Abstract: An improved reel servo for a recording and reproducing machine is disclosed. The reel servo as well as other servos in the machine are controlled by a single microprocessor which results in greater inherent communication between such servos and significantly improved operating capabilities. The reel servo itself is adapted to have the supply and take-up reels operate in different kinds of close loop servo control during various operating modes. The servo circuitry provides instantaneous information to the microprocessor for determining the diameter of tape that is wrapped on each of the reels. The reel servo has the capability of performing high speed shuttle and cueing operations without engaging the capstan and the tensioning arm can be positioned to provide the appropriate tape tension during shuttling in both the forward and reverse directions. An acceleration loop controls the supply reel so that the tape tension is maintained within predetermined upper and lower limits.

Abstract: A nonmagnetic holder is made having a plurality of precisely located parallel grooves. Each groove has a reference lateral surface provided therein. Individual magnetic transducers are inserted in each groove with a lateral surface abutting the reference lateral surface within that groove. The transducers are preferably made by well known batch fabrication techniques. A locating element, such as a leaf spring, is provided in each groove to urge the transducer core against the reference surface and to firmly hold the transducer in a desired position during alignment and assembly. The modular structure allows inspecting the individual transducers for mechanical or electrical damages and their replacement, if necessary, prior to the final assembly. The multichannel head is then integrally joined together, for example by bonding. The rejection rate of the resulting modular multichannel head is significantly reduced.

Abstract: The working surfaces of nickel-coated substrates for rigid magnetic discs are polished in a single-step process that employs a polishing composition comprising an aqueous suspension of unlubricated aluminum oxide powder having a hexagonal crystal shape and a nominal particle size of 1 to 10 microns, and colloidal aluminum oxide.

Abstract: In a disc information storage system which employs a servo data disc, a servo data head and a moveable carriage assembly for transporting a plurality of magnetic heads radially across the surface of the disc in response to a control signal produced in connection with a velocity command signal, an improved method and apparatus for production of a velocity command signal wherein one or a plurality of discrete velocity steps are added to the velocity command signal in a region which would otherwise indicate only a single value for velocity.

Abstract: A tape cassette has a springloaded indexing mechanism to urge the cassette reels in a tape winding directions so as to tension the free run of tape between the reels whenever the cassette is removed from the tape transport machine.

Abstract: A microprocessor controlled multiple servo system for use with a recording and reproducing apparatus is disclosed. The system controls all servo systems for a magnetic tape recording and reproducing apparatus, including a capstan servo, a reel servo, a scanning drum servo and an automatic scan tracking servo which controls the position of reproduced heads carried by the scanning drum which are of the type which can be transversely moved relative to the longitudinal direction of recorded tracks to accurately follow the tracks during special effect reproducing modes, such as slow motion, stop motion and fast motion reproducing. The microprocessor controlled servo system has unique and powerful functional capabilities which enable it to provide reliable precise asynchronous reproducing so that precisely accurate time compression and expansion can be carried out without performing any editing of the recorded material.

Abstract: A voltage controlled equalizer has two parallel signal paths. A first signal path is provided by a delay line coupled to an input of an amplifier. A control circuit is coupled between an input of the delay line and an output of the amplifier, via a second, parallel signal path. A control signal is applied to the control circuit to adjust the gain of the second signal path, thereby adjusting an amplitude versus frequency response characteristic of the equalizer. Signal delays caused by the control circuit are preferably selected substantially equal to those of the amplifier to compensate for undesired phase shifts of high frequency signals in the second signal path.

Abstract: A multiple speed servo is provided which measures and controls the speed of a head scanner below approximately 900 rpm, to maintain a preselected, relatively reduced, scanner speed which is fast enough to aid threading and unthreading tape about the scanner in the reverse direction, but not fast enough to damage the heads or tape. The safe handling is enhanced by selectively reducing the tape speed during reverse threading and unthreading of the tape, to maintain a preferred ratio of scanner circumferential velocity equal to, or slightly greater than, the tape speed. To this end, a slow speed scanner servo is employed to continually monitor and maintain the scanner at the preselected reduced scanner speed while the tape is maintained at the associated reduced tape speed.

Abstract: A narrow track magnetoresistive transducer has a square shaped bias permanent magnet superposed with an MR element. The square shaped magnet provides bias field components of substantially the same magnitude in both hard and easy axis directions of the MR element. A stable and uniform bias field is thereby obtained.

