Process and measuring probe for the determination of ice or snow formation

Claim 1

A measuring probe for determining the presence of ice or snow at a sensed region, said probe including an electrical circuit comprising: an electrical power supply, thermal switch means for assuming a switch-off position in response to reaching a switch-off temperature and for assuming a switch-on position in response to reaching a switch-on temperature lower than said switch-off temperature, a cold conductor exposed to said sensed region and disposed adjacent said thermal switch means for heating the latter at a first rate when said cold conductor is not exposed to snow or ice and at a slower second rate when said cold conductor is exposed to snow or ice, said first rate being sufficient to heat said thermal switch means to said switch-off position within a given time period, and said second rate being insufficient to heat said thermal switch means to said switch-off position within said time period, whereby the inability of said thermal switch means to assume a switch-off position within said time period is indicative of the presence of ice or snow, control means for disconnecting said cold conductor from said electrical power supply in response to said thermal switch means assuming said switch-off position to thereby terminate the heating of said thermal switch means by said cold conductor, and for connecting said cold conductor to said electrical power supply in response to said thermal switch means assuming said switch-on position, to thereby resume heating of said thermal switch means by said cold conductor, and means actuated in response to said thermal switch means remaining in a switch-on position at the end of said time period.