Electrostatic occupant detection apparatus and method for detecting failure of the same
First Claim
1. An electrostatic occupant detection apparatus comprising:
- an electrostatic sensor including a main electrode, which is located in a vehicle seat, and a guard electrode, which is located between a vehicle body and the main electrode and spaced from the vehicle body and the main electrode, the vehicle body being conductive with a vehicle grounded portion;
a sensor-characteristics detection unit configured to;
selectively apply an alternating voltage signal to each of the main electrode and the guard electrode of the electrostatic sensor;
selectively cause each of the main electrode and the guard electrode to be opened or grounded;
cause, in these conditions, a selection unit to select a potential difference between ends of one of resistors connected to the main electrode and the guard electrode respectively;
cause a current conversion unit to convert the selected potential difference into an electric current;
cause a voltage conversion unit to convert the electric current into a voltage value; and
cause an overcurrent detection unit separately to detect an overcurrent in each of the main electrode and the guard electrode when the alternating voltage signal is applied; and
an arithmetic control unit configured to, according to one or a combination of the voltage value detected by the sensor-characteristics detection unit and detection or non-detection of the overcurrent by the sensor-characteristics detection unit;
determine whether an open failure occurs in each of the main electrode and the guard electrode;
determine whether a power supply short failure occurs due to a short-circuit between a connection path from a power supply to a signal source, which is for applying the alternating voltage signal to each of the main electrode and the guard electrode, and another electric conduction element;
determine whether a grounded failure occurs in each of the main electrode and the guard electrode; and
determine whether a short failure occurs between the main electrode and the guard electrode.
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Accused Products
Abstract
A main electrode is located in a vehicle seat. A guard electrode is located between a grounded vehicle body and the main electrode. A detection unit selectively applies an alternating voltage signal to the main electrode and the guard electrode, sets the main electrode and the guard electrode to be in an open state or a grounded state, detects an electric current of one of the main electrode and the guard electrode, converts the selected electric current into a voltage value, and detects an overcurrent in the main electrode and the guard electrode. A control unit determines the main electrode and the guard electrode to be an open failure, a power supply short failure, a grounded failure, or a short failure with the guard electrode, according to one or a combination of the voltage value and detection or non-detection of an overcurrent.
16 Citations
11 Claims
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1. An electrostatic occupant detection apparatus comprising:
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an electrostatic sensor including a main electrode, which is located in a vehicle seat, and a guard electrode, which is located between a vehicle body and the main electrode and spaced from the vehicle body and the main electrode, the vehicle body being conductive with a vehicle grounded portion; a sensor-characteristics detection unit configured to; selectively apply an alternating voltage signal to each of the main electrode and the guard electrode of the electrostatic sensor; selectively cause each of the main electrode and the guard electrode to be opened or grounded; cause, in these conditions, a selection unit to select a potential difference between ends of one of resistors connected to the main electrode and the guard electrode respectively; cause a current conversion unit to convert the selected potential difference into an electric current; cause a voltage conversion unit to convert the electric current into a voltage value; and cause an overcurrent detection unit separately to detect an overcurrent in each of the main electrode and the guard electrode when the alternating voltage signal is applied; and an arithmetic control unit configured to, according to one or a combination of the voltage value detected by the sensor-characteristics detection unit and detection or non-detection of the overcurrent by the sensor-characteristics detection unit; determine whether an open failure occurs in each of the main electrode and the guard electrode; determine whether a power supply short failure occurs due to a short-circuit between a connection path from a power supply to a signal source, which is for applying the alternating voltage signal to each of the main electrode and the guard electrode, and another electric conduction element; determine whether a grounded failure occurs in each of the main electrode and the guard electrode; and determine whether a short failure occurs between the main electrode and the guard electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification