Keyboard chassis for a keyboard instrument

Abstract

Keyboard chassis (2) for a keyboard instrument, formed as a cast article from a synthetic resin and configured to hold a plurality of keys (3) and hammers (4), each extending in a front-back direction, in a left-right arranged state, comprising: a rear retaining part (13) configured to pivot a rear end of each of the buttons (3), a front retaining part (11, 12) which is arranged in front of the rear retaining part (13) at a distance from it, and a key guide part (11a, 12a) which guides the keys (3) which are moved pivotally by a key depress, and / or a hammer retaining part (15) which holds the hammers (4) which are moved in connection with the key depress so that they can pivot, and a plurality of connecting parts (14) arranged with a distance between them in the left-right direction and configured to connect the rear retaining part (13) to the front retaining part (12), wherein each connecting part (14) comprises: a vertical rib (14a) formed with a plate shape of a predetermined thickness in the left-right direction and connected to the rear retaining part (13) and the front retaining part (12), and a reinforcing rib (14b) which is formed with a plate shape having a predetermined thickness in a vertical direction and is arranged at an upper end of the vertical rib (14a) between the rear retaining part (13) and the front retaining part (12), wherein the width in the left-right direction is greater than the thickness of the vertical rib (14a).

Description

Background of the invention / Field of invention

[0001] The present invention relates to a keyboard chassis for a keyboard instrument, which is applied to a keyboard instrument such as an electronic piano and is configured to hold a plurality of keys and hammers in a state arranged in the left-right direction, and in particular to a keyboard chassis structure formed from a cast article made of synthetic resin, and to a key guide structure for guiding a key which is pivotally moved when a key is pressed. State of the art

[0002] The present applicant has already proposed a keyboard chassis for an electronic piano in the published Japanese patent (Kokai) JP 2005-70644 A. The keyboard assembly of the electronic piano, including the keyboard chassis, comprises a plurality of keys extending in a front-to-back direction and a plurality of hammers, each corresponding to one of the keys, with the keyboard chassis pivotally holding the keys and hammers. The keyboard chassis is formed as a cast article made of a synthetic resin such as ABS. The keyboard chassis of the entire electronic piano is formed by connecting a plurality of keyboard chassis, each corresponding to one octave in the front-to-back direction.

[0003] The keyboard chassis is constructed from a synthetic resin such that a rear part of it (referred to here as the "chassis back") pivots the keys, while a front part of it (referred to here as the "chassis front") guides each key, which pivots when pressed, and holds a hammer associated with the key and moved in conjunction with its depression. Furthermore, the keyboard chassis is provided with a plurality of vertical ribs that connect the chassis back to the chassis front, maintaining space between them for the pivoting movement of each hammer. Specifically, each vertical rib is formed as a plate of a predetermined thickness in the left-right direction and is arranged such that it divides adjacent hammers in this direction.

[0004] The applicant has further proposed a key guidance assembly for a keyboard instrument in the published Japanese patent (Kokai) JP 2000-122654 A. A keyboard device of an electronic piano, to which the key guidance assembly is applied, comprises a plurality of keys, each extending in a front-to-back direction and having an inverted U-shape in cross-section formed by a top wall and left and right walls, and a keyboard chassis that holds these keys in a left-to-right oriented position, in which each key is pivotably held at its rear end. A key guide is provided on the keyboard chassis for each key to guide the pivoting keys. Furthermore, in this keyboard device, the keys and the keyboard chassis are formed as cast articles made of a hard synthetic resin.Each key guide rises below a front end or adjacent to an associated key and is formed with a plate shape having a lateral width substantially equal to the distance between the left and right side walls of the key, with a lubricant such as grease applied to the left and right sides of the key guide.

[0005] Furthermore, another key guide design for a keyboard device was proposed in the disclosed Japanese patent publication (Kokai) JP H11-296162 A. A key guide described in this publication is formed by mounting a rubber guide element to a guide element retaining part that projects upwards. The guide element has a hollow, cylindrical shape and is mounted to the guide element retaining part such that the retaining part is inserted into its interior.

[0006] Further examples of keyboard devices are disclosed in US 2007 / 0068360 A1 and JP 2009-109934 A.

[0007] In the key guidance assemblies of the disclosed Japanese patent publications (Kokai) JP 2000-122654 A and the disclosed Japanese patent publications (Kokai) JP H11-296162 A, when a key is in a released state, an upper end of the associated key guide engages the key in a partially inserted state. When the key is pressed from this released state, the key guide engages deeply into the key to guide the pivoting key in such a way as to prevent it from pivoting in the left-right direction, thus preventing lateral pivoting of the key.

[0008] In the keyboard chassis described above, relatively high rigidity is ensured by the inclusion of numerous vertical ribs connecting the front and rear sections of the chassis. However, because the number of vertical ribs is large, a greater quantity of resin is required for casting the keyboard chassis. Naturally, the amount of material used for the keyboard chassis can be reduced by decreasing the number of vertical ribs.

