A method of preparing and testing an array of ceramics for optical properties, comprising: providing a host material that is capable of being made optically transparent or translucent upon sintering; forming the host material into an array of pixels attached to a base plate; doping the host material; reacting the host material and the dopant, to form an array of products; and testing the products for optical properties.

1. Field of the Invention
This invention relates to a method for screening transparent materials, and more particularly to a combinatorial method for screening an array of transparent materials.
2. Description of Related Art
Combinatorial chemistry techniques have been developed by the pharmacutical industry for the rapid development and screening of drug chemistries. For example, Pirrung et al. developed a technique for generating arrays of peptides and other molecules using, for example, light-directed, spatially-addressable synthesis techniques (U.S. Pat. No. 5,143,854). In addition, Fodor et al. have developed automated techniques for performing light-directed, spatially-addressable synthesis techniques, photosensitive protecting groups, masking techniques and methods for gathering fluorescence intensity data (Fodor et al., PCT Publication No. WO 92/10092).
Using these various methods of combinatorial synthesis, arrays containing thousands or millions of different organic elements can be formed (U.S. Pat. No. 5,424,186). The solid phase synthesis techniques currently being used to prepare such libraries involve a stepwise process (i.e., sequential, coupling of building blocks to form the compounds of interest). In the Pirrung et al. method, for example, polypeptide arrays are synthesized on a base material by attaching photoremovable groups to the surface of the base material, exposing selected regions of the base material to light to activate those regions, attaching an amino acid monomer with a photoremovable group to the activated region, and repeating the steps of activation and attachment until polypeptides of the desired length and sequences are synthesized. The Pirrung et al. method is a sequential, step-wise process utilizing attachment, masking, deprotecting, attachment, etc. Such techniques have been used to generate libraries of biological polymers and small organic molecules to screen for their ability to specifically bind and block biological receptors (i.e., protein, DNA, etc.). These solid phase synthesis techniques, which involve the sequential addition of building blocks (i.e., monomers, amino acids) to form the compounds of interest, cannot readily be used to prepare many inorganic and organic compounds. As a result of their relationship to semiconductor fabrication techniques, these methods have come to be referred to as xe2x80x9cVery Large Scale Immobilized Polymer Synthesis,xe2x80x9d or xe2x80x9cVLSIPSxe2x80x9d technology. Robotics are used to mix and process hundreds or thousands of samples simultaneously, allowing for parallel testing of material mixtures for efficacy.
More recently combinatorial techniques have been applied to inorganic materials in the form of thin films deposited or evaporated onto a substrate. For example, Schultz et al. applied combinatorial chemistry techniques to the field of material science in U.S. Pat. No. 5,985,356. More particularly, Schultz et al. disclosed methods and apparatus for the preparation and use of a substrate having thereon an array of diverse materials in predefined regions. An appropriate array of materials is generally prepared by delivering components of materials to predefined regions on the substrate and simultaneously reacting the reactants to form different materials. While these films have known composition, the particle size and porosity of the material make it highly scattering and non-transparent.
A luminescent material absorbs energy in one portion of the electromagnetic spectrum and emits energy in another portion of the electromagnetic spectrum. A luminescent material in powder form, where the material is excited by UV light to generate photons is commonly called a phosphor, while a luminescent material in the form of a transparent solid body that is excited by gamma or X-rays to generate visible photons is commonly called a scintillator.
Most useful phosphors emit radiation in the visible portion of the spectrum in response to the absorption of the radiation which is outside the visible portion of the spectrum. Thus, the phosphor performs the function of converting electromagnetic radiation to which the human eye is not sensitive into electromagnetic radiation to which the human eye is sensitive. Most phosphors are responsive to more energetic portions of the electromagnetic spectrum than the visible portion of the spectrum. Thus, there are powder phosphors which are responsive to ultraviolet light (as in fluorescent lamps), electrons (as in cathode ray tubes) and x-rays (as in radiography).
There are a number of known scintillators each of which has its own set of properties such as the turn-on delay, efficiency, primary decay time, afterglow, hysteresis, luminescent spectrum, radiation damage and so forth. The turn-on delay of a luminescent material is the time period between the initial impingement of stimulating radiation on the luminescent material and the luminescent output reaching its maximum value, for a constant intensity of stimulating radiation. The efficiency of a luminescent material is the percentage of the energy of the absorbed stimulating radiation which is emitted as luminescent light. When the stimulating radiation is terminated, the luminescent output from a scintillator decreases in two stages. The first of these stages is a rapid decay from the full luminescent output to a low, but normally non-zero, value at which the slope of the decay changes to a substantially slower decay rate. This low intensity, normally long decay time luminescence, is known as afterglow and usually occurs with intensity values less than 2% of the full intensity value. The initial, rapid decay is known as the primary decay or primary speed and is measured from the time at which the stimulating radiation ceases to the time at which the luminescent output falls to 1/e of its full intensity value.
A luminescent material exhibits hysteresis if the amount of luminescent light output for a given amount of incident stimulating radiation depends upon the amount of stimulating radiation which has been recently absorbed by the luminescent material. The luminescent spectrum of a luminescent material is the spectral characteristics of the luminescent light which is emitted by that material.
Radiation damage is the characteristic of a luminescent material in which the quantity of light emitted by the luminescent material in response to a given intensity of stimulating radiation changes after the material has been exposed to a high radiation dose. Radiation damage may be measured by first stimulating a luminescent material with a known, standard or reference, intensity of radiation. The initial output (Io) of the photodetector in response to this reference intensity of incident stimulating radiation is measured and recorded or stored. Next, the luminescent material is exposed to a high dosage of radiation. Finally, the luminescent material is immediately again exposed to the reference intensity of stimulating radiation and the final output (If) of its photodetector, in response to this reference intensity of stimulating radiation, is measured and stored or recorded. The radiation damage (RD) may then be expressed as:   RD  =                    I        f            -              I        o                    I      o
Ideally, the radiation damage should be as small as possible. In most luminescent materials, it is a negative number because it is normally less than Io.
In a computed tomography (CT) scanning system, an x-ray source and an x-ray detector array are positioned on opposite sides of the subject and rotated around the subject in fixed relation to each other. CT scanners with solid scintillators are known in the art. In a solid scintillator system, the scintillator material of a cell or element absorbs x-rays incident on that cell and emits light which is collected by a photodetector for that cell. During data collection, each cell or element of the detector array provides an output signal representative of the present light intensity in that cell of the array. These output signals are processed to create an image of the subject in a manner which is well known in the CT scanner art. It is desirable for the luminescent material in a CT scanner to have a linear characteristic in which the light output is a linear function of the amount of stimulating radiation which is absorbed in order that light output may be directly converted to a corresponding intensity of stimulating radiation in a linear manner.
In systems such as CT scanners, the luminescent material has many specialized characteristics which are not needed in many of the previously mentioned phosphor based systems. First, in x-ray based CT systems, it is desirable to absorb substantially all of the incident x-rays in the luminescent material in order to minimize the x-ray dose to which the patient must be exposed in order to obtain the computed tomography image. In order to collect substantially all of the incident x-rays, the luminescent material must have a thickness in the direction of x-ray travel which is sufficient to stop substantially all of the x-rays. This thickness depends both on the energy of the x-rays and on the x-ray stopping power of the luminescent material. Second, it is important that substantially all of the luminescent light be collected by the photosensitive detector in order to maximize overall system efficiency, the signal-to-noise ratio and the accuracy with which the quantity of incident stimulating radiation may be measured. In order to extract substantially all of the luminescent light generated in the luminescent material of the CT scanner, the luminescent material should be. transparent to the luminescent light. Otherwise much of the luminescent light will not reach the photosensitive detector because of scattering and absorption within the luminescent material. Consequently, the luminescent material is provided in the form of a solid bar which is substantially transparent to the luminescent light and which is thick enough in the direction of x-ray travel to absorb substantially all of the incident x-rays. This complicates both the selection of a luminescent material for use in CT scanning and its preparation since many materials which are known to luminesce and which have been used or tested as powder phosphors cannot be provided in the form of a solid bar having the necessary transparency.
The luminescent properties of materials have not been tabulated in handbooks in the manner in which the melting point, boiling point, density and other more mundane physical characteristics of various compounds have been tabulated. Most luminescent data is found in articles with respect to particular materials which the authors have measured for one reason or another. Further, most characterization of luminescent materials has been done using ultraviolet (UV) light as the stimulating radiation because ultraviolet light is more easily produced than x-rays and is generally considered less harmful. Unfortunately, there are a number of materials which are luminescent in response to ultraviolet light stimulation which are not luminescent in response to x-ray stimulation. Consequently, for many materials, even that luminescent data which is available provides no assurance that the material will luminesce in response to x-ray stimulation. Further, for many applications of phosphors many of the parameters which must be closely controlled in a scintillator for use in a state-of-the-art CT scanning system are unimportant and thus have not been measured or reported. Consequently, existing luminescent material data provides little, if any, guidance in the search for a scintillator material appropriate for use in a state-of-the-art CT scanning system. Among the parameters on which data is generally unavailable are radiation damage in response to x-ray stimulation, afterglow, susceptibility to production in single crystalline form, hysteresis phenomena, mechanical quality and in many cases, even whether they are x-ray luminescent. The large number of parameters which must meet strict specifications in order for a given material to be suitable for use in a state-of-the-art CT scanner, including the ability to provide the material in the form of transparent scintillator bodies, makes the process of identifying a suitable scintillator material one which essentially begins from scratch and is akin to searching for xe2x80x9ca needle in a haystackxe2x80x9d.
There are several reasons that it is desirable that the radiation damage be as small as possible. One disadvantage of high radiation damage is that as radiation damage accumulates, the sensitivity of the system decreases because of the progressively smaller quantity of light which is emitted by the scintillator material for a given stimulating dosage of radiation. Another disadvantage is that for too high a radiation damage, the scintillation detectors must eventually be replaced because of the cumulative effects of the radiation damage. This results in a substantial capital cost for the replacement of the scintillation detecting system. A more bothersome, and potentially even more expensive effect of high radiation damage is a need to recalibrate the system frequently during the working day, and potentially as frequently as after every patient. Such recalibration takes time and also exposes the scintillator material to additional radiation which contributes further damage. It is considered desirable that the radiation damage of a scintillator material for use in a CT scanning system be small enough that calibration of the system at the beginning of each working day is sufficient to ensure accurate results throughout the working day.
One way of providing the luminescent material in the form of a transparent bar is to employ a single crystalline luminescent material which is transparent to its own luminescent radiation. A common method of growing single crystals is the Czochralski growth technique in which appropriate source materials are placed in a high temperature crucible which is often made of iridium (Ir) and the crucible and its contents are heated to above the melting point of the desired single crystalline material. The resulting molten material is known as the melt. During growth, the melt temperature is held at a value at which the upper portion of the melt is cool enough for single crystalline material to grow on a seed crystal brought into contact with the melt, but not to spontaneously nucleate. A seed crystal of the desired material or one on which the desired material will grow as a single crystal is lowered into contact with the top of the melt. As the desired crystalline material grows on the seed crystal, the seed crystal is withdrawn (pulled upward) at a rate which maintains the growing boule of single crystalline material at a desired diameter. Typically, the seed crystal is rotated during growth to enhance the uniformity of the growing crystal. The source material which is initially placed in the crucible may take any appropriate form, but is normally a mixture of appropriate quantities of source materials which together provide a melt having the stoichiometry and impurity control desired for the single crystalline material to be grown.
