An apparatus and a method are disclosed for rapidly controlling the rate of ion generation in an ion source. The ion source includes an ion chamber, filament-cathode, a mirror electrode, and a grid. The ion source is operable to generate an ion beam from the ionization of ion precursor gas present in the ion chamber by electrons emitted from the filament. The rate of ion generation is controlled by modifying the potential of the grid relative to the filament to control the number of electrons available for ionization between the grid and the mirror electrode. An alternative embodiment for rapidly controlling the rate of ion generation in an ion source is also disclosed. In the alternative embodiment, the ion source comprises an ion chamber having mutually opposed sides and configured to receive ion precursor gas; a filament-cathode located on one side of said ion chamber and operable to emit electrons for the ionization of the precursor gas for the generation of the ion beam; and a mirror electrode having a potential associated therewith and located on the other side of said ion chamber. The mirror electrode is connected to a circuit to vary its potential relative to said filament so as to vary the number of the electrons available in the ion chamber for ionization.

The development of the ion implantation industry continues to increase demand for systems having higher ion beam current capacity, which has led to performance challenges such as instability and slow responsiveness. In the manufacture of semiconductor devices in the past, semiconductor wafers were modified by diffusing or implanting positive or negative ions (dopants), formed from precursors such as boron, phosphorus, arsenic, antimony into the body of the wafer to produce regions having varying conductivity. Various ion implanters are known, using several types of ion sources. In most ion sources, an ion beam of a preselected chemical species is generated by means of the current applied to a filament within an ion source chamber coupled to a power supply and fitted with an ion precursor gas feed. The ions are extracted in the form of an ion beam through an aperture in the ion source chamber by means of a potential between the source chamber, which is positive, and an extraction means. The beam is directed to an acceleration system, a magnetic analysis stage that separates the desired ions from unwanted ions on the basis of mass, and a post acceleration stage that ensures delivery of the required ions at the required beam current level to the target or substrate wafer to be implanted. The size and intensity of the generated ion beam can be tailored by system design and operating conditions; for example, the current applied to the filament can be varied to regulate the intensity of the ion beam emitted from the ion source chamber.
The most common type of ion sources used for ion implanters are a Freeman source and a Bernas source. In the Freeman source, a rod-like filament, or cathode, made of tungsten or tungsten alloy is passed into an ion chamber (sometimes known as an "arc chamber") whose walls are the anode. The ion chamber includes a gas feed for delivering the desired gas into the chamber for use in generating the desired ions, a filament supply for heating the filament to about 2000 degrees Kelvin up to about 2800 degrees Kelvin to emit thermal electrons, and an exit aperture. A magnet is provided that applies a magnetic field parallel to the filament to increase the electron path length and to suspend the plasma (ions and electrons) within the chamber. Numerous other features and aspects of the Freeman type ion chamber are shown and described in U.S. Pat. No. 4,754,200, the teachings of which are incorporated herein by reference.
The Bernas type ion chamber is substantially identical to the Freeman-type chamber and differs primarily in that the Bernas chamber uses a filament in the form of a loop at one end of the ion chamber in contrast to the rod-like filament that extends through the Freeman ion chamber. Other aspects of the Bernas ion chamber are shown and described in U.S. Pat. No. 5,262,652, the teachings of which are incorporated herein by reference.
In both the Freeman and the Bernas ion chambers, when power is supplied to the filament, the filament temperature increases until electrons are emitted that bombard and breakup the precursor gas molecules such that a plasma is formed containing the electrons and various ions. The ions are emitted from the ion source chamber through the exit aperture and are selectively passed to the target as the ion beam.
For stable ion source operation in Freeman and Bernas sources, the arc voltage and the arc current are required to be relatively constant. This was accomplished through control of the arc current by a feedback loop that controlled filament power, as explained in detail in the '200 and '652 patents. If the arc current dropped, an arc current measuring circuit together with arc current error circuit would alter the filament power control circuit to bring the actual arc current back to the level demanded. Because of the thermal inertia of a high-resistance filament, the filament power control loop for maintaining constant arc current responds relatively slowly to changes in programming.
An attempt to overcome these problems used an ion implanter having an ion chamber that operated to maintain the ion beam current by varying the arc voltage on the filament cathode while supplying direct current electrical power across the filament cathode (as described in the '200 patent). In particular, the '200 patent teaches a scheme of control that varies the arc voltage to provide a faster response while using a slower servo on the filament to maintain the beam current at the desired value.
This ion chamber is not ideal for large ranges of control since the ionization efficiency depends on the arc voltage, and the beam current extracted from the source will not remain constant if the arc voltage is varied over a wide range even if the arc current is kept constant.
The mirror electrodes in the prior art are connected to the filament cathode or are left floating. In either case, the mirror electrode charges up to the filament potential and the electrons from the filament do not have the energy to reach the electrode.
Thus, what is needed is an ion source that can rapidly control the number of electrons available for ionization.

System and method for rapidly controlling the output of an ion source for ion implantation


Faults in a computer system having circuits are managed by fault detectors connected to detect fault states of respective circuits. A fault manager associates the fault states with the respective circuits. The fault manager includes a system manager connected to identify which of the circuits is causing faulty operation in the computer system. The fault detectors associated with the respective circuits are configured to detect faulty operation of and to generate fault state information for the respective circuits. A central manager is connected to accumulate fault state information from the fault detectors. One of the circuits includes a bus, and the fault state includes a bus error condition. The bus is connected to multiple devices, and the fault manager identifies which of the multiple devices causes the bus error condition. One of the circuits includes multiple modules, and the fault manager identifies fault states of the multiple modules. The modules include state machines. One of the circuits includes an internal clock, and the fault state of the circuit includes the internal clock not functioning properly. One of the circuits includes a temperature sensor, and the fault state of the circuit includes a high temperature condition detected by the temperature sensor.

The invention relates to fault diagnosis.
Critical hardware failures in a computer system may occur in components such as a fan, a power supply, a central processing unit (CPU) or memory boards, or an I/O bus. Typically, a non-maskable interrupt (NMI) or system management interrupt (SMI) is generated to handle the failure. When an SMI or NMI is asserted, the CPU is aware that a catastrophic failure has occurred which necessitates the shut-down of the computer system.
Other types of failures can also be detected in a computer system. For example, the bus agents on a Peripheral Component Interconnect (PCI) bus include data error detection logic (e.g., parity error checker), which asserts a parity error signal PERR.sub.-- if the data error is detected. The PERR.sub.-- signal is shared among the PCI agents. Catastrophic errors on the PCI bus, such as an address parity error, can be reported by asserting a system error (SERR) signal, which may cause the NMI to be asserted to the CPU.

Method and apparatus for diagnosing fault states in a computer system


A load sharing, multi-module power supply system for supplying power to a load. The system may involve: a first power supply module having a controller, and having a first per unit capacity (pu-c); a second power supply module having a controller, and having a second per unit capacity (pu-c); the controller of the first power supply module adapted to implement a reduction in an output power of the first power supply module upon the detection of an operating event, where a portion of the load being handled by the first power supply module is shed by a percentage, and such that the first power supply module remains operating during the operating event but at a reduced power output level; and upon the occurrence of the operating event the controller of the second power supply module is adapted to increase a power output of the second power supply module sufficient to accommodate the portion of the load that has been shed by the first power supply module.

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Multi-module power supplies, for example uninterruptible power supply ("UPS") systems, have multiple UPS's, typically referred to as a UPS module, and typically load share among the UPS modules. Load sharing is used to equalize the stress on each UPS module and to provide the maximum range of load increase while causing the minimum load change for any individual UPS module. Each UPS module of the multi-module UPS system is limited to operating within its thermal capability to prevent damage to its internal components. When the internal temperature of a module reaches a maximum, the UPS module is disconnected (e.g., shut down) from the load until the problem is resolved, such as a repair made. This will result in either loss of redundant UPS module and/or an increase in the load for the UPS modules remaining connected to the load.
FIG. 1 shows a basic block diagram of a prior art multi-module UPS system 100. While multi-module UPS system 100 is shown as having two UPS modules 102, it should be understood that multi-module UPS system 100 can have more than two UPS modules 102.
Each UPS module 102 includes input magnetics subsystem 104 (such as an input transformer), an output of which is coupled to an input of an AC/DC converter 106. The AC/DC converter 106 may typically be a rectifier having switched rectifying devices, such as SCR's, thyristors, MOSFETs or the like. An output of AC/DC converter 106 is coupled to an input of DC/AC converter 108 as is an output of a back-up power source 110. Back-up power source 110 can be a battery bank, flywheel, fuel cell, generator or the like that provides power in the event of interruption of input power to multi-module UPS system 100, such as from a electric power utility distribution system. DC/AC converter 108 may illustratively be an inverter. An output of the DC/AC converter 108 is coupled to an input of output magnetics subsystem 112, which may be an output transformer. An output of output magnetics subsystem 112 is coupled to an output of the multi-module UPS system 100, which provides power to a load. A bypass switch 114 may be coupled between the input of UPS module 102, such as the input of input magnetics subsystem 104, to the output of UPS module 102, such as the output of output magnetics subsystem 112. Temperature sensors 116 may be coupled to one or more of input magnetics subsystem 104, AC/DC converter 106, DC/AC converter 108 and output magnetics subsystem 112. Temperature sensors 116 may also be coupled to a controller 118 which controls UPS module 102. Controller 118 may be a programmable device such as a microcontroller, computer or the like. Preferably, temperature sensors 116 are coupled to the components 104, 106, 108 and 112 of every UPS module 102, as indicated in FIG. 1.
FIGS. 2A and 2B are basic schematic illustrations of load sharing in prior art multi-module UPS systems, such as multi-module UPS system 100. In FIG. 2A, each UPS module 102 of multi-module UPS system 100 has the same capacity, or per-unit rating ("pu-c"). The load on multi-module UPS system 100, referred to as the "system load," in FIG. 2A is shared equally among the UPS modules 102. That is, each UPS module 102 supplies the same percentage of the system load. In FIG. 2B, two of the UPS modules 102 have a 1 pu-c and two have a 2 pu-c. The system load is shared proportionally among the UPS modules 102 based on their individual pu-c. That is, each UPS module 102 supplies proportionally a percentage of the system load based on its pu-c.
In multi-module UPS systems such as multi-module UPS system 100, the temperature of critical components, inlet air and exhaust air of each UPS module 102 are monitored to determine if that UPS module 102 is operating within an acceptable range of temperatures. If cooling is insufficient resulting in excessive temperature, an abnormal condition is alarmed and eventually the UPS module 102 is shut down. This can unnecessarily stress the remaining, operating UPS modules, provided the UPS module experiencing an excessive temperature can still be operated satisfactorily at some reduced power output level.

