A method and apparatus for coating and drying coated substrates without introducing significant surface imperfections while running at higher web speeds than known drying methods. The substrate is preferably coated within the drying enclosure or the coating bead may form a closure at the entrance of the drying enclosure. The substrate is moved through a first drying enclosure along a first axis. The first drying enclosure is substantially isolated from an external environment. A first low velocity, substantially laminar flow field of a drying gas is directed across the front surface of the substrate. The first flow field is generally parallel to the front surface and generally perpendicular to the first axis to minimize the formation of surface imperfections during the evaporation of the coating solvent. The substrate may then be moved to subsequent drying enclosures through transition enclosures that minimize surface imperfections due to high velocity interaction between the adjacent drying enclosures. In embodiments where the first axis is in an inclined configuration with respect to horizontal, louvers may be utilized for directing solvent evolving from the substrate to minimize surface imperfections due to solvent cascade.

The production of high quality articles, particularly photographic, photothermographic, and thermographic articles, consists of applying a thin film of coating solution onto a continuously moving substrate. Thin films can be applied using a variety of techniques including: dip coating, forward or reverse roll coating, wire-wound coating, blade coating, slot coating, slide coating, and curtain coating (see for example L. E. Scriven; W. J. Suszynski; Chem. Eng. Prog. 1990, September, p. 24). Coatings can be applied as single layers or as two or more superposed layers. While it is usually most convenient for the substrate to be in the form of a continuous substrate, it can also be in the form of a succession of discrete sheets.
The initial coating is either a mixture of solvent and solids or a solution and must be dried to obtain the final dried article. While the cost of a coating process is determined by the coating technique, the cost of a drying process is often proportional to the desired line speed (see E. D. Cohen; E. J. Lightfoot; E. B. Gutoff; Chem. Eng. Prog. 1990, September, p. 30). The line speed is limited by the capabilities of the oven. To reduce costs, it is desirable that the removal of solvent from the coating be as efficient as possible. This is generally accomplished by transferring heat to the coated article as efficiently as possible. This is often accomplished by increasing the velocity of the drying gas at the coating surface, thereby increasing heat transfer and solvent evaporation and thus drying the coating more quickly. The resulting turbulent air, however, increases the tendency for defect formation.
The process of applying a coating to and drying that coating on a substrate can inherently create defects, including Benard cells, orange peel, and mottle. Benard cells are defects arising from circulatory motion within the coating after it has been applied (see C. M. Hanson; P. E. Pierce; Cellular Convection in Polymer Coatings--An Assessment, 12 Ind. Eng. Chem. Prod. Res. Develop. 1973, p. 67).
Orange peel is related to Benard cells. Orange peel is most common in liquid coatings which have a high viscosity to solids ratio. This is due to the tendency of such systems to "freeze in" the topography associated with Benard cells upon loss of relatively small amounts of solvent. The topography can be observed as a small scale pattern of fine spots like the surface of an orange peel. The scale of the pattern is on the order of millimeters and smaller.
Mottle is an irregular pattern or non-uniform density defect that appears blotchy when viewed. This blotchiness can be gross or subtle. The pattern may even take on an orientation in one direction. The scale can be quite small or quite large and may be on the order of centimeters. Blotches may appear to be different colors or shades of color. In black-and-white imaging materials, blotches are generally shades of gray and may not be apparent in unprocessed articles but become apparent upon development. Mottle is usually caused by air movement over the coating before it enters the dryer, as it enters the dryer, or in the dryer (see for example, "Modern Coating and Drying Technology," Eds. E. D. Cohen, E. B. Gutoff, VCH Publishers, NY, 1992; p. 288).
Mottle is a problem that is encountered under a wide variety of conditions. For example, mottle is frequently encountered when coatings comprising solutions of a polymeric resin in an organic solvent are coated onto webs or sheets of synthetic organic polymer substrates. Mottle is an especially severe problem when the coating solution contains a volatile organic solvent but can also occur to a significant extent even with aqueous coating compositions or with coating compositions using an organic solvent of low volatility. Mottle is an undesirable defect because it detracts from the appearance of the finished product. In some instances, such as in imaging articles, it is further undesirable because it adversely affects the functioning of the coated article.
Substrates that have been coated are often dried using a drying oven which contains a drying gas. The drying gas, usually air, is heated to a suitable elevated temperature and brought into contact with the coating in order to bring about evaporation of the solvent. The drying gas can be introduced into the drying oven in a variety of ways. Typically, the drying gas is directed in a manner which distributes it uniformly over the surface of the coating under carefully controlled conditions that are designed to result in a minimum amount of disturbance of the coated layer. The spent drying gas, that is, drying gas which has become laden with solvent vapor evaporated from the coating, is continuously discharged from the dryer.
Many industrial dryers use a number of individually isolated zones to allow for flexibility in drying characteristics along the drying path. For example, U.S. Pat. No. 5,060,396 describes a zoned cylindrical dryer for removing solvents from a traveling substrate. The multiple drying zones are physically separated, and each drying zone may operate at a different temperature and pressure. Multiple drying zones are desirable because they permit the use of successively lower solvent vapor composition. German Pat. No. DD 236,186 describes the control of humidity and temperature of each drying zone to effect maximum drying at minimum cost. Soviet Pat. No. SU 620,766 describes a multistage timber dryer with staged temperature increases that reduce the stress within the timber.
Usually, when multiple zones are present in an oven, they are isolated from one another. The coated substrate is transferred between the zones through a slot. In order to minimize the air and heat flow between zones and to be able to effectively control the drying conditions in each zone, this slot typically has as a cross-section on the order of about 2.54 cm to about 10.16 cm so as to allow the substrate to pass between zones. However, the adjacent zones are in communication with one another through the slot and thus there is typically a pressure difference between zones. Air flows from one zone to another; and since the dimensions of the slot are small, the air gas velocity is high. Therefore the slots between ovens tend to be sources for mottle defects.
U.S. Pat. No. 4,365,423 discloses an apparatus and method for drying to reduce mottle. FIG. 1 shows an embodiment of this invention. The drying apparatus 2A uses a foraminous shield 4A to protect the liquid coating 6A from air disturbances. The foraminous shield 4A is described to be a screen or perforated plate that sets up a "quiescent" zone above the substrate promoting uniform heat and mass transfer conditions. The shield 4A is also noted to restrict the extent to which spent drying gas, which is impinged toward the liquid coating 6A, comes in contact with the surface of the coating, thereby reducing the inherent turbulent airflow in the oven that tends to cause mottle. This method is reported to be especially advantageous in drying photographic materials, particularly those comprising one or more layers formed from coating compositions that contain volatile organic solvents. This apparatus and method has the limitation that it slows the rate of drying.
U.S. Pat. No. 4,999,927 discloses another apparatus and method for drying a liquid layer that has been applied to a carrier material moving through a drying zone and which contains both vaporizable solvent components and non-vaporizable components. FIG. 2 illustrates this apparatus 2B and method. Drying gas flows in the direction of the carrier material 8B and is accelerated within the drying zone in the direction of flow. In this manner, laminar flow of the boundary layer of the drying gas adjacent to the liquid layer on the carrier material is maintained to reduce mottle.
Examples of two other known drying apparatuses and methods are shown in FIGS. 3 and 4. FIG. 3 schematically shows a known drying apparatus 2C in which air flows (see arrows) from one end of an enclosure to the other end. The airflow is shown in FIG. 3 as being parallel and counter to the direction of travel of the coated substrate (i.e., counter-current). Parallel concurrent airflow is also known.
FIG. 4 schematically shows a known drying apparatus 2D which involves the creation of impingement airflow (see arrows), that is more perpendicular to the plane of the substrate 8D. The impinging air also acts as a means for floating or supporting the substrate through the oven.