[0009] However, this presents the following problem: If the electronic piano is stored upright with the left and right sides positioned vertically opposite each other, and the room temperature becomes very high, for example in summer, the vertical resin ribs tend to bend downwards due to the weight of the keyboard chassis and the hammers, potentially causing deformation of the chassis. This can result in the hammer not moving smoothly when a key is pressed, or a noise being produced by the pivoting key or hammer rubbing against the keyboard chassis.

[0010] In contrast, the key guide design of the aforementioned disclosed Japanese patent publication (Kokai) JP 2000-122654 A uses a hard synthetic resin for the keys and keyboard chassis. This means that if the lubricant applied to the key guides becomes depleted after prolonged use of the electronic piano, noise is generated by the rubbing of each key's inner surface against the guide as it slides. Furthermore, if too much lubricant is applied to the key guide, it can leak from the key. However, because the guide element in disclosed Japanese patent publication (Kokai) JP H11-296162 A has a hollow cylindrical shape that covers the exterior of the guide element's retaining part, the amount of material used to form the guide element is relatively large, thus increasing the cost. Summary of the invention

[0011] It is an object of the invention to provide a keyboard chassis for a keyboard instrument which can provide sufficient rigidity and can reduce the amount of synthetic resin used as material, thereby preventing deformation of the keyboard chassis even when the keyboard instrument is stored in an upright position.

[0012] The present invention is defined in main claim 1. Preferred embodiments are the subject of the dependent claims.

[0013] To solve the problem, the invention provides a keyboard chassis for a keyboard instrument, which is formed as a cast article made of a synthetic resin and is configured to hold a plurality of keys and hammers, each extending in a front-back direction, in a left-right oriented position, wherein the keyboard chassis comprises: a rear retaining part configured to pivot a rear end of each of the keys; a front retaining part arranged in front of the rear retaining part at a distance from it, and comprising a key guide part that guides the keys pivotally moved by a key depress, and / or a hammer retaining part that pivotally holds the hammers moved in conjunction with the key depress;and a plurality of connecting parts arranged with a space between them in the left-right direction and configured to connect the rear retaining part to the front retaining part; each connecting part comprising: a vertical rib formed with a plate shape of a predetermined thickness in the left-right direction and connecting to the rear retaining part and the front retaining part; and a reinforcing rib formed with a plate shape of a predetermined thickness in a vertical direction and arranged at an upper end of the vertical rib between the rear retaining part and the front retaining part, the width in the left-right direction being greater than the thickness of the vertical rib.

[0014] In this keyboard chassis design, the numerous keys are each pivotally mounted at their rear end to the rear support section of the chassis. Furthermore, the front support section of the keyboard chassis contains a key guide that directs the keys as they pivot when pressed, and / or a hammer support that pivots the hammers that move in conjunction with the key press. The rear and front support sections are connected by numerous connecting pieces spaced apart along the left-right axis.

[0015] Each connecting element has a vertical rib formed with a plate of predetermined thickness in the left-right direction, the vertical rib being connected to the rear and front retaining elements. Furthermore, a reinforcing rib, also formed with a plate of predetermined thickness in a vertical direction, is located at the upper end of the vertical rib between the rear and front retaining elements, with a width greater than the thickness of the vertical rib in the left-right direction.This allows the connecting element to be much stronger than if it were formed solely by the vertical rib, and the number of connecting elements (vertical ribs) can be reduced while still providing sufficient rigidity for the keyboard chassis compared to a conventional keyboard chassis where vertical ribs divide adjacent hammers in the left-right direction. Compared to the prior art, rigidity can therefore be ensured while simultaneously reducing the amount of resin used and preventing deformation of the keyboard chassis when the instrument is stored upright.

[0016] Preferably, the multitude of connecting parts are provided for each predetermined two or a larger number of buttons and / or hammers.

[0017] In this design, compared to the conventional keyboard chassis with vertical ribs that divide between adjacent hammers, the number of connecting parts is reduced, which in turn reduces the amount of synthetic resin used as material.

[0018] Preferably, the reinforcing rib is designed such that the width in the left-right direction increases progressively from the rear retaining part or the front retaining part to the other part.

[0019] This design maintains sufficient strength in each connecting part while simultaneously reducing the amount of material compared to the case where the reinforcing rib is formed with a greater width in the left-right direction over its entire length in the front-back direction.

[0020] According to a preferred sub-aspect of the present invention, a key guide assembly for a keyboard instrument is specified, comprising a plurality of keys, each extending in a front-to-back direction, the rear ends of which are each pivotably held on a keyboard chassis and which have a downwardly open guide recess, wherein the key guide assembly is designed to guide each key pivotally moved by a key depress, and comprises: a plurality of key guide holders, each having a mounting part that opens upwards and extends in a left-to-right direction, and each provided for the keys such that they rise on the keyboard chassis at a position below the guide recess;and a plurality of key guide bodies, each formed from a soft synthetic resin and having a plate shape with a width substantially equal to the inner width of the guide recess of the key in the left-right direction, each key guide body being mounted in the mounting part of an associated key guide holder in a position inserted into it from above in order to be brought into sliding contact with the left and right inner surfaces of the guide recess of the associated key.

