WO2000068066A1

WO2000068066A1 - Piezoelectrically operated led

Info

Publication number: WO2000068066A1
Application number: PCT/DE2000/001417
Authority: WO
Inventors: Herwig Fitz
Original assignee: Herwig Fitz
Priority date: 1999-05-07
Filing date: 2000-05-07
Publication date: 2000-11-16
Also published as: AU5802300A; DE19921055A1

Abstract

The invention relates to a blinker, especially a safety blinker, with at least one light-emitting diode (2, 3), at least one piezoelectric element (1, 211, 212, 31, 41, 51, 61, 71, 81, 82) which supplies power to the light-emitting diode (2, 3) and which is held by at least one elastic carrier plate (221, 222, 32, 42, 52, 62, 72, 73, 83, 84). One component of said carrier plate (221, 222, 32, 42, 52, 62, 72, 73, 83, 84) including an opposite edge thereof with the exception of a first edge of said carrier plate (221, 222, 32, 42, 52, 62, 72, 73, 83, 84) can be moved cross-wise in relation to the surface thereof.

Description

PIEZOELECTRICALLY OPERATED LED

Description

The invention relates to a flashing light, in particular a safety flashing light, with at least one light-emitting diode, at least one piezoelectric element which supplies the light-emitting diode and which is held by at least one elastic carrier plate.

Direction indicators are used to draw attention to special danger points in the dark, especially so that people who move in the dark can be recognized in good time. Direction indicators are also simply used as eye-catchers to attract attention or to convey joie de vivre.

Safety indicators equipped with LEDs are sold, for example, as bicycle accessories or for joggers to be carried on the arm. These flashing lights are usually powered by batteries.

The disadvantage of battery-operated turn signal lamps is that a battery is used up after a certain operating time, so that it must be replaced. This not only creates operating costs for the consumer, it also creates waste that has to be disposed of as special waste. Also, replacement batteries are not readily available for replacement at any time, so there is a risk that the turn signal lamp is not always ready for use.

These disadvantages are avoided in a flashing light known from DE 296 04 903 Ul of the type mentioned in that the light-emitting diode is supplied with current pulses via a piezoelectric element.

In a piezoelectric element, the effect is exploited that charges are shifted with the deformation of the element and the resulting displacement of the crystal lattice in the piezoelectric element. This allows the a voltage can be tapped on opposite surfaces of the piezoelectric element. If the piezoelectric element is deformed and then returned to an initial position, different voltages are present on the surfaces. This voltage change is accompanied by a current pulse that can be used to operate light-emitting diodes. With sufficiently rapid and alternating deformation of the piezoelectric element, a flashing light can thus be implemented in the simplest way. The faster the piezoelectric element is deformed, the stronger the current pulse generated and the brighter the LED lights up.

To generate electricity, the known piezo generator is subjected to a mechanical pulse via a force transducer, so that a current pulse is generated which causes the light-emitting diode to light up. The piezo generator consists of one or more piezoelectric elements arranged parallel to one another, the edge regions of which are spring-mounted in a cup-like frame via elastic electrodes acting as carrier plates.

The force transmitter acts on the central area of the surface of a piezoelectric element. Either levers are proposed as force transmitters, one of which can be moved against the force of a return spring and with which, for example, the unevenness of the tire wall of a rotating bicycle tire can be used to generate a mechanical pulse. In another exemplary embodiment, a spring-mass system is fixedly attached to the surface of a piezoelectric element and can be set in vibration, as a result of which periodic pulses act on the surface of the piezoelectric element.

However, the proposed embodiments for generating a mechanical impulse are comparatively complex in terms of space and construction.

The present invention is therefore based on the object of providing a flashing light of the type mentioned at the outset which can be operated without batteries, is space-saving and of simple construction.

This object is achieved in that the remaining part of the carrier plate, including the opposite edge, is relatively movable with respect to one edge of the carrier plate. The essence of the invention is that the transport plate is elastic in its entire area together with the piezoelectric element arranged thereon and can be subjected to oscillation due to bending or torsion.

