CN1034449C

CN1034449C - Keyboard assembly for electronic musical instrument

Info

Publication number: CN1034449C
Application number: CN95102652A
Authority: CN
Inventors: 吉永宪市; 三岛顺一
Original assignee: Yamaha Corp
Current assignee: Yamaha Corp
Priority date: 1992-08-10
Filing date: 1995-03-08
Publication date: 1997-04-02
Anticipated expiration: 2013-08-10
Also published as: CN1114765A; CN1086035A; CN1032169C

Abstract

To shorten a rolling reduction cycle for one slab in the width rolling reduction of the slab. A front part pressing surface 10b and a rear part pressing surface 10c sloped to the front side and the rear side of a center pressing surface 10a are arranged in one die 10, respectively. While travelling the slab 8, a preform to the front end part of the slab 8 is executed by the pressing surfaces 10b and 10a by changing a shifting stroke of the die 10. When the preform to the slab front end part completes, the ordinary width rolling reduction is executed by the die 10. When the rear end part of the slab 8 comes in, the preform to the rear end part of the slab is executed by the pressing surfaces 10c and 10a by changing the opening degree of the die 10.

Description

Keyboard device for electronic musical instrument

The present invention relates to a keyboard apparatus for an electronic musical instrument such as an electronic piano.

According to the general structure of a conventional keyboard used in an electronic musical instrument, a plurality of keys, key switches, key stoppers, key guides, and the like are supported by a key frame fixed to the instrument main body, and each of the keys is supported by the key frame so that it can freely rotate about a predetermined fulcrum. On the key frame, a key switch connected to the key is provided. When each key is pressed, the corresponding key switch is actuated, thereby generating a key-on signal.

Fig. 1 shows a cross-sectional view of the mechanical structure of the keyboard apparatus. A key guide 11 is provided at the front edge portion of the key frame 8, and functions to prevent lateral swinging or twisting that may occur when a certain key is pressed. The key frame 8 is made of a rectangular metal plate. The top edge portion of the key frame 8 is bent and the bent portion of the frame is covered with a resin film to finally form the key guide piece 11. Or the bent portion of the key frame itself is made of resin, and then the bent portion of the key frame in contact with the key is covered with a flexible resin, so that the key guide piece 11 will eventually become a part of the key frame. The key switch 10 is mounted on the circuit board 81 to form a switching circuit device. The switching circuit arrangement is firmly fixed to the key frame 8 by means of screws 82. The key switch 10 includes a projection member made of an elastic material such as rubber. When the key is pressed, the stopper 6 connected to the lower surface of the key 1 presses the projection member of the key switch 10 downward to deform the projection member. In this way, a plurality of internal contacts (not shown) of the key switch 10 are brought into contact with each other, so that the key switch 10 is turned on.

The guide member 4 is formed as a part of the key 1 and protrudes from the lower surface of the key 1. When the key 1 is pressed, the guide member 4 slides down under the guide of the key guide piece 11 of the key frame 8. The braking member 5 is formed as a part of the guide member 4. When the key 1 is returned from the depressed position, the stopper member 5 comes into contact with the key guide piece 11, thereby forming an upper limit stopper with respect to the key 1. Incidentally, the member 3 is designated as a black key. The key 1, i.e. the white key, has a projecting portion 7 projecting downwardly from the common base edge portion 2. The common base edge portion is provided at a trailing edge portion of the key. The convex portion 7 is inserted into a hole 9 formed at a predetermined rear edge portion of the key frame 8, and then the key 1 and the key frame 8 are fixed by a screw 83.

When the key 1 and the key frame 8 are assembled together, the projecting portion 7 of the key 1 is temporarily mounted on the key frame 8, and then the key 1 is slid on the key frame 8 in the horizontal direction so that the guide member 4 is engaged with the key guide piece 11, and thereafter, the projecting portion 7 is fitted into the hole 9. As described above, due to the shape of the guide member 4, the key 1 should slide in the horizontal direction on the key frame 8. In other words, the stopper 5 horizontally extends from the guide member 4 in the opposite direction (i.e., the left direction of fig. 1). Thus, in order to make the guide member 4 having a shape similar to the letter L fit with the key guide piece 11, the key should be horizontally moved in the opposite direction just before the keyboard apparatus is assembled together.

In assembling the conventional keyboard apparatus, some lower surface portions of the keys 1 and the driver 6 are horizontally moved with respect to the key switches 10 which project from the key frame 8 while being in contact with each other, and then they are fixed together. Due to this fixing manner, the key switch 10 may be deformed in the horizontal direction in some cases. If the key 1 and the key frame 8 are fixed together in such a fixed manner, the key switch 10 does not function well, which makes it impossible to fully perform the function of the key switch 10. In order to overcome the aforementioned deformation caused by the force generated in the horizontal direction when the key 1 and the key frame 8 are fixed together, the conventional art provides some countermeasures by which the thickness of the rubber wall of the key switch 10 is increased or the hardness of the rubber used is reinforced, or for the same purpose, it is necessary to fix the key switch 10 to the key frame 8 with a strong force. Another counter-measure is disclosed in us patent 4,914,999, where the key is moved vertically down to the key frame, and then the key is inserted to be attached to the key frame. For this reason, a valve-like structure for the special design of the key frame, key switch and circuit groove is provided so that the stopper member 5 can smoothly move down along the key guide piece 11 when the key and key frame are fixed together.

However, if the thickness of the rubber wall of the key switch 10 is increased or the key switch 10 is made of hard rubber as described above, the key-down sensitivity will be lowered. In order to securely connect the key switch and the key frame together, the number of fixing members for fixing the key switch and the key frame together and the number of steps taken should be increased. In addition, when fixing the key and the key frame together, the worker should pay special attention not to touch the key switch with the part of the key. Such a complicated fixing operation requires many man-hours or requires a high manual skill of a worker.

In the aforementioned technique disclosed in the above-mentioned us patent, the structure of the key unit and the key frame unit is complicated, and when a key frame is formed, a complicated process is required. In addition, the actuator element also passes through a valve-like portion when the key and the key frame are secured together. Such an operation is required for each of all the keys. Thus. This disclosed technique suffers from its complexity.

It is, therefore, a primary object of the present invention to provide a keyboard apparatus for an electronic musical instrument, in which the key switches are prevented from being deformed by applying an external force to the key switches when the keys and the key frame are assembled together.

According to the basic structure of the keyboard apparatus defined by the present invention, it comprises a key, a key frame, a key-down sensor, a driver and a key guide piece. The fixed portion of the key is supported by the key frame so that the front portion of the key can freely rotate upward and downward. The driver is attached to a lower surface of the key, and the key-down sensor is attached to the key frame. When the key is pressed down, the driver drives the key-down sensor, so that a key-down situation is sensed. The key-down sensor may be designed as a key switch having a convex portion made of an elastic material. Thus, when the key is depressed, the driver presses and partially deforms the raised portion of the key switch, thereby causing the key to turn on.

When the key and the key frame are assembled together, the key is guided by the guide piece so that the driver does not directly contact the key switch when the key is moved in the length direction of the key. Thus, it is possible to avoid the application of the external force to the key switch during the assembly work of assembling the key and the key frame together.

Other objects and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings in which a preferred embodiment of the invention is shown. Wherein,

fig. 1 is an assembly view showing an assembly operation carried out between a key unit and a key frame unit in a conventional keyboard apparatus;

fig. 2 is an assembly view showing an assembly operation to be performed between a key unit and a key frame unit in the keyboard apparatus according to the first embodiment of the present invention;

FIG. 3(A) is a side perspective view showing details of a key guide tab;

FIG. 3(B) shows the shape of one brake element;

fig. 4(a) shows another example of the key guide piece;

FIG. 4(B) shows another example of the brake element;

FIG. 5(A) is a side perspective view showing the detailed structure of a device guide member;

FIG. 5(B) shows another example of the device guide member;

FIGS. 6(A) -6(D) illustrate steps of an assembly process for assembling the keyboard apparatus according to the first embodiment of the present invention;

FIGS. 7(A) -7(B) show another example of steps for performing an assembly process for the keyboard apparatus;

FIG. 8 is a sectional view showing another example of the keyboard apparatus;

FIGS. 9(A) -9(C) illustrate assembly process steps for another example of the keyboard structure of FIG. 8;

FIGS. 10(A) -10(B) illustrate another example of assembly process steps for another example of the keyboard apparatus;

fig. 11 is a sectional view showing still another example of the keyboard apparatus;

fig. 12(a) -12(B) show different examples of the vertical direction assembly guide member used in the keyboard apparatus shown in fig. 11;

FIG. 13 illustrates an example use of a boss with a conically shaped assembly guide member;

FIG. 14 illustrates another use of the boss with a conically shaped assembly guide member;

fig. 15 is a plan view showing a shape of a guide groove and a hole formed in the key frame;

fig. 16(a) shows an insertion manner of inserting a boss into a hole on the key frame;

fig. 16(B) shows another example of the shapes of the guide groove and the hole formed in the key frame;

FIGS. 17(A) -17(F) illustrate steps of an assembly process for assembling the keyboard apparatus of FIG. 11;

FIGS. 18(A) -18(F) illustrate another example of assembly process steps performed to assemble the keyboard apparatus of FIG. 11;

FIG. 19 is an exploded side perspective view showing the assembly operation of the two key members together;

fig. 20 is a plan view showing a main body portion of a key frame used in the keyboard apparatus according to the second embodiment of the present invention;

fig. 21 is a side view showing an assembled state of the keyboard apparatus.

FIG. 22 is a side perspective view showing the key device and key frame not assembled together;

FIG. 23 is a side perspective view showing an example of the rear edge portion of the key device;

FIG. 24 is a cross-sectional view of the key device shown in FIG. 23;

FIGS. 25(A) -25(C) are side views showing an example of an assembly process for assembling the key device and the key frame together;

FIGS. 26(A) -26(D) are side views showing still another example of the assembly process;

fig. 27 is a side perspective view showing still another example of the key device;

fig. 28 is a side perspective view showing still another example of the key device;

FIG. 29 is a side perspective view showing an example of the key frame corresponding to the key device shown in FIG. 28;

FIG. 30 is a side perspective view showing yet another example of the key device and the key frame which are not assembled together;

fig. 31(a) -31(C) are side views showing one example of assembling steps for assembling the key device and the key frame shown in fig. 30 together;

FIG. 32 is a side view showing still another example of the keyboard apparatus;

FIG. 33 is an exploded view, particularly illustrating the trailing edge portions of a plurality of the key units assembled together;

FIG. 34 is a side view showing an example of a fixing plate for the keyboard apparatus shown in FIG. 30;

FIG. 35 is an exploded view showing three key units assembled together according to a third embodiment of the present invention;

fig. 36 is a partial view showing a main body portion of a keyboard apparatus according to a fourth embodiment of the present invention;

fig. 37 is a side view showing a main body portion of the keyboard apparatus according to a modification of the fourth embodiment of the present invention;

fig. 38 is a side view showing a main body portion of the keyboard apparatus according to another modification of the fourth embodiment of the present invention;

fig. 39 is a partial view showing a switching device according to a fifth embodiment of the present invention, which is used as the key switch associated with the keyboard apparatus;

fig. 40 is a side perspective view showing an example of the switching device in which a plurality of elastic protrusion members are arranged in series at a predetermined pitch;

fig. 41 is a partial view showing another switching device formed as a two-way contact type touch-responsive switch;

fig. 42 is a partial view showing an example of the keyboard apparatus in which the switching device is used as the key switch;

fig. 43 is a partial view showing another example of the switching device;

FIG. 44 is a partial view showing still another example of the switching device;

fig. 45 is a side view showing a keyboard apparatus according to a sixth embodiment of the present invention; and

fig. 46 is a side perspective view showing a main part of the keyboard apparatus according to the sixth embodiment of the present invention.

