Keyboard device for keyboard instruments

Abstract

To provide a keyboard device of a keyboard musical instrument that simplifies connection structure of keys and a key support mechanism, can easily assemble them to a keyboard chassis, and as a result allow the entire device to be assembled efficiently.SOLUTION: A keyboard device includes multiple key support mechanisms 6 that are engaged with a keyboard chassis 4, are provided so as to support the corresponding keys 2 from below each, and operate the pressed keys 2 so as to be rotated with a virtual support positioned in the rear of a rear end of the keys 2 as a center when the keys are pressed. The key support mechanisms 6 are configured so as to be extended by a predetermined length in a fore-and-aft direction each and be freely rockable, and have first arms 31 and second arms 32 rotatably and slidably connected to each other. In the keyboard chassis 4, an opening for assembling arms that is opened at least upward or forward and assembles the first arms 31 and the second arms 32 to the keyboard chassis 4 is provided.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a keyboard device that is applied to keyboard instruments such as electronic pianos, and that operates so that a depressed key rotates around a virtual fulcrum that is located behind the rear end of the key. [Background technology]

[0002] Conventionally, as a keyboard device of this kind, for example, the one described in Patent Document 1 already filed by the applicant is known. This keyboard device includes a horizontal plate-like base, a number of keys that are provided above the base and extend a predetermined length in the front-rear direction, and a number of link mechanisms that are provided on the base and support each key from below. The link mechanism includes a front connecting link bar that extends a predetermined length in the front-rear direction and has a front end that is rotatably connected to the front part of the key, and a rear connecting link bar that extends a predetermined length in the front-rear direction and has a rear end that is rotatably and slidably connected to the rear end of the key. These front connecting link bar and rear connecting link bar are rotatably supported near the center of their respective length directions, and are rotatably and slidably connected to each other. The front connecting link bar and rear connecting link bar are both made of elongated metal plates and formed into a predetermined shape.

[0003] In the keyboard device configured as above, when the front end of the key is pressed down, the front connecting link bar and the rear connecting link bar each rotate in a predetermined direction, and when the front end of the key is pressed down to the lowest position, the front end is positioned a predetermined distance (e.g., 10 mm) lower than when the key is released, and the rear end moves downward a distance that is about half the predetermined distance (e.g., 5 mm). In other words, in this keyboard device, when a key is pressed, the key rotates around a virtual fulcrum as if the virtual fulcrum exists at a predetermined position behind the rear end of the key. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-52391 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned keyboard device, the front and rear connecting link bars of the link mechanism supporting the keys are both made of metal plates. Therefore, when these connecting link bars are connected to each other or to the keys, it is necessary to insert the connecting pins and fix them in a state where the pin holes of the connecting parts overlap each other in the left-right direction. When connecting the front and rear connecting link bars and the keys to each other in this way, the work is very complicated, and it takes time and effort to assemble the keyboard device. Therefore, there is room for improvement in the above-mentioned keyboard device.

[0006] The present invention has been made to solve the above-mentioned problems, and has as its object to provide a keyboard device for a keyboard instrument which simplifies the connecting structure of the keys and key support mechanisms and allows for easy assembly of the entire device to the keyboard chassis. [Means for solving the problem]

[0007] In order to achieve the above object, the invention according to claim 1 comprises a keyboard chassis, a plurality of keys arranged on an upper portion of the keyboard chassis, each extending a predetermined length in the front-rear direction and aligned with one another in the left-right direction, and a plurality of key support mechanisms each engaging with the keyboard chassis and aligned with one another in the left-right direction to support a corresponding key from below, and causing the pressed key to rotate about a virtual fulcrum located behind the rear end of the key when the key is pressed, the key support mechanism being configured to extend a predetermined length in the front-rear direction and engaging a first support shaft provided on the keyboard chassis so as to be able to swing, and a first arm front connecting portion forward of the first support shaft is connected to a key front connecting portion provided on a front portion of the corresponding key. The keyboard has a first arm which is connected to the keyboard chassis in a rotatable and / or slidable manner, and a second arm which is configured to extend a predetermined length in the front-to-rear direction and swingably engages with a second spindle which is provided on the keyboard chassis at a position rearward and higher than the first spindle, and has a second arm rear connecting portion rearward of the second spindle which is rotatably connected to a key rear connecting portion provided at the rear of the corresponding key, and a second arm front connecting portion forward of the second spindle which is rotatably and / or slidably connected to the first arm rear connecting portion rearward of the first spindle of the first arm, and the keyboard chassis is provided with an arm assembly opening which is open to at least one of the upper and front directions, for assembling the first arm and the second arm to the keyboard chassis.

[0008] According to this configuration, a number of keys, each extending a predetermined length in the front-rear direction, are arranged side by side in the left-right direction on the upper part of the keyboard chassis. The keyboard chassis is also provided with a number of key support mechanisms arranged side by side in the left-right direction to engage with the keys, and each key support mechanism supports a corresponding key from below and, when a key is pressed, rotates the pressed key around a virtual fulcrum located at the rear.

[0009] Each key support mechanism has a first arm and a second arm as described above. The first arm is pivotally engaged with the first spindle of the keyboard chassis, and a first arm front connector located in front of the first spindle is pivotally and slidably connected to a key front connector provided at the front of the corresponding key. The second arm is pivotally engaged with the second spindle of the keyboard chassis, and a second arm rear connector located behind the second spindle is pivotally connected to a key rear connector provided at the rear of the corresponding key. In addition, the second arm is pivotally and slidably connected to the first arm rear connector of the first arm, and a second arm front connector located in front of the second spindle. The front and rear of the key are supported from below by the key support mechanism configured in this way, so that when the front end of the key is pressed down when the key is pressed, the rear end of the key moves downward in conjunction with the front end of the key while maintaining a certain relationship with the front end of the key. That is, when a key is pressed, the entire key rotates around a virtual fulcrum at the rear.

