HK1113291B - Element displaying a band tightening tension, in particular of a portable device wristband - Google Patents

Description

Element for indicating the tightening tension of a strap, in particular for a wristband for portable devices

Technical Field

The invention relates to a fastening strap comprising at least a first and a second free end portion and means for fastening and adjusting the length of the strap.

Generally, a belt of this type may be, for example, a holding strap or a flat belt for fixing a number of objects to each other.

Preferably, the invention relates to a band embodied as a strap or wrist band for fixing a portable device, such as a watch, on the arm of a user.

Background

Many wristbands or straps for portable devices, in particular watches, known from the prior art comply with the above definition.

However, in the case of a watch with multiple functions, for example when said watch has a pulse meter which uses sensors located at the back cover of the case and which must be in close contact with the wearer's wrist, the proper tightness of the band must be ensured when the measurement is carried out and this tightness must be maintained throughout the operation of the pulse meter. In fact, since such devices generally perform a plurality of operations, such as calculating an average value using the pulse values measured during a given time, it must be possible to ensure that no interruption of the measurement occurs, leading to an error in the average value, so that the displayed value is indeed representative of the result obtained during the given time.

Therefore, it is necessary to be able to adjust the tightness of the band of the wearer's wrist accurately, so as to place the watch in a good pulse-measuring condition even under difficult working conditions, for example during a race in which the wrist band is subjected to considerable vibrations and oscillations.

U.S. patent No.6,529,754B 2, issued on 3/4/2003 to Seiko Epson corporation, provides a pulse meter including a wristband capable of solving the above problems because it includes an elastically variable region along its periphery. This document provides, by way of example, a particular embodiment in which the wristband comprises two main rigid parts and two links fixed to the rigid parts and having an elasticity value higher than that of the rigid parts.

Due to the presence of these additional highly elastic links, the watch case is still pressed against the wrist even during significant movements, in particular rotations, of the user's wrist.

However, this solution does not provide means for indicating to the wearer of the pulse meter whether the wrist strap is sufficiently tensioned to ensure that the watch case is properly pressed against its wrist and thus to an appropriate level of measurement accuracy. In fact, this patent states that the wearer of the disclosed pulse meter must tension his wrist strap to feel an excessive squeezing sensation similar to that experienced when wearing a conventional watch.

Disclosure of Invention

The object of the present invention is to overcome the above-mentioned drawbacks of the prior art by proposing a fastening strap which provides its user with data about the fastening tension (tightening force) of the strap, in particular in an intuitively readable way indicating when this fastening tension is suitable for the respective use state.

The invention therefore relates to a fastening strip of the above-mentioned type, characterized in that it comprises, on the one hand, an element indicating the fastening tension, which element is capable of assuming a specific visual configuration (state) recognizable by the user for indicating that the value of the tension exerted on the strip is substantially equal to a predetermined value. Preferably, the indicator element comprises an elastically deformable portion bounded by first and second rigid end portions.

Preferably, the belt according to the invention comprises a main portion, while the tightening tension indicator element is a link whose rigid end has means for fixing (attaching) to the main portion. Preferably, the deformable portion of the link comprises at least one hole which is movable or deformable in response to a change in the tightening tension of the belt to allow a certain marking to be revealed when the tightening tension is of sufficient value. Alternatively, the aperture may have a first shape when at rest (at rest) and deform as the tightening tension increases so as to form a second predetermined shape when the tightening tension reaches or exceeds a desired value.

In a preferred embodiment, the strap fastening and length adjustment means comprises means for adjusting the length in a continuous manner.

Owing to these features, when the strap according to the invention is implemented, for example, in the form of a retaining strap (strapping), and is used for fixing fragile or deformable objects, its fastening tension can be adjusted precisely to ensure that the objects are held properly without any damage.

Furthermore, according to a preferred application of the invention, the band is embodied as a wrist band to allow the user to wear the multifunction watch-type device on the wrist. The advantages of a wrist band that meets the above characteristics will be more evident when the band is used in a watch that includes in particular the function of measuring physiological data of the wearer, in particular the function of a pulsometer, which measures by optical means. In fact, in this case, the above-mentioned features enable the wearer of the watch to adjust precisely the tightening tension of the wristband to ensure a high quality measurement, without the uncomfortable feeling of squeezing his wrist.

