Hammer device for keyboard instrument

Abstract

A hammer device for a keyboard instrument, comprising a plurality of hammers (4), each of which is provided in association with an associated one of a plurality of keys (3), and which is pivotally supported on a frame (2) in a state in which they are arranged side by side in a left / right direction, and in which each of the hammers (4) is pivotally moved in a manner interlocked with the depression of the associated key (3), thereby transmitting the touch weight of the key (3). The frame (2) is formed as a molded article made of a synthetic resin and has a plurality of partition parts (50) each arranged between each pair of hammers (4) that are adjacent to each other in the left / right direction. Each of the hammers (4) comprises: a hammer body (31) formed as a molded article made of a synthetic resin and extending in a front / back direction.and pivotally supported on the frame (2) by a support (15) formed at a predetermined position of its front half, and a weight (32) extending in the front / rear direction, the weight (32) being attached to the rear half of the hammer body (31), and on the left and right side surfaces of the hammer body (31) between the support (15) and the weight (32), left and right opposing projections (39) are formed, which project outwardly from the weight (32) and each oppose an associated one of the separating parts (50) at a predetermined distance.

Description

BACKGROUND OF THE INVENTIONField of the InventionThe present invention relates to a hammer device for a keyboard instrument used for a keyboard instrument such as an electronic piano, and configured to transmit a touch weight by a hammer pivotally moved in a manner interlocked with depression of a key.Description of the Prior ArtAs a hammer device for a keyboard instrument such as an electronic piano, those disclosed in, for example, Japanese Patent Application Laid-Open (Kokai) Nos. 2011-022472 A and 2004-341321 A have conventionally been known. Each of these keyboard devices for which these hammer devices are respectively used includes a plurality of keys each extending in a front / rear direction, a plurality of hammers provided in association with the respective keys, and a keyboard frame for pivotally supporting the keys and the hammers thereon in a state arranged side by side in a left / right direction.The hammer disclosed in Japanese Patent Application Laid-Open (Kokai) JP 2011-022472 A includes a hammer body formed as a resin molded article and a metal weight detachably attached to the hammer body. The hammer body is formed in a predetermined shape extending in the front / rear direction, and has a front half pivotally supported on the keyboard frame and a rear half formed with a weight fixing portion having a predetermined shape. On the other hand, the weight is constituted by a metal plate extending in the front / rear direction. The weight has a front half formed with a mounting portion having a shape complementary to the weight mounting portion of the hammer body, and extends from the mounting portion to a location close to the rear end of the keyboard frame. The weight is configured to be able to be fixed to the hammer body by being pushed forward in a state where the fixing portion is fitted into the weight fixing portion of the hammer body, and to be removed from the hammer body by being pushed backward from the state where it is fixed to the hammer body.The keyboard frame is formed as a molded article made of a synthetic resin such as an ABS resin. The keyboard frame has a large number of vertical ribs formed to ensure the strength and rigidity of the keyboard frame while maintaining a space for the pivotal movement of each hammer performed in a manner associated with the depression of a key. Specifically, each of the ribs is formed in a plate shape having a predetermined thickness in the left / right direction and arranged in a manner separating the hammers that are adjacent to each other in the left / right direction.On the other hand, the hammer disclosed in Japanese Patent Application Laid-Open (Kokai) JP2004-341321A has a hammer body comprising a resin holder and a metal base plate and two weight plates mounted on the left and right side surfaces of the hammer body, respectively. The hammer body is formed in a general S shape by insert molding the metal base plate in the resin holder in the side view. At predetermined locations at a front end of the metal base plate, a rivet hole and two positioning holes are formed, each of which extends through the metal base plate in the left / right direction, respectively. On the other hand, the two weight plates are formed by respective metal plates having the same outer shape. Each of the weight plates has two positioning protrusions and rivet holes formed at the respective predetermined