U.S. Pat. No. 4,051,278 describes a method for reducing mottle caused by solvent evaporation in the coating zone. Coating a substrate with reduced mottle, such as coating a composition comprising a film-forming material in an evaporable liquid vehicle onto a flexible web or synthetic organic polymer, is achieved by maintaining at least two of the following at a temperature substantially equivalent to the equilibrium surface temperature of the coated layer at the coating zone: (1) the temperature of the atmosphere at the location of coating; (2) the temperature of the coating composition at the location of coating; and (3) the temperature of the substrate at the coating zone. The equilibrium surface temperature is defined as the temperature assumed by the surface of a layer of the coating composition under steady state conditions of heat transfer following evaporative cooling of the layer at the coating zone. After coating, drying of the coated layer is carried out by conventional techniques. This invention includes methods of drying while preventing mottle formation by controlling temperature (i.e., by cooling) at the coating zone and does not address temperature control or mottle formation within the drying oven. Furthermore, this method would be useful only for coatings that cool significantly due to evaporative cooling which subsequently causes mottle.
U.S. Pat. No. 4,872,270 describes a method of drying latex paint containing water and one or more high boiling organic solvents coated onto a carrier film. The process yields a dried paint layer free of blisters and bubble defects. The coated film is passed continuously through a series of at least three drying stages in contact with warm, moderately humid air and more than half of the heat required for evaporation is supplied to the underside of the film. Drying conditions in at least each of the first three stages are controlled to maintain a film temperature profile which causes the water to evaporate at a moderate rate but more rapidly than the organic solvents, thus achieving coalescence of the paint and avoiding the trapping of liquids in a surface-hardened paint layer. Bubble formation is reportedly eliminated by controlling the vapor pressure of the volatile solvent within the film. The formation of mottle occurs due to a different mechanism than blisters and requires different methods for control and elimination.
U.S. Pat. No. 4,894,927 describes a process for drying a moving web coated with a coating composition containing a flammable organic solvent. The web is passed through a closed-type oven filled with an inert gas and planer heaters on top and bottom of the web. The coating surface is reported to be barely affected by movement of the inert drying gases due to the small amounts of gas required. No discussion of the criticality of the gas flow system or of the need to prevent mottle is given.
U.S. Pat. No. 5,077,912 describes a process for drying a continuously traveling web coated with a coating composition containing an organic solvent. The coating is first dried using hot air until the coating is set-to-touch. It is sufficient that the drying conditions, such as temperature and hot air velocity, are adjusted so as to obtain the set-to-touch condition. Set-to-touch corresponds to a viscosity of 10.sup.8 to 10.sup.10 poise. Residual solvent is then removed using a heated roll. This method is said to reduce drying defects, decrease drying time, and reduce oven size. No discussion on the construction of the oven, methods of drying, or the criticality of the gas flow system and path is given.
U.S. Pat. No. 5,147,690 describes a process and apparatus for drying a liquid film on a substrate which includes a lower gas or air supply system and an upper gas or air supply system. Heated gas on the underside of the substrate forms a carrying cushion for the substrate and at the same time supplies drying energy to the substrate. The exhaust air is carried away through return channels. Slots for the gas supply and return are arranged alternately in the lower gas system. The upper gas or air supply system has a greater width than the lower gas or air supply system. In the upper gas or air supply system, the supply air or gas is diverted by baffles onto the substrate and returned over the substrate web as return air or gas. The upper gas or air supply system is subdivided into sections for the supply air and exhaust air, each section includes two filter plates of porous material. This arrangement, however, still impinges air on the coated web, which can lead to uncontrolled turbulent air flow and mottle.
U. S. Pat. No. 5,433,973 discloses a method of coating a magnetic recording media onto a substrate, wherein the coating is substantially free of Benard cells. The method comprises the steps of: (a) providing a dispersion comprising a polymeric binder, a pigment, and a solvent; (b) coating the dispersion onto the surface of a substrate; (c) drying the dispersion; (d) calculating values comprising .mu., .beta., and d representing the viscosity, temperature gradient, and wet caliper of the dispersion respectively; and (e) during the course of carrying out steps (a), (b), and (c), maintaining the ratio ##EQU1## below a threshold value sufficient to substantially prevent the formation of Benard Cells in the magnetic recording media coating. No discussion of the interior of the drying oven and arrangement of air inlets and exhausts is given.
A number of methods involve the control of the drying gas within the oven. For example, U.S. Pat. No. 5,001,845 describes a control system for an industrial dryer used to remove a flammable solvent or vapors from a traveling web of material. Sensors within each zone measure the oxygen content of the pressurized atmosphere. If the oxygen content exceeds a given limit, an inert gas is added. At the same time, the pressure is maintained within the oven body by releasing excess gas to the atmosphere.
U.S. Pat. No. 5,136,790 describes a method and apparatus for drying a continuously moving web carrying a liquid, wherein the web is passed through a dryer in which the web is exposed to a recirculating flow of heated drying gas. Exhaust gas is diverted and discharged from the recirculating gas flow at a gas velocity which is variable between maximum and minimum levels, and makeup gas is added to the recirculating gas flow at a gas velocity which is also variable between maximum and minimum levels. A process variable is sensed and compared to a selected set point. A first of the aforesaid flow rates is adjusted to maintain the process variable at the selected set point, and a second of the aforesaid flow rates is adjusted in response to adjustments to the first drying gas velocity in order to insure that the first drying gas velocity remains between its maximum and minimum levels. No discussion of the interior of the drying oven and arrangement of air inlets and exhausts is given.
Soviet Pat. No. SU 1,276,889 describes a method for controlling drying gas by controlling the air gas velocity within the oven. In this method, fan speed in one zone is adjusted, controlling the air flow rate, in order to maintain the web temperature at the outlet to a specified temperature. This approach is limited in that increasing the air gas velocity in order to meet a drying specification can lead to mottle.
The physical state of the drying web can also be used to control the drying ovens. For example, in Soviet Pat. No. SU 1,276,889, noted above, the temperature of the web at the outlet of the oven was used to set the air flow rate.
U.S. Pat. No. 5,010,659 describes an infrared drying system for monitoring the temperature, moisture content, or other physical property at particular zone positions along the width of a traveling web, and utilizing a computer control system to energize and control for finite time periods a plurality of infrared lamps for equalizing physical property and drying the web. The infrared drying system is particularly useful in the graphic arts industry, the coating industry and the paper industry, as well as any other applications requiring physical property profiling and drying of the width of a traveling web of material. No discussion of the interior of the drying oven and arrangement of air inlets and exhausts is given.
U.S. Pat. No. 4,634,840 describes a method for controlling the drying temperature in an oven used for heat-treating thermoplastic sheets and films. A broad and continuous sheet or film is uniformly heated in a highly precise manner and with a specific heat profile by using a plurality of radiation heating furnaces, wherein in the interior of each radiation heating furnace, a plurality of rows of heaters are arranged rectangularly to the direction of delivery of the sheet or film to be heated. A thermometer for measuring the temperature of the sheet or film is arranged in the vicinity of an outlet for the sheet or film outside each radiation heating furnace. Outputs of heaters arranged within the radiation heating furnaces located just before the respective thermometers are controlled based on the temperatures detected by the respective thermometers by using a computer.
Two other patents address drying problems, but fail to address the problem of mottle. U.S. Pat. No. 3,849,904 describes the use of a mechanical restriction of air flow at the edge of a web. Adjustable edge deckles are noted as forming a seal with the underside of a fabric allowing for different heating conditions to occur at the edge. This allows the edge of the fabric to be cooled while the remainder of the fabric is heated. This approach, however, is not advantageous when a polymer substrate is used. Possible scratching of the polymer substrate can generate small particulates which can be deposited on the coating. U.S. Pat. No. 3,494,048 describes the use of mechanical means to divert air flow at the edge of the web. Baffles are noted as deflecting air and preventing air from penetrating behind paper in an ink dryer and from lifting the paper from a drum. Keeping the paper on the drum prevents the drying ink from being smeared.
A need exists for a drying method and apparatus which minimizes or eliminates uncontrolled airflow that can lead to mottle, minimizes initial drying rates that can lead to orange peel and permits higher line speeds. There is also a need for a drying apparatus that minimizes mottle caused by natural convection of the evaporated solvent from the coating on an inclined web path. Additionally, there is a need for a drying method and apparatus that can isolate a series of drying zones.

