A turbine gas flow meter (10) includes a meter body (12) including an inlet portion (24) having an inlet body (32) mounted therein, with an exit end (30) of the body inlet portion being defined at an internal plenum (22) of the meter body, and a removable turbine meter measuring module (44) including a rotor assembly (48) which is inserted into the plenum with an inlet end (127) of the rotor assembly and the exit end of the inlet portion defining an interface therebetween. A closed space (114) is formed about the rotor assembly within the plenum between an inner wall (106) of the body and outer walls (116, 118) of the rotor assembly. An axial gap (128) between a surface (130) of the rotor assembly inlet end and a surface (132) of the body inlet portion exit end, and/or radial notches in either of the surfaces (130, 132), provide fluid pressure communication from the interface to the closed space. A pressure tap (138) extends through the body into the closed space for measuring pressure within the closed space.

Axial flow turbine meters are widely used for measuring flow of gas by which to determine gas usage and the like. To this end, an axial flow turbine meter includes a meter body having an inlet end connected to a gas supply line or pipe and an outlet end which may be connected to a gas delivery line or pipe. Inside the meter body at the inlet end is a cone or bullet-shaped inlet body, the exit end of which is placed adjacent to a turbine rotor assembly having at least first rotor which rotates in response to gas flowing thereover so as to provide a measure of the gas flow. A second rotor may be positioned downstream of the first rotor for more accurate or calibrating measurements. Blades on the rotor periphery cause the rotor to rotate. To focus the flowing gas on the blades, the inlet body conditions the flowing gas to change it from the space of the supply pipe to the annular path.
In order to provide reliable measurements, certain correction factors must be taken into account. In particular, the pressure and temperature of the gas passing through the meter are usually not equal to the standard pressure and temperature upon which gas suppliers base their pricing structure, and therefore the actual volume of gas indicated by the meter is corrected to standard conditions in order to determine the total price for the gas used.
It is desirable for a gas flow meter to measure flow volume with a high degree of accuracy, since flow volume errors of as little as a half a percent, occurring over a significant time period, can result in a substantial revenue error in the total gas usage. The gas supplier accordingly may significantly overcharge or undercharge the user. It will also be appreciated that a gas meter of a given design may be placed in a variety of types of installations whose usage rates may vary substantially from each other, and furthermore, there frequently is a significant variation in usage rates even for a particular installation as demand rises and falls in accordance with need. Thus, the goal for the designer of a gas flow meter is to design a meter which has a high degree of accuracy and repeatability over a wide range of flow rates.
In order to achieve accurate measurement of gas flow, it is standard practice to calibrate each meter by comparing the meter's indicated flow volume to a known flow volume and repeating this test over a range of flow rates so as to develop a "calibration curve" representing the meter's flow volume error in percent. One calibration method commonly used is to place the meter to be calibrated in series with a highly accurate flow measurement device such as a "flow prover" in a test line and to flow gas through the test line. At a given test point, the actual flow volumes of the test meter and the flow prover are acquired and each is corrected to standard conditions (e.g., 1 bar pressure and 15 degrees C.) based on measurements of the pressure and temperature of the gas entering the test meter and the pressure and temperature of the gas entering the flow prover. This test is repeated over a range of flow rates to arrive at the test meter's calibration curve. Using this curve, for any indicated flow rate, an accurate flow volume can be determined.
Thus, it will be appreciated that an accurate measurement of gas flow volume is highly dependent on accurate measurement of the pressure of the gas entering the meter, both at the time of meter calibration and at the time of usage. For instance, a pressure measurement error of one inch of water can translate into a 0.25 percent error in a meter's calibration curve.
During field use, one of the factors affecting the accuracy of a meter's calibration is variation in the configuration of the environment in which the meter is installed, from one installation to another. In one known turbine meter, the turbine rotor assembly and the inlet body form a complete or self-contained unit or module which is removable as a unit from the meter body for maintenance or calibration. The combined inlet body and rotor assembly are contained within a cylindrical sub-housing that is inserted axially into the meter body through the inlet end thereof. An annular pressure space is formed between the sub-housing and meter body radially outwardly of the inlet body. The pressure space is sealed from the rest of the meter so as to be confined over the inlet body and one or more apertures are formed in the sub-housing over the inlet body by which to permit pressure communication from the flow path over the inlet body to the pressure space. A sensor coupled to the pressure space may be used to obtain a readout of the pressure therein.
The plurality of apertures through the sub-housing require manufacturing time for machining, deburring, inspection, and testing. Moreover, in order to create the pressure space, the module must include the sub-housing. Thus, replacement of a bad rotor assembly results in disconnecting the gas line(s) from the meter body to remove the module and necessitates removal of the entire module, along with the inlet body, the latter being a component that is not prone to failure. The result is a less efficient and more costly system to build and maintain.
In other turbine gas meters, the inlet body is not part of the removable measuring module, but rather remains with the meter body, since it is a stationary part which is durable and seldom requires maintenance or replacement. For instance, in a prior meter design by the assignee of the present application, a measuring module including a separate turbine rotor assembly is removable from and insertable into an internal plenum within the body and adjacent to an exit end of the inlet body through a lateral opening in the body. The measuring module includes a main rotor which is carried within a generally cylindrical main rotor carrier and a sensing rotor which is carried within a generally cylindrical sensing rotor carrier, the two rotor carriers being connected to each other and to a top plate which covers the lateral opening in the body and supports a mechanical counter mechanism as well as connections for various sensors. To remove the module, the top plate is disconnected from the body, and the entire top plate and rotor assembly is removed, without having to disconnect the body from the gas supply line. The body includes an inlet body in the form of a nose cone with flow straightening vanes, but these remain with the body when the measuring module is removed.
With the stand-alone rotor assembly, calibration of the measuring module is performed independent of the inlet body and flow straightening vanes. Further, the measuring module can be removed from the body without disconnecting the body from the gas supply line. However, because the inlet body may have a substantial effect on the flow conditions, such as the static pressure, at the inlet to the measuring module, it is necessary to accurately measure and account for the static pressure during calibration and field use of the measuring module. To this end, pressure measured in the inlet flowpath above the inlet body is not a reliable or accurate source for calibration of the module since the module and inlet body are independent. Thus if a measuring module is calibrated in a test setup, the module may not be accurately calibrated for field use where the inlet body and other aspect of the meter body in the field may vary slightly from the test set-up unit. For example, the location of the sensor may vary from meter to meter or the size and spacing of the components may vary slightly from meter to meter. As a consequence, there is a marked risk of degraded repeatability and interchangeability of measuring modules from one meter body to another.
To overcome problems associated with measuring pressure over the inlet body, pressure measurements have been focused on the rotor turbine module assembly itself. To this end, pressure is measured at the inlet to the main rotor via a pressure tap machined through the main rotor carrier just upstream of the main rotor blades. The pressure tap is connected by flexible tubing to a fitting that extends through the top plate. A pressure sensor may be connected to the fitting. Thus, the pressure tap location is consistent from meter to meter and moves with the module. By measuring pressure close to the main rotor within the rotor assembly and making the pressure measurement system part of the removable measuring module, the same calibration curve can be used for the measuring module even when it is placed in different bodies.
This pressure measurement system has been found to be satisfactory up to gas flow velocities of about 110 feet per second. However, for reasons that are not known, it has been discovered that the accuracy of the pressure measured within the rotor assembly ahead of the main rotor begins to deteriorate at higher flow rates. For example, at 160 feet per second flow velocity, the meter calibration curve determined by using this pressure measurement is about 0.5 percent in error. Additionally, it has been found that pressure measurements taken over the inlet body exhibit inconsistencies with different measuring module/body combinations.
Accordingly, there has been a need for a pressure measurement system for a turbine flow meter module in which pressure can be accurately measured for a wide range of flow rates and which permits interchanging the meter in various meter bodies without having to recalibrate the meter each time it is placed in a new meter body.

Pressure measuring system for gas flow meter


Disclosed is a system, method, and program for generating a data structure for use by a computer in determining a location of boundaries in text. The data structure is initialized and at least one regular expression is processed. Input characters in the at least one regular expression are then processed to determine at least one transition to at least one state. A determination is then made as to whether one input character would cause a non-deterministic transition. Additional states are added to the data structure to transform the non-deterministic transition to a deterministic transition.

