Keyboard mechanism of a keyboard instrument

Abstract

The present invention provides a keyboard mechanism for a keyboard instrument that prevents the hammer from rotating too far down after it has rebounded from the hammer stopper following an upward rotation caused by pressing a key, thereby preventing a drop in sound immediately after pressing a key. [Solution] The device comprises a pivotable key 2 extending in the front-rear direction, an action unit 6 provided at its rear end which performs a predetermined operation in conjunction with pressing the key, a hammer 5 mounted on the hammer 5 which is driven upward via the action unit 6 when the key is pressed, and a key switch 7 for detecting key press information by being pressed from below by the hammer 5. The action unit 6 has a holder 51 fixed to the key 2, a repetition lever 52 and a jack 53 rotatably attached thereto, and a hammer height holding means 65a for holding the hammer 5, which has bounced back from the hammer stopper 38, at a predetermined height or higher.

Description

TECHNICAL FIELD

[0001] The present invention relates to a keyboard device for keyboard instruments such as electronic pianos, and particularly to a keyboard device for keyboard instruments that achieves the same action as a grand piano.

BACKGROUND ART

[0002] Conventionally, as this type of keyboard device, for example, the one described in Patent Document 1 already filed by the present applicant is known. This keyboard device has a key that extends in the front-rear direction and is swingable about a fulcrum at the center in the length direction, and an action unit that performs a predetermined operation in conjunction with key depression is attached to the rear portion of the key. This action unit includes a holder attached to the key, and a repetition lever and a jack rotatably supported by the holder. The repetition lever is formed in a predetermined shape extending in the front-rear direction, is rotatably supported by the holder via a fitting hole provided in the front portion and penetrating in the left-right direction, and is provided with a jack guide hole penetrating in the up-down direction behind the fitting hole. On the other hand, the jack is rotatably supported by the holder via a fitting hole provided in the lower portion and penetrating in the left-right direction, and has a hammer lifting portion and a rear arm extending upward and rearward respectively from the fitting hole, and the hammer lifting portion is engaged with the jack guide hole of the repetition lever in a state of being inserted from below.

[0003] Further, a hammer support is disposed on the rear side of the key, and a hammer extending in the front-rear direction is supported at its rear end by the hammer support so as to be rotatable in the up-down direction. The hammer also has a hammer protruding portion protruding downward at its rear portion, and the hammer protruding portion is placed on the upper surface of the repetition lever above the jack guide hole.

[0004] In the keyboard mechanism configured as described above, when a key is pressed, the holder at the rear end of the key rises, and the repetition lever and jack move upward together with it. Consequently, the repetition lever first pushes up the hammer via the hammer projection, causing it to rotate upward. Next, the rear end of the repetition lever locks into place by contacting the repetition stopper of the hammer support from below, causing the jack to push up the hammer projection via the hammer thrusting part, causing the hammer to rotate upward. When the hammer has rotated to just before pressing the key switch, the rear end of the jack's rear arm contacts the jack stopper of the hammer support from below, causing the hammer thrusting part of the jack to disengage from the hammer projection (escapement). This escapement of the jack releases the hammer from the action unit, allowing it to rotate freely, press the key switch, and produce a piano sound.

[0005] The hammer, having rotated upward, strikes a hammer stopper located on the hammer support from below, preventing further rotation. The hammer then bounces back from the hammer stopper and rotates downward, engaging with a back check located on the holder, preventing further rotation and stopping it. Subsequently, when the finger is released from the pressed key, the holder at the rear end of the key descends, and the repetition lever and jack move downward together with it. The repetition lever and jack are then biased by the repetition spring and jack spring, respectively, and return to their original positions in the released state. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2024-93320 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In the above keyboard mechanism, when a key is pressed, if the hammer, which bounces back from the hammer stopper and rotates downward, rotates to a position close to the height it is at when the key is released, the key switch turns OFF, detecting a stop in sound. As a result, contrary to the performer's intention, the piano sound may stop immediately after pressing the key, causing a drop in sound. In particular, the harder the key is struck, the stronger the rebound of the hammer from the hammer stopper becomes, which tends to lower the height of the hammer that engages with the back check, making the above drop in sound more likely to occur. When such a drop in sound occurs, the playability deteriorates.

[0008] The present invention was made to solve the above-mentioned problems, and aims to provide a keyboard device for a keyboard instrument that can prevent the hammer from rotating too far down after it rebounds from the hammer stopper and rotates downward following an upward rotation caused by pressing a key, thereby preventing a drop in sound immediately after pressing a key. [Means for solving the problem]

[0009] To achieve the above objective, the invention according to claim 1 comprises: a key extending a predetermined length in the front-rear direction and pivotable with a pivot point near the center in the longitudinal direction; an action unit provided at the rear of the key and performing a predetermined operation in conjunction with the pressing of the key; a hammer support positioned at the rear of the key; a hammer extending a predetermined length in the front-rear direction and rotatably supported at its rear end via a hammer support shaft extending in the left-right direction of the hammer support, and mounted on the action unit via a hammer projection provided so as to protrude downward immediately in front of the hammer support shaft, and driven upward via the action unit in conjunction with the pressing of the key; and a key switch for detecting key pressing information by being pressed from below by the hammer, wherein the action unit comprises: a holder fixed to the rear end of the key; a hammer projection mounted on an upper surface formed in a predetermined shape extending in the front-rear direction and rotatably attached to the holder, with a jack guide hole that penetrates in the vertical direction and extends in the front-rear direction, and which rises in conjunction with the pressing of the key, thereby pushing up the hammer via the hammer projection and rotating it upward The hammer support has a lever, a hammer thrusting section extending vertically, and a rear arm extending rearward from near the lower end of the hammer thrusting section, and is rotatably mounted on a holder. The upper end of the hammer thrusting section is inserted from below into the jack guide hole of the repetition lever and engages so as to be movable in the front-rear direction. The hammer thrusting section pushes the hammer upward via the hammer projection as the repetition lever rises in conjunction with the pressing of the key, and the jack rotates it upward. The hammer support is located in the middle of the hammer being pushed up by the repetition lever. The action unit includes a repetition stopper that locks the repetition lever by contacting the rear end of the repetition lever from below, a jack stopper that locks the jack by contacting the rear end of the rear arm from below while the hammer is being thrust upward by the jack, and rotates the jack using the contacting rear end of the rear arm as a pivot point, thereby disengaging the hammer thrust portion of the jack from the hammer projection of the hammer, and a hammer stopper that the hammer, which rotates upward when the key is pressed, contacts to prevent further rotation.The device is further characterized by comprising a hammer height holding means for maintaining the height at which the hammer projection of the hammer, which has rebounded from the hammer stopper and rotated downward, contacts the repetition lever from above, above a predetermined height at which the hammer presses the key switch until the pressed key is released.

