JP2007242439A - Light emitting device and flashlight using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device that is compact and exhibits high power generation efficiency, and a flashlight using the same, the flashlight being lightweight, small-sized and especially convenient for at-hand illumination in a disaster emergency, not requiring maintenance. <P>SOLUTION: This light emitting device comprises: a piezoelectric element that is generally rectangular in shape and includes a piezoelectric plate and a reinforcing plate, the piezoelectric plate being divided into two sections such that positive and negative polarizations in the thickness direction are in opposite directions to each other, arranged along the longitudinal direction of the reinforcing plate and bonded to the reinforcing plate; a first holding member for holding one lengthwise end of the piezoelectric element; a second holding member for holding the other lengthwise end of the piezoelectric element; an electric circuit for taking out electric energy from the piezoelectric element; and a light emitting diode connected to the electric circuit. An external force applied to the second holding member causes the piezoelectric element to be displaced in its thickness direction to generate a deformation of the piezoelectric element. The piezoelectric plate is thereby bent to generate power, so that electric energy is obtained to allow the diode to emit light. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a light emitting device that converts external energy such as vibration into electric energy, and a flashlight using the same.

Conventionally, many inventions have been made on light emitting devices and flashlights using the same, and they are used as portable lights for walking at night, emergency lights for power outages, and the like. A normal light emitting device and a flashlight using the same include a battery or a manual generator and a charger. A device equipped with a battery has a problem of non-lighting during use due to battery consumption. A device equipped with a manual generator and a charger is composed of an electromagnetic induction generator having a magnet and a coil, and has a large number of parts. It is difficult to say that it is lightweight, small and convenient to carry. In addition, in a piezoelectric light emitting device that emits a light emitting body such as a light emitting diode using an electromotive force generated by stress applied to the piezoelectric element, in a warning lamp that is shaken by hand, the vibration and stress applied are used. A non-power-supply piezoelectric light emitting device characterized by causing a light emitter to emit light is disclosed. (Refer to Patent Document 1) Further, when the piezoelectric elements are stacked in order to obtain a large electric energy, it is necessary to devise a device that prevents the piezoelectric element plate from being detached from the holding member against a sudden large displacement. In this improved type, when the piezoelectric element is rectangular, it is possible to support it with one end with the other end of the piezoelectric element part as a free end without providing holding members at both ends, but avoid deformation of the piezoelectric element itself by long-term use. In order to avoid contact with each other, it is necessary to take a long holding portion corresponding to the deformation of the piezoelectric element.

Japanese Patent Laid-Open No. 2001-351416

  The present invention has been made in view of such circumstances, and is a light-emitting device that is compact and has high power generation efficiency and a flashlight using the light-emitting device, and is light and small, and is particularly convenient for lighting at hand in the event of a disaster. The purpose is to provide a flashlight that does not require maintenance.

According to the first aspect of the present invention, a substantially rectangular shape having a piezoelectric plate and a reinforcing plate, the positive and negative of polarization in the thickness direction along the longitudinal direction of the reinforcing plate is reversed. A piezoelectric element including a piezoelectric plate disposed and bonded in half, a first holding member that holds one end of the piezoelectric element in the longitudinal direction, and a first holding member that holds another end in the longitudinal direction of the piezoelectric element And a light emitting diode connected to the electric circuit, and an external force applied to the second holding member causes the piezoelectric element in the thickness direction. Disclosed is a light emitting device in which the piezoelectric element is displaced and the piezoelectric element is deformed, whereby the piezoelectric plate is bent all at once to generate electric power to obtain electric energy, and the light emitting diode emits light. To do.

Further, a plurality of piezoelectric elements according to claim 1 are laminated in the thickness direction of the piezoelectric elements, and one end in the longitudinal direction is the first holding member so that the plurality of piezoelectric plates do not contact each other in the thickness direction, In addition, the other end in the longitudinal direction is integrated and held by the second holding member so that the plurality of piezoelectric plates do not contact each other in the thickness direction, and by external force applied to the second holding member, The light emitting diode according to claim 1, wherein the piezoelectric element is displaced in the thickness direction of the piezoelectric element, and the piezoelectric element is deformed, whereby the piezoelectric plate is bent all at once to generate electric power, and electric energy is obtained, and the light emitting diode according to claim 1 emits light. A light-emitting device is provided.

