Apparatus for detecting the existence of an abnormality in a vehicle operator protection system

An operator protection system for use with a vehicle, comprising:

• a battery, mounted on said vehicle, for supplying electric power;
• a squib for actuating an air bag on said vehicle;
• means for detecting a collision of said vehicle comprising means for providing an electrical path from said battery to said squib to enable said electric power to be supplied to said squib to cause said squib to actuate said air bag when said collision detecting means detects said collision;
• a backup capacitor, being charged by said electric power to attain a charging voltage, for supplying backup electric power to said squib when said electric power being supplied to said squib by said battery is interrupted;
• a resistor, having first and second terminals and coupled to said electrical path and said backup capacitor, for forming a charging path to enable said battery to charge said backup capacitor;
• a diode, provided between said electrical path and said backup capacitor, to form a discharge path to provide said backup electric power from said backup capacitor to said electrical path;
• and
• means for determining a predetermined condition of said backup capacitor comprising:
• means for detecting magnitudes of first and second voltages at said first and second terminals of said resistor, respectively, when said backup capacitor is being charged;
• means for calculating, during a predetermined period of time, a difference between said magnitudes of said first voltages and said magnitudes of said second voltages;
• and
• means for adding said plurality of voltage differences to calculate a value;
• said determining means determining said predetermined condition of said backup capacitor in accordance with said value.

An operator protection system for use with a vehicle, comprising:

• a battery having a battery voltage stored therein for providing electric power and being mounted on said vehicle;
• actuating means, supplied with said electric power, for actuating an operator protection device at a predetermined time, said actuating means comprising:
• means for detecting a collision of said vehicle;
• and
• a squib for actuating an air bag when said collision is detected;
• an electrical path for directing said electric power to said actuating means;
• means for regulating said electric power being provided to said actuating means to provide a predetermined current to terminals of said squib to prevent said squib from actuating said air bag when said collision detecting means does not detect said collision;
• auxiliary power supply means, charged by said battery, for supplying backup electric power to said actuating means when said electric power being supplied by said battery to said actuating means is interrupted, said auxiliary power supply means comprising a capacitor;
• means for determining a predetermined condition of said auxiliary power supply means, comprising:
• means for detecting a magnitude of a charging voltage being stored in said auxiliary power supply means and a magnitude of said battery voltage of said battery during a period when said battery is charging said auxiliary power supply means such that variations in said battery voltage do not affect said charging voltage to determine a charging capability of said auxiliary power supply means;
• and
• checking means for detecting a voltage across said terminals of said squib when said predetermined current is provided to said terminals to determine a predetermined condition of said electrical path,
• said determining means determining said predetermined condition of said auxiliary power supply means in accordance with said charging capability;
• and
• means for notifying an operator of said vehicle of said predetermined condition when said determining means determines said predetermined condition of said auxiliary power supply means.