WO2007069111A2

WO2007069111A2 - Device for assessing the physical condition of a person

Info

Publication number: WO2007069111A2
Application number: PCT/IB2006/054457
Authority: WO
Inventors: Annelies Goris; Johanna J. Van Herk
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2005-12-15
Filing date: 2006-11-27
Publication date: 2007-06-21
Also published as: WO2007069111A3

Abstract

A device for assessing the physical condition of a person comprises a belt (10) to be arranged around the person's chest, a sensor unit (50) for detecting a distance between ends (12, 13) of the belt (10), and a processor unit for processing output provided by the sensor unit (50) during operation of the device. The sensor unit (50) comprises a LED (51) for emitting light, a phototransistor (52) for generating an output signal on the basis of a received amount of light, and a light blocking element (53) having a wedge-shaped light-varying section (54). The LED (51) and the phototransistor (52) are associated with one end (12) of the belt (10), while the light-blocking element (53) is associated with the other end (13) of the belt (10). As a result, when the person inhales and exhales, the amount of light that is received by the phototransistor (52) varies, and an output signal of the phototransistor (52) may be used as a measure of the chest circumference.

Description

Device for assessing the physical condition of a person

FIELD OF THE INVENTION

The present invention relates to a device for assessing the physical condition of a person, comprising a sensor unit. In particular, the device according to the present invention is applicable in the field of assessing physical fitness and energy expenditure during exercise by monitoring the chest circumference of the person who is tested. As the person breathes in and breathes out, his/her chest circumference changes continually over time. The difference between a maximum circumference and a minimum circumference is a measure of the physical fitness and the energy expenditure of the person. In the following, this difference is referred to as chest respiration depth.

BACKGROUND OF THE INVENTION

NL 1015410 discloses a method of determining the condition of a person. According to this method, measurements are performed on a person who is exercising, in order to obtain a so-called breathing pattern. In particular, the circumference of the chest of the person is measured by means of a stretchable belt, which is arranged around the chest, wherein means for detecting a pressure being exerted on the belt or means for detecting the extension of the belt are applied.

According to the state of the art, various embodiments of the means for detecting a pressure being exerted on the belt are known, and the same applies to the means for detecting the extension of the belt. For example, US 5423328 discloses a stress-detecting device comprising a respiration sensor that slid ably engages a stretchable belt. The respiration sensor comprises a base supporting a transducer responsive to forces applied thereon by the belt, for producing electrical signals representative of magnitudes of said forces. The force transducer may be a piezo transducer. Furthermore, WO 2005/044090 discloses a respiration sensor comprising an elastic strap that fits around the chest of the person and a transducer that is mounted to the strap, wherein the transducer comprises a flexible, variable resistance element. An important feature of this flexible element is that its resistance increases as its radius of curvature decreases. Also, in WO 2005/044090, the use of a belt and a strip of conductive rubber embedded in the belt are described. Stretching of the belt causes the conductive strip to elongate and to become reduced in cross-section, thus increasing its electrical resistance.

SUMMARY OF THE INVENTION It is an objective of the present invention to provide a device for assessing the physical condition of a person, comprising a sensor unit that may be used in combination with a belt or shirt to be arranged around the chest of a person, and that is capable of yielding accurate measuring results, while being robust, small, easy to manufacture and cost effective. According to the present invention, the objective is achieved by means of a device comprising a sensor unit having an active element which is adapted for emitting energy during operation of the sensor unit, a passive element which is arranged at a distance from the active element, and which is adapted for receiving energy emitted by the active element during operation of the sensor unit, and an intermediate element which is arranged in a path between the active element and the passive element, and which is adapted for influencing the amount of energy that is transferred from the active element to the passive element during operation of the sensor unit, wherein the intermediate element and a combination of the active element and the passive element are movably arranged with respect to each other, and wherein an extent to which the intermediate element is capable of influencing an amount of energy that is transferred from the active element to the passive element is dependent on the position of the intermediate element with respect to the combination of the active element and the passive element.