The preferred embodiments of the present invention will be described with reference to the accompanying drawings, in which like parts are designated by like reference numerals. [A] First embodiment

Fig. 2 is an assembly view showing a sectional view of the key unit and another sectional view of the key frame unit assembled together. All the keys used in the keyboard apparatus are classified into three groups, and three blocks are provided for the three groups of keys, respectively, the first block corresponding to a plurality of black keys arranged side by side on the keyboard, wherein one octave is provided with 5 black keys. The second block corresponds to a group of white keys, wherein every other one of the white keys corresponds to a white key to be selected from a row of white keys. The third block corresponds to another set of white keys which is not selected for the second block, and the three blocks are assembled together by jointly assembling the three common base edge portions 2a, 2b and 2c together. The white key 1 is provided with a projection 7 projecting downward from the lower surface of the common base edge portion 2 c. The common base edge portion 2c is provided at the rear edge portion of the key 1. The protrusion 7 is fitted into a hole 9 of the key frame 8 so that the key unit and the key frame unit are assembled together. A key guide piece 11 is provided at a front edge portion of the key frame 8 to prevent the key 1 from being swung or rotated laterally when pressed downward. In forming the key guide piece 11, the top edge portion of the key frame 8 made of a rectangular metal plate is bent, and then, the bent portion is covered with a resin film material, or the key frame 8 itself having a bent shape is made of the resin material, and then only the key contact portion thereof is covered with a flexible resin material, thereby forming the key guide piece 11. On the key frame 8, the key switch 10 is provided for each of a plurality of keys. As described above, the key switch 10 includes a convex portion made of an elastic material such as rubber. The convex portion is deformed by the pressing of the driver 6 when the key is pressed. Here, a movable contact is attached at the inner wall of the convex portion, and a stationary contact is provided at a position opposite to the movable contact within the key switch 10. Thus, when the key is pressed, the movable contact comes into contact with the stationary contact, thereby transmitting a key-on state. Therefore, on the print circuit groove connected to the lower surface of the key frame 8, the above-described convex portion is mounted. Therefore, the top edge portion of the projecting portion projects upward from the through hole provided in the key frame 8.

The guide member 4 is provided as a part of the key 1. The guide member 4 can slide up and down while being guided by the key guide pieces 11 of the key frame 8. A braking member 5 serving as an upper limit stopper of the key 1 serves as a lower edge portion of the guide member 4. When the pressed key returns to its original position, the detent member 5 comes into contact with the key guide piece 11.

Incidentally, reference numeral 3 designates a black key.

Fig. 3(a) shows an example of a detailed structure of the key guide piece 11. The key guide is mainly composed of a guide member 14 and a stopper member 15. The two side portions of the guide member 14 form guide surfaces by which the key can be moved up and down. The brake member 15 can be made as a large frame for a plurality of keys arranged in parallel. In addition, the key guide pieces 11 may be separately formed from the key frame 8. In this case, after the key guide piece 11 is manufactured, the key guide piece 11 is attached to the key frame by fitting the key frame top edge portion into a groove 15a formed in the stopper member 15 in the length direction thereof. At both lower edge portions of the guide member 14, slopes 16 are formed with which the guide member 4 can be smoothly guided by the guide member 14 or the guide member 4 can be smoothly assembled with the key guide piece 11.

The guide members 14 of the key guide pieces 11 are sandwiched by the guide members 4 of the keys 1. A taper 13 as shown in fig. 3(B) is formed at a top edge portion of the stopper member 5 formed as a lower edge portion of the guide member 4. The taper 13 helps the braking element 5 to smoothly connect with the guide member 14. When the key unit and the key frame unit are assembled together, the stopper member 5 is pressed against the guide member 14.

Fig. 4(a) shows another example of the key guide piece 11. In this example, a taper 17 is formed along a lower edge portion of the brake member 15. As shown in fig. 4(B), the braking element 5 of the guide member 4 is not provided with the taper 13 (see fig. 3 (B)). However, by providing the braking element 5 with said taper 13, the assembly operation can be made more gradual. In other words, by attaching the taper 17 to the stopper member 5, the assembling operation in which the stopper member 5 is pressed into the stopper member 15 can be performed smoothly.

During this time, an assembly guide member 12 is formed and will extend from a rib of the driver 6 which is projected downward from the inner wall of the key 1 as shown in fig. 5 (a). Fig. 5(a) and 5(B) are two side perspective views, each of which shows a detailed component of the device guide element 12. Incidentally, each of these two figures shows a main part of the interior of the key 1 in a case where it is shown upside down. Fig. 5(a) shows an example in which one transversely directed rib is provided for the driver 6, and fig. 5(B) shows another example in which two ribs are provided for the driver 6. In each of these two examples, the device guide member 12 extends lengthwise from the rib. The assembly guide member 12 is disposed at a position where the assembly guide member 12 is in contact with an upper edge portion of the key guide piece 11 of the key frame 8 when the key unit and the key frame unit are assembled together. Such an assembly guide member 12 does not have a function that the driver can press the key switch 10. In short, such an assembly guide member 12 has only a function of guiding the member when the assembly operation is performed.

Fig. 6(a) -6(D) show the corresponding steps associated with the keyboard assembly process. First, as shown in fig. 6(a), the projection 7 of the key 1 is fitted in the vicinity of the hole on the key frame 8 (see dotted line). At this time, the stopper element 5 of the guide member 4 is placed above the stopper member 15 of the key guide 11.

Next, as shown in fig. 6(B), the key 1 is pressed downward by rotating around the projection 7, and the projection 7 is used as a fulcrum. At this time, the top edge portion of the check member 5 will be slightly moved forward (i.e., in the right direction of the drawing) as compared with the previous position of the check member 5 shown in fig. 6 (a). Subsequently, the top edge portion of the detent element 5 will slide down along the front surface of the detent member 15 of the key guide 11.

By further pressing down the key 1, the upper surface of the detent element 5 eventually reaches one surface having the lower surface of the detent member 15 as shown in fig. 6 (C). At this time, the lower surface of the assembly guide member 12 is in contact with the highest portion of the guide member 14 of the key guide piece 11. In addition, the driver 6 is disposed above the upper surface away from the key switch 10. Therefore, in this state, the driver 6 is not in contact with the key switch 10 at all.

The key 1 can be slightly moved backward (i.e., in the left direction of the drawing) in a state where the assembly guide member 12 is in contact with the highest portion of the guide member 14 of the key guide 11. Therefore, as shown in fig. 6(D), the protrusion 7 is finally fitted into the hole of the key frame 8. Thus, the assembling work is completed. At this time, the stopper member 5 of the guide member 4 is placed at a position contacting with the lower surface of the stopper member 15, which is defined as an upper limit position to which the rising movement of the key 1 is restricted when it returns from the depressed position. Both the braking member 15 and the braking element 5 together constitute an upper limit brake for the key 1. In a state where the assembly guide member 12 is placed above the guide member 14 apart from the key guide piece 11, the assembly guide member 12 does not interfere with the downward movement of the key 1 when it is pressed downward. When the key 1 is pressed down, the driver 6 presses and deforms the key switch 10, thereby driving the key switch 10.

Fig. 7(a) -7(B) show another assembly process for the keyboard apparatus. The projection 7 of the key 1 is mounted on the key frame 8 at a position L apart from the position of the hole (see dotted line) as shown in fig. 7 (a). In this state, the key 1 is moved backward (i.e., in the left direction of the drawing), and its lower surface is slid to be in contact with the highest portion of the guide member 14. In the case where the highest portion of the guide member 14 reaches the root of the rib of the driver extending in the lengthwise direction of the key 1 as shown in fig. 7(a), the aforementioned distance L between the projection 7 and the hole becomes equal to the distance between the detent member 5 of the guide member 4 and the detent member 15 to be in contact with the detent member 5. In short, after the guide member 14 and the rib of the driver 6 are brought into contact with each other, the key 1 is moved in the horizontal direction by the distance L while sliding on the key frame 8.

From the state shown in fig. 7(a), the key 1 is further moved in the left direction, and the highest portion of the guide member 14 slides along the rib of the driver 6. Thus, the key 1 is moved leftward while being moved outward. Subsequently, the highest portion of the guide member 14 reaches the highest portion of the rib. In addition, as shown in fig. 7(B), the highest portion of the guide member 14 finally reaches the position of the device guide member 12.

If the key 1 continues to move leftward, the former state as shown in fig. 6(C) is obtained, and then, as shown in fig. 6(D), the key 1 is finally fixed with the key frame 8.

When the assembly process shown in fig. 7(a) and 7(B) is performed, the key 1 will move in the horizontal direction, and the guide member 14 will slide along the rib of the driver 6. For this reason, the rib extending in the longitudinal direction is not formed by a sharply rising angle. In other words, the ribs must be formed at an angle of gradual inclination.

Fig. 8 shows another example of the mechanical structure of the keyboard apparatus. Unlike the previous example, this keyboard device is designed to replace the aforementioned assembly guide member 12 with one device guide rib 18 arranged separately from the actuator 6.

Fig. 9(a) -9(C) show an assembly process of such a keyboard apparatus. First, as shown in fig. 9(a), the protrusion 7 of the key 1 is mounted at a position near the hole (indicated by a dotted line) of the key frame 8. The stopper element 5 of the guide member 4 is placed above the stopper member 15 apart from the key guide piece 11.

Then, as shown in fig. 9(B), and the key 1 is raised with rotation around the projection 7. At this time, the top edge portion of the braking member 5 is slightly moved forward (i.e., in the right direction of the drawing) as compared with the state shown in fig. 9 (a). Accordingly, the top edge portion of the stopper member 5 is slidingly rotated along the front surface of the stopper member 15 of the key guide 11.

By further moving the key 1 downward, the upper surface of the stopper element 5 reaches the lower surface of the stopper member 15 to be in contact therewith as shown in fig. 9 (C). At this time, the device guide rib 18 will come into contact with the highest portion of the guide member 14 of the key guide piece 11. In addition, the driver 6 is disposed above the upper surface away from the key switch 10. In this state, the driver 6 is not in contact with the key switch 10 at all.

With the device guide rib 18 in contact with the highest portion of the guide member 14 of the key guide piece 11, the key 1 moves backward (left direction in the drawing). Subsequently, as shown in fig. 8, the projection 7 is fitted into the hole of the key frame 8, thereby completing the assembling process. At this time, the braking element 5 of the guide member 4 is not in contact with the lower surface of the braking member 15. When the key 1 is returned from the depressed position, the contact point between them forms the upper limit of the key 1. In other words, the braking member 15 forms, together with the braking element 5, an upper limit brake for the key 1. In this state, the device guide rib 18 is disengaged from the guide member 14 of the key guide piece 11, so that the device guide rib 18 does not interfere with the key depression movement of the key 1. Thus, when the key 1 is depressed, the driver 6 presses and deforms the key switch 10, thereby driving the key switch 10.

Fig. 10(a) and 10(B) show an assembly process for the keyboard apparatus shown in fig. 8. As shown in fig. 10(a), the protrusion 7 is provided on the key frame 8 at a position apart from the hole position (indicated by a dotted line). In this state, the guide member 14 of the key guide piece 11 is in contact with the lower surface of the key 1. Subsequently, the key 1 is moved backward while the lower surface of the key 1 slides along the highest portion of the guide member 14. In the case where the guide member 14 reaches the root of the long rib portion of the device guide rib 18 as shown in fig. 10(a), the driver 6 does not reach the key switch 10, so that the driver 6 and the key switch 10 are away from each other.

Thereafter, the key 1 continues to move in the left direction, and the outermost part of the guide member 14 slides along the device guide rib 18. Therefore, as shown in fig. 10(B), the key 1 is moved in the left direction while being lifted.

By continuing to move the key 1 leftward, the highest portion of the guide member 14 reaches the highest portion of the device guide rib 18. Thus, the former assembled state as shown in fig. 9(C) can be obtained. Thereafter, the key 1 is moved as described above, so that the key 1 is finally assembled with the key frame 8 as shown in fig. 8.

When the assembly process shown in fig. 10(a) and 10(B) is performed, the key 1 is moved in the horizontal direction, and the guide member 14 slides along the device guide rib 18. For this reason, the long rib portion of the device guide rib 18 is not formed at a steeply rising angle, and in short, must be formed at an angle that is gradually inclined.

In the foregoing example, a keyboard apparatus is designed such that its guide member 14 and the assembly guide member 12 or the assembly guide rib 18 are in contact with each other. However, it is possible to modify these examples so that the position of the guide member 14 is moved to other directions than the lengthwise direction of the key 1. In this case, a protruding element specifically designed to come into contact with the assembly guide member 12 or the assembly guide rib 18 may be provided at a position where the guide member 14 was previously provided.

Fig. 11 shows yet another example of the keyboard apparatus. As described above, one black key block 21 and two white key blocks 22, 23, which correspond to a plurality of black keys, are aggregated to form one key device. The key blocks are grouped together so that all of the keys can be arranged side-by-side on the keyboard. Fig. 11 shows only one white key 1 and one black key 3, however, it is a practical case that a plurality of white keys and a plurality of black keys are arranged side by side on the keyboard.

In order to avoid contact between the driver 6 (connected to the key 1) and the key switch 10 (provided on the key frame 8 1) when the key unit and the key frame unit are combined, the assembly guide member 12 is provided in the manner described in the foregoing example, which also provides a reinforcing rib 20 extending laterally, at the top edge portion of the key frame 8, a key depression guide member 14 (i.e., guide member 14) is provided, which guide member 14 guides the key 1 in the vertical direction (i.e., key depression direction 1) when the key 1 is depressed, and in addition, an upper limit stopper (i.e., stopper member) 5 is provided for the key 1.

