The present invention relates to a white key for a keyboard musical instrument in which the key body is formed of resin in a small thickness but is contrived to damp the click noise caused by a clash between the white key and the nail of the player.
Electronic keyboard musical instruments and the like keyboard musical instruments generally employ playing keys made of resin or plastics. A key made of resin is generally formed in a shape of a hollow box having a horizontal upper wall to be pressed by the finger of the player and vertical walls including a front wall, two side walls and a rear wall extending downward from the periphery of the upper wall to surround an open space therein. A plastic key can therefore be manufactured easily and inexpensively when compared with a traditional key (such as of a piano) which comprises a core bar made of wood and surface plates made of plastics or ivory adhered on the wooden core.
However, a plastic key of a hollow box shape has a drawback, in comparison with a wood-core key of a solid body, of generating harsh click noises caused by the clashes between the key top (horizontal upper wall) and the nail and resonating in the hollow box structure when the key is struck by the player's finger. In particular, a white key which has a larger surface area for key depression than a black key tends to generate louder click noises, much more does a white key having thinner plastic walls for the purpose of decreasing the weight and the manufacturing cost of the keyboard assembly.
A keyboard is a main input device for playing music on a keyboard musical instrument, and accordingly the keys constituting the keyboard are required to be of high quality and a high grade. But a harsh or ear-annoying clash noise between the key top and the nail would give an impression of a cheap musical instrument. Further, in the case of an electronic musical instrument on which the player is playing music using a headphone or an earphone, the musical tones can be heard only by the player and not by the persons near the player, and consequently only the clash noises would reach conspicuously to the ear of the persons present nearby.
Unfortunately, however, there has been known no technique of taking countermeasures against such nail clashing noises. The technique disclosed in an unexamined Japanese patent publication No. 2000-132168 is to utilize cushion materials disposed between the screw heads and the key bed when the keyboard assembly is fixed to the key bed in the electronic piano in order to absorb the vibration of the keyboard assembly generated by the key depression and to prevent the vibration from being propagated to the key bed. The technique is for suppressing the noises produced by the vibrations of the key bed at the times the keys are depressed, and does not work as a countermeasure against the clash noises between the key and the nail.
The technique disclosed in a registered Japanese patent publication No. 3758590 is to manufacture a key by forming the portion which serves as a swing fulcrum of the key by resin and forming the front body part by wood in order to increase the preciseness of the connecting portion to serve as the swing fulcrum as well as obtain the appearance and the rigidness of the wood material. As this technique utilizes wood material, the manufacturing cost will be almost the same as the conventional wooden key.
In view of the foregoing circumstances, therefore, it is a primary object of the present invention to obviate the above-mentioned drawback residing in the conventional plastic keys and to provide a white key made of resin material as a whole for keyboard musical instruments, in which the thickness of the key body is decreased for the purpose of decreasing the weight and the manufacturing cost of the key and yet the clash noise between the key top and the nail is suppressed from generating and resonating harshly to sound soft at the time the key is struck by a finger.
According to the present invention, the object is accomplished by providing a white key for a keyboard musical instrument comprising: a key body made of resin in the form of a hollow box shape having an upper wall to be pressed by an instrument player and vertical walls extending downward from the periphery of the upper wall, wherein the upper wall of the key includes a wide part and a narrow part, the narrow part providing a space to accommodate a black key to be interposed between two white keys, and wherein the upper wall has a thickness not exceeding 1.5 mm and the wide part has a projection extending from the upper wall downward.
The projection downwardly extending from the upper wall serves to change the vibration characteristics (the natural frequency and the mode of vibration) of the key body, and in particular the provision of the projection to the wide portion (having a large area) of the key wall will effectively influence the characteristics. Thus, the annoying harsh clash noises due to the striking nails will be suppressed and the tone quality of the sound generated by the key itself will be improved. Consequently, even though the thickness of the upper wall which would otherwise require to be thick to constitute the wall to be struck by the player's finger can be 1.5 mm or less, with the nail striking noises being suppressed to a tolerable degree. This will help in decreasing the weight and the manufacturing cost of the key and in improving the sound quality at the time of the key depression.
In an aspect of the present invention, the projection may be in the form of a rib. The rib serves to reinforce the struck wall in its longitudinal direction to provide a robust key exhibiting a minimal bend or twist.
In another aspect of the invention, the rib may be integrally formed with the key body extending in the longitudinal direction of the key body. As the key is manufactured by injecting plastic resin into a mold and the resin flows along the longitudinal direction in the mold, the longitudinally extending mold cavity will help smooth flow of the resin in the mold cavity, which will present a smooth surface of the product. On the contrary, if the rib is provided lying in the transverse direction, the flow of the resin in the mold cavity may be turbulent in the rib area and may degrade the smoothness of the surface of the product or may cause a flow mark to deteriorate the appearance of the key.