According to the present invention, the sensor unit comprises three elements, namely an active element, a passive element and an intermediate element, wherein the active element and the passive element on the one hand and the intermediate element on the other hand are movable with respect to each other. During operation of the sensor unit, the active element emits energy, and the passive element receives an amount of this energy. The intermediate element is chosen such as to be capable of influencing the amount of energy that is received by the passive element, wherein an extent to which this influence is exerted is dependent on the position of the intermediate element with respect to the active element and the passive element. For example, the intermediate element may have a function in hindering the energy transfer from the active element to the passive element. In such a case, the more the intermediate element is between the active element and the passive element, the less energy is received by the passive element. An output provided by the passive element during operation of the sensor unit is dependent on the amount of energy received from the active element. As the intermediate element and the combination of the active element and the passive element are movably arranged with respect to each other, and the output provided by the passive element is determined by the mutual position of the intermediate element and the combination of the active element and the passive element, the sensor unit is very well applicable for the purpose of detecting mutual displacements of two members. In particular, the intermediate element may be connected to one of the members, while the combination of the active element and the passive element may be connected to another of the members. In view of this possibility offered by the sensor unit, the sensor unit is very well applicable for the purpose of detecting the extension of an element incorporated in a belt or a shirt. Hence, the device according to the present invention is suitable to be applied for the purpose of assessing the physical condition of a person on the basis of measurements of the chest circumference of the person. In a practical embodiment of a device according to the present invention, which is suitable to be used for the purpose of determining the respiration depth of a person, the device further comprises a belt to be arranged around the chest of the person, wherein one end of the belt is connected to one of the intermediate elements and the combination of the active element and the passive element. When the person inhales, the circumference of the person's chest increases, wherein the intermediate element and the combination of the active element and the passive element are pulled apart. As a result, only a small portion or no portion at all of the intermediate element is present between the active element and the passive element, so that the influence of the intermediate element on the energy transfer from the active element to the passive element is very small or totally absent. When the person exhales, the circumference of the person's chest decreases, wherein the intermediate element and the combination of the active element and the passive element are moved towards each other. As a result, at least a substantial portion of the intermediate element is present between the active element and the passive element, so that there is a considerable or even maximal influence of the intermediate element on the energy transfer from the active element to the passive element. When the device according to the present invention comprises a belt, and one end of the belt is connected to the intermediate element, another end of the belt may be connected to an element for guiding the intermediate element, wherein the intermediate element is slid ably arranged with respect to the guiding element. In this way, a very stable and compact sensor unit is realized. In a preferred embodiment, the sensor unit further has resilient means for ensuring that a default mutual position of the active element and the passive element on the one hand and the intermediate element on the other hand is realized when the sensor unit is put to an unstressed condition after having been stressed. The resilient means may comprise a coil spring, for example.

For the purpose of processing output provided by the passive element on the basis of the amount of energy as received from the active element during operation of the sensor unit, the device according to the present invention may comprise any suitable type of processor unit. Preferably, such a processor unit is equipped with means for storing parameters representative of the output provided by the passive element, so that a user of the device according to the present invention is enabled to retrieve and study a history of measurement results.

The processor unit may be incorporated in one housing with the sensor unit, but in order to keep the sensor unit as small as possible, it is also possible for at least a portion of the processor unit to be arranged at a distance from the sensor unit, without any physical connection to the sensor unit, wherein transmission means are provided for transmitting data to this portion of the processor unit, and wherein receiving means are provided for receiving data in this portion of the processor unit. By providing the transmission means and the receiving means, it is possible to transfer data in a wireless fashion. The transmission means may be any type of suitable transmitter, for example a so- called blue tooth transmitter, and the receiving means may be any type of suitable receiver, for example a what is called blue tooth receiver.

The device according to the present invention is suitable to be applied for the purpose of informing a person who is exercising about his/her physical condition. In that case, the device is further preferred to comprises a member to be arranged around another part of the body of the person than the chest, wherein the portion of the processor unit which is arranged at a distance from the sensor unit is incorporated in this member. Such a member may be in the form of a headset or a watch, for example.

