A storage controller system may include a host controller that queues host commands as data transfer commands in a plurality of queue channels. The storage controller system may also include a data storage controller that selects data transfer commands for execution. The data storage controller may select all data transfer commands associated with a host command when all of the data transfer commands are located at heads of the queue channels. Alternatively, the data storage controller may select for execution data transfer commands at heads of the queue channels when associated cache areas are available to receive data, regardless of whether all of the data transfer commands associated with a host command are at the heads. The host controller may then retrieve the data in the cache areas when all of the data to be sent to the host in response to the host command is being cached.

Storage systems may include a controller that handles commands received from a host. The controller may be configured to store the commands in a queue when the controller is unable to immediately execute the command. The commands may be stored in multiple channels of the queue to achieve maximum throughput. To do so, the commands may be divided into multiple sub-commands. When the individual sub-commands are executed, they may be executed at different times. That is, some of the sub-commands are executed while other sub-commands are pending in the queue.

Command and data selection in storage controller systems


According to one embodiment, a semiconductor device, includes: a first semiconductor region of a first conductivity type; a second semiconductor region provided on the first semiconductor region, an impurity concentration of the second semiconductor region being lower than an impurity concentration of the first semiconductor region; a third semiconductor region of a second conductivity type provided on the second semiconductor region; and a fourth semiconductor region provided on the third semiconductor region or in a portion of the third semiconductor region. A lattice strain of the fourth semiconductor region is greater than a lattice strain of the third semiconductor region.

Device structures and device materials to realize low-loss semiconductor devices are desirable. By using, for example, silicon carbide (SiC) as the material, it is possible to design with a lower on-resistance and a higher breakdown voltage than when silicon (Si) is used. There are cases where dislocations called basal plane dislocations (BPDs) exist inside the semiconductor substrate. It is known that the dislocations extend during the device operation particularly in a bipolar mode; characteristic fluctuation of the device occurs; and the loss increases. Because the extension of the dislocations reduces the long-term reliability of the device, it is necessary to suppress the characteristic fluctuation of the semiconductor device recited above.

Semiconductor device and method for manufacturing same


A sensor device for use in an automobile as an airflow sensor is composed of a silicon substrate in which a cavity is formed and a base plate bonded to the silicon substrate. An upper end of the cavity is closed with a thin membrane including a sensor element such as a temperature sensor element, while a lower end of the cavity is closed with the base plate. An air passage having a small cross-section is formed through the base plate, so that the cavity communicates with the outside air through the air passage. The thin membrane is prevented from being damaged by collision with foreign particles included in the airflow because the air in the cavity functions as a damper. The air passage may be made in the silicon substrate in parallel to its surface without using the base plate.

1. Field of the Invention
The present invention relates to a sensor device having a thin membrane that includes a sensor element. The sensor device is advantageously used as an airflow sensor for detecting an amount of air supplied to an internal combustion engine.
2. Description of Related Art
An example of this kind of sensor device is disclosed in JP-A-2001-50787. In this sensor device, a cavity is formed in a semiconductor substrate, and a thin membrane made of an insulating film is positioned to face the cavity. This sensor device is used as an airflow sensor for detecting an amount of air supplied to an internal combustion engine. The amount of air is detected based on temperature changes sensed by a temperature sensor element included in the thin membrane. Small particles contained in an airflow hit, or collide with, the surface of the thin membrane, and thereby the thin membrane formed by an insulating film is often damaged. To increase the mechanical strength of the membrane against collision of foreign particles, edges of the membrane where the stress of collision concentrates are reinforced by polyimide resin.
In a process of manufacturing the conventional sensor device, however, an additional process for reinforcing the membrane edges with the polyimide resin is required. Further, the amount of polyimide resin reinforcing the membrane edges is decreased by abrasion with the foreign particles that repeatedly hit the membrane surface for a long time use because the polyimide resin is soft. The same problem is common to other sensors having the thin membrane, such as a gas sensor, a humidity sensor, or an infrared sensor.