When a pure crystal is grown from a corresponding melt, the Czochralski growth technique normally provides a high quality, uniform composition single crystal of the desired composition. When it is desired to produce a crystal having substitutions for some portion of the atoms of the pure crystalline material, the growth dynamics are more complex and the manner in which the substituent enters into the crystal structure and thus its concentration in the melt and boule as functions of time depend on a number of characteristics. One of the effects of these characteristics is characterized as the segregation coefficient. The segregation coefficient has a value of 1 when the substituent is normally present in the solid boule in the same ratio as it is present in the source melt. The segregation coefficient is greater than 1 when the substituent is normally present in the solid boule in greater concentration than it is present in the source melt and the segregation coefficient is less than 1 when the substituent is normally present in the solid boule in lesser concentrations than it is present in the melt. While there are a number of different fundamental reasons for these differences, the segregation coefficient is an effective means of expressing the result.
In a CT scanning system, one of the important characteristics of a scintillator bar is its Z-axis response curves. Individual scintillator bars are normally narrow for maximum resolution and deeper than wide to provide adequate x-ray stopping power and relatively long perpendicular to the plane of the x-ray beam/scintillator system in order to collect sufficient x-rays to be efficient. The Z-axis characteristic is the photodetector output in response to a constant intensity, narrow, x-ray stimulating beam as that beam is scanned from one Z-direction end of the scintillator bar to the other. Ideally, this characteristic is symmetric about the longitudinal center of the scintillator bar and increases monotonically from each end to the center. The increase in output near the ends of the bar is preferably complete once the entire Z-direction thickness of the beam is disposed on the scintillator bar with the output being substantially uniform along the intervening portion of the bar.
In order to meet these Z-axis requirements, the scintillator bar should have substantially uniform optical, luminescent and source radiation absorption properties along its entire length. For single crystal, impurity-activated scintillator bars, this requires the ability to grow source boules having uniform luminescent activator concentration both radially and lengthwise of the boule, since the luminescent output is dependent on the local concentration of the activator ion. Consequently, the process of selecting a scintillator material for a CT scanner, in addition to determining all of the other important properties of the material, preferably also includes establishing the feasibility of producing scintillator bars with acceptable Z-axis characteristics.
In a CT scanner, it is preferable to provide a reflective surface on all surfaces of the scintillator bar other than the surface along which the photodetector diode is disposed. Thus, a typical solid scintillation detector system comprises a plurality of individual scintillator bars positioned side-by-side with an individual photodetector diode coupled to each scintillator bar to convert its luminescent light into a corresponding electrical signal. It is important in such a system that all of the scintillator bars have similar overall conversion efficiencies (that is, substantially identical electrical output signals for identical incident x-ray radiation). This places another limitation on the selection of the scintillator material in that it must be possible to produce a sufficient quantity of scintillator bars having similar characteristics to assemble a scintillation detector having as many as 1,000 or more elements.
The primary decay time determines how fast a CT scanner can scan a patient since it is necessary for the luminescent output in response to radiation incident in one position of the scanner to have ceased before the luminescent output at another position of the scanner can be accurately measured. At present, a primary decay time of less than 500 microseconds is preferred, with still lower values being more desirable if they can be obtained without undesirable effects on other properties of the scintillator material such as maximum light output, radiation damage and hysteresis. It is also desirable that the maximum afterglow level be very small and that it decay relatively rapidly. For modern CT scanners, afterglow may be measured at 100 to 150 milliseconds after stimulating radiation termination and again at 300 milliseconds to characterize a scintillator material. An afterglow of less than 0.1% is considered highly desirable since the photodetector cannot distinguish between luminescent light which is a result of afterglow from earlier stimulation and luminescent light which is a result of present stimulation. Thus, afterglow can limit the intensity resolution of a CT scanner system.
For purposes of comparing the efficiency of different candidate scintillator materials, it is convenient to normalize light output. The amplitude of the output signal from a photodetector diode in response to stimulation of a standard sized scintillator bar of the candidate material with an established reference intensity of x-rays is compared with the output produced by cadmium tungstate of the same configuration in response to the same stimulation. Cadmium tungstate is a convenient standard because the self-activated nature of its luminescence results in substantially fixed light output for a given intensity of stimulating radiation so long as it has not been heavily radiation damaged, since its light output does not depend on the concentration of an activator. Thus, light output data taken by different individuals and at different times can be directly compared without having to first establish the calibration of different test setups.
It is desirable to have computed tomography scanning systems operate as fast as possible to maximize the number of patients that can be examined by a computed tomography scanner each working day and because the shorter time a scan takes, the easier it is for a patient to hold still during the scan. Further, the movement of internal organs is minimized.
As the scanning speed of a CT system is increased, the signal amplitude decreases for a fixed x-ray dose rate. Consequently, the signal-to-noise ratio, the contrast and thus the useful intensity resolution will decrease unless system parameters are adjusted to reduce noise. In order to reduce noise, the primary decay time of the scintillator should be reduced to a value where it does not contribute noise to the system. The afterglow should also be reduced as much as possible, since it provides a background luminescence intensity which is a noise contribution to the photodetector output. Selecting a scintillator material having its peak output in the vicinity of the peak sensitivity of the photodetector has the effect of reducing noise by increasing signal amplitude. Other modifications can also assist in maintaining the signal-to-noise ratio.
As the CT scanner field has matured, the speed of the electronics has increased, thus making faster scintillators desirable in order that a data scan may be performed in less time. It is now desired to operate CT scanning systems at speeds which require scintillators which are much faster than what was required as late as five years ago. Consequently, there is a vast lack of data about known solid luminescent materials which would be needed in order to select and make a scintillator material which is appropriate for use in a state-of-the-art CT scanning system where high speed electronics must be matched by a still higher speed scintillation material.
Separate from the problem of determining all these characteristics for individual candidate materials is the problem that, in a scintillation scanner, material must be provided in the form of a transparent solid body. Many luminescent materials which can be provided in powder form cannot be provided in a single crystalline form and thus are not available as transparent bodies. This inability to produce particular luminescent materials as single crystalline material can be a result of incompatibility of crystal structures, instability at Czochralski growth temperatures, low solubility of some components of a luminescent material in the crystal structure or the melt, a segregation coefficient which results in a non-uniform distribution within the boule of the additives and/or substituents or other reasons. Consequently, even if a particular luminescent composition is identified as apparently having desirable properties for use in a scintillation detector of a computed tomography-machine, production of such a scintillator detector is not straightforward. In many cases, the desired composition cannot be produced as a single crystalline material.
There are a number of luminescent materials which can be produced by flux growth techniques as small single crystals, but which cannot be produced as large single crystals because they are unstable at high temperatures and decompose into constituent materials. Other luminescent materials have been produced as thin films in attempts to develop phosphors for projection cathode ray tubes in order to minimize light loss due to scattering in amorphous or polycrystalline films. Such materials have no utility for the scintillators of CT scanners in the absence of an ability to provide a transparent body having sufficient thickness (generally at least 1 mm thick) for the material to be effective at stopping the x-rays employed in a CT scanning system. Further, the reports of the development work done on these materials contain no data on many characteristics which are crucial to determining whether a material is suitable for use in a CT scanning system.
A polycrystalline alternative to the single crystalline scintillator materials cesium iodide and cadmium tungstate is disclosed in U.S. Pat. Nos. 4,421,671; 4,466,929; 4,466,930; 4,473,413; 4,518,545; 4,518,546; 4,525,628; 4,571,312; 4,747,973 and 4,783,596. The scintillator composition disclosed in these patents is a cubic yttrium gadolinium oxide doped with various rare earth elements to provide a scintillator material having desired luminescent properties. These materials have not been prepared in single crystalline form because of the difficulty of growing crystals with desired, uniform distribution of all of the necessary constituents. As is further disclosed in the above recited patents, a method was developed for providing this doped yttrium-gadolinium oxide scintillator material in a polycrystalline ceramic form in which it is sufficiently transparent to provide an excellent scintillator material. This material has the substantial advantage over the cesium iodide and cadmium tungstate of being essentially free of radiation damage and hysteresis as well as having a sufficiently low afterglow to satisfy the requirements for a high quality CT scanning system. Unfortunately, this material has a primary decay time on the order of 1,000 microseconds and thus is not as fast as is desired for present state-of-the-art CT scanning systems.
It would be desirable to have a scintillator which is fast, has a low afterglow, no hysteresis, no non-linearity in output, high x-ray stopping power, high light output for a given stimulating x-ray input and which emits light at a frequency where photodetector diodes are particularly sensitive.
Single crystalline yttrium aluminum garnet (YAG) doped with neodymium is a known laser material. This material has also been further doped with chromium to increase the absorbence of the light frequency used to optically pump a YAG laser. While attempts have been made to produce transparent polycrystalline YAG, such attempts have not been successful. Reduced opacity or increased translucency or transparency has been reported in sintered YAG where magnesium oxide or silicon dioxide was included in the composition in a concentration of 500-2,000 ppm. However, even with this addition, true transparency is not obtained. Further, the inclusion of such transparency promoters in a scintillator material would be expected to be undesirable because of the potential for these impurities to adversely effect one or more of the desirable properties of a scintillator material.
Developments in optical and electrical ceramics have resulted in materials doped with multiple elements at 5 ppm to 1 mole percent levels. Dopants at such low levels can affect and improve the performance of these ceramics. Complex interactions between these elements makes optimization time consuming and expensive, as designs of experiments require dozens of individual samples, with each requiring a week of processing steps to form transparent samples for testing. Examples include the Gd3O2S:Pr,F,Ce scintillator disclosed by Hitachi in U.S. Pat. No. 4,442,360, and the Gd3Ga5O12:Cr,Ce scintillator disclosed by GE in U.S. Pat. No. 5,484,750.
There thus exists a need for the development of a method of combinatorial chemistry, which has been previously used to develop thin-film materials such as phosphors, for developing scintillators from solid transparent materials having a general thickness of over 1 mm. Previous to the present invention, inorganic combinatorial chemistry did not generate transparent materials of this thickness. Transparency or translucency is an important parameter for many optical ceramics, and can influence the measurement and optimization of a host of other properties such as radiation damage of a scintillator. Transparency occurs when light freely passes through a material without optical attenuation, whereas translucency occurs when light passes through materials with an optical attenuation coefficient of less than about 100 cmxe2x88x921. A second limitation of the current state of the art is that of elemental doping levels. Parts per million levels can be used for controlling electronic and optical properties, and the thin film techniques developed to date are limited in doping levels due to volume considerations. This is because thin film techniques typically use evaporation methods, which makes it difficult to control dopants at the level of 10 to 100 ppm level. Techniques for the creation of transparent ceramic libraries (TCLs) will accelerate this process and will likely result in more highly optimized compositions of matter.
In a preferred embodiment of the present invention there is provided a method of preparing and testing an array of ceramics for optical properties, comprising: providing a host material that is capable of being made optically transparent or translucent upon sintering; forming the host material into an array of pixels attached to a base plate; doping the host material; reacting the host material and the dopant, to form an-array of products; and testing the products for optical properties.