In a practical embodiment, the device according to the present invention is equipped with means for displaying parameters representative of the output provided by the passive element, so that the output may easily be read out by a user of the device. In case the device comprises a member such as described in the preceding paragraph, the displaying means may very well be part of that member. According to a first preferred option, the sensor unit has a light source, a light- sensitive element for receiving light that is emitted by the light source during operation of the sensor unit, and a light blocking element which is arranged in a light path between the light source and the light-sensitive element, wherein the light blocking element and a combination of the light source and the light-sensitive element are movably arranged with respect to each other, and wherein the light blocking element is adapted for interrupting the light path to different extents in different positions with respect to the combination of the light source and the light-sensitive element. Due to the fact that in the sensor unit comprising the light source, the light- sensitive element and the light blocking element, the interruption of the light path between the light source and the light-sensitive element is determined by the position of the light- blocking element with respect to the light source and the light-sensitive element, the sensor unit is suitable to be used for the purpose of measuring a distance between the ends of a belt arranged around the chest of a user. In case each of the light blocking element and the combination of the light source and the light-sensitive element is associated with another end of the belt, an output of the light-sensitive element, which is related to the amount of received light, is representative of the distance between the ends of the belt. An important advantage of the sensor unit functioning on the basis of transmission and reception of light is that a simple magnetic transmitter may be used for the purpose of transmitting data related to the output of the light-sensitive element.

The light-blocking element may have any suitable shape. For example, at least a portion of this element may be shaped like a wedge. It is also possible that the light- blocking element comprises a hole having any suitable shape. The fact that the shape may be a wedge shape applies to such a hole as well.

According to a second preferred option, the sensor unit has two electric coils arranged at a distance from each other, which are adapted for being magnetically coupled to each other during the operation of the sensor unit, and a core element which is arranged in a path between the coils, wherein the core element on the one hand and the coils on the other hand are movably arranged with respect to each other, and wherein the core element is adapted for enhancing the magnetic coupling between the coils to different extents in different positions with respect to the coils during operation of the sensor unit. The functioning of this type of sensor unit is based on the fact that a magnetic coupling between coils is improved when a core element, in particular a core element comprising a magnetically conductive material such as iron, is positioned between the coils. Hence, when more of the core element is present between the coils, the magnetic coupling between the coils is enhanced, and when less of the core element is present between the coils, the magnetic coupling between the coils is diminished.

Due to the fact that in the sensor unit having the coils and the core element, the magnetic coupling between the coils is determined by the position of the core element with respect to the coils, the sensor unit can be suitably used for the purpose of measuring a distance between ends of a belt arranged around the chest of a user. In case each of the core element and the coils is associated with another end of the belt, an output of one of the coils, which is related to the extent to which this coil is energized by another of the coils, is representative of the distance between the ends of the belt. An advantage of the sensor unit having the coils and the core element is that this sensor unit may be very robust, cost effective and very small, for example as small as 0.5 cm³.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be explained in greater detail with reference to the figures, in which similar parts are indicated by the same reference signs, and in which: Figure 1 diagrammatically shows a device according to the present invention, comprising a belt, a sensor unit, and a processor unit and display means;

Fig. 2 diagrammatically shows a first preferred embodiment of the sensor unit; and

Fig. 3 diagrammatically shows a second preferred embodiment of the sensor unit.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 diagrammatically shows a device 1 for assessing the physical condition of a person. In particular, the shown device 1 can be suitably applied for the purpose of performing measurements aimed at determining changes in the size of the person's chest due to chest-respiration.

The device comprises a belt 10 to be arranged around the chest of a person. In a buckle portion 11 of the belt 10, in particular between ends 12, 13 of the belt 10, a sensor unit 20 is arranged, which is adapted for detecting displacements of the ends 12, 13 of the belt 10 with respect to each other. During operation, the sensor unit 20 outputs a signal representing these displacements, which are a direct measure of changes of the circumference of the person's chest.

The device further comprises a watch-like device 30, which is intended to be positioned around a wrist of a user of the device 1 , who may be the person who is tested, but who may also be another person. For the purpose of surrounding a person's wrist, the watch- like device 30, like any conventional watch, comprises a strap 31. Furthermore, the watch- like device 30 comprises a functional unit 32 having a display 33. A processor unit 40 for processing an output signal of the sensor unit 20 in order to obtain information that may be understood and interpreted by a human being is arranged inside the functional unit 32.

