Keyboard device of a keyboard instrument

Abstract

To provide a keyboard device for a keyboard musical instrument capable of effectively suppressing detachment of a hammer from a support shaft when the impact is applied and easily removing the hammer.SOLUTION: A keyboard device 1 of the present invention includes: a keyboard chassis 4 (chassis); rotatable keys 2; and first arms 31 (hammers) rotatably supported on first spindles 18a (support shafts) of the keyboard chassis 4 and rotating in conjunction with the depressed keys 2. The first arm 31 includes: a shaft hole 36a which can be fitted to the first spindle 18a; and a guide groove 36b which extends obliquely upward from the lower surface of the first arm 31 so as to continue to the shaft hole 36a, has a groove width W smaller than the diameter D of the first spindle 18a and guides the shaft hole 36a to the first spindle 18a when the first arm 31 is mounted.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a keyboard device for a keyboard instrument such as an electronic piano, which includes a hammer that rotates in conjunction with a key that is pressed.

Background Art

[0002] As a conventional keyboard device of this type, for example, the one disclosed in Patent Document 1 is known. This keyboard device includes a chassis made of synthetic resin, and the hammer is rotatably supported by a hammer support shaft (hereinafter simply referred to as "support shaft") of the chassis. The support shaft is integral with the chassis, protrudes laterally, and has a circular cross-section. On the other hand, the hammer is made of synthetic resin and integrally has a hammer body extending in the front-rear direction and a bearing portion provided in the middle thereof and supported by the support shaft. The bearing portion is formed in a C shape that opens rearward, and has a central circular holding hole and a guide groove that is continuous with the holding hole and opens rearward. Further, the guide groove extends substantially horizontally in the key-released state, is tapered toward the holding hole, and its minimum width is smaller than the diameter of the support shaft.

[0003] In the above configuration, when attaching the hammer to the support shaft, the bearing portion of the hammer is positioned on the front side of the support shaft, the guide groove is engaged with the support shaft, and then the hammer is pressed backward. As a result, with the guide groove being expanded by the support shaft, the hammer moves backward while being guided by the guide groove. Then, when the guide groove gets over the support shaft and the holding hole fits onto the support shaft, the hammer is rotatably supported by the support shaft via the bearing portion.

[0004] Also, in the keyboard device disclosed in Patent Document 2, the hammer has a shaft hole that fits onto the support shaft of the chassis and a guide groove that is continuous with the shaft hole and opens downward, and is fitted onto the support shaft from above via the guide groove.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] When a keyboard device is transported as a product, it is mainly subject to impacts in the front-rear direction and the up-down direction. In contrast, in the keyboard device of Patent Document 1 described above, the hammer is fitted onto the support shaft from the front through a substantially horizontal guide groove. Therefore, when an impact in the front-rear direction acts during transportation or the like, since the direction of the inertial force caused thereby substantially coincides with the fitting direction of the hammer, there is a risk that the hammer may become detached from the support shaft even if the guide groove is provided with a constriction. Similarly, in the keyboard device of Patent Document 2, since the hammer is fitted onto the support shaft from above, there is a risk that the hammer may become detached from the support shaft when an impact in the up-down direction acts.

[0008] The present invention has been made to solve the above-described problems, and can effectively suppress the detachment of the hammer from the support shaft when an impact acts The key and an object thereof is to provide a keyboard device for a stringed musical instrument.

Means for Solving the Problems

[0009] To achieve this object, the invention according to claim 1 includes a chassis, a rotatable key, and a hammer that is rotatably supported by a support shaft of the chassis and rotates in conjunction with the key that is pressed. The hammer has a shaft hole that can be fitted onto the support shaft, and a groove that extends obliquely upward so as to be continuous with the shaft hole from the lower surface of the hammer and has a groove width smaller than the diameter of the support shaft, and a guide groove that guides the shaft hole onto the support shaft when the hammer is attached. and the guide groove extends obliquely at an angle of 45 ± 15 degrees with respect to the horizontal in the key-released state It is characterized by the above.

[0010] According to this configuration, when attaching the hammer to the support shaft, the shaft hole and the guide groove of the hammer are positioned diagonally above the support shaft. After engaging the guide groove with the support shaft, the hammer is pressed diagonally downward along the guide groove. As a result, with the guide groove having a narrow groove width being elastically expanded by the support shaft, the hammer moves diagonally downward while being guided by the guide groove. Then, when the guide groove crosses over the support shaft, the guide groove elastically returns, and at the same time, the shaft hole fits (snaps) onto the support shaft. Thereby, the hammer is attached to the support shaft via the shaft hole and is rotatably supported.

