SE2150754A1 - Breath analyzing system suitable for helmets - Google Patents

Abstract

The present invention relates to a personal protection device, for example a helmet, comprising a breath analyzing system suitable to be provided in a helmet. The breath analyzing system comprises a breath analyzer, a proximity sensor, a communication unit and a flow control assembly arranged to alarm if the breath concentration of a selected intoxicating substance exceeds a predetermined value. The breath analyzing system has a low power inactive mode and an active mode and the proximity sensor is arranged to detect if the personal protection device is worn, and if so, the system changes to an active mode the breath analysis is initiated. The active mode includes initiating an active element of the flow control assembly.

Description

BREATH ANALYZING SYSTEM SUITABLE FOR HELMETS Field of the invention The present invention relates to a breath analyzing system suitable to be provided in a helmet.The breath analyzing system comprises a breath analyzer, a proximity sensor, a floW controlassembly, and a communication unit arranged to alarm if the breath concentration of aselected intoxicating substance exceeds a predeterrnined value. In particular, the inventionrelates to a helmet in Which the breath analyzer is activated only if the proximity sensor detects that the helmet is Wom properly.

Background of the invention Vehicles equipped With breath analyzing equipment to detect air-bome intoxicatingsubstances, in particular alcohol, are becoming increasingly common. The breath analyzingequipment may be a stand-alone unit that gives a measured value of the content of anintoxicating substance or substances in the driver°s breath, it may also be part of a systemWherein also equipment for identifying the driver and/or immobilizer equipment. To provide abreath analyzer that has an appropriate sensitivity, is reliable and provides a reasonable fastanalysis is far from trivial. This is especially true if the breath analyzing equipment should beable to detect a plurality of substances and not being disturbed by variation in moisture, C02content etc. Breath analyzing equipment that fulfills these requirements are described in for example US79l9754B2 and US9746454B2, hereby incorporated by reference.

So far breath analyzers and system incorporating breath analyzers have been installed mainlyin vehicles such as cars and trucks and to a relatively large extent, commercial vehicles. For anumber of reasons breath analyzers have been discussed much less in association With openvehicles such as motorcycles and scooters. Given the high number of serious accidentsWherein motorcycles and scooters are involved, not at last in regions Wherein open vehiclesare common for both transportation and commercial use, for example deliveries, a number ofinitiatives has been taken to improve the security. These initiatives have so far beenconcentrated on forcing the driver to Wear a helmet by making it impossible to ignite thevehicle Without wearing a helmet. HoWever, recently more functionality has beenincorporated into helmets that are commonly referred to as “smart helmets” or “intelligent helmets”. A “smart helmet” that incorporate an alcohol detection device is discussed in 2 “Intelligent Helmet”, Jennifer William et al.; Intemational Journal of Scientific & EngineeringResearch, Volume 7, Issue 3, March-2016, ISSN 2229-5518. To incorporate a reliable andaccurate alcohol detection function in a helmet imposes very different demands compared toproviding the function in a closed car compartment. Areas of major concems are for example,but not limited to: -The size and weight of the equipment added to the helmet. The comfort, and even moreimportantly, the protective capacity of the helmet should not be jeopardized, which forexample adding substantial weight to the helmet would do. Also the appearance is ofimportance in getting the helmet accepted by a large majority of drivers -the smart helmetshould preferably have the same sleek appearance as a regular helmet.

-Power consumption. A smart helmet should preferably be wireless during use. Given the sizeand weight constrains discussed above, this limits the amount of batteries, and hence power,that can be provided in the helmet. Reliable breath analyzing equipment, exemplified byUS7919754B2 and US9746454B2, are typically high power consuming as they are based onInfrared (IR) Spectroscopy for the analysis. There is to date no low power altemative thatoffers the same sensitivity and ability to detect a range of substances. CN107348596 disclosesa helmet that power up an integrated breath analyzing system if a detector or switch indicatethat a person is wearing the helmet.

-It is preferred to provide implementations not requiring the driver blowing into a mouthpiece,something that is offered by some car mounted systems and referred to as passive systems. Ina helmet a very complex airstrean1/pressure situation has to be handled if a passive system is to be implemented.

Summary of the invention The object of the invention is to provide a personal protection device, for example a helmet ora wearable device, comprising a breath analyzing system suitable for being provided in ahelmet. Being mounted in a such personal protection device gives constrains to the system with regards to being compact and power efficiency.

This is achieved by the personal protection device as defined in claim 1, the helmet as definedin claim 15, the helmet attachment as defined in claim 15 and the method as defined in claim 18.

The personal protection device according to the invention comprises a breath analyzer, aproximity sensor, a control and computational unit and a communication unit. The breathanalyzer, the proximity sensor and the communication unit are arranged to be incommunicative connection with the control and computational unit. The breath analyzingsystem has a low power inactive mode and an active mode. The proximity sensor is arrangedto detect the presence of a human skull in the helmet, said detection operable at least duringthe inactive mode of the breath analyzing system. The control and computational unit isoperable in a low power stand-by mode monitoring an input from the proximity sensor at leastduring the inactive mode, and upon input from the proximity sensor it initiates a change toactive mode of the breath analyzing system and activates the breath analyzer. The breathanalyzer is arranged to on receiving an activation from the control and computational unit,perform a breath analysis and transmit a representation of the breath analysis to the controland computational unit. The breath analyzing system further comprises a flow controlassembly comprising at least one active element and one passive element, providing a gascommunication channel from the mouth and/or nose of a user wearing the helmet to an inletof the breath analyzer and through the breath analyzer. The active element of the flow controlassembly is arranged to provide a continuous transport of air to the inlet and through the breath analyzer during the active mode of the breath analysis system.

The personal protection device according to the invention has the advantage of providing anenergy efficient system only activating major energy consuming parts as the breath analyzerand the active element than required for performing the breath analysis. The flow control assembly with a combination of passive and active elements ensure that respiratory air is 4 diluted as little as possible and that the time delay is short, both prerequisites for passive detection of for example alcohol.

According to one aspect of the invention at least one passive element of the flow controlassembly is forrned as an integrated part of the protective structure of the helmet. A passiveelement may be in the forrn of an air channel for expiratory air forrned in the protectivestructure of the personal protection device. The channel may be open on the side configured to face the user so that during use that side of the channel is forrned by the head of the user.

According to one aspect of the invention the flow control assembly comprises at least oneflow guiding structure positioned so that it will be close to the mouth of a user wearing thepersonal protection device and having a ridge facing the mouth to forrn a bifurcation of the airflow into the mouth/nose and the airflow out of the mouth/nose of the user.