In the present example, a hollow cylindrical wire housing 24 is provided to project downward from the common base edge portion of the white key block 23 at the lowermost position of the aforementioned key device. The thread sleeve 24 may correspond to the aforementioned protrusion 7. A vertical direction assembly guide member 25 is formed by the wire housing 24 along the long axis direction of the wire housing. The assembly guide member 25 has a skirt-like (or taper-like) shape such that its root portion is relatively small and its edge portion is relatively wide. The purpose of the assembly guide member 25 is to avoid an event in which the driver 6 is roughly moved vertically downward from the above-mentioned position of the key switch 10 when the key blocks 21, 22 and 23 (i.e., key devices) are attached to the key frame 8, thereby enabling an external force to be applied to the key switch 10 in the horizontal direction.

As described above, when the key unit and the key frame unit are assembled together, the key 1 is moved in both the horizontal and vertical directions, and then, the key 1 is rotated about the fulcrum, that is, the projection 7 provided at the top edge portion of the key 1, and finally the projection 7 is fitted into the hole 9 of the key frame 8 (see fig. 2), thereby completing the assembling operation (see fig. 6(a) -10 (B)). The above-mentioned complicated assembly movement of the key 1 is necessary for partially bending the upper limit stopper 5 and then placing it under the key frame 8. In other words, it is impossible to simply move the key 1 so that the protrusion 7 is vertically moved to be fitted into the hole 9 of the key frame 8. Just before the projection 7 is fitted into the hole 9 of the key frame 8, the driver 6 connected to the key 1 is located just above the key switch 10. Before this state is reached, the driver 6 is prevented from coming into contact with the key switch 10 due to the action of the assembly guide elements 12 or the assembly guide ribs 18 acting in the horizontal direction. In this way, it is possible to avoid the external force from acting laterally on the key switch 10 when the assembly operation is performed. As a result, it is possible to improve the reliability of the function of the key switch 10 after the key unit is completely assembled with the key frame unit.

Meanwhile, when the projection 7 is inserted into the hole 9 of the key frame 8, the key 1 is rotated around the upper limit stopper 5 with the upper limit stopper 5 placed under the key depression guide 14 provided for the key frame 8. At this time, the projection 7 moves downward while its side surface slides to come into contact with the edge portion of the hole 9. According to the insertion process of the projection 7 into the hole 9, the projection 7 is moved to be close to the hole 9, and thus, the key 1 is moved in a lateral (or horizontal) direction. Due to this movement of the key 1, the driver 6 finally slightly applies an external force to the key switch 10 in the horizontal direction.

The present example is provided to avoid the above phenomenon that when the projection 7 is finally fitted into the hole 9 on the key frame 8, the driver 6 will roughly move vertically downward from the above position of the key switch 10, resulting in the external force being applied laterally to the key switch 10. Therefore, this example can improve the reliability of the performance of the key switch 10.

Specifically, the wire case 24 connected to the key block 23 provides a vertical direction assembly guide member 25 having a similar taper shape, and the wire case 24 is lowered while a tapered edge portion of the assembly guide member 25 slides along an edge portion 30a of the hole 30 formed at a certain position of the key frame 8. In the case where the tapered portion 13 of the upper limit stopper 5 is placed under the key depression guide 14 of the key frame 8, when the key block 23 is turned around the rotation center corresponding to the upper limit stopper 5, the structure having the assembly guide member 25 having a similar taper acts so that the same distance is maintained between the rotation center and the tapered edge portion of the assembly guide member 25. Thus, the root portion, which is similar to the cone, is designed to be small, in other words, the cone-shaped edge portion of the assembly guide member 25 constitutes a part of an annular slider when the key block 23 is rotated about the center of rotation. The wire sleeve 24 is inserted into the hole 30 of the key frame 8 by moving along the tapered edge portion. Since the same distance is maintained between the rotation center and the tapered edge portion of the assembly guide member 25 when the key block is rotated about the rotation center, even if the insertion of the wire housing into the hole 30 in coordination with the rotation does not cause any force, no force is applied to the block 23, and the key block 23 is not moved toward the hole 30. Therefore, the driver 6 connected to the key 1 will be roughly moved vertically downward from a position above the key switch 10 provided on the key frame 8, but no force will act laterally on the key switch 10 during the downward movement of the driver 6.

Fig. 12(a) and 12(B) are two side perspective views each showing the shape of the assembly guide member 25. In these figures, the illustrated wire sleeve 24 is reversed as compared to that shown in fig. 11. Fig. 12(a) shows an assembly guide member 25 constituted by a rib-shaped thin plate member. A lower rim portion 25a extends from the plane of the rim portion of the boss 24 to guide the boss 24 horizontally toward the hole 30 before inserting the boss 24 into the hole 30. The lower edge portion 25a will slide into a hole 29 (which will be described later in connection with fig. 15 and 16). In addition, an auxiliary member 25b works to widen the tapered guide surface to ensure a guiding operation for the wire cover 24 and smoothly perform a horizontal guiding operation (which will be described later). The auxiliary element 25b may extend along the entire length of said tapered edge portion.

Fig. 12(B) shows another example of the assembly guide member 25, the assembly guide member 25 being configured substantially in an oval shape, and in this member, the top edge portion is configured larger than the root portion thereof. The main function of this assembly guide member 25 shown in fig. 12(B) is identical to that of the assembly guide member 25 shown in fig. 12 (a).

Fig. 13 shows an example of use of the wire housing 24 with the assembly guide member 25 as described above. According to this example, the silk 24 is used as a fixing member for fixing the key to a lower case 26 constituting a part of the electronic musical instrument main body. Here, the thread bushing 24 has a hollow shape and provides a cylindrical threaded hole. A tapping screw 27 is inserted into the threaded hole of the screw boss 24 through the lower case 26 so that the key frame 8 is fixed to the lower case 26.

Fig. 14 shows another use example of the wire housing having the assembly guide member 25. In this example, a printed circuit board 28 on which an electronic circuit for controlling the electronic sound emission of the electronic musical instrument is mounted is fixed below the key frame 8, and the key frame 8 and the lower case 26 are fixed by the printed circuit board 28. The tapping screw 27 is inserted into the screw boss 24 through the printed circuit board 28, so that the lower case 26 and the key frame 8 are fixed to each other. Incidentally, this example may be modified such that the printed circuit board 28 can be attached to the boss 24 only with screws.

Fig. 15 shows the shape of the hole 30 which is formed in the key frame 8 and through which the assembly guide member 25 can be inserted. In this hole 30, a guide groove 29 is provided for sliding the wire sleeve 24 connected to the key block horizontally on the key frame 8 and guiding it to the hole 30 when assembling the key block and the key frame 8 together. The guide groove 29 may be modified to be a through hole and extend through the key frame 8 similarly to the hole 30. Or the guide groove 29 may be formed as a concave portion formed on the key frame by means of punching or the like.

The aforementioned lower edge portion 25a of the assembly guide member 25 is inserted into and fitted with the guide groove 29. According to the progress of the assembling operation, the assembling guide member 25 is guided from the guide groove 29 so that the wire housing 24 is finally guided to the hole 30. In the guide groove 29, a first rim width D₁Is set to be larger than the second edge width D₂. Due to this taper-like shape of the guide groove 29, even if the lower edge portion 25a of the assembly guide member 25 is roughly fitted into the guide groove 29 first, the passage of travel is narrowed so that the wire cover 24 can be accurately fitted into the hole 30. In short, it is possible to simplify the insertion operation of the thread bushing 24. Incidentally, the width D of the hole 30₃Matching the outer diameter of the thread sleeve 24.

Fig. 16(a) and 16(B) show a modified example of the hole 30 formed through the key frame 8. As shown in fig. 16(B), a locking hole 32 is formed by the holes 30, which cross each other at right angles. In short, the morphology of these holes resembles the letter "L". As shown in fig. 16(a), a finger 31 is formed by the black key block 21 (the black key block 21 is positioned at the highest position among the key blocks 21, 22, and 23). The finger 31 is elastically inserted into the locking hole 32 and caught in the locking hole 32, thereby firmly fixing the key block with the key frame 8.

Fig. 17(a) -17(F) show the steps of the assembly operation. With this step, the white key block 23, which provides the aforementioned assembly guide member 25, is attached to the key frame 8. When actually assembling the keyboard apparatus, the aforementioned key apparatus including three key blocks is simultaneously attached to the key frame. However, since the assembly operation related to the key device is the same as the assembly operation related to the white key block 23, only the assembly operation related to the white key block 23 will be described in detail for convenience. In these figures, the dotted lines indicate the edge portions of the hole 30 of the key frame 8 through which the silk braid 24 can be inserted. First, as shown in fig. 17(a), the wire case 24 is mounted on the key frame 8. According to this state, the rear edge portion of the assembly guide member 25 slides along the guide groove 29 (see fig. 15), thereby sliding the wire case 24 toward the hole 30 in the right direction as shown in fig. 17 (B). Fig. 17(C) shows a state in which the rear edge portion of the assembly guide member 25 reaches the edge position of the hole 30 (defined by a dotted line). In this state, the drivers 6 connected to the key block 23 are placed just above the key switches 10. As described above, until the driver 6 reaches this position, the driver 6 is forced out of contact with the key switch 10 by the assembly guide member 12 formed continuously in the horizontal direction by the driver 6.

In the state shown in fig. 17(C), the key block 23 is turned around the rotation center which is disposed in the vicinity of the upper limit stopper 5, and the upper limit stopper 5 is disposed below the key depression guide 14 connected to the key frame 8. Due to the rotation of the key block 23, the wire case 24 with the assembly guide member 25 attached thereto is lowered into the hole 30 of the key frame 8. Fig. 17(D) shows a state in which the lower edge portion 25a of the assembly guide member 25 is slightly lowered into the hole of the key frame 8, thereby moving the driver 6 downward from directly above the key switch 10 and then bringing the driver 6 into contact with the key head portion of the key switch 10. At this time, the key depression guide 14 also slides along the edge portion of the assembly guide member 12 and then is partially embedded in the key 1. In this state, a projection 61 of the actuator 6 is engaged with the head portion of the key switch 10, thereby establishing a good fixed relationship between the actuator 6 and the key switch 10. Therefore, even if a shock or vibration inevitably occurs when the key 1 is moved down, it is impossible to change the relationship. Due to this relationship, an equilibrium state can be automatically established for the key as a whole, whereby the position of the key switch 10 is used as a center of balance. Fig. 17(E) shows a state in which the key 1 is lowered and the outer edge portion of the assembly guide member 25 slides along the edge portion of the hole. In this state, the driver 6 is roughly lowered in the vertical direction while pressing the key head portion of the key switch 10 made of an elastic material. Fig. 17(F) shows a state in which the mantle 24 is completely inserted into the hole 30. In this state, even the root of the assembly guide member 25 can be fitted into the hole of the key frame 8. In inserting the screw boss 24 into the hole, the driver 6 is always moved downward in a direction perpendicular to the key switch 10 (or a switch driving direction). Therefore, no force acts on the key switch 10 in the horizontal direction. In other words, the key switch 10 made of an elastic material is not pressed and deformed in the lateral direction.

Fig. 18(a) -18(F) show another example of the assembly operation step by which the key 23 providing the aforementioned wire sleeve 24 with the tapered assembly guide member 25 is attached to the key frame 8. Unlike the previous example shown in fig. 17(a) -17(F), the assembly guide member 12 continuously molded by the driver 6 is replaced with the assembly guide rib 18 independent of the driver 6. The function and operation of the assembly guide rib 18 has been described in connection with fig. 8-10 (B). In the first state shown in fig. 18(a), the upper edge portion of the key depression guide 14 directly contacts the lower surface of the key 1. Thus, the inclination of the key block 23 must be larger than that of the former example of fig. 17 (a). However, the assembly guide member 25 performs substantially the same function in this example as compared with the previous example shown in fig. 17(a) -17 (F). According to the state shown in fig. 18(a), the wire housing 24 slides and is guided to the hole of the key frame 8 (see fig. 18(B) and 18 (C)). When the rear edge portion of the assembly guide member 25 reaches the edge portion of the hole (see fig. 18(D)), the wire housing 24 descends while the outer edge portion of the assembly guide member 25 slides along the edge portion of the hole (see fig. 18 (E)). Finally, as shown in fig. 18(F), the embedding process of the wire housing 24 is completed. As described above, the structure of the wire housing 24 with the tapered assembly guide member 25 attached thereto can be used in combination with the assembly guide rib 18 so as to be extended in the horizontal direction, the rib 18 being attached to the inner wall of the white key 1 and disposed apart from the driver 6.