locations on a side surface of the hammer body. The two weight plates are fixed to the hammer body by clamping the metal base plate from both left and right sides and riveting the rivets inserted through the rivet holes of the two weight plates and the metal base plate, each of the positioning protrusions being fitted into an associated one of the positioning holes.In an electronic piano having the hammer device disclosed in Japanese Patent Application Laid-Open (Kokai) No. 2011-022472 A or Japanese Patent Application Laid-Open No. 2004-341321, the weight of each of the hammers associated with respective keys in a small pitch range is made heavier than that of each of the hammers associated with respective keys in a high pitch range to obtain a touch weight of a keyboard almost analogous to the touch weight of an acoustic piano during musical performance. For this reason, in the hammer device, generally, ordinary hammer bodies are used for the respective hammers, and plural kinds of weights or weight plates different in shape from each other are used to some the hammers different in weight according to each pitch range.However, in the hammer device disclosed in Japanese Patent Application Laid-Open (Kokai) JP 2011-022472 A, the shape of the attachment portion of the weight is the same for all the hammers, but it is necessary to form a plurality of protrusions at respective predetermined locations on the edge of the attachment portion of the weight in order to facilitate the removal of the weight from the hammer body, which complicates the shape of the attachment portion. Further, it is necessary to form a portion of the weight that is continuous with the mounting portion and extends rearward, so that the shape of the portion is greatly different based on the pitch range. On the other hand, in the hammer device disclosed in Japanese Patent Application Laid-Open (Kokai) No. 2004-341321, the two weight plates share a common outer shape, but it is necessary to form the two positioning protrusions so as to protrude in different directions. In addition, it is necessary that the two weight plates of each hammer are formed so that their shape is greatly different on a basis of the pitch range.As described above, the weight or the weight plate (hereinafter, generally referred to as "the weight") included in the hammer device disclosed in Japanese Patent Application Laid-Open (Kokai) JP 2011-022472 A or JP 2004-341321 A has a complicated shape, and a plurality of kinds of weights are required for an entire keyboard instrument. For this reason, a plurality of kinds of metal molds are necessary that allow a metal plate to be cut into complicated shapes to produce the above weights, resulting in increases in production costs. In addition, since the shape of the weight is complicated, there is a fear that the production efficiency and yield are lower.Further, assuming that the electronic piano is stored in a room in an upright position in which its left and right sides are located at vertically opposite positions, the keyboard frame made of a synthetic resin and the hammer body tend to bend downward when the room temperature becomes very high, for example, in summer, due to the dead weight of the keyboard frame and the weight of the hammers, which may cause the deformation of the keyboard frame and the hammer body. In this case, there is a possibility that noise is generated during musical performance, for example, due to rubbing of the metal weight of a hammer in a pivotal motion against an associated one of the vertical ribs of the keyboard frame made of synthetic resin. To avoid this, for example, during the manufacture of the electronic piano, a guide band having lubricity is wound around a portion of the weight of each hammer which can rub against a vertical rib associated therewith, thereby greatly reducing the noise generated due to the rubbing of the weight of the hammer against the keyboard frame.Generally, however, the keyboard device of an electronic piano is provided with the same number (e.g., 88) of hammers as the number of keys. For this reason, when it is necessary to wind the leader tape around the weight of each of the hammers, the tape winding work requires much time and labor and requires the leader tape, which causes an increase in manufacturing cost.Further examples of keyboard devices are disclosed in JP 2003-186475 A and US 2004 / 0261598 A1.SUMMARY OF THE INVENTIONAn object of the present invention is to provide a hammer device for a keyboard instrument which not only enables generation of noise to be prevented while ensuring smooth pivotal movement of a hammer but also achieves reduction in manufacturing cost.The present invention is achieved by the features of the main claim 1. Preferred embodiments are defined in the dependent claims.According to the present