System and method for load sharing in multi-module power supply systems


Provided is an optical recording medium including: two discs, each of which includes a substrate and a plurality of recording layers; and an attachment layer which is provided between the two discs and includes ultraviolet curable resin, wherein thickness of each of the substrates in the two discs is equal to or greater than 0.3 mm and equal to or less than 0.545 mm, wherein transmittance of the two discs is equal to or less than 20%, and wherein inversion rates on both surface sides of the attachment layer are equal or substantially equal to each other, and are equal to or greater than 70%.

The present disclosure relates to an optical recording medium provided with two substrates and a manufacturing method of the same.
As an optical recording medium, an attachment-type optical recording medium such as a digital versatile disc (DVD) has widely been used. The optical recording medium is manufactured by laminating two substrates via ultraviolet curable resin, curing the ultraviolet curable resin, and attaching the two substrates to each other.
In relation to the attachment-type optical recording medium, a technique for suppressing occurrence of warpage of the medium has been studies. For example, Japanese Unexamined Patent Application Publication 2003-99985 discloses manufacturing of a flat attachment-type substrate by holding two thin substrates by a substrate holding unit with an ultraviolet curable adhesive interposed therebetween, adsorbing and holding the thin substrates by a holding table provided at the holding unit, and correcting warpage and deformation occurring in the thin substrates.

Optical recording medium and manufacturing method of the same


A planar irradiating coil including a first ring conductor, a second ring conductor having a smaller diameter than that of the first ring conductor, and a plurality of first line conductors that connects the first ring conductor and the second ring conductor, is provided with means for causing the irradiation pulse to be more uniform. That is, in order to make the irradiation pulse more uniform, it is necessary to disperse the operating voltage or to diverge the irradiation current. Therefore, the irradiating coil is provided with a plurality of resonant capacitance elements on the first ring conductor between its connections with the first line conductors, or it is provided with second line conductors, that are connected to the first line conductors, and third line conductors, that connect each end of the second line conductors with the second ring conductor.

A magnetic resonance imaging apparatus (hereinafter referred to as an MRI apparatus) is designed to measure the concentration distribution and the relaxation time distribution of nuclear spins at a desired portion to be examined within an object to be examined, utilizing the nuclear magnetic resonance phenomenon, and to display an image of a cross section of the object obtained from the obtained data.
The nuclear spins of an object, which is placed within an apparatus for generating a uniform and strong magnetic field, perform precession at a frequency (Lamor frequency) determined by the magnetic field strength around an axis in the direction of the magnetic field. When a radio-frequency pulse having a frequency equivalent to the Larmor frequency is irradiated to the object from the outside, the nuclear spins are excited and shift to a higher energy state (nuclear magnetic resonance phenomenon). When the radio-frequency pulse irradiation to the object is terminated, the nuclear spins return to a low energy state at a time constant in accordance with their respective states, and they radiate electromagnetic waves (NMR signal) to the outside of the object. The electromagnetic waves are detected by a radio-frequency receiving coil, which is synchronized with their frequency.
Here, gradient magnetic fields on x-, y-, and z-axes are applied to the magnetic field space so as to add positional information to the NMR signals. Consequently, the positional information within the space can be obtained as frequency information.
For radio-frequency pulse irradiation, an irradiating coil is used which generates a radio-frequency magnetic field in a direction perpendicular to the static magnetic field direction. This irradiating coil has been researched and modified to obtain an improvement of the irradiation uniformity over a wide area in the magnetic field space, and various types of coils have been used.
FIG. 1 is a diagram showing one example of an irradiating coil, wherein an example of a planar birdcage coil is shown. Referring to FIG. 1, two concentric ring conductors 1a and 1b having different sizes on the same plane are mutually connected by a plurality of line conductors 2, extending in the radial direction.
FIG. 2 is an equivalent circuit diagram of the planar birdcage coil. Referring to FIG. 2, a loop a and a loop b designate the ring conductor 1a and the ring conductor 2a, respectively. The loop a and the loop b are usually synchronized at a magnetic resonance frequency. For the synchronization, condensers C and coils L are used.
FIG. 3 is a diagram showing the voltage distribution and current distribution in the loop a shown in FIG. 2. Referring to FIG. 3, the current is maximized and the voltage is minimized at the feeding points d, since the loop a is synchronized at the resonance frequency.
FIG. 4 is a diagram showing one example of the irradiating planar birdcage coil shown in FIG. 1, which is mounted in an MRI apparatus. Referring to FIG. 4, an irradiating coil 18 is usually located in the vicinity of an object 14 to be examined so as to efficiently apply an irradiation pulse to the object 14. Around the object 14, there are arranged a receiving coil 17 for receiving magnetic resonance signals that are generated from the object 14, a pre-amplifier 22 for amplifying the received signals, distribution lines 23 for connecting the signals that are amplified by the pre-amplifier 22 to an A/D converter (not shown), and the like, which are usually mounted in a bed on which the object 14 is supported. The receiving coil 17, the pre-amplifier 22, and the distribution lines 23 may be arranged in one location, for ease of manufacturing and operationality.
FIG. 5(B) is a graph showing an intensity distribution of radiation that is applied to the object, the intensity having been measured at arbitrary points (c, d, e, f, g, h, i, and j, along the phantom line circle in FIG. 5(A)) on the line conductors 2 of the above-mentioned planar birdcage coil. In FIG. 5(B), the vertical axis represents the irradiation intensity, and the horizontal axis represents locations along the phantom line circle. As shown in FIG. 5(B), the irradiation intensity is larger on the line conductors 2 than in the space between the line conductors 2, and it has a pulse shape that is pulsing with a uniform width.
As shown in FIG. 4, in the MRI apparatus, imaging is performed while the object 14, on which the receiving coil 17 is placed, is mounted on the bed. The pre-amplifier 22, for amplifying the signals sent from the receiving coil 17, and the distribution lines 23 are installed in the bed.
To adjust the location of the object 14 so as to image a particular portion, the bed is constructed so that it can be moved. However, the positional relation between the pre-amplifier 22, the distribution lines 23 and the irradiating coil 18 is changed by moving the bed, since the pre-amplifier 22 and the distribution lines 23 are installed in the bed. Consequently, a potential difference is generated between the potential of the receiving coil 17, the pre-amplifier 22, and the distribution lines 23, and that of the irradiating coil 18, and so a radio-frequency coupling is generated. The strength of the radio-frequency coupling fluctuates when the positional relation is changed, since the positional relation affects the potential difference.
Next, the fluctuation of the radio-frequency coupling will be described with reference to FIG. 6. Referring to FIG. 6, the irradiating coil 18 operates as a QD coil. Here, reference number 8 represents a condenser C in the circuit diagram of FIG. 2, and it is located where the voltage is maximized in FIG. 3.
Usually, in a QD coil, one feeding point does not affect a resonant circuit of another feeding point, since the two feeding points are perpendicularly arranged. However, as shown in FIG. 4, when only one side of the irradiating coil is subject to radio-frequency coupling due to the effect of the distribution lines 23 (in FIG. 6, the pre-amplifier 22 and the distribution lines 23 are arranged as shown) or the like, the pre-amplifier 22 and the distribution lines 23 are located where the potential of the irradiating coil 18 is high. In this case, radio-frequency coupling between the pre-amplifier 22, the distribution lines 23, and the irradiating coil 18 is caused to fluctuate with fluctuation of the positional relation between the pre-amplifier 22 and the distribution lines 23.
Next, this fluctuation of the potential will be described with reference to FIG. 7. FIG. 7 shows a voltage that is generated in resonant circuits d and d′ in FIG. 6. The respective voltage distributions of circuits d and d′ are indicated by the v1 and v1′ solid lines in ideal conditions. The potential of v1′ at a point where the potential of v1 is highest (or lowest) is the base potential, and this prevents radio-frequency coupling. However, when the object 14 is moved, or the bed is moved, the pre-amplifier 22 and the distribution lines 23 are moved relative to the irradiating coil 18. They are moved to a location where the potential of the resonant circuit d is the highest, whereby the potential is shifted as shown in FIG. 7 (represented by the broken line). Consequently, the location where the potential of d is a base potential is shifted from the point e, whereby fluctuation of a potential difference between d and d′ is generated. Consequently, the orthogonality of the QD coils d and d′ between d and d′ is lost, and a radio-frequency coupling is generated between them.
An error in the phase of the radio-frequency magnetic field generated from the two coils of the QD coil occurs, varying from 90 degrees due to the above-described radio-frequency coupling, and, consequently, the uniformity of the radiation pulse and the irradiation efficiency are deteriorated. However, in the conventional technique, consideration for the radio-frequency coupling between the irradiating coil 18 and the distribution lines 23 in the vicinity thereof has not been given.
Also, in the planar birdcage coil, line conductors 2 are radially arranged between the two ring conductors 1a and 1b, which have different sizes. Consequently, the irradiation intensity is large in the vicinity of the central portion close to the ring conductor 1b, since the distance between two line conductors is narrow. On the contrary, the irradiation intensity is small on the periphery close to the ring conductor 1a, since the distance between two line conductors is broad. That is, the irradiation intensity distribution is lower where the line conductors 2 are farther from the ring conductor 1b, whereby the overall irradiation distribution is not uniform. Therefore, when imaging a relatively large object, the sensitivity in the portions other than the central portion in the obtained image is lower, in comparison with the central portion.
Thus, in the conventional technique, consideration to provide a uniform irradiation pulse has not been given.

