Abstract:
A keyboard device has a plurality of keys, each key having a support base where one end of each key is supported and is arranged to allow for movement, and a plate that hides the surface of the base. The keys are created with ultrasonic welding once the base and the plate merge. Thus, it is possible to weld while merging the base and the plate together, because the base and the plate are connected by ultrasonic welding. Compared to pasting the two together using traditional adhesives, it is possible to have the base securely bound to the plate. It is then possible to have performers use the device for an extended period of time. The result is the ability to curb the chances of the base and the plate becoming loose.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    The present invention relates to Japanese Patent Application No. 2006-264600, filed Sep. 28, 2006, which is incorporated herein in its entirety and which forms a basis for a priority filing date. 
       BACKGROUND 
       [0002]    The present invention relates generally to the field of keyboard devices and, more particularly, to keyboard devices that are able to reduce the occurrence of undesired sounds when pressing keys along with being able to provide a secure attachment of a cover plate to a base. 
         [0003]    Japanese Examined Patent 1974-35209 discloses use of a hard material to increase the strength of the keys. When pressed by a musical performer, if coarse material was used to increase the absorbency, there was a problem in that the keys were weak. 
         [0004]    The surface material (plate) submerged into absorption fluid is affixed to the key (base) surface using an adhesive. The key affixes the surface material with a different characteristic than the key surface, as described in Japanese Unexamined Patent 1995-44156. 
         [0005]    However, the key affixed to both the base and the plate was pressed excessively by performers, and if it continued for a long period of time after being affixed, the strength of the adhesive could wear off, and the plate could become loose. 
         [0006]    Also, because the adhesive is applied between the base surface and the plate surface, if the adhesive is not evenly distributed, one area can become loose, leaving an empty space between the base and the plate. When this empty space occurs, an undesired noise can occur when the performer touches the keys, and this may confuse the performer. 
       SUMMARY 
       [0007]    Embodiments of the present invention provide a keyboard device that can reduce the occurrence of undesired noises when the keys are pressed, strengthen the bond between the base and the plate, and/or solve other problems mentioned above. 
         [0008]    In one aspect, a keyboard device has a plurality of keys, wherein each key has a support base where one end of each key is supported and is arranged to allow for movement. The keyboard also has a plate that hides the surface of the base. The keys are formed with ultrasonic welding of the merged base and plate. It is possible to weld while merging the base and the plate together, because the base and the plate are connected by ultrasonic welding. Compared to gluing the base and plate together using traditional adhesives, it is possible to have the base securely bound to the plate. It is then possible to have performers use the device for an extended period of time. The result is the ability to reduce the chances of the base and the plate becoming loose. 
         [0009]    In one embodiment, the base is created with a wood-coloured resin, while the plate is created with a white-coloured resin. Because the plate is created with a white-coloured resin, the result is the ability to have a keyboard device that has an elegant sense of charm with simple composition. 
         [0010]    In one embodiment, the base and the plate may have different kinds of materials added to them. Thus, the base and the plate may be composed of a primary ingredient with a similar resin. Because different ingredients are added, the result is that it is possible to demonstrate special qualities on these objects. For example, by adding an ingredient which hardens the plate, it is possible to increase the strength of the plate. In addition, it is possible to increase the hygroscopic characteristics of a plate by adding a material which increases the water absorption characteristics of the plate. In addition, it is possible to securely fix the objects together with ultrasonic welding because the base and the plate may use the same primary ingredient. 
         [0011]    In one embodiment, the plate has a surface on the front that hides the front side of the base. Thus, the plate is affixed from top and front surfaces. The top surface is welded by ultrasonic energy on the top surface of the base, and the front surface serves to conceal the front surface of the base. In general, because the keyboard device is aligned with and attached to the keys, the areas regularly seen by performers are the top and front surfaces. When using this keyboard device, the result is that it is possible to minimize any loss of elegance with a simple design, because the plate conceals the top and front surfaces. Also, after the base and plate are welded, the result is that it is possible to minimize the amount of manufacturing work required with the presence of the top and front surface, because only the top surface is welded by ultrasonic welding. 
         [0012]    In one embodiment, the plate has an area or projection that protrudes from the top surface to the base for melting by ultrasonic welding. 
         [0013]    More specifically, the plate has a surface facing the base and the surface has a first area extending from the front surface of the base to a predefined distance from the front surface. The ratio of the at least one protrusion area in the first area to the overall first area is greater than the ratio of the at least one protrusion area located outside of the first area to the overall area located outside of the first area. The edge of the keys sometimes makes undesired noises when touched if there are many cracks between the base and the plate from being pressed by performers. However, with the above ratios of welding protrusion areas relative to the areas of the plate or base, it is possible to lessen these noises and reduce the cracks between the base and the plate due to the fact that it is possible to securely weld the portion of the keys pressed by performers. 
         [0014]    In one embodiment, the base has a convex shape in the location of the welding space once the plate has merged. Thus, it is possible to house the melted resin within the gap in case the protruding component used for welding melted, because the gap is formed at a location which corresponds to the welding space. Therefore, the result is that the melted resin remains between the top surface of the base and the plate, and it is possible to prevent the plate from slanting when being welded against the base. 
