A single crystal silicon wafer with a back surface free of an oxide seal and substantially free of a chemical vapor deposition process induced halo and an epitaxial silicon layer on the front surface, the epitaxial layer is characterized by an axially symmetric region extending radially outwardly from the central axis of the wafer toward the circumferential edge of the wafer having a substantially uniform resistivity, the radius of the axially symmetric region being at least about 80% of the length of the radius of the wafer.

The present invention generally relates to the preparation of semiconductor material substrates, especially silicon wafers, which are used in the manufacture of electronic components. More particularly, the present invention relates to a single crystal silicon wafer comprising an epitaxial silicon layer with reduced autodoping and a back surface that is free of halo.
In the production of single silicon crystals grown by the Czochralski method, polycrystalline silicon is first melted within a quartz crucible with or without dopant. After the polycrystalline silicon has melted and the temperature equilibrated, a seed crystal is dipped into the melt and subsequently extracted to form a single crystal silicon ingot while the quartz crucible is rotated. The single crystal silicon ingot is subsequently sliced into individual silicon wafers which are subjected to several processing steps including lapping/grinding, etching, and polishing to produce a finished silicon wafer having a front surface with specular gloss. In addition to polishing the front surface, many device manufacturers also request a polished back surface with a specular gloss (such wafers are commonly referred to as xe2x80x9cdouble-side polishedxe2x80x9d). To prepare the finished wafer for device manufacturing, the wafer may be subjected to a chemical vapor deposition process such as an epitaxial deposition process to grow a thin layer of silicon generally between about 0.1 xcexcm and about 200 xcexcm thick on the front surface of the wafer such that devices can be fabricated directly on the epitaxial layer. Conventional epitaxial deposition processes are disclosed in U.S. Pat. Nos. 5,904,769 and 5,769,942.
The epitaxial deposition process is typically comprised of two steps. In the first step after the silicon wafer is loaded into a deposition chamber and lowered onto a susceptor, the front surface of the wafer is subjected to a cleaning gas such as hydrogen or a hydrogen/hydrochloric acid mixture at about 1150xc2x0 C. to xe2x80x9cpre-bakexe2x80x9d and clean the front surface of the silicon wafer and remove any native oxide on that surface to allow the epitaxial silicon layer to grow continuously and evenly onto the front surface. In the second step of the epitaxial deposition process the front surface of the wafer is subjected to a vaporous silicon source such as silane or trichlorosilane at about 800xc2x0 C. or higher to deposit and grow an epitaxial layer of silicon on the front surface. During both steps of the epitaxial deposition process the silicon wafer is supported in the epitaxial deposition chamber by the susceptor which is generally rotated during the process to ensure even growth of the epitaxial layer. The susceptor is generally comprised of high purity graphite and has a silicon carbide layer completely covering the graphite to reduce the amount of contaminants such as iron released from the graphite into the surrounding ambient during high temperature processes. Conventional susceptors used in epitaxial growth processes are well known in the art and described in U.S. Pat. Nos. 4,322,592, 4,496,609, 5,200,157, and 5,242,501.
During the loading process, gas can be trapped between a conventional susceptor and the wafer as the wafer is lowered onto the susceptor causing the wafer to xe2x80x9cfloatxe2x80x9d and slide onto the susceptor in a position that is not intended (e.g., partly out of the recessed xe2x80x9cpocketxe2x80x9d). This can result in uneven epitaxial growth. Furthermore, during the pre-bake step a small amount of cleaning gas such as hydrogen can effuse around the wafer edge between the wafer and the susceptor and into the space between the wafer and the susceptor. If the back surface of the wafer is sealed with an oxide layer (typically about 3000 xc3x85 to about 5500 xc3x85 thick), the effused hydrogen will not react sufficiently with the oxide layer to create pinholes in the layer or completely remove the oxide layer. If the back surface is an etched or polished surface as desired by many device manufacturers and only has a thin native oxide layer (typically about 15 xc3x85 to about 30 xc3x85), the hydrogen or hydrogen/hydrochloric acid mixture will typically completely remove the native oxide layer near the outer edge of the back surface where the cleaning gas effuses around the wafer and create pinhole openings in the native oxide layer exposing the silicon surface as etching moves inward from the outer edge of the wafer. These pinhole openings typically form in an annular region inward of the circumferential edge of the wafer.
During the epitaxial deposition process a small amount of silicon containing source gas can also effuse around the wafer edge between the wafer and the susceptor and into space between the wafer and the susceptor. If the back surface of the wafer is oxide sealed, nucleation and growth of a silicon film is substantially suppressed. In areas where the native oxide layer has been completely etched away by the cleaning gas a smooth continuous layer of silicon is grown. However, in areas where the cleaning gas has not completely removed the native oxide layer, pinholes in the native oxide layer expose the silicon wafer and allow the silicon containing source gas to deposit silicon in the pinholes and create a nonuniform silicon film on the wafer backside during the epitaxial deposition. Thus, for wafers with etched or polished back surfaces having only a native oxide layer, pinholes created in the native oxide layer during the pre-bake step may lead to discontinuous silicon growth on the back surface which appears hazy under bright light illumination. This haziness or xe2x80x9chaloxe2x80x9d on the back surface of the wafer is comprised of small silicon growths or bumps having a diameter of about 0.5 xcexcm and being about 10 nm high. These bumps of silicon scatter light and lead to haziness and can be deemed undesirable as they can interfere with machine vision and optical pyrometry systems that view the back surface of the wafer during device processing. The halo is particularly visible to the eye under bright light and by laser surface scanners on the specular glossy back surface of a double side polished wafer (see FIG. 12A). In contrast, the relatively rough back surface of a single side polished wafer results in a significant degree of diffuse scattering of reflected light which reduces the appearance of halo.
Another problem encountered during the high temperature growth of the epitaxial silicon layer is the out-diffusion of dopant atoms such as boron or phosphorus through the back surface of the silicon wafer during the high temperature pre-bake and the epitaxial growth steps. With conventional susceptors, the dopant atoms that out-diffuse from the back surface can effuse between the wafer edge and the susceptor toward the front surface of the wafer. These dopant atoms can be incorporated into and contaminate the growing deposition layer and degrade the resistivity uniformity near the wafer edge. If the back surface of the silicon wafer is oxide sealed, the dopant atoms will not substantially out-diffuse from the back surface. Silicon wafers having etched or polished back surfaces, however, are subject to out-diffusion of dopant atoms from the back surface during the epitaxial deposition process which can lead to unwanted autodoping of the front surface.
Several methods have been suggested for attempting to eliminate back surface halos and autodoping. To eliminate back surface halos Nakamura (Japanese Unexamined Patent Application No. JP11-16844) disclosed performing a hydrogen fluoride strip and/or a high-temperature hydrogen annealing step of the back surface up to 10 days before the wafers are loaded into the epitaxial reactor. The process adds additional processing steps which can greatly increase complexity and cost of the deposition process. Deaton et al. (U.S. Pat. No. 5,960,555) disclosed a method of preventing the frontside reactive source gas from effusing to the wafer backside by utilizing a susceptor with built-in channels along the wafer edge for directing purge gas flows to the edge of the wafer. This process requires substantial modification of existing epitaxial deposition chambers and utilizes increased purge gas flows which can cause the purge gas to spill over to the front surface and mix with the source gas which can degrade the resulting epitaxial film.
To reduce autodoping, Hoshi (Japanese Unexamined Patent Application No. JP11-87250) disclosed using vacuum sucking on the edge of a susceptor to evacuate boron dopant on the edge of the susceptor and prevent autodoping. This process may affect wafer edge uniformity and thickness and requires substantial modification to existing epitaxial deposition systems. Nakamura (Japanese Unexamined Patent Application JP10-223545) disclosed a modified susceptor having slots on the edge of the susceptor such that the out-diffused dopant atoms would be pushed down through the slots and into the exhaust. This method also allows a substantial amount of the deposition gas to be evacuated below the back surface of the wafer which can lead to the halo affect previously discussed as well as premature corrosion of the exhaust system and safety concerns.
To date, therefore, methods of controlling the halo effect on the back surface of silicon wafers and autodoping problems associated with dopant out-diffusion from the back surface during an epitaxial deposition process have not been satisfactory. As such, a need exists in the semiconductor industry for a simple, cost effective approach to solving the halo effect and unwanted autodoping of the front surface of a silicon wafer during an epitaxial deposition process.
Among the objects of the present invention, therefore, is the provision of a single crystal silicon wafer which (a) has an epitaxial surface that is essentially unaffected by gas-phase autodoping; and (b) has a back surface free from halo.
Briefly, therefore, the present invention is directed to a single crystal silicon wafer comprising a silicon wafer substrate having a central axis, a front surface and a back surface which are generally perpendicular to the central axis, a circumferential edge, and a radius extending from the central axis to the circumferential edge of the wafer. The back surface of the wafer is free of an oxide seal and substantially free of a chemical vapor deposition process induced halo. Additionally, the silicon wafer substrate comprises P-type or N-type dopant atoms. The single crystal silicon wafer further comprises an epitaxial silicon layer on the front surface of the silicon wafer substrate. The epitaxial silicon layer is characterized by an axially symmetric region extending radially outwardly from the central axis toward the circumferential edge wherein the resistivity is substantially uniform. The radius of the axially symmetric region is at least about 80% of the length of the radius of the substrate. The epitaxial silicon layer also comprises P-type or N-type dopant atoms.
This invention is also directed to a process for growing an epitaxial silicon layer on a silicon wafer substrate in a chemical vapor deposition chamber. The process comprises contacting the front surface of the silicon wafer substrate and substantially the entire back surface of the silicon wafer substrate with a cleaning gas to remove an oxide layer from the front surface and the back surface of the silicon wafer substrate. After the oxide layer is removed, the epitaxial layer is grown on the front surface of the silicon wafer substrate. During the growth of the epitaxial layer, a purge gas is introduced into the the chemical vapor deposition chamber to reduce the number of out-diffused dopant atoms from the back surface of the silicon wafer substrate incorporated in the epitaxial silicon layer.
This invention is also directed to an apparatus for the support of a silicon wafer during the growth of an epitaxial silicon layer via a chemical vapor deposition process. The apparatus comprises a susceptor sized and configured for supporting the silicon wafer thereon. The susceptor has a surface with a density of openings between about 0.2 openings/cm2 and about 4 openings/cm2 which is in a generally parallel opposed relationship with the silicon wafer. The openings permit fluid flow through the surface for fluid contact with the back surface of the silicon wafer.
This invention is also directed to an apparatus for use in an epitaxial deposition process wherein an epitaxial silicon layer is grown on a silicon wafer substrate with a front surface and a back surface. The apparatus comprises a chamber, a wafer support device for supporting the silicon wafer substrate and rotatable means for supporting the wafer support device and the silicon wafer substrate. The wafer support device permits fluid contact with the front surface of the silicon wafer substrate and substantially the entire back surface of the silicon wafer substrate. The apparatus further comprises a heating element, a gas inlet for allowing cleaning gas, source gas and purge gas to enter the apparatus and a gas outlet for allowing the foregoing gases to exit the apparatus.
Other objects and features of this invention will be in part apparent and in part pointed out hereinafter.

