EP1730479A1

EP1730479A1 - Electronic person-weighting device

Info

Publication number: EP1730479A1
Application number: EP05744617A
Authority: EP
Inventors: Benoît LINGLIN; Didier Moiret
Original assignee: SEB SA
Current assignee: SEB SA
Priority date: 2004-03-30
Filing date: 2005-03-25
Publication date: 2006-12-13
Also published as: WO2005095905A1; FR2868533A1; FR2868533B1

Abstract

The inventive person- weighting device comprises a plate (1) which is provided with a weight sensor and/or electrodes (2, 3, 4, 5) connected to bioelectrical impedance measuring means and is supported by a base (8) and/or legs (9) and with an electronic card comprising a measuring printed circuit displaying a measured value. According to said invention, at least one electrode and/or weight sensor is directly connected to said electronic card by a rigid connection element comprising one or several lateral blade which produces the pressure contact of the electrode (2, 3, 4, 5) and/or the weight sensor, wherein each blade is connected to a central blade which contacts the electronic card by pressure.

Description

ELECTRONIC SCALE

The present invention relates to a weighing device of the bathroom scale type, in particular of the electronic type comprising strain gauges associated with an electronic measurement circuit delivering a signal which is a function of the weight to be measured. Such a device can advantageously include means for measuring the bioelectric impedance of the body used to estimate the lipid reserves of the body of the individual.

A weighing device in principle comprises a plate capable of receiving the weight to be measured, at least one test body comprising on one of its faces strain gauges, one of the ends of this body being connected to the plate and the other to a base or foot of the device intended to rest on a flat surface. The two ends of this body are embedded in the plate and the base or foot and delimit a bar of an elastic material supporting the strain gauges and deformable essentially by bending under the effect of the weight to be weighed. The gauges are connected, by flexible conductors welded to the connection points of the gauges, to an electronic measurement circuit which converts the deformations undergone by the gauges into electrical signals and transforms them into digital values corresponding to the measured weight. Such a weight receiving plate can, moreover, be provided with electrodes and with an electronic circuit for measuring the bioelectric impedance of the body and therefore the device can, moreover, estimate the body composition of the body. who stands on such a tray.

Such a device for measuring body composition is described in document FR 2 830 740 in the name of the applicant. This device includes a measurement platform supported by four weight sensors connected to a common electrical circuit and to a display. The circuit also includes an electronic module intended to measure a bioelectric impedance, as well as a source of electrical energy intended to generate a variable electrical signal which crosses the body of the individual. The signal is sent through the body of the individual by two excitation electrodes and the resulting signal is measured across two measurement electrodes. To make such an apparatus, electrodes are used in the form of steel plates, each comprising a connection wire welded to its lower surface. These electrodes are glued with double-sided adhesive tape to the upper face of the weighing pan. The weight sensors are attached to the bottom surface of the weighing pan, which also rests on the feet of the device. A finishing plate is added to the electrodes and keeps them in place on the plate. The electrode connection wires follow a certain route between reinforcing ribs located in the lower part of the weighing pan and must be held in place by fixing lugs. The assembly thus produced is then connected to the calculation and display unit by the terminal connector of the connection wires. Operating satisfactorily, such an apparatus however has a complex structure and requires significant assembly time for all of its components.

Document EP 1 212 981 describes an impedance meter scale comprising an upper resin plate with overmolded electrodes. The four electrodes are first molded from a conductive resin, the connection cables being embedded in the resin. The plate is then formed by overmolding the electrodes with an electrically insulating part. A display is fixed to this plate, the assembly then being mounted on a lower metal support. The electrode connection cables are soldered to a central electronic plate. Such a device certainly has a smaller number of components and is easier to assemble, but it has the drawback of requiring considerable time and labor to make the connections from the electrodes to the electrical circuit of the apparatus.

Another impedance scale is described in document EP 1 336 826 where the apparatus comprises an upper glass plate on which are deposited, by a thin layer deposition technique, conductive tracks forming the electrodes and their connections. Such a deposit is not only expensive, but it is also very weak, the wear by abrasion of a conductive track which can render the device non-functional. In addition, the numerous conductive tracks deposited on the surface of the plate converge together towards an area greater than eight conductive tabs, which implies an adequate and fairly complex connection.

The object of the invention is to remedy these drawbacks at least in part and to propose an electronic scale, in particular of the impedancemetry type, comprising a reduced number of components and a simplified manufacturing process, for assembly time. and reduced labor costs.

Another object of the invention is to propose an electronic bathroom scale, in particular of the type with low impedance measurement, which is of a simple and robust construction, while being reliable in operation and which can be industrialized for a lower cost. .

