A spring drive mechanism for power switch gear. The mechanism includes an engagement shaft free to rotate about its own axis and carrying both a large toothed wheel and a cam. An engagement spring constituted by a traction spring is coupled to the large toothed wheel at an attachment point by a chain. The large toothed wheel meshes with a small toothed wheel which is coupled via a gear train to a driving gearwheel secured to an outlet shaft of a drive motor. In the predetermined direction A of rotation, the large toothed wheel includes a discontinuity in its teeth, thereby generating a gap which constitutes a zone without teeth, and in which a retractable tooth is disposed. Following the retractable tooth, the large toothed wheel has an additional discontinuity in its teeth over at least two meshing steps. This mechanism is advantageous as switchgear for a circuit breaker.

European patent application No. 0 651 409 A1 describes a mechanism of this type. In that embodiment, all of the teeth of the small toothed wheel and the first tooth following, in the predetermined direction, the gap formed by the discontinuity in the teeth of the large toothed wheel are shaped in such a manner that their flanks converge on respective single common edges. The purpose of that measure is to prevent the toothed wheels jamming. Nevertheless, it turns out that the friction between an edge of the small toothed wheel against the leading flank of the first tooth of the large tooth wheel immediately after the gap gives rise to a loss of power of greater or lesser extent due to friction. Such losses of power depend on the position of the small toothed wheel, and as a result they give rise to variations in the time taken to engage the switchgear as well as to non-negligible wear on the first tooth of the large toothed wheel immediately following the gap. If the mechanism is used for controlling a switch that is designed to be engaged to reduce surges on a network synchronously with the voltage of the network, then such variations appear in random manner and are not acceptable.
European patent No. 0 294 561 A2 describes a drive mechanism of similar type, coupled to a disconnector and having a first tooth of the large toothed wheel that is situated immediately following the gap which is radially retractable against the urging of a compression spring. If this tooth comes into abutment against the top of a tooth of the small toothed wheel at the beginning of the engagement process, then it retracts radially, compressing the spring with which it is associated. As a result, this tooth can slide over the edge of the corresponding tooth of the small toothed wheel without giving rise to jamming. After it has gone past the edge, it engages in the space following the tooth of the small toothed wheel. Nevertheless, there exists a large risk of the retractable tooth continuing to drive the large toothed wheel by friction, in spite of it being progressively retracted into the housing which contains the spring. Under such circumstances, the second tooth following the gap formed on the large toothed wheel, which second tooth is not retractable, can itself come into abutment against the edge of a tooth of the small toothed wheel and jam the entire mechanism. This probability is high, since the small toothed wheel is decoupled from its drive by a freewheel coupling and therefore can turn very easily.

Spring drive mechanism for switch gear, in particular a circuit breaker


Methods of manufacturing a semiconductor device include forming a gate electrode on a semiconductor substrate, forming spacers on side walls of the gate electrode, and doping impurities into the semiconductor substrate on both sides of the spacers to form highly doped impurity regions. The spacers are selectively etched to expose portions of the semiconductor substrate, and more lightly doped impurity regions are formed in the semiconductor substrate between the highly doped impurity regions and the gate electrode.

Some embodiments relate to methods of manufacturing a semiconductor device. More particularly, some embodiments relate to methods of manufacturing a semiconductor device including a metal oxide semiconductor (MOS) transistor having a reduced overlapping capacitance.
Generally, as semiconductor devices become more highly integrated, short channel effects in MOS transistors have become more problematic. In order to reduce the prevalence of short channel effects, source/drain regions of MOS transistors have been formed to have a lightly doped drain (LDD) structure.
FIG. 1 illustrates an LDD structure formed by using an offset dual spacer (ODS).
The LDD structure illustrated in FIG. 1 may include two offset spacers 25 and 40 formed on side walls of a gate electrode 15 formed on a substrate 10. At the bottom portion of the gate electrode 15, a gate oxide layer 12 may be formed, and at a side wall of the gate electrode 15, a side wall oxide spacer 20 may be formed. By using the two offset spacers 25 and 40, a lightly doped impurity region 30 and a highly doped impurity region 45 may be formed.
FIG. 2 illustrates an LDD structure formed by using an offset single spacer (OSS).
The LDD structure illustrated in FIG. 2 may include one offset spacer 25 formed on a side wall of a gate electrode 15.
Referring to FIGS. 1 and 2, the ODS and OSS LDD structures may have little difference in terms of a shape of the spacers and a shape of impurity regions. However, the LDD structures show a very large difference in electric characteristics. The differences in the electric characteristics of MOS devices including ODS and OSS LDD structures are shown in FIGS. 3 to 8.
FIGS. 3 to 5 illustrate graphs for comparing a current, a driving voltage and a gate overlapping capacitance value of each NMOS transistor having an LDD structure formed by using an ODS or an OSS.
Referring to FIG. 3, the NMOS transistor formed by using the OSS shows a slight decrease but no improvement of a driving current when compared to the NMOS transistor formed by using the ODS.
Referring to FIG. 4, the NMOS transistor formed by using the OSS shows an improvement in an average driving voltage by about 5 mV when compared to the NMOS transistor formed by using the ODS.
Referring to FIG. 5, the NMOS transistor formed by using the OSS shows a decrease of a gate overlapping capacitance value by about 3.0% when compared to the NMOS transistor formed by using the ODS.
FIGS. 6 to 8 illustrate graphs for comparing a current, a driving voltage and a gate overlapping capacitance value of each PMOS transistor having an LDD structure formed by using an ODS or an OSS.
Referring to FIG. 6, the PMOS transistor formed by using the OSS shows an improvement in a driving current by about 7.44% when compared to the PMOS transistor formed by using the ODS.
Referring to FIG. 7, the PMOS transistor formed by using the OSS shows an improvement in an average driving voltage by about 67 mV when compared to the PMOS transistor formed by using the ODS.
Referring to FIG. 8, the PMOS transistor formed by using the OSS shows a decrease of a gate overlapping capacitance value by about 3.65% when compared to the PMOS transistor formed by using the ODS.
As described above, the performance of a transistor having an LDD structure including an OSS structure may be improved compared to transistors having an ODS structure. However, for manufacturing a dynamic random access memory (DRAM), commonly applicable processes for manufacturing a MOS transistor having an LDD structure using an OSS structure may be very complicated.
In particular, when an offset spacer layer is formed on a side wall of a gate electrode and on a substrate in a peripheral region, the offset spacer layer may also be formed on a bit line and on the substrate in a cell region. Since the formation of the offset spacer may not be necessary on the side wall of the bit line in the cell region, the cell region may be covered using a photoresist layer pattern by performing a photolithography process before etching the offset spacer layer anisotropically to form the offset spacer in the peripheral region.
Then, an anisotropic etching process with respect to the offset spacer layer in the peripheral region may be performed to form the spacer on the side wall of the gate electrode. Thereafter, a lightly doped impurity region may be formed and an additional oxide layer spacer may be formed. Then, a highly doped impurity region may be formed.
As described above, an additional photolithography process may be required for selectively covering the cell region before forming the lightly doped impurity region in the peripheral region. In addition, the area of a bottom portion of a contact plug formed between the bit lines may be decreased due to the offset spacer layer that remains on the side wall of the bit line in the cell region.

Method of manufacturing semiconductor device


An arrangement is disclosed for supplying an air jet form to the furnace of a recovery boiler, where the furnace has a front wall, a rear wall and side walls. Black liquor spraying devices are disposed on the furnace walls at one or several levels of the furnace. A plurality of air ports are located at several horizontal levels for introducing air into the furnace from an air supply. In the arrangement for the secondary air flows, two horizontal air levels at different elevations are arranged above the lower primary levels and below the black liquor sprayer. Secondary air is supplied from two opposite walls and the air ports from each of the two levels are located so that the air jets are introduced in an interlaced pattern having an even number of jets on one opposite wall and an uneven number of jets on the other opposite wall. The air jets of said at least two air levels are located substantially one above each other in substantially vertical rows.