Epitaxial silicon wafer free from autodoping and backside halo and a method and apparatus for the preparation thereof


An airbag apparatus according to an exemplary embodiment of the present invention includes: an airbag main body; at least one vent which is provided at a side of the airbag main body, and operated in an opened state; a shield which shields the vent; and a tether which is connected with the shield, in which when an occupant in a vehicle collides with the airbag main body, the tether is operated so that the shield shields the vent.

In general, an airbag apparatus for a vehicle is a safety device which deploys an airbag cushion at the time of a collision accident so as to mitigate impact, and prevents an occupant from being catapulted out of a vehicle body. The airbag apparatus may be classified into a driver airbag (DAB) and a passenger airbag (PAB) which protect occupants seated in front seats at the time of a head-on collision, and a side airbag (SAB) and a curtain airbag (CAB) which protect the sides of the occupants at the time of a broadside collision.
Regarding the passenger airbag among the airbag apparatuses, the very important point is that a problem with injury to the neck of the occupant needs to be improved by maintaining internal pressure after a collision with the occupant.
Particularly, it is necessary to pass the New Car Assessment Program (NCAP) Test in order to export vehicles to the North America, and a neck injury test is a test item with the highest importance in assessment of marketability of the passenger airbag according to the NCAP, and as a result, it is essential to improve a technology of reducing injury to the neck in this technical field.
As a related technology, Korean Patent Application Laid-Open No. 10-2013-0062521 discloses 'Airbag Cushion for Reducing Injuries having Vent Control Means'.
According to the airbag cushion for reducing injuries having a vent control means, a point of time at which a vent hole is closed is adjusted using a horizontal tether.
However, the airbag cushion for reducing injuries having a vent control means has a problem in that the vent hole cannot be closed in a case in which the horizontal tether is not pressed.


An attachment gusset with ruffled corners and method and machinery for manufacture provides a gusset formed of a continuous strip of material which is pleated at corners or turns in direction of the gusset to form ruffles which are attached to an adjacent layer of material. The ruffled gusset lies substantially flat against adjacent layers of material to which it is attached in a pressed state, and can be expanded to accommodate dimensional structures, such as cushioned pads. The number and spacing of pleats can be adjusted according to the radius of the corners or turns in the gusset. In a method of construction of the gusset, the pleats are formed as the material to which the gusset is attached is turned relative to the sewing point of attachment.

The present invention pertains generally to sewn articles and sewing operations and, more particularly, to sewn attachment of different pieces or panels of material by gussets.
In the sewn construction of padded articles, such as furniture cushions, seating and mattresses, a padded layer or layers may be enclosed in upholstery and attached by a gusset to an accompanying pad or spring unit. As shown in FIGS. 7 and 8, for example in a pillowtop style mattress, a pad or pillowtop 100 is attached to an adjacent support structure 120 by a gusset 140, which in one form is a folded band of material sewn along the fold line 141 and one edge 142 to a first panel 110, and sewn along the other edge 143 to the underside of pillowtop 100. At corners 160 of the pad 100 to which the gusset 140 is sewn, the gusset is mitered at seam 170 to allow the gusset to turn the ninety degree corner of the support structure 120. The mitering of the gusset at the corners 160 requires at least one miter cut to be made in the gusset at each right angle corner of the adjoining panel. Each of the mitered corner cuts must be individually sewn so that the gusset forms a closed structure between the mattress and the pillowtop. In a manual assembly process, the gusset is separately constructed by sewing together each leg of the gusset at the mitered corners to form a gusset frame which matches the mattress panel. The gusset is then sewn-attached to the edges of the top panel of the mattress by a tape edge. Thereafter, the pillowtop is attached to the other free edge of the gusset by a second tape edge.
If the miter cuts at the corners of the gusset are not made at the correct angles, the gusset corner will not have a smooth contour or appearance. Also, in articles where the gusset remains visible, the multiple seams in the gusset are unsightly and vulnerable to separation. Constructing a gusset this way is a tedious manual production process which adds significantly to the cost of producing pillowtop mattresses and similar sewn articles.
The present invention overcomes these and other disadvantages of the prior art by providing a ruffled gusset corner construction which is easier to manufacture and which has an improved finished appearance and strength over prior art pillowtop attachment constructions. In accordance with one aspect of the invention, there is provided an attachment gusset for attachment of adjoining panels, wherein the gusset is continuously folded in half along a length of the material and sewn at the fold line to a first panel, generally along one or more sides of the panel. At the corners of the panel, a series of pleats are formed on the inside folded edge of the gusset to create a ruffled ninety degree corner, or a turn of fewer or greater degrees, which matches the edge of the panel. In an automated method of manufacture aspect of the invention, the panel is turned ninety degrees relative to a sewing machine head as the pleats are formed and sewn to the panel at the corner. The aligned edges of the gusset are aligned with the edge of a first panel to which the gusset is sewn. The edge of the gusset against the panel is sewn with the panel edge by a tape edge. The other edge of the gusset is attached to the edge of a second overlying or parallel panel by another tape edge. Edges of other layers of material may also be included in the tape edge. In this way, two panels are securely attached about the perimeter. The spreading of the gusset halves relative to the sewn fold allows it to accommodate layers of padding contained by the panels, such as a padded pillowtop attached to the top panel of a mattress.
These and other aspects of the invention are herein described with reference to the accompanying Figures.

Pillowtop/panel attachment gusset with ruffled corners


A process for producing maleic anhydride from a C.sub.4 hydrocarbon selected from n-butane and n-butene feed which comprises: (a) feeding the C.sub.4 hydrocarbon and air to a reactor; (b) contacting the C.sub.4 hydrocarbon and air in the reactor with a catalyst comprising vanadium and phosphorus oxides at reaction conditions including a temperature between 550.degree. and 1000.degree. F. so as to obtain a reactor effluent containing maleic anhydride, unreacted butane, nitrogen, oxygen, and acrylic, acetic or maleic acid or mixtures of the foregoing acids; (c) removing maleic anhydride from the reactor effluent to obtain maleic anhydride-lean effluent; (d) removing said acids from at least a portion of the maleic anhydride-lean effluent to obtain a purified recycle stream containing less than 100 ppm of the acids; and (e) recycling the purified stream to the reactor. Preferably the acids are removed in step (d) by water and/or caustic scrubbing the maleic anhydride-lean effluent.