Combinatorial method foe development of optical ceramics


A picture encoding apparatus and the method in which the quantization step width of the lower hierarchy data having a resolution higher than that of the upper hierarchy data is determined for each predetermined block of respective hierarchy data based on the quantization step width determined by the upper hierarchy data having a low resolution, so that the additional code indicating the characteristics of quantizer can be omitted thereby the compression efficiency can be improved and the deterioration of picture quality can be reduced when picture data is hierarchical-encoded.

Heretofore, a picture encoding apparatus for encoding input picture data using a method of hierarchy encoding, for example, pyramid encoding has been provided. In this type of picture encoding apparatus, a first hierarchy data being input picture data of high resolution, a second hierarchy data of which its resolution is lower than that of the first hierarchy data, and a third hierarchy data of which its resolution is lower than that of the second hierarchy data, are sequentially and recursively formed. The plurality of hierarchy data are transmitted through one transmitting path being a communicating path or a recording/reproducing route.
In a picture decoding apparatus for decoding this plurality of hierarchy data, all of the plural picture data can be decoded, in addition to this, one of the desired hierarchy data can be selected and decoded in accordance with the resolution of the corresponding television monitor or the like. In this manner, only the desired hierarchy data is decoded out of the plurality of hierarchy data, so that the desired picture data can be obtained with the minimum amount of transmitting data at need.
Here, as shown in FIG. 1, in the hierarchy encoding, a picture encoding apparatus 1 for actualizing for example, four hierarchical-encoding, has decimating filters 2, 3, and 4 of three hierarchies and interpolating filters 5, 6, and 7. The input picture data D1 is passed through the decimating filters 2, 3, and 4 of the respective stages to sequentially form reduced picture data D2, D3, and D4 having a lower resolution, and the reduced picture data D2, D3, and D4 are passed through the interpolating filters 5, 6, and 7 to change the resolutions of those data to that before reducing.
Outputs D2 to D4 of the respective decimating filters 2 to 4 and outputs D5 to D7 of the respective interpolating filters 5 to 7 are input to difference circuits 8, 9, and 10 respectively, in order to generate difference data D8, D9, and D10. As a result, in the picture encoding apparatus 1, the data quantity of hierarchy data and the signal power are reduced. Here, the difference data D8 to D10 and the reduced picture data D4 have the sizes of 1, 1/4, 1/16, and 1/64 respectively in the areas.
The difference data D8 to D10 obtained from the difference circuits 8 to 10 and the reduced picture data D4 obtained from the decimating filter 4, are encoded by respective encoders 11, 12, 13, and 14 and are performed compression processing. As a result, first, second, third, and fourth hierarchy data D11, D12, D13, and D14 which have different resolutions respectively are sent from the respective encoders 11, 12, 13, and 14 to a transmitting path in a predetermined sequence.
Thus transmitted first through fourth hierarchy data D11 through D14 are decoded by a picture decoding apparatus 20 shown in FIG. 2. That is, the first through fourth hierarchy data D11 through D14 are decoded by decoders 21, 22, 23, and 24 respectively, so that the fourth hierarchy data D24 is output from the decoder 24.
Further, in an adding circuit 29, the output of the decoder 23 is added to the interpolating data of the fourth hierarchy data D24 obtained from an interpolating filter 26, to restore the third hierarchy data D23. Similarly, in an adding circuit 30, the output of the decoder 22 is added to the interpolating data of the third hierarchy data D23 obtained from an interpolating filter 27, to restore the second hierarchy data D22. Further, in an adding circuit 31, the output of the decoder 21 is added to the interpolating data of the second hierarchy data D22 obtained from an interpolating filter 28, to restore the first hierarchy data D21.
However, in a picture encoding apparatus realizing the above method of hierarchy encoding, the input picture data is divided into a plurality of hierarchy data and encoding it, hence, the amount of data of the hierarchy component is increased necessarily, as a result, it arises that compression efficiency decreases comparing with the case of using the high-efficiency encoding system in which hierarchy encoding is not used. Further, there is a problem that when improving the compression efficiency, the deterioration of picture quality occurs due to the respective quantizers applied to the hierarchy data.


An improved impact power tool for carving and engraving an article comprises an air delivery system operable to communicate with a pressurized air source; a drive assembly operable to receive air from the pressurized air source via the air delivery system; a hand held device in driven communication with the drive assembly; and a housing for storage of the air delivery system and drive assembly. The tool includes an improved valve design, a throttle bias valve, and an air storage tank housed within the housing, and an improved housing construction. The improved valve design and air storage tank enable greater stroke speeds of a work tool over a wider power range while also improving the crispness and speed of the impact reaction time over the entire range. The throttle bias valve is in communication with an additional exhaust path, such that the bias valve allows improved control of the hand held device and improved operation over a wider range of air pressures.