[0010] In this configuration, an action unit is provided at the rear of the key, and a hammer, whose rear end is rotatably supported on the hammer support shaft of the hammer support, is mounted on the action unit via a hammer projection immediately in front of the hammer support shaft. This action unit comprises a holder fixed to the rear end of the key, and a repetition lever and a jack rotatably attached to this holder. The hammer thrust portion of the jack is inserted from below into the jack guide hole of the repetition lever and engages with it so as to be movable in the front-rear direction, and the hammer is mounted on the upper surface of the repetition lever, where the jack guide hole is provided, via a hammer projection.

[0011] When the key is pressed, the front end of the key is pushed down, causing the rear end of the key to move upward together with the holder of the action unit. Consequently, the repetition lever of the action unit rises, pushing up the hammer via the hammer projection and rotating it upward. While the hammer is being pushed up by the repetition lever, the rear end of the repetition lever contacts the repetition stopper of the hammer support from below, locking the repetition lever in place. After the repetition lever is locked, the hammer-pushing portion of the jack pushes up the hammer via the hammer projection and rotates it further upward. While the hammer is being pushed up by the jack, the rear end of the jack's rear arm contacts the jack stopper of the hammer support from below, locking the jack and rotating the jack using the contacting rear end of the rear arm as a pivot point, thereby disengaging the hammer-pushing portion of the jack from the hammer projection. In other words, the jack is disengaged from the hammer. This escape of the jack releases the hammer from the action unit and key, allowing it to rotate freely upwards. This escape of the jack creates a click sensation due to a sudden increase or decrease in the key's touch weight, providing the player with a let-off sensation. Furthermore, the upward rotation of the hammer presses the key switch from below, detecting a key press. Based on this detected key press information, the keyboard instrument produces sound.

[0012] Furthermore, according to the above configuration, the hammer that rotates upward comes into contact with the hammer stopper of the hammer support, preventing further rotation. The hammer then bounces back from the hammer stopper and rotates downward, with the hammer projection coming into contact with the repetition lever from above. In this case, the height at which the hammer projection comes into contact with the repetition lever from above is maintained by the hammer height holding means at or above a predetermined height at which the hammer presses the key switch until the pressed key is released. As a result, unlike conventional keyboard devices, the hammer that bounces back from the hammer stopper and rotates downward when a key is pressed can be prevented from going too low, and as a result, it is possible to prevent the sound from cutting off immediately after pressing the key.

[0013] The invention according to claim 2 is characterized in that, in the keyboard device of a keyboard instrument described in claim 1, the hammer height holding means is provided on a holder and consists of a stopper that prevents the rotation of the repetition lever by contacting the front end of the repetition lever from below.

[0014] In this configuration, the hammer height holding means is comprised of a stopper provided on the holder, and the rotation of the repetition lever is prevented when the front end of the repetition lever contacts the stopper from below. When the hammer's protrusion, which has bounced back from the hammer stopper and rotated downward, contacts the repetition lever from above, the height at which it contacts the stopper can be easily maintained at or above the predetermined height. Therefore, with this configuration, the hammer height holding means can be easily provided on the holder and configured with a stopper that prevents the rotation of the repetition lever. [Brief explanation of the drawing]

[0015] [Figure 1] This is a perspective view showing the keyboard mechanism of an electronic piano to which a keyboard mechanism according to one embodiment of the present invention is applied, where (a) shows the keyboard mechanism viewed from the front and diagonally above, and (b) shows the keyboard mechanism viewed from the rear and diagonally above. [Figure 2] (a) and (b) correspond to Figures 1(a) and (b), respectively, and show a magnified view of the rightmost part of the keyboard mechanism. [Figure 3] (a) shows the keyboard device shown in Figure 1(a), with the right-side metal fittings omitted and one white key and one black key remaining on the far right. (b) is a right-side view of the keyboard device. [Figure 4] (a) is a perspective view showing the action unit assembled to the key and the hammer mounted on top thereof, and (b) is a perspective view showing the key, action unit, and hammer disassembled. [Figure 5] This is a perspective view showing the hammer support; (a) is an external view, and (b) is a view showing a portion of it cut out. [Figure 6] This diagram shows a hammer support, with (a) being a front view and (b) being a cross-sectional view along line AA. [Figure 7] This is a magnified perspective view of the hammer and action unit, with (a) showing the action unit with all its components assembled and (b) showing the action unit with all its components disassembled. [Figure 8] This is a right side view of the hammer. [Figure 9] This is a right side view showing the holder. [Figure 10] This is a right side view showing the repetition lever, with (a) showing the repetition lever with the bushing attached and (b) showing the repetition lever with the bushing removed. [Figure 11] This diagram shows a magnified view of the bushing for the repetition lever, with (a) being a front view and (b) being a perspective view. [Figure 12] This is a right-side view of the jack, with (a) showing the jack with the bushing attached and (b) showing the jack with the bushing removed. [Figure 13] This diagram shows a magnified view of the bushing for the jack, with (a) being a front view and (b) being a perspective view. [Figure 14] This is an enlarged view of the right side of the rear end of the keyboard mechanism. [Figure 15] This is an explanatory diagram sequentially illustrating the operations of the action unit and the hammer when a key is pressed, where (a) shows the key released state, and (b) shows the state where the repetition lever abuts against the repetition stopper when the key is pressed. [Figure 16] This is an explanatory diagram following Fig.15, where (a) shows the state where the jack abuts against the jack stopper, and (b) shows the state where the hammer lifting portion of the jack is disengaged from the hammer projection. [Figure 17] This is an explanatory diagram following Fig.16, where (a) shows the state where the front end of the key is pressed down to the lowest position and the hammer abuts against the hammer stopper, and (b) shows the state where the hammer rebounds from the hammer stopper and is supported by the repetition lever. [Figure 18] This is an explanatory diagram following Fig.17, where (a) shows the state where the pressed key is slightly returned so that the hammer lifting portion of the jack wraps around below the hammer projection, and (b) shows the state where the key returns to the original key released state. [Mode for Carrying Out the Invention]

