Capacitance-based sensor and occupant sensing system
A capacitive sensor and current sensing technology, applied in radio wave measurement system, pedestrian/occupant safety arrangement, instrument, etc., can solve the problem of ineffective sensing of occupant
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no. 1 example
[0052] figure 1 is a schematic diagram showing the overall structure of the occupant sensing system with the capacitive sensor 10 according to the first embodiment. FIG. 2 is a schematic diagram showing the front passenger seat 9 representing the installation position of the electrode unit 1 serving as a sensing device based on the capacitive sensor 10 .
[0053] Such as figure 1 As shown in , the capacitance-based sensor 10 of this embodiment includes occupant sensing electrodes 20 , empty seat capacitance reducing electrodes 21 , current sensing means (current sensing circuit) 31 , and driving means (driving circuit) 32 . The occupant sensing electrode 20 is embedded in at least one of the seat bottom 12 and the seat back 17 of the front passenger seat 9 serving as the vehicle seat of the present invention. In this specific example, as figure 1 As shown in , occupant sensing electrodes 20 are embedded in the seat bottom 12 . Empty seat capacitance reducing electrode 21 i...
no. 2 example
[0067]As shown in FIG. 5, the second embodiment is characterized in that the driving device 32 is electrically connected at the illustrated position (the first position of the present invention) between the occupant sensing electrode 20 and the empty seat capacitance reducing electrode 21, And the current sensing device 31 is electrically connected at the illustrated position (the second position of the present invention) between the empty seat capacitance reducing electrode 21 and the driving device 32 .
[0068] The operation based on each part of the capacitance sensor 10 when measuring capacitance will be described with reference to FIG. 5 . When the driving device 32 electrically connected between the occupant sensing electrode 20 and the empty seat capacitance reducing electrode 21 generates a high-frequency low-voltage driving output, the occupant sensing electrode 20 is driven to have a high potential. Thus, a capacitance Cb is generated between the occupant sensing el...
no. 3 example
[0071] The third embodiment is characterized by modifying the structure of the first or second embodiment as described below. That is, if Figure 6 As shown in , the current sensing device 31 has an operational amplifier 31a for maintaining the same potential and electrical isolation between the respective two electrodes between which the current sensing device 31 is interposed. In this way, in the structure (first embodiment) in which the current sensing device 31 is connected between the occupant sensing electrode 20 and the empty seat capacitance reducing electrode 21, these electrodes 20, 21 can be made to be controlled by the operational amplifier 31a at the electrode 20. , 21 effectively provide the same potential and electrical isolation between the state. In this state, use a voltmeter to measure the voltage drop V generated by the resistor R. According to the relationship V=i·R, the current i flowing through the human body (measurement object) can be sensed with hig...
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