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 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.

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 composite structure for magnetic recording includes a core member of polymeric material to which is bonded at least one silicon disk having a magnetic recording material on its outer surface. The silicon disk surface provides optimal flatness and smoothness characteristics for a magnetic recording substrate, while the polymeric core member provides strength to the structure.

Abstract: Multi-layer magnetic thin film disks comprising a synthetic resin layer on an aluminum-containing substrate and an overlying metallic magnetic layer, are liable to have pin holes in the synthetic resin layer caused by galvanic corrosion of the aluminum in the substrate. The pin holes are passivated by aluminum oxide produced therein by anodically oxidizing the aluminum of the substrate in an electrolytic bath, the electric voltage of which is well below the normal passivation voltage for aluminum.

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.

Abstract: A magnetic recording device employing a thin foil member is fabricated by radially compressing a ring member, securing the periphery of the foil member to the compressed ring, releasing the compression on the ring so that it expands to produce tension in the foil member.A magnetic coating may be applied to the foil member either before or after securing it to the ring member.

Abstract: A circuit provides either the J-K logic function or the Exclusive Or (EOR) logic function depending upon a control signal. The circuit includes a conventional cross-coupled EOR block with two inputs, the logic function being performed by the block depending on the presence or absence of the control signal.

Abstract: Structure for providing a file protect function for a removable cartridge which houses a magnetic recording medium includes a rotary actuator in a sleeve member, the actuator having an outer disk and an inner disk. The actuator may be rotated in the sleeve to either of two positions 180.degree. apart by application of force to the outer disk. The inner disk has an interrupted segment therein, and the rotational position of this interrupted segment controls the enabling or disabling of the circuitry for recording on the magnetic medium.

Abstract: Structure for providing a file protect function for a cartridge which houses a magnetic recording medium includes a sleeve molded integrally with the cartridge. The sleeve has diametrically opposed slots and a rotary file protect actuator disposed in the sleeve has diametrically opposed projections which engage the sleeve slots to hold the actuator in position. The actuator may be rotated 180.degree. by a screwdriver or other tool, and this rotation controls the enabling or disabling of the circuitry for recording on the magnetic medium to provide a file protect function.

Abstract: A magnetic recording device employing one or more thin circular foil members which are secured to a supporting member on at least the outer edges of the foil members. In one embodiment, the foil members have central openings therein, with the central opening in one foil member being larger than the opening in the other foil member. A clamping and spacing member is secured to the foil member having the smaller opening and extends through the larger opening in the other foil member to both provide a means for transmitting rotational force to the structure and to provide for spacing between the structure and an adjacent structure in a recording assembly.In an alternate embodiment, one of the foil members has a central opening while the other does not, and rotational force is transmitted through the foil without the central opening. As additional alternatives, the foils may have central openings of equal sizes and be secured to support members either at their outer edges or at both their inner and outer edges.

Abstract: Direct method for measuring the magnetostriction constant .lambda..sub.s of soft magnetic and isotropic magnetic materials. A thin film sample is cantilevered and clamped at one edge. Under the influence of a magnetic AC field and the magnetostriction effect of the sample material, the free end of the cantilevered sample is deflected and oscillates with twice the frequency of the AC field. The resonance amplitude a.sub.res is measured by using a laser beam impinging upon the oscillating sample and measuring the reflected beam amplitude by means of a position-sensitive photodiode. The AC output signal of the photodiode is proportional to the sample amplitude. The magnetostriction constant .lambda..sub.s is directly proportional to the resonance amplitude a.sub.res multiplied by a constant factor which depends on known geometry and properties of the sample material.

Abstract: A method and means are provided to increase the effective data transfer rate between a direct access storage device (DASD) and a central processing unit (CPU) communicating with the DAS device through a channel and a DASD control device.A command issued to the AS subsystem which requires mechanical motion in the DAS device is stored in the subsystem and the subsystem provides a response to the channel indicating that the command has been carried out, without actually carrying out the command. The channel responds by issuing one or more additional commands in the chain to the subsystem which may be carried out without mechanical motion. When a command is issued to the subsystem which again requires mechanical motion of the device, the control device causes the stored command to be executed essentially simultaneously with the newly received command.

Abstract: A sampled data servo positioning system employs an actuator to move a member between a current and a target position. Incremental position feedback is provided only at sampling times. The system employs a model responsive to a velocity related input signal to produce a continually available model incremental position signal. Phase comparing means indicates phase differences between the model and sampled position signals at the sampling times.The system has two operational configurations in the first of which a source of saturation control signals is connected to the actuator to cause maximum acceleration or deceleration thereof. In this first configuration, the model is forced to track the actuator motion by means of feedforward plus feedback control. The feedforward signal represents actuator performance while the feedback signal is the position signal phase difference.

Abstract: A disk file employs a disk having sectors of track-following servo information interspersed around the disk between data portions. Included in each sector is a SYNC signal which is encoded to indicate the validity or invalidity of the servo information in that sector. The servo information in a sector is used only if the SYNC signal indicates that it is valid.

Abstract: A magnetic dispersion is prepared by adjusting the pH of a mixture containing magnetic particles to a value which results in a positive electrostatic charge on the particles, while a mixture containing colloidal silica particles at the same pH results in negative electrostatic charges on the silica particles. Combining these mixtures causes the silica particles to coat and irreversibly bond to the magnetic particles resulting in better dispersion and less aggregation of the magnetic particles.