| 摘要 |
<p>PURPOSE:To shorten a time required for detection of a fault and to facilitate the detection of the fault by providing a detection circuit for carrier components and detecting the faults for each coordinatepointing device during the application of a coordinate input device. CONSTITUTION:A carrier detection circuit 7 detects only the DC component out of the output signal of an envelope detection circuit 6 and sends the detected component to a control circuit 9. The circuit 9 checks whether the output level of the circuit 7 is kept under the prescribed value or not. Then the circuit 9 produces a signal to show the presence or absence of the fault of a coordinate pointing device 2 and outputs the signal to a processor 11 as data. That is, a driving coil 1 is connected in series to a capacitor 10 for constitution of a serial resonance circuit. When the coil 1 is disconnected, the level of the input signal applied to a tuning amplifier 5 drops and therefore the output level of the DC component of the circuit 6 also drops. Then the output level of the circuit 7 also drops. Thus the circuit 9 outputs an alarm signal to the processor 11 to show the fault of the device 2. As a result, the occurrence of a fault is easily detected for the device 2 under application.</p> |