The present invention relates to an arrangement for supplying air in an air jet form to the furnace of a recovery boiler. The furnace has a front wall, a rear wall and side walls. Black liquor spraying devices are disposed on these walls at one or several levels. A plurality of air ports are located on several horizontal levels on said walls for introducing air into the furnace from an air supply. Specifically, the invention relates to an arrangement for organizing the secondary air flows below the black liquor spraying devices.
An optimal supply of combustion air in the lower part of the furnace of a black liquor recovery boiler plays a considerable role in the control of a combustion process in the boiler.
Since the chemical reactions in the kraft recovery boiler are very rapid, the speed of the process becomes substantially dependent on the mixing of combustion air and black liquor. This mixing step determines the burning rate and also has an effect on the process efficiency. Air and black liquor are typically introduced into the boiler through individual ports, and it is particularly important that a rapid mixing in the boiler is effected by the air supply without generating large differences in the upward flow profile. The high velocity xe2x80x9cliftxe2x80x9d in the center of the furnace is especially harmful as it results in carry-over of the sprayed liquor droplets. The burning symmetry must be controlled throughout the whole cross-sectional area of the boiler and the air supply must be adjusted when required.
Black liquor is generally introduced in the form of considerably large droplets into a kraft recovery boiler so as to facilitate the downward flow of the droplets, and to prevent them from flowing, unreacted (as fine fume), upwards together with the upward flowing gases to the upper part of the boiler. The large droplet size, which results in the droplets being spaced further from each other than in a fine black liquor spray, means that proper mixing is even more important in a recovery boiler. Pyrolysis of black liquor solids produces char as well as combustible gases. The char falls down to the bottom of the furnace and forms a char bed which must be burned.
A stoichiometric amount of air, relative to the amount of black liquor, is introduced into the recovery boiler and additionally, a surplus amount of air is supplied to ensure complete combustion. Too much excessive air, however, causes a loss in efficiency of the boiler and an increase in costs. Air is usually introduced into the boiler on three different levels: primary air at the lower part of the furnace, secondary air above the primary air level but below the liquor nozzles, and tertiary air above the liquor nozzles to ensure complete combustion. Air is usually introduced through several air ports located on all four furnace walls, or only on two opposing walls of the furnace.
Primary air is typically 20-35% of the total air supplied into the furnace, depending on liquor and dry solids content of the liquor. The task of the primary air is to keep the char bed from rising into air ports of the furnace. Secondary air is typically 35-60% of total air, and tertiary air, which may be distributed into several levels in vertical direction, is typically 10-40% of the total air. More than three air levels for introducing air into the furnace may be arranged in the boiler.
Mixing of black liquor and air is difficult because of the upflow of gas which is formed in the center part of the boiler, through which it is difficult for the weak secondary air flow to penetrate. More specifically, the primary air flows, supplied from the sides in the bottom part of the boiler, collide with each other in the center part of the boiler and form, with secondary air flow pattern, in the center part of the boiler, a gas flow flowing very rapidly upwards, catching flue gases and other incompletely burnt gaseous or dusty material from the lower part of the furnace. This gas flow, also called a xe2x80x9cdroplet liftxe2x80x9d, also catches black liquor particles flowing counter-currently downwards and carries them to the upper part of the boiler, where they stick to the heat surfaces of the boiler, thus causing fouling and clogging. In the center part of the boiler, the speed of the upwards flowing gas may become as much as four times as great as the average speed of the gases as a result of incomplete or weak mixing. Thus, a zone of rapid flow is formed in the center part of the boiler, and this renders mixing of flue gases from the side of the flow very difficult to achieve.
The xe2x80x9cdroplet liftxe2x80x9d mentioned above, results in such a situation where the tertiary air(s) has (have) to burn not only the unburned gases from combustion (CO, H2S, NH3, etc.), but the unburned char from the droplets as well. As the combustion rate for char is much slower than for the unburned gases, increased excess oxygen has to be used to ensure complete combustion. Then the flue gas leaving the furnace contains higher amounts of residual CO and H2S, and the utilization of the furnace is less effective than would be possible.
Current secondary air arrangements are also characterized by at least one secondary air level where secondary air ports are placed close to another in horizontal direction. This leads to mixing patterns where furnace gases are circulated in vertical direction, with the above mentioned xe2x80x9cliftxe2x80x9d, i.e. they flow towards the walls and then turn up (or down) and follow the main flue gas direction.
Another variation of the secondary air design is to use partial interlaced jets (e.g. U.S. Pat. Nos. 5,121,700, 5,305,698), whereby a large jet opposes a small jet. The large and small jets are alternated between the two opposite walls used.
U.S. Pat. No. 5,724,895 discloses an arrangement for feeding combustion air. In this system, a more favorable flow pattern in furnaces can be achieved by replacing vertical mixing by horizontal mixing, whereby a strong central flow channel, upward xe2x80x9cliftxe2x80x9d, can be prevented. This horizontal mixing is applied for the whole furnace. The horizontal mixing is improved by disposing additional air inlet ports e.g., at more than six different elevations in a pattern of vertical spaced-apart rows above the lowest air levels.
In the method of U.S. Pat. No. 5,454,908 a portion of combustion air is introduced into a recovery boiler at a distance above the black liquor inlet so as to provide a reducing atmosphere with a residence time of at least three seconds between the black liquor inlet and the introduction of said portion of combustion air. A drawback of the described arrangement is a high vertical combustion area, reaching in extreme cases the bullnose of the furnace. As this combustion area has a reducing atmosphere, at least locally, more expensive materials have to be used in the furnace to a higher position than would be needed if combustion took place lower in the furnace. Other disadvantages of the air systems, where combustion takes place high up in the furnace include high furnace outlet temperature resulting in large convective heat transfer surfaces later in the boiler, lower temperature in the lower furnace, and more expensive layout. The lower temperature in the lower furnace does not allow as high sulfidity without SO2 emissions as a combustion system having a higher lower furnace temperature does.
The present invention provides an improved air supply system of combustion air to a recovery boiler. Particularly, a secondary combustion air supply is provided in which either local and/or central upward gas flows having a high velocity compared to an average upward gas velocity are efficiently avoided. Another feature of the invention is to enable a constant penetration of combustion air into the boiler at different loading levels. A further feature of the invention is to produce a better mixing of black liquor and combustion air in the furnace. The improved air supply arrangement of this invention is also designed to reduce the amount of harmful emissions from the boiler furnace.
The present invention may be embodied in a recovery boiler having a furnace that comprises:
two horizontal air levels at different elevations are arranged above the lowest air level or levels and below the black liquor spraying level or levels,
air is supplied from two opposite walls on said two levels and the air ports on each level are located so that the air jets are introduced in an interlaced pattern having an even number of jets on one opposite wall and an uneven number of jets on the other opposite wall, and
the air jets of said two air levels are located in substantially vertical rows.
According to an embodiment of the invention, secondary air on two air levels is introduced only from the two opposite walls, preferably from the front and rear walls. Substantially no air is supplied from the two remaining walls, i.e., the side walls. In the interlaced pattern, an air flow coming from an air port located on a wall having an even number of air jets is directed in between two adjacent air ports of the opposite wall having an uneven number of air jets. Correspondingly, the air jets coming from the wall having an uneven number of air jets are directed substantially directly in a horizontal plane towards the opposite wall. The air jets coming from the opposite walls by-pass each other without actually colliding with each other.
Thus, on the two secondary levels, the lateral arrangement of the jets on one level sideways is symmetrical. On the wall having an uneven number of air jets, e.g. three, the middle air jet is located substantially on the center line of the wall, and the other jets are located within an equal distance on both sides of the middle jet. On the opposite wall having an even number of jets, two in this example, the jets are located laterally midway between the jets on the opposite wall. Thus, the jet arrangement is symmetrical in relation to the vertical plane parallel to the remaining walls (i.e. the walls having no secondary air jets) and passing through the center lines of the walls having the secondary air jets.
The present invention employs the following principles in order to avoid strong vertical gas flows, but still to obtain effective mixing in the furnace between combustion air and unburned/burning liquor droplets:
strong secondary air jets (strong air jets below black liquor spraying devices).
arrange these jets so that they do not collide against each other, which easily generates strong upflow jets and unwanted upflow profile for the gases in the furnaces. Instead, strong shearing flows should be generated to obtain good mixing.
minimize suction of gases in vertical direction into these jets above the liquor spraying devices as this increases gas flow up.
minimize suction of liquor droplets from liquor sprays into tertiary air jets.
cover the tertiary air stage(s) with several jets, which cover the furnace cross section evenly and well in order to prevent the formation of vertical jets that may punch the final combustion area where the final combustion of the unburned gases cannot take place. Also, here the jets should not collide against each other but generate strong shearing flows and good mixing.
According to a preferred embodiment of the invention, there is a distance, V, in vertical direction between the horizontal air levels, when measured from the lateral center lines of the air ports of the air levels. This distance, V, fulfills the following formula: V/Lxe2x89xa60.5, where L is the distance between two adjacent air ports on the same air level, when measured from the longitudinal center lines of the adjacent air ports. Preferably, V/L is 0.25-0.5. Typically, the vertical distance, V, is 1-2 meters.
Preferably the air ports located one above the other are positioned in a vertical row so that they are located on the same straight vertical line. The invention covers also an embodiment in which the air ports laterally deviate so that there a transverse distance, D, between the air ports above each other. The transverse distance is a distance between the longitudinal center lines of the ports one above the other. D is less than 1.5xc3x97H or less than 1.5xc3x97W depending on which number is greater. H is the height of the highest air port and W is the width of the widest air port.
According to an embodiment of the invention there is only one air level below the two secondary air levels. According to another embodiment, the number of the lowest air levels below the two secondary air levels is two. The air jets of the air level which is located higher in vertical direction below the two secondary air levels are arranged in an interlaced pattern on two opposite walls, preferably on the front and rear walls, so that the number of air jets is greater by one than the number of air jets of the two secondary air levels on the same wall. For example, if the secondary air level has one air jet on the front wall and two jets on the rear wall, the above-mentioned lower air level has two air jets on the front wall and three jets on the rear wall. However, the air velocity is lower on this lower air level. On this air level which, thus, is located above the lowest air level and below the two secondary air levels, and which can be called a low-secondary or high-primary air level, the air jets are arranged also on the remaining opposite walls, i.e., preferably on the side walls. The air jets on the side walls are smaller than the air jets on the front and rear walls.
An embodiment of the invention is directed also to an arrangement for supplying secondary air in an air jet form to the furnace of a recovery boiler, said furnace having a front wall, a rear wall and side walls, black liquor spraying devices disposed on said walls on a level and a plurality of air ports located on several horizontal levels on said walls for introducing air into the furnace from an air supply, said arrangement comprising: one horizontal air level is arranged above the lowest air level or levels and below the black liquor spraying level or levels, and air is supplied from two opposite walls on said level and the air ports are located so that the air jets are introduced in an interlaced pattern having an even number of jets on one opposite wall and an uneven number of jets on the other opposite wall. The air port has an area, A, and a width, W, and the ratio of the area to the width to the power of 2 (A/W2) is more than 4, preferably more than 10.

