JP7696271B2 - Keyboard device for keyboard instruments - Google Patents

Description

The present invention relates to a keyboard device for keyboard instruments such as electronic pianos, which is equipped with hammers that rotate in conjunction with a pressed key.

A known example of this type of conventional keyboard device is disclosed in Patent Document 1. This keyboard device includes a chassis made of synthetic resin, and the hammer is supported rotatably on a hammer support shaft (hereinafter simply referred to as the "support shaft") of the chassis. The support shaft is integral with the chassis, protrudes to the side, and has a circular cross section. The hammer is made of synthetic resin and has a hammer body that extends in the front-rear direction, and a bearing part that is provided midway and supported by the support shaft. The bearing part is formed in a C-shape that opens to the rear, and has a circular retaining hole in the center and a guide groove that is connected to the retaining hole and opens to the rear. The guide groove extends almost horizontally when the key is released, and tapers toward the retaining hole, with its minimum width being smaller than the diameter of the support shaft.

In the above configuration, when attaching the hammer to the support shaft, the bearing portion of the hammer is positioned in front of the support shaft, the guide groove is engaged with the support shaft, and the hammer is then pressed backward. As a result, the guide groove is pushed open by the support shaft, and the hammer moves backward while being guided by the guide groove. Then, the guide groove overcomes the support shaft, and the retaining hole fits into the support shaft, so that the hammer is supported on the support shaft via the bearing portion so that it can rotate freely.

In addition, in the keyboard device disclosed in Patent Document 2, the hammer has an axle hole that fits onto the support shaft of the chassis, and a guide groove that is connected to the axle hole and opens downward, and is fitted onto the support shaft from above via the guide groove.

JP 2016-191832 A JP 2015-87591 A

When a keyboard device is transported as a product, it is often subjected to shocks mainly in the front-rear and up-down directions. In contrast, in the keyboard device of Patent Document 1 mentioned above, the hammer is fitted into the support shaft from the front via a nearly horizontal guide groove. For this reason, if a shock acts in the front-rear direction during transportation, etc., the direction of the resulting inertial force and the direction in which the hammer is fitted are nearly the same, so there is a risk that the hammer will come off the support shaft even if a restriction is provided in the guide groove. Similarly, in the keyboard device of Patent Document 2, the hammer is fitted into the support shaft from above, so there is a risk that the hammer will come off the support shaft when a shock acts in the up-down direction.

The present invention has been made to solve the above-mentioned problems, and has an object to provide a keyboard device for a keyboard instrument that can effectively prevent the hammer from coming off the support shaft when an impact is applied.

In order to achieve this object, the invention of claim 1 comprises a chassis, a rotatable key, and a hammer rotatably supported on a support shaft of the chassis and rotating in conjunction with a pressed key, the hammer having an axle hole that can be fitted onto the support shaft, and a guide groove that extends diagonally upward from the underside of the hammer to connect to the axle hole, has a groove width smaller than the diameter of the support shaft, and guides the axle hole to the support shaft when the hammer is attached, and is characterized in that when the key is in the released state, the guide groove extends diagonally at an angle of 45±15 degrees to the horizontal .

According to this configuration, when attaching the hammer to the support shaft, the shaft hole and guide groove of the hammer are positioned diagonally above the support shaft, the guide groove is engaged with the support shaft, and the hammer is then pressed diagonally downward along the guide groove. As a result, the hammer moves diagonally downward while being guided by the guide groove, with the narrow guide groove being elastically pushed open by the support shaft. Then, when the guide groove overcomes the support shaft, the guide groove elastically returns to its original position and the shaft hole fits (snaps) into the support shaft. As a result, the hammer is attached to the support shaft via the shaft hole and supported so as to be freely rotatable.

As described above, the hammer is snap-fitted onto the support shaft via the shaft hole. In addition, a guide groove extends obliquely from the underside of the hammer to the shaft hole. Therefore, when an impact acts on the keyboard device in the front-to-back or up-to-down directions, such as during transportation of the product, the direction of the resulting inertial force differs significantly from the direction of the guide groove, dispersing the inertial force. As a result of the above, it is possible to effectively prevent the hammer from coming off the support shaft when an impact acts on it.

