Keyboard device key

Abstract

To provide a key of a keyboard device, which can rigidly hold a weight part stored inside a key body, and can suppress manufacture cost by simplifying a mold for molding.SOLUTION: A key of a keyboard device includes: a resin key body 51 which has at least an upper face part and a pair of side face parts, is formed in a hollow shape in which a lower part is opened, and extends in a cross direction by a prescribed length; and a weight part 54 which is formed of an elastically deformable material and is stored in a prescribed position inside the hollow shape of the key body 51. The key body 51 includes one or a plurality of groove parts 53 extending along the cross direction on each inner face of a pair of side face parts. The weight part 54 includes one or a plurality of engaged protrusions 55 which are formed in positions facing the one or the plurality of groove parts 53 in the prescribed positions, and hold the weight part 54 inside the key body 51 by engaging with the one or the plurality of groove parts 53.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a key of a keyboard device that is applied to a keyboard instrument such as an electronic piano, and more particularly to a key of a keyboard device in which a weight part is attached inside the key. [Background technology]

[0002] Conventionally, there are known keys for keyboard devices that have weights attached to the hollow interior of the key to adjust the key's touch. For example, Patent Document 1 discloses a key for a keyboard instrument in which the key body has a hole that opens downward, and a protruding anti-fall-off part and anti-slip part are provided inside this hole, and by pressing an elastically deformable weight into this, the weight is prevented from falling off and vertical rattle is suppressed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-44989 Summary of the Invention [Problem to be solved by the invention]

[0004] The key of the keyboard instrument in Patent Document 1 has multiple protruding anti-fall and anti-shift parts to hold the weight inside the hole in the key body, which results in a problem that the structure of the mold used for molding is complicated and costs are high.

[0005] In addition, there are known keys for keyboard devices in which wooden pieces are attached to the sides of a resin key body to give the key a wood-like appearance at low cost. Typically, in such keys, the top surface of the key body is made to protrude laterally beyond the sides, thereby covering the top surface of the wooden board so that the top surface of the wooden piece is not exposed to the outside. However, when a key body is shaped in this way, uneven cooling speeds occur in the top surface during molding, which causes uneven shrinkage of the resin material and makes the top surface more susceptible to molding defects known as sink marks.

[0006] The present invention has been made to solve the above problems, and aims to provide a key for a keyboard device that can firmly hold the weight part housed inside the key body and can reduce manufacturing costs by simplifying the mold used for molding. Another aim is to provide a key for a keyboard device that can prevent sink marks from occurring on the top surface during molding of the key body. [Means for solving the problem]

[0007] In order to achieve the above object, the key of the keyboard device according to claim 1 comprises a resin key body having at least an upper surface and a pair of side surfaces, formed in a hollow shape with an open bottom, and extending a predetermined length in the front-to-rear direction, and a weight portion formed of an elastically deformable material and housed at a predetermined position inside the hollow shape of the key body, the key body having one or more grooves extending along the front-to-rear direction on the inner surface of each of the pair of side surfaces, and the weight portion having one or more engaging protrusions formed at a position facing the one or more grooves at the predetermined position and engaging with the one or more grooves to hold the weight portion inside the key body. The one or more grooves are formed on the top of the pair of side surfaces, and the thickness of the top of the pair of side surfaces of the key body is smaller than the thickness of the top surface of the key body. It is characterized by:

[0008] According to this configuration, one or more grooves extending in the front-to-rear direction are formed on the inner surface of the side portion of the hollow key body, which is open at the bottom, and the weight portion has one or more engaging protrusions formed at positions opposite the one or more grooves at predetermined positions inside the key body.Therefore, when the weight portion is stored at a predetermined position inside the key body, the engaging protrusions engage with the grooves, thereby firmly holding the weight portion inside the key body.

[0009] Furthermore, since the key body can hold the weight portion using only one or more grooves provided on the inner surface of the side portion, there is no need to provide multiple protruding anti-fall portions, etc., which simplifies the mold for molding and reduces manufacturing costs.

[0011] AlsoOne or more grooves are formed in the uppermost parts of the inner surfaces of the pair of side sections of the key body, and the thickness of the side sections at the uppermost parts where the grooves are formed is thinner than the thickness of the top section of the key body. As a result, even if, for example, a wooden board is attached to the side sections of the key body and the left and right ends of the top section protrude laterally to cover the upper end surface of the wooden board, the difference in thickness between the connection part of the top section and the side sections and the rest of the top section is very small, which makes it less likely that a difference in cooling rate will occur during molding, and therefore makes it possible to prevent sink marks from occurring in the top section.