Drawings

Other characteristics and advantages of the invention will appear more clearly from the following detailed description, given by way of non-limiting example, when read in conjunction with the accompanying drawings. In the drawings:

figure 1 shows a schematic perspective view of a fastening strip according to a first preferred embodiment of the invention;

FIG. 2a shows a partial cross-section of a first configuration of the belt shown in FIG. 1;

FIG. 2b shows a section similar to the view of FIG. 2a, with the belt in a different configuration;

fig. 3 shows a schematic perspective view of one part of a portable device provided with a strap according to a second preferred embodiment of the invention;

FIG. 4 is a view similar to FIG. 3, showing a portable device provided with a strap in accordance with a third preferred embodiment of the present invention;

FIG. 5 is similar to FIG. 4 and shows the portable device when the strap is subjected to a tension substantially equal to a predetermined value;

fig. 6 shows a fastened tension indicator element attached to the portable device of fig. 4 in a longitudinal sectional view.

Detailed Description

Figures 1, 2a and 2b show a fastening strip according to a first general embodiment of the invention.

Fig. 1 shows a self-tightening fastening strip 1. The belt 1 comprises a first main portion 2 having two free ends 3 and 4 connected by a belt fastening and length adjustment device.

The strap fastening and length adjustment means may be implemented in a number of ways known in the art. A preferred means is shown here in a schematic way, in the form of a buckle 5 fixed to the first end 3 of the belt 1, for example by sewing. The second end 4 passes through the buckle 5 and is folded back on itself, provided with means for holding the second end firmly on the main part-even if the length of the strap 1 is fixed in this position. By way of example, as shown in figure 1, on the end portion 4 of the belt and on the area adjacent to it in the main portion, there is distributed in a suitable manner a complementary hook-and-loop system, for example with the trade name "Velcro".

Any known fastening system suitable for implementing the present invention can be employed without difficulty by those skilled in the art. It must be noted, however, that in the practice of the invention, it is preferable to use, for the means for fastening the belt and adjusting the length of the belt 1, specific means which allow the belt length to be adjusted continuously. Another example of a fastening and adjustment system of the type that may be mentioned in a schematic way is a fastening buckle used on an aircraft safety belt, which fastening buckle is fixed to a first end of the belt and locks a second end of the belt by pressing together. Of course, the implementation of the invention is advantageous compared to the known devices of the prior art, even in the case where the strap fastening and length adjustment means act in a discontinuous manner.

The main portion 2 of the belt can be made of any material that is both flexible and slightly elastic, such as leather, non-deformable natural or synthetic fabric, or even a plastic material with a lower elasticity, such as polyurethane.

Furthermore, the belt 1 comprises an additional portion 6 shorter than the main portion 2. The manner in which the additional portion 6 is arranged along the circumference of the belt 1 is generally not important, but may be important in certain applications. Thus, in the case of the embodiment shown in fig. 1, the additional portion 6 is shown at a distance from the end 3 of the belt.

The attachment means for joining the additional portion 6 to the circumference of the main portion 2 of the belt 1 are more clearly visible in figures 2a and 2b and will be analyzed in more detail hereinafter.

An optional decorative element 7 for masking the means used to connect the additional portion 6 to the main portion 2 is shown in a schematic way. These decorative elements 7 can be made of any suitable material, for example conventional plastic, and can advantageously be used for attaching the trademark of the producer of the illustrated tape 1.

In order to perform the function of indicating the tightening tension of the belt, the attachment portion 6 comprises a central portion 8 which is highly elastic, in particular in the longitudinal direction of the belt 1. Furthermore, the central portion 8 has a special shape for promoting its deformation in the longitudinal direction of the belt 1, i.e. a lateral recess 9.

Furthermore, the central portion 8 is provided with a hole 10 in its centre, the function of which hole 10 will be explained in the following detailed description in relation to fig. 2a and 2 b. In a preferred and non-limiting manner, the shape of the hole 10 in its rest configuration is circular as shown in fig. 1 and allows the appearance of a surface 11 having predetermined structural features (textures), for example a predetermined colour.