In still another aspect of the present invention, the rib may be provided to have a frequency band of a vibration mode due to a deformation of the upper wall when pressed by the user so that the frequency band is shifted toward the higher frequency side as compared with the case where the upper wall has no projection. In such a way, the frequency band of the mode of vibration of the upper wall of the key body which would make a conspicuous harsh noise at the nail strike on the wall which has a thickness of 1.5 mm or less will be shifted toward a higher frequency, which in turn suppress the strike noise from sounding harshly.
The frequency of the vibration mode of the upper wall may preferably lie in the range of 1 kHz-2 kHz. As the harsh annoying noise of the nail clash onto the key wall generally is due to the frequency components of the vibration mode lying in the range of 1 kHz-2 kHz, shifting the frequency components in that range toward higher frequency side will suppress such a harsh annoying noise. For the similar reason, the rib may preferably be formed to cause a decrease of an acceleration peak value of the vibration mode of the upper wall of the range between 1 kHz and 2 kHz. This will also suppress a harsh annoying noise.
In a further aspect of the present invention, the white key has a swing fulcrum at its rear end, and a plurality of white keys may preferably be connected with each other by a rear connecting member behind the swing fulcrums to form a unit of white keys. This structure will be advantageous in fixing the white keys to the keyboard assembly unit by unit. The white keys which have different shapes in association with the interposed black keys can thus be positioned easily in the exact arrangement by simply placing the unit on the keyboard frame, which will enormously simplify the assembling process. This will reduce the manufacturing cost in addition to the cost reduction by saving the resin material.
For a better understanding of the present invention, and to show how the same may be practiced and will work, reference will now be made, by way of example, to the accompanying drawings, in which:
a and 1b are plan views of a white key for a keyboard musical instrument according to an embodiment of the present invention,
The invention and its various embodiments can now be better understood by turning to the following detailed description of the preferred embodiments with reference to the accompanying drawings.
It should be expressly understood that the illustrated embodiments are presented just as practicable examples of the invention and that the invention as defined by the claims may be broader than the illustrated embodiments described below. In the drawing, like reference characters refer to like parts so that repetitive explanations may be omitted. The term “front” will be used herein to denote the area or part of a key which is near to the player of the keyboard musical instrument where the keyboard is assembled in the instrument, and the term “rear” to denote the area or part which is far from the player. The term “white key” will be used to denote a key which is assigned to a natural note as opposed to a black key which is assigned to a sharp (or flat) note. It should therefore be understood that the actual color of the white key may not necessarily be literally “white,” and may be of another color which can be differentiated from the black key in hue, chroma (saturation) or lightness. It is well known in the art that a traditional harpsichord has white keys in the color of “black” and black keys in the color of “white.”
A white key or keys of an embodiment of the present invention are shown in
As shown in
Under the wide part 11a of the upper wall 11 is formed a planar projection 20a in the form of a rib extending transversely from the side walls 14 and 15a. The planar projection 20a is formed integrally with the key body 10 by plastic molding to connect the side wall 14 and the front-part side wall 15a. The planar projection 20a influences or alters the vibration characteristics (the natural frequency of vibration and the mode of vibration) of the key body 10. More specifically, the planar projection 20a is designed and provided so that the frequency band of the mode of vibration due to the deformation of the upper wall 11 when struck by the finger is shifted toward the higher frequency side as compared with the case where the projection is not provided on to the upper wall 11 and so that the acceleration peak value of the vibration mode of the upper wall 11 is decreased. The planar projection 20a provided to the wide part 11a having a large area can effectively modify the vibration characteristics. As a result, the clicking harsh noise generated when the nail clashes or knocks on to the upper wall 11a will be suppressed, so that the tone quality of the sound generated by the key body 10 itself at the key strike will be improved. This effect of decreasing the nail clashing noises will make it possible to thin the walls of the key body 10, in particular the upper wall 11 which is most influenceable, for example, down to 1.0 through 1.5 mm, still keeping the nail clashing harsh noises suppressed. The front wall 12, the rear wall 13 and the side walls 14, 15 can be thinned to the same degree or more as long as the necessary structural strength can be obtained.