1. Field of the Invention
The present invention relates generally to impact power tools. More specifically, the present invention concerns an impact power tool, such as a pneumatically powered, rotary valve controlled tool, for use in delicate hand working operations, such as detailed, precise, and fine engraving, carving, and stone setting work.
2. Discussion of Prior Art
Delicate hand working operations, such as detailed, precise, and fine engraving, carving, and cutting on metals, woods, stones, and the like, as well as stone setting work require an impact tool that delivers a low impact energy level for each stroke of the tool and that is capable of delivering such low impact strokes at a rapid rate. These problems have previously been identified in U.S. Pat. No. 4,694,912, assigned of record to the assignee of the present invention, issued Sep. 22, 1987 and entitled CONTROLLED IMPACT POWER TOOL ("Glaser '912 patent") and hereby incorporated by reference herein.
The impact power tool disclosed in the Glaser '912 patent was an advance in the field and solved many of the problems identified in the art at the time. However, it has been determined that engravers and jewelry craftsmen increasingly are desiring to utilize larger hand piece attachments in their impact power tools, such as those capable of advanced carving applications on virtually any type of material, as well as desiring to utilize a wider range of hand pieces on the same impact power tool system for various and wide ranging applications. These desires are not being adequately met with the prior art impact power tools. In fact, craftsman desiring to perform multiple crafting applications that each require a different, wide range of power output must currently utilize multiple impact power tool systems to accomplish their tasks and even then, the combination of systems does not adequately address their desired ranges of power. Current impact power tool systems, particularly the use of multiple systems, undesirably consume valuable and limited inventory space on a craftsman's work bench.
Prior art impact power tools are also subject to other problems and limitations. For example, craftsman desire a crisp, quick, and immediate impact control adjustment. Such response time is simply lacking in prior art impact power tools. This problem is further frustrated by the craftsman's frequent "over-driving" of the tool—for example, when the craftsman is searching for the desired stroke speed or impact energy that is outside of the limits of the prior art tools. Accordingly, there is a need for an improved impact power tool.

Impact power tool with a precision controlled drive system


A method and apparatus for performing transformation and inverse transformation on a current block by using multi-core transform kernels in video encoding and decoding processes. A video decoding method may include obtaining, from a bitstream, multi-core transformation information indicating whether multi-core transformation kernels are to be used according to a size of a current block; obtaining horizontal transform kernel information and vertical transform kernel information from the bitstream when the multi-core transformation kernels are used according to the multi-core transformation information; determining a horizontal transform kernel for the current block according to the horizontal transform kernel information; determining a vertical transform kernel for the current block according to the vertical transform kernel information; and performing inverse transformation on the current block by using the horizontal transform kernel and the vertical transform kernel.

Image data is encoded by a codec conforming to a data compression standard, e.g., the Moving Picture Expert Group (MPEG) standard, and then is stored in a recording medium or transmitted through a communication channel in the form of a bitstream.
As hardware capable of reproducing and storing high-resolution or high-quality image content has been developed and become widely popular, a codec capable of efficiently encoding or decoding the high-resolution or high-quality image content is in high demand. The encoded image content may be reproduced by decoding it. Currently, methods of effectively compressing high-resolution or high-quality image content are used. For example, an image compression technique has been proposed to be effectively implemented by dividing an image to be encoded by an arbitrary method or manipulating data.
A transformation technique for frequency-transforming spatial-domain data into frequency-domain data is used as one of data manipulation techniques. In the compression standards, a fixed transform kernel is generally used because a transform kernel (a transform matrix) to be used for transformation and inverse transformation should be the same between an encoding process and a decoding process.

Video decoding method and apparatus using multi-core transform, and video encoding method and apparatus using multi-core transform


A method for exchanging heat with a patient's spinal column incident to spinal surgery or to relieve a patient for a hypoxia condition of the spine. A closed loop heat exchange catheter is percutaneously advanced into the retroperitoneal space of the patient or into the vasculature, and then heat exchange fluid is circulated through the catheter to cool the spinal column.

It has been discovered that the medical outcome for a patient suffering from various maladies, e.g., severe brain trauma or from ischemia caused by stroke or head attack or cardiac arrest is improved if the patient is cooled below normal body temperature (37° C.). Furthermore, it is also accepted that for such patients, it is important to prevent hyperthermia (fever) even if it is decided not to induce hypothermia. Moreover, in certain applications such as spinal surgery or to counter the effects of spinal injury, the present invention recognizes that cooling the spine can be advantageous.
The following U.S. patents, all of which are incorporated herein by reference, disclose various intravascular catheters/systems/methods which, as understood herein, can be used in the novel non-intravascular approach described herein: U.S. Pat. Nos. 6,749,625, 6,419,643, 6,416,533, 6,409,747, 6,405,080, 6,393,320, 6,368,304, 6,338,727, 6,299,599, 6,290,717, 6,287,326, 6,165,207, 6,149,670, 6,146,411, 6,126,684, 6,306,161, 6,264,679, 6,231,594, 6,149,676, 6,149,673, 6,110,168, 5,989,238, 5,879,329, 5,837,003, 6,383,210, 6,379,378, 6,364,899, 6,325,818, 6,312,452, 6,261,312, 6,254,626, 6,251,130, 6,251,129, 6,245,095, 6,238,428, 6,235,048, 6,231,595, 6,224,624, 6,149,677, 6,096,068, 6,042,559, and U.S. patent application Ser. No. 10/355,776.

This patent is subject to a terminal disclaimer.


An apparatus, system, and method are disclosed for copying data from a volatile memory device to a plurality of persistent storage devices in response to a loss of primary power. The apparatus includes a section module, a stripe module, and a write module. The section module sections a data image of a write cache into a plurality of data blocks. The stripe module establishes a plurality of data stripes from the plurality of data blocks. The write module writes in parallel each of the plurality of data stripes to a corresponding plurality of unique, persistent data storage devices in response to a loss of line power to the write cache. Advantageously, the apparatus quickly copies the write data from the write cache to a persistent memory device in a relatively short period of time, decreasing the dependence on significant batteries to back up the volatile memory device.

1. Technological Field
This invention relates to data copy technologies and more particularly relates to facilitating a parallel stripe copy.
2. Background Technology
Write caches are often incorporated into computer systems to increase perceived performance of the computer system. By implementing a write cache, the computer system may store certain data in memory, for example, and later write the data from memory to disk or another persistent storage device. Unfortunately, it is possible to lose the write data in the write cache in a volatile memory, such as random access memory (RAM), if a power failure occurs before the write data is written to persistent storage.
Conventional caching technologies have resulted in various proposed solutions to avoid losing the write data in response to a power loss. In particular, one conventional technology provides secondary, backup power to the memory device. These memory devices are often referred to as battery-backed memory (BBM) devices. A battery may back up the memory device for a long time. For example, some BBM devices are able to maintain write data in the write cache for approximately 72 hours. However, BBM devices can be costly in terms of purchasing and installing these devices. Additionally, BBM devices can take up a relatively large amount of physical space that otherwise might be used for additional computing devices.
Other conventional technologies provide backup power to the write cache, memory, processor, and storage devices long enough store a copy of the write data to persistent storage. These conventional technologies may be categorized into two types of copy operations: serial copies and parallel, ordered copies.
Serial copies, in which two or more copies of the same data are created in persistent storage, are facilitated by making a first copy of the write data and then making a second copy of the write data. These copies may be written to the same or to different persistent storage devices, such as two separate disks. While the redundant copies are typically more secure than only a single copy, the serial nature of the copy operations require that the secondary power source back up the system for a longer period of time in order to make the second copy after the first copy is completed.
Parallel copies, in contrast, take advantage of approximately parallel processing within the processor or multiple processors. Parallel copies also result in redundant copies, but are potentially created more quickly than serial copies. Parallel copies write a first copy to a first disk and a second copy to a second disk at approximately the same time. However, if the backup power fails before the parallel copy operations are completed, the user may lose data at the end of the write cache, even though parallel copies of the beginning portion of the write data may be preserved. In other words, two copies of only part of the data may be stored in persistent storage, but the remaining portion of both copies may be lost.
From the foregoing discussion, it should be apparent that a need exists for an apparatus, system, and method for copying data that decreases the opportunity for data loss as a result of a loss of secondary power during the copy operation. Furthermore, a need exists for an apparatus, system, and method for copying data that decreases the length of time during which the system or system components require secondary power to copy the write data from the write cache to persistent storage. Beneficially, such an apparatus, system, and method would overcome the present challenges associated with conventional copy technologies.

Apparatus, system, and method for writing stripes in parallel to unique persistent storage devices

International Business Machines Corporation


Foamed completion fluids and methods of completing subterranean zones penetrated by well bores are disclosed. A method of completing a subterranean zone penetrated by a well bore comprises the steps of providing or preparing a foamed completion fluid comprising water, one or more salts, a gas and a capryl/capramidopropylbetaine surfactant foaming agent, introducing the foamed treating fluid into the subterranean zone, and then carrying out a completion operation in the subterranean zone.