One advantage of the passive elements is that the control of the transportation of respiratoryair is increased. By integrating with the protective structure of for example a helmet anefficient implementation of the breath analyzing system is achieved and comfort and protection is not jeopardized.

According to one aspect of the invention the control and computational unit is arranged toanalyze the representation of the breath analysis and compare with at least one predeterrninedvalue of an intoxicating substance, and if the predeterrnined value is exceeded activate thecommunication unit to issue an alarm. The breath analysis may include the computation of thedifference between maximal and minimal readings during a breath cycle of a substance and a tracer signal, said tracer signal representing the concentration of carbon dioxide.

According to one aspect of the invention the flow control assembly includes flow impedanceswhich are either resistive or capacitive and wherein the resistance is dominated by the air flowthrough a preheater provided in the flow control assembly, the preheater resistance Rh, and thecapacitance by the breath analyzer cavity capacitance CC, and the response time ro is given bythe relation, ro = RhCC, and wherein the response time, m, is less than one second, andpreferably less than 0.5 second. Sufficiently short response time is a prerequisite in providing an effective and reliable passive breath analyzing system.

According to one aspect of the invention the proximity sensor is an ultra-low power proximitysensor, for example a capacitive or an inductive proximity sensor. Altematively, the ultra-low power proximity sensor is a mechanical switch.

The proximity sensor will be “on” also in the inactive mode of the breath analysis system. Byintroducing an ultra-low power proximity sensor the power consumption in the inactive modewill be minimized which in tum increases the battery life. Decent battery life could be a key factor for public acceptance of the system.

According to aspects of the invention the breath analyzing system may comprise one or moresensor arranged to detect a condition associated to the usage of the personal protection device,and the control and computational unit being operable in a low power stand-by modemonitoring an input from the proximity sensor and the at least one second sensor; and uponinput from the proximity sensor proximity sensor and the second sensor activate the breathanalyzer. Second sensor include, but are not limited to, a switch detecting the position of avisor of the helmet, a switch detecting that a mechanical locking mechanism of a strapholding the personal protection device in place is correctly engaged, and indicator of positions of vents on a helmet.According to one aspect of the invention the personal protection device is a helmet.

According to one aspect of the invention the personal protection device is an attachment conf1gured to be attached to a helmet, for example a collar.

The method according to the invention of performing breath analysis suitable for drivers ofopen vehicles by the use of a helmet comprising a breath analyzing system comprising abreath analyzer, an proximity sensor, a flow control assembly, a control and computationalunit and a communication module, the method comprises the steps of: -keeping the breath analyzing system in an inactive mode wherein only the proximity sensoris actively in a detecting mode; - the control and computational unit (12) in the active mode, activating the breath analyzerand the active element of the flow control assembly, the breath analyzer which in responseoutputs a representation of measured data to the control and computational unit; -in the active mode the control and computational unit activates the breath analyzer, which in 6 response outputs a representation of measured data to the control and computational unit;- the representation of measured data is analyzed by the control and computational unit - the control and computational unit issuing an alarrn if the estimated breath concentration ofa selected intoxicating substance exceeds a predeterrnined value; - if the estimated breath concentration of a selected intoxicating substance exceeds apredeterrnined value, at least an alarm is activated and if the estimated breath concentration ofthe intoxicating substance is lower than the predeterrnined value, the system retums to aninactive mode. In combination With the alarm the open vehicle may be immobilized. Theprocess of checking analyzing the breath may be repeated during the uses of the vehicle, for example at predeterrnined time intervals.

According to one aspect of the method of the invention the step of tuming the breathanalyzing system from an inactive mode to an active mode further comprises receiving andanalyzing the input from a plurality of sensors or indicators and only if the input from theplurality of sensors or indicators corresponds to a predeterrnined scheme tum the breathanalyzing system from the inactive mode to the active mode. The predeterrnined scheme mayfor example specify that the visor of the helmet should be in a closed position and/or that the strap of the helmet is secured.

According to a further aspect of the method according to the invention the step of activatingthe breath analyzer comprises a pre-step of activating the active element of flow controlassembly to give a stable flow of air, including expiratory air, through the sensor module before the actual measurement is performed.

According to one aspect of the method according to the invention the air transport from auser°s mouth/nose to the breath analyzer is effectuated With a time delay considerably shorterthan one second. The breath analysis preferably includes the computation of the differencebetWeen maximal and minimal readings during a breath cycle of a substance and a tracer signal, said tracer signal representing the concentration of carbon dioxide.

According to one aspect the method further comprises a step of immobilizing the open vehicleif the estimated breath concentration of a selected intoxicating substance exceeds a predeterrnined value. 7 Afforded by the present invention is the possibility to use a breath analyzer which is based onthe principle of non-dispersive infrared spectroscopy (NDIR) to allow adequate accuracy,specificity and reliability, and confined in a breath analyzer cavity having physical dimensions small enough to be integrated inside a helmet.

One advantage of the present invention is that the function of the helmet with respect to thepersonal safety of its carrier is not compromised. This is ensured by the system according tothe invention being an integral part of the helmet or constituting a separable physicalenclosure. From the points of view of testing and quality assurance, the second alternative is particularly attractive.

One advantage is that the breath analyzing system may be adapted to various kinds of helmets, such as open helmet and full-face helmets.

Low power consumption and attractive features increases the likelihood of the equipmentbeing used. Low power consumption of the breath analyzing system is a requirement on itsown, but an additional effect is that power can be saved to other systems that might attract adriver more than a breath analyzing system, for example a GPS navigator with on-visor display.

In the following, the invention will be described in more detail, by way of example only, withregard to non-limiting embodiments thereof, reference being made to the accompanying drawings.

Brief description of the drawingsFig. la-b are schematic illustrations of the helmet according to the present invention in (a) a semi cross-section View and (b) in a View from below;Fig. 2 is a schematic illustration of the functional units of the present inVention; Fig. 3 is a schematic illustration of one embodiment of the helmet according to the present inVention; Fig. 4 is a schematic illustration of the ultra-low power proximity sensor according to the present inVention; Fig. 5 is a schematic illustration of the functional units of the helmet node and the open vehicle node according to one embodiment of the present inVention; Fig. 6 is a logical circuit of the sWitching functionality according to one embodiment of the inVention; Fig. 7 a-b are graphs illustrating the analyzed C02 content and detected substance at different time as detected by the breath analyzer of the present inVention; Fig. 8 is a schematic representation of the function of the flow control assembly including its basic constituents provided in the helmet according to the present inVention; Fig. 9 is a floWchart of the method according to the present inVention; Fig. l0 illustrates one embodiment of an additional helmet module according to the inVention.