[0021] In this key guide assembly, the numerous keys, extending in a front-to-back direction, each have a downward-facing guide opening and are pivotally mounted at their rear end to a keyboard chassis. The numerous key guide holders, each with a predetermined mounting element, rise for each key on the keyboard chassis at a position below the guide recess. A key guide body is mounted in the mounting element of an associated key guide holder in a position inserted from above. Each key guide body is formed with a plate shape whose width is essentially equal to the inner width of the key's guide recess in the left-to-right direction, in order to be brought into sliding contact with the left and right inner surfaces of the guide recess.Therefore, when a key is pressed, the key is pivoted around its rear end and guided by the left and right inner surfaces of the guide recess sliding along the left and right sides of the key guide body.

[0022] Furthermore, the key guide body is made of a soft resin. Therefore, even if the key itself is made of a hard resin and the inner surfaces of the guide recess rub against the key guide body, the generation of sliding noise can be significantly reduced. The key can thus be guided stably and without noise. And because the key guide body has a plate-like shape, the amount of resin used can be reduced compared to a cylindrical guide, thereby lowering manufacturing costs.

[0023] Preferably, the key comprises left and right side walls with a predetermined distance between them in the left-right direction, as well as left and right guide walls which are provided at corresponding positions spaced inwards from the left and right side walls at a predetermined distance, such that they are spaced apart from each other at a distance which is essentially equal to the lateral width of the key guide body in the left-right direction, wherein the left and right guide walls each form left and right walls of the guide recess.

[0024] In this design, the key, which has left and right side walls spaced at a predetermined distance in the left-right direction, is provided with left and right guide walls. These guide walls are positioned at predetermined distances from the associated side walls. Furthermore, these guide walls are spaced apart from each other at a distance essentially equal to the lateral width of the key guide body in the left-right direction, and each forms the left and right walls of the guide recess. Thus, by positioning the guide walls at distances from the associated side walls, even when a relatively large amount of lubricant, such as grease, is applied to the key guide body, lubricant leakage from the key is effectively prevented.

[0025] Preferably, the key guide body has left and right side surfaces, each of which is provided with a groove for holding a lubricant.

[0026] When a lubricant is applied to the left and right sides of the key guide body in this design, some of the lubricant enters the groove and is retained there. This allows a condition to be maintained in which the lubricant is held on the left and right sides of the key guide body for an extended period, ensuring lubrication between the side walls of the key guide recess and the sides of the key guide body during key depression.

[0027] Preferably, the key guide body has a retaining part provided at a lower end, wherein the retaining part is configured to engage with the key guide holder in a held state when the key guide body is mounted in the mounting part.

[0028] In this design, the key guide body engages in the key guide holder in a held position when it is mounted in the mounting part by being inserted into the mounting part of the key guide holder from above. This ensures that the key guide body is reliably attached to the key guide holder and prevents it from falling off, even when the key's guide recess is in sliding contact with the key guide body during key depression.

[0029] Preferably, the key guide holder comprises a holder body which is designed with a hollow, cylindrical shape, extends vertically and includes the mounting part, and a reinforcing part which rises on the keyboard chassis in front of and / or behind the holder body and connects to the holder body.

[0030] In this design, the holder body and mounting part have a hollow, cylindrical shape and extend vertically, with the key guide body mounted to the holder body. Furthermore, a reinforcing element is positioned in front of and / or behind the holder body, thus strengthening it against the load in the front-to-back direction. Consequently, the key guide body mounted on the holder body can be reliably held.

[0031] In particular, the reinforcement part is designed with a hollow shape and extends vertically.

[0032] In this design, the reinforcing part of the key guide holder has a hollow shape and extends vertically, so that the holder body is reinforced not only against loads in the front-back direction, but also against loads in the left-right direction. As a result, the key guide mounted on the holder body can be held more reliably.