Irradiation coil and magnetic resonance imaging apparatus comprising the same


According to one embodiment, a semiconductor storage device includes a semiconductor pillar including a channel. The channel includes a first channel portion and a second channel portion. A virtual cross section intersecting a first direction and including a first interconnection, a first electrode, the semiconductor pillar, a second electrode, and a second interconnection is determined. Both first end portions of the first channel portion and a first midpoint between both the first end portions are determined in the virtual cross section. Both second end portions of the second channel portion and a second midpoint between both the second end portions are determined in the virtual cross section. In this case, an angle between a second direction and a center line connecting the first midpoint and the second midpoint is an acute angle.

A semiconductor storage device has been proposed which includes: a laminate including insulating films and word lines which are alternately laminated; and semiconductor pillars which penetrate through the laminate. A semiconductor storage device has been known which has an opposed cell structure in which floating gate electrodes are disposed at both sides of the semiconductor pillar with a tunnel insulating film interposed therebetween. In the semiconductor storage device having the opposed cell structure, a structure has been known in which channels of the opposed cells are connected to each other. In this kind of semiconductor storage device, there is a problem in that, as miniaturization of the cell size advances, capacitance between the opposed cells increases, interference between the opposed cells significantly occurs.


A ultrasonic vibration cutting tool which can optimize materials as in a separate type and can improve the transmission efficiency of ultrasonic vibration as in an integrated type. The ultrasonic vibration cutting tool comprises a ring-shaped projection and a blade essentially composed of diamond and held by the ring-shaped projection both of which are formed on the peripheral surface of a vibration conversion portion provided on a resonator, and the outer diameter of the blade is set larger than the outer diameter of the ring-shaped projection.

1. Field of the Invention
The present invention relates to an ultrasonic vibration cutting tool and to a production method thereof.
2. Description of the Prior Art
A cutting tool making use of ultrasonic vibration is described at page 218 of xe2x80x9cUltrasonicsxe2x80x9d published by Corona Co., Ltd. in Jun. 30, 1999.
Ultrasonic vibration cutting tools are divided into two types: an integrated type in which a blade projecting outward from the peripheral surface of a resonator is integrated with the resonator and a separate type in which a disk-like blade is attached to a resonator. Since the blade and the resonator are made from the same material in the case of the integrated type, when the blade is formed from a material best suited for a member to be cut, the material of the resonator may not have excellent acoustic characteristics, or when the resonator is formed from a material having excellent acoustic. characteristics, the material of the blade has poor compatibility with the member to be cut. Therefore, the material of the blade is limited inevitably. In the case of the separate type, the blade and the resonator can be formed from different materials. For example, the blade is formed from a material best suited for a member to be cut and the resonator is formed from a material having excellent acoustic characteristics. However, since the blade is attached to the resonator, the transmission efficiency of ultrasonic vibration from the resonator to the blade becomes worse inevitably compared with the integrated type.
Then, the present invention provides an ultrasonic vibration rotary cutting tool which can optimize materials as in a separate type and, can improve the transmission efficiency of ultrasonic vibration as in an integrated type, as well as a production method thereof.
According to an aspect of the present invention, there is provided an ultrasonic vibration cutting tool comprising a ring-shaped projection and a blade essentially composed of diamond and held by the ring-shaped projection, all of which are formed on the peripheral surface of a vibration. conversion portion provided on a resonator, wherein the outer diameter of the blade is made larger than the outer diameter of the ring-shaped projection. According to this invention, the blade is formed from a material best suited for a member to be cut regardless of the resonator and integrated with the resonator. Therefore, the optimization of materials as in the separate type and the improvement of the transmission efficiency of ultrasonic vibration as in the separate type can be made possible.
According to another aspect of the present invention, there is provided a method of producing an ultrasonic vibration cutting tool, the method comprising the steps of immersing a resonator having a vibration conversion portion and a ring-shaped projection in a plating solution obtaining diamond powders and growing a blade essentially composed of diamond with the ring-shaped projection as a seed by electroplating. According to this invention, an ultrasonic vibration cutting tool which can optimize materials as in the separate type and can improve the transmission efficiency of ultrasonic vibration as in the integrated type can be easily produced.
In the above invention, if the peripheral portion of the ring-shaped projection is removed after the growth of the blade so that the ring-shaped projection is located inside the peripheral portion of the blade, the outer diameter of the blade can be set properly.
The above and other objects, advantages and features of the present invention will become more apparent from the following description when taken into conjunction with the accompanying drawings.

Ultrasonic vibration cutting tool and production method thereof


A method, a device, and a non-transitory storage medium are described in which a network performance optimization service is provided. A load balancer device may receive, from an end device, an application service request for an application service that is available from multiple server devices of an application layer network. The load balancer device may determine, from a source identifier associated with the end device and obtained from the application service request, that the source identifier does not map to a network traffic forwarding rule of a set of stored network traffic forwarding rules. In response, the load balancer device may map the source identifier to an application service profile of a set of stored application service profiles; select, based on the application service profile, a first server device of the multiple server devices and establish the first server device to be the destination of the application service request.

Development and design of communication networks present certain challenges from a network-side perspective and an end device perspective. Multi-access edge computing (MEC), also known as mobile edge computing, is being developed in which some network capabilities— conventionally implemented in a core network or a cloud network (e.g., computation, storage, transport, etc.)—are alternatively situated at the network "edge" relative to a point of attachment of an end device to a radio access network (RAN). In MEC environments, Internet service providers (ISPs) may have a pool of servers, such as physical servers, virtual hosts, and/or service containers, which are capable of providing similar functionality.

Method and system for network performance optimization service


A carrier phase synchronous type maximum likelihood decoder for estimating a maximum likelihood sequence of data sequence includes N memories for memorizing N partial series of data sequence; N carrier phase adjust loop, each provided correspondingly to N memories, each for adjusting a carrier phase of received data series on the basis of a partial series memorized in corresponding memory; N likelihood function calculate parts, each provided correspondingly to N memories and N carrier phase adjust parts, each for calculating likelihoods of partial series by utilizing partial series memorized in corresponding memory and an output of corresponding carrier phase adjust loop, a compare and modulation part for comparing N calculated likelihoods and for selecting partial series having a maximum likelihood from memory, thereby, the satisfactory operation in the low S/N ratio can be realized and the satisfactory phase tracking characteristics can be obtained.

1. Field of the Invention
The present invention relates to a detection and determination of data within a range having a low signal-to-noise ratio (referred to as a S/N ratio hereinafter) in a communication or a recording device etc., and more particularly, relates to a carrier phase synchronous type maximum likelihood decoder for transmitting and receiving digital signals.
2. Description of the Related Art
In recent years, it has been noticed the receiving system in which modulation signals, in a broad sense, involving the phase modulation of convolutionally encoded data, an orthogonal amplitude modulation, an encoded modulation, CPFSK and a modulation having an interference between the symbols, are detected with Maximum Likelihood Sequence Estimation Scheme, because it provides the satisfactory S/N ratio against error rate characteristics.
The maximum likelihood sequence estimation system as mentioned above, is structured to estimate a transmit data sequence with a minimum error on the basis of reference signals which are hypothetical ideally detected signals.
Since the maximum likelihood estimation system has the advantage that the remarkable low error rate can be expected in the low S/N ratio range which the other system cannot achieve, it has been considered widely in various fields.
The demodulation means is required to have a low error rate in such low S/N ratio. To carry out a maximum likelihood decode, coherent detection means which has good error rate characteristics is utilized.
FIG. 13 is a block diagram showing the structure of the phase synchronous circuit used in such a synchronous detection system. As shown in the drawing, the phase synchronous circuit includes an orthogonal demodulate circuit 1, a temporary detect circuit 3, a phase error detect circuit 5, a regenerated carrier wave generate circuit 7 and a maximum likelihood sequence estimate circuit 9.
The orthogonal demodulate circuit 1 demodulates orthogonally the received signals. The temporary detect circuit 3 detects the transmitted data with immediate detection scheme. The phase error detect circuit 5 detects the phase error between the output of the orthogonal demodulation circuit 1 and the output of the temporary determine circuit 3.
The regenerated carrier wave generate circuit 7 generates the regenerated carrier wave controlled by the output of the phase error detect circuit 5. The maximum likelihood sequence estimate circuit 9 estimates the transmit signal with maximum likelihood on the basis of the output signal of the orthogonal demodulation circuit 1.
In the phase synchronous circuit as mentioned above, the phase error between the regenerated carrier wave and the carrier wave of receive signal is calculated and the phase of the regenerated carrier wave is controlled based on the phase error. This loop does not contain a long delay, and shows good tracking performance in high SN ratio condition.
However, in such a phase synchronous loop, when "the output of temporary detect circuit" is not correct, the incorrect phase error is calculated and the phase of regenerated carrier wave is controlled on the basis of the incorrect phase error, therefore, the synchronization cannot be achieved well, especially in low SN ratio condition. The phase error calculated on the basis of the correct transmit data is the error where a Gaussian random noise is added to the real phase error. Therefore, the noise component can be removed by means of a linear filter, if the phase movement of the carrier wave is within a certain range. On the contrary, since the phase error calculated on the basis of the incorrect transmitted data has not only the Gaussian random noise added to the real phase error, but also the incorrect error based on the erroneous detection, which acts as a nonlinear noise, it is difficult to hold the synchronization when the error exceeds a certain range. Further, it is very difficult to synchronize when the phase of transmit carrier wave changes fastly, for example by fading.
Since the phase error is calculated on the basis of the temporary detected data involving larger amount of errors than the maximum likelihood sequence, the sufficient operation cannot be carried out in a low S/N ratio. As a result, it is not possible to obtain good error rate performance in a low S/N ratio.
FIG. 14 is a block diagram showing the structure of another phase synchronous circuit. This phase synchronous circuit includes an orthogonal demodulate circuit 1, a maximum likelihood sequence estimate circuit 11, a delay circuit 13, a phase error detect circuit 5 and a regenerated carrier wave generate circuit 7.
The delay circuit 13 delays an output signal of the orthogonal demodulate circuit 1. The maximum likelihood sequence estimate circuit 11 estimates the maximum likelihood sequence of the transmit signal on the basis of the output signal from the orthogonal circuit 1. The phase error detect circuit 5 detects the phase errors between the outputs of the delay circuit 13 and the Maximum likelihood sequence estimate circuit 11. The regenerated carrier wave generate circuit 7 generates the regenerated carrier wave on the basis of the output from the phase error detect circuit 5.
In the phase synchronous circuit as mentioned above, the phase error is calculated by the phase error detect circuit 5 on the basis of the output of the maximum likelihood sequence estimate circuit 11. The most reliable phase errors can be calculated by the system described above.
However, for determining the maximum likelihood of the transmit data, it takes a quite long time.
Further, the time for decoding is taken longer in some case. For example, in decoding such punctured convolution data of the 7/8 encode rate, it takes in general the time nearly ten times as much as the constrained length. The circuit for adjusting the regenerated carrier wave by utilizing the phase error calculated on the basis of the transmit data determined in a long period of time has the remarkably large delay time in the control loop, therefore, it is impossible to attain a good characteristics in the phase tracking. Namely, the circuit has disadvantages that a frequency tracking range becomes remarkably narrow, a loop becomes easily unstable and a time required for the synchronization is taken remarkably long.
In the phase synchronization circuit, the delay in the loop becomes longer, the sufficient phase tracking characteristics cannot be obtained. Therefore, the synchronization failure in the loop is caused if phase of the carrier wave varies even slightly. As a result, it is not possible to obtain good error rate performance.
As described above, it is hard to carry out the maximum likelihood sequence estimation and achieve the phase synchronization of signals having the large Inter-Symbol-Interference simultaneously. Moreover, the phase synchronization in the low S/N ratio is remarkably hard to obtain. Further, when the maximum likelihood sequence estimation system is used in the satellite mobile communication and the land mobile communication, it is hard to obtain the carrier phase synchronization, because the carrier phase is remarkably fluctuated by the complicated transmission path characteristics, such as a multipath fading and a shadowing. Further, the ratio of whole signals occupied by the preamble or the pilot is remarkably high, therefore, it is difficult to utilize the frequency band efficiently.