[0012] Claim 2 The invention according to claim 1 to In the key of the described keyboard device, the vertical length dimension of the engaging protrusion of the weight part is formed to be smaller than the vertical length dimension of one or more groove parts.

[0013] With this configuration, the vertical length of the groove on the inner surface of the side of the key body is greater than the vertical length of the engaging protrusion on the weight, so when the weight is attached to the inside of the key body with adhesive, the adhesive accumulates in the gap created by the groove where the engaging protrusion engages, allowing the weight to be more firmly attached to the inside of the key body. This gap also functions as a space for excess adhesive to escape. [Brief explanation of the drawings]

[0014] [Figure 1] 1A and 1B are perspective views showing a part (for one octave) of a keyboard device of an electronic piano to which the present invention is applied, in which (a) shows the appearance of the keyboard device, and (b) shows a state in which keys other than the white and black keys on the left end are omitted. [Figure 2] 1(b) is a perspective view showing the keyboard device shown in FIG. 1(b) with the white keys and black keys, together with their respective key support mechanisms, removed from the keyboard chassis. FIG. [Figure 3] 1(b) is a cross-sectional view taken along line AA of the keyboard device shown in FIG. 1(b). [Figure 4]1A and 1B are perspective views showing a white key and a key support mechanism, in which FIG. 1A shows the white key and the key support mechanism connected together, and FIG. 1B shows the white key and the key support mechanism disassembled. [Figure 5] 1A and 1B are perspective views showing the black key and the key support mechanism, in which FIG. 1A shows the black key and the key support mechanism connected together, and FIG. 1B shows the black key and the key support mechanism disassembled. [Figure 6] 1A and 1B are diagrams for explaining the operation of a white key in a keyboard device, in which FIG. 1A shows a key-released state and FIG. 1B shows a key-depressed state. [Figure 7] 1A and 1B are diagrams for explaining the operation of black keys in a keyboard device, in which (a) shows the key-released state and (b) shows the key-depressed state. [Figure 8] FIG. 1(a) is a side view showing the key body of a white key, and FIG. 1(b) is a bottom view showing the key body. [Figure 9] 8(a) is a cross-sectional view taken along line BB in FIG. 8(a), and FIG. 8(b) is a cross-sectional view showing a white key according to a modified example. [Figure 10] 10(a) is a perspective view showing a weight portion, and FIG. 10(b) is a perspective view showing a weight portion according to a modified example. [Figure 11] 10A is a cross-sectional view showing the key body in a state in which the weight portion is housed, and FIG. 10B is a perspective view showing the key body in a state in which the weight portion according to a modified example is housed. DETAILED DESCRIPTION OF THE INVENTION

[0015] A preferred embodiment of the present invention will be described in detail below with reference to the drawings. Figure 1(a) shows only one octave of a keyboard device 1 of an electronic piano to which the present invention is applied. In the following explanation, the basic configuration and operation of the keyboard device 1 will be explained first, and then the main parts of the present invention will be explained.

[0016] Figure 1(b) shows the keyboard device 1 of Figure 1(a) with all keys 2 omitted except for the white key 2a and black key 2b on the left end, and Figure 2 shows the white key 2a and black key 2b removed from the keyboard chassis 4 together with the key support mechanism 6.

[0017] This keyboard device 1 includes a keyboard chassis 4, a plurality of keys 2 consisting of white keys 2a and black keys 2b arranged in a row in the left-right direction, a key support mechanism 6 rotatably attached to the keyboard chassis 4 for each key 2 and supporting the corresponding key 2 from below, and a key switch 3 for detecting key depression information for each key 2.

[0018] The keyboard chassis 4 includes a chassis main body 4a made of a resin molded product of a predetermined shape, obtained by injection molding a predetermined resin material (e.g., ABS resin). As shown in Figure 3, the chassis main body 4a has a front portion 11, a middle portion 12, and a rear portion 13, all of which are formed to extend in the left-right direction (the left-right direction in Figure 3(a)) as a whole, and are integrally formed with a plurality of ribs 14 spaced apart in the left-right direction and each extending in the front-to-rear direction. In the following description, the front portion 11, middle portion 12, and rear portion 13 of the chassis main body 4a of the keyboard chassis 4 will be referred to as the "chassis front portion 11," the "chassis middle portion 12," and the "chassis rear portion 13," respectively.