[0011] As described above, the hammer is snap-fitted to the support shaft via the shaft hole. Further, a guide groove extends diagonally between the shaft hole from the lower surface of the hammer. Therefore, when impacts in the front-rear direction or the up-down direction act on the keyboard device during transportation of the product or the like, since the direction of the inertial force due to this is significantly different from the direction of the guide groove, the inertial force is dispersed. As a result, it is possible to effectively suppress the detachment of the hammer from the support shaft when an impact acts.

[0013] Also If the inclination angle of the guide groove with respect to the horizontal is greater than 60 degrees, the guide groove becomes closer to vertical, so the dispersion of the inertial force when an up-down impact acts becomes insufficient. On the other hand, if the inclination angle of the guide groove is less than 30 degrees, the guide groove becomes closer to horizontal, so the dispersion of the inertial force when a front-rear impact acts becomes insufficient. Therefore, the above According to the configuration of, since the inclination angle of the guide groove with respect to the horizontal is 45 ± 15 degrees, it is possible to effectively suppress the detachment of the hammer by sufficiently dispersing the inertial force due to the impact.

[0014] Claim 2 The invention according to relates to claim to 1 In the keyboard device of the keyboard musical instrument described in, the hammer is characterized in that an uneven portion is formed on the hammer with which a tool for moving the hammer diagonally upward from the support shaft and removing it engages.

[0015] Claim of 1In the keyboard device, since the hammer is snap-fitted to the support shaft, it is difficult to remove the hammer for repair or the like. According to this configuration, uneven portions are formed on the hammer, and by operating a tool engaged with the uneven portions and moving the hammer obliquely upward in the extending direction of the guide groove, the hammer can be easily removed from the support shaft.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiment for Carrying out the Invention

[0017] Hereinafter, with reference to the drawings, preferred embodiments of the present invention will be described in detail. FIG. 1(a) shows only one octave of the keyboard device 1 to which the present invention is applied. In the following description, first, the basic configuration and operation of the keyboard device 1 will be described, and then the main part of the present invention will be described.

[0018] FIG. 1(b) shows a state in which the keys 2 other than the leftmost white key 2a and black key 2b are omitted in the keyboard device 1 of FIG. 1(a), and FIG. 2 shows a state in which the white key 2a and black key 2b are removed from the keyboard chassis 4 together with the key support mechanism 6.

[0019] This keyboard device 1 includes a keyboard chassis 4, a plurality of keys 2 composed of white keys 2a and black keys 2b arranged side by side in the left - right direction, a key support mechanism 6 that is rotatably attached to the keyboard chassis 4 for each key 2 and supports the corresponding key 2 from below, a key switch 3 for detecting the key - pressing information of each key 2, and the like.

[0020] The keyboard chassis 4 includes a chassis main body 4a made of a resin molded product having a predetermined shape by injection molding a predetermined resin material (for example, ABS resin). As shown in FIG. 3, in this chassis main body 4a, its front portion 11, middle portion 12, and rear portion 13 are all formed so as to extend in the left - right direction (the left - right direction in FIG. 3(a)) as a whole, and these are integrally molded by a plurality of ribs 14 that are spaced apart in the left - right direction and each extend in the front - rear direction. In the following description, in the keyboard chassis 4, the front portion 11, middle portion 12, and rear portion 13 of the chassis main body 4a are referred to as the "chassis front portion 11", "chassis middle portion 12", and "chassis rear portion 13", respectively.