[0016] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Fig.1 shows a keyboard device of an electronic piano to which the keyboard device according to one embodiment of the present invention is applied and from which an exterior case is omitted, where (a) shows the state when the keyboard device is viewed from the front diagonally above, and (b) shows the state when the keyboard device is viewed from the rear diagonally above. Further, Fig.2(a) and (b) correspond to Fig.1(a) and (b) respectively, and show the right end portion of the keyboard device in an enlarged manner. Furthermore, Fig.3(a) shows a state where one white key and one black key at the right end are left remaining in the keyboard device shown in Fig.1(a), and (b) is a right side view of the keyboard device.

[0017] As shown in the figures above, the keyboard device 1 includes a number of keys 2 (88 in Figure 1) arranged in the left-right direction of the electronic piano (52 white keys, 36 black keys), a keyboard chassis 3 that supports these keys 2, a hammer support 4 connected to the rear end of the keyboard chassis 3, a hammer 5 provided for each key 2 and rotatably supported by the hammer support 4, an action unit 6 provided at the rear end of the key 2 that drives the hammer 5 upward when the key is pressed, and a key switch 7 for detecting key press information. In the following description, when distinguishing between white keys and black keys, the keys 2 will be referred to as "white key 2a" and "black key 2b," respectively, and when not distinguishing between them, they will simply be referred to as "key 2."

[0018] As shown in Figure 3(a), the keyboard chassis 3 is assembled in a grid pattern from three support rails 10, consisting of a front rail 11, a middle rail 12, and a rear rail 13, all of which extend in the left-right direction and are spaced apart from each other in the front-back direction (left-right direction in Figure 3(b)), and a plurality of reinforcing ribs 14 (only two are shown in Figure 3(a)) that extend in the front-back direction and are spaced apart from each other in the left-right direction. These support rails 10 and reinforcing ribs 14 are made of sheet metal formed into predetermined shapes, for example by pressing and bending, and are connected to each other by screws.

[0019] The front rail 11 has a horizontal top plate portion 11a, a front plate portion 11b that bends downward at a right angle from the front end of the top plate portion 11a, and a bottom plate portion 11c that bends backward at a right angle from the lower end of the front plate portion 11b. The reed front 15 is fixed to the underside of the top plate portion 11a by screws or the like. The reed front 15 is formed in the shape of a thick plate made of synthetic resin and extends in the left-right direction across the entire length of the front rail 11. Numerous front pins 16 are erected on the reed front 15 at front and rear positions corresponding to the white keys 2a and black keys 2b, passing through the top plate portion 11a of the front rail 11 and arranged in a left-right direction.

[0020] The central rail 12 has a horizontal reed mounting section 12a, the front and rear ends of which are bent upward at right angles. The reed 17 is mounted on the reed mounting section 12a and fixed in place by screws or the like. The reed 17 is formed in the shape of a thick plate made of synthetic resin and extends in the left-right direction across the entire central rail 12. Numerous balance pins 18 are erected on the reed 17 in a left-right direction at front and rear positions corresponding to the white keys 2a and black keys 2b.

[0021] The rear rail 13 has an upward-opening recess 13a in which the lower part of the hammer support 4 and the keyboard cushion 91 (described later) are housed and fixed, and a connecting portion 13b that bends at a right angle from the upper end of the front plate portion of the recess 13a and extends forward, to which the rear ends of each rib 14 are connected.

[0022] Figure 4(a) shows the action unit 6 assembled to the key 2 (white key 2a in the figure) and the hammer 5 placed on top of it, and Figure 4(b) shows the key 2, action unit 6 and hammer 5 disassembled. As shown in these figures, the key 2 has a wooden key body 21 that extends a predetermined length in the front-to-back direction and has a rectangular cross-section, and a synthetic resin key cover 22 that is bonded to the upper surface and front of the front half of the key body 21. A balance pin hole 23 that penetrates vertically is formed near the center of the length of the key body 21, and the key 2 is pivotably supported by a balance pin 18 erected in the reed 17 via this balance pin hole 23.

[0023] The balance pin hole 23 described above is formed as a nearly circular hole near the bottom surface of the key body 21, and the entire upper part connected to the hole is formed as an elongated hole extending in the longitudinal direction of the key body 21. Furthermore, felt 23a is provided on the left and right inner surfaces of the balance pin hole 23 to allow smooth sliding against the balance pin 18 when the key 2 swings. In addition, a cushion 20 is attached to the rear side of the balance pin hole 23 on the top surface of the key body 21, and this cushion 20 prevents the front end of the hammer 5 from directly hitting the key 2 during maintenance, etc.

[0024] Furthermore, a front pin hole 24 (see Figure 3(b)) that opens downward is formed at a predetermined position on the front of the key body 21. This front pin hole 24 engages with a front pin 16 erected on the reed front 15, thereby preventing the key 2 from swinging in the left-right direction.

[0025] Figures 5 and 6 show the hammer support 4. As shown in these figures, the hammer support 4 is made of molded parts made of synthetic resin, and multiple molded parts for, for example, one octave worth are connected to each other in the left-right direction and screwed to the rear rail 13 of the keyboard chassis 3. The hammer support 4 consists of a hammer support part 31 that rises upright from near the rear rail 13 and a switch mounting part 32 that extends diagonally upward from its upper end. A hammer support shaft 33 is provided at the upper end of the hammer support part 31 to rotatably support each hammer 5.