Sensor device having thin membrane and method of manufacturing the same


In one embodiment, a thin-film transistor (TFT) includes a gate electrode, a semiconductor pattern, first and second electrodes and a protective layer. The semiconductor pattern is formed on the gate electrode, and includes a first semiconductor layer deposited at a first deposition speed and a second semiconductor layer deposited at a second deposition speed faster than the first deposition speed. The first and second electrodes are spaced apart from each other on the semiconductor pattern. The protective layer is formed on the semiconductor pattern to cover the first and second electrodes, and makes contact with a channel region of the first semiconductor layer to form an interface with the first semiconductor layer. Thus, electrical characteristics of the TFT may be improved.

1. Field of the Invention
Example embodiments of the present invention relate to a thin-film transistor (TFT) and a method of manufacturing the TFT. More particularly, example embodiments of the present invention relate to a TFT capable of improving electrical characteristics between a channel region and a protective layer to decrease an off current, and a method of manufacturing the TFT.
2. Description of the Related Art
Liquid crystal display (LCD) devices are one of the most widely used types of flat panel display (FPD) devices. An LCD device includes two substrates including electrodes and a liquid crystal layer interposed between the substrates. Liquid crystals of the liquid crystal layer vary arrangement in response to an electric field applied thereto, and thus light transmittance of the liquid crystal layer is changed, thereby displaying an image. Recently, the screen size and the resolution of LCD devices have been increased.
One of the substrates of the LCD device includes a plurality of pixel electrodes arranged in a matrix shape, and another of the substrates of the LCD device includes a common electrode. When a voltage is applied to each of the pixel electrodes, the image is displayed. A thin-film transistor (TFT) that is a switching element having three terminals is electrically connected to each of the pixel electrodes. The TFT including a gate electrode, a source electrode and a drain electrode, a gate line and a data line are formed on the substrate. The gate line transmits a gate signal to control the TFT. The data line transmits a voltage to the pixel electrode. The source electrode is electrically connected to the data line. The drain electrode is spaced apart from the source electrode, and faces the source electrode. The source electrode and the drain electrode are electrically connected to a semiconductor pattern that is under the source and drain electrodes through an ohmic contact layer.
When a gate on voltage Von is applied to the gate electrode, the voltage is applied to the drain electrode through the source electrode and a channel region of the semiconductor pattern. The channel region is exposed between the source and drain electrodes.
However, electrical characteristics of the semiconductor pattern may be poor. Thus, leakage current flows from the channel region when the TFT is turned off. When the off current is increased, contrast ratio is decreased and afterimages are increased. In addition, manufacturing time is increased thereby increasing manufacturing costs for compensating the electrical characteristics of the semiconductor pattern.

Thin-film transistor and method of manufacturing the same


To provide a system and a method for providing information and a recording medium, by which communications cost and network traffic are reduced in a system which provides a plurality of pages including successive contents via a communication network. A story provider site 100 generates user ID for identifying a reader terminal 300 and reader information which includes information representing a last page, and transmits web page data segments based on the reader information together with the user ID to the reader terminal 300 concerned. The reader terminal 300 requests the pages with transmitting the user ID. The story provider site 100 transmits web page data segments based on the reader information corresponding to the returned user ID. The story provider site 100 updates the reader information based on the transmitted web page.

1. Field of the Invention
The present invention relates to a system and a method for providing information and a recording medium, suitable for providing contents of readings via communications networks.
2. Description of the Related Art
There are services for providing the contents of readings such as novels and serial columns to terminals (such as personal computers) via communications networks such as the Internet. Users of the terminals (that is, readers) operate web browser to establish sessions with the service provider's server for obtaining desired HTML based web pages representing the contents of the readings.
The readers must establish plural sessions when obtaining a full-length novel, because it requires much data. In case of providing serial column or novel, the story may be divided into plural sections, and those are uploaded one after another constantly. The readers also require plural sessions to obtain the contents of such the readings because it is impossible to download all sections at once.
Such the services generally provide the readers with index pages at beginning of each session. The index page may list indexes of available contents. In case of full-length novel, for example, the index page may list indexes of chapters, and a reader selects a chapter which follows to a chapter he/she read last time. The readers intend to forget which was the last chapter when he/she continues reading for the first time in a long while. Under such the situation, the service providers generally provide all pages at each session. It is helpful for avoiding the above problem, but increases connection time for downloading the pages. Thus, it increases network traffic and the readers' telecommunication costs.