[0021] The chassis front portion 11 mainly serves to guide the white keys 2a when pressing the keys and to regulate the upper and lower limit positions of the front end portion thereof. In this chassis front portion 11, a plurality of white - key guides 11a for preventing the lateral movement of the white keys 2a, which are inserted from below for each white key 2a, are erected in a side - by - side state in the left - right direction. Further, in the chassis front portion 11, engagement holes 11b, 11b penetrating in the vertical direction are provided on both the left and right sides of each white - key guide 11a, and the left and right two upper - limit position regulating portions 21, 21 of the white keys 2a, which will be described later, penetrate and engage with the two engagement holes 11b, 11b, respectively. Furthermore, in the chassis front portion 11, at its front end portion, a stopper mounting portion 11c protruding forward and extending in the left - right direction over the entire chassis main body 4a is provided, and a key upper - limit stopper 16a and a key lower - limit stopper 16b for the white keys are mounted on the lower surface and the upper surface of this stopper mounting portion 11c, respectively, so as to extend in the left - right direction. In addition, in the chassis front portion 11, at a predetermined position behind the white - key guide 11a, a stopper mounting portion 11d for the black keys extending in the left - right direction over the entire chassis main body 4a is provided, and a key upper - limit stopper 17 for the black keys is mounted on this stopper mounting portion 11d so as to extend in the left - right direction.

[0022] The middle part 12 of the chassis mainly guides the black keys 2b when a key is pressed, and swingably supports the first arm 31 and the second arm 32 of the key support mechanisms 6a and 6b for the white keys and the black keys, which will be described later. This middle part 12 of the chassis has a flat part 12a in the shape of a flat plate extending in the left-right direction, and a plurality of black key guides 12b erected on this flat part 12a and arranged at appropriate intervals in the left-right direction. Each black key guide 12b is inserted from below for each black key 2b to prevent lateral movement of the black key 2b. Further, at the front part of the middle part 12 of the chassis, a first arm support part 18 for supporting the first arm 31 of the key support mechanism 6 is provided. This first arm support part 18 has a plurality of first support shafts 18a provided so as to extend in the left-right direction between adjacent ribs 14, 14, and the first arm 31 is swingably supported by these first support shafts 18a. Furthermore, at the rear part of the middle part 12 of the chassis, a second arm support part 19 for supporting the second arm 32 of the key support mechanism 6 is provided. This second arm support part 19 has a plurality of second support shafts 19a provided so as to extend in the left-right direction between adjacent ribs 14, 14. The plurality of second support shafts 19a are arranged on the same axis extending in the left-right direction at a position behind and higher than the above-mentioned first support shafts 18a, and the second arm 32 is swingably supported by these second support shafts 19a. In addition, at a predetermined position of a middle rail 8, which will be described later, provided below the middle part 12 of the chassis, a first arm lower limit stopper 10b extending in the left-right direction over the entire chassis body 4a is provided.

[0023] Also, below the keyboard chassis 4, between the front part 11 of the chassis and the middle part 12 of the chassis, the key switch 3 is attached. This key switch 3 is composed of a horizontally long printed circuit board 3a extending in the left-right direction, and a plurality of switch bodies 3b each composed of a rubber switch attached to this printed circuit board 3a for each key 2 and pressed by the first arm 31 when a key is pressed.

[0024] The rear part 13 of the chassis mainly serves to guide the key 2 in the vertical direction while preventing lateral movement at its rear end, and to regulate the upper limit position of the rear end of the first arm 31. As shown in FIGS. 2 and 3(a), the rear part 13 of the chassis has a plurality of partition walls 13a spaced apart from each other at a predetermined interval in the left-right direction so as to partition adjacent keys 2, 2. Further, as shown in FIG. 3(b), at a predetermined position in the upper part of the rear part 13 of the chassis, a first arm upper limit stopper 10a extending in the left-right direction over the entire chassis body 4a is provided. The first arm upper limit stopper 10a and the first arm lower limit stopper 10b provided in the middle part 12 of the chassis each have a function as a hammer for imparting a touch weight to the key 2, and regulate the upper limit position and the lower limit position when the first arm 31 rotates upward and downward with respect to the first arm 31. Further, a metal cover plate 15 extending in the left-right direction over the entire chassis body 4a and arranged to cover the rear end of the key 2 is attached to the upper part of the rear part 13 of the chassis.

[0025] As shown in FIGS. 2 and 3(a), the chassis body 4a of the keyboard chassis 4 configured as described above is provided with a plurality of first openings 5a opening upward and forward and a plurality of second openings 5b opening upward. Through each of the above-mentioned first openings 5a, the first arm 31 of the key support mechanism 6 is engaged with the first support shaft 18a from the outside, and through each of the above-mentioned second openings 5b, the second arm 32 is engaged with the second support shaft 19a from the outside.