invention, there is provided a hammer device for a keyboard instrument, comprising a plurality of hammers each provided in association with an associated one of a plurality of keys, and pivotally supported on a frame in a state arranged side by side in a left / right direction, and in which each of the hammers is pivotally moved in a manner interlocked with depression of the associated key to thereby impart a touch weight of the key, wherein the frame is formed as a molded article made of a synthetic resin and having a plurality of partition members each provided between each pair of hammers which are adjacent to each other in the left / right direction, and each of the hammers comprises a hammer body formed as a molded article, which is made of a synthetic resin and extends in a front / rear direction and is pivotally supported on the frame by a bracket formed at a predetermined position of its front half and a weight extending in the front / rear direction, wherein the weight is attached to a rear half of the hammer body, and wherein on the left and right side surfaces of the hammer body between the bracket and the weight, left and right opposing protrusions are formed which protrude outward from the weight and each oppose each with a predetermined distance to an associated one of the partition parts.With the construction of the hammer device, the hammers associated with the respective keys are pivotally supported on the frame formed as a molded article of a synthetic resin in a manner arranged side by side in the left / right direction. The partition parts of the frame are respectively disposed between each pair of hammers that are adjacent to each other in the left / right direction. Further, the hammer body of each of the hammers is formed as a molded article made of a synthetic resin and extending in the front / rear direction. The hammer body is supported on the frame by a bracket formed at a predetermined location of the front half of the hammer body, and the weight extending in the front / rear direction is attached to the rear half of the hammer body. In addition, between the support and the weight, left and right opposing protrusions protruding outward from the weight are formed.The left and right opposing projections project outward, i.e., leftward and rightward, respectively, and are each opposed to the associated partition portion of the frame at a predetermined interval. Thus, in a case where a hammer is made to abut against the associated partition part of the frame, for example, due to deformation of the frame, because the distance between the opposing protrusion and the partition part is set smaller than that between the weight and the partition part, the opposing protrusion of the hammer body abuts against the partition part with priority over the weight, and therefore it is possible to avoid the impact of the weight of the hammer against the frame. This makes it possible to prevent generation of noise due to the impact of the weight of the hammer against the frame while ensuring smooth pivotal movement of the hammer. Further, it is not necessary to wind guide tapes around the respective weights as in the prior art, so that it is possible to achieve a reduction in manufacturing cost.Preferably, each of the opposing protrusions is formed in a curved shape in the side view extending along a concentric circle around the support.With this structure, each of the opposing protrusions has the above-described curved shape in the side view, so even when the opposing protrusion is brought into sliding contact with the partition part of the frame during the swinging movement of the hammer, it is possible to reduce a frictional force generated between the opposing protrusion and the frame, thereby ensuring smooth swinging movement of the hammer.More preferably, each of the opposing protrusions is formed with a groove for holding lubricant.With this structure, when the lubricant is applied to the left and right projections of the hammer body, a part of the lubricant enters the grooves of the respective opposing projections to be held therein. This makes it possible to maintain, over a long period of time, a state in which the lubricant is retained in each of the opposing protrusions of the left and right side surfaces, respectively. Therefore, when the hammer is pivotally moved in a manner associated with the depression of the key, even if the opposing protrusion of the hammer body is brought into sliding contact with the partition part of the frame, it is possible to ensure the smooth pivotal movement of the hammer while preventing the generation of noise due to the sliding contact.The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.Brief Description of the DrawingsFIG. 