Combustion air system for recovery boilers, burning spent liquors from pulping processes


The present invention provides a plasma display apparatus comprising a second driver supplying a first bias signal with a voltage maintained at a first bias voltage in a reset period and an address period, a first sustain rising signal that gradually rises from the first bias voltage to a second bias voltage, and a second bias signal with a voltage maintained at the second bias voltage, to the second electrode.

1. Field of the Invention
This document relates to a plasma display apparatus and a driving method of the plasma display apparatus
2. Description of the Background Art
Generally, a plasma display apparatus comprises a plasma display panel in which a plurality of electrodes are formed, and a driver for the plurality of electrodes of the plasma display panel. The driver of the plasma display apparatus supplies a driving signal. In accordance to the driving signal, a reset discharge, an address discharge, and a sustain discharge are generated in a discharge cell of the plasma display panel. When the discharges are generated in the discharge cell, a discharge gas filled in the discharge cell generates vacuum ultraviolet rays. The vacuum ultraviolet rays causes a phosphor formed in the discharge cell to emit light, and an image is displayed.
In the plasma display apparatus, a noise due to a coupling effect occurring between electrodes overlaps with the driving signal. The noise causes to generate an Electro Magnetic Interference, and causes an operation of the plasma display apparatus to be unstable.

Plasma display apparatus and driving method of plasma display apparatus


This invention provides infrared sensing photodetector and a method therefor which provides a structure for effectively absorbing a light incident in a normal direction on a substrate, and a method compatible with existing processes for making integrated circuitry. An infrared sensing photodetector includes a compound semiconductor substrate of a first conductivity type, superlattice areas having implanted impurity ions of a second conductivity type opposite to the compound semiconductor substrate, each being spaced a predetermined distance each other in a selected region of the semiconductor substrate, a first collector area and a first emitter area which are formed in both end portions positioned perpendicular relative to the doped superlattice areas, a first collector electrode and a first emitter electrode formed on the first collector area and the first emitter area, respectively, a second collector area and a second emitter area which are spaced a predetermined distance in a horizontal direction on the doped superlattice area, and a second collector electrode and a second emitter electrode formed on the second collector area and the second emitter area, respectively.

1. Field of the Invention
The present invention relates to an infrared photodetector and method thereof, and more specifically to an infrared photodetector using doping superlattice structure with improved photo-sensitivity and method thereof.
2. Description of the Prior Art
In general, infrared semiconductor devices are used in many practical applications such as communications, security systems, and other modern electronic devices. In many of these applications, the sensitivity of the infrared photodetector is critical to its application.
Accordingly, there have been many advances in the use of semiconductor and transistor structures for detecting infrared radiation or light. Many of these advances have resulted in faster, more responsive detectors, as well as detectors capable of detecting multi-color infrared radiation.
Recently, multiple quantum well (MQW) photodetectors using heterojunction superlattice structure of compound semiconductors have been developed One such detector is disclosed in U.S. Pat. No. 5,272,356 issuing to Wen on Dec. 21, 1993, and entitled "MQW Photodetector for Normal Incident Radiation".
However, infrared photodetector with doping superlattice structure have not yet found widespread commercial use.
The doping superlattice structure-consists of ultrathin n- and p-type doped layer, possibly separated by intrinsic layers (n-i-p-i crystal). These doped superlattice exhibit novel electronic properties which result from a very efficient spatial separation between electron and hole subbands (indirect gap in real space) by the periodic space-charge potential. This separation implies recombination lifetimes which may be increased by many orders of magnitude over those of bulk material. Consequently, large deviations of the electron and hole concentration from thermal equilibrium are metastable under weak excitation conditions.
In addition, the space-charge-induced superlattice potential itself is strongly affected by a variation of the electron and hole concentration. The effective energy gap of a n-i-p-i crystal as well as the structure of the dimensional (2D) subband should thus no longer be fixed material parameters but tunable quantities.
The basic electron and optical properties of the doping superlattice structure (n-i-p-i crystal) are tunable as a consequence of the spatially indirect bandgap which can be varied with optical or electrical excitation. The absorption coefficient of a semiconductor at photon energies below the bandgap increases in the presence of an electric field.
In a n-i-p-i crystal, a large electric field is built in due to the ionized impurities. Hence, by varying the effective bandgap which varies the electric field, the absorption coefficient and the conductivity can be tuned. Using these properties, infrared photodetector is manufactured.
FIG. 1 shows a cross-sectional view of the infrared photodetector with doping superlattice structure according to a prior art. This device includes a substrate 1, a p+ emitter layer 2, doped superlattice layers 3, an N+ collector layer 4, an emitter electrode 5, and a collector electrode 6.
A configuration of the conventional photodetector made according to the conventional method is such that the quantum wells provided in the superlattice areas are arranged in a horizontal manner, therefore it is difficult for any incident light in a normal direction on the substrate to be absorbed in the superlattice areas.
To overcome such a problem, there has been used a substrate having an etched mesa structure suitable for absorbing more light incident in a normal direction, or a prism type of flat plate acting to change a propagating path of the incident light.
However, these configurations adopted to moderate the problem requires to use considerably expensive equipment, such as metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE), to be used for making the desired superlattice structure, which therefore increases in a manufacturing cost.
Further, since the structures made advantageously do not exhibit a satisfactory absorption feature of the light incident in a normal direction, the structures further necessitate another auxiliaries separately provided thereto for an effective absorption of the incident light, moreover not compatible with existing processes for fabricating the required integrated circuits, making it difficult to integrate the conventional structure together with other integrated circuitry.

