Disclosed is a method for forming a bit-line of a semiconductor device. In a line patterning process for forming a bit-line in a DRAM (Dynamic Random Access Memory) of a semiconductor device, a barrier metal layer and a tungsten layer are sequentially formed on an interlayer insulating film comprising a contact hole to fill the contact hole by a CVD (Chemical Vapor Deposition) method. Then, the barrier metal layer and the tungsten layer are removed until the interlayer insulating film is exposed, and a tungsten layer having small thickness is re-formed on the exposed interlayer insulating film by a PVD (physical Vapor Deposition) method. As a result, the bit-line area is reduced as much as the barrier metal layer removed from the upper portion of interlayer insulating film, thereby having low bit-line capacitance.

1. Field of the Invention
The present invention relates to a method for forming a bit-line of a semiconductor device, and more specifically, to a method for forming a bit-line of a semiconductor device having low bit-line capacitance. In a line patterning process for forming a bit-line in a DRAM (Dynamic Random Access Memory) of a semiconductor device, a barrier metal layer and a tungsten layer are sequentially formed on an interlayer insulating film comprising a contact hole to fill the contact hole by a CVD (Chemical Vapor Deposition) method. Then, the barrier metal layer and the tungsten layer are removed until the interlayer insulating film is exposed, and a tungsten layer having small thickness is re-formed on the exposed interlayer insulating film by a PVD (physical Vapor Deposition) method. As a result, the bit-line area is reduced as much as the barrier metal layer removed from the upper portion of the interlayer insulating film, thereby having low bit-line capacitance.
2. Description of the Prior Art
Due to high integration and high capacity of semiconductor devices, capacity of a DRAM device increases with increase of the number of charged and discharged bits. However, the cell size of semiconductor devices is decreased, and it is difficult to obtain sufficient capacitance necessary for operation of the device. The capacitance C is proportional to the dielectric constant ε and the storage electrode surface area A, and is inversely proportional to the thickness d of the dielectric film as follow Equation 1.
                    C        =                  ɛ                                A            d                                              [                  Equation                                                              1                ]
If the capacitance of the device is not secured, coupling capacitance of various wires for forming a cell array increases, and the subsequent sensing margin of a sense amplifier decreases. Therefore, the capacitance is secured by using a method of increasing the cell capacitance Cs or decreasing the bit-line capacitance Cb.
However, to use the method of increasing the cell capacitance, a dielectric material having a large dielectric constant is used or a cap oxide film having a thick thickness is formed. As a result, wires of bit-line are formed of tungsten and TiN having low resistance to decrease the capacitance of the bit-line. However, since it is difficult to effectively reduce the capacitance of the bit-line using the above-described method, studies have been made to solve the problem.
FIGS. 1a to 1d are cross-sectional diagrams illustrating a conventional method for forming a bit-line of semiconductor.
Referring to FIG. 1a, a polysilicon layer (not shown), a conductive layer for gate electrode (not shown) and a hard mask nitride film (not shown) are sequentially formed on a semiconductor substrate 1 comprising a device isolation film 2.
A selective etching process is performed on the hard mask nitride film (not shown), the conductive layer for gate electrode (not shown) and the polysilicon layer (not shown). A gate line 6 where a polysilicon pattern 3, a conductive layer for gate electrode 4 and a hard mask nitride film pattern 5 are sequentially stacked is formed.
As shown in FIG. 1b, an interlayer insulating film (not shown) is formed on the semiconductor substrate including the gate line 6 of FIG. 1a. Then, the selective etching process is performed until the upper surface of the hard mask nitride film pattern 5 and the semiconductor substrate 1 to form an interlayer insulating film pattern 8 having a bit-line contact hole 10 of a cell region and a bit-line contact hole 12 of a peripheral circuit region.
As shown in FIG. 1c, a barrier metal layer 14 using Ti/TiN and a CVD tungsten layer 16 are sequentially formed on the semiconductor substrate including the bit-line contact holes 10 and 12 of FIG. 1b.
The barrier metal layer 14 has a thickness ranging from 100 to 200 Å, and the CVD tungsten layer has a thickness of less than 1000 Å.
A photoresist pattern 18 is formed on the upper surface of the CVD tungsten layer 16 of FIG. 1c via an exposure and developing process. Then, as shown in FIG. 1d, the CVD tungsten layer is etched using the photoresist pattern 18 as an etching mask to form a CVD tungsten pattern 16-1.
However, since the barrier metal layer as conductor for bit line and the CVD tungsten layer are stacked at the small thickness on the upper surface of the interlayer insulating film, the area of bit-line becomes larger and capacitance becomes higher in subsequent formation of a capacitor, thereby decreasing the sensing margin of the subsequent DRAM operation.

Method for forming bit-line of semiconductor device


An improved adjustable mounting system for mounting a flat panel display to a surface. A mounting bracket is configured to attach to the surface, while an adapter bracket is operatively connected to the mounting bracket and is configured to operatively connect to the flat panel display. At least one carrier mechanism operatively connects the mounting bracket and the adapter bracket, the first carrier mechanism positioned with a set of substantially straight guide paths or surfaces to couple the adapter bracket to the mounting bracket. When the flat panel display is operatively connected to the adapter bracket and the mounting bracket is attached to the surface, the flat panel display is generally selectively rotatably positionable about an axis substantially parallel to the surface as a result of the interaction of the first carrier mechanism with the set of substantially straight guide paths or surfaces.

In recent years, flat-panel television units have become enormously popular in both the commercial and the residential sectors. As the prices for plasma and liquid crystal display (LCD) flat panel displays have continued to fall, and as the quality for the same devices have improved, more and more businesses and individuals have purchased such devices both for business and home entertainment purposes.
One of the advantages of flat-panel television units that customers have found particularly appealing is their relatively low thickness. Because conventional "tube" televisions have a relatively large depth, the display options for such devices are quite limited. In the residential setting, most users require a television stand or large entertainment center to store the television. Such stands or entertainment centers can take up significant floor space, which is often undesirable. In the commercial or educational setting, users will often install large overhead mounting systems that can contain the television. However, these systems usually require professional installation and, once the television is secured in the mount, it is often very difficult to access and adjust due to its height.
With flat-panel televisions, on the other hand, users are presented with a relatively new option: mounting the television directly to a wall or similar surface. By mounting the television to a wall, a person can eliminate the need to take up potentially valuable floor space with a television stand or entertainment unit. Furthermore, individuals and entities can mount the television at a sufficiently low height to be able to adjust the television's orientation with little difficulty.
Although the introduction of flat-panel televisions on a wide scale has presented new opportunities to both residential and commercial customers, it has also presented new challenges. Over the past few years, a number of wall mounting systems have been developed for use with flat panel televisions, but each has their own drawbacks. The products described in these disclosures rely upon the use of a set of curved slots to form a rotatable connection between a mounting bracket and a support bracket. Although moderately useful, a rolling connection among the slots is required for the smooth tilting movement of the mounting bracket relative to the support bracket. Unfortunately, the curved slots themselves can cause the mounting systems' rolling pins to slip during the tilting process, which can lead to the mounting bracket, and therefore the attached television or display, to move in an abrupt, non-smooth fashion relative to the support bracket. Such movements can make it difficult for one to precisely position the television or display in the desired position. Additionally, gravity can, on occasion, cause the rolling pins to fall within the slots, which can cause the system to bind. In such a situation, it becomes more difficult to adjust the orientation of the flat panel display. Furthermore, with some newer plasma and LCD televisions being more sensitive and delicate than conventional tube televisions, such sudden slippage could also damage the devices.
U.S. Application Publication No. 2004/0245420 discloses a mounting system where a plurality of arc-shaped glides are used in place of the rolling pins. However, such glides may be more expensive to manufacture than rolling pins, are more difficult to assemble into the curved slots than the rolling pins, and are prone to suffering wear to the frictional sliding of the glides against the sides of the slots.
It therefore would be desirable to develop an improved rotatable connection for tilt mounting systems that addresses the above-identified shortcomings.


A disk changer for CD and DVD disks including a rotatable platter with several slots each adapted for receiving a disk generally needs two optical sensors. The first sensor is adapted for detecting the number of a related slot of the platter and for providing a stop signal for the rotation of the platter. The second sensor is adapted for detecting the presence or absence of a disk in a given slot. Said sensors and their associated evaluation circuits are expensive components. Therefore it is an object to simplify the means for realizing said sensors. Said second sensor has the form of a link hingedly mounted between its two ends a first end of the link contacting the surface of the disk and a second end of the link cooperating with said first optical sensor. By this solution said second sensor and its associated evaluation circuit can be omitted substantially reducing the total costs of the changer.

A disk changer adapted for CD or DVD disks generally includes a rotatable plate with several slots each for receiving a disk. The platter can be rotated on the chassis of the changer so that a desired disk can be moved to a playback unit optically reading the disk especially from the underside of the disk. Such an arrangement generally needs for proper operation two sensors. The first sensor generally in form of an optical sensor is adapted for sensing the number of a slot. Each slot carries some ribs of different number and size. Number and size of the ribs represent a code for the number of the respective slot. A sensor is provided on the chassis of the changer evaluating number and size of the ribs passing through the sensor during rotation of the platter. In this way each slot can be identified for feeding a disk to the playback unit the user wants to be reproduced. The second sensor is adapted to detect whether a disk is loaded in a given slot or not. This is useful, for example, to ignore or to skip a slot not containing a disk during a search operation by rotation of the platter in order to minimize the access time needed for finding a desired disk. Alternatively or additionally the second sensor can control a display unit showing which slot contains a disk and which slot does not contain a disk. The second sensor is not needed to be an optical sensor and may also be a mechanical sensor or whatever.
In fact, for both purposes several optical sensors and associated evaluation circuits are needed substantially increasing the total costs of the changer.


