Abstract: An apparatus for detecting double-feed of sheets of paper with a light-transmission sensor. The light-transmission sensor is composed of a light emitting source, such as an LED, and a light receiving sensor located on both sides of a paper transport path. Before the first sheet is fed, the gain of a variable gain amplifier, which amplifies an output of the light receiving sensor, is present at a predetermined value so that an output level of the amplifier may be appropriate. When the first sheet passes the light transmission sensor, an output level of the variable gain amplifier is measured and the level for a sheet is stored. Each time a sheet is fed in the sequential paper feeding operation, the output level of the amplifier is measured and compared with the stored data to detect double-feed of sheets. If the level is not appropriate, the intensity of the light emitting source is controlled in order to correct the level.

Abstract: A paper feeder includes a rotatable feed roller and a retard roller biasingly urged toward one another, the feed roller being rotatable in a feed direction for feeding a paper sheet between the feed roller and the retard roller. A pivot are pivotably supports the retard roller, and a motor mounted on the pivot arm is operable to apply a turning torque to the retard roller in a direction opposite to the direction of feed of the feed roller.

Abstract: A linear motor driven elevator system comprises: a car connected to a counterweight by a rope; a linear motor comprised of a primary conductor and secondary conductor, one of which is a moving element and the other being a stator, the moving element being mounted in the car or the counterweight; and a device for stopping the car comprising, a power source connected to the primary conductor, the power source being continuously fed to the primary conductor to move the car and not being fed to the primary conductor to stop the car, and a braking device mounted on the car, the braking device being disengaged when power is fed to the primary conductor and engaged when power to the primary conductor is interrupted.

Abstract: An apparatus for maintaining an air gap between a stationary and a moving element of a toroidal linear motor which provides motive force to an elevator, comprises; a plurality of rollers mounted upon the moving element, and a means for biasing the rollers towards a central axis of the stationary element, and for cooperating with the rollers to maintain the air gap when power to the motor is shut off or vibration or other forces would tend to lessen the gap below a predetermined minimum. The rollers are arranged angularly about the stationary element and rotate due to the relative rotation of the moving and stationary elements.