According to the second aspect of the present invention, the first holding member serves as a grip portion or is fixed to the grip portion, and the second holding member has a long vibration in the longitudinal direction of the piezoelectric element. The child is fixed, or the second holding member is a vibrator that is long in the longitudinal direction of the piezoelectric element, and external force is applied to the second holding member and / or the vibrator by vibration of a hand that grips the grip portion. 3. A flashlight using a light-emitting device according to claim 1, wherein electrical energy is obtained when the piezoelectric element is deformed by external force in the previous period, and the light-emitting diode emits light. To do.

According to the light emitting device of the present invention, since the piezoelectric element is used, large electric energy can be obtained with a small displacement. In addition, since the entire support portion moves, even when the displacement is large, the piezoelectric element can take out electric energy with high efficiency without dropping from the support portion. Furthermore, high integration can be achieved with a compact device. Since the displacement in the vicinity of the support portion is small, the stress load at the end of the piezoelectric element is light and the life is long. In addition, a flashlight using this is a compact flashlight with high power generation efficiency, is lightweight and small, is particularly convenient for lighting at hand in the event of a disaster, and does not require maintenance.

The light emitting device 100 in FIG. 1 includes a piezoelectric element 13 formed by bonding a rectangular piezoelectric plate 11 and a rectangular reinforcing plate 12 together. It is a piezoelectric element 13 including a piezoelectric plate that is arranged and bonded in two along the longitudinal direction of the reinforcing plate 12 so that the polarity of the polarization in the thickness direction is reversed. A first holding member 20 for holding one end in the longitudinal direction of the piezoelectric element; a second holding member 30 for holding another end in the longitudinal direction of the piezoelectric element; an electric circuit for extracting electric energy from the piezoelectric element; The light-emitting diode 70 is connected to the electric circuit. The external force is applied to the second holding member 30 by the vibrator 60 attached to the second holding member 30, for example, by gripping and shaking the grip portion also serving as the member 20. As a result, the piezoelectric element is displaced in the thickness direction of the piezoelectric element, and the piezoelectric element is deformed, whereby the piezoelectric plate is bent to generate electric power, electric energy is obtained, and the light emitting diode 70 emits light. The light emitting device 100 is characterized.

The piezoelectric plate 11 has a structure in which electrode films (not shown) are formed on the front and back surfaces of a rectangular piezoelectric ceramic, and the piezoelectric plate is substantially divided into two at the center. The piezoelectric ceramic of the piezoelectric plate is polarized in the thickness direction. The polarization direction is positive in the divided portion and negative in the reverse direction. The piezoelectric plate 11 is bonded to the reinforcing plate 12 using a resin adhesive. A piezoelectric polymer may be used instead of the piezoelectric ceramic. The reinforcing plate 12 is made of at least one of metal and resin, and has a rectangular shape longer than the piezoelectric plate 11. When a resin plate is used as the reinforcing plate 12, a metal foil is provided on the surface to be bonded to the piezoelectric plate 11 in order to facilitate the removal of electrode leads (not shown) from the piezoelectric plate 11. It is preferable to use what is.

  In the energy conversion device 100 illustrated in FIG. 1, the second holding member 30 is moved by the vibrator 60 attached to the second holding member 30 by swinging the grip portion that also serves as the first holding member 20 by hand. Power is generated by external force applied to That is, an external force acts on the second holding unit 30 through the vibrator 60 and the piezoelectric element 13 held by the first holding unit 20 is a straight line or a parallel line. The piezoelectric elements are aligned to generate electric power by repeating displacement in the S shape of FIG. 1C or the anti-S shape of FIG. 1B. FIG. 2 schematically shows a cross-sectional view showing a driving mode of the energy conversion device 100, and FIG. 3 shows a circuit configuration diagram for recovering electrical energy from the energy conversion device 100. As shown in FIG. This is a configuration example in which electric energy is extracted from a plurality of piezoelectric elements.