A driving force transmission apparatus has a driving gear; a driven gear; a toothed clutch transferring the driving force from driving gear to driven gear and which includes driving-side and driven-side ratchets that are movable in the axial direction of the clutch; and a compression spring biasing driven-side ratchet toward driving-side ratchet. When the tip end of the pawl of the driven-side ratchet is at the same position as the tip end of the pawl of the driving-side ratchet in the axial direction of the toothed clutch, the compression spring biasing force acts on the driven-side ratchet. And when the driven-side ratchet fully engages the driving-side ratchet, the biasing force does not act on the driven side ratchet.

1. Field of the Invention
The present invention relates to a driving force transmission apparatus having a toothed clutch that transmits a driving force received from a driving source, and a sheet conveyance apparatus.
2. Description of the Related Art
An image forming apparatus, such as a copier, a printer, a facsimile machine or a multifunctional apparatus having all these functions, mounts a thermal fixing device and a sheet conveyance mechanism, such as a recording material conveying belt mechanism. This sheet conveyance mechanism includes a sheet conveyance roller (or belt), which forms a sheet conveyance nip portion; a drive motor, for driving a sheet conveyance roller; and a driving force transmission mechanism, which transfers the driving force produced by a driving motor to the sheet conveyance roller.
When the image forming apparatus is abnormally halted because of a sheet jam in the sheet conveying mechanism and the sheet is caught at the conveyance nip portion, the sheet must be manually removed by a user, i.e., the jam must be cleared by the user. While the jam is being cleared, the sheet conveyance roller is rotated by friction between it and the sheet. At this time, because of the operating arrangement of the image forming apparatus, a driving force generated by the rotation of the sheet conveyance roller is transmitted to the driving motor via the driving force transmission mechanism, that is, a load produced by the rotation is imposed on the gear of the driving force transmission mechanism and thence on the driving motor. Therefore, removing the sheet is difficult and the sheet may sometimes be torn.
In order to reduce such a load, a driving force transmission mechanism having a function in which it is able to stop transmitting a driving force may be provided between the driving motor and the sheet conveyance roller. A toothed clutch is one example of such a driving force transmission mechanism. A toothed clutch includes a driving-side ratchet and a driven-side ratchet that are biased in the direction in which they are coupled. Thus, when the driving motor is rotated in the sheet conveying direction, the driving-side ratchet and the driven-side ratchet engage each other to transmit the driving force produced by the driving motor to the sheet conveyance roller. On the other hand, when a jam is being cleared and the sheet conveyance roller is rotated in the direction opposite to that in which a sheet is conveyed, the pawl of the driven-side ratchet slides over the pawl of the driving-side ratchet, so that the driven-side ratchet is not rotated and transmission of the driving force from the sheet conveyance roller to the driving motor is prevented. In this case, since the load imposed on a jammed sheet is comparatively small, a user can easily remove the sheet from the sheet nip portion.
However, for the conventional art described above, there are the following problems.
A user must rotate the driven-side ratchet forward a number of times when clearing a jam where a sheet is caught at the conveyance nip portion of the sheet conveyance roller. Therefore, the pawl of the driven-side ratchet must slide over the pawl of the driving-side ratchet many times. And since the driven-side ratchet and the driving-side ratchet are biased forward by a spring, in the direction in which they are coupled, the ratchet pawls forcefully strike each other each time the pawl of the driven-side ratchet slides over the pawl of the driving-side ratchet, and an impulsive sound (an action sound) is produced. It is assumed that this impulsive sound will frequently cause user discomfort.
As means for preventing the generation of such an impulsive sound, there is an arrangement whereby, when a user opens the cover of an apparatus to clear a jam, a lever that interlocks with the cover reversely impels the pawl of a driven-side ratchet separating, against the biasing force exerted by an biasing spring, away from the pawl of a driving-side ratchet (see Japanese Patent Application Laid-Open No. H10-142996). According to this arrangement, since the ratchet pawls do not forcefully strike each other while the user is removing the jam, the occurrence of the impulsive sound can be prevented. However, since a lever and an interlocking mechanism for securing the main body of the apparatus to the lever must be additionally provided, the number of parts is increased.
A pressure release mechanism is also proposed whereby, when a sheet jam has occurred, a drive motor is rotated in reverse, in the direction opposite that in which a sheet is normally conveyed, to remove the pressure imposed on a conveyance nip portion (see Japanese Patent Application Laid-Open No. 2000-029347). According to this arrangement, since no pressure is imposed on the conveyance nip portion while the jam is being cleared, the process can be easily performed.
However, the pressure release mechanism, for example, may not work, as in a case wherein power to the image forming apparatus is turned off during the image forming processing. At this time, while a user is clearing the jam, the ratchet pawls would strike each other and produce the above described impulse sound.
Further, according to the arrangement whereby the pressure imposed on the conveyance nip portion is released by rotating the driving motor in reverse, in the direction opposite to that in which a sheet is conveyed, the driving-side ratchet pawl will slide over the driven-side ratchet pawl each time the pressure release procedure is performed. And thus, an impulse sound will still be generated by the ratchet pawls.

Driving force transmission apparatus and sheet conveyance apparatus


An accessory for affixmentation to a recreational flying disk is disclosed in the form of a separate apparatus that is readily compatible and adaptable to any flying disk that will greatly enhance the flight distance length and the other flight characteristics of that retrofitted disk because of the centrifugal power, ballast stabilization and lift capability that the disclosed invention apparatus transmutes to the said flying disk. The disclosed apparatus, in conjunction with it being the aforementioned aerodynamic catalyst that it becomes once it is affixed to the said thrown flying disk, also can transform the said disk into a flying disk that can skip across the surface of a body of water not unlike a flat stone used for centuries for the same results—that same body of water that would render an ordinary flying disk as immobile upon contact with it now can be considered as just another obstacle to cross just as easily as flying aerially. The many variations of embodiments that are possible and probable are capable of being manufactured in an inexpensive method or manner such as by plastic molding or injection in and as a lightweight composite, which is a proven material both in the durability and safety factorage in the art of recreational flying disks.

1. Field of the Invention
The present invention relates to the many varieties of recreational flying disks currently in the marketplace and more precisely, to an apparatus that when attached to any recreational flying disk will exemplify the aerodynamics of that said flying disk resulting in a much longer distance of traveling in flight and the said disk being capable of traversing or 'skipping' on and over the surface of a body of water and if desired, a hard surface such as land, snow, or field of ice.
2. Description of the Related Art
Many variations of the recreational flying disk are currently available to the general consumer and differ in their size and composite material, from the very familiar soft pliable type used for throwing and catching to the smaller, stiffer and heavier types utilized for certain interactive games such as disk or Frisbee golf. Manufacturers have made many attempts to enhance the flight characteristics of flying disks by altering their shape or contour and their weight by providing the disk with a thicker or heavier circumstantial outside rim or just adding weight by manufacturing the flying disk in a heavier composite material. Also, attempts have been made to provide the flying disk with a means to be able to make it capable of traversing or hydroplaning across the surface of a liquid such as water by providing a solid surface on the underside of the disk, which unfortunately alters the aerodynamics of the disk relating to its lift capability, therein reducing the disk to poor flight and hydroplaning characteristics due to the interference with the most important of aeronautic flight principals of any flying structure including a flying disk; its lift capacity.

Recreational flying disk apparatus for enhanced flight enabling and traversing land and water surfaces


The combination multi-effect distillation and multi-stage flash evaporation system integrates a multi-stage flash (MSF) evaporation system with a multi-effect distillation (MED) system such that the flashing temperature range of the MSF process is shifted upward on the temperature scale, while the MED distillation process operates in the lower temperature range. The multi-stage flash evaporation system includes a plurality of flash evaporation/condensation stages, such that the multi-stage flash evaporation system receives a volume of seawater or brine from an external source and produces distilled water. The multi-effect distillation system includes a plurality of condensation/evaporation effects, such that the multi-effect distillation system receives concentrated brine from the multi-stage flash desalination system and produces distilled water.