System and method for providing information, and recording medium


The production of ethylene oxide by the catalytic vapor phase oxidation of ethylene with a molecular oxygen-containing gas is effected in a reactor provided with a preheating zone, a reaction zone, a cooling zone, a partition plate separating the first two portions from the third portion, and a multiplicity of reaction tubes piercing the two separated sections by a method which comprises supplying hot water to the cooling zone of the reactor, forwarding zone of the hot water discharged from the cooling zone to a gas-liquid separation tank, circulating the remainer of the hot water in conjunction with the cooling hot water to the cooling zone, supplying the hot water separated in the gas-liquid separation tank to the reaction zone to remove the heat of the oxidation reaction, and circulating the hot water extracted in the form of a gas-liquid mixed phase to the gas-liquid separation tank. The method is excellent to prevent isomerization of ethylene oxide to acetaldelyde which is impurity, excels in thermal efficiency and exhibits ideal durability of the partition plate.

1. Field of the Invention
This invention relates to a method for the production of ethylene oxide. More particularly, it relates to a method for producing ethylene oxide by the catalytic vapor phase oxidation of ethylene with a molecular oxygen-containing gas, which method is characterized by the use of hot water as a heat medium for the reaction apparatus.
2. Description of the Prior Art
In the process for catalytic vapor phase oxidation of a hydrocarbon, specifically the catalytic vapor phase oxidation of ethylene with a molecular oxygen-containing gas in the presence of a silver catalyst for the production of ethylene oxide, the catalytic vapor phase reaction is carried out by mixing a hydrocarbon-containing gas containing saturated hydrocarbons such as methane and ethane, nitrogen, carbon dioxide, argon, and oxygen in addition to ethylene with a molecular oxygen-containing gas such as air, oxygen-enriched air, or pure oxygen in a prescribed ratio and introducing the resultant mixed gas into a reactor packed with a silver catalyst. Like virtually all hydrocarbons, ethylene reacted with molecular oxygen in the presence of a silver catalyst induces exothermic reactions represented by the following formulas: EQU C.sub.2 H.sub.4 +1/2O.sub.2 .fwdarw.C.sub.2 H.sub.4 O+29 kcal/mol(1) EQU C.sub.2 H.sub.4 +3O.sub.2 .fwdarw.2CO.sub.2 +2H.sub.2 O316 kcal/mol(2)
For the purpose of enhancing the yield of ethylene oxide, these exothermic reactions ought to be controlled so as to allow the reaction of Formula (1) to proceed in a large ratio. In this connection, studies are being pursued regarding silver catalyst and reaction method. By the existing technical standard, however, the simultaneous occurrence of the reaction of Formula (2), namely the complete oxidation of ethylene which entails evolution of a large amount of heat of reaction, cannot be avoided.
Besides Formulas (1) and (2) mentioned above, there exists another formula which affects the yield of ethylene oxide. It is the isomerization of the produced ethylene oxide into acetaldehyde which proceeds as indicated by Formula (3) shown below. ##STR1##
No matter how high the selectivity in the conversion of ethylene to ethylene oxide may be, the degradation of the yield of ethylene oxide inevitably ensues when the isomerization of the produced ethylene oxide into acetaldehyde notably occurs.
Acetaldehyde has a boiling point very close to that of ethylene oxide. Therefore, isolation of ethylene oxide from acetaldehyde by such a process as distillation, calls for a large amount of energy even when the acetaldehyde is contained in an extremely small amount. Further, since the number of trays in the distillation column is large and the reflux ratio therein is high and consequently the cost of equipment is high, an increase in the acetaldehyde content affects the cost of purification to a large extent.
The reactor outlet gas has a high temperature and, therefore, is made to exchange heat with the reactor inlet gas for recovery of heat. The cooled reaction product gas gives rise to a drain which mainly contains water, ethylene oxide, and acetaldehyde. Since this drain has a high acetaldehyde content, the isolation of ethylene oxide from the drain is extremely difficult to perform. The drain, therefore, leads to a decline in the yield of ethylene oxide.
The cooled reaction product gas is introduced into an absorption column and absorbed therein by an absorption liquid mainly containing water and ethylene glycol and the absorption liquid now containing the absorbed reaction product gas is forwarded to the next step for purification. In this case, ethylene oxide and water partly react in the absorption liquid to form ethylene glycols. For the purpose of maintaining the concentration in the system, the absorption liquid containing the ethylene glycols is partly removed from the system and subjected to purification and recovery of ethylene glycols. Due to the impurities originating in the aldehyde contained in the absorption liquid, the recovered ethylene glycols have degraded qualities, particularly in uv absorbance. Even for the purpose of preventing the decrease of qualities, the content of these aldehydes in the absorption liquid is preferably low.
Minimization of the isomerization of ethylene oxide into acetaldehyde, therefore, constitutes in itself one of the major tasks assigned to the production of ethylene oxide.
