JPH0935570A - Switch device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a device into a thin type and to increase on/off output voltage without receiving an influence of external magnetism, by providing a dome- shaped elastic member rapidly elastically deformed when a key top press operating force is increased to a prescribed value or more. SOLUTION: After a dome-shaped elastic member 16 is inserted to a recessed part 18 of an under cover 17, a connector part of a piezoelectric sheet 6 is positioned in a connector receiving part of the cover 17. A locating hole is fitted to a protrusion, and the sheet 6 is mounted in an upper surface of the under cover 17, to insert a key top 4 to an opening part 2 of a body case 1. Next a protrusive part protruded to a reverse surface of the case 1 is fitted to a step difference in a peripheral wall of the cover 17, to be built integrally in the cover 17 by a securing means. A large pressure is generated in the sheet 6 by cooperative action of the top 4 and the member 16, and when press operating force of the top 4 is increased to a shape holding limit or more of the member 16, the member 16 is rapidly elastically deformed, to be reset. In this way, in the sheet 6, large pulse voltage can be output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch device using a piezoelectric element.

[0002]

2. Description of the Related Art FIG. 10 is a sectional view showing a switch device disclosed in Japanese Patent Application Laid-Open No. 58-80229. In FIG. 10, 40 is a case, 41 is an internal space of the case 40, and 42 is an internal space. Hall ICs arranged at one end side of the space 40, 43 Hall ICs arranged at the other end side of the internal space 40, 44 is a lever, the lever 44 is rotatably mounted in the middle portion, the upper end is The case 40 is projected to the outside, the lower end is inserted into the internal space 41, and the permanent magnet 45 is fixed to the lower end.

The terminals 42a are connected to the Hall ICs 42 and 43,
When the operating power is supplied from 43a, the lever 4
4 is tilted to the state shown in FIG. 8, the permanent magnet 45 approaches one Hall IC 42, so that the Hall IC 42
42 generates a Hall voltage in a direction orthogonal to the direction in which the operating current flows and a direction of the magnetic field of the permanent magnet 45, and is turned on, while the Hall IC 43 is distant from the permanent magnet 45. Is almost zero and is off.

[0004]

However, since the above-mentioned conventional switching device uses magnetism, it is affected by external magnetism and lacks reliability. Hall IC and permanent magnet 45 to be in a state
It is necessary to increase the distance between and to prevent the generation of Hall voltage, which leads to an increase in the size of the device.

Further, there are many additional parts such as holding positions of the Hall ICs 42 and 43 and the tilt stop position of the lever 44, which is economically disadvantageous when the switch is a collective unit.

Therefore, the present invention is intended to provide an economically advantageous switch device which can be thinned and has a large on / off output voltage without being affected by external magnetism.

[0007]

According to a first aspect of the present invention, there is provided a key top mounted so that a switch case can be pressed.
A piezoelectric sheet that is laid inside the switch case under the key top and that generates a pulse voltage due to the piezoelectric effect,
The recess formed in the switch case below the piezoelectric sheet and the elasticity that is housed in the recess and resists the pressing operation of the key top are applied to the piezoelectric sheet, and rapidly when the pressing operation force of the key top exceeds a predetermined value. And a dome-shaped elastic member that elastically deforms.

According to the structure of claim 1, when the key top tries to push down the piezoelectric sheet by the pressing operation, the lower surface of the piezoelectric sheet is held by the dome-shaped elastic member, and the key top and the elastic member are While the piezoelectric sheet generates a large amount of piezoelectric force due to the joint operation of, the pressing force of the key top exceeds the shape holding limit of the elastic member, causing the elastic member to elastically deform and return (snap action). Then, a certain amount of movement and a large piezoelectric force are generated in the piezoelectric sheet, and the piezoelectric sheet outputs a large pulse voltage.

A second aspect of the present invention is characterized in that the elastic member according to the first aspect is formed in a dome shape.

According to the second aspect of the present invention, since the elastic member has a dome shape in which the elastic deformation start point is stable, the pulse voltage becomes constant and the quality and reliability are improved.

According to a third aspect of the present invention, the upper electrode and the lower electrode for extracting the pulse voltage of the piezoelectric sheet according to the first and second aspects are formed in a circular shape so that the electrode area and the operating area coincide with each other. It is characterized in that the connected wiring and the wiring connected to the lower electrode are arranged so as not to face each other vertically.

