JPH0448600Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a key switch used in electronic keyboard instruments such as electronic organs and portable electronic keyboard instruments.

[Conventional technology]

In conventional electronic keyboard instruments, the keyboard frame and the key switches operated by the keys attached to the keyboard frame are separate parts.

A miniaturized version of the key switch, for example, as seen in Japanese Utility Model Application Publication No. 54-112124, has a circuit board on which fixed contacts corresponding to each key are printed, and a circuit board from which the fixed contacts are connected to the circuit board. Some devices include movable conductive rubber contacts spaced apart and a holder for positioning and holding these contacts on the keyboard frame.

[Problem that the invention attempts to solve]

However, even such a conventional miniaturized key switch still requires a large number of parts, such as a printed circuit board, a movable contact, and a member to hold it apart from a fixed contact, and requires a large space. There was also a problem with the dust resistance.

In addition, since the switch obtains on/off signals by connecting and separating a fixed contact and a movable contact, by using conductive rubber for the movable contact, problems such as chattering and contact wear and deterioration can be greatly reduced. Although these problems can be improved, there are problems that cannot be completely resolved.

Therefore, piezoelectric keyboards that use piezoelectric films instead of movable contacts and eliminate the need for holding members, as seen in, for example, Japanese Utility Model Application Publications No. 57-95715 and No. 58-173127, etc., have been developed as electronic keyboards. It can be considered to be used as a key switch for musical instruments.

However, in such conventional piezoelectric keyboards, the keys or hammers are always separated from the piezoelectric film, and when the key is pressed down a predetermined stroke, the piezoelectric film is struck and made conductive. Even if you use it as a key switch, it is not possible to continuously detect the pressure force used to operate the key from the start to the end of the key operation, so touch control or after control depending on the strength of the key press is not possible. In order to do this, it is necessary to separately provide a sensor for this purpose.

This invention aims to solve all of these problems by making it possible to form the key switch integrally in a thin layer on the keyboard frame, solving the problems of space and dustproofness, and making it possible to eliminate movable contacts. To maintain the desired performance over a long period of time by eliminating this, and to continuously detect the pressing force for operating each key from the start to the end of the operation.

[Means of trying to solve the problem]

The key switch for electronic keyboard instruments based on this invention is
In order to achieve the above purpose, a pair of contact patterns spaced close to each other is formed using a conductive material on an insulating layer closely formed on the keyboard frame, and an insulator on which the pair of contact patterns of the keyboard frame is formed is formed. A piezoelectric film is directly attached to the layer, and the actuator attached to each key attached to the keyboard frame is in contact with the piezoelectric film when the key is not pressed, and elastically deforms as the key is pressed to change its stroke. At the same time, the elastic force of the piezoelectric film is used to press a portion of the piezoelectric film on the pair of contact patterns corresponding to the pressed key.

[Effect]

In the key switch configured as described above, the actuator of each key, which is in contact with the piezoelectric film when the key is not pressed, elastically deforms as the key is pressed to absorb the stroke, and at the same time, the actuator of the key contacts the piezoelectric film due to its elastic force. Since the part on the pair of contact patterns corresponding to the pressed key is pressed, only the pressed part of the piezoelectric film generates a voltage or becomes a conductor in accordance with the pressing force.

Therefore, the voltage or degree of conductivity between the corresponding pair of contact patterns changes in accordance with the key operation pressing force from the start to the end of the key operation, and this can be detected.

〔Example〕

An embodiment of this invention will be described below with reference to the accompanying drawings.

FIG. 1 is a perspective view showing the structure of the key switch according to this invention with the piezoelectric film partially peeled off.
FIG. 2 shows its cross section with the key and its actuator.

Reference numeral 1 designates a keyboard frame of an electronic keyboard instrument, on the top of which an insulating layer 2 of epoxy resin or the like is formed in the form of a band by direct screen printing or hot stamping.

On this insulating layer 2, a lead wire pattern 5 is provided with a pair of contact patterns 3 and a component connecting portion 4, which are closely spaced from each other and correspond to each key, as shown in the figure.
A circuit pattern such as the following is printed and formed using a conductive material.

The conductive material used is, for example, a mixture of copper paste and copper fly (copper powder) mixed with a binder and a volatile solvent.

Note that small components such as a chip resistor 6 are attached to the component connection portion 4 using a conductive adhesive as necessary.

Then, a piezoelectric film 7 wider than the insulating layer 2 is directly attached onto the insulating layer 2 on which the pair of contact patterns 3 and the like are formed on the keyboard frame 1, and the piezoelectric film 7, which is wider than the insulating layer 2, is covered and sealed. are doing.

