Current limiting device

摘要

A demagnetizing circuit and a current limiting device thereof for being built into a power supply circuit of a color television receiver or color monitor display or the like with which it is possible to effect a reliable demagnetizing operation using existing components and without using either a positive characteristic thermistor which reaches a high temperature or a relay circuit. The demagnetizing circuit is connected in parallel with a power supply circuit having a smoothing capacitor (4) and a negative characteristic thermistor (7) or fixed resistance for suppressing surge currents to the smoothing capacitor (4). The demagnetizing comprises a thermally actuated switch (16) connected in series with one end of a demagnetizing coil (8) by way of a positive characteristic thermistor (15) which is actuated by heat produced by the negative characteritic thermistor (7) or fixed resistance to cut off a demagnetizing current. The current limiting device within the demagnetizing circuit comprises the negative characteristic thermistor (7) or fixed resistance, the positive characteristic thermistor (15) and the thermally actuated switch (16) interposed between the negative characteristic thermistor (7) or fixed resistance and the positive characteristic thermistor (15). The thermally actuated switch (16) comprises a thermally actuated member (26) caused to bend by heat produced by the negative characteristic thermistor (7) or fixed resistor, and a moving contact point (27) and a fixed contact point (28) which are opened by this bending of the thermally actuated member (26). <IMAGE>