WO1987005402A2

WO1987005402A2 - Piezo-electric detector for detecting motions comprising a recorder apparatus for recording detected motions

Info

Publication number: WO1987005402A2
Application number: PCT/BE1987/000002
Authority: WO
Inventors: Joseph Varga
Original assignee: Joseph Varga
Priority date: 1986-02-28
Filing date: 1987-03-02
Publication date: 1987-09-11
Also published as: WO1987005402A3; EP0259384A1

Abstract

The motion detector according to the invention is comprised of a piezo-electric element (26, 27) provided with electrodes (28) and mounted inside a closed housing (31) wherein a weight (25) is movably enclosed. The piezo-electric element provides a pulse when it is struck by the weight (25). A micro-computer (18) adds and records the pulses of the terminals of said piezo-electric element (26, 27).

Description

PIEZOELECTRIC MOTION DETECTOR COMPRISING A DEVICE RECORDING DETECTED MOVEMENTS.

The present invention relates to a piezoelectric detector of movements of a support on which it is fixed, comprising at least one piezoelectric element provided with electrodes and integral with a closed enclosure and a counterweight movably enclosed in said enclosure, flyweight which by moving emits shocks which are transmitted to the piezoelectric element and produces electric pulses at the electrodes of the latter.

European patent application No. 0171848 discloses a device for detecting movements of a support on which said detector device is fixed, σui comprises at least one piezoelectric element provided with electrodes and secured to a closed container and a grain movably enclosed in said container.

This grain generates shocks on the walls of the container, which are transmitted to the piezoelectric element and produce electric pulses on the electrodes of the piezoelectric element.

In this known device, the piezoelectric element is fixed to an outer wall of the container and "listens" to the container so that the mechanical deformation imprinted on the container can be transferred to the piezoelectric element and reveal variations in electrical charges which are collected by electrodes.

Such a detector is unable to discern two perpendicular directions. It also does not lend itself to miniaturization because of the large inertia of the parts. In addition, it requires application and filtering electronics.

The present invention aims to remedy the aforementioned drawbacks and proposes a device for detecting movements of a support on the leo which it is fixed, comprising at least one piezoelectric element provided with electrodes and integral with a closed enclosure and a weight encased with mobile manner in said enclosure, flyweight which when moving emits shocks σui are transmitted to the piezoelectric element and produces electrical pulses on the electrodes of the latter. The movement detector device is essentially characterized in that the piezoelectric element or elements are fixed inside the enclosure and receive the impact of the counterweight.

The counterweight can be a ball, a cylinder or a mobile prism which, moving, strikes the piezoelectric element (s) which deliver an impulse to each percussion of the counterweight.

The piezoelectric element is advantageously of the type of that used in a piezoelectric speaker.

This pulse or output signal activates a calculator without, or preferably with memory, and / or solar power, - the addition of the number of contacts established or pulses or output signals delivered by the sensor is equal to the number of back and forth movements or oscillations of the moving body.

According to a feature of the invention, the detector consists of a tube in which slides freely a weight in the form of a ball, a cylinder or any other suitable form which, with each reciprocating or oscillating movement of the moving body establishes electrical contact or provides an impulse or an output signal.

According to yet another embodiment of the invention, the detector is an accelerometer, for example quartz.

Other details and particularities of the invention will appear during the following detailed description referring to the attached drawings which show, by way of nonlimiting examples, various embodiments of this invention.

In these figures:

Figure 1 is an exploded view of a piezoelectric device according to the invention, intended to be adapted on the handle of a toothbrush;

Figure 2 is a perspective view of the device illustrated in Figure 1;

Figure 3 is a perspective view of a piezoelectric element;

FIG. 4 shows the electrical diagram for mounting the piezoelectric element in an integrated circuit of a microcomputer;

FIG. 5 illustrates the program for recording the number of oscillations.

In these figures, the same reference signs designate identical or analogous elements.

EXAMPLE 1

The improved toothbrushes developed to date are based on the principle of measuring brushing time, to achieve reproducibility and consistency in the quality of brushing. The precision thus obtained is not very good because some brush their teeth quickly, others slowly. However, it is just as harmful to brush your teeth too much because inevitably the brush inflicts micro-injuries to the gum, injuries which must be avoided. In addition, the use of scouring powder and acids in toothpastes that claim to be anti-tartar, has the consequence that any unnecessary brush stroke damages the enamel.

The superiority of the invention discussed in this patent makes it possible to achieve better precision and reproducibility, since the number of brush strokes is measured instead of a brushing time.

In addition, the movements being detected in two perpendicular directions, they can be summed separately. This selective totalization is used in one of the more efficient prototypes.

For brushing to be effective, it must reach a certain value which can be measured by the number of times the brush is rubbed on the affected teeth.

This number is measured and controlled using the toothbrush according to the invention which makes it possible to check whether the brushing has been carried out correctly, the counting of the different successive movements of the brush being done automatically by adding the movements and a device is provided. to signal acoustically and / or visually when the number of movements is reached.