Detailed description 77 CC 77 CC Terms such as ”top , bottom”, upper”, lower”, “below , above” etc are used merely withreference to the geometry of the embodiment of the invention shown in the drawings and/orduring norrnal operation of the helmet and are not intended to limit the invention in any IIIaIIIICT.

The terrn “open vehicle” is herein used to encompass all vehicles for which a helmet iscommonly recommended for the driver and passengers. Open vehicle includes, but is not limited to, motorcycles, scooters, tricycles, quads/ATVs, snowmobiles and speedboats.

The present invention relates to a personal protection device provided with a breath analyzingsystem. The personal protection device could be a helmet or an attachment to a helmet, forexample a collar to be wom together with a helmet. The personal protection item is primarilydescribed as a helmet for the ease of description only and all features and variants are relevant for all personal protection items, if not otherwise stated.

A helmet according to the present invention comprising a breath analyzing system 3 isschematically illustrated in Figures la-b, wherein a) is a partly cross-sectional sideview of thehelmet and b) is a view of the helmet from below. Figure 2 is a schematic illustration of thefunctional units of a breath analyzing system according to the invention. The helmet lcomprises a visor 2, which may be movable and is depicted in a downward position. Thebreath analyzing system 3 of the helmet l comprises a breath analyzer 6 with an analyzingchamber 6b forrning a cavity in which a breath sample is analyzed, a proximity sensor 7, acontroller and computational unit l2, a communication unit l3 and a power supply l5. Thebreath analyzer 3, the proximity sensor 7 and the communication unit l3 are arranged to be incommunicative connection with the controller and computational unit l2. The breath analyzer6 is provided with an inlet 16 and an outlet l7. A flow control assembly ll is provided influid communication with the inlet l6, or the outlet l7, or both the inlet 16 and the outlet l7.The inlet 16 may include a heater element, e g a serpentine conducting foil or metallic wiregrid, to prevent condensation of water droplets within the breath analyzer cavity 6. The heaterconstitutes the dominant air flow resistance of the flow control assembly ll, the functionalsignificance of which will be further described in relation to Figure 8. The flow control assembly ll comprises passive elements and at least one active element lla to control the air flow within the helmet 1. The passive elements are operative to provide selected air passagesto the respiratory air flow and the active element 1 la to actively transport at least a portion ofthe respiratory air flow. The active element 11a of the flow control assembly 11 is in communicative connection with and is controlled by the controller and computational unit 12.

According to one embodiment the active element 11a of the flow control assembly 11 is aflow generating device 11a provided in connection to the analyzing chamber 6b. Preferably,the flow generating device 11a comprises a miniature fan, and also a flow measurementdevice with a tachometer control function. The flow generating device 11a can be controlledby the controller and computational unit 12. According to one embodiment the flowgenerating device 1 la is provided after the analyzing chamber 6b in the direction of theairflow, as this generally is a preferred way to ensure a steady and predictable air flowthrough the analyzing chamber 6b. Altematively, the flow generating device 1 la may bepositioned elsewhere in the flow control assembly ll, which could be a design choiceconsidering other design parameters of the helmet, such as safety, comfort and weight distribution.

The proximity sensor 7 is according to one embodiment an ultra-low power proximity sensordesigned and arranged to detect the presence of a human skull in the helmet. Preferably theultra-low power proximity sensor 7 requires a minimum of power during a non-detecting stateand also only a small amount of power for the actual detection of a skull and forcommunication with the control and computational unit 12. The ultra-low power proximitysensor 7 may be a capacitive or inductive proximity sensor. Such ultra-low power proximitysensors are known in the art and will be further discussed below. The proximity sensor 7 mayalso comprise a plurality of sensors and/or switches arrange to, in combination, detect thepresence of a skull in the helmet 1 and also other conditions associated to the driver beingdriving or about to start driving. Such additional sensors/switches include, but is not limited tosensors indicating the position of a visor of the helmet, the driver having mounted the vehicle CtC .

Suitable breath analyzers are known and commercially available from for example SenseairAB. As discussed in the background breath analyzers with required physical size and weightfor helmet integration, sensitivity, reliability and speed of detection typically relies on IR- spectroscopy, which make them consume considerably amounts of energy during operation. 11 The breath analyzer 6 is arranged to respond to the intoxicating Substance, and to a respiratorytracer gas generally occurring in expiratory air, e g C02 or H20. Preferably the breathanalyzer is based on infrared spectroscopy, including an infrared source, a detector, andoptical filters with passband adapted to absorption bands of the substances to be analyzed. Inthe case of ethyl alcohol as the intoxicating substance, an absorption band at 9.5 um is used.Corresponding absorption band for C02 is 4.3 um. These design principles are enabling highsensitivity and specificity to the selected substances. The breath analyzer 6 according to theinvention is arranged to have a low power inactive mode, including a completely switch offmode, and an active mode. The breath analyzer 6 is tumed on or put in active mode by thecontrol and computational unit 12 and then perform a breath analysis and transmit arepresentation of the breath analysis to the control and computational unit 12 and after the breath analysis is performed retum to the inactive mode or to being tumed off.

The control and computational unit 12 is preferably a general-purpose microcontrolleroperating on digital signals to perform logical and arithmetic operations according to a pre-programmed scheme. It may calculate the breath concentration of the intoxicating substanceby multiplying the actual measured value by the appropriate dilution factor deterrnined bybreath analyzer element responding to the tracer gas. The control and computational unit 12 isbeing operable in a low power stand-by mode essentially only monitoring an input from theproximity sensor 7. The detection of a signal from the proximity sensor 7 acts as trigger toactivate the control and computational unit 12 into an operational mode and in sequenceactivate the breath analyzer 6 in combination with the active element 11a of the flow controlassembly 11. Also the the communication unit 13 may be activated. Also other conditionsmay be required for the control and computational unit 12 to activate the breath analyzer 6.From a system level the breath analyzing system 3 may be described as having an inactivemode, which is characterized by a minimum of power consumption, wherein only partsrequired for a first detection of the helmet being used is active and an active mode wherein breath analysis and communication is performed.

The power control unit 14 is preferably managing proper power supply to all systemcomponents. It is preferably driven by a power supply 15, which may be a rechargeablebattery, preferably a high capacity battery such as a lithium-ion battery. The power control unit 14 may be connected with power harvesting devices harvesting energy from 12 electromagnetic radiation, sun, motion or other energy sources, which can be used momentarily or to charge the battery.