Apparatus and method for drying a coating on a substrate

Minnesota Mining and Manufacturing Company


The present invention provides an epoxy resin composition including an epoxy resin represented by the following formula (1) and an epoxy resin represented by the following formula (2):

The cured products of epoxy resin compositions each including an epoxy resin and a curing agent are used in various applications including, for example, electronic parts of semiconductor packages and semiconductor chips. For example, Patent Literature 1 discloses a method for producing an epoxy resin having a polyether group in which the number of the repeating units formed of an alkyleneoxy group is less than three. Patent Literature 2 discloses a method for producing an epoxy resin having a polyether group in which the number of the repeating units formed of an alkyleneoxy group is less than six.

Epoxy resin composition, epoxy resin, and cured product


The invention relates to magnesium-based alloys and, more specifically, to a magnesium alloy composition and methods of producing the same. The alloys have improved mechanical properties in that creep ratios are decreased. The magnesium-based alloys comprise aluminium, zinc, manganese and silicon. A method for producing said alloy consists of loading the alloying components, pouring the molten magnesium, introducing a titanium-containing fusion cake with a flux agent and continuously agitating. The alloy is then soaked and cast.

1. Field of the Invention
This invention relates generally to magnesium-based alloys and more specifically to magnesium alloy compositions and methods of producing them that are for use in the automotive industry.
2. Background Art
There are various alloys developed for special applications including, for example, die casting of automotive components. Among these alloys magnesium-aluminium alloys can be designated as cost-effective and widely used for manufacture of automotive parts, e.g. AM50A alloy (where AM means aluminium and manganese are in the composition of the alloy) containing approx. 5 to 6 wt. % aluminium and manganese traces, and magnesium-aluminium-zinc alloys, e.g. AZ91D (where AZ means aluminium and zinc are in the composition of the alloy) containing approx. 9 wt. % aluminium and 1 wt. % zinc.
The disadvantage of these alloys is their low strength and poor creep resistance at elevated operating temperatures. As a result, the above mentioned magnesium alloys are less suitable for motor engines where some components such as transmission cases are exposed to temperatures up to 150° C. Poor creep resistance of these components can lead to a decrease in fastener clamp load in bolted joints and, hence, to oil leakage.
Known in the present state of art is a magnesium-based alloy (Inventors' certificate No. 442225 issued in Invention Bulletin 33, 1974) containing aluminium, zinc, manganese, and silicon as alloying components in the following amounts:    Aluminium—6–15 wt. %    Zinc—0.3–3.0 wt. %    Manganese—0.1–0.5 wt. %    Silicon—0.6–2.5 wt. %    Magnesium—balance.
The disadvantages of this alloy are its low ductility, high hot shortness, and insufficient strength of the alloy which keeps this alloy from automotive applications.
Known presently is another magnesium die cast alloy ("Magnesium alloys" in Collected works of Baikov Institute for Metallurgy edited by Nauka Publishing House, 1978, p.140–144) which comprises aluminium, zinc, manganese, and silicon as alloying components in the following amounts:    Aluminium—3.5–5.0 wt. %    Zinc—under 0.12 wt. %    Manganese—0.20–0.50 wt. %    Silicon—0.5–1.5 wt. %    Copper—under 0.06            Nickel—0.03 wt. %
The drawback of this alloy is that the quantitative composition of the alloy selected provides poor mechanical properties, in particular, the alloy having a small solidification range is characterised with advanced susceptibility to cracking in case of hindered contraction and bad castability.
A well-known German standard EN 1753-1997 is taken as the closest prior art by its qualitative and quantitative composition and discloses the methods of manufacture of EN MB MgAl2Si and EN MB MgAl4Si alloys. The qualitative analysis of the alloys is the following, in wt. %:    EN MB MgAl2Si:    Al—1.9–2.5    Mn—min 0.2    Zn—0.15–0.25    Si—0.7–1.2EN MB MgAl4Si (AS41):    Al—3.7–4.8    Mn—0.35–0.6    Zn—max 0.10    Si—0.6–1.4
The alloys of the above quantitative and qualitative compositions demonstrate better mechanical properties. However, at 150–250° C. these alloys have high creep that keeps these alloys from machine-building applications. Presently known is the method (PCT Patent No. 94/09168) for making a magnesium-based alloy that provides for alloying components in a molten state being introduced into molten magnesium. Primary magnesium and alloying components are therefor heated and melted in separate crucibles.
A disadvantage of this method is the need to pre-melt manganese and other alloying elements (at the melting temperature of 1250° C.) that complicates alloy production and process instrumentation.
There are some other methods known (B. I. Bondarev "Melting and Casting of Wrought Magnesium Alloys" edited by Metallurgy Publishing House, Moscow, Russia 1973, pp 119–122) to introduce alloying components using a master alloy, e.g. a magnesium-manganese master alloy (at the alloying temperature of 740–760° C.).
This method is disadvantageous because the alloying temperature should be kept high. This leads to extremely high electric power consumption for metal heating and significant melting loss.
Also known is another method of producing a magnesium-aluminium-zinc-manganese alloy (I. P. Vyatkin, V. A. Kechin, S. V. Mushkov in "Primary magnesium refining and melting" edited by Metallurgy Publishing House, Moscow, Russia 1974, pp. 54–56, pp. 82–93) which is taken as an analogue-prototype. This method stipulates various ways for feeding molten magnesium and alloying components such as aluminium, zinc, and manganese. One of these approaches includes simultaneous charging of solid aluminium and zinc into a crucible, then heating above 100° C., pouring in molten primary magnesium and again heating up to 700–710° C. and introducing titanium-containing fusion cake together and manganese metal under continuous agitation.
The main shortcoming of the method is in considerable loss of alloying components, resulting in lower recovery of alloying components in magnesium and preventing from producing alloys with specified mechanical properties. Furthermore, this increases the cost of the alloy.

Magnesium-based alloy and method for the production thereof

Joint Stock Company “AVISMA-titanium-magnesium works”


A decoupling capacitor includes a fixed resistance in series with the capacitor, the resistance formed by contacts connecting a polysilicon layer to metal and a diffusion layer to metal; the contacts being of location and quantity sufficient for limiting defect current while allowing the capacitor to function at high frequency. N pairs of contacts in at least two sets of contacts are separated by a distance K sufficient to achieve a leakage limiting resistance of R and a bandwidth limiting resistance of R/2.

1. Technical Field of the Invention
This invention relates to electronic circuit design. More specifically, it relates to placement of voltage and ground contacts in a decoupling capacitor for application specific integrated circuit (ASIC) libraries.
2. Background Art
Current CMOS technology integrated circuits (ICs) contain millions of logic gates switching at very high speeds. Decoupling capacitors are required across the power supply busses VDD and GND to reduce the switching noise which can affect the timing of the individual gates on the chip. As CMOS technologies have progressed, higher circuit speeds are realized and increased wire resistance results from smaller metal cross sections in the power bussing. Adding larger areas of decoupling capacitors to an IC requires large areas of polysilicon which increase the probability that a single processing defect could cause a short from VDD to Ground in the capacitor area. This would render the entire chip useless and reduce the wafer yield thereby increasing the cost of the functional chips.
Heretofore a first solution has been to add a gating device in series to the decoupling capacitor for two reasons: first, to turn off the leakage path from VDD to Ground for testing purposes; and, second, to gate off the defective device to save the chip should a defect cause a power supply short in the capacitor area.
There are a few drawbacks to the above solution that make implementation difficult, and the usefulness of this approach is bandwidth limited for high speed applications. The gating device is usually an NFET (NFET are typically smaller than PFET for the same lgs current). This NFET is sized such that there is a low impedance from gate-to-source. The low impedance in series with the capacitor is required to reduce the RC which limits the bandwidth of the network. This low impedance NFET must be very large physically which may take up as much area as the capacitor itself. The large NFET must also have a large gate area which increases the gate capacitance, which in turn forces the chip designer to use a large driver to drive the gate. Another draw back is the fact that the decoupling capacitor has an input pin. Ideally a decoupling capacitor is a passive device without any wireable pins. When thousands of decoupling capacitors are required on a chip, thousands of gates must be wired and driven by circuit buffers from one or more primary input pins. The wiring and buffering is further complicated when it is desirable to isolate and degate the defective capacitor. A substantial amount of circuit area and wireability is lost when implementing such schemes.
A second solution has involved the addition of an integrated circuit resistor, resulting in a capacitor with a large RC. This solution also results in a relatively large area requirement for the resistor.
It is understood that coupled noise and leakage are driving down circuit yields. This is cause by highly resistive and closely spaced circuit wiring (coupled noise) and extremely thin gate oxides causing current leakage. A large RC means that the capacitor can not function as a decoupling capacitor, or has limited affect as a decoupling capacitor. On the other hand, a low series resistance capacitor allows more leakage current. Consequently, there is a need in the art for a decoupling capacitor the limits leakage current by design without adding a resistor in series.
Such decoupling capacitors as gated capacitors, capacitors with series resistance of a chosen resistance, and a series of capacitors pfet/nfet decoupler with NFET drain tied to PFET gate and Pfet drain tied to NFET gate which have previously done well at high-frequency decoupling have not performed successfully in newer technologies due to their large series resistance Referring to FIGS. 1 and 2, the first solution described above uses a gating transistor TN2 102 that can be turned on or off by switching the input GATE 104 high or low. When turned off, such as during test, gate 102 is open. The leakage current through the capacitor CAP1 106 from VDD 110 to GND 108 is limited by the size of gating transistor TN2 102 when TN2 is on. This approach requires a very large device TN2 102, a buffer TN1 112 and TP1 114 and an input pin 100 for gate 104, all added to the layout of capacitor CAP1 106.
Referring to FIG. 3, the second solution described above uses an integrated circuit resistor R1 116 added in series to capacitor CAP1 106. Referring to FIG. 4, this solution requires the area overhead of the integrated circuit resistor 116, which reduces the layout density of decoupling capacitor CAP1 106 considerably.

Controlled leakage CMOS decoupling capacitor for application specific integrated circuit libraries

International Business Machines Corporation


The present disclosure relates to a bootstrapped switch circuit, a track-and-hold circuit, an analog-to-digital converter, a method for operating a track-and-hold circuit, a base station, and a mobile station. The bootstrapped switch circuit comprises an output for an output signal, a first input, a switching element configured to couple the output with a signal from the first input, a bootstrapper capacitor configured to drive the switching element, and a second input coupled to the bootstrapper capacitor.

In analog-to-digital conversion (ADC) circuits an analog input signal travels across packages, interconnections, blocks, transmission lines from a transmitter to a receiver and a high level of signal integrity should be guaranteed, if correct data should be captured. Every conductor has a frequency-dependent resistance (R)/conductance (G), capacitance (C), and/or inductance (L). Thus, at a high-enough frequency, a wire is no longer a wire but a distributed, frequency-dependent parasitic element with an impedance profile that can cause distortion when connected to a dynamic circuit, e.g. a front-end track-and-hold (T/H) circuit at the input of an ADC.
A multi-GHz input signal is not contained in the conductor itself but is, instead, carried in the local electric and magnetic fields around the conductors. Furthermore, an input signal, which comprises useful info to be postprocessed, can be affected by other signals, therefore R-L-C components of all the conductor structures have vital roles of guaranteeing proper signal integrity along the path toward a receiver.

Bootstrapped switch circuit, a track-and-hold circuit, an analog-to-digital converter, a method for operating a track-and-hold circuit, a base station and a mobile device


A printed circuit board or card includes a pair of ball grid array packages connected one over the other on opposite sides of the board or card. The packages may connect through feed-through vias so that board space on the underside of the board, populated by feed-through vias, can be utilized to provide additional functionality. In one implementation, GTL resistive terminations and decoupling capacitors may be included in the ball grid array package on the underside of the board or card.