During operation of the device 1, output generated by the sensor unit 20 is transmitted to the processor unit 40 in a wireless fashion. For the purpose of transmitting the data, a transmitter 45 is arranged in the buckle portion 11 of the belt 10, at a position close to the sensor unit 20. For the purpose of receiving the data, a receiver 46 is arranged in the functional unit 32 of the watch- like device 30, at a position close to the processor unit 40. In figure 1, the wireless transmission of data from the transmitter 45 to the receiver 46 is diagrammatically depicted by means of a dotted line.

In the following, the way in which the device 1 is operated and used by a person is explained. First of all, the person puts the belt 10 around his/her chest and puts the watch- like device 30 around one of his/her wrists. In order to obtain good measuring results, the person takes care that the tension in the belt 10 is such that the belt 10 is closely surrounding his/her chest, while at the same time the ends 12, 13 of the belt 10 are not exerting a pulling force on the sensor unit 20. After these preparatory actions, the person activates the device 1, and starts exercising. Due to the respiration of the person, the circumference of the person's chest continually changes. In particular, when the person inhales, the circumference increases, and when the person exhales, the circumference decreases. When the person inhales, the ends 12, 13 of the belt 10 are moved apart, and when the person exhales, the ends 12, 13 of the belt 10 are moved towards each other again. This process is continually repeated, wherein a frequency of the person's respiration and a difference between a minimum chest circumference and a maximum chest circumference change over time, in other words, wherein a respiration frequency and a respiration depth change over time, as the person's physical state is influenced by the exercise. The sensor unit 20 outputs a signal that is directly related to the distance between the ends 12, 13 of the belt 10. Hence, this signal is also directly related to the chest circumference. By means of the transmitter 45, the signal provided by the sensor unit 20 is transmitted to the receiver 46. The signal that is received by the receiver 46 serves as input of the processor unit 40 in the watch-like device 30.

The processor unit 40 processes the signal representing the chest circumference of the person in order to obtain parameters relating to energy expenditure and/or fitness of the person. By determining the respiration depth, the energy expenditure can be estimated, as the respiration depth represents the breath volume and the oxygen consumption. It is noted that this estimation has been found to be more accurate than an estimation of energy expenditure on the basis of measurements of the heart rate. Furthermore, on the basis of the measured values of the respiration depth, physical fitness of the person can be estimated. Also, the person can be assisted in training in the right training zone for increasing physical fitness or for losing weight, for example. In case it appears that the person is training in another training zone than desired, the person can be informed whether an increase or decrease of his/her efforts is needed for the purpose of reaching the right training zone. An estimation of training zones by measurements of respiration depth may be as follows: below 0.6 = recovery; 0.6 to 0.65 = fat burning/recovery; 0.65 to 0.75 = endurance; 0.75 to 0.82 = aerobic endurance; 0.82 to 0.89 = typical average road race intensity; 0.89 to 0.94 = speed training above threshold; and 0.94 to 1 = anaerobic sprints/intervals .

In the above list of training zones, the values as mentioned are expressed in relation to a maximum heart rate. As there is a linear relation between the maximum heart rate and the respiration depth, it is possible to measure the respiration depth, to translate the measured value to a value representing a portion or percentage of a maximum heart rate and find the appropriate training zone. In general, the respiration depth may be measured in various manners, wherein the unit of the respiration depth is dependent on the type of measuring method that is applied.

Output provided by the processor unit 40 is shown to the person by means of the display 33 of the watch-like device 30. Thus, by looking at the display 33, the person can be informed about the energy expenditure resulting from the exercise, about the training zone, etc. Advantageously, the functional unit 32 offers the person an opportunity of choosing which type of information is displayed. Also, it is preferred for the functional unit 32 to have a memory 41 for storing the data as determined, so that the person is enabled to retrieve the desired information at a later stage.