Carrier phase synchronous type maximum likelihood decoder


The present invention provides a method of treating edematous retinal disorders. The method comprises administration of a pharmaceutical formulation comprising a hydrolysis-resistant P2Y receptor agonist to stimulate the removal of pathological extraneous fluid from the subretinal and retinal spaces and thereby reduce the accumulation of said fluid associated with retinal detachment and retinal edema. The P2Y receptor agonist can be administered with therapeutic and adjuvant agents commonly used to treat edematous retinal disorders. The pharmaceutical formulation useful in this invention comprises a P2Y receptor agonist with enhanced resistance to extracellular hydrolysis, such as dinucleoside polyphosphate compounds, or hydrolysis-resistant mononucleoside triphosphate salts. The present invention also provides P1-(2′-deoxycytidine 5′-)P4-(uridine 5′-)tetraphosphate, tetra-(alkali metal) salts such as tetrasodium, tetralithium, tetrapotassium, and mixed (tetra-alkali metal) salts. The present further provides a pharmaceutical formulation comprising a P1-(2′-deoxycytidine 5′-)P4-(uridine 5′-)tetraphosphate, tetra-(alkali metal) salt, in a pharmaceutically acceptable carrier.

The retinal pigment epithelium (RPE) lies in the back of the vertebrate eye and forms a barrier that separates the retina from the choroidal blood supply. A critical function of the RPE is to maintain and regulate the hydration of the subretinal space, the extracellular volume that exists between the retina and the RPE. (Marmor, pp. 3–12, in The Retinal, Pigment Epithelium, Eds. M. F. Marmor and T. J. Wolfensberger, Oxford University Press, New York, (1998)). This function is achieved by the regulated transport of fluid, ions, and metabolites between the subretinal space and the choroidal blood supply. (Marmor, pp. 420–438, in The Retinal Pigment Epithelium, Eds. M. F. Marmor and T. J. Wolfensberger, Oxford University Press, New York, (1998); Pederson, pp. 1955–1968, in Retina, Ed. S. J. Ryan, Mosby, St. Louis, (1994)). Like all epithelia, the RPE contains two functionally and anatomically distinct membranes: an apical membrane that faces the retina, and a basolateral membrane that faces the choroidal blood supply. In the normal retina, fluid is absorbed across the RPE in the direction of the subretinal space to the choroid. This active absorption of fluid by the RPE, often referred to as the "RPE pump," plays a critical role in maintaining proper attachment of photoreceptors to the apical membrane of the RPE by pumping fluid out of the retinal spaces. (Marmor, pp. 1931–1954, in Retina, Ed. S. J. Ryan, Mosby, St. Louis, (1994); Hughes, et al., pp. xvii, 745, in The Retinal Pigment Epithelium, Eds. M. F. Marmor and T. J. Wolfensberger, Oxford University Press, New York, (1998)).
Retinal detachment is characterized by abnormal accumulation of fluid in the subretinal space leading to detachment of the retina from the underlying retinal pigment epithelium. Retinal edema refers to abnormal accumulation of fluid within the retina itself. Retinal detachment or edema in the central part of the retina (macula) produces significant loss of vision, and can ultimately lead to irreversible blindness. (Yanoff and Duker, Ophthalmology, Mosby, Philadelphia, (1999); Wilkinson, et al., Michels' Retinal Detachment, 2nd ed. Mosby, St. Louis, (1997)) A wide variety of ocular pathologies can result in retinal detachment or retinal edema. The most common type of retinal detachment is rhegmatogenous retinal detachment, which occurs as a result of single or multiple tears or holes in the retina that permit liquefied vitreous to enter into the subretinal space and create a retinal detachment.
There are no pharmacological approaches employed in the treatment of rhegmatogenous retinal detachment (RRD). The only current treatments for RRD are surgical (scleral buckling, pneumatic retinopexy, or vitrectomy). (Wilkinson, Michels' Retinal Detachment, 2nd ed., Mosby, St. Louis, (1997)). There are two vital components for successful RRD surgery: reattachment of the retina and repair of the retinal break. The principal difference among the three surgical techniques for treating RRD is in the method employed to facilitate retinal reattachment.
Scleral buckle uses an extraocular buckle (usually a silicone sponge or solid silicone) that is sewn to the sclera towards the detached retina (Wilkinson, et al, Michels' Retinal Detachment, 2nd ed., Mosby, St. Louis (1997)). The retina usually reattaches over a period of a few days, but may take up to a few weeks. The surgeon may elect to drain the subretinal fluid at the time of operation by inserting a needle through the sclera, choroid, and RPE. In general, the buckle remains permanently sewn to the sclera. In pneumatic retinopexy, a gas bubble is injected directly into the vitreous, and the head is positioned so that the gas bubble acts as a tamponade and covers the retinal break. (Tomambe and Hilton, Ophthalmology 96(6):772–83 (1989)). The subretinal fluid usually resolves within 1–2 days, but precise head positioning is required to insure that the bubble covers the retinal break. (Tomambe, 10 et al., Am. J. Ophthalmol. 127(6):741–3 (1999)). Vitrectomy is usually used for complex RRD associated with vitreous traction or hemorrhage, but is occasionally used for simple RRD (Chang, pp. 8.34.1–8.34.6, in Ophthalmology, Eds. M. Yanoff and J. S. Duker, Mosby, Philadelphia, (1999)). The procedure involves making three small incisions through the sclera to allow the introduction of instruments in the vitreous cavity. The vitreous is removed and replaced with a special saline solution. Depending on the type and cause of the detachment, a variety of instruments and techniques are then used to reattach the retina. For simple detachments, the retina is flattened via anterior drainage of the subretinal space by insertion of a needle through the retinal tear.
Scleral buckle and vitrectomy often require general anesthesia and can involve hospitalization. Pneumatic retinopexy is usually done in the physician's office, but requires patient compliance for success. (Hilton and Tornambe, Retina 11(3):285–94 (1991); Hilton and Brinton, pp. 2093–2112, in Retina, Ed. Stephen J. Ryan, Mosby, Philadelphia, (1999); Han, et al., Am. J. Ophthalmol. 126(5):658–68 (1998)). Depending on the surgical technique and the surgeon, success rates can vary following a single surgery, with lower rates for pneumatic retinopexy and higher rates for scleral buckle. (Tornambe, et al., Am. J. Ophthalmol. 127(6):741–3 (1999); Han, et al., Am. J Ophthalmol. 126(5):658–68 ($$ 1998)). The success of retinal detachment surgery is measured in terms of retinal reattachment at any point following surgery (ranging from hours to weeks). Parameters such as visual outcome and patient quality-of-life are not used to assess success of retinal detachment surgery.
The conditions that are commonly associated with the more severe forms of intra-retinal edema are diabetic macular edema, exudative age-related macular degeneration (AMD) and clinically significant cystoid macular edema. (Jampol and Po, pp. 999–1008, in Retina, Ed. S. J. Ryan, Mosby, St. Louis, (1994)). Other pathological conditions associated with abnormal fluid accumulation in intra-retinal or subretinal spaces include uveitis, central and branch vein occlusion, retinitis pigmentosa, central serous retinopathy, CMV retinitis, and choroidal melanoma. Physical trauma associated with ocular injury following certain surgical procedures (such as cataract surgery) can also produce retinal detachment or edema. (Ahmed and Ai, pp. 8.34.1–8.34.6, in Ophthalmology, Eds. M. Yanoff and J. Duker, Mosby, Philadelphia, (1999)).
Intra-retina accumulation of fluid in the macula results in decreased visual acuity and is the most common cause of vision loss in patients with diabetic retinopathy, AMD and other ischemic retinopathies such as branch and central retinal vein occlusion. (Jampol and Po, pp. 999–1008, in Retina, Ed. Stephen J. Ryan, Mosby, St. Louis, (1994); Kent, et al., Br. J. Ophthalmol. 84(5):542–5 (2000)). Macular edema is a frequent complication of uveitis and is commonly seen in patients with retinitis pigmentosa. (Rothova, et al., Br. J. Ophthalmol. 80(4):332–6 (1996); Fetkenhour, et al., Trans. Am. Acad. Ophthalmol. Otolaryngol. 83(3)Pt 1: OP515–21 (1977)). Macular edema is also a major cause of decreased vision following intraocular surgery (called cystoid macular edema). (Miyake, Surv. Ophthalmol. 28 Suppl:554–68 (1984)). Accumulation of intra-retina fluid is believed to result from a breakdown of the inner and/or outer blood-retinal barrier. (Kent, et al., Br. J. Ophthalmol. 84(5): 542–5 (2000)). The inner retinal barrier consists of endothelial cells of the retinal vasculature and the outer barrier comprises the retinal pigment epithelium. Breakdown of the blood-retinal barrier can result in focal leakage of fluid from the vasculature and fluid accumulation within retinal layers or in the subretinal space. The present treatments for retinal edema include systemic and topical administrations of corticosteroid, acetazolamide, and non-steroidal anti-inflammatory drugs, as well as surgical options such as vitrectomy, grid, and focal laser photocoagulation. These therapies show limited utility in patients.
Although modern day RRD surgery has a relatively high success rate (60–90%), it is thought that a pharmaceutical composition that can reattach the retina in cases where surgery failed would be of enormous patient benefit. In addition, if the pharmaceutical composition can reattach the retina in the absence of surgical intervention, it would be most therapeutically useful, particularly in the treatment of rhegmatogenous retinal detachment.
A number of pharmacological and surgical approaches are employed to treat cystoid and diabetic macular edema, but they are generally considered empirical and often ineffective. Non-specific anti-inflammatory treatment is used for all types of macular edema, except in cases associated with ischemic retinopathies in which laser treatment is indicated (Kent, et al., Br. J. Ophthalmol. 84 (5):542–5 (2000)). Corticosteroids are frequently used to treat macular edema, but were shown to be ineffective in a randomized, placebo controlled study (Flach, et al., Am. J. Ophthalmol. 103(4):479–86 (1987); Flach, et al., Ophthalmology 97(10):1253–8 (1990)). Acetazolamide also alleviates certain types of macular edema and is postulated to work via activation of the RPE pump, but systemic tolerance to acetazolamide is poor. (Cox, et al., Arch. OphthaZmoZ. 106(g): 1190–5 (1988)). Focal or grid laser photocoagulation is commonly used to reduce retinal vascular leakage associated with diabetic retinopathy, and is useful in limited cases. (Ip, et al., In Ophthalmology, London; Philadelphia: Mosby, 8.4.1–8.4.2 (1999); The Diabetic Retinopathy Study Research Group, Ophthalmology 88 (7):583–600 (1981); Early Treatment Diabetic Retinopathy Study Research Group, Arch. Ophthalmol. 103(12):1796–806 (1985); The Branch Vein Occlusion Study Group, Am. J. Ophthalmol. 98(3):271–82 (1984)). In addition, vitrectomy is employed to treat diabetic retinopathies associated with vitreal hemorrhages and/or vitreoretinal traction. (Wilkinson, et al, Michels' Retinal Detachment, 2nd ed., Mosby, St. Louis, (1997)). There remains a large unmet medical need for a safe, effective treatment of macular edema. (Kent, et al., Br. J. Ophthalmol. 84(5):542–5 (2000)).
Peterson, et al. (J. Neurosci. 17:2324–37 (1997)) suggest that UTP (or perhaps ATP) could be used therapeutically to reduce the pathological accumulation of fluid in the subretinal space. However, both ATP and UTP are rapidly degradeable by ubiquitous extracellular nucleotidases. Therefore, in order for ATP and UTP to be efficacious in the treatment of retinal detachment, these compounds need to be delivered directly into the subretinal space. Drug delivery into the subretinal space is widely regarded to be unacceptably risky for patients because it involves the insertion of a needle between the retina and RPE, which can result in complications and blindness. In order for ATP or UTP to be therapeutically useful, it must be delivered into the intravitreal cavity, which is a much less invasive procedure. However, in order for ATP or UTP to reach the RPE apical membrane, it must diffuse across the retina. It is unknown if intravitreal ATP or UTP is degraded by the time it reaches the RPE apical membrane and therefore effective in stimulating retinal reattachment. The present examples show that intravitreal UTP is ineffective in stimulating retinal reattachment and that the present method is effective in stimulating retinal reattachment.