According to one embodiment at least one passive element of the flow control assembly ll isformed as an integrated part of the protective structure of the helmet l and the flow controlassembly ll is arranged to direct air up around the head and into the breath analyzer. Theintegrated part may for example be, but not limited to channels transporting air, in particularexpiratory air, a flow guiding structures assisting in directing the air or providing separationbetween airstreams or sealing members. According to one embodiment illustrated in Figuresla-b, the flow control assembly comprises the flow generating device lla, at least a front airchannel l lb and at least a rear air channel llc. A modem helmet l is typically built up by ahard outer shell lb, an impact absorbent liner lc and a comfort liner ld forrning the protectivestructure. The front air channel l lb and the rear air channel llc may be arranged in either theimpact absorbent liner lc or a comfort liner ld or extends over both liners. The front airchannel l lb and the rear air channel llc may be realized by a number of channels that are j oined to the inlet l6 and the outlet l7, respectively. The front air channel llb and the rear airchannel llc typically have a depth, i.e. their extension in the radial direction, in the order oflcm. The front air channel llb may preferably be shaped as a funnel with a substantiallywider opening, in the direction of the helmet°s inner circumference, at the front end, towardsthe persons face, than at its rear end j oining the inlet l6. Preferably the width at the front endof the front air channel l lb is in the order of 5 cm or larger. In order to not impair with theimpact function or the comfort of the helmet an air channel, for example front air channel l lb, may in its wider parts, be divided into a plurality of thinner channels, or having aplurality of impact absorbent protrusions extending in the radial direction. The rear airchannel llc may end as depicted close to the user°s neck. Altematively the rear air channelllc ends in one or more vents (not shown) provided in the rear part of the helmet l. Such vents typically exist on modem helmets in order to provide means for ventilation.

According to one embodiment at least one air channel is an open elongated recession in theprotective structure, so that during use the user's head forms one wall of the channel. Thecomfort liner ld in the helmet is often removable, for cleaning and/or personal adjustment,and may comprises of a plurality of different parts referred to as pads. One altemative is thatthe front air channel llb and the rear air channel llc are formed as intentional gaps between separate comfort liner pads. 13 The air flow directed by the flow control assembly 11 is indicated with arrows in Figure 1.Air enters the helmet inlet area 4 and is either mixed with the person°s expiratory air or partlyinhaled by the person depending on the actual instant within the person”s respiratory cycle.The air is further drawn upwards inside the closed visor 2 and then passes through the breathanalyzer 6 to the helmet flow outlet 5 at the neck of the driver. The airflow is driven andcontrolled by the flow generating device 11a to pass through the inlet 16 and outlet 17 of thebreath analyzer 6. Preferably, the flow generating device 6b is a miniature fan, including aflow measurement device with a tachometer control function. The inner surface of the visor 2and other inner surfaces of the helmet 1 preferably includes material which is non-absorbing with respect to the intoxicating substance, e g a fluoropolymer.

According to one embodiment the air is transported driven by the flow generating device 6band via air one or more channels provided in the protective structure of the helmet 1, for example in channels provided in padding.

The flow control assembly 11 may include one or several flow guiding structures. Accordingto one embodiment flaps 11d, 11c preferably made from non-absorbing polymer foam are arranged on and extending from the inner surface of the helmet 1 close to the breath analyzercavity 6 and forrning a flexible, yet tight contact surface towards the person°s skull. The flaps 11c, 11d are given a curved surface to allow a smooth and laminar air flow.

According to one embodiment a flow dividing structure 1 le is attached to the inner surface ofthe visor 2. Preferably, the structure 11e includes an edge, rim or equivalent, guiding airflowto pass on either side of it. By guiding expiratory air in an upward direction while allowinginspired air to pass unhindered towards the mouth or nose of the person, the flow dividingstructure 11e def1nes a flow bifurcation point Q between the part extending upwards, and the part of expired flow moving downwards to the ambient.

Furthermore, the air passages in the flow control assembly 1, for example between thehelmet°s inner surface and the person°s skull, or in the front air channel 11b and the rear airchannel 11c, are carefully dimensioned and designed to control the flow impedances along theflow path. A more detailed description of the air flow dynamics is provided in relation to Figure 8.

The helmet 1 according to the invention preferably includes a mechanism to prevent it from being involuntarily removed from its proper position by translational or rotational movement. 14 By example, a strap band 18 is locked into position across the chin of the person wearing thehelmet with a spring latch 19 including a microswitch signaling locking or unlocking position.Altematively, the visor 2 may in the locked position be covering the chin of the person to prevent removal.

The result of a breath analysis, at least if the result indicates the existence of an intoxicatingsubstance in a concentration surpassing a predeterrnined value, is presented to the user. This isperforrned by the control and computational unit 12 engaging the communication unit 13 tocommunicate the result directly to the driver as an audio-visual waming, for example, or to areceiving unit on the open vehicle, which issue a waming, for example an audio-visualwaming to the user. Altematively, the receiving unit of the open vehicle is in connection to animmobilizer unit that upon the detection of an improper concentration of the intoxicatingsubstance hinder the ignition or tum off the vehicle if it is already running. The latter actionneeds of course to be done in a manner that does not jeopardize the safety of the driver or others.

According to one embodiment of the invention the communication unit 13 is a wirelesscommunication unit preferably using a standard protocol such as Bluetooth, Zigbee or NFCfor the communication with an extemal unit, for example a receiving unit on the vehicle. Thecommunication unit 13 may be used also for other purposes, it may for example be integratedwith a Bluetooth headset for communication with a smartphone or intercom devices.Altematively or additionally the communication unit 13 may be provided withcommunication means, for example a 4G communication unit, to communicate with telecommunication networks or other wide area networks.

Figure 3 illustrates schematically an altemative embodiment of a helmet 101 according to theinvention. The helmet 101, a so called fullface helmet, comprises a transparent part 102located in front of the eyes of the person carrying the helmet 101. The transparent part 102may be movable. The helmet 101 comprises a chin bar 120 below the transparent part 102 and partly in front of the mouth of the person.

The breath analyzing system 103 comprises a breath analyzer 106 with an inlet 116 and anoutlet 117, corresponding to the breath analyzer 6 of Figures 1 and 2, and is located on theinside of the chin bar 120. When the person emits expired air flow 104 it will directly impinge on the breath analyzer 106, whereas inspired air flow 105 will clean the area from expiratory air.The breath analyzer 106 is similar to the above described embodiments provided with an flow generating device and preferably also a pre-heater.

