Keyboard device for electronic keyboard instrument

Abstract

A pressing surface of a hammer and a to-be-pressed surface of a key switch have relatively-concaved shapes in a longitudinal direction of the hammer. When a switch body is pressed by the hammer, an inclination caused by an overall curvature of the switch body that results from the fact that the switch body is pressed by the hammer from an oblique direction is canceled by an inclination of the switch body caused by partial compression and deformation that results from the relatively-concaved shapes, so that movable contacts in the switch body frontally face stationary contacts and come into contact with the stationary contacts, respectively.

Claims

1. A keyboard device for an electronic keyboard instrument, the keyboard device comprising: a swingable key; a hammer that has a pressing surface having a predetermined shape and that rotates while following a circular arc locus in response to depression of the key; and a key switch to detect key depression information on the key, the key switch comprising: a substrate on which a plurality of stationary contacts are disposed; a hollow switch body that has a to-be-pressed surface, that is made of an elastic material, and that is attached to the substrate so as to cover the plurality of stationary contacts; and a plurality of movable contacts that are disposed inside the switch body, that respectively face the plurality of stationary contacts with mutually different intervals, and that respectively come into contact with the plurality of stationary contacts in order when the switch body is pressed by the hammer in response to depression of the key, wherein the pressing surface and the to-be-pressed surface have relatively-concaved shapes in a longitudinal direction of the hammer, wherein the relatively-concaved shape is a shape in which the to-be-pressed surface and the pressing surface become loose at a center therebetween when the to-be-pressed surface and the pressing surface a fitted together, and an inclination caused by an overall curvature of the switch body that results from the fact that the switch body is pressed by the hammer from an oblique direction after the hammer begins to come into contact with the switch body is canceled by an inclination of the switch body caused by partial compression and deformation that results from the relatively-concaved shapes when the switch body is pressed by the hammer, so that the plurality of movable contacts frontally face the plurality of stationary contacts and come into contact with the plurality of stationary contacts, respectively.

2. The keyboard device for an electronic keyboard instrument according to claim 1, wherein the pressing surface wholly come into close contact with the to-be-pressed surface before the plurality of movable contacts come into contact with the plurality of stationary contacts, respectively.

3. The keyboard device for an electronic keyboard instrument according to claim 1, wherein the plurality of movable contacts are three or more in number, and the plurality of stationary contacts are three or more in number.

4. The keyboard device for an electronic keyboard instrument according to claim 2, wherein the plurality of movable contacts are three or more in number, and the plurality of stationary contacts are three or more in number.

5. The keyboard device for an electronic keyboard instrument according to claim 1, wherein the hammer has ribs on a side of the switch body.

6. The keyboard device for an electronic keyboard instrument according to claim 2, wherein the hammer has ribs on a side of the switch body.

7. The keyboard device for an electronic keyboard instrument according to claim 3, wherein the hammer has ribs on a side of the switch body.

8. The keyboard device for an electronic keyboard instrument according to claim 4, wherein the hammer has ribs on a side of the switch body.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a sectional side view that shows an embodiment of a keyboard device for an electronic keyboard instrument of the present invention and that shows a case in which the electronic keyboard instrument is an electronic piano and is in a key-off state in which the key is not depressed.

(2) FIG. 2 is an enlarged, sectional side view that shows a hammer, a key switch, and its peripheral portion of the keyboard device of FIG. 1 and that shows a state when the hammer begins to come into contact with the key switch in response to the rotation of the hammer.

(3) FIG. 3 is an enlarged, sectional side view that shows the hammer, the key switch, and its peripheral portion of the keyboard device of FIG. 1 and that shows a state when a front-end side of the hammer comes into contact with the key switch in response to the rotation of the hammer.

(4) FIG. 4 is an enlarged, sectional side view that shows the hammer, the key switch, and its peripheral portion of the keyboard device of FIG. 1 and that shows a state when a pressing surface of the hammer comes into close contact with a to-be-pressed surface of the key switch and when the hammer presses the key switch as a whole.

(5) FIG. 5 is a descriptive view showing a positional relationship between a hammer and a key switch in a conventional key touch sensing configuration.

(6) FIG. 6 is a descriptive view showing a positional relationship between a hammer and a key switch in a configuration in which the hammer has ribs.

(7) FIG. 7 is an enlarged, sectional side view that shows a hammer, a key switch, and its peripheral portion of a conventional keyboard device and that shows a state when the hammer rotating while following a circular arc locus begins to come into contact with the key switch.