1. Field of the Invention
The present invention relates to desalination, and particularly to a system for producing desalinated water from saltwater, such as seawater using both multi-effect distillation and multi-stage flash evaporation.
2. Description of the Related Art
A falling film evaporator is an industrial device to concentrate solutions, especially with heat sensitive components. The evaporator is a special type of heat exchanger. In general, the evaporation takes place on the outside surfaces of horizontal or vertical tubes, although it should be noted that there are also applications where the process fluid evaporates inside vertical tubes. In all cases, the process fluid to be evaporated flows downwards by gravity as a continuous film. The fluid creates a film along the tube walls, progressing downwards, hence the name "falling film".
In a falling film evaporator, the fluid distributor must be designed carefully in order to maintain an even liquid distribution for all tubes along which the solution falls. In the majority of applications, the heating medium is placed inside the tubes, thus high heat transfer coefficients can be achieved. In order to satisfy this requirement, condensing steam is commonly used as a heating medium.
For internally evaporating fluids, separation between the liquid phase (i.e., the solution) and the gaseous phase takes place inside the tubes. In order to maintain conservation of mass as this process proceeds, the downward vapor velocity increases, increasing the shear force acting on the liquid film and therefore also the velocity of the solution. The result can be a high film velocity of a progressively thinner film, resulting in increasingly turbulent flow. The combination of these effects allows very high heat transfer coefficients.
The heat transfer coefficient on the evaporating side of the tube is mostly determined by the hydrodynamic flow conditions of the film. For low mass flows or high viscosities, the film flow can be laminar, in which case heat transfer is controlled purely by conduction through the film. Therefore, in this condition, the heat transfer coefficient decreases with increased mass flow. With increased mass flow, the film becomes wavy laminar and then turbulent. Under turbulent conditions, the heat transfer coefficient increases with increased flow. Evaporation takes place at very low mean temperature differences between heating medium (i.e., process stream) and film liquid, typically between 3 K and 6 K, thus such devices are ideal for heat recovery in multi effect processes.
A further advantage of the falling film evaporator is the very short residence time of the liquid and the absence of superheating of the same. The residence time inside the tubes is typically measured in seconds, making it ideal for heat-sensitive products such as milk, fruit juice, pharmaceuticals, and many other mass-produced liquid products. Falling film evaporators are also characterized by very low pressure drops, thus they are often used in deep vacuum applications as well.
However, due to the intimate contact of the film liquid with the heating surface, such evaporators are susceptible to fouling from precipitating solids; liquid velocity, typically low at the top rows of a bank of horizontal tubes, is usually not sufficient to perform an effective self-cleaning of the tubes. Falling film evaporators are therefore typically used only with clean, non-precipitating liquids.
Falling film evaporation is the primary principle used in multi-effect distillation (MED) systems (sometimes also referred to as "multiple-effect distillation systems"). Multi-effect distillation is a distillation process often used for sea water desalination. It consists of multiple stages or "effects". In each effect, the seawater feed falls as a film over the outside surfaces of the tubes and is heated by steam inside the tubes. Some of the falling water film evaporates, and this vapor flows into the tubes of the next effect, heating and evaporating more water. Each effect essentially reuses the energy from the previous effect. Although the tubes can be submerged in the feed water, it is far more common that the seawater feed is sprayed on the top of a bank of horizontal tubes, and then drips from tube to tube until it is collected at the bottom of the effect.
FIG. 2 illustrates a typical prior art multi-effect distillation evaporator 100. In the first effect 102, seawater is fed, via an inlet 108, to one or more sprayers or nozzles 110 positioned within the first effect 102. Heated steam, produced by an external boiler or the like, is fed through a tube 112. As the sprayed seawater lands on the external surface of the tube 112, and forms a thin liquid film thereon, heat transferred from the heating steam causes the seawater to evaporate, forming water vapor V. The heat transfer cools the steam, producing condensate in the tube 112, which is then returned back to the boiler for subsequent re-heating. The seawater which does not evaporate (indicated as S in FIG. 2), drips from one portion of the tube 112 to another (or from tube to tube, in the case where multiple such tubes are used), until it is collected at the bottom 114 of the first effect. A pump 116 then delivers this collected seawater into the second effect 104, where it is sprayed by sprayers or nozzles 120, similar to the spraying in the first effect 102.
The water vapor V from the first effect is transferred by a second tube 118 into the second effect and acts in a similar manner to the steam passing through tube 112 in the first effect, except that the condensate in second tube 118, rather than being returned to the boiler, is drawn out through a product conduit 124, where distilled water is collected. The seawater S which does not evaporate into water vapor V in the second effect 104, once again, falls from tube portion to tube portion (or tube to tube) to be collected on the bottom 122 of the second effect 104. A pump 126 then delivers this collected seawater into the third effect 106, where it is sprayed by sprayers or nozzles 128, similar to the spraying in the first and second effects 102, 104.
The water vapor V from the second effect 104 is transferred by a third tube 130 into the third effect 106 and acts in a similar manner to the steam passing through tube 112 in the first effect 102 and the heated vapor passing through the second tube 118 in second effect 104. In the third effect 106, the condensate in third tube 130 is drawn out through the product conduit 124, where it mixes with the desalinated water from the second effect 104 to be collected. The seawater S which does not evaporate into water vapor V in the third effect 106, once again, falls from tube portion to tube portion (or tube to tube) to be collected on the bottom 132 of the third effect 106, where it is then pumped, by pump 134, to the next effect. Although only three effects 102, 104, 106 are shown in FIG. 2, it should be understood that this is shown for exemplary and illustrative purposes only. An example of a conventional multi-effect distillation system is shown in U.S. Pat. No. 3,481,835, which is hereby incorporated by reference in its entirety.
Conventional multi-effect distillation systems, such as the above, which generally rely on falling film evaporation, suffer from a number of drawbacks, each of which typically limits the design capacity of the units and the maximum permissible operating temperatures. On a broad level, many MED designs involve complex and often circuitous paths for heated seawater and vapor to minimize usage of pumps, maintain wettability of the tubes to avoid scaling, and to maximize energy recovery from the flashing brine and distillate. The farther the pumps, vessels, water routes and vapor routes are from minimal, optimized paths, the more the design suffers from excessive losses.
In addition to multi-effect distillation systems, multi-stage flash (MSF) evaporation is also relatively commonly used to produce desalinated water from saltwater sources, such as seawater. FIG. 3 shows a conventional prior art MSF system or plant 200, where feed seawater or brine enters the system under pressure, being drawn into the plant 200 via a pump 228 or the like. The seawater or brine is transported, under pressure, through conduits or pipes 232 to a brine heater 214, which then delivers heated brine to flash chambers 216. A steam generator 212, which is a separate simple steam power plant, external to the MSF system, supplies the brine heater 214 with the heating steam needed to heat up the brine. The steam generator 212 is a simple steam power plant (preferably a Rankine cycle power plant), and consists of a pump 240, a boiler 242, and a steam turbine 244, in addition to the condenser 214, which also acts as the brine heater. It should be understood that the steam turbine 244 shown in FIG. 3 is not a component of a typical MSF process, but is merely shown in this example as part of an exemplary plant utilizing MSF. The steam passing to the brine heater 214 may be extracted from a turbine, such as steam turbine 244, or may be fed directly from boiler 242. It should be understood that the simplified illustration of FIG. 3 is provided merely to describe a conventional MSF process and system. Typically, a de-superheater would also be used to condition the steam, whether extracted from a turbine or passing directly from a boiler, prior to entering the brine heater 214, thus ensuring that the steam is saturated and not superheated. Conventional MSF systems are well-known. U.S. Pat. Nos. 3,966,562 and 8,277,614, both of which are hereby incorporated by reference in their entirety, show conventional MSF systems.
As shown, the seawater or brine may also be first drawn through a cooler 230 in order to reduce the temperature of the feed, thus also the temperature of the last stage. The brine is then passed through the feed heater conduits 232. The feed heaters are condenser type heat exchangers where feed is heated by the heat released from condensing the vapor flashed off in each stage. Feed brine reaches the first stage at an elevated temperature, however it is not high enough to start flashing, and therefore, additional heat must be supplied to the brine. The brine heater 214 receives steam from the external steam generator 212, and elevates the brine temperature to the level suitable to start flashing. The brine is then injected into the flash chambers 216. It should be understood that the number of flash chambers 216 shown in FIG. 3 is shown for exemplary purposes only, and is a simplification of the number of flash stages. Typical MSF plants have between fifteen and forty stages or flash chambers. The brine delivered by the heater 214 typically has a temperature of between approximately 90° C. and 120° C., depending upon the chemical treatment or scale prevention technique used, the quality of heating steam, and the ejection system maintaining pressure in each stage.
The operating pressure in the flash chambers 216 is lower than that in the heater, thus causing the heated brine to rapidly boil or "flash" into vapor. Typically, only a small percentage of this water is converted into vapor. Consequently, the remaining water will be sent through a series of additional stages or flash chambers 216, as shown, each possessing a lower operating pressure than the previous chamber. The brine is delivered through each successive flash chamber 216 or stage through any conventional method. As vapor is generated, it is condensed in the same stage or flash chamber on the pipes 232, which run through each chamber. The condensed water is then collected by collection trays 218 and is removed by a pump 220 to produce a stream of desalinated water 222. The pipes 232 and trays 218 form the condensers for each flash stage. The remaining brine with a high saline concentration may be drawn out by a separate pump 224, and removed as waste at 226.
In the MSF process, heat transfer surfaces, which are on the brine side, are never subject to change of phase and are always kept wet and relatively free of scale precipitation by effective scale control techniques, typically involving chemical treatment of feed water and on-line mechanical cleaning. Flashing of the brine occurs at a safe distance from heat transfer tubes. This procedure makes the MSF process fairly protected from scale formation and precipitation up to the temperatures at which sulfate-based scales begin to form (i.e., above 121° C.).
In the MED process, on the other hand, evaporation takes place directly on the outside surfaces of the heat transfer tubes as the brine film reaches the liquid superheat temperatures needed for the change of phase to occur. Such an evaporation mechanism makes heat transfer surfaces highly vulnerable to scale formation and precipitation, especially since only chemical treatment can be used to retard scale formation while on-line mechanical cleaning is not possible. This situation imposes severe restrictions on the maximum practical operating temperatures in the MED process, which must be kept within a safe range (i.e., below 70° C.).
The conventional MSF process suffers from three primary sources of thermodynamic loss, namely boiling point elevation loss, pressure drop loss, and non-equilibrium loss. The boiling point elevation loss is due to the presence of salts at high concentrations in the brine, thus it is a loss that must be present in any process involving boiling or change of phase and its value depends on the state of the brine solution in terms of its temperature and concentration. Boiling point elevation loss increases with temperature as well as with concentration. In the MSF process, both driving forces of the boiling point elevation act conversely, since flashing brine temperature decreases while its concentration increases as the brine flows toward the lower temperature stages. Consequently, the resulting effect of this behavior minimizes the variations in the boiling point elevation across the MSF stages.
The pressure drop caused by the flow of vapor through the demisters and through the tube bundle results in vapor expansion, which is accompanied by a drop in its corresponding saturation temperature. This is known as pressure drop loss and it is far less in magnitude as compared with boiling point elevation or non-equilibrium losses, and it usually increases as the brine flows toward the lower temperature stages. The non-equilibrium loss, unlike the previous two losses, is an inherited characteristic of the MSF process. The amount of this loss is inversely proportional to the stage thermal level and it is directly proportional to the flashing brine depth. To illustrate such a characteristic, one can define the vapor equilibrium temperature in the brine pool at a given depth below the surface as T*b=T*0+
                              ⅆ                      T            *                                    ⅆ          P                    ·      γ                                    h      b        ,where T*0 is the vapor equilibrium temperature at the stage pressure,
      ⅆ          T      *            ⅆ    P  represents the rate of change in vapor saturation temperature vs. pressure, and γhb represents the hydrostatic pressure in the brine pool at a given depth hb below the surface.
FIG. 4 shows plots for T*b at different values of hb over typical flashing ranges of the conventional MSF process. FIG. 4 shows that the effect of the brine depth on vapor equilibrium temperature in the brine pool is quite insignificant for high thermal level stages and it becomes rapidly significant for the lower thermal level stages. In other words, taking (Tb)in and (Tb)out as the brine bulk temperatures at the stage inlet and outlet less the boiling point elevation, then (Tb)in>T*b is a condition necessary for evaporation to occur at any point on the brine surface and below to a maximum depth of hb. For high thermal level stages, this condition is usually furnished even for the maximum submergence in the brine pool. However, for evaporation to remain effective as the brine travels through the stage towards its outlet, the condition (Tb)out>T*b must be sustained for a significant depth in the brine pool. As the brine flows toward lower thermal level stages, the condition (Tb)in>T*b>(Tb)out becomes prevalent even for minimum brine depth, which indicates that evaporation may take place only near the surface at the stage inlet and it lessens until it diminishes as the brine approaches the stage outlet, thus making a significant part of the stage nonproductive.
FIG. 5 is a plot of the three losses and the resulting total thermodynamic losses across the stages of a typical prior art MSF unit. FIG. 5 shows the changes in the relative magnitudes of these losses as fractions of the total average temperature difference between flashing and recycling brine along the stages of the MSF unit. Contrary to MSF, non-equilibrium thermodynamic losses are non-existent in the MED process. This is because evaporation occurs in the superheated liquid film rather than by flashing of the liquid pool. On the other hand, both boiling point elevation and pressure drop losses exist to an extent similar to that of the MSF process. However, these losses have far less significance as far as the thermal performance of the MED process is concerned, mainly because the evaporation temperature range is already limited to a narrow low temperature stretch, and also because the overall heat transfer coefficient at these low thermal levels is almost double that of the MSF process.
The combined effect of these losses is illustrated by the per-stage and the accumulated mass flow rates of product distillate shown in FIG. 6 for a typical prior art MSF unit. FIG. 6 clearly shows that stage productivity is directly dependent on stage thermal level, and that low stage productivity in the stages of the lower temperature range in the MSF process is an inherent characteristic.
Two basic quantities must be first established when an MSF or an MED plant is under consideration, namely the plant's production capacity and the available thermal energy in the form of low-grade steam required to drive any of these plants to produce the desired output. The guidelines for measuring MSF and MED plant effectiveness, or the process potential, are usually based on these two quantities and are known in combination as the gain output ratio (GOR) or the performance ratio (PR). The GOR is defined as the mass ratio between the product distillate (in kilograms per unit time) and the steam supplied to the process (also in kilograms per unit time). The PR is defined either as the amount of distillate mass (in kilograms per a predefined quantity of latent heat due to condensation of the heating steam, measured in kilojoules) or the amount of heat supplied (in kilojoules) to produce one kilogram of distillate. These ratios depend on several parameters, some of which are the top brine temperature (TBT), number of evaporation stages or effects, available flashing temperature range, mass ratio of the brine subject to evaporation and the product distillate, concentration of the brine, and effectiveness of evaporation stage or effect. There are, however, certain technical and economic limitations to the upper values of the GOR or PR that can be achieved for any process. However, one must be cautious when comparing these quantities (GOR or PR) for MSF with that of MED, since heating steam conditions, and, hence, the grades of energy supplied to each process, are usually quite different. It would be desirable to be able to integrate MSF with MED such that the flashing temperature range of the MSF process is shifted upward on the temperature scale for better performance of the MSF at relatively higher operating temperatures, while the MED subunit incorporated into the MSF system operates in the lower temperature range for better performance in this range.
Thus, a combination multi-effect distillation and multi-stage flash evaporation system solving the aforementioned problems is desired.

