To enhance piezoelectric property. One aspect of the present invention is ferroelectric ceramics including a Pb(Zr1-xTix)O3 film, wherein: the x satisfies the following formula 1, the Pb(Zr1-xTix)O3 film has a plurality of columnar single crystals, the x axis, the y axis and the z axis of each of the plurality of columnar single crystals are oriented in the same direction, respectively,0<x<1  formula 1.

Field of the Invention
The present invention relates to ferroelectric ceramics and a method for manufacturing thereof.
Conventional method for manufacturing Pb(Zr, Ti)O3 (hereinafter referred to as "PZT") film will be explained. This PZT film is one example of a perovskite-type ferroelectric ceramics.
A SiO2 film having a thickness of 300 nm is formed on a wafer of Si of 4 inches, and a TiOx film having a thickness of 5 nm is formed on the SiO2 film. Next, a Pt film having a thickness of 150 nm oriented, for example, in (111) is formed on the TiOx film, and a PZT sol-gel solution is coated on the Pt film under rotation by a spin coater. The spin condition at this time is a condition of rotation at 1500 rpm for 30 seconds, and then at 4000 rpm for 10 seconds.
Next, the thus coated PZT sol-gel solution is dried by keeping with heating on a hot-plate at 250° C. for 30 seconds to remove water, and further, is pre-calcined by being kept under heating on a hot-plate at a high temperature of 500° C. for 60 seconds. A PZT amorphous film having a thickness of 150 nm is produced by repeating the procedure several times.
Subsequently, annealing treatment at 700° C. is performed on the PZT amorphous film by using a pressurized lamp annealing apparatus (RTA: rapid thermal anneal) to thereby carry out crystallization of PZT. The thus crystallized PZT film has the perovskite structure (refer to, for example, Patent Document 1).
Description of a Related Art
Patent Document
    [Patent Document 1] WO2006/087777    [Non-Patent Document 1] Rigaku Journal 39(2)2008, PP10-17 "Technical Note X-Ray measuring method of thin film Basic structure The third high resolution X ray diffraction method Takayuki KONYA"    [Non-Patent Document 2] Hunsai No. 56(2013), pp 38-41 "Special/Front line of application of nano particle technology Role and future advance of nano particles in ferroelectric piezoelectric device Yuji NOGUCHI, Yuki KITANAKA, Masaru MIYAMA"

Feroelectric ceramics and method for manufacturing the same


A swimming pool water analyzer has a housing providing a coulometric titration chamber, a chlorine concentration measuring chamber, a chamber for measuring pH, and conduits connecting the several chambers, the reservoir and a discharge outlet. One or more pumps move fluid through the conduits and chambers to the discharge outlet. Electrodes in each of the chambers are connected to electrical circuitry, and a power supply is provided. A microprocessor receives and analyzes signals indicative of the activity at the electrodes and provides outputs representing values for the chemistry of the sample determined as a result of such analysis of the signals.

The present invention relates to apparatus for analysis of water and, more particularly, to microprocessor controlled apparatus for concurrently performing a series of electrochemical analyses on a sample of swimming pool water.
It has long been known that it is desirable to balance the chemicals added to swimming pool water in order to control bacteria and algae while avoiding excessive free chlorine and limiting the amount of deviation of the pH from neutral. If this balancing is not done properly, contaminated pool water may cause infections or appear cloudy, or the pool wall may become slimy. If free chlorine level and pH are not controlled, the eyes and skin may be irritated.
As a result, pool owners frequently conduct tests to determine pH and chlorine content and, based upon the measured values, add estimated amounts of pool water treatment chemicals. However, the tests which are generally conducted by a home pool owner are of limited character and are generally insufficient to effect full control over the desired chemistry of the water.
Generally, desirable analyses of swimming pool water would include determinations of all or most of the following: cyanuric acid content, pH, free chlorine, dissolved solids, and total alkalinity. With this information, and information as to the total water volume of the pool, it is possible to calculate the amount of various chemical additions required to balance the chemistry of the pool water.
In the late 1970's, Applicant's assignee introduced a computer controlled apparatus utilizing various reagents to effect coulometric evaluation of swimming pool water samples. The operation and accuracy of this apparatus have been enhanced over the years, but there has been a desire to make analysis faster, less complex and more accurate. Moreover, its use of reagents and test tubes for testing has required restocking of reagents and washing of test tubes.
It is an object of the present invention to provide a novel microprocessor controlled apparatus and method for automatically analyzing swimming pool water samples by electrochemical techniques.
It is also an object to provide such apparatus which is reliable and long-lived, and which is simple to operate.
Another object is to provide such apparatus and method which will provide an output indicating the amounts of various chemicals to be added to the pool water to balance its chemistry.
A further object is to provide such apparatus which is simple to maintain and which is operable without reagents or other chemical additives.

Method and apparatus for analysis of swimming pool water and analytical cell utilized therein


Devices, systems, methods, and computer-implemented methods to facilitate transmitting microwave signals to one or more cryogenic stages of a cryogenic refrigerator are provided. According to an embodiment, a device can comprise a monolithic signal carrier device comprising a thermal barrier disposed within a ground layer and a signal layer. The device can further comprise a thermal decoupling device coupled at the thermal barrier to the ground layer and the signal layer.

The subject disclosure relates to signal carrier devices, and more specifically, to a monolithic signal carrier device that can facilitate transmitting microwave signals to a quantum computing device in a cryogenic refrigerator. Quantum computing is generally the use of quantum-mechanical phenomena for the purpose of performing computing and information processing functions. Quantum computing can be viewed in contrast to classical computing, which generally operates on binary values with transistors. That is, while classical computers can operate on bit values that are either 0 or 1, quantum computers operate on quantum bits that comprise superpositions of both 0 and 1, can entangle multiple quantum bits (qubits), and use interference.
Universal quantum computers (e.g., quantum computing hardware) require many physical qubits (e.g., millions) and error correction schemes require access to all such qubits (e.g., microwave signal transmission to all such qubits). A problem with current state-of-the-art systems is that access to one or more stages (e.g., a mixing chamber stage) of a cryogenic refrigerator (e.g., a dilution refrigerator) is limited to the number of connectors that can physically fit through cryogenic plates that define the stages of the cryogenic refrigerator. Existing systems are limited to approximately 200 ports for input and output, and thus, such systems can only facilitate transmission of approximately 100 independent microwave signals to and from quantum computing hardware (e.g., to 100 qubits). Another problem with current state-of-the-art systems is that they require several connection components at and/or between each cryogenic plate to ensure thermal isolation of such components in each stage of the cryogenic refrigerator. For example, such existing systems require several bulkheads (e.g., subminiature version A (SMA) bulkheads), attenuators, and coaxial cables for each port that accesses a quantum computing device at the mixing chamber stage of a cryogenic refrigerator.

Monolithic signal carrier device implemented in cryogenic quantum computing applications

INTERNATIONAL BUSINESS MACHINES CORPORATION


Hydrocarbylethyl sulfonyl fluorides in which the hydrocarbyl substituent contains at least 3 carbon atoms, can be prepared by reacting 2-mercaptoethanol with chlorine to form chloroethyl sulfonyl chloride which is treated with aqueous potassium fluoride to yield chloroethyl sulfonyl fluoride, followed by treatment with magnesium oxide to yield vinyl sulfonyl fluoride. The vinyl sulfonyl fluoride is adducted to a hydrocarbyl substituent precursor, such as an olefin or halogenated olefin. A representative compound is polyisobutenyl sulfonyl fluoride. The hydrocarbylethyl sulfonamide products for which the hydrocarbylethyl sulfonyl fluorides are intermediates are useful as additives for lubricating oils.

Field of the Invention
This invention relates to processes for preparing hydrocarbylethyl sulfonyl fluorides. The higher-molecular-weight compounds are useful as intermediates for lubricating oil additives. The intermediate-molecular-weight compounds are useful as detergent intermediates, and the lower-molecular-weight compounds are useful intermediates in the preparation of agricultural and medicinal compounds. This invention further relates to hydrocarbylethyl sulfonyl fluorides, methods for their preparation, and lubricating oil additives and compositions prepared from them.
Dispersants for use in lubricating oils have become a necessity for use in modern engines. One such class of dispersants is hydrocarbylethyl sulfonamides. A method for their preparation via a new intermediate enables these sulfonamides to be easily produced.


Objects are levitated in a sound system substantially free of reverberation and reflection by positioning a small reflector in the path of sound waves. Interference between the primary waves and reflected waves creates a localized zone of minimized energy closely adjacent to the reflector in which an object may be stably levitated. The energy well thus produced is not dependent upon distance from the sound source, and the levitated object may be moved in any direction by moving the reflector. A plurality of reflectors may be employed to manipulate and combine levitated materials, and improvements in the processing of levitated objects are also achieved.

