Bell + Howell Company

Other

Robert F Johnston

John R Flint

Kenneth L Hendrickson

Thomas R Wells

Richard Frystak

John A Thiel

John A Gallagher

A method and system for automatically calibrating a D.C. transducer are described in the environment of an illustrative film retrieval system. In this system, the output of a transducer such as a light sensor is amplified and the amplified output is compared to upper and lower limits within which it is desired to hold the transducer's amplified output. When either of the limits is exceeded, the amplification of the transducer's output is varied so as to shift its average value to a value which is between the upper and lower limits.

Automatic calibration for D.C. transducers

A web drive system for automatically reversing the direction of travel of the web when the end of the web is reached. A reversible electric motor provides power to either the supply or take up spindles. An end of the web is affixed to each of the spindles so that either spindle can be provided with power to draw the web from the other spindle. A planetary gear system provides power to whichever spindle acts as the take up spindle until the end of the web is sensed. The motor is then reversed and the planetary gear then provides power to the other spindle, which was previously the supply spindle.

Reversible ribbon drive

A microfiche reader stores a library file of microfiche in a cartridge which may be inserted into the reader, so that it is not necessary to manually manipulate the individual microfiche. The reader automatically extracts and feeds a selected microfiche from a cartridge and then returns it to the vacated cartridge location. A right angle rack and pinion causes the extractor mechanism to provide an automatic feed mechanism which moves over a horizontal advance, raise, drop and back path so that hooks may be removed from and then returned into notches in a microfiche carrier, without damaging them. An automatic elevator mechanism positions the cartridge so that any selected microfiche may be placed on display.

Microfiche reader

This invention relates to photographic apparatus having means for automatically moving a lens along an axis for properly focusing on an object. The apparatus includes a light emitter for transmitting a train of light signals toward the object at a constant angle relative to the axis, and a pair of movable photoreceptors disposed in spaced relationship with the emitter in the apparatus. The photoreceptors are adapted to receive the light signals upon reflection thereof from the object, and are further adapted to produce electrical signals corresponding to the amount of light received. An operational amplifier is adapted to receive the electrical signals produced by the photoreceptors, and produce a difference signal corresponding to the difference in strength of the electrical signals. The apparatus further includes an electric motor, responsive to the difference signal, adapted to cause the movement of the lens along the axis, and further adapted to cause the movement of the photoreceptors until the amount of light received at each of the photoreceptors is equalized to produce an absolute minimal difference signal indicative of the object being properly focused by the lens. A gain change device is provided to increase the amplitude of the difference signal when relatively far objects are focused on.

Automatic focusing system

A photographic apparatus having a lens movable along an axis for automatically focusing an object to be photographed is disclosed. The apparatus includes a rotatable sleeve controlled by electrical signals produced by photoreceptor means adapted to receive light emitted by the apparatus and reflected from the object. The sleeve effectuates the movement of the lens along an axis to bring the object into focus. The apparatus further includes assembly means, carrying the photoreceptor means, pivotably secured to the sleeve for adjusting the light received by the photoreceptor means by an amount corresponding to the rotation of the sleeve, thereby changing the electrical signals to maintain the object in focus.

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Wildwood, IL, United States of America

Robert F Johnston