1. Field of the Invention
The present invention relates to foamed completion fluids and methods of completing subterranean zones utilizing the foamed completion fluids.
2. Description of the Prior Art
The completion process prepares a well for production and the fluids used at that stage of well construction are called "completion fluids." Initially, drilling fluids were used as completion fluids. Once perforating wells became a normal practice, it was found that using clean, solids-free brines for perforating increases well productivity. Well completion practices consisted of cementing casing, displacing the drilling fluid with a completion fluid and then perforating the well. Once the directional drilling evolved to horizontal and multilateral well designs and sand control in unconsolidated formations, the completion technology became more complex. As a result, specialized completion fluid technology has been developed and completion fluids are frequently used for perforating, forming gravel packs and other well operations such as the placement of tubing, packers, pumps and the like.
The aqueous completion fluids utilized are clean, relatively solids free, include one or more dissolved salts that provide weight to the completion fluids and do not react with the subterranean formation rock or hydrocarbons contained therein.
Completion fluids must also be compatible with formation clays to prevent clay swelling or deflocculating which causes the pore spaces in the subterranean formation to become blocked. Further, the completion fluids must be compatible with formation crude oil and natural gas so that oil-water emulsions are not formed which may produce formation damage.
The weight of an aqueous completion fluid can be adjusted by mixing one or more salts with the fluids, e.g., calcium chloride and calcium bromide. In order to prevent loss of the completion fluid, fluid loss control additives can be included in the completion fluids. Also, the rheology of a completion fluid can be controlled by the addition of friction reducers and/or lowering the viscosity of the completion fluid.
Thus, a completion fluid must be heavy enough to control formation pressure, be solids free, have minimum or no fluid loss to the producing formation and prevent damage to the formation.
While foamed completion fluids have been utilized heretofore, it has been difficult to form stable foamed completion fluids, particularly those completion fluids containing zinc bromide and other salts.
Thus, there is a need for foamed completion fluids formed of water, one or more salts, a gas and a foaming agent that are extremely stable.


An electronic circuit, referred to as an on-time extension circuit herein, provides an ability to adjust a power delivered to a load by pulsing a predetermined current to the load. The on time of the a DC-DC converter used to provide the power is extended to be longer than the on time of the current pulse when the on time of the current pulses becomes very short.

A variety of electronic circuits are used to drive loads and, more particularly, to control electrical current through strings of series connected light-emitting diodes (LEDs), which, in some embodiments, form an LED display, or, more particularly, a backlight for a display, for example, a liquid crystal display (LCD). It is known that individual LEDs have a variation in forward voltage drop from unit to unit. Therefore, the strings of series connected LEDs can have a variation in forward voltage drop.
Strings of series connected LEDs can be coupled to a common DC-DC converter, e.g., a switching regulator, e.g., a boost switching regulator, at one end of the LED strings, The switching regulator can be configured to provide a high enough voltage to supply each of the strings of LEDs. The other end of each of the strings of series connected LEDs can be coupled to a respective current sink, configured to sink a relatively constant current through each of the strings of series connected LEDs.
It will be appreciated that the voltage generated by the common switching regulator must be a high enough voltage to supply the one series connected string of LEDs having the greatest total voltage drop, plus an overhead voltage needed by the respective current sink. In other words, if four series connected strings of LEDs have voltage drops of 30V, 30V, 30V, and 31 volts, and each respective current sink requires at least one volt in order to operate, then the common boost switching regulator must supply at least 32 volts.
While it is possible to provide a fixed voltage switching regulator that can supply enough voltage for all possible series strings of LEDs, such a switching regulator would generate unnecessarily high power dissipation when driving strings of series connected LEDs having less voltage drop. Therefore, in some LED driver circuits, the voltage drops through each of the strings of series connected LEDs are sensed (for example, by a so-called "minimum select circuit," or by a multi-input amplifier) to select a lowest voltage or lowest average voltage appearing at the end of one of the strings of series connected LEDs. The common switching regulator is controlled to generate an output voltage only high enough to drive the series connected LED string having the lowest voltage (i.e., the highest voltage drop) or to drive a lowest average voltage to the strings. Arrangements are described, for example, in U.S. Pat. No. 6,822,403, issued Nov. 23, 2004, and in U.S. patent Ser. No. 12/267,645, filed Nov. 10, 2008, and entitled "Electronic Circuits for Driving Series Connected Light Emitting Diode Strings."
It will be understood that a predetermined current can be regulated though each one of the series connected diode strings, and the voltage of the DC-DC converter can be maintained just high enough to drive a worst case one of the diode strings, or to drive a worst case average voltage though the diode strings.
In some applications, it is desirable to dim or to brighten the LED diode strings. In some particular applications, it is desirable to brighten and to dim the LED diode string over a wide dynamic range.
In order to cause a dimming or brightening of the LEDs while still maintaining a desirable lowest voltage from the DC-DC converter (switching regulator), and while still maintaining the predetermined current through the diode strings, the predetermined current through the LEDs can be cycled on and off at a rate fast enough to be undetected by the human eye. When the current though the LEDs is on, the current equals the desirable predetermined current, and when the current through the LEDs is off, the current can be zero or some current less than the predetermined current.
When the current through the load is switched off, it is desirable to switch off the DC-DC converter, and when the current through the load is switched on, it is desirable to switch on the DC-DC converter. If the DC-DC converter is left on when the current through the load is switched off, the DC-DC converter would lack feedback control and the output voltage of the DC-DC converter could move to a different voltage, which is undesirable.
In order to achieve the wide dynamic range of brightness required by some applications, the on time of the current and the on time of the DC-DC converter must be able to be very short. For reasons described below, DC-DC converters are unable to achieve very short on times when switched on and off.
A DC-DC converter is often used in a feedback arrangement, in which a current or voltage at a load is sensed and the sensed current or voltage is used in a feedback loop to control the output voltage of the DC-DC converter. In a feedback loop, there is often so-called "compensation," often in the form of a capacitor or filter, in order to slow the response time of the feedback loop in order to maintain stability.
Furthermore, many types of DC-DC converters, and switching regulators in particular, use an inductor to store energy during operation. The DC-DC converter, and the inductor in particular, require a finite time to reach steady state operation, and to reach a steady state output voltage.
In view of the above, it should be recognized that, when a short on time is desired to achieve a wide brightness dynamic range, the DC-DC converter may not behave properly in short duty cycle operation and fluctuations of the output voltage of the DC-DC converter may result, which may result in undesirable fluctuation (flicker) in the brightness of the LEDS.
It would be desirable to provide a circuit and technique that can achieve a wide dynamic range of power provided by a DC-DC converter to a load in a feedback loop arrangement, while allowing a DC-DC converter to maintain proper operation and proper voltage regulation.

Electronic circuits and techniques for improving a short duty cycle behavior of a DC-DC converter driving a load


A computer program product for computing a correction rate predictor for medical record dictations, the computer program product residing on a computer-readable medium includes computer-readable instructions for causing a computer to obtain a draft medical transcription of at least a portion of a dictation, the dictation being from medical personnel and concerning a patient, determine features of the dictation to produce a feature set comprising a combination of features of the dictation, the features being relevant to a quantity of transcription errors in the transcription, analyze the feature set to compute a predicted correction rate associated with the dictation and use the predicted correction rate to determine whether to provide at least a portion of the transcription to a transcriptionist.

Healthcare costs in the United States account for a significant share of the GNP. The affordability of healthcare is of great concern to many Americans. Technological innovations offer an important leverage to reduce healthcare costs.
Many Healthcare institutions require doctors to keep accurate and detailed records concerning diagnosis and treatment of patients. Motivation for keeping such records include government regulations (such as Medicare and Medicaid regulations), desire for the best outcome for the patient, and mitigation of liability. The records include patient notes that reflect information that a doctor or other person adds to a patient record after a given diagnosis, patient interaction, lab test or the like.
Record keeping can be a time-consuming task, and the physician's time is valuable. The time required for a physician to hand-write or type patient notes can represent a significant expense. Verbal dictation of patient notes offers significant timesavings to physicians, and is becoming increasingly prevalent in modern healthcare organizations.
Over time, a significant industry has evolved around the transcription of medical dictation. Several companies produce special-purpose voice mailbox systems for storing medical dictation. These centralized systems hold voice mailboxes for a large number of physicians, each of whom can access a voice mailbox by dialing a phone number and putting in his or her identification code. These dictation voice mailbox systems are typically purchased or shared by healthcare institutions. Prices can be over $100,000 per voice mailbox system. Even at these prices, these centralized systems save healthcare institutions vast sums of money over the cost of maintaining records in a more distributed fashion.
Using today's voice mailbox medical dictation systems, when a doctor completes an interaction with a patient, the doctor calls a dictation voice mailbox, and dictates the records of the interaction with the patient. The voice mailbox is later accessed by a medical transcriptionist who listens to the audio and transcribes the audio into a text record. The playback of the audio data from the voice mailbox may be controlled by the transcriptionist through a set of foot pedals that mimic the action of the "forward", "play", and "rewind" buttons on a tape player. Should a transcriptionist hear an unfamiliar word, the standard practice is to stop the audio playback and look up the word in a printed dictionary.
Some medical transcriptionists may specialize in one area of medicine, or may deal primarily with a specific group of doctors. The level of familiarity with the doctors' voices and with the subject matter can increase the transcriptionist accuracy and efficiency over time.
The medical transcriptionist's time is less costly for the hospital than the doctor's time, and the medical transcriptionist is typically much more familiar with the computerized record-keeping systems than the doctor is, so this system offers a significant overall cost saving to the hospital.
To reduce costs further, health care organizations have deployed speech recognition technology, such as the AutoScript™ product (made by eScription™ of Needham, Mass.), to automatically transcribe medical dictations. Automatically transcribed medical records documents usually require editing by the transcriptionist.
In an application of background (as opposed to real-time) speech recognition to medical transcription, the automatic speech recognition process is run offline, i.e., without real-time clinician interaction. The speaker dictates and the speech recognition process is run in batch mode at another time. Draft transcriptions produced by the automatic speech recognition process may then be edited by the clinician or by a Medical Transcriptionist (MT) before being added to the medical record. An example of such an application is the EditScript™ product from eScription™.
Real-time and background speech recognition systems enroll and qualify clinicians using a prescribed quantity of training data, or in the case of most real-time ASR systems, by having the speaker dictate a specific text during an enrollment session. Once enrolled, all subsequent dictations for that speaker or speaker-worktype are processed through the speech recognition systems and transcriptions are created. For background ASR systems, these transcriptions are considered to be drafts manually edited by MTs before the final documents are uploaded into the electronic medical record. In real-time speech recognition applications, the words are transcribed as they are spoken, appearing on the computer screen for nearly immediate verification and editing by the clinician.
The yield of a background speech recognition application may be defined as the percentage of dictations which are able to be processed into draft transcriptions, as a fraction of the total number of dictations which enter the system. Generally, increasing the yield of an application reduces costs, so long as the drafts produced are of sufficient quality to save time when edited as compared to typing the transcription from scratch. Since draft transcriptions cannot be produced for a particular speaker until automatic speech recognition models exist for that speaker, there is an advantage in terms of system yield to create models with as little training as possible. However, drafts produced by ASR models based on very little training data generally lead to poorer quality draft transcriptions than would be possible by waiting for more training samples. Even with sufficient training data, some draft transcriptions require significant correction. For example, some drafts can produce more work for the MT than would typing the transcription from scratch, without the ASR device producing a draft. It may also be desirable to only allow editing of transcriptions that are substantially correct.