Fig. 2a shows a partial cross-section of the belt 1 of the configuration shown in fig. 1, taken through a plane traversing the middle of the belt and extending in the longitudinal direction of the belt.

According to the preferred embodiment shown, the additional portion 6 comprises two rigid end portions 20 and 21 located on either side of the elastic central portion 8. Each of these two rigid ends 20, 21 has a groove 22 (visible in fig. 3) of substantially rectangular shape to cooperate with the means for attaching the main portion 2. Each of the parts of the main portion 2 connected to the additional portion 6 is divided into two end portions 23, which are symmetrical with respect to the median plane of the belt and each comprise a small frame 24 made of rigid plastic or metal, which frame 24 can be sewn onto or into the respective end portion 23. Each frame 24 is shaped and dimensioned to allow it to be inserted into the groove 22 of the corresponding rigid end 20, 21 of the additional part. Preferably, at each rigid end 20, 21 of the additional portion 6, said two symmetrical ends 23 are mutually sewn at least laterally and possibly through the respective rigid end 20, 21, so as to retain each of the frames 24 securely in its groove 22. This construction ensures that the main and additional parts of the belt 1 are effectively and reliably connected together. Furthermore, it should be noted that such a connection means also increases the rigidity of the two ends 20, 21.

The decorative element 7 covers the connecting means of the main part and the additional part, i.e. the frame 24 and the seam, on the outside of the belt, i.e. the side of the belt that is visible when the belt is in use.

According to the embodiment shown in a schematic way, the additional portion 6 has a central cavity 25 of parallelepiped shape which houses a plate 26 of complementary shape. The plate 26 is preferably made of a rigid material and can be provided in the additional portion 6 by overmoulding. The first side 27 of the plate 26 is fixed to the rigid end 20, thanks to the provision of a portion of a seam 28 that secures the two symmetrical ends 23 to each other, and thanks to the provision of a block 29 that passes through the two symmetrical ends 23 and the plate 26. Of course, the invention is not limited to the means just described for fixing the first side 27 of the plate 26, which means can be implemented independently of one another or can be made in a conventional manner by gluing the first side 27 of the plate to the rigid end 20 of the attachment portion 6.

Two successive zones of the plate in the longitudinal direction of the belt have been schematically shown, a first zone corresponding to the first side 27 and a second zone 30 extending from the end of the first zone to the end of the plate on the side of the rigid end portion 21. The first area has a part 11 visible through the hole 10 in the central portion 8. Preferably, the two regions 27, 30 have different colors, such as red and green, which are easily distinguishable from each other.

It will be noted in fig. 2a that said second region 30 is not visible through the hole 10, the length of this hole 10 in the longitudinal direction at rest being denoted L1. Thus, in this configuration of the belt, the user can see the red patch through the aperture 10.

When the strap 1 is tightened, for example in order to hold objects together, as shown in fig. 2b, the tension to which the additional part is subjected increases, causing its elastic central portion 8 to deform. This deformation of the central portion 8 causes a deformation, in particular a stretching, of the holes 10, so that said holes 10 have a length in the longitudinal direction of the belt, denoted L2, L2 being greater than L1.

It is also evident from fig. 2b that the hole 10, in addition to the deformation, also follows a deformation over a greater extent of the central portion 8, in particular until the second region 30 of the plate 26 is locally visible. It should be noted in fact that, since the additional portion 6 has the configuration described previously, the plate 26 does not move or deform in response to an increase in the tightening tension of the belt 1. Preferably, if the user at this stage sees a green appearance after the initial red, this indicates that the tightening tension of the strap has reached a sufficiently large value within the current range of use of the strap 1.

Thus, for the intended application of the belt 1, the person skilled in the art knows how best to have the fastening tension when the belt is tensioned, and they can therefore provide the necessary deformation of said hole 10 to allow the second zone 30 of the plate 26 to emerge and indicate to the user that the tension is sufficient. Thus, when the strap is used to hold fragile objects together, these features can be adjusted during manufacture to ensure that the necessary and sufficient tension is indicated to the user to achieve this without damaging the objects.