According to the third aspect of the present invention, the upper electrode and the lower electrode are formed in a circular shape so that the electrode area and the operating area coincide with each other, and the wiring of the upper electrode and the wiring of the lower electrode are vertically opposed to each other. By arranging in a state where it is not, the drop of the pulse voltage due to the behavior like a parallel capacitor is prevented, and the quality and reliability are improved.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In FIGS. 1 to 5, reference numeral 1 denotes a body case, which has a plurality of openings 2 penetrating vertically and a stepped shape larger than the openings 2 on the entire peripheral edge of the lower part of the openings 2. And a stopper hole 3 formed therein.

Reference numeral 4 denotes a plurality of key tops, which are provided with stoppers 5 protruding laterally from the entire peripheral edge of the lower part.

Reference numeral 6 indicates a piezoelectric sheet made of a polymer compound such as polyvinylidene fluoride, which has a function of converting mechanical energy into electric energy such that electricity is generated by receiving impact or vibration, and It has a function of converting mechanical energy into electric energy, such as expanding and contracting by receiving a signal, or generating a vibration of a surface by receiving an electric signal in a state of being curved and fixed at both ends, A plurality of circularly formed upper electrodes 7 and an upper electrode terminal 9 in which two pairs of the upper electrodes 7 are connected by wiring 8 are laid on the upper surface of this, and the lower surface thereof is indicated by a dotted line in FIG. As shown, a plurality of lower electrodes 10 formed under the upper electrode 7 and two lower electrodes 10
The lower electrode terminal 12 connected by the wiring 11 is laid as a set.

In the case of this embodiment, the connector portion 13 in which the upper electrode terminal 9 and the lower electrode terminal 12 are arranged side by side
Has a notch 14 between the upper electrode terminal 9 and the lower electrode terminal 12, and the portion on the upper electrode terminal 9 side is folded in two on the lower surface side and overlapped with each other.
The part on the second side is folded back and overlapped with the upper surface.

A plurality of locate holes 15 are formed around the upper electrode 7 of the piezoelectric sheet 6.

Reference numeral 16 denotes an elastic member formed in a plurality of domes (hemispherical shapes), the periphery of which is bent inward with the inclination angle made clear at the inflection point.

Reference numeral 17 denotes an undercover which constitutes a switch case together with the body case 1. This undercover has a circular recess 18 formed on the upper surface for individually accommodating a plurality of elastic members 16, and a bottom surface of the recess 18. A circular hole 1 formed to secure a space when the elastic member 16 elastically deforms.
9, a protrusion 20 formed around the recess 18 on the upper surface to be inserted into the locate hole 15 of the piezoelectric sheet 6, a peripheral wall 21 protruding from the entire peripheral edge of the upper surface, and an upper edge of the peripheral wall 21. It is provided with a step 22 and a connector accommodating portion 23 formed on the peripheral wall 21 and a part of the upper surface.

In this embodiment, after inserting the dome-shaped elastic member 16 into the concave portion 18 of the under cover 17, the connector portion 13 of the piezoelectric sheet 6 is positioned in the connector accommodating portion 23 of the under cover 17 and the locate hole 15 is formed.
Is fitted to the protrusion 20, the piezoelectric sheet 6 is mounted on the upper surface of the under cover 17, the key top 4 is inserted into the opening 2 of the body case 1, and the outside of the figure projected on the back surface of the body case 1 is inserted. The convex portion is a step 2 on the peripheral wall 21 of the undercover 17.
The switch device is assembled in the form shown in FIG. 5 by fitting it into the undercover 17 and fitting it to the undercover 17 by a fixing means (not shown).

In this assembled switch device, as shown in FIG. 1, the upper and lower surfaces of the piezoelectric sheet 6 are covered with protective insulating sheets 24 and 25.

The key top 4 inserted into the stopper hole 3 of the body case 1 is prevented from coming off by the stopper 5 coming into contact with the connecting step portion 26 between the stopper hole 3 of the body case 1 and the opening 2, and at the same time, the lower surface thereof. The piezoelectric sheet 6 is provided with a hemispherical projection 27 that is in contact with the upper surface of the upper electrode 7 of the piezoelectric sheet 6 through the protective insulating sheet 24.

The lower surface of the lower electrode 10 of the piezoelectric sheet 6 at the substantially central portion is in contact with the top of the dome-shaped elastic member 16 via the protective insulating sheet 25.