         [0015]    In one embodiment, the welded area has an incline from front to back, and the plate has an opening connected to an inclined welding space after the plate merges. The incline may be curved, or the incline may be flat. A circular cone may be formed at the center of the path linking the front and back sides to be welded with the base. The plate will be urged toward the back side of the base as the incline is moved through the opening while welding. The result of this can create a crack between the front side of the plate and the front side of the base. The plate also cannot stay in position because it will move along the incline to the center from the edge of the opening while welding. Thus, the incline with one welding space is located at the end of the top surface of the plate. This inclined weld has a slant from the edge side to the end side. The incline is attached to an opening set up on the base. Generally, if using ultrasonic energy to weld, the incline will melt and be welded while sliding the opening to the end side, because the plate is welded by ultrasonic energy waves when held down from the top. Therefore, the result is that it is possible to improve the quality of the keys&#39; outer surface, and also possible to prevent cracks from forming between the front ends of the base and the plate. 
         [0016]    In one embodiment, the plate has a protuberance that penetrates through the top surface of the base. The base has enough empty space to house the front end of the protuberance and the area connected to the front side of the protuberance. The distance between the front side of the base to the linked area and the distance between the front side and the end side is substantially identical. On the base is a receptacle area with enough empty space to house the end edge on the protuberance and the linking component which links with the edge side of the protuberance. Also, in the event the plate merges with the base, the protuberance is housed while linking the receptacle area linking component and the edge end of the protuberance together, because the distance made between the edge end of the base and the linking component as well as the distance between the front surface and the edge end of the protuberance are identical. Therefore, when placing the plate on the base, the plate may be prevented from moving or sliding away from its proper position, because it is possible to select a location where movement to the edge end is restricted. Also, the yield rate may be improved and the possibility of having a defective product may be reduced, because the plate is placed in its proper position. 
         [0017]    In one embodiment, the plate supports the protrusion area from the top portion to the base. The protrusion area is arranged in a second dimension orthogonal to the first dimension and joined with the front side and the back side. The base provides a receptacle with enough empty space to house the length of the front end of the protruding area by linking each linking space with the space outside the protrusion area in the second dimension. The distance from the outer edge of the base area to the linking space in the second dimension is the same as the distance between the outer surface on the top and the outer side of the protruding area. As in the receptacle, it may be composed of a linking component that links with the end side of the protuberance. There may also be receptacle space for housing every protuberance as there should be a component that links with the outer surface on the second path of the protuberance. Furthermore, the protuberance may hold the welded material melted by ultrasonic welding. On the edge of the protruding area linked to the linking component and the linking component for the housing space is a curved surface, or similarly, a plane or a protruding surface, or other suitable shapes. The linking component and the protrusion area are more ideal for protruding shapes from the top surface to a perpendicular path. This will make it impossible to choose a location that is easy for the protrusion area to detach from the housing space if the end of the protrusion area is obtuse on the top surface. On the other hand, if it is acute, the protrusion area may become a problem if the plate merges with the base. As used herein, “roughly equal distance” also includes identical distant. It should also be separate from ranges where it is possible to choose a location for the plate in respect to the base. This separation is ideally set by the largeness of the plate and the base. Thus, on the plate, a protuberance sits in the second dimension running orthogonally to the first dimension linking the edge with the rear end. For the base, it is equipped with a receptacle which has enough empty space to house the edge of the protuberance with the linking component linking with the edge outside the protuberance along the second dimension. Also, in the event the plate merges with the base, the protuberance is housed while linking the housing device linking component and the edge end of the protuberance together, because the distance made between the edge end of the base and the linking component as well as the distance between the front surface and the edge end of the protuberance are substantially identical. Therefore, when placing the plate on the base, the result is being able to prevent the plate from moving from its proper position to a position the plate slides to, because it is possible to select a location where movement to the second path of the plate is restricted. Also, another result is being able to improve the yield rate and reduce the possibility of having a defective product because the plate is placed in its proper position. 
         [0018]    In one embodiment, the base has multiple support areas to support the bottom surface of the plate once the plate has merged. The plate has a space where it fits between the supports and is arranged on the bottom surface. Thus, when the plate is placed on top of the base, the lower front surface on the plate will be supported by the supports. Furthermore, the fitting space for the plate is housed between the supports. Therefore, when the plate is merged with the base, the plate is prevented from sliding away from its proper position, because of the ability to choose a location along the second dimension running orthogonally to the dimension linking the rear side with the edge using the supports and the fitting space. Also, the occurrence of undesired noises is reduced by preventing the front surface from loosely flapping from vibrations when stroking the keys, yet making it so that the front surface need not be welded because the lower section of the front surface of the plate is supporter by the support device. 
         [0019]    In one embodiment, the front surface of the plate area forms a groove extending from the lower surface toward the top surface on the surface of the base area. The base area forms a notch area located in the place which corresponds to the grooved area at the front end of the lower surface. Thus, on the front surface of the plate, a grooved area extended from the edge of the lower section on the front surface toward the top surface is formed at the surface of the base. On the base, it is possible to apply an adhesive to this groove from the notch component with ease, because the notch component is formed at the location targeted for the groove area at the lower edge. Therefore, after the plate and the base are welded using ultrasonic energy, if a gap exists between the area on the front surface and the entire surface, it is possible to conjoin the entire front surface with the front surface portion and apply an adhesive from the notch. Thus, the result is being able to reduce the likelihood of defective products through simple manufacturing. 