The principles of acoustic levitation are well established. It is known that sound exerts a small but continuous force on materials in a sound field over and above the pressure oscillation occuring at that frequency. Various schemes have been devised whereby such continuous forces are maximized sufficiently to enable small objects to be suspended in a sound field without visible means of support.
The potential applications for acoustic levitation, positioning and manipulation are numerous and varied. Many potential applications exist whenever there is a need to hold, move, store or position an object without contact with any surface, particularly if such contact would contaminate or damage the object or otherwise interfere with some desired property or state of the object. For example, an object that is melted by conventional means at high temperatures will be contaminated by the container, and acoustic levitation offers the possibility of containerless melting as well as other containerless or non-contact processing involving, for example, chemical reaction, alteration of physical shape, coating, combining, conveying, and the like.
Acoustic levitation also lends itself to manufacturing processes in outer space by preventing drift of the materials being processed. In this connection, several proposals have already been made for the processing of acoustically positioned objects in future space stations.
Of the acoustic levitation systems heretofore proposed, all have exhibited serious drawbacks or limitations that affect practical usage or otherwise restrict performance under a variety of conditions. All previous systems utilize resonant cavities that must be carefully tuned and because of the cavity nature are limited in physical geometries. For example, U.S. Pat. No. 3,882,732 describes a resonant rectangular chamber utilizing three sound transducers arranged in three normal axes. The system is used to establish a standing wave pattern to urge an object toward a zone of minimum pressure. Tuned cylindrical chambers have also been proposed but similarly suffer from the requirement to be tuned.
In another proposed system, a single sound source is used, and a large reflector is placed at a critical distance from the sound source to produce standing waves.
In all of the foregoing, the geometry of the system is critical and variations in temperature cause the system to detune. If a reflective surface is used to produce a standing wave, the distance between the sound source and reflective surface must be maintained at n (x/2), where x is the wavelength of the sound, and n is a whole number. If the temperature should change, the wavelength of the sound is also changed. As a result, the system will no longer be in resonance, the standing wave will be destroyed, and the levitation will be lost.

Acoustic levitation and methods for manipulating levitated objects


A method of diminishing the symptoms of neurodegenerative disease in a patient is disclosed. In one embodiment, the method comprises the steps of: (a) identifying a patient with a neurodegenerative disease, (b) producing a cell culture, wherein the cell culture comprises cells with induced antioxidant response element (ARE) mediated transcription, and (c) transplanting at least a portion of the cell culture into the brain of the patient, wherein symptoms of neurodegenerative disease are diminished.

The present invention is concerned with the treatment of neurodegenerative diseases, most particularly neurodegenerative diseases characterized by mitochondrial dysfunction.
The importance of mitochondrial dysfunction in neurodegenerative diseases, such as Huntington's Disease (HD), is underscored by the observation that complex II inhibitors produce a symptomology that is strikingly similar to HD, including select damage the medium spiny neurons of the striatum while sparing the aspiny neurons, and similar behavioral deficits (Ming, L., J. Toxicol. Clin. Toxicol. 33:363-367, 1995; Liu, X., et al., Biomed. Environ. Sci. 5:161-177, 1992; Ludolph, A. C., et al., Can. J. Neurol. Sci. 18:492-498, 1991; Palfi, S., et al., J. Neurosci. 16:3019-3025, 1996; Bossi, S. R., et al., Neuroreport 4:73-76, 1993). Consequently, the complex II inhibitors 3-nitropropionic acid (3NP) and malonate have been used extensively to model HD in vitro and in vivo (Brouillet, E., et al., Prog. Neurobiol. 59:427-468, 1999; Schapira, A. H., Curr. Opin. Neurol. 9:260-264, 1996). Like genetic models of HD, complex II inhibitors generate ROS (Perez-Severiano, F., et al., supra, 2004; Wyttenbach, A., et al., supra, 2002) as a direct consequence of disruption of the electron transport chain and excitotoxicity via a calcium influx through the N-Methyl D-Aspartate receptor (Reynolds, I. J. and T. G. Hastings, J. Neurosci. 15:3318-3327, 1995; Dugan, L. L., et al., J. Neurosci. 15:6377-6388, 1995; Albin, R. L. and J. T. Greenamyre, Neuroloqy 42:733-738, 1992). Additionally, the high concentration of striatal dopamine may contribute to ROS production and exacerbate the damage caused by complex II inhibition (Jakel, R. J. and W. F. Maragos, Trends Neurosci. 23:239-245, 2000). Striatal dopamine depletion attenuates damage caused by either 3NP or malonate in vivo (Maragos, W. F., et al., Exp. Neurol. 154:637-644, 1998). Conversely, enhanced dopamine release by methamphetamine potentiates 3NP (Reynolds, D. S., et al., J. Neurosci. 18:10116-10127, 1998).
One mechanism by which cells respond to oxidative insults is through the antioxidant response element (ARE), a cis-acting enhancer sequence that regulates the transcription of many cytoprotective genes. Upon toxic insult, glutathione depletion or chemical activation, the transcription factor Nrf2 translocates to the nucleus and dimerizes with small Maf proteins to form a trans-activation complex that binds to the ARE [For a review of Nrf2 regulation see Nguyen, et al., Free Radic. Biol. Med. 37:433-441, 2004]. Consequently, Nrf2-induced ARE activation coordinates the expression of many genes involved in combating oxidative stress and toxicity in a wide variety of tissues and cell types (Chan, K. and Y. W. Kan, Proc. Natl. Acad. Sci. USA 96:12731-12736, 1999; Ramos-Gomez, et al., Proc. Natl. Acad. Sci. USA 98:3410-3415, 2001; Cho, H. Y., et al., Am. J. Respir. Cell Mol. Biol. 26:175-182, 2002; Enomoto, A., et al., Toxicol. Sci. 59:169-177, 2001; Gao, X. and P. Talalay, Proc. Natl. Acad. Sci. USA 101:10446-10451, 2004; Lee, J. M., et al., J. Biol. Chem. 278:37948-37956, 2003; Thimmulappa, R. K., et al., Cancer Res. 62:5196-5203, 2002). In addition to protecting against chemical insults, carcinogenesis, and aging (Thimmulappa, R. K., et al., supra, 2002; Suh, J. H., et al., Proc. Natl. Acad. Sci. USA 101:3381-3386, 2004; Talalay, P. and J. W. Fahey, J. Nutr. 131:3027S-3033S, 2001; Zhang, Y. and G. B. Gordon, Mol. Cancer Ther. 3:885-893, 2004), Nrf2 has been shown to directly inhibit Fas-mediated apoptosis, a substrate for caspase-3-like proteases and an effector of PERK-mediated cell survival (Ohtsubo, T., et al., Cell Death Differ. 6:865-672, 1999; Kotlo, K. U., et al., Oncogene 22:797-806, 2003; Cullinan, S. B. and J. A. Diehl, J. Biol. Chem. 279:20108-20117, 2004; Cullinan, S. B., et al., Mol. Cell Biol. 23:7198-7209, 2003).
HD is an autosomal dominant neurodegenerative disorder that results from a polyglutamine repeat expansion in the in the first exon of the huntingtin gene (The Huntington's Disease Collaborative Research Group, Cell 72:971-983, 1993). Hallmarks of HD include severe degeneration of striatal medium spiny neurons and progressive choreiform movements (Graveland, G. A., et al., Science 227:770-773, 1985; Reiner, A., et al., Proc. Nat. Acad. Sci. USA 85:5733-5737, 1988). There are many proposed mechanisms of huntingtin-induced neuronal degeneration, yet no model fully explains the progression from mutation to cell death. Huntingtin aggregation, excitotoxicity, and oxidative stress have been suggested to play key roles in disease progression. However, the mechanism by which these factors arise and influence each other is largely unclear. Furthermore, it is unknown why striatal neurons are most susceptible to mutant huntingtin yet the protein is expressed ubiquitously.
One model of HD pathogenesis centers around mitochondrial dysfunction, excitotoxicity and subsequent reactive oxygen species (ROS) production (Calabrese, V., et al., Neurochem. Res. 26:739-764, 2001; Brown, S. E., et al., Brain Pathol. 9:147-163, 1999; Beal., M. F., Ann. Neurol. 38:357-366, 1995). Mitochondrial deficiencies, including reduced overall respiration and reduced activities of complex II, III and IV, have been measured in the striatum of post mortem HD brains (Gu, M., et al., Ann. Neurol. 39:385-389, 1996; Brennan, W. A., Jr., et al., J. Neurochem. 44:1948-1450, 1985). Similarly, reduced mitochondrial activity has been observed in at least one genetic mouse model of HD (Tabrizi, S. J., et al., Ann. Neurol. 47:80-86, 2000), and enhancement of electron transport by Coenzyme Q10 is effective in genetic models (Ferrante, R. J., et al., J. Neurosci. 22:1592-1599, 2002; Andreassen, O. A., et al., Neurobiol. Dis. 8:479-491, 2001; Ferrante, R. J., et al., J. Neurosci. 20:4389-4397, 2000; Schilling, G., et al., Neurosci. Lett. 315:149-153, 2001). HD patients also display increased ROS production in red blood cells and the striatum (Zanella, A., et al., J. Neurol. Sci. 47:93-103, 1980; Kuhl, D. E., et al., Ann. Neurol. 12:425-434, 1982; Martin, W. R., et al., J. Neuroimaging 5:227-232, 1995; Antonini, A., et al., Brain 119(Pt. 6):2085-2095, 1996) which is reflected in in vitro and genetic mouse models of HD (Andreassen, O. A., et al., supra, 2001; Hurlbert, M. S., et al., Diabetes 48:649-651, 1999; Perez-Severiano, F., et al., Neurochem. Res. 29:729-733, 2004; Wyttenbach, A., et al., Hum. Mol. Genet. 11:1137-1151, 2002).
Previously we have demonstrated that Nrf2-dependant transcription can prevent ROS-induced apoptosis in neurons and astrocytes in vitro (Lee, J. M., et al., supra, 2003; Lee, J. M., et al., J. Biol. Chem. 278:12029-12038, 2003; Shih, A. Y., et al., J. Neurosci. 23:3394-33406, 2003; Kraft, A. D., et al., J. Neurosci. 24:1101-1112, 2004; L1, J., et al., Physiol. Genomics 18:261-272, 2004).
In the Examples below, we demonstrate that Nrf2 and ARE-dependant signaling are critical mediators of the cellular response to mitochondrial inhibitors in vitro and in vivo. Furthermore, we show that further ARE induction can protect against complex II inhibitor toxicity.