[0019] The chassis front section 11 primarily guides the white keys 2a when they are pressed and regulates the upper and lower limit positions of their front ends. A plurality of white key guides 11a are arranged side-by-side in the left-right direction on the chassis front section 11. Each white key guide 11a is inserted from below into the corresponding white key 2a to prevent the white key 2a from swaying sideways. The chassis front section 11 also has engagement holes 11b, 11b penetrating vertically on both the left and right sides of each white key guide 11a. Two upper limit position regulation sections 21, 21 (described later) of the white key 2a penetrate the engagement holes 11b, 11b, respectively. Furthermore, the chassis front section 11 is provided with a stopper mounting section 11c at its front end, which protrudes forward and extends laterally across the entire chassis body 4a. An upper limit key stopper 16a and a lower limit key stopper 16b for the white keys are attached to the lower and upper surfaces of the stopper mounting section 11c, respectively, so as to extend laterally. In addition, a stopper mounting portion 11d for the black keys is provided at a predetermined position behind the white key guide 11a on the front part 11 of the chassis, extending in the left-right direction across the entire chassis body 4a, and an upper key limit stopper 17 for the black keys is attached to this stopper mounting portion 11d so as to extend in the left-right direction.

[0020] The chassis intermediate section 12 primarily guides the black keys 2b when pressed and swingably supports the first and second arms 31 and 32 (described later) of the key support mechanisms 6a, 6b for the white and black keys. The chassis intermediate section 12 includes a flat section 12a extending laterally and a plurality of black key guides 12b arranged vertically on the flat section 12a and spaced apart appropriately in the left-right direction. Each black key guide 12b is inserted into each black key 2b from below to prevent the key from swaying laterally. The front of the chassis intermediate section 12 includes a first arm support section 18 that supports the first arm 31 of the key support mechanism 6. The first arm support section 18 includes a plurality of first support shafts 18a extending laterally between adjacent ribs 14. The first arms 31 are swingably supported by these first support shafts 18a. Furthermore, a second arm support section 19 that supports a second arm 32 of the key support mechanism 6 is provided at the rear of the chassis intermediate section 12. This second arm support section 19 has a plurality of second support shafts 19a that are provided between adjacent ribs 14, 14 and extend in the left-right direction. The plurality of second support shafts 19a are arranged on the same axis that extends in the left-right direction, at a position rearward and higher than the first support shaft 18a, and the second arm 32 is supported by these second support shafts 19a so that it can swing freely. Note that a first arm lower limit stopper 10b that extends in the left-right direction across the entire chassis main body 4a is provided at a predetermined position on a middle rail 8 (described later) that is provided below the chassis intermediate section 12.

[0021] The key switch 3 is attached to the bottom of the keyboard chassis 4, between the chassis front section 11 and the chassis middle section 12. The key switch 3 is composed of a horizontally elongated printed circuit board 3a extending in the left-right direction, and multiple switch bodies 3b made of rubber switches attached to the printed circuit board 3a for each key 2 and pressed by a first arm 31 when the key is pressed.

[0022] The chassis rear section 13 primarily guides the key 2 vertically at its rear end while preventing lateral movement, and regulates the upper limit position of the rear end of the first arm 31. As shown in FIGS. 2 and 3(a), the chassis rear section 13 has multiple partition walls 13a spaced at predetermined intervals in the left-right direction to separate adjacent keys 2. Also, as shown in FIG. 3(b), a first arm upper limit stopper 10a extending left-right across the entire chassis main body 4a is provided at a predetermined position on the upper part of the chassis rear section 13. This first arm upper limit stopper 10a and the first arm lower limit stopper 10b provided on the chassis intermediate section 12 regulate the upper limit position and the lower limit position, respectively, of the first arm 31, which functions as a hammer for applying a touch weight to the key 2, when the first arm 31 rotates upward and downward. Furthermore, a metal cover plate 15 is attached to the upper part of the chassis rear part 13, extending in the left-right direction across the entire chassis body 4a and arranged to cover the rear end of the key 2.

[0023] 2 and 3(a), the chassis main body 4a of the keyboard chassis 4 configured as described above is provided with a plurality of first openings 5a that open upward and forward, and a plurality of second openings 5b that also open upward. The first arm 31 of the key support mechanism 6 engages with the first support shaft 18a from the outside through each of the first openings 5a, and the second arm 32 engages with the second support shaft 19a from the outside through each of the second openings 5b.