According to the invention, the toothbrush is equipped with a detector which may, to simplify manufacture, consist of a tube preferably located at the end of the handle of the brush and in the extension thereof, on the side opposite to the brush, in which tube freely slides a counterweight of suitable shape and dimensions allowing that a contact is established at each movement of the brush, or that an impulse or an output signal is given which add up to that the adjustable number of preset movements is reached, which can trigger an informative -sound, light or other signal announcing to the user of the brush, that sufficient brushing is reached.

When the brush is intended for the use of children, it may be wise to plan, for example from European patent application No. 0199158, that the brush counter will emit or control the emission of rhythmic music, during the duration of brushing, encouraging children to scrupulously brush the teeth necessary for their proper maintenance.

Since we may have to give the brush movements in different planes, it can it would be useful, according to the invention, to place two or two to several detectors arranged, for example, orthogonally and whose output signals can add up, thus making it possible to control complex or variable movements of the brush.

The back and forth brushing movement time required varies practically between one and five minutes, and the dentist constantly insists with his patients that the brushing of teeth is properly carried out and measured, i.e. - say that you count how many times you have brushed a given area of teething because there are people who brush their teeth quickly and others slowly.

In a particular embodiment illustrated in FIG. 1, the motion detector device according to the invention comprises an LCD display frame 1, fixed by a double-sided adhesive strip 2, to a box 3 of electronic circuit. The tubular case 3 houses a battery support 4.

A 0-ring seal 5 seals the housing 3.

A start switch 6, held by a spring 7, makes it possible to activate the device using an alkaline battery 8 of 1.5 V and 38mAH carried by a contact 9.

Fixing screws 10,21 hold a printed circuit 19 isolated by a seal 11 in place.

The battery compartment is closed by an O-ring seal 12 making it possible to tightly apply a valve 13 held by a screw 14. A crystal display 15 liquids is made more visible by a reflector 16. The device also includes zebra strips 17, an integrated circuit 18 of the LC 5732 type, a piezoelectric motion detector 20 and a loudspeaker 22.

The motion detector device is relatively waterproof, that is to say it can be in the shower for a few minutes. Its solidity allows it to resist shocks: fall from lm on hard ground.

One of the sides of the housing is a sleeve 23 which fits on the handle of the toothbrush, possibly thanks to an intermediate piece.

The motion detector uses a piezoelectric wafer 24, as used in the piezoelectric speakers. This wafer 24 is illustrated in FIG. 4. It is cut into two elements 26, 27 mounted at right angles in the form of a bracket which is fixed to the internal orthogonal walls of a cavity 31. A counterweight made of a small ball 25 comes, due to its "inertia, to hit a face 26 of the piezoelectric element constituting the motion detector, that is to say the face which is perpendicular to the direction of movement, when the detector is moved back and forth. The arrangement of two elements 26, 27 at right angles makes it possible to detect back and forth movements in two perpendicular directions.

Such a detector provides, in the absence of any amplifier, voltage variations across the electrodes 28 of each piezoelectric element 26, 27 of the order of several volts.

The computer system of the embodiment described below front is composed of a CMOS microcomputer programmed by mask so as to count the pulses supplied by the piezoelectric element (s). A liquid crystal display shows the number of pulses counted at any time.

The microcomputer consists of the integrated circuit 18 of the LC 5732 type from SANYO of 4 bits programmed by mask.

This CMOS technology achieves very low current consumption. This integrated circuit and a few others from its family lend themselves best to the application.

The circuit does not have an on-off switch, since the consumption of the system on standby is minimal (of the order of 4 ^ u A). The detector device comprises a clock controlled by quartz. The microcomputer must be stable enough to generate music over the entire operating temperature range.

The motion detector connects directly to one of the entry doors. A circuit composed by a diode and a resistor maintains the input voltage at LC 5732 in an acceptable range. Here, use is made of the input protection diodes, internal to the LC 5732, the currents supplied by the motion detector being low enough not to destroy them. The motion detector provides an AC voltage that resembles the shape of a damped oscillating discharge when struck by the flyweight. To avoid spurious counts (i.e. peaks after the first), the LC 5732 has been programmed, as shown in the diagram in Figure 5, to simulate a monostable multivibrator with a width of 20 millisec pulse. After the detection of the first peak, the input is inactive and does not detect anything for 20 milliseconds, sufficient time long so that the oscillations are damped, below a non-detectable threshold. This hardware simulation technique by software reduces the number of system components, as well as its size and cost.

The multiplex LCD display 15 is controlled by the microcomputer 18. The piezoelectric speaker 22 is attacked by an NPN transistor which is used in saturated mode, as a current amplifier.

The motion detector according to the invention is a paramedical device which teaches how to carry out the correct daily brushing of the teeth. A digital micro-electronic calculator records and adds up the number of tooth brushings required to remove plaque and any harmful substances. A musical sound is the reward for the accomplished duty which signals the anion of correct brushing. The amplitude of a back and forth movement is approximately 3-4 cm.

The length of a jaw or arch is approximately 9-12 cm.

