Nova Patents
SE519289C2

Safety device for preventing fingers being trapped in furniture with motor driven components, comprises twin conductor generating capacitive electric field

Abstract

The safety device comprises a twin conductor with two input conductors formed by thin, electrically conducting metal strips lying side by side or symmetrically one above the other. The strips are separated by a thin, insulating dielectric medium. When the motor is activated, the conductors are connected to a weak low voltage alternating current, which flows around, over and along the free sides of the twin conductor to create a symmetrical capacitive alternating current field. The symmetry, capacitance and integrity of this field are locally altered (9) if a body part or finger (8) with an intrinsic capacitance approaches the region (10) where there is a risk of it becoming trapped or comes into direct contact with the twin conductor. This variation is processed using standard electronic techniques, so that the motor is immediately stopped and/or put into reverse. The automatic safety device can be secured to any dangerous surface on the fixed and/or movable sections (7) of the furniture.

SE519289C2, drawing sheet 1
Sheet 1 of 2

Term

No projected expiry on record.

  1. Priority and filed
  2. Granted
  3. Today

1 claim: 1 independent, 0 dependent

  1. 1
    Clamp protection device based on a double conductor (1) isolated from the environment and intended as automatic clamp protection in motorized, person-loaded or unloaded furniture of the type beds, armchairs, patient tables, etc., and mounted (4) against and along all dangerous surfaces on the furniture structure's fixed and / or movable structural members (6,7), which when any of them are set in mechanical motion by a drive motor, may present an obvious risk of personal injury, characterized in that both conductors (1) of the double conductor (1) are designed as very thin electrically conductive metal strips placed wide side to wide side over each other and with their longitudinal edges exactly coincident, or symmetrically coincident along their center lines, and separated from each other by a thin insulating dielectric layer (3) and that, at the same time as the drive motor is started, also the two conductors (2) are connected to a weak low-voltage alternating current to create a constant and symmetrical alternating field (5), which radiates from the two edges and around the free side along the entire length of the double conductor (1), and that the smallest measurable change in the capacitance and / or goodness number of the double conductor, arising from a body part or a finger (8) approaching the danger area (10) or touching the double conductor (1) and thereby causing its gear field (9) to locally deflect and become asymmetrical, is used as a signal to be converted to automatically and immediately stop and / or reverse the drive motor, until the body part has been removed from the danger area (10) and the drive motor and the clamp protection device can be restarted. 1. Klämsky ddsnordning utgående från en från omgivningen isolerad dubbelledare (1) och avsedd som automatiskt klämskydd i motordrivna, personbelastade eller obelastade möbler av typen sängar, fåtöljer, patientbord, m.m., samt monterad (4) mot och längs med alla farliga ytor på möbelkonstruktionens fasta och/ eller rörliga konstruktionsdelar (6,7), som när någon av dessa sätts i mekanisk rörelse av en drivmotor, kan utgöra en uppenbar risk för personskada, kännetecknad av att dubbelledarens (1) båda ledare (2) är utförda som mycket tunna elektriskt ledande metallband placerade bredsida mot bredsida över varandra och med sina längsgående kanter exakt sammanfallande, alternativt symmetriskt sammanfallande längs sina centrumlinjer, och åskilda från varandra genom ett tunnt isolerande dielektrikumskikt (3) och att, samtidigt med att drivmotom startas, även de båda ledarna (2) ansluts till en svag lågspänd växelström för att skapa ett konstant och symmetriskt växelfält (5), som strålar ut från de båda kanterna och runt den fria sidan utmed hela dubbelledarens (1) längd, samt att minsta mätbara förändring i dubbelledarens kapacitans och/eller godhetstal, uppkommet genom att en kroppsdel eller ett finger (8) närmar sig riskområdet (10) eller berör dubbelledaren (1) och därigenom får dess växelfält (9) att lokalt böja av och bli as symmetriskt, används som signal att omvandlas till att automatiskt och omedelbart stoppa och/eller reversera drivmotom, tills kroppsdelen tagits bort från riskområdet (10) och drivmotor och klämskyddsanordning kan återstartas.