1 is a perspective view of a keyboard device (for the portion of an octave) of an electronic piano to which a hammer device according to an embodiment of the present invention is applied. FIG. 2A is a plan view of the keyboard device shown in FIG. 1. FIG. 2B is a cross-sectional view of the keyboard device shown in FIG. 1, taken on line b--b of FIG. 2A. FIG. 3A is an exploded perspective view of a keyboard frame and the keys of the keyboard apparatus in FIG. 1. FIG. 3B is an enlarged perspective view of a part of a rear end of the keyboard frame in FIG. 1. FIG. 4 is a perspective view of a white key and a black key. FIG. 5A is an enlarged plan view of a rear portion of the button. FIG. 5B is an enlarged right side view of the rear portion of the button. FIG. 6A is a perspective view of the appearance of a hammer. FIG. 6B is an exploded perspective view of the hammer disassembled into a hammer body and weights. FIG. 7 is a view useful for explaining the relationship between the hammer and the keyboard frame. FIG. 8A is an enlarged view of the hammer and a separating part of the keyboard frame. FIG. 8B is a cross-sectional view of the hammer and the separation part of the keyboard frame taken on the line b--b of FIG. 8A. FIGS. 9A to 9F are views useful for explaining the weights of the hammer, in which: FIG. 9A shows a general weight in a state attached to the hammer body; and FIGS. 9B to 9F show adjusting weights in a state before being attached to the hammer body.DETAILED DESCRIPTION OF PREFERRED EMBODIMENTSThe present invention will now be described in detail with reference to the drawings showing a preferred embodiment thereof. FIGS. 1, 2A, and 2B show a keyboard device of an electronic piano in a key released state to which a hammer device according to the embodiment is applied. Note that FIGS. 1, 2A, and 2B show only the range of an octave of the keyboard device.As shown in FIGS. 1, 2A and 2B, the keyboard apparatus 1 includes a keyboard frame 2 (frame), a plurality of keys 3 including white keys 3 aand black keys 3 b swingably mounted on the keyboard frame 2 and mounted in the left / right direction, a plurality of hammers 4 swingably mounted on the keyboard frame 2 in association with the corresponding keys 3, and a key switch 5 for detecting the information on the depression of a key via each key 3.The keyboard frame 2 is formed as a resin molded article formed by, for example, injection molding a predetermined resin material (e.g., an ABS resin) into a predetermined shape. As shown in FIG. 3A, the keyboard frame 2 has a front part 11, a central part 12, and a rear part 13 each extending as a whole in the left / right direction. The front part 11, the central part 12 and the rear part 13 are connected to each other by a plurality of ribs 14 disposed with an appropriate interval therebetween in the left / right direction. Note that in the following description, the front part 11, the central part 12, and the rear part 13 of the keyboard frame 2 will be referred to as "the frame front side 11", "the frame center 12", and "the frame rear side 13", respectively.The frame front 11 serves to guide the white keys 3a. The frame front 11 has a plurality (seven in Fig. 3a) of white key guide portions 11a erected thereon, each inserted from below into a corresponding one of the white keys 3a to prevent the white key 3a from swinging sideways. Further, the frame front 11 has engaging holes 11b and 11b vertically extending therethrough formed on the left and right sides of each of the white key guide portions 11a, respectively. A pair of left and right upper limit position regulating parts 21 aand 21 a, referred to below, of the white keys 3 aengages with the corresponding engaging holes 11 band 11 bin a state of being inserted therethrough.The frame center 12 serves to guide the black keys 3b. Similarly to the frame front 11, the frame center 12 has a plurality (five in Fig. 3A) of black key guide portions 12a erected thereon, each of which is inserted from below into a corresponding one of the black keys 3a to prevent lateral swing of the black key 3b. Further, at a position forward of the frame center 12, a hammer support member 15 is disposed to support the hammers 4. The hammer support part 15 has a plurality of support shafts 15 aextending along a single straight line extending in the left / right direction, and the hammers 4 are pivotally supported by the support shafts 15 a, respectively.Further, between the hammer support part 15 and the frame front 11, the key switch 5 is fixed. The key switch 5 includes a laterally elongated printed circuit board 5a extending in the left / right direction and a plurality of switch bodies 5b each formed by a rubber switch and mounted on the printed circuit board 5a in association with each key 3.The frame back 13 serves to support the buttons 3 by their rear ends so that the buttons 3 can pivotally move in the vertical direction. As shown in FIG. 