It is noted that instead of or in addition to a watch-like device 30, a headset may be used. In such case, the desired information is not communicated to the exercising person through a display. Instead, the person gets informed on the basis of sound, wherein every suitable type of sound may be chosen. For example, the person may be confronted with an automated voice speaking to him/her, or the person may be confronted with beeps, tones or the like. An advantage of using a headset is that the person is not hindered in exercising, which may be the case when he/she needs to look at a display 33 from time to time. It is not necessary that the transmission of data from the sensor unit 20 to the processor unit 40 takes place in a wireless fashion. Within the scope of the present invention, it is possible that these units 20, 40 are connected through a wire. Nevertheless, a wireless connection is preferred.

There is no need for the sensor unit 20 to contact the skin of the person in order to be capable of monitoring the chest circumference. On the basis of this fact, various embodiments of the device 1 according to the present invention are feasible, wherein there is much freedom of choice. Also, there is no need for measures to ensure skin contact.

The belt 10 may be integrated in clothing, for example in a shirt or a sports bra. In such a case, it is convenient for a person to use the belt 10, as the belt 10 is automatically positioned in the right place when the person puts on a certain piece of clothing.

The device 1 according to the present invention can be suitably used by sports- athletes, but also by people exercising for fun or health reasons. The monitoring function of the device 1 allows a person to follow his/her training progress and to exercise in the right training zone for either increasing physical fitness or for losing weight.

Within the scope of the present invention, various embodiments of the sensor unit 20 are feasible. In general, according to the present invention, the sensor unit 20 is equipped with two elements arranged at a distance from each other, wherein one of the elements, which is referred to as passive element, is arranged such as to be responsive to another of the elements, which is referred to as active element. Furthermore, the sensor unit 20 is equipped with an intermediate element which is arranged in a path extending between the two elements, and which is adapted for influencing the response of the passive element to the active element. The intermediate element on the one hand and the two elements on the other hand are movably arranged with respect to each other, so that the intermediate element may be moved between the two elements and influence the cooperation between the elements to a large extent, and the intermediate element may be at a retracted position and influence the cooperation between the elements to a small extent or not at all. When the intermediate element and the two elements are moved with respect to each other, the output of the sensor unit 20, which is obtained at the side of the passive element, changes. In this way, characteristics of the respiration of the person may be found on the basis of the output of the sensor unit 20.

Figure 2 diagrammatically shows a first preferred embodiment of the sensor unit 20, which is indicated by reference numeral 50. In this sensor unit 50, light is applied in the process of determining a mutual displacement of the ends 12, 13 of the belt 10. Therefore, the sensor unit 50 is referred to as light sensor unit 50.

The light sensor unit 50 comprises a light source for emitting light. In the shown example, the light source comprises a LED 51. Furthermore, the light sensor unit 50 comprises a light-resistive element. In the shown example, the light resistive element comprises a phototransistor 52. An output signal of the phototransistor 52 is dependent on an amount of light that is received from the LED 51.

For the purpose of varying the amount of light that reaches the phototransistor

52 in such a way that this amount of light may be taken as a measure of a mutual displacement of the ends 12, 13 of the belt 10, the sensor unit 20 comprises a light blocking element 53 having a wedge-shaped light-varying section 54, which is movably arranged in a light path extending between the LED 51 and the phototransistor 52. In the shown example, a direction in which the light-blocking element 53 is movable is substantially at right angles to a direction in which the light path is extending.

End portions 55 of the light-blocking element 53 are slid ably arranged inside portions 56 of a housing 57, which are adapted for guiding these portions 55 of the light- blocking element 53. At the side of one guiding portion 56 of the housing 57, a first end 12 of the belt 10 is connected to the housing 57, through a suitable connecting element 58. At the side of another guiding portion 56 of the housing 57, which guiding portion 56 comprises a through-hole for accommodating the end portion 55 of the light blocking element 53, a second end 13 of the belt 10 is connected to the light blocking element 53, through a suitable connecting element 59.