[0026] Furthermore, the hammer support 4 has multiple partition walls 34 that separate adjacent hammers 5 at predetermined intervals from each other in the left-right direction, and the hammer support shaft 33 extends in the left-right direction between adjacent partition walls 34, 34. As shown in an enlarged view in Figure 6(b), the hammer support shaft 33 has a so-called oval cross-sectional shape, with two cutouts at the front and back of a circle centered on the axis of the hammer support shaft 33.

[0027] Specifically, the outer surface of the hammer shaft 33 is composed of a pair of upper and lower curved portions 33a, 33a and a pair of front and rear flat portions 33b, 33b extending between these curved portions 33a, 33a. In the hammer shaft 33 configured in this way, the upper and lower curved portions 33a, 33a are set in the shape of an arc with a diameter of length L1, while the distance between the front and rear flat portions 33b, 33b is set to a length L2 that is shorter than the aforementioned length L1.

[0028] Furthermore, as shown in Figures 1 to 3, a key switch 7 is attached to the switch mounting portion 32 of the hammer support 4. This key switch 7 consists of a switch board 7a made of a printed circuit board and a switch body 7b made of a rubber switch attached to the hammer 5 side of the switch board 7a for each key 2.

[0029] Furthermore, as shown in Figures 5 and 6, a repetition stopper 35 is provided on the rear side of the hammer support 4, diagonally below and behind the hammer pivot shaft 33, to which the repetition lever 52 of the action unit 6 (described later) will strike and lock when pressed. This repetition stopper 35 is inclined downwards and forwards and has a contact surface 35a against which the repetition lever 52 strikes. A cushion such as felt is attached to this contact surface 35a to suppress noise and vibration when the repetition lever 52 strikes.

[0030] Furthermore, on the rear side of the hammer support 4, below the repetition stopper 35, there is a jack stopper 36 that the jack 53 of the action unit 6 (described later) contacts and locks when pressed. Similar to the repetition stopper 35 described above, this jack stopper 36 is inclined downwards and has a contact surface 36a that the jack 53 contacts. A cushion such as felt is also attached to this contact surface 36a to suppress noise and vibration when the jack 53 makes contact.

[0031] Furthermore, as shown in Figures 1 to 3, a hammer stopper 38 is provided at the upper front end of the hammer support 4. This stopper 38 contacts the hammer 5 from below when the hammer 5 rotates upward, preventing further rotation. The hammer stopper 38 extends horizontally across all hammer supports 4, has a rectangular cross-section, and is made of a cushion with a predetermined thickness.

[0032] As described above, the hammer supports 4 are arranged in a row in the left-right direction (for example, eight units), and their lower ends are connected to the rear rail 13. In addition, predetermined parts are supported by multiple metal fittings, which will be described later.

[0033] Specifically, as shown in Figures 1 and 2, all hammer supports 4 are supported by an upper rail 101 that extends across the entire left-right direction of the keyboard device 1 and connects the upper ends on the rear side of each hammer support 4, an upper front rail 102 that connects the upper ends on the front side of each hammer support 4, two left and right side plate fittings 103, 103 that are positioned at both ends of the keyboard device 1 and connect the rear rail 13, upper rail 101, and upper front rail 102 to each other by screw fastening, and a plurality of connecting fittings 104 (seven in Figure 1(b)) that extend vertically, are positioned spaced apart from each other in the left-right direction and connect the rear rail 13 and the upper rail 101. As a result, all hammer supports 4 can be held firmly and stably, and deformation and vibration of each hammer support 4 can be prevented even when the hammer 5 strikes the hammer stopper 38 of the hammer support 4 hard when a key is pressed.

[0034] Figure 7 shows the hammer 5 and the action unit 6, where (a) shows the action unit 6 assembled and (b) shows the action unit 6 disassembled. Figure 8 is a right side view of the hammer 5. As shown in these figures, the hammer 5 has an arm-shaped hammer body 41 that extends a predetermined length in the front-rear direction, and two weight plates 42, 42 attached to the front ends of its left and right sides. The hammer body 41 is made of synthetic resin, and the weight plates 42 are made of a metal material such as iron with a relatively high specific gravity.

[0035] The rear end of the hammer body 41 is provided with an engaging portion 43 that engages with the hammer support shaft 33 of the hammer support 4. This engaging portion 43 has an arc-shaped shaft hole 44 that penetrates in the left-right direction and has a C-shaped side profile, and its opening is formed to widen outward. The shaft hole 44 has a diameter slightly larger than the diameter (length L1) of the upper and lower curved portions 33a, 33a of the hammer support shaft 33, and the width L3 of the opening is slightly larger than the length L2 between the front and rear flat portions 33b, 33b of the hammer support shaft 33 and smaller than the aforementioned length L1. The hammer 5 is detachably attached to the hammer support shaft 33 of the hammer support 4 through the opening of the shaft hole 44, and is rotatably supported by the hammer support 4 when the shaft hole 44 fits onto the hammer support shaft 33.

[0036] Furthermore, a switch pressing portion 45 and a hammer protrusion portion 46 are provided above and below the shaft hole 44 at the rear of the hammer 5. The upper surface of the switch pressing portion 45 is formed flat, and when the hammer 5 rotates upward, it presses the switch body 7b of the key switch 7, thereby detecting the key press information of the key 2 corresponding to the hammer 5.

[0037] On the other hand, the hammer projection 46 corresponds to the shank roller in the hammer of a grand piano. This hammer projection 46 is constructed by attaching a roller bush 49 made of an elastic material to a projection body 48 which is molded integrally with the hammer body 41.

[0038] Then, in the unlocked state, the hammer projection 46 is placed on the hammer mounting portion 74 of the repetition lever 52 of the action unit 6, which will be described later.

[0039] Next, the action unit 6 will be described. As shown in Figure 7, the action unit 6 comprises a holder 51 fixed to the rear end of the key 2, a repetition lever 52 and a jack 53 rotatably attached thereto, and a repetition spring 54 and a jack spring 55, both made of coil springs, which bias these to rotate in a predetermined direction.