3B, the frame back 13 is provided with a plurality of partition walls 16 formed with a predetermined interval therebetween in the left / right direction so that the adjacent keys 3 and 3 are separated from each other. Further, between each pair of the neighborhoods of the partition walls 16, a predetermined key supporting part 17 having a laterally symmetrical shape and configured to pivotally support an associated one of the keys 3 is formed. Specifically, the key support part 17 has left and right lower support portions 18 and 18 (only the left of which is shown in FIG. 3B ) for supporting from below left and right pivot shafts 24 and 24, referred to below, respectively, and a pair of left and right upper support portions 19 and 19 for supporting from above a portion of a rear end of the key 3 extending from the upper surface of the key 3 to its rear surface.The button 3 is formed by, for example, injection molding a predetermined resin material (e.g., an AS resin) into a hollow shape that extends over a predetermined length in the front / rear direction and opens downward. As shown in FIGS. 3A and 4, the white key 3a has a front end formed with the pair of left and right upper limit position regulating parts 21 (21a) extending downward from the respective side walls of the front end of the white key 3a and each bent forward at its lower end. The upper limit position regulating members 21 (21a) engage with the left and right engaging holes 11b and 11b of the frame front 11 in a state of being inserted therethrough. Further, the white key 3a has an actuator part 22 (22a) protruding downward formed at a predetermined location rearward of the upper limit position regulating parts 21a. The actuator part 22 ( 22 a) engages with an engagement recess 34, referred to below, of the hammer 4 in a state of being accommodated therein. On the other hand, the black key 3 bhas a front end formed with a regulating part 21 ( 21 b) and an actuator part 22 ( 22 b) each having the same functions as those of the upper limit position regulating parts 21 aand the actuator part 22 aof the white key 3 a.As shown in FIGS. 4, 5A and 5B, the button 3 has a rear part including a rear body 23 formed to have a width smaller than that of the part of the button 3 forward thereof and extending in the front / rear direction. The pivot shafts 24 and 24 protruding outward (i.e., leftward and rightward, respectively) are formed on the left and right side surfaces of the rear body 23 at respective predetermined locations near a rear end of the rear body 23. Each of the pivot shafts 24 and 24 has a lower half formed as a semicircular portion 24 athat has a curved lower surface and a semicircular side surface, and a protrusion 24 bthat protrudes upward from the center of the semicircular portion 24 ain the front / rear direction. Note that the semicircular portion 24 aof each of the pivot shafts 24 has a groove 24 cformed in its curved lower surface, so that when a lubricant such as grease is applied to the curved lower surface of the semicircular portion 24 a, the grease can be held therein for a long time.The rear end of the rear body 23 is formed such that a curved surface 25 having a predetermined curvature extends from the upper surface of the rear surface of the rear body 23. The bent surface 25 is formed to be convexly bent along a concentric circle around the pivot shaft 24 of the key 3 in the side view. Further, the rear end of the rear body 23 has a tapered portion 26 continuous with the curved surface 25 and having a lateral width which gradually decreases downward. Note that the bent surface 25 is formed with a groove 25 athat has the same function as that of the groove 24 cof the pivot shaft 24.As shown in FIGS. 6A and 6B, the hammer 4 includes a hammer body 31 and two weights 32 and 32 attached to the hammer body 31. The hammer body 31 is formed as a resin molded article manufactured by, for example, injection molding a predetermined resin material (e.g., POM (polyacetal resin)) into a predetermined shape. The hammer body 31 extends over a predetermined length in the front / rear direction and has a bearing portion 33 formed at a predetermined location forward of the center of the hammer body 31 in the front / rear direction. The bearing portion 33 has an opening in an inverted U-shape downwardly in side view and pivotally engages with the support shaft 15 aof the hammer support part 15 of the keyboard frame 2. The engaging recess 34 for engaging with the actuator part 22 of the key 3 is formed in the front half of the hammer body 31 at a location forward of the bearing portion 33. The engagement recess 34 is open upward and forward, and the lower portion of the actuator part 22 of the button 3 is accommodated in the engagement recess 34 in a state where a lower end of the actuator part 22 is held in contact