Abstract: Apparatus and method for phase scatter detection and reduction in a digital signal transmitted over a channel, for example a magnetic recording and reproducing channel. The transmitted signal is equalized to compensate for a non-constant amplitude response and/or non-linear phase response of the channel. A bit synchronization circuit, employing a controllable frequency reference clock signal generator and a digital phase detector, provides a reference clock synchronized with the transmitted data. The amount of phase scatter in the equalized signal is determined by monitoring the switching frequency of the phase detector. The equalizer may be adjusted to minimize that frequency, thereby reducing phase scatter.

Abstract: A transducer and method are described where track width reducing notches are filled with a nonmagnetic material which is heated to or slightly over its softening temperature but below its melting temperature. Concentrated high pressure at discrete locations is applied to the softened nonmagnetic material to enhance flow thereof into the notches.

Abstract: A tachometer assembly comprises two toothed rings (68, 70) in approximate axial register. The rings have similar peripheries of which the teeth (69, 71) are closely spaced in the axial direction of the rings. Magnetic flux in a path extending axially of the teeth varies as the rings rotate and is sensed by a coil (74) disposed coaxially of the rings.

Abstract: A switched RF signal, formed of modulated RF and blanking level signals, is selectively phase inverted on alternate pairs of television lines to provide, after FM detection, a video signal containing alternating positive and negative offset errors. The video signal is integrated to average and thus, in effect, minimize the alternating errors.

Abstract: An improved clock recovery system for use in digital rotary scan magnetic playback devices utilizing a phase locked loop. The clock signal recovered from the playback data has a phase error with a periodic component caused by time base variations in the playback data and a random noise component due to playback channel noise. The phase locked loop of the invention tracks the periodic component, while it suppresses the random noise component. The improved system is suitable for tracking wide bandwidth dynamic time base variations in the playback data without introducing phase errors caused by random noise into the recovered clock signal.

Abstract: A plurality of magnetic blocks is integrally joined side-by-side with a nonmagnetic material therebetween to provide a monolithic block defining parallel transducing gap planes, each pertaining to one multichannel transducer stack. A plurality of first parallel slots in the monolithic block intersects the gap planes to define a plurality of partitions, each partition forming pairs of magnetic pole pieces defining respective transducing gaps pertaining to respective stacks. The transducing gaps of each partition define interlaced transducing channels of the multichannel assembly. Second parallel slots provided along the gap planes have apexes defining transducing gap depths. The resulting transducing channels have uniform gap azimuth and gap depth while uniform internal stack alignment between all the respective stacks is obtained.

Abstract: An arrangement for a linear motor which uses a shorted turn as a shield for the magnet of the motor to thus provide a substantial reduction in the introduction of particulate matter into the Head Disk Assembly environment associated with the linear motor, without substantially increasing the reluctance of the magnetic circuit of the motor.

Abstract: For each magnitude of charge stored on a section of a target of a photoelectric tube due to the action of incident light thereon, there is a specific value of cathode voltage which ensures the discharge of the section in one pass of the scanning beam. It follows that if the cathode receives a voltage whose instantaneous value is proportional to the magnitude of the charge stored on the corresponding portion of the target, the complete discharge of the target is effected in one pass of the scanning electron beam. Since the output voltage of a camera preamplifier at any instant is directly related to the magnitude of the charge stored on the corresponding portion of the target of the same tube or a different tube viewing the same scene, the preamplifier output voltage herein is selectively applied to the tube cathode, preferably with an appropriate transfer function, whereby lag in the tube is eliminated.

Abstract: An error detection and correction system locates and corrects double errors in a received data block word digitally encoded in a Reed-Solomon code (n,K) as coefficient terms of an n-order codeword polynomial in the form ##EQU1## where the coefficients are powers of the primitive a of a Galois field, which codeword is divisible by a code generator polynomial in the form of a product of a plurality of different factors in the form (x+a.sup.i). Four syndrome signals are derived, each corresponding to a respective first order syndrome equal to the remainder upon dividing a received data block word by a respective factor. An error locator responsive to the four syndrome signals derives a reference signal corresponding to the position h of a reference term in the received data block word equally spaced relative to the two terms containing errors, and a relative position signal k corresponding to the number of terms by which the terms containing the errors are spaced from the reference term.