This invention relates generally to techniques for providing electrical components on printed circuit boards or cards.
In a wide variety of electronic devices, space is often at a premium in order achieve small device size. This is particularly true in a variety of computer applications and most particularly true in connection with portable computers.
The demands for available board space has increased with the introduction of the Pentium.RTM. II brand processor from Intel Corporation. This processor uses Gunning transceiver logic ("GTL"), which requires parallel resistive terminations for all GTL signals. The number of GTL signals between the processor and bridge can be in the range of 150, each of which must be connected to a parallel pull up resistive termination. Decoupling capacitors are typically utilized to provide high frequency capacitive decoupling in computer systems. From 30 to 40 decoupling capacitors may be needed in a portable computer using GTL. Thus, the demands for limited PCB or card space are strained even further by the additional device requirements brought on in recent vintage processors.
Ball grid array ("BGA") packages have become increasingly popular for a large variety of applications Fundamental limitations on wire bonding technology and pad pitch have made some existing industry standard packages, such as plastic quad flat pack ("PQFP") packages, technology roadblocks when the input/output pin count must exceed 250 to 300. In addition, BGA packages can have internal ground and power planes for high frequency operation. These internal planes provide impedance control, limiting the effective inductance seen by the silicon device. This may increase the useable operating frequencies of the silicon device due to the reduction of package related noise and cross-talk.
While there are a wide variety of options available in the general field of BGA's, there are two well known BGA packages. One BGA package uses an over molded pad array carrier ("OMPAC") while the other uses a substrate material that is ceramic ("CBGA"). Generally, BGA packages include a die carrier and a plurality of solder balls or bumps beneath the die carrier which connect to contacts formed on a board or card. These contacts may communicate via metal lines with vias which extend through the board. The portion of the board on the underside of a BGA package is generally too populated with via holes to provide useful space for additional devices.


A wind tunnel for measuring the aerodynamics of a vehicle may comprise a test section. Air moving through the test section may be collected in a plurality of individual ducts, each with a fan for moving the air through the test section and ducts. The vehicle of vehicle wheels may be supported at an incline.

Generally speaking, a wind tunnel used to test the aerodynamics of a vehicle includes a housing within which a vehicle to be tested is positioned. An air flow generator or mover such as a fan or blower is used to create an air stream that is directed through a contraction cone and a test section within which the vehicle is positioned. Air typically exits from the wind tunnel through a diffuser. In one known approach, six extremely large fans were positioned in a single common duct downstream of the diffuser for moving air through the test section. This common duct was connected to a single additional downstream diffuser. Wind tunnels may be of an open circuit design in which atmospheric design where air is drawn into the contraction cone and discharged from the diffuser back to atmosphere. Alternatively, wind tunnels may be designed to recirculate air in a loop or return flow configuration. A wind tunnel also includes instrumentation for measuring the desired information, such as the wind drag created by a vehicle.
It is common practice to include the entire vehicle in a wind tunnel during a test. In the case of tractor trailer combinations, one common approach is to include either the tractor alone or the entire tractor and towed trailer or shortened mock towed trailer with or without wheels in the wind tunnel. In this latter case, the wind tunnel must be large enough to receive the entire tractor trailer combination.
A need exists for a new and improved wind tunnel and associated methods for measuring the aerodynamics of vehicles, such as, but not limited to, tractors of the type which tow trailers.

Vehicle wind tunnel method and apparatus


A display apparatus includes a display panel; and a data driver configured to output drive voltages from a plurality of output nodes to drive the display panel. The data driver includes a plurality of output amplifiers, each of which is configured to receive a gradation voltage corresponding to a pixel data and to output the drive voltage in response to the gradation voltage; and a driver-side demultiplexer configured to connect the plurality of output amplifiers to selection output nodes selected from among the plurality of output nodes. The display panel includes a plurality of data lines; and a panel-side demultiplexer configured to connect selection data lines selected from among the plurality of data lines with the plurality of output nodes.

1. Field of the Invention
The present invention relates to a display apparatus, and more particularly, to a display apparatus in which data lines of a display panel is driven in a time divisional manner.
2. Description of Related Art
Typically, output amplifiers are integrated in a data driver IC for driving data lines in a liquid crystal display panel and other display panels. This is because load of the data line such as parasitic capacitance, wiring resistance and on-resistance of TFT is large. The output amplifier is necessary to quickly drive the data line having the large load to a desirable voltage.
One problem lies in the point that when the number of data lines is increased, the number of output amplifiers is also required to be increased. In the display panel in recent years, the number of pixels is increased more and more. Thus, the number of data lines is also increased, so that the number of output amplifiers provided to drive the data lines tends to be increased. However, the increase in the number of output amplifiers causes the following problems. The first problem lies in the increase in the chip area of the data driver IC when the number of output amplifiers is increased. The increase in the chip area of the data driver IC is not preferable because this involves the increase in cost of the data driver IC. The second problem lies in the increase in the steady-state consumed power of the data driver IC. Since a steady-state current flows through the output amplifier according to a power supply voltage, the output amplifier consumes a certain power in a steady-state state. Thus, the increase in the number of output amplifiers causes the increase in the consumed power as the entire data driver IC, and this is not especially preferable in case that a display apparatus is used in a field which requests the small consumed power such as a mobile terminal.
One measure to cope with this problem is to employ a time divisional driving method. The time divisional driving method is a technique that sequentially selects the data line to be driven with the output amplifier by a demultiplexer. In the time divisional driving method, one output amplifier is used to drive data lines. Thus, the number of output amplifiers integrated in the data driver can be reduced.
A hardware configuration for attaining the time divisional driving method is mainly divided into two kinds. In one kind of hardware configuration, demultiplexers (switch) are integrated in the display panel to select the data line, as disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 11-327518) and Japanese Laid Open Patent Application (JP-P2005-43418A). In the other kind of hardware configuration, switches are integrated in the data driver IC to select the data line, as disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 5-173506), and Japanese Laid Open Patent Applications (JP-P2002-318566A and JP-P2006-154808A).
FIG. 1 is a conceptual diagram showing the configuration of a liquid crystal display apparatus in which a demultiplexer is integrated in a display panel to select data lines. In FIG. 1, a liquid crystal display apparatus 100 contains a liquid crystal display panel 101. Scanning lines G, data lines D and pixels 103 are integrated in an effective display region 102 of the liquid crystal display panel 101, i.e., a region that is actually used to display an image in the liquid crystal display panel 101. The scanning lines G extend in an x-axis direction, and the data lines D extend in a y-axis direction. The pixels 103 are provided at intersections of the scanning lines G and the data lines D.
A circuit group for driving the pixels 103 is provided around an effective display region 102. Specifically, a scanning line driver circuit 104 and a demultiplexer 105 are integrated in the liquid crystal display panel 101. Moreover, a data driver IC 106 is connected in a flip-flop manner to the liquid crystal display panel 101. Attention should be paid to the description of the liquid crystal display apparatus 100 in FIG. 1, in which a COG (Chip on Glass) technique is employed to mount the data driver IC 106. The demultiplexer 105 is configured by switches 105a provided between the data lines D and output nodes of the data driver IC 106. The liquid crystal display apparatus 100 in FIG. 1 is configured in such a manner that the 6 data lines D are selectively connected to the output node of one data driver IC 106. When the pixel 103 is driven, the 6 data lines D are sequentially selected by the demultiplexer 105, and a drive voltage is supplied from the output node of the data driver IC 106 through the selected data line D to the desirable pixel 103.
The chip width of the data driver IC 106 is smaller than the width of the effective display region 102. Thus, wirings 107 to connect the output node of the data driver IC 106 and the demultiplexer 105 are radially arranged. The region in which this wirings 107 are arranged is referred to as a throttling region 108. The existence of the throttling region 108 is not preferable because of the increase in the region that is not used to actually display the image in the liquid crystal display panel 101.
On the other hand, FIGS. 2 and 3 are conceptual diagrams showing the configuration in which the demultiplexer is integrated in the data driver IC to select the data line. In a liquid crystal display apparatus 100A of FIG. 2, the demultiplexer is integrated in a data driver IC 106A and not in a liquid crystal display panel 101A. The data line D is directly connected to the output node of the data driver IC 106A through the wiring 107 that is laid in the throttling region 108.
FIG. 3 is a block diagram showing a typical configuration of the output stage of the data driver IC 106A. The image data, i.e., a pixel data to specify the gradation of each pixel is sent to a digital-to-analog (D/A) converter (DAC) 111, and the D/A converter 111 supplies a gradation voltage corresponding to the pixel data to an output amplifier 112. The output of the output amplifier 112 is connected to a demultiplexer 113. The demultiplexer 113 sequentially selects data lines D and connects the selected data line D to the output of the output amplifier 112. A drive voltage is supplied from the output node of the data driver IC 106A through the selected data line D to the desirable pixel 103.
Japanese Laid Open Patent Application (JP-P2005-165102A) further discloses the improvement of the configuration in which a demultiplexer to select the data line is integrated in the data driver IC. In the data driver IC disclosed in this related art, the demultiplexer is integrated in the data driver IC to connect the output amplifiers to output nodes, and a signal line to connect the output node, which is not connected to the output amplifier, to the output of a D/A converter is provided.
One demand to the display apparatus in recent years is to increase the number of data lines that can be driven by one data driver IC. In order to cope with this demand, the number of data lines that are driven in a time divisional manner by one output amplifier is required to be increased. Specifically, in the liquid crystal display apparatus of a next generation, it is required to use one output amplifier and drive the six or more data lines.
Another demand is to reduce a region other than an effective display region in the display panel (hereinafter, a non-effective display region). Through reduction of the non-effective display region it is possible to reduce the size of the display apparatus when the display panel is mounted, and this is useful for decreasing cost of the display panel.
However, the above two kinds of hardware configuration have a problem that, when the number of data lines to be driven in a time divisional manner by one output amplifier is increased in association with the increase in the number of data lines to be driven by one data driver IC, the non-effective display region of the display panel is increased.
At first, in the configuration in which the demultiplexer is integrated in the display panel, the increase in the number of data lines to be driven in the time divisional manner by one output amplifier involves the increase in the area of the demultiplexer 105. This results in the increase in the area of the non-effective display region in the display panel. There are two reasons why the non-effective display region is increased. Firstly, the trial of the increase in the number of data lines to be driven in the time divisional manner by the output amplifier requires the increase in the gate width of TFT of the demultiplexer provided on the display panel. The increase in the number of data lines to be driven in the time divisional manner by the output amplifier decreases a drive period of one data line. In order to sufficiently drive the data line in a shorter drive period, the on-resistance of the TFT of the demultiplexer is required to be low. In order to decrease the on-resistance of the TFT, the gate width of the TFT must be increased. However, the increase in the gate width of the TFT of the demultiplexer leads to the increase in the non-effective display region. Secondly, the increase in data lines to be driven in the time divisional manner by the output amplifier requires the increase in the number of control signal lines that are used to send control signals to the switches. This increases the area of the non-effective display region. The control signal line to send the control signal to the switch is a long wiring that reaches from one end of the effective display region of the display panel to the other end, and the area occupied thereby is very large.
On the other hand, in the configuration in which the demultiplexer for selecting the data line is integrated in the data driver IC, the number of output nodes from the data driver IC is not reduced, and the number of data lines driven by the data driver IC is increased. This increases the height of the throttling region 108 (the dimension in the y-axis direction), and also increases the non-effective display region of the display panel. This reason is as follows. In order to prevent a short-circuit between the wirings 107 to connect the data line D and the output of the data driver IC, a certain interval is required to be reserved between the wirings 107. Thus, an angle θ between the wiring 107 and the line in which the outputs of the data driver are lined up has a predetermined lower limit. Thus, in order to connect the wiring 107 to the data line D of the end, the height of the throttling region 108 is required to be reserved to a certain degree. This leads to the increase in the non-effective display region. Also, in order to suppress the height of the throttling region 108, if the interval between the wirings 107 is narrowed to a degree at which the short-circuit is not generated, a parasitic capacitance between the wirings is increased. Therefore, with the influence of the voltage variation caused by the capacitance coupling, a voltage error becomes greater. In particular, the voltage errors of the pixels located at the left and right ends of the effective display region 102 in which the wiring 107 is long become large, which brings about the display irregularity.