[0040] Figure 9 shows a right side view of the holder 51. As shown in Figure 9 and Figure 7, the holder 51 is made of synthetic resin and is a molded product of a predetermined shape that extends in the front-rear direction. The holder 51 includes a key mounting portion 61 provided at the front and fixed to the rear end of the key 2, a repetition support shaft 63 provided at the upper end near the center in the front-rear direction and rotatably supports the repetition lever 52, and a jack support shaft 64 provided at the rear end and rotatably supports the jack 53.

[0041] The key mounting portion 61 has a U-shaped side profile formed by an upper wall 61a, a rear wall 61b, and a lower wall 61c, with the left ends of these walls connected by a left side wall 61d. When the holder 51 is attached to the rear end of the key 2, the upper wall 61a and left side wall 61d of the holder 51 are fixed by adhesive in contact with the upper and left sides of the rear end of the key body 21, respectively, and staples (not shown) are driven in from above the upper wall 61a and to the left of the left side wall 61d of the holder 51. In this way, the holder 51 is firmly fixed to the rear end of the key body 21.

[0042] Both the repetition shaft 63 and the jack shaft 64 are formed in a cylindrical shape with a predetermined diameter and protrude to the right by a predetermined length. Furthermore, the repetition shaft 63 is formed at a predetermined position higher than the jack shaft 64.

[0043] Furthermore, the holder 51 is provided with a repetition spring locking portion 65 at a predetermined position in front of the repetition support shaft 63, which locks the upper end of the repetition spring 54. This repetition spring locking portion 65 is formed in a U-shape with a side shape that opens downwards, and is configured to hold the upper end of the repetition spring 54 immovably. In addition, the lower end portion 65a (hammer height holding means, stopper) of the repetition spring locking portion 65 also functions as a stopper, preventing further rotation of the repetition lever 52 when it rotates during keying by its front end contacting it from below.

[0044] Furthermore, the holder 51 is provided with a jack spring locking portion 66 located between the repetition support shaft 63 and the jack support shaft 64, at a predetermined position in front of the jack support shaft 64, which locks the upper end of the jack spring 55. Similar to the repetition spring locking portion 65 described above, this jack spring locking portion 66 is formed in a U-shape with a side shape that opens downwards, and is configured to hold the upper end of the jack spring 55 immovably. In addition, the lower end portion 66a of the jack spring locking portion 66 also functions as a stopper, preventing further rotation of the jack 53 when it rotates during keying by its front end contacting it from below.

[0045] Furthermore, the lower rear portion of the holder 51 is provided with a contact projection 67 that protrudes slightly downward and, when the key is released, abuts against the keyboard cushion 91 (described later) from above. This contact projection 67 has an inclined surface 67a at its bottom that slopes downward at a predetermined angle relative to the horizontal.

[0046] Figure 10 shows a right side view of the repetition lever 52, where Figure 10(a) shows the state with the bush 77 for the repetition lever (described later) attached to the repetition lever 52, and Figure 10(b) shows the state with the bush 77 removed from the repetition lever 52. The repetition lever 52 is made of synthetic resin and is a molded product of a predetermined shape formed to extend in the front-rear direction. This repetition lever 52 has a fitting hole 71 that penetrates in the left-right direction and is rotatably fitted onto the repetition support shaft 63 of the holder 51, a front arm 72 that extends forward from the lower side of the fitting hole 71, and a hammer mounting arm 73 that is formed to extend rearward from the rear side of the fitting hole 71 and on which the hammer 5 is mounted and which the jack 53 engages.

[0047] The front arm 72 is configured so that the bush 77 for the repetition lever can be easily and securely attached. Specifically, as shown in Figure 10(b), the front arm 72 has a horizontal upper surface and a two-tiered bottom, with the height decreasing towards the tip (left end of Figure 10(b)). The tip of the front arm 72 is also provided with a return 72a that protrudes upward and holds the bush 77 attached to the front arm 72 in a secure position.

[0048] Figure 11 shows a magnified view of the bushing 77 for the repetition lever, with (a) being a front view and (b) being a perspective view. As shown in these figures, the bushing 77 is made of an elastic soft resin and is a molded product with a substantially T-shaped side profile. The bushing 77 has a mounting hole 77a that penetrates in the front-rear direction and is attached to the front arm 72 of the repetition lever 52 when the front arm 72 is inserted through it. The vertical height dimension of this mounting hole 77a is the same as that of the front arm 72 near its center in the longitudinal direction.

[0049] Furthermore, a locking projection 78 is provided in the center of the upper surface of the bush 77, which protrudes upward and engages with the lower end of the repetition spring 54. The upper half of this locking projection 78 has a diameter slightly larger than the inner diameter of the repetition spring 54, while the lower half has a diameter smaller than the inner diameter of the repetition spring 54. In addition, the front and rear portions of the locking projection 78 are slightly cut vertically. Moreover, on the lower surface of the bush 77, a plurality (three in this embodiment) of downward projections 77b are arranged side by side in the left-right direction, protruding downward and extending in the front-rear direction.

[0050] When attaching the bush 77 configured as described above to the front arm 72 of the repetition lever 52, the front arm 72 is inserted into the mounting hole 77a of the bush 77, and as shown in Figure 10(a), the return 72a of the front arm 72 is exposed to the outside on the opposite side of the mounting hole 77a of the bush 77 from the insertion side. In this case, the lower end of the bush 77 on the insertion side of the mounting hole 77a abuts against the stepped portion 72b at the bottom of the front arm 72 as shown in Figure 10(b), preventing further insertion of the bush 77 into the front arm 72. As a result, the bush 77 can be easily attached to the front arm 72 and is securely attached in a way that prevents it from coming loose.

[0051] Furthermore, when attaching the repetition spring 54 to the upper locking projection 78 of the bush 77 described above, the upper half of the locking projection 78 is pressed inward from below against the lower end of the repetition spring 54. This allows the lower end of the repetition spring 54 to be easily and securely attached to the locking projection 78.

