Abstract: A control system for a bidirectional printer having a print head carriage movable at different speeds on different printing lines employs a microcomputer which generates a desired velocity profile for the carriage motion. This desired velocity profile is continuously compared with the actual velocity and the error voltage generated is used to control pulse width modulator circuitry which supplies driving power to carriage drive motor.

Abstract: A track following servo system for a magnetic disk file employs a buried servo pattern having two types of signals therein. The first is a reference signal of frequency f and the second type are control signals of frequency 2f, adjacent control signals being 180.degree. out of phase with each other.

Abstract: A servo system generates a velocity profile for moving a load from one position to another by dividing the time during which the load is moving into a plurality of segments, each segment being one half as long as the preceding segment. For each segment a fixed number of desired velocity values are stored and used to control the velocity of the moving load. This results in increasing resolution of the velocity wave as the load approaches its desired position, while not requiring excessive storage capacity for storing the desired velocity values.

Abstract: In spin coating a liquid magnetic dispersion onto a rotating annular substrate, a stationary fluid barrier member is positioned closely adjacent the substrate after deposition of the dispersion thereon and during the time the excess dispersion is spun off, the substrate has a radial opening therein which permits fluid communication between the outer portion of the fluid barrier and its inner portion. The barrier member serves to reduce the rate of solvent evaporation from the dispersion so that the dispersion flows more readily during spin-off to produce a thinner resulting magnetic coating.

Abstract: A method for monitoring characteristics of a magnetic recording head which is flying in an air bearing relationship over a rotating magnetic recording disk containing Fe.sub.2 O.sub.3 detects triboelectric charges generated by intermittent contact between the head and the disk and also detects modulations in the spacing between the head and the disk surface when the two are not in contact.

Abstract: In a control system for a bidirectional printer capable of printing at different speeds on different lines, stored values representing the ideal velocities during the acceleration and deceleration of the print carriage for each direction and speed are compared with the actual values and any resulting difference is used to move the carriage velocity toward the ideal value.

Abstract: A control system for a bidirectional printer having a print head carriage movable at different speeds on different printing lines provides for equal stopping distance in the margin at both high and low speed operation. This is accomplished by delaying the initiation of stopping carriage motion when printing at low speed so that the carriage travels farther into the margin and this distance is controlled so as to be equal to the travel distance at the end of a line printed at high speed.

Abstract: A new magnetic medium permits magnetic recording either in the longitudinal or the vertical direction. The medium, unlike prior art structures, does not require a nonmagnetic substrate. The medium is a rigid magnetic disk homogeneously prepared from ferric oxide particles and polyethersulfone in ratios and proportions that produce effective and inexpensive magnetic recording media.

Abstract: In a control system for a bidirectional printer capable of printing at different speeds on different lines and in which the actual velocity of the print carriage is compared with a desired velocity profile to generate an error count, the error count is measured and averaged out for each direction and speed of carriage movement to compensate for the effect of changes in the printer system dynamics such as aging, wear, debris buildup, etc.

Abstract: A sector servo system for a magnetic disk file employs servo signals in the sectors which are recorded at a slant relative to the data tracks. Using digital techniques, the slanted servo tracks produce information relative to the amount and direction of the displacement of the disk file magnetic head from the centerline of a data track for use in a track following servo system.

Abstract: A magnetic recording composition contains load-bearing particles which consist of a monodispersion of spherical particles distributed throughout the coating. The spherical particles have a diameter somewhat in excess of the finished coating thickness so as to extend above the coating.

Abstract: A monolayer magnetic coating is prepared by applying magnetic particles which have an electrostatic charge in an aqueous environment to an active layer on a substrate, the active layer having an electrostatic charge in an aqueous environment opposite to the charge on the magnetic particles so that the particles bond to the active layer. The concentration of the electrolyte in which the charged particles are dispersed is adjusted to reduce the coulombic repulsive forces between the particles, permitting them to move close together and thereby increasing the magnetic particle packing in the resultant magnetic coating.

Abstract: To compensate for drops in the amplitude of signals read from magnetic records, in particular servo signals, a complementary correction signal is produced from the signal drops by rectifying, low-pass filtering, differentiating, integrating and forming the absolute value. This complementary correction signal is added to the defective signal to obtain a signal which has roughly been corrected to the original magnitude prior to evaluating and forming the position error signal (PES).

Abstract: A method for producing a magnetic recording composition involves preparing an aqeuous dispersion of magnetic particles and colloidal silica particles, the pH of this dispersion being adjusted so that the magnetic and silica particles are electrostatically attracted to and bond to each other, removing the water from the dispersion, and dispersing the silica-coated magnetic particles in an organic liquid binder system for application to a recording substrate.

Abstract: For a metallic thin film magnetic disk, a chromium undercoat and a magnetic layer, in particular of an FeCoCr alloy, are obliquely sputtered by means of a sputtering system onto a substrate at an angle of incidence of about 60.degree.. The operating pressure of the argon gas atmosphere is between 5 and 15 .mu.bar and the thickness (t.sub.Cr) of the undercoat, which also influences the coercive field strength, is between about 50 and 180 nm. By means of a sector shutter of suitable shape, the thickness distribution between the inner diameter ID and the outer diameter OD of the storage area of the magnetic disk can be influenced in the desired manner.

Abstract: A substrate for a magnetic recording disk employs an annular core of synthetic material having thin metal foils bonded to opposite faces, the metal foils serving to receive a magnetic recording material to form a magnetic recording structure. The inner surfaces of foils which are bonded to the core faces have applied thereto a thin, soft, deformable layer such as copper to prevent irregularities in the core faces from affecting the outer surfaces of the metal foils.

Abstract: The substrate 1 for magnetic disks takes the form of a laminate made up of a plurality of individual thin, fiber-reinforced, anisotropic and unidirectional lamellae. These lamellae are arranged staggered on top of each other at few angular spacings, i.e., at great angles of up to 60.degree., and are finally pressed together. The outer layers and lamellae, respectively, may be reinforced by stronger fibers or other material, such as carbon fibers outside and glass fibers inside, to influence the flexural modulus and the shearing modulus independently of each other. This makes for a substrate which consists of anisotropic material, whose characteristics are essentially isotropic, which is lighter than previously used substrates, and which has a higher critical number of revolutions.

Abstract: A drive is provided which accepts a cartridge containing a flexible magnetic recording disk and provides for simultaneous transducer access to both recording surfaces of the disk. The cartridge is inserted into a tray in the drive and then rotated in the tray to position both recording surfaces adjacent transducers and to position the disk center on a disk drive member for rotating the disk.

Abstract: Servo records provided at intervals on a record medium are used in a sampled servo system to define data tracks on the medium. Asperities in the medium, or problems arising from the servo writing process can in some instances lead to mis-alignment of a servo path 33 defined by a servo sample with the corresponding desired data track. This causes non-zero position error signals to be produced even when the track following head is accurately positioned over the data track. The problem is solved by measuring the position error signals derived from each servo sample with the head constrained in the correct on-track position. The value of each of these position error signals is then stored as a digital number forming part of a correcting byte in the data section immediately preceding the associated faulty sample. The correction byte also includes a flag bit which is set to demark the next servo sample if the error is so large as to be deemed uncorrectable.

Abstract: A polyurethane coating material for magnetic recording disks which is composed of magnetic particles, solvent blends and a thermosetting binder system. The resins are made from blocked isocyanates or blocked polyisocyanates with polyacrylates which contain reactive hydrogens.