The present invention relates to the oxidation of a butane feed to maleic anhydride.
Oxidation of hydrocarbons to maleic anhydride is well known. Feeds which have been disclosed include benzene, butene, and n-butene. A series of patents to Kerr, including U.S. Pat. Nos. 3,156,705, 3,156,706, 3,156,707, 3,238,254, 3,255,211, 3,255,212, 3,255,213, 3,288,721, 3,351,565 and 3,385,796, discloses vanadium-phosphorus oxide catalysts for oxidation of butene to maleic anhydride.
Friedrichsen et al U.S. Pat. No. 3,478,063 discloses oxidation of olefinically unsaturated hydrocarbons with a catalyst containing vanadium and phosphorus oxides and wherein the amount of phosphorus oxide is at least equal to twice that of the vanadium oxide and wherein the catalyst contains at least one other oxide of chromium, iron, cobalt or nickel, and the catalyst is preferably on a carrier. The patent discloses at Col. 4 that the catalyst may have a surface area from 1 to 100 m.sup.2 /g.
Bergman U.S. Pat. No. 3,293,268 discloses a vanadium-phosphorus oxide catalyst for oxidation of butane to maleic anhydride. Surface area is not disclosed for the catalyst in the Bergman reference. Also, as in the Friedrichsen et al reference, the Bergman catalyst is prepared by an aqueous solution method.
Schneider U.S. Pat. No. 3,864,280 discloses a vanadium-phosphorus mixed oxide catalyst having an intrinsic surface area of 7 to 50 m.sup.2 /g. The Schneider catalyst can be prepared using an organic medium as opposed to an aqueous medium.
The use of recycle of unreacted constituents to a reactor is, of course, well known and frequently is employed in various processes.
Bissot et al, in "Oxidation of Butane to Maleic Anhydride", IEC Vol. 2, No. 1, March 1963, pp. 57-60, disclose that, in a process for conversion of butane to maleic anhydride unreacted butane may be recycled to the reactor. However, Bissot et al prefer to use sequential reaction, with maleic anhydride separation between the reactors, and with unreacted butane from the first reactor being fed to the second reactor, etc.
U.S. Pat. No. 3,904,652 discloses the oxidation of n-butane to maleic anhydride using enriched oxygen and with a recycle stream of reactor effluent which lowers the oxygen concentration in the total feed to the reactor. It is known that explosive mixtures of butane and oxygen exist and that some oxygen concentrations can cause an oxygen-butane-nitrogen mixture to go into the explosive range; see, for example, Bureau of Mines Bulletin 503 (1952), FIG. 35, page 62, and Bureau of Mines Bulletin 627 (1965), FIG. 21, page 23. In U.S. Pat. No. 3,904,652, the reactor feed mixture is kept below explosive (flammable) limits by the addition of an inert gas, e.g., nitrogen, to the enriched oxygen fresh feed.
Butane conversion levels in U.S. Pat. No. 3,904,652 are 30 to 70% per pass. The unconverted butane passes out of the oxidizer reactor as part of the reactor effluent. The effluent is processed to remove maleic anhydride. The maleic anhydride is removed from the effluent in part by cooling to condense out liquid maleic anhydride. Completion of maleic anhydride removal from the effluent is carried out by scrubbing the vapor/gaseous material left from the condensation step. The scrubbing is done by contacting the effluent with a recirculated aqueous maleic acid solution to which is added an undisclosed amount of fresh water. The maleic anhydride-free gaseous effluent is then divided into two parts, a recycle stream which is recycled back to the reactor, and a purge stream which is removed from the system.

Maleic anhydride production with recycle treatment


Composition and methods are disclosed for utilizing microaggregation of FAP-containing complexes to promote their fast internalization. This approach allows the uptake of cytotoxic cargo coupled to either FAP-Antibodies or FAP-liposome complexes by tumor bladder cells. Importantly, this approach is efficient even under serum-free conditions such as the ones found in the lumen of the bladder.

Bladder cancer is the fourth most common cancer in men and eleventh most common in women. Approximately 80% of the cases are classified as superficial cancer and most are treated with surgery alone. However, 70% of newly diagnosed patients suffer disease recurrence after surgical treatment. Therefore, the development of efficient therapeutic countermeasures against this pathology is a high priority.
The bladder displays unique characteristics and challenges as an organ to be targeted for therapy. Specifically, bladder epithelial cells lining the luminal surface, known as umbrella cells, are engaged in tight junctions that prevent access to the lower transitional cell layers. Furthermore, umbrella cells express characteristic extracellular proteins (uroplakins) that assemble into semi-rigid plaques that effectively shield the apical surface. The urothelium is further isolated from the bladder lumen by a mucin layer comprised of GlycosAminoGlycans (GAG) that are produced and assembled on the apical surface of the umbrella cells. In addition, the well-differentiated umbrella cells have limited secretory and endocytic capacity. In contrast, malignant bladder cells are usually less differentiated and polarized, exhibit diminished uroplakin expression and low GAG layer synthesis. Therefore, as opposed to normal bladder epithelia, neoplastic cells are exposed to the lumen of the bladder. This leads to increased accessibility of tumor lesions to therapeutic agents, compared to the well-protected normal regions of the bladder. However, constant urine influx and periodic voiding of the bladder makes the direct instillation of therapeutic drugs limited in their impact on bladder tumor cells.
At present, intravesical instillation of live Mycobacterium bovis bacillus Calmette-Guerin (BCG) is currently the adjuvant therapy of choice for the treatment of superficial bladder tumors. While the specific mechanisms of BCG-mediated antitumor activity is not yet fully understood, direct targeting and binding to bladder tumor cells, followed by cellular uptake and subsequent activation of adaptive immune responses, are required. Nevertheless, intravesical BCG is associated with high local morbidity and a risk of systemic mycobacterial infection. Notably, multiple instillations leads to increased toxicity, thus limiting patient tolerance for the treatment regimen required for effective anti-cancer activity. Therefore, the development of high-affinity, non-toxic targeting strategies is of high priority in the field.
A breakthrough came from the identification of BCG's Fibronectin Attachment Protein (FAP) as the targeting molecule used by the bacteria to adhere to bladder tumor cells (Ratliff et al. Infect Immun 1993; 61: 1889-94; Schorey et al. Mol Microbiol 1996; 21: 321-9; and Schorey et al. Infect Immun 1995; 63: 2652-7). FAP was shown to interact with α5β1 Integrin-bound fibronectin (FBN) and undergo internalization by tumor cells. Since FAP by itself was observed to mediate antitumor activity in FAP-immune mice (Sinn et al. Cancer Immunol Immunother 2008; 57: 573-9), it may represent a lower-risk alternative to BCG for therapeutic purposes. In addition, the internalization of FAP by bladder tumor cells provides a novel and potentially powerful approach for the delivery of therapeutics that may greatly enhance the antitumor effect of FAP.
In accordance with the present disclosure a FAP-targeted delivery strategy is provided for delivering and inducing the uptake of cytotoxic agents into bladder tumor cells.

Treating bladder tumor cells using fibronectin attachment protein as a target


Examples are disclosed that relate to the coupling of light into a light guide for a backlight system. One disclosed example provides a flat-panel illuminator comprising a concentrating reflector, a light guide, and one or more light emitters. The example includes a curved reflective portion, a light guide including a planar face and an input edge positioned adjacent the concentrating reflector, and the one or more light emitters are arranged within the concentrating reflector and spaced from the input edge of the light guide.

Some electronic displays include a light guide edge-lit by a row of light-emitting diodes (LEDs). One consideration for such displays is the efficiency at which light emission from the LEDs is coupled into the light guide. Losses at the LED/light-guide interface may result in reduced display brightness, increased power consumption, and stray light effects that may degrade display image quality.

Flat panel illuminator with concentrator


A digital radiographic detector includes a multi-layered core having integrated circuits generating heat within a housing of the detector. A thermally conductive component that is configured to provide a distinct function for the core is thermally coupled to the integrated circuits to also serve as a heat sink therefor.

