| 摘要 |
PURPOSE:To contrive safety against a short circuit trouble, by a method wherein Hi level output decision voltage of a voltage comparison circuit is lowered than 0V, and a circuit which applies lower voltage than the 0V through ''ON'' of a pressure switch is connected with an inversion input terminal of a voltage comparison circuit. CONSTITUTION:When a capacitor 21 or resistor 24 or a voltage comparison circuit 3 has a short circuit trouble in an ''OFF'' state of a pressure switch 10, neighter the voltage comparison circuit 3 is inverted nor a signal showing presence of a flame becomes applicable because the voltage of an inversion input terminal 5 does not drop to (-)fV, but to 0V only. Then, a Hi level signal showing presence of no flame becomes applicable by the voltage comparison circuit 3 based on an output of the pressure switch even if the short circuit trouble is generated during ignition action and combustion and either a device is not ignited or its flame is extinguished. With this, a control circuit is safe as it suspends its ignition or combustion action. |