         [0020]    In one embodiment, the base has a set empty space formed between the rear end of the plate area once the plate has merged. Thus, on the base, it is possible to house the remains of a gate remaining on the rear side of the plate at a fixed space. Generally, the rear end of the keys do not affect the aesthetics of the keys and, thus, the aesthetics of the keys are not impacted by the gate on the rear end of the plate. Therefore, the result is being able to omit from the manufacturing process, a procedure for removing or otherwise processing a gate by creating this space, and in turn, being able to design a cost-efficient device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1(   a ) is a top view of a keyboard device according to an embodiment of the present invention; 
           [0022]      FIG. 1(   b ) is a side view of the keyboard device of  FIG. 1(   a ); 
           [0023]      FIG. 2(   a ) is a perspective view of a white key according to an embodiment of the present invention prior to welding; 
           [0024]      FIG. 2(   b ) is a perspective view of the white key of  FIG. 2(   a ) after the welding; 
           [0025]      FIGS. 3(   a )-( d ) are various views illustrating the structure of an exemplary white key according to an embodiment of the present invention, wherein  FIG. 3(   a ) is a side view of the key prior to welding;  FIG. 3(   b ) is a bottom view of the key with the plate sitting on the IIIb area,  FIG. 3(   c ) is a top view of the key with the plate sitting on the IIIc area, and  FIG. 3(   d ) is a cross-sectional view taken along IIId-IIId of the key prior to welding; 
           [0026]      FIGS. 4(   a )-( d ) are various views illustrating the exterior and the cross-section of an exemplary white key according to an embodiment of the invention, wherein  FIG. 4(   a ) is a top view of the white key,  FIG. 4(   b ) is a bottom view of the white key,  FIG. 4(   c ) is a cross-sectional view along IVc-IVc of the white key prior to welding, and  FIG. 4(   d ) is a cross-sectional view along IVd-IVd of the white key after welding; 
           [0027]      FIGS. 5(   a )-( c ) are various cross-sectional views illustrating the composition of the protuberance area and the housing space according to an embodiment of the invention, wherein  FIG. 5(   a ) is a cross-sectional view taken along Va-Va (in  FIG. 4(   c )) of the edge of the exemplary white key, Figure (b) is a detailed cross-sectional view of the area enclosed by the dotted line Vb in  FIG. 4(   c ), and  FIG. 5(   c ) is a detailed cross-sectional view of the area enclosed by the dotted line Vc in  FIG. 4(   d ); 
           [0028]      FIGS. 6(   a )-( d ) are various cross-sectional views illustrating the structure of the protrusion area and the hole according to an embodiment of the invention, wherein  FIG. 6(   a ) is a cross-sectional view taken along VIa-VIa in  FIG. 4(   a ),  FIG. 6(   b ) is a detailed cross-sectional view of the area surrounded by dotted line VIb in  FIG. 4(   a ),  FIG. 6(   c ) is a detailed cross-sectional view of the area surrounded by dotted line VIc in  FIG. 4(   c ), and  FIG. 6(   d ) is a detailed cross-sectional view of the area surrounded by dotted line VId in  FIG. 4(   d ); 
           [0029]      FIGS. 7(   a ) and ( b ) illustrate the front end of the exemplary white key, wherein  FIG. 7(   a ) shows the white key on arrow VIa ( FIG. 4(   c )) prior to welding, and  FIG. 7(   b ) shows the white key on arrow VIIb ( FIG. 4(   d )) after welding; 
           [0030]      FIGS. 8(   a ) and ( b ) illustrate detailed cross-sectional views of a lower section of the front end of the exemplary white key, wherein  FIG. 8(   a ) is a detailed cross-sectional view of a section encompassed by dotted line VIIIa ( FIG. 4(   c )), and  FIG. 8(   b ) is a detailed cross-sectional view of a section encompassed by dotted line VIIb ( FIG. 4(   d )); 
           [0031]      FIGS. 9(   a )-( c ) illustrate the composition of the lower front ends of the base and the plate according to an embodiment of the invention, wherein  FIG. 9(   a ) is a detailed cross-sectional view of a section encompassed by dotted line IXa ( FIG. 4(   b )),  FIG. 9(   b ) is a perspective view of the front end section of the front surface area according to an embodiment of the invention,  FIG. 9(   c ) is a perspective view of the lower section of the front surface; and 
           [0032]      FIG. 10  is a cross-sectional view illustrating a section encompassed by dotted line X in  FIG. 4(   d ). 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    Below are examples of certain embodiments and uses for certain embodiments of the present invention, with figures for reference and elaboration.  FIG. 1  shows the of a keyboard device  1  according to an embodiment of the present invention in a “real world” use.  FIG. 1(   a ) illustrates a top view of a keyboard device  1 , while  FIG. 1(   b ) is a side-view of the keyboard device  1 . Also, the explanation below illustrates a first dimension as a straight line along a white key  2  and a black key  3  (marked as dimension X), a second dimension as a path running orthogonal to X (marked as dimension Y), and a third dimension running perpendicular to the plane formed by X and Y (marked as dimension Z). 