This patent is subject to a terminal disclaimer.

Method of diminishing the symptoms of neurodegenerative disease


An ultrasonic material-evaluation or classification method using spectral and envelope-statistics variables from backscattered ultrasound echo signals using an adaptive-bandwidth and combined with global variables. This classification method can be applied to any organ or tissue among biological materials and any non-biological material that produces backscattered signals as a result of microscopic internal in homogeneities such as a crystalline structure.

The improvements described herein generalize the definition of QUS by adding:
(1) estimates based on variables of the statistics of the envelope of linearly amplified, radio-frequency ultrasound echo signals backscattered from biological or non-biological materials to
(2) estimates based on variables of normalized power spectra of linearly amplified, radio-frequency ultrasound echo signals in previously described QUS methods such as those shown in the '342 patent, and optionally
(3) one or more global variables such as clinical data, e.g., antigen level or patient age, when typing tissue or such as material properties, e.g., acoustic attenuation or mass density, when typing non-biological material.
The improvements also generalize the application of the covered QUS methods to any and all materials in which pulse-echo ultrasound produces echo signals within the material and where such echo signals result from spatial variations in the acoustical impedance of the material on a scale of fractions to multiples of the incident acoustical-pulse wavelength.
Although specific clinical examples are cited herein to illustrate applications of the described method, the method is applicable to a very broad range of material-typing and imaging applications in addition to the cited clinical, tissue-typing and imaging applications. Examples of potential non-biological material-typing and imaging applications include, but are not limited to, assessment of composite quality, fiber density in fiber-reinforced plastics, crystalline-material properties, particle size and concentration in liquid suspensions, etc. An example of a potential non-clinical, biological-material typing and imaging includes, but is not limited to, beef-quality grading. Examples of potential clinical applications include, but are not limited to, distinguishing among healing, non-healing and infected wounds; distinguishing between ischemic and non-ischemic myocardium; distinguishing among progressing, static, and regressing lesions; distinguishing between lesions that are responsive to treatment and those that are unresponsive to treatment; etc. Furthermore, in clinical applications, the method may be able to grade conditions such as, for example, the degree of treatment response, severity of ischemia, extent of infection, rate of healing, depth of burns, pressure or friction-ulcer status, progression of disease; etc.
For example, two salient, representative clinical applications are detection and imaging of cancer in the prostate gland or of metastases in lymph nodes. Reliable detection of primary-cancer foci in the prostate or metastatic foci in lymph nodes is critical for staging the disease and planning its treatment. The described method of cancer detection analyzes raw ultrasound echo-signal data in two- or three-dimensions (2D or 3D) in combination with global clinical variables such as serum PSA (prostate-specific antigen) values in the case of prostate cancer or primary-tumor type in the case of lymph-node metastases to generate 3D images that depict cancerous foci in the prostate or lymph nodes and thereby that reliably detect, characterize, and localize metastatic regions.
A reliable method using spectrum-analysis-based QUS to characterize and type biological tissue is described in the '342 patent and is incorporated herein by reference. The '342 patent describes a method that combines spectrum-analysis-based QUS variables (i.e., the slope, intercept, mid-band variables of the so-called normalized power spectrum and also the effective scatterer size and so-called acoustic concentration estimates that are derived from the spectral variables and known ultrasound-system properties) with global clinical data.
The improvements described herein additionally combine variable values of the envelope statistics of ultrasound echo signals derived from the tissue of interest with the spectrum-analysis-based variable values and global variables described in the '342 patent, and/or described herein.

Typing and imaging of biological and non-biological materials using quantitative ultrasound


A skid shoe assembly for use on a snow thrower includes a bracket having a mounting portion configured to couple to the snow thrower and a support portion extending generally perpendicular from the mounting portion. The skid shoe assembly also includes a replaceable insert composed of a plastic material. The insert includes an elongated body extending generally parallel to the support portion and configured to engage a ground surface.

The present invention relates to utility machines and, more particularly, to skid shoes for utility machines.
Utility machines (e.g., lawn mowers, lawn tractors, trimmers, tillers, snow throwers, etc.) are generally used for outdoor applications such as landscaping, gardening, lawn care, or snow removal. A snow thrower typically includes an auger supported within an auger housing. While removing snow from a surface, the auger housing rests on the surface, and snow is channeled through the auger housing as the snow thrower is maneuvered about the surface. As the auger housing slides along the surface, the auger housing may scrape and mar the surface.


A sudden-stop brake-light warning system (10) that causes the brake lights (56) of a vehicle to intermittently pulsate. The pulsation of the lights (56) is achieved by a flashing brake-light circuit (12) that is only activated when the brake pedal is depressed during a panic stop. The circuit (12) consists of a mercury switch (51), located in an inertia operative switching circuit (16), that closes only when the brake switch (54) is depressed during a panic stop. When the switch (54) closes, the power from the vehicle battery (52) is applied to the gate of a silicon controlled rectifier (CR1) located in a silicon controlled rectifier circuit (18). The energizing of CR1 enables a multivibrator circuit (14) connected via a relay driven transistor (Q3) to the coil (20A) of a relay (K1) located in a relay drive/relay circuit (20). The relay is pulsed in accordance with the time constant of the multivibrator and as the coil (20A) pulses, so are the brake lights (56).

It has long been known that intermittently flashing lights attract more attention than lights that illuminate constantly. This is particularly true in automobiles where currently, the turn indicating lights in both the front and back flash intermittently to warn and alert drivers of an impending left or right turn. However, even though flashing lights are more noticeable, they are not employed with vehicle brake lights. The brake lights in current use, conventionally remain continuously illuminated as long as the brake light switch remains closed by the continuous pressure applied to the brake pedal.
The conventional brake light circuit which operates a pair of lights located at the rear of a vehicle has in many instances failed to produce adequate warning. This problem is especially prevalent on newer vehicles that have a large assemblage of lights on the rear panel of the vehicle. In addition, turn signals which are normally located in the same light assembly with the taillights and stoplight often add to the confusion as to whether brakes are being applied or a turn is to be made.
One of the problems in driving is that to drive safely, a driver needs to know how quickly the automobile in front is slowing down with conventional brake lights, an illuminated light only-means that the driver has his or her foot on the brake pedal. The trailing driver does not know if the vehicle is decelerating slowly or whether a sudden panic stop is about to take place. The brake light used in conventional vehicles looks the same in either case.
With vehicles traveling at high speeds on interstate and freeway road systems with relatively little spacing between vehicles; the ambiguity in brake lights can and has caused rear end collisions with consequent vehicular damage, human injury, loss of life and further road congestion.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention however, the following U.S. patents were considered related:
______________________________________ U.S. PAT. NO. INVENTOR ISSUED ______________________________________ 5,059,947 Chen 22 October 1991 4,663,609 Rosario 5 May 1987 3,593,278 Bower 13 July 1971 3,528,056 Voevodsky 8 September 1970 ______________________________________
U.S. Pat. No. 5,059,947 issued to Chen, discloses a vehicle brake warning device for use in a vehicle with a brake pedal. The device includes a detector for producing different electrical signals in response to the magnitude of the inertia force experienced during braking. Whenever a pressing force is exerted on the brake pedal, the detector experiences an inertia force whose magnitude depends upon the speed of the vehicle. The detector sends an appropriate signal dependent upon the magnitude of the inertia force to a control circuit which then activates a warning device which activates the brake lights.
U.S. Pat. No. 4,663,609 issued to Rosario discloses a brake light warning system for a motor vehicle which causes the brake lights to flash in a manner to attract the attention of a driver to the rear of the vehicle. The system provides a warning of a slow down or stopping of the vehicle upon the application of the brakes. The brake lights are first caused to flash rapidly for 2 or 3 times for a first interval of time followed by prolonged "on" periods interrupted periodically by a short "off" period followed by a short "on" period followed by a short "off" period for a second interval of time as long as pressure is applied to the brake pedal of the vehicle.
U.S. Pat. No. 3,593,278 issued to Bower discloses a vehicle brake light system wherein a flashing signal of variable frequency indicates the rate of deceleration of a vehicle. The system includes a series of inertia switches and resistors forming a decelerometer, a multivibrator and a transistorized gate circuit which flashes the brake lights at a frequency proportional to the detected rate of deceleration.
U.S. Pat. No. 3,528,056 issued to Voevodsky discloses a device for measuring the deceleration of a leading vehicle. The device uses an accelerometer formed by mercury switches tilted at different angles with respect to a horizontal. They are progressively closed as the deceleration increases. In another form, deceleration is measured by brake pressure and in still another form a tachometer device is coupled to a rotating part of the automobile. The warning light, mounted on the leading car, is flashed at a rate which varies exponentially with a component of deceleration.
For background purposes and as indicative of the art to which the invention relates, reference may be made to the following remaining patents found in the search:
______________________________________ U.S. PAT. NO. INVENTOR ISSUED ______________________________________ 4,983,953 Page 8 January 1991 4,403,210 Sullivan 6 September 1983 3,559,164 Bancroft 26 January 1971 3,382,405 Johnson 7 May 1968 ______________________________________


Improved performance in a fiber interferometer gyro results from eliminat signals attributed to unwanted reflections from the fiber ends and the coupling lenses. A coiled single-mode fiber bidirectionally transmits beams radiating from a continuous wave laser to a detector. A fixed frequency oscillator amplitude modulates the laser output and provides a reference signal at the same frequency to enable synchronous detection of the detector output signals. Shifting the reference signal .pi./2 radians from the modulating signal eliminates the detector output signals which are attributed to reflections from the fiber ends and coupling lenses. By properly selecting the modulating frequency and reference phase, the information validity of beam signals passing through the coiled single-mode fiber is enhanced.