1. Field of the Invention
Preferred embodiments provide a method, system, and program for generating a deterministic table to determine boundaries between characters.
2. Description of the Related Art
Computer text editors display words on a page such that characters within each word remain together. Words are typically separated by a whitespace or a punctuation, such as a period, comma, semi-colon, etc. During operation, a word processor may have to determine morphological boundaries in text, such as characters, words, sentences or paragraphs. For instance, when displaying strings comprising unseparated words on a line, the word processor may have to determine where to break the string between the unseparated words or, during operation of a spell check program, the word processor must go from the beginning to the end of the document to locate each word on which to perform a spell check operation. One program used to locate word, sentence or character boundaries in text is the International Business Machines Corporation (xe2x80x9cIBMxe2x80x9d) BreakIterator. The BreakIterator program is a class in the Java Class Libraries, which is part of both the Java Developer Kit (JDK), which comprises programming tools for developers to create Java programs, and the Java Runtime Environment (JRE), which is the application to execute Java programs.** BreakIterator uses a state machine table to process each character to determine whether a morphological boundary has been reached.
** Java is a trademark of Sun Microsystems Inc.
A state machine provides an output based on one or more received inputs. A state machine in effect memorizes previous inputs to determine the current output. A non-deterministic state machine can indicate a multiple number of output states for a given input, whereas a deterministic state machine indicates only one output state given the input. The behavior of a deterministic machine can be defined in a state transition diagram, such as that shown in FIG. 1, which illustrates an example of the type of state machine BreakIterator uses.
FIG. 1 illustrates a state transition diagram, which shows all possible states as circles. The circles are connected by arrows representing possible state transitions. The arrows are labeled by the input values that cause the particular transition, e.g., the arrow from state 2 to state 4 indicates that the input is a digit. A double circle represents an accepting state. If the current state is an accepting state, and the next character in the text does not indicate a transition along any of the transition lines, than a word boundary is placed after the accepting state position. A single circle indicates a non-accepting state. If the current state is one of the non-accepting states, and the character in the next position does not provide a transition to an accepting state, then the end of word boundary is placed at the position following the previous accepting state from which the transition to the current non-accepting state occurred. For instance, if the current state is a letter (2), then receiving another letter will cause a transition (letter) back to the letter state (2), receiving a digit will cause a transition (digit) to the digit (4) state, or receiving a word punctuation will cause a transition (wordPunct) to the word punctuation state (3). Word punctuation refers to punctuation marks that are acceptable for use within words, such as hyphens and apostrophes. Digit punctuation refers to punctuation marks acceptable within numbers, such as a decimal point, comma, etc. If the current state is a digit (4) and number suffix is the next input character, then the transition (numSuffix) will lead to the number suffix state (6). Because there is no transition possible out of the number suffix state (6), a word boundary is placed thereafter. Alternatively, at the punctuation state (3 and 5) from the letterstate (2) or the number state (4), there is no transition if the next character is further punctuation. This means that at the punctuation non-accepting states (3 and 5), if the next character is punctuation, then a word boundary will be placed at the previous accepting state, which is the previous letter (2) or number (4) state, respectively, from which the non-accepting punctuation state (3 or 5) was reached. After placing a word boundary, control proceeds to the start state (1) to process the next characters in the text to determine a next word boundary.
FIG. 2 illustrates a representation of the state machine in FIG. 1 as a two dimensional array that the text editor program uses to determine word boundaries. The shaded rows indicate accepting states. A row indicates a current state and the column indicates an input at a current state. The circles representing states in FIG. 1 are labeled with numbers indicating the corresponding row representing that state in the table in FIG. 2. The value in the cell indicates the next row or state based on an input of the column value. For instance, values in row 1 are at the start state. The cell value in row 1, column 1 indicates determining a letter character following the start position, which causes a transition to row 2, which represents the transition 2 to the letter state. At a letter state, which is indicated as row 2 in the table, receiving an apostrophe or other punctuation causes the use of transition 3 to go to the punctuation state, which is represented by row 3 in the table in FIG. 2. If a letter is received as input in the punctuation state, then transition 2 occurs back to the letter state, which is the value in the first column (the letter column) in row 3. Anything other than a letter at the punctuation state, shown as the other columns in row 3 following the letter (xe2x80x9cltrxe2x80x9d) column, indicates no transition, which causes the insertion of a word boundary. Thus, at a state i, the next position is determined by the value in row i at the column corresponding to the character type at the next position. If the cell correpsonding to row i and the column for the character type in the next position is a number, then the next state is provided at the row corresponding to the number. If the cell with row i and the column corresponding to the next character are empty, then the word boundary has been reached.
In the prior art IBM BreakIterator product, the BreakIterator programmer must manually create and modify the state machine table shown in FIG. 2. Such manual editing of these tables can be time consuming and cumbersome. Thus, there is a need in the art to provide an improved system for generating the state machine table.
To overcome the limitations in the prior art described above, preferred embodiments disclose a method, system, and program for generating a data structure for use by a computer in determining a location of boundaries in text. The data structure is initialized and at least one regular expression is processed. Input characters in the at least one regular expression are then processed to determine at least one transition to at least one state. A determination is then made as to whether one input character would cause a transition to multiple states. If so, additional states are added to the data structure to transform the transition to multiple states to a deterministic transition.
In further embodiments, adding additional states comprises adding an additional state having a same number of output transitions as a number of non-deterministic output transitions from the non-deterministic state.
In still further embodiments, data structures are used to indicate states capable of transitioning to multiple states. In such case, each state having transitions to multiple states is updated to point to a new state providing deterministic transitions to the multiple states.
In certain implementations, the data structure is a table. In such case, initializing the data structure would involve defining columns in the table. Processing the input characters to determine at least one transition to at least one state comprises indicating one row as a decision point. An input character is received and a new row is added to the table for the input character. An input column corresponding to the input character in at least one decision point row is set to point to a row number of the added new row.
Preferred embodiments provide an algorithm for processing a set of regular expressions to generate a deterministic state table therefrom. With preferred embodiments, a word processing application developer need only define a set of regular expressions defining sequences of characters that form a known entity, such as a word, sentence or paragraph. In this way, if a software developer updates, modifies or completely replaces the set of regular expressions, the program may automatically generate a new deterministic state table machine from these regular expressions. Preferred embodiments allow developers to modify the set of regular expressions without having to spend time encoding a state table representing the regular expressions.

Method, system, and program for generating a deterministic table to determine boundaries between characters


A composite color includes a first colored ink and a second colored ink. The first colored ink exhibits a color that is different from that exhibited by the second colored ink. The first colored ink includes pigment particles either formulated at a basic pH so that a surface of the pigment particles carries a net negative charge or formulated at an acidic pH so that a surface of the pigment particles carries a net positive charge; and the second colored ink includes pigment particles either formulated at an acidic pH so that a surface of each of the pigment particles carries a net positive charge or formulated at a basic pH so that a surface of the pigment particles carries a net negative charge. The first colored ink and the second colored ink have opposite charges. The composite color exhibits enhanced color richness when printed on a substrate.

The present disclosure relates generally to composite colors and methods of making the same.
Pigment-based inks generally exhibit good permanence properties and good water fastness properties. These inks may, when printed on some substrates, exhibit poor richness of color. Color richness may be especially difficult to achieve when two different colored inks are used to form a composite color. Efforts to increase the color richness of composite colors have included, for example, decreasing or increasing the amount of fixer ink printed when forming the composite color, and printing the composite color on specially coated papers. Fixer inks may, however, increase the cost associated with printing and may require additional pen nozzles. Specially coated papers may also increase the cost associated with printing.

Composite color and method of making the same

Hewlett-Packard Development Company, L.P.


A fault-tolerant self-indicating surge protector system and methods are presented. An unwanted surge of electrical energy induced by a lightning strike is directed away from a sensitive electrical or electronic component, and the unwanted surge of electrical energy is directed through series connected pairs of varistors. A voltage signal is extracted from a center tap point between the series connected pairs of the varistors, and the voltage signal is monitored for a health of the varistors. A high impedance in a varistor among the varistors is provided for a low voltage across the varistor, and a low impedance in the varistor is provided and the unwanted surge of electrical energy is diverted through the varistor in response to a high voltage across the varistor.

Energy levels produced from lightning, electromagnetic pulses, and electromagnetic discharge play havoc on airplane electrical power, controlling, and indication systems. Lightning effects can penetrate electrical systems on aircraft due to any external connections such as hydraulic tubes, air-data sensors, antennas and electrical cables from engines to the internal electrical wiring bay.

Fault-tolerant self-indicating surge protection system for aircraft


A method for reducing bonding pad loss is achieved using a capping layer when contact openings are etched to the bonding pads, while concurrently etching much deeper fuse openings to the substrate. Bonding pads are used on the top surface of integrated circuit semiconductor chips to provide external electrical connections for I/Os and power. And fuses are used in the underlying insulating layers to remove redundant defective circuit elements and thereby repair defective chips. It is desirable (cost effective) to etch the contact openings in the passivation layer to the bonding pads near the top surface on the chip and to concurrently etch the much deeper fuse openings in the thick underlying insulating layers over the fuses. However, because of the difference in etch depth of the two types of openings, the bonding pads composed of Al/Cu are generally overetched causing bond-pad reliability problems. This invention uses a novel process in which a capping layer, having a low etch rate, is formed on the bonding pads to prevent overetching while the fuse openings are etched to the desired depth in the thicker insulating layers.