[0010] Furthermore, according to the above configuration, the keyboard chassis is provided with an arm installation opening that opens to at least one of the upper and front sides, which allows the first arm and the second arm to be easily installed to the keyboard chassis from above or from the front side of the keyboard chassis through the arm installation opening, thereby enabling the keyboard device to be assembled efficiently.

[0011] The invention according to claim 2 relates to a keyboard device for a keyboard instrument according to claim 1, wherein the keyboard chassis comprises a plurality of chassis main bodies each made of a resin molded product and connected to each other in the left-right direction, and the chassis main bodies have a first support shaft and a second support shaft, and further include a key front guide portion for guiding the front end of the key, a key rear guide portion for guiding the rear end of the key, a key upper limit stopper portion for restricting an upper limit position of the front end of the key, a key lower limit stopper portion for restricting a lower limit position of the front end of the key, a first arm upper limit stopper portion for restricting an upper limit position of the rear end of the first arm, and a key rear limit stopper portion for restricting an upper limit position of the rear end of the first arm. The lock has at least one of a first arm lower limit stopper portion for regulating the lower limit position, a first arm side surface guide portion for guiding the side surface of the first arm, and a second arm side surface guide portion for guiding the side surface of the second arm, and is characterized in that the first spindle and the second spindle, and at least one of the key front side guide portion, the key rear side guide portion, the key upper limit stopper portion, the key lower limit stopper portion, the first arm upper limit stopper portion, the first arm lower limit stopper portion, the first arm side surface guide portion, and the second arm side surface guide portion are integrally molded via a plurality of ribs extending in the front-to-rear direction and arranged in the left-to-right direction at intervals from each other.

[0012] According to this configuration, the keyboard chassis is formed by connecting a plurality of chassis bodies made of resin molded products to each other in the left-right direction. Each chassis body is integrally molded with the first and second support shafts and at least one of the key front guide portion, key rear guide portion, key upper limit stopper portion, key lower limit stopper portion, first arm upper limit stopper portion, first arm lower limit stopper portion, first arm side guide portion, and second arm side guide portion via the plurality of ribs. This makes it possible to easily obtain at least one of the key front guide portion, key rear guide portion, key upper limit stopper portion, key lower limit stopper portion, first arm upper limit stopper portion, first arm lower limit stopper portion, first arm side guide portion, and second arm side guide portion in addition to the first and second support shafts by a single molding operation when molding the chassis body.

[0013] The invention of claim 3 is characterized in that, in the keyboard device of the keyboard instrument described in claim 2, the first support shaft is composed of a plurality of first support shafts each provided between adjacent ones of the plurality of ribs, and the second support shaft is composed of a plurality of second support shafts each provided between adjacent ones of the plurality of ribs, and at least one of the plurality of first support shafts and the plurality of second support shafts are arranged on the same axis extending in the left-right direction.

[0014] According to this configuration, the first support shaft as the swing shaft of the first arm is composed of a plurality of first support shafts provided between adjacent ribs, and the second support shaft as the swing shaft of the second arm is composed of a plurality of second support shafts provided between adjacent ribs. In this case, the plurality of first support shafts are arranged on the same axis extending in the left-right direction, and the plurality of second axes are arranged on another same straight line, so that all the first arms and all the second arms can be aligned in the left-right direction in the plurality of key support mechanisms regardless of the type of key (white key or black key). In addition, when one of the plurality of first support shafts and the plurality of second support shafts is arranged on the same axis and the other is not arranged on the same axis, in the plurality of key support mechanisms, one of all the first arms and one of all the second arms can be aligned in the left-right direction, and the other can be aligned in the left-right direction according to the type of key.

[0015] The invention according to claim 4 is characterized in that, in the keyboard device of the keyboard instrument described in claim 2 or 3, a certain rib among the multiple ribs is formed so that a portion of it is omitted in the front-to-rear direction.

[0016] According to this configuration, certain of the multiple ribs can be omitted in the front-to-rear direction, which makes it possible to reduce the weight of the chassis body.In addition, by reducing the material used to mold the chassis body, it is possible to reduce manufacturing costs.

[0017] The invention of claim 5 is a keyboard device for a keyboard instrument described in any one of claims 2 to 4, characterized in that each of the multiple chassis bodies has a side wall that is connected to the other and is formed in a complementary shape.

[0018] With this configuration, when multiple chassis bodies are connected to each other in the left-right direction, the connected side wall portions can be configured in the same way as other ribs without increasing their thickness in the left-right direction, thereby ensuring stable strength and rigidity over the entire left-right direction of the keyboard chassis. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view showing a keyboard device according to an embodiment of the present invention, with one white key and one black key attached to a keyboard chassis, where (a) shows the state when viewed from the upper right, and (b) shows the state when viewed from the upper left. [Diagram 2] 2 is a perspective view showing the keyboard device shown in FIG. 1 in a state where the white keys and the black keys, together with their respective key support mechanisms, have been removed from the keyboard chassis. FIG. [Diagram 3] 1A and 1B are diagrams for explaining a keyboard chassis, in which (a) is a plan view of the keyboard chassis with a single chassis main body at its center, and (b) is a cross-sectional view taken along line AA in (a). [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. [Diagram 5] 1A and 1B are perspective views showing a black key and a 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 is an enlarged perspective view of the rear end portion of the second arm, FIG. 1B is a view of the key and the rear end portion of the second arm when viewed from below while separated from each other, and FIG. 1C is an enlarged plan view of the key and the rear portion of the second arm. [Figure 7] FIG. 2 is a plan view of the white keys and their key support mechanisms, and the black keys and their key support mechanisms, in which the white keys and black keys are indicated by dashed double-dashed lines. [Figure 8] 1A and 1B are diagrams for explaining the operation of a white key in a keyboard device, in which (a) shows the key-released state and (b) shows the key-depressed state. [Figure 9] 1A and 1B are diagrams for explaining the operation of a black key in a keyboard device, in which (a) shows a key-released state and (b) shows a key-depressed state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] A preferred embodiment of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a perspective view of a keyboard device 1 of an electronic piano to which the present invention is applied, showing a state in which each of the white keys 2a and black keys 2b is attached to a keyboard chassis 4, (a) showing the state as seen from the upper right, and (b) showing the state as seen from the upper left. Fig. 2 shows the keyboard device 1 shown in Fig. 1 in a state in which the white keys 2a and black keys 2b have been removed from the keyboard chassis 4 together with a key support mechanism 6a for white keys and a key support mechanism 6b for black keys that support them from below, respectively.