The subject matter disclosed herein relates to digital radiographic (DR) detectors.
Portable digital radiographic detectors have been widely deployed to improve diagnostic radiographic imaging productivity, image quality and ease of use. In particular, mobile or bedside radiographic imaging is conducted in locations such as intensive care units so that the patient does not need to be transported from their critical care environment. This type of imaging procedure is best served by a portable detector to improve ease of use and reliability.
Current digital radiographic detectors typically include an image sensor array made from amorphous silicon having thin-film-transistors and photo diodes fabricated on a substrate, such as a rigid glass substrate, using semiconductor processes that are similar to those used for flat panel displays. A scintillator is combined with the image sensor array, along with required electronics for image signal readout and image processing, onto an internal multilayer core plate which is contained within a durable housing, such as a carbon fiber housing, to create the portable DR detector.
Heat generated inside a DR detector having a thermally nonconductive carbon fiber housing may not have a good thermal dissipation path. Heat accumulating in pockets within the carbon fiber housing may cause imaging problems in DR detectors.
Advantageous features of the digital radiographic detectors disclosed herein include light weight, durable DR detector, with a housing such as a carbon fiber based housing, having excellent thermal management and a layered core plate assembly that takes advantage of the benefits provided by a light weight image sensor core and well designed thermal management.
FIG. 1 is a perspective view of a digital radiographic (DR) imaging system 10 that may include a generally curved or planar DR detector 40 (shown in a planar embodiment and without a housing for clarity of description), an x-ray source 14 configured to generate radiographic energy (x-ray radiation), and a digital monitor, or electronic display, 26 configured to display images captured by the DR detector 40, according to one embodiment. The DR detector 40 may include a two dimensional array 12 of detector cells 22 (photosensors), arranged in electronically addressable rows and columns. The DR detector 40 may be positioned to receive x-rays 16 passing through a subject 20 during a radiographic energy exposure, or radiographic energy pulse, emitted by the x-ray source 14. As shown in FIG. 1, the radiographic imaging system 10 may use an x-ray source 14 that emits collimated x-rays 16, e.g. an x-ray beam, selectively aimed at and passing through a preselected region 18 of the subject 20. The x-ray beam 16 may be attenuated by varying degrees along its plurality of rays according to the internal structure of the subject 20, which attenuated rays are detected by the array 12 of photosensitive detector cells 22. The curved or planar DR detector 40 is positioned, as much as possible, in a perpendicular relation to a substantially central ray 17 of the plurality of rays 16 emitted by the x-ray source 14. In a curved array embodiment, the source 14 may be centrally positioned such that a larger percentage, or all, of the photosensitive detector cells are positioned perpendicular to incoming x-rays from the centrally positioned source 14. The array 12 of individual photosensitive cells (pixels) 22 may be electronically addressed (scanned) by their position according to column and row. As used herein, the terms "column" and "row" refer to the vertical and horizontal arrangement of the photo sensor cells 22 and, for clarity of description, it will be assumed that the rows extend horizontally and the columns extend vertically. However, the orientation of the columns and rows is arbitrary and does not limit the scope of any embodiments disclosed herein. Furthermore, the term "subject" may be illustrated as a human patient in the description of FIG. 1, however, a subject of a DR imaging system, as the term is used herein, may be a human, an animal, an inanimate object, or a portion thereof.
In one exemplary embodiment, the rows of photosensitive cells 22 may be scanned one or more at a time by electronic scanning circuit 28 so that the exposure data from the array 12 may be transmitted to electronic read-out circuit 30. Each photosensitive cell 22 may independently store a charge proportional to an intensity, or energy level, of the attenuated radiographic radiation, or x-rays, received and absorbed in the cell. Thus, each photosensitive cell, when read-out, provides information defining a pixel of a radiographic image 24, e.g. a brightness level or an amount of energy absorbed by the pixel, that may be digitally decoded by image processing electronics 34 and transmitted to be displayed by the digital monitor 26 for viewing by a user. An electronic bias circuit 32 is electrically connected to the two-dimensional detector array 12 to provide a bias voltage to each of the photosensitive cells 22.
Each of the bias circuit 32, the scanning circuit 28, and the read-out circuit 30 may include heat generating integrated circuits and may communicate with an acquisition control and image processing unit 34 over a connected cable 33 (wired), or the DR detector 40 and the acquisition control and image processing unit 34 may be equipped with a wireless transmitter and receiver to transmit radiographic image data wirelessly 35 to the acquisition control and image processing unit 34. The acquisition control and image processing unit 34 may include a processor and electronic memory (not shown) to control operations of the DR detector 40 as described herein, including control of circuits 28, 30, and 32, for example, by use of programmed instructions, and to store and process image data. The acquisition control and image processing unit 34 may also be used to control activation of the x-ray source 14 during a radiographic exposure, controlling an x-ray tube electric current magnitude, and thus the fluence of x-rays in x-ray beam 16, and/or the x-ray tube voltage, and thus the energy level of the x-rays in x-ray beam 16. A portion or all of the acquisition control and image processing unit 34 functions may reside in the detector 40 in an on-board processing system 36 which may include a processor and electronic memory to control operations of the DR detector 40 as described herein, including control of circuits 28, 30, and 32, by use of programmed instructions, and to store and process image data similar to the functions of standalone acquisition control and image processing system 34. The image processing system may perform image acquisition and image disposition functions as described herein. The image processing system 36 may control image transmission and image processing and image correction on board the detector 40 based on instructions or other commands transmitted from the acquisition control and image processing unit 34, and transmit corrected digital image data therefrom. Alternatively, acquisition control and image processing unit 34 may receive raw image data from the detector 40 and process the image data and store it, or it may store raw unprocessed image data in local memory, or in remotely accessible memory.
With regard to a direct detection embodiment of DR detector 40, the photosensitive cells 22 may each include a sensing element sensitive to x-rays, i.e. it absorbs x-rays and generates an amount of charge carriers in proportion to a magnitude of the absorbed x-ray energy. A switching element may be configured to be selectively activated to read out the charge level of a corresponding x-ray sensing element. With regard to an indirect detection embodiment of DR detector 40, photosensitive cells 22 may each include a sensing element sensitive to light rays in the visible spectrum, i.e. it absorbs light rays and generates an amount of charge carriers in proportion to a magnitude of the absorbed light energy, and a switching element that is selectively activated to read the charge level of the corresponding sensing element. A scintillator, or wavelength converter, may be disposed over the light sensitive sensing elements to convert incident x-ray radiographic energy to visible light energy. Thus, in the embodiments disclosed herein, it should be noted that the DR detector 40 (or DR detector 300 in FIG. 3 or DR detector 400 in FIG. 4) may include an indirect or direct type of DR detector.
Examples of sensing elements used in sensing array 12 include various types of photoelectric conversion devices (e.g., photosensors) such as photodiodes (P-N or PIN diodes), photo-capacitors (MIS), photo-transistors or photoconductors. Examples of switching elements used for signal read-out include a-Si TFTs, oxide TFTs, MOS transistors, bipolar transistors and other p-n junction components.
FIG. 2 is a schematic diagram 240 of a portion of a two-dimensional array 12 for a DR detector 40. The array of photosensor cells 212, whose operation may be consistent with the photosensor array 12 described above, may include a number of hydrogenated amorphous silicon (a-Si:H) n-i-p photodiodes 270 and thin film transistors (TFTs) 271 formed as field effect transistors (FETs) each having gate (G), source (S), and drain (D) terminals. In embodiments of DR detector 40 disclosed herein, such as a multilayer DR detector (400 of FIG. 4), the two-dimensional array of photosensor cells 12 may be formed in a device layer that abuts adjacent layers of the DR detector structure, which adjacent layers may include a rigid glass layer or a flexible polyimide layer or a layer including carbon fiber without any adjacent rigid layers. A plurality of gate driver circuits 228 may be electrically connected to a plurality of gate lines 283 which control a voltage applied to the gates of TFTs 271, a plurality of readout circuits 230 may be electrically connected to data lines 284, and a plurality of bias lines 285 may be electrically connected to a bias line bus or a variable bias reference voltage line 232 which controls a voltage applied to the photodiodes 270. Charge amplifiers 286 may be electrically connected to the data lines 284 to receive signals therefrom. Outputs from the charge amplifiers 286 may be electrically connected to a multiplexer 287, such as an analog multiplexer, then to an analog-to-digital converter (ADC) 288, or they may be directly connected to the ADC, to stream out the digital radiographic image data at desired rates. In one embodiment, the schematic diagram of FIG. 2 may represent a portion of a DR detector 40 such as an a-Si:H based indirect flat panel, curved panel, or flexible panel imager.