         [0034]    As shown in  FIGS. 1(   a ) and ( b ), the keyboard device  1  is provided with several white keys  2  and black keys  3 , which can be pressed by performers. White key  2  and black key  3  have axle gaps in them on one end of each key. A turning axle  5  installed on the chassis  4  is installed in the center through the axle gaps of the keys for allowing the keys to pivot. 
         [0035]    Also, when a white key  2  or a black key  3  is pressed and pivoted about the axle  5 , a corresponding hammer  6  in the chassis  4  is swung about its center and activates a switch  9  on a printed board  8 , which is secured by an actuator  7  of the hammer  6  below the chassis  4 . On the keyboard device  1 , the key behaviour is determined by operating the switch  9 , and sounds are emitted by a control unit (not shown in the figures). 
         [0036]      FIGS. 2(   a ) and ( b ) are perspective illustrations of a white key  2  according to an embodiment of the present invention.  FIG. 2(   a ) illustrates a pre-weld white key  2 , while  FIG. 2(   b ) illustrates a post-weld white key  2 . Also, the white keys  2  have alternate shapes based on pitch. In  FIG. 2 , the shape of the white key  2  is such that the left side (the visible side in  FIG. 2)  is formed on a plane extending to roughly the entire length, while the right side (the hidden side in  FIG. 2 ) is formed with a difference in level. Therefore, one end of the white key  2  in the X dimension is formed with a greater thickness in the Y dimension. The section with this greater thickness is on the “depressed” area  2   a  of the white key  2 . The other section is on the “long/narrow” area  2   b . (See  FIG. 2(   b )). 
         [0037]    The white key  2  is composed of a base  21  pivotably supported on the turning axle  5 , and a plate  22  concealing at least one surface of the base  21 . The base  21  has a top surface  23  and a front surface  24  on a front side (in the X dimension). The plate  22  is composed of a top surface area  25  welded by ultrasonic waves to the top surface  23  of the base  21 , and a front surface area  26  hiding the front surface  24  of the base  21 . 
         [0038]    Also, because the white key  2  and black key  3  are adjoined and aligned in rows (see  FIGS. 1(   a ) and (b)), the top surface and front surface on the white key  2  are areas frequently seen by the performer. The white key  2  according to embodiments of the present invention can improve the quality of the superficial areas of keyboard device  1  with its composition. 
         [0039]    In one embodiment, the base  21  is formed of a wood-coloured resin, and the plate  21  is formed of a white-coloured resin. Therefore, it is possible to manufacture a white key  2  with an aesthetically-pleasing appearance, while allowing assembly of the device with ease. 
         [0040]    The base  21  and the plate  22  may be merged together by a mould made from the resin. Therefore, the base  21  and the plate  21  can be tightly bonded together by ultrasonic welding, because they may have a similar main ingredient. Also, a hard material can be added to the resin in the plate  22 , thus strengthening the plate  22 . 
         [0041]    Next, with reference to  FIGS. 3-10 , a detailed explanation is provided of the structure of a white key  2  according to an embodiment of the present invention. 
         [0042]      FIGS. 3(   a )-( d ) illustrate the structure of white key  2 .  FIG. 3(   a ) is a side-view illustration of a plate  22  prior to welding, while  FIG. 3(   b ) is a bottom view of the plate  22  sitting on the IIIb area in  FIG. 3(   a ).  FIG. 3(   c ) is a top view of the plate  22  sitting on the IIIc area in  FIG. 3(   a ).  FIG. 3(   d ) is a cross-sectional view taken along IIId-IIId of the white key  2  prior to welding. 
         [0043]    As shown in  FIG. 3(   a ), in producing the white key  2 , the plate  22  is merged with the base  21  at a roughly perpendicular direction (arrow A). Afterwards, each key is welded by ultrasonic welding, using a welding device not shown in this diagram. 
         [0044]    Below is an explanation of features for merging the base  21  and the plate  22  and ultrasonic welding according to an embodiment of the invention. 
         [0045]    As shown in  FIG. 3(   b ), on the top surface area  25  of the plate  22 , a pair of protuberances  33  protrude out from the underside of the top surface area  25  to an approximately perpendicular position so that the plate  22  can be properly positioned with respect to the base  21 . The plate  22  is also provided with welding protrusion areas  31   a - f  and protrusion  32  protruding from the underside of the top surface area  25  in an approximately perpendicular direction. 
         [0046]    The welding protrusion areas  31   a - f  extend in a straight-line fashion along the X dimension on the plate  22 . Protrusion areas  31   a  and  31   b  extend along substantially the total length of the plate  22 . Protrusion areas  31   c - e  are at an area corresponding to and targeted for the key depression area  2   a  on the plate  22 . Protrusion area  31   f  extends along the front edge of the plate  22  in the Y dimension. Protrusion area  32  is formed at the rear end of the plate  22 . The pair of protuberances  33  are formed on each side of the protrusion area  31   f.    