(1) FIELD OF THE INVENTION
The present invention relates to the fabrication of integrated circuits, and more particularly to a method for making more reliable bonding pads using a capping layer. This method eliminates the overetching of the bonding pads when the bonding pad openings are etched, while concurrently etching deeper fuse openings in the underlying insulating layers to the polysilicon fuse near the substrate surface.
(2) DESCRIPTION OF THE PRIOR ART
The reduction of the feature sizes of semiconductor devices using advanced semiconductor techniques, such as high-resolution lithography and directional etching, have dramatically increased the device packing density on integrated circuit chips formed on the substrate. However, as the device packing density increases, it is necessary to increase the number of electrical metal interconnect layers on the chip to effectively wire up the discrete devices on the substrate while reducing the chip size. For example, it is not uncommon to use between two and six levels of metal interconnect layers. Typically after completing the multilevel interconnect structure, bonding pads are formed on the top surface of the interconnect structure to provide external electrical connections to the chip. A passivation layer is then applied, such as a phosphorous doped glass, a silicon nitride, a silicon oxynitride layer, or a combination of these layers to passivate the chip from moisture and contamination.
Another concern as the density of the semiconductor devices increases on the chip is that the final product yield for many integrated circuits (chip yield) can dramatically decrease. For example, one circuit device that can experience this yield loss with increased device density is the dynamic random access memory (DRAM) currently having 64 megabits of memory on a chip. After the year 2000 the number of memory cells is expected to increase further to about 1 to 4 gigabits, and high final product yield will be difficult to achieve without utilizing cell redundancy and repair yield methods. One method of overcoming this lower yield on RAM devices is to provide additional rows of memory cells and fusing each row of cells. A laser is then used to open connections (fuses) in the patterned polysilicon layers on the substrate that are used to form the DRAM or SRAM devices. By this means defective rows of memory cells can be disabled and the address decoder circuits can be modified so that spare rows of memory cells are selected instead. To achieve this laser deletion, it is necessary to etch deep openings through the multilevels of insulating layers in the multilevel metal interconnect structure over the fuse portions of the patterned polysilicon layer. It is also common practice in the semiconductor industry to etch the bonding pad openings and the fuse openings using the same masking step to reduce manufacturing cost. Unfortunately, when the fuse openings are etched in the thick multilevels of insulation, the bonding pad openings can be overetched, essentially eroding away a major portion of the bonding pad causing reliability concerns.
To better appreciate this overetch problem, FIGS. 1-3 depict the problem of the prior art and are briefly described. The drawing in FIG. 1 is a schematic cross-sectional view showing a portion of a substrate 10 having an integrated circuit completed up to and including the bonding pad layer. The semiconductor devices formed on the substrate typically include patterned polysilicon layers that also serve as local interconnections which include portions for fuses 14, as shown in FIG. 1. For example, the polysilicon layer can be used to form the gate electrodes for field effect transistors (FETs) or bit lines on DRAM devices. A multilevel interconnect structure 16 is then formed over the devices to complete the electrical interconnections on the chip. Typically the interconnect structure 16 is composed of several layers of patterned metal, such as aluminum/copper (AlCu), with alternating insulating layers, such as silicon oxide (SiO.sub.2) or low dielectric insulators. Metal plugs are formed in the insulating layers as electrical interconnects between metal layers. The details of the interconnect structure 16 are not essential to understanding the problem and are therefore not depicted in detail in the Figs. to simplify the drawings and the discussion. As shown in FIG. 1, the bonding pad layer 18 is typically formed by depositing a multilayer conducting layer such as titanium nitride-AlCu-titanium nitride layers to a thickness of 9000 Angstroms. Bonding pads 18' are then formed by using a patterned photoresist etch mask 20 and conventional plasma etching to pattern the bonding pad layer 18, as shown in FIGS. 1 and 2. The bonding pads 18' are typically used to make external electrical connections to the chip for the I/O signals (input/output signals) and to provide power for the chip. FIG. 2 shows one of the bonding pads 18' making contact to one of the metal plugs 22 in the multilevel interconnect structure 16 as part of the electrical interconnections. Still referring to FIG. 2, a passivation layer 26 is deposited over the substrate to prevent moisture and contamination of the integrated circuits. Typically the passivation layer is composed of a doped glassy a silicon nitride, silicon oxynitride, or a combination of these insulating materials to prevent moisture and/or ion contamination from corroding and electrically degrading the semiconductor devices, respectively.
Still referring to FIG. 2 and more specifically to the nature of the problem, a photoresist layer 28 is patterned to form an etch mask for etching openings 1 in the passivation layer 26 to the bonding pads 18' while concurrently openings 2 are etched in the passivation layer and in the underlying insulating layers of the multilevel interconnect structure over the fuses 14, as shown in FIG. 3. However, because of the excessive etching in the relatively thick insulating layers, about 55,000 Angstroms, it is difficult to etch the fuse openings 2 to within the required depth D of 5000+/-3000 Angstroms without overetching the bonding pads 18' in the openings 1. As shown in FIG. 3, this overetching of the bonding pads results in a thinning of the bonding pads to a thickness E that is less than 4000 Angstroms, which causes reliability problems. The current etching conditions do not provide sufficient etch selectivity between the passivation layer and the bonding pads to prevent this overetching. For example, the current etching gases, such as CF.sub.4)/CHF.sub.3 /Ar, and etching parameters, such as at about 1100 Watts of power, can result in AlCu etch rates of 300 to 400 Angstroms per minute.
One method of forming bonding pads is described by Bryant et al., U.S. Pat. No. 5,403,777, in which bonding pads are formed in the shape of grid, and a second conducting layer is deposited to prevent pad lift-off. Another method for making low-resistance bond-pad interconnects is described by Doan et al., U.S. Pat. No. 5,384,284. The method uses an intermediate conducting layer to prevent Al.sub.2 O.sub.3 from forming on the Al bond pads, thereby preventing high resistance. In U.S. Pat. No. 5,290,588 by Romero et al., a method is described for eliminating "purple plague" which is an undesirable reaction of the gold (Au) layer on Al bonding pads. The method utilizes a TiW layer between the Al and the Au and an inert atmosphere anneal to form stable TiAl.sub.3 phase that prevents inter-diffusion between the Al and the Au. Liu et al. in U.S. Pat. No. 5,705,428 describe a method for preventing Ti lifting during and after metal etching by adding nitrogen during plasma etching, or during photoresist plasma strip, using an oxygen stream ambient. However, none of these references addresses the overetch bonding-pad problem described.
There is still a strong need in the semiconductor industry to provide a method for etching openings in a passivation layer to bonding pads and concurrently etching openings to the fuses without overetching the bonding pads.

Method for reducing bonding pad loss using a capping layer when etching bonding pad passivation openings

Taiwan Semiconductor Manufacturing Company, Ltd.


A quick coupler for detachably coupling a bucket or other work tool to the stick of an excavator or backhoe is disclosed. The quick coupler has a latching mechanism with is powered by a single acting cylinder to unlatch the coupler and which is powered by both a spring device and a gas charged accumulator to latch the coupler to the bucket.

In recent years, quick couplers have become commonly used for detachably connecting buckets or other tools to earth working machines, such as backhoes, excavators and loaders. Such quick couplers are advantageous because they allow a machine operator to quickly change from one bucket to another. Of course, the operator can detach and attach other work tools, as well as buckets, for performing other types of work. Thus, the use of a quick coupler makes the machine much more efficient and versatile.
Several different types of quick couplers have been employed in the past. One of such quick couplers is disclosed in U.S. Pat. No. 5,494,396 for a Coupling Device for a Work Implement, issued to Timothy D. Geier et. al. on Feb. 27, 1996. Such coupling device utilizes a manually actuated latching arrangement that requires the operator to wrench out the latching member on the coupling device. Other types of quick couplers are provided with a hydraulically actuated latching mechanism to allow the operator to detach and attach such tools from the cab. One of such quick couplers with a hydraulically actuated latching mechanism is disclosed in U.S. Pat. No. 5,147,173 for a Coupling Device, issued to Raymond L. Fauber on Sep. 15, 1992. In such coupling device, a double acting hydraulic cylinder is employed to both engage and disengage the coupler from the tool. This coupling device also employs a coil spring as a back-up force to the latching wedge in the event hydraulic pressure is lost. Another such quick coupler arrangement is disclosed in U.S. Pat. No. 5,634,736 for a Quick-Disconnect Coupling Device, issued to Eric A. Brown et. al. on Jun. 3. 1997. In this coupling device, a double acting cylinder actuates an over center linkage arrangement to operate the latch. However, no back-up force is provided in the event of the loss of hydraulic pressure.
While prior quick couplers satisfactorily perform their intended task, some are inconvenient because they require the operator to leave the cab to operate them. Others employ double acting cylinders that require two hydraulic lines or are otherwise complex and costly. Others do not employ a back-up system in the event of a loss of the primary latching force.
The present invention is directed at overcoming one or more of the problems set forth above.