FIG. 19 is an exploded side perspective view showing the body portion of the key device. The figure shows a bottom view relating to the two white key blocks 22 and 23. A plurality of white keys 34 are constituted by each of the white key blocks 22 and 23. Each of these white keys 34 is rotatable around the root of the key made of the elastic material. The present figure shows 3 white keys 34, wherein the key block 23 provides an E-key and the key block 22 provides an F-key and a D-key. A plurality of convex portions 33 are formed on the key block 34. The key block 22 provides a plurality of concave portions 37, each of which corresponds to each of the convex portions 33. By means of the convex portion 33 and the concave portion 37 respectively fitting each other, the key blocks 22 and 23 can be stacked together while the keys 34 are arranged side by side. Reference numeral 35 designates a positioning hole which is engaged with the positioning boss 36. A plurality of ribs 38 project from the inner side walls of the concave portion 37, respectively. These ribs 38 are formed as part of the key block 22 made of the elastic material. Since the rib 38 made of the elastic material is used, the key blocks 22 and 23 can be firmly fixed together when the key blocks 22 and 23 are assembled by the interfitting of the concave portion 37 and the convex portion 33. In fig. 19, the black key block 21 (not shown) is disposed under the white key block 22. Since the common base edge portion of this black key block 21, in which a plurality of black keys are provided, is similar to the common base edge portion of the white

key block

22 or 23, in which a plurality of white keys are provided, the description with respect to the black key block 21 is omitted. Of course, a plurality of ribs 38 are also provided in the black key block. It is possible to provide a plurality of ribs 38 on the outside of the convex portion 33 without providing the ribs 38 on the inside of the concave portion 37.

Fig. 20 is a plan view showing a key supporting member for the keyboard apparatus according to the second embodiment of the present invention. On a key frame (i.e., key support member) 112 made of a metal material, a flexible panel 113 made of a resin material such as mylar or the like is mounted, an edge portion of the flexible panel 113 is folded back toward a lower side of the key frame 112, and then the folded portion is connected to a main panel 135 by a connector 1132 disposed at an edge portion of the folded portion 1131 (see fig. 21). The resiliently deformable key depression sensors (i.e., before key opening) are connected on the flexible panel 113 by means of a rubber strip 114 in connecting relation to each of the keys. The key switch contains two movable contacts in its convex portion while two stationary contacts corresponding to the two movable contacts, respectively, are arranged in a concentrated manner on the flexible panel 113. When pressed by an actuator 132 (described later), the two switching elements of the key switch 115 are sequentially turned on for a certain time interval, thereby enabling the key switch 115 to generate a touch response message. The above-described structure of the movable contact of the key switch 115 can be used for the stroke sensor. For example, a convex portion including a movable contact is eliminated, the upper surface of the key switch is formed with a key, and then a light reflection type photosensor is fixed to the flexible panel 113 at a position facing the mirror for each of the keys. Thus, the key switch can be redesigned as a stroke sensor capable of transmitting a key depression stroke. As the key depression sensor, embodiments of the present invention may use a stroke sensor or a front/rear touch sensor instead of the key switch. In short, the key depression sensor is not limited to the key switch. However, for convenience, the present embodiment also employs the key switch as the key depression sensor.

Along with the side edge portion of the key frame 112 (i.e., the right side portion in fig. 20), a plurality of key guides 116 are also provided, each of which can prevent lateral swinging and rotation of the key when the key is pressed downward. Reference numeral 117 designates a fixing hole with which the key frame 112 can be fixed to each side portion of an upper case (not shown) constituting a part of the keyboard apparatus main body.

The rear edge portion (i.e., the left side portion of fig. 20) of the key frame 112 is bent upward to form an upright portion 118. At a predetermined position of the upright portion 118, a claw hole 119 is formed, by which claw hole 119 the key device can be firmly fixed. A predetermined number of fixing holes 120 for fixedly fixing the aforementioned lower case are formed at corresponding positions of the key frame 112. The number of the fixing holes 120 is determined such that one or two holes are provided for a plurality of keys corresponding to sound tones in an octave range. For example, a thread bushing 126 is inserted through the fixing hole 120, and a screw 1201 is screwed into the thread bushing 126 from the lower side of the thread bushing 126. Thus, the key frame 112 and the lower case are firmly screwed together.

A predetermined portion of the rear edge portion of the key frame 112 is partially cut and folded upward to form a guide portion 123. Reference numeral 122 denotes an opening which is cut open. On the key frame 112, the guide portion 123 is bent upward with being turned upside down. The upper edge portion of the guide portion 123 is further bent in the horizontal direction to form a supporting member 145 to be used for supporting the upper case. In addition, a fixing hole 124 is formed through the supporting member 145 to firmly support the upper case. Incidentally, reference numeral 125 denotes a positioning hole used when assembling the key device.

Fig. 21 shows a partial view of one such keyboard apparatus. In this keyboard apparatus, the keys are attached to the keyboard frame 112, and the key apparatus is fixed to the upper and lower cases. Under the center portion of the key frame 112, a main panel 135 is provided, and the main panel 135 is fixed to the key frame 112 by means of a bush 134. The flexible panel 113 is folded back toward the lower edge of the key frame 112, and then the folded portion of the flexible panel 113 is attached to the main panel 135. The main panel 135 is a circuit board with various electronic circuits such as a microcomputer, a memory, and a sound source circuit. These circuits are used to perform operations such as operations specified by key depression and music tone control.

Key device 129 is attached to key frame 112 and consists essentially of three

key blocks

1281, 1282, and 1271 stacked upon each other and assembled together at the common base portion. Fig. 21 shows two white keys 128, 128a and one black key 127.

Each of the white keys 128 is provided with an actuator 132 that presses the key switch 115 when the key is depressed. As a part of the key front edge portion, a slide guide member 146 is formed and arranged so that the key guides 116 are sandwiched by them. A lower edge portion of the slide guide member 146 is bent to form a stopper member 147 in contact with a lower edge surface of the key guide 116, to stop the return movement of the key returning from the key depression position from the surface. Further, a rib 133 is attached to an inner wall of the key 128. Due to the rib 133, when the key is slid in a horizontal direction in order to assemble the key and the key frame together, the upper surface of the key guide 115 slides along the rib 133, thereby preventing the driver 132 from touching the key switch 115.

In the key device 129, an elastic member 138 providing a projecting finger 139 projects from the common base edge portion of the white key 128. The raised fingers 139 resiliently engage a finger hole 119 formed through the upright portion 118 of the key frame 112 to secure the key assembly 129 and the key frame 112 to one another.

Key blocks

1281, 1282, and 1271 of key device 129 are stacked on each other and fixed by screws 137. In this way, each of the keys is supported by the key frame 112 at the common base edge portion of the key by means of the hinge portion 136. So that the key can be freely rotated in the key depression direction (i.e., the vertical direction).

At the same time, the driving positioning in the length direction and width direction of the key is executed between the key and the key pivot frame. This positioning is performed by means of the holes 125 provided between the keys and the projections (not shown) corresponding thereto. If the key and the key frame are fixed together at a certain point, the protrusion 123 and the guide hole 141 do not function well to stop a small rotation of the key unit. In order to stop such rotation of the key unit which must be firmly fixed to the key frame, the present embodiment provides a fixing mechanism constituted by the convex portion 143, the elastic member 138 and the upright portion 118, by which the key unit can be accurately fixed to the key frame. Incidentally, two of the fixing mechanisms are provided for one octave width of the keyboard.

During this time, the panel 1311 is fixed to the upper case 131 by a nipple (not shown) protruding from the upper case 131. The upper housing 131 provides a switch panel that includes a plurality of tone selection switches 1312 mounted on the panel 1311.

When the keyboard is assembled as shown in fig. 21, the upper case is placed upside down on a base plate (not shown), the key frame 112 fixed to the key unit is also turned upside down, a screw 1231 is inserted through the opening 122, the screw 1231 is also inserted through the hole 124 of the support member 145 provided in the guide portion 123, and then, the screw 1231 is inserted into the wire housing 154 attached to the upper case 131, thereby causing the key frame 112 fixed to the key unit to be firmly fastened to the upper case 131. In this state, the inverted lower case 130 is brought over the key frame 112, and the screw 1201 is inserted into the thread bushing 126, so that the lower case 130 is firmly and tightly joined to the key frame 112. Therefore, the assembly work for assembling the key unit, the key frame 112, the upper case 131, and the lower case 130 together is completely performed.

Fig. 22 is a side perspective view showing a rear portion of the keyboard apparatus not yet assembled together, wherein the key frame 112 is shown in a top view and the key apparatus 129 is shown in a bottom view. Fig. 23 is a side perspective view showing a part of the rear edge portion of the key device 129, and fig. 24 is a partial view of fig. 23. A guide hole 141 is formed through the public base edge portions of the three key blocks stacked and assembled together therein and at a predetermined position where it meets the guide portion 123 of the key frame 112. A protrusion 143 is protruded in a rear direction of the guide hole 141. A guide groove 142 is formed in a lower surface of the protrusion 143. At the trailing edge inlet portion of the guide groove 142, a taper 144 is formed. Thus, the entrance portion of the guide groove 142 is enlarged.

The rear edge portion of the convex portion 143 is bent upward to form an elastic member 138. The elastic member 138 can be elastically bent in the length direction of the key. The aforementioned convex hooks 139 are also formed at the rear surface portion of the elastic member 138. The upper edge portion of the elastic member 138 is also bent rearward to form a pressing member 140. The rear edge portion of the guide portion 123 cut and bent upward from the key frame 112 is formed in an arc shape to form a guide surface 123a having an inner portion similar to a cone shape.

Next, assembling steps for assembling the key device 129 and the key frame 112 together will be described with reference to fig. 25(a) -25 (C). For convenience, the representation of the black keys is omitted in these drawings. First, the key device 129 is moved in the horizontal direction by sliding the guide rib 133 along the uppermost portion of the key guide 116 of the key frame 112. As shown in fig. 25(a), the highest portion of the guide portion 123 protruding from the key frame 112 is fitted with the guide groove 142 formed at the rear edge portion of the key device 129.

Then, as shown in fig. 25(B), the key device 129 is slid in the rear direction (i.e., the left direction in the drawing), so that the rear-edge inner edge portion of the guide hole 141 reaches the rear edge portion of the guide surface 123a of the guide portion 123. At this time, the driver 132 of the key device 129 is separated from and positioned above the key switch 115 attached to the key frame 112.

According to the state shown in fig. 25(B), the key device 129 descends to slide the inner edge portion of the guide hole 141 along the guide surface 123a of the guide portion 123 as shown in fig. 25 (C). In this case, the rear edge portion of the key device 129 is lowered in a natural falling manner, and the resistance in the horizontal direction that affects the lowering movement of the key device 129 is maintained at substantially zero level. Thus, the driver 132 of the key device 129 is lowered from the upper position of the key switch 115, so that the driver 132 is elastically brought into contact with the switch 115. Therefore, no force is applied to the key switch 115 in the horizontal direction.

Thereafter, the detent elements 147 (which function as an upper limit detent) of the key device 129 are placed under the lower surface of the key guide 116, and the upper surface 1271 of the common base edge portion provided for the black keys is pressed, so that the projecting claws 139 are elastically caught on the holes 119 formed in the upright portions 118 of the key frame 112. In this state, the bottom surface of the public base edge portion is in full contact with the upper surface of the rear edge portion of the key frame 112. Thereby, as shown in fig. 21, a fixed relationship in the horizontal direction is established between the key device 129 and the key frame 112. In short, the keyboard apparatus according to the present embodiment is designed such that, at a contact portion to be formed between the key device 129 and the key frame 112, the sum of the thickness of the rear edge portion of the guide hole 141 and the protruding length of the protruding portion 143 is equal to the distance between the upright portion 118 and the guide surface 123a of the guide portion 123 protruding from the key frame 112. Therefore, in the case where the bottom surface of the key device 129 is in contact with the upper surface of the key frame 112, the key device 129 cannot move in the horizontal direction of the key, so that the horizontal position of the key device 129 is firmly fixed with respect to the key frame 112. Since the projecting fingers 139 of the elastic member 138 are caught to the finger holes 119 formed through the key frame 112, the vertical movement of the key device 129 is adjustable, in other words, the falling-off event of the key device 129 can be prevented during the assembly operation. Incidentally, when the key device 129 is moved again from the key frame 112, the pressing member 140 of the elastic member 138 is pressed backward against the elastic resistance of the elastic member 138, so that the projecting fingers 139 are released from the finger holes 119.

As described above, the protrusion 143 and the elastic member 138 are interposed between the upright portion 118 and the guide surface 123a of the guide portion 123, and then the guide hole 141 descends along with the guide surface 123a, so that the key assembly 129 is automatically guided to the key frame 112 in a predetermined direction.