The piezoelectric film 7 may include, for example, a piezoelectric polymer (piezoplastic) such as polyvinylidene fluoride that generates a voltage in response to applied pressure;
Or a pressure-sensitive conductive polymer (pressure-sensitive resistor) that changes its resistivity depending on the applied pressure and becomes a good conductor.
Using film by et al.

The manufacturing process of the key switch 10 having such a structure is performed in the following order.

(1) Form the insulating layer 2 in a band shape on the keyboard frame 1 by screen printing or the like.

(2) On the insulator layer 2, a circuit pattern such as a pair of contact patterns 3 corresponding to each key is printed and formed using a conductive material.

(3) If necessary, attach small parts such as the chip resistor 6 on the circuit pattern (this may be omitted).

(4) Paste the piezoelectric film 7 on the keyboard frame 1 so as to cover the insulator layer 2.

This key switch 10 is formed along the arrangement direction of a large number of keys 11 attached to the keyboard frame 1 as shown in FIG. As shown in FIG. 2, the key 11 is brought into light contact with the piezoelectric film 7 in a horizontal, non-depressed state.

When each key is pressed, the actuator 12 of that key is elastically deformed to absorb the stroke, and at the same time, due to the elastic force, the tip convex portion 12a
is arranged so that a portion of the voltage film 7 on a pair of contact patterns 3 corresponding to each key 11 is pressed.

According to this embodiment, when one of the keys 11 is pressed, the actuator 12 of that key is elastically deformed, and the portion of the piezoelectric film 7 of the key switch 10 on the pair of contact patterns 3 corresponding to that key is Since the key is pressed by elastic force, a pressure F is applied to the key at the same time as shown in FIG. 4a.

As a result, if the piezoelectric film 7 is a piezoelectric polymer film, a voltage V is generated at that portion as shown in FIG.

By inputting this voltage to the electronic circuit of the main body (not shown) through the pair of contact patterns 3 and lead wire patterns 5, etc., key operation information corresponding to the strength or change of the operation pressing force is continuously transmitted from the start to the end of the key press. can be detected.

When a pressure-sensitive conductive polymer film is used as the piezoelectric film 7, the resistivity of the part pressed by the actuator 12 by pressing the key decreases in accordance with the pressing force and becomes a conductor. Therefore, since the degree of conductivity between the pair of contact patterns changes, it is possible to continuously detect key operation information corresponding to the strength or change of the operation pressing force from the start to the end of the key press.

Using this key operation information, it is possible to perform touch control and after control according to the opening/closing of music and the key operation force.

[Effects of the invention] The key switch of the electronic keyboard instrument according to this invention is
As mentioned above, since the insulating layer closely adhered to the keyboard frame, the pair of contact patterns corresponding to each key made of conductive material, and the piezoelectric film are formed in a layered manner, it is possible to hold the key switch on the keyboard frame. Not only does it eliminate the need for a holder, but it also eliminates the need for a printed circuit board for forming the fixed contacts and a spacer for holding the movable contacts apart, allowing it to be formed extremely thin and in a small space.

Furthermore, since the contact portion is covered with a piezoelectric film attached to the key frame and is in a sealed state, it is completely dust-proof, and there is no risk of malfunction due to dirt on the contact.

Further, since it does not have a movable contact, no chattering occurs, and no wear or deterioration of the contact occurs, so that the desired performance can be maintained over a long period of time.

Further, key operation information corresponding to the operation pressing force for each key can be continuously obtained from the start to the end of the operation of the key.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a key switch, which is an embodiment of this invention, with a part of the piezoelectric film peeled off, Fig. 2 is a cross-sectional view showing the cross section together with the key and its actuator, and Fig. 3 is a perspective view showing the key switch as an embodiment of the invention. A perspective view showing a state in which a key is attached to the keyboard frame that also forms the key switch, and FIG. FIG. 3 is a diagram showing an example of voltages. 1...Keyboard frame, 2...Insulator layer, 3...
Pair of contact patterns, 7...Piezoelectric film, 10...
...key switch, 11...key, 12...actuator.

Claims (1)

[Scope of utility model registration request] A pair of contact patterns spaced close to each other is formed using a conductive material on an insulator layer closely formed on a keyboard frame, and a piezoelectric film is directly applied to the insulator layer on which the pair of contact patterns of the keyboard frame are formed. The actuator attached to each key attached to the keyboard frame is in contact with the piezoelectric film when the key is not pressed, and elastically deforms as the key is pressed to absorb the stroke and at the same time A key switch for an electronic keyboard instrument, characterized in that a portion of the piezoelectric film on the pair of contact patterns corresponding to a pressed key is pressed by force.