These aims are achieved with an electronic bathroom scale, comprising a plate fitted with weight sensors and / or electrodes connected to means for measuring the bioelectric impedance, supported by a base and / or by feet, as well as '' an electronic card comprising an electronic circuit for measuring and displaying the measured value, characterized in that at least one of the electrodes and / or one of the weight sensors is / are directly connected to said electronic card by a rigid connection piece comprising one or more lateral lamella (s) which makes (s) pressure contact at the level of the electrode and / or the weight sensor, each lateral lamella being connected to a central strip which makes pressure contact with the electronic card.

Such a rigid connection piece directly connects an electrode and / or a weight sensor (in particular its electrical circuit comprising the strain gauges applied to the bending bar) to the electronic card. This connection piece then includes contacts which are of the non-welded type, which are easier to implement. These contacts are made by flexible strips which make contact by pressure or by simple pressing on the one hand, at the point of contact with the electrode and / or with the connections of the electrical circuit with strain gauges of the weight sensor, and on the other hand, with the connection tracks of the electronic card. The connection piece is rigid enough to allow good mechanical strength of the flexible end strips.

A first flexible strip of such a connection piece comes directly into contact with the conductive part of the electrodes, the latter being able to be produced in the form of metal plates, or blocks of conductive resin, or by a conductive deposit (in a thin layer or thick layer) on an insulating support. This first flexible strip is electrically connected to a second flexible strip which is supported on the connection tracks of the electronic card.

Such a rigid connection part can then be easily integrated into any construction of electronic scale or impedance scale, it achieves a connection by simple pressing between two distant parts and / or offset in height of the device, without soldering or specific connectors are required. This makes it possible to significantly reduce the assembly time of such an apparatus, the assembly process of such an apparatus easily lending itself to automation, the manufacturing costs then being greatly reduced.

Advantageously, said lateral and central lamellae are produced at the two ends of a metal strip.

It could, of course, have been envisaged to arrange the strips at the ends of a rigid piece of plastic material through which passes a connection cable connecting the two end strips. However, it is preferred to use, for reasons of simplicity and robustness, a simple metal strip the ends of which are bent for more flexibility at the level of the contacts, this bar possibly being able to be stiffened in its central part. Usefully, said connection piece connects at least two electrodes to the electronic card.

An impedance scale has at least two electrodes which are then connected to the electronic card by a common connection piece, which further simplifies the construction and mounting of the device.

In a preferred embodiment of the invention, the device comprises four electrodes, all four being connected to the electronic card by a common connection part.

Advantageously, said connection piece comprises one or more metal strips in a sheath made of an electrically insulating material.

Such a sheath of electrically insulating material ensures the insulation of the conductors with respect to each other or from the other components of the device, and at the same time gives more rigidity and good mechanical strength of the assembly. .

Usefully, said connecting piece comprises two metal bands in the shape of an inverted F overmolded together with said sheath, their longest sides facing each other.

Thus, the two arms of an F-shaped part provide the connections with two adjacent electrodes, the longest side leading to the central electronic card. Two F-shaped pieces arranged side by side in the same plane can thus make the connections of the four electrodes with the electronic card, these two pieces then being easily made integral by overmolding with a protective sheath made of an electrically insulating material. Such a generally flat and thin connection piece can then be mounted inside the housing of a scale without increasing its size. Usefully, two adjacent central lamellae are obtained by cutting a metal strip in the upper part of said connection piece.

This allows for simple separation of the conductive tracks from a simple metal strip. Advantageously, such cutting is carried out after overmolding in order to allow good mechanical strength of the assembly and to avoid the appearance of deformations during the injection of the plastic material.

Preferably, said connection piece is arranged in a recess of shape corresponding to that of the sheath, recess formed in the upper part of a support plate.

This recess allows a rapid positioning and positioning of said connection piece on a support plate. In addition, it makes it possible to compensate for the thickness of the connection piece, thus giving more compactness to the assembly.

Advantageously, said support plate bears on the lower part on weight sensors disposed inside the feet of the device.

Such a support plate is intended to receive the weight of the user, the weight sensors transmitting the signal to a central measurement and display unit.

Preferably, said electrodes are sandwiched between said support plate held by a base in the lower part and flanges in the upper part.

The flanges and the support plate are then held tight, for example by a fixing screw mounting in order to ensure permanent contact of the electrodes with the connection piece. In a variant, the electronic scale of the invention comprises four weight sensors, the connections between the sensors and the electronic card being made by means of a connection piece with four arms, each arm comprising contact strips which rest on the connection tracks of the strain gauge circuit of each sensor and which converge in a central zone of said connection piece provided with strips for connection to the electronic card.

Thus, the connections between the electrical circuits with strain gauges of all the weight sensors and the electronic card are provided by a common connection piece, which further simplifies the construction and mounting of such an apparatus. The electrical circuit of such a sensor can comprise two strain gauges mounted in a half-bridge, and each arm of such a connection piece then comprises three lateral contact strips, the strips of all the arms being able to be held together by a sheath. made of an electrically insulating material.