[0033] The above-mentioned and other tasks, features and advantages of the present invention are clarified by the following detailed description with reference to the accompanying drawings. Brief description of the drawings Fig. Figure 1 is a perspective view of a keyboard device (for an octave section) of an electronic piano to which a keyboard chassis and a key guidance structure according to an embodiment of the present invention are applied. Fig. 2A is a top view of the keyboard mechanism of Fig. 1. Fig. 2B is a cross-sectional view along line b--b of Fig. 2A. Fig. 3A is a perspective exploded view of a keyboard chassis and keys of the keyboard device by Fig. 1 Fig. 3B is an enlarged perspective view of part of the rear end of the keyboard chassis. Fig. Figure 4 is a perspective view of a white key and a black key. Fig. 5A is an enlarged top view of a rear part of the key. Fig. 5B is an enlarged right side view of the rear part of the key. Fig. 6A is a perspective view of a hammer. Fig. 6B is a perspective exploded view of the hammer, broken down into a hammer body and weights. Fig. 7A and Fig. 7B are views showing the ribs of the keyboard chassis, where Fig. 7A is a perspective view showing a reinforcing rib, and Fig. Figure 7B is a top view of the keyboard chassis, showing the reinforcing rib in the center. Fig. 8A and Fig. 8B are views showing a white key guide part, where Fig. Figure 8A shows a perspective view of a left white key guide part in a state where a key guide body has been mounted on a key guide holder, and of a right white key guide part in a state where a key guide body has been removed from a key guide holder. Fig. 8B a top view of the left and right white key guide parts in the states of Fig. 8A is. Fig. 9A is a front view of the key guide body. Fig. 9B is a cross-sectional view along line b--b of Fig. 9A. Fig. 9C is a cross-sectional view along line c--c of Fig. 9A. Fig. 10 is a cross-sectional view of the white key guide part along the line X--X of Fig. 8B. Fig. 11A and Fig. 11B are views showing the relationship between a white key and an associated white key guide part, where Fig. 11A is a perspective vertical section view from below of a front end of the white button and Fig. Figure 11B is a top view of the white key, the upper part of which is cut horizontally to show the relationship between the white key and the white key guide part. Detailed description of preferred embodiments

[0034] The invention is described in detail below with reference to the drawings, which show a preferred embodiment. Fig. 1, Fig. 2A and Fig. Figure 2B shows a keyboard device in a released key state of an electronic piano, to which a keyboard chassis and a key guide assembly according to the embodiment are applied. It should be noted that Fig. 1, Fig. 2A and Fig. 2B shows only one octave section of the keyboard device.

[0035] As in Fig. 1, Fig. 2A and Fig. As shown in Figure 2B, the keyboard device 1 comprises a keyboard chassis 2, a plurality of keys 3 including white keys 3a and black keys 3b which are pivotably mounted on the keyboard chassis 2 and arranged in the left-right direction, a plurality of hammers 4 which are pivotably mounted on the keyboard chassis 2 in association with the corresponding keys 3, and a key switch 5 for detecting key depress information on the keys 3.

[0036] The keyboard chassis 2 is a cast resin component, formed, for example, by injection molding a predetermined resin material (e.g., ABS resin) into a predetermined shape. As in Fig. As shown in Figure 3A, the keyboard chassis 2 comprises a front part 11, a middle part 12, and a rear part 13, each extending in the left-right direction. The front part 11, the middle part 12, and the rear part 13 are connected to one another by a plurality of ribs 14 (connecting part) spaced at appropriate intervals in the left-right direction. It should be noted that in the following description, the front part 11, the middle part 12, and the rear part 13 of the keyboard chassis 2 are each referred to as "the chassis front part 11," the "chassis middle part 12," and the "chassis rear part 13," respectively.

[0037] The chassis front section 11 serves to guide the white keys 3a. The chassis front section 11 has a multitude of (seven in Fig. 3A) White key guide parts 11a (key guide part) rise there and are each inserted from below into an associated white key 3a to prevent lateral pivoting of the white key 3a. Furthermore, the chassis front part 11 has engagement holes 11b and 11b, which extend vertically and are formed in the left and right sides of each of the white key guide parts 11a. A pair of left and right upper limit position determining parts 21a and 21a (explained below) of the white key 3a engages in the corresponding engagement holes 11b and 11b when inserted into them.

[0038] The chassis center section 12 serves to guide the black keys 3b. Similar to the chassis front section 11, the chassis center section 12 has a multitude of (five in Fig. 3A) Black key guide parts 12a (key guide part) rise up there and each engage from below in an associated black key 3a to prevent lateral pivoting of the black key 3b. Furthermore, a hammer retaining part 15 for holding the hammers 4 is arranged at a position in front of the chassis center part 12. The hammer retaining part 15 has a plurality of retaining shafts 15a that extend along a straight line in the left-right direction, with the hammers 4 each being pivotably held by the retaining shafts 15a.

[0039] Furthermore, the push-button switch 5 is mounted between the hammer retaining part 15 and the chassis front part 11. The push-button switch 5 consists of a laterally elongated circuit board 5a, which extends in the left-right direction, and of a plurality of switch bodies 5b, each formed by a rubber switch and mounted on the circuit board 5a in association with each button 3.

[0040] The chassis rear section 13 serves to hold the keys 3 at their rear ends in such a way that the keys 3 can pivot in the vertical direction. As in Fig. As shown in Figure 3B, the chassis rear section 13 is provided with a plurality of partitions 16, which are formed between them at a predetermined distance in the left-right direction, such that the adjacent keys 3 and 3 are separated from each other. Furthermore, between each pair of adjacent partitions 16, 16, a predetermined key retainer 17 is formed, which has a laterally symmetrical shape and is configured to pivotally hold an associated key 3. In particular, the key retainer 17 comprises left and right lower retainers 18 and 18 (only the left one of which is shown in Figure 3B). Fig. 3B shown), to hold from below corresponding left and right pivot shafts 24 and 24 (explained further below), and a pair of left and right upper retaining parts 19 and 19 to hold from above part of a rear end of the key 3 extending from the upper surface of the key 3 to the rear surface of the same.