[0026] In the above-mentioned keyboard chassis 4, a plurality of chassis bodies 4a are connected in a state of being arranged side by side in the left-right direction, and are all screwed in a state of being placed on metal front rails 7, middle rails 8, and rear rails 9 that extend in the left-right direction and are arranged at a predetermined interval in the front-rear direction. Then, the keyboard chassis 4 is fixed on a shelf board (not shown) of the electronic piano via the above-mentioned front rail 7 and rear rail 9.

[0027] Next, the key 2 and the key support mechanism 6 will be described. Fig. 4(a) shows an enlarged view of the white key 2a and its key support mechanism 6a, and Fig. 4(b) shows an exploded view thereof. As shown in the figure, the white key 2a is formed in a hollow shape that extends a predetermined length in the front-rear direction and is open downward by injection molding a predetermined resin material (for example, AS resin). At the front end of the white key 2a, a pair of left and right upper limit position regulating portions 21, 21 are provided, which are formed to extend downward from the left and right side walls and have their lower ends bent forward. These upper limit position regulating portions 21, 21 engage with the left and right engaging holes 11b, 11b of the front portion of the chassis 11 in a penetrating state as described above.

[0028] Also, at a predetermined position behind the upper limit position regulating portion 21 in the front portion of the white key 2a, a key front side connecting portion 22 connected to the first arm 31 of the key support mechanism 6a is provided. This key front side connecting portion 22 has a connecting recess 22a formed in a U shape with a long hole-shaped side surface and open forward. Further, in this connecting recess 22a, a key side noise suppressing member 20 for suppressing the generation of noise is attached so as to cover the entire inner peripheral surface thereof when the connecting shaft 35b, which will be described later, of the first arm 31 slides within the connecting recess 22a.

[0029] Furthermore, at the rear portion of the white key 2a, a key rear side connecting portion 23 connected to the second arm 32 of the key support mechanism 6a is provided. This key rear side connecting portion 23 has a plate-shaped connecting main body portion 23a that hangs downward from the central portion of the white key 2a in the left-right direction and has a predetermined thickness in the left-right direction, and a pair of left and right engaging convex portions 23b, 23b that project coaxially from the left and right side surfaces of this connecting main body portion 23a, respectively. Also, at the rear portion of the white key 2a, a tool insertion hole 24 is formed that penetrates in the vertical direction and is for inserting a predetermined tool from above when disconnecting the connection between the white key 2a and the second arm 32 of the key support mechanism 6a during maintenance of the keyboard device 1 or the like.

[0030] On the other hand, the key support mechanism 6a includes a first arm 31 and a second arm 32 that engage with each other and are respectively connected to the key front side connecting portion 22 and the key rear side connecting portion 23 of the white key 2a.

[0031] As shown in FIG. 4(b), the first arm 31 is composed of an arm main body 33 and two weights 34, 34 attached to the arm main body 33. The arm main body 33 is composed of a resin molded product with a predetermined shape by injection molding a predetermined resin material (for example, polyacetal). The arm main body 33 extends a predetermined length in the front-rear direction, and a first arm front-side connecting portion 35 for connecting to the key front-side connecting portion 22 of the white key 2a is provided at the front end portion. The first arm front-side connecting portion 35 has a box portion 35a formed in a box shape that is open upward and forward, and a connecting shaft 35b provided so as to extend in the left-right direction while connecting the front upper end portions of the left and right side walls of the box portion 35a. And this connecting shaft 35b is connected to the connecting recess 22a of the key front-side connecting portion 22 of the white key 2a so as to be rotatable and slidable in the front-rear direction.

[0032] Further, the arm main body 33 has a U-shaped bearing portion 36 with a downwardly open side surface shape at a predetermined position immediately behind the first arm front-side connecting portion 35, and this bearing portion 36 is rotatably engaged with the first support shaft 18a in the keyboard chassis 4. Further, the arm main body 33 is provided with a first arm rear-side connecting portion 37 for connecting to the second arm 32 at a predetermined position behind the bearing portion 36. Specifically, the first arm rear-side connecting portion 37 has a connecting shaft 37a that extends in the left-right direction and both ends of which protrude outward from the left and right side surfaces of the arm main body 33, respectively. And both ends of this connecting shaft 37a are engaged with the connecting recesses 45b, 45b of the second arm front-side connecting portion 45 described later of the second arm 32.