This patent is subject to a terminal disclaimer.

Pharmaceutical formulation comprising dinucleoside polyphosphates and salts thereof


A process and an apparatus that can be used for surface preparation and treatment of a metal workpiece surface, for example in a processing stage prior to adhesive assembly, without using environmentally harmful materials. The process comprises triggering and maintaining pulsed unipolar arc discharges between an electrode wired as an anode and a workpiece surface wired as a cathode, with the arc discharges following one another with a timing, number, and speed such that they do not cause macroscopic melting of the workpiece surface while ensuring complete extinction of the individual arc discharges. The apparatus comprises an electrode as the anode and the workpiece as the cathode, and a generator or component for generating electrical pulses.

This application claims the priority of German patent document DE 196 37 513.4, the disclosure of which is expressly incorporated by reference herein.
The invention relates to the field of mechanical engineering and metallurgy, and concerns a process and an apparatus for treatment of metal workpiece surfaces by electrical discharges, like those that can be used advantageously for subsequent adhesive assembly for example, by gluing or welding for example, or for combined assembly processes, for example gluing, resistance welding, or adhesive and shaping connections.
A number of problems arise in conjunction with gluing metal surfaces in industrial manufacturing. The most important condition for firm adhesion consists in the molecules of the adhesive being able to penetrate the surface of the substrate to a degree that allows the adhesion forces to become effective. Therefore, metal surfaces must be free of impurities (grease, oil, dust, and dirt). This is followed by mechanical pretreatment (brushing, blasting) and frequently by chemical pretreatment as well.
Because of the high, long-term stability that can be achieved in this fashion, classical chromium-sulfuric acid anodization for aluminum alloys has been employed largely unchanged for decades. This is especially the case in the aircraft industry. In order to make adhesive connections more stable with respect to environmental factors and especially to prevent breaks in adhesion caused by water diffusing inward, primer systems have been developed as adhesion promoters that are applied in very thin layers in order not to affect the overall behavior of the connection adversely. Epoxy resins have been the dominant adhesives for joining aluminum parts since the 1950s, said resins curing at temperatures of about 120.degree. C. and with relatively low applied pressures (approximately 1 bar). Special adhesives have been developed for gluing steel panels in the automobile industry, said adhesives being suitable for automatic manufacturing, medically safe, and resistant to oil to a limited degree.
Despite the very high level of technological development of industrial adhesives overall, there are still several important shortcomings. Thus, pretreatment usually involves several costly worksteps and, to some extent, the use of chemicals that are medically objectionable or are problematic from the environmental standpoint. In addition, many technical solutions that have proven successful in manufacturing cannot be transferred to repair.
As an alternative to purely chemical processes, chemical and physical surface treatment processes are also employed that are much more advantageous as far as their environmental compatibility is concerned. In this connection, we can mention in particular the process of blast coating known by the name of SACO (O. Hahn, B. Motzko, "Influence of the Process Parameters of SACO Surface Treatment on the Properties of Glued Stainless-Steel Connections," convention proceedings, Swissbonding 1994). In the SACO process, a corundum grain is used as the blasting medium, said grain being enclosed in a layer of silicate. When this abrasive strikes the surface of the substrate to be treated, a portion of the kinetic energy is converted into heat, and the silicate coating of the corundum grain suddenly breaks free of the grain and becomes firmly anchored in the substrate being blasted. The advantage of this process is that adhesion to the adhesive is largely independent of the material of which the parts being assembled are composed, since the adhesion is produced by the intermediate silicate layer. Thus, even materials that are conventionally difficult to glue together can be joined firmly to each other.
The problem that arises in this process is the development of dust that is necessarily associated with a blasting process, and which necessitates special work protection measures (particle sizes 1 to 10 .mu.m). This pretreatment therefore requires special shielding that makes it more difficult to use for repairs and makes it impossible to integrate into automated production processes.
Processes for treatment of surfaces of metal workpieces by means of electrical discharges under atmospheric pressure are described in a number of places in the literature and have been proposed for various applications.
While the processes at the cathode of a vacuum arc discharge have been studied for a long time (L. P. Harris, "Arc Cathode Phenomena," in: J. M. Lafferty (Editor), "Vacuum Arcs, Theory and Application," Wiley, NY, 1980) and DC arcs in air have been used for a variety of applications (welding technology, switches), the processes that take place during brief arc discharges in a gas atmosphere at the cathode application point have thus far been investigated to only a limited extent. Such short-term discharges are characterized by the fact that no macroscopic arc application point constituting a liquid melt can form on the cathode, and the development of cathode erosion is characterized by the same microscopic craters as with a vacuum arc. Various characteristic erosion patterns develop as a function of the state of the surface (A. E. Guile and B. Juttner, "Basic Erosion Processes of Oxidized and Clean Metal Cathodes by Electric Arcs," IEEE Trans. Plasma Sci. Vol. PS-8 (1980), pp. 259-269). Depending on the type of gas and the duration of the discharge, net erosion decreases inversely with gas pressure (J. -L. Meunier and M. G. Drouet, "Experimental Study of the Effect of Gas Pressure on Arc Cathode Erosion and Redeposition in He, Ar, and SF from Vacuum to Atmospheric Pressure," IEEE Trans. Plasma Sci. Vol. PS-15, (1987), pp. 515-519). It has also been observed that an amorphous layer whose corrosion resistance is definitely higher than that of the basic material forms under the influence of brief arc discharges (Larikov, L. N. et al., "The Formation of an Amorphous Layer on Fe.sub.86 B.sub.14 Alloy Under the Effect of a Spark Discharge, " Metals Abstracts, Vol. 16, April 1983, p. 183, No. 56-0373; Metallofizika, 6 (1982) 4, 92-93). Technical applications, especially for adhesion technology, have thus far not been derived from these physical studies.
U.S. Pat. No. 4,931,613 describes a process for improving the strength characteristics of steels containing silicon with the aid of electrical discharges. The processing electrode is kept constantly in contact with the workpiece in order to trigger a plurality of discharges by means of a pulsed current source. When the discharge is produced in this fashion, it is important to remember that the processing electrode likewise is severely eroded, and material is transferred from said electrode to the workpiece.
German patent document DE 36 18 412 A1 describes a process for treating objects using electrical high voltage discharges, with the goal being to use the electrical field of the discharge to accelerate gas components against the surface of the object. This process therefore involves chemical treatment of the surface of the workpiece using an electrically activated gas (ozone, radicals, ions), with cratering being considered a disturbing effect. Another problem that arises in this connection is that such treatment creates large quantities of byproducts that are hazardous to health (especially NO.sub.x and O.sub.3).
German patent document DE 42 25 106 A1 describes a process for producing a metal-plastic bond, especially for dental prostheses, with an adhesion-promoting oxide layer being formed on a metal part, said layer then being bonded with a dental plastic using an intermediate layer consisting of an adhesive silane. An electrical potential is maintained between the metal part and an adjacent electrode, and spark discharges are triggered as a silico-organic compound is introduced into the space between the electrode and the part. In this process as well, the emphasis is on electrochemical coating, while any roughnesses that may form are considered undesirable.
These adhesion-promoting layers based on silicon oxide, according to German patent document DE 34 03 894 C1, can also be produced at high temperature on selected areas of a metal dental prosthesis by reacting an oxidizable silicon compound in the gaseous state with a flame pyrolysis burner. The flame cone of the burner is guided over the part of the dental prosthesis to be coated.
In German patent document DE 40 12 086 A1, a process with the same basis is described that is intended to produce an adhesion-promoting layer for cathodic electrophoretic dip painting. In this case, zinc, aluminum, and their alloys are used as substrate materials in addition to iron. The fact that an adhesion-promoting layer made of silane is also applied gives the process its name, i.e. the "silicoater" process.
Adhesion promoters of a completely different kind for aluminum adhesives, and therefore for aluminum materials as well, are described in German patent document DE 43 03 077 A1. The invention claimed therein relates to adhesion promoters that form a chelate complex with aluminum ions and that have a group that reacts with an epoxy resin adhesive.
The disadvantage of all processes using adhesion promoters is that they are complex multistage processes (cleaning, oxide formation, application of silane), in which, at each stage, environmentally harmful and poisonous or health-hazardous materials are used or released as byproducts.