[0021] In both figures, only a part of the keyboard chassis 4 of the keyboard device 1 is shown, and specifically, two chassis bodies 4a, 4a for one octave are shown connected to each other on the left and right. In addition, a front rail 8 and a rear rail 9 made of metal are attached to the front and rear ends of the underside of the keyboard chassis 4, respectively, and extend in the left-right direction. The keyboard chassis 4 is fixed to a shelf board (not shown) of the electronic piano via these rails 8, 9.

[0022] In the following description, when there is no particular distinction between the white keys 2a and the black keys 2b, they will simply be referred to as "keys 2", and when there is no particular distinction between the key support mechanisms 6a for the white keys and the key support mechanisms 6b for the black keys, they will simply be referred to as "key support mechanisms 6".

[0023] FIG. 3 shows the keyboard chassis 4 with a single chassis main body 4a at the center, with (a) being a plan view and (b) being a cross-sectional view taken along line AA in (a). The chassis main body 4a of the keyboard chassis 4 is made of a resin molded product of a predetermined shape, which is formed by injection molding a predetermined resin material (e.g., ABS resin). As shown in FIG. 3, the front part 11, middle part 12, and rear part 13 of the chassis main body 4a are all formed to extend in the left-right direction as a whole (left-right direction in FIG. 3(a)), and are integrally molded with a plurality of ribs 14 spaced apart in the left-right direction and each extending in the front-rear direction. In the following description, the front part 11, middle part 12, and rear part 13 of the chassis main body 4a of the keyboard chassis 4 are referred to as the "chassis front part 11," the "chassis middle part 12," and the "chassis rear part 13," respectively.

[0024] The chassis front part 11 mainly serves to guide the white keys 2a when they are pressed, and to regulate the upper and lower limit positions of the front ends of the white keys. A number of white key guides 11a are arranged in a line in the left-right direction and stand upright on the chassis front part 11. Each white key 2a is inserted from below into the chassis front part 11 to prevent the white keys 2a from swaying sideways. The white key guides 11a are formed by attaching a resin guide body 15 of a predetermined shape (only two are shown in Figs. 2 and 3(a)) to the top of a number of standing pieces 8a that are formed integrally with the front rail 8 by bending a metal plate of a predetermined shape.

[0025] In addition, the front part 11 of the chassis has engagement holes 11b, 11b that penetrate in the vertical direction on both the left and right sides of each white key guide 11a, and two upper limit position regulating parts 21, 21 on the left and right sides of the white key 2a, which will be described later, engage with these engagement holes 11b, 11b in a penetrating state, respectively.

[0026] Furthermore, the chassis front part 11 is provided at its front end with a stopper attachment part 11c (upper key stopper part, lower key stopper part) that protrudes forward and extends in the left-right direction across the entire chassis body 4a, and a white key upper limit stopper 16a and a white key lower limit stopper 16b are attached to the lower and upper surfaces of this stopper attachment part 11c so as to extend in the left-right direction, respectively. The chassis front part 11 is provided at a predetermined position behind the white key guide 11a with a stopper attachment part 11d (upper key stopper part) for black keys that extends in the left-right direction across the entire chassis body 4a, and a black key upper stopper 17 is attached to this stopper attachment part 11d so as to extend in the left-right direction.

[0027] The chassis intermediate section 12 mainly guides the black key 2b when the key is pressed, and also supports the first arm 31 and the second arm 32 of the key support mechanism 6a, 6b for the white and black keys so that they can swing. The chassis intermediate section 12 has a flat plate-like flat section 12a extending in the left-right direction, and a number of black key guides 12b standing on the flat section 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, and prevents the black key 2b from swinging sideways. The black key guides 12b are formed by attaching a resin guide body (not shown) having a predetermined width to each of a number of standing sections 12c (key front guide sections) integrally molded with the chassis body 4a.

[0028] In addition, a first arm support section 18 that supports a first arm 31 of the key support mechanism 6 is provided at the front of the chassis intermediate section 12. The first arm support section 18 has a plurality of first support shafts 18a provided between adjacent ribs 14, 14 so as to extend in the left-right direction, and side guide sections 18b, 18b (first arm side guide sections) provided at both ends of each first support shaft 18a. The plurality of first support shafts 18a are arranged on the same axis line extending in the left-right direction, and the first arm 31 is supported by these first support shafts 18a so as to be able to swing freely. In addition, the side guide sections 18b, 18b at both ends of the first support shaft 18a are formed integrally with the rib 14 in a state of protruding toward the first support shaft 18a, and the distance between the both side guide sections 18b, 18b is set to be approximately the same as the left-right width of a bearing 36 of the first arm 31, which will be described later. As a result, when the first arm 31 swings about the first support shaft 18a, the left and right side surfaces of the first arm 31 come into sliding contact with both side surface guide portions 18b, 18b, thereby preventing lateral vibration.

