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 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: 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: 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: 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: 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.

Abstract: A barrier anodizing process for an aluminum alloy substrate employs an anodizing current having a density between 20 and 300 milliamps/cm.sup.

Abstract: A magnetic disk coating composition contains magnetic particles and a binder system comprising epoxy and phenolic resins, a titanate coupling agent and a water miscible solvent system, the coating having a pigment volume concentration of up to 35.

Abstract: For the servo track control of magnetic heads over magnetic tracks, in addition to the main servo position signals arranged in offset fashion to the middle of the track, auxiliary servo position signals are provided symmetrically on each side of the middle of the track. These auxiliary servo position signals are offset along the track length relative to each other and are smaller than half the track width. In the determination of the position error signal, they serve to indicate the tilting of the magnetic head relative to the recording track in that they are unequal. If the magnetic head deviates greatly from the middle of the track, these auxiliary servo position signals can be added to the main servo position signals to obtain a stronger position error signal.

Abstract: A servo system provides track following servo information from a buried servo layer disposed under the data recording layer, using the same transducer for simultaneously reading the servo information and writing data. To prevent the voltage generated in the transducer while writing data from masking out the servo information, a dummy voltage having the same magnitude as the transducer voltage is connected so that it cancels the write data voltage in the head.

Abstract: A bi-directional serial printer has a look-ahead feature which determines the distance between the margin of the line being printed and the margin, in the direction of the print head travel, of the next line to be printed. If this distance is less than a predetermined number, print head motion continues after printing the last character on the present line until the print head reaches the margin position for the next line.

Abstract: A magnetic recording device for non-contact recording on a flexible disk employs a Bernoulli plate to stabilize the rotating disk. The plate is slightly concave and has a number of small orifices therein through which air is drawn by the disk rotation to produce a thin, cushion of air between the plate and the disk.

Abstract: In a printing system employing a spliced endless print ribbon, an opening is provided in the ribbon adjacent the splice to enable sensing of the approach of the splice to the print station. Printing is suspended as the splice passes the print station to avoid undesirable printing quality and damage to the splice. The same sensing means detects lack of ribbon movement, indicative of a ribbon jam, to suspend printing and ribbon drive.