The invention will be better understood from the study of the embodiments taken without any limitation being implied and illustrated in the appended figures in which:

- Figure 1 is a perspective view of the apparatus of the invention;

- Figure 2 is an exploded view of the apparatus of the invention;

- Figure 3 is a perspective view of a connection plate used with the apparatus of the invention; FIG. 4 is a perspective view of the conductors of the connection plate of FIG. 3.

FIG. 1 illustrates a perspective view of an impedance scale according to the present invention comprising, in the upper part, a plate 1 provided with excitation electrodes 2.3 and measurement electrodes 4.5, as well as a display window 6. Several buttons 7 are arranged next to the display window 6 and are used to navigate in the menu proposed on the display screen, in particular for entering the age value, gender, size, etc., to validate the values entered, to call up a memory, or even to display on the screen a specific type of measured parameter, its history, etc. The tray 1 is closed in the lower part by a base 8 through which pass feet 9 resting on the ground.

Referring to Figure 2, there is the base 8 of generally rectangular shape having holes 11 at the four corners. Feet 9 pass through the orifices 11 while bearing with their upper part on a support plate 12, their lower part being intended to bear on the ground. Each leg 9 contains a weight sensor of the type described in document FR 2 734 050 in the name of the applicant, the leg 9 comprising an interface 10 fixed, for example, by gluing to the support plate 12, one of the zones d support of the weight sensor being fixed by clipping to the interface 10, the other support area coming into contact with the lower part of the foot 9. The contour of the support plate 12 follows that of the base 8, the support plate 12 being rigid enough to support without deforming the weight of the user. Such a support plate is made of an electrically insulating material, for example wood or a rigid plastic material with a thickness of about 20 mm. A cutting 14 is made in the front part of the support plate 12, cutting which is intended to receive an electrical box assembly 15.

The electrical box assembly 15 comprises an electronic card 17 on the lower part of which is fixed a battery box 18, on its upper part being fixed an LCD screen display. The electronic card 17 integrates an ASIC card constituting the electronic control unit of the device, the electronic card 17 comprising connections connecting the ASIC card to the display 19, to the power supply, as well as to a connection zone. 20. The connection area 20 receives, as will be explained below, the connections of the electrodes of the device and those of the common electrical circuit of the weight sensors.

In the central part of the upper face of the support plate is formed a recess 22 in the form of an inverted H intended to receive a connection piece 23 in the form of a lizard with arms apart. The recess 22 has a contour to conical sides and rounded edges to facilitate the orientation and rapid installation of the connection piece 23. The connection piece 23 has, at its lateral ends, four lateral strips 24 and, in its front part, four central strips 25. The central strips 25 are designed to come into contact with the conductive tracks of the connection area 20 of the electronic card 17, while the side strips 24 are intended for direct contact with the electrodes of the device.

A faceplate 27 is affixed to the support plate 12 and forms the mounting base for the electrodes of the device. The front plate 27 has for this purpose, in its front part, two oval protrusions 28, 29 having the same shape and the same dimensions as the excitation electrodes 2, 3, in particular their internal fixing part, and, in its rear part, two circular protrusions 30, 31 having the same shape and the same dimensions as the internal part for fixing the measurement electrodes 4.5. The protrusions 28, 29, 30, 31 each have an orifice 33 through which a lateral strip 24 of the connection piece 23 projects. A light 32 is formed in the central front part of the front plate 27 revealing the screen of the 'display 19 located below. The front plate 27 also comprises, in the lower part of the light 32, openings allowing the passage of the buttons 7 mounted to the electrical box 15.

The device also has four electrodes 2,3,4,5 produced for example in the form of stainless steel plates, which are affixed on the protrusions 28, 29, 30 and 31 of the faceplate 27. The electrodes are held in place by two flanges 34,35 each provided with passage openings 36,37,38,39 revealing the upper surface, of contact with the feet of the user, of the electrodes 2,3,4,5. Each of the electrodes then comes into contact with a lateral strip 24 located below, belonging to the connection piece 23. The flanges 34, 35 are fixed to the base 8 of the device by a screw fixing 41. Several screws 41 are arranged on the periphery of the flanges 34, 35, respectively of the base 8 and thus ensure uniform tightening of the two parts and, consequently, good contact of the electrodes 2, 3, 4, 5 with the lateral strips 24 of the connection piece 23. A display window 6 transparent then completes the front of the device. All the components are thus included inside a closed space of small thickness, ensuring a compact construction of the device.

