JPH0446311Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a key device for an electronic keyboard instrument, mainly an electronic piano.

(Prior Art) As a conventional key device for an electronic keyboard instrument, as shown in Figure 5, there is a known key device in which a weight b is attached to the upper part of the rear end of the fulcrum of key a to obtain a return force for key a. ing.

This device has a key touch load similar to that of a piano, compared to a device that uses a spring to obtain the key return force.
Keystroke characteristics are obtained.

(Problems to be solved by the invention) The above-mentioned conventional key device, as shown in Figure 6,
There is no hysteresis characteristic in the line load and return load of a key touch, so when playing by slowly pressing down on a key, if you weaken the force of your fingers even a little when pressing down on a key, the key will rise. The keys tend to sway, making it difficult to create subtle expressions like piano touches. In addition, since the return force of the key is obtained only from the weight, the weight of the entire keyboard increases.If the weight of the weight is reduced, the length of the rear end of the key fulcrum becomes longer to balance the initial load of the key. As a result, the keyboard becomes larger.

The present invention aims to solve these problems of conventional key devices.

(Means for Solving the Problems) In order to achieve the above object, the present invention fits the groove of the rotating shaft into the locking part of the chassis, and the recessed part of the rotor fits into the rotating shaft. to make the rotor freely rotatable, and bring one end of the rotor into contact with the rear end of the fulcrum of the key,
A key return spring is stretched between the other end of the rotary shaft with the center of rotation sandwiched therebetween and the chassis, and the spring force of the key return spring presses the rotary shaft against the chassis, and at the same time, the rotor is attached to the rotary shaft. It is characterized by pressure contact.

(Function) When the key is pushed in with a finger, a frictional force in the same direction as the spring force acts between the rear end of the fulcrum of the key, one end of the rotor, the rotor's recessed wall surface, and the rotating shaft.
As shown by X in the figure, the touch load on the key becomes heavier.

Conversely, when the key is returned to its original position, the frictional force acts in the opposite direction to the spring force, so the touch load on the key becomes lighter, as shown by Y in FIG.

Since the return force of the key is provided by the spring, the length of the rear end of the fulcrum of the key can be shortened without increasing the weight of the keyboard.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

1 and 2, reference numeral 1 denotes a chassis fixed to a shelf board 2, on which a rotating shaft 3 is locked, and a rotor 5 that can be rotated by fitting a recess 4 into the rotating shaft 3. A key return coil spring 8 is stretched between the chassis 1 and the other end of the rotor 5 with the rotating shaft 3 interposed therebetween, with one end in contact with the upper surface of the fulcrum rear end 7 of the key 6.

To explain the above structure in more detail, the chassis 1 is composed of a dogleg-shaped upright part 9, a spring receiving part 10, and a fixed part 11, as shown in FIG. , a plurality of windows 12 into which a plurality of rotors 5 corresponding to a plurality of keys 6 are inserted are formed. The rotating shaft 3 has a circumferential surface mostly shaped like a circular button, and has a groove 13 for engaging the chassis 1. The rotor 5 has a recess 4 in the middle part into which the rotation shaft 3 is fitted, one end of which is formed into an arc surface to smoothly contact the upper surface of the rear end 7 of the fulcrum of the key 6. At the other end of the shaft 3, there is a groove 14 into which one end of the spring 8 is fitted and locked.
is formed.

In FIG. 2, reference numeral 15 denotes a vibration damping material made of, for example, sponge, which extends continuously over a plurality of keys 6 bonded to the chassis 1 in order to prevent the vibration of the spring 8, and 16 denotes a groove in the rotation shaft 3. A locking portion 17 that fits into the rotor 13 is, for example, Teflon tape pasted so that the rotor 5 can slide smoothly.

The key 6, rotor 5, and coil spring 8 reduce the increase in key touch load with respect to the key stroke, so that fingers do not feel pressured when playing.
In order to make it easier to play, the following relationships are selected.

In FIG. 3, A is the fulcrum of the key 6, B is the contact point between the rotor 5 and the key 6, C is the center of rotation of the rotor 5, D is the point of action of the coil spring 8 on the rotor 5, and E is the point on the chassis 1. This is the locking point of the coil spring 8.