Fig. 26(a) -26(D) show another example of an assembling process by which the key device 129 is assembled with the key frame 112. The assembly process shown in fig. 26(a) and 26(D) is similar to the assembly process shown in fig. 25(a) and 25 (B). Therefore, detailed descriptions thereof are omitted herein. After the assembly step shown in fig. 26(B) is carried out, the descending speed of the key device 129 at its front edge portion is different from that of the key device 129 at its rear edge portion due to the frictional force existing in some portions or the difference between the grease sprayed states of the key guide 116 and the stopper member 147. In some cases, the sliding guide 146 provided at the leading edge portion of the key device 129 descends faster than the trailing edge portion of the key device 129. As described above, if the front edge portion of the key device 129 descends at a higher speed than the rear edge portion of the key device 129, the assembled state thereof is as shown in fig. 26 (C). Fig. 26(C) shows the worst state of the key-down badly. In general, however, the mirror-angled portions 1331 of the ribs 133 may slightly transmit a horizontal component of force to the key arrangement 129 during key depression, thereby causing the trailing and leading edge portions of the key to descend simultaneously. In short, in a general case, the worst state as shown in fig. 26(C) can be avoided. However, if the state shown in fig. 23(C) occurs, the driver 132 of the key device 129 descends in a nearly natural falling manner, so that the driver 132 can be made to be displayed above the key switch 115. In this case, the driver 132 is placed slightly away from the key switch 115. In other words, even if such a transitional state is generated, it is ensured that no force is applied to the key switch 115 in the horizontal direction. In the key-down state, a small horizontal component of force is transmitted to the key, causing the trailing edge portion of the key device 129 to continue to descend. Thereafter, the trailing edge portion of the key device 129 is lowered in a manner similar to that shown in fig. 25 (C). In other words, the key device 129 moves down in a nearly natural falling manner while the inner edge portion of the guide hole 141 slides along the guide surface 123a of the guide portion 123. As a result, the state shown in FIG. 26(D) can be obtained. As described above, after moving down from the position above the key switch 115 attached to the key frame 112 from the driver 132 of the key device 129, the rear edge portion of the key device 129 further falls. Therefore, no force is applied to the key switch 115 in the horizontal direction.

FIG. 27 is a side perspective view showing another example of a trailing edge portion of the key structure. In this example, no guide groove is provided in the protrusion 143 protruding rearward from the guide hole 141. When the key device is assembled to the key frame, the key is brought to the position shown in fig. 25(B) or 26(B) without sliding on the key frame in advance. According to this state, the rear edge portion of the key device is lowered while the inner edge portion of the guide hole 141 slides along the guide portion 123 attached to the key frame 112. Thus, as described with reference to fig. 25(a) -25(C) or 26(a) -26(D), the key device is lowered in a nearly natural falling manner, so that the actuators of the keys are brought into contact with the upper surface of the key switch 115. For this reason, an arcuate portion or taper 148, which may correspond to the aforementioned arcuate taper 144 (see fig. 23) formed in the guide slot 142, is formed in the guide bore 141 to enlarge the opening of the guide bore 141. In this example, the portions other than the above-described portions are similar to those of the foregoing example, so that the same operation and effect can be achieved.

FIG. 28 is a side perspective view showing yet another example of a trailing edge portion of the key device. Fig. 29 is a side perspective view showing a detailed structure of the guide portion 123 provided on the key frame 112 and corresponding to the key device shown in fig. 28. In these examples, the guide portion is made of a resin material and is molded independently of the key frame, or the guide portion 123 is formed as a part of the key frame 112. In the key device 129, a projection 151 projects downward from a rear projection portion 143 of the guide hole 141. A guide groove 149 is formed on the upper surface of the guide portion 123 in order to match the protrusion 151. At the entrance portion of the guide slot 149, an arcuate portion or taper 150 is formed. Holes 124 are provided for securing the upper housing and the key frame 112 to each other. Below the hole 124, a larger through hole (not shown) is provided to match the nut, and a smaller hole (not shown) is provided to guide the large hole, so that the nut is prevented from passing through the hole. A positioning hole 152 is formed through the key frame 112 at a position apart from the rear side surface of the guide portion 123. This positioning hole 152 may correspond to the front hole 125 shown in fig. 20. In the present embodiment, a positioning structure for the key unit is provided between the D key and the D # key.

The above-described projection 151 and the hole 152 need not be formed in the vicinity of the guide structure (see fig. 28 and 29) provided between the G # key and the a-key. Initially, the protrusion 151 shown in fig. 28 or a protrusion corresponding to the hole 125 (see fig. 20) is provided to overcome the accuracy error of the contraction of the head of the key unit made of the resin material and the through hole molded in the key frame, thereby enabling the key depression movement to be smoothly performed. In short, these projections are provided as positioning structures, so that the positioning need can be satisfied by using only one positioning point.

When the key device and the key frame are assembled together, the key device 129 is moved toward the key frame 112, and then the protrusion 151 attached to the key structure 129 is fitted into the opening of the guide groove 149, where an arc portion 150 is formed. Then, the key device 129 is slid in the horizontal direction so that the guide hole 141 and the guide portion 123 are engaged with each other. Similar to the previous example, the trailing edge portion of the key device 129 descends in a manner similar to a natural fall. In the case where the key device 129 is completely lowered, the protrusion 151 of the key device 129 is inserted into the positioning hole 152 of the key frame 112, and at the same time, the protrusion claw 139 of the elastic member 138 bites into the claw hole 119 of the key frame 112. In this way, the positioning of the key device 129 relative to the key frame 112 in both the length and transverse directions can be achieved. In addition, the key device 129 is electrically fixed to the key frame 112 in a vertical direction.

In this case, both the guiding structure and the positioning structure are provided at almost the same location. In this way, it is possible to simultaneously perform the assembling operation and the positioning operation accurately between the key device 129 and the key frame 112. As a result, the assembling work can be performed accurately at high speed. This is a great advantage of this example.

Fig. 30 is a side perspective view showing still another example of the rear edge portion of the keyboard apparatus. According to this example, each of the keys is individually attached to the key frame 112. At the common base edge portion 1531 of the key 153, the guide hole 141 having the convex portion 143 at the rear edge portion thereof, the elastic member 138, the pressing member 140, and the like are provided, similarly to the previous example. Near the rear edge portion of the key frame 112, a guide portion 123 corresponding to a key is provided. The guide portion 123 may be formed of the resin material separately from the key frame 112, or the guide portion 123 may be molded as a part of the key frame. In fig. 30, the guide rib 133 by which the key can be slid in the horizontal direction is omitted from the illustration relating to the key 153.

In addition, the hole 124 for fixing the upper case and the key frame is formed at a proper position on the upper surface of the guide portion 123. For one octave, for example, two fixing holes 124 are provided, and they are arranged at positions corresponding to the D key and the a key in one octave key group, respectively. In fig. 30, the rear side surface of the guide portion 123 is vertically erected on the key frame 112. However, the guide portion 123 may be modified to be at an oblique angle with respect to the key frame 112 or to be formed in a circular arc shape.

Fig. 31(a) -31(C) will describe the assembly procedure according to which the keys 153 are assembled with the key frame 112 according to the present example. For the present example, a number of assembly procedures are provided, and therefore a detailed description will be made with respect to each of them. (1) First assembling procedure

First, the key 153 is continued to a certain position when supported by one finger, and thus the projection 143 of the key 153 contacts the upper surface of the guide 123 fitted on the key frame 112. With the support of the finger, the guide groove 142 of the key 153 moves to a dropping point (dropping point) as shown in fig. 31 (a). At this drop point, the actuator 132 is positioned just above the key switch 115. At the same time or later when the guide portion 123 is inserted into the guide hole 141, the finger is separated from the key 153. Thereafter, the rear edge portion of the key 153 drops almost in a natural dropping manner, bringing the key 153 into contact with the key frame 112. Thereafter, the common base edge portion 153 of the key 153 is pressed down, so that the projecting hook 139 is caught in the hook hole 119. Thus, the key 153 is completely mounted with the key frame 112.

The above-described fitting operation is repeatedly performed for each key. After all the keys are completely assembled with the key frame, a common fixing plate (see fig. 34), the length of which matches the entire length of the keyboard, is pressed and fixed to the rear edge portions of the keys. When fixed with the upper housing, the key frame to which the key is fixed is changed in direction and fixed to the upper housing. In this case, a screw is inserted through the four-legged boss 154, and the screw is also inserted into the hole 124 of the guide mechanism 123 provided on the key frame 112, so that the upper housing is screwed with the key frame 112. The fixing plate 155 is provided with a plurality of through holes 169 and screw holes 168. The number of through holes 169 is equal to the number of guide portions 123, and the number of screw holes 168 can be adjusted such that one screw hole 168 can be used for one, two or three keys. The fixing plate 155 is placed on the common base edge portion 1531, and thus the common base edge portion 1531 is sandwiched between the fixing plate 155 and the key frame 112. Thereafter, a screw 1532 is inserted into the screw hole 168, and thus, the fixing plate 155 is firmly fixed with the key frame 112 by means of the common base edge portion 1531. (2) Second Assembly procedure

First, the key 153 is held by a human hand or a manipulator, and thereafter, the key 153 is mounted on the key frame 112 such that the common base edge 1531 is fixed to the upper surface of the guide portion 123 and the slide guide 146 is fixed in the vicinity of the key guide 116. In this case, the guide groove is fixed to the head of the guide portion 123. The angle θ is formed between the horizontal portion of the key frame 112 and the surface of the key 153. As described above, the angle θ is defined as "θ 1". According to this case, when a free edge portion of the key 153 is reversely changed in position by a human hand or a robot arm, the angle θ is gradually increased. Meanwhile, when the trailing edge portion of each guide hole 141 contacts the trailing edge portion of the guide portion 123, the angle θ may be defined as follows: θ 0 > θ 1. Fig. 31(B) shows a case where the trailing edge portion of the key 153 is fixed just before the drop point. For this case, the height of the guide portion 123 or the height of the actuator 132 is determined such that the actuator 132 is not in contact with the key switch 115, and the actuator 122 is disposed slightly away from the key switch 115. Thereafter, the key 153 is further lightly pressed in the reverse direction, so that the rear edge portion of the key 153 falls into contact with the key frame 112. The following steps of the apparatus assembling procedure are similar to the above assembling procedure, and therefore, a description thereof will be omitted.

Next, the advantages of the present embodiment will be described in detail. In general, when considering the number of parts, the precision of driving the switches, and the total thickness of the keyboard apparatus, it is necessary to design the keyboard apparatus in which the keys are fixed regardless of the key frame and the height of the four-leg bosses is low.

In this prior embodiment, the angle θ is equal to θ 1, and this angle 9 is 90, 90 > θ 1, before the key is slid in the reverse direction.

It is expected that the actuator 132 will be slightly away from the key switch 115 just before the key is dropped. Even when the key device structure is actually designed, the distance between the actuator and the key switch is set to 1mm, which should be increased to 2mm in order to cope with manufacturing errors of the key device. In this case, the distance between the actuator and the key switch is increased by 1mm, however, the height of the guide portion 123 should be increased by 5-6mm since the height of the guide portion 123 is changed in proportion to the increase of the interval between the actuator and the key switch. In the conventional example, the vertical positional relationship is strongly maintained between the actuator 132 and the key switch 115, and this is just before the fitting operation is performed, in other words, just before the key is dropped. Therefore, the allowable distance range between them can be reduced, so that the distance between them can be set to 1 mm. Even when the keyboard is actually constructed such a small distance of 1mm is roughly cleared to zero, there is a small gap between the guide portion 123 and the guide hole 141, so that even if the actuator 132 lightly presses the key switch 115 in its lateral direction until it starts the falling movement, such a pressing force can be completely cleared just before the key falling movement. Therefore, it is possible to improve the relationship between the keys and the key frame. It is furthermore possible to manufacture smaller thicknesses of the key device.

Fig. 32 is a side view illustrating still another keyboard apparatus. According to the first feature of this example, the fitting operation and the positioning operation for the key unit and the key frame can be performed simultaneously or immediately. According to a second feature, a guide portion is attached to the key. The temporary stopper can help this fitting operation to be performed more quickly when the key and the key frame are fitted together. Accordingly, the present example provides the projecting portion 1235 which functionally performs both the guiding portion operation and the temporary braking operation, wherein the lower edge portion constituting the projecting portion 1235 is circular. The projecting portion 1235 is designed to be under the lower surface of the common base edge of the key unit. More specifically, one projecting portion is provided between the D key and the D # key, and the other projecting portion is provided between the G # key and the a key. A recess (or a through hole) 1125 is formed in the key frame, wherein the shape of the recess 1125 is designed to match the circular shape of the projecting portion 1235. The other parts of this example are similar to the previous examples (refer to fig. 20, 21, 22, 25(a) -25(C) and 26(a) -26(D)), and therefore, the description will be omitted.