Furthermore, if the inclination angle of the guide groove with respect to the horizontal is greater than 60 degrees, the guide groove will be close to vertical, and therefore the dispersion of the inertial force when an impact in the up-down direction acts will be insufficient. On the other hand, if the inclination angle of the guide groove is less than 30 degrees, the guide groove will be close to horizontal, and therefore the dispersion of the inertial force when an impact in the front-rear direction acts will be insufficient. Therefore, according to the above configuration, since the inclination angle of the guide groove with respect to the horizontal is 45±15 degrees, the inertial force caused by the impact can be sufficiently dispersed, and the detachment of the hammer can be effectively suppressed.

The invention according to claim 2 is a keyboard device for a keyboard instrument as described in claim 1 , characterized in that the hammer is formed with a concave-convex portion with which a tool for moving the hammer diagonally upward from the support shaft and removing it can engage.

In the keyboard device of claim 1 , the hammer is snap-fitted onto the support shaft, making it difficult to remove the hammer for repairs, etc. With this configuration, a concave-convex portion is formed on the hammer, and the hammer can be easily removed from the support shaft by operating a tool engaged with the concave-convex portion and moving the hammer diagonally upward in the direction of the extension of the guide groove.

1A and 1B are perspective views showing a portion (for one octave) of a keyboard device of an electronic piano to which the present invention is applied, in which (a) shows the external 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. 2 is a perspective view showing the keyboard device shown in FIG. 1B 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. 1A is a plan view of the keyboard device shown in FIG. 1B, and FIG. 1B is a cross-sectional view taken along line AA. 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. 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. 5A and 5B are diagrams for explaining the operation of a white key in a keyboard device, in which FIG. 5A shows a key-released state and FIG. 5B shows a key-depressed state. 5A and 5B are diagrams for explaining the operation of a black key in a keyboard device, in which FIG. 5A shows a key-released state and FIG. 5B shows a key-depressed state. 5A and 5B are enlarged schematic views showing a bearing portion of a first arm and a first support shaft supporting the bearing portion, respectively, before and after attachment; 1A to 1C are diagrams for explaining the packaging state of the keyboard device and the state in which the keyboard device is subjected to impact during transportation, etc. FIG. FIG. 1A is a perspective view of a first arm on which a recessed and protruding portion for removal is formed, and FIGS. 1B to 1D are partially enlarged views showing different examples of the recessed and protruding portion in part B of FIG. 11A and 11B are diagrams showing a state before and after detachment of the first arm from the first support shaft using the uneven portion in FIG. 10 .

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

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.

This keyboard device 1 is equipped with a keyboard chassis 4, a number 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 that is rotatably attached to the keyboard chassis 4 for each key 2 and supports the corresponding key 2 from below, and a key switch 3 for detecting key press information for each key 2.

The keyboard chassis 4 has a chassis body 4a made of a resin molded product of a predetermined shape, for example, 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 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 body 4a of the keyboard chassis 4 will be referred to as the "chassis front part 11," the "chassis middle part 12," and the "chassis rear part 13," respectively.

The chassis front 11 is mainly for guiding the white key 2a when the key is pressed and for regulating the upper and lower limit positions of the front end. A plurality of white key guides 11a are arranged in a left-right direction on the chassis front 11, which are inserted from below for each white key 2a to prevent the white key 2a from swaying sideways. In addition, the chassis front 11 is provided with 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 of the white key 2a, which will be described later, are engaged in a state in which they penetrate through both engagement holes 11b, 11b. Furthermore, the chassis front 11 is provided with a stopper attachment part 11c at its front end, which protrudes forward and extends in the left-right direction over the entire chassis body 4a, and a key upper limit stopper 16a and a key lower limit stopper 16b for the white key are attached to the lower and upper surfaces of the stopper attachment part 11c, respectively, so as to extend in the left-right direction. In addition, a black key stopper attachment section 11d is provided on the front of the chassis 11 at a specified position behind the white key guide 11a, and extends left and right across the entire chassis body 4a. An upper key limit stopper 17 for the black keys is attached to this stopper attachment section 11d so as to extend left and right.