A transponder apparatus having an identifier associated therewith includes a receiver for receiving an RF signal transmitted by an interrogator, a power source and a processing unit that is operatively coupled to the power source and is capable of being in an inactive, sleep state (low current draw) and an active state. The transponder apparatus also includes a buffer device that is structured to: (i) receive an information signal based on the RF signal from the receiver, (ii) determine whether the information signal includes the identifier, and (iii) cause the processing unit to move from the inactive state to the active state and transmit at least a portion of the information signal to the processing unit only if it is determined that the information signal includes the identifier. An associated method is also provided.

The use of radio frequency identification (RFID) systems is expanding rapidly in a wide range of application areas. RFID systems consist of a number of radio frequency tags or transponders (RFID tags) and one or more radio frequency readers or interrogators (RFID readers). The RFID tags include one or more integrated circuit (IC) chips, such as a complementary metal oxide semiconductor (CMOS) chip, and an antenna connected thereto for allowing the RFID tag to communicate with an RFID reader over an air interface by way of RF signals. In a typical RFID system, one or more RFID readers query the RFID tags for information stored on them, which can be, for example, identification numbers, user written data, or sensed data. RFID systems have thus been applied in many application areas to track, monitor, and manage items as they move between physical locations.
RFID tags can generally be categorized as either passive tags or active tags. Passive RFID tags do not have an internal power supply. Instead, the relatively small electrical current induced in the antenna of a passive RFID tag by the incoming RF signal from the RFID reader provides enough power for the IC chip or chips in the tag to power up and transmit a response. Most passive RFID tags generate signals by backscattering the carrier signal sent from the RFID reader. Thus, the antenna of a passive RFID tag has to be designed to both collect power from the incoming RF signal and transmit (or reflect, e.g., backscatter) the outbound backscatter signal. Due to power limitations, the ability to provide devices such as sensors or microprocessors on passive RFID tags is limited. Passive RFID tags do, however, have the advantage of a near unlimited lifetime as they obtain their power from the RF signal sent from the RFID reader.
Active RFID tags, on the other hand, have their own internal power source, such as, without limitation, a battery, a fuel cell or what is commonly known as a super capacitor. The internal power source is used to power the IC chip or chips and discrete circuit elements, which typically include an RF receiver, an RF transmitter, and some type of controller, such as microcontroller or other processor, and any other electronics provided on the active RFID tag. As a result, active RFID tags can include relatively high power devices such as sensors, microprocessors, receivers and transmitters. Also, because of the on-board power, active RFID tags typically have longer ranges and larger memories than passive RFID tags. The internal power source, however, also means that active RFID tags typically have a lifetime that is limited by the lifetime of the power source. Thus, periodic maintenance is required.
As noted above, multiple active RFID tags may be used to track, monitor, and manage multiple items/assets as they move between physical locations. In such an application, each active RFID tag is affixed to an item/asset that is located in a particular location or environment, such as in a building. In current RFID systems, the active RFID tags, when deployed in such a manner, are done so in a state where (i) an RF receiver of the tag is in an active state for receiving RF signals, and (ii) the controller is in a low power inactive (sleep) state to preserve power. When one or more of the active RFID tags are to be queried, the RFID reader sends out a wake-up signal that is received by the RF receiver of each tag. Upon receipt of the signal, the RF receiver in each tag will then send a signal to the controller of the tag that causes it to move from the inactive state to an active (wake-up) state. For example, in RFID systems implemented according to the ISO 18000 Part 7 standard, when one or more tags are to be queried, the reader will send out a 30 KHz tone lasting for a period of approximately 2.5 seconds. Upon receipt of the tone, the RF receiver in each tag will wake-up the controller in the tag. The RFID reader then sends out signals intended for particular ones of the tags. Those particular tags for which the signals are intended will then perform the requested action, and the remaining tags (i.e., those tags not currently of interest to the reader) will move back to a sleep state. Alternatively, in some implementations both the RF receiver and the controller of each tag are in a constant active state when deployed, and therefore a wake-up signal is not required.
The multiple active RFID tag arrangements just described present at least two power management problems. First, each active RFID tag that is deployed is required to have at least one component in an active, relatively high power consuming state at all times. In the first described arrangement, an RF receiver of each tag is always "on" so that it can listen for the wake-up signal. In the second described arrangement, both the RF receiver and controller of each tag are always "on." Second, in the first described arrangement, when the RFID reader needs to query one or more particular tags, all of the tags that are deployed are woken up (for example, according to the ISO 18000, Part 7 standard), i.e., their controllers are caused to move to an active, relatively high power consuming state. Only when a particular tag determines that the query in question is not intended for it will it then move back to the sleep state. As will be appreciated, these problems result in unnecessary use of power from the power source (e.g., battery) of each tag, and therefore decreases the continuous uninterrupted operational lifetime of each tag by requiring periodic maintenance.

Methods and apparatus for reducing power consumption of an active transponder

University of Pittsburgh of the Commonwealth of Pennsylvania


A SAW device comprises a single crystal piezo-electric strate (made, for example, of LiTaO3 or LiNbO3), and an interdigital transducer (IDT) formed of a material mainly containing Al and disposed on the piezo-electric substrate. The piezo-electric strate contains an additive (for example, Fe, Mn, Cu, Ti), and an orientation rotated by an angle in a range of 42° to 48° (more preferably 46°±0.3°) from a Y-axis toward a Z-axis about an X-axis. The IDT presents a normalized thickness h/λ (h: thickness of electrode, and λ: spacing between digits of the IDT) of 7% to 11%. A more appropriate substrate cut angle can be shown for the SAW device which employs a piezo-electric substrate containing an additive, to improve the electric characteristics thereof.

The present invention relates to a surface acoustic wave device, and more particularly, to a substrate cut angle which is suitable for a single crystal piezo-electric substrate to which an additive is added to constitute a surface acoustic wave device.
A surface acoustic wave device (hereinafter called the "SAW device") which utilizes a surface acoustic wave (SAW) generated by a piezo-electric effect is widely applied to portable telephones and other electronic equipment as an electronic device such as a filter, a resonator and the like, because of its small size and light weight as well as high reliability.
The SAW device generally comprises a first electrode which is applied with a high frequency signal to excite a surface acoustic wave, a second electrode which receives the surface acoustic wave propagated thereto after excited by the first electrode, and converts the surface acoustic wave again to an electric signal to extract a signal at a particular frequency, and a piezo-electric substrate on which the first and second electrodes are formed. The SAW device can form part of a signal processing device for extracting a signal at a particular frequency, such as a filter, a resonator, a duplexer and the like.
A variety of proposals have also been made for an angle at which a used piezo-electric substrate is cut such that a resulting filter or resonator exhibits optimal electric characteristics, for example, in JP-A-2004-507960 and JP-A-9-167936.


The present invention provides a splice plate suitable for use in joining beams for use in a grid that supports panels and ceiling fixtures in a suspended ceiling. In particular, the present invention provides a splice plate suitable for use in joining main beams together for use in a grid that supports panels and ceiling fixtures in a suspended ceiling.

