US 12,219,672 B2
Safe heating circuit and electric blanket provided with safe heating circuit
Min Zhou, Ningbo (CN)
Assigned to North Star Home LLC, Libertyville, IL (US)
Filed by North Star Home LLC, Libertyville, IL (US)
Filed on Nov. 3, 2021, as Appl. No. 17/518,185.
Claims priority of application No. 202110950605.7 (CN), filed on Aug. 18, 2021.
Prior Publication US 2023/0056786 A1, Feb. 23, 2023
Int. Cl. H05B 3/34 (2006.01); H05B 1/02 (2006.01)
CPC H05B 3/34 (2013.01) [H05B 1/0202 (2013.01); H05B 2203/019 (2013.01); H05B 2203/02 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A safe heating circuit, comprising:
a PTC electric heating element, generating heat when being electrified;
a first switching element, coupled into a ground loop of the PTC electric heating element and configured to switch on or off a power loop of the PTC electric heating element based on an on-off control signal;
a first voltage acquisition circuit, configured to sample a first temperature voltage based on a ground current of the PTC electric heating element;
an NTC element, disposed between the PTC electric heating element and a sensing element;
the sensing element, configured to receive a leakage current from the PTC electric heating element transmitted by the NTC element;
a second voltage acquisition circuit, configured to sample a second temperature voltage based on the leakage current; and
a controller, configured to compare the first temperature voltage or the second temperature voltage to a set temperature voltage and output the on-off control signal based on a comparison result.