At the same time, the carrier plate can thus interact directly with a motion sensor so that its elastic properties can be used to reset the motion sensor.

Since the carrier plate is at most fixed on one side and thus the circumferential mounting of the piezoelectric element via the resilient electrode in a cup-like frame is dispensed with, it is possible to use the rest of the carrier plate to absorb forces to generate a current pulse. At the same time, mechanical constructions for applying a mechanical impulse can be considerably simplified.

The piezoelectric element can consist of one or more piezoceramic elements, the surfaces of which are coated with a conductor material.

A suitable carrier plate can consist, for example, of metal or plastic, a conductive material being preferred in principle, since it can simultaneously be used as a contact plate for connecting light-emitting diodes. The carrier plate material should be dimensioned such that the carrier plate always returns to the same rest position from a deflected state when the load is released. The piezoelectric element can be soldered, glued or laminated onto the carrier plate.

As soon as the carrier plate is subjected to a bending moment, the voltage distribution in the piezoelectric element changes, so that a current is generated as a result. In order to exert a bending moment on the carrier plate, it can, for example, be firmly clamped at one of its ends and a force can act on its other end.

For example, a commercially available piezoceramic sound transducer can be used as the piezoelectric element arranged on a carrier plate. It also makes sense to supply two light-emitting diodes in anti-parallel connection with the one or more piezoelectric elements with current. In this way, both the current that is generated when the piezoelectric element is loaded and the current in the opposite direction that is generated when the piezoelectric element is relieved can be used to generate the flashing signal.

In a preferred embodiment, the forces to be applied to the carrier plate can be applied in particular by means of a movement sensor which interacts with the carrier plate. This motion sensor must ensure that dynamic forces that are to be used by the flashing light are applied to the carrier plate in such a way that the greatest possible current is generated, but at the same time the carrier plate and the piezoelectric element located thereon are protected against damage by an overload .

In an advantageous embodiment of the flashing light according to the invention, the motion sensor comprises a spring element and / or a lever arm. In this way, the flow of force from the force to be acted upon can be guided onto the carrier plate and, at the same time, protection against mechanical overloading can be ensured.

For example, two lever arms attached to opposite ends of the carrier plate can be provided and the spring element can be a leaf spring, the leaf spring being held by the lever arms. The leaf spring is guided essentially parallel to the carrier plate. If the leaf spring is loaded towards the carrier plate, the distance between the fastening points of the leaf spring and lever arms is changed. As a result, a torque acts on the attachment points of the lever arms on the carrier plate, which is then transmitted to the elastic carrier plate, so that it changes its position, for example bends out of a rest position. As a result, bending forces act on the piezoelectric element, so that a current is generated.

In this embodiment, the carrier plate is decoupled from an applied movement and thus secured against mechanical overload, especially if the leaf spring or the lever arms are mounted so that only torques and non-directional forces act on the carrier plate. Another advantageous embodiment is that the carrier plate has two plate parts which together form an acute angle and are rigidly coupled to one another. If the free ends of the plate parts are pressed together, the plate parts are bent towards one another, so that the piezoelectric elements held by the plate parts are compressed and a current is generated.

Another embodiment of the flashing light according to the invention is that the support plate is fixed about a central axis, the motion sensor is formed by a pin which is oscillating in a plane obliquely movable to the support plate, the plane of movement of the pin the support plate near the central axis cuts and the pin oscillates in its oscillating movement beyond the end of the carrier plate.

Here, during a vibration, the free end of the carrier plate is first deflected by the pin until it swings beyond the free end and releases the carrier plate again, so that it swings back into its rest position. On the way in the opposite direction, the pin deflects the other free end of the carrier plate in the other direction until it swings back over its end, so that the end can then spring back into the rest position.

In yet another embodiment of the invention, two are piezoelectric

Elements are provided, which are each arranged on a carrier plate, the sides of the carrier plates facing away from the piezoelectric elements being uneven, abutting against one another and displaceably supported in essentially parallel planes and each being deflectable against the force of a return spring.

If the two carrier plates move past one another, they are deflected to different extents at different points, so that the piezoelectric

Element is exposed to different voltage states and a current is generated.

