Roll-up shade drive with spring motor and reduced drive force

A roll-up window shade for motor vehicles comprising:

• a rotatably supported wind-up shaft having first and second ends;
• a shade element having a first edge fixed to the wind-up shaft;
• a pull rod connected to a second edge of the shade element remote from the wind-up shaft;
• two guide rails each extending on a respective side of the shade element for guiding movement of the pull rod and shade element between a retracted position exposing a window and an extended position covering the window;
• two push elements each of which is allocated to a respective one of the guide rails, each push elements being guided through its respective guide rails, each push element carrying teeth and pushing on the pull rod;
• two drive gears each of which is allocated to a respective one of the push elements, each drive gear being fixedly mounted on an end of a connecting shaft;
• at least one spring motor coupled with the connection shaft for rotating said drive gears in a direction that moves the pull rod and shade element to said extended position;
• and
• an electric drive motor coupled to said wind-up shaft operable for rotating said wind-up shaft in a direction that moves said pull rod and shade element toward said retracted position.