         [0047]    As shown in  FIG. 3(   c ), on the top surface area  23  of the base  21 , once the plate  22  is placed down, grooves  41   a - 41   f  on the base  21  correspond to the protrusion areas  31   a - 31   f  of the plate  22 , an opening or hole  42  of the base  21  corresponds to the protrusion area  32  of the plate  22 , and a housing space  43  on the base  21  houses the pair of protuberances  33  on the plate  22 . Thus, the grooves  41   a - 41   e , the hole  42 , and a pair of receptacles  43  each merge at a location corresponding with the protrusion areas  31   a - 31   f , protrusion area  32 , and protuberance  33 , respectively. 
         [0048]    The protrusion areas  31   a - 31   f  occupy a portion of the depression area  2   a , and a portion of the length of protrusion areas  31   a  and  31   b  also occupy the area  2   b . The ratio of the area occupied by the protrusion areas  31   a - 31   f  within the depression area  2   a  relative to the overall depression area  2   a  is greater than the ratio of the area occupied by the portion of the length of protrusion areas  31   a  and  31   b  that occupy the area  2   b  relative to the overall area  2   b . In the illustrated example, the key depression area  2   a  is welded in six places (along protrusion areas  31   a ,  31   b ,  31   c ,  31   d ,  31   e ,  31   f ), while the long, narrow area  2   b  is welded in two places (along protrusions  31   a  and  31   b ). As a result, when the base  21  and plate  22  are welded together, the weld density is greater in the key depression area  2   a  than in the long, narrow area  2   b . As a result, the key depression area  2   a  is able to avoid a gap or empty space from forming between the base  21  and the plate  22 , and, thus, limit the occurrence of undesired noises caused by such gap or empty space during key depression. 
         [0049]    Next, with reference to  FIG. 3(   d ), a description is provided of the protrusion areas  31   a - 31   f  on the plate  22  and the grooves  41   a - 41   f  on the base  21 . Also, because the cross-sectional view of the protrusion areas  31   a - 31   f  and the grooves  41   a - 41   f  are all respectively similar, the following description relates to the protrusion area  31   e  and the groove  41   e.    
         [0050]    The protrusion area  31   e  is formed in a convex, generally triangular shape on the cross-sectional view. The groove  41   e  is formed in a generally rectangular gap on the cross-sectional view. Also, the width of the groove  41   e  is larger than the width of the protrusion area  31   e.    
         [0051]    Therefore, once the plate  22  is placed on top of the base  21 , the tip of the protrusion area  31   e  is joined with the surface of the groove  41   e . Then, if the base  21  and the plate  22  are welded together using ultrasonic waves, the equal distribution strengthens the bond on the groove  41   e  where the protrusion area  31   e  melts. Also, it is possible to prevent the resin melted by the ultrasonic welding from jutting out within the groove  41   e , and it is possible to avoid inadvertent welding of the top surface area  25  of the plate  22  and in a manner in which melted resin flows between the top surface  23  of the base  21 . 
         [0052]      FIGS. 4(   a )-( d ) illustrate the exterior and cross-sectional views of the exemplary white key  2 .  FIG. 4(   a ) is a top view of the white key  2 , and  FIG. 4(   b ) is a bottom view of the white key  2 .  FIG. 4(   c ) is a cross-sectional view taken along IVc-IVc of  FIG. 4(   a ) of the white key  2  prior to welding.  FIG. 4(   d ) is a cross-sectional view taken along IVd-IVd in  FIG. 4(   a ) of the white key  2  after welding. Further details of the embodiment of  FIGS. 4(   a )-( d ) are described with reference to  FIGS. 5-10 . 
         [0053]    With reference to  FIGS. 5(   a )-( c ), a description is provided of a receptacle or housing space  43  on the base  21  and a protuberance area  33  on the plate  22 .  FIGS. 5(   a )-( c ) are cross-sectional views displaying the configuration of the protuberance area  33  and the receptacle  43 .  FIG. 5(   a ) is a cross-sectional view taken along Va-Va (see  FIG. 4(   c )) of the edge of the white key  2 .  FIG. 5(   b ) is a detailed cross-sectional view of the area enclosed in the dotted line Vb in  FIG. 4(   c ).  FIG. 5(   c ) is a more detailed cross-sectional view of the area enclosed by the dotted line Vc in  FIG. 4(   d ). 
         [0054]    As shown in  FIG. 5(   a ), the length of the white key  2  (base  21  and plate  22 ) in the Y dimension is t 1 . The distance from the exterior surface  33   a  of the protuberance area  33  to the outer edge of the plate  22  is t 2 . The distance between the exterior surfaces  33   a  of the two protuberance areas  33  is t 3 . For the base  21 , the distance from the exterior surface  43   a  of the receptacle  43  to the outer edge of the base  21  is also t 2 , and the distance between the outer edges  43   a  of the two receptacles  43  is also t 3 . 
         [0055]    Therefore, when merging the plate  22  with the base  21 , it is possible to properly position the plate  22 , because the exterior surfaces  33   a  and the exterior surfaces  43   a  are aligned. 
         [0056]    As shown in  FIG. 5(   b ), an edge of the protuberance  33  in the X dimension is a side  33   b . The corresponding edge of the housing space  43  in the X dimension is a side  43   b . Again, the distance between the side  33   b  and the middle surface of the front surface area  25  and the distance between the outer surface of the front surface  24  and the side  43   b  are both t 4 . 