Infrared photodetector with doping superlattice structure

Electronics and Telecommunications Research Institute


In one aspect, the present invention provides an implant device for use in an eye with elevated intraocular pressure or glaucoma. In another aspect, the present invention provides a method for lowering intraocular pressure and/or treating a condition associated with elevated intraocular pressure using the implant device of the present invention.

Glaucoma is a major cause of blindness worldwide. The blindness that results from glaucoma can involve both central and peripheral vision and can have a major impact on an individual's ability to lead an independent and productive life. Pathophysiologically, glaucoma is an optic neuropathy (a disorder of the optic nerve) observed most typically in the setting of an elevated intraocular pressure. Dramatic and/or prolonged increases in intraocular pressure cause changes in the appearance ("cupping" or "excavation") and function ("scotomas" or "blind spots" in the visual field) of the optic nerve. If the pressure remains high enough for a long enough period of time, total, irreversible vision loss occurs. High intraocular pressure results from an imbalance in intraocular fluid production versus outflow. Glaucoma surgeries, also referred to as filtering procedures, are designed to improve intraocular fluid balance by augmenting fluid outflow, thereby lowering intraocular pressure.
Many techniques are available for treating an eye with an elevated intraocular pressure. These include various surgical techniques for facilitating flow of fluid from the inside of the eye to the subconjunctival space. The most commonly performed procedure, known as a trabeculectomy, involves creating a surgical fistula between the anterior chamber of the eye and the subconjunctival space. Less commonly, a surgical drainage device may facilitate flow of fluid between the anterior chamber and the subconjunctival space. Some such drainage devices, such as the Molteno, Ahmed, Kruppin, and Baerveldt valves, connect via a shunt tube to an externally fixated, subconjunctival reservoir. Modifications of these devices are available whereby the external reservoir and tube may facilitate flow from the posterior segment of the eye at the pars plana following removal of the vitreous to prevent clogging.

Glaucoma drainage device and uses thereof


A brush for applying mascara or the like, having a bristle array with a discontinuous profile including two contiguous tandem portions, differing from each other in cross-section, for respectively performing different mascara-applying functions.

This invention relates to bristle brushes for applying cosmetics such as mascara or the like.
For purposes of illustration, the invention will be described as embodied in mascara brushes of the type having an axially elongated twisted wire core with a multiplicity of fibers such as bristles clamped at their midpoints in the core and extending radially outwardly therefrom to form a brush bristle array surrounding the core over a substantial portion of the length of the core, typically to the outer (distal) end of the core. The core is constituted of two runs of wire, which may be initially separate but are more usually opposed legs of a single U-shaped wire, twisted together into an axially rectilinear helix to hold the bristles between them. This combination of a twisted wire core and a radiating array of bristles clamped in the core provides a simple, low-cost and effective brush structure for uses exemplified by the application of mascara.
Such mascara brushes are well known and widely used in the cosmetics industry. Commonly, the proximal end of the brush is mounted within the threaded cap of a mascara container, so that the brush projects into the container when the cap is in container-closing position. Upon removal of the cap, the brush carries a quantity of mascara out of the container, and is manipulated to deliver and apply the mascara to the user's eyelashes, the cap serving as a handle for the brush.
In conventional mascara brushes having the described twisted-wire-and-bristle construction, the overall profile of the brush bristle array (such profile being the notional envelope defined by the bristle extremities) is ordinarily cylindrical and/or smoothly tapering, with progressively shorter bristles, toward the distal end of the brush. The bristles within the profile may be arranged in discrete though closely spaced helical rows corresponding to the helical turns of the wire core, or they may be distributed substantially uniformly. In either case, any given brush has essentially only a single set of applicator characteristics (shape, dimensions, bristle stiffness, etc.). The application of mascara, however, involves diverse functions and operations, including pickup, transport and deposit of the mascara; combing of the lashes; and even distribution of the applied mascara. The applicator characteristics of a given conventional brush do not perform all these various functions and operations equally well.
It has heretofore been proposed to provide two implements, such as a brush and a comb, for separately performing the diverse functions involved in applying mascara. The provision of two implements adds to cost and detracts from convenience of use; furthermore, as it is usually not feasible to enclose more than one implement in a mascara container, one of the implements must be left exposed (when not in use) to contamination outside the container.

Cosmetics brush with discontinous bristle face


A printing control method comprises a rendering step for rendering a description language document, a color matching step for converting color information specified in the description language document into color information for a printing device which is to print the description language document, and a control step for controlling whether to perform the conversion in the color matching step before the rendering or following the rendering. Appropriately controlling whether to perform color matching before rendering or following rendering enables color reproducibility to be improved.

1. Field of the Invention
The present invention relates to the art of rendering and color matching with an imaging device such as a printing device.
2. Description of the Related Art
Conventionally, at the time of outputting color specified in rendering commands in a PDL (Page Description Language) document to a monitor or printer (output device), the PDL document is subjected to gamut mapping/conversion. This gamut mapping/conversion is performed using a profile (ICC profile or the like) of the output device, to perform mapping/conversion of the PDL document into the gamut of the output device. This method is described in Japanese Patent Laid-Open No. 7-107312, for example.
Also, Japanese Patent Laid-Open No. 8-235346 describes converting objects having different attributes (color space, etc.) into respective optimal image data structures, and switching the color matching processing to be applied to the image data structure in real-time.
There are cases wherein opacity (alpha value) is included in PDL document rendering commands as a color specification. Alpha blending is necessary in the event that an image according to rendering commands having opacity and an image according to other rendering commands overlap. In such instances, rendering results differ depending on whether mapping to the gamut of the output device (e.g., a printer) before performing the alpha blending for the rendering commands, or performing alpha blending after mapping to the gamut of the output device. However, there is no single factor which determines which timing for gamut mapping would be better. Rendering results are affected by the colors and alpha values specified in the rendering commands, the output device, profiles used at the time of gamut mapping, rendering intent, and so forth.
Also, in the event that a paint command in the PDL document includes gradient, gradient rendering is necessary. In this case as well, rendering results differ depending on whether mapping to the gamut of the device is performed before performing gradient rendering, or performing gradient rendering is performed before mapping to the gamut of the device. As can be seen here, whether to perform color matching before or after certain types of rendering such as alpha blending and gradient needs further consideration.

Imaging device, control method, and program for rendering data and performing color matching


A paper feed device for a duplex printing apparatus. The paper feed device includes a hinge link coupled to an end of a solenoid, an arm link extended upwards from the hinge link, a reverse guide coupled to the arm link by a guide hinge, a vertical link coupled to one side of the hinge link by a hinge, and a plurality of gears for changing the turning direction of rollers according to a print mode.