[0041] It should be noted that in the keyboard chassis 2 with the above described construction, the chassis rear part 13 corresponds to a rear retaining part of the present invention, while the chassis front part 11, the chassis middle part 12 and the hammer retaining part 15 correspond to a front retaining part of the present invention.

[0042] For example, key 3 is formed by injection molding a predetermined synthetic resin material (e.g., an AS resin) into a hollow shape that extends over a predetermined length in the front-to-back direction and opens downwards. As in Fig. 3A and Fig. As shown in Figure 4, the white button 3a is provided at its front end with a pair of left and right upper limit position determining elements 21 (21a), which extend downwards from corresponding side walls of the front end of the white button 3a and whose lower ends are each bent forwards. The upper limit determining elements 21 (21a) engage in the corresponding left and right engagement holes 11b and 11b when inserted into them. Furthermore, the white button 3a has an actuator element 22 (22a) that projects downwards and is formed at a predetermined position behind the upper limit position determining elements 21a. The actuator element 22a engages in an actuator recess 34 (described below) of the hammer 4 when engaged in the recess.Furthermore, the black button 3b has a front end which is equipped with an upper limit position determining part 21 (21b) and an actuator part 22 (22b) which have the same functions as the upper limit position determining parts 21a and the actuator part 22a of the white button 3a.

[0043] As in Fig. 4, Fig. 5A and Fig. As shown in Figure 5B, the key 3 has a rear part including a rear body 23, which is configured to be narrower than the front part of the key 3 and extends in the front-to-back direction. The pivot shafts 24 and 24, which project outwards (left and right respectively), are formed on the left and right side faces of the rear body 23 at corresponding predetermined positions near a rear end of the rear body 23. Each of the pivot shafts 24 and 24 comprises a lower half, configured as a semicircular part 24a with an arcuate base and a semicircular side face, and a projection 24b, which projects upwards from the center of the semicircular part 24a in the front-to-back direction. It should be noted that the semicircular part 24a of each of the pivot shafts 24 has a groove 24c formed in the arcuate base surface.If a lubricant such as grease is applied to the arc-shaped base surface of the semicircular part 24a, the grease can be retained therein for a long time.

[0044] The rear end of the rear body 23 is configured such that a curved surface 25 with a predetermined curvature extends from the upper surface to the rear surface of the rear body 23. The curved surface 25 is configured to curve convexly along a concentric circle around the pivot shaft 24 of the key 3 in a side view. Furthermore, the rear end of the rear body 23 has a tapered portion 26 adjoining the curved surface 25, with a lateral width that tapers downwards. It should be noted that the curved surface 25 is formed with a groove 25a, which serves the same function as the groove 24c of the pivot shaft 24.

[0045] As in Fig. 6A and Fig. As shown in Figure 6B, the hammer 4 comprises a hammer body 31 and two weights 32 and 333, which are attached to the hammer body 31. The hammer body 31 is formed as a casting made of synthetic resin, which is formed, for example, by injection molding a predetermined synthetic resin material (e.g., POM (polyoxymethylene or polyacetal)) into a predetermined shape. The hammer body 31 extends over a predetermined length in the front-to-back direction and has a bearing part 33, which is formed at a predetermined position forward of the center of the hammer body 31 in the front-to-back direction. The bearing part 33 has an inverted U-shape that opens downwards in a side view and pivotably engages in the retaining shaft 15a of the hammer retaining part 15 of the keyboard chassis 2. The engagement recess 34 for engagement in the actuator part 22 of the button 3 is formed in the front half of the hammer body 31 at a position in front of the bearing part 33.The engagement recess 34 opens upwards and forwards, and the lower part of the actuator part 22 of the button 3 is received in the engagement recess 34 in a state in which a lower end of the actuator part 22 is held in contact with a bottom surface of the engagement recess 34. Furthermore, a plurality of switch push elements 35 for pressing the switch body 5b of the push button 5 are provided below the engagement recess 34 in the front half of the hammer body 31.

[0046] A weight mounting part 36, forming a rear half of the hammer body 31, comprises two pairs of engagement projections 37 and 37, respectively, which are formed at predetermined positions on the corresponding left and right side faces of the weight mounting part 36 such that they project outwards, i.e., to the left and right respectively, from the weight mounting part 36, and a mounting hole 38, which is formed at a position near the rear pair of engagement projections 37 such that it extends through the weight mounting part 36 in the left-right direction. It should be noted that a recess 36a is formed in a central part of the weight mounting part 36 to prevent screws or similar fasteners from being used to fix the keyboard assembly 1 to a keybed 10 of an electronic piano (see Figure 1). Fig. 2B) strike against the hammer 4 when the keyboard device 1 is in the released key state.