[0024] In the keyboard chassis 4, multiple chassis bodies 4a are connected to one another in a line up in the left-right direction, and are placed on and screwed to metal front rails 7, middle rails 8, and rear rails 9 that extend left-right and are arranged at a predetermined distance from one another in the front-to-rear direction. The keyboard chassis 4 is then fixed to a shelf board (not shown) of the electronic piano via the front rails 7 and rear rails 9.

[0025] 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, while FIG. 4(b) shows them exploded. As shown in the figure, the white key 2a is formed by injection molding a specific resin material (e.g., AS resin) to extend a specific length in the front-to-rear direction and to have a hollow shape that opens downward. The front end of the white key 2a is provided with a pair of left and right upper limit position restrictors 21, 21 that extend downward from the left and right side walls and are formed so that their lower ends are bent forward. As described above, these upper limit position restrictors 21, 21 are engaged in a state in which they penetrate the left and right engagement holes 11b, 11b of the chassis front part 11, respectively.

[0026] Additionally, a front-key connecting portion 22 is provided at the front of the white key 2a, at a predetermined position rearward of the upper limit restriction portion 21, to connect to the first arm 31 of the key support mechanism 6a. This front-key connecting portion 22 has a U-shaped connecting recess 22a with an elongated side surface that opens forward. A key-side noise suppression member 20 is attached to this connecting recess 22a, covering its entire inner circumferential surface, to suppress noise generated when a connecting shaft 35b (described later) of the first arm 31 slides within the connecting recess 22a.

[0027] Furthermore, a key rear connector 23 is provided at the rear of the white key 2a, which is connected to the second arm 32 of the key support mechanism 6a. This key rear connector 23 hangs down from the center of the white key 2a in the left-right direction and has a plate-like connector body 23a with a predetermined thickness in the left-right direction, and a pair of left and right engaging protrusions 23b, 23b that protrude coaxially from the left and right sides of the connector body 23a. In addition, a tool insertion hole 24 is formed at the rear of the white key 2a, penetrating vertically. This tool insertion hole 24 is used to insert a predetermined tool from above when releasing the connection between the white key 2a and the second arm 32 of the key support mechanism 6a, for example during maintenance of the keyboard device 1.

[0028] On the other hand, the key support mechanism 6a includes a first arm 31 and a second arm 32 that are engaged with each other and connected to the front-key connecting portion 22 and the rear-key connecting portion 23 of the white key 2a, respectively.

[0029] As shown in FIG. 4(b), the first arm 31 is composed of an arm body 33 and two weights 34, 34 attached to the arm body 33. The arm body 33 is a resin molded product of a predetermined shape, typically obtained by injection molding a predetermined resin material (e.g., polyacetal). The arm body 33 extends a predetermined length in the front-to-rear direction, and its front end is provided with a first-arm front connector 35 that connects to the front-side connector 22 of the white key 2a. The first-arm front connector 35 has a box-shaped box portion 35a that opens upward and forward, and a connecting shaft 35b that extends left and right and connects the front upper ends of the left and right side walls of the box portion 35a. The connecting shaft 35b is connected to the connecting recess 22a of the front-side connector 22 of the white key 2a so as to be rotatable and slidable in the front-to-rear direction.

[0030] The arm main body 33 also has a U-shaped bearing 36 with a downwardly open side at a predetermined position immediately rearward of the first arm front connecting portion 35, and this bearing 36 rotatably engages with the first support shaft 18a of the keyboard chassis 4. Furthermore, the arm main body 33 has a first arm rear connecting portion 37 at a predetermined position rearward of the bearing 36, which connects to the second arm 32. Specifically, the first arm rear connecting portion 37 has a connecting shaft 37a that extends in the left-right direction and has both ends that protrude outward beyond the left and right side surfaces of the arm main body 33. Both ends of this connecting shaft 37a engage with connecting recesses 45b, 45b of a second arm front connecting portion 45 of the second arm 32, which will be described later.

[0031] Two elongated plate-like weights 34, 34 are attached to weight attachment portion 38 at the rear of arm main body 33, sandwiching weight attachment portion 38 from both sides. Each weight 34 is made of a material (e.g., a metal such as iron) with a higher specific gravity than arm main body 33, and is formed into a predetermined shape by pressing a metal plate, for example.