The air flow conditions are somewhat different in the embodiments of Figures 1 and 3, mainlydue to the different positions of the breath analyzer cavities 6b and 106, respectively. Whenthe cavity 106 is positioned right in front of the person°s mouth and nose, the air flow can beconcentrated to this region. This difference is, however, quantitative in nature, rather thanqualitative. Basically, equivalent elements of the flow control assembly 11/111 need to bepresent in both cases, including at least one active element, the flow generating device,required to ensure adequate gas exchange through the breath analyzer cavity 106 and causingan exhaust air flow 110 and at least one passive element preferably integrated with the interiorof the helmet 101. The dominating flow resistance from the preheater of the inlet of the breath analyzer 106 remains as a common element in both embodiments.

According to one embodiment the passive element of the flow control assembly 111 is a flowguiding structure 111 positioned at the inlet of the breath analyzer 106. It is designed toseparate the exhaust air flow 110 from the incoming flow 104. The edge or rim directedtowards the person°s mouth of the structure 111 def1nes a bifurcation point analogous to the flow guiding structure 1 le in Figure 1.

According to one embodiment, the full face helmet 101 is provided with a proximity sensor107 used for activating the breath analyzer system 103 analogously to the function describedin relation to Figures 1 and 2. A further proximity further sensor 107” or sensors may beprovided to indicate the position of the user's head. The embodiment of the helmet in Figure 3may further include a mechanism to prevent the helmet from being involuntarily removed from its proper position by means of a strap band 108 and a locking mechanism 109.

The breath analyzing system 3 in the embodiments illustrated in Figures 1 and 3 may beprovided with a physical casing including protective material, e g polymer foam, to minimizeimpact damage on the human skull. Altematively, the breath analyzing system 3 is made as an integral part of the protective padding of the helmet 1.

Figure 10 illustrates an embodiment of the personal protection item according to the inventionrealized as a U-shaped collar 201 designed to be attached to, or integrated with, the lowercircumference of a helmet 200. The collar 201 comprises two legs 201a; 201b provided withthrough channels 21 la; 21 lb which extends from a chin position 220 to the breath analyzer 16 206. The through channels 21 lb; 211c as well as a flow generated device 201 la provided atthe breath analyzer and an outlet channel 211d are parts of the flow control assembly. Thethrough channels 21 lb, 211c of the collar 201 represents passive elements integrated in theprotective structure and the flow generating device 21 la represents an active element. Duringuse, the air flow is actively driven from the chin position 202 through channels 210a; 21 laand then passes through a breath analyzer 206 before being emitted to the ambient air throughthe outlet channel 211d. In this embodiment, the breath analyzer 206 comprises all thenecessary elements including the breath analyzer with the breath analyzer cavity 203,proximity sensor, control, computational and communication units, and flow generating device 21 la, although not all of these elements are explicitly drawn in Figure 10.

The embodiment in Figure 10 differ from to those of Figures 1 and 3 in that the breathanalyzing system 3 being physically separable from the helmet. Therefore, the protectiveproperties of the helmet are uncompromised and can be tested independently from thepresence or absence of the system according to the invention. Furthermore, the collar-shapeddesign and position is advantageous from a flow control perspective. One advantage of thisembodiment is that the dead space between the person°s mouth and the inlet 16 of the breathanalyzer cavity 6 is minimized, which improves the system response time. Furthermore, thepositioning of the main system components at the backside of the helmet in Figure 10 is not intrusive to the person carrying the helmet.

Figure 4 illustrates the function principle of one embodiment of the proximity sensor 7, in theform of a ultra-low power proximity sensor. The sensor includes a resonator 45 illustrated asan inductor and capacitor connected in parallel. The resonating frequency is deterrnined bythe magnitude of these reactive elements, and also to some degree by the resistive loss alwayspresent. The quality factor is deterrnined by the magnitude of this loss in relation to the storedenergy in the reactive elements at resonance. Using the piezoelectric effect, electromechanicalresonating elements may be combined with electromagnetic elements. More specif1cally,quartz resonators allow a quality factor of 106 or even higher to be obtained which ispreferable, both from the point of view of sensitivity and of power consumption. The resistiveloss and the resonance frequency is influenced by the presence of conductive tissue 48, forexample a human skull, in the proximity of the resonator. An oscillator circuit 46 isconf1gured to oscillate at the resonance frequency of the resonator, and a trigger circuit 47 is detecting small shifts of the oscillating frequency, and its output signal is used for switching 17 the system from the inactive mode into an active mode of operation as described above andfurther discussed below with reference to the flowchart of Figure 8. The total powerconsumption of the ultra-low power proximity sensor according to the invention is less than uW.

Figure 5 shows one embodiment of the breath analyzing system 3 according to the inventionadapted to be used to perrnit a sober person wearing a helmet to drive a motorcycle whilepreventing an intoxicated person to do the same. The system is adapted to also prevent drivingwithout a helmet. The system includes one helmet node 51 and one motorcycle node 58 (withmutual two-way, wireless data communication.

The helmet node 61 is basically configured in the same way as was previously described inrelation to Figure 2. It includes a control and computational unit 52, a data communicationunit 53, a power control unit 54, a flow control assembly 55 with at least one active elementcontrollable by the control and computational unit 52, a breath analyzer 56, and a proximitysensor 57. These units correspond to the units 12, 13, 14, 15, 16, 17 in Figure 2.

The open vehicle node 58 includes one data communication unit 51 configured for two-waywireless data communication with the helmet node 51 following Bluetooth, Zigbee, or otherstandards for short-range wireless data communication. Also included is a control andcomputational unit 59 comprising a standard microcontroller with intemal memory andprogramming capabilities. The sensor unit 60 may include sensor elements to establish theexact position of the vehicle, its speed and other entities of interest, for example based on theGlobal Positioning System (GPS). A power control unit 62 is also included. This may controlboth the open vehicle node 58 and remotely also the helmet node 51 when this is in a “sleeping mode” as described in relation to Figure 2.

The open vehicle node 58 may also include an immobilizer unit 63 which is basically a switchconfigured to enable or disable driving or the open vehicle by controlling the ignition, thesteering or other critical functions of the open vehicle. The immobilizer 63 is controlled by the control and computational unit 59.

The “smart helmet” described with reference to Figure 5 may be extended to include alsoother sensors and functions. As described, the proximity sensor 57 can be used not only toactivate the system, but also to ensure that the driver actually wears the helmet, in that the control and communication unit of either the helmet or the open vehicle is arranged to not 18 activate the immobilizer unit if and only if both the proximity sensor 57 signals that thehelmet is wom and that one or more intoxicating substance is below a predeterrnined value.Further sensors may be utilized. It is for example plausible that, depending on the design ofthe helmet, the visor 2 or transparent part 102 has to be in a downward position in order toprovide for a stable and predictable airflow to the breath analyzer 6, 106. In that case a visorsensor could sense the position of the visor and ensure that the visor is in the correct positionfor the breath analysis. Altematively, the inforrnation from the visor sensor could be used toinfluence the flow control assembly 11 to change the settings depending on the indicationsfrom the visor sensor. Biometric devices could also be incorporated in the system to ensurethe correct identity of the driver. Bluetooth communication offers a way to gain knowledge ofthe distance between two communicating units, inforrnation that could be used to activate thebreath analysis procedure only if the driver is actually on, or in close vicinity to, the open vehicle.