Incident x-rays, or x-ray photons, 16 are converted to optical photons, or light rays, by a scintillator, which light rays are subsequently converted to electron-hole pairs, or charges, upon impacting the a-Si:H n-i-p photodiodes 270. In one embodiment, an exemplary detector cell 222, which may be equivalently referred to herein as a pixel, may include a photodiode 270 having its anode electrically connected to a bias line 285 and its cathode electrically connected to the drain (D) of TFT 271. The bias reference voltage line 232 can control a bias voltage of the photodiodes 270 at each of the detector cells 222. The charge capacity of each of the photodiodes 270 is a function of its bias voltage and its capacitance. In general, a reverse bias voltage, e.g. a negative voltage, may be applied to the bias lines 285 to create an electric field (and hence a depletion region) across the pn junction of each of the photodiodes 270 to enhance its collection efficiency for the charges generated by incident light rays. The image signal represented by the array of photosensor cells 212 may be integrated by the photodiodes while their associated TFTs 271 are held in a non-conducting (off) state, for example, by maintaining the gate lines 283 at a negative voltage via the gate driver circuits 228. The photosensor cell array 212 may be read out by sequentially switching rows of the TFTs 271 to a conducting (on) state by means of the gate driver circuits 228. When a row of the pixels 22 is switched to a conducting state, for example by applying a positive voltage to the corresponding gate line 283, collected charge from the photodiode in those pixels may be transferred along data lines 284 and integrated by the external charge amplifier circuits 286. The row may then be switched back to a non-conducting state, and the process is repeated for each row until the entire array of photosensor cells 212 has been read out. The integrated signal outputs are transferred from the external charge amplifiers 286 to an analog-to-digital converter (ADC) 288 using a parallel-to-serial converter, such as multiplexer 287, which together comprise read-out circuit 230.
This digital image information may be subsequently processed by image processing system 34 to yield a digital image which may then be digitally stored and immediately displayed on monitor 26, or it may be displayed at a later time by accessing the digital electronic memory containing the stored image. The flat panel DR detector 40 having an imaging array as described with reference to FIG. 2 is capable of both single-shot (e.g., static, radiographic) and continuous (e.g., fluoroscopic) image acquisition.
FIG. 3 shows a perspective view of an exemplary prior art generally rectangular, planar, portable wireless DR detector 300 according to an embodiment of DR detector 40 disclosed herein. The DR detector 300 may include a flexible substrate to allow the DR detector to capture radiographic images in a curved orientation. The flexible substrate may be fabricated in a permanent curved orientation, or it may remain flexible throughout its life to provide an adjustable curvature in two or three dimensions, as desired. The DR detector 300 may include a similarly flexible housing portion 314 that surrounds a multilayer structure, or core, comprising a flexible photosensor array portion 22 of the DR detector 300. The housing portion 314 of the DR detector 300 may include a continuous, rigid or flexible, x-ray opaque material or, as used synonymously herein a radio-opaque material, surrounding an interior volume of the DR detector 300. The housing portion 314 may include four flexible edges 318, extending between the top side 321 and the bottom side 322, and arranged substantially orthogonally in relation to the top and bottom sides 321, 322. The bottom side 322 may be continuous with the four edges and disposed opposite the top side 321 of the DR detector 300. The top side 321 comprises a top cover 312 attached to the housing portion 314 which, together with the housing portion 314, substantially encloses the core in the interior volume of the DR detector 300. The top cover 312 may be attached to the housing 314 to form a seal therebetween, and be made of a material that passes x-rays 16 without significant attenuation thereof, i.e., an x-ray transmissive material or, as used synonymously herein, a radiolucent material, such as a carbon fiber, carbon fiber embedded plastic, polymeric, elastomeric and other plastic based material.
With reference to FIG. 4, there is illustrated in schematic form an exemplary cross-section view along section 4-4 of the exemplary embodiment of the DR detector 300 (FIG. 3). For spatial reference purposes, one major surface, or side, of the DR detector 400 may be referred to as the top side 451 and a second major surface, or side, of the DR detector 400 may be referred to as the bottom side 452, as used herein. The core layers, sheets, or plates may be disposed within the interior volume 450 enclosed by the housing 314 and top cover 312 and may include a flexible curved or planar scintillator layer 404 over a curved or planar the two-dimensional imaging sensor array 12 shown schematically as the device layer 402. The scintillator layer 404 may be directly under (e.g., directly connected to) the substantially planar top cover 312, and the imaging array 402 may be directly under the scintillator 404. Alternatively, a flexible layer 406 may be positioned between the scintillator layer 404 and the top cover 312 as part of the core layered structure to allow adjustable curvature of the core layered structure and/or to provide shock absorption. The flexible layer 406 may be selected to provide an amount of flexible support for both the top cover 312 and the scintillator 404, and may comprise a foam rubber type of material. The layers just described comprising the core layered structure each may generally be formed in a rectangular shape and defined by edges arranged orthogonally and disposed in parallel with an interior side of the edges 318 of the housing 314, as described in reference to FIG. 3.
A substrate layer 420 may be disposed under the imaging array 402, such as a rigid glass layer, in one embodiment, or flexible substrate comprising polyimide or carbon fiber upon which the array of photosensors 402 may be formed to allow adjustable curvature of the array, and may comprise another layer of the core layered structure. Under the substrate layer 420 a radio-opaque shield layer 418, such as lead, may be used as an x-ray blocking layer to help prevent scattering of x-rays passing through the substrate layer 420 as well as to block x-rays reflected from other surfaces in the interior volume 450. Readout electronics, including the scanning circuit 28, the read-out circuit 30, the bias circuit 32, and processing system 36 (all shown in FIG. 1) may be formed adjacent the imaging array 402 or, as shown, may be disposed below support member 416 in the form of integrated circuits (ICs) electrically connected to printed circuit boards (PCBs) 424, 425.
The support member 416 may be electrically conductive, such as an aluminum support, or other electrically conductive material. The support member 416, if made from a metal, may also be thermally conductive. As an electrically conductive structure, the support member 416 may be configured to function as a ground plane, or ground circuit, for the PCBs 424, 425. Thus, the support member 416 may be electrically connected to the PCBs 424, 425 using electrically conductive connectors 421. The imaging array 402 may be electrically connected to the readout electronics 424 (ICs) over a flexible connector 428 which may comprise a plurality of flexible, sealed conductive circuits known as chip-on-film (CoF) flex circuits. As a thermally conductive structure, the support member 416 may be configured to also function as a heat sink to dissipate heat generated by the IC chips on the PCBs 424, 425 or IC chips on the CoF flex circuit, as described herein below.
X-ray flux may pass through the radiolucent top panel cover 312, in the direction represented by an exemplary x-ray beam 16, and impinge upon scintillator 404 where stimulation by the high-energy x-rays 16, or photons, causes the scintillator 404 to emit lower energy photons as visible light rays which are then received in the photosensors of imaging array 402. The frame support member 416 may connect the core layered structure to the housing 314 and may further operate as a shock absorber by disposing elastic pads (not shown) between the frame support beams 422 and the housing 314. Fasteners 410 may be used to attach the top cover 312 to the housing 314 and create a seal therebetween in the region 430 where they come into contact. In one embodiment, an external bumper 412 may be attached along the edges 318 of the DR detector 400 to provide additional shock-absorption.
Processes have been developed that enable fabrication of the image sensor array and core layers onto durable thin substrates that are enclosed in a carbon fiber housing having a unitary structure. This highly durable substrate enables the use of alternative housing components that are lighter in weight.
In one embodiment illustrated in FIG. 5, a carbon fiber unitary housing 514 in the form of a four or five sided box is used to create a structurally sound, fluid resistant outer enclosure. The housing 514 has an open end to enable insertion of a multilayer core subassembly 502 into the open end of the housing 514, as shown. The multilayer core subassembly 502 may include a metal ground plate, or plane, onto which the sensor panel with attached scintillator, sensor readout electronics, and image data processing circuit boards are mated. After insertion of the multilayer core subassembly 502 into the housing 514, an end cap, or cover, may be mounted onto the open end of the housing 514 to complete the enclosure.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.


