Exterior structure for keyboard instrument

Abstract

The external structure used for keyboard instruments can significantly improve the types of keyboard instruments that can be manufactured while reducing the cost of molds. The lower case includes a front-side lower case (LCf) and a rear-side lower case (LCr) disposed on the rear side of the front-side lower case (LCf) in a side-by-side manner. The upper case (UC) is placed above the lower case. The front lower case (LCf) is fixed to the upper case (UC), and the rear lower case (LCr) is fixed to the upper case (UC), so that the lower case is fastened to the upper case (UC) ).

Description

technical field [0001] The invention relates to an external structure of a keyboard musical instrument, which has a shell structure of a combination of multiple shells and is used to house keyboard components. Background technique [0002] Generally, as disclosed in Japanese Utility Model Registration Publication No. 2545353, an external structure of a keyboard musical instrument is known in which two upper casings of respective types are selectively combined with a single type of lower casing , so two shell structures can be formed. Generally, in such an external structure, the upper case and the lower case are made of resin and molded using a mold. A screw guide hole is formed in each upper case, and a clearance hole for screwing a screw is formed in the lower case in combination with the screw guide hole. In this way, the two housings are fastened to each other by screwing in screws from below. [0003] However, in this type of external structure, when the angle of the...

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Problems solved by technology

However, each screw forms an exposed portion by fitting only a part thereof along the shorter side of the elongated screw guide hole, so the fastening rigidity of the screw is lowered.

Moreover, it is difficult for the screw to go straight during screwing in, thereby reducing its fixing accuracy

Therefore, an elliptical protrusion combined with this elongated hole has to be formed in the mold, thus becoming more difficult to machine the mold than a circular shape forming the hole in section, resulting in an increase in the cost of the mold

[0005] Moreover, when one type of lower case is commonly used or shared with various types of keyboard instruments, even if a plurality of upper cases are provided, the depth and shape of each keyboard instrument in planar view depend on the lower case, and thus from From the standpoint of its design and mounting stability, especially, the depth of the upper case cannot be increased, otherwise it will be difficult to manufacture keyboard instruments that vary in size between types

[0006] For the reasons mentioned above, if the premise is to reduce the mold cost, there are great restrictions in the design of the upper case, and in practice, it is difficult to produce by sharing the lower case and replacing only the upper case based on the type of keyboard instrument Various types of keyboard instruments

Therefore, the fact is that the number of types of keyboard instruments that can be manufactured is limited

[0007] Also, in the above kind of external structure, the upper and lower casings are originally formed as separate parts, so that unless the parts where the two casings are assembled are carefully arranged, there is a fear that the rigidity of the entire casing structure will be lowered.

Also, if the shell structure is constructed by combining 3 or more separate parts, it is more likely that the overall shell structure will be less rigid

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