Of course, the indication of fastening tension according to the invention is not limited to the use of color-changeable elements as just described. The change in the display color or in the broadest sense of the structural features can be simply defined, the basic principle being that at least an appearance recognizable by the user is obtained when the necessary tightening tension is reached.

Fig. 3 shows a preferred embodiment of a band according to the invention as a wrist band allowing a portable device 40 of the wristwatch type to be worn on the wrist. Only a portion of the belt according to the present embodiment is shown to make certain details of its construction apparent.

The main part of the belt (not shown) described here is divided into two similar belt sections, between which the casing 41 of the portable electronic device 40 is arranged.

According to a preferred embodiment, the portable electronic device is a sphygmometer comprising means for measuring the pulse of the wearer and electronic circuits for processing the measurement results and control display means for displaying the result obtained. Such electronic devices are known in the art and will not be described in detail here, since they do not directly contribute to the invention. As an example, the person skilled in the art can refer to the teaching of the US patent mentioned in the introduction to devise an electronic device with the function of measuring the heartbeat of a wearer, in particular using a measuring device of the optical type.

Since the belt tightening and adjusting device can be implemented in a manner similar to that described in detail with reference to fig. 1, it is not shown in fig. 3. Alternatively, a conventional wristband fastening device having a buckle and a tongue fitting into a hole may be used, which may incorporate a special device for adjusting the length of the wristband as disclosed in EP patent application No. 1588640 filed 4/23 of 2004 by the Swatch Group management services AG. Of course, any other known fastening and adjustment system commensurate with the embodiments of the strap described herein may be employed by those skilled in the art without departing from the scope of the present invention.

Fig. 3 shows a preferred variant according to which the belt comprises two identical elements 42 for indicating the tightening tension of the belt, arranged on both sides of a shell 41.

Each of these elements 42 comprises two rigid ends 43 and 44, of which one end 43 is connected to the shell 41. To this end, the shell comprises four horns 45 through which cylindrical holes 46 are provided, the rigid end 43 having a complementary shape adapted to fit between the horns 45. In addition, the rigid end 43 includes a cylindrical bore (not visible) disposed in alignment with the bore 46, and a rod 47 for securing the horn and the rigid end 43 to one another.

The second rigid end 44 is similar to the rigid end 21 described in the detailed description of the previous embodiment with respect to fig. 2 a. The rigid end 44 contains a substantially rectangular shaped recess 22, the recess 22 being for receiving a rigid frame secured to a corresponding wristband strand (not shown). As noted above, the belt segments are preferably secured to the indicator element or link 42 by stitching.

The central portion 48 of each indicator element 42 is elastically deformable, since the elasticity of said central portion is greater than the elasticity of the rigid end portions 43, 44. The elasticity of the central portion 48 is due in particular to its unique structure. It should be noted in practice that this central portion 48 contains a lateral recess 9, said lateral recess 9 being identical to that described in relation to fig. 1 and serving to cause the indicator element 42 to deform longitudinally in response to an increase in the fastening tension between the two rigid end portions.

Further, the center portion 48 includes a plurality of through holes 49 each having a substantially elliptical shape. Thus, as the tension applied to the wristband increases, the central portion 48 of each link 42 deforms and thereby causes the aperture 49 to deform.

With certain parameters, such as the exact shape of the aperture 49 and the change in the elastic properties of the central portion 48, which can be easily adjusted by one skilled in the art, any type of appearance recognizable by the user can be defined for displaying a predetermined wristband fastening tension.

In particular, at the base of the hole 49 shown in fig. 3, the nature of each link 42 may be defined such that the hole is deformed to have a circular or rhomboid shape for a predetermined tightening tension value.

The person skilled in the art will not encounter any particular difficulty in selecting the material of the links 42 and adjusting the shape of said holes 49 to obtain a predetermined appearance recognizable by the user when the tightening tension is equal to the optimum value related to the application.

Alternatively, a structure may be provided having one or more holes similar to hole 49 that are configured to deform as the fastening tension of the strap increases to form an indication of when the fastening tension value is substantially equal to the desired value.