A recent development that improves the capabilities of inertial systems which stabilize aircraft, missiles, torpedoes, etc. is the fiber interferometer gyro. This is a relatively rugged, reliable and long-term accurate device in which applied rotation rates cause changes in the output intensity of the interferometer. Detection of these changes gives a measure of the rotation rate. One of the first disclosures of such a gyro was by Vali and R. W. Shorthill as "Fiber Laser Gyroscopes" at the East Coast Conference of SPIE in Reston, Virginia on March 22 and 23, 1976.
The essential elements of the Vali et al., fiber interferometer gyro are schematically depicted in FIG. 1 as prior art although the Vali et al., gyro applied a pair of beamsplitters and associated detectors and coupling lenses. The output of a continuous wave laser is divided by a beamsplitter into two beams which circulate in opposite directions in a long, multiple turn, single-mode fiber. The beams exit the fiber and are recombined at the beamsplitter. Their interference pattern is translated by a photodetector into an electronic signal representative of the applied rotation rate.
However, in addition to the beams transmitted through the coiled single-mode fiber, beams are reflected from the fiber ends and from the input/output coupling lenses. These reflected beams also are translated at the photodetector and can interfere with the desired signals (those indicative of rotation rate) and cause erroneous indications of the measurements of the rotation rate.
Schemes for elimination of these reflections mostly have followed two methods. The first, shown as prior art in FIG. 2 of the drawings, employs special antireflection coated lenses and beamsplitters. The fiber ends are polished or cleaved at an angle to deflect the reflected beams along a path which is not coincident with the optical axis of the fiber interferometer. The alternative method calls for the immersion of the entire optical component in a bath of an index matching liquid. The index matching liquid eliminates a variety of reflections since the objectionable reflections occur only at interfaces between media of different refractive indices.
Both of these methods have disadvantages. Both are costly and complex to implement. Generally speaking, shaping the ends degrades the optical surfaces and decreases the gyro signal quality. Grinding and polishing fiber ends at an angle while maintaining a good optical quality surface requires involved fabrication procedures which must be done by skilled techniques. Even when highly skilled technicians and sophisticated equipment are employed and the best fabrication methods are followed, the resulting surfaces generally have scratches and pits making the cleaved fiber end approach unsatisfactory. Immersion of the interferometer in an index matching liquid is not a practical method suitable for a gyro's operational environment. In such an environment there are usually large temperature variations and possible severe mechanical vibrations. These effects introduce variations in the refractive index of the liquid and cause intensity fluctuations with consequent gyro output signal errors.
Thus, there is a continuing need in the state-of-the-art for an apparatus and method for reducing the reflection signals from fiber ends and coupling lenses which is consistent with the rugged, reliable and uncomplicated system of the fiber interferometer gyro.

Method to eliminate fiber interferometer reflections

The United States of America as represented by the Secretary of the Navy


An intrusion detector having a transmitter, receiver, detector, signal processor, and control unit is disclosed. The transmitter is able to transmit waves into a defined space and has a variable output power. The receiver is able to receive those waves after reflection. The detector is connected to the receiver and able to detect a signal based on a change in the waves after reflection, where the detected signal is representative of any motion in the defined space. The signal processor is able to process the detected signal in order to determine if an intrusion has occurred. The control unit is able to determine any change in the detected signal, and to increase the output power of the transmitter in response to such change. A method for performing such intrusion detection is also disclosed.

1. Technical Field
The present invention relates to an intrusion detector with power consumption control. More specifically, the invention relates to a vehicle intrusion detector of the type based on Doppler effects of transmitted ultrasonic waves. The invention also relates to a method for intrusion detection.
2. Background Information
Intrusion detectors are known for creating unwanted false alarms. This is particularly true in vehicle intrusion detectors. Not only do they create a disturbance to people in the neighborhood and risk reducing or eliminating the power source, they also tend to result in common acceptance of active alarms, thereby decreasing the discouraging effect of alarms on potential burglars.
Detectors based on transmission of waves in, for example, the interior of a car have been developed and are known in the art. Typically, these systems receive waves reflected from the interior surroundings, demodulate them, pass them through a band pass filter, integrate the band pass signal, and compare the result with a predefined threshold value. If the threshold is exceeded, a signal is passed to a unit responsible for giving off an alarm. The waves are often ultrasonic sound waves or microwaves, and the demodulation performed is often based on the Doppler effect.
U.S. Pat. No. 5,856,778 to Kani et al. discloses a vehicle intrusion detector of this type that is an improvement of this wave transmission technique. The detector of Kani also includes an envelope detecting circuit for determining the level of the received ultrasonic signal. An alarm is generated only if this ultrasonic level exceeds a second predefined threshold value.
Intrusion alarms also face the problem of power consumption, especially in a vehicle or any other location where power is a scarce resource. A vehicle alarm is active only when the vehicle is parked and turned off, making it completely dependent upon the available battery power. If the vehicle is parked during a long period, it is crucial that power consumption is minimized, as the vehicle otherwise will be difficult to start.
In a detector such as the one described in U.S. Pat. No. 5,856,778, the issue of power consumption differs with the first issue of avoiding unwanted false alarms, as alarm accuracy depends on a relatively strong ultrasonic wave transmitter, and therefore increased power consumption. In order to overcome excessive power consumption, the supersonic transmitter is driven intermittently. However, this approach is not free from problems. First, the ability of the detector to detect any intrusion is greatly reduced, as it is active only part of the time. During inactive or intermittent periods, the detector is xe2x80x9cblindxe2x80x9d, allowing intrusions, although short, to occur unnoticed. Secondly, the output frequency of the supersonic transmitter is unstabilized at the beginning of each active period, making it difficult to stabilize the detection operation of the detector. Thus, there is an increased risk of obtaining a false alarm due to this unstable period occurring in each active period.
A solution for this problem is provided in U.S. Pat. No. 5,483,219 to Aoki et al. Aoki discloses a device that invalidates the signal from the integrating circuit during a short period of each active period. Still, this is not a completely satisfactory solution. Further, it does not in any way improve the partial xe2x80x9cblindnessxe2x80x9d of the detector.
As such there is a need for an intrusion detector that is able to combine a high detection level, good signal quality, and low power consumption.
The present invention provides an intrusion detector that overcomes the above problems, making it possible to continuously detect intrusions while simultaneously reducing power consumption. The invention also provides a vehicle intrusion detector with continuous transmission of waves having satisfactorily low power consumption.
These and other objects are achieved by a detector having a transmitter, receiver, detector, and control unit. The transmitter has a variable output power and is able to transmit waves into a defined space. The receiver is able to receive those waves after they reflect. The detector is connected to the receiver and is able to detect a signal based on a change in the waves after reflection, with the detected signal being representative of any motion in said defined space. The control unit is able to determine any change in the detected signal, as well as increase the output power of the transmitter in response to such change. They are also achieved by a method for intrusion detection involving transmitting waves into a defined space, receiving those waves after reflection, detecting a signal based on a change in the waves after reflection, where the reflected signal is representative of any motion in the defined space, controlling an output power of the wave transmission, and increasing the output power in response to a change in the detected signal.
When using a detector according to the invention, waves are transmitted into a defined space, and reflected back to the receiver (sensor), and the reflected waves are processed to obtain a signal corresponding to any change caused by motion in the space. The output power of the transmitter is variable, and a micro-controller (MCU) is arranged to increase the output power in response to a change in said signal.
This arrangement makes it possible to avoid driving the transmitter with a high power output, unless a signal representing motion in the vehicle has been detected. This in turn allows the power consumption to be lowered considerably without losing the continuous transmission of waves into the space.
According to a preferred embodiment, the detector includes a signal processor that is able to process the detected signal in order to securely determine if an intrusion has occurred. This processing can be of any suitable type, possibly of a previously known kind. It is typically dependent on a satisfactory signal-to-noise ratio in order to perform the analysis.
During normal functioning when no motion is detected, the transmitter output power is kept at a low level. A change in the reflected waves thus results in a very weak signal that cannot be securely analyzed in order to eliminate false alarms. As soon as the signal is detected, implying that any motion is present in the vehicle, and the transmitter output increased by the MCU, a significantly stronger detected signal is provided, considerably increasing the signal-to-noise ratio. This makes it possible to use advanced detection algorithms whereby the detected signal can be analyzed in order to securely determine whether or not the detected change is due to an intrusion. In the case of extreme weather conditions or traffic noise that result in high signal levels, those detected signals can be identified and removed by advanced algorithms without any significant increase in power consumption.
To further decrease power consumption, the signal processor can be deactivated during periods of low power transmission. The control unit is then arranged to activate the processor only when a change in the detected signal is determined, i.e., when the output power is increased.
One preferred way of embodying the output power control is to allow the control unit to raise the output power of the transmitter to a higher output level when the detected signal exceeds a predefined threshold.
Preferably, the control unit is then arranged to reset the output power of the transmitter to a lower output level after a predetermined period of time without any intrusion detection. Each time the detected signal exceeds the threshold, the intrusion detector will then be placed in an alert condition with a higher output power and a significantly increased possibility of identifying intrusions. If the detector signal increase is found to be a xe2x80x9cfalsexe2x80x9d alarm and no intrusion can be securely determined, the output power will be reset again, thereby effectively reducing power consumption.
The waves that are transmitted into the defined space can be any type of waves that can be carried by the medium filling the space. In the normal case of an air-filled space, possible wave types include sound waves and electromagnetic waves (e.g., microwaves or infrared waves).
In one embodiment of the invention primarily intended for use in a vehicle, the waves are ultrasonic waves. These waves have the advantage of being evenly distributed in the vehicle, while at the same time being confined by the vehicle walls and windows. Also, at least compared to microwaves, ultrasonic waves have a lower frequency, facilitating detection of any change in the reflected waves caused by an intrusion.
With microwaves, the transmitter generates a well-defined wave field, making good detection possible in defined areas. An advantage with using microwaves is that the detector is undisturbed by air movements, for example, movements due to an open window. On the other hand, the wave field must be carefully adjusted within the space. Otherwise, movements outside a window can be unintentionally detected.
As mentioned, infrared waves are another possible wave form. However, infrared waves are more sensitive to temperature changes and light phenomena typically introduced through the windows of a vehicle.
The signal detected by the detector in the reflected waves can be of different types, as the detection can be based on various types of phenomena occurring in the reflected wave field.
In one embodiment of the invention the detection is based on the Doppler effect. This technique is commonly known in intrusion detectors, including those found in vehicles as well as in other types of movement detectors. The technique can be utilized with ultrasonic waves as well as with electromagnetic waves. An advantage of using the Doppler effect is that the geometric form of the space is less influential on the result, which is advantageous in, e.g., a vehicle with a typically complex geometry. When using the Doppler effect in connection to microwaves, the detection can be based on pulse Doppler effect.
The detection of the Doppler signal can be performed with an envelope demodulator. The envelope of the reflected waves has the advantage of being phase and frequency independent, i.e., synchronization is not crucial. This in turn results in a greater freedom when placing the detector in a convenient space, such as a vehicle passenger compartment, especially in vehicle intrusion detectors, as it allows for a more compact design.
Instead of Doppler effect, a time discriminating detection can be performed. In the case of microwaves, a combination of these techniques can be performed, for example used in the pulse Doppler radar.
The detector according to the invention is primarily intended for the interior of a vehicle, such as a personal car, van, truck, etc., but could in principle be applied to any type of alarm system where low power consumption is desired.