In order to make the sides facing away from the piezoelectric elements uneven, they can each be provided with a corundum layer, for example, or they can also be wavy. Accordingly, it is also possible to move only one piezoelectric element together with the carrier plate with an uneven sliding surface on an equally uneven surface.

The particular advantage in this embodiment is that its overall height is extremely low, since the direction of movement of the elements is in the plane of the piezoelectric elements. The overall height is thus determined only by the piezoelectric elements lying next to one another and a frame for guiding them and the holder for the return springs.

Due to the small size of the components required for the flashing light, a variety of uses are possible.

These flashing lights can be used within a roll for roller skates, inline skates or a skateboard.

In a possible embodiment, a support plate made of two resiliently interconnected plate parts can be arranged underneath in a roller below the running surface, so that the piezoelectric element is pressurized when the part of the roller supporting the support plate rolls on the floor and relieves pressure when other parts of the roll roll on the floor. The light-emitting diode can then be arranged, for example, in the region of the side wall of the roller. If the roll rotates quickly, an observer will perceive the flashing light generated by the light-emitting diode as a circle of light due to the inertia of the eye.

If the roll is made with a transparent material, the entire roll can be illuminated with the LED.

In another embodiment, the carrier plate of a piezoelectric element is not firmly connected to the roller frame on the inside, but rather on one side. The free end of the carrier plate is coupled to a spring arm which has a friction wheel rolling on the roller at its free end. The peripheral surface of the friction wheel can be polygonal or in the form of a cam, so that the spring arm is deflected to different degrees when the friction wheel rolls on the running surface of the roller. The same effect is achieved if the friction wheel is mounted eccentrically. A constantly changing force or a constantly changing bending moment thus acts on the carrier plate, as a result of which the current is generated for the light-emitting diode, with the impression of a continuous light even when driving fast enough. The light-emitting diode can be arranged on the skateboard, roller skates or inline skates in such a way that it radiates to the rear when viewed in the direction of travel and thus takes on the function of a rear light.

The resistance associated with the generation of electricity, acting on the rollers, is so low in both embodiments that it is not perceived by the driver.

The principle of the flashing light can be used in a similar manner in a tire for a vehicle, in particular in a car or bicycle tire, the light-emitting diode in the lateral outer surface of the tire and the piezoelectric element optionally in the tread of the tire or in its lateral outer surface is embedded or put on. The pressure forces acting on the tread of the tire or the flexing forces acting in the side wall of the tire casing can be used here.

The profile of a tire can also be used to deflect a round friction wheel arranged on a spring arm to different extents when rolling on the tread of the tire and in this way to excite a piezoelectric element.

Furthermore, the flashing light can advantageously be used in a shoe, in particular a gymnastic or casual shoe. Thus, the piezoelectric element can be incorporated in the heel area of the shoe sole and can be compressed each time the foot appears and can be relieved when the foot rolls off and off. Alternatively or in combination, it is also possible to provide a piezoelectric element in the area of the ball of the foot. The light-emitting diode can, for example, be arranged in the heel area of the shoe and act as a rear light.

The flashing light can also be used advantageously in a riding or bicycle saddle. For example, the piezoelectric element can be arranged below the seat surface.

Another application for the turn signal lamp is a safety flagpole for vehicles, especially for bicycles and tricycles. The flagpole is attached to the vehicle frame at its lower end, carries a flag at its upper end, is usually made of a resilient plastic and swings back and forth while driving. The carrier plate for the piezoelectric element can also be fixedly supported at one end via the vehicle frame, while the bending moments acting in the flagpole act on the opposite end. The light-emitting diode can preferably be arranged at the upper end of the safety flag pole, so that it is as clearly visible as possible. In the same way, other flagpoles, for example flagpoles for pennants as fan articles, can be provided with flashing lights.

The flashing light can also be used according to the invention for safety clothing, the light-emitting diode being arranged at a clearly visible location on the safety clothing and the piezoelectric element in a movement-intensive area of the safety clothing, in particular in the area of the elbow or knee joint.