with a lower surface of the engagement recess. Further, a plurality of switch pressing portions 35 are formed under the engaging recess 34 in the front half of the hammer body 31 to press the switch body 5b of the key switch 5.A weight fixing portion 36 as a rear half of the hammer body 31 has two, i.e., front and rear, pairs of engaging protrusions 37 and 37 formed on the left and right side surfaces of the weight fixing portion, respectively, at predetermined positions in a manner to protrude outward, i.e., leftward and rightward, from the weight fixing part 36, and a fixing hole 38 formed at a position close to the rear pair of engaging protrusions 37 in a manner to extend through the weight fixing part 36 in the left / right direction. Note that a cutout 36 ais formed in a central portion of the weight fixing part 36 to prevent screws and the like that fix the keyboard device 1 to the key bed 10 of an electronic piano (see FIGS. 2A and 2B ) from interfering with the hammer 4 when the keyboard device 1 is in the key-released state.The weights 32 are made of a material (metal such as steel) having a larger specific gravity than the hammer body 31, and are formed as two long and narrow plates. Each of the weights 32 is formed by pressing a long metal plate having a predetermined thickness and width into a predetermined shape. Specifically, the weight 32 is formed with two engaging holes 41 and 41, i.e., front and rear, a mounting hole 42 and a recess 43 respectively corresponding to the two engaging protrusions 37 and 37, the mounting hole 38 and the cutout 36 aformed in the hammer body 31. The two weights 32 and 32 are firmly secured to the hammer body 31 by riveting rivets 44 inserted through the attachment holes 42, 42 and 38 in a state in which the weight attachment part 36 of the hammer body 31 is inserted.One of the weights attached to each of the hammers 4 (hereinafter referred to as "the general weight 32A") has a predetermined length and the same for all the hammers 4. On the other hand, the other weight (hereinafter referred to as "the adjustment weight 32B") is formed to have a length equal to or smaller than that of the general weight 32A. Therefore, it is possible to change the weight of the hammer 4 including the two weights 32A and 32B by adjusting the length of the adjusting weight 32B.In the keyboard apparatus 1 constructed as above, when the key 3 is depressed in the key released state shown in Figs. 1 and 2B, the key 3 pivotally moves downward about the left and right pivot shafts 24 and 24 of the rear end of the key 3. In accordance with this pivotal movement of the key 3, the actuator portion 22 of the key 3 presses down the engaging recess 34 of the hammer 4. As a result, the hammer 4 pushes, from above, the associated switch body 5 bof the key switch 5 through the switch pushing portion 35 while pivotally moving about the support shaft 15 aof the hammer support part 15 in the counterclockwise direction as viewed in FIG. 2B. In this case, the rear end of the hammer 4 (i.e., the rear end of the general weight 32A) is brought into abutment with a hammer stopper 13 aof the frame rear 13 from below, thereby blocking the further pivotal movement of the hammer 4. By the above-described operation of depressing the key, a predetermined touch weight corresponding to the weight and the torque of the hammer 4 is given to the key 3, and the information on the depression of the key via the key 3 is simultaneously detected by the key switch 5.On the other hand, when the depressed key 3 is released, the hammer 4 pivotally moves in the clockwise direction as viewed in Fig. 2B. In accordance with this swinging movement of the hammer 4, the key 3 is pushed up by the actuator part 22 and pivotally moves up. As a result, the key 3 and the hammer 4 return to the key released state as shown in FIGS. 1 and 2B. In this case, the upper limit position regulating members 21 of the front end of the key 3 are brought into abutment from below with a predetermined stopping device 20 of the keyboard frame 2, thereby inhibiting the further pivotal movement of the key 3.Next, a further detailed description will be given of the hammer device according to the present invention with reference to Figs. 6A, 6B and 7 to 9F focusing on the construction of the hammer 4. FIG. 7 shows the hammer and left and right separation parts 50 and 50 (only one of which is shown) provided in the frame center 20 in a state near the left and right sides (the near and far sides as viewed in FIG. 7 ) of the hammer 4, respectively.The hammer body 31 has left and right opposing projections 39 and 39 formed on its left and right side surfaces, respectively, at a central location in the front / rear direction. The opposing projections are opposed to the left and right partition parts 50 and 50, respectively, at a predetermined