When a person who is wearing the belt 10 inhales, the light-blocking element

53 on the one hand and the housing 57, the LED 51 and the phototransistor 52 on the other hand are moved apart. As a result, another portion of the light-varying section 54 of the light- blocking element 53 is in the light path. In the shown example, the arrangement of the light- varying section 54 of the light blocking element 53 is chosen such that in an unstressed condition, a portion of the light-varying section 54 having a smallest height is present in the light path, and that in a stressed condition, a portion of the light-varying section 54 having a larger height is present in the light path. Hence, the more the ends 12, 13 of the belt 10 are pulled apart, the less light is allowed to reach the phototransistor 52.

In order to ensure that the light blocking element 53 moves back to a default position after having been moved with respect to the housing 57, the LED 51 and the phototransistor 52 as a result of an inhalation, the light sensor unit 50 has a coil spring 60 which is arranged around a portion of the light blocking element 53, and which extends between a connection 61 to the light blocking element 53 and a guiding portion 56 of the housing 57. The default position may be associated with a relaxed state of the coil spring 60, but this is not necessary. In the shown example, the coil spring 60 is arranged at the side of the guiding portion 56 of the housing 57 having the through-hole, and a stop 62 is arranged at the end portion 55 of the light-blocking element 53 extending through that guiding portion 56 of the housing 57, at a position outside the housing 57. In that case, the default position is associated with a situation in which the stop 62 abuts against the housing 57.

It is clear from the preceding description of the light sensor unit 50 that when the person who is wearing the belt 10 inhales, a displacement of the light blocking element 53 with respect to the combination of the LED 51 and the phototransistor 52 is realized, wherein, due to the shape of the light-varying section 54 of the light blocking element 53, less of the light emitted by the LED 51 is allowed to reach the phototransistor 52. As a rule, the more the ends 12, 13 of the belt 10 are moved apart, the less light is received by the phototransistor 52, and the smaller the output signal of the light sensor unit 50 will be. When the person who is wearing the belt 10 exhales, the light-blocking element 53 is moved back to the default position. In the process, more and more light is allowed to reach the phototransistor 52, until the belt 10 is in a relaxed state, and the displacement of the light blocking element 53 and the housing 57, the LED 51 and the phototransistor 52 with respect to each other has stopped. As the person alternately inhales and exhales, the process of the phototransistor 52 receiving less and less light, until a minimum has been reached, and then receiving more and more light, until a maximum has been reached, is continually repeated. In this way, the magnitude of the output signal of the light sensor unit 50 continually changes, and an amplitude and a frequency of the respiration may easily be determined by the processor unit 40. The light-blocking element 53 does not necessarily need to have a wedge- shaped light-varying section 54 such as shown in figure 2. Various other embodiments of the light-varying section 54 of the light-blocking element 53 are feasible, wherein it is important that the extent to which the light is blocked varies with the relative position of the light- varying section 54. For example, the light-varying section 54 may comprise a plate having a wedge-shaped hole. Furthermore, it is not necessary that the light-varying section 54 is adapted for ensuring that the amount of light that is transferred from the LED 51 to the phototransistor 52 decreases when the distance between the ends 12, 13 of the belt 10 increases. It may also be the other way around, i.e. the amount of light that is transferred from the LED 51 to the phototransistor 52 increases when the distance between the ends 12, 13 of the belt 10 increases.

An advantage of the fact that the mutual position of the ends 12, 13 of the belt 10 is measured by using light is that the transmitter 45 for transmitting the output of the phototransistor 52 may be a common transmitter 45 capable of generating a magnetic field, as the performance of such a transmitter 45 is not influenced by light.

Figure 3 diagrammatically shows a second preferred embodiment of the sensor unit 20, which is indicated by reference numeral 70. In this sensor unit 70, a voltage and two magnetically coupled coils 71, 72 are applied in the process of determining a mutual displacement of the ends 12, 13 of the belt 10. Therefore, the sensor unit 70 is referred to as coil sensor unit 70.

The coil sensor unit 70 is shaped like a common transformer. In particular, the coils 71, 72 are arranged opposite each other. During operation, a voltage is applied to one of the coils 71, 72, which are referred to as primary coil 71, for example a sine wave at a frequency of 10 KHz. As a result, an alternating magnetic field is generated. Under the influence of this alternating magnetic field, an output voltage is generated in another of the coils 71, 72, which is referred to as secondary coil 72.