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 freely. The chassis intermediate section 12 has a flat plate-like section 12a extending in the left-right direction, and a plurality of black key guides 12b standing on the flat section 12a and spaced appropriately in the left-right direction. Each black key guide 12b is inserted from below for each black key 2b to prevent the black key 2b from swinging sideways. In addition, a first arm support section 18 that supports the 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 that are provided between adjacent ribs 14, 14 so as to extend in the left-right direction, and the first arm 31 is supported by these first support shafts 18a so that it can swing freely. 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 so as to extend in the left-right direction. The plurality of 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, a first arm lower limit stopper 10b that extends in the left-right direction over the entire chassis main body 4a is provided at a predetermined position of a middle rail 8 (described later) provided on the lower side of the chassis intermediate section 12.

The key switch 3 is attached to the bottom of the keyboard chassis 4, between the chassis front part 11 and the chassis middle part 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 the first arm 31 when the key is pressed.

The chassis rear part 13 mainly guides the key 2 in the vertical direction while preventing lateral vibration at its rear end, and regulates the upper limit position of the rear end of the first arm 31. As shown in Figures 2 and 3(a), 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. Also, as shown in Figure 3(b), a first arm upper limit stopper 10a extending in the left-right direction over the entire chassis main body 4a is provided at a predetermined position on the upper part of the chassis rear part 13. This first arm upper limit stopper 10a and the first arm lower limit stopper 10b provided on the chassis intermediate part 12 are intended to regulate the upper limit position of the first arm 31, which functions as a hammer for applying touch weight to the key 2, when the first arm 31 rotates upward and the lower limit position when the first arm 31 rotates downward. In addition, a metal cover plate 15 is attached to the top of the rear part 13 of the chassis, extending left and right across the entire chassis body 4a and positioned to cover the rear end of the key 2.

As shown in Figs. 2 and 3(a), the chassis body 4a of the keyboard chassis 4 configured as described above has a plurality of first openings 5a that open upward and forward, and a plurality of second openings 5b that open upward. Through each of the first openings 5a, the first arm 31 of the key support mechanism 6 engages with the first support shaft 18a from the outside, and through each of the second openings 5b, the second arm 32 engages with the second support shaft 19a from the outside.

In addition, in the keyboard chassis 4, multiple chassis bodies 4a are connected to each other in a line in the left-right direction, and are screwed in a state in which they are placed on metal front rails 7, middle rails 8, and rear rails 9 that all extend in the left-right direction and are arranged at a predetermined distance from each other 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.

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 engage with the left and right engagement holes 11b, 11b of the chassis front part 11 while penetrating them, respectively.

The front of the white key 2a is provided with a key front connecting part 22 that is connected to the first arm 31 of the key support mechanism 6a at a predetermined position behind the upper limit position restricting part 21. This key front connecting part 22 has a connecting recess 22a that is U-shaped and has an elongated hole-like side that opens forward. A key side noise suppression member 20 is attached to this connecting recess 22a so as to cover its entire inner circumferential surface, and is used to suppress noise generated when a connecting shaft 35b of the first arm 31 (described later) slides within the connecting recess 22a.

Furthermore, the rear of the white key 2a is provided with a key rear connecting part 23 that is connected to the second arm 32 of the key support mechanism 6a. This key rear connecting part 23 has a plate-shaped connecting body part 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 engaging protrusions 23b, 23b that protrude coaxially from the left and right side surfaces of the connecting body part 23a. In addition, a tool insertion hole 24 is formed in the rear of the white key 2a, which penetrates in the up-down direction and 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 during maintenance of the keyboard device 1, etc.

On the other hand, the key support mechanism 6a has 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 composed of a resin molded product of a predetermined shape, such as by injection molding a predetermined resin material (e.g., polyacetal). The arm body 33 extends a predetermined length in the front-rear direction, and at its front end is provided a first arm front connecting part 35 that connects to the key front connecting part 22 of the white key 2a. The first arm front connecting part 35 has a box part 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 part 35a. The connecting shaft 35b is connected to the connecting recess 22a of the key front connecting part 22 of the white key 2a so as to be freely rotatable and freely slidable in the front-rear direction.