Figure 6 describes, by means of example, the logic circuitry controlling the switching of thebreath analyzing system 3 to and from active and standby mode, respectively according to oneembodiment of the invention. The overruling principle is to establish the occupancy andsecured position of the helmet with reasonable certainty. The occupancy should in tumdetermine if and when the system should be activated. In some applications when carrying ahelmet is mandated by law or other means, it is important that the deterrnination of occupancyis reliable. Employing a plurality of independent indicators 81, 82, 83 is an arrangement toachieve this, wherein one indicator 83 corresponds to the above described proximity sensor 7, preferably an ultra-low power proximity sensor.

The circuitry includes a plurality of digital indicators 81, 82, 83 whether or not the helmet iswom in a secure way by a user. The electromechanical switches 81 and 82 will close bycontacting or by movement when the helmet is taken on, thereby being switching from “low”to “high°. One of the switches 81, 82 can be activated by the visor (2 in Figure 1), and anotherswitch one could, for example, be activated by a strap to secure fastening of the helmet to theskull. A further altemative is that the helmet may be provided with one or more vents thatoften can be manually opened or closed in order to regulate the ventilation of the helmet. Theswitches 81, 82 may be associated with the vents and indicated a position of the vents that issuitable for the breath analysis to be performed, for example and typically the vents being in a closed position. Via the communication unit 13 and the communication unit 13 the driver may 19 be inforrned to take the necessary actions to get the switches in the required positions for thebreath analysis to be performed. The output of the proximity sensor 83 will correspondinglygo from ”low” to “high° when the presence of a human skull is detected, as previouslydescribed in relation to Figures 1-2. A timer circuit 84 is receiving signals from the switches81, 82 and the proximity sensor 83 and is programmed to provide a “high” signal if thesesignals occur in a correct sequence according to a preprogrammed schedule. In its simplestimplementation, this schedule is the order in which the switches 81, 82 and/or the proximitysensor 83 are indicating occupancy. The schedule could altematively involve other logicalfunctions. The output of the logical “AND° gate 85 will go from “low° to “high° when andonly when the signals from the switches 81, 82, the ultralow power proximity sensor 83 andthe timer 84 all are “high°. Then the system according to the invention will tum from standbyto active mode. The circuit elements of Figure 6 are preferably comprised of CMOS switcheswith extremely low power consumption both in their static “high” and “low° conditions, andwhen switching between these conditions. The total power consumption of this control circuit will not exceed 1 uW.

Figure 7 shows a simultaneous recording of C02 concentration (top graph) and theconcentration of ethyl alcohol representing an intoxicating substance (bottom graph). Threeconsecutive high C02 concentration peaks 71, 72, and 73, occur with a few seconds intervalwith the concentration retuming to a minimum reading 74 in between. The peaks coincidewith alcohol concentration peaks 75, 76, 77 compared to the minimum reading 78. Thedifference between maxima and minima of C02 readings is used for estimating the dilution ofthe recorded peak concentrations based on the physiologically defined alveolar C02concentration of approximately 4.2 vol%. An estimate of the alveolar intoxicating substanceconcentration is then calculated from the measured substance peak concentration difference and the dilution.

Response time of the breath analyzing system 3 according to the invention is considerablyshorter than one second or the time interval between two breaths. The airflow controlfacilitated by the breath analyzing system 1is such that the time of gas transportation and exchange is considerably shorter than one second or the time interval between two breaths. 0ne intoxicating substance the breath analyzing system 3 according to the invention could be arranged to detect is ethyl alcohol. 0ther substances include, but is not limited to opiates, cannabis and various pharrnaceutical compounds known to affect the ability to handle a vehicle.

Figure 8 is a circuit model of the air flow control assembly 11 according to the invention.Circuit modelling of this kind is customary to describe the behavior of interconnected passiveand active elements in electronics, pneumatics, hydraulics, and acoustics (see e g R. T.Weidner, R. L. Sells Elementary Classical Physics, Allyn and Bacon, 1965, pp. 753-780, 901-931). The model in Figure 8 includes the respiratory air flow generated by the person wearingthe helmet, and the circuit elements of the flow control assembly 11. The active element Gr isrepresenting the person°s respiratory, bidirectional flow. At rest the flow rate is typically 0.5liters per breath, both at expiration and inspiration. The duration of one expiration is typicallyone second. The other active element Gf is the flow generating device driving air through thebreath analyzer cavity 6, typically at a constant rate of 0.3 liters per second across a pressuredifference of 50 Pa. The volume of the breath analyzer cavity 6, 106 is typically less than 0.02liters, with physical dimensions 60 x 30 x 10 mm. The transit time of air through the cavity istherefore typically 0.02/0.3 = 0.067 seconds. Flow generating devices of this kind areavailable from several manufacturers, including SEPA GmbH, Germany, operating in bothaxial and radial modes, and having dimensions smaller than 45 x 45 x 5 mm. The embodimentshown in Figure 3 will not require as high capacity as that in Figure 1. Therefore, the flow generating device in the Figure 3 embodiment may be smaller.

The two active elements Gr and Gf are interconnected as illustrated by the circuit diagram inFigure 8 by passive flow impedances which are either resistive or capacitive. The magnitudeof the resistive elements is proportional to their length and inversely proportional to theircross-section area. The magnitude of capacitive elements is proportional to their volume.

A critical condition of the flow control assembly is to provide adequate coupling between therespiratory generator Gr to the measuring circuit arm defined by the transfer impedancesRr1//Cr1 and Rr2//Cr2, the preheater resistance Rrr, the breath analyzer cavity CC, and the flowgenerator Gf. Rh constitutes the dominating resistive element of typically 1.5 * 105 Pa/m3/s.The transfer impedances Rr1//Cr1 and Rrg//Crg are dominated by their reactive constituents Cr1,Cr; compared to the resistive parts Rr1 and RQ. Typically, the total transfer volumes range from0.05 to 0.2 litres. The smaller number refers to the embodiment in Figure 3, whereas theembodiment in Figure 1 is represented by the larger number. In both cases, the mean transit time is less than one second. 21 The establishment of a well-defined flow bifurcation point Q is critical to provide adequatedivision of air flow between the measuring arrn to the right-hand side of Gr, in Figure 8,compared to the shunting left-hand side. If the shunting impedance RS//CS is very small, it willeffectively short circuit the measuring arrn, and the signal output will be inadequate. Thephysical implementation of a bifurcation is exemplified by the flow guiding structure 11e shown in Figure 1 and 104 in Figure 3.