This patent is subject to a terminal disclaimer.

Combination multi-effect distillation and multi-stage flash evaporation system

Kuwait Institute for Scientific Research


A reticle and a method of fabricating the samer for projecting a fine pattern on an object surface comprises: a. transparent substrate; a first type phase-shifter selectively patterned and deposited on the substrate producing a phase difference between the light passing therethrough and the light passing through the other areas without phase-shifter; and a second type phase-shifter selectively patterned and forming a groove in the substrate producing a phase difference between the light passing therethrough and the light passing through the other areas without phase-shifter. The reticle may include a patterned shield layer which interrupts transmission of light, and the phase difference of the first and second type phase-shifters is many times selected substantially equal to a half wavelength of light. Another type of a reticle comprises: a transparent substrate; a phase-shifter of a first groove; and another phase-shifter of a second deeper groove formed in the first groove.

1. Field of the Invention
This invention relates to a reticle used for projecting a very fine pattern on a semiconductor substrate in photolithography and, more particularly, to a reticle into which phase-shifters are incorporated and to a method of fabricating the reticle with the phase-shifters.
With a trend toward higher integration of an integrated circuit, patterns formed on a semiconductor substrate in photolithography are required to be ever finer and more precise. A reticle having phase-shifters is one of the solutions therefor.
2. Description of the Related Art
It is known that a magnified pattern with a magnification ratio of about 1 to 10 is formed on a reticle and the reticle pattern is projected forming a reduced real image on a semiconductor substrate by a step and repeat method using a so-called stepper.
When dimensions constituting the pattern on the semiconductor substrate are reduced to submicron order, there arises a problem in that two lights which penetrate through two adjacent transparent portions of the reticle pattern, the two portions being separated by a narrow strip portion containing the pattern to be projected onto the substrate, interfere with each other, and accurate strip pattern is not projected and formed on the semiconductor substrate.
In order to solve the interference problem between the two adjacent lights, a phase-shifter technique has been introduced into the reticle fabrication process.
Typical known reticle structures with phase-shifters are described herein. FIG. 1 shows a cross section of a known reticle structure with phase-shifters. On a reticle substrate 1 manufacture of glass or quartz, a light-shielding layer 2 and 2' containing the pattern to be projected onto the substrate (hereinafter abbreviated as shield layer), generally a chromium (Cr) or a chromium compound is formed in a conventional method. Of the two adjacent openings 30 and 31, one opening 31 between shield layers 2 and 2' is covered with a phase-shift layer 3 (hereinafter abbreviated as phase-shifter) which has a function of improving the resolution in photolithography.
The lights 33 and 34 impinging on the bottom surface of the reticle and traveling a distance t, undergo a different phase shift due to an existence of the phase-shift layer 3 (in an actual case, the reticle is arranged upside down in the stepper). When a thickness of the phase-shift layer is properly selected, two lights passing through the reticle can be made to have an opposite phase (phase-shift of .pi.) to each other. This results in forming a distinct image pattern of the middle Cr layer 2' onto the semiconductor substrate because the adverse effects from the adjacent lights from both sides are eliminated.
FIG. 2 shows a cross section of another known reticle structure with phase-shifters. In the same way as in FIG. 1, a pattern of light-shielding layers 2 are formed on a glass substrate 1. However, in this case, a phase-shifter 3' has the shape of a groove or well formed under a window 31 between the two adjacent light-shielding layers 2 and 2'. The groove is formed by subjecting the substrate 1 to a conventional unisotropic etching process such as RIE (Reactive Ion Etching), in which only the substrate surface for the area where the groove is to be formed is exposed and the remaining areas are covered with a resist layer. The function of the phase-shifter 3' is almost the same as the phase-shifter 3 of FIG. 1. However, in this case, the light 33 traveling a distance d within the substrate causes a phase difference of .pi. from the light 34 which travels the same distance d through the groove without substrate material.
With a reticle with phase-shifters, fine complicated patterns are formed on a semiconductor substrate. However, in the process of fabricating a reticle, defects are often formed in the patterns of shield layer 2 or phase-shifters 3. In addition, though a reticle with phase-shifters has been completed, it may be required that a small portion of the pattern needs to be modified or changed. Therefore, it is an important that the reticle pattern be able to be repaired or modified.
When it is found that the shield layer 2 includes a missing portion or void portion, or an unnecessary extra portion in its pattern before forming phase-shifters, these defect portions are comparatively easily repaired using a Focused Ion Beam (hereinafter abbreviated as FIB) apparatus.
When the phase-shifter 3 is formed and includes a missing portion or an unnecessary extra portion in its pattern, the extra portion can be removed using the above FIB apparatus and the reticle can be repaired. However, if the defect is a missing portion in the phase-shifter pattern, the reticle can not be repaired easily.
The FIB apparatus will be briefly described. FIG. 3 shows a schematic cross section of the FIB apparatus. Ions are emitted from an ion gun 6 and gallium (Ga) ions are popularly used therein. The emitted ions are focused by a condenser lens 7 and further on-off controlled by a blanking electrode 8 and a blanking aperture 9. An object lens 10 and a deflection lens 11 have the function of focusing and projecting an ion beam onto an object 14 to be processed at a specified scanning position. The object can be moved by an XY-table 15. The ion beam can sputter-and-etch the object, and a secondary ion detector 12 can detect the object and identify the ion beam position. When a gas is introduced from a gas injection gun 13, the ion beam resolves or separates the gas, and the resolved elements or components can be deposited on the object 14.
In order to remove the unnecessary extra, portion of the shield layer 2 or the phase shifter 3, the unnecessary portion is subjected to irradiation of the above ion beam by moving the XY-table and scanning the ion beam. However, when the phase-shifter 3 of FIG. 1 has a missing portion, or when the groove-shaped phase-shifter 31 of FIG. 2 includes an extra groove portion which should not have been taken away, the process of depositing phase-shifter material or substrate material and repairing the void or missing portion of the phase-shifters is very difficult. The reason is that the thickness of phase-shifter 3 and depth of phase-shifter 3' is too large or deep (a few thousands angstroms) to bury or fill the void portion using the FIB apparatus. Even if silicon dioxide, which is a popular material for a phase-shifter, is deposited by the FIB apparatus, the deposited phase-shifter contains gallium. Since the gallium containing silicon dioxide is not transparent, silicon dioxide does not work as a phase-shifter.