Another possible use is in a walking stick or a cane for the blind, in which an elastically mounted plunger is arranged in the tip of the stick, which picks up the bumps when the stick is put on and transmits them to the piezoelectric element. One or more light-emitting diodes can be operated in this way, the light-emitting diodes being able to be arranged distributed over the length of the stick. The stick can also be made of a transparent material, so that the entire stick can be illuminated by the one or more light-emitting diodes.

In a safety helmet, in particular a bicycle helmet, the flashing light can be used if, for example, a long support plate is firmly attached to the helmet at one end and the other end is lightly weighted so that it moves back and forth due to the movement of the helmet wearer commutes here. One or more light emitting diodes can then be embedded in the helmet surface.

In the latter two embodiments, it can preferably be used in a fishing lure, in particular a pilker or wobbier, the relative movement between two limbs of the fishing lure in the water being used to generate a current pulse. The principle of the invention is explained in more detail with reference to the following description of the figures.

Show it

Figure 1 shows an equivalent circuit for a flashing light; as is also known from the prior art, and

Figures 2 to 9 examples of various constructive according to the invention

Versions for power generation with a piezoelectric element.

In the equivalent circuit diagram shown in FIG. 1, the piezoelectric element 1 is connected to two light-emitting diodes 2 and 3 arranged in anti-parallel connection. In the same way, further light-emitting diodes can be connected in parallel, just as several light-emitting diodes can be connected in series antiparallel to further light-emitting diodes connected in series.

FIG. 2 shows a first principle of a very simple construction for generating electricity using a piezoelectric element. Thus, the piezoelectric element 11 is arranged on an elastic carrier plate 12 which is fixedly supported at one end and the other end of which has a degree of freedom. If a force is exerted on the carrier plate 12, it will bend in the direction of the force, so that the piezoelectric element 11 is compressed or stretched and a current is thus generated. If the support plate 12 is relieved, it will move back to its rest position, again generating a current.

Another principle of a simple construction is shown in FIG. Here, the carrier plate is formed in two parts 22, each plate member 22 ,, 22 ₂ _j, a piezoelectric element 21, 21 carries _2. The plate parts 22 _1? 22 ₂ enclose an acute angle and are rigidly connected to one another in the gusset. If the two plate parts 22... 22 _{2 are} pressed together, each plate part 22 _{1 (} 22 ₂ bent so that the piezoelectric element 21 ^ 21 _{2 are} compressed and thus a current is generated. The same applies correspondingly when the plate parts 22 _{1 (} 22 ₂ .

FIG. 4 shows a further design principle in which two spring arms 33, 34 are rigidly attached to opposite ends of the carrier plate 32. The spring arms 33, 34 each form an obtuse angle with the elastic carrier plate 32. They are rotatably supported at a defined distance from the carrier plate 32. If a force acts on the free ends of the spring arms 33, 34 in a direction perpendicular to the plane spanned by the carrier plate 32, the resulting torque is transmitted to the carrier plate 32, so that the piezoelectric element 31 is stretched and a current is thereby generated. The same applies here when the free ends of the spring arms 33, 34 are relieved.

To protect the piezoelectric element 31, the carrier plate 32 can be arranged in a housing 35, shown here in broken lines, the spring arms being rotatably mounted in the housing wall and projecting out of the housing. The free ends of the spring arms 33, 34 can be secured against excessive deflection by stop elements, not shown here.

In the principle shown in FIG. 5, the elastic support plate 42 carrying the piezoelectric element 41 is rigidly connected at opposite ends to lever arms 43, 44 arranged essentially perpendicular to the plane of the support plate. A leaf spring 45 is held between the free ends of the lever arms. It can be under a pretension that is directed against the force to be applied. If the leaf spring 45 is acted upon by the force, it is deformed so that the distance between the ends of the lever arms 43, 44 holding the leaf spring 45 changes. As a result, a bending moment acts on the elastic carrier plate 42, as a result of which the piezoelectric element 41 is compressed or stretched and a current is generated. If the leaf spring 45 is relieved, it moves back into its original shape, whereby a current is generated again.

