text: The present invention relates generally to an apparatus for handling and storing optical disks and, more particularly, to an apparatus for providing controlled lateral displacement of an optical disk within an optical disk handling system.
  An optical disk is a data storage medium which is readable by a laser-based reading device. Optical disks known as "compact disks" or "CDs" have become increasing popular during the past few years for recording music and audio-video works Due to the huge storage capacity of optical disks as compared to conventional magnetic storage media, optical disks known as "ROM disks" have become popular for storing computer readable information. However, until very recently, optical disks were of somewhat limited use in the computer industry due to the fact that optical disks could not be "erased" and "written" with new information, i.e. ROM disks are "read only" memory devices. However, recent technology has produced optical disks which are both computer readable and computer writable. Thus, in the future, optical disks are expected to become increasingly more important in the computer industry and may eventually replace magnetically readable and writable storage media such as "floppy disks" and "hard disks." Another recent development, the ability to provide data storage on both surfaces of an optical disk, has effectively doubled the optical disk storage capacity.
  Optical disks of the type used in computer applications are generally mounted in parallelepiped-shaped cartridges. Optical disk reading devices generally receive a disk which is to be read through a narrow slot provided on the front surface of the device. Currently, most optical disks are hand-inserted into disk readers. However, for large databases consisting of many optical disks, it is preferable, and perhaps essential, to provide an optical disk storage system for storing the disks at known locations, and an optical disk handling system which is capable of retrieving a desired disk from a storage location and inserting the disk into an optical disk reader. In a disk storage system wherein the stored disks and an associated disk reader are arranged in a longitudinally extending, two-dimensional array consisting of vertically extending columns and laterally extending rows, it is necessary for a disk handling system to be capable of engaging and moving each disk vertically, laterally, and longitudinally in order to remove it from storage, move it into aligned relationship with the disk reader, and insert it into the disk reader. It may also be necessary for the disk handling system to flip the disk to reverse the side thereof which will be positioned in readable relationship with a reader.
  In order to decrease production and maintenance costs and to increase reliability of such a disk handling system, it is generally desirable to reduce the number of separate drive units to a minimum. It is also desirable to minimize or eliminate the type of mechanical systems such as, for example, clutch assemblies, which are particularly subject to malfunction under frequent use conditions It is also desirable to minimize the use of sensing devices which are particularly subject to malfunction such as, for example, photoelectric or magnetic proximity sensors. It is also desirable to minimize the mounting of sensors or motors on moving system components to eliminate problems associated with moving lead wires, etc.