[0029] In addition, 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. The second arm support section 19 has a plurality of second support shafts 19a provided between adjacent ribs 14, 14 so as to extend in the left-right direction, and side guide sections 19b, 19b (second arm side guide sections) provided at both ends of each second support shaft 19a. The second support shafts 19a are arranged on the same axis extending 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 as to be able to swing freely. In addition, the side guide sections 19b, 19b at both ends of the second support shaft 19a are formed integrally with the rib 14 in a state of protruding toward the second support shaft 19a side, and the distance between the two side guide sections 19b, 19b is set to be approximately the same as the left-right width of a bearing 41 of the second arm 32 described later. As a result, when the second arm 32 swings about the second support shaft 19a, the left and right side surfaces of the second arm 32 come into sliding contact with both side surface guide portions 19b, 19b, thereby preventing lateral vibration.

[0030] As described above, the multiple first support shafts 18a with which the first arms 31 of the key support mechanism 6 engage are arranged on the same axis, and similarly, the multiple second support shafts 19a with which the second arms 32 engage are also arranged on the same axis, so that all of the first arms 31 and all of the second arms 32 of the multiple key support mechanisms 6 in the keyboard device 1 can be uniformly aligned in the left-right direction.

[0031] Although not shown in the drawings, it is also possible to arrange one of the multiple first support shafts 18a and the multiple second support shafts 19a on the same axis, and arrange the other on a different axis depending on the type (white key 2a or black key 2b) of the corresponding key 2. In this case, in the multiple key support mechanisms 6, one of all the first arms 31 and one of all the second arms 32 can be aligned uniformly in the left-right direction, and the other can be aligned uniformly in the left-right direction for each type of key 2.

[0032] Although not shown, a key switch for detecting key press information of each key 2 is provided below the keyboard chassis 4, between the chassis front part 11 and the chassis middle part 12. This key switch is composed of a horizontally long printed circuit board extending in the left-right direction, and multiple switch bodies made of rubber switches attached to the printed circuit board for each key 2. The rubber switches are pressed by the first arm 31 when the key is pressed.

[0033] The chassis rear part 13 mainly guides the key 2 in the up-down direction while preventing the rear end of the key 2 from swaying sideways, and regulates the upper and lower limit positions of the rear end of the first arm 31. As shown in FIG. 3, the chassis rear part 13 has a plurality of partition walls 13a spaced apart from each other at a predetermined interval in the left-right direction to separate adjacent keys 2, 2. In addition, adjacent partition walls 13a, 13a are provided with key guide protrusions 13b, 13b that extend in the up-down direction and protrude inward on the opposing side surfaces. The distance between the two key guide protrusions 13b, 13b is set to be approximately the same as the left-right width of the rear end of the key 2. As a result, when the key 2 is pressed, the rear end of the key 2 is smoothly guided in the up-down direction while preventing swaying sideways.

[0034] As shown in Fig. 3(b), stopper attachment parts 13c and 13d (first arm upper limit stopper part, first arm lower limit stopper part) are provided at predetermined upper and lower positions of the rear part 13 of the chassis, and extend in the left-right direction over the entire chassis main body 4a. The upper and lower stopper attachment parts 13c and 13d are provided with the first arm upper limit stopper 10a and the first arm lower limit stopper 10b, respectively. The first arm upper limit stopper 10a and the first arm lower limit stopper 10b are for restricting the upper limit position and the lower limit position of the rear end of the first arm 31, which functions as a hammer for applying touch weight to the key 2. The stoppers 10a and 10b are made of, for example, urethane, have a rectangular cross section, and are provided so as to extend over the entire left-right direction of the keyboard chassis 4.

[0035] As shown in FIG. 3(a), the ribs 14, 14 corresponding to the side walls at both the left and right ends of the chassis main body 4a are formed in a complementary shape that continues in the front-rear direction when the two chassis main bodies 4a are connected to each other. Specifically, the rib 14 at the left end of the chassis main body 4a is formed in a state in which the part corresponding to the chassis middle part 12 is omitted, while the rib 14 at the right end is formed in a state in which the parts corresponding to the chassis front part 11 and the chassis rear part 13 are omitted. Therefore, by connecting the two chassis main bodies 4a to each other adjacent to each other, the connected side wall parts can be configured in the same way as the other ribs 14 without increasing the thickness in the left-right direction. This ensures stable strength and rigidity throughout the entire left-right direction of the keyboard chassis 4.

[0036] 3(a), the chassis intermediate portion 12 has an engagement recess 12d of a predetermined shape that opens to the left formed at the left end of the flat portion 12a, and an engagement protrusion 12e of a predetermined shape that protrudes to the right and corresponds to the engagement recess 12d formed at the right end of the flat portion 12a. Therefore, when two chassis bodies 4a are connected to each other, the engagement protrusion 12e of one chassis body 4a is fitted into the engagement recess 12d of the other chassis body 4a, so that positioning can be easily performed when connecting the two chassis bodies 4a, 4a.

[0037] As shown in Fig. 3(a) and (b), the chassis body 4a of the keyboard chassis 4 configured as above is provided with a first opening 5a (arm assembly opening) that opens upward and forward, and a second opening 5b (arm assembly opening) that opens upward. Through the first opening 5a, the first arm 31 of the key support mechanism 6 can be easily engaged with the first support shaft 18a from the outside, and through the second opening 5b, the second arm 32 can be easily engaged with the second support shaft 19a from the outside. In this way, the first arm 31 and the second arm 32 of the key support mechanism 6 can be easily assembled to the keyboard chassis 4, and as a result, the keyboard device 1 can be efficiently assembled.

[0038] As described above, the chassis main body 4a is integrally provided with the first support shaft 18a, the second support shaft 19a, the standing portion 12c for the black key guide 12b, the key guide protrusion 13b, the stopper mounting portions 11c, 11d, 13c, 13d, the side guide portion 18b for the first arm 31, the side guide portion 19b for the second arm 32, and the rib 14, and these can be easily obtained by a single molding operation.