Reticle with phase-shifters and a method of fabricating the same


An airbag system for jointly supporting at least two vehicle occupants inside a motor vehicle in case of an accident with at least two separate airbags inflatable with a gas supplied by a gas generator. The airbag system has at least two airbags (14, 15) folded into a common housing (10) to be arranged in the dashboard of the motor vehicle. The airbags are connected to a common gas generator (11) having at least two outflow areas (13, 18, 19) assigned to the at least two airbags (14, 15). Each airbag (14, 15) is sealed by a deflector (16, 17) inserted therein against the respectively other airbag (14, 15), and the airbags are fixed inside the housing (10).

The invention relates to an airbag system for jointly supporting at least two vehicle occupants inside a motor vehicle in case of an accident. The airbag system has at least two separate airbags inflatable by gas supplied by a gas generator.
German Patent Specification DE 43 02 891 C2 discloses an airbag system which is designed to support at least two vehicle occupants, especially in the knee region. To this end, the prior-art airbag system has two separate airbags arranged in the center console of a motor vehicle. When triggered, these airbags are inflated by a common inflation device and emerge laterally from the center console so that they extend in front of the knees of the vehicle occupants sitting to the right and the left of the center console supporting them in the knee region.
The airbag system disclosed in DE 43 02 891 C2 cannot be used to support the upper body of several, or at least two, vehicle occupants by means of airbags inflatable from the dashboard. To solve this problem it is known from Patent Specification DE 199 33 586 C1 or German Laid Open Publication DE 196 20 537 A1 to divide a single airbag into several chambers. The airbag extends in front of the two or more vehicle occupants and consists of a uniform textile blank, using suitable configurations.
An airbag system designed in this manner has several drawbacks. Such a system can be optimally configured only for two persons of identical size penetrating the central airbag uniformly. If only one person is to be protected, one problem is that the internal pressure of the large airbag required to produce a corresponding retaining action cannot be reached because the volume of the airbag is too large. In the case of two persons of very different size and different body weight, the vehicle occupants also cannot be optimally protected because the differences in body size and body weight cannot be taken into account. Also, if the vehicle occupants are sitting in different positions relative to the airbag prior to the accident, very different retaining actions result, even for identical occupants. Furthermore, such a single airbag has a very large volume. Since the time required for inflation must be comparable to that of other airbag systems, such a large airbag must be filled with a substantially greater volume flow per time unit. Very high loads can occur especially for vehicle occupants sitting near the area in front of the deploying airbag, i.e. in a so-called out/off position.
Thus, an object of the invention is to provide an airbag system which offers both or several vehicle occupants equal protection for the loading cases that have to be assumed.
This object, including advantageous embodiments and refinements of the invention, is attained as set forth in the claims following this description.


A driving-force transmitting member is formed of a material having a linear expansion coefficient larger than that of a sleeve bearing, and Δx1>r1×Δt×a−R1×Δt×b is satisfied, where R1 is inner radius of the sleeve bearing, r1 is outer radius of a rotary shaft unit, Δx1 is difference between the inner radius R1 and the outer radius r1 at a reference temperature, Δt is maximum amount of temperature change of the driving-force transmitting member relative to the reference temperature, a is linear expansion coefficient of the sleeve bearing, and b is linear expansion coefficient of the driving-force transmitting member.

1. Field of the Invention
The present invention relates to a driving-force transmission device and an image forming apparatus that employs the driving-force transmission device.
2. Description of the Related Art
A driving-force transmission device that is employed in an image forming apparatus transmits a rotary driving force from a driving source such as a motor to a rotating unit (drive target) such as an image carrier. When the rotating unit is detachable from the image forming apparatus, the driving-force transmission device typically includes a gear (driving-force input unit) that receives the rotary driving force from the driving source, a rotary shaft mounted on the gear, and a coupling member that is mounted on the rotary shaft and couples to a coupled portion of the rotating unit. A driving-force transmission device having such a configuration is disclosed in, for example, Japanese Patent Application Laid-open No. 2002-328499. With such a configuration, fluctuation in rotational velocity of the rotating unit largely depends upon adverse effect by a gear and a coupling member. The adverse effect by the gear includes eccentricity of the gear and eccentric error in mounting the gear on a rotary shaft, and the adverse effect by the coupling member includes eccentricity of the coupling member, eccentric error in mounting the coupling member on rotary shaft, and an engaging gap between the coupling member and a coupled portion.
The adverse effect by the eccentricity of the gear and the coupling member can be suppressed by improving molding accuracy.
Furthermore, the adverse effect by the gap between the coupling member and the coupled portion can be suppressed by applying spline engagement in which the coupling member and the coupled portion can be molded with low shape error and can be easily detached. In the spline engagement, one of the rotary shaft of the rotating unit and a boss portion of a driving-force transmitting member is formed into a spline shaft, and a spline hole is formed in the other. The spline shaft is inserted into the spline hole to mesh external teeth on the spline shaft with internal teeth in the spline hole.
Moreover, the adverse effect by the eccentric error in mounting the gear or the coupling member on the rotary shaft can be suppressed by mounting the gear and the coupling member on the rotary shaft without causing backlash.
Recently, resin has been increasingly used for forming a gear and a coupling member on the beneficial aspects of vibration, noise, and cost. On the other hand, metal is often used for a rotary shaft on the beneficial aspect of torsional stiffness. However, with a combination use of parts molded from different materials, linear coefficient of expansion differs between the parts. Therefore, a gap may be formed at engaging portion between the rotary shaft and the gear or between the rotary shaft and the coupling member due to temperature change in an operating environment and heat generated from a driving source in an image forming apparatus. This leads to backlash of the gear or the coupling member relative to the rotary shaft and eccentric rotation of the gear or the coupling member, resulting in fluctuation in rotational velocity of the rotating unit.
To address such fluctuation, the inventors of the present invention have invented a driving-force transmission device that employs a driving-force transmitting member including a rotary shaft unit, a gear, and a coupling member, all of which are integrally formed using the same material of resin. The use of such a driving-force transmission device does not cause the backlash even if the driving-force transmitting member thermally expands. Therefore, the eccentric rotation of the gear and the coupling member can be sufficiently suppressed.
However, the inventors found that the above driving-force transmitting member causes the following problem.
The driving-force transmitting member needs to be supported in a rotatable manner in an image forming apparatus to allow transmission of a rotary driving force that is input to the gear, from the coupling member to a drive target. Therefore, the driving-force transmitting member needs to be supported at least at two support portions by a support member such as a side plate on a side of an image forming apparatus via a metal sleeve bearing. With the use of such a sleeve bearing, sliding friction between an outer circumferential surface of the rotary shaft unit of the driving-force transmitting member and an inner circumferential surface of the sleeve bearing can be suppressed low over a prolonged period. In this manner, generally, the driving-force transmitting member can be rotatably supported by the support member for a long period. However, resin that forms the driving-force transmitting member has the linear coefficient of expansion larger than metal that forms the sleeve bearing. Accordingly, if the driving-force transmitting member thermally expands by temperature rise in an operating environment or heat from a heat source such as a motor, a gap between the outer circumferential surface of the rotary shaft unit and the inner circumferential surface of the sleeve bearing is reduced, so that friction loading between the outer circumferential surface of the rotary shaft unit and the inner circumferential surface of the sleeve bearing increases, i.e., rotation load on the driving-force transmitting member increases, leading to overload on the motor to be stopped.
The countermeasure for the above is to reduce a diameter of the rotary shaft unit at the support portion to as small as possible to suppress a dimensional change in the rotary shaft unit when the driving-force transmitting member thermally expands. However, in the driving-force transmitting member employing an engagement in which one end of the rotary shaft unit engages with an engaging target arranged concentrically with the rotary shaft unit (for example, spline engagement) as a configuration of the gear and the coupling member, a diameter of the one end of the rotary shaft unit needs to be increased to assure the strength of the one end. Therefore, when the driving-force transmitting member thermally expands, the dimensional change of the rotary shaft unit is increased at the support portion in the one end (large-diameter portion), resulting in overload on the motor to be stopped.
Still worse, at the support portion on the side of the large-diameter portion, frictional heat between the outer circumferential surface of the rotary shaft unit and the inner circumferential surface of the sleeve bearing causes the rotary shaft unit to be melted and adhered to the sleeve shaft. Under such a circumstance, if rotation of the sleeve bearing is restricted relative to the support member (including the case where the sleeve bearing cannot rotate relative to the support member due to increased frictional force caused by the thermally-expanded sleeve bearing), the driving-force transmitting member can not be rotated, causing overload on the motor to be stopped.
Such a problem occurs not only in the case where the driving-force transmitting member is formed of resin and the sleeve bearing is formed of metal, but also in the case where the driving-force transmitting member is formed from a material having linear coefficient of expansion larger than that for the sleeve bearing.
Furthermore, this can occur also between the sleeve bearing and the support member. If the sleeve bearing is formed from a material having linear coefficient of expansion larger than that for the support member, frictional force between the sleeve bearing and the support member increases by the thermally-expanded sleeve bearing, so that a motor may stop due to overloading. Moreover, if the rotation of-the sleeve bearing is restricted relative to the driving-force transmitting member (including the case where the driving-force transmitting member cannot rotate relative to the sleeve bearing due to the thermal expansion of the driving-force transmitting member), the diving-force-transmitting unit can not be rotated and the motor may stop due to overloading.

