latching portions36b,37b,38b, and39bof the weight mounting portion27latching the four portions of the front protrusions51and61and the rear protrusions52and62. Further, in this case, the projections31aof the left side wall31of the weight mounting portion27are held in pressure contact with the left side surface of the mounting portion29in a state slightly crushed by the same. Thus, the mounting portion29is held immovable in the direction of thickness thereof.

Further, in the hammer4, as described hereinbefore, the upper and lower hook bodies41band41bof the weight mounting portion27are engaged with the respective hook engaging portions56and66of the mounting portion29, and the upper and lower engaging protrusions42and42of the weight mounting portion27are engaged with the respective upper and lower latching recesses54and64of the mounting portion29. As a consequence, the mounting portion29positioned in the fixed position is brought into a state where sliding to the fit-in position is inhibited. Further, in this case, the projection34aof the front wall34of the weight mounting portion27is brought into a state slightly crushed by the front end surface of the mounting portion29to be held in pressure contact with the same. Thus, the mounting portion29is held immovable in the longitudinal direction thereof (left-right direction as viewed inFIGS. 4A to 4C).

According to the present embodiment, since the mounting portion29of the weight25is held in the weight mounting portion27of the hammer body24in a manner immovable in any of the vertical direction, the direction of thickness, and the direction of length as described above, it is possible to obtain the hammer4with the weight25securely mounted to the hammer body24such that it does not wobble. Further, the hammer4can be easily assembled by relatively simple work of fitting the mounting portion29of the weight25in the housing portion35of the weight mounting portion27of the hammer body24via the opening28of the housing portion35and then sliding the mounting portion29.

It should be noted that when it is required to disassemble each of the hammers4into the resin hammer body24and the metal weight25in the case of disposing of an electronic piano provided with the hammers4, it is possible to easily dismount the weight25from the hammer body24by a sequence reverse to the above-described sequence of assembly of the hammer4. Specifically, when an external force of a predetermined magnitude is caused to act on the mounting portion29to slide the same toward the fit-in position, engagement of the hooks41and41and the engaging protrusions42and42of the weight mounting portion27with the mounting portion29is released, whereby the mounting portion29slides to the fit-in position. Then, the mounting portion29is dismounted from the housing portion35of the weight mounting portion27via the opening28thereof. Thus, the hammer4can be disassembled with ease.

Next, the construction of a hammer71according to a second embodiment of the present invention and a method of assembling the same will be described with reference toFIGS. 5A,5B, and6A to6C. It should be noted that in the following, component parts corresponding to those of the hammer4of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted, but only different points from the hammer4will be described.

As shown inFIGS. 5A and 53, the hammer71comprises a hammer body72which is a resin molded article, a metal weight73, and a weight retaining member74for preventing fall-off of the weight73. On each of the upper and lower walls32and33of the weight mounting portion27of the hammer body72, there are formed three protrusions larger in number than those of the weight mounting portion27of the hammer body24in the first embodiment by one. Specifically, the upper wall32has not only the front protrusion36and the rear protrusion37, but also a central protrusion75formed between the two protrusions36and37. Similarly, the lower wall33has not only the front protrusion38and the rear protrusion39, but also a central protrusion76formed in a manner vertically symmetrical to the central protrusion75.

The housing portion35of the weight mounting portion27has inwardly-opening recesses formed by the inner surfaces of the respective six protrusions36to39,75, and76. Specifically, the upper portion of the housing portion35is formed with the front recess36a, the rear recess37a, and a central recess75acorresponding, respectively, to the front protrusion36, the rear protrusion37, and the central protrusion75of the upper wall32, while the lower portion of the housing portion35is formed with the front recess38a, the rear recess39a, and a central recess76acorresponding, respectively, to the front protrusion38, the rear protrusion39, and the central protrusion76of the lower wall33.

Differently from the hammer body24in the first embodiment, each of the front protrusions36and38, the rear protrusions37and39and the central protrusions75and76of the upper wall32and the lower wall33has a rear end thereof formed with an engaging portion for preventing fall-off of the mounting portion29of the weight73. Specifically, the rear ends of the front and rear protrusions36and37and the central protrusion75of the upper wall32have respective latching portions36b,37b, and75bformed on an opening-side end of the housing portion35, while the rear ends of the front and rear protrusions38and39and the central protrusion76of the lower wall33are formed with respective latching portions38b,39b, and76b.