[0047] The weights 32 are formed as two long and narrow plates from a material (a metal such as steel) that has a higher specific gravity than the hammer body 31. Each of the weights 32 is formed in a predetermined shape, e.g., by pressing a long metal plate with a predetermined thickness and width. In particular, the weight 32 is provided with two engagement holes 41 and 41 (front and rear), a mounting hole 42, and a recess 43, which correspond to the two engagement projections 37 and 37, the mounting hole 38, and the recess 36 in the hammer body 31. The two weights 32 and 32 are rigidly attached to the hammer body 31 in a state in which the weight mounting part 36 of the hammer body 31 is clamped, by riveting rivets 44 inserted through the mounting holes 42, 42, and 38.

[0048] One of the weights attached to each of the hammers 4 (hereinafter referred to as the "common weight 32A") has a predetermined length and is common to all hammers 4. Furthermore, the other weight (hereinafter referred to as the "adjustment weight 32B") has a length equal to or less than that of the common weight 32A. Therefore, the weight of the hammer 4 containing the two weights 32A and 32B can be changed by adjusting the length of the adjustment weight 32B.

[0049] If, in the keyboard device 1 with the setup described above, key 3 is in the released key state of Fig. 1 and Fig. When 2B is pressed down, the button 3 pivots downwards around the left and right pivot shafts 24 and 24 of the rear end of the button 3. During this pivoting movement of the button 3, the actuating part 22 of the button 3 presses the engagement recess 34 of the hammer 4 downwards. It follows that the hammer 4 presses the associated switch body 5b of the push button 5 from above over the switch push element 35, while pivoting counterclockwise from Fig. 2B rotates around the retaining shaft 15a of the hammer retaining part 15. In this case, the rear end of the hammer 4 (i.e., the rear end of the common weight 32A) is brought into contact from below with a hammer stop 13a of the chassis rear part 13, thus suppressing any further pivoting movement of the hammer 4. Through the key depressing process described above, a predetermined contact weight corresponding to the weight and torque of the hammer 4 is exerted on the key 3, and key depress information is also detected at the key 3 via the key switch 5.

[0050] If, on the other hand, the depressed button 3 is released, the hammer 4 moves pivoting in a direction opposite to the direction mentioned above, i.e., in a clockwise direction. Fig. 2B. During this pivoting movement of the hammer 4, the button 3 is pushed upwards via the actuator part 22 and moves upwards in a pivoting motion. It follows that the button 3 and the hammer 4 return to the released button state of Fig. 1 and Fig. 2B return. In this case, the upper limit position determining parts 21 of the front end of the key 3 are brought from below into a collision with a predetermined stopper 20 of the keyboard chassis 2, thereby suppressing any further pivoting movement of the key 3.

[0051] In the following, the keyboard chassis 2 according to the invention is described with reference to Fig. 3A, Fig. 7A and Fig. 7B is described in greater detail, in particular explaining the construction of the ribs 14 which connect the chassis rear part 13 (the rear retaining part) with the assembly group consisting of the chassis front part 11, the chassis middle part 12 and the hammer retaining part 15 (the front retaining part) in the front-to-back direction.

[0052] Fig. 7A and Fig. Figures 7B are each a perspective view and a top view, which in magnification show the ribs 14 that serve to support the chassis rear section 13 and the chassis center section 12 of the in Fig. To connect the keyboard chassis 2 shown in 3A. As in Fig. As shown in Figure 3A, the keyboard chassis 2 is provided with five ribs 14 for two or three keys 3 (hammers 4) spaced apart in the left-right direction. Each rib 14 has a rib body 14a (a vertical rib) formed with a plate shape of a predetermined thickness in the left-right direction, which connects to the chassis center section 12 and the chassis rear section 13, wherein the predetermined two of the ribs 14 each have a reinforcing rib 14b for strengthening the rib 14, which is provided at an upper end of the rib body 14a.

[0053] The reinforcing rib 14b is designed such that it has a plate shape with a predetermined thickness in the vertical direction, its width in the left-right direction being greater than the thickness of the rib body 14a. Furthermore, the reinforcing rib 14b is designed such that its width increases progressively from the center of the upper end of the rib body 14a in the front-back direction towards the chassis center section 12.

[0054] As described in detail above, in this embodiment of the keyboard chassis 2, the ribs 14 connect the chassis rear section 13, for pivotally holding the keys 3, to the chassis center section 12, for guiding the black keys 3b. Furthermore, one of the adjacent ribs 14 has the reinforcing rib 14b, which is provided at the upper end of the rib body 14a. In this way, the thickness of the rib 14 can be significantly increased compared to the case where the rib 14 only has the rib body 14a, while simultaneously reducing the number of ribs 14 and still ensuring sufficient rigidity for the keyboard chassis 2 compared to a conventional keyboard chassis in which vertical ribs are arranged to separate adjacent hammers in the left-right direction.Therefore, the amount of synthetic resin used as a material can be reduced compared to the amount used in a conventional keyboard chassis, while still ensuring sufficient rigidity of the keyboard chassis 2. Furthermore, deformation of the keyboard chassis 2 can be prevented even when the electronic piano is stored in an upright position.