Display apparatus, data driver and method of driving display panel


A communications device includes a frequency conversion circuit and a control circuit. An antenna receives a radio signal at a first frequency and converts it into a radio frequency (RF) signal of the first frequency. The frequency conversion circuit is associated with the antenna and configured to convert the RF signal into a first signal component and a second signal component. The first and second signal components occupy a baseband. The control circuit has first ports connected to the frequency conversion circuit to receive the first and second signal components and second ports connected to a processor circuit to output amplified first and second signal components, and separate channels for the first and second signal components existing between the first and second ports. Each channel comprises an amplifier and a feedback loop configured to control the amplifier as a function of a reference signal and a control signal derived from the RF signal. The communications device may be a cellular phone comprising a direct conversion module.

1. Field of the Invention
The invention generally relates to a communications system. More particularly, the invention relates to a communications device and a method of receiving radio frequency signals within a communications system.
2. Description of the Related Art
One example of a communications system is a wireless communications system which may be a cellular mobile communications system. The cellular mobile communications system is implemented in a geographical area and logically divided into individual service cells. A fixed transceiver station such as a base station defines at least one cell and is connected to a base station controller. Mobile stations, such as hand-held or car-based cellular phones, move freely within the geographical area covered by a cell.
The base station handles all telephone traffic to and from those cellular phones which are currently located in the cell. In addition, the cellular phones and the base stations exchange radio signals in accordance with a communications protocol defined for a given communications system. For instance, in a conventional Code Division Multiple Access (CDMA) systems, a traffic channel, a pilot channel, and a paging channel are defined for communications between the base stations and the cellular phones. The pilot channel carries no information, but provides the cellular phone, for example, with a reference for time, phase and signal strength. The cellular phone constantly evaluates the strengths of the pilot channels of the serving and neighboring base stations to determine potential base stations should the cellular phone move from one cell to another.
In some cellular phones, a receiver includes two frequency conversion stages. A first conversion stage down converts a received radio frequency (RF signal) to an intermediate frequency (IF) signal whose intermediate frequency (IF) is lower than the radio frequency. An amplifier amplifies the IF signal and a second conversion stage down converts the amplified IF signal to the baseband.
Conventional direct conversion (DC) module receivers, on the other hand, convert the RF signal directly down to the baseband. The DC module outputs an inphase (I) signal component and a quadrature (Q) signal component which are, in turn, processed by a baseband processor. Subsequent to the downconversion, amplifiers amplify the signal components I and Q in separate I- and Q-channels. The amplifiers should amplify the signal components I and Q with gains that are ideally the same for each one of the signal components I and Q. Unfortunately, gain imbalances between the I- and Q-channels may degrade the signal demodulation in the baseband processor.
An aspect of the invention relates to a method of enhancing the direct conversion of a radio frequency signal. The method comprises converting a radio frequency (RF) signal into an I signal and a Q signal. The method further comprises varying the amplification of the I signal based on the comparison of the amplified I signal, a reference voltage, and a signal strength signal. The method also comprises varying the amplification of the Q signal based on the comparison of the amplified Q signal, the reference voltage and the received signal strength indicator signal.
An aspect of the invention involves a direct conversion receiver for a communications system. The receiver includes a frequency conversion circuit and a control circuit connected to the frequency conversion circuit. The frequency conversion circuit converts a radio frequency (RF) signal into a first signal component and a second signal component which occupy a baseband. The control circuit comprises first ports connected to the frequency conversion circuit to receive the first and second signal components and second ports connectable to a processor circuit to output amplified first and second signal components. Between the first and second ports exist separate channels for the first and second signal components. Each channel comprises an amplifier and a feedback loop to control the amplifier as a function of a reference signal and a control signal derived from the RF signal.
An aspect of the invention involves a wireless communications device that includes a frequency conversion circuit and a control circuit. An antenna receives a radio signal at a first frequency and converts it into an electrical radio frequency (RF) signal. The frequency conversion circuit is associated with the antenna and configured to convert the RF signal into a first signal component and a second signal component. The first and second signal components occupy a baseband. The control circuit has first ports connected to the frequency conversion circuit to receive the first and second signal components and second ports connected to a processor circuit to output amplified first and second signal components, and separate channels for the first and second signal components existing between the first and second ports. Each channel comprises an amplifier and a feedback loop configured to control the amplifier as a function of a reference signal and a control signal derived from the RF signal.
Another aspect of the invention involves an apparatus comprising a frequency conversion circuit and a control circuit. The frequency conversion circuit is configured to convert a first signal having a first frequency into a first signal component and a second signal component. The first and second signal components have a second frequency which is lower than the first frequency. The control circuit has first ports connected to the frequency conversion circuit to receive the first and second signal components and second ports connectable to a processor circuit to output amplified first and second signal components. The control circuit further has separate channels for the first and second signal components existing between the first and second ports. Each channel comprises an amplifier and a feedback loop configured to control the amplifier as a function of a reference signal and a control signal.
A further aspect of the invention involves a method of controlling power levels of first and second signal components, which are processed in separate channels. For each channel, one of the first and second signal components is amplified and a detector signal, which is indicative of a power level of one of the amplified first and second signal components, is generated. Further, an error signal, which is indicative of a difference between one of the amplified first and second signal components and a reference signal, is generated. The error signal and a control signal are summed to generate a gain control signal, and to adjust amplification of one of the first and second signal components.
Another aspect of the invention involves a method of controlling power levels of first and second signal components. The first and second signal components are processed in separate channels. In each channel one of the first and second signal components is amplified and amplification is controlled as a function of an error signal, which is indicative of a difference between the amplified signal component and a reference signal, and a sum of the error signal and a control signal.
For purposes of summarizing the invention, certain aspects, advantages and novel features of the invention have been described herein. Of course, it is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.
These and other aspects, advantages, and novel features of the invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings.
FIG. 1 is an illustration of a cellular phone.
FIG. 2 is an illustration of a receive path of a cellular phone.
FIG. 3 is a block diagram of a receiver.
FIG. 4 is an illustration of a frequency conversion module.
FIG. 5 is an illustration of a gain control module.

Secondary automatic gain control loops for direct conversion CDMA receivers


In order to realize a means for acquiring three-dimensional shape information about patterns by nondestruction and evaluate a relationship between the three-dimensional shape information about these patterns and device properties, a semiconductor device pattern evaluating system is provided with a feature index calculating means for quantifying a property of a three-dimensional shape of a pattern to be evaluated, as feature index, a database that records therein a relationship between the feature index of each three-dimensional pattern shape and a device property of a circuit containing patterns each having the feature index, and a device property estimating means for estimating a property of a device circuit formed by the pattern to be evaluated, on the basis of the feature index of the three-dimensional pattern shape, which have been quantified by the feature index calculating means, and the information recorded in the database.