Therefore, according to the structure of this embodiment, when the key top 4 is pressed with a finger in the state shown in FIG. 1, the protrusion 27 tends to push down substantially the central portion of the upper electrode 7 of the piezoelectric sheet 6. But in the initial state,
Since the substantially central portion of the lower electrode 10 of the piezoelectric sheet 6 is held by the top of the dome-shaped elastic member 16, the protrusion 27
A large stress is generated in the piezoelectric sheet 6 between the upper electrode 7 and the lower electrode 10 by the joint operation of the elastic member 16 and the elastic member 16.

Subsequently, when the key top 4 is strongly pressed to push it down, a pressure corresponding to the pressing operation force is generated in the piezoelectric sheet 6, and the pressing force is stronger than the elastic force for holding the shape of the elastic member. When the elastic member 16 becomes larger, the peripheral edge of the dome-shaped elastic member 16 expands, and when the limit is reached, the elastic member 16 undergoes elastic deformation (snap-like) rapidly, and as shown in FIG. Becomes smaller, and the bent peripheral edge of the elastic member 16 has a circular hole 1
It is supported around the bottom surface of the recess 18 around 9 and the top of the elastic member 16 enters the circular hole 19.

A rapid elastic deformation operation of the elastic member 16,
That is, a certain amount of movement and a large pressure are applied to the piezoelectric sheet 6 by the snap action.

Also, when the pressing operation force is released from the key top 4, the elastic member 16 is rapidly (snapped) restored from the state shown in FIG. 2 to the state shown in FIG. A quantity and a large pressure are applied to the piezoelectric sheet 6.

The pressure applied to the piezoelectric sheet 6 and the voltage characteristic generated by the pressure sheet 6 when the key top 4 is pressed and released are in the relationship shown in FIG.

In FIG. 6, by pressing the key top 4 and releasing the key top 4, signals of two different poles, that is,
It can be seen that positive and negative pulse voltages are output due to the piezoelectric effect of the piezoelectric sheet 6.

Therefore, a switching operation is possible in which the switch is turned on by the pulse voltage generated when the key top 4 is pressed and the switch is turned off by the pulse voltage when the key is released.

In addition, since the piezoelectric material behaves like a parallel capacitor and lowers the pulse voltage when an electrode is present on the surface other than the operating surface, in this embodiment, as shown in FIG.
As shown in FIG. 5, the upper electrode 7 and the lower electrode 10 are formed in a circular pattern so that the electrode areas are matched with the operating area, while the wiring 8 on the upper electrode 7 side and the wiring 11 on the lower electrode 10 side are formed.
Are arranged on the upper and lower surfaces of the piezoelectric sheet 6 so as not to face each other.

FIG. 7 shows an experimental result comparing the magnitude of the pulse voltage between the above-mentioned embodiment and the comparative example. The comparative example shows the same protective insulating sheet as the embodiment on the upper surface of the base member 31 having the movable piece 30. The piezoelectric sheet 6 having 24 and 25 is mounted, and the protrusion 27 of the key top 4 is brought into contact with the protective insulating sheet 24 of the piezoelectric sheet 6 above the movable piece 30, and the pressing operation and release of the key top 4 are performed. This is a measurement of the pulse voltage generated in the piezoelectric sheet 6 when the above step is repeated several times.

Considering the voltage waveform which is the measurement result in FIG. 7, the pulse voltage of the embodiment is about 2.7 to 3.2 times the proportionality, and the keytop 4 is proportional.
Although the size is different between when the key is pressed and when released, in the embodiment, it is understood that the size is substantially the same when the key top 4 is pressed and released.

The elastic member 16 can be formed of metal or resin.

When the elastic member 16 is formed of resin, the under cover 1 is formed if the snap action is established.
It can be molded integrally with 7 as a snap piece.

For example, as shown in FIGS. 8 to 9, the recess 1 is formed on one side of the recess 18 of the under cover 17 from the bottom side.
8, the snap piece 16A is integrally formed to be obliquely upward and outwardly longer than the width of the recess 18, while the jaw portion is provided at the side edge of the opening edge of the recess 18 opposite to the side on which the snap piece 16A is extended. 18a is projected, and the snap piece 16A is elastically deformed into a bow shape so that the free end of the snap piece 16A is jaw 18a as shown in FIG.
The elastic member 16 that performs snap action can be configured by being attached to the.