[0032] The second arm 32 is made of a resin molded product of a predetermined shape, which is injection molded from the same resin material as the arm body 33 of the first arm 31. The second arm 32 is shorter than the first arm 31 and extends a predetermined length in the front-to-rear direction. The second arm 32 also has a C-shaped bearing portion 41 near the center in the longitudinal direction, with the side surface opening forward, and this bearing portion 41 rotatably engages with the second support shaft 19a of the keyboard chassis 4.

[0033] Additionally, a second-arm rear connecting portion 42 that connects to the key rear connecting portion 23 of the white key 2a is provided at the rear of the second arm 32. This second-arm rear connecting portion 42 is bifurcated, with two left and right connecting arms 43, 43 that extend parallel to each other a predetermined length along the length of the second arm 32. A connecting hole 43a that penetrates in the left-right direction is formed at the rear end of each connecting arm 43. Between their rear ends, the connecting arms 43, 43 sandwich the connecting main body 23a of the key rear connecting portion 23 of the white key 2a, and each connecting hole 43a rotatably fits into the corresponding engaging protrusion 23b of the key rear connecting portion 23.

[0034] Furthermore, a second arm front connecting portion 45 is provided on the front portion of the second arm 32, which is connected to the first arm rear connecting portion 37 of the first arm 31. This second arm front connecting portion 45 has a pair of left and right connecting pieces 45a, 45a spaced a predetermined distance from each other in the left-right direction, and each connecting piece 45a is formed with a U-shaped connecting recess 45b whose side surface is elongated and open forward. The left and right connecting pieces 45a, 45a of the second arm front connecting portion 45 are rotatably and slidably engaged with both ends of the connecting shaft 37a of the first arm 31 via the connecting recesses 45b, 45b, respectively.

[0035] FIG. 5(a) shows an enlarged view of the black key 2b and its key support mechanism 6b, while FIG. 5(b) shows them in exploded view. The black key 2b is injection-molded from the same resin material as the white key 2a. It is shorter than the white key 2a, extends a predetermined length in the front-to-back direction, and is hollow and open downward. The front lower end of the black key 2b is provided with a front-side connecting portion 26, which is formed in a manner similar to the front-side connecting portion 22 of the white key 2a. This front-side connecting portion 26 has a connecting recess 26a that is elongated and U-shaped and opens forward. The front-side connecting portion 26 also has an extension 26b at the front end below the connecting recess 26a, which extends a predetermined length forward beyond the front surface of the black key 2b. This extension 26b functions as an upper limit position limiter for the black key 2b. In the following description, the same components of the black key 2b and key support mechanism 6b as those of the white key 2a and key support mechanism 6a described above will be denoted by the same reference numerals, and detailed description thereof will be omitted.

[0036] The key support mechanism 6b that supports the black keys 2b is configured in a manner similar to the key support mechanism 6a for white keys described above. Specifically, the arm body 33 of the first arm 31 and the second arm 32 of the key support mechanism 6b are configured to be identical in shape and size to the arm body 33 and second arm 32 of the key support mechanism 6a for white keys. However, the two weights 34, 34 on the left and right of the key support mechanism 6b for black keys have a different rear shape than the weight 34 of the key support mechanism 6a for white keys.

[0037] Next, we will explain the operation of the keys 2 and key support mechanism 6 in the keyboard device 1 configured as above. Figure 6 shows the operation of the white keys 2a and their key support mechanism 6a, and Figure 7 shows the operation of the black keys 2b and their key support mechanism 6b.

[0038] 6(a), when the player presses down on the front end of the white key 2a with his / her finger, the front-key connector 22 of the white key 2a moves downward, causing the first arm 31 to rotate counterclockwise around the first support shaft 18a. Accompanying the rotation of the first arm 31, the front-key connector 45 of the second arm, which engages with the connecting shaft 37a of the first arm 31 via the connecting recess 45b, moves upward. This causes the second arm 32 to rotate clockwise around the second support shaft 19a. Accompanying the rotation of the second arm 32, the rear-key connector 23 connected via the rear-key connector 42 at its rear end is pulled down, causing the rear end of the white key 2a to move downward.

[0039] During the above-described rotation of the first arm 31, as the box portion 35a of the first arm front connecting portion 35 moves downward, the bottom wall of the box portion 35a presses from above against the switch body 3b of the key switch 3 corresponding to the pressed key 2. As a result, the electronic piano detects key press information of the pressed key 2, and a sound is generated from a speaker (not shown) based on the detected key press information.