The present invention relates to a semiconductor device pattern evaluating system for, in a semiconductor manufacturing process, evaluating whether the result of processing of each circuit pattern formed on a wafer is good or bad, and a method therefor, and particularly to a technology effective if applied to a method for estimating the property of a device circuit formed by a semiconductor device pattern to thereby evaluate the semiconductor device pattern.
In a conventional semiconductor circuit pattern relatively long in gate length, an electric property of a transistor has principally depended on a wiring width (gate length) of a gate wiring portion. Therefore, a scanning electron microscope (critical-dimension SEM) dedicated to measurement has heretofore been used to measure and manage the wiring width of the pattern in a semiconductor manufacturing process.
With shrink rapidly advanced in recent years, however, short channeling of each transistor has been put forward, and shape parameters for determining a device property have become more than just the wiring width.
The difference in pattern cross-sectional shape of a gate wiring will now be explained.
FIG. 2 is a diagram for describing the shape of a gate wiring pattern and abnormal shapes of gate wiring patterns.
Referring to FIG. 2, FIG. 2A shows a shape considered to be most desirable in general. A sidewall angle of each pattern sidewall is substantially vertical, and no bottom corner roundness or the like occurs in a pattern bottom.
On the other hand, FIG. 2B shows the shape of a taper, FIG. 2C illustrates the shape of a retrograde, and FIG. 2D depicts the shape of a footing (bottom corner roundness). These shapes are indicative of shape abnormalities caused because a condition for a manufacturing process is not suitable.
Since a gate length assumes the size of the pattern bottom, it is of importance that the size of the bottom is measured regardless of the shape.
In a gate process, ion implantation is performed with the wiring pattern as a mask to form a source/drain of the transistor. Therefore, the inclination of each pattern sidewall and the bottom corner roundness state exert an influence on the result of processing in the ion-implantation process, so that a device property varies.
While the evaluation of a pattern's three-dimensional shape is very important in this way, the conventional critical-dimension SEM has encountered difficulties in evaluating such a three-dimensional shape by only dimensions of a two-dimensional shape, like the width of a wiring pattern, the diameter of a contact hole, etc. Since a change in pattern shape makes a cause and hence the result of a subsequent process such as ion implantation is affected by its cause, there is a lot of uncertainty about the relationship between variations in three-dimensional shape and the property of a device formed as a result thereof.
In the scale-down advanced product as described above, it is becoming difficult to allow only the conventional wiring size to compensate for the device property. In order to ensure a desired device property in contrast, there is a need to clarify to which portion of a pattern's three-dimensional shape attention is made and with what degree of accuracy it should be managed.
However, the conventional critical-dimension SEM (Scanning Electron Microscope) is accompanied by problems that it is difficult to acquire information about the three-dimensional pattern shape, and as a device structure and a process become complex, it becomes also difficult to estimate which shape of the resultant three-dimensional pattern shape information is effective for any type of property.
If the relationship of these can be made clear, then the standard for process control becomes definite and hence stable production is enabled.
Incidentally, there is known one described in Japanese Patent Laid-open No. Hei 7(1995)-27549 as a related art relevant to the measurement of each pattern by using a critical-dimension SEM.

System and method for evaluating a semiconductor device pattern, method for controlling process of forming a semiconductor device pattern and method for monitoring a semiconductor device manufacturing process


The present invention relates to a composition for topical application for preventing hair loss, androgenic alopecia (AA) and stimulating hair growth having dutasteride. The composition for topical application for preventing hair loss and stimulating hair growth according to the present invention provides equal or superior hair loss prevention and hair growth stimulating effects while using much smaller dosage than the conventional compositions (oral dosage form) which use finasteride and dutasteride.

According to the studies conducted so far, it has been found that the causes of hair loss include endocrine system disorders such as hormonal imbalance; excessive sebum formation caused by circulatory system disorders such as autoimmune nervous system disorders, blood circulation disorders; nutritional deficiency of hair roots, allergies, bacterial infections, genetic factors psychological stress, environmental factors such as atmospheric pollution or foods, and aging etc.
The products which are sold as hair growth stimulating agents or hair loss preventing agents on hair include growth period inducing effects, hair growth period extending effects, 5α-reductase inhibitory effects, blood circulation promoting effects, antiseptic effects, anti-dandruff effects, moisturizing effects, antioxidant effects etc., but the effects of preventing hair loss and stimulating hair growth of conventional agents are not sufficient.
Male pattern alopecia is dependent on male hormones and is thus directly related to the amount of male hormones. 5α-reductase is an enzyme that is responsible for conversion of testosterone, a male sex hormone, to dihydrotestosterone (DHT). DHT is an androgenic compound that causes hyperandrogenic conditions like enlargement of the prostate in men with progressing age, termed "benign prostatic hyperplasia". Another consequence of increased DHT levels includes androgenic alopecia (AA), which is commonly termed "male pattern baldness." The cause of male pattern alopecia is synthesis of excessive DHT by action of 5α-reductase, and thus it is possible to fundamentally and effectively prevent and treat male pattern alopecia by inhibiting the activity of 5α-reductase.
Currently, two treatments are approved by U.S. Food and Drug Administration for the treatment of androgenic alopecia (AA) in males: topical minoxidil and oral finasteride. While minoxidil (having a chemical name 6-piperidin-1-ylpyrimidine-2,4-diamine 3-oxide) is an arterial vasodilator, finasteride is a type II 5α-reductase inhibitor.
The minoxidil was developed for the purpose of lowering blood pressure of hypertensive patients, but it is most widely used as hair growth drug since its use changed due to hair growth side-effects that occurred during the use. The mechanism of action of minoxidil has not been clearly elucidated. However, the mechanism of action of minoxidil has been explained by a hypothesis that the minoxidil increases blood flow to the follicles to cause an increase in blood flow, thus stimulating the growth of hair, and a hypothesis that the minoxidil acts directly on the follicular epithelium to induce the growth of hair. However, hair restorers comprising minoxidil should be applied several times daily to maintain the hair growth effect, which is very cumbersome and easy to forget. Therefore, in many cases, the hair growth effect is not sufficiently obtained due to irregular application and arbitrary discontinuation of treatment.
Finasteride is a drug that inhibits 5α-reductase type II which converts testosterone, one of the male hormones, into DHT that causes hair loss. Oral finasteride 1 mg causes the possible sexual side effects, which is used for the male pattern alopecia, even after discontinuation of use. Therefore, USFDA recommended the attention of medical professionals and patients. As a result of reviewing the postmarketing cases reported on the FDA's Adverse Event Reporting System (AERS) and safety databases of marketed products, it was found that some sexual function-related adverse reactions (such as hyposexuality, ejaculation disorders, orgasmic disorders etc.) continued even after discontinuation of use.
One more compound in the 5α-reductase inhibitor class is dutasteride. Dutasteride has a chemical name (5α,17β)-N-{2,5-bis(trifluoromethyl)phenyl}-3-oxo-4-azaandrost-1-ene-17-carboxamide. The structural formula is represented as below.

Dutasteride is a synthetic 4-azasteroid compound that is a selective inhibitor of both type I and type II isoforms of steroid 5α-reductase (5AR), an intracellular enzyme that converts testosterone to 5α-dihydrotestosterone (DHT), and is indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men. A pharmaceutical product containing dutasteride as the active ingredient is commercially available as AVODART®, which is approved by USFDA from GlaxoSmithKline, in the form of soft gelatin capsules for oral administration and containing 0.5 mg of the active ingredient. Oral Dutasteride has been approved by Ministry of Food and Drug Safety; South Korea for the treatment of male pattern baldness (androgenic alopecia) at dosage of 0.5 mg once daily.
Dutasteride is a highly lipophilic molecule (Log P=6.8). It is insoluble in water, soluble in ethanol, methanol and polyethylene glycol 400. Absolute bioavailability of orally administered dutasteride is only about 60% (40%-94%). Some of the known approaches to improve solubility characteristics and bioavailability of drug compounds include salt formation, particle size reduction, pH adjustment, use of surfactants, inclusion complexes with cyclodextrins, use of oily formulations, use of self-emulsifying drug delivery systems, formation of co-precipitates with hydrophilic polymers, and co-milling with hydrophilic excipients, to name a few. 5α-reductase inhibitors block conversion of testosterone to dihydrotestosterone (DHT), a potent androgen. Systemic administration 5α-reductase inhibitors suppress level of DHT in blood, thereby there are chances of sexual side effects. Oral Finasteride and dutasteride currently approved for androgenic alopecia causes sexual side effects on long term use.
US Patent Publication No. 20100048598 discloses the pharmaceutical composition for topical application comprising dutasteride or pharmaceutically acceptable salt, ester, derivative thereof, and a pharmaceutically acceptable carrier, and optionally one or more other pharmaceutically acceptable excipients. Further US '598 Publication discloses the pharmaceutical compositions for topical application comprising 0.5 wt % of dutasteride.
The present invention has been made to solve the above problems of the prior art, and an object of the present invention is to provide a composition of dutasteride for topical application for preventing hair loss and stimulating hair growth, which has the following advantages                1. It provides the effects of preventing hair loss and stimulating hair growth that are equal to or higher than that of conventional treatment agents (oral dutasteride & finasteride) even though the amount of dutasteride used is less than one half, more preferably less than two fifth that of the conventional treatment agents (oral dutasteride and finasteride).        2. There are almost no systemic side effects of the conventional treatment agents (oral dutasteride and finasteride).        3. It is possible to effectively prevent hair loss from the beginning of the treatment due to a rapid onset of the effect; and        4. It provides almost 100% effect to patients with hair loss, unlike the conventional prescription (oral dutasteride and finasteride) that provides about 70% effect.


A system for customizing a golf club which utilizes a hosel to interconnect the had and the shaft includes a hosel bending vise. The hosel bending vise imparts an offset bend and a lie angle bend in the hosel. The shaft of the golf club is then cut to length. If desired a loft angle bend may be made in the hosel.

Many golf professionals believe that individual golfers can dramatically improve their golf game if their golf clubs are customized to fit the size, structure, and strength of their bodies. Because each person's golf swing and physical capabilities are unique, customized golf clubs can maximize the performance in each golfer's unique swing and physical capabilities. Such maximization can be obtained, in part, by precisely adjusting the length of the golf club shaft and the spatial and geometric inter-relationship between the golf club head and the golf club shaft.
As many do not thoroughly understand the spatial and geometric inter-relationship between the golf club head and the golf club shaft, the next few paragraphs will lay the foundation for an understanding the Golf Club Customizing System of the present invention.