A vehicle headlamp includes a projection lens, a first lens, a second lens, a first light source, and a second light source. The first lens and the second lens are behind the projection lens. The first light source is behind the first lens. The second light source is behind the second lens. The first lens and the second lens deviate from an optical axis of the projection lens and are opposite to each other.

1. Technical Field
The present disclosure relates to lighting fixtures for vehicles and buildings, and, in particular, to a vehicle headlamp.
2. Description of the Related Art
In the related art, a vehicle lamp creates a low-beam light distribution pattern and a high-beam light distribution pattern by reflecting light from two light sources by a reflector and a light emitting unit, respectively, and passing the light through a projection lens.
For example, in Japanese Patent Unexamined Publication No. 2016-39110, a low-beam light distribution pattern and a high-beam light distribution pattern are created as shown in FIG. 11. Light emitting unit 30 includes first light source 14 and second light source 32. The low-beam light distribution pattern is formed by reflector 16 emitting light from first light source 14 toward projection lens 12. The high-beam light distribution pattern is formed by light emitting unit 30 emitting light from second light source 32 toward projection lens 12 through light-transmissive member 34.

PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.


In accordance with an embodiment, a method of operating a switched-mode power converter includes defining at least one of a minimum switching frequency threshold and a maximum switching frequency threshold; detecting valleys occurring in a voltage over the switching element when the switching element is in an off-state; and either in a quasi-resonant mode, switching the switching element on when an nth consecutive valley occurs, n being an integer equal to or greater than one, so that the actual switching frequency is at least one of: below the maximum switching frequency threshold and above the minimum switching frequency threshold, or in a forced switching frequency mode, switching the switching element on so that the actual switching frequency is the maximum or the minimum switching frequency.

Each time a switch, such as a transistor, is turned on or off in switched-mode power converter, energy is dissipated in proportion to the current and voltage being switched. The power losses associated with switch operations, referred to as switching losses, represent a significant source of power dissipation and therefore a significant source of inefficiency in conventional switch mode power converters. In addition to increasing switching loss, large rates of change for voltages and/or currents (i.e., dv/dt and/or di/dt) at the time of switch transition increase stress on the switch and the amount of electromagnetic interference (EMI) produced by the switch. Some switching schemes have been developed that take advantage of resonance in switch-mode power converters to turn on switches at times when the voltages applied to the switches are at a local minimum, referred to as a valley. Such switching schemes are therefore typically referred to as valley-mode switching schemes.


In a robot hand according to the present invention, a first-type grasping claw driven by a servo motor on a hand base and a second-type grasping claw having no actuator are used with the grasping claws mounted on each holding unit. The second-type grasping claw is movable in a direction perpendicular to a moving direction of the first-type grasping claw. The robot is operated so that an external force is applied to the grasping claw by bringing the grasping claw into contact with a contact surface of a stationary stand member, thereby to change a position of the grasping claw relative to the hand base and that grasping claw is locked at that position by a brake mechanism. Each grasping claw is adapted to be able to be mounted or dismounted on or from the holding unit using a pull bolt and a retaining mechanism, and can be automatically changed by the robot operation. By attaching the pull bolt to the workpiece in advance, the retaining mechanism also can be used for holding the workpiece.

1. Field of the Invention
The present invention relates to a robot hand structure, of an industrial robot, for handling a workpiece and to a handling robot system having the same.
2. Description of the Related Art
An industrial robot for performing a handling operation is intended to handle not one type of workpiece, but, in most cases, different types of workpieces of different shapes and sizes. For this reason, operation requirements often cannot be met by a robot system having only one type of robot hand (hereinafter referred to simply as a "hand") prepared for grasping a workpiece. Also, in the case that a single type of workpiece is handled, a portion of the workpiece to be grasped may be required to be changed depending on a specific requirement of a handling operation. In this case, if the shape of the held portion of the workpiece is different before and after the change, a single type of hand, similarly, cannot meet the requirements suitably. Further, in the case that a grasping claw is required to have a shape conforming to the shape of the workpiece, it is difficult to perform the handling operation with a single hand.
In order to address such a situation, it has conventionally been the common practice to prepare a plurality of types of hands in accordance with the number of workpiece types or the number of operation types. Each of the prepared hands often has built therein the required number of grasping claws (grasping members), an actuator for causing the grasping claws to perform the grasping operation (such as motor, air cylinder, etc.), and a drive mechanism for driving the grasping claws with the actuator. To change the hand, on the other hand, a hand retaining unit for changing a hand is widely used. In the case that a plurality of types (three types in this case) of workpieces 6, 7, 8 having different shapes are handled, for example, using a handling robot (robot mechanical part) 1 having six degrees of freedom (axes) as shown in FIG. 1, different hands 3, 4, 5 suitable for grasping the different workpieces are used to execute different types of handling operations.
The hand retaining unit 2 is arranged at a forward end of an arm of the handling robot (hereinafter sometimes referred to simply as the "robot") 1, and one of the prepared hands 3 to 5 is mounted on the robot via the hand retaining unit 2. FIG. 1 shows the workpiece 6 being grasped by the hand 3 mounted on the robot. Each of the hands 3 to 5 has built therein grasping claws having an arrangement, shape and size suitable to grasp one of the workpieces 6 to 8, and an actuator to cause the grasping claws to perform the grasping operation. Drive mechanisms for moving the robot 1 along each of axes thereof are controlled by a robot control unit (not shown) in a well-known manner, while the hand retaining unit 2 and the actuators for the hands to perform the grasping operation are also controlled by the robot control unit.
When the hand is changed (for example, the hand 3 is replaced with the hand 4), the robot 1 is moved, for example, to an access point to a fixation holder for the hand 3, and a hand release command is sent from the robot control unit to the hand retaining unit 2 to release the hand 3 and bring the hand 3 back to the fixation holder for the hand 3. Then, the robot 1 is moved, for example, to another access point to a fixation holder for the hand 4, to engage the hand retaining unit 2 with the hand 4, and a command to lock the hand 4 is sent from the robot control unit to the hand retaining unit 2. In this way, the hand 3 is completely replaced with the hand 4. The hand retaining unit 2 is also equipped with a mechanism for connecting or disconnecting a signal line system, etc., to the actuator built in each hand when the hand is replaced.
However, in the case that the hand including the grasping claws, the actuator and the drive mechanism for the grasping claws is changed to deal with a great variety of shapes, etc., of the workpieces, as in the prior art described above, a problem may be caused in which both the actuator and the drive mechanism are liable to interfere with devices surrounding the workpiece in a wide area so that the handling operation may be hampered. For example, in the case that ten types of hands are prepared for a hand changing, nine hands other than the hand in use exist in an operation range of the robot and occupy a considerable volume of space, resulting in an increased risk of interference.
An attempt to handle a plurality of types of workpieces with a few types of hands, on the other hand, would cause a problem in which the shape, etc., of the grasping claw may fail to conform to the shape of a particular workpiece, thereby resulting in an increased possibility of the workpiece being grasped erroneously or dropped. Further, in the case that a grasping claw having a shape suitable for a particular workpiece having a unique shape is required, it is necessary to prepare a hand having dedicated grasping claws having the shape suitable for each type of the workpieces, thereby increasing the system cost.


The light directed from a light source to a concave mirror and the light directed from a display device to an eyepiece optical system are intersected by each other in a layout. This allows the light source, the concave mirror, and the display device to be arranged in compactness adjacent to the eyepiece optical system without increasing the optical power of an illumination optical system. As the result, the apparatus can easily be minimized in the thickness or the overall size. A hologram optical element is provided where the relationship between the wavelength range Δλ1 at half of the diffraction efficiency of each of the three primary colors of the light in the hologram optical element and the wavelength range Δλ2 at half of the intensity of each of the three primary colors of the light emitted from the light source is defined by Δλ1<Δλ2. Accordingly, a component at desired wavelengths of each of the R, G, and B colors of the light emitted from the light source can be diffracted by the action of the hologram optical element and then directed to the pupil of the viewer. This allows the image to be increased in the color reproduction area and improved in the quality regardless of the display device actuated in a time-division mode.