1. Field of the Invention
The present invention relates to a duplex printing apparatus, and more particularly, to a paper feed device for reversing a paper feed path for duplex printing.
2. Description of the Related Art
An existing type of duplex printing apparatus includes a main body and a duplex unit installed at one side of the main body. A first delivery roller and a first feed roller are respectively installed at the upper and lower sides of the duplex unit. A driving motor connected to drive the first delivery roller is installed at the inner side of the duplex unit. A solenoid is installed under the driving motor.
When the duplex unit is attached to the main body, the first delivery roller and the first feed roller respectively touch a second delivery roller and a second feed roller installed at corresponding portions of the main body, thereby forming one paper feed path. A central rod of the solenoid moves outward to push an upper portion of a reverse paper guide during simplex printing, and moves inward to release the reverse paper guide during duplex printing.
For simplex printing, a sheet picked up by the revolution of a pickup roller from a paper cassette is fed to a developing unit through a paper guide. An image is formed on one (front) side of the sheet while the sheet passes between a photoconductive drum of the developing unit and a fixing roller. The image is fixed on the sheet when the sheet passes between a heating roller and a pressure roller. Thereafter, the sheet passes through the upper side of a reverse paper guide. The sheet fed along a paper feed path is discharged to the exterior of the main body by the revolution of first and second exit rollers.
For duplex printing, the central rod of the solenoid is retracted. The sheet, printed on the front side, is fed between the delivery rollers through the lower side of the reverse paper guide. The sheet is sensed by a sensor and the delivery rollers are driven in reverse by the driving motor. Then the sheet is fed between the first and second feed rollers along a reverse paper feed path. The sheet is fed between third and fourth feed rollers and is again picked up by the pickup roller. Thereafter, the image forming process for the back side of the sheet is performed.
The duplex printing unit required for duplex printing has a driving motor for driving the delivery rollers and a solenoid for controlling the reverse paper guide. Since the duplex unit includes a driving motor and a number of rollers, its cost is high and its internal construction becomes complicated. Therefore, the duplex unit is not included with the main body of the duplex printing apparatus as standard equipment, but rather is installed as an accessory at one side of the main body as needed by the user.
Other examples of apparatus for duplex printing can be seen in the following U.S. patents. U.S. Pat. No. 4,835,567 to Ogata entitled Paper Re-Feeding Apparatus Of Image Forming Apparatus discusses duplex copying involving guiding the paper through a gate downward by a turn unit onto a stacker with other sheets, where the paper is picked up, sent through switchback rollers and guided by a gate to the developing and fixing units where the paper is printed on the other side. This apparatus has two motors, and requires the activation of several gates as well as stopping and reversal of two pairs of rollers to achieve duplex printing.
U.S. Pat. No. 4,928,127, to Stemmle, entitled Sheet Circulation in a Duplex Printer, discusses a duplex printing apparatus involving the use of reversible rollers. In this design, however, the reversing rollers also serve as discharge rollers, requiring that the duplex printed sheet be partially ejected on the discharge tray during duplex printing. This can cause problems due to interaction with sheet already lying in the discharge tray.
U.S. Pat. No. 4,928,150, to Hatta, entitled Copy Apparatus Having Plural Copy Sheet Discharge Trays for Different Sized Copy Sheets, describes a duplex copying machine which uses reversing rollers partially ejecting the sheet onto a discharge tray to redirect the sheet for the second-side printing. Again, there are potential problems with interactions with sheets on the discharge tray. A solenoid is required to activate the reversing rollers, and the mechanism of this activation is not disclosed.
U.S. Pat. No. 5,055,885, to Yoshikado, entitled Picture Image Forming Equipment, describes a duplex device and in particular the gate where the image-forming channel, paper-discharging channel and paper-reversing channel meet. This apparatus, however, requires a pair of reversing rollers and a lever as part of the gate mechanism, possibly adding to the complexity of the apparatus.
U.S. Pat. No. 5,081,508, to Kotani et al., entitled Paper-Jam Detecting Device, describes a duplex printing apparatus in which the reversing rollers discharge the paper onto the discharge tray. The patent deals with a device for detecting the paper jam caused when the paper is partially ejected and then reversed back for duplex printing, but in the process adheres to papers already in the tray. This device is thus an added layer of complexity to solve a problem created by a certain duplex printing arrangement.
U.S. Pat. No. 5,448,348, to Azeta, entitled Image Forming Apparatus Having A Sheet Material Transport Device, describes a duplex printing apparatus which during duplex printing partially discharges the paper onto the discharge tray before reversing. Again, this device suffers from the problems associated with partial discharge of the paper onto the discharge tray. Additionally, the reversal step requires reversing the motor and changing the position of a flapper.
Based on my observation of the art, I have decided that what is needed is a duplex printing apparatus where the duplex printing mechanism is of simple design and low cost, so that duplex printing can be incorporated cheaply as standard equipment. In particular, it is desirable to avoid reversing the main motor or to have an extra motor to achieve duplex printing.

Paper feed device for duplex printing apparatus


A cage for housing laboratory animals, said cage comprising a tray and a cover which can be removed and switched between a first closing position, in which it is positioned on said tray thus stopping the access to the internal space delimited by said tray, and a second opening position, in which said internal space may be accessed.