[0033] Two elongated plate-shaped weights 34, 34 are attached to the weight attachment portion 38 which is the rear portion of the arm main body 33 in a state of sandwiching the weight attachment portion 38 from both sides. Each weight 34 is made of a material (for example, a metal such as iron) having a specific gravity greater than that of the arm main body 33, and is formed into a predetermined shape by pressing a metal plate or the like.

[0034] The second arm 32 is formed of a resin molded product having a predetermined shape by injection molding a resin material similar to the arm body 33 of the first arm 31. This second arm 32 is shorter than the first arm 31 and extends a predetermined length in the front-rear direction. Further, the second arm 32 has a C-shaped bearing portion 41 with a side surface shape open forward near the center in the length direction, and this bearing portion 41 is rotatably engaged with the second support shaft 19a in the keyboard chassis 4.

[0035] In addition, a second arm rear side connecting portion 42 connected to the key rear side connecting portion 23 of the white key 2a is provided at the rear portion of the second arm 32. This second arm rear side connecting portion 42 is formed in a bifurcated shape and has two left and right connecting arm portions 43, 43 extending a predetermined length in parallel with each other along the length direction of the second arm 32. A connecting hole 43a penetrating in the left-right direction is formed at the rear end portion of each connecting arm portion 43. Then, both connecting arm portions 43, 43 sandwich the connecting main body portion 23a of the key rear side connecting portion 23 in the white key 2a from both the left and right sides between their rear end portions, and each connecting hole 43a is rotatably fitted to the corresponding engaging convex portion 23b of the key rear side connecting portion 23.

[0036] Furthermore, a second arm front side connecting portion 45 connected to the first arm rear side connecting portion 37 of the first arm 31 is provided at the front portion of the second arm 32. This second arm front side connecting portion 45 has a pair of left and right connecting pieces 45a, 45a spaced a predetermined interval from each other in the left-right direction, and a U-shaped connecting recess 45b having a long hole-shaped side surface shape and open forward is formed in each connecting piece 45a. Then, the left and right connecting pieces 45a, 45a of the second arm front side connecting portion 45 are rotatably and slidably engaged with both end portions of the connecting shaft 37a of the first arm 31 via their connecting recesses 45b, 45b, respectively.

[0037] FIG. 5(a) shows an enlarged view of the black key 2b and its key support mechanism 6b, and FIG. 5(b) shows an exploded view thereof. The black key 2b is formed of the same resin material as the white key 2a by injection molding or the like, is shorter than the white key 2a and extends a predetermined length in the front-rear direction, and is formed in a hollow shape that opens downward. At the front lower end of the black key 2b, a front key connecting portion 26 formed substantially the same as the front key connecting portion 22 of the white key 2a is provided. This front key connecting portion 26 has a connecting recess 26a formed in a U-shape with a long hole-shaped side surface and opening forward. Further, the front key connecting portion 26 has an extended portion 26b that extends a predetermined length forward from the front surface of the main body of the black key 2b at the lower front end of the connecting recess 26a, and this extended portion 26b functions as an upper limit position regulating portion of the black key 2b. In the following description, for the black key 2b and the key support mechanism 6b, the same components as those of the white key 2a and the key support mechanism 6a described above are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0038] The key support mechanism 6b that supports the black key 2b is configured substantially the same as the key support mechanism 6a for the white key described above. Specifically, the arm main body 33 of the first arm 31 and the second arm 32 of the key support mechanism 6b are configured to have exactly the same shape and size as the arm main body 33 and the second arm 32 of the key support mechanism 6a for the white key. Note that the shapes of the rear portions of the two left and right weights 34, 34 of the key support mechanism 6b for the black key are different from those of the weight 34 of the key support mechanism 6a for the white key.

[0039] Next, the operations of the key 2 and the key support mechanism 6 in the keyboard device 1 configured as described above will be described. FIG. 6 shows the operation of the white key 2a and its key support mechanism 6a, and FIG. 7 shows the operation of the black key 2b and its key support mechanism 6b.

[0040] In the key-off state shown in Fig. 6(a), when the front end of the white key 2a is pushed down by a finger of the player, the front-side connecting portion 22 of the white key 2a moves downward, whereby the first arm 31 rotates counterclockwise about the first support shaft 18a. Further, with the rotation of the first arm 31, the front-side connecting portion 45 of the second arm that engages with the connecting shaft 37a of the first arm 31 via the connecting recess 45b moves upward. As a result, the second arm 32 rotates clockwise about the second support shaft 19a. Then, with the rotation of the second arm 32, the rear-side connecting portion 23 connected via the rear-side connecting portion 42 of the second arm at the rear end thereof is pulled down, and the rear end of the white key 2a moves downward.