A goal of the invention is to provide a process and an apparatus for modification of metal workpiece surfaces by electrical discharges, by which multistage processes for surface modification can be avoided and modification takes place without using environmentally harmful, poisonous, and/or health-hazardous materials.
This and other goals have been achieved according to the present invention by providing a process for treatment of a metal workpiece surface, comprising: wiring a workpiece as a cathode; triggering and maintaining pulsed unipolar arc discharges between an electrode wired as an anode and a surface of the workpiece; controlling a duration of the arc discharges in order to avoid macroscopic melting of the surface of the workpiece; and controlling a repetition rate of the arc discharges in order to avoid macroscopic melting of the surface of the workpiece, and in order to guarantee complete extinction of each individual arc discharge.
This and other goals have also been achieved according to the present invention by providing a process for treatment and adhesive assembly of a metal workpiece surface, comprising: wiring a workpiece as a cathode; arranging an electrode at a distance from a surface of said workpiece which is to be subsequently adhesively connected to another surface, said electrode being wired as an anode; triggering and maintaining pulsed unipolar arc discharges between said electrode and said surface of the workpiece; controlling a duration of the arc discharges in order to avoid macroscopic melting of the surface of the workpiece; controlling a repetition rate of the arc discharges in order to avoid macroscopic melting of the surface of the workpiece, and in order to guarantee complete extinction of each individual arc discharge; moving at least one of said electrode and said workpiece in order to treat an entirety of said surface; and adhesively connecting said surface to said another surface.
This and other goals have also been achieved according to the present invention by providing an apparatus for treatment of metal workpiece surfaces as a pretreatment for subsequent adhesive or combined assembly, comprising: a workpiece wired as a cathode; an electrode wired as an anode; a generator comprising a high-voltage pulse source and one of a pulsed-current source and a component that consists of a laser and a pulsed-current source; and a controller controlling said generator to generate electrical pulses for triggering and maintaining pulsed unipolar arc discharges between the electrode and the surface of the workpiece.
This and other goals have also been achieved according to the present invention by providing an apparatus for treatment of metal workpiece surfaces as a pretreatment for adhesive connection, comprising: a workpiece wired as a cathode; an electrode wired as an anode and arranged at a distance from a surface of said workpiece which is to be subsequently adhesively connected to another surface; a generator comprising a high-voltage pulse source and one of a pulsed-current source and a component that consists of a laser and a pulsed-current source; and a controller controlling said generator to generate electrical pulses for triggering and maintaining pulsed unipolar arc discharges between the electrode and the surface of the workpiece, said controller: (a) triggering and maintaining pulsed unipolar arc discharges between said electrode and said surface of the workpiece, (b) controlling a duration of the arc discharges in order to avoid macroscopic melting of the surface of the workpiece, and (c) controlling a repetition rate of the arc discharges in order to avoid macroscopic melting of the surface of the workpiece, and in order to guarantee complete extinction of each individual arc discharge.
According to the invention, in a process for modification of metal workpiece surfaces, by electrical discharges as pretreatment for subsequent adhesive assembly and/or combined assembly techniques, pulsed unipolar arc discharges are triggered and maintained between an electrode wired as an anode and the workpiece surface, with the workpiece being wired as a cathode, with the duration of an arc discharge being controlled in each case in order to avoid macroscopic melting of the surface of the workpiece and with the arc discharges following one another in a number and at a speed such that they do not lead to macroscopic melting of the workpiece surface and guarantee complete extinction of the individual arc discharges.
Advantageously, the arc discharges are triggered and maintained between the electrode and a part of the workpiece surface that is required for subsequent adhesive assembly and/or combined assembly techniques.
It is also advantageous that the work takes place at atmospheric pressure using active or inert gases or gas mixtures.
The present invention further provides an apparatus for modification of metal workpiece surfaces by electrical discharges as pretreatment for subsequent adhesive assembly and/or combined assembly techniques, said apparatus consisting of an electrode as the anode and a workpiece as the cathode, and a generator is also provided that consists of a high-voltage pulse source and a pulsed current source or a part that consists of a laser and a pulsed current source, to generate electrical pulses for triggering and maintaining pulsed unipolar arc discharges between the electrode and the surface of the workpiece.
It is advantageous for the high-voltage pulse source in the generator to be connected with the electrode through one diode and for the pulse current source to be connected with the electrode through another diode.
According to one advantageous embodiment, a pulsed laser and a pulsed current source are utilized, with the laser being focused on the surface of the workpiece opposite the electrode.
According to another advantageous embodiment, the radius of curvature of the electrode wired as the anode is much smaller than that of the surface of the workpiece opposite thereto.
According to another advantageous embodiment of the present invention, a gas pressure above 100 Pa is maintained in the processing chamber.
Special advantages are obtained when atmospheric pressure prevails in the processing chamber.
The present invention is also advantageously designed such that the processing chamber is flushed by a gas.
Advantages are also obtained if, in the apparatus according to the invention, the flushing gas enters the processing chamber through an opening in the electrode that is wired as the anode.
According to the present invention, in order to modify a metal workpiece surface, only pulsed unipolar (in other words, not oscillating) discharges are used, with the electrode being connected with the positive pole of a pulsed voltage source. The term "unipolar discharge" means that the current flows essentially in one direction during the entire discharge process, in other words, there is no reversal of the flow direction, and that any current flowing in the opposite direction is very small by comparison to the current in the main direction.
It has been found that with a circuit of this kind using short pulsed light arc discharges (with a duration on the order of 5 to 100 .mu.s) it is mainly the surface of the workpiece and not the electrode (or only to a very slight degree) that is eroded. Furthermore, the brief pulses have the effect that the heat applied to the workpiece remains low. The discharges produce a local roughening of the surface of the workpiece. This roughening increases the effective surface and thus can improve the adhesion of adhesives, for example. It has been observed that this effect is pronounced in an advantageous manner when processing takes place under the influence of a gas, with a passive gas (for example a noble gas or nitrogen) or a gas that activates the surface (oxygen for example) or a mixture of gases (a mixture containing a halogen) being employed depending on the adhesive used and the materials to be joined. When the arc discharges are triggered by high-voltage breakdown, the discharge preferably begins at dielectric inclusions that can therefore be preferably eliminated. Since it is precisely these foreign substances that adhere poorly to the surface that cause problems during gluing, the desired effect is reinforced even further.
The apparatus and the process according to the present invention for modification of a metal workpiece surface using pulsed unipolar arc discharges produces a fine uniform roughening that constitutes a modification of the crystal structure in the surface area of the workpiece. As a result, in one process step and without using environmentally harmful, poisonous, and/or health-hazardous materials, a clean and oxide-free surface is produced on the metal workpieces being treated, said effect being especially advantageous for subsequent adhesive assembly and/or combined assembly techniques.
According to the process and apparatus of the present invention, the strength of adhesive assembled connections, especially glued connections, is improved. The long-term strength of such assembled connections is especially improved.
Additional advantages of the process according to the invention and the apparatus according to the invention include the following:
modification takes place in one workstep, with the processing time being adapted to the degree of contamination; PA1 modification can be performed both completely automatically, for example by means of manipulators, and also visually, using a manual apparatus; PA1 modification can be performed at atmospheric pressure (no vacuum process being necessary); PA1 because the energy applied is very low and is limited to a surface layer a few microns thick, the modified workpiece can, for the most part, remain cool; PA1 modified and unmodified or insufficiently modified areas of the individual surfaces of the workpiece can be clearly distinguished by the unaided eye; PA1 modification can take place locally on areas of the workpiece that are relevant to subsequent assembly processes without affecting surrounding areas.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