[0052] As shown in Figure 10(a), the hammer mounting arm 73 of the repetition lever 52 has a side shape that includes a hammer mounting portion 74 that extends a predetermined length diagonally upward and rearward from the fitting hole 71, and an extension portion 75 that extends diagonally downward and rearward from the rear end of the hammer mounting portion 74 and further rearward. In addition, the hammer mounting arm 73 has a jack guide hole 73a that penetrates in the vertical direction and extends in the front-rear direction across the hammer mounting portion 74 and the extension portion 75.

[0053] Furthermore, the rear end of the repetition lever 52 is provided with a projection 76 that protrudes upward. When the repetition lever 52 is rotated, the projection 76 contacts the contact surface 35a of the repetition stopper 35 in the hammer support 4 from below.

[0054] Figure 12 shows a right side view of the jack 53, where Figure 12(a) shows the jack 53 with the bush 87 for the jack (described later) attached, and Figure 12(b) shows the jack 53 with the bush 87 removed. The jack 53 is made of synthetic resin and is composed of a molded product of a predetermined shape. The jack 53 has a fitting hole 81 that penetrates in the left-right direction and is rotatably fitted onto the jack support shaft 64 of the holder 51, a front arm 82 that extends forward from the front side of the fitting hole 81, a hammer thrusting portion 83 that extends upward for a predetermined length from the top side of the fitting hole 81, and a rear arm 84 that extends rearward from the rear side of the fitting hole 81.

[0055] The front arm 82 of the jack 53 is configured so that the bush 87 for the jack can be easily and securely attached. Specifically, as shown in Figure 12(b), the front arm 82 has its upper and lower surfaces parallel to each other, and its tip is provided with a return 82a that protrudes downward and holds the bush 87 attached to the front arm 82 in a secure position.

[0056] Figure 13 shows a bushing 87 for the jack, with (a) being a front view and (b) being a perspective view. As shown in these figures, the bushing 87 is made of an elastic soft resin and is a molded product with a horizontally elongated rectangular shape on its side. The bushing 87 has a mounting hole 87a that penetrates in the front-to-back direction and is attached to the front arm 82 of the jack 53 when the front arm 82 is inserted through it. The vertical height dimension of this mounting hole 87a is the same as the height dimension between the top and bottom surfaces of the front arm 82.

[0057] Furthermore, the upper surface of the bush 87 is provided with a locking projection 88 that protrudes upward and engages with the lower end of the jack spring 55. This locking projection 88 has a truncated cone-shaped head located slightly higher than the upper surface of the bush 87. The upper end of this head has a diameter smaller than the inner diameter of the jack spring 55, while the lower end has a diameter slightly larger than the inner diameter of the jack spring 55. In addition, the front and rear portions of the locking projection 88 are slightly cut vertically. Moreover, the lower surface of the bush 87 has multiple (two in this embodiment) downward projections 87b that protrude downward and extend in the front-rear direction, arranged side by side in the left-right direction.

[0058] When attaching the bush 87 configured as described above to the front arm 82 of the jack 53, the front arm 82 is inserted into the mounting hole 87a of the bush 87, and as shown in Figure 12(a), the return 82a of the front arm 82 is exposed to the outside on the opposite side of the mounting hole 87a of the bush 87 from the insertion side. In this case, the lower end of the bush 87 on the insertion side of the mounting hole 87a abuts against the stepped portion 82b at the bottom of the front arm 82 as shown in Figure 12(b), preventing further insertion of the bush 87 into the front arm 82. As a result, the bush 87 can be easily attached to the front arm 82 and is securely attached in a way that prevents it from coming loose.

[0059] Furthermore, when attaching the jack spring 55 to the upper locking projection 88 of the bush 87 described above, the head of the locking projection 88 is pressed inward from below against the lower end of the jack spring 55. This allows the lower end of the jack spring 55 to be easily and securely attached to the locking projection 88.

[0060] As shown in Figure 12(a), the hammer thrusting portion 83 extends diagonally upward and forward at a predetermined angle, relative to the front arm 82 and rear arm 84, which extend almost horizontally in the front-rear direction. The upper end of the hammer thrusting portion 83 is formed to be narrower in the front-rear direction than the portion below it. The rear end of the rear arm 84 is provided with a projection 84a that protrudes upward. When the jack 53 rotates, the projection 84a contacts the contact surface 36a of the jack stopper 36 in the hammer support 4 from below.

[0061] Figure 14 shows an enlarged right side view of the rear end of the keyboard device 1. As shown in the figure, in the action unit 6 configured as described above, the hammer thrust portion 83 of the jack 53 is engaged with the jack guide hole 73a of the repetition lever 52 when inserted from below. The repetition lever 52 is biased downward by the repetition spring 54 via the bush 77 at its front arm 72, while the jack 53 is biased downward by the jack spring 55 via the bush 87 at its front arm 82. As a result, the repetition lever 52 and the jack 53 are biased in a counterclockwise direction in Figure 14, around the repetition support shaft 63 and the jack support shaft 64, respectively.

[0062] Furthermore, as shown in Figure 14, a keyboard cushion 91 is provided in the receiving recess 13a of the rear rail 13 of the keyboard chassis 3 to support the rear end of the key 2 from below when the key is released. This keyboard cushion 91 is made of a molded product made of synthetic resin, and, similar to the hammer support 4 described above, multiple molded products for, for example, one octave are connected to each other in the left-right direction and screwed into the receiving recess 13a of the rear rail 13. The keyboard cushion 91 also has an inclined surface 91a at its upper end that slopes downward at a predetermined angle to the horizontal. A cushion 92 extending in the left-right direction, with a horizontally elongated rectangular cross-section and a predetermined thickness, is attached to this inclined surface 91a by adhesive. When the key is released, the contact projection 67 of the holder 51 of the action unit 6 of the key 2 rests on the cushion 92 on the keyboard cushion 91 from above.