An arch is divided into 8 brushable surfaces

Posterior Anterior Posterior

6. buccal 1. labial 3. buccal 7. occlusal 2. palatal, 4. lingual occlusal

8. palatine 5. palatine, lingual lingual Brushing movements are carried out at an average speed of 4 movements per second, resulting in 400 movements in 100 seconds.

To remove harmful substances, brush

25 times a surface. The anatomical shape of the teeth requires horizontal, vertical and diagonal brushing.

The number of 400 strokes currently used is based on a statistical measurement in a hospital environment with visual and chemical control (400 = 25 brush strokes x 8 planes x 2 perpendicular directions).

For more precise control, each 25th movement is signaled to allow the user to change the brushing plan. These brushing plans are indicated by a figure.

The purpose of the program represented by the diagram in FIG. 5 is to count and record the pulses supplied by the piezoelectric motion detector. The program uses three counters: a motion counter, a standby counter and a melody counter. If the 400 stroke threshold is reached, one. Music generation subroutine is executed. At the end of the music, the system goes into a waiting state during which the display 15 is off, so as to reduce consumption to a minimum. The register "melody counter" is initialized to 1 when the power is turned on for the first time. This register is incremented after each brushing finished, when the music sounds. If the value contained in this register is greater than 9, it is reset to 1, since there are nine different melodies in this embodiment of the invention. When the device has been idle for more than a minute, that is, the movement does not send a signal, the system goes into the standby state to avoid wasting battery power, until the next start.

The program is resident in ROM, as well as the melody tables. There are 9. The melody counter registers have a length of 4 bits, the movement counter has a length of 12 bits, the inactivity counter has a length of 16 bits. The word length of LC 5732 is 4 bits. -

It should be noted that the parameters of 400 and 25 brush strokes mentioned above are completely arbitrary and can be changed as required.

EXAMPLE 2

Tennis. The detector (s) can be incorporated or adapted in or on the racket; they can also be fixed on the player's body, for example on the player's active wrist, possibly another point on the player's body, for example on the ankle if the number of steps has to be counted.

One, two or more than two groups of sensors can be used on the racket, each group of sensors comprising at least two sensors of different sensitivities such that the first sensor will record the number of movements of the player's arm, whether the ball is caught or not by him, while the second sensor, less sensitive, will only record the number of balls returned to the opponent.

Filtering performed on the electrical or mechanical signal provided by the sensor makes it possible to select fast or slow responses. This filtering can also be performed by appropriate software when using a microcomputer.

Accelerometers, for example quartz, delivering a linear signal quantifiable by an analog to digital converter (analog to digital eonverter), can, using a suitably programmed microcomputer, be used to study the different constraints (stresses), accelerations and shocks of joints, bones and limbs. This kind of study interests sports medicine. Intensive training can also use these devices to quantify efforts and be alerted if certain limits are exceeded.

The use of photoelectric cells, accelerometers and quartz sensors, piezoelectric pellets in particular, makes it possible to achieve a wide range of sensitivities, to lighten the devices and to increase the robustness of the embodiments.

EXAMPLE 3

The sports. The invention is of interest to both athletes and their trainers, making it possible to measure the effort and therefore to control it; the sensors alone or the entire device can, in the case of cycling, be attached to the cyclist's leg or to the pedal of the bicycle.

For other sports such as swimming, jogging, fencing, boxing, rowing and in general any sport operating the limbs, the invention makes it possible to measure the effort by counting the number of movements and by an audible or other signal, to allow some to continue their effort until the signal sounds. while for the others, he will inform them that the effort not to be exceeded has been reached. For convalescents, such information is useful, even essential, and, in addition, an audible signal accompanied by a light signal which may be flashing, can facilitate the monitoring of patients by medical and hospital staff.

It is obvious that the invention is not limited to the examples described above and that many modifications can be made to the type, number, shapes and dimensions of the elements involved in its production, without going beyond the ambit of the following claims.

Claims

1. Piezoelectric detector (20) of movements of a support on which it is fixed, comprising at least one piezoelectric element (26, 27) provided with electrodes (28) and integral with a closed enclosure (31 ) and a counterweight (25) movably enclosed in said enclosure (31), counterweight (25) which, when moving, emits shocks which are transmitted to the piezoelectric element (24) and produces electrical pulses on the electrodes of the latter, characterized in that the piezoelectric element or elements (26, 27) are fixed inside the enclosure (31) and receive the impact of the counterweight (25).

2. Piezoelectric detector according to claim 1, characterized in that it is of the type used in a piezoelectric speaker.

3. Piezoelectric detector according to claim 1 or 2, characterized in that the piezoelectric element (26, 27) constitutes a part of the enclosure.

4. Piezoelectric detector according to any one of the preceding claims, comprising an apparatus for recording the detected movements, characterized in that it consists of a microcomputer (18) of the LC 5732 type.

5. Piezoelectric detector, characterized in that the piezoelectric element (26, 27) is a piezoelectric wafer (24) as used in piezoelectric speakers, including a ceramic element (29 ) is notched and the brass support (30) is folded at right angles so as to form two sensitive elements (26, 27) at right angles.

6. Toothbrush comprising a piezoelectric detector according to any one of the preceding claims.