A rice pudding formulation which incorporates 2-16% dry weight parboiled medium grain rice which is processed by ultra-high temperature treatment of at least 230xc2x0 F. for a time effective to produce sporecidal activity and to produce a rice pudding product which has a relatively-low level of microbiological activity and which is suitable for refrigerated distribution. The parboiled, medium grain rice is more tolerant to the high temperature and shear conditions of UHT processing. The rice maintains a soft texture for greater than 60 days of refrigerated storage in the finished rice pudding product.

The invention relates to a ready-to-eat rice pudding formulation and method of preparation using ultra-high temperature during processing and packaging in a manner which results in sterility or a relatively-low level of microbiological activity.
Ready-to-eat food products are becoming increasingly more popular. In particular, consumers look for products which are packaged in individual or multiple serving size containers, require minimal preparation time and are extended shelf life, refrigerated products. Further, as consumers have become more health conscious, there is a tendency toward purchasing ready-to-eat food products which are wholesome and have a homecooked taste. Among the commonly purchased types of ready-to-eat food products are desserts, including puddings. One of the more popular puddings because of nutritional value as well as taste is rice pudding. However, rice pudding tends to have a shorter shelf life than other types of ready-to-eat pudding formulations due to the fact that the amylopectin fraction in rice starch causes retrogradation/firming during refrigerated storage.
Aseptically-packaged, ready-to-eat puddings are conventionally prepared by batching and homogenizing the ingredients and then subjecting the resultant pudding formulation to ultra-high temperature (xe2x80x9cUHTxe2x80x9d) processing. Rice pudding formulations are typically manufactured with a long grain rice or a raw milled medium grain rice. Long grain rice survives UHT processing better than raw milled medium grain rice. However, while long grain rice yields intact kernels with acceptable texture immediately after processing, over a relatively short time (e.g., 30 days) in refrigerated storage, the texture of the long grain rice kernels becomes unacceptably firm and mealy. Raw milled medium grain rice sustains more damage than long grain rice during UHT processing, resulting in fewer intact kernels immediately after processing. Rice kernel texture is initially soft and desirable, however, pudding texture tends to be somewhat starchy or pasty due to starch leached from damaged rice kernels. Over time in refrigerated storage, raw milled medium grain rice kernels become firm, but less firm than long grain rice stored under the same conditions. Rather than unacceptable firmness, raw milled medium grain rice kernels in UHT pudding applications develop an unacceptable mealy, grainy texture over time in refrigerated storage.
Conventional rice pudding products, such as Kozy Shack rice pudding, are batch pasteurized rather than UHT processed. In the batch pasteurization process, all ingredients, including rice, milk, sugar, eggs, vanilla and salt are added into batch cooker and heated up to 190xc2x0 F. for over 30 minutes. Then the products are hot filled, vacuum-sealed, and cooled to 45xc2x0 F. The heating time and temperature conditions for batch pasteurization are less severe than for the UHT process and therefor spores survive the batch pasteurization process. Regular milled medium grain rice can keep its integrity well in batch pasteurization process. The overall shelf life ranges from 60-75 days depending on the pack size.
U.S. Pat. No. 4,788,075 to Joseph et al. discloses a method for producing aseptically-packaged puddings. According to the invention, conventional pudding ingredients are homogenized and then subjected to a high-temperature, short-time treatment sufficient to render the formulation commercially sterile and to fully gelatinize the starch contained in the formulation. U.S. Pat. No. 5,238,699 to King et al. discloses a ready-to-eat UHT low/no fat pudding in which calcium-sensitive, thermally-irreversible gelling hydrocolloids such as calcium alginate are utilized as a total or partial replacement for the fat component. U.S. Pat. No. 5,221,549 to Leshik discloses the incorporation of polyphosphate into a UHT low/no fat pudding to reduce the amount of protein aggregation which results from the heat treatment. However, all of these patents fail to disclose a pudding formulation containing rice wherein the rice maintains its integrity and soft texture during extended refrigerated shelf life.
Accordingly, there is a need in the art for a ready-to-eat rice pudding wherein the rice maintains a soft texture throughout storage for at least 60 days of refrigerated storage.
Thus, it is a purpose of the present invention to overcome the disadvantages of the prior art and thereby provide a ready-to-eat rice pudding comprising a pudding formulation wherein the rice component of the rice pudding formulation comprises 2-16% by weight of dry parboiled medium grain rice based on the total rice pudding formula weight.
In accordance with a preferred embodiment of the invention, there is provided a method for preparing a ready-to-eat rice pudding comprising combining water, a source of soluble calcium, a thickening agent, a sweetener and an emulsifier to form a slurry; subjecting the slurry to homogenization; adding a parboiled medium grain rice to the slurry to form a rice and slurry mixture and cooking the rice and slurry mixture at a temperature of at least 230xc2x0 F. for a period of time effective to produce sporecidal activity and to produce a rice pudding product which has a relatively-low level of microbiological activity. The rice pudding product which possesses a low microbial count is suitable for refrigerated distribution and will achieve at least 60 days refrigerated storage. Sporecidal activity for purposes of this disclosure is defined as a heat treatment which is effective to kill spores but may not necessarily kill all spores. The method further provides for cooling the pudding formulation; and packaging the pudding formulation. Other rice pudding formulations which incorporate a protein such as soy may be produced without the incorporation of a source of soluble calcium.
In another preferred embodiment of the invention, a method for preparing a ready to eat rice pudding comprises preparing a pudding formulation comprising 45-75% by weight water, 0.5-25% by weight sweetener, 0-10% by weight milk fat, 1.5-10% by weight non-fat milk solids, 0-10% by weight egg yolk, 0.2-1.5% by weight thickening agent and 0.05-0.5% by weight emulsifier/stabilizer based on total weight of the rice pudding formula. 2-16% by weight of dry parboiled medium grain rice based on the total rice pudding formula is added to form a rice and slurry mixture which is then cooked at a temperature of at least 230xc2x0 F. for a period of time effective to produce sporecidal activity and to produce a rice pudding product which has a relatively-low level of microbiological activity. The resultant pudding is cooled to a temperature of 32-140xc2x0 F. and packaged.
In yet another preferred embodiment of the invention, a ready-to-eat rice pudding having a refrigerated storage life of at least 60 days comprises a pudding formulation comprising water, a source of soluble calcium or protein, a thickening agent, sweetener and an emulsifier and 2-16% by weight of dry parboiled medium grain rice based on the total rice pudding formula weight, the rice pudding being prepared in an ultra high temperature process wherein the rice and pudding formulation are cooked at a temperature of at least 230xc2x0 F. for a period of time effective to produce sporecidal activity and to produce a rice pudding product which has a relatively-low level of microbiological activity.
It is, therefore, an object of the invention to provide a ready-to-eat rice pudding formulation produced in an ultra high temperature process which maintains a soft rice texture throughout storage for at least 60 days of refrigerated storage.
Further objects of the invention will become apparent from the detailed description that follows.
In accordance with the invention, an ultra-high temperature (xe2x80x9cUHTxe2x80x9d), i.e., above 230xc2x0 F., processed and packaged pudding having a rice level of from 2 to 16% (by weight of dry rice based on the total rice pudding formula weight) is prepared using a combination of conventional ready-to-eat pudding ingredients and parboiled medium grain rice. The inventors have found that either instant parboiled or non-instant parboiled medium grain rice exhibits better rice kernel integrity than raw milled medium grain rice in UHT processed pudding applications. The pudding matrix texture is less pasty or starchy than pudding produced with raw milled medium grain rice. Like raw milled medium grain rice, the initial parboiled medium grain rice kernel texture is soft and tender. Over an extended period of time, i.e., 60 days or longer, in refrigerated storage, parboiled medium grain rice kernels remain soft and tender, without developing the graininess and mealiness found in raw milled rice kernels under extended refrigerated storage.
Parboiled rice is defined as rough, whole-kernel rice with the hull remaining, which has been soaked in warm water under pressure, steamed and dried before milling. Parboiled rice differs greatly from raw milled rice and its properties, depending on the type and severity of parboiling. For more specific details on the parboiling process, please see Bhattacharya, K. R., 1985. Parboiling of Rice. Pages 289-342 in: Rice Chemistry and Technology, B. Juliano ed., American Association of Cereal Chem., St. Paul, Minn. which is herein incorporated by reference.
Parboiling forms an amylose complex and produces a more compact arrangement of starch in the kernel. This helps to keep the starch granule intact and reduces amylose leaching during cooking. The parboiled rice possesses a firmer texture that is due in large part to reassociation of gelatinized starch. The inventors have discovered that this firmer rice kernel is more tolerant to the high temperature and shear conditions of UHT processing. The heat treatment during parboiling also disrupts and denatures the protein bodies, which improves grain hardness for better rice stability during UHT processing.
The inventors have also found that instant parboiled medium grain rice will maintain rice grain integrity through UHT processing, however, to a lesser extent than regular parboiled medium grain rice. The instantizing process combines rehydration followed by drying of the parboiled medium grain rice to a stable moisture of about 9.5% which results in a kernel of slightly lower density. The expansion is the result of increased porosity throughout the pre-cooked rice kernels. This increased porosity results in a much greater surface area, allowing the pudding matrix to effectively penetrate into the individual kernels, improving the softening characteristics of each kernel. Thus, instant parboiled medium grain rice does provide an added benefit of maintaining a softer texture over a longer period of time.
The emulsifier level and specific thickening agents used in the pudding formulation preferably are incorporated to maintain a soft rice texture through storage. The emulsifier(s) retards retrogradation of the amylopectin portion of the starch in the rice grains. While the presence of parboiled medium grain rice in a UHT rice pudding will alone retard the rate of firming over time, the combination of parboiled medium grain rice with emulsifiers and specific thickening agents further helps to slow the rate of firming of the rice kernel after processing. The fat, if incorporated in the preferred embodiment, is preferably a liquid shortening such as a vegetable or canola oil, but may be a non-liquid shortening such as butter and animal fats. Any emulsifier that is conventionally used in puddings may be utilized. The preferred emulsifiers include mono and di-glycerides and sodium stearoyl lactylate. One or more emulsifiers or fats, or combinations thereof may be utilized.
The use of thickening agents, e.g., starch, gelatin or carageenan, in the pudding formulation provide suspension of rice in the pudding while not negatively impacting mouthfeel. Suspension of rice in the pudding is critical to the appearance of the pudding and ensures consistent rice delivery to each container. Thickening agents also help to maintain the soft rice texture over time because they help maintain the desired ratio of rice to slurry constant which is critical in keeping the rice kernel adequately hydrated.
Protein aggregation has been found to occur when ready-to-eat rice puddings are processed at temperatures above 230xc2x0 F. This protein aggregation is evidenced by the development of a speckled, translucent appearance within the pudding and a chalky mouthfeel from the pudding. In this invention, a low level of polyphosphates, in particular pyrophosphate and tetrasodium pyrophosphate, is used to minimize and/or control the degree of protein aggregation in ultra-high temperature processing conditions. Incorporating polyphosphates into the ready-to-eat rice pudding formula significantly reduces the aggregate size to prevent unpleasant grainy texture in finished product.
In a preferred method for preparing the pudding product, water is heated to a temperature between 90 and 150xc2x0 F. and any thickening agents are added and thoroughly mixed using a relatively high level of agitation. Milk or milk products (e.g., whole, low fat, skim milk, non-fat dry milk, whole milk powder, or heavy cream, whey, milk protein concentrate) is then added to the liquid mix. Any fatty ingredients (e.g., fats, emulsifiers and/or stabilizers) may then be added to the heated liquid components. Thereafter, the dry ingredients are added to the liquid mix using a relatively high level of agitation. Such agitation may be provided by an induction mixer or the like. Any egg solids and volatile flavor components are added last in order to minimize the denaturization of egg protein and the volatilization of flavors from exposure to heat.
The slurry mixture is then mixed to effect thorough and complete dispersion, such as by homogenization. Typically, the mixture is heated to a temperature between 120 and 130xc2x0 F. and then passed through a mixing apparatus (e.g. a Manton-Gaulin.(trademark) homogenizer or a Bran-Lubbe(trademark) homogenizer) in either a single or multiple-stage at an appropriate pressure. The slurry may be held in an intermediate, agitated hold tank which serves as a buffer against process disruptions; if held, the slurry should be maintained at a temperature below 45xc2x0 F. to retard microbiological growth.
The rice is added to the slurry and mixed to thoroughly disperse the rice in the slurry. The rice addition is typically conducted with some type of rice feeding device, such as a loss-in-weight feeder, whereby the rice is metered into an intermediate mix tank. The rice may be dry or pre-soaked. Pre-soaking is performed using conventional methods such as batch cooking, continuous cooking, steaming or soaking with or without heat in excess water. The disadvantages of utilizing presoaked rice includes an added processing step, and loss of nutrients. Slurry flowrate and rice feedrate into the intermediate mix tank are controlled to maintain the desired rice level, typically about 2-16% by weight of dry rice based on the total rice pudding formula weight.
Cooking may be effected using either direct or indirect heat. Steam injection is typically utilized for applying direct heat. More preferably, the ultra-high temperature processing of the pudding composition is conducted in a scraped-surface heat exchange apparatus so as to best accommodate the increasing viscosity of the mixture during heating. In the ultra-high temperature processing step, the composition is heated to at least 230xc2x0 F. for a time effective to product sporecidal activity and to produce a rice pudding product which has a relatively-low level of microbiological activity and, more preferably, to a temperature range of from about 275xc2x0 F. to about 300xc2x0 F. for 0.6 seconds to 15 seconds in a suitable holding tube, where the composition is held at the desired temperature for the necessary time required to effect cooking and microbial kill. In addition to the UHT process, the rice slurry mix may be held prior to the hold tube at a temperature within the range of 40xc2x0 F. to 300xc2x0 F. for the necessary time required, typically from 0 to 10 minutes to effect rice hydration and provide desired finished rice texture.
Thereafter, the cooked composition is cooled to a temperature suitable for filling into containers that are then sealed. The cooling step is accomplished while the mix is being subjected to shear conditions. Cooling may be accomplished using tubular and/or scraped-surface heat exchangers.
The cooled pudding formulation is then packaged. Where the product container is a plastic material to be sealed with an adhesively-applied foil lid, the product is usually cooled to a product temperature of 32-140xc2x0 F., typically below about 130xc2x0 F., and preferably below 80xc2x0 F. If an aseptic-packaging process is to be implemented, the process will further include steps of sterilizing the containers and lids into which the sterilized pudding is packaged and then filling the container with pudding in a sterile environment. Such known methods as superheated steam, hydrogen peroxide, ultraviolet light, high-intensity light, irradiation, etc., are useful for sterilizing the packaging materials which, in the case of pudding, are typically composed of single-service or multiservice, cup-shaped, plastic containers and flexible lid stock. The lid stock, may be foil-laminated polyester with a heat-sealable coating that can be heat sealed onto the container. The plastic container may be a thermoformed or molded container fabricated from a material such as high-impact polystyrene. The sterilization steps are also desirable to reduce microbial activity even in the event that a true aseptic process in not being sought, such as when the pudding is placed in a refrigerated distribution system and sterility is not required but extended storage life is desirable. The formulations of the invention incorporating parboiled medium grain rice processed in this manner produce a packaged rice pudding that has intact rice particles and soft rice texture over extended refrigerated 35-45xc2x0 F. pudding shelf life.
The puddings of the invention will typically have a composition in accordance with the following formula that represents an unflavored and uncolored pudding mix, where the % weight ranges of all components stated herein is based on the finished weight of the pudding formulation including the rice.
Flavor and color agents and other functional ingredients may be added to the pudding as desired.
The invention is further described but not limited by the following examples.