Suspended ceilings are common in many buildings and applications, including, for example, bathrooms, schools, and office buildings. They typically consist of a grid system formed by beams, and ceiling tiles that are suspended from overhead structural supports as by wires. The suspended ceilings are constructed at a job site, from the individual components, comprising main beams, cross-beams and wall angles, forming a grid. Such grid has parallel main beams that are connected by cross beams. The beams are of fixed length, for example, 12 feet, or 4 feet, or 2 feet. More than one beam may be connected together, in order to form the suspended ceiling grid of the desired dimensions.
There are various ways in which beams are connected.
For example, U.S. Pat. No. 7,788,872 B2 discloses a line of seismic main beam connections of the invention between main beams separates the ceiling into segments that move independently of each other during a quake, to limit a build-up in ceiling momentum.
In another example, U.S. Pat. No. 7,673,429 B2 discloses a ceiling system having a primary grid network which includes a plurality of grid members that are in generally perpendicular relation and form points of intersection. The ceiling system includes one or more joint clips, each of which is attached to the grid network at a point of intersection. Each joint clip partitions the primary grid network into smaller networks, which move independently of one another.
In another example, U.S. Pat. No. 7,661,236 B2 discloses a stab-in connector for a cross beam in a grid of a suspended ceiling, wherein the grid supports panels in rectangular grid openings; the connector having a top and a bottom angled flange extending outwardly at its top and at its bottom, respectively, the improvement comprising the connector with an indent, wherein the indent is formed v-shaped in the bottom angled flange with a height above the surface of the bottom angled flange.
In another example, U.S. Pat. No. 7,614,195 B2 discloses a ceiling grid for a suspended ceiling intended for use in zones subject to earthquakes, the improvement comprising a joint clip that (1) in a connection in the grid between a main beam and a pair of cross beams, each of which extends from an opposite side of the main beam, (2) permits, during an earthquake, the main beam and each of the pair of cross beams to move independently of one another, without transmitting forces between or among the beams; (3) is formed of a pair of loosely connected segments movable with respect to one another longitudinally of the main beam; and (4) has a) an overhang that extends above, and laterally across, the main beam and is slidably secured to the main beam by a cut-out in the overhang that conforms in shape generally to the cross-section of the bulb in the main beam, with a stop below the cut-out; b) an underhang on each side of the main beam integral with the overhang, that forms, with the overhang, a pocket that conforms in shape generally to the bulb and web in the cross beam, on each side of the main beam, and that extends laterally of the main beam over each cross beam, and slidably receives a cross beam, and; c) slots in each underhang that slidably receive a screw embedded in an end of the cross beam; whereby, by using a clip at connections along a selected main beam in the ceiling grid, one area of the ceiling grid is isolated from forces created in another area of the ceiling grid, during the earthquake.
In another example, U.S. Pat. No. 7,293,393 B2 discloses a perimeter clip that (a) attaches to an angle wall molding having a face and a ledge, and (b) supports a beam end in a suspended ceiling, the perimeter clip having (a) a first leg that attaches to and extends along the wall molding, and (b) a second leg that supports the beam end and that extends away from the wall molding face at a right angle to the first leg; the improvement comprising a slot in the second leg having (1) an inclined segment that extends upward and away from the first leg, and (2) a horizontal segment that extends toward the wall molding face from the inclined segment, wherein the slot receives a screw that extends through the slot into the web of the beam end being supported in the clip, with the screw being free to slide in the slot during an earthquake and support the beam end in the clip.
In another example, U.S. Pat. No. 6,957,517 B2 discloses a splice plate for a faceted curved beam formed in the field from a straight beam.
In another example, U.S. Pat. No. 6,729,100 B2 discloses a connector for a main tee of a suspended ceiling grid that has improved self-aligning and connection force properties.
In another example, U.S. Pat. No. 6,523,313 B2 discloses an end-to-end connection for main beams in a ceiling grid for a suspended ceiling.
In another example, U.S. Pat. No. 6,305,139 B2 discloses a clip for attachment to the end of a main beam for a grid in a suspended ceiling. The beam has an inverted T cross section. The clip engages an identical clip on the end of another main beam to form an end to end connection. The clip has a tongue and channel that engages with a tongue and channel in the other clip of the connection.
In another example, U.S. Pat. No. 6,178,712 B2 discloses a locking connection used to join the cross runners and main runners of a suspended grid ceiling system. The main runners are provided with periodic openings through which the cross runner ends are inserted and thereby locked together. Each cross tee end connector contains a resilient finger which engages the main runner upon insertion. Further, each connector has apertures and raised detents which will mate with those of a like opposing cross tee end connector when both are inserted through the same main runner opening. A locked grid intersection can be disengaged by depressing the resilient finger holding the main runner, rotating the main runner over the cross runner end connector, and pushing the cross tee end vertically free.
In another example, U.S. Pat. No. 6,199,343 B2 discloses a hook type assembly that interlocks a pair of intersecting cross-beams and a main beam in a grid for a suspended ceiling. A gapped ridge in a clip on each cross-beam engages the other gapped ridge in a vertical movement that is part of a hooking action while the assembly is formed.
In another example, U.S. Pat. No. 4,724,650 discloses an intersection spacer . . . for use in a subceiling structure of a grid of open-ended runner beams and intersecting open-ended cross beams.
In another example, U.S. Pat. No. 4,335,973 B2 discloses a splicer bar . . . for fastening together two inverted T-shaped runners. The splicer bar spans the junction between two runners and the splicer bar is fastened to the vertical web of both runners. Each runner has spaced apertures in its vertical web and the splicer bar has snap fasteners that will fit into these apertures to hold the two runners in parallel alignment and fixedly fastened together.
In another example, U.S. Pat. No. 4,314,432 discloses a pair of beams joinable end to end in aligned relation, each of the beams having a vertical web and lower flange at right angles thereto.
In another example, U.S. Pat. No. 4,108,563 A discloses locking connection for suspension ceiling systems.
In another example, U.S. Pat. No. 3,871,150 B2 discloses a main beam for use in a suspended ceiling system having a non-directional, integral coupling means provided at its ends.
In another example, U.S. Pat. No. 3,871,150 B2 discloses a clip structure . . . designed to snap over the flange of an existing suspended ceiling system suspension member. This clip will then accept or join with a new suspension member to help in the establishment of a second suspended ceiling system under the original suspended ceiling system of a room. To the second suspended ceiling system there is then mounted new ceiling boards to provide the ceiling with a new visible ceiling structure.
In another example, U.S. Pat. No. 3,284,977 B2 discloses an expansion splice.
In another example, U.S. Patent Application 20090223146A1 discloses a line of seismic main beam connections of the invention between main beams separates the ceiling into segments that move independently of each other during a quake, to limit a build-up in ceiling momentum. A slotted fishplate in the connection is set to keep the beam ends stable about a gap before a quake, and slidably connected about the gap during a quake.
In another example, U.S. Patent Application 20080060306A1 states "Joint clips of the invention are used in grids for suspended ceilings, at selected intersections, to create separate areas of ceiling that move independently of one another during an earthquake, to prevent a buildup of momentum in the entire ceiling."
In another example, U.S. Patent Application 20050166509A1 discloses a stab-in connector that locks with an opposing identical connector, through a slot in the main beam of a suspended ceiling grid. The connector has a cantilevered locking latch that is pivoted in an arc from the base of the connector that delays contact with the side of the slot as the connector is being stabbed into the slot.
In another example, U.S. Patent Application 20020124496A1 discloses an end-to-end connection for main beams in a ceiling grid for a suspended ceiling. A connector is formed at the end of a beam by combining a clip, fastened to the beam, with a configuration in the end of the beam. The connections are engaged to form a connection. The connection can be disengaged and reengaged.
In another example, European Patent EP1775398B1 discloses a connector for ceiling systems.
In another example, European Patent EP1640523B1 discloses a stab-in connector with expansion relief.
In another example, European Patent EP1553239B1 discloses a locking connector.
In another example, PCT Application WO2000008269A1 discloses a beam clip.
In another example, Canadian Patent Publication CA 1065572 a splice connection comprising: two generally aligned beam members each having a web means and a bead means surmounting said web means providing increased rigidity to said beam member, connecting means on adjacent ends of said web means splicing said beam members in an end-to-end relation.
To span a large room the main beams must be provided in sections which are spliced together end to end to form an abutting joint. It is difficult to produce a main beam connector that is consistently easy to assemble in the field and that will result in a reliable, sturdy and positive interconnection. Furthermore, the existing methods to splice beams frequently utilize pre-engineered splicing means that have a "male" and a "female" end, conferring a directionality to the beams, which must be followed, if the pre-engineered splicing means are to work. This may be difficult when adding a new suspended ceiling to an already existing suspended ceiling.
The present invention solves these problems by providing a joint or splice for a main beam in a suspended ceiling system which has a high degree of security and which insures a snug and precise fit between the abutting ends of a pair of beam sections. The splice of the present invention may be used with any beam, irrespective if the beam has pre-engineered splicing means. The splice of the present invention does not require pre-engineered fastening means to join main beams, and may be used on beams in either direction, or on beams without pre-engineered fastening means and provides a more secure connection than that produced by a pre-engineered fastening means. The splice plate of the present invention may also be used to splice beams of a different manufacturer together. The ability to splice together beams of different manufacturers is of particular usefulness because renovation projects and the like frequently require connecting an existing ceiling grid of one manufacturer to a new ceiling grid of a different manufacturer.


Provided is an apparatus for substrate processing. The apparatus may include a radiation source emitting a photonic beam, an optical system to form a beam image, a scanning stage, a temperature monitoring means, an output signal generator that compares the monitored temperature with a preset temperature, and a controller coupled to the radiation source and the stage. The stage may be adapted to scan the substrate so the beam image heats a region of the substrate surface, and the temperature monitoring means may collect and analyzes p-polarized radiation of at least three different spectral regions emitted from one or more places on the heated substrate region. The controller in response to a temperature error signal may be programmed to alter the beam intensity and/or to provide changes in the scanning velocity between the stage and the beam. Other apparatuses and temperature monitoring systems are provided as well.