[0039] In addition, in the chassis main body 4a, all of the multiple ribs 14 other than those on the side walls at both the left and right ends are configured to extend in the front-rear direction from the chassis front part 11 to the chassis rear part 13, but it is also possible to form the chassis 14 so that some of the ribs 14 are omitted. For example, it is possible to omit the ribs 14 as appropriate between the chassis front part 11 and the chassis middle part 12. This allows the chassis main body 4a to be made lighter, and the manufacturing cost can be reduced by reducing the material used to mold the chassis main body 4a.

[0040] 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 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-rear direction and to be hollow and open downward. The front end of the white key 2a is provided with a pair of left and right upper limit position restricting parts 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 restricting parts 21, 21 are engaged with the left and right engagement holes 11b, 11b of the chassis front part 11 while penetrating therethrough.

[0041] Additionally, a front-key connecting part 22 that is connected to a first arm 31 of the key support mechanism 6a is provided at the front of the white key 2a at a predetermined position behind the upper limit position regulation part 21. The front-key connecting part 22 has a connecting recess 22a that is U-shaped and has an elongated hole-like side that opens forward.

[0042] 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. The key rear connector 23 has a plate-shaped connector body 23a that hangs down from the center 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 engagement protrusions 23b, 23b that protrude coaxially from the left and right side surfaces of the connector body 23a. A tool insertion hole 24 is formed at the rear of the white key 2a, which penetrates in the up-down direction and is used to insert a specific tool from above when releasing 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, as described below.

[0043] The rear end of the white key 2a is formed so that its width in the left-right direction is smaller than that of the portion in front of it, and is set to approximately the same distance as the distance between the key guide protrusions 13b, 13b facing each other at the rear part 13 of the chassis described above.

[0044] 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 connected to the front-key connecting portion 22 and the rear-key connecting portion 23 of the white key 2a, respectively. 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, formed by injection molding a predetermined resin material (e.g., polyacetal). The arm body 33 extends a predetermined length in the front-rear direction, and is provided at its front end with a first arm front connecting portion 35 that connects to the front-key connecting portion 22 of the white key 2a. The first arm front connecting portion 35 includes a box portion 35a formed in a box shape that opens upward and forward, and a connecting shaft 35b that is provided to extend in the left-right direction while connecting 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 connecting part 22 of the white key 2a so as to be rotatable and slidable in the front-rear direction. A bushing 35c is attached to the connecting shaft 35b to fill the gap between the outer circumferential surface of the connecting shaft 35b and the inner surface of the connecting recess 22a.

[0045] The arm body 33 also has a U-shaped bearing 36 with a downwardly open side at a predetermined position immediately behind 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 body 33 has a first arm rear connecting portion 37 that connects to the second arm 32 at a predetermined position behind the bearing 36. 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 from the left and right side surfaces of the arm 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.

[0046] The weight mounting portion 38, which is the rear of the arm main body 33, is provided with two front and rear mounting protrusions 38a, 38a that protrude outward at predetermined positions on both the left and right sides, and a mounting hole 38b that penetrates in the left-right direction is formed between them.

[0047] The weight 34 is made of a material (for example, a metal such as iron) having a higher specific gravity than the arm body 33, and is composed of two elongated plate-like weights. Each weight 34 is formed into a predetermined shape by pressing a metal plate or the like. Specifically, each weight 34 is formed with two fitting holes 34a, 34a and a mounting hole 34b corresponding to the two mounting protrusions 38a, 38a and the mounting hole 38b of the arm body 33, respectively. Both weights 34, 34 are fixed to the arm body 33 by crimping rivets (not shown) inserted into the mounting holes 34b, 34b and 38b, with the weight mounting portion 38 of the arm body 33 sandwiched between them from both sides.

[0048] The second arm 32 is made of a resin molded product of a predetermined shape by injection molding 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-rear direction. The second arm 32 has a bearing portion 41 near the center in the longitudinal direction, the bearing portion 41 having a C-shaped side shape that opens forward, and the bearing portion 41 rotatably engages with the second support shaft 19a of the keyboard chassis 4.

[0049] The rear part of the second arm 32 is provided with a second arm rear connector 42 that is connected to the key rear connector 23 of the white key 2a. The second arm rear connector 42 is bifurcated and has two left and right connector arms 43, 43 that extend parallel to each other for a predetermined length along the length of the second arm 32. A connector hole 43a is formed in the rear end of each connector arm 43, penetrating in the left-right direction. The connector arms 43, 43 hold the connector body 23a of the key rear connector 23 of the white key 2a between their rear ends, and each connector hole 43a is rotatably fitted into the corresponding engagement protrusion 23b of the key rear connector 23. The connector arms 43, 43 are configured to bend in a state where the distance between their rear ends is widened to allow attachment and detachment of the connector body 23a and the engagement protrusion 23b.

[0050] Furthermore, a second arm front connecting part 45 is provided at the front of the second arm 32, which is connected to the first arm rear connecting part 37 (connecting shaft 37a) of the first arm 31. This second arm front connecting part 45 has a pair of left and right connecting pieces 45a, 45a spaced apart from each other by a predetermined distance in the left-right direction, and each connecting piece 45a is formed with a U-shaped connecting recess 45b (second connecting recess) whose side shape is an elongated hole and opens forward. The left and right connecting pieces 45a, 45a of the second arm front connecting part 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.

[0051] FIG. 5(a) shows the black key 2b and its key support mechanism 6b in an enlarged manner, and FIG. 5(b) shows them in an exploded manner. The black key 2b is formed by injection molding the same resin material as the white key 2a, and is shorter than the white key 2a, extends a predetermined length in the front-rear direction, and is hollow and open downward. The front lower end of the black key 2b is provided with a front-side connecting part 26 formed in a manner similar to the front-side connecting part 22 of the white key 2a. The front-side connecting part 26 has a connecting recess 26a formed in a U-shape with a long hole-like side shape and an open frontward. The front-side connecting part 26 has an extension part 26b at the lower front end of the connecting recess 26a, which extends a predetermined length forward from the front surface of the main body of the black key 2b, and the extension part 26b functions as an upper limit position regulating part for the black key 2b. In the following description, the same components of the black key 2b and the key support mechanism 6b as those of the white key 2a and the key support mechanism 6a described above are designated by the same reference numerals, and detailed description thereof will be omitted.