[0040] As described above, when the white key 2a is pressed down, as the first arm 31 rotates counterclockwise, the weight 34 of the first arm 31 tilts upward at the rear as shown in Figure 6(b), and its rear end abuts against the first arm upper limit stopper 10a from below, thereby preventing further rotation of the first arm 31. Then, when the front end of the white key 2a is pressed down to the lowest position, the front end of the white key 2a abuts against the key lower limit stopper 16b, preventing further depression of the white key 2a.

[0041] When the white key 2a is pressed as described above, it rotates around an imaginary fulcrum P located behind its rear end. The position of this imaginary fulcrum P is set, for example, so that 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 of the white key 2a is pressed down to the lowest position, the front end of the white key 2a is positioned a predetermined keystroke (e.g., 10 mm) lower, and the rear end of the white key 2a is positioned approximately half the keystroke (e.g., 5 mm) lower, compared to when the key is released as shown in Figure 6(a).

[0042] On the other hand, when the pressed white key 2a is released, the weight of the weight 34 causes the first arm 31 of the key support mechanism 6a to rotate in the opposite direction to that described above, and accordingly, the second arm 32 also rotates in the opposite direction to that described above. As a result, the white key 2a rotates upward around the imaginary fulcrum P. Then, a predetermined portion of the first arm 31 behind the first support shaft 18a abuts against the first arm lower limit stopper 10b from above, and both upper limit position restriction portions 21, 21 of the white key 2a abut against the key upper limit stopper 16a from below, preventing further rotation of the white key 2a and returning it to its original key-released state.

[0043] Furthermore, the operation of the black key 2b when pressed is similar to that of the white key 2a and key support mechanism 6a described above. Specifically, when the front end of the black key 2b is depressed in the key-released state shown in FIG. 7(a), the first arm 31 rotates counterclockwise around the first support shaft 18a, and the second arm 32 rotates clockwise around the second support shaft 19a, causing the black key 2b to rotate around a virtual fulcrum Q at the rear. Similar to the virtual fulcrum P of the white key 2a described above, the position of this virtual fulcrum Q is set so that its 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 of the black key 2b is depressed to its lowest position, the front end of the black key 2b is positioned a predetermined keystroke lower than in the key-released state shown in FIG. 7(a), and the rear end of the black key 2b is positioned approximately half the keystroke lower.

[0044] On the other hand, when the pressed black key 2b is released, the first arm 31 and the second arm 32 of the key support mechanism 6b rotate in the opposite direction, causing the black key 2b to rotate upward around the virtual fulcrum Q. Then, the extension 26b of the front-key connecting portion 26 of the black key 2b abuts against the upper key stopper 17 from below, preventing further rotation of the black key 2b and returning it to its original released state.

[0045] Next, the main part of the present invention will be described with reference to Figures 8 to 11. The main part of the present invention is the mounting structure of the weight part inside the key body. In this embodiment, an example in which the mounting structure of the weight part is applied to a white key will be described, but a similar mounting structure may also be applied to a black key.

[0046] FIG. 8(a) shows a side view of the key body of a white key, and FIG. 8(b) shows a bottom view of the same key body. As described above, the key body 51 of the white key 2a is formed by injection molding a predetermined resin material (e.g., AS resin). In this embodiment, the white key 2a is, for example, an A key (the key for the note A). The key body 51 of the white key 2a consists of a wide portion 51a adjacent to another white key 2a and a narrow portion 51b adjacent to the black key 2b. Wooden boards 52 are attached to the left and right sides of each of the wide portion 51a and the narrow portion 51b to give the key a woody feel. The wooden boards 52 can be made of wood, wood-grain veneer, plywood, medium-density fiberboard (MDF), or other wood materials. In this embodiment, the wooden boards 52 are made of soft wood with a specific gravity of 0.5 or less. Examples of such wood include spruce and certain tropical woods.

[0047] As shown in FIG. 8(b), the key body 51 is formed hollow with an open bottom, and an internal space S is provided inside the wide portion 51a for accommodating the weight portions 54, 54a, and 54b, which will be described later.