  As shown in FIG. 2, for example, as a result of vibration of the vibrator 60, when a force in the −Z direction is applied to the second holding unit 30 and a force in the + Z direction is applied to the first holding unit 20, the piezoelectric element 13 is Bends to be S-shaped. S-shaped bending means that when viewed from the side surface of the piezoelectric element, the right side piezoelectric element is bent upward and the left side piezoelectric element is protruded downward, with the central portion in the length direction of the piezoelectric element as a turning point. I mean.

Further, as a result of the vibration of the vibrator 60, when a force in the + Z direction is applied to the second holding unit 30 and a force in the -Z direction is applied to the first holding unit 20, the piezoelectric element 13 becomes anti-S-shaped. Bend. Therefore, when vibration in the Z direction is applied to the second holding unit 30, the piezoelectric element 13 repeats bending vibration that is deformed, and the piezoelectric plate 11 generates power at that time. As described above, the piezoelectric element of one reinforcing plate is divided into two at the central portion. Therefore, if the polarization direction is reversed, the electromotive force due to bending due to S-shaped or anti-S-shaped deformation is reduced. The sign is the same on the reinforcing plate side and the same on the piezoelectric ceramic surface side. This is because both the S-shape and the anti-S-shape are shrunk on the inner side, and a stress is applied to the outer side to cause bending corresponding to the stress. If the polarization directions are the same, the positive / negative of the electromotive force due to the bending due to the S-shaped or anti-S-shaped deformation is reversed on the reinforcing plate side and also on the piezoelectric ceramic surface side. This is because both the S-shape and the anti-S-shape are shrunk on the inner side, and a stress is applied to the outer side to cause bending corresponding to the stress.

Therefore, as shown in FIG. 3, this electromotive force can be taken out by connection in consideration of positive and negative. Since the electrical energy obtained in this way is AC power, normally, as shown in FIG. 3, the power is converted into DC power through a rectifier circuit and charged in a power storage device such as a capacitor or a secondary battery, or The load can be driven by supplying it directly to the “load”. Alternatively, DC power can be obtained through a rectifier circuit for each piezoelectric element or by inserting a rectifier circuit for each piezoelectric element group.

  The light emitting device 100 can be easily downsized by using the piezoelectric element 13. The amount of displacement of the piezoelectric element 13 can be adjusted by changing the material and thickness of the reinforcing plate and the shape and number of the piezoelectric elements, thereby realizing an energy conversion device using a piezoelectric element that is largely displaced by a weak force. If possible, an energy conversion device using a piezoelectric element that is displaced by a strong force can be realized. Even in this case, sufficiently large electric energy can be obtained by using the piezoelectric element.

  Regarding the holding members 20 and 30 and the piezoelectric element 13, as the reinforcing plate 12, in general, materials having various spring properties such as a resin substrate, a metal, and a metal plate can be used, but a metal plate is preferable. Used. When a large force is required, metal materials such as engineering ceramics and stainless steel having excellent mechanical strength are preferably used.

  When the piezoelectric element 13 is deformed, a predetermined force is applied to the holding member, the spacer portion, and the vibrator. For this reason, mechanical strength that does not cause deformation when such a force is applied is required. From such a viewpoint, various materials such as plastic resin, stainless steel, and aluminum alloy are suitably used for the holding member. A material equivalent to the holding member can be used for the spacer portion. The vibrator is also required to have rigidity capable of transmitting an external force. An appropriate weight can be added to the vibrator to optimize the period of vibration.

  In the case where a metal material is used for the holding member and a metal material is also used for the reinforcing plate 12 constituting the piezoelectric element 13, the holding members 20 and 30 have high mechanical strength and insulation. Ceramic materials (for example, alumina, zirconia, mullite, etc.) can be used.

  FIG. 2 schematically shows the deformation of the piezoelectric element 13 when vibration is applied to the holding members 20 and 30. Since the piezoelectric element on one reinforcing plate 12 is divided into two at the central portion, if the polarization direction is reversed, the piezoelectric element is caused by bending due to S-shaped deformation (or anti-S-shaped deformation). The sign of power is reversed on the reinforcing plate side and also on the piezoelectric ceramic single surface side.