Since the demand for ethylene oxide has been growing in recent years and for the purpose of lowering the cost of production of ethylene oxide, plans for enlarging the existing plants for the production of ethylene oxide are gaining in impetus. Thus, the amount of the heat of reaction produced in the reactors per ethylene oxide production plant is large as plainly surmised from the aforementioned formulas of reaction, though the enhancement of yield has been achieved to a considerable extent. The question on how the large amount of the heat of reaction ought to be safely and effectively recovered for reuse poses a problem of safety and economy for the production of ethylene oxide by the catalytic vapor phase oxidation of ethylene with molecular oxygen.
Generally, in the catalytic vapor phase oxidation of a hydrocarbon with molecular oxygen, the method of passing the reaction product gas through a cooling zone filled with a packing for the purpose of curbing secondary reactions has been known to the art JP-B-39-17,254(1964). The practice of applying this method to the production of ethylene oxide by the catalytic vapor phase oxidation of ethylene with molecular oxygen has also been known to the art. GB-1,449,091 and GB-1,449,092, for example, teach a method which comprises causing the reaction product obtained in a reaction zone to be passed through a cooling zone which adjoins or does not adjoin the reaction zone and contains or does not contain an inert packing. U.S. Pat. No. 4,061,659 discloses a method which comprises passing the reaction product through a cooling zone packed with inert refractory particles having a surface area of not more than 1 m.sup.2 /g.
The reaction apparatuses which are used for these methods adopt a procedure which comprises circulating a high boiling heat medium such as Dowtherm (a proprietary product of the Dow Chemical Company) or a low boiling heat medium such as water to the reaction zone for removal of heat and using a high boiling heat medium such as Dowtherm in the cooling zone. These methods have the disadvantage in that the thermal media are high boiling dangerous substances which are difficult to handle and the apparatuses are complicated and not easy to operate.
Heretofore, as a reactor for the production of ethylene oxide by the catalytic vapor phase oxidation of ethylene with molecular oxygen, a shell-and-tube exchanger type reactor which is so constructed as to cool the reaction tubes of the reactor by forcibly circulating with a pump a high boiling heat medium such as Dowtherm between the exteriors of the reaction tubes and a heat exchanger adapted to form steam thereby removing the heat of reaction, cause the heat medium consequently heated to an elevated temperature to give the heat thereof to the water through the heat exchanger and make the water generate steam, and recirculating the consequently cooled heat medium and cooling the exteriors of the reaction tubes again has been known to the art.
Besides, a shell-and-tube exchanger type reactor which is so constructed as to effect formation of steam directly on the shell side of the reactor when a vaporizable heat medium such as water is used and, therefore, obviate the necessity for using a heat exchanger adapted to form steam as described above and permit spontaneous circulation when hot water is used and, therefore, obviate the necessity for installing a pump has been known to the art.
JP-B-1-56,070(1989) proposes a method for the catalytic vapor phase oxidation of ethylene, which uses a shell-and-tube exchanger type reactor having a reaction zone and a cooling zone adjoining each other and effects the oxidation by first supplying hot water to the cooling zone, cooling the reaction product gas cooling zone, causing the hot water to be further heated and discharged out of the reactor, flushing the hot water thereby inducing gas-liquid separation, then supplying the hot water to the reaction region thereby removing the heat of reaction by cooling, allowing the hot water to boil and depart from the reactor, flushing the hot water for gas-liquid separation, circulating the hot water to the reaction zone, recovering the steam, and accomplishing effective recovery of heat.
In these conventional reactors for the production of ethylene oxide, however, the effect of curbing the occurrence of aldehydes cannot be amply fulfilled because the hot water of a temperature in the range between 100.degree. C. and 150.degree. C. is first passed through the cooling zone provided for a vertical shell-and-tube exchanger type reactor and then used for cooling the reaction zone and, as a natural consequence, the amount of the hot water passed through the cooling zone is very small as compared with that passed through the reaction zone and the reactor is destined to be cooled unevenly. Moreover, the baffle plate portion of the cooling zone, the lower tube plate contiguous to the hot water in the cooling zone, and the lower tube plate contiguous to the reaction product gas have the possibility of generating thermal stress and causing vibration.
This invention has been produced to solve the problems encountered by the conventional reactors as described above.
An object of this invention is to provide a method for the production of ethylene oxide which eliminates the possibility of the baffle plate portion of the cooling zone of the vertical shell-and-tube exchanger type reactor for the production of ethylene oxide, the lower tube plate contiguous to the hot water of the cooling zone, and the lower tube plate contiguous to the reaction product gas generating thermal stress and inciting vibration, promotes enhancement of thermal efficiency, and heightens the effect of curbing the isomerization of ethylene oxide into aldehydes as impurities.