Process for treatment of metal workpiece surface by electrical discharges


An outdoor unit for an air-conditioning apparatus includes: a compressor; an outdoor fan; a plurality of outdoor heat exchangers coupled to a plurality of indoor units; a switching member configured to switch functions of the outdoor heat exchangers to either condensers or evaporators by switching of coupling states between the compressor and the outdoor heat exchangers; and a control unit configured to calculate a low pressure saturation temperature during a cooling operation or a cooling-main operation, and configured to cause all of the plurality of outdoor heat exchangers to serve as condensers by controlling the switching member when a state in which an open-air temperature is lower than the low pressure saturation temperature continues for a predetermined time.

1. Technical Field
The present disclosure relates to an outdoor unit for an air-conditioning apparatus, and an air-conditioning apparatus.
2. Related Art
Heretofore, an air-conditioning apparatus having at least one outdoor unit and a plurality of indoor units has been known. The indoor units are coupled in parallel to the outdoor unit via a plurality of refrigerant pipes. The air-conditioning apparatus is capable of allowing the indoor units to be individually set to (or select) either a cooling operation or a heating operation and allowing them to be simultaneously operated (a so-called "cooling/heating-free operation").
Such an air-conditioning apparatus is described in, for example, JP-A-2004-286253 (Patent Document 1). This air-conditioning apparatus is provided with one outdoor unit, two indoor units, and two electromagnetic valve units. The outdoor unit is provided with a compressor, an accumulator, an oil separator, a receiver tank, and two outdoor heat exchangers. The outdoor unit also includes an outdoor expansion valve, a discharge valve, and an intake valve coupled to each of the outdoor heat exchangers. Each of the indoor units is provided with an indoor heat exchanger. Each of the electromagnetic valve units is provided with two electromagnetic valves. The electromagnetic valve units switch the couplings of the respective indoor heat exchangers to the discharge side (high-pressure side) of the compressor or the intake side (low-pressure side) of the compressor.
In the air-conditioning apparatus disclosed in Patent Document 1, the outdoor unit, the indoor units, and the electromagnetic valve units are coupled via refrigerant pipes as follows. A discharge pipe coupled to the discharge side of the compressor is coupled to the oil separator and branched therefrom. One branch pipe is coupled to the outdoor heat exchangers via the discharge valves. The other branch pipe is coupled to the indoor heat exchangers via the electromagnetic valve units. The discharge pipe and the branch pipes constitute a high-pressure gas pipe.
An intake pipe coupled to the intake side of the compressor is coupled to the accumulator and branched therefrom. One branch pipe from the accumulator is coupled to the outdoor heat exchangers via the intake valves. The other branch pipe from the accumulator is coupled to the indoor heat exchangers via the electromagnetic valve units. The intake pipe and the branch pipes constitute a low-pressure gas pipe.
The outdoor heat exchangers each have two coupling ports. To one of the coupling ports, the discharge valves and the intake valves are coupled. To the other of the coupling ports, one end of a branched refrigerant pipe is coupled via the outdoor expansion valves. The other end of the refrigerant pipe is coupled to the receiver tank and branched therefrom. The branch pipes from the receiver tank are coupled to the coupling ports of the indoor heat exchangers on the side on which the electromagnetic valve units are not coupled. The refrigerant pipe and the branch pipes constitute a liquid pipe.
In the air-conditioning apparatus described above, the coupling between the indoor heat exchangers and the compressor is switched by opening or closing the electromagnetic valves of the electromagnetic valve units. Namely, by opening or closing the electromagnetic valves, the coupling between the indoor heat exchangers and the discharge side or intake side of the compressor is switched. Thus, each of the indoor heat exchangers can be caused to individually serve as a condenser or an evaporator. Thus, the cooling operation or the heating operation can be selected for the individual indoor units while the indoor units are simultaneously operated.

Outdoor unit for air-conditioning apparatus, and air-conditioning apparatus


In imaging an internal region of the human body, using optical or NMR techniques, a high resolution image is produced by imaging a layer of material formed on the region of interest which conforms to the surface of the region. The material is preferably a lipid, introduced into the body and positioned adjacent the region of interest using a probe.

This invention relates to imaging apparatus and methods and, in particular, to apparatus and methods for in vivo imaging of microscopic internal regions of a patient's body.
In some conventional systems for in vivo imaging of internal tissues, a probe is inserted into a channel, normally a naturally-occurring channel, in the body to collect signals representative of the tissue surface to be imaged, and pass the signals to image processing means.
Where the regions to be imaged are microscopically small e.g. of diameter of no more than 1.5 mms, it is difficult to achieve satisfactory resolution.
For example, when using an optical imaging technique wherein a probe directs light from a laser source onto a region of tissue and detects light reflected back from the region onto the probe, the resolution obtainable is limited by the transparency of the tissue and also by very high levels of scattering of light in the tissue. Due to such scattering the mean optical path length is at least 4.4 times that expected on geometric considerations.
When using magnetic resonance imaging techniques the problem arises that water molecules have a diffusion coefficient of around 3.5.times.10.sup.-3 m.sup.2 /s at 37.degree. C. in bulk water and the diffusion coefficient of water molecules in body tissue is likely to be much the same. In imaging systems, the time interval between RF excitation of a region and magnetic resonance data acquisition is of the order of 10 ms. Hence, half of the molecules originally excited in one part of the body tissue will have diffused over a distance of around 8 microns before their signals are acquired. Reducing the time interval between excitation and data acquisition requires wider acquisition bandwidths to be used, thus decreasing the signal to noise ratio, and also makes it necessary for stronger spatially encoding gradients to be used.
The water molecule diffusion coefficient can be reduced by restricting the free diffusion of water, but only by a relatively small factor. Alternatively, localised cooling of tissue may slow down diffusion, but this produces only a minor reduction in diffusion before the water molecules begin to form ice.

In vivo imaging microscopic interval regions of a patient's body


In a wire electric discharge machine, a permissible discharge frequency is calculated on the basis of an average discharge frequency per unit time which is estimated on the basis of a target inter-electrode voltage or a detected average inter-electrode voltage and a discharge period. The number of times a discharge is actually induced between a wire electrode and a workpiece every unit time is counted and the application of a pulse-shaped voltage is ceased for a residual time of the unit time by a control device when the discharge frequency exceeds the permissible discharge frequency.

1. Field of the Invention
The invention relates to a wire electric discharge machine for processing a workpiece (an object to be processed) by repetitively inducing a pulse-shaped discharge between a wire electrode and the workpiece.
2. Description of Related Art
In the conventional wire electric discharge machine, a pulse voltage is applied between a wire electrode and a workpiece by a power source to repetitively induce a pulse-shaped discharge between the wire electrode and the workpiece, whereby the processing of the workpiece is performed.
However, the above type of wire electric discharge machine has the problem that the wire electrode is broken when there is a frequent occurrence of abnormal discharge, having an extremely short no-load time, in which the discharge occurs between the wire electrode and the workpiece simultaneously with the application of a pulse voltage by the processing power source.
In order to solve the above problem, a method, as disclosed in U.S. Pat. No. 4,695,696, which corresponds to Japanese Patent Publication No. 2-44648, has been proposed. In this method, each discharge pulse generated between the wire electrode and the workpiece is discriminated as an abnormal discharge pulse or a normal discharge pulse on the basis of the length of the no-load time and, when an abnormal discharge pulse having short no-load time occurs, the pulse height of discharge current is reduced or a rest time for a pulse voltage supply operation is made longer to thereby reduce the discharge energy supplied between the wire electrode and the workpiece by the processing power source. In that manner, breakage of the wire electrode is avoided.
However, even when the normal discharge is induced, a so-called abnormal discharge pulse having short no-load time is very frequently actually generated.
FIG. 4 shows a typical example of a voltage waveform between the wire electrode and the workpiece to be processed.
In a graph of FIG. 4, the ordinate represents an inter-electrode voltage while the abscissa represents a time. The graph shows time-variation of the potential of the wire electrode with respect to the workpiece when the workpiece is connected to the earth such that it serves as a positive electrode side. As is apparent from FIG. 4, a number of so-called abnormal discharge pulses having short no-load time, as disclosed in U.S. Pat. No. 4,695,696, occur even when the normal discharge is induced. According to an experiment of the inventors of this application, it has been experimentally proven that a generally-defined abnormal discharge pulse is contained in an amount of about 15 to 40% of all discharge pulses even during the normal discharge operation. Therefore, if each discharge pulse is discriminated as an abnormal discharge pulse or a normal discharge pulse on the basis of only the no-load time and the discharge energy supplied between the wire electrode and the workpiece is reduced for every discrimination of the abnormal discharge pulse, it is obvious to conclude that processing speed is also reduced.
In addition, it is unreasonable, in principle, that the abnormal discharge pulses be defined on the basis of only the no-load time. That is, the judgment of abnormality or normality is originally dependent on various conditions, such as a sectional area of the wire electrode, material of the wire electrode, wire tension, discharge energy per shot, and a discharge period. Thus it is impossible to set a fixed threshold level for the no-load time. If the judgment (discrimination) of abnormality or normality is daringly made on the basis of the no-load time irrespective of the above fact, there would occur a case where the processing speed is reduced or a function of preventing the breaking of wires does not normally work when the wire electrode is changed to one having a different structure, or a processing condition such as a discharge period for a target (desired) inter-electrode voltage between the wire electrode and the workpiece to be processed is altered.

