Patent ID: 11928846
Assignee: ESSITY HYGIENE AND HEALTH AKTIEBOLAG
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 9:
10. A device for detecting presence and absence of a creature, the device comprising processing resources that are adapted to:
receive an input signal from a radiation sensor;
apply a first low-pass filter to the input signal with a first time constant and to generate a first filter output;
apply a second low-pass filter to the received input signal with a second time constant and to generate a second filter output;
determine a presence of a creature by comparing a slope of the first filter output to a predetermined value;
set a first threshold based on the second filter output;
decrease the second time constant;
increase the second time constant;
calculate a difference between said first threshold and the second filter output;
adjust said first threshold based on the second filter output; and to determine an absence when the first filter output falls below said first threshold,
wherein said processing resources are adapted to also:
after decreasing the second time constant, perform one of the following steps:
waiting for a predetermined time; and
waiting until the second filter output becomes equal to the first filter output within a predetermined tolerance.