Example implementations relate to a dual-sided fan tray assembly of an electronic system. The fan tray assembly includes a housing having a front panel, a back panel, and a pair of side walls coupled to the front and back panels. The fan tray assembly further includes a handle assembly pivotably connected to the pair of side walls such that the handle assembly is at least rotatable around the housing to at least first and second positions spaced apart from each other. When the handle assembly is rotated to the first position, the fan tray assembly is slidably insertable into a chassis of an electronic system with the front panel facing the chassis to install the fan tray assembly to the electronic system. When the handle assembly is rotated to the second position, the fan tray assembly is slidably insertable into the chassis with the back panel facing the chassis.

Electronic systems, for example, a server system or a switch system may include a fan tray assembly having a plurality of fans to supply coolant air for dissipating a waste-heat from an interior of the electronic system. Typically, many of the various electronic devices disposed within the electronic system generates the waste-heat while operating. For example, the electronic devices, such as power supply units, hard drives, circuit boards of the electronic system may generate the waste-heat. To avoid overheating of the electronic devices, the plurality of fans may either draw the coolant air and/or blow the coolant air over such electronic devices. Thus, the coolant airflow generated by the plurality of fans may provide forced convection that may transfer the waste-heat from the electronic devices to the coolant air, thereby generating a heated air. Normally, the heated air exits the interior of the electronic system via a front panel or a back panel of the electronic system.

Dual-sided fan tray assembly of an electronic system

Hewlett Packard Enterprise Development LP


Method for holding a vehicle in the stationary state, which has the following steps: (a) if the vehicle has an automatic transmission, engaging a parking lock, or if the vehicle has a manual transmission, engaging a gear, (b) at least temporarily, automatically carrying out vehicle movement monitoring by means of a sensing device; and (c) automatically activating a brake device of the vehicle in order to apply a braking force if the sensing device signals a vehicle movement.

In order to park a vehicle with an automatic transmission, the P position of the gear selector lever is engaged. A parking lock (also referred to as a parking pawl) thereupon engages on a corresponding toothing arrangement on the transmission output. With this positive engagement the transmission is prevented from rotating if a torque acts on the wheels, and therefore on the drive train, owing to a downgrade force. In order to provide additional securement, it is known also to close a parking brake automatically or manually along with the engagement of the P position.
In the case of vehicles with a manual transmission, a gear, in particular the first gear or the reverse gear, is correspondingly engaged for the purpose of parking. Furthermore, a parking brake for additionally securing the vehicle is usually activated automatically or manually.

Method for holding a vehicle in the stationary state, open-loop and closed-loop control device for a brake device of a vehicle and brake device of a vehicle


A new vehicle screen for attaching to the exterior roof of a vehicle to cover an open roof opening. The inventive device includes a generally rectangular flexible mesh screen having a plurality of spaces therethrough. A flexible border member is extended around the outer periphery of the mesh screen. The lower surface of the border member is designed for detachably mounting on the exterior roof of a vehicle around the periphery of a roof opening through the roof of the vehicle. Provided on the lower surface is a magnetic strip which is designed for magnetically mounting the lower surface of the border member to the exterior roof of a vehicle. Provided on the upper surface of the border member is an elongate attachment strip. The attachment strip is designed for attaching to a wind shield device upwardly extending from the exterior roof of a vehicle adjacent the roof opening. The border member and the mesh screen, along with the strips are all sufficiently flexible to permit rolling up of the border member and the mesh screen into a generally cylindrical roll.