Intrusion detector with power consumption control and method for intrusion detection


A solvent phase of low solute content is contacted with a solute gas phase for absorption of the solute; effluent gas is condensed in admixture with a portion of the solvent phase which has not been fed to the absorption zone. Overall thermal yield is increased.

This invention concerns an improvement to heat pumps and refrigerators of the absorption type. As known, such systems basically operate by supplying heat to an external fluid A while receiving heat from an external fluid B and exchanging heat with an external fluid C. The two cases are to be distinguished. In the first case (called case 1), the thermal level of fluid B is higher than the thermal level of fluid A and the system receives heat from the fluid C which is at a lower thermal level than the fluids A and B. If fluid C is at a thermal level higher than room temperature, the device operated according to such a cycle is usually referred to as an absorption heat pump. In that case, there is transferred to fluid A a heat amount Q.sub.2 higher than the heat amount Q.sub.1 which is transferred from fluid B, and a heat amount Q.sub.2 -Q.sub.1 is received from fluid C. The fluid C may be at a thermal level lower than room temperature; in that case, the device operates as a refrigerator. In the second case (called case 2), the thermal level of fluid B is lower than the thermal level of fluid A and the system supplies heat to fluid C which is at a lower thermal level than fluids A and B: this is a heat converter such as is disclosed in French Pat. No. 2,321,098 (EN No. 7,525,598). In that case, fluid A receives a heat amount Q.sub.2 lower than the heat amount Q.sub.1 which is released by fluid B, and a heat amount Q.sub.2 -Q.sub.1 is supplied to fluid C.
In the description of the present invention, any device receiving heat only above room temperature and complying with the above general definition, either in case 1 or in case 2, is designated as an absorption heat pump.
In the above general description of the prior art, and in the following disclosure, temperature or thermal level is intended to designate more or less wide temperature ranges which may be also a substantially constant temperature in the case of a change of state of the external fluid with which the heat exchange is effected. A first "thermal level" is considered as higher than a second "thermal level" if the corresponding temperature range is at least partly above the temperature range of the second "thermal level".
In the two cases described above, the cycle comprises at least one absorption step in which a gas phase of a working fluid (the solute) is contacted with a liquid phase (the solvent), and a desorption step which yield a liquid phase of lower solute content and a gas phase of high solute content. Therefore, the solute is a material which may appear either as a gas or in the dissolved state.
The absorption step is usually effected in one contact step; the liquid solvent phase (L) and the gas solute phase (V) are fed to an enclosure and a solution (S) is obtained, while the absorption heat is discharged by indirect contact exchange in the absorber, as disclosed in FIG. 1A.
It is also known to effect the absorption step by counter-current contact of the liquid phase with the vapor phase. This system is disclosed, for example, in the French Pat. No. 2,321,098. In that case, it is possible to operate according to the arrangement shown in FIG. 1B. The counter-current contact is effected in adiabatic conditions, for example in a column, and the discharge of heat to the environment is effected at least partly by condensation, outside the column, of the vapor obtained at the top. In the contact column, the absorption heat results in the vaporization of a fraction of the solvent phase which is less volatile, and there is collected, at the top of the column, a vapor fraction of higher solvent vapor content, which fraction is condensed in exchanger (W) while supplying heat to fluid A.
Adiabatic conditions are conditions in which, as a result of the limitation or even absence of heat exchange with the environment, any released heat is recovered, at least in part, in the fluids discharged from the zone subjected to these conditions.
If the solvent phase fed to the column is in the pure state, it is possible to collect, at the top of the column, a vapor fraction of low solute content and high solvent content, and to thus obtain, at the top of the column, a temperature higher than at the bottom, also higher than the temperature which is attained in one single contact stage.
This arrangement has also some disadvantages. In fact, the condensation range for the top vapor depends on its content of solute; therefore, to avoid that the final condensation temperature be far lower than the initial condensation temperature, it is necessary to allow only a low proportion of solute in the top vapor and therefore the solvent phase must be totally purified in the desorption step.
This problem is made apparent when considering ammonia absorption in aqueous phase in the case where the vapor is discharged in a practically balanced proportion to the solvent phase (L) supplied to the column, which occurs when the vapor feed rate is low as compared to the liquid feed rate. The following results are obtained when varying the composition of the solvent phase (L) at a pressure of 10.2 atm.
TABLE 1 ______________________________________ NH.sub.3 NH.sub.3 Initial Final molar molar conden- conden- fraction fraction Heat of sation sation in the in the conden- temper- temper- Condensa- solvent vapor sation ature ature tion Range phase phase cal/mole .degree.C. .degree.C. .degree.C. ______________________________________ 0.01 0.065 8735 178 162 16 0.04 0.242 8933 169 118 51 0.10 0.512 8740 153 64 89 ______________________________________
It is apparent that the condensation range widens very quickly. To avoid this it is necessary to thoroughly purify the solvent phase in the desorption step and to limit the feed rate of the vapor fraction fed to the column. These requirements limit the yield.

Absorbers used in absorption heat pumps and refrigerators


An image forming apparatus includes an image reading portion, an image processing portion, a storage portion, a storage selector portion, an image forming portion, and a control portion. The storage portion includes a first storage portion and a second storage portion with greater vibration resistance than the first storage portion, and stores image data scanned by the image reading portion and processed by the image processing portion. The storage selector portion selects one of the first storage portion and the second storage portion based on the strength of mechanical vibrations during an operation of the apparatus, and a data size of the image data. The control portion causes the image data to be stored in the storage portion selected by the storage selector portion, and controls the image forming portion to read the stored image data and form an image.

The present disclosure relates to an image forming apparatus such as a photocopier or multi-function peripheral that scans a document image, and forms images based on the scanned image data.
An image forming apparatus such as a photocopier or multi-function device is configured to scan a document image, compress and temporarily store scanned image data in a storage portion, and form an image based on the image data stored in the storage portion.
The storage device that temporarily stores compressed image data may be a hard disk drive (HDD) using a magnetic disk or a solid-state drive (SSD) using semiconductor memory.
However, HDDs, being structured to write data to an internal magnetic device using a head, have low vibration resistance. Consequently, when using an HDD as the storage portion that temporarily stores image data, vibration can cause write errors in the image data, which lowers the data transfer speed. Thus, there is a risk that a required data speed (transfer rate) may not be satisfied due to mechanical vibrations during copy operations (vibrations produced by the revolution of the motor, the feeding of documents or copy sheets, and the like).
In contrast, SSDs are highly vibration resistant as compared to HDDs. Consequently, when using an SSD as the storage portion that temporarily stores image data, vibration does not result in a lowered data transfer rate. However, since SSDs have a higher cost-per-bit of data compared to HDDs, and since there is a limit on the number of available rewrites, SSDs lead to higher apparatus costs and running costs.


A method for detecting faults in a manufacturing line includes processing a plurality of workpieces in a plurality of tools; generating a first error signal associated with the workpieces based on the processing performed in a first tool of the plurality of tools; generating a second error signal associated with the workpieces based on the processing performed in a second tool of the plurality of tools; combining the first and second error signals to generate a composite error signal; and identifying a fault condition with the workpieces based on the composite error signal. A manufacturing system includes a plurality of tools adapted to process workpieces, and a fault monitor. The fault monitor is adapted to receive a first error signal associated with the workpieces based on the processing performed in a first tool of the plurality of tools, receive a second error signal associated with the workpieces based on the processing performed in a second tool of the plurality of tools, combine the first and second error signals to generate a composite error signal, and identify a fault condition with the workpieces based on the composite error signal.