This solution advantageously enables the producer of the belt or of the apparatus to attach its trademark in an initial manner to its product.

The arrangement shown in fig. 3 corresponds to a preferred application of the belt according to the invention and should not be considered as limiting. In fact, the wristband as described above has particular advantages when it is applied to equipment having a pulsometer function for measuring with an optical type measuring device. The measurement device typically includes a light beam transmitter and a receiver for at least partially receiving the transmitted light beam after it has propagated into the wearer's body. Thus, the measurement results are susceptible to light sources outside the device, in particular ambient light. As such, it is important that the housing of the portable device be properly pressed against the skin of the wearer. For this reason, the fastening tension must have a minimum value such that ambient light does not disturb the measurement. The wristband, partially shown in fig. 3, therefore not only presses the shell properly against the wrist of the wearer even when the latter is moved, due to the elasticity of the links 42 directly connected to the shell, but also indicates to the wearer when the tightening tension is sufficient to ensure a high degree of measurement reliability. Such an indicating characteristic advantageously allows the wearer to adjust the gripping tension accurately to such an extent that the (wearing) comfort of the device is not affected.

According to a variant, a combination of strap-fastened tension indicator elements according to the two embodiments described above may be provided. The fastening tension indicator element as shown in fig. 3 may comprise a cavity similar to the cavity 25 in fig. 2a, which receives a plate similar to the plate 26 and serves as a reference frame. In this case, the plate comprises on its face 11 a pattern or marking corresponding to the position and shape of the hole 49 when said hole 49 is deformed in response to the desired value of the belt tightening tension. This variant advantageously allows the wearer to recognize the situation in which the hole 49 is easier to reach the desired shape than in the embodiment shown in fig. 3, but with a substantially more compact structure.

According to a further variant, the holes 49 may be omitted leaving the central portion 48 intact, and the holes 49 replaced by a simple pattern provided on the visible surface of the central portion 48. The pattern may be formed in the bulk of the central elastic portion or printed on its surface in any suitable manner. The mechanical properties of the elastic central portion can then be adapted to make a pattern which can have any predetermined shape recognizable by the user from any shape in the rest position of the central portion when the belt fastening tension reaches a predetermined value. In a similar manner to that described above, the resulting pattern may be, for example, a sheet, a diamond, or form a recognizable predetermined inscription (inscription, signature).

Within the scope of this variant, the pattern may also be carried by an additional support element fixed on the elastic central portion, for example, without limitation, by a thin silicon wafer repeatedly shaped on the elastic central portion or vice versa.

According to a third embodiment of the invention illustrated in fig. 4 to 6, as with the portable electronic device 40 in fig. 3, a fastening tension indicator element or indicator element 42 is provided on one end of the wristband 1 to be secured to the case 41, and the indicator element 42 is of the same type of construction as that described in fig. 1, wherein the plate is replaced by a longitudinal stem 50 which extends into the layer of the indicator element 42 and is partially visible through a display aperture 52 provided in the central portion 48 of the indicator element 42.

For the description of the third embodiment, similar elements or elements having the same functions as those used in the previous embodiments will be denoted by the same reference numerals.

According to this third embodiment, a stem 50 forming a reference element for indicating the gripping tension is fixed to the shell 41 with a corresponding rigid end 42 of the indicator element 42, the connection of said rigid end 43 to the shell 41 being the same as described in the embodiment with reference to fig. 3. For fixation, the stem 50 comprises at its fixed end 54 a transverse hole 56 for the passage of the rod 47, so that the stem 50 is held on the housing 41 by the rod 47 with the rigid end 43.

The display aperture 52 has in this embodiment the shape of a longitudinal slot having a width substantially equal to the diameter of the stem 50 so as to allow, in the rest configuration of the indicator element 42, the appearance of a first section 58 of the stem 50, this first section 58 being referred to as the intermediate section and having a predetermined colour or structural characteristic. The stem 50 includes a second section 60 and a third section 62 on a side thereof opposite the fixed end 54, the second section 60 being adjacent the first section 58 and having a different color and structural characteristics than the first section 58, and the third section 62 being adjacent the second section 60 and having a different color and structural characteristics than the second section 60.

