Abstract: A disk drive system is described for forming and reading precise optically detectable patterns on rotating members of a disk and spindle assembly used in data storage system. In particular the invention describes a magnetic disk drive employing a laser system to form and sense optical clock patterns placed on the rotating members of the disk drive. These optically detectable patterns are used to create an accurate clock track. The clock may be used to create multiple accurate magnetic patterns on one or more disks attached to a disk and spindle assembly in a magnetic data storage system. By successively changing the radius at which the magnetic patterns are created it is then possible to create multiple magnetic patterns at successive radii with all such magnetic patterns having a precise geometric relationship to each other. Alternatively, the accurate clock pattern may stand alone as an encoder.

Abstract: The present invention is used to form precise, optically detectable patterns on rotating members of a disk and spindle assembly of a disk drive used in data storage system. In particular, the invention employs an optical source to form optically detectable patterns on the rotating members of the disk drive. These optically detectable patterns are used to create an accurate clock track. The clock track may be used to create multiple accurate magnetic patterns on one or more disks attached to a disk and spindle assembly in a magnetic data storage system. By successively changing the radius at which the magnetic patterns are created it is then possible to create multiple magnetic patterns at successive radii with all such magnetic patterns having a precise geometric relationship to each other. Alternatively, the accurate clock pattern may stand alone as an encoder.

Abstract: Electrorheological based acoustic droplet ejectors and their applications in acoustic print heads are described. The droplet ejectors include an acoustic transducer which generates acoustic energy into a fluid well holding an electrorheological fluid such that the fluid's free surface is adjacent electric field electrodes. The acoustic energy is such that droplets are ejected from the fluid as long as a lower voltage is applied to the electrodes. However, when a higher voltage is applied to the field electrodes, the electrodes produce an electric field through the fluid which causes the viscosity of the fluid to increase sufficiently that droplet ejection is prevented. When used in a print head, the electrorheological fluid is an ink. Further, many (perhaps thousands) of individual droplet ejectors are formed in the print head. By controlling droplet ejection from the individual print heads, an image can be produced on a recording medium.

Abstract: A material deposition head having lithographically defined ejector units. Beneficially, each ejector unit includes a plurality of lithographically defined droplet ejectors. Furthermore, methods of fabricating such lithographically defined material deposition heads are also described.

Abstract: In response to the foregoing need, the cap structures that are provided by this invention for controlling the free ink surface levels of acoustic ink printers are characterized by having aperture configurations that are more or less equally subdivided into "reflectively balanced" sectors that radially differ from each other by 1/4 of the dominant wavelength of the surface ripple waves that are generated by the droplet ejection process. The 1/4 wavelength difference in the radii of the two generally equal reflectively balanced fractional parts of these apertures causes the dominant frequency components of the retroreflected ripple waves to destructively interfere with each other in the critical central regions of the apertures.

Abstract: A motion monitor which produces audible sound representative of motions of a subject or object being monitored, including a carrier, an optical fiber carried by the carrier, a laser source for injecting a laser beam in the optical fiber to produce a speckle light pattern at the output of the optical fiber, a photodetector for producing an output signal representative of modal noise developed in the optical fiber due to physical movement of the fiber, an amplifier for amplifying the output of the photodetector, and a loudspeaker which converts the amplified signals to audible sound representative of the modal noise at the fiber output. Optionally, the signals produced by the photodetector are shifted to a higher frequency range, e.g., the 500-700 Hz range, thereby to enable use of conventional inexpensive electronics and efficient loudspeakers.

Abstract: Techniques for improving droplet uniformity in acoustic ink printing. Row to row variations in an average droplet characteristic are reduced by controlling the electric power applied to the droplet ejectors of the individual rows. By applying the proper power to each row, the average droplet characteristic from the individual rows are made substantially. Another technique varies the efficiency of the individual droplet ejectors by physically trimming (such as with a laser) one or more of its components. Trimming may be performed on a droplet ejector's transducer, varactor, one or more associated resistors, or one or more capacitors. Yet another technique controls droplet ejector efficiency by electrically controlling the capacitance of a varactor associated with each droplet ejector, and thus each droplet ejector's efficiency.

Abstract: A printhead for an acoustic ink printer has a piezoelectric transducer on one surface of a substrate. A layer of a dielectric material is provided on the surface of the transducer away from the substrate. A Fresnel lens is formed in the surface of the dielectric layer away from the transducer, for focusing sound energy near the surface of a body of ink adjacent the dielectric layer. Thus the transducer and lens are both on the same side of the substrate. A pit may be formed in the substrate under the transducer. The transducer may be a body of piezoelectric material sandwiched between a pair of electrodes, the lower electrode of which has a thickness that is a quarter wave at the excitation frequency of the transducer.

Abstract: A fiber optic body motion monitor in which light is transmitted through an optical fiber waveguide physically coupled to a body being monitored, and modal noise at the output of the optical fiber waveguide is applied to a photodetector filtered, rectified and analyzed to detect breathing and heartbeats. Detection of breathing is performed by low-pass filtering the rectified and filtered signal, and adaptive thresholding of the low-pass filtered signal. A similar but separate technique is used to detect heartbeats. In one embodiment, reliability of detection is enhanced by reducing the number of speckles of light applied to the photodetector to approximately 50%, thereby to maximize modal noise current. In another embodiment the photodetector has two halves separately illuminated by approximately two-thirds of the light from the optical fiber waveguide.