(8) FIG. 8 is an enlarged, sectional side view that shows a hammer, a key switch, and its peripheral portion of a conventional keyboard device and that shows a state when a switch body pressed by the hammer curves as a whole and is inclined, and hence movable contacts of the switches in the switch body obliquely come into contact with stationary contacts, respectively.

DESCRIPTION OF EMBODIMENTS

(9) The present invention will be hereinafter described with reference to FIG. 1 to FIG. 4. In FIG. 1 to FIG. 4, the same reference sign is given to a component that is equivalent to or corresponds to each component shown in FIG. 5 to FIG. 8.

(10) FIG. 1 is a sectional side view that shows an embodiment of a keyboard device for an electronic keyboard instrument of the present invention and that shows a case in which the electronic keyboard instrument is an electronic piano and is in a key-off state in which the key is not depressed.

(11) As shown in FIG. 1, a keyboard device 1 includes a hammer 2, a key switch 3, a key 4, and a keyboard chassis 5. The hammer 2 is rotatably attached to the keyboard chassis 5, and the key 4 is swingably attached to the keyboard chassis 5. For example, eighty-eight keys each of which is the key 4 (white key 4a, black key 4b) are disposed in a direction of its arrangement (in a direction perpendicular to the plane of paper). A set of the hammer 2 and the key switch 3 is provided for the single white key 4a, and a set of the hammer 2 and the key switch 3 is provided for the single black key 4b.

(12) Although a configuration with respect to the white key 4a will be described hereinafter, the same applies to a configuration with respect to the black key 4b.

(13) The keyboard chassis 5 consists of a front chassis 11, an intermediate chassis 12, and a rear chassis 13. The chassis 11 to 13 are each made, for example, by injection molding of a synthetic resin (e.g., ABS resin), and are connected together by means of ribs that extend in a front-rear direction, and are fixedly placed on a key bed of the electronic piano through front, intermediate, and rear mounting rails 14 to 16 that extend in a right-left direction (in a direction in which the keys are arranged).

(14) The front chassis 11 has two right and left engagement holes 11a passing through the front chassis 11 in an up-down direction that are bored for each white key 4a, and a key stopper 11b made of felt or the like is attached to a lower surface of a front-side portion of the engagement holes 11a.

(15) The intermediate chassis 12 is provided with a shaft-shaped hammer fulcrum 12a that supports the hammer 2 and that protrudes both rightwardly and leftwardly.

(16) The rear chassis 13 is provided with a shaft-hole-shaped key fulcrum 13a that supports the white key 4a, and a hammer stopper 13b made of felt or the like is attached to a lower surface of a rear-side portion of the key fulcrum 13a.

(17) The white key 4a is formed in a hollow shape that is open downwardly, for example, by injection molding of a synthetic resin (e.g., AS), and extends forwardly. A rear end portion of the white key 4a is provided with a fulcrum shaft 17 that protrudes both rightwardly and leftwardly, and the white key 4a is swingably supported by the rear chassis 13 by allowing the fulcrum shaft 17 to engage the key fulcrum 13a.

(18) A left-right pair of hook portions 18 are disposed at a front end portion of the white key 4a, and the hook portions 18 extend downwardly from left and right sidewalls through the engagement holes 11a of the front chassis 11, respectively, and bend forwardly from a lower end of each engagement hole 11a.

(19) In the key-off state of the white key 4a, the hook portion 18 is brought into contact with the key stopper 11b of the front chassis 11 from below, and an upper limit position of the white key 4a is restrained. An actuator portion 19 protruding downwardly is disposed on a lower surface of the white key 4a, at a more rearward position than the hook portion 18.

(20) The hammer 2 is composed of a hammer body 2a and a weight 20 attached to the hammer body 2a. The hammer body 2a is made, for example, by injection molding of a synthetic resin (e.g., POM (polyacetal)), and extends in the front-rear direction, and has a U-shaped shaft hole 2e that is open downwardly at a position slightly in front of a center of the hammer body 2a. The hammer 2 is rotatably supported by the intermediate chassis 12 by allowing the shaft hole 2e to engage the hammer fulcrum 12a.

(21) An engagement concave portion 2f that is open upwardly and forwardly is formed at a more forward side than the shaft hole 2e of the hammer body 2a. The actuator portion 19 of the white key 4a is housed in the engagement concave portion 2f, and is brought into contact with a bottom of the engagement concave portion 2f. A switch pressing portion 2c to press the key switch 3 is formed on the key-switch side of the engagement concave portion 2f of the hammer body 2a, and has a convex pressing surface 2b that is gently curved downwardly.