To date, the use is widespread of cages for housing laboratory animals such as for example, small rodents or the like, the cages having variable sizes and shapes according to the number of animals to be housed and the conditions to be ensured to the animals themselves. For example, the use is widespread of "ventilated" cages, namely of cages in which a flow of forced air taken from a main circuit is caused to circulate.
However, in addition to specificities provided according to needs and/or circumstances, the cages of known type or at least those most commonly used essentially comprise a tray designed to contain the litter and a cover (also called top hereinafter); moreover, there is usually housed a third component in the tray, the trough, which is designed to contain the food in accessible position for the animals and so that the food does not come into contact with the litter. Finally, a bottle with the drinking water may be prepared inside the cage or also outside and resting on the cover.
The cover or top is positioned above the tray (and possibly fastened to the tray by means of suitable closing means such as clips or the like) and the desired seal is ensured due to a seal positioned between the two elements so that the tray-cover system is adequately isolated from the external environment, where the users of the housing operate, thereby avoiding contaminations both of the housing towards the inside of the cage, and from the inside of the cage towards the housing or external environment.
It indeed is to be considered that in most cases, the housing relates to "clean" animals, in particular called "SPF", specific pathogen free, wherein the volume and the inner surfaces of the cage in the case of "clean" animals are kept and are considered "clean", while everything outside the cage, including the external surface of the cage itself, is considered potentially "dirty" and contaminated.
To the contrary, the opposite concept applies in the case of potentially contaminated animals, in particular from a microbiological viewpoint, wherein t everything inside the cage is considered "dirty" and therefore potentially contaminating for the outside, including the operators.
In both cases, however, the primary need arises to avoid the exchanges and/or mixtures (in particular microbiological contaminations) of what is confined inside the cage and what is outside thereof, thereby maintaining the concept of aseptic conditions.
Therefore, it is apparent that all the operations requesting opening the cage, and in particular removing the cover, are to be carried out according to methods such as to avert the aforesaid mixtures and therefore any contamination of the cage and of the accessories therein and of the animals, but also of the external environment and in particular, of the operators. Such operations comprise for example, but not exclusively, changing the cage (in order to put the animal in a new tray with clean and dry litter, new food and sometimes fresh water), taking and relocating the animals according to the gender and before they reach reproduction maturity, wherein removing the cover is required also in the case of "procedures", such as for example, specific experiments, weighing the animals, injecting and/or taking samples of biological liquids, diagnostics, health check-ups, surgical interventions, etc., and wherein according to the most common methods implemented, the aforesaid operations are carried out in controlled atmosphere in change or microbiological safety cabinets.
Said microbiological safety cabinets, also more simply referred to as cage changes, essentially comprise a work surface struck by a flow of barrier gas, in particular of barrier air, which is perpendicular to the work surface, and possibly by a further flow substantially parallel to the work surface, said work surface being closed on two/three sides by means of fixed walls and accessible from one side at which there is prepared a vertical sliding window, wherein, due to the calibration of the one or more barrier flows taken from peripheral slits provided along the outer perimeter of the work surface, an attempt is made to obtain the desired protection and to avert the aforesaid contaminations of animals and/or cages and/or components and/or operator. In practice, the air walls prevent that which is outside the work surface from contaminating the material inside, and that which is inside and potentially contaminated from being outlet from the laminar flow system and reaching operators and environment.
However, the cages of known type complicate the operations summarized above, even compromising the effectiveness and/or reliability thereof.
Indeed, each of the operations summarized above necessarily requires handling the cover which is in particular to be first removed from the seat thereof on the tray, then positioned on the work surface (generally beside trays or in rear position, paying attention that the internal surfaces do not to come into contact with the work surface or other instruments resting thereon), and finally gripped (ensuring not to touch the inner surface thereof), removing it from the position thereof on the work surface and relocating it in the seat thereof above the tray, thereby reclosing the cage.
However, handling the cover results in a series of drawbacks, essentially due to the limited space on the work surface.
For example, when the cage is changed, both the "dirty" cage, with the animals and the used litter, and the new sterile "clean" cage are necessarily present on the work surface of the cabinet, with the apparent risk of accidental contact between "dirty" components and "sterile" components and that the dirty cover comes into contact with clean components.
In the same way, on occasion of the separation of the genders, there are at least three cages present on the work surface of the cabinet: the original "dirty" one where there is contained the litter and at least two "clean" cages at the sides, each designed to receive the animals of one or the other gender; clearly the risk of contact between dirty components and clean components, in particular between the dirty cover and clean components, is increased here in consideration of the increased number of components to be arranged on the work surface.
In consideration of that disclosed above, the problems and/or drawbacks encountered in handling or managing the cages according to the prior art, in particular the covers of the cages according to the prior art, may be classified in the following groups.
1) Risk of contamination of the parts inside the cage and therefore of the animals, with external parts of the cage or with other objects
2) Risk of contamination of the operators
3) Risk of interrupting the integrity of the laminar flow and aseptic conditions inside the work cabinet
4) Ergonomic risk due to repetitive movements
5) Human risk due to the lack of a clear procedure guiding the operator
Concerning the risks under item 1), same are at least partly due to the fact that, for example, the hands of the operator may accidentally come into contact with the internal parts of the cover during each of the three handling steps described above. Moreover, when the cover is placed on the work surface, the internal parts thereof may touch potentially contaminated parts such as external parts of the cage itself, the work surface, containers, potentially contaminated test tubes or bottles present within the laminar flow. Finally, it is worth noting that such operations become difficult by the obligation—or at least the opportunity—for the operators to wear gloves, which decrease the friction and sensitivity of the operator's hands, by the minimal spaces inside of which the protection is ensured, and also by the front safety glass which certainly limits the freedom of movement of the arms.
Concerning the risks under item 2), it is worth noting that while the risk in housing generally is associated with the contamination of the animals by pathogens introduced by the operators or already present in the rooms of the housings, the same potential problems described above could result in the contamination of the operators and of the surrounding environment by animals that might host microbiological agents.
Concerning the risks under item 3), it is worth noting that as described above, the restricted area of the work surface often is crowded or occupied because, in addition to the trays being changed, there may be present a plurality of tools useful for the operations, such as containers for disinfectant and/or for the food, bottles for the water, test tubes, cups for microbiological screening, etc.
Such objects are to be carefully positioned inside the sterile area because if they are even briefly positioned outside during the handling and then used, they themselves could become contaminated or contaminate the environment; moreover, such objects may not be positioned along the perimeter of the laminar flow area because by obstructing the air intakes, they could nullify the protection normally ensured by the sterile flow curtain.
Therefore, the risk of human errors which may compromise the required sterility is high.
Concerning the risks under item 4, it is worth noting that even hundreds of cages are changed by a single operator every day in a housing facility: such a procedure results in the repetition of the same movements mainly by the wrist, fingers, elbow and shoulder of the animal care takers, such as opening the cover, positioning it on the work surface generally beside the tray and successively closing it, which result in a rotation of the wrist and of the hand by at least 180 degrees, first in one direction and then in the other. It is known that pathologies such as that of carpal tunnel may affect such operators, also due to these movements.
Finally, concerning the risks under item 5, it is to be noted that regardless of the system and the brand of cage used, no clear procedure for accessing the IVCs exists to date: each facility implements standard operations which tend to minimize the above-described risks, but there is no optimized process recommended by the suppliers because there is no system that simplifies, rationalizes and increases the safety and repeatability of such an operation.
In an attempt to overcome the drawbacks described above and therefore to reduce in particular the risks according to items 1) to 5), support devices have recently been proposed called "top holders", for supporting the cover (top) of the cage when the same is removed from the tray. In use, said supports are in particular positioned on the work surface of the change cabinet and when the cover is removed from the tray, same is positioned on one of them. Therefore, said supports at least partly facilitate the task of the operator, who knows where to position the cover; moreover, they limit the risk of the (dirty) inner surface of the cover coming into contact with clean components and/or being touched by the operator's hands.
However, although the top holders can be appreciated for the aforesaid reasons, they nevertheless have various drawbacks and do not provide a significant and complete solution to the problems disclosed above.
Indeed, also the top holder type systems present on the market are themselves to be positioned in fixed position on the already restricted work surface, thus occupying a portion thereof and restraining the handling of the cages.
Moreover, being placed externally to the cage on the sides or in rear position, they require an even larger handling space for the operator when they are opened and closed, with respect to that available in the absence thereof.
Therefore, it is the main object of the present invention to overcome or at least minimize the problems summarized above and encountered in the prior art.
In particular, it is a first object of the present invention to provide a solution which allows the facilitated handling of the cover of a cage for laboratory animals, thus limiting the risks of contamination. In detail, it is an object of the present invention to propose a solution which allows repositioning the cover by means of operations that are quick, safe and simple to be carried out. In greater detail, it is an object of the present invention to propose a solution which allows the aforesaid repositioning of the cover but at the same time does not complicate the operations of removing the cover, if desired and/or required.

Cover for a cage for laboratory animals, and cage for laboratory animals including said cover


In a mold for producing a disc having a stationary mold half and a movable mold half, an air passageway is provided in the stationary mold half to feed air into a cavity between the mold halves approximate the center of the disc being molded. Further, two air passageways are provided in the movable mold half to feed air into the cavity between the mold halves. One of the air passageways in the movable mold half feeds air into the cavity proximate the center of the molded disc while the second air passageway feeds air into the cavity proximate the outer periphery of the disc on the side toward the stationary disc. The air fed from the second air passageway of the movable mold half flows around the outer periphery of the disc and behind the disc to assist in separating the disc from the movable mold half. Further, a vacuum passageway is provided in the movable mold half leading to the backside of a stamper, mounted to the face of the movable mold half, to prevent air from the second air passageway of the movable mold half from also flowing around the peripheral edge of the stamper and behind the stamper.

1. Field of the Invention
The present invention relates generally to a mold for producing, or molding, a disc and, more particularly, to an apparatus for improving the releasability of the disc from the mold.
2. Description of Related Art
Injection molding apparatus for molding a disc has hitherto been performed in such a manner as shown in FIG. 2. A synthetic resin material is injected through a sprue bushing 4 into a cavity 3 defined by a mirror surface 14 of a stationary mold half 1 and a stamper 13 set on a mirror surface 10 of a movable mold half 2 and is molded as a disc 30.
Further, the releasing of the molded disc 30 from the mirror surface 14 and the stamper 13 has been performed by blowing air from a stationary-side air hole A toward the stationary mold half 1 side of the disc 30 and, at the same time, additional air is blown from a movable-side air hole B toward the movable mold half 2 side of the disc 30. Thus, the disc 30 is released respectively from the stamper 13 and the mirror surface 14 of the stationary mold half 1. Thereafter, an ejection bar 7 is moved by ejector pins 9 to eject and release the disc 30.
Although no influence is exerted on the disc 30 at the time of releasing the disc 30 from the mirror surface 14 of the stationary mold half 1 by blowing air from the stationary-side air hole A, when the disc 30 is released from the stamper 13, by the blowing air from the movable-side air hole B, signal pits on the surface of the stamper 13 offer resistance to the air-blow. Thus, in the course of the disc 30 being released from inside to outside (center hole to outer edge), that is, before the air blown from the movable-side air hole B completely reaches around the outermost periphery of the disc, the ejection bar 7 starts to operate.
As a consequence, a boundary line of the air that defines reached and unreached portions between the disc 30 and the stamper 13 appears on the disc. This often results in the appearance of stains on the disc.


A locator is for aligning cables which are configured to be connected with a circuit board having an accommodated portion. The locator comprises at least a main portion which extends in a pitch direction. The main portion is, at least in part, formed with at least one circuit board accommodating portion. The main portion is formed with at least one first through hole and at least one second through hole which is different from the first through hole. The at least one circuit board accommodating portion is configured to accommodate the accommodated portion of the circuit board. The at least one circuit board accommodating portion opens at least forward in a front-rear direction perpendicular to the pitch direction. In the pitch direction, the at least one first through hole is provided at a location which is different from a location of the circuit board accommodating portion.