[0052] Similar to the white key 2a, a key rear connecting portion 23 is provided at the rear of the black key 2b, and a tool insertion hole 24 is formed which penetrates in the vertical direction.

[0053] On the other hand, the key support mechanism 6b supporting the black key 2b is constructed almost similarly 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 constructed to be exactly the same in shape and size as the arm body 33 and the second arm 32 of the key support mechanism 6a for white keys. In addition, the two weights 34A and 34B on the left and right sides of the key support mechanism 6b for black keys have different rear shapes compared to the weight 34 of the key support mechanism 6a for white keys. In addition, the left weight 34A and the right weight 34B of the key support mechanism 6b have different rear shapes.

[0054] Here, the structure of the rear end of the second arm 32, i.e., the rear end of the two left and right connecting arm parts 43, 43 will be described in more detail with reference to Fig. 6. As shown in Fig. 6(a), each connecting arm part 43 is provided with a guide part 44 on the upper side of the connecting hole 43a for guiding each engagement protrusion 23b of the key 2 to the connecting hole 43a. This guide part 44 has an inclined guide surface 44a that is inclined downward toward the front toward the inside of the connecting arm part 43, and front and rear standing guide surfaces 44b, 44b that are provided in an upright state in front and behind the inclined guide surface 44a and opposed to each other. The upper ends of the front and rear standing guide surfaces 44b, 44b are formed in an arc shape.

[0055] Because the two left and right connecting arm portions 43, 43 of the second arm 32 have the guide portions 44, 44 formed as described above, when the key 2 is connected to the second arm 32, the pair of left and right engaging protrusions 23b, 23b of the key 2 are guided, respectively, by the guide portions 44, 44 of the second arm 32 into the lower connecting holes 43a, 43a. This makes it easy to connect the key 2 to the second arm 32 when assembling the keyboard device 1.

[0056] In addition, the upper surface rear end portions of the two left and right connecting arm portions 43, 43 of the second arm 32 are provided with anti-slip portions 43b, 43b which protrude outward in the left-right direction by a predetermined length and prevent each engaging protrusion 23b of the key 2 from slipping out of each connecting hole 43a of the second arm 32.

[0057] As shown in Fig. 6(c), when the left and right engaging protrusions 23b, 23b of the key 2 are fitted into the connecting holes 43a, 43a of the second arm 32, the left and right retaining portions 43b, 43b are located directly below the left and right side walls of the key 2. For this reason, even if the rear end of the key 2 is shifted downward relative to the rear end of the second arm 32 due to a strong keystroke near the rear end of the key 2, the left and right side walls of the key 2 come into contact with the left and right retaining portions 43b, 43b of the second arm 32, preventing the rear end of the key 2 from shifting downward significantly. As a result, the left and right engaging protrusions 23b, 23b of the key 2 can be prevented from coming out of the connecting holes 43a, 43a of the second arm 32.

[0058] FIG. 7 is a plan view of the white key 2a and its key support mechanism 6a, and the black key 2b and its key support mechanism 6b, in which the white key 2a and the black key 2b are indicated by two-dot chain lines. As shown in the figure, the white key 2a, the first arm 31, and the second arm 32 are arranged so that the center line extending along the length of the white key 2a (the vertical direction in FIG. 7), the center line extending along the length of the first arm 31 of the key support mechanism 6a, and the center line extending along the length of the second arm 32 all coincide with the center line C1 in a plan view. The same is true for the black key 2b. That is, the black key 2b and the first arm 31 and the second arm 32 of the key support mechanism 6b are arranged so that they coincide with each other's center line C2 in a plan view.

[0059] As described above, in the keyboard device 1, each key 2 and the first arm 31 and second arm 32 of the key support mechanism 6 that supports it are positioned so that their center lines in the longitudinal direction coincide with each other in a plan view, so that when a key is pressed, the force exerted on the key 2 can be stably and firmly received by the key support mechanism 6. This makes it possible to increase the rigidity and durability of the keyboard device 1 as a whole.

[0060] As described above, in the key support mechanism 6a for white keys and the key support mechanism 6b for black keys, the arm bodies 33 of the first arms 31 and the second arms 32 are configured to be the same in shape and size, so that the arm bodies 33 of the first arms 31 and the second arms 32 can be standardized in the key support mechanisms 6 for white keys and black keys. This makes it possible to reduce the number of types of molds used to manufacture the first arms 31 and the second arms 32, compared to when the first arms and second arms are different for each type of key 2, for example, and thus reduces the manufacturing costs of the keyboard device as a whole.

[0061] Furthermore, the weight 34 provided on the first arm 31 of the key support mechanism 6 can be selected from a plurality of types of weights having different shapes according to the type of key 2. As a result, even if the rotation angle of the first arm 31 when a key is pressed differs depending on the type of key 2, for example, by selecting an appropriate weight from the plurality of types of weights, the weight 34 of the first arm 31 can be appropriately abutted against the first arm upper limit stopper 10a when a key is pressed.

[0062] Next, a description will be given of the operation of the key 2 and the key support mechanism 6 in the keyboard device 1 configured as above. Figure 8 shows the operation of the white key 2a and its key support mechanism 6a, and Figure 9 shows the operation of the black key 2b and its key support mechanism 6b.

[0063] In the key-released state shown in Fig. 8(a), when the player presses down 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. As the first arm 31 rotates, the second-arm front connector 45, which engages with the connector shaft 37a of the first arm 31 via the connector recess 45b, moves upward. As a result, the second arm 32 rotates clockwise around the second support shaft 19a. As the second arm 32 rotates, the rear-key connector 23 connected via the second-arm rear connector 42 at its rear end is pulled down, causing the rear end of the white key 2a to move downward.