[0041] Incidentally, when the first arm 31 rotates as described above, as the box portion 35a of the front-side connecting portion 35 of the first arm 31 moves downward, the switch body 3b of the key switch 3 corresponding to the key 2 that has been keyed is pressed from above by the bottom wall of the box portion 35a. As a result, in the electronic piano, the keying information of the key 2 that has been keyed is detected, and based on the detected keying information, a sound is generated from a speaker (not shown).

[0042] As described above, when the white key 2a is pushed down, with the counterclockwise rotation of the first arm 31, the weight 34 of the first arm 31 inclines rearward and upward as shown in Fig. 6(b), and the rear end abuts against the first arm upper limit stopper 10a from below. As a result, further rotation of the first arm 31 is blocked. When the front end of the white key 2a is pushed down to the lowest position, the front end of the white key 2a abuts against the key lower limit stopper 16b, and further depression of the white key 2a is blocked.

[0043] The white key 2a pressed as described above operates to pivot about a virtual fulcrum P located behind its rear end. The position of this virtual fulcrum P is set such that, for example, the distance from the front end of the white key 2a is approximately twice the length of the white key 2a itself. As a result, when the front end portion of the white key 2a is pushed down to the lowest position, compared to the key-off state shown in Fig. 6(a), the front end portion of the white key 2a is positioned downward by a predetermined key stroke (e.g., 10 mm), and the rear end portion is positioned downward by a distance approximately half of the key stroke (e.g., 5 mm).

[0044] On the other hand, when the finger is released from the depressed white key 2a, due to the weight of the hammer 34, the first arm 31 of the key support mechanism 6a pivots in the reverse direction as described above, and accordingly, the second arm 32 also pivots in the reverse direction. Along with this, the white key 2a pivots upward about the virtual fulcrum P. Then, a predetermined portion behind the first pivot shaft 18a in the first arm 31 abuts against the first arm lower limit stopper 10b from above, and both upper limit position regulating portions 21, 21 of the white key 2a abut against the key upper limit stopper 16a from below, preventing further pivoting of the white key 2a and returning it to the original key-off state.

[0045] Also, the operation when the black key 2b is pressed is performed in the same manner as the above-described white key 2a and key support mechanism 6a. That is, in the key-off state shown in Fig. 7(a), when the front end portion of the black key 2b is pushed down, the first arm 31 pivots counterclockwise about the first pivot shaft 18a, and the second arm 32 pivots clockwise about the second pivot shaft 19a. As a result, the black key 2b operates to pivot about a virtual fulcrum Q at the rear. Note that the position of this virtual fulcrum Q is set in the same manner as the virtual fulcrum P of the white key 2a described above, for example, such that the distance from the front end of the black key 2b is approximately twice the length of the black key 2 itself. Therefore, when the front end portion of the black key 2b is pushed down to the lowest position, compared to the key-off state shown in Fig. 7(a), the front end portion of the black key 2b is positioned downward by a predetermined key stroke, and the rear end portion is positioned downward by a distance approximately half of the key stroke.

[0046] On the other hand, when the finger is released from the depressed black key 2b, the first arm 31 and the second arm 32 of the key support mechanism 6b rotate in the opposite direction to the above, and accordingly, the black key 2b rotates upward about the virtual fulcrum Q. Then, the extended portion 26b of the key front side connecting portion 26 of the black key 2b abuts against the key upper limit stopper 17 from below, the further rotation of the black key 2b is blocked, and it returns to the original key-off state.

[0047] Next, with reference to FIGS. 8 to 11, the main part of the present invention will be described. FIG. 8 shows an enlarged view of the bearing portion 36 of the arm main body 33 of the first arm 31 and the first support shaft 18a that supports it. Note that FIG. 8 is schematically shown, for example, the guide groove 36b is drawn slightly longer than the actual one for easier understanding of the configuration.