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 sides of the arm body 33. Both ends of this connecting shaft 37a engage with connecting recesses 45b, 45b of the second arm front connecting portion 45 of the second arm 32, which will be described later.

Two elongated plate-like weights 34, 34 are attached to the weight attachment section 38 at the rear of the arm body 33, sandwiching the weight attachment section 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 the arm body 33, and is formed into a predetermined shape by pressing a metal plate, etc.

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. This second arm 32 is shorter than the first arm 31 and extends a predetermined length in the front-to-rear direction. In addition, the second arm 32 has a C-shaped bearing portion 41 near the center in the longitudinal direction, with the side shape opening forward, and this bearing portion 41 rotatably engages with the second support shaft 19a in the keyboard chassis 4.

The rear of the second arm 32 is provided with a second arm rear connecting part 42 that is connected to the key rear connecting part 23 of the white key 2a. This second arm rear connecting part 42 is bifurcated and has two left and right connecting arms 43, 43 that extend parallel to each other for 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 hold the connecting body part 23a of the key rear connecting part 23 of the white key 2a from both the left and right sides, and each connecting hole 43a fits rotatably into the corresponding engaging protrusion 23b of the key rear connecting part 23.

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 of the first arm 31. This second arm front connecting part 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 has a U-shaped connecting recess 45b 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.

5(a) shows the black key 2b and its key support mechanism 6b in an enlarged view, and FIG. 5(b) shows them in an exploded view. 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. This front-side connecting part 26 has a connecting recess 26a whose side shape is an elongated hole and is formed in a U-shape that opens forward. In addition, 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 this extension part 26b functions as an upper limit position regulating part for the black key 2b. In the following explanation, 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 given the same reference numerals, and detailed explanations will be omitted.

The key support mechanism 6b that supports the black key 2b is constructed 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 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. 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.

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

When the front end of the white key 2a is pressed down by the player's finger in the released key state shown in FIG. 6(a), the front key connection part 22 of the white key 2a moves downward, causing the first arm 31 to rotate counterclockwise around the first support shaft 18a. In addition, with the above rotation of the first arm 31, the second arm front connection part 45, which engages with the connection shaft 37a of the first arm 31 via the connection recess 45b, moves upward. As a result, the second arm 32 rotates clockwise around the second support shaft 19a. Then, with this rotation of the second arm 32, the rear key connection part 23 connected via the second arm rear connection part 42 at its rear end is pulled down, and the rear end of the white key 2a moves downward.

When the first arm 31 rotates as described above, the box portion 35a of the first arm front connecting portion 35 moves downward, and the bottom wall of the box portion 35a presses the switch body 3b of the key switch 3 corresponding to the pressed key 2 from above. As a result, the electronic piano detects the 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.

When the white key 2a is pressed down as described above, as the first arm 31 rotates counterclockwise, the weight 34 of the first arm 31 tilts upward at the rear as shown in FIG. 6(b), and the rear end abuts against the first arm upper limit stopper 10a from below. This prevents the first arm 31 from rotating any further. 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 the white key 2a from being pressed down any further.

When the white key 2a is pressed as described above, it rotates around the virtual fulcrum P, which is located behind its rear end. The position of this virtual 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 located a predetermined key stroke (e.g., 10 mm) lower, and the rear end is located approximately half the distance of the key stroke (e.g., 5 mm) lower, compared to when the key is released as shown in FIG. 6(a).

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 the above, and the second arm 32 also rotates in the opposite direction to the above. As a result, the white key 2a rotates upward around the virtual fulcrum P. Then, a specific 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 regulating parts 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 released state.

The operation of the black key 2b when it is pressed is the same as 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. 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, so that the black key 2b rotates around the virtual fulcrum Q at the rear. The position of this virtual fulcrum Q is set so that the distance from the front end of the black key 2b is about twice the length of the black key 2 itself, for example, like the virtual fulcrum 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 about 1/2 the distance of the key stroke, compared to the key-released state shown in FIG. 7(a).

