Classifications

• • G—PHYSICS
  • G08—SIGNALLING
  • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
  • G08C17/00—Arrangements for transmitting signals characterised by the use of a wireless electrical link
  • G08C17/04—Arrangements for transmitting signals characterised by the use of a wireless electrical link using magnetically coupled devices

Definitions

• the object of the invention is an arrangement for the detection of ambient conditions and changes therein, for example detecting factors of interest, such as moisture, tem- perature, mechanical stress, and the like, e.g. moisture in the structures of buildings and in diapers of infants and chronics. Other applications involve temperatures above or below allowed limits, movement in structures due to e.g. fatigue of materials, etc.
• factors of interest such as moisture, tem- perature, mechanical stress, and the like, e.g. moisture in the structures of buildings and in diapers of infants and chronics.
• Other applications involve temperatures above or below allowed limits, movement in structures due to e.g. fatigue of materials, etc.
• Moisture damage to buildings has been found to be quite common. Moisture damages occur in as many as 55% to 90% of residential buildings. Visible mould fungus is found in approximately one third of the houses built after 1950. Mould fungus spores have been found to be highly allergenic. Various studies have estimated that as many as 50% of asthmatic persons are allergic to moulds. Mould spores also increase the sus ⁇ ceptibility of exposed persons to catch respiratory diseases caused by viruses and bacteria.
• the arrangement according to this invention enables the detection of changes in ambi ⁇ ent conditions, and the solving of problems similar to those described above.
• - Fig. 1 shows an arrangement according to the invention, with a transducer device and a detection unit
• - Fig. 2 shows different embodiments of the transducer device
• FIG. 3 shows the connection of a possible embodiment of the detection unit
• FIG. 4 shows the operating sequence of the detection unit and the detection signals in two different cases
• FIG. 5 shows the use of an arrangement according to the invention in monitoring a bed-patient.
• TC is a transducer device, which can be a resonance circuit formed by a capacitance and an inductance and oscillating at a specific frequency fi.
• DU is a detection unit, which may be hand-held, containing, associated with the operation, an operating control OC, which can be e.g. a push-button, and further containing indication devices, for example SI is a sound indicator and VDI is a visual indicator device such as a signal light (lamp, light- emitting diode, liquid crystal display, or the like.).
• the detection unit can be connected through wires or wirelessly to a central unit in a control room, or through a telephone device to wireless pagers, a radio telephone apparatus (e.g. GSM, NMT), etc.
• Fig. 2 shows some embodiments of transducer TC.
• TC can contain a resonance circuit consisting of a coil L and a capacitor C.
• the compo ⁇ nents L and C can be implemented e.g. with the same technology as transducer com ⁇ ponents in modem burglar alarms.
• Such solutions and also solutions associated with the implementation of detection units are shown e.g. in reference US 5,381 ,137. These solutions can be applied in arrangements according to the present invention.
• the transducer circuit may have one or more sensing elements SE.
• SE is a thin metal foil, which short-circuits several turns of coil L. If foil SE breaks or is gradually displaced due to e.g.
• Fig. 3 shows a possible connection of the DU detection electronics.
• the Figure shows only a part of the electronics in DU. For instance power sources, display components, audio signal components, and any components associated with external central units are not shown.
• EDC is a coil into which pulse generator PG, controlled by the GATE signal, applies a current pulse through amplifier EA.
• the rapidly rising edge of the cur ⁇ rent pulse starts an oscillation in the nearby transducer(s) TC (not shown in Fig. 3) at its/their specific frequency/frequencies.
• This oscillation induces in EDC a signal which is connected through capacitor C to pre ⁇ amplifier PA and band-pass amplifier BPA. After BPA there is a peak detector, which during the pulse is reset under the control of the GATE signal.
• the oscillation is de ⁇ tected by comparator COMP. If the amplified signal exceeds the reference level VREF, a detection signal DTS is transmitted.
• the Figure shows only one of the possible em- bodiments.
• the protection scope of the invention includes also other possible em ⁇ bodiments, in which the VREF can be automatically regulated, for instance.
• EDC may also be a resonance circuit whose loading situation is sensed by associated electron ⁇ ics, as described in reference US 5,381 ,137.
• DU may identify the TC signal on the basis of its specific frequency, or DU may include means for computing the frequency spectrum of the signal emitted by TC using e.g. a Fourier transformation or some other spectrum-analysis method, such as autoregres- sive algorithms or wavelet transformations. DU may also include storage means to record the received signal and/or the informa- tion derived therefrom, for possible later examination. In this case means can be added to DU to record also the identification of the detection location, for instance wirelessly with TIRIS equipment manufactured by Texas Instruments (USA), or with some other wired or wireless technology.
• Figs. 4a and 4b show, with reference to Fig. 3, an operation sequence (detection se ⁇ quence).
• TC TC oscillates for a long time at its specific frequency, because the quality factor (Q-factor) of the cir ⁇ cuit is good.
• Q-factor quality factor of the cir ⁇ cuit
• DTIME a strong signal is detected.
• the resonance circuit of TC is loaded, as urine is a good con- ductor of electricity, and the quality factor (Q-factor) of the resonance circuit in TC be ⁇ comes very small.
• the oscillation ceases quickly already during the GATE signal, and no notable signal is detected during the detection time DTIME.
• DU can with ⁇ out effort be used to check whether a need exists for changing the diaper.
• Another way of detecting the status of TC is to use an initiating pulse at a varying repe ⁇ tition frequency. Then, within a certain repetition frequency range, the output signal strength of TC varies at the frequency of the initiating pulse. This happens because successive initiating pulses occur in different phases of the TC oscillation, and the ini ⁇ tiating signal is strengthened and damped by successive pulses. The larger the repeti- tion range where variation can be detected, the poorer is the Q-factor of TC.