In the rest configuration of the indicator element 42, the second and third segments 60, 62 are not visible in the display aperture 52 due to being received within complementary cylindrical apertures 64 formed on the second rigid end 44 of the indicator element 42. The second and third segments are thus concealed under a portion of the wristband 1.

In the foregoing embodiment, because the elasticity of the central portion 48 of the indicator element 42 is greater than the elasticity of the rigid end portions 43, 44, the central portion 48 is elastically deformable. Thus, the central portion 48 is here undulated to give it a sinusoidal profile and to provide a controlled elasticity which facilitates the longitudinal deformation of the indicator element 42 in response to an increase in the tension experienced between the two rigid end portions 43, 44.

When the amount of tension applied to the bracelet 1 is less than a predetermined value, only the intermediate segment 58 is visible in the display aperture 52-as shown in figures 4 and 6-the user therefore knows that the bracelet 1 is not sufficiently tensioned for its intended application.

When the amount of tension applied to the wristband 1 reaches or exceeds a predetermined value, as shown in FIG. 5, a second section 60, which is green for example, appears in the display aperture 52, indicating to the user that the wristband is sufficiently tensioned for the current application.

Advantageously, the third segment 62, for example red, will appear when the value of the tension applied to the bracelet 1 is greater than or equal to another predetermined value corresponding to an excess tension of the bracelet. This embodiment thus gives a warning to the user when the wristband is too tight, to prevent the user from being injured by the wristband 1 and/or from causing accelerated wear of the wristband 1.

Preferably, the stem 50 is sufficiently flexible to be able to follow the curvature of the indicator element 42 as the bracelet 1 wears.

According to the embodiment shown here, the indicator element 42 is molded as one piece of plastic material with the respective wristband strand 1. Since the elasticity of the central portion 48 of the indicator element 42 is obtained essentially through its sinusoidal profile, rather than through the actual elasticity of the material forming the indicator element 42, the entire bracelet 1 can be manufactured with the same material, thereby minimizing the production costs of the bracelet 1. Of course, the indicator element 42 can also be produced in the form of an indicator link to be added to the wristband strand 1, as in the exemplary embodiment in fig. 3.

The foregoing description, in particular as regards the structure of the strap fastening and length adjustment device or of the device for connecting the various constituent elements of the strap, corresponds only to a preferred embodiment of the invention and should in no way be considered limiting. Those skilled in the art will not encounter any particular difficulty in adapting the particular characteristics of the belts to their particular requirements, in materials, shapes or dimensions that do not depart from the scope of the invention.

Claims (21)

1. Portable device (40), the portable device (40) comprising a case and a fastening strap (1) performing a wristband function to allow the portable device to be worn, the fastening strap (1) comprising at least a first and a second free end (3, 4) and means (5) for fastening and adjusting the length of the strap, characterized in that the fastening strap comprises a fastening tension indicator element (6, 42) for indicating a fastening tension, the fastening tension indicator element (6, 42) being capable of assuming a specific visible configuration recognizable by a user for a tension value applied to the strap substantially equal to a predetermined value, the fastening tension indicator element (6, 42) comprising at least one elastically deformable portion (8, 48), the deformable portion (8, 48) being formed by a first rigid end (20) of the fastening tension indicator element (6, 42), 43) and a second rigid end portion (21, 44).

2. A portable device according to claim 1, characterised in that the fastening strap comprises at least one main portion (2), the fastening tension indicator element being a link (6, 42) whose rigid end (20, 21, 44) has attachment means (22) for cooperating with suitable attachment means (24) of the main portion (2).

3. A portable device according to claim 1 or 2, characterized in that said deformable portion (48) comprises at least one hole (49), the cross-sectional shape of said hole (49) depending on the value of the tension applied to said strap (1).

4. A portable device according to claim 3, characterized in that said holes (49) have a circular or rhombic cross-section or define a inscription when the value of the tension applied to the strap is substantially equal to said predetermined value.