This invention relates to a locator for aligning cables which are configured to be connected with a circuit board.
Referring to FIGS. 15 and 16, JPA2018-152244 (Patent Document 1) discloses a connector 900 which is configured to be connected with a composite cable 950 including a plurality of cables 960. Specifically, the connector 900 comprises a mating portion 910, a circuit board 920, a locator 930 and a back shell 940. The mating portion 910 is configured to be mated with a mating connector, which is not shown in the figure, along a front-rear direction. In the figure, the front-rear direction is a Y-direction. The circuit board 920 is connected with the mating portion 910. The circuit board 920 is formed with a plurality of pads 922. The circuit board 920 is provided with an accommodated portion 924. The locator 930 has a circuit board accommodating portion 932 and a plurality of through holes 934. Specifically, the circuit board accommodating portion 932 opens forward. In the figure, forward is a negative Y-direction. The accommodated portion 924 of the circuit board 920 is accommodated in the circuit board accommodating portion 932 of the locator 930. The cables 960 included in the composite cable 950 are held by the through holes 932, respectively, of the locator 930 and are thereby positioned both in a pitch direction and in an up-down direction. In the figure, the pitch direction is an X-direction while the up-down direction is a Z-direction. A core wire 962 of the cable 960 is connected with the pad 922 of the circuit board 920. The back shell 940 is attached to a rear end part of the mating portion 910 so as to cover the pads 922 of the circuit board 920.
According to Patent Document 1, the cable 960 and the circuit board accommodating portion 932 overlap with each other in the up-down direction at an area rearward of the through hole 934 of the locator 930. Thus, as an outer diameter of the cable 960 becomes larger, the through hole 934 must be positioned away from the circuit board accommodating portion 932 in the up-down direction in consideration with a positional relationship between an outer periphery of the cable 960 and the circuit board accommodating portion 932. Consequently, according to Patent Document 1, as the outer diameter of the cable 960 becomes larger, the locator 930 has an increased size in the up-down direction and thereby the connector 900 has an increased size in the up-down direction.

Japan Aviation Electronics Industry, Limited


The addition of a nucleating or coalescing agent (e.g., urea) to liquid ammonia reduces the size and persistence of a deadly, fog-like cloud of ammonia droplets that tend to form when liquid ammonia is accidentally released to the atmosphere. In addition, high purity ammonia is obtained by evaporating ammonia from the ammonia- and nucleating agent-containing composition.

This invention relates to transporting and storing liquid ammonia and, more specifically, to limiting the risk of harm in the event of an accidental liquid ammonia spill. (As used in the specification and claims, the term "liquid ammonia" means any grade of ammonia existing in the liquid state that boils at or below ambient temperature and pressure, i.e., about 101.3 kpascal (about 1 atm) and about 20.degree. C. (about 68.degree. F.)).
Anhydrous liquid ammonia is used in massive quantities world-wide for many industrial and agricultural purposes. (As used in the specification and claims, the term "anhydrous liquid ammonia" means liquid ammonia that is at least about 98 weight percent ammonia and up to about 2 weight percent water. Under one commercial standard, anhydrous liquid ammonia transported by pipeline must be at least 99.5 weight percent ammonia. Anhydrous liquid ammonia is thus substantially water-free, but nevertheless often contains a small proportion of water, e.g., about 0.1 to about 0.5 weight percent, purposely included to inhibit corrosion of storage vessels and pipes.) A gas at ambient temperatures and pressures, anhydrous liquid ammonia is normally shipped and stored as a liquid, either in pressure vessels at ambient temperature, e.g., at about 20.degree. C. (about 68.degree. F.) and about 928.7 kpascal (about 120 psig), or in refrigerated vessels at ambient or nearly ambient pressure, e.g., at about -33.degree. C. (about -27.4.degree. F.) and about 104.8 kpascal (about 0.5 psig). It is transported in bulk in ships, barges, and railroad tank cars, and in tank trucks on public roads and highways. It is frequently stored in large quantities at industrial sites in populated areas and is frequently used as the working fluid in large refrigeration systems. It is now coming into wider use for the removal of NOx from flue gas at power generating stations in urban areas.
Anhydrous liquid ammonia is an extremely hazardous, toxic, and volatile material. In the event of an accidental discharge, it can cause immediate death to humans and animals and rapid death to trees and plants.
Both anhydrous liquid ammonia and very concentrated aqueous liquid ammonia display a deadly characteristic which substantially increases the risk of widespread injury and death in case of a spill. Specifically, upon sudden release to the atmosphere, as might occur in a train wreck or a traffic accident, the ammonia forms a cloud made up of an aerosol fog of liquid ammonia droplets. Unlike gaseous ammonia, which, though toxic, is lighter than air and quickly dissipates to harmless concentrations, the cloud can persist for a surprisingly long time, as long as several hours, before it finally disappears. The cloud is typically heavier than air and tends to drift along the surface of the earth, i.e., the ground or the surface of a body of water. The cloud moves with the wind and can sweep over a total area, i.e., a "footprint," much larger than the area covered by the cloud at any one moment. Contact with the cloud is instantly incapacitating, and a single breath can be fatal.
Substantial numbers of bulk shipments of anhydrous liquid ammonia routinely move through or near densely populated areas. It is estimated that an anhydrous liquid ammonia spill from a truck trailer (about 18,143.7 kg (about 40,000 lb) liquid ammonia capacity) would generate a cloud having an average lethal footprint of about 1173.6 are (about 29 acres), that is, an area of about 1173.6 are (about 29 acres) in which the concentration of ammonia would reach a lethal level, about 0.5 percent, before the cloud eventually dissipated.

Method for reducing the risk in transporting and storing liquid ammonia


The present invention provides methods and apparatus for determining the location of an apparatus in a wellbore. The method includes lowering the apparatus with a conveying member and measuring a parameter associated with the conveying member. Thereafter, the measured parameter is used to determine the location of the apparatus as well as other conditions in the wellbore. The apparatus includes a conveying member operatively connected to an object released downhole. The apparatus may also include a dispensing apparatus coupled to one end of the conveying member. Preferably, the conveying member is a fiber optics line capable of transmitting optical signals. Other types of conveying members include a wire, a tube, and a cable. Additionally, a sensor may be disposed on the object and connected to the conveying member.