[0064] During the above-mentioned 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 the switch body of the key switch 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.

[0065] As described above, when the white key 2a is pressed down, the first arm 31 rotates counterclockwise, causing the weight 34 of the first arm 31 to tilt upward toward the rear as shown in Fig. 8(b), and the rear end abuts against the first arm upper limit stopper 10a from below, thereby preventing the first arm 31 from rotating any further.

[0066] During the above-mentioned rotation of the first arm 31 having the weight 34, the weight of the weight 34 acts on the rear part of the first arm 31, and a rotating force acts on the first arm 31 and the second arm 32 so that their front ends (first arm front connector 35) and rear ends (second arm rear connector 42) move upward. As a result, the white key 2a is strongly supported from below by the key support mechanism 6a, and therefore, when the white key 2a is pressed down, the touch weight becomes large as a reaction force against the press.

[0067] When the front end of the white key 2a is pressed down to the lowest position, the front end of the white key 2a comes into contact with the lower key limit stopper 16b, preventing the white key 2a from being pressed down any further.

[0068] The white key 2a depressed as described above moves so as to rotate 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 depressed to the lowest position, the front end of the white key 2a is located a predetermined key stroke (e.g., 10 mm) lower, and the rear end is located approximately half the key stroke (e.g., 5 mm) lower, compared to when the key is released as shown in Fig. 8(a).

[0069] 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 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, both upper limit position restriction parts 21, 21 of the white key 2a come into contact with the upper key stopper 16a from below, preventing further rotation of the white key 2a and returning it to its original released state.

[0070] The operation of the black key 2b when pressed is similar to that of the white key 2a and the key support mechanism 6a described above. That is, when the front end of the black key 2b is pressed down in the key-released state shown in FIG. 9(a), the first arm 31 rotates counterclockwise around the first pivot 18a, and the second arm 32 rotates clockwise around the second pivot 19a, so that the black key 2b rotates around the virtual pivot Q at the rear. The position of the virtual pivot Q is set so that the distance from the front end of the black key 2b is approximately twice the length of the black key 2 itself, for example, as with the virtual pivot P of the white key 2a described above. Therefore, when the front end of the black key 2b is pressed down to the lowest position, the front end of the black key 2b is located lower by a predetermined key stroke, and the rear end is located lower by approximately half the distance of the key stroke, compared to the key-released state shown in FIG. 9(a).

[0071] 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, and the black key 2b rotates upward around the virtual fulcrum Q. Then, the extension 26b of the front-key connecting part 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.

[0072] As described above in detail, the keyboard device 1 of this embodiment can provide the various effects described above.

[0073] When assembling the keyboard device 1, the key 2 and the first arm 31 can be easily connected by simply inserting the connecting shaft 35b of the first arm 31 into the connecting recess 22a of the key 2. When connecting the key 2 and the second arm 32, the connecting body 23a of the key 2 is inserted between the two connecting arm parts 43, 43 of the second arm 32, while pushing the space between the two connecting arm parts 43, 43 apart, and the engaging protrusions 23b, 23b of the connecting body 23a are fitted into the connecting holes 43a, 43a of the two connecting arm parts 43, 43, respectively. This makes it easy to connect the key 2 and the second arm 32. Furthermore, when connecting the first arm 31 and the second arm 32, the connecting work between the first arm 31 and the second arm 32 can be easily performed by simply inserting the connecting shaft 37a of the first arm 31 into both connecting recesses 45b, 45b of the second arm 32.

[0074] 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 2 and the first arm 31 and the second arm 32 of the key support mechanism 6 that supports it are arranged so that their center lines extending along their respective length directions coincide with each other in a plan view, but the present invention is not limited to this, and it is sufficient that at least two of the key 2, the first arm 31, and the second arm 32 are arranged so that their respective center lines coincide with each other in a plan view.

[0075] In the embodiment, in the connection structure between the key front connecting part 22 of the key 2 and the first arm front connecting part 35 of the first arm 31, the connecting recess 22a is provided on the key 2 side and the connecting shaft 35b is provided on the first arm 31 side, but the present invention is not limited to this, and the connecting shaft may be provided on the key 2 side and the connecting recess on the first arm 31 side. In addition, the connecting recess 22a is a U-shaped recess with an elongated hole-like side shape that opens forward, but it is also possible to use a recess simply formed in an elongated hole shape. In this case, for example, the connecting shaft 35b of the first arm 31 can be configured so that both left and right ends protrude outward, and the connecting recess 22a can be configured as a pair of left and right connecting recesses, and the left and right connecting recesses can be snap-fitted into both ends of the connecting shaft, for example.

[0076] In addition, in the embodiment, in the connection structure between the key rear connection portion 23 of the key 2 and the second arm rear connection portion 42 of the second arm 32, the connection main body portion 23a and left and right engaging protrusions 23b, 23b are provided on the key 2 side, and the left and right connecting arm portions 43, 43 and connecting holes 43a, 43a are provided on the second arm 32 side, but the present invention is not limited to this, and it is also possible to provide the connecting arm portion and connecting hole on the key 2 side, and the connecting main body portion and engaging protrusion on the second arm 32 side.

[0077] Furthermore, in the embodiment, in the connection structure between the first arm rear connecting portion 37 of the first arm 31 and the second arm front connecting portion 45 of the second arm 32, the connecting shaft 37a is provided on the first arm 31 side and the connecting recesses 45b, 45b are provided on the second arm 32 side, but the present invention is not limited to this, and the connecting recess may be provided on the first arm 31 side and the connecting shaft may be provided on the second arm 32 side. In addition, for the connecting recess 45b, a U-shaped recess having an elongated hole-like side shape and opening forward is used, but it is also possible to use a recess simply formed in an elongated hole. In this case, the connecting recesses can be snapped into both ends of the connecting shaft 37a via a pair of left and right connecting pieces 45a, 45a in which elongated hole-like connecting recesses are formed, for example.