(22) One side of a rear half portion of the hammer body 2a is a weight-attached portion 2g, to which the weight 20 is detachably attached. The weight 20 is made of a metallic plate of, for example, iron that is larger in specific gravity than the hammer body 2a, and is formed in a predetermined shape by, for example, press working. The weight 20 extends in the front-rear direction, and is attached to the weight-attached portion 2g of the hammer body 2a in its front half portion, and protrudes rearwardly from the weight-attached portion 2g, and extends to the vicinity of a rear end of the rear chassis 13.

(23) The key switch 3 includes a printed circuit board (substrate) 6 and a switch body 3 attached to the printed circuit board 6 with respect to the white key 4. The printed-circuit board 6 has a front end portion screwed to the front chassis 11 in a state in which its rear end portion is inserted in the intermediate chassis 12, and the printed circuit board 6 extends in the right-left direction while inclining forwardly and downwardly.

(24) FIG. 2 to FIG. 4 are enlarged, sectional side views, each showing the hammer 2, the key switch 3, and its peripheral portion of the keyboard device 1 of FIG. 1.

(25) Herein, FIG. 2 shows a state when the hammer 2 begins to come into contact with the key switch 3 in response to the rotation of the hammer 2, and FIG. 3 shows a state when the front-end side of the hammer 2 comes into contact with the key switch 3, and FIG. 4 shows a state when the hammer 2 wholly comes into close contact with the key switch 3 and presses the key switch 3. In the key-off state of the white key 4a, the hammer 2 is away from the key switch 3 and is above the key switch 3.

(26) As shown in FIG. 2 to FIG. 4, the switch body 3a of the key switch 3 is formed in a hollow dome shape that is open downwardly with an elastic material, such as rubber, and integrally has a to-be-pressed portion having a to-be-pressed surface 3b and a peripheral wall portion 3d.

(27) A plurality of bosses 3e are formed on a lower surface of the peripheral wall portion 3d, and the switch body 3a is attached to the printed circuit board 6 by inserting the bosses 3e into engagement holes of the printed circuit board 6. An upper surface of the switch body 3a of the key switch 3 is the to-be-pressed surface 3b that is pressed by the switch pressing portion 2c of the hammer 2.

(28) Hereinafter, the to-be-pressed surface 3b of the to-be-pressed portion of the switch body 3a of the key switch 3 is referred to simply as the “to-be-pressed surface 3b,” and the pressing surface 2b of the switch pressing portion 2c of the hammer 2 is referred to simply as the “pressing surface 2b.”

(29) The to-be-pressed surface 3b and the pressing surface 2b are not identical in shape with each other although conventional ones are identical in shape with each other, and the to-be-pressed surface 3b and the pressing surface 2b have relatively-concaved shapes in a longitudinal direction of the hammer 2 (i.e., direction in which the fulcrum and the front end of the hammer 2 are connected together). The term “relatively concaved shape” denotes a shape in which the to-be-pressed surface 3b and the pressing surface 2b become loose at a center therebetween when the to-be-pressed surface 3b and the pressing surface 2b are fitted together.

(30) First to third switches 3c-1 to 3c-3 for the single white key 4a are disposed in the switch body 3a, and respectively have first to third stationary contacts 3g-1 to 3g-3 formed on an upper surface of the printed circuit board 6 with predetermined intervals between the first to third switches 3c-1 to 3c-3 in order of distance away from the side closest to the hammer fulcrum 12a. The first to third stationary contacts 3g-1 to 3g-3 are covered with the switch body 3a.

(31) First to third attaching portions 3f-1 to 3f-3 that extend toward the printed-circuit-board-6 side integrally with the switch body 3a are disposed inside the to-be-pressed surface 3b of the switch body 3a, and the first to third switches 3c-1 to 3c-3 are each made of an elastic material, such as rubber, in the same way as the switch body 3a, and are formed so that the first attaching portion 3f-1 is slightly longer than the second attaching portion 3f-2 and so that the second attaching portion 3f-2 is slightly longer than the third attaching portion 3f-3.

(32) First to third movable contacts 3h-1 to 3h-3 are attached to front ends of the first to third attaching portions 3f-1 to 3f-3, respectively, and the first to third movable contacts 3h-1 to 3h-3 face the first to third stationary contacts 3g-1 to 3g-3 from above so as to be paired with the first to third stationary contacts 3g-1 to 3g-3, respectively.