interval (e.g., 0.2 mm). Each of the opposing protrusions 39 and 39 is formed in a manner to protrude outward from the associated weight 32 by a predetermined length (e.g., 0.5 mm) and extend along a concentric circle curved about the pivotal motion support (support shaft 15 a) of the hammer body 31. Further, each of the opposing protrusions 39 and 39 is formed with a groove 39 aextending along its longitudinal direction, so that when lubricant such as grease is applied to the opposing protrusions 39, the grease can be retained therein for a long period of time.In the frame center 12, the separation parts 50 vertically extend from a horizontally flat portion 12 bof the frame center 12 so as to separate each of the hammers 4 and 4 that are adjacent to each other in the left / right direction (see FIG. 3A ). As shown in FIGS. 7, 8A, and 8B, each of the partition members 50 includes a partition wall 50 athat has a predetermined thickness in the left / right direction (near / far direction when viewed in FIGS. 7 and 8A and vertical direction when viewed in FIG. 8 ) and a guide protrusion 50 bthat extends along the left and right side walls of the partition wall 50 aand protrudes toward the associated one of the hammers 4. In the key-released state shown in FIG. 7, an upper portion of the opposing protrusion 39 of the hammer 4 is opposed to a lower end of the guide protrusion 50 bof the partition member 50 with a distance as shown in FIGS. 8A and 8B.Further, as mentioned above, all the hammers 4 have the same general weight 32A, and therefore, all the general weights 32A are identical in shape and size to each other. On the other hand, each of the adjustment weights 32B has its length differently adjusted in the front / rear direction according to a touch weight required by the associated button 3. Specifically, the adjustment weights 32B for the hammers 4 associated with the respective keys 3 in a low pitch range are formed to be longer, while the adjustment weights 32B for the hammers 4 associated with the respective keys 3 in a high pitch range are formed to be shorter.FIG. 9A shows the general weight 32A (first weight) attached to the hammer body 31, and FIGS. 9B to 9F show the respective adjustment weights 32B (second weights) different in length from each other. As shown in FIGS. 9A to 9F, the general weight 32A and the adjusting weight 32B each have a general fastening portion 40 fastened to the weight fastening portion 36 of the associated one of the hammer bodies 31. More specifically, the general fastening portion 40 of each of all the weights 32A and 32B is formed with two engagement holes 41 and 41, a fastening hole 42 and a recess 43 respectively corresponding to the two engagement protrusions 37 and 37, the fastening hole 38 and the cut-out 36 aformed in the hammer body 31, and all the weights 32A and 32B have the two engagement holes 41 and 41, the fastening hole 42 and the recess 43 in the same size and position.Therefore, when the general weight 32A and the adjustment weight 32B are manufactured, a long metal plate having the same thickness and width as those of each weight to be manufactured is prepared. Then, the general fixing portion 40 is formed in the metal plate by, for example, press working, and the metal plate is cut into the desired length, whereby it is possible to produce the general weight 32A and the adjustment weight 32B with relative ease.As described above in detail, according to the present invention, the general weight 32A and the adjusting weight 32B are attached to the hammer body 31, whereby more than half of the weight required by the hammer 4 is provided by the general weight 32A and the weight is adjusted by the adjusting weight 32B. The general weight 32A is the same for all the hammers 4, so that when one of the hammers 4 is pivotally moved, the movement path of the rear end of the general weight 32A forms the same path. This allows the hammer stopper 31 ato be disposed in the frame rear 13 of the keyboard frame 2 in a manner extending along a single straight line in the left / right direction, thereby obtaining a stable swing angle when the hammer 4 is pivotally moved in a manner associated with depressing the associated key 3. Further, the weight of the adjustment weight 32B is adjusted as desired by setting the length in the front / rear direction. Therefore, unlike the prior art using weights having a complicated outer shape, it is possible to improve the manufacturing efficiency and yield concerning the two weights 32A and 32B attached to each hammer body 31 while suppressing an increase in manufacturing cost. Further, since the attachment portion 40 of the general weight 32A and the adjustment weight 32B to be attached to the weight attachment portion 36 of the hammer body 31 are identical in structure to each other, it is possible