In these first four design principles, one directed force is used to generate electricity. They are therefore suitable for use in a saddle, in a shoe sole, in tire coats and in rolls. There are also other possible uses that have not yet been named, for example below a tread of a bicycle pedal for the supply of Light-emitting diodes in the area of the reflectors usually attached to the bicycle pedal, or in a floor covering in which light-emitting diodes are embedded, which can indicate, for example, running directions. Another possible application is under, for example, a rubberized tread of the footboard of a scooter. Use in a foldable greeting card is also possible.

In the design principle shown in FIG. 6, the carrier plate 52 carrying the piezoelectric element 51 is fixedly supported at one end. At its opposite end, it is rigidly connected to a motion sensor in the form of a leaf spring 53. At the free end of the leaf spring 53, a friction wheel 54 is rotatably mounted, the tread of which may be polygonal in the circumferential direction or may be designed in the manner of a cam, or may be eccentrically mounted with a round tread. The leaf spring 53 is deflected to different degrees when the friction wheel 54 rolls on a roller 55 or a treadless tire. The resulting forces are transmitted to the carrier plate 52, whereby the piezoelectric element 51 is compressed, stretched or relieved again.

A similar principle is shown in FIG. 7, in which the friction wheel 64 is round and is mounted centrally. If the friction wheel 64 runs on a profiled tire or a ring gear 65, the spring arm is also deflected here and the piezoelectric element 6l is compressed or stretched.

A torque is used in each of these two construction principles. In addition to the uses already mentioned, they can also be used to operate LEDs in bicycle pedals when the friction wheel rolls on the axis of the bicycle pedals.

FIG. 8 shows another construction principle in which the piezoelectric element 71, shown here in a side view, is arranged between two elastic carrier plates 72, 73. It is fixed in the area of a central horizontal axis and extends obliquely in space, the angle between the piezoelectric element 71 together with the support plates 72, 73 and the horizontal plane being approximately 30 ° in the example shown. The motion sensor is formed by a pin 74, which is oscillatable in the horizontal plane obliquely to the carrier plate within a guide 75, the plane of movement of the pin 74 being close to the carrier plate intersects its central axis and the pin can oscillate in its oscillating movement beyond the end of the carrier plate. If the pin 74 swings towards the carrier plate 73 from its position shown, it will bend the free end of the piezoelectric element 71, which is on the right in the figure, together with the carrier plates 72, 73 into the horizontal plane until the pin 74 over the end of the carrier plate 73 swings out. At this moment, the piezoelectric element 71 together with the carrier plates 72, 73 can spring back into its original position. The same applies if the pin 74 is then moved in the opposite direction towards the carrier plate 73. So that the pin moves both in one and in the other direction, it is deflected against the force of a return spring, which is not shown here for reasons of clarity.

In the construction, care must be taken that either the central axis of the package of piezoelectric element 71 and carrier plates 72, 73 is slightly displaceable in the vertical direction, or that the horizontal plane of movement of the pin 74 is variable so that the pin can move in both directions on the Package can move past.

The design principle shown in FIG. 9 shows two piezoelectric elements 81, 82, which are each arranged on a carrier plate 83, 84, the sides of the carrier plates 85, 86 facing away from the piezoelectric elements being uneven. The uneven sides of the carrier plates 85, 86 lie against one another. They are mounted so as to be displaceable in substantially parallel planes, being held together by means of elastic clamp elements 87, 88. They can be deflected against the force of a return spring 91, 92 by the tensile forces applied via the connecting tongues 89, 90. In this case, the support plates 83, 84 which bear against one another will press differently from one another in different ways, so that different and changing voltage states occur in the piezoelectric element, as a result of which current pulses can be generated. The unevenness of the uneven sides 85, 86 of the carrier plates 83, 84 can be formed directly on the carrier plates, for example in the form of a wave. However, they can also be coated, for example with corundum, so that a surface similar to sandpaper is produced.

