Position encoder for sliding door power drive system

In a vehicle sliding door apparatus accommodating either manual or powered operations of a vehicle mounted sliding door which is movable along a fixed path between door opened and door closed positions in which an elongate door drive member is coupled to the door for longitudinal forward and rearward movement with the door, first rotary means are positively mechanically engaged with the door drive member for rotation coordinated with longitudinal forward and rearward movement of the door drive member, a bidirectional drive motor has a rotary output shaft, a clutch means positively mechanically couples the output shaft to the first rotary means in response to rotation of the output shaft in either direction and for accommodating free rotation of the first rotary means relative to the output shaft when the shaft is stationary, and a control means for selectively operating the drive motor, the improvement comprising:

• position encoder means for generating position signals indicative of the travel distance of the door as the door moves in forward and rearward directions along the fixed path between a door opened and a door closed position, the position encoder means comprising:
• a rotatable encoder wheel positively mechanically connected to said first rotary means, said encoder wheel having a plurality of circumferentially spaced apertures between solid teeth, said encoder wheel adapted for rotation with said first rotary means;
• first and second photoelectric means mounted in spaced relationship with the apertures in the wheel;
• each of the first and second photoelectric means including a light emitter and a light receiver, the light emitter and light receiver being disposed on opposite sides of the teeth on the encoder wheel to detect the passage of the teeth therebetween;
• each of the first and second photoelectric means generating an output to the control means indicative of the passage of each tooth past the first and second photoelectric means, respectively, the control means counting the outputs of the first and second photoelectric means to determine the actual position of the door;
• the first and second photoelectric means being spaced apart a distance such that each of the first and second photoelectric means is positioned to independently detect the passage of a different tooth in the encoder wheel therepast;
• and
• the control means determining the direction of movement of the encoder wheel and the door from the outputs from the first and second photoelectric means.

A vehicle sliding door position encoder comprising:

• a vehicle mounted sliding door movable along a fixed path between door opened and door closed positions;
• an elongate door drive member coupled to the door for longitudinal forward and rearward movement with the door;
• first rotary means positively mechanically engaged with the door drive member for rotation coordinated with longitudinal forward and rearward movement of the door drive member;
• a bidirectional drive motor having a rotary output shaft;
• a clutch means positively mechanically coupling said motor output shaft to said first rotary means in response to rotation of said output shaft in either direction and for accommodating free rotation of said first rotary means relative to said output shaft when said output shaft is stationary;
• control means for selectively operating said drive motor;
• a rotatable encoder wheel positively mechanically connected to said first rotary means, said encoder wheel having a plurality of circumferentially spaced apertures between solid teeth, said encoder wheel adapted for rotation with said first rotary means;
• first and second photoelectric means mounted in spaced relationship with the apertures in the wheel;
• each of the first and second photoelectric means including a light emitter and a light receiver, the light emitter and light receiver being disposed on opposite sides of the teeth on the encoder wheel to detect the passage of the teeth therebetween;
• each of the first and second photoelectric means generating an output to the control means indicative of the passage of each tooth past the first and second photoelectric means, respectively, the control means counting the outputs of the first and second photoelectric means to determine the actual position of the door;
• the first and second photoelectric means being spaced apart a distance such that each of the first and second photoelectric means is positioned to independently detect the passage of a different tooth in the encoder wheel therepast;
• and
• the control means determining the direction of movement of the encoder wheel and the door from the outputs from the first and second photoelectric means.