[0055] It should be noted that the keyboard chassis 2 according to the invention is not limited to the embodiment described above, but that the invention can also be implemented in various other ways. For example, in one octave section of the keyboard chassis 2 of this embodiment, two of the five ribs 14 are provided with reinforcing ribs 14b, although one reinforcing rib 14b can also be provided for each of the ribs 14. Alternatively, a reinforcing rib 14 can be provided for only one of the ribs 14 if sufficient strength and rigidity of the keyboard chassis 2 can be ensured.

[0056] Furthermore, in this embodiment, the reinforcing rib 14b is designed such that its width increases from the rear chassis section 13 to the central chassis section 12. However, the shape of the reinforcing rib 14b is not limited to this and it can also be designed such that its width increases progressively from the central chassis section 12 to the rear chassis section 13. The detailed construction of the keyboard chassis 2 of this embodiment is described here only by way of example and can be modified as required within the scope of the invention.

[0057] The following section describes in detail the key guidance structure according to the invention with reference to Fig. 3A, 3B and 8A to 11B are described, in particular explaining the construction of the white key guide part 11a of the chassis front part 11 and the construction of the white key to be guided by the white key guide part 11a.

[0058] Fig. 8A and Fig. Figure 8B shows two white key guide parts 11a of the chassis front 11. One (the left one in Fig. 8A and Fig. 8B) The white key guide parts 11a are in a state in which a key guide body 52 (described below) has been mounted on it. And the other (the right one in Fig. 8A and Fig. 8B) The white key guide parts 11a are in a state in which the key guide body 52 has been removed from it. As in Fig. As shown in Figure 8A, each of the white key guide parts 11a comprises a key guide holder 51 which rises on a horizontal, flat part 11c of the chassis front part 11, and the key guide body 52 which is mounted on the key guide holder 51.

[0059] The key guide holder 51 is formed integrally with the keyboard chassis 2 and comprises a hollow, cylindrical holder part 53 (holder body) extending vertically over a predetermined length, and reinforcing parts 54 and 55 that rise on the flat part 11c such that they connect to the front and rear parts of the holder part 53, respectively. The holder part 53 is provided with a slotted mounting part 53a that extends vertically upwards and has a slot in the left-right direction, with the key guide body 52 being mounted on the mounting part 53a. Each of the front and rear reinforcing parts 54 and 55 has a U-shape in plan view, opening towards the holder part 53.It should be noted that the reinforcement part 55 is provided with additional reinforcement parts 55a and 55a, which extend on the flat part 11c in such a way that they connect to the corresponding left and right side surfaces of the lower half of the rear reinforcement part 55.

[0060] Furthermore, the key guide body 52 is made of a soft synthetic resin (e.g., an elastomer) and has a vertically elongated plate shape. In particular, the key guide body 52 is as shown in Fig. Figures 9A to 9C show the key guide body 52 having a vertically elongated, rectangular shape in front view, with its upper, left, and right end parts each having predetermined thicknesses and being designed such that the end parts are thicker than the other parts. Furthermore, the end parts of the key guide body 52 are provided with a groove 52a extending along the circumference. When a lubricant such as grease is applied to the end parts of the key guide body 52, some of the lubricant enters the groove 52a and is retained therein. This allows a condition to be maintained in which the grease is retained on the left and right side surfaces for a long time, thus ensuring lubrication between the left and right guide walls 61 and 61 (described below) of the key 3 and the left and right side surfaces of the key guide body 52 during key depression.

[0061] Furthermore, the key guide body 52 has an insertion part 56 which is designed in the center of the front surface such that it extends vertically in order to be inserted into the holder part 53 of the key guide holder 51. As shown in Fig. 9A and Fig. As shown in Figure 9B, the insertion part 56 is relatively thick in the front-to-back direction and has a lateral width that decreases downwards. Furthermore, the insertion part 56 has a lower end provided with a forward-projecting engagement projection 57 (retaining element). The engagement projection 57 comprises an engagement surface 57a, which is essentially horizontal, and an inclined surface 57b, which slopes forwards and upwards at a position below the engagement surface 57a.

[0062] In the key guide holder 51 and the key guide body 52 with the assembly described above, the key guide body 52 is mounted on the key guide holder 51, with the insertion part 56 being inserted from above into the mounting part 53a of the holder part 53 of the key guide holder 51 in the center of the key guide body 52. ​​In this case, the key guide body 52 is mounted such that its upper, left, and right end parts are held by the holder part 53 of the key guide holder 51 as shown in Fig. 8A shown protruding outwards. Furthermore, as in Fig. Figure 10 shows the engagement projection 57 of the key guide body 52 positioned under the retaining part 53 of the key guide holder 51, and the engagement surface 57a of the engagement projection 57 is blocked by the lower end of the retaining part 53. This ensures that the key guide body 52 is reliably mounted in a held position on the key guide holder 51.