Besides the coils 71, 72, the coil sensor unit 70 comprises an iron core element 73. This core element 73 is movably arranged, and is positioned such that it may be moved in and out of a space 74 that is present between the coils 71, 72. The more the core element 73 is moved between the coils 71, 72, the higher the output voltage that is obtained, as the core element 73 is capable of enhancing the effect of the alternating magnetic field on the secondary coil 72.

In the device 1 according to the present invention, the coils 71, 72 and the core element 73 are coupled to different ends 12, 13 of the belt 10. When a person who is wearing the belt 10 inhales, the ends 12, 13 of the belt 10 are moved apart, and the core element 73 is moved out of the space 74. As a result, the output voltage of the secondary coil 72 decreases. When the person who is wearing the belt 10 exhales, the ends 12, 13 of the belt 10 are moved towards each other, and the core element 73 is moved more and more into the space 74. As a result, the output voltage of the secondary coil 72 increases. In this way, the output voltage is applicable as a measure of the distance between the ends 12, 13 of the belt 10. Therefore, it is possible to determine an amplitude and a frequency of the respiration of the person by using the coil sensor unit 70.

Important advantages of the coil sensor unit 70 are that this sensor unit 70 may be cost effective, as it comprises only a number of standard components, and it may be small, for example only 0.5 cm .

The core element 73 may comprise any suitable magnetically conductive material. In case of relatively high voltages, the application of a material known as ferroxdure is preferred. It will be clear to a person skilled in the art that the scope of the present invention is not limited to the examples discussed in the foregoing, but that several amendments and modifications thereof are possible without deviating from the scope of the present invention as defined in the attached claims.

It is noted that the device 1 according to the present invention does not necessarily need to comprise a belt 10 for the purpose of providing the sensor unit 20, 50, 70 with input related to a circumference of a person's chest or another characteristic of a person's body.

In the foregoing, the device 1 according to the present invention is described in the context of measurements of the circumference of a person's chest during exercise. That does not alter the fact that the device 1 may be adapted for performing other measurements. Nevertheless, as the device 1 comprises a combination of an active element for emitting energy and a passive element for receiving energy, and an intermediate element, wherein an actual amount of energy that is received by the passive element is dependent on a relative position of the intermediate element, the device 1 is particularly suitable for measuring body characteristics involving a movement.

In the foregoing, among other things, a device 1 for assessing the physical condition of a person having a belt 10 to be arranged around the person's chest, a sensor unit 20, 50, 70 for detecting a distance between ends 12, 13 of the belt 10, and a processor unit 40 for processing output provided by the sensor unit 20, 50, 70 during operation of the device 1 are disclosed. In one embodiment, the sensor unit 50 comprises a LED 51 for emitting light, a phototransistor 52 for generating an output signal on the basis of an amount of the light that is received from the LED 51, and a light-blocking element 53 having a wedge-shaped light- varying section 54. The LED 51 and the phototransistor 52 are associated with one end 12 of the belt 10, while the light-blocking element 53 is associated with another end 13 of the belt 10. As a result, when the person inhales and exhales, and the ends 12, 13 of the belt 10 are moved apart and towards each other, the amount of light that is received by the phototransistor 52 varies, as the position of the light-varying section 54 of the light blocking element 53 with respect to the LED 51 and the phototransistor 52 varies. The results of the measurements of the changes of the chest circumference can be suitably used for calculating energy expenditure and for determining an actual training zone.

Claims

CLAIMS:

1. Device (1) for assessing the physical condition of a person, comprising a sensor unit (20, 50, 70) having an active element (51, 71) which is adapted for emitting energy during operation of the sensor unit (20, 50, 70), a passive element (52, 72) which is arranged at a distance from the active element (51, 71), and which is adapted for receiving energy emitted by the active element (51, 71) during operation of the sensor unit (20, 50, 70), and an intermediate element (53, 73) which is arranged in a path between the active element (51, 71) and the passive element (52, 72), and which is adapted for influencing the amount of energy that is transferred from the active element (51, 71) to the passive element (52, 72) during operation of the sensor unit (20, 50, 70), wherein the intermediate element (53, 73) and a combination of the active element (51, 71) and the passive element (52, 72) are movably arranged with respect to each other, and wherein an extent to which the intermediate element (53, 73) is capable of influencing an amount of energy that is transferred from the active element (51, 71) to the passive element (52, 72) is dependent on the position of the intermediate element (53, 73) with respect to the combination of the active element (51, 71) and the passive element (52, 72).