1. Field of the Invention
The present invention relates to an image display apparatus for projecting an image displayed on a display device (for example, a reflective display device) onto the eyes of a viewer as a virtual image, and to a head mounted display (hereinafter referred to as an HMD) equipped with the image display apparatus.
2. Description of the Prior Art
An apparatus is known as a so-called HMD which is mounted on the head of a viewer for projecting the image, which has been produced by a display device, as a virtual image onto the pupil of the viewer across an eyepiece optical system. The display device employed in the HMD is classified into a transmissive type illuminated from the back of its screen and a reflective type illuminated from the front side or the viewer side.
The transmissive type of the display device may be implemented by a transmissive type liquid crystal display (LCD) device which is commonly used in the HMD. As the transmissive type LCD device includes a liquid crystal panel sandwiched by a pair of substrates illuminated from the back by light of illumination, its substrate has to be high in the transmissivity of light such as a glass material. This limits the semiconductor process in the production thus making the integration of pixels at higher density difficult. Also, the transmissive type of the display device is essentially equipped with periphery circuits which includes switching elements (for example, TFT switches) for turning the transmission of light on and off at each pixel, and patterns of wiring. In addition, these periphery circuits are required to be disposed on the same display panel. When the integration of pixels is increased, the proportion of the pixel area to the screen of the display panel (so called the aperture) becomes smaller thus declining both the illumination efficiency and the quality of the image.
On the other hand, the reflective type of the display device has a substrate made of a semiconductor material such as silicon and can thus be increased in the integration of pixels while decreased in the dimensions. Moreover, this allows a periphery circuit to be mounted on the other side of the substrate opposite to the display side, thus ensuring the aperture not declined when the integration of pixels is increased. As the result, the reflection efficiency will significantly be high thus producing a brighter image. This advantage becomes emphasized as the size of pixels is reduced. While the number of pixels remains unchanged, the display panel can be scaled down without sacrificing the brightness. Alternatively, while the size of the display panel remains unchanged, the number of pixels can favorably be increased thus contributing to the higher definition of the image.
Using such a reflective type display device having a variety of merits, the HMD can be advantageous for displaying the image at higher brightness and definition.
FIG. 23 is across sectional view schematically showing an arrangement of a conventional image display device of which the display device is of a reflective type. In the arrangement, a PBS (polarized beam splitter) 103 is provided across the optical path between a light source 101 and a reflective display device 102 for separating between an optical path of illumination light emitted from the light source 101 and an optical path of view light released from the reflective display device 102. More specifically, the illumination light emitted from the light source 101 passes through the PBS 103 and is directed toward the reflective display device 102. A reflection (view light) of the illumination light reflected on the reflective display device 102 is reflected by the action of the PBS 103, passes through an eyepiece lens 104, and is directed toward the pupil EP of a viewer. This allows the viewer to view an enlarged image of the image displayed on the reflective display device 102.
The HMD using the conventional image display apparatus is used for a considerable length of time when has been mounted to the head of the viewer and its image display apparatus will hence be as small in the size and light in the weight as possible. However, the conventional image display apparatus includes the PBS 103 which is considerably heavy and will thus remain not lightened.
For compensation, an image display apparatus is disclosed in Patent Document 1, listed below, where the optical path in an illumination optical system are separated from the optical path in a view (eyepiece) optical system with no use of a PBS disposed at the intersection of the two optical paths. This will be explained below in more detail.
FIG. 24 is across sectional view schematically showing an arrangement of the image display apparatus of Patent Document 1 for use in an HMD. In the image display apparatus, the light emitted from a light source 201 is converged by a collector lens 202 and directed across a polarizer 203 to a display device 204. An image light from the display device 204 is directed toward the pupil EP of a viewer through another polarizer 205 and an optical element (prism) 206. In particular, those optical elements are arranged so that the reference axis L0 extending from the light source 201 to the display device 204 and the reference axis L0 extending from the display device 204 to the optical element 206 are intersected by each other at the location of the display device 204. This arrangement is intended to reduce the overall dimensions of the image display apparatus.
FIG. 25 is across sectional view schematically showing an arrangement of an image monitor apparatus disclosed in Patent Document 2, listed below. In this apparatus, the light emitted from a light source 301 is reflected by the reflective/transmissive surface 302a of a prism 302 and received by a displaying means 303. A reflection of the light from the displaying means 303 is received again by the prism 302 where it is passed through the reflective/transmissive surface 302a this time and then passed across a polarizer 304 and another prism 305 before directed to the monitoring point of a viewer. Since the prism 302 is shared between an illumination optical system for illuminating the displaying means 303 and a monitor optical system for directing the light from the displaying means 303 to the monitor position of the viewer, the apparatus can be decreased in the overall size and widened in the angle of view.
The HMD disclosed in Patent Document 1 is such that the display device 204 is of a ferroelectric LCD type having a wider angle of view, and the image light from this display device is directed toward the pupil of the viewer via an enlargement optical system (a prism 206). Another prism is bonded to the enlargement optical system and its bonding interface is arranged of a half mirror surface. Accordingly, the viewer can view the image received through the half mirror surface from the display device and simultaneously an external scene projected across the prisms.
In addition, the HMD in which the reflective LCD device is actuated in a field sequential mode (time-division mode) and the image light in the R, G, and B colors is directed via the hologram optical system toward the pupil of the viewer, thereby providing the viewer with the image in colors (virtual image) is disclosed, for example, Non-Patent Document 1, listed below.
The patent and non-patent documents mentioned above are as follows:                Patent Document 1: JP-A-2000-249969        Patent Document 2: JP-B-3461297        Non-Patent Document 1: "Novel Virtual Image Optics or Reflective Micro-displays" by H. Mukawa et al., SID Conference Record of the International Display Research Conference, ISSN1083-1312/00/2001-0096-$1.00+0.00, 2000 SID (a preparatory proceeding at the Conference from Sep. 25 to 28 in 2000)
However, as disclosed in Patent Document 1, when the reference axis L0 which extends from the light source 201 to the display device 204 remains not bent but held straight, the optical path has to be lengthened for permitting the collector lens 202 to converge the illumination light emitted from the light source 201 on the screen of the display device 204. Accordingly, the apparatus will be limited in the downsizing and configured in an unfavorable layout possibly with its light source 201 projecting towards the viewer. Alternatively, when the collector lens 202 is increased in the optical power for converging the illumination light emitted from the light source 201 on the screen of the display device 204, its dimensions will increase and then prevent the apparatus from being decreased in the overall size.
Also depicted in Patent Document 1 is the optical path which extends from the light source 201 to the display device 204 is bent by the action of a mirror. The mirror is however located at the light source 201 side about the optical path which extends from the display device 204 to the optical element 206. This causes the light source 201 to be positioned far from the optical element 206 for projecting the light onto the mirror. As the result, the apparatus will be increased in the height thus interrupting the downsizing.
Patent Document 2 has similar drawbacks. Assuming that the light of illumination is directed from the light source 301 to the displaying mean 303 and the light of view travels along the optical path of the light of illumination and is directed from the displaying means 303 to the prism 305 in the view optical system, the optical path of the light of illumination is bent by the prism 302 at the light source 301 side about the optical path of the light of view. Accordingly, the optical path in the illumination optical system has to be lengthened between the light source 301 and the prism 302 to converge the illumination light on the displaying means 303. As the result, the downsizing of the apparatus will be interrupted.
It is also essential for increasing the quality of a color image (to be displayed on a display device and viewed by a viewer) to widen the color reproduction area in the image. For example, when the half mirror but not a hologram optical element is used as a combiner for the image light and the ambient light as disclosed in Patent Document 1, the color reproduction area produced on the ferroelectric LCD device being actuated in a time-division mode (with no use of color filters) may be determined by the wavelength range of the R, G, and B colors of the light emitted from the light source. On the other hand, when a hologram optical element is used as the combiner for the image light and the ambient light as disclosed in Non-Patent Document 1, the color reproduction area produced on the display device being actuated in a time-division mode is determined by a combination of the wavelength range of the R, G, and B colors of the light emitted from the light source and the diffraction wavelength range of the R, G, and B colors of the light in the hologram optical element.
However, Non-Patent Document 1 does not refer to the action of widening the color reproduction area in an image to be viewed, still less the diffraction wavelength range of the R, G, and B colors of the light in the hologram optical element in combination with the wavelength range of the R, G, and B colors of the light emitted from the light source for widening the color reproduction area.

Image display apparatus and head mount display


The pouring tube includes a discharge portion having discharge ports in its wall for splitting the flow of melt, and for directing the various portions of the flow into the surrounding melt as melt streams emerging at angles to the outer surface of the pouring tube. The angles of the streams to the pouring tube are selected such that the energy of the streams is dissipated in the surrounding melt before the streams impinge against a wall of the mold. The pouring tube also includes seals for temporarily preventing the emergence of selected streams in order to avoid excessive splashing and/or material build up on the walls of the mold during the start-up phase of its operation.