[0063] Here, we will describe the repetition spring 54 and jack spring 55 in the action unit 6 provided for each key 2. As mentioned above, the keyboard device 1 has 88 keys 2, and is divided into low register, mid register, upper mid register, and high register, in order from the low register to the high register. Specifically, all 88 keys are numbered 1 to 88 from the low register to the high register, and the keys 2 in each register are generally divided as follows. Low register: Key No. 1-15 Mid-range: Key No. 16-32 Mid-range: Key No. 33-63 High register: Key No. 64-88

[0064] In the four distinct ranges described above, the repetition springs 54 in the action unit 6 are set as follows: For example, the spring constant of the repetition spring 54 in the action unit 6 for the key 2 corresponding to the lower range is set 10% higher than the spring constant of the repetition spring 54 in the action unit 6 for the key 2 corresponding to the middle range (a predetermined reference range), the spring constant of the repetition spring 54 in the action unit 6 for the key 2 corresponding to the middle range is set 5% higher, and the spring constant of the repetition spring 54 in the action unit 6 for the key 2 corresponding to the upper range is set 10% lower. This ensures that hammers with different weights for each range are reliably lifted when the key is released, resulting in a touch and repetition performance equivalent to that of a grand piano.

[0065] The spring constant settings described above are just examples. For the repetition spring 54 in the mid-range, the spring constant for the lower-range should be set 0-10% larger, and the spring constant for the higher-range should be set 0-10% smaller. By precisely setting the spring constant of the repetition spring 54 for each range in this way, the effects and benefits described above can be obtained more reliably.

[0066] Furthermore, in each action unit 6, the spring constant of the repetition spring 54 (hereinafter referred to as "spring constant K1") is set to be greater than the spring constant of the jack spring 55 (hereinafter referred to as "spring constant K2"). More specifically, the spring constant K2 of the jack spring 55 has the minimum value necessary to rotate the escaped jack 53 back to its original position, while the spring constant K1 of the repetition spring 54 is set to 1.5 to 10 times the spring constant K2 of the jack spring 55 (1.5·K2 ≤ K1 ≤ 10·K2). For example, if K1 < 1.5·K2, the spring strength of the repetition spring 54 may be insufficient, and the repetition lever 52 may not be able to properly lift the hammer 5. On the other hand, if K1 > 10·K2, the spring strength of the repetition spring 54 may be excessive, and the touch feel of the key 2 may deteriorate.

[0067] Therefore, by setting the spring constant K1 of the repetition spring 54 and the spring constant K2 of the jack spring 55 to satisfy 1.5·K2 ≤ K1 ≤ 10·K2, a touch and playability that more closely resembles that of a grand piano can be obtained.

[0068] Next, referring to Figures 15 to 18, the operation of the action unit 6 and hammer 5 when key 2 (white key 2a) is pressed will be explained.

[0069] Figure 15(a) shows the keyboard device 1 in the unlocked state. In this unlocked state, the hammer 5 is placed on the hammer mounting portion 74 of the repetition lever 52 via the hammer projection portion 46, and the upper end of the hammer thrust portion 83 of the jack 53 faces the hammer projection portion 46 with a gap between them.

[0070] When the front end of key 2 is pushed down from the unlocked state described above, key 2 swings downward and forward around the balance pin 18, and the rear end of key 2 moves upward. Consequently, the action unit 6 also moves upward together with the rear end of key 2, and the hammer 5 is pushed up by the repetition lever 52 via the hammer projection 46. As a result, the hammer 5 rotates upward (clockwise in Figure 15(a)) around the hammer pivot shaft 33.

[0071] Next, as the key is pushed forward and the action unit 6 moves upward, as shown in Figure 15(b), the projection 76 at the rear end of the repetition lever 52 contacts the downward-sloping contact surface 35a of the repetition stopper 35 on the hammer support 4 from below. As a result, the rear end of the repetition lever 52 is locked, while the upper end of the hammer thrusting portion 83 of the jack 53 contacts the hammer projection 46 from below. As a result, the hammer 5 is thrust upward by the hammer thrusting portion 83 of the jack 53 and rotates further upward.

[0072] Next, as the key is pushed further and the action unit 6 moves further upward, as shown in Figure 16(a), the projection 84a at the rear end of the rear arm 84 of the jack 53 contacts the downward-sloping contact surface 36a of the jack stopper 36 on the hammer support 4 from below. As a result, with the rear end of the rear arm 84 locked, the jack 53 rotates clockwise in Figure 16(a) as the jack pivot shaft 64 moves upward, pivoting around the rear end of the rear arm 84. Consequently, as shown in Figure 16(b), the upper end of the hammer thrust portion 83 of the jack 53 moves backward and disengages from the hammer projection 46 of the hammer 5. This disengagement of the jack 53 releases the hammer 5 from the action unit 6 and the key 2, allowing it to rotate further upward in a state of free rotation.

[0073] Furthermore, when jack 53 escapes, a click sensation is produced due to the abrupt increase or decrease in the touch weight of key 2, thereby providing a let-off sensation to the player's touch.

[0074] Figure 17(a) shows the state in which the front end of key 2 is pushed down to its lowest position, and the hammer 5, which has rotated upward, comes into contact with the hammer stopper 38 at the upper front end of the hammer support 4. In this case, the front part of the hammer body 41 of hammer 5 comes into contact with the hammer stopper 38 from below, preventing further rotation of hammer 5. Also in this case, the switch pressing part 45 of hammer 5 presses the switch body 7b of key switch 7 from below, turning key switch 7 ON. This detects key press information corresponding to the rotation speed of hammer 5, etc., and outputs it to a sound control device (not shown). Based on the key press information, the sound control device outputs piano sound from the speaker (not shown) of the electronic piano.

[0075] Furthermore, in the above case, the front arm 72 of the repetition lever 52 abuts against the lower end 65a of the repetition spring locking portion 65 from below via the bush 77, and the front arm 82 of the jack 53 abuts against the lower end 66a of the jack spring locking portion 66 from below via the bush 87. Since both the bush 77 and 78 are made of elastic soft resin, it is possible to prevent the generation of noise caused by the above abutment.