Refrigerated ready to eat aseptically produced rice pudding


A bypass air injection scheme for a combustor of a gas turbine. Combustor includes a body with an inner liner and a casing enclosing the body with a passageway defined therebetween. A predetermined amount of the compressor discharge air passing through the passageway is extracted through a manifold. A conduit feeds the extracted air into an injection manifold having a plurality of injection tubes for injecting the extracted air into the combustor bypassing the reactor. The injection tubes and the injection manifold are disposed in a substantially common axial plane.

Gas turbine manufacturers are currently involved in research and engineering programs to produce new gas turbines that will operate at high efficiency without producing undesirable air polluting emissions. The primary air polluting emissions usually produced by gas turbines burning conventional hydrocarbon fuels are oxides of nitrogen, carbon monoxide and unburned hydrocarbons.
Catalytic reactors are generally used in gas turbines to control the amount of pollutants as a catalytic reactor burns a fuel and air mixture at lower temperatures, thus reduces pollutants released during combustion. As a catalytic reactor ages, the equivalence ratio (actual fuel/air ratio divided by the stochiometric fuel/air ratio for combustion) of the reactants traveling through the reactor needs to be increased in order to maximize the effectiveness of the reactor. Thus, there is a need to compensate for the degradation of the catalytic reactor.
Accordingly, the present invention is directed to a bypass air injection apparatus and method to compensate for the degradation of a catalytic reactor and to increase combustor efficiency by extracting compressor discharge air prior to its entry into a combustion or reaction zone of the combustor, and re-injecting the extracted compressor discharge air into the combustor bypassing the catalytic reactor using a plurality of injection tubes located substantially in a common radial plane with an injection manifold. Compressor discharge air is received by the combustor in a first combustion chamber through a passageway, preferably an annulus defined between a combustor body with an inner liner and a casing enclosing the body. The first combustion chamber includes a pre-burner stage where fuel is mixed with compressor discharge air for combustion, thus raising the temperature of the hot gases sufficiently to sustain a reaction with the catalyst disposed downstream of the first combustion chamber. Hot gases flowing out of the first combustion chamber pass through a main fuel premixer (MFP) assembly for combustion in a main combustion chamber disposed downstream of the catalyst.
A predetermined amount of compressor discharge air, flowing through the annulus, and prior to reception in the first combustion chamber, is extracted into a manifold. The extraction manifold is disposed adjacent to an array of openings located in the casing enabling compressor discharge air to flow from the annulus into the extraction manifold. A bypass conduit connects the extraction manifold to an injection manifold. The injection manifold lies in communication with a plurality of injection tubes for injecting the extracted air into the combustor body bypassing the catalyst. As noted above, each injection tube and the injection manifold are disposed in a substantially common radial plane. Removable flange covers are provided on the injection manifold in substantial radial alignment with the respective injector tubes affording access to the tubes. The injection tubes are installed from the outside of the injection manifold at circumferentially spaced locations about the casing and the liner through flange covers. A bypass air (i.e., extracted air) path is therefore provided to bridge the backside cooling airflow annulus disposed between the combustor casing and the combustion liner.
In another embodiment, the combustor includes only one combustion chamber. Thus, the combustor is devoid of the catalyst and the MFP assembly. Here, main combustion occurs at the pre-burner stage where a greater amount of fuel is mixed with air in order for combustion to occur.
In one aspect, the present invention provides a combustor for a gas turbine having a combustor body; a casing enclosing the combustor body and defining an annular passageway therebetween for carrying compressor discharge air into the combustor body at one end thereof; a reaction zone within the combustor body for main combustion of fuel and air; a first annular manifold surrounding the casing and arranged to extract a predetermined amount of compressor discharge air from the annular passageway; a second annular manifold surrounding the casing and arranged to receive the extracted air, the second manifold located downstream of the first manifold in a combustion flow direction; a conduit for supplying the extracted air from the first manifold to the second manifold; and a plurality of injection tubes in communication with the second manifold for injecting the extracted air into the combustor body downstream of the reaction zone in the combustion flow direction to quench combustion, the injection tubes and the second manifold being disposed in a substantially common radial plane.
In another aspect, the present invention provides a combustor for a gas turbine including a combustor body with an inner liner; a casing enclosing the body and defining a passageway therebetween for carrying compressor discharge air; a catalytic reactor disposed in the body for controlling pollutants released during combustion; a first manifold for extracting a predetermined amount of compressor discharge air from the passageway; a second manifold for receiving the extracted air and supplying the extracted air to the body at a location bypassing the catalytic reactor; and a plurality of injection tubes in communication with the second manifold for injecting the extracted air into the body, the injection tubes and the second manifold being disposed in a substantially common radial plane.
In another aspect, the present invention provides a gas turbine having a compressor section for pressurizing air; a combustor for receiving the pressurized air; and a turbine section for receiving hot gases of combustion from the combustor, the combustor including a combustor body with an inner liner, a casing enclosing the body and defining a passageway therebetween for carrying compressor discharge air, a reaction zone within the combustor body for combustion of fuel and air, a first manifold surrounding the casing and arranged to exhaust a predetermined amount of compressor discharge air from the passageway, a second manifold surrounding the casing and arranged to receive the extracted air, the second manifold located downstream of the first manifold in a combustion flow direction; a conduit for supplying the extracted air from the first manifold to the second manifold; and a plurality of injection tubes in communication with the second manifold for injecting the extracted air into the combustor body downstream of the reaction zone in the combustion flow direction to quench combustion, the injection tubes and the second manifold are disposed in a substantially common radial plane.
In yet another aspect, the present invention provides a method for quenching combustion by extracting a predetermined amount of compressor discharge air, before the air flows into the reactor, from the passageway into the first manifold; supplying the extracted air from the first manifold to the second manifold via the conduit; injecting the extracted air received by the second manifold into the body at a location along the body bypassing the reactor using an array of injection tubes; and disposing the injection tubes and the second manifold in a substantially common plane.

Bypass air injection method and apparatus for gas turbines


A solar panel may include a first multi-cell thin-film photovoltaic module of a first fabrication type including a transparent support forming a front surface of the panel, a first pair of connection terminals on the transparent support, and first cells of a certain area, being on the transparent support, and being connected in series to the first pair of connection terminals. The solar panel may include a second multi-cell thin-film photovoltaic module of a second fabrication type comprising a support forming a rear surface of the panel, a second pair of connection terminals on the support, and second cells of a certain area, being on the support, and being connected in series to the second pair of connection terminals. The solar panel may further include a pair of panel terminals for connecting the solar panel to an external circuit, the first and second pairs of connection terminals being connected either in series or in parallel, and then connected to the external circuit through the panel terminals, or both connected to a maximum power point tracker and then connected to the external circuit through the panel terminals.