The present sensor technology can accept a dilution of 1:10 corresponding to 90% shunting ofthe generated breath flow through RS//Ca This condition can be met in the embodimentsdescribed in Figures 1 and 3 by inclusion of flow guiding structures for flow path separation,adequate definition of bifurcation points, and using a spacing of 10 mm between the skull andthe inner helmet surface. The latter criterion is also based on a further condition that theperson°s respiratory gas exchange shall not be hampered by an excessive flow impedance.The response time to is deterrnined by the equation to = RhCC = 0.03 seconds according to thenumerical data provided above, less than half the transit time. Both numbers are consistent with a required total response time of less than one second.

Figure 9 is a flowchart over the method of performing breath analysis suitable for drivers ofopen vehicles according to the invention using the sensor system according to the invention.

The method comprises the steps of: 805: Inactive mode. The breath analyzing system is in an inactive mode characterized by thatonly one sensor/indicator or indicator or a limited set of sensors/indicators, referred to as the proximity sensor 7, is actively in a detecting mode 810: Detecting breath analyzing conditions. If the proximity sensor 7 is activated by detectingthat the user is using the personal protection device 1, 101, 201 in a correct manner, forexample detecting the presence and position of a human skull within the helmet 1 or thatcollar 201 is correctly positioned around the neck, the system is tumed from an inactive modewith very low power consumption into an active mode, step 815. If not, the system remains ininactive mode.

The system going to active mode may require a plurality of actions/ events or a combination ofsuch actions/ events, which are referred to as triggers: a) the proximity sensor 7 detects that a person is wearing the personal protection device 1, 101, 201; 22 b) the visor 2 is in a closed position as sensed by a visor indicator 81; c) the strap of the helmet is closed as sensed by a strap indicator 82; c) communication units, or other units, indicating that the personal protection device 1, 101,201 is close to the open vehicle; d) during operation initiate breath analysis at predeterrnined time intervals; e) verifying the identity of the driver, for example using biometric data. 815: Active mode and Initiating respiratory activity. The control and computational unit 12sets the breath analyzing system to an active mode and activates the breath analyzer 6 and theflow generating device 1 la of the flow control assembly 11. The breath analyzer 6 in response outputs a representation of measured data to the control and computational unit 12. 820: The control and computational unit 12 receives and analyzes the representation ofmeasured data from the breath analyzer 6. Respiratory activity is detected by the tracer gasresponding element of the breath analyzer 6 as an expiratory peak of tracer gas, e g C02, orH20. The output of the breath analyzer element responding to the intoxicating substance indicates whether intoxicating substance is present in the expiratory airflow from the driver. 825: Substance detection. If the estimated breath concentration of a selected intoxicatingsubstance exceeds a predeterrnined value, an alarm is activated, step 830. If on the other handthe estimated breath concentration of the intoxicating substance is lower than the predeterrnined value, the system retums to an inactive mode, step 835. 830: Alarm. The driver is inforrned of the result that the estimated breath concentration of aselected intoxicating substance exceeds the predeterrnined value, for example by an audio-visual signal. The signal may be issued by the communication unit 13 of the helmet 1, oraltematively the communication unit 13 communicates with a receiving unit of the open vehicle, which issues the alarm. 831: Prohibit driving: In an optional step or as altemative to, or in combination to the alarm ofstep 830, an immobilizer unit of the open vehicle is activated via the communication unit 13 and a receiving unit of the open vehicle.835: retum to inactive mode. The breath analyzing system is tumed into the inactive mode.

The method may also comprise the steps of: 23 840: Time limit. If repeated breath tests are utilized, the procedure is repeated after apredeterrnined period of time, during the waiting time the system remains in the inactive mode, step 810.

As realized by the skilled person, certain steps in the method can be performed in variousunits. For example, the computation of the measured result may be performed by acomputational unit on the open vehicle instead of being performed in a computational unit of the helmet. In that case all “raw data” is transferred to the open vehicle unit.

The step of tuming to active mode and initiating respiratory activity, step 815, may include apre-step of activating the active element of the flow control assembly 11 to give a stable flow of air, including expiratory air, through the sensor module.

Upon detection of a selected intoxicating substance exceeding a predeterrnined value a secondbreath analysis may be initiated before issuing the alarm in order to minimize the risk for theresult being a faulty measurement. As a complement to having a predeterrnined value that isnot allowed to surpass, a range below that predeterrnined value could result in a milder formof alarm, for example if linked to a immobilizer, the immobilizer is not activated but thedriver is inforrned about the existence of the intoxicating substance. A concentration of anintoxicating substance in a range below the predeterrnined value could also trigger a more frequent repetition of the breath analysis.

The embodiments described above are to be understood as illustrative examples of the systemand method of the present invention. It will be understood that those skilled in the art thatvarious modif1cations, combinations and changes may be made to the embodiments. Inparticular, different part solutions in the different embodiments can be combined in other configurations, where technically possible.

Claims (1)