This is because both the S-shape and the anti-S-shape are shrunk on the inner side, and a stress is applied to the outer side to cause bending corresponding to the stress. If the polarization directions are the same, the sign of the electromotive force is the same on the reinforcing plate side and the same on the piezoelectric ceramic surface side due to the bending due to the S-shaped or anti-S-shaped deformation. This is because both the S-shape and the anti-S-shape are shrunk on the inner side, and a stress is applied to the outer side to cause bending corresponding to the stress. Therefore, this electromotive force can be taken out by connection in consideration of the sign of the electromotive force.

Since the electric energy obtained from the piezoelectric element is AC power, it is usually converted into DC power by a rectifier circuit as shown in FIG. 3 and charged to a power storage device such as a capacitor or a secondary battery. Alternatively, the load can be driven by supplying the load directly. Alternatively, DC power can be obtained by inserting a rectifier circuit for each piezoelectric element, or by inserting a rectifier circuit for each piezoelectric element group.

  When the polarization direction of the piezoelectric plate 11 divided in two is different, the reinforcing plate 12 short-circuits the electrode film on the bonding surface side of the piezoelectric plate 11a and the electrode film on the bonding surface side of the piezoelectric plate 11b. The structure may be sufficient. For this reason, a metal foil / metal plate can be used as the reinforcing plate 12. On the other hand, when the polarization direction of the piezoelectric plate 11 is the same, the reinforcing plate 12 needs to have a structure that does not short-circuit the electrode film on the bonding surface side of the piezoelectric plate 11a and the electrode film on the bonding surface side of the piezoelectric plate 11b. For this reason, when using a metal foil / metal plate as the reinforcing plate 12, one of the piezoelectric plates 11a / 11b is connected to the metal foil / metal plate via an insulating film so as not to short-circuit the metal foil / metal plate. A device such as bonding is required. In addition, when using a reinforcing plate 12 that is made of a resin substrate with a metal foil attached, such as a printed circuit board, the metal foil is connected to the inner peripheral side and the outer periphery so that the piezoelectric plates 11a and 11b are insulated. What is necessary is just to set it as the pattern divided into the side part.

  Another embodiment of the light emitting device will be described. FIG. 4 shows a front sectional view and a plane sectional view showing a schematic structure of the light emitting devices 200 and 300. The light emitting devices 200 and 300 both have the embodiment in which the first holding unit 20 is fixed to the inside of the cylindrical or hollow rectangular gripping unit 80 and the action point portion of the rod-shaped vibrator 60 is fixed to the holding member 30. is there. The fulcrum portion of the rod-shaped vibrator 60 is supported on the bottom or end of the grip portion 80 so as to be rotatable. In the light emitting device 200, the length of the fulcrum can be secured from the force point to the entire length of the vibrator, and a large force can be applied to the piezoelectric element with a smaller force, but the end portion is designed to be an open end. . In the light emitting device 300, the total length of the length from the fulcrum to the fulcrum and the length from the fulcrum to the action point is the length of the vibrator. The piezoelectric element is held by the first holding part and the second holding part, the piezoelectric plate is divided into two at the approximate center of the reinforcing plate, and the positive and negative of the polarization in the thickness direction is reverse along the longitudinal direction of the reinforcing plate The piezoelectric element including the piezoelectric plate which is divided and arranged so as to be attached is formed. When the piezoelectric element is deformed into an S-shape or an anti-S-shape due to an external force applied to the second holding portion 30 and the piezoelectric plate is bent, the piezoelectric element is relatively displaced in the thickness direction. Has an electric circuit that generates electric energy by taking out electric power and takes out the electric energy, and a light emitting diode connected to the electric circuit, so that the piezoelectric plate is bent to generate electric power when the element is deformed. Then, electric energy is obtained, and the light emitting diode emits light.