1. Field of the Invention
The present invention relates to vehicle screens and more particularly pertains to a new vehicle screen for attaching to the exterior roof of a vehicle to cover an open roof opening, such as a sun roof.
2. Description of the Prior Art
The use of vehicle screens is known in the prior art. More specifically, vehicle screens heretofore devised and utilized are known to consist basically of familiar, expected and obvious structural configurations, notwithstanding the myriad of designs encompassed by the crowded prior art which have been developed for the fulfillment of countless objectives and requirements.
Known prior art vehicle screens include U.S. Pat. Nos. 4,993,471; 5,040,839; 360,181; 4,395,939; 4,872,722; and 4,702,518.
While these devices fulfill their respective, particular objectives and requirements, the aforementioned patents do not disclose a new vehicle screen. The inventive device includes a generally rectangular flexible mesh screen having a plurality of spaces therethrough. A flexible border member is extended around the outer periphery of the mesh screen. The lower surface of the border member is designed for detachably mounting on the exterior roof of a vehicle around the periphery of a roof opening through the roof of the vehicle. Provided on the lower surface is a magnetic strip which is designed for magnetically mounting the lower surface of the border member to the exterior roof of a vehicle. Provided on the upper surface of the border member is an elongate attachment strip. The attachment strip is designed for attaching to a wind shield device upwardly extending from the exterior roof of a vehicle adjacent the roof opening. The border member and the mesh screen, along with the strips are all sufficiently flexible to permit rolling up of the border member and the mesh screen into a generally cylindrical roll.
In these respects, the vehicle screen according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of attaching to the exterior roof of a vehicle to cover an open roof opening, such as a sun roof.


A method of implementing a casino table poker game, the method including (a) receiving an ante wager from a player, (b) dealing a player's hand and a dealer's hand, (c) determining by the player whether to raise or fold, (d) if the player raises in the determining, then the player places a raise wager and then both the player's hand and the dealer's hand are revealed, (e) evaluating who has the higher hand, the dealer or the player, (f) if the dealer has the higher hand in the evaluating, then the player loses the ante wager and the raise wager, and (g) if the player has the higher hand in the evaluating, then the player pushes on the ante wager and wins a paytable payout on the raise wager.

1. Field of the Invention
The present invention is directed to a method, apparatus, and computer readable storage medium directed to casino poker games.
2. Description of the Related Art
Casino games are a billion dollar industry, both in the U.S. and around the world.
What is needed is a new poker game which can increase player enjoyment as well as casino revenue.


Visibility profiles associated with a substantially real time messaging environment are disclosed. Additionally, techniques for managing visibility profiles are disclosed, which include automatically associating a first profile with a first situation, automatically associating a second profile with a second situation, and where the first and second profiles are associated with visibility. Visibility profiles may be used to manage the appearance of a user to other users/friends for communication using applications such as instant messaging, electronic mail, web-based mail programs, or other types of data communication exchange applications.

Applications, programs, and other activities that enable users to control and personalize their online activities are useful. However, conventional techniques are often limited in their ability to invoke privacy protections without adversely impacting communications.
Internet and internetworking based technologies such as instant messaging and e-mail are often considered to be personalized communication applications that enable simple, but direct messaging from one user to another or several users. Specialized services such as personal accounts and other forms of tailored communication applications have been developed to meet the growing demand for personalized communication services. However, these services are often limited in features, capabilities, and configurability. Further, conventional techniques are often limited in terms of privacy and accessibility control.
Managing online interaction often involves the use of applications that enable a user to configure her online activities. Such applications can enable a person to establish particular settings that affect privacy, accessibility, and other user attributes. However, these applications can also detrimentally impact the ability of a user to communicate, often stopping or interrupting communication with friends entirely or rendering a communication application (e.g., instant messaging) virtually useless.
Thus, what is needed is a solution for configuring online interactivity without detrimentally affecting communication abilities or user control.