The left side wall31of the weight mounting portion27has a front end thereof formed with a mounting hole72ato which the weight retaining member74is removably attached.

On the other hand, the mounting portion29of the weight73has a shape complementary to the opening28of the housing portion35of the weight mounting portion27of the hammer body72. Specifically, the upper portion of the mounting portion29is formed with the front protrusion51, the rear protrusion52, and a central protrusion81corresponding, respectively, to the front recess36a, the rear recess37a, and the central recess75aas the upper wall-side recesses, while the lower portion of the mounting portion29is formed with the front protrusion61, the rear protrusion62, and a central protrusion82corresponding, respectively, to the front recess38a, the rear recess39a, and the central recess76aas the lower wall-side recesses. The protrusions61,62, and82are formed to be equal in size to each other, and the two protrusions82and62central and rear are formed in a manner vertically symmetrical to the upper central protrusion81and the upper rear protrusion52. Further, the upper front protrusion51of the mounting portion29is formed to have a larger width in the front-rear direction and protrude further forward than the lower front protrusion61.

The weight retaining member74is a resin molded article made of the same resin material as the hammer body72. Further, the weight retaining member74is formed in a relatively small block shape, and has a protrusion (not shown) to be press-fitted in the mounting hole72aof the left side wall31of the weight mounting portion27.

Next, the method of mounting the weight73to the hammer body72will be described with reference toFIGS. 6A to 6C. First, the hammer body72, the weight73, and the weight retaining member74are prepared as shown inFIG. 6A, and the mounting portion29of the weight73is fitted in the housing portion35(fit-in position) of the weight mounting portion27via the opening28of the hammer body72as shown inFIG. 6B, similarly to the first embodiment. In this case, the front end of the mounting portion29is brought to a location close to the front wall34of the weight mounting portion27.

Then, one of the hammer body72and the weight73is fixed, and the other of the two is slid to thereby bring the front wall34of the weight mounting portion27and the front end of the mounting portion29away from each other, inversely to the case in the first embodiment. For example, inFIG. 6B, if the hammer body72is fixed, the weight73is slid rearward (rightward as viewed inFIG. 6B). As a consequence, the mounting hole72aof the weight mounting portion27faces outside via the opening28. Then, the weight retaining member74is inserted in between the front wall34of the weight mounting portion27and the front end of the mounting portion29and press-fitted in the mounting hole72a. Thus, the mounting portion29of the weight73is held in a fixed position shifted rearward of the fit-in position as shown inFIG. 6C, and the assembly of the hammer71is completed.

In the hammer71, each of the upper and lower front protrusions51and61, the upper and lower rear protrusions52and62, and the central protrusions81and82of the mounting portion29of the weight73has its rear end sandwiched between the left side wall31of the weight mounting portion27of the hammer body72and an associated one of the upper and lower latching portions36b,37b,38b,39b,75b, and76b. As a consequence, the mounting portion29is not only prevented from falling off from the opening28, but also made immovable in the direction of thickness thereof. Further, since the weight retaining member74functions as a wedge, the mounting portion29positioned in the fixed position is held unslidable to the fit-in position as well as immovable in the direction of length.

As described above, according to the present embodiment, it is possible to obtain the hammer71with the weight73securely mounted to the hammer body72such that it does not wobble, similarly to the first embodiment. Further, although work for mounting the weight retaining member74is required during assembly of the hammer71, and work for dismounting the weight retaining member74is required during disassembly of the hammer71, it is possible to assemble and disassemble the hammer71relatively easily.

It should be noted that the present invention is by no means limited to the above-described embodiments, but it can be practiced in various forms. Although in the above-described embodiments, the hammer4and the hammer71are applied to an electronic piano, the present invention is also applicable to hammers for other electronic keyboard instruments.

Further, although in the above-described embodiments, during assembly of the hammer4(71), the mounting portion29of the weight25(73) is fitted in the housing portion35of the weight mounting portion27of the hammer body24(72) and then slid in the front-rear direction of the housing portion35to be held in a state in which it is prevented from falling off from the opening28, this is not limitative, but it is also possible to configure a weight and a hammer body such that the mounting portion of the weight can be slid in a different direction from the front-rear direction, which is different from the left-right direction in which the mounting portion29is fitted in the housing portion35. Further, the details of the construction of the hammers4and71described in the respective embodiments are given only by way of example, and various changes and modifications may be made without departing from the spirit and scope of the present invention.