[0048] 9(a) shows a cross section taken along line BB in FIG. 8(a). As shown in the figure, grooves 53 are formed on the inner surfaces of a pair of left and right side portions of the key body 51. The grooves 53 are formed at the top of the inner surfaces of the wide portion 51a and the narrow portion 51b of the key body 51, extending longitudinally in the front-to-rear direction. Furthermore, the left and right ends of the upper surfaces of the wide portion 51a and the narrow portion 51b of the key body 51 protrude laterally beyond the pair of side portions and cover the upper end surfaces of the wooden boards 52 attached to the side portions, making the appearance of the key when viewed from the side resemble that of a wooden key.

[0049] FIG. 10(a) shows the weight portion 54 of this embodiment. The weight portion 54 is accommodated inside the key body 51 of each key in the keyboard device to adjust the weight balance of each key and thereby adjust the touch of the key. The weight portion 54 of this embodiment is formed in a substantially rectangular parallelepiped shape from an elastically deformable material. The weight portion 54 can be made of an elastic material such as synthetic rubber or a thermoplastic elastomer, and in this embodiment, the weight portion 54 is made of, for example, chloroprene rubber. An engaging protrusion 55 is formed on the upper end of each of a pair of opposing side surfaces of the weight portion 54. When the weight portion 54 is accommodated in the internal space S of the key body 51, the engaging protrusion 55 engages with the groove 53 to hold the weight portion 54 within the internal space S.

[0050] The length between the pair of side surfaces of weight portion 54 is configured to be approximately the same as the length between the respective inner surfaces of the pair of side surfaces of key body 51. In addition, the length between each of engaging protrusions 55 formed on the pair of side surfaces of weight portion 54 is larger than the length between the inner surfaces of the pair of side surfaces of key body 51, and is configured to be approximately the same as the length between the inner surfaces at the position where groove portion 53 is formed.

[0051] 11(a) shows the key body 51 with the weight 54 accommodated at a predetermined position within the internal space S. The weight 54 is attached to a predetermined position within the key body 51, for example, by pushing the weight 54 into the internal space S from the open bottom of the key body 51. When the weight 54 is pushed into the key body 51 from below, the engaging protrusions 55 first come into contact with a pair of side surfaces of the key body 51. However, the weight 54 elastically deforms, bending the engaging protrusions 55 in the direction opposite to the pushing direction of the weight 54, thereby fitting the weight 54 into the internal space S.

[0052] Thereafter, weight 54 is pushed further upward, and when weight 54 reaches a predetermined position within internal space S, engaging protrusion 55, which has been elastically deformed, returns to its original shape within groove 53, and engaging protrusion 55 fits into and engages with groove 53. When weight 54 is thus accommodated at a predetermined position within internal space S, engaging protrusion 55 and groove 53 engage with each other, thereby firmly holding weight 54 within key body 51.

[0053] It should be noted that weight portion 54 may be more firmly attached to the inside of key body 51 by applying an adhesive to the upper surface of weight portion 54 or by attaching double-sided tape thereto.

[0054] As described above, the key body 51 of this embodiment can firmly hold the weight 54 only by the groove 53 provided on the inner surface of the side portion, so there is no need to form a separate protrusion to prevent the weight from falling off. This simplifies the mold used to mold the key body 51, thereby reducing manufacturing costs.

[0055] In addition, in the key body 51, which is a molded product made of a resin material, attention must be paid to the occurrence of sink marks in thicker portions, such as the junction between the top and side sections. Since the top section of the key body 51 is the striking surface during playing, it is particularly important to effectively prevent sink marks from occurring in the top section to prevent deterioration of aesthetics and touch during playing. In the key body 51 of this embodiment, grooves 53 are formed at the top of the inner surfaces of the pair of side sections, making the thickness dimension L1 of the top section of the side sections smaller than the thickness dimension L2 of the top section. That is, in the key body 51 of this embodiment, the grooves 53 formed at the top of the side sections act as a recess, reducing the difference in thickness between the junction between the top section and the side sections and the rest of the top section. This reduces the difference in cooling rate between the junction between the top section and the side sections and the rest of the top section during molding, effectively preventing sink marks from occurring in the top section.