FIG. 3 illustrates a perspective view of the connection piece 23 comprising four ends forming lateral strips 24 and four central strips 25 in its front part. As best seen in Figure 4, the connecting piece 23 comprises two metal strips 43,44 each having an inverted F shape. The two metal strips 43, 44 are arranged one beside the other, their longest sides facing each other and are held together by a sheath 45 (FIG. 3) made of an electrically insulating material. The metal strips 43, 44 can advantageously be made of copper or stainless steel by being overmolded with the sheath 45 made, it, of a plastic material. After overmolding, cutouts 47 are made in the central front part of each of the metal strips 43,44 in order to separate the conductive tracks leading to the two different electrodes. The end portions forming lateral lamellae 24 are folded upwards and have point contact zones 24 ′ coming into direct contact with the surface of the electrodes situated above. Similarly, the central strips 25 have their end portions folded downwards, each strip having a point contact area 25 ′ which rests on a contact in facing contact in the connection area 20 of the electronic card 17 located above.

Such a connecting piece is quickly installed during assembly of the device and even lends itself to automation of the assembly process. In addition, it guarantees good contact between the electrodes located above and in the lateral part of the plate with an electronic card located in the central part and below said plate, without several delicate operations of welding and checking of the welded contacts being carried out during the industrialization process.

In a variant not shown in the drawings, a connection piece of general shape similar to that of the connection piece 23 could be arranged in the lower part of the support plate 12, the lateral strips being provided to come into contact with the connection points of a circuit with strain gauges screen printed on the bending bar of a weight sensor which is located at the inside of a foot 9 of the device. Each arm of the connection piece should then have three lateral strips each providing a connection at a point on the sensor circuit. All the lateral lamellae are overmolded with a common sheath of a plastic material, and communicate with six central lamellae for connection with the electronic card 17 situated in the central part of the connection part.

Other variants and embodiments can be envisaged without departing from the scope of these claims.

Thus, one could consider using such a connecting piece only in an electronic scale to connect the weight sensors, in particular their circuits to the card or central electronic circuit.

Furthermore, a connection piece of the invention can be used to connect the electrodes to the central electronic card of an impedance scale, which further comprises an additional connection piece that connects these weight sensors to the same card. In an advantageous embodiment, the connection piece of the electrodes and that of the weight sensors are connected together and form a single piece, which makes the implementation of the apparatus even more economical.

In another variant of the invention, one could imagine that the upper plate and the base are kept apart by elastic means and that the connection part makes the contacts of the weight sensors and / or the electrodes with the electronic card only when the user climbs onto the device tray.

Claims

1. Electronic bathroom scale, comprising a plate (1) fitted with weight sensors and / or electrodes (2,3,4,5) connected to means for measuring the bioelectric impedance, supported by a base ( 8) and / or by feet (9), as well as an electronic card (17) comprising an electronic circuit for measuring and displaying the measured value, characterized in that at least one of the electrodes and / or one of the weight sensors is / are directly connected (s) to said electronic card (17) by a rigid connection piece (23) comprising one or more lateral lamella (s) (24) which realizes ( nt) a pressure contact at the electrode (2,3,4,5) and / or the weight sensor, each lateral strip (24) being connected to a central strip (25) which makes a pressure contact with the electronic card (17).

2. Bathroom scale according to claim 1, characterized in that said lateral (24) and central (25) strips are produced at the two ends of a metal strip.

3. Bathroom scale according to one of claims 1 or 2, characterized in that said connecting piece (23) connects at least two electrodes (2,3) to the electronic card (17).

4. Bathroom scale according to one of the preceding claims, characterized in that said connection piece (23) connects the four electrodes (2,3,4,5) to the electronic card (17).

5. Scale according to one of the preceding claims, characterized in that said connecting piece (23) comprises one or more metal strips (43,44) in a sheath (45) made of an electrically insulating material.

6. Bathroom scale according to claim 5, characterized in that said connecting piece comprises two metal bands (43,44) in the shape of an inverted F overmolded together with said sheath (45), their longest sides facing each other.

7. Bathroom scale according to claim 6, characterized in that two adjacent central strips (25) are obtained by cutting (47) made in the upper part of a metal strip (43,44) of said connecting piece ( 23).

8. Scale according to one of claims 5 to 7, characterized in that said connecting piece (23) is disposed in a recess (22) of shape corresponding to that of the sheath (45), recess formed in the upper part of a support plate (12).

9. Bathroom scale according to claim 8, characterized in that said support plate (12) is supported in the lower part on weight sensors disposed inside the feet (9) of the device.

10. Bathroom scale according to claim 9, characterized in that said electrodes (2,3,4,5) are sandwiched between said support plate (12) held by a base in the lower part and flanges (34,35 ) at the top.

11. Bathroom scale according to claim 1, characterized in that said plate comprises four weight sensors, the connections between the sensors and the electronic card being made by means of a connection piece with four arms, each arm comprising contact strips which are supported on the connection tracks of the strain gauge circuit of each sensor and which converge in a central area of said connection piece provided with strips for connection to the electronic card.