The condition that the key touch load does not increase is F ₁ l ₁ ≧F ₁ ′l ₁ ′ …(1) However, F ₁ l ₁ and F ₁ ′l ₁ ′ are the key rotation moments before and after the key stroke. Strictly speaking, F ₁ l ₁ ≒F ₁ ′l ₁ ′, but in reality,
There is a slight increase in the load due to the keyboard switch (not shown), so taking this into consideration, F ₁ l ₁ > F ₁ ′
l ₁ ′ is also included.

Before the stroke of the key 6, from the balance of the moment around the rotation center of the rotor 5, F ₂ l ₂ = F ₃ l ₃ ...(2) Here, F ₃ = F ₄ cos θ ₃ (F ₄ : Coil Spring force of spring 8) Since the vertical force of the rotor 5 and the vertical force of the key 6 are equal, F ₁ /cos θ ₁ =F ₂ /cos θ ₂ (3) holds true. From formula (3), F ₁ = cos θ ₁ / cos θ ₂ F ₂ = cos θ ₁ / cos θ ₂・l ₃ /l ₂・F ₄・cos θ ₃ …(4) Since it holds even after the stroke, F ₁ ′=cos θ ₁ ′/cos θ ₂ ′・l ₃ ′/l ₂ ′・F ₄ ′ ・cos θ ₃ ′ …(4)′ (4) and (4 )′ expressions, we find that l ₂ ≒l ₂ ′, l ₃ ≒l ₃ ′, F ₄ ′＞F ₄ , and in order for l ₁ ≒l ₁ ′ to hold F ₁ ≒F ₁ ′, cos θ ₁ /cos θ ₂・F ₄・cos θ ₃ =cos θ ₁ ′/cos θ ₂ ′・F ₄ ′・cos θ ₃ ′…(5) It is necessary that the relationship holds true.

That is, _{the key} fulcrum A, _the contact point B _{between the} key _{and the rotor} , By arranging the center of rotation C, the point of action D of the coil spring 8, and the locking point E of the coil spring 8, the increase in key touch load is reduced. Fourth
The figure is a key touch load per key stroke characteristic diagram of an embodiment of the present invention.

(Effects of the invention) As is clear from the above explanation, according to the invention, since the increase in key touch load is small with respect to the key stroke, the fingers do not feel pressured when playing, and the keys are pressed easily. The key touch load when releasing the key,
Since hysteresis characteristics similar to those of a piano can be obtained, it is possible to express delicate touches similar to those of a piano, and the keyboard can also be made smaller compared to conventional models. This has the advantage that the rotor can be easily and rotatably attached to the chassis using the spring force of the key return spring with a simple structure.

[Brief explanation of the drawing]

FIG. 1 is a side view of one embodiment of the present invention, FIG. 2 is an exploded perspective view of its main parts, FIG. 3 is an explanatory diagram for obtaining conditions for reducing the increase in key touch load, and FIG. FIG. 5 is a side view of an example of a conventional key device, and FIG. 6 is a diagram showing the key touch load and one key stroke characteristic of an embodiment of the present invention. 1... Chassis, 3... Rotating shaft, 4... Recessed part,
5... Rotor, 6... Key, 7... Rear end of fulcrum, 8...
... Coil spring for key return, 9 ... Standing part, 10 ...
Spring receiving part, 13... groove, 16... locking part.

Claims (1)

[Scope of utility model registration request] The groove of the rotating shaft is fitted into the locking part of the chassis, the recessed part of the rotor is fitted with the rotating shaft to make the rotor freely rotatable, and one end of the rotor is brought into contact with the rear end of the fulcrum of the key. , a key return spring is stretched between the other end of the rotary shaft with the rotation center sandwiched therebetween and the chassis, and the spring force of the key return spring presses the rotary shaft against the chassis, and at the same time the rotor is pressed against the rotary shaft. A key device for an electronic keyboard instrument, characterized in that the key device is pressed into contact with the key device.