Abstract: An acoustic ink printer transducer comprising a piezoelectric layer positioned between two suitable electrode materials. Also, a method for obtaining second harmonic operations from an acoustic ink printer transducer to enable ejection of a number of different ink droplet sizes from the acoustic ink printer thereby facilitating grey scale printing.

Abstract: The free ink surface levels of acoustic ink printers are controlled by cap structures that have substantially non-retroreflective aperture configurations. The non-retroreflective configurations of the apertures of these cap structures cause diffusive scattering or directional deflection of the reflected surface ripple waves, thereby significantly reducing the time that is required for the oscillatory perturbations, which are caused by reflection of the surface ripple waves that are generated during the droplet ejection process, to dissipate to a negligibly low amplitude in the critical local areas of the ejection sites. This, in turn, increases the droplet ejection rates at which printers having such cap structures can be operated asynchronously.

Abstract: A motion monitor using coherent or partially coherent light passing through an optical fiber which is in contact or close to an object whose motion is to be monitored. An optical speckle pattern is formed near the output of the optical fiber which pattern changes as the fiber moves in response to the motion of the object being monitored. An optical detector monitors all or a part of the speckle pattern and electronically processes the optical detector's electrical output signals to derive information on the status of the object being monitored.

Abstract: To improve the tolerance of acoustic ink printers to changes in their free ink surface levels, provision is made for significantly reducing the effect of half wave resonances on the acoustic power density of the acoustic beam or beams that are incident on the free ink surface of such a printer, thereby reducing its focusing sensitivity. Some of the approaches that are taken to accomplish this rely upon acoustic losses to damp out the halfwave resonances and anti-resonances, while others employ multi-frequency rf voltage pulses for driving the droplet ejector or ejectors so that the acoustic power perturbations caused by the half wave resonances and anti-resonances of the different frequencies tend to neutralize each other.

Abstract: An ink transport system for an acoustic ink printer having an array of ejectors with associated ink bodies and free surfaces. The ink transport system supplies ink to the injector ink bodies constantly, yet zeros the hydrostatic gauge pressures of the free surfaces of the ink bodies to ensure uniformity of ejector performance. The ink transport system works with linear and two-dimensional arrays of ejectors.

Abstract: Acoustic radiators which are focused diffractively by multi-discrete-phase binary Fresnel lenses are provided for applications, such as acoustic ink printing. Standard semiconductor integrated circuit techniques are available for fabricating such lenses in compliance with design specifications having relatively tight tolerances, including specifications for integrated lens arrays demanding substantial precision in the relative spatial positioning of several lenses. The diffractive performance of these lenses simulate concave refractive lenses, even though the lenses preferably have generally flat geometries. To that end, the lenses advantageously are defined by patterning acoustically flat surfaces, such as an acoustically flat face of a substrate or, better yet, an acoustically flat face of a layer of etchable material which is grown or otherwise deposited on an acoustically flat surface of an etch resistant substrate.

Abstract: In accordance with the present invention, an acoustic ink printer comprises a pool of liquid ink having a free surface in intimate contact with the inner face of a perforated membrane. The printer addresses all pixel positions within its image field via substantially uniform, relatively large diameter apertures which extend through the membrane on centers that are aligned with respective ones of the pixel positions. In operation, one or more focused acoustic beams selectively eject individual droplets of ink from the ink menisci that extend across the apertures. Accordingly, the membrane is positioned and the bias pressure that is applied to the ink is selected so that the menisci essentially remain within the focal plane of such beam or beams.

Abstract: A fail-safe optical T-coupler for coupling a local terminal having at least one light source and at least one photodetector to a segmented optical data bus comprises an optically transparent acousto-optic cell, a pair of collimating lenses for coupling adjacent segments of the data bus to opposite ends of the acoustic-optic cell symmetrically with respect to the optical axis of the coupler so that there is a fail-safe path for transmitting remotely injected light from one segment of the bus to the next, and at least one acoustic driver for coupling acoustic bulk waves into the acousto-optic cell to selectively establish or intensify an ultrasonic grating along an acoustic axis.

Abstract: A biconically tapered passive star optical coupler has mutually exclusive input and output optical fibers, so that optical power injected into any one of the input fibers is relatively uniformally distributed to all of the output fibers.

Abstract: A multi-emitter extended source solid state laser designed to omit light beams at multiple wavelengths within a narrow total spectral bandwidth, that is, a relatively incoherent composite output beam of narrow total spectral bandwidth, is used as the input to a multimode optical fiber of an optic communications link or network. By providing an incoherent composite laser input beam to the fiber, modal noise due to coherence effects are virtually eliminated so that such effects no longer affect network performance. In addition, because the source is extended, a more uniform illumination of the fiber face is achieved. An exemplary multi-emitter laser would consist of an array of simultaneously driven emitting regions or cavities which operate in multiple longitudinal modes.

Abstract: An active repeater for a star configured communications network includes a threshold detector for collision detection. Whenever two or more terminals simultaneously feed data into the repeater, a threshold sensitive collision detector is triggered to logically isolate the data from the output of the repeater and to logically substitute a predetermined collision signal therefor, thereby causing the competing terminals to reset to retry the transmissions at randomly selected later times.