The projecting portion 1235 is guided by the recess 1125, and thereafter, temporarily stopped by the key frame 112. When the projecting portion 1235 is fixed in a certain position on the key frame 112, the hook 139 is caught in the hook hole 119 formed through the upright portion 118. The projecting portion 1235 is fixed at a point of contact where its front face is in contact with the front face of the recess 1125, and the rear face of the elastic member 138 is fixed with the upright portion 118, so that they are pressed against each other. By improving the accuracy of fitting between the hook hole 119 and the hook 139, it is possible to fully realize the positioning operation between the key unit and the key frame. In this case, the key unit and the key frame are fixed together in all directions, for example, in the width direction, the longitudinal direction and the vertical direction of the key. Incidentally, such positioning can also be achieved well by improving the fitting accuracy with respect to the two pairs of hook holes 119 and hooks 139, so that the hook holes can be slightly enlarged in the width direction of the keys for the other pair of hook holes and hooks. The present example provides two pairs of convex-concave portions with respect to a key unit providing an eight (tone) degree keyboard. In order to adjust the movement of the key unit in the width direction of the key, a pair of convex-concave portions in which the width of the convex portion matches the width of the concave portion is provided as a first engagement mechanism, and a certain clearance is provided for the other pair of convex-concave portions. Adjacent to the first engagement mechanism, a pair of hooks 139 and hook holes 119 are provided as the second engagement mechanism, and since the first and second engagement mechanisms are provided, it is possible to completely determine the positional relationship between the key unit and the key frame.

Fig. 33 is a perspective view illustrating a rear edge portion of a key assembly of the keyboard apparatus. Here, it is explained that the two key units 157 and 158 are assembled together, wherein the key unit 157 provides a C key, an E key 163, a G key and a B key (wherein the C, G and B keys are not shown), and the other key unit 158 provides a D key 164, an F key 165 and an a key (not shown). The black key unit description is omitted, but it may be disposed below the key unit 158. In the perspective view, the rear key unit is at the lowermost position as compared with the white key portion, but in the assembly views shown in fig. 21 and 22, the black key unit is at the uppermost position. A number of projections are formed on the key unit 157 providing the E key 163. A plurality of recesses 160 corresponding to each of the projections 159 are formed on the key unit 158, and the key 158 is to be fitted with the key unit 157. In each recess 160, there is a stiffener structure 166. When the convex portion 159 engages the concave portion 160, the reinforcing ribs 166 deform, slightly damaging the outer wall of the convex portion 159. Thus, both of them are securely fixed together by the rib 166 and are pressed against each other. Numeral 161 denotes a projection which is used to determine the positional relationship between the key units 157 and 158. The projection provided in the recess 160 of the key unit 158 is inserted into the positioning hole 162 formed in the upper wall of the projection 159 of the key unit 157. In each of the key units 157 and 158, a number of through holes 167 are formed. The through-hole 167 of each key unit 157 and the through-hole 167 of each key unit 158 are matched. These through holes 167 serve as screw holes. By inserting the screw 137 (see fig. 21) into the screw hole, the key assembly including the key unit is securely fixed with the key frame.

A guide groove and a guide hole 141 are formed in the key unit 157 fixed at the lowermost position when all the key units are fitted together. In the other key unit 158, another guide hole 141 is formed to match the guide hole 141 of the key unit 157. Similar to the key assembly described above, the key assembly shown in fig. 33 can be assembled by dropping the guide hole 141 along the guide portion of the key frame without damaging the key switch. [C] Third embodiment

The previous perspective view of fig. 19 shows a key assembly according to a third embodiment. Here, a via 208 is reused. When the key device is fixed to the main body of the musical instrument, a screw is inserted through the through hole 208.

The cross-sectional shape of the reinforcing rib 38 is mainly triangular, and the reinforcing rib 38 extends along the inner wall of the concave portion 37 in the vertical direction. In order to exert an appropriate pressure between the outer wall of the convex portion 33 and the inner wall of the concave portion 37 when the two key units (i.e., key blocks) 22 and 23 are assembled together, the vertical angle of the triangular reinforcing rib 38 is equal to 90 °, and the height thereof is 0.1mm to 0.2mm as an example. In order to smoothly complete the insertion operation between the convex portion 33 and the concave portion 37, it is desirable to form a circular portion having a radius R of 0.3mm at the entrance edge portion of the concave portion 37.

Fig. 35 is a perspective view illustrating a modification of the third embodiment. In this example, the reinforcing ribs 38 are formed on the outer surface of the convex portion 33. Here, three key units, i.e., one black key unit 222 and two white

key units

224 and 226, are provided. The three

key units

222, 224 and 226 are assembled together to form an eight degree portion of the keyboard. In the black key unit 222, a plurality of black keys 221 are supported by a common base edge portion 227, which can freely swing. An inner (not shown in fig. 35) portion of the common base edge portion 227 is formed to serve as the above-described concave portion, and into which is entered the convex portion 33 of the white key unit 224. In fig. 35, only two black keys 221 are illustrated, but, in practice, 5 black keys should be provided, which correspond to symbols G #, D #, F #, G # and a #, respectively. A plurality of white keys 223 are provided to the common base edge portion 228 of the white key unit 224, which can freely swing. In fig. 35, only two white keys 223 are illustrated, but actually 3 white keys should be provided, which correspond to the symbols D, F and a, respectively. Similarly, a plurality of white keys 225 are provided to the common base edge portion 229 of the white key unit 226, which can freely swing. In fig. 35, only two white keys 225 are illustrated, and actually 4 white keys should be provided, which correspond to symbols C, E, G, and B, respectively.

In the third embodiment as shown in fig. 19 or 35, two reinforcing ribs 38 are formed on both side walls of the concave portion 37 or the convex portion 33, respectively. It is possible to provide only one reinforcing rib 38 for one recess 37 or one projection 33. Of course, the location, size or attachment spacing of the ribs 38 can be varied as desired. The shape of the reinforcing rib 38 is not limited to the above-described triangular shape. The shape of the reinforcing rib may be changed to be semi-cylindrical, semi-spherical, etc. [D] Fourth embodiment

Next, referring to FIGS. 36-38, a fourth embodiment of the present invention will be described in detail. This embodiment is provided to avoid conduction errors in circuit components mounted on a circuit board. More specifically, when the keys are depressed to be guided by the key guide, a predetermined type of lubricant, such as grease, is applied to the sliding contact portions of the key guide to prevent the generation of undesired sound. However, in the same case, the lubricant may overflow to the circuit board, thereby leading to conduction errors of the switching elements provided on the circuit board. To overcome this drawback, the fourth embodiment features a special mechanism (e.g. a stiffening rib) for avoiding lubricant flow to the circuit elements.

Fig. 36 is a sectional view showing a main part of a keyboard apparatus provided to an electronic musical instrument according to embodiment 4 of the present invention.

The keypad provides a key 301 and a key frame 303. The key frame 303 supports and fixes a rear edge portion of the key 301. The key frame 303 is made of a metal plate having elastic stability, and supports the key 301 by which the key 301 can be swung up and down in the key depression/release direction (see arrow a).

The key 301 includes a white key 304 and a black key 305 each made of a resin material and formed in a block shape. A predetermined number of white keys and black keys corresponding to one eight (tone) degree or half eight (tone) degree keyboard are arranged in parallel in one key unit.

Similar to the embodiments described above, this fourth embodiment provides three common base edge portions that are gathered together at the trailing edge portion of the key 301. Here, each two common

base edge portions

304a and 304b correspond to white keys, and one common base edge portion 305a corresponds to a black key.

A through hole is formed through the three common

base edge portions

304a, 304b and 305. A quadrangular boss 308 should be attached to and partially inserted into a lower surface of the key frame 303 along with a supporting point 302 of the key 301. Thereafter, the screw 307 is inserted through the through hole and screwed into the tetragonal boss 308. Thus, the tetragonal boss 308 is firmly fixed to the lower surface of the key frame 303, and the three common

base edge portions

304a, 304b and 305 are also firmly fixed to an upper surface of the key frame 303.

Both side walls (see right-side portion) of the front portion of the white key 304 partially protrude downward to form stopper elements 304C each having the pictogram "L". A key guide 309 is provided corresponding to the pair of braking members 304 c. In the present example, some portions of the front edge portion of the key frame 303 are formed to have a width slightly smaller than that of the keys 304; and this part is floating and curved, with the top edge extending up to the underside of the key; accordingly, the outer side portion of the suspended portion of the keyframe 303 is covered with a guide mechanism made of a resin material (e.g., a sound absorbing material such as a plastoelastic substance or a foamed medium) to form a key guide 309. A lubricant is applied to both side surfaces of the key guide 309 that slides with the white key 304. The inner wall of the stopper member 304c is slid along both side surfaces of the key guide 309. Such a sliding operation will prevent the key from being swung when the key is moved up and down in the key depression/release direction.

Like the white key 304, the black key would provide a braking element similar to the braking element 304c described above. In response to these stopper elements of the black keys 305, additional key guides 309 are formed at the front edge portion of the keyframe 303.

A circuit board 311 is attached to one surface of the key frame 303 facing the lower surface of the white keys 304. Perhaps, the circuit board 311 may be positioned adjacent to the key frame 303, switch contacts and the like may be mounted on the circuit board 311. The two-key switches 310 correspond to the white keys 304, respectively, and the black keys 305 are mounted on the circuit board 311.

Similar to the key switches described above, the key switch 310 includes a fixed contact point and a movable contact point. Fixed contacts are formed on the circuit board 311, and movable contacts are included in an inner portion of the resilient projection mechanism 312. For example, the fixed contact points are constituted by a pair of non-conductive elements each having a comb-like shape or a letter "E" like shape, wherein these elements are arranged in parallel on the wiring board 311. The exterior of these elements is closed with a circular carbon printing paper.

In this elastic projection mechanism 312, a cylindrical projection is formed to be downwardly projected. On the lower edge face of the stud projection, a movable contact is formed so that the movable contact faces the fixed contact in parallel. The circular movable contact is made of a conductive elastic material such as conductive rubber.

The resilient projection means 312 is substantially made of a moldable resilient material such as rubber. An annular ring 313 is formed on the upper portion of the elastic projection mechanism 312, and an actuator 314 is projected downward from the lower surface of the white key 304 (or from the lower surface of the black key 305). When the key is depressed, the actuator 314 depresses the annular ring portion 313, whereby the elastic projection portion 312 is elastically deformed to raise the movable contact downward into contact with the fixed contact formed on the circuit board 311, thus turning on the key switch 310. After which the tone is emitted.

Meanwhile, a stepped portion 315 is formed at a certain portion of the key frame 303 between the key guide 309 and a free edge portion 311a of the circuit board 311. The stepped portion 315 extends continuously in the key arrangement direction. The level difference portion 315 is lower in the vertical plane than the circuit board 311.

The circuit board 311 is fixed to the key frame 303 such that its free edge portion slightly protrudes from a wall portion 315a of the stepped portion 315 toward the key guide 309.

A screw base 303a is formed under the stepped portion of the key frame 303. A screw base 303a formed in a downward direction of the screw hole is fixed to one edge portion of the main frame 316 by a screw 317. The tetragonal screw boss 308 is fixed to the other edge portion of the main frame 316 by a screw 318. In this manner, the keyboard apparatus is entirely and securely fixed to the main frame 316.

A key stopper portion 304d protrudes downward from the white key 304 near the stopper member 304c, and a lower limit stopper 309a for adjusting the swing of the white key 304 in the key depression direction is formed as a part of the upper surface of the key guide 309, and when the key stopper portion 304d is brought into contact with the lower limit stopper 309a and the white key 304 is depressed, the position of the lower side of the white key 304 is restricted. On the other hand, an upper limit stopper 309b is formed as a part of the lower surface of the key guide 309. When the stopper member 304c comes into contact with the upper limit stopper 309b, the white key 304 is returned from the key-pressed position, and the upper side position of the white key 304 is restricted.

Similarly, the upper and lower side positions of the black key 305 are restricted by upper and lower limit stoppers, respectively.

On the lower surface of the key frame 303, an auxiliary circuit board 319 is fixed with screws inserted into two boss bosses 322, respectively.

As described above, since the circuit board 311 is located close to the key guide 309, there is a possibility that a small amount of lubricant 320 applied to both side walls of the key guide 309 may slowly overflow the circuit board 311. For some cases, the spilled lubricant 320 creates conduction errors at the contacts of the key switch 310.