1. Field of the Invention
This invention relates generally to the field of semiconductor device manufacturing and, more particularly, to a method and apparatus for fault detection using multiple tool error signals.
2. Description of the Related Art
There is a constant drive within the semiconductor industry to increase the quality, reliability and throughput of integrated circuit devices, e.g., microprocessors, memory devices, and the like. This drive is fueled by consumer demands for higher quality computers and electronic devices that operate more reliably. These demands have resulted in a continual improvement in the manufacture of semiconductor devices, e.g., transistors, as well as in the manufacture of integrated circuit devices incorporating such transistors. Additionally, reducing the defects in the manufacture of the components of a typical transistor also lowers the overall cost per transistor as well as the cost of integrated circuit devices incorporating such transistors.
Generally, a set of fabrication steps is performed on a lot of wafers using a variety of tools, including photolithography steppers, etch tools, deposition tools, polishing tools, rapid thermal processing tools, implantation tools, etc. The performance of the fabrication steps is also typically measured by metrology tools, such as scanning electron microscopes, optical measurement tools, electrical test tools, etc. The technologies underlying semiconductor fabrication and metrology tools have attracted increased attention over the last several years, resulting in substantial refinements. However, despite the advances made in this area, many of the tools that are currently commercially available suffer certain deficiencies. In particular, such tools often lack advanced process data monitoring capabilities, such as the ability to provide historical parametric data in a user-friendly format, as well as event logging, real-time graphical display of both current processing parameters and the processing parameters of the entire run, and remote, i.e., local site and worldwide, monitoring. These deficiencies can engender nonoptimal control of critical fabrication or metrology parameters, such as throughput, accuracy, stability and repeatability, fabrication temperatures, mechanical tool parameters, wafer state measurements/results, and the like. This variability manifests itself as within-run disparities, run-to-run disparities and tool-to-tool disparities that can propagate into deviations in product quality and performance, whereas an ideal monitoring and diagnostics system for such tools would provide a means of monitoring this variability, as well as providing means for optimizing control of critical parameters.
One technique for improving the operation of semiconductor processing line includes using a factory wide control system to automatically control the operation of the various fabrication and metrology tools. The manufacturing tools communicate with a manufacturing framework or a network of processing modules. Each tool is generally connected to an equipment interface. The equipment interface is connected to a machine interface which facilitates communications between the tool and the manufacturing framework. The machine interface can generally be part of an advanced process control (APC) system. The APC system initiates a control script based upon a manufacturing model, which can be a software program that automatically retrieves the data needed to execute a manufacturing process. Often, semiconductor devices are staged through multiple tools for multiple fabrication processes and associated metrology measurements, generating data relating to the quality of the processed semiconductor devices.
During the fabrication process various events may take place that affect the performance of the devices. That is, variations in the fabrication steps result in device performance variations. Factors, such as feature critical dimensions, doping levels, contact resistance, particle contamination, etc., all may potentially affect the end performance of the device. Various tools in the processing line are controlled in accordance with performance models to reduce fabrication and metrology measurement variation. Commonly controlled tools include photolithography steppers, polishing tools, etching tools, and deposition tools. Pre-processing and/or post-processing metrology data is supplied to process controllers for the tools. Operating recipe parameters, such as processing time, are calculated by the process controllers based on the performance model and the metrology information to attempt to achieve post-processing results as close to a target value as possible. Reducing variation in this manner leads to increased throughput, reduced cost, higher device performance, etc., all of which equate to increased profitability.
Statistical process control techniques are commonly used to monitor the operation of manufacturing processes, systems, or individual tools. Commonly, various measurements related to the process being monitored are compiled and plotted on a control chart. The control chart has control limits, which, if violated, immediately indicate an error condition requiring investigation. Certain error conditions result from special causes, such as a defective tool, operator error, material defect, process changes, trends, etc., that may be corrected by process optimization or redesign.
In some instances error conditions are present, yet go undetected. The error signal may not be significantly strong to rise above the threshold set for detection. An error signal may also be masked by measurement detection limitations and noise. Undetected faults can lead to misprocessed wafers, which require rework or may even need to be scrapped. Misprocessed wafers are costly and reduce the efficiency of the processing line.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
One aspect of the present invention is seen in a method for detecting faults in a manufacturing line. The method includes processing a plurality of workpieces in a plurality of tools; generating a first error signal associated with the workpieces based on the processing performed in a first tool of the plurality of tools; generating a second error signal associated with the workpieces based on the processing performed in a second tool of the plurality of tools; combining the first and second error signals to generate a composite error signal; and identifying a fault condition with the workpieces based on the composite error signal.
Another aspect of the present invention is seen in a manufacturing system including a plurality of tools adapted to process workpieces, and a fault monitor. The fault monitor is adapted to receive a first error signal associated with the workpieces based on the processing performed in a first tool of the plurality of tools, receive a second error signal associated with the workpieces based on the processing performed in a second tool of the plurality of tools, combine the first and second error signals to generate a composite error signal, and identify a fault condition with the workpieces based on the composite error signal.

Method and apparatus for fault detection using multiple tool error signals


A method of audio-visual communication using a television and a television using the same are provided, wherein the broadband network and television technologies are used to achieve services of audio-visual communication over a network, such that a user uses the television to conduct audio-visual communications.

1. Field of Invention
The present invention relates to a television, and more particularly, to a television integrated with a network.
2. Related Art
The number of users of audio-visual communication services over a network is growing rapidly with the maturity of the broadband network environment, due to the high quality of the audio-visual communication of the Voice over Internet Protocol (VoIP) and the network visual specifications (H.323), and the development of specifically designed communication software for these applications.
However, currently, many video content and services are conducted over Internet, thus, the user has to use personal computers (PCs) or specialized network phones and specialized network video phones to enjoy the convenience of these services. Though many users spend more time on computers than on televisions, and they soon get used to take the computer as a tool for instant visual or voice communication, as for users who are not accustomed to or unfamiliar with computer operations, these services cannot be prevailing.
The recent phone surveys conducted by two American market research companies: Points North Group and Horowitz Associates shows, 25% of the Internet users prefer to watch downloaded TV programs and movies on the computer, while 38% of the users prefer to enjoy this kind of videos on televisions. As for users with the age of 18-34, 68% of them are more interested in televisions, while 45% of them prefer to enjoy videos on computers. These data show that, though the computer has multiple functions and better interactivity, most users still prefer to use televisions, for example, to watch TV programs or films, to ease their busy activities on computers and to relax themselves.
As can known from the above that, the television is a non-resistable medium for most consumers, and its popularity and convenience are far beyond the computer. Therefore, if the network visual or voice communication service can become available through simple operations on the televisions, the popularity of such service will be enhanced, thereby providing better opportunity to both networks and televisions.

Method of audio-visual communication using a television and television using the same


In accordance with a preferred embodiment of the invention, a solenoid operated unit fuel injector, for internal combustion engines of the type which are capable of having distinct timing, metering and injection periods, and in which the same supply line serves for the delivery of fuel to both a timing chamber and a metering chamber, is improved by providing a drilling in the injector barrel which leads directly from the timing fluid flow portion of the fuel supply circuit to an injector fuel drain path, and mounting a C-shaped spring valve on the injector body for controlling dumping of fuel through the drilling at a location above that of the timing and metering spill ports.

