| 摘要 |
PURPOSE:To enable a stable, effective detection of disconnection by a method wherein a temperature characteristics of a disconnection detection output is made into the minimum by means of a given correction circuit and diode connected in a given way to be compared with a reference voltage. CONSTITUTION:The linearity of a detection output of a detection element Rs formed with a resistor connected in series to lamps 5... is corrected through a correcting circuit 3a constituted with a Zener diode ZD and resistors R1-R3. And the detection output and a reference voltage which is generated in a reference voltage generating circuit 3b dividing the power source voltage connected jointly with the circuit 3a to the earthing via a diode D are compared in a comparison circuit 3c to control a lighting of a display lamp 4. On this account, when resistors R1-R3 and the diode D are selected to select a circuit constant and along with this, the diode D is selected, then, the temperature characteristics of a detection output of the element Rs becomes the minimum and also protection of a power source inverse connection is performed, thus, a disconnection detection being performed, stably and effectively. |