         [0057]    Therefore, as shown in  FIG. 5(   c ), when merging the plate  22  with the base  21 , it is possible to select a merge location on the plate  22  along the X dimension, because the side  33   b  and the side  43   b  are aligned. 
         [0058]    The sides  33   a ,  33   b ,  43   a  and  43   b  are aligned along the Z dimension on the white key  2 . Thus, the sides  33   a ,  33   b  start from the top surface area  25  along an approximately perpendicular path, and the sides  43   a ,  43   b  start from the top surface  23  along an approximately perpendicular path. For example, if the sides  33   a ,  33   b ,  43   a , and  43   b  have a slant from the edges to the rear end, there will be difficulty in having the protrusion area  33  placed in a location that is easy to disconnect from. If the sides  33   a ,  33   b ,  43   a  and  43   b  have an incline from the rear end to the edge (in the X dimension from the right to the left), the protrusion area  33  becomes a hindrance when the plate  22  is planted on top of the base  21 . If using this example, the protrusion area  33  can limit the possibility of being disconnected from the receptacle  43 , and it is possible to prevent the protrusion  33  from becoming a strain on the receptacle  43 , because the sides  33   a  and  33   b  protrude from the top surface area  25  along an approximately perpendicular path, and the sides  43   a  and  43   b  start from the top surface  23  along an approximately perpendicular path. 
         [0059]    In this example, arranging the sides  33   a ,  33   b ,  43   a , and  43   b  onto a plane makes a semicircle-shaped protuberance on the protuberance area  33 , and a housing device may be provided with a corresponding semicircle-shaped crevice. In this case, the protuberance area  33  and the housing space  43  are merged at a location where the edge of the protuberance area  33  and the exterior, curved surface, and the edge of the receptacle  43  and the exterior, curved surface are conjoined. Alternatively, the shape of the edge of the protuberance area  33  and the exterior edge, and the edge of the receptacle  43  and the exterior edge conjoined to the edges of the protuberance area  33  and the receptacle  43 , need not be flat but may be curved surfaces, or have pointed shapes, or other suitable shapes. 
         [0060]    Furthermore, the protuberance area  33  has the sides  33   a  and  33   b , while the housing space  43  may have the sides  43   a  and  43   b  that attach with the sides  33   a  and  33   b . Also, for the protuberance area  33  and the receptacle  43 , each pair may include one protuberance area  33  with one housing space  43 , or may be two or more protuberance areas  33  for each one housing space  43 . 
         [0061]    The distance between the surface of an end  33   a  of the projection area  22  to the exterior surface of the plate  22  is the same distance (t 2 ) as the distance between the surface of an end  43   a  of the housing space  43  to the exterior surface of the base  21 . In addition, the distance between the surface of an end  33   b  of the projection area  33  to the interior of the front section  26  of the plate  22  is the same distance (t 4 ) as the distance between the surface of an end  43   b  of housing space  43  to the surface of the front  24  of the base  21 . However, in other embodiments, the distance between the surface of an end  33   a  of the projection area  22  to the exterior surface of the plate  22  can be made different from the distance between the surface of an end  43   a  of the housing space  43  to the exterior surface of the base  21 . Similarly, the distance between the surface of an end  33   b  of the projection area  33  to the interior of the front section  26  of the plate  22  can also be made to be different from the distance between the surface of an end  43   b  of the housing space  43  to the surface of the front  24  of the base  21 . In that regard, when putting plate  22  on base  21 , the distances t 2  and t 4  need not be completely in agreement, but should be sufficiently accurate to set an attachment position. For example, the distance between the surface of an end  33   a  of the projection area  33  to the exterior surface of the plate  22  is the distance (t 2 ), which may be slightly longer than the distance between the surface of an end  43   a  of the housing space  43  to the exterior surface of the base  21  (t 2 ′), where: 
         [0062]    t 2 -t 2 ′&gt;0 when t 2 &gt;t 2 ′. Similarly, the distance between the surface of an end  33   b  of the projection area  33  to the interior of the front section  26  of the plate  22  (t 4 ) is a distance slightly longer than the distance between the surface of an end  43   b  of housing space  43  to the surface of the front  24  of the base  21  (t 4 ′), where t 4 -t 4 ′=about 0.1 mm. 
         [0063]    Next, with reference to  FIGS. 6(   a )-( d ), a description of the protrusion area  32  on the plate  22  and the hole  42  on the base  21  is provided.  FIGS. 6(   a )-( d ) are cross-sectional views displaying the structure of the protrusion area  32  and the hole  42 .  FIG. 6(   a ) is a cross-sectional view taken along the VIa-VIa ( FIG. 4(   a )) of the white key  2 .  FIG. 6(   b ) is a detailed cross-sectional view of a section surrounded by the dotted line VIb in  FIG. 4(   a ).  FIG. 6(   c ) is a detailed cross-sectional view of a section surrounded by the dotted line VIc in  FIG. 4(   c ).  FIG. 6(   d ) is a detailed cross-sectional view of a section surrounded by the dotted line VId in  FIG. 4(   d ). 
