Temperature sensing unit and temperature sensing method for human presence detection

A temperature sensing method, used for human presence detection (HPD), the temperature sensing method comprising:

• sensing an in-machine temperature (Ta) and a cap temperature (Tb1) and a human object temperature (Tb2);
• calculating an ambient temperature Tamb based on,
• Tamb
• ⁢
• =
• T
• b
• ⁢
• 1
• -
• (
• T
• a
• -
• T
• b
• ⁢
• 1
• )
• ⁢
• R
• a
• ⁢
• c
• R
• i
• ,
• wherein a first ratio of a first thermal resistance (Rac), which is between the cap temperature (Tb1) and an external ambient temperature, and a second thermal resistance (Ri), which is between the in-machine temperature (Ta) and the cap temperature (Tb1) is obtained through a first calibration procedure;
• calculating a normal skin temperature (Tskin) from the ambient temperature (Tamb) based on a second order polynomial function or a third order polynomial function as, Tskin=(a1×Tamb3+)a2×Tamb2+a3×Tamb+a4;
• calculating a coverage ratio (CV) based on,
• C
• ⁢
• V
• =
• T
• b
• ⁢
• 2
• n
• -
• T
• amb
• n
• T
• skin
• n
• (
• Tamb
• )
• -
• T
• amb
• n
• ;
• and
• determining a HPD status to be 1 for human presence when the CV is greater than a preset HPD threshold δ, and determining a HPD status to be 0 for human non-presence when the CV is equal to or less than the preset HPD threshold δ.