Wire electric discharge machine having function for counting number of discharge times


Various embodiments of the present invention are directed to micro-electro-mechanical systems and photonic interconnects employing micro-electro-mechanical systems. One micro-electro-mechanical system embodiment of the present invention includes a lens structure and an actuator. The lens structure includes a substantially transparent membrane having a flexible, curved surface, and a reservoir holding fluid that is fluidly coupled to the membrane. The actuator system is operably coupled to the reservoir in order to exert pressure on the fluid to change the curvature of the membrane and the focal point of the lens structure.

Distributed computing is a computer-processing method in which a single computational task is partitioned into a number of computational tasks that can be run simultaneously and separately on nodes of a distrubuted computing platform ("DCP"). A node can be a server, a computer, memory, a peripheral device or any other data processing and/or storage device. The computer may include one or more memory devices and one or more processors. In order to distribute data between nodes, the nodes are typically interconnected via high-speed, low latency, electrical interconnections to a switch, which is used to transmit data between nodes. FIG. 1 shows a schematic representation of an 8-node DCP 100. DCP 100 comprises nodes 102-109 and a switch 110. Nodes 102-109 are arranged into two columns, and are electronically interconnected to switch 110 via data-transmission cables, such as Ethernet cables. Nodes 102-109 can be stored in one or more racks or cabinets (not shown) and use switch 110 to forward packets of data between nodes 102-109 for processing. For example, switch 110 can be used to transmit data generated by node 104 to nodes 103 and 107 for further processing.
In general, DCPs are efficient computing platforms for parallel-processing applications. However, typical DCPs are inefficient energy consuming devices. In particular, metal wires are often used to interconnect nodes and node components, and much of the energy needed to transmit electrical signals over the metal wires is dissipated as heat. For example, approximately 80-90% of the electrical energy needed to transmit signals over Cu wires is dissipated as heat. In order to prevent this heat from building up and causing irreparable damage to node components, wires, and other electrical interconnects, DCPs are typically located in air conditioned rooms, and each node may include one or more fans that circulate air over node components and circuit board wires. However, the energy needed to cool DCPs only adds to the total amount of energy needed to operate DCPs. Manufacturers, designers, and users of DCPs have recognized a need for interconnects that provide high bandwidth, high-speed interconnections between nodes and node components and use less energy and generate less heat than conventional electrical interconnects used in typical DCPs.

Micro-electro-mechanical systems and photonic interconnects employing the same

Hewlett-Packard Development Company, L.P.


A process for forming metal salicide layers on an MOS transistor structure that reduces the risk of forming metal silicide bridges between source/drain regions and a polysilicon gate. The process includes the use of a uni-directional ion metal plasma deposition step to deposit a metal layer on the surface of a MOS transistor structure such that the ratio of the metal layer thickness on the surface of a gate sidewall spacers to the metal layer thickness on the surface of a polysilicon gate is no greater than 0.2. The relatively thin metal layer on the surface of the gate sidewall spacer reduces the possibility of forming metal silicide defects.

1. Field of the Invention
The present invention relates to processes for the formation of metal salicide layers during semiconductor device fabrication and, in particular, to such a process that includes a step of depositing a metal layer by ion metal plasma deposition and that provides for a reduced risk of metal silicide bridging defects.
2. Description of the Related Art
In Metal-Oxide-Semiconductor (MOS) device manufacturing, self-aligned metal silicide layers (also known as a "salicide" layers) are useful in reducing the sheet resistance of polysilicon interconnections, source regions and drains regions, as well as contact resistance. See, for example, Stanley Wolf et al., Silicon Processing for the VLSI Era I, 388-399 (Lattice Press 1986).
FIGS. 1-3 illustrate a conventional process for forming a metal salicide layer over a polysilicon gate, a source region and a drain region of an MOS transistor structure.
FIG. 1 illustrates a representative conventional MOS transistor structure 10. The MOS transistor structure 10 includes a thin gate oxide 12 overlying P-type silicon substrate 14 between N-type drain region 16 and N-type source region 18, both of which are formed in P-type silicon substrate 14. A polysilicon gate 20 overlies thin gate oxide 12, and field oxide regions 22 isolate MOS transistor structure 10 from neighboring device structures (not shown). Gate sidewall spacers 24, typically of silicon dioxide or silicon nitride, are formed on the sides of polysilicon gate 20 and thin gate oxide 12.
As illustrated in FIG. 2, in the first step of a conventional metal salicide formation process, a metal layer 28 is deposited over the surface of MOS transistor device 10. Metal layer 28 is conventionally deposited by a multi-directional evaporative or sputtering-based physical vapor deposition (PVD) process or a multi-directional chemical vapor deposition (CVD) process and is, therefore, of essentially equal thickness over the entire surface of MOS transistor structure 10.
Wherever metal layer 28 is in contact with silicon surfaces (i.e. source region 18, drain region 16 and the polysilicon surface of polysilicon gate 20) the metal is reacted to form a metal salicide layer. The conditions, such as temperature and gaseous ambient, employed for such a metal reaction are chosen to foster the reaction of the metal layer with these regions which have silicon surfaces while impeding reaction of the metal layer with the silicon dioxide or silicon nitride surfaces (i.e. the gate sidewall spacers and field oxide regions).
A selective etch is then used to remove unreacted metal from the surface of the gate sidewall spacers and field oxide regions, as well as any unreacted metal residue still remaining above the source region, drain region and polysilicon gate. The etch is "selective" since it does not remove the metal salicide layer that was formed on the surface of the silicon and polysilicon regions. The result, illustrated in FIG. 3, is a metal salicide layer 32 on the surface of drain region 16, a metal salicide layer 34 on the surface of source region 18 and a metal salicide layer 36 on the surface of polysilicon gate 20.
A drawback of conventional metal salicide processes is the tendency to form metal silicide "bridges" 40 between the salicide layer on source region 18, or drain region 16, and the salicide layer on the polysilicon gate, as shown in FIG. 4. Metal silicide bridges cause an undesirable electrical short between these regions.
Needed in the art is a process for forming a self-aligned metal silicide layer on an MOS transistor structure that provides a reduced susceptibility to the formation of metal silicide bridging defects.

Metal salicide process employing ion metal plasma deposition


An illumination system for providing an illumination beam to a light valve is provided. The illumination system includes a light source, a light integration rod, a color wheel, a first focusing unit and a second focusing unit. The light source is capable of generating the illumination beam, and the light integration rod is disposed on the transmission path of the illumination beam. The first focusing unit is disposed between the integration rod and the color wheel and is capable of focusing the illumination beam onto the color wheel. The second focusing unit is disposed between the color wheel and the light valve and is capable of focusing the illumination beam onto the light valve.

1. Field of the Invention
The present invention generally relates to an illumination system and more particularly to an illumination system for a projection apparatus.
2. Description of Relative Art
Referring to FIG. 1, an illumination system 100 of a conventional liquid crystal on silicon (LCOS) projection apparatus adopting scrolling color recapture (SCR) technology includes a light source 110, a light integration rod (LIR) 120, a color wheel 130, a polarization conversion system (PCS) 140 and a relay lens group 150. The relay lens group 150 includes a plurality of lenses 152, 154 and 156. In addition, the light source 110 is for providing an illumination beam 112 which passes through the LIR 120 and the color wheel 130, followed by being focused to an LCOS panel 50 by the relay lens group 150. The PCS 140 is disposed between the lens 152 and the lens 156, so as to convert the illumination beam 112 into a beam with the same polarization state.
In the prior art, the color wheel 130 is disposed between the LIR 120 and the relay lens group 150. However limited by the mechanism, the color wheel 130 and a light output end 124 of the LIR 120 are unable to be disposed on the object plane of the relay lens group 150, which leads to edge blur problem of a light spot on the LCOS panel 50.
Referring to FIG. 2, generally, considering the system tolerance, an ideal light spot 32 has a size slightly larger than the size of the LCOS panel 50. In fact, a light spot (as shown by the light spot 34) with blur edges is generated. The edges of the light spot 34 may fall on the LCOS panel 50 to cause that the illumination beam 112 is received by the LCOS panel 50 nonumiformly, which degrades the projection imaging quality. In the prior art, in order to avoid the edges of the light spot 36 from falling on the LCOS panel 50, the light spot size is increased (as shown by the light spot 36 in FIG. 2). However, the overfill ratio of the light spot 36 with respect to the LCOS panel 50 in the case is higher, which lowers the light utilization efficiency and the brightness of the projection images.
Referring to FIGS. 1 and 3A, the notation 38 of FIG. 3A represents a light spot formed by the illumination beam projected on the color wheel 130. The color wheel 130 is composed of multiple filters 132 with different colors. During the period from time T1 at which the boundary 133 between two adjacent filters 132 is passing the left end of a horizontal line 39a of the light spot 38 to time T2 at which the boundary 133 is passing the right end of the horizontal line 39a, the horizontal line 39a falls on two filters 132 with two different colors, such that the light with two different colors is transmitted away from the color wheel 130 to the LCOS panel 50, which causes a color mess and affects the color quality of the images. To avoid the color mess, the LCOS panel 50 usually stops image processing during the period from time T1 to time T2, which leads to a loss of image luminance.
Referring to FIG. 3B, similar to the above described, the same problem occurs during the period from time T3 at which the boundary 133 is passing through the right end of another horizontal line 39b of the light spot 38 to time T4 at which the boundary 133 is passing through the left end of the horizontal line 39b.