Detection device
View Patent ↗A detection device includes a resonance unit having a coil and a capacitor, an oscillation unit for oscillating the resonance unit, and a signal processing unit for detecting the oscillation state of the resonance unit and outputting an object detection signal when oscillation is stopped. The signal processing unit intermittently executes a self-diagnosis mode by forcibly oscillating the oscillation unit to determine whether or not an abnormality occurs in the resonance unit.
1. A detection device, comprising:
a resonance unit including a coil and a capacitor;
an oscillation unit for oscillating the resonance unit; and
a signal processing unit for detecting an oscillation state of the resonance unit and outputting an object detection signal when the oscillation is stopped,
wherein the signal processing unit intermittently executes a self-diagnosis mode for determining whether or not an abnormality occurs in the resonance unit by forcibly oscillating the oscillation unit.
2. The detection device of claim 1 , wherein the signal processing unit forcibly oscillates the oscillation unit by increasing an absolute value of negative conductance of the oscillation unit.
3. The detection device of claim 2 , wherein the signal processing unit forcibly oscillates the oscillation unit by increasing the absolute value of the negative conductance of the oscillation unit to be larger than a maximum value of conductance of the resonance unit.
4. The detection device of claim 1 , wherein the signal processing unit forcibly oscillates the oscillation unit by applying a pulse voltage or a pulse current to the resonance unit.
5. The detection device of claim 1 , wherein the signal processing unit outputs an abnormality detection signal different from the object detection signal when the abnormality is determined in the self-diagnosis mode.
6. The detection device of claim 5 , wherein the signal processing unit continues outputting the abnormality detection signal until it is determined that there is no abnormality.
7. The detection device of claim 1 , wherein in a case where it is determined that there is no abnormality during execution of the self-diagnosis mode, if the object detection signal is outputted just before execution of the self-diagnosis, the signal processing unit continues outputting the object detection signal.
8. The detection device of claim 1 , wherein the signal processing unit outputs a signal different from the object detection signal during execution of the self-diagnosis mode.
9. The detection device of claim 1 , wherein the signal processing unit periodically executes the self-diagnosis mode.
10. The detection device of claim 1 , wherein the signal processing unit executes the self-diagnosis mode when it is detected that the oscillation of the resonance unit is stopped while the self-diagnosis mode is not executed.
11. The detection device of claim 10 , wherein the signal processing unit executes the self-diagnosis mode only once immediately after the oscillation stop is detected.
12. The detection device of claim 1 , wherein the signal processing unit executes the self-diagnosis mode only once immediately after starting to operate.
13. The detection device of claim 1 , wherein the signal processing unit forcibly stops the oscillation of the resonance unit when the self-diagnosis mode is completed.
14. The detection device of claim 13 , wherein when the self-diagnosis mode is completed, the signal processing unit forcibly stops the oscillation of the resonance unit only in a case where the object detection signal is outputted just before execution of the self-diagnosis mode.