1. 24 Claims . A personal protection device (1, 101, 201) comprising a breath analyzing system (3) comprising a breath analyzer (6, 106, 206), a proximity sensor (7, 107), a control andcomputational unit (12) and a communication unit (13) , the breath analyzer (6, 106,206), the proximity sensor and the communication unit (13) arranged to be incommunicative connection with the control and computational unit (12)characterized in that -the breath analyzing system (3) comprises a flow control assembly (11) comprising atleast one active element (11a, 211a) and one passive element, providing a gascommunication channel from the mouth and/or nose of a user wearing the helmet (1 ,101) to an inlet (16) of the breath analyzer (6, 106, 206) and through the breathanalyzer (6, 106, 206); -the breath analyzing system (3) having a low power inactive mode and an activemode; -the proximity sensor (7, 107) is arranged to detect the presence of a human skull inthe helmet (1), the proximity sensor (7, 107) operable during the inactive mode of thebreath analyzing system (3); -the control and computational unit (12) adapted to react on an input from theproximity sensor (7, 107) and initiate a change to active mode of the breath analyzingsystem (3) and activate the breath analyzer (6, 106, 206) and the active element (11a,211a) of the flow control assembly (11); -the breath analyzer (6, 106, 206) arranged to, on receiving an activation from thecontrol and computational unit (12), perform a breath analysis and transmit arepresentation of the breath analysis to the control and computational unit (12); -the active element (11a, 211a) of the flow control assembly (11) arranged to provide acontinuous transport of air from the user wearing the helmet to an inlet 16 of the breath analyzer (6, 106, 206) at least during the breath analysis. . The personal protection device (1, 101, 201) according to claim 1, wherein at least one passive element of the flow control assembly (11) is formed as an integrated part of the protective structure of the personal protection device (1, 101, 201). 10. The__personal protection device (1, 101, 201) according to claim 2, wherein the flowcontrol assembly (11) comprises at least one channel (11b, 11c, 211b, 221c) forexpiratory air forrned in the protective structure of the personal protection device (1,101, 201), wherein the channel is open on the side configured to face the user so that during use that side of the channel is forrned by the head of the user . The personal protection device (1, 101, 201) according to any of claims 2 to 3,wherein flow control assembly (11) comprises at least one flow guiding structure(11d, 111) positioned so that it will be close to the mouth of a user wearing thepersonal protection device (1, 101, 201) and having a ridge facing the mouth to form a bifurcation of the airflow into the mouth/nose and the airflow out of the mouth/nose. The personal protection device (1, 101, 201) according to any of the preceding claims,wherein the control and computational unit (12) is arranged to analyze therepresentation of the breath analysis and compare with at least one predeterrninedvalue of an intoxicating substance, and if the predeterrnined value is exceeded activate the communication unit (13) to issue an alarm. The personal protection device (1, 101, 201) according to any of the preceding claims, wherein the proximity sensor (7, 107) is a ultra-low power proximity sensor. The personal protection device (1, 101, 201) according to claim 6, wherein the ultra- low power proximity sensor (7, 107) is a capacitive or an inductive proximity sensor. The personal protection device (1, 101, 201) according to claim 6, wherein the ultra- low power proximity sensor (7, 107) is a mechanical switch. The personal protection device (1, 101, 201) according to any of the preceding claims,further comprising at least one second sensor arranged to detect a condition associatedto the usage of the helmet (1), and the control and computational unit (12) beingoperable in a low power stand-by mode monitoring an input from the proximity sensor(7, 107) and the at least one second sensor; and upon input from the proximity sensor proximity sensor and the second sensor activate the breath analyzer. 11. 12. 13. 14. 15. 16. 17. 18. 26 The personal protection device (1, 101, 201) according to claim 9, wherein the at least second sensor is a switch detecting the position of a visor (2). The personal protection device (1, 101, 201) according to any of the preceding claims,wherein the said breath analyzing system is encased and provided with protective material. The personal protection device (1 , 101, 201) according to any of the preceding claims,wherein said breath analysis includes the computation of the difference betweenmaximal and minimal readings during a breath cycle of a substance and a tracer signal, said tracer signal representing the concentration of carbon dioxide: The personal protection device (1, 101, 201) according to claim 1, wherein saidtransfer from inactive to active mode of operation being further conditioned on thelocking of a mechanical mechanism (19, 109) preventing said helmet from being involuntarily removed from said skull by translational or rotational movement. The personal protection device (1, 101, 201) according to any of the preceding claims,wherein the flow control assembly (11) includes flow impedances which are eitherresistive or capacitive and wherein the resistance is dominated by the air flow througha preheater provided in the flow control assembly (11), the preheater resistance Rh,and the capacitance by the breath analyzer cavity capacitance CC, and the responsetime to is deterrnined by the equation to = RhCC and wherein the response time to is less than one second, and preferably less than 0.5 second. The personal protection device (1, 101) according to any of claims 1 to 14, wherein the personal protection device (1, 101) is a helmet. The personal protection device (201) according to any of claims 1 to 14, wherein thepersonal protection device (201) is an attachment configured to be attached to a helmet. The personal protection device (201) according to any of claims 1 to 14, wherein thepersonal protection device (201) is a collar configured to be attached to a helmet (200). 19. 20. 21. 22. 27 A method of performing breath analysis suitable for drivers of open vehicles by theuse of a personal protection device (1, 101, 201) comprising a breath analyzing system(3) comprising a breath analyzer (6, 106, 206), an proximity sensor (7, 107), a controland computational unit (12), a i) and a communicationmodule (13), the method comprising the steps of: - (805) keeping the breath analyzing system in an inactive mode Wherein only theproximity sensor (7, 107) is actively in a detecting mode; - (810) tuming, if at least the proximity sensor (7, 107) indicates that the personalprotection device (1, 101, 201) is Wom by a user, the breath analyzing system (3) froman inactive mode into an active mode, and if not, the breath system remains in inactivemode; - (815) the control and computational unit (12), in the active mode, activating thebreath analyzer (6, 106, 206) and the active element (1 la, 21 la) of the east: the breath analyzer (6, 106, 206) in response outputs a representationof measured data to the control and computational unit (12); - (820) the representation of measured data is analyzed by the control andcomputational unit (12); - (825-840) if the estimated breath concentration of a selected intoxicating substanceexceeds a predeterrnined value, at least an alarm is activated (830), and if the estimated breath concentration of the intoxicating substance is lower than the predeterrnined value, the system retums to an inactive mode (835). The method according to claim 18, Wherein the step of tuming the breath analyzingsystem (3) from an inactive mode to an active mode (810) further comprises receivingand analyzing the input from a plurality of sensors or indicators and only if the inputfrom the plurality of sensors or indicators corresponds to a predeterrnined scheme tum the breath analyzing system (3) from the inactive mode to the active mode. The method according to claim 19, Wherein the personal protection device (1 , 101,201) is a helmet and the predeterrnined scheme comprises the visor (2) of the helmet (1) being in a closed position. The method according to claim 20, Wherein in the step of activating the breath analyzer (815), comprises a pre-step of activating the active element (1 la, 21 la) of the 23. 24. 25. 26. 28 flow control assembly (11) before activation of to give a stable flow of air, including expiratory air, through the breath analyzer (815). The method according to any of claims 18 to 21, Wherein in the air transport from theusers mouth/nose to the breath analyzer (815) is effectuated With a time delay considerably shorter than one second. The method according to any of claims 18 to 22, further comprising a step ofimmobilizing (831) the open vehicle if the estimated breath concentration of a selected intoxicating substance exceeds a predeterrnined value (825). The method according to any of claims 18 to 23, Wherein said breath analysis includesthe computation of the difference between maximal and minimal readings during abreath cycle of a substance and a tracer signal, said tracer signal representing the concentration of carbon dioxide. The method according to any of claims 18 to 24, Wherein said transfer from inactive toactive mode of operation being further conditioned on the locking of a mechanicalmechanism (19, 109) preventing said personal protection device (1, 101, 201) frombeing involuntarily removed from its correct position on a user by translational or rotational movement.