         [0064]    As shown in  FIGS. 6(   a ) and ( b ), in one embodiment, the protrusion area  32  is a sloped area made up of a lower tier  32   a  on a circular cone protruding from the middle surface of the top surface area  25  (the side on the base  21 ), a central tier  32   b  on a cylinder connected to the lower tier  32   a , and an upper tier  32   c  on the cone connected to the central tier  32   b . Also, for the opening or hole  42 , an opening  42   a  is formed on top of the top surface  23 . The length of the opening  42   a  in the Y dimension is the approximately the diameter of the central tier  32   b . The length of the opening  42   a  in the Y dimension and the diameter of the central tier  32   b  are t 5 . 
         [0065]    Additionally, as shown in  FIG. 6(   c ), the location where the plate  22  is placed with the base  21  is the location where the opening  42   a  and the surface of the upper tier  32   c  are aligned. The length of the opening  42  in the X dimension is t 6 , which should be longer than t 5  in the Y dimension. Thus, the opening  42  has a generally elliptical crevice (see  FIG. 3(   c )). 
         [0066]    Also, the plate  22  moves from its place in  FIG. 6(   c ) to a lower region along an approximately perpendicular direction (Z dimension), and if welded using ultrasonic waves once it merges with the base  21 , the incline surface on the upper tier  32   c  is welded while being slid through the opening  42   a  to the rear end (left side in the X dimension), because the plate  22  is pressed down to the base  21 . Because the surface of the lower tier  32   a  also has an inclined surface, if welded with ultrasonic waves, the plate  22  is urged to the rear side of opening  42 . As a result, it is possible to improve the quality of the exterior because it is possible to prevent cracks or gaps from forming between the front surface  24  on the base  21  and the front surface area  26  on the plate  22 . 
         [0067]    As shown in  FIG. 6(   d ), if the plate  22  is affixed with the base  21 , a part of the opening or hole  42  and the protrusion area  32  is melted together, and becomes a melted area  27 , which will secure the plate  22  with the base  21 . Also seen in  FIG. 6(   b ), the plate  22  is welded while being guided to the center point in the Y dimension, because the diameter of the central tier  32  and the length of the opening or hole  42  in the Y dimension are roughly the same lengths (t 5 ). Therefore, not only is the plate  22  extended to the rear end in the X dimension, it is also possible to select a location along the Y dimension simultaneously. 
         [0068]    Regarding the protrusion area  32 , areas making up the lower tier  32   a , the central tier  32   b  and the upper tier  32   c  may have a protrusion area on only one cylinder extending out from the middle surface of the upper surface area  25 . If the shape contains an incline from one end to the other, the plate  22  would be extended to the end side when welding with ultrasonic waves. 
         [0069]    Next, with reference to  FIGS. 7 and 8 , a description of the composition of a front end of a white key  2  is provided.  FIGS. 7(   a )-( b ) illustrate the front end of the exemplary white key  2 .  FIG. 7(   a ) shows the white key  2  on arrow VIa prior to welding.  FIG. 7(   b ) shows the white key  2  on arrow VIIIb after welding.  FIGS. 8(   a )-( b ) are detailed illustrations of a lower section of the front end of the white key  2 .  FIG. 8(   a ) is a detailed cross-sectional view of a section encompassed by the dotted line VIIIa in  FIG. 4(   c ).  FIG. 8(   b ) is a detailed cross-sectional view of a section encompassed by the dotted line VIIb in  FIG. 4(   d ). 
         [0070]    As shown in  FIG. 7(   a ), on the lower end of the base  21  (Z dimension), a pair of supporters  44 , each protruding from the front surface  24  to the front side, are installed on the left and right sides (in Y dimension). As shown in  FIG. 8(   a ), if the supporter  44  is viewed from a transverse direction, it appears in the form of a general shape of an “L.” For the lower section of the front surface  26  on the plate  22 , an incline  34  is formed at a location targeted by each supporter  44 . A section included in the incline  34  becomes a fitting space  35 , suited to fit into the space between the supporters  44 . 
         [0071]    As shown in  FIG. 7(   b ), if the plate  22  is affixed to the base  21 , the supporters  44  and the inclines  34  are conjoined, with incline  34  being supported by supporters  44 . Fitting space  35  is fitted in the space between supporters  44 . Therefore, fitting space  35  is able to go into a location along a path (Y arrow) on plate  22 , because it fits in the space between supporters  44 . Also, as shown in  FIG. 8(   b ), after welding the plate  22  with the base  21 , when pressing keys, it is possible to stop the front surface area  26  from moving loosely and also reduces the occurrence of undesired noises as the inclines  34  and the supporters  44  are conjoined. 
         [0072]    Next, with reference to  FIGS. 9(   a )-( c ), a description of the lower part of the front end of the plate  22  and the base  21  is provided.  FIGS. 9(   a )-( c ) feature the composition of the lower front ends of the base  21  and the plate  22 .  FIG. 9(   a ) is a detailed cross-sectional view of a section encompassed by dotted line IXa on  FIG. 4(   b ).  FIG. 9(   b ) is a squint view of the front end section of the front surface area  26 .  FIG. 9(   c ) is a squint view of the lower section of the front surface  23 . 