The oxygen partial pressure control unit includes a gas purification section for purifying the gas having the oxygen partial pressure controlled within a range of from 0.2 to 10−30 atm, and a tank for storing the purified gas produced by the gas purification section. The purified gas stored within the tank is supplied to the another unit. The oxygen partial pressure control unit includes a circulation circuit including the tank and the gas purification section. The gas filled in the tank 20 is caused to circulate along the circulation circuit, and the purified gas produced by the gas purification section is stored in the tank.

Conventionally, there is known a method in which a single crystal sample or the like is prepared using an atmospheric gas that has an oxygen partial pressure controlled by an oxygen partial pressure control unit provided with an electrochemical oxygen pump containing a solid electrolyte (Patent Document 1).
An oxygen partial pressure control unit illustrated in FIG. 9 includes a mass flow controller (MFC) 3 that controls the flow rate of an inert gas coming through a valve 2 to a set value, an electrochemical oxygen pump 4 capable of controlling the oxygen partial pressure of the inert gas coming through the mass flow controller 3 to a target value, and an oxygen sensor 5 for supply gas, which monitors the oxygen partial pressure of the inert gas, which has been controlled by the oxygen pump 4, and supplies the gas to a subsequent process (unit) such as a sample preparation unit.
This unit further includes an oxygen partial pressure setting section 6 that sets a desired oxygen partial pressure value, an oxygen partial pressure control section 7 that compares a monitor value of the oxygen sensor 5 with the set value of the oxygen partial pressure setting section 6 to control the oxygen partial pressure of the inert gas to be sent from the oxygen pump 4 to a predetermined value, and an oxygen partial pressure display section 8 that displays the monitor value of the oxygen sensor 5. It should be noted that the oxygen partial pressure of the inert gas is normally approximately 10−4 atm.
As illustrated in FIG. 10, in the electrochemical oxygen pump 4, electrodes 4b and 4c made of platinum are formed on both the inner surface and the outer surface of a solid electrolytic cylindrical body 4a having oxide ion conductivity. The solid electrolytic cylindrical body 4a is, for example, a zirconia-based solid electrolyte, and is heated by a heater (not shown). The inert gas is supplied in the axial direction from one opening of the solid electrolytic cylindrical body 4a to the other opening thereof. The inert gas is, for example, Ar+O2 (10−4 atm). The DC voltage of a DC power supply E is applied between the electrodes 4b and 4c disposed on both the inner and outer surfaces thereof. When a positive voltage is applied to the electrode 4c disposed on the outer surface and a negative voltage is applied to the electrode 4b disposed on the inner surface to cause a current I to flow, oxygen molecules (O2) within the inert gas flowing through the solid electrolytic cylindrical body 4a are electrically reduced into ions (O2−), and then are released via the solid electrolyte to the outside of the solid electrolytic cylindrical body 4a as oxygen molecules (O2) again. The oxygen molecules released to the outside of the solid electrolytic cylindrical body 4a are discharged along with auxiliary gases such as air. The inert gas Ar+O2 (10−4 atm) supplied to the solid electrolytic cylindrical body 4a is converted, with the oxygen molecules reduced in number, into a processed gas (purified gas) that has the oxygen partial pressure controlled to a target value, and then is fed to the subsequent process (unit).
It should be noted that the oxygen pump 4 of FIG. 10 is capable of performing the pump operation also when a DC voltage having the opposite polarity to the above-mentioned case is applied between the electrodes 4b and 4c disposed on both the inner and outer surfaces of the solid electrolytic cylindrical body 4a. Specifically, when a negative voltage is applied to the electrode 4c disposed on the outer surface and a positive voltage is applied to the electrode 4b disposed on the inner surface, oxygen molecules (O2) in gas, such as air, flowing along the outer surface of the solid electrolytic cylindrical body 4a are electrically reduced into ions (O2−) via the solid electrolyte, and then released via the solid electrolyte to the inside of the solid electrolytic cylindrical body 4a as oxygen molecules (O2) again. In this case, the oxygen partial pressure of the inert gas flowing inside the solid electrolytic cylindrical body 4a is increased, and the inert gas is fed to the outside.
By supplying a gas that has the oxygen partial pressure controlled by such an oxygen pump, it becomes possible to perform crystal growth, alloying, heat treatment, a semiconductor manufacturing process, and the like, under an inert gas atmosphere having a controlled oxygen partial pressure.
Patent Document 1: JP 2002-326887 A

Oxygen partial-pressure control unit and method of gas supply


A 1/4 wave circuit switch for use in an NMR probe has a housing with a stepped cavity for precisely locating switch components inside. The 1/4 wave circuit switch cooperates with a 1/4 wave tube and is designed to receive either an external capacitor on a capacitor stick for single tune operations or a 1/4 wave center conductor with a threaded tip on a 1/4 wave stick for double tune operations. For single tune operations, the external capacitor comes into contact at one end with a resiliently supported, movable electrical contact and at the other end with a spring clip inside the housing cavity to orient the external capacitor in parallel with the NMR coil. The movable electrical contact is resiliently biased by a pair of crescent washers supported by an insert plug which serves as a positive stop for the travel of the electrical contact. For double tune operations, the threaded tip of the 1/4 wave center conductor simultaneously contacts a pair of threaded contacts provided inside the housing cavity and spaced by an insulating spacer. The simultaneous contact creates a current path which grounds the NMR circuit through the 1/4 wave tube, so that the NMR circuit may resonate at two separate frequencies. The two frequencies can be easily adjusted by employing an extension tube that effectively changes the length of the 1/4 wave tube and grounds the NMR circuit through the 1/4 wave tube to resonate at different frequencies.

An NMR probe holds a sample placed in a uniform polarizing magnetic field in NMR spectrometry. A coil is disposed close to the sample within the probe to apply an exciting RF magnetic field to the sample. The resultant resonance signal of the sample is picked up by the coil and delivered to a receiver circuit. The receiver circuit generates an output signal. A computer takes the Fourier transform of the signal to obtain an NMR spectrum.
The NMR apparatus is most often characterized in gross by cylindrical symmetry. The internal structure of the probe generally exhibits no geometric symmetry because it contains circuits, circuit elements, connectors, fluid supply tubes, and mechanical mounting means for all of the above and the like. A typical NMR magnet is of the superconducting variety and is housed in a dewar which includes a room temperature cylindrical bore in which a very carefully controlled homogeneous magnetic field is sustained by operation of the superconducting magnet in the interior of the dewar. The NMR probe contains the excitation and detection interface to the sample and is mounted in a cylindrical housing for insertion in the bore.
It is often desirable to use an NMR probe to resonate at frequencies outside of the standard range of frequencies of the probe. In addition, NMR probes are used in single tune mode and double tune mode. Because existing NMR probes are generally constructed for use only in either single tune operation or double tune operation, two NMR probes are needed for applications in single tune and double tune.


An image display device includes: excitation light source (5), fluorescent screen (6) provided with a plurality of phosphor regions (61, 62, 63) that are arranged periodically in the in-plane direction, the regions between phosphor regions being retroreflective regions (64) that bend incident light in the direction opposite the direction of incidence of the light; scanning means (4) that scans fluorescent screen (6) with a light beam from excitation light source (5); optical detection means (2, 3) that detects retroreflective light (7) that is reflected by retroreflective regions (64); and control means (1) that causes scanning by scanning means (4), detects boundaries between each phosphor region (61, 62, 63) and retroreflective region (64) on fluorescent screen (6) based on output of optical detection means (2, 3), and controls the light emission timing of excitation light source (5) based on the detected boundaries.

In an image display device in which a fluorescent screen is scanned by an excitation light to display an image, the relative positional relationship between the scanning system and the fluorescent screen typically changes due to various causes such as vibration, distortion, or changes in the environment such as temperature or humidity, the influence of gravity, or changes over the passage of years, whereby the appropriate irradiation beam timing becomes difficult to maintain and image quality deteriorates.
In Patent Documents 1 and 2, image display devices are described that include: a fluorescent screen; an optical module that scans the fluorescent screen with a laser beam (excitation light); an optical sensor that detects the excitation light (feedback light) that is reflected by a reflection means on the fluorescent screen and generates a monitor signal for detecting the position of the laser beam on the fluorescent screen; and a feedback control unit that, based on the monitor signal from this optical sensor, controls the ON/OFF timing (light emission timing) of the laser beam in the optical module. The fluorescent screen includes a plurality of phosphor stripes and a reflection means that is provided between each of the phosphor stripes.
In the above-described image display device, an image is displayed by scanning the fluorescent screen in a direction orthogonal to the phosphor stripes by an excitation light beam (optical pulse) that is modulated based on a modulated signal to excite the phosphor of each phosphor stripe. In the feedback control, while carrying out this image display, a delay process is carried out on the modulated signal such that the position of each optical pulse moves back and forth in the scanning direction on the fluorescent screen. By means of this delay process, the output value of the optical sensor changes in accordance with the position of the beam with respect to each phosphor stripe. The optimum light emission timing is obtained based on the change in output of this optical sensor.

Image display device and light emission timing control method


An organic light-emitting diode (OLED) display, electronic device including the same and method of manufacturing the OLED display are disclosed. In one aspect, the OLED display includes a first plastic layer, a first barrier layer formed over the first plastic layer and a first intermediate layer formed over the first barrier layer. The OLED display also includes a second plastic layer formed over the first intermediate layer, a second intermediate layer formed over the second plastic layer and a second barrier layer formed over the second intermediate layer. The OLED display further includes an OLED layer formed over the second barrier layer and a thin-film encapsulation layer encapsulating the OLED layer.