At least one of the abutting lower sides 85, 86 of the carrier plates 83, 84 should be designed insulated so that the piezoelectric elements 81, 82 are not electrically connected to one another. In the example shown, the piezoelectric elements 81, 82 are largely embedded in the carrier plates 83, 84 so that they do not get caught on the clamp elements 87, 88 during the oscillating movement of the carrier plates 83, 84. In this case, care must be taken to ensure that the mounting of the end faces of the piezoelectric elements 81, 82 by the carrier plates 83, 84 does not short-circuit the surfaces of the piezoelectric elements 81, 82. A corresponding enclosure of a piezoelectric element can also be used in all other exemplary embodiments.

The embodiments shown in FIGS. 8 and 9 can be used in particular to generate current pulses from oscillating tensile forces. In particular, the exemplary embodiment according to FIG. 9 can preferably be used between two belts or on the surface of elastic belts. It can also be used in fishing lures such as pilkers or wobblers, whereby the movements resulting from the relative movement between different links of the fishing lure can be used.

With all of the principles, power generation is essentially silent.

Claims

Patent claims

1. Flashing light, in particular safety flashing light, with at least one light-emitting diode (2, 3), at least one piezoelectric element (1, 21, 21, 31, 41, 51, 61, 71, 81) that supplies the light-emitting diode (2, 3) , 82) which is held by at least one elastic carrier plate (22 ,, 22 ,, 32, 42, 52, 62, 72, 73, 83, 84), characterized in that with respect to an edge of the carrier plate (22, , 22 ,, 32, 42, 52, 62, 72, 73, 83, 84) the remaining part of the carrier plate (22 „22 ,, 32, 42, 52, 62, 72, 73, 83, 84) including the opposite Edge is relatively movable across its surface.

2. Flashing light according to claim 1, characterized by a motion sensor that cooperates directly with the carrier plate (22 ,, 22 ,, 32, 42, 52, 62, 72, 73, 83, 84).

3. Flashing light according to claim 2, characterized in that the movement sensor comprises a spring element and / or a lever arm (43, 44).

4. Flashing light according to claim 3, characterized in that two lever arms (43, 44) attached to opposite ends of the carrier plate (42) are provided and the spring element is a leaf spring (45), the leaf spring (45) from the lever arms ( 43, 44) is held.

5. Flashing light according to claim 3, characterized in that the spring element is a second elastic carrier plate (22,) with a second piezoelectric (21) element thereon, the first carrier plate (22,) and the second carrier plate (22 ₂ ) together enclose an acute angle and are rigidly coupled together.

6. Flashing light according to claim 2, characterized in that the carrier plate (72, 73) is fixed about a central axis, the motion sensor a pin (74) is formed, which can oscillate in a plane obliquely to the carrier plate (72, 73), the plane of movement of the pin (74) intersecting the carrier plate (72, 73) near the central axis and the pin (74) oscillates in its oscillating movement beyond the end of the carrier plate (72, 73).

7. Flashing light according to claim 1, characterized by two piezoelectric elements (81, 82), each arranged on a carrier plate (83, 84), the sides of the carrier plates (83, 84) facing away from the piezoelectric elements (81, 82). are uneven, abut one another and are mounted displaceably against one another in substantially parallel planes and can each be deflected against the force of a return spring (91, 92).

8. Use of a flashing light according to one of claims 1 to 5 within a role for roller skates, inline skates or skateboard.

9. Use of a flashing light according to claim 8, characterized in that the roller is made with a transparent material.

10. Use of a flashing light according to one of claims 1 to 5 in a tire for a vehicle, in particular in a car or bicycle tire, the light-emitting diode in the lateral lateral surface of the tire and the piezoelectric element optionally in the tread of the tire or in its lateral Shell surface is embedded or put on.

11. Use of a flashing light according to one of claims 1 to 5 for safety clothing, the light-emitting diode being arranged at a clearly visible location on the safety clothing and the piezoelectric element in a movement-intensive area of the safety clothing, in particular in the area of the elbow or knee joint.

12. Use of a flashing light according to one of claims 1, 6 or 7 in a belt under tension, in particular a shoulder strap of knapsacks or backpacks. Use of a flashing light according to one of claims 1, 6 or 7 in a fishing lure, in particular a pirk, wherein the relative movement of two limbs of the fishing lure in the water is used to generate a current pulse.