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 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.

Next, the main parts of the present invention will be described with reference to Figures 8 to 11. Figure 8 shows an enlarged view of the bearing portion 36 of the arm body 33 of the first arm 31 and the first support shaft 18a that supports it. Note that Figure 8 shows the guide groove 36b in a schematic manner, for example, being drawn slightly longer than it actually is, to make it easier to understand the configuration.

As mentioned above, the first support shaft 18a is integral with the chassis middle portion 12 (not shown in FIG. 8) of the keyboard chassis 4, extends horizontally, and has a circular cross section and a predetermined diameter D. The bearing portion 36 has a circular shaft hole 36a formed near the bottom surface of the arm body 33, and a guide groove 36b that opens into the bottom surface of the arm body 33, extends diagonally upward from there, and is connected to the shaft hole 36a.

The groove width W of the guide groove 36b is slightly smaller than the diameter D of the first support shaft 18a, and the diameter of the shaft hole 36a is set to be approximately the same as the diameter D of the first support shaft 18 so that it can rotatably fit onto the first support shaft 18a. In addition, the inclination angle A of the guide groove 36b with respect to the horizontal in the key-released state is preferably in the range of 45±15 degrees for reasons described below, and is set to approximately 45 degrees in the example of Figure 8.

With the above configuration, the first arm 31 is attached to the first support shaft 18a as follows. First, the first arm 31 is positioned as shown in FIG. 8(a), and then moved diagonally downward (in the direction of the arrow X) toward the first support shaft 18a, and the tip of the guide groove 36b is pressed against and engaged with the first support shaft 18a. After that, when the first arm 31 is further pressed in the same direction, the first arm 31 moves diagonally downward while being guided by the guide groove 36b in a state in which the narrow guide groove 36b is elastically pushed open by the first support shaft 18a. Then, when the guide groove 36b passes over the first support shaft 18a, the guide groove 36b elastically returns to its original position, and at the same time, the shaft hole 36a fits (snaps) into the first support shaft 18a. As a result, as shown in FIG. 8(b), the first arm 31 is attached to the first support shaft 18a via the shaft hole 36a and is supported so as to be freely rotatable.

As described above, the first arm 31 is snap-fitted onto the first support shaft 18a via the bearing portion 36. In addition, the guide groove 36b extends obliquely from the underside of the first arm 31 to the shaft hole 36a. For this reason, when an impact acts on the keyboard device 1 in the front-to-back or up-down directions, such as during product transportation, the direction of the resulting inertial force differs significantly from the direction of the guide groove 36b, dispersing the inertial force. As a result of the above, it is possible to effectively prevent the first arm 31 from coming off the first support shaft 18a when an impact acts.

For example, when an electronic piano including the keyboard device 1 of the embodiment is transported as a product, it is usually stored in a packaging box P made of cardboard or the like with the four corners of the electronic piano covered with cushioning material C such as polystyrene foam, as shown in FIG. 9. For this reason, impacts on the keyboard device 1 during transportation are often applied in the front-to-back direction (H) or the up-to-down direction (V).

When the impact on the keyboard device is in the front-to-back direction, in the keyboard device of Patent Document 1 mentioned above, the hammer is fitted into the support shaft from the front, and the direction of the inertial force due to the impact and the direction in which the hammer is fitted are nearly aligned, so there is a risk that the hammer will come off the support shaft. Also, when the impact on the keyboard device is in the up-down direction, in the keyboard device of Patent Document 2, the hammer is fitted into the support shaft from above, and the direction of the inertial force due to the impact and the direction in which the hammer is fitted are nearly aligned, so there is also a risk that the hammer will come off the support shaft.

In contrast, in the keyboard device 1 of this embodiment, as described above, when an impact is applied in the front-rear or up-down direction, the direction of the resulting inertial force is significantly different from the direction of the guide groove 36b, and as a result, the inertial force is dispersed, effectively preventing the first arm 31 from coming off the first support shaft 18a.