1. Field of the Invention
The present invention relates to solenoid operated unit fuel injectors for internal combustion engines. In particular, to such fuel injectors which are capable of having distinct timing, metering and injection periods, and in which the same supply line serves for the delivery of fuel to both a timing chamber and a metering chamber.
2. Description of Related Art
Solenoid operated fuel injectors, of the type to which the present invention is directed, have been used for some time, and an example of such an injector can be found in commonly-owned U.S. Pat. No. 4,531,672 to Smith. In this type of injection, a timing chamber is defined between a pair of plungers that are reciprocably displaceable within the bore of the body of the injector and a metering chamber is formed in the bore below the lower of the two plungers. A supply rail in the engine delivers a low pressure supply of fuel to the injector body. To control this supply of fuel, a solenoid valve is disposed in the flow path between the fuel supply rail and the injector bore and the plungers block and unblock respective ports leading from injector body fuel supply circuit into the timing and metering chambers.
During the operation of such an injector, the port to the timing chamber is opened during retraction of the plungers to allow fuel to enter the timing chamber. During the injector downstroke, the timing port is closed by the upper plunger, and then, the metering port is opened to direct the supply of fuel into the metering chamber. During the entire time, from the start of the timing period through the end of the metering period, the solenoid valve remains open. As a result, during the portion of the downstroke before the timing port is closed, the downward plunger movement produces a high pressure backflow of fuel from the timing chamber, through the solenoid valve to the supply rail. Not only can this high pressure backflow damage O-ring seals within the injector, but it creates pulsations in the fuel supply rail that can result in a phenomenon known as "crosstalk", whereby the pressure wave produced by the backflowing injector causes "bumping" of an inlet check ball valve of other injectors of the engine so as to exert an influence on the quantity of fuel metered in the other injectors.
In an existing injector design, sold by the Cummins Engine Co. under the CELECT trademark, shown in FIGS. 1-3 & 3a, improved performance is achieved, and the timing fluid backflow-related problems ameliorated. In this existing fuel injector 1, as shown in FIG. 1, initially, during the retraction stroke, with the solenoid valve 3 closed, the metering plunger 5 and the timing plunger 7 rise together, and fuel under rail pressure is metered into the metering chamber 9. When the proper quantity of fuel has been metered, the solenoid valve 3 is opened, allowing fuel to flow into the timing chamber 11, causing the pressure at the top and bottom of the metering plunger to be equalized, thereby stopping movement of the metering plunger 5 while the timing plunger 7 continues to rise, and the timing chamber 11 to fill, as the retraction stroke is completed. During the downstroke, prior to the time at which injection is to commence, as shown in FIG. 3, the solenoid valve 3 remains open and fuel is forced back out of the timing chamber 11, through the solenoid valve 3 into the supply circuit.
However, unlike the situation in the injector of the Smith patent, a relief valve assembly 15 is provided to vent high pressure spikes from the rail side of the injector 1 to the drain side thereof (FIG. 3A). More specifically, the relief valve assembly 15 comprises a valve member 15a which is urged against a relief port 15b by a coil spring 15c which is disposed in spacer member 17, the upper surface of which forms the bottom wall of the metering chamber 9 and which contains channels through which fuel flows between the fuel inlet port 19 and the metering chamber 9 and from the relief valve 15 to a drain passage 21. When the pressure of the backflowing timing fluid exceeds that of spring 15c, the valve member 15a unblocks relief port 15b, thereby opening a path from the fuel supply circuit to drain passage 21.
Similarly, at the end of the injection phase, when the solenoid 3 is closed, the top edge of the metering plunger 5 passes below at least one timing fluid spill port 23, thereby evacuating the timing chamber 11 via the drain passage 21. Additionally, passages 5a in the metering plunger 5 are brought into communication with at least one spill port 25 by which a small quantity of fuel is spilled to the fuel supply circuit. To prevent pressure spikes due to the fuel spilling from the metering chamber 5, valve member 15a, again, is forced open to vent the excess fuel pressure from the supply side thereof to the drain passage 21.
On the other hand, while a definite improvement over other prior art injectors, it has been found that the valve assembly 15 does not fully resolve the problems associated with pressure build-ups in the fuel supply circuit, and shot-to-shot fuel volumes can vary by as much as a third during engine idling conditions, thereby adversely impacting on idling emissions from the engine with which the fuel injector is used. These inconsistencies appear to be due to the length and tortuous nature of the path of the supply side fuel routing to the valve assembly, which affects the time it takes for the pressure wave to reach valve member 15a and the pressure of the fuel when it does reach valve member 15a. However, the space requirements for such a spring-loaded valve assembly 15 and the limited space available for it to be incorporated into the injector, prevent the problems associated with the use of valve assembly 15 from being fully addressed by merely shifting its position to shorten and simplify the flow routing to it. Furthermore, the use of valve assembly 15 is associated with the costs of the high degree of precision machining required to produce it and the flow paths to and from it, as well as that attributable to production and assembly of the three parts thereof (i.e., valve member 15a, valve spring 15c and the threaded plug 15d used to hold them in place).
One-way, spring valves, which permit a fluid to flow therethrough in only a given direction and as a function of the extent to which the pressure of the fluid acting in prescribed flow direction exceeds the force of the spring in a valve closing direction, have also been known for a long time. Such valves in which a band-shape spring serves as the valve spring have been used in numerous types of equipment, from air compressors (U.S. Pat. No. 233,432) to controls for load-moving mechanisms (U.S. Pat. No. 4,095,617). In various different types of fuel injectors such spring valves have been used to control the supply of fuel to a fuel injector nozzle (U.S. Pat. Nos. 2,590,575 and 5,014,918) as well as the releasing of timing fluid from a timing chamber (commonly assigned, co-pending U.S. Pat. application Ser. No. 07/898,818 to Kolarik et. al.). However, because of the construction of the noted CELECT injectors, such a band spring valve cannot merely be substituted for its relief valve assembly 15; furthermore, more than mere adaption of the barrel member for the use of such a valve would be required to overcome the noted shortcomings of the valve assembly 15.
Thus, there still is a need for further improvements to fuel injectors of the type to which this invention is directed, both from the standpoint of reducing supply side pressure effects, and from the standpoint of simplifying the construction and costs of producing such fuel injectors.

Solenoid operated unit fuel injector with supply line backflow pressure relief valve


A transducer assembly including a pair of transducers positioned directly opposite each other on the two faces of a flexible magnetic disk and a pair of gimbal springs each for supporting one of the transducers. The gimbal springs are so adjustably bent that the transducers bear with substantially equal, opposite and uniform pressures on the opposite sides of the disk. A method is disclosed for measuring the forces exerted by the transducers acted on by the gimbal springs including the positioning of three balls on the active face of each of the transducers with strain gauges measuring the forces on each of the balls. A first one of the balls is located on the transverse center line of the active face of the transducer while the other balls are equally spaced from this center line; and all of the balls are equally spaced from a longitudinal center line of the face. The gimbal spring for the transducer is then adjustably bent until the force from the transducer on the first ball is twice that of the forces provided by the transducer on the second and third balls so that the transducer will bear with uniform pressures on the disk.

The invention relates to assemblies of magnetic transducers particularly for use with flexible magnetic disks that undulate from their principal plane during their rotation.
It has been previously proposed in Castrodale et al. U.S. Pat. No. 4,089,029, issued May 9, 1978, to provide a transducer assembly of this type having a pair of transducers held against the opposite faces of a flexible magnetic disk with a pair of gimbal springs. In the ordinary manufacture of the transducer assembly, it was found that the gimbal springs in particular caused the transducers to bear against the disk and against themselves through the intermediary of the disk with non-uniform forces. These non-uniform forces were due to the many various manufacturing steps including heat welding, pressure bonding, chemical etching, and varied handling of the parts during formation and assembling; and any accompanying malformation of the parts of the assembly were not visually apparent. These non-uniform forces resulted in vibration of the transducers, movements of the transducers from their intended magnetic tracks on the disk and other misfunctions so that data transfer was unreliable particularly for very high speeds of rotation of the disk and for very high track densities.

Uniformly loaded opposite magnetic transducer assembly

International Business Machines Corporation


A blower provided, for example, at the bottom of a predetermined concavity in an electronic keyboard instrument supplies an air blast to a light ball to blow same up, using a fan rotated by a motor. In this case, a motor controller controls the rotational speed of the motor on the basis of the amplitude of a tone signal output from an amplifier. As a result, the ball moves up and down in accordance with the amplitude of the tone signal. The motor controller may control the rotational speed of the motor on the basis of a pitch for controlling the generation of a tone signal, velocity, timbre, automatic performance tempo, rhythm pattern or a change in the pitch or a combination of some or all of them, and not on the basis of the amplitude of the generated tone signal by itself.

1. Field of the Invention
The present invention relates to apparatus and process which visually represent a piece of music to be performed.
2. Description of the Related Art
It is said that performance of an musical instrument should preferably be learned since infancy. Unless the infant itself takes interest in the instrument, exercise would not continue so long whenever it exercises and it would soon feel bored, so that however much its parent may try to persuade it to do the effect of its learning does not improve. Therefore a scheme should be devised for causing the infant to feel it delightful to play a musical instrument.
There are conventionally devices in which when learner performs a melody on an electronic musical instrument, LEDs are lighted or voice such as "do", "re", "mi", "fa", etc., are produced in correspondence to the depressed keys. Those devices are suitable for telling the learner a key to be depressed or for the performer to memorize the note name of the depressed key. However, they are not necessarily delightful for infants.
Although, conventionally, music is, of course, one which human being enjoys acoustically, it could widely be used in the form of an interior device if the music is visually enjoyed as well.

Music representing apparatus for floating an object on the basis of a performance of music


A business method for promoting goods and services of providers includes the steps of designating a group of targeted recipients, and storing demographics information of each recipient in an electronic database. A plurality of direct mail items including provider promotions is generated, and each marked with a machine-readable ID code unique to each of the recipients. The direct mail items are sorted by their respective ID codes into cooperative mail packages, each mail package containing multiple items with common ID codes. The mail packages are then forwarded to respective recipients. After redemption of a direct mail item by a recipient, the ID code is read and electronically linked with the recipient's demographics information contained in the electronic database. A report is generated based on the direct mail items redeemed.

This invention relates to a business method for promoting goods and services of providers, such as business owners, through the distribution and tracking of direct mail promotional items. The invention utilizes machine-readable codes applied to the items. When the items are redeemed and the codes scanned, useful information concerning the recipient of the item is acquired and reported. The invention reveals trends relevant to particular customer groups, markets and industries, provides valuable demographics information to business owners, and generates customer and prospects lists for future mailings.
Unlike other direct mail promotions, the present invention designates a targeted group of recipients and preselects multiple items highly relevant to the group for mailing in a bundled cooperative mail package. For example, if the targeted group is first-time parents, each package may include paper coupons for a baby furniture store, diapers and wipes, daycare and pediatrician services, baby formula, and the like. Some recipients in the group may receive more or less items, or even different but related items based on demographics and other valuable information obtained in previous mailings to similarly situated recipients. Similarly, the invention may also generate secondary mailings to recipients based on past item redemptions. For example, if a recipient in a direct mailing which targets new residents redeems an item at a furniture store to purchase a baby's crib, the secondary mailing to that recipient may include direct mail items relating to baby formula, diapers, and the like.
Prior art U.S. Pat. No. 4,752,675 to Zetmeir describes a comparable method for determining the effectiveness of a mass mailing. In Zetmeir, random direct mail items are mailed individually to a class of recipients. The mass mailing is not targeted based on the nature of the goods and services advertized, nor does the mailing include multiple items in a single cooperative mail package.

Business method for promoting goods and services of providers


Tablets containing 1-2% by weight carboxymethylguar as a disintegrant are equivalent to tablets containing sodium carboxymethylcellulose in medicant release. These tablets can be made at a lower cost while still meeting Pharmacopeia standards.