In order to avoid the lateral swinging movement of the keys, the gap formed between the both side walls of the key guide 309 and the inner wall of the white key 304 (or black key 305) must be minimized. When the white keys 304 are assembled with the key frame 303, the stopper members 304c of the white keys 304 are fixed such that they are partially overlapped with the key guide 309 at first; then, the white key 304 is pressed in the left direction of fig. 36. At the same time, the stopper member 304c can partially wipe off the lubricant applied to both sidewalls of the key guide 309 so that the frictional lubricant can easily move toward the circuit board 311.

However, according to the present example, even if the lubricant 320 overflows from the key guide 309 to the circuit board 311, the stepped portion 315 between the key guide 309 and the free edge portion 311a of the circuit board 311 will prevent the lubricant 320 from rolling so that the flowing lubricant does not reach the upper surface of the circuit board 311.

The circuit board 311 of the present embodiment is fixed such that the free edge portion 311a thereof slightly protrudes from the wall portion 315a of the stepped portion 315 toward the key guide 309. This position of the circuit board 311 will in turn avoid the flow of lubricant 320 to the circuit board 311.

Therefore, the lubricant 320 does not flow to the contact of the key switch 310 mounted on the circuit board 311. Thus, the conduction error of the key switch 310 is not generated.

Incidentally, the position of the circuit board 311 can be improved such that the free edge portion 311a thereof does not protrude from the wall portion 315a of the level difference portion 315. Even with such a modified position of the circuit board 311, the stepped portion 315 can satisfy the requirement of preventing the flowing lubricant 320 from flowing to the circuit board 311.

Fig. 37 is a side view illustrating a main part of another example of the key frame 303, in which the same parts as those shown in fig. 36 will be denoted by the same numerals.

If compared with the 4 th embodiment shown in FIG. 36, this example is characterized in that the stepped portion 315 is replaced with a reinforcing rib 321. The reinforcing rib 321 is provided between the free edge portion 311a of the circuit board 311 and the key guide 391 to prevent the lubricant oil 320 from overflowing toward the key switch 310.

Even if the lubricant 320 applied to the key guide 391 overflows toward the circuit board 311, the reinforcing ribs 321 prevent the flow of the lubricant 320, whereby the lubricant 320 no longer overflows to the circuit board 311. Similar to the above-described embodiment in which the stepped portion 315 is provided, the reinforcing rib 321 provided in this example can prevent the lubricant 320 from flowing to the contact of the key switch 310, in other words, it is possible to avoid conduction errors of the key switch 310.

Incidentally, the reinforcing ribs 321 can be made of a resin material regardless of the key frame 303, so that the reinforcing ribs 321 are strongly attached to the key frame 303. Perhaps the stiffener 321 may be part of the keyframe 303. In that case, portions of the key frame 303 made of a metal plate are bent upward by a drawing process or other methods to form the reinforcing ribs 321.

It is possible to further improve the present example by providing both the stepped portion 315 and the reinforcing ribs 321. In this case, the stepped portion shown in fig. 36 is formed on the key 303 at a position between the circuit board 311 and the key guide 391, and the reinforcing rib 321 is designed on the bottom surface of the stepped portion 315 so as to prevent the lubricant 320 from overflowing to the circuit board 311.

According to the above-described modification, even if the lubricant 320 applied to the key guide 391 overflows toward the circuit board 311, and thereafter, the flowing lubricant exceeds the reinforcing ribs 321, the flowing lubricant must be given resistance by the wall portion 315a of the stepped portion 315. In short, the rolling lubricant can be prevented from reaching the upper surface of the circuit board 311, and therefore, it is of course possible to avoid causing conduction errors on the contacts formed on the circuit board 311.

Fig. 38 is a side view illustrating main parts of another example of the keyframe 303 and the key 301, wherein the same parts as those shown in fig. 36 will be denoted by the same reference numerals.

Unlike the above-described embodiment shown in fig. 36, the reinforcing rib 321a for preventing the flow of the lubricating oil 320 protrudes from the upper edge of the key guide 309 facing the circuit board 311, in the key guide 309, the lower limit stopper 399 is formed as a part of the key guide 309.

Similar to the above-described embodiment and modified examples, the reinforcing ribs 321a of this example can prevent the lubricant from the key guide 309 from spilling toward the circuit board 311. Since the reinforcing rib 321a and the lower limit stopper 399 are formed as part of the key guide mechanism 309, it is possible to reduce the manufacturing cost of the key device as compared with the case where the reinforcing rib is independently constructed as in the above example.

As shown in fig. 38, when a key 301 (corresponding to each of the white key 304 and the black key 305) comes into contact with the lower stopper 399, a gap S is present between the key stopper portion 304d and the reinforcing rib. Therefore, even if the key 301 is depressed to the lower limit position as shown in fig. 38, in the case where the lubricant 320 overflows to the upper surface of the lower limit stopper 399, there is hardly such a possibility that the lubricant 320 exceeds the reinforcing ribs 321a and overflows to the circuit board 311.

Further, the present example designs the key stopper portion 304d such that the different reinforcing ribs 321a are in contact. Therefore, the reinforcing rib 321a will not affect the key-down stroke of the key 301 at all (i.e., the rotational stroke of the key 301, which is limited by the lower limit stopper 399). [E] Example 5

Then, a detailed description will be given of the embodiment 5 of the present invention. This embodiment is characterized by a specially designed key switch structure added to a keyboard apparatus according to the present invention.

It is generally difficult to securely attach the key switch to the circuit board. In some cases, the claws around the outer portions of the key switches are inserted into and caught in holes of the circuit board, so that the key switches are firmly fixed to the circuit board. Such a key switch structure is effective for attaching the key switch to a circuit board if the circuit board has a certain rigidity. But in the case of flexible printed circuit boards, this structure does not work well. On the other hand, the key switch can be directly attached to the circuit board with an adhesive medium. In this case, however, in order to obtain sufficient bonding strength, it is necessary to obtain a certain size for the bonding area on the circuit board. This is a disadvantage because such an adhesion area limits the shape and structure of the key switch, while also reducing the degree of freedom in the operation of the key switch.

To overcome the above-described circumstances, the present embodiment provides 3 key switches of a new structure which can be easily attached to a keyboard apparatus according to the present invention.

Fig. 39 is a sectional view illustrating a mechanism structure of a keyboard apparatus applied in the embodiment 5 according to the present invention, and fig. 40 is a perspective side view illustrating a key switch in which a pair of elastic projections are formed. In brief, the cross-sectional view of FIG. 39 is taken along the line X-X through the key switch of FIG. 40.

As shown in fig. 39, the key switch 410 is mainly constituted by a substrate 412 which functions as a base structure for the key switch, and the expanded portion 414 has a dome shape and an elastic expanded portion 411. Fixed contact 415 is attached to substrate 412; the movable contact 413 is attached to the inner wall of the bulging portion 414 with respect to the fixed contact; the pressing portion 416 is formed outside the surrounding elastic bulging portion 44; the opening 418 is formed by the sheet-like pressing mechanism so that the bulging portion 414 of the elastic bulging portion 44 is inserted into the opening 418 and engaged with the opening 418 of the pressing portion 417.

As shown in fig. 40, a plurality of elastically-bulging portions 411 equal in number to 6 (corresponding to half an octave of the keyboard) or 12 (corresponding to one octave) are arranged at equal intervals in a line shape, and the lower edge portions thereof are connected together with a pressing portion 416. These elastically bulging portion 411 and pressing portion 416 are formed as one unit.

The elastic bulging portion 411 is formed of a plastic and elastic material such as rubber. The elastic bulging portion 411 provides the above-mentioned dome-shaped bulging portion 414, a cylindrical portion 419, an annular ring 421 and a movable contact 413, the cylindrical portion 419 projecting downward from the center of the inner wall of the bulging portion 414; the annular ring portion 421 is on the opposite side of the cylindrical portion 419; the movable contact 413 is partially melted and attached to the lower edge surface of the cylindrical portion 419. The movable contact 413 in the form of a disk is made of a conductive elastic material such as conductive rubber. When the annular ring portion 421 is pressed down in the AA direction by an external force, the bulging portion 414 is partially deformed, so that the movable contact 413 is moved down to be in contact with the fixed contact 415 attached to the substrate 412.

The base plate 412 is made of a bakelite printing plate or a thin-thickness plastic printing plate. A pair of non-conductive elements, each having a comb or letter "E" shape and externally surrounded by approximately circular elements. Thus forming fixed contact 415. Fixed contact 415 is formed at a fixed position on substrate 412 by printing with toner or the like, and is opposed to movable contact 413 of elastically bulging portion 411.

As shown in fig. 40, positioning projections 422 are formed downward below the pressing portion 416 between the elastic swelling portions 411 arranged linearly at equal intervals. The number of the positioning projections 422 is determined such that a set of the elastic swelling portions 411 continuously formed by the pressing portions 416 and connected together can be simultaneously and effectively fixed to the base 412. For example, 3 or 4 positioning projections are provided for one key block. A plurality of positioning holes 423 are respectively formed through the substrate 412 as long as the protrusions 422 can be respectively matched thereto. By inserting the projection 422 into the hole 423, it is possible to accurately fix the position of the elastically bulging portion 411. Thus, each movable contact 413 can be fixed at an accurate position facing the fixed contact 415.

The sheet-like pressing portion 417 is made of, for example, a prepreg. A plurality of openings 418 are formed through the pressing mechanism 417, and thus the swelling portion 414 of each elastic swelling portion 411 can be smoothly inserted through the opening 418 of each pressing portion 417. When the elastically bulging portion 411 is inserted through the opening 418 of the pressing mechanism 417, the peripheral portion of the pressing mechanism 417 is fixed to the outside of the edge portion of the pressing portion 416.

In order to firmly fix the elastic bulged portion and the base plate 412 together, after the projections 422 are engaged with the holes 423 of the base plate 412, respectively, the following steps are performed. First, a viscous medium having a large adhesive strength is applied to a predetermined portion 412a of the substrate 412 fixed to the outside of the pressing portion 416; the pressurizing mechanism 417 covers the elastic swelling portion 411, and the swelling portions 414 are respectively inserted through the openings 418 of the pressurizing mechanism 417; thereafter, the pressing mechanism 417 is bonded to the base plate 412 in such a manner that the pressing portion 416 connected to the elastic bulging portion 411 is pressed by the pressing portion 417.

As described above, the pressing portion 416 and the elastically bulging portion 411 are firmly fixed by the pressing portion 417. Thus, it is possible to establish an accurate positioning relationship among the elastically bulging portions 411 on the base plate 412.

Therefore, when the pressing portion 416 of the elastic bulging portion 411 is press-connected, it is possible to easily attach the key switch 410 to the circuit board by simply sticking the pressing mechanism 417 to the base plate 412. For general purposes, where the elastic bulged section is directly adhered to the circuit board, the area of the lower surface of the elastic bulged section should be limited so that sufficient adhesive strength can be obtained. As compared with this case, the present embodiment is advantageous in that the shape of the elastically bulging portion of the key switch 410 is not limited to the above-described factors. It is thus possible to improve the degree of freedom thereof with respect to the design of the key switch shape.

Further, due to the structure of the above-described key switch, there is no interlayer caused by the viscous medium between the upper surface of the substrate 412 and the lower surface of the pressing portion 416.

For the above general case, an adhesive medium layer must be formed between the lower surface of the elastically bulging portion and the upper surface of the substrate. Such a layer of viscous medium may vary its thickness slightly by the amount of viscous medium or by the viscous pressure applied between the resilient bulge and the substrate.

The difference in thickness of the adhesive medium layer may result in a difference in distance between the movable contact and the fixed contact. If a contact of the so-called kind is used as a key switch, this difference does not affect the operation of the key switch. However, for the so-called contact-type contact-responsive switches of various types, the above-described small thickness difference will affect the detection of the contact response. In other words, this may cause some deviation in the touch-responsive operation of the switches each serving as a key linearly arranged on the keyboard of the musical instrument. Alternatively, this may cause other deviations in the touch-responsive operation in the instrument.

Since there is no adhesive medium layer in the present embodiment, there is no contact-response operation deviation in the key or musical instrument even in the case of the two types of contact-type contact-responsive switches as shown in fig. 41. The contact-responsive switch shown in fig. 41 provides a pair of the first movable contact 4131 and the first fixed contact 451, and another pair of the second movable contact 4132 and the second fixed contact 452. Thus, the present embodiment is advantageous in that the contact-responsive switch with high accuracy can be implemented at a relatively low price.