1. Field of the Invention
The present invention relates to apparatuses and methods for remotely measuring the temperature of a surface, and has particular utility in the field of laser thermal processing (LTP) where a beam of radiation is scanned across a substrate surface to heat the surface, and has general utility to thermal processing where the temperature of a surface needs to be known to a relatively high degree of accuracy and precision.
2. Description of the Background Art
LTP is a technique for manufacturing semiconductor devices such as integrated circuits or "ICs". LTP involves irradiating a substrate, such as a doped semiconductor wafer, to bring the substrate surface from a relatively low temperature (e.g., 400° C.) to a relatively high temperature (e.g., 1,300° C.) so quickly that the substrate bulk remains at a low temperature and can pull the surface temperature down quickly. Such a rapid thermal cycle might be used, for example, to efficiently activate dopants in the substrate surface because only the material very close to the top surface of the substrate is heated to the relatively high temperature during irradiation.
As described in U.S. Pat. No. 6,747,245 to Talwar et al., one approach to LTP involves scanning a long, narrow laser beam back and forth across the wafer surface in a raster pattern. The amount of time the laser beam resides over a given point on the wafer surface is called the "dwell time". Using this scanning approach, it is possible to achieve peak surface temperatures near 1350° C. with dwell times in the millisecond range and below. The result is a rapid thermal annealing of doped Si wafers that yields high activation levels with very little dopant diffusion. When used to fabricate transistor-based circuits, transistors with an abrupt dopant profile and with a low sheet resistance are formed. LTP is capable of providing significantly lower sheet resistance values than possible using so-called Rapid Thermal Processing (RTP), which has dwell times equivalent to several seconds. While the LTP process is quick and effective, the results are sensitive to the peak temperature produced on the substrate surface.
Deviations in peak annealing temperatures may be produced as a result of substrate surface reflectivity variations. Deviations in annealing temperatures may also be an artifact of systemic process deviations associated with the apparatuses used to effect LTP. In either case, a difference in the peak annealing temperature of as little as a 5° C. can result in a measurable and undesirable difference in sheet resistance. Accordingly, it would be advantageous to provide a measurement means to ensure uniform heating during LTP. For example, it would be advantageous to be able to measure the maximum substrate surface temperature during LTP. Because of the rapid heating and cooling cycle associated with LTP, and because of the scanning geometry, in practice the peak surface temperature is best measured remotely. An exemplary remote temperature measuring technology is described in U.S. Patent Application Publication No. 20060255017 to Markle. In addition, it would be advantageous to be able to use the temperature measurement to control the amount of power delivered to the substrate surface.
Nevertheless, opportunities exist for improvements to known technologies relating to remote temperature technologies for LTP applications.

Methods and apparatus for temperature measurement and control on a remote substrate surface


A chain saw includes a motor unit and a guide bar clamped thereto by a clamping plate. The guide bar, which supports a saw chain, has a longitudinal slot formed therein. Clamping bolts carried by the motor unit pass through the slot and through the clamping plate for securing the clamping plate to the motor unit. One (or both) of the side edges of the slot includes corrugations. The clamping plate includes a hole aligned with the corrugations to enable a toothed key to be arranged in meshing engagement with the corrugations whereby a rack-and-pinion relationship is formed. By manually rotating the key, the guide bar is longitudinally displaced for varying the tension on the saw chain.

The present invention relates to a chain saw having a longitudinally displaceable guide bar for varying the tension on the saw chain.
For proper operation of a chain saw the saw chain has to be tight with a proper tensioning force. The guide bar is during operation clamped to the motor unit of the chain saw machine by a clamping plate which is normally held by two nuts threaded onto two bolts fixed to the motor unit and penetrating through a slot in the guide bar. When the chain tension is to be adjusted, e.g., when a chain is worn or when mounting a new chain, the nuts are left slightly loose, and the guide bar is pulled outwards by hand, or by some mechanism actuated by screwdrivers or wheels. Such mechanisms, which are usually located in the motor unit as described in the following patents: U.S. Pat. No. 5,528,835, No. 5,353,506, No. 5,491,899, German Document No. 42 22075, U.S. Pat. No. 5,497,557 and No. G-93 11081, push the guide bar outwards, e.g., by a peg penetrating a hole in the guide bar which is offset to one side of the bolt slot. To move the peg many different mechanisms have been used, employing helical or conical gears, cams or angular levers.
One main problem has been, however, to reach the actuating means. Since the strength of the guide bar in this critical region does not allow any extra cutouts to be formed therein, most designs involve an actuating means accessible behind the guide bar, often only by turning the chain saw upside down, which makes it difficult and time-consuming to adjust the chain tension. In some cases it has been attempted to control the peg movement from the same side as the nuts, such as German Document 44 36300 where the peg itself is rotated and connected by conical gears to a nut on a threaded shaft, which requires a special clamping plate with an oblong hole and which presents difficulties to arrange suitable bearings for the rotatable peg. In German Document G-93 11081, one of the nuts is connected by hollow spline shifts, helical gears and slip clutches to the screw mechanism for moving the peg, which requires an extra wide bolt slot to accommodate the hollow spline shaft.
All those mechanisms are rather complicated, employing a multitude of components and making the shell of the motor unit larger and difficult to produce. They also share the disadvantage that before fitting a new chain or guide bar, the peg has to be reset rearward.
Another type of tensioning mechanism is described in U.S. Pat. Nos. 4,939,842 and 5,070,618 where a gear wheel with a shaft journalled in the clamping plate acts on a rack part of the bolt slot, or a gear wheel with a shaft without any proper journal but guided by a hole in the guide bar acts on a rack surface in a recess in the motor casing. In both cases the shaft is rotated with a screwdriver. Disadvantages involve an insufficient journal support of the shaft, and the need of a relatively large gear diameter which requires a strong hand torque. The latter patent requires a difficult machining of the recess in the motor casing.

Method and apparatus for adjusting the tension on a saw chain


Provided is hydroxypropylmethylcellulose having a high thermal gelation temperature and a high thermal gel strength and a method for producing the same and a food comprising the hydroxypropylmethylcellulose. More specifically, provided is hydroxypropylmethylcellulose having an average substitution degree of a methoxy group of 1.0 to 2.0 per glucose unit, an average substitution degree of a hydroxypropoxy group of 0.05 to 0.4 per glucose unit, and a A/B value of 0.305 or greater wherein A represents a substitution degree of a methoxy group directly substituted for a hydroxy group on carbon at position 6 in a glucose unit free from a hydroxypropoxy group-substituted hydroxy group, B represents a substitution degree of a methoxy group per glucose unit, and the A/B represents a value of A divided by B.

1. Field of the Invention
The present invention relates to hydroxypropylmethylcellulose having a high thermal gel strength, a method for producing the same and a food comprising the hydroxypropylmethylcellulose.
2. Description of the Related Art
Cellulose ether capable of thermoreversibly gelating, such as methylcellulose and hydroxypropylmethylcellulose, is used in processed foods. For example, such cellulose ether is known to improve shape retention during heating when added to dry cheese (JP 01-080252A). The cellulose ether, when added with agar to freeze-dried foods such as freeze-dried tofu (bean curd), can produce a food which maintains its shape, even if large, during rehydration and during cooling after rehydration and has an excellent texture (JP 2005-348721A). The cellulose ether, when added to frozen foods, can thermally gelate during food processing or during heat-thawing to retain water, thereby keeping flavor (JP 2002-51758A).
In general, an aqueous methylcellulose solution forms a harder gel by heating than the gel an aqueous hydroxypropylmethylcellulose solution forms. Thus, methylcellulose is more preferable than hydroxypropylmethylcellulose as an additive for improving shape retention by thermal gelation. However, such methylcellulose has the problem that in the preparation of its aqueous solution, the methylcellulose cannot be dissolved completely unless it is temporarily cooled to 15° C. or lower. By contrast, hydroxypropylmethylcellulose can be dissolved in water at room temperature of 25° C. or higher. Thus, development of hydroxypropylmethylcellulose having excellent solubility and thermal gel strength has been demanded because cooling procedures at 15° C. or lower are often difficult to be performed in food preparation.
In general, the thermal gelation temperature of hydroxypropylmethylcellulose is higher than that of methylcellulose. A low thermal gelation temperature can offer rapid gelation during heating, while an excessively low thermal gelation temperature requires much time for returning to a solution state by natural cooling after temporal thermal gelation. For example, a compound having an excessively low thermal gelation temperature is added to heat-processed foods such as croquette, the food textures may deteriorate because the foods remain gelled during eating and are therefore too hard. Thus, a thermal gelation temperature, in addition to thermal gel strength, must also be taken into consideration in adding hydroxypropylmethylcellulose to processed foods for the purpose of exerting thermoreversible gelation effect.
Hydroxyalkylmethylcellulose having a high thermal gel strength is described in JP 2008-285673A. The hydroxyalkylmethylcellulose is produced through the steps of: adding a hydroxyalkyl etherification agent, and reacting the hydroxyalkyl etherification agent with alkali cellulose and then adding a methyl etherification agent to the reaction product; or the step of adding a hydroxyalkyl etherification agent and a methyl etherification agent such that 40% by weight or more of the stoichiometric amount of the methyl etherification agent is unreacted at the point in time when 60% by weight or more of the stoichiometric amount of the hydroxyalkyl etherification agent is reacted. However, this hydroxyalkylmethylcellulose, when used in food application, has been requested to be further improved in terms of thermal gel strength and a thermal gelation temperature.

Hydroxypropylmethylcellulose having high thermal gel strength, method for producing the same and food comprising the hydroxypropylmethylcellulose