[0076] Figure 17(b) shows the state immediately after the hammer 5 contacts the hammer stopper 38, specifically, the state in which the hammer 5 has bounced back from the hammer stopper 38 and rotated downward (counterclockwise) toward its original position before pressing the key. In this case, the hammer 5 is placed on the hammer mounting portion 74 of the repetition lever 52 via the hammer projection 46. This prevents the hammer 5 from rotating downward more than necessary.

[0077] Figure 18(a) shows the state in which the pressed-down key 2 has been released and returned slightly (for example, 1 / 3 of the key depth). When the key is released from the state shown in Figure 17(b) above, as shown in Figure 18(a), the front end of the key 2 moves upward while the rear end moves downward, and consequently the action unit 6 moves downward together with the rear end of the key 2. In this case, the repetition lever 52 has its front arm 72 pushed down by the biasing force of the repetition spring 54, and as a result it rotates counterclockwise around the repetition pivot shaft 63 as shown in Figure 18(a). Similarly, the jack 53 has its front arm 82 pushed down by the biasing force of the jack spring 55, and as a result it rotates counterclockwise around the jack pivot shaft 64 as shown in Figure 18(a). As a result, as shown in Figure 18(a), the upper end of the hammer thrust portion 83 of the jack 53 wraps around to the underside of the hammer projection portion 46 of the hammer 5, and consequently, the hammer 5 can be driven by the action unit 6 even if the key 2 has not completely returned to the unlocked position.

[0078] Then, when key 2 is fully released, as shown in Figure 18(b), key 2, hammer 5, and the repetition lever 52 and jack 53 of the action unit 6 each return to their original released positions.

[0079] As described in detail above, according to this embodiment, the keyboard device 1 equipped with the aforementioned keys 2, action unit 6, and hammers 5 can achieve operation similar to that of a grand piano, thereby providing a touch and playability equivalent to that of a grand piano during performance.

[0080] Furthermore, when a key is pressed, the hammer 5, which bounces back from the hammer stopper 38 and rotates downward, has its hammer projection 46 contact the hammer mounting portion 74 of the repetition lever 52 from above. In this case, the repetition lever 52 is prevented from rotating by its front arm 72 (bush 77) contacting the lower end portion 65a of the repetition spring locking portion 65 from below. As a result, the height at which the hammer projection 46 contacts the repetition lever 52 from above is maintained above a predetermined height at which the hammer 5 (switch pressing portion 45) presses the key switch 7 (switch body 7a) until the pressed key 2 is released (see Figure 17(b)). This prevents the hammer 5, which bounces back from the hammer stopper 38 and rotates downward when a key is pressed, from going too low, and as a result, it is possible to prevent the sound from cutting off immediately after pressing the key.

[0081] It should be noted that the present invention is not limited to the embodiments described above and can be implemented in various forms. Furthermore, the detailed configurations of the keyboard device 1, keys 2, hammer support 4, hammers 5, and action unit 6 shown in the embodiments are merely illustrative and can be modified as appropriate within the scope of the spirit of the present invention. [Explanation of Symbols]

[0082] 1 Keyboard device 2 keys 4 Hammer Support 5 Hammers 6 Action Units 7-key switch 33 Hammer support shaft 35 Repetition Stopper 36 Jack Stopper 38 Hammer stopper 41 Hammer body 46 Hammer projection 51 Holder 52 Repetition Lever 53 Jack 65 Repetition spring locking mechanism 65a Lower end of repetition spring locking mechanism (hammer height holding means, stopper) 72 Front Arm 73 Hammer mounting arm 73a Jack guide hole 74 Hammer mounting section 83 Hammer thrust section 84 Rear arm

Claims

1. A key that extends a predetermined length in the front-to-back direction and is pivotable with a pivot point near the center in the length direction, An action unit is provided at the rear of the key and performs a predetermined operation in conjunction with the pressing of the key, A hammer support positioned behind the aforementioned key, A hammer extends a predetermined length in the front-rear direction, is rotatably supported at its rear end via a hammer support shaft that extends in the left-right direction of the hammer support, and is mounted on the action unit via a hammer projection that protrudes downward immediately in front of the hammer support shaft, and is driven upward via the action unit when the key is pressed, This hammer presses from below, thereby detecting the key press information of the key, Equipped with, The aforementioned action unit is A holder fixed to the rear end of the key, A repetition lever is formed in a predetermined shape extending in the front-rear direction and is rotatably mounted on the holder. The hammer projection is placed on the upper surface of the lever, which has a jack guide hole that penetrates in the vertical direction and extends in the front-rear direction. The repetition lever rises in response to the pressing of the key, thereby pushing up the hammer via the hammer projection and rotating it upward. The jack has a hammer thrusting portion extending vertically and a rear arm extending rearward from near the lower end of the hammer thrusting portion, is rotatably mounted on the holder, the upper end of the hammer thrusting portion is inserted from below into the jack guide hole of the repetition lever and engages with it so as to be movable in the front-rear direction, and the hammer thrusting portion thrusts the hammer upward via the hammer projection portion from the repetition lever as it rises in conjunction with the pressing of the key, causing the hammer to rotate upward. It is equipped with, The aforementioned hammer support is A repetition stopper locks the repetition lever by contacting the rear end of the repetition lever from below while the hammer is being pushed up by the repetition lever. A jack stopper that, while the jack is thrusting upward by the jack, the rear end of the rear arm contacts the jack from below, thereby locking the jack in place and rotating the jack using the contacting rear end of the rear arm as a pivot point, thereby disengaging the hammer-thrusting portion of the jack from the hammer-protruding portion of the hammer, A hammer stopper that the hammer, which rotates upward when the key is pressed, strikes to prevent further rotation, It has, The keyboard device for a keyboard instrument is characterized in that the action unit further comprises a hammer height holding means for maintaining the height at which the hammer projection of the hammer, which has bounced back from the hammer stopper and rotated downward, contacts the repetition lever from above, at or above a predetermined height at which the hammer presses the key switch until the pressed key is released.

2. The keyboard device for a keyboard instrument according to claim 1, characterized in that the hammer height holding means is provided on the holder and consists of a stopper that prevents the rotation of the repetition lever by contacting the front end of the repetition lever from below.

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