In addition, in the light emitting devices 100, 200, and 300, the piezoelectric element 13 has a so-called bimorph structure in which the piezoelectric plate 11 is attached to both surfaces of the reinforcing plate 12. A so-called unimorph structure to which the piezoelectric plate 11 is attached may be used. Furthermore, the piezoelectric plate is not limited to a single plate, and may have a multilayer structure (multilayer capacitor type structure).

  The electrical energy extracted from the light emitting device is used for charging a power storage device such as a battery or a capacitor, or is used for driving the electrical device. For example, if it is an automobile when it is used for a moving body, examples of the electric device include a blinker lamp, a stop lamp, a headlight, a taillight, a wiper, a power window, a car navigation system, and an audio. If the moving body is a hybrid vehicle, an electric vehicle, or a fuel cell vehicle, an electric motor for traveling is further included. In addition, if the moving body is a vehicle such as a train, examples of the electric device include an in-vehicle display board (stop station guidance, in-vehicle advertising liquid crystal screen, etc.).

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to such embodiment. For example, in the light emitting device, the piezoelectric elements 13 are arranged in series. However, the piezoelectric elements 13 may be arranged in parallel, or may be arranged in series and parallel.

  The light-emitting device according to the present invention is compact and can obtain a large electromotive force and a large current, and is suitable as a light-emitting device that takes out vibration energy from a human body such as a hand or various structures, and is suitable for a non-powered flashlight. Use.

Sectional drawing which shows schematic structure of the drive of the light-emitting device which concerns on this invention FIG. 2 is a cross-sectional view schematically showing a driving mode of the light emitting device shown in FIG. FIG. 2 is a configuration diagram illustrating a circuit for recovering electrical energy of the light emitting device shown in FIG. Sectional drawing which shows schematic structure of another light-emitting device which concerns on this invention.

Explanation of symbols

100/200/300; Light-emitting device
11,11a, 11b; Piezoelectric plate
12; Reinforcing plate
13: Piezoelectric element
20; 1st holding part
30; Second holding part
21; Spacer
60; vibrator
70; Light-emitting diode
80; grip

Claims (3)

A piezoelectric plate having a substantially rectangular shape having a piezoelectric plate and a reinforcing plate, which is arranged and bonded in two along the longitudinal direction of the reinforcing plate so that the polarity of the polarization in the thickness direction is in the opposite direction. A piezoelectric element including a plate;
A first holding member for holding one end in the longitudinal direction of the piezoelectric element;
A second holding member for holding another end in the longitudinal direction of the piezoelectric element;
An electrical circuit that extracts electrical energy from the piezoelectric element;
A light emitting diode connected to the electrical circuit;
Have
Due to the external force applied to the second holding member, the piezoelectric element is displaced in the thickness direction of the piezoelectric element, and the piezoelectric element is deformed, whereby the piezoelectric plate is bent to generate electric power, and electrical energy is obtained, A light emitting device, wherein the light emitting diode emits light. A plurality of piezoelectric elements according to claim 1 are laminated in the thickness direction of the piezoelectric elements,
One end in the longitudinal direction is integrally held by the first holding member so that the plurality of piezoelectric plates do not contact each other in the thickness direction,
Furthermore, the other end in the longitudinal direction is integrated and held by the second holding member so that the plurality of piezoelectric plates do not contact each other in the thickness direction,
The external force applied to the second holding member displaces the piezoelectric element in the thickness direction of the piezoelectric element, and the piezoelectric element is deformed, so that the piezoelectric plate is bent all at once to generate electric power, thereby obtaining electric energy. The light emitting diode according to claim 1 emits light. The first holding member serves as a grip portion or is fixed to the grip portion, and a long vibrator is fixed to the second holding member in the longitudinal direction of the piezoelectric element, or the second holding member The holding member is a vibrator that is long in the longitudinal direction of the piezoelectric element, and an external force is applied to the second holding member and / or the vibrator by vibration of a hand that grips the grip portion, and the piezoelectric element is applied to the piezoelectric element by a previous external force. 3. The flashlight using the light emitting device according to claim 1, wherein electrical energy is obtained by the deformation and the light emitting diode emits light.

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