Guar is a leguminous plant from which a guar gum is extracted. Chemically, guar gum is a galactomannan which is a polysaccharide polymer with a galactose on every other unit of a mannose repeating backbone. Purified and chemically modified guars have gained utility as thickening agents and food additives.
E. Nuernberg et al., "Carboxymethylated Galactomannan Products as Pharmaceutical Adjuvants", Acta Pharmaceutica Technologia, 30(1), pp. 50-55, 1984, discloses that carboxymethylated guar absorbs more water than natural guar when the two materials are held at the same relative humidity. U.S. Pat. No. 4,109,018 discloses that guar gum can be used to produce a low calorie diet bread. European patent application EPO 0 281 360 discloses hydrophobically modified non-ionic polygalactomannan ethers which are useful as thickening agents for aqueous systems.
It is known in the art to use an acid crosslinked carboxymethylcellulose identified as croscarmellose sodium, type A, NF or crosslinked polyvinyl pyrrolidone or sodium starch glyconate in the manufacture of disintegrating tablets. Yet in spite of an ongoing need for an alternative to the predominate use of crosslinked carboxymethylcellulose for this application, There was no suggestion in the art that a new and cost effective substance could be substituted for the long established crosslinked carboxymethylcellulose.

Crosslinked carboxymethyguar tablet disintegrant


A powered access platform unit having a wheeled base carrying a corner pillar to which is articulated one end of a parallel linkage boom articulated at the other end to the remote corner of a platform structure on the same side of said structure as the side of the base which carries the corner pillar, and a drive unit on the base for raising and lowering the platform structure on the parallel linkage boom by means of an hydraulic ram articulated between the base pillar and the boom.

A powered access platform unit comprises a base, an elevating structure, a platform mounted on the elevating structure, and a power unit for raising or lowering the platform via the elevating structure.
It is a general object of this invention to provide a powered access platform unit which, in a preferred version, is especially suitable for domestic use, although not limited to this application. For domestic use, e.g. to enable the user to have easy access to the upper parts of a house for the purpose of roof repairs, painting or the like, it is important for the platform unit to be easy and safe to use, to collapse to a relatively small size to enable it to pass through house gateways and doorways, to be easily manoeuvrable and, in the collapsed condition, to locate the platform close to ground level to facilitate easy entry. Generally, however, it is not to be expected that the platform will have to raise very substantial loads to substantial heights, as is the case with many powered access platforms intended for industrial use. At the same time, it will be understood that, whilst retaining the advantages of ease of use, maneuverability and platform entry, it is readily possible to manufacture the unit of this invention to a size and scale which makes it suitable for industrial use.


The invention is an improvement in an AC adjustable frequency load-moving system of the type having a control circuit providing a motor speed signal and using command ramps to control each of plural AC squirrel cage motors. The invention helps assure substantially equal load sharing by the motors. The improvement includes a dwell circuit which maintains the motor speed reference signal at a synchronizing value at least for a period of time denominated as the dwell time. This permits microprocessors--which may be running asynchronously--to both "read" the same value of motor speed signal even though such value may be read at slightly different instants. Separate inverter units monitor such signal and responsively generate synchronized command ramps to effect load sharing. The invention is suitable for use with a wide variety of plural-motor drive systems and has been found to be particularly suitable for use on crane hoist systems.

Certain "load-moving" drive systems involve two or more electric motors for moving a single load. In some systems, the motors exert forces on the load by some sort of "resilient" connections, e.g., elastic belts or slip clutches. In such a configuration, each motor (and the power transmission and control equipment connected thereto) is somewhat insulated from mechanical shock resulting from a failure of the motors to share load equally.
On the other hand, some types of systems couple plural motors to a load using "rigid" connections such as gear boxes, line shafts or the like. In those instances, failure of motors to substantially equally share the load can result in undue stress to all of the mechanical components in the drive train (including the motors themselves) and to the electrical control system. Premature wear and breakage is often the result.
An example of an application involving plural drive motors for moving a single load is a crane. Cranes are made in a wide variety of configurations. One type is called an overhead travelling crane (OTC) and is used in factories or the like for lifting and placing loads on the factory floor. Such a crane travels on a pair of elevated main rails which are parallel and spaced apart, usually by several yards. A pair of bridge girders spans across the rails and there are driven wheels mounted at either end of the girders for riding atop the rails. And the girders themselves have rails on them.
A "trolley" is mounted on the girder rails and can travel the width of the bridge under motive power. A load hoist is mounted on the trolley and includes a powered hoist/lower "rope drum" about which steel cable is wrapped. The cable is connected to a load-lifting hook, sling, magnet or the like. With the foregoing arrangement, the operator (who usually rides in a cab attached to the crane) can pick up, move and deposit a load anywhere in the area travelled by the crane.
Another type of crane is called a straddle crane and many of its operating principles are similar to those of an OTC. A difference is that the main rails are about at ground level and the trolley is supported at an elevation by legs extending down from the bridge girders to the main rails. A straddle crane resembles an inverted letter "U" in shape. An advantage of such an arrangement is that the main rails need not be mounted at an elevated level. Another is that the crane can position itself over (or "straddle") a truck, for example, and unload the truck's cargo. Sometimes the crane is an L-shaped "hybrid" with one end supported on an elevated rail and the other on a rail at ground level.
In load-moving systems of the foregoing types (including load hoisting/lowering cranes), controllability of load "picking" and placement is important. That is, the system operator must have the ability to gently initiate load movement and later place the load accurately and gently. Nowhere is this more true than in crane material handling work where the load to be lifted and placed can be an expensive machined product worth thousands of dollars. Such cranes are sometimes designed to lift tons, even hundreds of tons, of load. And, often, crane operations are attended by workers at ground level who assist in load attachment, placement and detachment. Such workers are understandably intolerant of a hoist/lower system which is difficult to control accurately. In plural-motor systems, good control and maximum load lifting capability depend in part upon equalized motor load sharing.
In former years, cranes of the foregoing type were often powered by direct current (DC) electric motors. More recently, alternating current (AC) drive systems have come into wide usage due in significant part to the fact that they can derive power from the existing AC power distribution networks.
A type of variable speed AC drive system used on cranes includes squirrel cage AC motors (generally acknowledged to be the most straightforward of all AC motor types) and controllers for providing variable motor speed ranging from "creep" to rated speed. While such drives are often known as adjustable frequency drives, in fact the power applied by the control system to the AC motor(s) is adjustable both in frequency and in voltage. The frequency of the applied voltage (which ranges generally from zero to 60 Hz for a 60 Hz network as in the United States) controls motor speed while the magnitude of the applied voltage controls motor current and therefore motor output torque. A known way of coordinating frequency and voltage is generally to cause a predetermined change in voltage with each, say, one Hz change in frequency. At very low frequencies, the voltage is elevated slightly to compensate for motor current/resistive losses, often called "IR losses." Some years ago, the term "Hertz," abbreviated "Hz," replaced the phrase "cycles per second" and is synonymous therewith.
A known AC adjustable frequency drive system, useful on cranes, includes a controller for two motors mechanically coupled to the same hoist drum by gearboxes. Such controller has a pair of general purpose, microprocessor-based adjustable frequency inverters (sometimes called scalar inverters), one for each motor. Each inverter derives input power from the AC network at, e.g., 460 volts, 3 phase, 60 Hz. Output power from the inverter to the connected motor is adjustable in frequency and voltage as described above.
A single master switch "tells" the system what motor speed is desired by the operator controlling such switch. It does so by providing a variable AC reference voltage nominally in the range of 0-16v. The master switch handle is movable in an arc either side of a center "neutral" position and the degree of handle displacement from the neutral position determines the magnitude of such voltage.
This voltage is directed to an interface card which rectifies it and responsively provides a DC motor speed signal nominally in the range of 0-10v. As the microprocessors of each inverter scan their programmed instructions, they periodically "read" this motor speed signal and responsively cause the inverters to apply electrical power to the motors at a frequency (and voltage) which correlates therewith. So-called "command ramps" are used to control the inverters in that way.
A command ramp is provided by the microprocessors according to aspects of the programming embedded therein. Such ramp, in the nature of an electrical signal, derives its name from the fact that it causes applied motor voltage to change somewhat gradually rather than instantaneously. One occasion in which such ramps affect system operation is when the operator rapidly throws the master switch handle "hard over" from neutral to an extreme position. Even though such position signifies full motor speed, the system prevents instantaneous application of full voltage. Rather, the applied motor voltage is "ramped up" to the value represented by the final master switch position. Such a system is sometimes said to provide "soft" acceleration and abuse to the electrical and mechanical components is thereby substantially reduced. A motor control system of the foregoing type is made by Harnischfeger Corporation of Milwaukee, Wisconsin, and sold under its SMARTORQUE.RTM. trademark.
With the foregoing arrangement, it is anticipated that the same voltage at the same frequency would be applied to both motors. The output torque of each motor is a function of motor electrical current, in turn a function of applied frequency and voltage. Therefore, electrical current is an indication of the degree to which the motors would share load. With equal motor currents, load sharing would be substantially equal.
Notwithstanding that both inverters are detecting the same motor speed signal, it has been observed that motor currents were not always equal to one another and the proportions of the total load being handled by each motor were sometimes disparate and varied randomly by as much as 1.5:1 or more. As a result, the crane is not able to easily lift rated load, one motor is somewhat "dragged along" by the other and both the electrical and mechanical systems were abused.
One solution to such a problem is to use special purpose inverters, the cost of which is significantly greater than that of a general purpose inverter. Another solution is to provide a feedback circuit whereby motor currents (or speeds or other parameters) are "fed back" for comparison with, say, the DC motor speed signal. Since such speed signal represents the desired motor operating condition, comparing it with a signal representing an actual motor operating condition yields (or may yield) an "error" signal. A feedback system is arranged to automatically change the actual operating condition until it satisfactorily matches that desired.
Such feedback systems are significantly more complex than similar non-feedback systems. As such, they are more expensive in the first instance, are more difficult to troubleshoot and somewhat more prone to failure.
A system which is inexpensive, easy to install or retrofit to existing controllers, uses general purpose inverters and is highly effective in causing load sharing in AC adjustable frequency drives would be an important advance in the art.

System with delay timer for motor load equalization