(33) The first switch 3c-1 consists of the first movable contact 3h-1 and the first stationary contact 3g-1, and the second switch 3c-2 consists of the second movable contact 3h-2 and the second stationary contact 3g-2, and the third switch 3c-3 consists of the third movable contact 3h-3 and the third stationary contact 3g-3.

(34) Intervals between the first to third movable contacts 3h-1 to 3h-3 and the first to third stationary contacts 3g-1 to 3g-3 become larger in order of the first switch 3c-1, the second switch 3c-2, and the third switch 3c-3 by determining the lengths of the first to third attaching portions 3f-1 to 3f-3 as mentioned above. Therefore, in response to the rotation of the hammer 2, the first movable contact 3h-1 first comes into contact with the first stationary contact 3g-1, and then the second movable contact 3h-2 comes into contact with the second stationary contact 3g-2, and last the third movable contact 3h-3 comes into contact with the third stationary contact 3g-3.

(35) Next, the operation of the keyboard device 1 of FIG. 1 will be described.

(36) In the keyboard device 1, the hammer 2 is inclined rearwardly and downwardly because of the gravitational weight of the weight 20 as shown in FIG. 1 when the white key 4a is in a key-off state.

(37) The white key 4a swings in a counterclockwise direction of FIG. 1 in response to depression of the white key 4a, and the actuator portion 19 pushes the bottom of the engagement concave portion 2f of the hammer 2 downwardly, and the hammer 2 rotates in the counterclockwise direction.

(38) The hammer 2 rotates while following the circular arc locus centering on the hammer fulcrum 12a, and hence is first brought into contact with the switch body 3a at the first-movable-contact-3h-1 side close to the hammer fulcrum 12a. FIG. 2 shows a state at this time.

(39) When the hammer 2 further rotates in accordance with the depression stroke of the depression of the white key 4a, a part of the switch body 3a at the first-movable-contact 3h-1 side is chiefly pressed by the hammer 2, and is compressed and deformed, and is inclined inwardly because the pressing surface 2b and the to-be-pressed surface 3b have relatively-concaved shapes in the longitudinal direction of the hammer 2.

(40) This partial inclination of the switch body 3a cancels an inclination caused by the overall curvature of the switch body 3a that results from the fact that the switch body 3a is pressed by the hammer 2 from an oblique direction, and, when the first movable contact 3h-1 comes into contact with the first stationary contact 3g-1, the first movable contact 3h-1 frontally faces the first stationary contact 3g-1 and then comes into contact therewith. Hence, it is possible to allow the first movable contact 3h-1 to frontally face the first stationary contact 3g-1 and then come into contact therewith at an early stage of the depression stroke when the white key 4a is depressed.

(41) When the hammer 2 further rotates in accordance with the depression stroke of the depression of the white key 4a, the front-end side of the hammer 2 also comes into contact with the key switch 3 at the third-movable-contact 3h-3 side farther from the hammer fulcrum 12a. A center portion between the fulcrum side and the front-end side of the hammer 2 does not come into contact with the key switch 3 because the pressing surface 2b and the to-be-pressed surface 3b have relatively-concaved shapes in the longitudinal direction of the hammer 2. FIG. 3 shows a state at this time.

(42) When the hammer 2 further rotates in accordance with the depression stroke of the depression of the white key 4a, a part of the switch body 3a at the third-movable-contact 3h-3 side is pressed and is then compressed and deformed, and is partially inclined outwardly.

(43) When the hammer 2 further rotates in accordance with the depression stroke of the depression of the white key 4a, the pressing surface 2b comes into close contact with the to-be-pressed surface 3b, and the hammer 2 presses the key switch 3 as a whole. FIG. 4 shows a state in which the pressing surface 2b comes into close contact with the to-be-pressed surface 3b, and the hammer 2 then presses the key switch 3 as a whole, and the second movable contact 3h-2 comes into contact with the second stationary contact 3g-2.

(44) Although the third movable contact 3h-3 has not yet come into contact with the third stationary contact 3g-3 in the state shown in FIG. 4, the third movable contact 3h-3 will come into contact with the third stationary contact 3g-3 if the hammer 2 further rotates in accordance with the depression stroke of the depression of the white key 4a.

(45) The interval between the first movable contact 3h-1 and the first stationary contact 3g-1, the interval between the second movable contact 3h-2 and the second stationary contact 3g-2, and the interval between the third movable contact 3h-3 and the third stationary contact 3g-3 become larger in this order as described above, and therefore the first movable contact 3h-1, the second movable contact 3h-2, and the third movable contact 3h-3 come into contact with the first stationary contact 3g-1, the second stationary contact 3g-2, and the third stationary contact 3g-3 in this order.