[0056] 10(b) shows a weight 54a according to a modified example. The difference between the weight 54 described above and the weight 54a according to the modified example is that, in the weight 54, one engaging protrusion 55 is formed on each of a pair of opposing side surfaces of the weight 54 so as to extend along the entire upper end of each of the pair of opposing side surfaces, whereas in the weight 54a, multiple engaging protrusions 55a are formed on the upper end of each of the pair of opposing side surfaces of the weight 54a. In this way, the multiple engaging protrusions 55a formed on the weight 54a are shorter than the engaging protrusions 55. This allows the engaging protrusions 55a to be deformed with less force when the weight 54a is pressed into the internal space S of the key body 51, making it easier to attach the weight 54a. Furthermore, when engaging protrusion 55a engages with groove 53, a space is created in groove 53 facing the discontinuous portion of engaging protrusion 55a, and so if adhesive is applied to the top surface of weight 54a, for example, the adhesive will accumulate in this space, thereby more firmly adhering weight 54a to key body 51. This space also functions as a space for excess adhesive to escape.

[0057] FIG. 11(b) shows a weight 54b according to another modification placed in a predetermined position within the internal space S of the key body 51. This weight 54b is characterized in that the engaging protrusion 55b is smaller than the groove 53. For example, the vertical length of the engaging protrusion 55b is smaller than the vertical length of the groove 53. As a result, when the engaging protrusion 55b engages with the groove 53, a gap G is formed between the engaging protrusion 55b and the groove 53. Therefore, if adhesive is applied to the top surface of the weight 54b, for example, the adhesive will accumulate in this gap G, thereby more firmly adhering the weight 54b to the key body 51. This gap G also functions as a space for excess adhesive to escape.

[0058] As described above, according to this embodiment, when weight 54 is placed at a predetermined position within internal space S of key body 51, engaging protrusion 55 of weight 54 fits into groove 53 provided on the inner surface of the side surface of key body 51, thereby firmly holding weight 54 inside key body 51. Furthermore, since there is no need to provide key body 51 with a separate protrusion to prevent the weight from falling out, the mold for molding key body 51 can be simplified, and manufacturing costs can be reduced.

[0059] Furthermore, by forming the groove 53 at the top of the side surface of the key body 51, the thickness L1 of the top of the side surface is smaller than the thickness L2 of the top surface. This reduces the difference in cooling rate between the connection between the top surface and the side surface and the rest of the top surface during molding of the key body 51, effectively preventing sink marks from occurring on the top surface.

[0060] The present invention is not limited to the above-described embodiment and can be embodied in various forms. For example, in the embodiment, the key body 51 having the wooden board 52 attached to its side surface was described. However, as shown in FIG. 9(b), the weight attachment structure of the present invention can also be employed in a key body 51a without a wooden board attached to its side surface. In the key body 51a shown in FIG. 9(b), the left and right ends of the top surface do not protrude laterally beyond the side surface. Therefore, during molding, the difference in cooling rate between the connection between the top surface and the side surface and the other parts of the top view is small, greatly reducing the possibility of sink marks occurring on the top surface. In this case, the groove 53a does not need to be formed at the topmost part of the inner surface of the side surface of the key body 51a, but can be formed at any position on the side surface. Furthermore, since the groove 53a does not need to extend all the way along the front-rear direction of the inner surface of the side surface of the key body 51a to prevent sink marks, the groove 53a may be formed only at a position necessary for attaching the weight 54, for example, the groove 53a may be formed only within the interior space S. In addition, the detailed configuration can be changed as appropriate within the scope of the spirit of the present invention. [Explanation of symbols]

[0061] 1 Keyboard device 2 keys 2a white key 2b black key 51 Key body 51a wide part 51b Narrow part 52 Wood board 53 Groove 54 Weight 54a Variations of the weight part 54b Variations of the weight part 55 Engagement protrusion 55a Modified engaging protrusion 55b Modified engaging protrusion S Internal space of the key body G Gap between the groove and the engaging protrusion

Claims

1. a resin key body having at least an upper surface and a pair of side surfaces, formed in a hollow shape with an open bottom, and extending a predetermined length in the front-to-rear direction; a weight portion formed of an elastically deformable material and accommodated at a predetermined position within the hollow interior of the key body; The key body has one or more grooves extending along a front-rear direction on the inner surface of each of the pair of side surfaces, the weight portion has one or more engaging protrusions formed at positions facing the one or more grooves at the predetermined position and engaging with the one or more grooves to hold the weight portion inside the key body, the one or more grooves are formed in the uppermost portions of the pair of side surfaces, A key for a keyboard device, characterized in that the thickness dimension of the top of the pair of side portions of the key body is formed to be smaller than the thickness dimension of the top surface of the key body.

2. 2. The key of a keyboard device according to claim 1, wherein the vertical length of the engaging protrusion of the weight portion is formed to be smaller than the vertical length of the one or more grooves.

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