5. A portable device according to claim 3, characterized in that said fastening tension indicator element (42) further comprises reference means (26) fixed on one (20) of said first and second rigid ends and carrying at least one pattern arranged opposite said hole and having the same shape as said hole when the value of the tension applied to said strap is substantially equal to said predetermined value.

6. A portable device according to claim 1 or 2, characterized in that the deformable portion (48) comprises at least one pattern whose shape depends on the value of the tension applied to the belt (1).

7. A portable device according to claim 6, wherein the pattern is circular or diamond shaped or defines a inscription when the value of the tension applied to the strap is substantially equal to the predetermined value.

8. A portable device according to claim 1 or 2, characterized in that the deformable portion (8) comprises at least one hole (10), the position of the hole (10) with respect to at least one of the rigid ends (20) depending on the value of the fastening tension of the strap (1); the tightening tension indicator element (6) further comprises reference means (26, 27, 30) fixed to and spaced from said at least one end (20) so as to have a predetermined specific visual appearance for a value of tension applied to the belt substantially equal to a predetermined value.

9. A portable device according to claim 8, characterized in that the reference means comprise two portions (27, 30) having respectively different colours, said two portions (27, 30) being positioned extending mutually in the longitudinal direction of the belt.

10. A portable device according to claim 1, wherein said deformable portion (48) comprises a hole (52), said fastening tension indicator (42) element further comprising reference means formed by a longitudinal stem (50) fixed on one (43) of said first and second rigid ends and slidingly housed in the other (44) of said first and second rigid ends, the stem (50) comprising a first section (58) having a first colour or structural characteristic and a second section (60) having a second colour or structural characteristic, the second section (60) being arranged on the opposite side to said one (43) of said first and second rigid ends for fixing, said second section (60) being hidden under a portion of said strap when the value of the tension applied to said strap is lower than a predetermined value, the second section (60) is visible in the hole (52) when the value of the tension applied to the belt is substantially equal to a predetermined value.

11. The portable device of claim 10, wherein the stem (50) includes a third segment (62) having a different color or structural characteristic than the second segment (60), the third segment (62) extending from a side of the second segment (60) opposite the first segment (58), the third segment (62) being visible in the aperture (52) when the amount of tension applied to the strap is greater than or equal to a predetermined value corresponding to an excess strap tension.

12. A portable device according to claim 1 or 2, characterized in that said means (5) for fastening and adjusting the length of the strap comprise means for continuously adjusting the length.

13. Portable device (40) according to claim 1, characterized in that a first of said free ends of said strap comprises means for cooperating with first suitable means of a first side of said case, a second of said free ends being adapted to cooperate with said means for fastening and adjusting the length of said strap, which means comprise means for cooperating with second suitable means of a second side of said case.

14. A portable device according to claim 13, characterised in that said fastening tension indicator element is in the form of a link (42) whose first rigid end (43) carries attachment means for cooperating with first suitable means (45, 46, 47) of the casing.

15. Portable device (40) according to claim 1 or 2, characterized in that the strap comprises at least two strap segments which are arranged on both sides of the housing and each carry one of the free ends, at least one of the two strap segments comprising a fastening tension indicator element (42) indicating a fastening tension of the strap.

16. A portable device according to claim 15, characterised in that said free end is connected to said means for fastening and adjusting the length of said strap; at least one fastening tension indicator element (42) is provided between one of the free ends and the shell (41).

17. A portable device according to claim 16, characterized in that the at least one fastening tension indicator element (42) is directly connected to the housing (41).

18. A portable device according to claim 17, characterized in that the at least one fastening tension indicator element (42) comprises two fastening tension indicator elements.

19. Portable device (40) according to claim 10 or 11, characterized in that one (43) of said first and second rigid ends carries attachment means for cooperating with suitable means (45, 46, 47) of said casing (41); the stem (50) cooperates with suitable means (45, 46, 47) of the shell (41) to be fixed to the shell (41).

20. A portable device according to claim 13 or 14, characterized in that it comprises means incorporated in said housing (41) for measuring physiological data of the wearer of the device.

21. A portable device according to claim 20, characterized in that it comprises a pulsometer function, the optical measuring means being arranged at the side of the housing that is to be pressed against the arm of the user.