(46) Likewise, in a process in which the second movable contact 3h-2 comes into contact with the second stationary contact 3g-2, and furthermore the third movable contact 3h-3 comes into contact with the third stationary contact 3g-3 in accordance with the depression stroke of the depression of the white key 4a as shown in FIG. 4, the switch body 3a is partially compressed and deformed, and is inclined when the switch body 3a is pressed by the hammer 2 because the pressing surface 2b and the to-be-pressed surface 3b have relatively-concaved shapes in the longitudinal direction of the hammer 2, and this inclination cancels an inclination caused by the overall curvature of the switch body 3a that results from the fact that the switch body 3a is pressed by the hammer 2 from an oblique direction, and, when the second movable contact 3h-2 and the third movable contact 3h-3 come into contact with the second stationary contact 3g-2 and the third stationary contact 3g-3, respectively, these movable contacts frontally face these stationary contacts, and come into contact therewith, respectively.

(47) Thereafter, when a rear end portion of the hammer 2 is brought into contact with the hammer stopper 13b, the rotation of the hammer 2 is stopped.

(48) On the other hand, when the white key 4a is released from being depressed, the hammer 2 rotates in a clockwise direction of FIG. 1. The white key 4a is pushed up through the actuator portion 19, and swings in the clockwise direction in response to the rotation of the hammer 2, and the hook portion 18 is brought into contact with the key stopper 11b, and the swing of the white key 4a is stopped. Hence, the white key 4a and the hammer 2 return to the key-off state of the white key 4a as shown in FIG. 1.

(49) Although FIG. 2 to FIG. 4 show that the first movable contact 3h-1 comes into contact with the first stationary contact 3g-1 before the pressing surface 2b of the hammer 2 wholly comes into close contact with the to-be-pressed surface 3b of the key switch 3, it is also preferable to allow the pressing surface 2b of the hammer 2 to wholly come into close contact with the to-be-pressed surface 3b of the key switch 3 before the first movable contact 3h-1 comes into contact with the first stationary contact 3g-1. In this case, it is possible to make the switch body 3a stable by wholly bringing the pressing surface 2b into close contact with the to-be-pressed surface 3b, and therefore it is possible to make constant the depression stroke until the first to third movable contacts 3h-1 to 3h-3 come into contact with the first to third stationary contacts 3g-1 to 3g-3, respectively, regardless of the key depression speed.

(50) Although the embodiment of the present invention has been described as above, the present invention is not limited to the aforementioned embodiment, and can be embodied in various modes within the range of the technical thought of the present invention.

(51) For example, although the electronic keyboard instrument is an electronic piano in the aforementioned embodiment, the present invention is effective even in a case in which any electronic keyboard instrument except the electronic piano is used.

(52) Additionally, the key switch is merely required to have a plurality of switches, and the effect of the present invention can be more excellently fulfilled if the key switch has three switches or more.

(53) Additionally, the hammer may have ribs as shown in FIG. 6, and the pressing surface of the hammer or the to-be-pressed surface of the key switch is merely required to have a relatively-concaved shape in the longitudinal direction of the hammer, and its shape is arbitrary as far as it goes. Additionally, although the key switch is placed below the hammer in FIG. 1 to FIG. 4, the disposition or configuration of those components is also arbitrary. Besides, detailed configurations of the keyboard device can be appropriately changed.

REFERENCE SIGNS LIST

(54) 1 . . . keyboard device, 2 . . . hammer, 2a . . . hammer body, 2b . . . pressing surface, 2c . . . switch pressing portion, 2d . . . rib, 2e . . . shaft hole, 2f . . . engagement concave portion, 2g . . . weight-attached portion, 3 . . . key switch, 3a . . . switch body, 3b . . . to-be-pressed surface, 3c-1˜3c-3 . . . switch, 3d . . . peripheral wall portion, 3e . . . boss, 3f-1˜3f-3 . . . attaching portions, 3g-1˜3g-3 . . . stationary contact, 3h-1˜3h-3 . . . • movable contact, 4 . . . key, 4a . . . white key, 4b . . . black key, 5 . . . keyboard chassis, 6 . . . printed circuit board, 11 . . . front chassis, 11a . . . engagement hole, 11b . . . key stopper, 12 . . . intermediate chassis, 12a . . . hammer fulcrum, 13 . . . rear chassis, 13a . . . key fulcrum, 13b hammer stopper, 14˜16 . . . mounting rail, 17 . . . fulcrum shaft, 18 . . . hook portion, 19 . . . actuator portion, 20 . . . weight.