Safety device for power window

A power-window safety device in combination with a drive motor which is connected to a window glass of an automotive vehicle to open and close the window glass, wherein said power-window safety device carries out a safety control operation to prevent an object from being caught by detecting an opening/closing position of the window glass, said safety device comprising:

• an angular position sensor for constantly measuring an angular position of said drive motor;
• a reduction mechanism which reduces the rotational speed of a rotary shaft of said drive motor;
• a position detecting circuit which detects an opening/closing position of said window glass on the basis of a signal output from said angular position sensor;
• and
• a safety control circuit which carries out a safety control operation, to prevent an object from being caught, in accordance with a signal output from said position detecting circuit;
• wherein said angular position sensor comprises a magnet supported on an output shaft of said reduction mechanism, and a magnetic flux sensor, disposed facing said magnet, for detecting a variation of the magnetic flux from said magnet, which variation of the magnetic flux is caused by a rotation of said rotary output shaft, whereby an opening/closing position of said window glass is detected on the basis of a detect signal derived from said magnetic flux sensor
• wherein said magnetic flux sensor outputs a voltage that is substantially linear in variation across 180° segments of rotation of said rotary output shaft, and periodically alternates.

A power-window safety device in combination with a drive motor which is connected toy a window glass of an automotive vehicle to open and close the window glass, wherein said power-window safety device carries out a safety control operation to prevent an object from being caught by detecting an opening/closing position of the window glass, said safety device comprising:

• an angular position sensor for constantly measuring an angular position of said drive motor, including a first sensor which outputs a first detection signal periodically changing in accordance with a rotation of an output shaft of the motor, and a second sensor which outputs a second detection signal which is shifted from said first detection signal by π/2 in phase;
• a reduction mechanism which reduces the rotational speed of a rotary shaft of said drive motor;
• position detecting means for detecting an opening/closing position of said window glass on the basis of said first and second detection signals;
• and
• safety control means for carrying out a safety control operation, to prevent an object from being caught, in accordance with an output signal of said position detecting means,
• wherein said angular position sensor comprises a magnet supported on an output shaft of said reduction mechanism;
• and
• wherein said first detection signal and second detection signal are substantially linear in variation across 180° segments of rotation of said rotary output shaft.