[0063] Fig. 11A and Fig. 11B shows a front part of the white key 3a. Fig. Figure 11A shows the internal structure of the front part of the white key 3a, and Fig. Figure 11B shows the relationship between the white key 3a and the white key guide part 11a. As in Fig. 11A and Fig.As shown in Figure 11b, the left and right guide walls 61 and 61 are provided in the front part of the white key 3a at a predetermined distance in the left-right direction. Each of the guide walls 61 is formed integrally with the white key 3a via a spacer element 62, which extends vertically over a predetermined length from an upper wall 60a of the white key 3a and projects inwards over a predetermined length from an associated side wall 60b of the white key 3a. The distance between the left and right guide walls 61 and 61 is set approximately equal to the lateral width of the key guide body 52, and the two guide walls 61 and 61 form a guide recess according to the invention, which opens downwards and brings the left and right side surfaces of the key guide body 52 into sliding contact.

[0064] When the white key 3a with the left and right guide walls 61 and 61 with the above described structure is pressed down, the white key 3a pivots around the pivot shafts 24 and its rear end is guided smoothly and without lateral pivoting, with the two guide walls 61 and 61 being held in sliding contact with the corresponding left and right side surfaces of the key guide body 52 of the white key guide part 11a.

[0065] The black key guide part 12a for guiding the black key 3b is not described in detail here, but has the same key guide body as the key guide body 52 of the white key guide part 11a, the key guide body being configured to be held in direct sliding contact with the left and right side walls of the black key 3b.

[0066] As described in detail above, in the key guide assembly of the present embodiment, the key guide body 52 for guiding the pivoting key 3 is made of a soft synthetic resin. This significantly reduces the sliding noise generated when the guide walls 61, etc., of the key 3 rub against the key guide body 52, thus ensuring stable and silent guidance of the key 3. Furthermore, because the key guide body 52 is designed in a plate shape, the amount of synthetic resin used can be reduced compared to the prior art, where the guide element is designed with a cylindrical shape, thereby reducing manufacturing costs.

[0067] And in the case of the white key 3b, the left and right guide walls 61 and 61, which are spaced inwards from the corresponding left and right side walls 60b and 60b of the white key 3b, are held in a sliding contact with the key guide body 52 of the white key guide part 11a, so that even if a relatively large amount of lubricant has been applied to the left and right side walls of the key guide body 52, it can be positively prevented that the lubricant leaks from the white key 3b (from the side walls 60b).

[0068] And because the reinforcing parts 54 and 55 are provided in positions in front of and behind the holder part 53 with the key guide body 52 mounted on it in the key guide holder 51, the holder part 53 can be reinforced against a load acting from the front, back, left and right, so that the key guide body 52 mounted on the holder part 53 is reliably held.

[0069] It should be noted that the key guide assembly of the present invention is not limited to the embodiment described above and that the present invention can be implemented in various ways. For example, in the key guide holder 51 of the embodiment described above, the holder part 53, on which the key guide body 52 is mounted, is designed with a hollow, cylindrical shape, and the reinforcing parts 54 and 55, each having a hollow prism shape, are arranged at corresponding positions in front of and behind the holder part 53. However, the holder part 53 need not have a hollow, cylindrical shape, but can also have a hollow shape other than a hollow, cylindrical one (such as a hollow prism shape). Furthermore, one of the two reinforcing parts 54 and 55 can be omitted, or the shape of the two reinforcing parts can be changed to a different shape (e.g., a hollow prism shape).to a hollow cylindrical shape or a plate shape).

[0070] The construction, material, etc. of the key guide holder 51, the key guide body 52 and the key 3 in the key guide assembly of the invention have been described above by way of example and can be modified as desired within the scope of the invention.

Claims

[1] Keyboard chassis (2) for a keyboard instrument, formed as a cast article from a synthetic resin and configured to hold a plurality of keys (3) and hammers (4), each extending in a front-back direction, in a left-right arranged state, comprising: a rear retaining part (13) configured to pivot a rear end of each of the buttons (3), a front retaining part (11, 12) which is arranged in front of the rear retaining part (13) at a distance from it, and a key guide part (11a, 12a) which guides the keys (3) which are moved pivotally by a key depress, and / or a hammer retaining part (15) which holds the hammers (4) which are moved in connection with the key depress so that they can pivot, and a plurality of connecting parts (14) arranged with a distance between them in the left-right direction and configured to connect the rear retaining part (13) to the front retaining part (12), wherein each connecting part (14) comprises: a vertical rib (14a) formed with a plate shape of a predetermined thickness in the left-right direction and connected to the rear retaining part (13) and the front retaining part (12), and a reinforcing rib (14b) which is formed with a plate shape having a predetermined thickness in a vertical direction and is arranged at an upper end of the vertical rib (14a) between the rear retaining part (13) and the front retaining part (12), wherein the width in the left-right direction is greater than the thickness of the vertical rib (14a). [2] Keyboard chassis (2) according to claim 1, wherein the plurality of connecting parts (14) are provided for each predetermined two or a larger number of keys (3) and / or hammers (4). [3] Keyboard chassis (2) according to claim 1 or 2, wherein the reinforcing rib (14b) is designed such that the width in the left-right direction increases progressively from the rear retaining part (13) or the front retaining part (12) to the respective other retaining part (12, 13).

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