[0048] As described above, the first support shaft 18a is integrally provided in the chassis intermediate portion 12 of the keyboard chassis 4 (not shown in FIG. 8), extends horizontally, and has a circular cross section and a predetermined diameter (diameter) D. The bearing portion 36 has a circular shaft hole 36a formed near the lower surface of the arm main body 33, and a guide groove 36b that opens on the lower surface of the arm main body 33, extends obliquely upward therefrom, and is continuous with the shaft hole 36a.

[0049] The groove width W of the guide groove 36b is slightly smaller than the diameter D of the first support shaft 18a, and the diameter of the shaft hole 36a is set to be approximately the same as the diameter D of the first support shaft 18a so as to be rotatably fitted to the first support shaft 18a. Further, the inclination angle A of the guide groove 36b with respect to the horizontal in the key-off state is preferably in the range of 45 ± 15 degrees for reasons to be described later, and is set to about 45 degrees in the example of FIG. 8.

[0050] From the above configuration, the first arm 31 is attached to the first support shaft 18a as follows. First, after positioning the first arm 31 as shown in Fig. 8(a), it is moved obliquely downward (in the direction of arrow X) toward the first support shaft 18a, and the tip of the guide groove 36b is pressed against and engaged with the first support shaft 18a. Then, when the first arm 31 is further pressed in the same direction, the first arm 31 moves obliquely downward while being guided by the guide groove 36b in a state where the guide groove 36b with a narrow groove width is elastically expanded by the first support shaft 18a. When the guide groove 36b has passed over the first support shaft 18a, the guide groove 36b elastically returns, and at the same time, the shaft hole 36a fits (snaps) onto the first support shaft 18a. As a result, as shown in Fig. (b) of the same figure, the first arm 31 is attached to the first support shaft 18a via the shaft hole 36a and is rotatably supported.

[0051] As described above, the first arm 31 is snap-fitted to the first support shaft 18a via the bearing portion 36. Also, the guide groove 36b extends obliquely between the lower surface of the first arm 31 and the shaft hole 36a. Therefore, when an impact in the front-rear direction or the up-down direction acts on the keyboard device 1 during transportation of the product, the direction of the inertial force due to this is significantly different from the direction of the guide groove 36b, so that the inertial force is dispersed. As a result, it is possible to effectively suppress the detachment of the first arm 31 from the first support shaft 18a when an impact acts.

[0052] For example, when the electronic piano including the keyboard device 1 of the embodiment is transported as a product, usually, as shown in Fig. 9, it is housed in a packing box P made of cardboard or the like with the four corners of the electronic piano covered with a cushioning material C such as styrofoam. Therefore, the impact on the keyboard device 1 during transportation often acts in the front-rear direction (H) or the up-down direction (V).

[0053] When the impact on the keyboard device is in the front - rear direction, in the keyboard device of Patent Document 1 described above, the hammer is fitted onto the support shaft from the front, and since the direction of the inertial force due to the impact and the fitting direction of the hammer are substantially the same, there is a risk that the hammer will become detached from the support shaft. Also, when the impact on the keyboard device is in the vertical direction, in the keyboard device of Patent Document 2, the hammer is fitted onto the support shaft from above, and since the direction of the inertial force due to the impact and the fitting direction of the hammer are substantially the same, there is also a risk that the hammer will become detached from the support shaft.

[0054] On the other hand, in the keyboard device 1 of the present embodiment, as described above, when an impact in the front - rear direction or the vertical direction acts, the direction of the inertial force thereby is significantly different from the direction of the guide groove 36b. As a result of the dispersion of the inertial force, detachment of the first arm 31 from the first support shaft 18a can be effectively suppressed.

[0055] As shown in FIG. 9, when an impact on the keyboard device 1 acts in an oblique direction (I), the direction of the inertial force due to the impact may coincide with the direction of the guide groove 36b. However, in that case, the packaging box P is crushed to absorb part of the impact, and the first arm upper - limit stopper 10a against which the rotated first arm 31 abuts supports part of the impact, so the first arm 31 does not become detached.

[0056] Next, with reference to FIGS. 10 and 11, the uneven portions for removing the first arm 31 will be described. As shown in FIG. 10(a), these uneven portions 51 are formed on the arm main body 33 (hammer - mounting portion 38) of the first arm 31. More specifically, as shown in FIG. 10(b), the uneven portion 51 is integrally provided at the rear - end portion of the upper surface of the arm main body 33 and is constituted by a protrusion 51a that protrudes upward over the entire width thereof.