As with the case of the preceding embodiment, this embodiment also will suppress the generation of clicking harsh noises caused by the nail clashes, improving the tone quality of the sound generated by the key body 10 itself at the key strike. Also with this embodiment, the effect of decreasing the nail clashing noises will make it possible to thin the walls of the key body 10. This embodiment will be particularly advantageous in plastic molding, as the planar projection 20b is provided in the form of a rib extending in the longitudinal direction of the key body 10. More specifically, in the plastic molding process of the key, the resin flows in the mold mainly along the longitudinal direction of the key body 10, and the resin for forming the projection 20b will accordingly flows through the cavity for the rib, while the cavity lies in the longitudinal direction, which therefore causes a smooth flow of the resin in the cavity. This will provide a smooth surface of the molded product, and accordingly prevent rough surfaces and flow marks due to the turbulence of the resin flow in the mold.
As with the case of the preceding embodiment, this embodiment also will suppress the generation of clicking harsh noises caused by the nail bumps on to the key top surface, improving the tone quality of the sound generated by the key body 10 itself at the key strike. Also with this embodiment, the effect of decreasing the nail bumping noises will make it possible to thin the walls of the key body 10. This embodiment will be particularly advantageous in plastic molding, as the projections 20c are provided in the form of separate columns protruding perpendicularly to the undersurface of the wide part 11a of the upper wall 11. More specifically, in the plastic molding process of the key, the resin flows will not be obstructed so much in the mold, which will accordingly provide a smooth surface of the molded product.
An explanation will now be made about the evaluation of vibration characteristics of a white key according to the present invention. The evaluation was conducted in the following way.
The white keys used for measurement had external dimensions of 140 mm in total length and 21.4 mm in width, in common. The other main dimensions are different from one model to another as shown in Table 1, wherein “t1” denotes the side wall height at the actuator end and “t2” denotes the side wall height at the front end as depicted in
As preparation for the measurements, the input characteristics of the key strikes by the impact hammer H were measured.
The result of the evaluation is as follows.
Each of the white key N having thick walls and the white keys A, B and C was struck by a finger, and the click noise generated when the nail clashed or knocked on to the key was evaluated auditorily, and the result was that the nail clashing noises sounded piercingly sharp in the cases of the white keys A, B and C as compared with the key N having walls of an ordinary thickness.
Each of the white key N having thick walls and the white keys A, B and C was struck by an impact hammer H, and the frequency response characteristic of each key is measured. The results of the measurements are shown in the graphs in the drawings, in which
These graphs tell that the levels of the response curves for the keys A, B and C are noticeably higher than that for the key N in the frequency range between 1 kHz and 2 kHz. As the hammer strike exhibits a frequency characteristic (frequency components) as shown in
Taking the key A as an example model of a key having thin walls, a simulation model is created by a computer based on the dimensions, the shape and the material characteristics (Young's modulus, Poisson's ratio, density, etc.).
Table 2 tells that the resonance peak frequencies of 244 Hz through 3110 Hz from the analysis are close to the resonance peak frequencies of 280 Hz through 4000 Hz from the measurements, respectively, in other words, the ratios of the “measured peak frequency/analyzed peak frequency” are close to “1” for each corresponding resonance peak. This means that the data obtained through the analysis of the simulation model will have a high degree of reliability in representing the actual model.
The present invention should not be interpreted to be limited to the embodiments described herein above, but can be realized with various modifications. For example, the shape of the white key may be variously designed other than the above described embodiments. While a plurality of white keys may preferably be connected at their rear end to make an integral unit, the individual white keys may be separately designed and manufactured. The projection may be in the form of a rib or a column, and the number of projections may be singular or plural according to the intended characteristic. The description made herein above with respect to several embodiments will be applicable to other types of embodiments.
While several preferred embodiments have been described and illustrated in detail herein above with reference to the drawings, it should be understood that the illustrated embodiments are just for preferable examples and that the present invention can be practiced with various modifications without departing from the spirit of the present invention.
This application is based on, and claims priority to, Japanese Patent Application N. 2007-275338, filed on Oct. 23, 2007. The disclosure of the priority application, in its entirety, including the drawings, claims, and the specification thereof, is incorporated herein by reference.
Number | Date | Country | Kind |
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2007-275338 | Oct 2007 | JP | national |
Number | Name | Date | Kind |
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3979990 | Hinago | Sep 1976 | A |
6051768 | Masubuchi | Apr 2000 | A |
20060219085 | Kamijima et al. | Oct 2006 | A1 |
20080066608 | Osuga | Mar 2008 | A1 |
Number | Date | Country |
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2000-132168 | May 2000 | JP |
2003-271127 | Sep 2003 | JP |
Number | Date | Country | |
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20090100987 A1 | Apr 2009 | US |