Incidentally, when the pressing mechanism 417 is stuck to the substrate 412, the adhesive medium may be coated on the lower surface of the pressing mechanism 417. Alternatively, double-sided tape may be attached to the presser bar 417 or the base plate 412, or other bonding techniques may be used.

In addition, the viscous medium may be coated on the upper portion of the pressurizing part 416 of the elastic swelling part 411 or 411 a. Similarly, when a double-sided tape is used, the tape can be stuck to the upper portion of the pressing portion 416 of the elastic bulge 411.

Fig. 42 is a sectional view of a keyboard apparatus in which the above-described switch device is assembled.

In fig. 42, the key switches 410 are mounted on the main frame 429 at positions corresponding to the white keys 425 or the black keys 426.

Similar to the embodiments described above, three common

base edge portions

425a, 425b, and 426a are provided. The common base edge portions 426a corresponding to the black keys are accumulated on the common

base edge portions

425a and 425b corresponding to the white keys, respectively.

With the three key blocks in the accumulated condition, the screw 428 is inserted into the screw hole 427, thereby screwing the key assembly together with the main frame 429 made of a metal plate as a whole.

A pair of stopper members 425c shaped like the letter "L" project downward from both side walls of the white key 425, respectively. The key guide 431 is secured to a main frame 429 that is responsive to the detent member 425 c. When the leading portion of the white key 425 is lifted up or down, the inner wall of the check member 425 slides along the side surface of the key guide mechanism 431, whereby the lateral swing movement of the white key 425 can be avoided.

The key switch 410 is fixed to a predetermined position of the main frame 429 in response to each of the white keys 425 and the black keys 426. The actuator 432 protrudes downward from the lower surface of the key such that the actuator faces the key switch 410. When the key is pressed, the actuator presses down the upper portion of the key switch 410, causing the bulging portion 414 to elastically deform. At this time, the movable contact 413 shown in fig. 39 is brought into contact with the fixed contact 415, and the key switch 410 is turned on, resulting in generation of a tone corresponding to the depressed key.

Incidentally, the contact surface 432a of the actuator 432 that contacts the key switch 410 can be shaped like the letter "H". In this case, it is possible to stabilize the pressed state between the actuator 432 and the annular ring 421 of the key switch 410.

Fig. 43 shows another example of the key switch. A feature of this example is that a plurality of projections 435 are provided, which are formed on the pressing portion 416 of the elastically bulging portion 411, so as to establish the positioning relationship between the elastically bulging portion 411 and the pressing mechanism 417. For example, two protrusions 435 are formed on the pressing portion 416 of the elastic swelling portion 411. Further, a plurality of holes 436 are formed through the pressing mechanism 417 at positions corresponding to the respective projections 435. The other parts illustrated in fig. 43 are similar to those of the above-described embodiment shown in fig. 41, and therefore, will be described in detail.

According to this example, by inserting the projections 435 into the holes 436, respectively, it is possible to easily fix the positional relationship between the elastically bulging portion 411 and the pressing mechanism 417. Due to the above-described fixing structure, the outer diameter of the through hole 418 of the pressing mechanism 417 can be relatively enlarged to easily cover the elastically bulging portion 411 with the pressing mechanism 417, and the bulging portion 411 of the elastically bulging portion 411 is inserted by the pressing mechanism 417. Even in this case, it is possible to accurately fix the position of the pressing mechanism 417 with respect to the elastically bulging portion 411. In short, it is possible to improve the performance of the assembly operation.

Incidentally, the structure of the key switch 410 is not limited to that shown in fig. 40, in which the elastically bulging portions 411 are continuously fixed at adjacent positions. In other words, it is possible to improve the key switch such that one elastic bulging portion is fixed to another elastic bulging portion adjacent thereto, respectively. In this case, it is necessary to provide two or more protrusions 422 to one elastic swelling portion 411.

Fig. 44 is a sectional view illustrating another switch device which provides a switch having an elastically bulging portion and another diaphragm switch, wherein the same portions as those shown in fig. 39 are denoted by the same numerals.

In this opening and closing member, a pressing mechanism 447 formed of a resin film in a sheet shape is used instead of the above-described pressing mechanism 417 shown in fig. 39. The pressing mechanism 447 is larger in size than the pressing mechanism 417. The reduced portion 446 is formed in the pressing mechanism 447 at a predetermined position away from the elastically bulging portion 411. The reduced portion 446 has a predetermined height. Such a reduced portion 446 can be formed from a metal mold. An upper contact 448 is attached to the inner surface of the reduced portion 446, and a lower contact 449 is secured to the substrate 412 opposite the upper contact 448. Thus, a membrane switch 440 is comprised of contacts 448 and a reduced portion 446.

Each of the upper contact 448 and the lower contact 449 is formed of a metal mold made of a predetermined material such as copper (Cu) or silver (Ag), and carbon powder is applied to these metals. Normally, the contacts 448 and 449 are fixed apart from each other. When the abbreviated portion 446 is pressed down, these contacts 448 and 449 contact each other, whereby the diaphragm switch 440 is turned on.

In the present switching device as shown in fig. 44, it is possible to form two switch types including the membrane switch 440 at the same time. When such a switch device is used as a key switch of an electronic musical instrument, it is possible to further reduce the manufacturing cost of the entire instrument. And further possibly as a size of the electronic musical instrument switch.

This type of switch device can be used for a tone switch, a sound switch or a push button switch (i.e., a partial selection switch) instead of the key switches of the keyboard for the electronic musical instrument. Alternatively, the switch device may be used for a push switch of an audio device. [F] Sixth embodiment

Finally, a sixth embodiment of the present invention will be explained with reference to fig. 45 and 46. This embodiment is characterized by reducing the thickness of the keyboard apparatus. Generally, a certain vertical length between the key upper surface and the key frame upper surface should be secured in order to avoid a lateral swinging movement of the key when the key is depressed. By reducing the length of the keyframe. The thickness of the keyboard may be reduced. However, this reduction in the thickness of the keyframe also serves to reduce the stability of the key moving in the lateral direction. Thus, a general keyboard apparatus suffers from a relatively large thickness at the front thereof.

This embodiment was invented for reducing the thickness of the keyboard apparatus at its front portion.

Fig. 45 is a side view illustrating a mechanical structure of a keyboard apparatus according to a sixth embodiment of the present invention. In fig. 45, a white key 501 is connected to a connecting portion 503 via a hinge portion 503. A black key 504 is also connected to the connecting portion 503. The keyframe 505 is fixedly secured to the body of the instrument (not shown). The key 501 can swing up and down about the hinge 502. The key frame corresponding to each key is arranged in parallel below a row of keys. On each of the key frames 505, a key switch 506 made of an elastic material is fitted on the key frame 505 with respect to each key. An actuator 513 is attached to the lower surface of the key 501. The actuator 513 is fixed such that the key switch 506 is driven by the actuator 513 when a key is pressed.

A key guide 507 made of urethane foam or other elastic material is attached to the front edge of the key frame 505. The key guide is partially bent downward from the lock frame 505.

Fig. 46 is a perspective view illustrating the key guide mechanism 507. The guide mechanism is mainly composed of a guide portion 510 and a stopper member 511. The guide portion 510 protrudes downward from the frame 505, and the stopper member 511 protrudes in both side directions of the frame 505. The side wall of the guide portion 510 is formed as a guide surface, and is lifted and lowered along the guide surface key 501. The guide surface is provided to prevent lateral rocking movement of the key 501. A pair of guided portions 508 project downward from the key 501 so that the guide portion 510 is sandwiched by them. Stopper portions 509 each formed in a hook shape project from a lower edge portion of the guided portion 508 in the longitudinal direction of the key 501. When the key 501 is restored from the key depression position, the stopper 509 comes into contact with the lower surface of the stopper member 511 of the key guide 507, stopping the lifting movement of the key 501. In other words, either detent portion 509 or detent element 511 is designed to form a lower limit detent.

The lower limit portion of the relative lower limit stopper at the time when the key switch 506 is pressed and deformed by the actuator 513 can be used to determine the reaction to the key position. Or a protrusion may be provided on the lower surface of the hinge portion 502 as a part of the lower limit stopper. In this case, the lower limit position can be determined when the projecting portion is in contact with the key frame 505 or with the upper surface of the stopper member 511 of the key guide 507.

In fig. 46, an upper limit stopper 509 is formed as a part of the lower edge portion of the guided portion 508. However, it is possible to form an upper limit stopper unrelated to the guided portion 508 and place it at another position. Alternatively, the lower limit stopper may be omitted so that the function of the lower limit stopper is solved by means of contacting the lower surface of the key 501 with the upper surface of the key guide 50-7. In this case, a thin felt material can be attached to the upper surface of the key guide 507.

In the case of a key operation (see arrow AA in fig. 45), the key 501 rotates about the hinge portion 502 and is deflected downward by a predetermined stroke as shown by a chain line in fig. 45. During key operation, the guided portion 508 of the key 501 moves downward while sliding with both side faces (i.e., guide surfaces) of the guide portion of the key guide 507 fixed to the front edge portion of the key frame 505. This makes it possible to avoid a lateral swinging movement or a relation with the downward deflecting action of the key 501. According to the present embodiment, the key guide 507 fixed to the edge portion of the key frame 505 is formed in such a manner that the main portion of the key guide 507 is directed downward of the key frame 505. Further, the protruding length of the key guide 507 and the lower edge portion of the guided portion 508 are the same, and when the key 501 is not depressed, the lower edge portion of the guided portion 508 is located below the key frame 505. Thus, the distance between the upper surface of the key 501 and the key frame 505 may be reduced. The reason why the distance can be reduced by the present embodiment will be described below.

Since the key 501 must be provided with a key-down stroke, if the key 507 projects upward from the key frame 505, the distance L₃(see fig. 45) at least the sum of the co-protruding portions for the key down stroke is required. If the embodiment is designed so that a distance L is provided₁Approximately equal to a distance L₂Theoretically, the distance L can be understood as₃Can be reduced to at least a stroke distance L₄Upper wall thickness L in same bond₅And (4) summing. However, in practice, only a small thickness L of the upper wall of the key 501₅The key pressure is not well endured. For this reason, to reinforce the 501 key, a side wall is provided for it. Thus, the distance L₃Equal to the distance of travel L₄A sidewall width L of the same key 501₆And (4) summing. In other words, if the sidewall width L of the key 501₅Can be reduced to a small width, and the key 501 can also bear the key pressing force, and the distance L₃And also decreases. As a result, the keyboard apparatus according to the present embodiment can be manufactured with a relatively small thickness.

Incidentally, the guide portion 510 of the key guide 507 can partially project above the key frame 505 while its downward projecting length is reduced.

Finally, as described thus far, the invention may be practiced or carried out in other ways without departing from its spirit or essential characteristics. Accordingly, the preferred embodiments described herein are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A keyboard apparatus for an electronic musical instrument, comprising:

a key frame;

a key whose fixed portion is supported by said key frame so that the front portion of said key can freely rotate up and down;

the method is characterized in that:

a key guide member protruding from a front portion of the key frame to guide the key in a key depression/release direction, the key guide member providing a guide surface along which the key is to be guided, and a lubricant being coated on the guide surface. Therefore, the key depression action can be smoothly performed;

a circuit board disposed along said keys and said key frame;

a key drop sensor mounted on said circuit board at a position facing a lower surface of said key, said key drop sensor sensing a key depression operation of said key when said key is depressed; and

a retention means formed continuously from said key frame, wherein a height of said retention means is set at least with respect to a partial height of said key frame surrounding said retention means to prevent lubricant from overflowing to said circuit board.

2. A keyboard assembly for an electronic musical instrument according to claim 1, wherein said leaving means comprises:

a rib is provided at a position between a leading edge portion of the circuit board and the key guide, so that the rib functions to prevent the lubricating oil from overflowing to the circuit board.

3. The keyboard apparatus for an electronic musical instrument according to claim 1, wherein the leaving means includes a stepped portion formed continuously with respect to the key frame, wherein a height of the stepped portion is set lower than a height of the circuit board to prevent the lubricant from overflowing to the circuit board.

4. A keyboard assembly for an electronic musical instrument according to claim 3, further comprising a reinforcing rib provided on a bottom surface of said stepped portion to prevent said lubricant from being drawn toward said circuit board.

5. A keyboard apparatus for an electronic musical instrument according to claim 3, wherein a lower limit stopper is formed as a part of said key guide member so that a lower position of said depressed key is restricted by said lower limit stopper, and another reinforcing rib is projected upward from an upper surface of said lower limit stopper at a position facing a front edge portion of said circuit board so that said reinforcing rib functions to prevent said lubricant from overflowing onto said circuit board.

6. A keyboard arrangement for an electronic musical instrument according to claim 1, wherein said aftermarket means has preventing means for preventing lubricant from overflowing onto said circuit board.