1. Field of the Invention
The present invention relates generally to pouring tubes for use with continuous strip-casting equipment. More particularly, the invention relates to pouring tubes which are designed for the introduction of a metallic melt into the cavity of the mold through lateral discharge ports located below the normal operational surface level of melt in the mold.
2. Summary of the Prior Art
In the continuous casting of metallic strip, particularly steel or aluminum strip, it is well understood that melt must be supplied to the cavity of the mold in sufficent quantity to allow the maintenance of efficient casting speeds. It is also well understood that the non-uniform distribution of melt within the cavity of the mold can detrimentally effect the quality of the strip being cast. The introduction of desirable quantities of melt into the cavity of the mold in a manner which maintains the required uniformity of distribution of melt within the mold, however, has heretofore presented serious problems to the art. For example, the so called "free-pouring" method has been found to be unsuitable for the continuous casting of steel strip. This method results in a melt distribution within the mold which is not uniform. Accordingly, acceptable product quality cannot be assured. Further, the "free pouring" method introduces unacceptable heat loss and re-oxidation problems in the continuous casting context.
Attempts have been made to solve this problem by introducing melt below the normal operational melt surface level in a continuous strip-casting mold. For this purpose, molds for the continuous casting of metallic strip have been developed having an enlarged pouring area which tapers inwardly and downwardly from the to of the mold centrally between the broad side walls and the narrow side walls which form the cavity of the mold. Pouring tubes for use with these molds have also been developed. These pouring tubes extend from a melt container to the mold cavity, and include a discharge portion (adjacent to their free ends) which extends into the volume of the enlarged pouring area below the normal operational melt surface level in the mold. The discharge portion of such pouring tubes is closed axially, and includes a lateral exit port facing each of the narrow side walls of the mold. The melt flows from the container through the pouring tube to its free end. At the free end of the tube, the melt is deflected outwardly through the lateral exit ports, toward the narrow side walls of the mold. The resulting melt stream flow into the melt already present in the mold cavity radially from the pouring tube toward the inner surfaces of the narrow side walls of the mold. Since the melt in each of these streams has a high kinetic energy (i.e., the flow is fast in order to assure that an adequate quantity of melt for efficient strip casting reaches the cavity of the mold), the identifiable currents created by the inflooding melt within the melt already present in the cavity extend from the pouring tube all the way to the walls of the mold. This results in erosion of the strand shell under formation along the walls of the cavity. The presence of an appropriate strand shell is important to the casting of strip having acceptable structure and a uniform, fault free surface. Hence, the damage to (and/or the impediment to the formation of) the strand shell in such prior art devices must, if possible, be strictly controlled. This means that melt introduction rates must be held below optimum levels, thus reducing the efficiency of the entire casting operation.
Similarly, since the volume of melt normally present within the cavity of the mold is not large (particularly in cases wherein strip having thin cross-sectional height, for example, less than 60 mm, is being cast), and since that volume cannot readily absorb the energy of the incoming melt streams, the streams flowing outwardly from the discharge ports towards the narrow side walls also tend to create non uniform distributions of melt within the cavity of the mold, i.e., an excess of melt (standing waves) adjacent the narrow side walls of the cavity. This excess melt is forced upwardly (adjacent the narrow side walls) because it is confined by the broad side walls, a narrow side wall, the melt below it, and the incoming stream of melt behind it. Therefore, the surface of the melt in the cavity is raised adjacent each of the narrow side walls relative to its normal level, creating a trough in the area adjacent the pouring tube. This can cause deviations from the preferred flow characteristics of the melt through the mold which are detrimental to the formation of acceptable strip. It also may cause metal to become caked on the walls of the mold above the normal level of the melt therein. In extreme cases, the energy of the streams may be great enough to cause splashing of the melt adjacent the narrow side walls of the mold. Melt splashing is particularly problematic during the start-up phase, when the melt in the cavity of the mold has not yet had a chance to reach its normal operational level.

Pouring tube for the introduction of metallic melt into a strip-casting mold


A new and distinct of Chrysanthemum plant named ‘Rosy Yoigloo’, characterized by its upright, outwardly spreading and mounding plant habit; freely branching habit; dense and full plant habit; uniform and freely flowering habit; duplex-type inflorescences with obovate-shaped ray florets; red-colored ray florets; and natural season flowering about September 18th in the Northern Hemisphere.

The present invention relates to a new and distinct cultivar of Chrysanthemum plant, botanically known as Chrysanthemum×morifolium, commercially grown as a perennial garden Chrysanthemum and hereinafter referred to by the name 'Rosy Yoigloo'.
The objective of the breeding program is to create new perennial garden-type Chrysanthemum cultivars having inflorescences with desirable inflorescence forms, attractive floret colors and good garden performance.
The new Chrysanthemum is a naturally-occurring whole plant mutation of the Chrysanthemum×morifolium cultivar Warm Yoigloo, disclosed in a U.S. Plant patent application filed concurrently. The new Chrysanthemum was discovered and selected by the Inventor as a single flowering plant within a population of plants of the cultivar Warm Yoigloo in December, 2003, in Alva, Fla. The selection of this plant was based on its desirable inflorescence color and good form and substance.
Asexual reproduction of the new Chrysanthemum by vegetative cuttings was first conducted in Alva, Fla. in February, 2004. Asexual reproduction by cuttings has shown that the unique features of this new Chrysanthemum are stable and reproduced true to type in successive generations.


A luminaire includes a light pipe having an optical axis. The light pipe includes a tube with a structured outer surface and a smooth inner surface. A reflective light extractor is positioned in the tube such that light reflected by the extractor will strike the tube on a first side. The first side has a contour such that the direction of travel of light reflected by the extractor will have a projection in the plane perpendicular to the optical axis that makes a predetermined angle with the smooth surface.

Light conduits, also known as light pipes, formed of structured surface materials and operating on the basis of total internal reflection are well-known. Such light conduits are described in U.S. Pat. No. 4,260,220 (Whitehead). As described in that patent, the light conduit is used primarily for transporting light. Alternatively, such a light conduit may be used as a lighting fixture or luminaire as described in U.S. Pat. No. 4,615,579 (Whitehead). Such a luminaire has the advantage that it provides even illumination over an extended region.
All of the light conduits described in the Whitehead references mentioned above, have flat sides. Experimentation has shown, however, that the transport efficiency of a light conduit having curved sides, and in particular a round cross-section, is, in general, better than that of such a pipe having flat sides. Such a light pipe is described in U.S. Pat. No. 4,805,984 (Cobb).
It is often desirable to use an extractor to help force light out of the tube forming the light conduit. This is particularly true when the light conduit is to be used as a luminaire. U.S. Pat. No. 4,850,665 (Whitehead) describes such an extractor. A preferred material for the extractor of that patent is a nonwoven polyester fiber formed into a sheet such as that sold under the registered trademark Tyvek by E. I. DuPont de Nemours and Company.
There are two related disadvantages that arise when light conduits such as those described in the above referenced patents are used as luminaires. Both problems result from the fact that these systems make no attempt to control the angle at which light escaping the tube strikes the smooth inner surface of the tube. The first problem relates to the efficiency of luminaires such as those described in the references discussed above. Experimentation and computer simulations have shown that light escapes the wall of the tube most efficiently when the projection of the direction of travel of the light ray in the plane perpendicular to the axis of the light pipe forms an angle of approximately 60 degrees with the normal to the smooth inner surface of the tube. In this context the phrase "most efficient" means that the highest percentage of the light striking the surface is transmitted and escapes from the light pipe. Since the prior art luminaires do not control the angle at which the light strikes the tube, they do not insure maximum efficiency.
The second problem is closely related to the first. Since the prior art systems do not control the angles at which the light strikes the inner surface of the tube, they tend to produce diffuse or otherwise uncontrolled light output. While this works well for some circumstances, it is not acceptable in situations where a strongly directed beam of light is desired.

Light pipe having optimized cross-section

Minnesota Mining and Manufacturing Company


The present disclosure relates to a system and method of cancelling feedback in a vehicle communications system. The system and method may adjust a phase and a polarity of the microphone signal to produce an inverted microphone signal having a shifted phase. A speaker signal may be summed with the inverted microphone signal to cancel out at least a portion of a microphone signal component of the speaker signal.