• Fig. 5 shows schematically an arrangement according to the invention, where DU is attached for example to a bed or a perambulator PB, the DU energy exchange means EDC, which can be a conductor loop, can be placed under or inside the mattress MT to improve sensitivity.
• EDC which can be a conductor loop
• TC which is not drawn in the Figure, is located in a place such as the diaper or clothes of the person P lying on the bed.
• DU is connected through signal transmission STM to a central observation unit COU.
• STM may be a wired or wireless connection.
• STM may include a telephone, radio, ultrasound, light (infrared), or other conceivable communications devices.
• COU can be in contact with many DUs. Then means can be provided in each DU for transmitting identification information to allow
• COU to identify the DU transmitting the information.
• COU may also contain means for monitoring and controlling other quantities. Such quantities may be blood pressure, EKG or movements of P detected by means (e.g. piezoelectric material) provided in mattress MT to convert movements into electric signals.
• the central observation unit COU is an entity generally associated with observation. It may therefore comprise separate display devices, central units and their controls. Further ⁇ more, the central observation unit COU may consist of many hierarchic units which form a larger network. Such a network can give the first alarm for example in a local unit, which e.g. in a hospital could cover a single ward, but unless no response is made to the alarm within a preset time, the local unit retransmits the alarm to the hospital's on-duty central control.
• An application example is the checking of whether a baby diaper should be changed.
• DU can be placed in the baby's cot or perambulator.
• DU detects the need to change, from the TC in the diaper, DU sends for example a radio signal to COU, which in turn gives an audio signal to inform the parents.
• COU can be battery-operated for easy moving and safe use.
• DU can make the detection se- quence when desired or every ten minutes, to save the battery.
• DU can contain also means to detect the baby's sounds, movements, or e.g. outsiders coming near the baby.
• DU can send an alarm signal also in such cases.
• the design of TC can be simple, because the good electrical conductivity of urine weakens greatly the Q- factor of the resonance circuit in TC.
• a DU can be provided for a given bed and connected to the central observation unit COU, which may also receive other observation information.
• COU central observation unit
• Such type of operation is illustrated in Fig. 5.
• the nurse making her rounds in the wards has a port- able DU for finding out individual needs of diaper changing.
• TC can be similar to the one in the previous example.
• a tape-formed TC with an adhesive surface can be used.
• Such adhesive-tape TC can be fastened to structural locations where moisture damage is probable, e.g. under the bathroom floor, beside the piping for underfloor heating, and in kitchen structures.
• SE element which by an electrochemical process alters some characteristic of TC, e.g. the resonance fre- quency or the Q-factor. Then TC reacts permanently to long-term moisture only.
• Sensitivity can be regulated by the choice of the types and quantities of the metals in the SE.
• the response of TC to short-duration increases in of moisture by e.g. a reduc ⁇ tion in the Q-factor of its resonance circuit.
• TC can be built inexpensively with thin metal foils, it can be made disposable. TC can be placed in the diaper so that it will not be in contact with the skin. Material with a high capacity of absorbing moisture can be placed on the TC coil to improve functional reliability.
• an adhesive tape with a number of TC cir- cuits can be used.
• SE is made electrochemically more active than the metal used in coil L. In the presence of moisture such SE gradually coats L, and the resonance frequency of TC changes.
• the advantage of such a detector is that only long exposure to moisture causes the state of the TC circuit to change.
• salts can be dissolved in the TC materials to improve the con ⁇ ductivity caused by moisture.
• the SE can also be a component made of a bimetal or of a form-retaining metal, which changes shape according to temperature and at the same time changes the TC circuit either temporarily or permanently.
• SE can also be made of an alloy which melts at a specified temperature. Such metals are used for example in automatic fire-extinguishing systems.
• Breaks or movement in structures can be detected by a TC for example when the TC is taped over structural joints or points subject to stress. Then a movement in the struc ⁇ ture breaks the TC circuit.
• the breaking of TC can be assisted by e.g. spring assem ⁇ blies triggered by a sufficient load to open the TC circuit.
• the object of the in ⁇ vention is a system in which a detection unit DU transmits energy to a transducer TC, which returns a part of the received energy to the DU, and characteristics of the re- turned energy, in the case of electromagnetic energy characteristics such as fre ⁇ quency, amplitude, phase and duration of transmission, are affected by the ambient conditions of the TC.
• the invention can be used to help a visually handicapped person to find nec- essary objects, such as a wallet, controls of appliances, etc. in his surroundings.
• a TC is attached to the object, and the visually handicapped person can use a DU find the object e.g. on a table or in a cupboard.
• the sensitivity of the DU can be adjusted to improve the locating accuracy when nearing the object.
• Different ob ⁇ jects can have their own TCs with specific resonance frequencies. The search can therefore be selective.
• the invention can be used to help locating objects, e.g. electrical panels installed under panelling or other surfacing materials.
• An advantage of the invention is that coil L or capacitor C can be used as the actual sensing element.
• the components of the resonance circuit can be connected to the observed object, for example a structure or a diaper, through electric conduction, a magnetic field (mainly coil L) or an electric field (mainly capacitor C).
• a magnetic field mainly coil L
• an electric field mainly capacitor C

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• Physics & Mathematics (AREA)
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Cited By (2)

Citations (5)

• 1995
  • 1995-07-18 FI FI953465A patent/FI100138B/fi active
• 1996
  • 1996-07-18 WO PCT/FI1996/000416 patent/WO1997004430A1/en active Application Filing

Patent Citations (5)

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