Driving-force transmission device and image forming apparatus


A circuit is disclosed for shifting and rotating operands of multiple size. In one embodiment, first and second shifter circuits are provided with the first shifter circuit configured to receive a z bit operand. In this embodiment, the first and second shifter circuits can operate in one of several modes depending on the size of the operand to be shifted or rotated. In one mode, the z bit operand provided to the first shifter circuit includes a y bit operand to be shifted and a copy thereof. The y bit operand and its copy are separated by a plurality of bits each one of which represents a logical zero. The first shifter circuit is coupled to first and second control nodes which are configured to receive control signals. When the first and second control nodes receive a first control signal, the first shifter circuit operates as a full shifter for shifting the received z bit operand in one direction by x bits. When the first and second control nodes receive a second control signal, the first shifter circuit operates as a partial shifter for shifting y bits of the received z bit operand in the one direction by x bits.

1. Field of the Invention
This invention relates to shifters or rotators, and more particularly to a circuit for shifting or rotating operands of multiple size.
2. Description of the Relevant Art
Microprocessors determine the speed and power of personal computers, and a growing number of more powerful machines, by handling most of the data processing in the machine. Microprocessors typically include at least three functional groups: the input output unit (I/O), the control unit and the arithmetic logic unit (ALU). The I/O unit interfaces between external circuitry and the ALU and the control unit. I/O units frequently include signal buffers for increasing the current capacity of the signal before the signal is sent to external components. The control unit controls the operation of the microprocessor by fetching instructions from the I/O unit and translating the instructions into a form that can be understood by the ALU. In addition, the control unit keeps track of which step of the control unit is being executed. The ALU handles the mathematical computations and logical operations that are performed by the microprocessor. The ALU executes the decoded instructions received from the control unit to modify data contained in registers within the processor.
Essential components of any ALU include the operand shifter and operand rotator. The shifter generally operates to shift an operand left or right by x bits with zero fill. The rotator generally operates to rotate an operand left or right by x bits. Often times, the shifter and rotator are combined into a single shifter/rotator circuit in order to conserve the physical size of the ALU. Furthermore, the shifter/rotator can be constructed and operated to shift or rotate operands of multiple size to avoid employing several shifter/rotators each designated for use on operands of a single size.
FIG. 1 illustrates a prior art shifter/rotator 10 capable of shifting or rotating eight bit or four bit operands either left or right depending upon the control signals inputted thereto and how the shifter/rotator 10 is loaded. Generally, shifter/rotator 10 is a double left shifter configured to also right shift operands provided thereto as will be more fully explained below. Shifter/rotator 10 includes a pre-shift stage 12 which has two functions one of which is to pre-shift four bit operands so that they are properly aligned for a rotation operation. Shifter/rotator 10 also includes a first shifting stage 14 for shifting operands provided thereto by one bit, second shifting stage 16 for shifting operands provided thereto by two bits, and third shifting stage 18 for shifting operands provided thereto by four bits. Shifter/rotator 10 is arranged so that the first, second, and third shifting stages 14, 16, and 18, respectively, receive the result operand of the pre-shifting, first, and second shifting stages, respectively.
Shifter/rotator 10 further includes upper input nodes 20, lower input nodes 22, and output nodes 26. The eight output nodes 26 provide the results of shifting or rotating an eight bit operand, while the four least significant output nodes 26 provide the results of shifting or rotating a four bit operand.
As noted above, shifter/rotator 10 operates to shift or rotate four or eight bit operands depending upon the operands provided to input nodes 22 and 24. More specifically, a shift left of an eight bit operand is accomplished by providing the eight bit operand to be shifted to the upper input nodes 20 and logical zeros to each of the lower input nodes 22. A shift right of an eight bit operand is accomplished by providing a logical zero to each of the upper input nodes 20 and the eight bit operand to be shifted to the lower input nodes 22. Rotating an eight bit operand left or right is accomplished by providing the eight bit operand to both the upper and lower input nodes 20 and 22, respectively.
A shift left of a four bit operand is accomplished by providing the four bit operand to be shifted to the four least significant upper input nodes 20, a logical zero to each of the four most significant upper input nodes 20, and a logical zero to each of the lower input nodes 22. Shifting a four bit operand right is accomplished by providing a logical zero to each of the upper input nodes 20, a logical zero to each of the four most significant lower input nodes 22, and the four bit operand to be shifted to the four least significant lower input nodes 22. Rotating a four bit operand either left or right is accomplished by providing the four bit operand to be rotated to the four least significant upper and lower input nodes 20 and 22, respectively, and a logical zero to each of the four most significant upper and lower input nodes 20 and 22, respectively.
Pre-shift stage 12 is configured to receive a sixteen bit operand consisting of the concatenated bits provided to upper and lower input nodes 20 and 22. Pre-shift stage 12 includes a pair of shifting stages which operate to selectively shift the sixteen bit operand left by one and/or realign a four bit operand provided to the four least significant lower input nodes 22. One of the pair of shifting stages includes a first set of multiplexers 44 coupled to and controlled by a pre-shift control node 46. The other shifting stage includes a second set of multiplexers 50 coupled to and controlled by a right shift control node 52. Multiplexers 44 operate to selectively left shift the four bit operand provided to the four least significant lower input nodes 22 in accordance with a control signal provided to pre-shift control node 46. More specifically multiplexers 44 operate to pass either the four bit operand provided to the four least significant lower input nodes 22 when pre-shift control node 46 receives a logical one, or the four logical zeros provided to the four most significant lower input nodes 22 when pre-shift control node 46 receives a logical zero. In general, multiplexers 44 shift or align the four bit operand provided to shifter/rotator when shifter/rotator circuit 10 is employed to rotate a four operand left or right. Multiplexers 50 operate to selectively shift the sixteen bit operand, with or without realignment by multiplexers 44, left by one according to a control signal provided to right shift control node 52. More specifically, multiplexers 50 operate to pass either the fifteen least significant bits of the sixteen bit operand provided thereto when the right shift control node 52 receives a logical one, or the fifteen most significant bits of the sixteen bit operand provided thereto when the right shift control node 52 receives a logical zero. As will be described below, multiplexers 50 of pre-shift stage 12 operate to shift left by one when shifter/rotator 10 is employed to right shift or right rotate a four or eight bit operand.
First shifting stage 14 includes a plurality of two input multiplexers 30 coupled to and controlled by a first shift control node 32. First shifting stage 14 is configured to receive the fifteen bit result operand of pre-shift stage 12. First shift stage 14 operates to selectively shift the result operand left by one bit according to a control signal provided to the first shift control node 32. In other words, first shifting stage 14 operates to pass either the fourteen least significant bits of the fifteen bit result operand provided by pre-shift stage 12 when the first shift control node 32 receives a logical one, or the fourteen most significant bits of the fifteen bit result operand provided by pre-shift stage 12 when the first shift control node 32 receives a zero.
Second shifting stage 16 includes a plurality of two input multiplexers 34 coupled to and controlled by second shift control node 36. Second shifting stage 16 is configured to receive the fourteen bit result operand of the first shifting stage 14. Second shifting stage 16 operates to selectively shift the result operand left by two bits in accordance with a control signal provided to second shift control node 36. In other words, second shifting stage 14 operates to pass either the twelve least significant bits of the fourteen bit result operand provided by first shifting stage 14 when the second shift control node 36 receives a logical one, or the twelve most significant bits of the fourteen bit result operand provided by first shifting stage 14 when the second shift control node 36 receives a logical zero.
Third shifting stage 18 comprises a plurality of two input multiplexers 40 coupled to and controlled by a third shift control node 42. Third shift control node 42 is configured to receive the twelve bit result operand provided by second shifting stage 16. Third shifting stage 18 operates to selectively shift the result operand left by four bits in accordance with a control signal provided to third shift control node 42. In other words, third shifting stage 16 operates to pass either the eight least significant bits of the twelve bit result operand provided by second shifting stage 16 when the third shift control node 42 receives a logical one, or the eight most significant bits of the twelve bit result operand provided by second shifting stage 16 when the third shift control node 42 receives a logical zero.
As noted above, shifter/rotator is a double left shifter which can right shift operands in addition to left shifting operands. Shifter/rotator can also rotate operands left or right. One of ordinary skill in the art will recognize that shifting or rotating an operand right by a designated shift count using a double left shifter is equivalent to shifting or rotating the same operand by the negative of the shift count. Further, one of ordinary skill in the art will recognize that in two's compliment notation, the negative of the shift count equates to the complemented shift count and binary one. Rather than employing a separate circuit to calculate the negative shift count in order to achieve a right shift or a right rotate, the shifter/rotator circuit 10 achieves right shift or a right rotate simply by complementing the shift input provided to control nodes 32, 36 and 42, and by asserting logical one to the right shift control node 52.
As noted above, each shifting stage 12-18 is controlled by corresponding control nodes 32, 36, 42, 46, and 52. Control nodes 32, 36, and 42 receive a shift count provided by an instruction to shift or rotate an operand. Control nodes 52 and 46 receive control signals associated with instructions for right shifting four or eight bit operands and/or rotating four bit operands. For example, when an eight bit operand is to be shifted or rotated left by five bits, control nodes 32, and 42 receive a logical one while control nodes 36, 52 and 46 receive a logical zero. When a four bit operand is to be shifted left by three bits, control nodes 32 and 36 receive a logical one while control node 42, 52 and 46 receive a logical zero. When a four bit operand is to be rotated left by three bits, control nodes 32, 46 and 36 receive a logical one while control node 42 and 52 receive a logical zero.
As can be appreciated, pre-shift stage 12 complicates the design and operation of shifter/rotator 10. More particularly, pre-shift stage 12 is complicated by the presence of the first set of multiplexers 44 coupled to and controlled by the pre-shift control node 46. Shifter/rotator 10 would require an even more complicated pre-shifting stage 12 if shifter/rotator 10 were configured to shift four, eight or sixteen bit operands.
From an inspection of FIG. 1 and the description relating thereto above, it is apparent that operation and implementation of shifter/rotator 10 can be simplified if the first set of multiplexers 44 within pre-shift stage 12 can be eliminated. This would have the effect of reducing the size of the shifter/rotator 10 in addition to increasing its speed of operation.