Vehicles in industrial and public safety applications have had intercom/radio mixer systems for many decades. These systems allow the vehicle users to communicate amongst themselves and also communicate to distant individuals using mobile radio technology. The systems have often incorporated headsets due to loud ambient noise environments inside and outside the vehicle. These systems aim to provide more coherent communication in the vehicle.
Some of these vehicle communication systems utilize headsets. Headsets may introduce some potential drawbacks including the additional time to don the headset, comfort, and restriction of movement. The donning of headsets takes additional time when entering the vehicle. In particular, for public safety workers, every second counts when trying to get as quickly as possible to the scene of an emergency. Even the couple of seconds that it takes to find and don a headset can be distracting and have a negative effect on the outcome of a life threatening situation. Headsets may become uncomfortable depending on the design and length of time that a particular headset is worn. If uncomfortable, crewmembers may decide not to wear the headsets, thereby exposing crewmembers to the inability to effectively communicate over the vehicle radio and amongst fellow crewmembers. Further, some headsets, such as corded headsets, can restrict the movement of a crewmember's head and reduce the ability to move about the interior of a vehicle.
As vehicle, engine, and transmission soundproofing technologies have advanced, the interiors of many industrial and public safety vehicles have become quieter. Despite soundproofing advancements, the interiors of these types of vehicles are still relatively large and are not completely soundproof, and thus are not conducive to easy communication amongst crewmembers. In addition, cabin speakers that broadcast radio traffic inside of the vehicles may have limitations including distortion, difficult placement, and the risk of being too loud.
Thus, it is advantageous to implement an improved vehicle crew communication system that does not require headsets (although headsets may be used with the system), positions speakers closer to crewmembers than traditional cabin speakers, and allows for verbal communication between crewmembers to be easily detected by a microphone and transmitted. In some embodiments, an individual seat system that incorporates speakers and a microphone that is integrated into the overall vehicle communications system constitutes an improved system. Moreover, in embodiments where the speakers and microphone are in close proximity, there is negligible feedback such that the system provides consistent and coherent communications.

Feedback cancellation for vehicle communications system


An apparatus for distributing a liquid in an exchange column includes a plate and at least one elongated internal baffle. The plate has at least one elongated channel, which has a first longitudinal axis, a bottom, and at least one aperture in the bottom. At least a substantial portion of the internal baffle, which has a second longitudinal axis substantially parallel to the first longitudinal axis, is disposed in the channel.