[0038]

As described above, according to the present invention, the following effects can be obtained.

According to the first aspect, a large pressure is generated in the piezoelectric sheet by the joint operation of the key top and the elastic member, and the pressing operation force of the key top exceeds the shape holding limit of the elastic member. Since the member suddenly elastically deforms and returns (snap action), the piezoelectric sheet can output a large pulse voltage.

Since the pulse voltage is generated by the piezoelectric effect, it is not affected by external magnetism.

Further, the thickness of the components such as the switch case, the piezoelectric sheet, the elastic member, and the under cover can be reduced, or the height can be reduced to make the device thinner.

Further, since the switch case, the piezoelectric sheet, the elastic member, the under cover and the like have a simple structure in which the constituent elements are vertically stacked, it is economically advantageous even when the switch is a collective unit.

According to the second aspect, since the elastic member is formed in the dome shape, the elastic deformation of the elastic member is stabilized at the start point and the pulse voltage becomes constant, so that the quality and reliability are improved. be able to.

According to the third aspect, the upper electrode and the lower electrode are formed in a circular shape so that the electrode area and the operating area coincide with each other, and the wiring of the upper electrode and the wiring of the lower electrode do not face each other vertically. Since it is arranged, it is possible to prevent the drop of the pulse voltage due to the behavior like a parallel capacitor, and improve the quality and reliability.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a pressing operation state of the same embodiment.

FIG. 3 is an exemplary exploded perspective view of the embodiment;

FIG. 4 is a plan view showing the piezoelectric sheet of the same embodiment.

FIG. 5 is a perspective view showing the appearance of the same embodiment.

FIG. 6 is a characteristic diagram showing the relationship between pressure and pulse voltage in the same embodiment.

FIG. 7 is a diagram showing the same embodiment and contrast.

FIG. 8 is a cross-sectional view showing another example of forming elastic members.

9 is a sectional view showing an assembled state of the elastic member of FIG.

FIG. 10 is a cross-sectional view showing a conventional switch device.

[Explanation of symbols]

 1 Body Case (Switch Case) 4 Key Top 6 Piezoelectric Sheet 7 Upper Electrode 8 Wiring 10 Lower Electrode 11 Wiring 16 Elastic Member 17 Under Cover (Switch Case) 18 Recess

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[Procedure amendment]

[Submission date] December 7, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

Reference numeral 6 denotes a piezoelectric sheet made of a polymer compound such as polyvinylidene fluoride, which has a function of converting mechanical energy into electric energy such that electricity is generated by receiving impact or vibration, and electric sheet. It has a function of converting electrical energy into mechanical energy such as expanding and contracting by receiving a signal, or generating a vibration of a surface by receiving an electrical signal in a state of being curved and fixed at both ends, A plurality of circularly formed upper electrodes 7 and an upper electrode terminal 9 in which two pairs of the upper electrodes 7 are connected by wiring 8 are laid on the upper surface of this, and the lower surface thereof is indicated by a dotted line in FIG. As shown, a plurality of lower electrodes 10 formed under the upper electrode 7 and a lower electrode terminal 12 in which two lower electrodes 10 are paired and connected by a wiring 11 are laid.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction contents]

Considering the voltage waveform which is the measurement result in FIG. 7, the pulse voltage of the embodiment is about 2.7 to 3.2 times the proportionality, and the keytop 4 is proportional.
Although the size is different between when the key is pressed and when released, in the embodiment, it is understood that the size is substantially the same when the key top 4 is pressed and released.

Claims (3)

[Claims] 1. A key top mounted on a switch case so that it can be pressed, a piezoelectric sheet laid inside the switch case below the key top to generate a pulse voltage due to a piezoelectric effect, and a piezoelectric sheet below the piezoelectric sheet. A recess formed in the switch case, and an elastic member housed in the recess that applies elasticity against the pressing operation of the key top to the piezoelectric sheet and that is elastically deformed rapidly when the pressing operation force of the key top exceeds a predetermined value. A switch device comprising: 2. The switch device according to claim 1, wherein the elastic member is formed in a dome shape. 3. An upper electrode and a lower electrode for extracting a pulse voltage of the piezoelectric sheet are formed in a circular shape so that the electrode area and the operating area coincide with each other, and the wiring connected to the upper electrode and the wiring connected to the lower electrode are formed. 3. The switch device according to claim 1, wherein the switch devices are arranged in a state in which they face each other above and below each other.