Field
The described technology generally relates to an organic light-emitting diode (OLED) display, an electronic device including the same, and a method of manufacturing the OLED display.
Description of the Related Technology
OLED displays are self-emissive and include a number of OLEDs each having a hole injection electrode, an electron injection electrode, and an organic emission layer that is interposed between the hole and electron injection electrodes. Light is emitted from the OLEDs when holes injected from the hole injection electrode and electrons injected from the electron injection electrode recombine with and annihilate each other in the organic emission layer. OLED displays have garnered attention as next-generation displays due to their superior characteristics such as low power consumption, high luminance, and high response speeds.

Organic light-emitting diode (OLED) display comprising flexible substrate, electronic device including the same, and method of manufacturing the OLED display


An ultrasonic device with increased efficiency as a result of substantially increased pressure uniformity across individual PZTs and through the PZT stack. Specifically, the PZT stack is uniformly compressed by way of a bolt having a head that has a surface area roughly equal to the surface area of the individual piezoelectric elements. The bolt is further combined with an aft end bell that has a reduced surface contact with the bolt head and a larger surface contact with the adjacent piezoelectric stack.

The present invention relates generally to ultrasonic transducer assemblies and, in particular to transducer assemblies of the composite or sandwich type with a compression assembly for providing a more uniformly compressive loading to the transducer assembly.
Ultrasonic transmission devices are well known for use in a variety of applications, such as surgical operations and procedures. The ultrasonic transmission devices usually include a transducer that converts electrical energy into vibrational motion at ultrasonic frequencies. The vibrational motion is transmitted to vibrate a distal end of a surgical instrument. Such uses are disclosed in representative U.S. Pat. Nos. 3,636,943 and 5,746,756, both incorporated herein by reference.
High-intensity ultrasonic transducers of the composite or sandwich type typically include front and rear mass members with alternating annular piezoelectric transducers and electrodes stacked therebetween. Most such high-intensity transducer are of the pre-stressed type. They employ a compression bolt that that extends axially through the stack to place a static bias of about one-half of the compressive force that the piezoelectric (PZT) transducers can tolerate. Sandwich transducers utilizing a bolted stack transducer tuned to a resonant frequency and designed to a half wavelength of the resonant frequency are described in United Kingdom Patent No. 868,784. When the transducers operate they are designed to always remain in compression, swinging from a minimum compression of nominally zero to a maximum peak of no greater than the maximum compression strength of the material.
As shown in FIG. 1, an acoustic or transmission assembly 80 of an ultrasonic device generally includes a transducer stack or assembly 82 and a transmission component or working member. The transmission component may include a mounting device 84, a transmission rod or waveguide 86, and an end effector or applicator 88. The transmission rod 86 and end effector 88 are preferably part of a surgical instrument.
The transducer assembly 82 of the acoustic assembly 80 converts the electrical signal from a generator (not shown) into mechanical energy that results in longitudinal vibratory motion of the end effector 88 at ultrasonic frequencies. When the acoustic assembly 80 is energized, a vibratory motion standing wave is generated through the acoustic assembly 80. The amplitude of the vibratory motion at any point along the acoustic assembly 80 depends on the location along the acoustic assembly 80 at which the vibratory motion is measured. The transducer assembly 82, which is known as a xe2x80x9cLangevin stackxe2x80x9d, generally includes a transduction portion 90, a first resonator or aft end bell 92, and a second resonator or fore end bell 94. The transducer assembly 82 is preferably an integral number of one-half system wavelengths (nxcex/2) in length.
The distal end of the first resonator 92 is connected to the proximal end of transduction section 90, and the proximal end of the second resonator 94 is connected to the distal end of transduction portion 90. The first and second resonators 92 and 94 are preferably fabricated from titanium, aluminum, steel, or any other suitable material. The first and second resonators 92 and 94 have a length determined by a number of variables, including the thickness of the transduction section 90, the density and modulus of elasticity of material used in the resonators 92 and 94, and the fundamental frequency of the transducer assembly 82. The second resonator 94 may be tapered inwardly from its proximal end to its distal end to amplify the ultrasonic vibration amplitude.
The transduction portion 90 of the transducer assembly 82 preferably comprises a piezoelectric section (xe2x80x9cPZTsxe2x80x9d) of alternating positive electrodes 96 and negative electrodes 98, with piezoelectric elements 100 alternating between the electrodes 96 and 98. The piezoelectric elements 100 may be fabricated from any suitable material, such as, for example, lead zirconate-titanate, lead meta-niobate, lead titanate, or ceramic piezoelectric crystal material. Each of the positive electrodes 96, negative electrodes 98, and piezoelectric elements 100 have a bore extending through the center. The positive and negative electrodes 96 and 98 are electrically coupled to wires 102 and 104, respectfully. The wires 102 and 104 transmit the electrical signal from the generator to electrodes 96 and 98.
The piezoelectric elements 100 are energized in response to the electrical signal supplied from the generator to produce an acoustic standing wave in the acoustic assembly 80. The electrical signal causes disturbances in the piezoelectric elements 100 in the form of repeated small displacements resulting in large compression forces within the material. The repeated small displacements cause the piezoelectric elements 100 to expand and contract in a continuous manner along the axis of the voltage gradient, producing high frequency longitudinal waves of ultrasonic energy. The ultrasonic energy is transmitted through the acoustic assembly 80 to the end effector 88.
The piezoelectric elements 100 are conventionally held in compression between the first and second resonators 92 and 94 by a bolt and washer combination 106. The bolt 106 preferably has a head, a shank, and a threaded distal end. The bolt 106 is inserted from the proximal end of the first resonator 92 through the bores of the first resonator 92, the electrodes 96 and 98, and piezoelectric elements 100. The threaded distal end of the bolt 106 is screwed into a threaded bore in the proximal end of second resonator 94.
Other embodiments of the prior art utilize a stud that is threadedly engaged with both the first and second resonators 92 and 94 to provide compressive forces to the PZT stack. Threaded studs are also known in the prior art for attaching and detaching transmission components to the transducer assembly. See, for example, U.S. Pat. Nos. 5,324,299 and 5,746,756. Such bolts and studs are utilized to maintain acoustic coupling between elements of the sandwich type transducer or any attached acoustic assembly. Coupling is important to maintain tuning of the assembly, allowing the assembly to be driven in resonance.
The problem with the prior art is that the compression means is inadequate and is unable to provide a uniform pressure across the inside diameter to the outside diameter of each PZT and through the entire PZT stack, the xe2x80x9crxe2x80x9d and xe2x80x9czxe2x80x9d axes as shown in FIG. 1 and graphically illustrated in FIG. 2. A Finite Element analysis shows that the ratio of the pressure in the r axis is of the order of 4:1.
Non-uniform pressure across the r and z axes reduces transducer efficiency and leads to high heat generation. This limitation becomes acutely critical in temperature-limited applications. In temperature-limited applications, the reduced efficiency translates into higher heat generation in the transducer and reduced maximum output. Further, non-uniform pressure limits the magnitude of compression and therefore limits the power capability of the transducer.
U.S. Pat. No. 5,798,599 discloses an ultrasonic transducer assembly which includes soft, aluminum foil washers disposed between facing surfaces of adjacent members of the PZT stack. The washers deform under compressive loading to follow the surface irregularities of the adjacent member surfaces.
There is a need therefore, for an ultrasonic transducer that exhibits substantially uniform compressive stresses across each PZT and throughout the PZT stack to reduce heat generation and increase power output efficiency. This invention meets this need.
The invention is an ultrasonic device with increased efficiency as a result of substantially increased pressure uniformity across individual PZTs and through the PZT stack. The invention comprises a transducer assembly adapted to vibrate at an ultrasonic frequency in response to electrical energy, the transducer assembly comprising; a stack of alternating positive and negative electrodes and piezoelectric elements in an alternating relationship with the electrodes; a mounting device having a first end and a second end, the mounting device adapted to receive ultrasonic vibration from the stack and to transmit the ultrasonic vibration from the first end to the second end of the mounting device; and structural means for applying compression forces to the stack, the stack being held together solely by said compression means, and the compression means comprises a surface for applying compression forces, the surface having a surface area substantially equivalent to the surface area of an individual piezoelectric element.
In a further embodiment the compression means comprises a spacer element disposed between the surface area and the piezoelectric elements. The spacer element is configured to comprise a first and second contact area wherein the first contact area is in contact with the surface area and has a smaller area than the second contact area, which is in contact with the proximal end of the piezoelectric stack.
In one embodiment, the PZT stack is uniformly compressed by way of a threaded bolt that has a bolt head surface area roughly equal to the surface area of the individual piezoelectric elements. The bolt can be further combined with a selectively configured end bell that has a first contact surface in contact with the bolt head and a second contact surface in contact with the adjacent piezoelectric stack. The second contact surface has a greater surface area than the first contact surface.
An advantage of the current invention is that the transducer thermal and power efficiencies increase.
A further advantage of the current invention is that heat generation decreases to a degree that active cooling systems are not necessary.
A still further advantage is that uniform pressure allows larger compression magnitudes which in turn leads to larger actuation magnitude. A larger actuation magnitude results in an increase of the useable range of the PZT.
These and other features and advantages of the present invention will become apparent from the following more detailed description, when taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Ultrasonic transducer with improved compressive loading