2. Device (1) according to claim 1, further comprising a belt (10) to be arranged around the chest of the person, wherein one end (12, 13) of the belt (10) is connected to one of the intermediate element (53, 73) and the combination of the active element (51, 71) and the passive element (52, 72).

3. Device (1) according to claim 2, wherein one end (13) of the belt (10) is connected to the intermediate element (53, 73), and wherein another end (12) of the belt (10) is connected to an element (56) for guiding the intermediate element (53, 73), wherein the intermediate element (53, 73) is slid ably arranged with respect to the guiding element (56).

4. Device (1) according to any one of claims 1-3, wherein the sensor unit (50, 70) further has resilient means such as a coil spring (60) for ensuring that a default mutual position of the intermediate element (53, 73) and the combination of the active element (51, 71) and the passive element (52, 72) is realized when the sensor unit (50, 70) is put to an unstressed condition after having been stressed.

5. Device (1) according to any one of claims 1-4, further comprising a processor unit (40) for processing output provided by the passive element (52, 72) on the basis of the amount of energy as received from the active element (51, 71) during operation of the sensor unit (20, 50, 70).

6. Device (1) according claim 5, wherein the processor unit (40) is equipped with means (41) for storing parameters representative of the output provided by the passive element (52, 72).

7. Device (1) according to claim 5 or 6, wherein at least a portion of the processor unit (40) is arranged at a distance from the sensor unit (20, 50, 70), without any physical connection to the sensor unit (20, 50, 70), and wherein transmission means (45) are provided for transmitting data to this portion of the processor unit (40), and wherein receiving means (46) are provided for receiving data in this portion of the processor unit (40).

8. Device (1) according to claim 7, further comprising a member (30) to be arranged around another part of the body of the person than the chest, wherein the portion of the processor unit (40) which is arranged at a distance from the sensor unit (20, 50, 70) is incorporated in this member (30).

9. Device (1) according to any one of claims 5-8, further comprising means (33) for displaying parameters representative of the output provided by the passive element (52,

72).

10. Device (1) according to claim 9, insofar as dependent on claim 8, wherein the means (33) for displaying parameters are part of the member (30) to be arranged around another part of the body of the person than the chest.

11. Device (1) according to any one of claims 1-10, wherein the sensor unit (50) has a light source (51), a light-sensitive element (52) for receiving light that is emitted by the light source (51) during operation of the sensor unit (50), and a light blocking element (53) which is arranged in a light path between the light source (51) and the light-sensitive element (52), wherein the light blocking element (53) and a combination of the light source (51) and the light-sensitive element (52) are movably arranged with respect to each other, and wherein the light blocking element (53) is adapted for interrupting the light path to different extents in different positions with respect to the combination of the light source (51) and the light- sensitive element (52).

12. Device (1) according to claim 11, wherein at least a portion (54) of the light- blocking element (53) of the sensor unit (50) is shaped like a wedge.

13. Device (1) according to claim 11, wherein the light-blocking element (53) of the sensor unit (50) comprises a plate having a wedge-shaped hole.

14. Device (1) according to any one of claims 1-10, wherein the sensor unit (70) has two electric coils (71, 72) arranged at a distance from each other, which are adapted for being magnetically coupled to each other during operation of the sensor unit (70), and a core element (73) which is arranged in a path between the coils (71, 72), wherein the core element (73) on the one hand and the coils (71, 72) on the other hand are movably arranged with respect to each other, and wherein the core element (73) is adapted for enhancing the magnetic coupling between the coils (71, 72) to different extents in different positions with respect to the coils (71, 72) during operation of the sensor unit (70).

15. Device (1) according to claim 14, wherein the core element (73) comprises a magnetically conductive material such as iron.