Thin film solar panels are gaining ever more recognition in the field of solar panels because of their relative low cost compared to panels of traditional technology using silicon wafers. Solar panels based on a photovoltaic structure using a semiconductor layer of cadmium telluride (CdTe) deposited on a glass sheet attain conversion costs smaller than $2.00 per watt and are rapidly approaching about $1.00 per watt.
Other thin film technologies of ternary or quaternary chalcogens are the so-called photovoltaic structures CIS (Copper Indium di-Selenide) and CIGS (Copper Indium Gallium di-Selenide) that promise conversion yields above 10% at very competitive costs.
Similar efficiencies values have been obtained using a thin film technology based on hydrogenated amorphous silicon (a-Si:H). Besides the smaller cost of metallurgic silicon as compared to the cost of elements, such as cadmium, indium, tellurium, there is the further advantage of not including toxic materials, such as, for example, cadmium. Thus, they would be more safely disposed of in the environment without using costly processes for recovering substances that cannot be dispersed in the environment, at the end of the working life of panels.
Among the numerous factors that may influence the choice of a thin film technology among the available technologies, it should be considered that among these thin film fabrication technologies of solar panels, there are important differences in functioning at the various wavelengths of the solar spectrum.
A hydrogenated amorphous silicon photovoltaic structure (p-i-n or n-i-p diode) has a relatively large band gap (slightly less than 2 eV) that makes the semiconductor particularly efficient in converting the blue portion of the solar spectrum, but not so in the red portion of the solar spectrum. Moreover, hydrogenated amorphous silicon tends to significantly "trap" carriers (in particular holes), thus keeping the thickness of the intrinsic semiconductor layer (i) (i.e. the absorption-conversion region) of the p-i-n or n-i-p structures within a few hundred nanometers. In addition, hydrogenated amorphous silicon undergoes an "aging" process, generally attributed to hydrogen desorption by structural defects of the material (the D-centers). All these characteristics may lead to the use of hydrogenated amorphous silicon as part of a relatively thin p-i-n or n-i-p structure, which is adapted to absorb blue-green radiation of the solar spectrum.
As far as the absorption exploitation of the red radiation part of the solar spectrum is concerned, it is either neglected for privileging a reduced cost of panels or done by a second tandem photovoltaic structure of a different semiconductor or by realizing stacked multi-junction photovoltaic structures. Semiconductors generally used for a tandem or multi-junction structure associated to a hydrogenated amorphous silicon structure, are microcrystalline silicon, hydrogenated silicon-germanium alloys (a-SiGe:H), ternary chalcogens (for example, CIS) or quaternary chalcogens (for example CIGS). See U.S. Pat. No. 6,368,892. Tandem structures of hydrogenated amorphous silicon and of microcrystalline silicon are known in the industry as micromorphic cells. These as well as other developments based on tandem or multi-junction structures are efficient, but up to now, they have lead to power conversion yields that at the most attain, at module level, 13% (see Martin A. Green, Keith Emery, Yoshihiro Hishikawa and Wilhelm Warta, Prog. Photovolt: Res. Appl. 2008; 16:61-67), i.e. well below the theoretical limit of the single photovoltaic structures combined together.
As it is known to the skilled person, certain characteristics of the thin film technology, with respect to other technologies, may negatively counterbalance certain positive characteristics of otherwise superior thin film technologies.
Micromorphic cells, that are promising from the point of view of cost and reliability, may suffer the drawback of a short-circuit current yield far lower than the theoretical limit. This is due to poor absorption capability of radiation in the red region of the solar spectrum. An increase of thickness of the microcrystalline intrinsic semiconductor material alleviates this problem, but it may imply a significant increase of costs.
By contrast, CIS and CIGS semiconductor structures are efficient even if in thin film form, in the order of 1.0 μm thickness. This is due to the fact that, differently from amorphous and microcrystalline silicon, these materials are direct band gap semiconductors capable of efficiently capturing photons even in very thin films. Up to now, the best results have been obtained with semiconductors, i.e. CIS or CIGS, having a low band gap, even if practical limits due to recombination of carriers in the region of spatial charge of the photovoltaic conversion structure are present.
As for amorphous silicon, even with these chalcogen materials it is possible to adjust the band gap value, for example, by exchanging Ga and In contents in CIGS. However, when increasing the band-gap from 1.0 to about 1.5 eV, a reduction of the power conversion yield by a factor of about 2 is observed. This indicates an intrinsic inefficiency of chalcogen photovoltaic cells in converting the blue portion of the solar spectrum.
An ideal structure appears to be a combination of a CIS, CIGS or CdTe converting structure and an amorphous silicon converting structure. The resulting combined photovoltaic structure efficiently converts both the red portion as well as the blue portion of the solar spectrum. See U.S. Pat. No. 6,368,892. Solar light crosses first an amorphous silicon structure photovoltaic diode that absorbs and converts radiation of wavelength in the blue region of the spectrum while the remaining green-red portion of the spectrum crosses the silicon diode, being only marginally absorbed, and it is efficiently absorbed and converted by an underlying CIS, CIGS or CdTe converting structure made of direct gap semiconductor material of a thickness sufficient to absorb substantially all the radiation reaching it.
Typically, this type of prior art conversion "stack" is monolithic and has the drawback that cells of the two photovoltaic conversion structures of different technology are electrically in series and thus crossed by the same current. This may significantly limit the overall power conversion yield.

Solar panel having monolithic multicell photovoltaic modules of different types


A display device has row driver circuitry (30) providing row address signals and column address circuitry (32) providing pixel drive signals. The row address signals comprise a plurality of voltage levels (V1-V4) to implement a desired drive scheme. The column address circuitry comprises circuitry (70) for generating low voltage representations of at least some of the row address signals. The row address circuitry comprises a conversion circuit (72) for converting the representations into the row address signal levels, at least one of has a high voltage magnitude. The invention provides an architecture which partitions different sections of the row voltage supply circuitry optimally between the row and column drivers. This enables a simplified power supply to be provided which can be made more power efficient.

This invention relates to active matrix display devices, in particular having a pixel configuration using a thin film transistor switching device.
This type of display typically comprises an array of pixels arranged in rows and columns. Each row of pixels shares a row conductor which connects to the gates of the thin film transistors of the pixels in the row. Each column of pixels shares a column conductor, to which pixel drive signals are provided. The signal on the row conductor determines whether the transistor is turned on or off, and when the transistor is turned on, by a high voltage pulse on the row conductor, a signal from the column conductor is allowed to pass on to an area of liquid crystal material, thereby altering the light transmission characteristics of the material. An additional storage capacitor may be provided as part of the pixel configuration to enable a voltage to be maintained on the liquid crystal material even after removal of the row electrode pulse. U.S. Pat. No. 5,130,829, whose contents are incorporated herein by reference, discloses in more detail the construction and driving of examples of such an active matrix display device.
The frame (field) period for active matrix display devices requires a row of pixels to be addressed in a short period of time, and this in turn imposes a requirement on the current driving capabilities of the transistor in order to charge or discharge the liquid crystal material to the desired voltage level. In order to meet these current requirements, the gate voltage supplied to the thin film transistor needs to fluctuate between values separated by approximately 30 volts. For example, the transistor may be turned off by applying a gate voltage of around xe2x88x9210 volts, or even lower, (with respect to the source) whereas a voltage of around 20 volts, or even higher, may be required to bias the transistor sufficiently to provide the required source-drain current to charge or discharge the liquid crystal material sufficiently rapidly.
The requirement for large voltage swings in the row conductors requires the row driver circuitry to be implemented using high voltage components.
The voltages provided on the column conductors typically vary by approximately 10 volts, which represents the difference between the drive signals required to drive the liquid crystal material between white and black states. Various drive schemes have been proposed enabling the voltage swing on the column conductors to be reduced, so that lower voltage components may be used in the column driver circuitry. In the so-called xe2x80x9ccommon electrode drive schemexe2x80x9d, the common electrode, connected to the full liquid crystal material layer, is driven to an oscillating voltage. The so-called xe2x80x9cfour-level drive schemexe2x80x9d uses more complicated row electrode waveforms in order to reduce the voltage swing on the column conductors, using capacitive coupling effects.
Whilst these drive schemes enable lower voltage components to be used for the column driver circuitry, they each result in more complicated row conductor waveforms, in particular having a plurality of voltage levels. This makes the row driver circuitry more complicated, and has conventionally been achieved by using a plurality of voltage supply circuits to generate the different row electrode voltages.
The invention is concerned with the generation of these row voltages.
According to the invention, there is provided a display device comprising an array of liquid crystal pixels, each pixel comprising a thin film transistor switching device and a liquid crystal cell, the array being arranged in rows and columns, wherein each row of pixels shares a row conductor, which connects to the gates of the thin film transistors of the pixels in the row, and wherein each column of pixels shares a column conductor to which pixel drive signals are provided, wherein row driver circuitry provides row address signals for controlling the switching of the transistors of the pixels of the row, and column address circuitry provides the pixel drive signals, wherein the row address signals comprise a plurality of voltage levels, and wherein the column address circuitry comprises circuitry for generating representations of at least some of the row address voltage levels, and wherein the row address circuitry comprises a conversion circuit for converting the representations into the row address levels.
The invention provides a first section of the row signal generating circuitry in the column address circuitry, and a second section in the row driver circuitry. The row driver circuitry is in any case required to switch high voltages on to the row conductors, so must be implemented using high voltage components. The invention thereby provides an architecture which partitions different sections of the row voltage supply circuitry optimally between the row and column drivers. This enables a simplified power supply to be provided which can be made more power efficient.
Preferably the representations comprise relatively low voltage signals (for example of magnitude less than 10V) and the row address levels comprise relatively high voltage signals (for example of magnitude greater than 10V).
The low voltage section generates equivalents of the voltages used in the row driver to address the display. These are the different voltage levels required by the particular addressing scheme being used, together with the common electrode voltage which may also adopt a number of different levels.
The representations, which comprise the equivalents of the voltages used in the row driver, may comprise digital representations or scaled analogue representations. The conversion circuit will then either comprise digital to analogue conversion circuitry or else analogue amplification circuitry. These representation voltages may be corrected for kickback correction, temperature effects and may allow a brightness control.
The representations may be generated only once for each frame period. The regularity with which the voltages must be regenerated depends upon the amount of leakage from the circuitry used.
The simplification of the power supply enables the row address circuitry to be driven by only two power rails. Thus, the digital to analogue converters or amplifiers may be powered from these two rails, avoiding the need in the row driver circuitry for multiple power sources.
The display device may, for example, be used in a mobile telephone.
The invention also provides a column address circuit and a row address circuit, which are adapted to enable the display device architecture to be implemented.
The invention also provides a method of generating row address signals for an active matrix liquid crystal display device, wherein the row address signals comprise a plurality of voltage levels, the method comprising:
in column address circuitry, generating representations of at least some of the row address levels, the representations comprising relatively low voltage signals,
in row driver circuitry, converting the representations into the relatively high voltage row address levels, and forming the row address signals from the row address levels.