The present invention relates to an apparatus and a method for distributing a liquid from a liquid distributor to a packing in an exchange column for heat and/or mass transfer processes. The apparatus and method have particular application in cryogenic air separation processes utilizing distillation, although the apparatus and method may be used in other heat and/or mass transfer processes that use liquid distributors and packing (e.g., random or structured packing).
The term, xe2x80x9ccolumnxe2x80x9d, as used herein, means a distillation or fractionation column or zone, i.e., a column or zone wherein liquid and vapor phases are countercurrently contacted to effect separation of a fluid mixture, such as by contacting of the vapor and liquid phases on packing elements.
The term xe2x80x9cpackingxe2x80x9d means solid or hollow bodies of predetermined size, shape, and configuration used as column internals to provide surface area for the liquid to allow mass transfer at the liquid-vapor interface during countercurrent flow of two phases. Two broad classes of packings are xe2x80x9crandomxe2x80x9d and xe2x80x9cstructuredxe2x80x9d.
xe2x80x9cRandom packingxe2x80x9d means packing wherein individual members do not have any particular orientation relative to each other or to the column axis. Random packings are small, hollow structures with large surface area per unit volume that are loaded at random into a column. xe2x80x9cStructured packingxe2x80x9d means packing wherein individual members have specific orientation relative to each other and to the column axis. Structured packings usually are made of expanded metal or woven wire screen stacked in layers or as spiral windings; however, other materials of construction, such as plain sheet metal, may be used.
The terms xe2x80x9corifice,xe2x80x9d xe2x80x9chole,xe2x80x9d and xe2x80x9caperturexe2x80x9d are used interchangeably herein to mean an opening through which a fluid may pass. Although circular orifices are shown in the drawings, the orifices may have other shapes, including irregular as well as regular shapes.
Cryogenic separation of air is carried out by passing liquid and vapor in countercurrent contact through a distillation column. A vapor phase of the mixture ascends with an ever increasing concentration of the more volatile components (e.g., nitrogen) while a liquid phase of the mixture descends with an ever increasing concentration of the less volatile components (e.g., oxygen).
Various packings may be used to bring the liquid and gaseous phases of the mixture into contact to accomplish mass transfer between the phases. The use of packing for distillation is standard practice and has many advantages where pressure drop is important. However, packed column performance is very dependent on creating and mantaining a balance between the downward flow of liquid and the upward flow of vapor locally in the packing. The distribution of the liquid and the vapor within the packing as influenced by the initial presentation of these fluids to the packing.
Initial presentation of liquid and vapor to the packing is usually made by means of distributors. A liquid distributor, the role of which is to irrigate the packing uniformly with liquid, is located above the packing, while a vapor distributor, the role of which is to create uniform vapor flow below the packing, is located below the packing.
There are three main types of typical liquid distributorsxe2x80x94pipe, pan, and trough distributors. Each type is discussed briefly below.
Pipe distributors are comprised of an interconnecting network of closed pipes or ducts, typically comprising a central pipe or manifold and a number of arms or branches radiating from the central pipe. The arms are perforated to allow the liquid passing from the central pipe and into the arms to be dripped or sprayed onto a packed bed below the pipe distributor. Upwardly flowing vapor passes easily in-between each arm. Pipe distributors receive liquid from a separate liquid collector or an external source piped through the wall of the column. While simple and inexpensive to construct, pipe distributors may distribute liquid poorly when vapor gets trapped in the arms.
Pan distributors are comprised of a pan or pot having holes in the bottom for feeding liquid to the packing below and tubes or risers for the vapor to pass upwardly through the distributor. Pan distributors often make a complete seal with the wall of a column. Thus, pan distributors can act as liquid collectors as well as distributors. However, since large pan distributors are costly to build, pan distributors usually are used in smaller columns, i.e., columns with diameters less than 1.5 meters.
Trough distributors comprise a collection of interconnecting open troughs or channels having irrigation holes in the base to feed liquid to the packing below. At least one upper collection trough, or a simple pot on top of the lower troughs, feeds liquid to the lower troughs through a series of holes or overflowing notches. Vapor from the packing below passes upward between the liquid-containing troughs.
FIG. 1 shows a typical liquid distributor 10 of the trough type. Liquid from feed assembly 12 enters a pre-distributor 14, which distributes the liquid to the distributor. The distributor is mounted on a combined hold-down/support grate (not shown) above the packing (not shown).
After entering the distributor 10, the liquid flows in a plurality of channels or troughs 18 spaced apart by vapor risers 16 throughout the distributor. A typical main channel 17 and multiple troughs or channels 18 on each side of the main channel 17 are shown in FIG. 2. Liquid from the main channel enters each channel at the inlet end 20 of the channel and flows in a direction 22 away from the inlet end. Streams of liquid 24 then exit each channel through orifices or holes 26 in the bottom 28 of the channel. If the liquid does not flow from the holes in uniform directions, some areas of the packing below the distributor are under irrigated areas 30 while other areas of the packing are over irrigated areas 32, as shown in FIG. 2. Also, some of the liquid may impact internal structures between the bottom of the distributor and the packing, such as distributor supports/hold-down grates 34, as shown in FIG. 2. (These internal structures may support the distributor and/or hold down the packing.)
Some liquid distributors used in distillation processes are disclosed in U.S. Pat. No. 5,752,538 (Billingham, et al.); U.S. Pat. No. 5,240,652 (Taylor, et al.); U.S. Pat. No. 6,086,055 (Armstrong, et al.); U.S. Pat. No. 4,729,857 (Lee, et al.); U.S. Pat. No. 5,192,465 (Petrich, et al.); and U.S. Pat. No. 5,645,770 (McNulty, et al.).
The prior art distributors generally use three types of distribution regulation mechanisms: the weir type, where liquid flows horizontally through a gap; the orifice type, where liquid flows vertically, or horizontally, usually through a circular hole; and the pressure type, where feed under pressure is distributed through a series of spray nozzles. The orifice type is distinguished by the fact that the flow rate of liquid through the hole is proportional to the square root of the height of liquid above the orifice. For a narrow weir, the flow can be taken as being proportional to the height of liquid raised to the power 1.5. Use of orifices is often preferred because the effects of minor changes in the liquid level or the levelness of the distributor are reduced by having the flow rate being proportional to the height squared if a reasonable liquid depth is used. However, this comes at the expense of reducing the operating range of a simple distributor because the height available for the distributor is often limited. Weir type distribution is often preferred when a large amount of liquid must be distributed, high rangeability is required, or in the pre-distribution section of the distributor.
In the case of orifice type distribution, the thickness of the orifice material plays an important part in regulating the flow and the direction of the liquid stream. Orifices generally may be divided into two classesxe2x80x94those in thick material and those in thin material. For a material to be classified as thick, the liquid flow must be fully developed within the thickness of the material, which gives rise to a high L/D ratio (where L is the material thickness and D is the diameter of the hole). For a thin material, the L/D ratio is lower, normally below 1.0. For an orifice in a thick material, the stream generally will emerge in line with the axis of the orifice, while in a thin material the stream will emerge at an angle with the axis of the orifice, which angle is determined by the direction of any cross-flow velocity in the liquid above the orifice. In any distributor, this cross-flow velocity is caused by the natural movement of liquid to the distribution orifices.
Since the use of thin materials often is advantageous due to ease of bending and manufacturing, many liquid distributors are constructed using channels which are made from thin material and bent to shape. The orifices are punched or drilled through a thin metal sheet prior to the bending process of forming the trough shape. Unfortunately, an orifice in a thin material suffers from the characteristic that the cross-flow velocity near the entrance to the orifice will influence the direction of the exiting stream biasing it in the direction of said cross-flow velocity. Although experiments have shown that a relatively severe cross-flow velocity is required to significantly affect the actual flow rate of the stream, the fact that the stream does not leave in line with the axis of the orifice means that two problems are encountered: 1) the stream does not land where it is expected to on the packing; and 2) during quality testing of the distributor, it is difficult to measure the performance accurately. A stream that has an inaccurate trajectory (i.e., does not flow as desired to the packing) may come into contact with other components, such as distributor support/hold-down grates 34, as illustrated in FIG. 2.
The most common way of eliminating the problems associated with streams leaving the orifices in a non-vertical direction is to add some form of tube to the outlet side of the orifice. These tubes are normally part welded onto the underside of the channel, with the orifice located at the center of the tube. The tube then directs the liquid straight down, regardless of the actual trajectory that the liquid has when it leaves the orifice. However, the use of these tubes is both expensive, as each tube must be individually attached to the main channel and/or the troughs or channels, and cumbersome, as the tubes are vulnerable to damage during handling. Therefore, use of such tubes normally is limited to those areas of the liquid distributor where high cross-flow velocities are expected. An additional problem with the tubes is that the tubes correct the directional problem after the liquid has left the orifice. However, in extreme cases, when the flow rate through the orifice is high, the cross-flow velocities above the orifice can significantly affect the flow rate through the orifice, which will lead to non-uniform distribution of liquid onto the packing.
Another approach to addressing the problems of streams not flowing vertically from the distributor is disclosed in U.S. Pat. No. 5,051,214 (Chen, et al.), where a pre-distributor is extended over the troughs in order to transfer the liquid from the pre-distributor to the distributor over a wider area. By introducing liquid directly into the troughs, the cross-flow velocity is reduced at what would be the feed end of the trough. The primary shortcoming of this approach is the cost of the complex pre-distributor. Also, the design takes up some of the space at the top of the channels, thereby reducing the design height available for the liquid, thus reducing the operable range of the distributor.
It is desired to have an apparatus and a method for distributing a liquid in an exchange column with a liquid distributor which mitigates the effects of cross-flow velocity on the direction of liquid streams from the liquid distributor.
It is further desired to have an apparatus and a method for distributing a liquid in an exchange column with a liquid distributor which will reduce or prevent the bulk flow of liquid in directions that is not desirable.
It is still further desired to have an apparatus and a method for distributing a liquid in an exchange column with a liquid distributor which can better control the flow of liquid to specific areas of the liquid distributor.
It is still further desired to have an apparatus and a method for distributing a liquid in an exchange column having packing which eliminate or mitigate under irrigation and over irrigation of the packing.
It is still further desired to have an apparatus and a method which overcome the difficulties, problems, limitations, disadvantages, and deficiencies of the prior art to provide better and more advantageous results.
It is still further desired to have a method of assembling a liquid distributor for exchange columns which affords better liquid distribution than the prior art liquid distributors, and which also overcomes many of the difficulties and disadvantages of the prior art to provide better and more advantageous results.
It is still further desired to have a new, more efficient method for the distribution of a liquid and a vapor in exchange columns.
It is still further desired to have a liquid distributor that shows high performance characteristics for cryogenic applications, such as those used in air separation, and for other heat and/or mass transfer applications.
It also is desired to have a more efficient air separation process utilizing a liquid distributor which is more efficient than the prior art.
The invention is an apparatus for distributing a liquid in an exchange column. The invention also includes a method for adjusting a flow direction of a stream of a liquid exiting an aperture in an elongated channel within a plate for distributing liquid in an exchange column. In addition, the invention includes a method for assembling a distributor for distributing a liquid to a packing in an exchange column.
A first embodiment of the apparatus includes a plate and at least one elongated internal baffle. The plate has at least one elongated channel, which has a first longitudinal axis, a bottom, and at least one aperture in the bottom. The internal baffle has a second longitudinal axis substantially parallel to the first longitudinal axis, and at least a substantial portion of the internal baffle is disposed in the channel.
There are many variations of the first embodiment of the apparatus. For example, the internal baffle may have a triangular shape or a zig-zag shape. In another variation, a part of the internal baffle is adjacent the aperture. In yet another variation, at least a portion of the internal baffle is perforated. In still yet another variation, the internal baffle has a plurality of edges, and at least one edge has a non-linear shape. In still yet another variation, the internal baffle has a plurality of perforations and divides the channel into generally parallel spaced apart first and second subchannels, the subchannels being in fluid communication across the perforations. In this variation, the first subchannel has at least one aperture and the second subchannel has a substantially fewer number of apertures (which can be zero) than the first subchannel.
A second embodiment of the apparatus is similar to the first embodiment, but includes a control baffle. At least a substantial portion of the control baffle is disposed in another channel having a third longitudinal axis at an angle with the first longitudinal axis and is in fluid communication with the channel having the first longitudinal axis.
Another aspect of the invention is an exchange column for exchanging heat and/or mass between a liquid and a vapor, the exchange column having at least one apparatus for distributing a liquid in the exchange column like the first embodiment of the apparatus discussed above.
Yet another aspect of the invention is a process for cryogenic air separation comprising contacting liquid and vapor counter-currently in at least one distillation column containing at least one mass transfer zone, wherein liquid-vapor contact is established by at least one packing, and wherein liquid is distributed to the packing by an apparatus like that in the first embodiment of the apparatus discussed above.
There are several steps in the first embodiment of the method for adjusting a flow direction of a stream of liquid exiting an aperture in an elongated channel within a plate for distributing liquid in an exchange column, the elongated channel having a first longitudinal axis, a bottom, and at least one aperture in the bottom. The first step is to provide at least one elongated internal baffle having a second longitudinal axis. The second step is to place at least a substantial portion of the internal baffle inside the channel in a position whereby the second longitudinal axis is substantially parallel to the first longitudinal axis.
There are several variations of the first embodiment of the method for adjusting a flow direction. For example, at least a section of the internal baffle may have a triangular shape or a zig-zag shape. In another variation, a part of the internal baffle is adjacent the aperture. In yet another variation, at least a portion of the internal baffle is perforated. In still yet another variation, the internal baffle has a plurality of edges, and at least one edge has a non-linear shape. In still yet another variation, the internal baffle has a plurality of perforations and divides the channel into generally parallel spaced apart first and second subchannels, the subchannels being in fluid communication across the perforations. In this variation, the first subchannel has at least one aperture and the second subchannel has a substantially fewer number of apertures (which can be zero) than the first subchannel.
In a second embodiment of the method for adjusting a flow direction of a stream of liquid exiting an aperture, there are several additional steps. The first additional step is to provide at least one control baffle. The second additional step is to place at least a substantial portion of the control baffle in another channel within the plate, the other channel having a third longitudinal axis at an angle with the first longitudinal axis and being in fluid communication with the channel having the first longitudinal axis.
A first embodiment of the method for assembling a distributor for distributing a liquid to a packing in an exchange column includes multiple steps. The first step is to provide the exchange column. The second step is to provide the distributor, which includes a plate and at least one elongated internal baffle. The plate has at least one elongated channel, the channel having a first longitudinal axis, a bottom, and at least one aperture in the bottom. The internal baffle has a second longitudinal axis substantially parallel to the first longitudinal axis, and at least a portion of the internal baffle is disposed in the channel. The third step is to install the distributor in the exchange column.
A second embodiment of the method for assembling a distributor is similar to the first embodiment, but the distributor includes an additional element. In this embodiment, the distributor includes at least one control baffle, and at least a substantial portion of the control baffle is disposed in another channel within the plate, the another channel having a third longitudinal axis at an angle to the first longitudinal axis of the channel.