[0078] Furthermore, the connection structures between the above-mentioned key 2, first arm 31 and second arm 32 are not limited to the connection structures described above, and it is possible to adopt other connection structures between members or other appropriate connection structures as long as the required connection function (rotation and / or sliding) between the members connected to each other can be ensured.

[0079] In the embodiment, the weight 34 is provided on the first arm 31 of the key support mechanism 6, but the present invention is not limited to this, and a weight may be provided on the second arm 32 instead of the first arm 31. Furthermore, in the embodiment, the key switch for detecting key press information is configured to be pressed from above by the box portion 35a of the first arm front connecting portion 35 of the first arm 31, but the present invention is not limited to this, and the key switch may be placed within the movable range of the second arm 32 and pressed by the second arm 32.

[0080] Furthermore, the detailed configurations of the key 2 and the first arm 31 and second arm 32 of the key support mechanism 6 shown in the embodiment are merely examples and can be modified as appropriate within the spirit and scope of the present invention. [Explanation of symbols]

[0081] 1 Keyboard device 2 keys 2a white key 2b black key 4 Key Chassis 4a Chassis body 5a First opening (opening for assembling the arm) 5b Second opening (opening for assembling the arm) 6 Key support mechanism 6a Key support mechanism for white keys 6b Key support mechanism for black keys 10a First arm upper limit stopper 10b First arm lower limit stopper 11 Front of keyboard chassis 11a White Key Guide 11c Stopper attachment part for white keys (upper limit stopper part, lower limit stopper part) 11d Black key stopper attachment part (upper key stopper part) 12 Middle section of keyboard chassis 12b Black Keys Guide 12c Black key guide upright (guide part in front of the key) 13 Rear of keyboard chassis 13a Partition wall 13b Key guide protrusion (rear guide part of key) 13c Stopper attachment part (upper limit stopper part of first arm) 13d Stopper mounting part (lower limit stopper part of first arm) 14 Ribs 15 White key guide body 16a Upper key stop for white keys 16b Lower key limit stop for white keys 17 Upper key stopper for black keys 18 First arm support part 18a 1st spindle 18b Side guide part (first arm side guide part) 19 Second arm support part 19a 2nd support shaft 19b Side guide part (second arm side guide part) 22 Key front connection part 23 Key rear connection part 26 Black key front connection part 31 First Arm 32 Second Arm 35 First arm front connection part 37 First arm rear connection part 42 Rear connection part of second arm 45 Second arm front connection part P White key imaginary fulcrum Q Virtual fulcrum of black key

Claims

1. A keyboard chassis and A plurality of keys, each extending a predetermined length in the front-rear direction and arranged side by side in the left-right direction, on an upper portion of the keyboard chassis; a plurality of key support mechanisms each of which is engaged with the keyboard chassis and arranged in a left-right arrangement to support the corresponding key from below, and which, when a key is pressed, rotates the pressed key about a virtual fulcrum located behind the rear end of the key; Equipped with The key support mechanism includes: a first arm configured to extend a predetermined length in the front-rear direction, pivotably engaged with a first spindle provided on the keyboard chassis, and a first arm front connector located forward of the first spindle, which is rotatably and / or slidably connected to a key front connector provided on the front of the corresponding key; a second arm configured to extend a predetermined length in a front-rear direction, pivotably engaged with a second spindle provided on the keyboard chassis at a position rearward and higher than the first spindle, a second arm rear connector located rearward of the second spindle rotatably connected to a key rear connector provided at the rear of the corresponding key, and a second arm front connector located forward of the second spindle rotatably and / or slidably connected to a first arm rear connector located rearward of the first spindle of the first arm, A keyboard device for a keyboard instrument, characterized in that the keyboard chassis is provided with an arm assembly opening that opens to at least one of the upper and front sides and is used to assemble the first arm and the second arm to the keyboard chassis.

2. the keyboard chassis includes a plurality of chassis bodies each made of a resin molded product and connected to each other in the left-right direction, The chassis body includes: The first support shaft and the second support shaft are provided, the locking mechanism has at least one of a key front guide portion for guiding the front end of the key, a key rear guide portion for guiding the rear end of the key, a key upper limit stopper portion for regulating an upper limit position of the front end of the key, a key lower limit stopper portion for regulating a lower limit position of the front end of the key, a first arm upper limit stopper portion for regulating an upper limit position of the rear end of the first arm, a first arm lower limit stopper portion for regulating a lower limit position of the rear end of the first arm, a first arm side guide portion for guiding a side surface of the first arm, and a second arm side guide portion for guiding a side surface of the second arm, 2. The keyboard device of a keyboard instrument as defined in claim 1, wherein the first and second support shafts and at least one of the key front guide portion, the key rear guide portion, the key upper limit stopper portion, the key lower limit stopper portion, the first arm upper limit stopper portion, the first arm lower limit stopper portion, the first arm side guide portion, and the second arm side guide portion are integrally formed via a plurality of ribs extending in the front-rear direction and arranged in the left-right direction at intervals from each other.

3. the first support shaft is made up of a plurality of first support shafts each provided between adjacent ones of the plurality of ribs, the second support shaft is made up of a plurality of second support shafts each provided between adjacent ones of the plurality of ribs, 3. The keyboard device for a keyboard instrument according to claim 2, wherein at least one of the plurality of first support shafts and the plurality of second support shafts are arranged on a same axis extending in the left-right direction.

4. 4. The keyboard device for a keyboard instrument according to claim 2 or 3, wherein a predetermined rib among the plurality of ribs is formed so as to be partially omitted in the front-rear direction.

5. 5. The keyboard device for a keyboard instrument according to claim 2, wherein each of the plurality of chassis bodies has a side wall on a side where the chassis bodies are connected to each other, the side wall being formed in a complementary shape.

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