Abstract: A vent cap has a long, narrow air communication passage covering the vent outlet of a sealed disk drive. The passage reduces diffusion of water vapor into the disk drive.

Abstract: A decoder for the 2,7 variable length code. A four-bit shift register sliding block decoder detects the presence of the code's four-bit ending sequence and provides decoded binary output. The decoder has only a three-bit binary error propagation.

Abstract: An improved method of height measurement and correction for a two-stage deflection ("fly's eye" lens) electron beam accessed lithography system is provided which employs a height measuring transducer such as a capacitance gauge or an optical gauge and a two position fiducial calibration grid (LFG) set at positions LFG1 and LFG2 a known distance apart and wherein the electron beam of the electron beam lithography system is sequentially deflected to the two positions for each lenslet being corrected. Measurement signals derived at each position are processed pursuant to a unique algorithm to derive desired height correction output signals and height corrected deflection signals for control of the fine deflector of the electron beam lithography system.

Abstract: A high velocity seek deceleration technique is disclosed for seek operations of disk drives wherein measured time per track is compared to a predetermined time per track in a memory as indexed by number of tracks to end of seek determines an error value which adjusts a deceleration amplifier. The gain of digital output to the amplifier is adjusted depending on the number of tracks to end of seek, the higher the number, the higher the gain. Further, a variable bandwidth filter is employed to increase bandwidth as velocity decreases.

Abstract: A gas laser optical recording apparatus having a write beam deflected from the optical path taken by the read beams by an acoustic optical modulator. In one embodiment the write beam is time-shared between the read optical path and the write optical path. In this embodiment an attenuator is placed in the read optical path to reduce the power of the laser beam from write power to read power. In a second embodiment 5 percent of the power is allowed to remain in the read optical path and the write beam is deflected between a beam stop and the write optical path as required.

Abstract: A method for polling headphones of a passive tv audience meter system. Tv audience members wear headphones by which they may receive the audio portion of the tv programs. The headphones are enabled to receive the audio for a short time by periodic polls transmitted by a tv audience meter. The headphones in turn acknowledge to the polls to indicate to the meter which members of the audience are watching tv. The method uses short and long period polls in conjunction with a timer whose period is shorter than the long period poll. The long period poll permits activation of headphone but also prevents adequate audio reception until the headphone acknowledges the poll. The short period poll is entered in response to the receipt of an acknowledgement and permits uninterrupted audio.

Abstract: A process for chemically bonding a lubricant to a magnetic disk by applying a functionalized polymeric lubricant to the disk, heating it until a significant portion bonds to the disk via the functional terminal group, and then reacting the unbonded residue with a chemical moiety, the residue then forming a mobile lubricant highly resistant to spin-off due to the presence of the bonded lubricant.

Abstract: Disclosed is an apparatus for detection of write protect data written on an optical disk by simultaneously reading the data during writing using differential detection and disabling further writing if write protect data is present. The write protect data is the same format as other data written on the optical disk and is written as the first byte of data on all data fields. The data is written in a fixed-block format defining a symbol having a predetermined number of symbol positions and a predetermined number of holes which may be written at the symbol positions, an equal number of holes at odd and at even positions. The write protect symbol has holes written at symbol position numbers two and five. During the writing of a write protect symbol, the laser is operated at read power before it is operated at write power and a signal associated with the hole associated power of the reflected beam is sampled at position number eight of the previous symbol and at position number one of the write protect symbol.

Abstract: Disclosed is an apparatus for verifying data written on an optical disk by simultaneously reading the data during writing and using differential detection to verify that the data has been written correctly. The data is written in a fixed-block format defining a symbol having a predetermined number of symbol positions and a predetermined number of holes which may be written in the symbol positions, an equal number of holes in the odd positions and in the even positions. In this regard, the holes written in the odd positions are independently verified from the holes written in the even positions. Immediately after the laser has been operated at write power, it is returned to read power and a signal associated with the hole associated power of the reflected beam is sampled. This signal is compared to the signal power generated at the previous even or odd position. The highest signal is retained and compared to the next even or odd position's signal.

Abstract: Disclosed is a sector mark decoder for an optical recorder. Sector marks are prerecorded on the optical recording surface and comprise a series of evenly spaced marks. Data is recorded on the media in a fixed block code via holes burned into the optical recording surface. Both sector marks and data are detected by common apparatus, but are distinguished from each other by their different recording format. The location of a hole or a prerecorded mark is determined by comparing two sample and hold cells in a comparator. One holds the read signal value received at one disk position and compares it to the signal value held in the other sample and hold cell received at the previous position. If the comparison results in a new higher valued signal being found, the output of the comparator changes. The new higher valued signal is retained and the other sample and hold cell samples at the next disk position. This sequence continues until a sector mark has been decoded.

Abstract: A one piece carrier for flatpack chips capable of accommodating chips of varying size. The carrier includes a pair of cantilever arms each having a tapered head for holding chips of varying thicknesses. The arms extend into the carrier's central aperture, one from the top and one from the bottom side of the aperture. Longitudinally offset stops are mounted on the arms to both laterally and longitudinally stabilize a small chip whose length is insufficient to reach the conventional stops mounted on the top and bottom sides of the central aperture. A recess is provided in the lateral sides of the central aperture to accommodate motion of the cantilever arms so that chips of varying widths may be held between the heads of the arms up to the width of the central aperture. A step of lower elevation is formed in the body of the carrier between the lead support channels adjacent the lateral sides of the central aperture to accommodate the formed leads of a chip.

Abstract: A mechanism for receiving, cradling, and loading, under force, a disk drive cartridge onto the drives spindle is disclosed. The mechanism has an U-shaped cradle, a transverse yoke, and a centrally mounted nub for applying downward pressure on the cartridge. A lever, actuated by motion of the drive's door, moves the cradle/yoke combination in the vertical direction.

Abstract: The invention comprises a high vacuum compatible electron beam stage having an X/Y and theta coordinate positioning drive mechanism mounted from below the stage. The stage comprises four plates: A base plate, an X plate slidably mounted thereon and constrained to slide in an X direction, a Y plate slidably mounted on the X plate and constrained to slide in a Y direction, and a theta plate mounted on the Y plate and constrained to translate in the Z direction. Two rotary capstans, mounted on drive shafts, are coupled on each to the X and Y plates by a metallic band looped around the capstan and attached at opposite ends to the plate. Rotation of the capstan causes the respective plates to slide in their constrained direction. The theta plate drive shaft is limited to vertical motion. The Y and theta drive shafts couple to universal joints. All three drive shafts couple to bellows joints. This permits the drive shafts to deflect at small angles.

Abstract: A pressurized seal which comprises the interface between a disk drive spindle housing and a disk cartridge housing whereby dirty, unfiltered air is prevented from entering the disk area of the cartridge when mounted on the disk drive. The seal is comprised of an annular stop having three channels. An inner channel has mounted therein a circular cross-sectioned, flexible tube running the length of the channel. A intermediate channel connects to a source of pressurized filtered air. An outer ring mounts a flap seal which is forced against the cartridge housing by the pressurized filtered air.