[0057] According to this configuration, by using the protrusion 51a, the first arm 31 is removed from the first support shaft 18a as follows. First, as shown in FIG. 11(a), after removing the key 2 from the assembled keyboard device 1, a rod-shaped tool R such as a driver is inserted from above, and its tip is abutted (engaged) against the front surface of the protrusion 51a. Then, the middle part of the tool R is pressed against an appropriate part S of the keyboard chassis 4 (the rear part 13 of the chassis) existing on the front side in the vicinity thereof, and the tool R is rotated in the direction of arrow Y in FIG. (b) with this part S as a fulcrum. As a result, as shown by arrow Z, the first arm 31 is driven obliquely upward and rearward along the guide groove 36b and is removed from the first support shaft 18a.

[0058] As described above, the first arm 31 is removed by rotating the rod-shaped tool R abutted against the protrusion 51a formed on the upper surface of the first arm 31 on the principle of a lever with the part S of the keyboard chassis 4 as a fulcrum. Thereby, the first arm 31, which is snap-fitted and difficult to remove, can be easily removed from the first support shaft 18a without using a special tool.

[0059] Note that the present invention is not limited to the above-described embodiment and can be implemented in various modes. For example, in the embodiment, the inclination angle A of the guide groove 36b of the first arm 31 with respect to the horizontal in the key-off state is set to about 45 degrees, but it may be in the range of 45 ± 15 degrees. This is because when the inclination angle A is greater than 60 degrees, the guide groove 36b becomes closer to vertical, so that the dispersion of the inertial force when an impact in the vertical direction acts becomes insufficient. Also, when the inclination angle A is less than 30 degrees, the guide groove 36b becomes closer to horizontal, so that the dispersion of the inertial force when an impact in the front-rear direction acts becomes insufficient. Therefore, if the inclination angle A is in the range of 45 ± 15 degrees, the detachment of the first arm 31 can be effectively suppressed by sufficiently dispersing the inertial force due to the impact, and the same effect can be obtained.

[0060] Also, in the embodiment, as the concavo-convex portion 51 for removing the first arm 31, FIG. 1 0(b) shows the protrusion 51a provided, but any configuration can be adopted as long as it is possible to engage the tool R and turn the first arm 31. Figure 1 0 (c) and (d) each show other examples of such uneven portions 51. In the example of (c), the uneven portion 51 is composed of a recess 51b formed over the entire width of the upper surface of the arm body 33, and in the example of (d), it is composed of a pair of notches 51c formed spaced apart in the width direction of the upper surface of the arm body 33. In these configurations, similar to the case of the protrusion 51a described above, by engaging and turning an appropriate tool R with the recess 51b or the notch 51c, the first arm 31 can be easily removed from the first support shaft 18a.

[0061] Furthermore, the detailed configurations shown in the embodiments, such as the configuration and dimensional relationships of the bearing portion 36 of the first arm 31 shown in FIG. 8, are merely examples, and can be appropriately changed within the scope of the gist of the present invention.

Explanation of Reference Numerals

[0062] 1 Keyboard device 2 Key 2a White key 2b Black key 4 Keyboard chassis (chassis) 31 First arm (hammer) 33 Arm body of the first arm (hammer) 36 Bearing portion 36a Shaft hole of the bearing portion (shaft hole) 36b Guide groove of the bearing portion (guide groove) 51 Uneven portion 51a Protrusion 51b Recess 51c Notch D Diameter of the first support shaft (diameter of the support shaft) W Groove width of the guide groove A Inclination angle of the guide groove

Claims

1. A chassis, A rotatable key, A hammer that is rotatably supported on a support shaft of the chassis and rotates in conjunction with the key when the key is pressed, The hammer has a shaft hole that can be fitted to the support shaft, and a guide groove that extends obliquely upward from the lower surface of the hammer so as to be continuous with the shaft hole and has a groove width smaller than the diameter of the support shaft. When the hammer is attached, the shaft hole is guided by the support shaft. The guide groove extends obliquely at an angle of 45 ± 15 degrees with respect to the horizontal in a key-off state of the key. A keyboard device for a keyboard instrument, characterized by this.

2. The keyboard device for a keyboard instrument according to claim 1, characterized in that the hammer is formed with uneven portions for engaging a tool for moving the hammer obliquely upward from the support shaft and removing it.

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