to efficiently form the attachment portions 40 using a single shape or the like.Further, according to the present invention, the left and right opposing projections 39 and 39 of the hammer 4 project outward, i.e., leftward and rightward, respectively, and the left and right opposing projections 39 and 39 are respectively opposed to the guide projection 50b of the associated partition part 50 of the keyboard frame 2 by a predetermined distance. As a result, when the hammer is caused to abut with the separating part 50 due to, for example, the deformation of the keyboard frame, the opposing protrusion 39 protruding outward from the hammer body 31 takes priority over the weights 32 to abut with the separating part 50, making it possible to avoid the abutment of the weight 32 of the hammer 4 against the keyboard frame 2. This makes it possible to prevent generation of noise due to the abutment of the weight 32 of the hammer 4 against the keyboard frame 2 while ensuring smooth pivotal movement of the hammer 4. Further, it is not necessary to wind guide tapes around the respective weights 32 of the hammer as in the prior art, so that a reduction in manufacturing cost can be achieved. Moreover, each of the opposing projections 39 has a curved shape in side view extending along a concentric circle around the swinging support of the hammer body 31, so that even if the opposing projection 39 is brought into sliding contact with the guide projection 50b of the keyboard frame 2 during the swinging movement of the hammer 4, it is possible to reduce the frictional force generated between the two, thereby ensuring smooth swinging movement of the hammer 4.Note that the present invention is by no means limited to the above-described embodiment, but may be embodied in various ways. For example, although the hammer device of the present invention is applied to the keyboard device of the electronic piano in the present embodiment, the hammer device may be applied to other keyboard instruments such as an electronic organ. Further, the structure of the weight fixing portion 36 of the hammer body 31 and that of the fixing portion 40 of the weight 32 are not particularly limited, but it is possible to form the weight fixing portion 36 and the fixing portion 40 in various shapes as long as the weight 32 can be attached to the hammer body 31. In addition, the position and the shape of the left and right opposing projections 39 and 39 of the hammer 4 are also not particularly limited, but any position or shape may be adopted as long as it is possible to prevent the side surfaces of the weight 32 from rubbing against the keyboard frame 2 during the pivotal movement of the hammer 4.Further, the details of the construction of the hammer body 31, the general weight 32A and the adjusting weight 32B of the hammer 4, the partition part 50 of the keyboard frame 2 and so forth described in the embodiment are given by way of example only, and various changes and modifications can be made without departing from the scope of the present invention which is defined by the claims.

Claims

A hammer device for a keyboard instrument, comprising a plurality of hammers (4), each of which is provided in association with an associated one of a plurality of keys (3), and which is pivotally supported on a frame (2) in a state of being arranged side by side in a left / right direction, and in which each of the hammers (4) is pivotally moved in a manner interlocked with depressing of the associated key (3) to thereby transmit the touch weight of the key (3), wherein the frame (2) is formed as a molded article made of a synthetic resin and has a plurality of partition parts (50) each arranged between each pair of the hammers (4) that are adjacent to each other in the left / right direction, and wherein each of the hammers (4) comprises: a hammer body (31), which is formed as a molded article made of a synthetic resin and extending in a front / rear direction and is pivotally supported on the frame (2) by a bracket (15) formed at a predetermined position of its front half and a weight (32) extending in the front / rear direction, the weight (32) being attached to the rear half of the hammer body (31), and wherein on the left and right side surfaces of the hammer body (31) between the bracket (15) and the weight (32), left and right opposing protrusions (39) are formed which protrude outward from the weight (32) and each oppose an associated one of the partition members (50) with a predetermined distance.The hammer device according to claim 1, wherein each of the opposing protrusions (39) is formed in a curved shape in the side view extending along a concentric circle around the support (15).The hammer device according to claim 2, wherein each of the opposing protrusions (39) is formed with a groove (39a) for holding lubricant.

Images