Circuit for shifting or rotating operands of multiple size


An apparatus and method for use in a semiconductor memory device to reduce or eliminate read disturbance effects. Select signals supplied from one or more address decoders to a memory array are used to select particular wordlines and bitlines of the array. Read disturbance effects can arise when select signal voltage stresses are applied for extended periods of time to terminals of memory cells coupled to the selected wordlines and bitlines. The memory device therefore includes circuitry to detect a transition in at least one of the select signals, and to generate a timing signal from the detected transition. The timing signal is supplied to the address decoders and directs the decoders to deselect previously-selected wordlines and bitlines at a predetermined time after the transition. The predetermined time is chosen to be greater than or equal to the total time required to read data reliably from the selected memory cells before the deselection of the wordlines and bitlines. The deselection ensures that voltage stresses will not be applied to selected memory cells for extended periods of time, and the contents of the cells are therefore not unintentionally altered due to read disturbance effects.

FIG. 1 shows a portion of a conventional floating gate memory device 10. Floating gate memory devices such as device 10 may be programmed using hot electron injection and erased using Fowler-Nordheim tunneling as is well-known and described in detail in U.S. Pat. Nos. 5,029,130 and 5,289,411. The device 10 includes a memory array 12 of floating gate memory cells 14. The memory array 12 includes a plurality of wordlines WL(j), j=1, 2, . . . J and a plurality of bitlines BL(k), k=1, 2, . . . K. A floating gate memory cell 14 located at the intersection of each WL(j) and bitline BL(k) is used to store a single bit of data. The device 10 includes an address input buffer 16 which receives an N-bit input address ADDR(0:N) designating a particular wordline WL(j) of cells 14 in the array 12. The address buffer 16 supplies portions of the input address ADDR(0:N) to an X or row pre-decoder 18. The X pre-decoder 18 supplies partially-decoded wordline address signals to a worldwide decoder 20 which selects the particular wordline WL(j) corresponding to the input address ADDR(0:N). The address buffer 16 also supplies a portion of the input address to a Y or column pre-decoder 22, which in turn supplies partially-decoded bitline address signals to a bitline decoder 24.
The device 10 in this example is configured as an 8-bit device and bitline decoder 24 therefore selects eight bitlines BL(k) corresponding to a group of eight memory cells 12 on the selected wordline WL(j), and supplies the data programmed in the selected cells to one input of a multiple sensing amplifier 26 via data lines DL(0:7). The multiple sensing amplifier 26 includes eight sensing amplifiers, each of which compare the data signal on one of the lines DL(0:7) to a reference SENREF. The multiple sensing amplifier 26 thus senses and amplifies the retrieved data on data lines DL(0:7) and supplies the resulting signals to an output buffer 28. The output buffer 28 supplies the retrieved data to output pins DQ(0:7) when enabled by an output enable (OE) signal supplied by a control logic circuit 30. The control logic circuit 30 receives complements of the OE signal, a chip enable (CE) signal and a write enable (WE) signal, and controls the operation of address input buffer 16 as well as other elements of the device 10. The device 10 may be configured as a 16-bit device, 32-bit device and so on by suitable alteration of the number of bitlines in a particular selected group of bitlines BL(k), the number of sensing amplifiers in multiple sensing amplifier 26, and the number of lines DL, DQ and the like.
Data may be programmed into the cells 14 of a selected word line WL(j) of array 12 in the following manner. The wordline decoder 20 supplies a threshold potential typically less than +5 volts to the selected wordline WL(j) and thereby to the gates of the cells 14 coupled to that wordline. A voltage of approximately +12 volts is supplied from a high voltage (HV) decoder (not shown) to the source of each of the cells 14 in the selected wordline via a corresponding N+ source line SL(j). A given cell 14 in the selected wordline is then programmed to a particular logic value by bringing the corresponding bitline BL(k) and thereby the drain of the given cell 14 to either 0 volts or +5 volts depending on the logic value to be programmed. Hot electrons from the source of the given cell 14 can thereby be injected into and stored on the floating gate of the cell.
Data may be read back from the cells 14 of a selected wordline WL(j) by bringing the sources of the cells to ground potential via source line SL(j), the drains of the cells to a read voltage on the order of +2 volts via corresponding bitlines BL(k), and the gates of the cells to about +5 volts via wordline WL(j). This will generate for each cell a signal indicative of the stored charge in that cell. These signals are amplified by sense amplifier 26 and supplied to output buffer 28 in the manner previously described.
Data may be erased from the cells 14 of a selected wordline WL(j) by bringing the source of the cells to ground potential via source line SL(j), the drains of the cells to ground potential via corresponding bitlines BL(k), and the gates of the cells to a potential of about +15 volts via the wordline WL(j). The high voltage potential on the gate of the floating gate cells 14 causes the charge stored on the floating gate to be removed by the mechanism of Fowler-Nordheim tunneling.
The above-described programming and erasing operations generally involve applying relatively high DC voltages to the cells 12 for periods of time on the order of milliseconds or microseconds. However, the contents of the memory cells 14 may also be unintentionally altered if lower DC voltages are applied to the cells for much longer periods of time. For example, the above-described read operation involves applying a voltage on the order of +5 volts to the gates of the memory cells 14 in a selected wordline WL(j). If the memory device 10 is placed in an active read mode in which +5 volts is applied to the gates of the cells 14 but no wordline or bitline addresses change for a relatively long period of time, the cells 14 may gradually gain or lose charge such that the stored logic values may be unintentionally altered. This unintentional alteration of stored charge under DC stress over relatively long periods of time is referred to as "read disturbance."
FIG. 2 is a timing diagram illustrating the read disturbance problem in greater detail. Several of the signals shown in the device 10 of FIG. 1 are illustrated over three time periods A, B and C. During period A, the device 10 is inactive as indicated by the logic high level of the complemented CE signal applied to control logic circuit 30. The input address ADDR(0:N) is therefore ignored and the wordline (WL) signal and bitline (BL) signal are maintained at logic low levels such that all wordlines and bitlines are deselected.
During period B, the complemented CE signal goes low, and the device 10 is placed in an active read mode. The input address specifies a particular selected wordline WL(m) and a group of selected bitlines designated BL(n). In accordance with the above-described read operation, the selected wordline WL(m) is brought to a voltage of about +5 volts and the selected group of multiple bitlines BL(n) are brought to a read voltage on the order of +2 volts as shown in FIG. 2. The data from the cells designated by the intersection of wordline WL(m) and bitlines BL(n) is then read out in the manner previously described.
During period C, the complemented CE signal remains low and device 10 remains in an active read mode. The input address ADDR(0:N) in period C specifies a different wordline WL(j) and set of bitlines BL(k), such that the selected wordline WL(j) is brought to a voltage of about +5 volts and the selected bitlines BL(k) are brought to a read voltage on the order of +2 volts as shown. However, the active read mode of period C is a "DC idle" read mode in which the input address ADDR(0:N) does not change for an extended period of time. This places multiple cells on selected wordline WL(j) under a long-term DC stress on the order of +5 volts, places multiple cells on selected bitlines BL(k) under a long-term DC stress on the order of +2 volts, and places selected cells at the intersection of WL(j) and BL(k) under both +5 volt and +2 volt stresses.
As noted above, such long-term DC voltage stresses can result in the unintentional alteration of stored charge in the stressed cells, leading to the loss of programmed data and therefore device malfunction. Conventional memory devices such as device 10 of FIG. 1 provide no sufficiently effective mechanism for reducing or otherwise alleviating these read disturbance effects.
It is therefore an object of the present invention to provide an improved memory device in which read disturbance effects may be substantially eliminated without unduly increasing the die size or power consumption of the device.