1. Field of the Invention
The present invention generally relates to apparatus and methods for completing a well. Particularly, the present invention relates to apparatus and methods for cementing operations. More particularly, the present invention relates to apparatus and methods for locating a cementing apparatus in the wellbore. More particularly still, the present invention relates to apparatus and methods for determining the amount of cement displaced.
2. Description of the Related Art
In the drilling of oil and gas wells, a wellbore is formed using a drill bit that is urged downwardly at a lower end of a drill string. After drilling a predetermined depth, the drill string and bit are removed and the wellbore is lined with a string of casing. An annular area is thus formed between the string of casing and the formation. A cementing operation is then conducted in order to fill the annular area with cement. The combination of cement and casing strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the casing for the production of hydrocarbons.
It is common to employ more than one string of casing in a wellbore. In this respect, a first string of casing is set in the wellbore when the well is drilled to a first designated depth. The first string of casing is hung from the surface, and then cement is circulated into the annulus behind the casing. The well is then drilled to a second designated depth, and a second string of casing, or a liner, is run into the well. The second string is set at a depth such that the upper portion of the second string of casing overlaps the lower portion of the first string of casing. The second liner string is then fixed or "hung" off of the existing casing. Afterwards, the second casing string is also cemented. This process is typically repeated with additional liner strings until the well has been drilled to total depth. In this manner, wells are typically formed with two or more strings of casing of an ever-decreasing diameter.
The process of cementing a liner into a wellbore typically involves the use of liner wiper plugs and drill-pipe darts. Plugs typically define an elongated elastomeric body used to separate fluids pumped into a wellbore. A liner wiper plug is typically located inside the top of a liner, and is lowered into the wellbore with the liner at the bottom of a working string. The liner wiper plug has radial wipers to contact and wipe the inside of the liner as the plug travels down the liner. The liner wiper plug has a cylindrical bore through it to allow passage of fluids.
Typically, the cementing operation requires the use of two plugs and darts. When the cement is ready to be dispensed, a first dart is released into the working string. The cement is pumped behind the dart, thereby moving the dart downhole. The dart acts as a barrier between the cement and the drilling fluid to minimize the contamination of the cement. As the dart travels downhole, it seats against a first liner wiper plug and closes off the internal bore through the first plug. Hydraulic pressure from the cement above the dart forces the dart and the plug to dislodge from the liner and to be pumped down the liner together. At the bottom, the first plug seats against a float valve, thereby closing off fluid flow through the float valve. The pressure builds above the first plug until it is sufficient to cause a membrane in the first plug to rupture. Thereafter, cement flows through the first plug and the float valve and up into the annular space between the wellbore and the liner.
After a sufficient volume of cement has been placed into the wellbore, a second dart is deployed. Drilling mud is pumped in behind the second dart to move the second dart down the working string. The second dart travels downhole and seats against a second liner wiper plug. Hydraulic pressure above the second dart forces the second dart and the second plug to dislodge from the liner and they are pumped down the liner together. This forces the cement ahead of the second plug to displace out of the liner and into the annulus. This displacement of the cement into the annulus continues until the second plug seats against the float valve. Thereafter, the cement is allowed to cure before the float valve is removed.
During the cementing operation, it is desirable to know the location of the second plug/dart in the wellbore. Generally, the position of the plug will indicate the amount of cement that has been displaced into the annulus. If insufficient cement is displaced ("underdisplacement"), cement will remain in the casing. If too much cement is displaced, ("overdisplacement"), portions of annulus will not be cemented.
One method of determining the plug location is by measuring the volume displaced after the second plug is released. Then, the volume displaced is compared to the calculated displacement volume based upon the dimensions of the casing or drill pipe. A second method is attaching an indication wire to indicate that a plug has been released. The indication wire is usually 2 to 3 feet in length. A third method is using mechanical flipper indicator. In this method, a lever is disposed below the plug container. A released plug will shift the lever when the plug travels by it. A fourth method is using electromagnetic or magnetic signals. Generally, an identification tag is attached to the plug or dart. A detector located below the cementing head picks up the signal when the plug passes to indicate that the plug has been launched.
There are drawbacks to using these methods to determine plug location. For instance, the displacement method is not very accurate and does not give a positive indication that the plug is moving at the same rate as the fluid being pumped behind the plug. Casing and drill pipe are generally manufactured to dimensional tolerances that could result in a substantial difference between the calculated displacement volume and the actual displacement volume. Further, fluids are subject to aeration and compression during the operation, thereby affecting measured volume. Indicator wires and mechanical flipper indicators only indicate that the plug has been released, not the location thereof. Finally, the signal detectors cannot track the plug for long distances and only indicate that the plug has moved past the detection device.
There is a need, therefore, for an apparatus for locating a plug in the wellbore. Further, there is a need for an apparatus for determining the amount of cement that has been displaced. The need also exists for a method for completing a cementing operation.


A mobile communication terminal provided with a tuning function, which saves a player the trouble of carrying around a tuning meter or the like and facilitates the tuning of instruments. A user designates a reference pitch stored in a memory, and inputs the sound of an instrument or a voice into a microphone. A synthesizer generates a sound that most approximates the sound input through the microphone according to the reference pitch designated by the user. The sound generated by the synthesizer is compared with the sound input through the microphone, and the result of the comparison is displayed on a display.

Before playing an instrument or singing, the player, singer, etc. adjusts the pitch for playing or singing musical notes correctly based on a reference tone using a tuning fork or a tuner.
Besides, when playing an instrument, the player or the like has to tune the instrument in advance so that it plays at the correct pitch. In this case, the player tunes the instrument while checking the pitch of each note with a tuning meter. Consequently, the player is required to carry the tuning meter into a venue for a concert each time he/she gives a performance as well as to take care of it.
If a cellular phone, which has been in widespread use, has a tuning function as for example described in Japanese Patent Application laid open No. 2002-49368, the player need not carry around the tuning meter.

Mobile communication terminal with audio tuning function


A single electronic module includes a autoregulating circuit that regulates an oscillation frequency of an oscillating mechanical system, such as a balance having a balance spring. A piezoelectric element is mounted on the oscillating balance spring and connected to the autoregulating circuit to generate an alternating voltage. The autoregulating circuit rectifies the alternating voltage and regulates the alternating voltage frequency. The rectified voltage is stored in a capacitor to power the autoregulating circuit. The autoregulating circuit includes an oscillator connected to a mirco-electro-mechanical system (MEMS) resonator that supplies a reference signal, and compares the frequency of the alternating voltage to the reference signal frequency. The autoregulating circuit supplies frequency adaptation signal to the piezoelectric element according to the result of the comparison, in order to regulate the oscillation frequency of the balance.

In the field of horology, the oscillating mechanical system may be a balance on which a balance spring is mounted, one end of which is secured to the rotating balance staff and the other end of which is secured to a fixed element of a bottom plate. The oscillation of the mechanical system is maintained via an energy source which is generally mechanical. This energy source may be, for example, a barrel driving a gear train with an escape wheel cooperating with a pallet lever. This rotating pallet lever for example actuates a pin secured in proximity to the rotating balance staff. The balance with the balance spring may thus form a regulating member of a timepiece movement. This oscillating regulating member determines the driving speed of the gear train with the escape wheel leading to the time indicator hands.
In order to precisely regulate the oscillation frequency of the oscillating mechanical system, the length of the spring may be adapted or a weight may be added or removed from the external circular part of the balance. However in the case of a wristwatch, all these additional regulating elements occupy considerable space inside the watch case, and lead to relatively long manufacturing time and high cost. This thus constitutes drawbacks.
In a mechanical or electromechanical watch, it is known to regulate the rotational speed of an electric generator connected to the spiral-shaped spring barrel to mechanically drive the hands of the watch via a gear train. The electric generator generates an alternating voltage, which is rectified by means of a rectifier of an electronic regulating circuit. The function of this regulating circuit is to control the rotational speed of the generator so that the time indicator hands can be moved as a function of the correct current time indication. A transistor of the regulating circuit can short-circuit the generator at determined time periods so as to brake the generator and thus regulate the rotational speed. EP Patent Application Nos. 0 762 243 A1 or 0 822 470 A1, which disclose a watch provided with this type of regulating circuit may be cited in this regard.
The aforementioned electric generator includes rotating permanent magnets and a coil opposite the magnets, capable of providing an induced alternating voltage. It can be complicated to make this type of generator and regulating circuit. A large number of elements generally have to be provided to design said generator with the regulating circuit. Moreover, the magnetic field of the rotating magnets may cause interference in some nearby ferromagnetic parts. This therefore constitutes several drawbacks.
Instead of an electric generator formed of rotating permanent magnets and a coil generating an induced alternating voltage, FR Patent No. 2 119 482 has already proposed providing an oscillating mechanical system with a piezoelectric element. This piezoelectric element is preferably arranged on a balance spring connected to a balance. To achieve this, films of piezoelectric material (PZT) are deposited on most of the length of the spring and on an inner face and outer face of said metal spring. A voltage converter supplies an alternating voltage to the piezoelectric element to alternately generate a compression force and an extension force on the spring in order to regulate the oscillation of the balance connected to the balance spring. However, in this Patent document, no mention is made of regulating the oscillation frequency of the balance with the balance spring using an autoregulating circuit, which is a disadvantage.
Regulating the oscillation frequency of a balance combined with a piezoelectric balance spring as the alternating voltage generator is known from JP Patent Application No. 2002-228774. The alternating voltage is rectified in a rectifier which comprises at least two diodes and FET transistors controlled by the electronic regulating circuit. The rectified voltage is stored at least in a supply voltage storage capacitor. The electronic circuit may be powered directly by the alternating voltage from the generator, which has been rectified and stored in the capacitor. The piezoelectric generator is of the bimetal type (PZT). To regulate the oscillation frequency, a comparison is made between a signal at a reference frequency supplied by a quartz oscillator circuit and the alternating signal from the generator. With the proposed electronic circuit it is not possible to devise a very compact oscillating mechanical system with the regulating circuit in a manner that is easily accomplished, which constitutes a drawback.

Circuit for autoregulating the oscillation frequency of an oscillating mechanical system and device including the same

The Swatch Group Research and Development Ltd.