         [0073]    As shown in  FIG. 9 , a groove  36  is formed on the middle surface of a fitting element  35  on the plate  22 . A notch area  46  is formed at the location targeted by the groove  36  on the base  21 . As shown in  FIG. 9(   b ), the groove  36  runs from the lower end of the front surface area  26  (top side, Z dimension), and the depth of the groove reduces while the width of the groove shortens along its length. As illustrated in  FIG. 9(   c ), the notch area  46  runs from the lower end of the front surface  24  (top view, Z dimension) to the top surface  23  (bottom view, Z dimension), and forms a “U” shaped notch. 
         [0074]    The groove  36  and the notch  46  allow for applying an adhesive with ease from the groove  36  to the notch  46  once the base  21  and the plate  22  have been welded together. If the plate  22  and the base  21  are welded together and a new gap or crack forms between the front surface  24  and the front surface area  26 , the product can be defective. However, the product can be improved or made operable by applying an adhesive from the notch  46  to the groove  36  to affix the front surface  24  and the front surface area  26 . 
         [0075]    Next, with reference to  FIG. 10 , a description of the structure of the rear end of the plate  22  is provided.  FIG. 10  is a cross-sectional view showing the rear area of the plate  22  and a detailed cross-sectional view of a section encompassed by the dotted line X in  FIG. 4(   d ). 
         [0076]    Here, an explanation of the plate  22  as a moulded element is provided. In one embodiment, the plate  22  has a gate on the exterior surface, because it has been moulded. In this situation, however, if the gate is not removed, this will make the white key  2  less aesthetically pleasing, and because there is a possibility that it may get damaged during welding, the gate may be removed before placing the plate  22  on top of the base  21 .  FIG. 10  illustrates such a case where there is a gate  37  on the rear end (left side, X dimension) of the plate  22 . 
         [0077]    On the embodiment of the plate  22  shown in  FIG. 10 , the remaining gate (gate  37 ) on the rear end is insufficient for processing. On the base  21 , a free space  47  exists in a location targeted for the rear end of the plate  22 . The free space  47  is composed of a first free space  47   a  located on the rear end (X dimension) and a second free space  47   b  located on the bottom of the long path of the white key  2  (Z dimension). 
         [0078]    The first free space  47   a  is an empty space for housing the gate remainder  37  on the plate  22  and is formed at a large empty space able to house the shape of the gate remainder  37  in a non-fixed, moveable state. 
         [0079]    The size of the gate remainder  37  unsuitable for operator processing may vary in such cases during normal processing. Without this empty space, in order to avoid damage during welding, it may be necessary to carefully process the gate. In order to avoid this problem, the first free space  47   a  can be generally a sufficiently large space to accommodate various sizes of gate remainder  37 . 
         [0080]    The second free space  47   b  is also an empty space for housing a gate remainder  37 , but the first free space  47   a  is formed to take in the side of the left side in the X dimension while the goal of the second free space  47   b  is to be able to house the lower section in the Z dimension while in a moveable, non-fixed state. 
         [0081]    During normal processing, a divided protuberance is easily formed as seen in the Z dimension of the gate remainder  37 . If there is no second free space  47   b , these protuberances will be damaged during welding. 
         [0082]    In this situation, by setting up the first free space  47   a  and the second free space  47   b , it is possible to plan an increase in the operating efficiency because of the possibility of removing the irrelevant gate procession operation once the gate has been formed on this part of the plate  22 . 
         [0083]    Thus, as explained above, the keyboard device  1 , traditionally using an adhesive, is capable of being securely fastened if the base  21  and the plate  22  are conjoined, because the base  21  and the plate  22  are welded together using ultrasonic waves. Therefore, it is possible to prevent the base  21  and the plate  22  from loosening after long term use even if, for example, operators firmly depress the keys. 
         [0084]    Also, the plate  22  has the protrusion area  32 , the protuberance  33 , and the fitting space  35 , while the base  21  has the hole  42 , the housing space  43 , and a pair of supporters  44 . Each of these is capable of preventing the base  21  and the plate  22  from being welded at a position other than their proper position because they set the location for the plate  22 . Therefore, it is possible to increase production efficiency. 
         [0085]    The present invention is not limited to the above examples, and it is possible to easily surmise possible alteration without departing from the aim of this invention. 
         [0086]    For example, in the above example, the protuberances  31   a - 31   f  being made up of a convex shape on a straight line, the convex shape could have curved lines, several convex shapes could be made, and straight lines, curved lines, and the scattered shapes could be combined. Also, protuberances  31   a - 31   f  may be formed on the base  21  (instead of the plate  22 ), while corresponding grooves and indentations may be provided on the plate  22  (instead of the base  21 ). Alternatively, each of the base  21  and plate  22  may include both protuberances and grooves or indentations that mate with corresponding indentations and grooves on the other of the base  21  and plate  22 . 
         [0087]    Also, the above examples explain the special characteristics of an exemplary white key  2 , but these are also applicable to a black key  3 . 
         [0088]    While particular embodiments of the present invention have been disclosed, it is to be understood that various different modifications and combinations are possible and are contemplated within the true spirit and scope of the appended claims. There is no intention, therefore, of limitations to the specific disclosure herein presented.