As shown in FIG. 9, when an impact acts on the keyboard device 1 in an oblique direction (I), the direction of the inertial force due to the impact may coincide with the direction of the guide groove 36b. In that case, however, the packaging box P will crush and absorb part of the impact, and the first arm upper limit stopper 10a against which the rotated first arm 31 abuts will bear part of the impact, so the first arm 31 will not come off.

Next, the uneven portion for removing the first arm 31 will be described with reference to Figures 10 and 11. As shown in Figure 10(a), this uneven portion 51 is formed on the arm body 33 (weight mounting portion 38) of the first arm 31. More specifically, as shown in Figure 10(b), the uneven portion 51 is integrally provided on the rear end of the upper surface of the arm body 33 and is composed of a protrusion 51a that protrudes upward over its entire width.

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

As described above, the first arm 31 is removed by rotating the rod-shaped tool R against the protrusion 51a formed on the top surface of the first arm 31 using the principle of a lever with the part S of the keyboard chassis 4 as the fulcrum. This makes it possible to easily remove the first arm 31, which is snap-fit and difficult to remove, from the first support shaft 18a without using a special tool.

The present invention is not limited to the above-described embodiment, and can be implemented in various ways. For example, in the embodiment, the inclination angle A of the guide groove 36b of the first arm 31 with respect to the horizontal in the key-released state is set to about 45 degrees, but it may be in the range of 45±15 degrees. This is because if the inclination angle A is greater than 60 degrees, the guide groove 36b becomes closer to the vertical, which results in insufficient dispersion of the inertial force when an impact in the up-down direction acts, and if the inclination angle A is smaller than 30 degrees, the guide groove 36b becomes closer to the horizontal, which results in insufficient dispersion of the inertial force when an impact in the front-rear direction acts. Therefore, if the inclination angle A is in the range of 45±15 degrees, the inertial force caused by the impact can be sufficiently dispersed, effectively suppressing the separation of the first arm 31, and the same effect can be obtained.

In the embodiment, the projection 51a shown in FIG. 10 (b) is provided as the uneven portion 51 for removing the first arm 31, but any configuration can be adopted as long as it is possible to engage the tool R and rotate the first arm 31. FIGS. 10 (c) and (d) show other examples of such uneven portions 51. In the example of (c), the uneven portion 51 is composed of a recess 51b formed over the entire width of the upper surface of the arm body 33, and in the example of (d), it is composed of a pair of notches 51c formed at a distance in the width direction of the upper surface of the arm body 33. In these configurations, as in the case of the projection 51a, the first arm 31 can be easily removed from the first support shaft 18a by engaging an appropriate tool R with the recess 51b or the notch 51c and rotating it.

Furthermore, the detailed configurations shown in the embodiment, such as the configuration and dimensional relationships of the bearing portion 36 of the first arm 31 shown in Figure 8, are merely examples and can be modified as appropriate within the scope of the spirit of the present invention.

1 Keyboard device 2 Key 2a White key 2b Black key 4 Keyboard chassis (chassis)
31 First arm (hammer)
33 Arm body of first arm (hammer)
36 Bearing portion 36a Shaft hole of bearing portion (shaft hole)
36b Guide groove of bearing portion (guide groove)
51: uneven portion 51a: protrusion 51b: recess 51c: notch D: diameter of first support shaft (diameter of support shaft)
W: Guide groove width A: Guide groove inclination angle

Claims (2)

A chassis,
A freely rotating key,
a hammer that is rotatably supported on a support shaft of the chassis and rotates in conjunction with the pressed key,
the hammer has a shaft hole into which the support shaft can be fitted, and a guide groove extending obliquely upward from a lower surface of the hammer to connect to the shaft hole, the guide groove having a groove width smaller than a diameter of the support shaft, and guiding the shaft hole to the support shaft when the hammer is attached ,
13. A keyboard device for a keyboard instrument , wherein said guide groove extends obliquely at an angle of 45±15 degrees with respect to the horizontal when said key is in a released state . 2. The keyboard device for a keyboard instrument according to claim 1 , wherein said hammer is formed with a projection and recess that engages with a tool for removing said hammer by moving said hammer obliquely upward from said support shaft.

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