Semiconductor memory device with reduced read disturbance


An open circuit gravity-assisted uroflowmeter has a urine collector having a generally open inlet in fluid communication with a sensing passage located at a lower elevation than the inlet, the sensing passage intersecting a magnetic field and having electrodes for detecting a flow-dependent voltage induced by the passage of urine through the magnetic field. Preferred embodiments of the uroflowmeter may have low pressure drop, rapid response and simple construction.

Uroflowmetry devices are used to measure urine discharge flow rates or total discharge volumes for diagnostic or research purposes. A variety of devices have been employed, including weight cells, rotameters, spinning disk or spinning rotor sensors, drop spectrometer sensors, air displacement sensors, capacitive sensors and pressure sensors. References describing such devices include U.S. Pat. Nos. 4,099,412, 4,683,748, 4,732,160, 5,046,510, 5,062,304, 5,078,012, 5,176,148 and 5,495,854.
Other references describing flow measurement devices include U.S. Pat. Nos. 4,008,609, 4,118,981, 4,145,924, 4,434,667, 4,881,413, 4,899,592, 5,207,105, 5,325,728, 5,327,787, 5,708,212, 6,237,424 B1 and 6,463,807 B1.

Open circuit gravity-assisted uroflowmeter


A self-contained, hydraulically operated clutch-type coupling, allowing a minimum of two vehicular type internal combustion engines to be mounted in tandem replacing the standard single block, multi cylinder engine. Flexibility is provided to the driver by a computerized control system to select operation of one or more engines to produce minimum to maximum horsepower at the flywheel, necessary to meet specific road and traffic conditions while maintaining a constant engine (RPM) speed. In one embodiment, a single engine is started to minimize undesirable emissions due to the combination of cold start conditions and wall quenching and fuel conservation purposes. Upon attaining engine operating temperature uniformity, the succeeding engine(s) can be started and operated to provide maximum available horsepower/torque to meet road load conditions. A second embodiment includes primary engine standard throttle linkage providing an input signal to the computer controlling total engine (RPM) speed by means of a stepper motor driving the secondary engine throttle linkage after synchronization of the two or more engines is attained and monitored by crankshaft sensor and tachometer input to the computer.

Heretofore, internal combustion engines have been manufactured based on a constant speed/fixed volume design in that the engine speed in revolutions per minute (RPM) and piston displacement are the major factors in determining horsepower and torque delivered at the flywheel. The final delivered horsepower/torque requirement necessary for a particular application is established to satisfy anticipated road load conditions consisting of (a) rolling resistance, (b) air resistance, (c) vehicular gross weight and (d) road grade.
Road Horsepower is expressed by the formula: ##EQU1## Where: Cr=Coefficient of Rolling Resistance
Ca=Coefficient of Air Resistance PA1 V=Vehicle speed, MPH PA1 A=Frontal area in square feet PA1 W=Gross Weight in pounds PA1 G=Road Grade, percent PA1 First, the designer/manufacturer will no longer be required to make assumptions during design of a specific engine to cover all possible driving conditions in a single block multi-cylinder engine and arrive at a single optimal horsepower curve. Instead this invention affords the availability of two or more specific horsepower/torque curves at the flywheel to economically adapt to a variety of road and driving conditions. PA1 Second, the invention will substantially reduce the amount of hydrocarbon emissions in the exhaust due to wall quenching during cold starts and normal operating conditions. PA1 Third, the invention will drastically reduce hydrocarbon and nitrogen oxide emissions together therefor decreasing smog products. PA1 Fourth, the invention will provide improved economic use of petroleum base fuels increasing the mileage (MPG) due to the flexibility of allowing the operator to select the engine volume required to meet specific conditions re: gross-load, heavy traffic, idling, cruising speeds, road grade and air resistance.
Predicated on the assumed requirements, a final design for a specific single block of four, six, eight or more cylinders is produced for installation in a variety of production type vehicles. Since the engine design and selection is based on a variety of assumed conditions, it is in most cases oversized for the greater percentage of use normally encountered.
Air pollution contributed by vehicle emissions includes Hydrocarbons (HC), Carbon Monoxide (CO), Oxides of Nitrogen (NO), Oxides of Sulfur (SO2) and Particulate Matter. Of the total Hydrocarbon Emissions from uncontrolled vehicle engines, 20 to 25 percent is caused by crankcase blow-by, 60 percent of the undesirable exhaust emissions are formed mainly within the combustion chamber of the engine during or after the combustion process and appear in the exhaust. The remainder of the emissions are contributed to evaporative losses.
In a four cycle, water cooled engine "wall quenching" is the predominate source of exhaust hydrocarbons. Wall quenching is a combustion phenomena that arises when a flame attempts to propagate in the vicinity of a surface or wall. Normally the effect of the wall is a slowing down or stopping of the reaction. In general, wall quenching results from both the chain breaking of the chemical reactions of the fuel/air mixture and from the cooling of the layer of charge adjacent to the wall (which is cooler than the rest of the combustion chamber). As a result the flame will not propagate completely to the wall surface. Wall quenching is the principal source of unburned hydrocarbons in the exhaust of an engine under most normal conditions and is extremely high during cold start conditions.
Of course hydrocarbons present a serious environmental concern. At a level of 0.15 parts per million (ppm) oxidant, approximately 50 percent of the population experience some eye watering. Further, a reduction of nitrogen oxide first increases then decreases smog products; therefore, nitrogen oxide and hydrocarbons together should be reduced to virtually zero before a smog benefit is realized.
To date state of the art engines are fixed volume in design. Due to the single block multi-cylinder vehicle engines presently in use, petroleum base fuels are used uneconomically during periods of cold starting, heavy traffic (when engine idling and extremely slow speeds are encountered) and at cruising speeds when road conditions, rolling resistance, air resistance and grade do not require full design horsepower. In recent years due to Federal mandates, automotive manufacturers have developed and placed in use a variety of emission control systems. These systems along with the electronic ignition, fuel injection and the use of unleaded fuel have contributed greatly to the decrease of exhaust and evaporative emissions, but have not reached the emission standard goals projected for the future. Also, these emission control systems, which are add-on in nature, have further contributed to the inefficient use of gasoline fuels.
Based on information available in the "1991 Gas Mileage Guide, EPA Fuel Economy Estimates, October 1990, DOE/CE-0019/10", the average mileage (miles per gallon) for passenger type automobiles manufactured in the United States is 18.14 MPG city and 24.64 MPG highway. The current practice within the automotive manufacturing industry of utilizing a single block multi-cylinder engine based on the constant speed/fixed volume concept continues to contribute now and into the future to excessive air pollution and the inefficient use of petroleum base fuels.

Internal combustion engine constant speed variable volume coupling and operation process


An adapter for use with a nozzle manifold of a hot runner injection molding system for fluidly connecting at least two runner sections and thereby distribute and conduct melt to cavities of an injection mold, includes a plug having at least one end face formed with a first opening for fluid connection to one runner section and a cylindrical or conical wall surface formed with a second opening for fluid connection to another runner section and extending at an angle with respect to the one end face, and a force-applying unit so acting upon the plug as to urge the end face and the wall surface into a fluid-tight pressure fit upon mating surfaces of the nozzle manifold.

The present invention refers generally to an adapter for connecting at least two runner sections of a nozzle manifold of a hot runner injection molding system for distributing and conducting a flow of melt to the cavities or hot runner nozzles. More specifically, the present invention refers to an adapter of a type having a preferably rotationally symmetrical body exhibiting at least one end face connected to one of the runner sections and a cylindrical or conical wall surface connected to another runner section and extending at an angle with respect to the one end face.
Adapters of this type are known in a variety of designs, e.g. in European Patent Specification No. 0 226 798. Of interest are in particular those adapters for fluidly connecting runner sections of a hot runner system in a fluid-tight manner whereby the runner sections are aligned and/or angled to one another.
In general, conventional adapters have the disadvantage that one end of the runner section, e.g. the melt inlet opening or melt outlet opening, is formed in the flat end face while the second end exits at the cylindrical surface of the adapter. Although, conventional adapters can be so designed as to allow a sealing of mating plane surfaces of the adapter and the nozzle manifold by tightly clamping the adapter to the manifold body by means of suitable screw threads, such screw threads act however in only one direction so that the fluid-tightness of the cylindrical outer adapter surfaces depends solely on the quality of the fit between both sections whereby the fit should be so designed as to allow an easy disassembly of the adapter for cleaning purposes as well.

Adapter for a nozzle manifold of a hot runner system