This patent is subject to a terminal disclaimer.

Associating multiple visibility profiles with a user of real-time communication system


The present invention provides a configuration of a computer-chassis containment or other electromagnetic device method for manufacture in which a “one-hit” solution may be implemented to provide adequate electromagnetic interference shielding (EMC shielding) and is configured such that shielding gaskets, “spoons” or other excessive structures may be reduced or eliminated completely. Patterned sinusoidal “patterns” that are stamped, molded, cut, or extruded into one or more sides of a “box” provide sufficient EMI shielding, such that the need for gaskets is reduced or eliminated.

The following background section is, in part, reprinted from "Design Techniques for EMC—Part 4 Shielding" by Eur Ing Keith Armstrong, Cherry Clough Consultants, Associate of EMC-UK.
A complete volumetric shield is often known as a "Faraday Cage", although this can give the impression that a cage full of holes (like Mr Faraday's original) is acceptable, which it generally is not. There is a cost hierarchy to shielding which makes it commercially important to consider shielding early in the design process. Shields may be fitted around the following: individual ICs—example cost 25 P; segregated areas of PCB circuitry—example cost £1; whole PCBs—example cost £10; sub-assemblies and modules—example cost £15; complete products—example cost £100; assemblies (e.g. industrial control and instrumentation cubicles)—example cost £1,000; rooms—example cost £10, 0000; and buildings—example cost £100,000.
Shielding always adds cost and weight, so it is always best to use the other techniques described in this series to improve EMC and reduce the need for shielding. Even when it is hoped to avoid shielding altogether, it is best to allow for Murphy's Law and design from the very conception so that shielding can be added later if necessary. A degree of shielding can also be achieved by keeping all conductors and components very close to a solid metal sheet. Ground-planed PCBs populated entirely by low-profile surface mounted devices are therefore are recommended for their EMC advantages.
A useful degree of shielding can be achieved in electronic assemblies firstly, by keeping their internal electronic units and cables very close to an earthed metal surface at all times, and secondly, by bonding their earths directly to the metal surface instead of (or as well as) using a safety star earthing system based on green/yellow wires. This technique usually uses zinc-plated mounting plates or chassis, and can help avoid the need for high values of enclosure SE.
Many textbooks have been written on the subject of how shields work, and it is not intended to repeat them here. However, a few broad concepts will help. A shield puts an impedance discontinuity in the path of a propagating radiated electromagnetic wave, reflecting it and/or absorbing it. This is conceptually very similar to the way in which filters work—they put an impedance discontinuity in the path of an unwanted conducted signal. The greater the impedance ratio, the greater the SE.
At thicknesses of 0.5 mm or over, most normal fabrication metals provide good SE above 1 MHz and excellent SE above 100 MHz. Problems with metal shields are mostly caused by thin materials, frequencies below 1 MHz, and apertures.
It is generally best to allow a large distance between the circuits that are shielded and the walls of their shield. The emitted fields outside of the shield, and the fields that the devices are subjected to, will generally be more "diluted" the larger the shielded volume.
When enclosures have parallel walls opposite each other, standing waves can build up at resonant frequencies and these can cause SE problems. Irregular shaped enclosures or ones with curved or non-parallel walls will help prevent resonances. When opposing shield walls are parallel, it is desirable to prevent resonances from occurring at the same frequencies due to width, height, or length. So, in order to avoid cubic enclosures, rectangular cross-sections can be used instead of square ones, and it is preferable to avoid dimensions that are simple multiples of each other. For example, if the length is 1.5 times the width, the second resonance of the width should coincide with the third resonance of the length. It is preferable to use irrationally ratio'd dimensions, such as those provided by the Fibonacci series.
Fields come in two flavours: electric (E) and magnetic (M). Electromagnetic fields consist of E and M fields in a given ratio (giving a wave impedance E/M of 377 in air). Electric fields are easily stopped by thin metal foils since the mechanism for electric field shielding is one of charge re-distribution at a conductive boundary; therefore, almost anything with a high conductivity (low resistance) will present suitably low impedance. At high frequencies, considerable displacement currents can result from the rapid rate of charge re-distribution, but even thin aluminium can manage this well. However, magnetic fields are much more difficult to stop. They need to generate eddy currents inside the shield material to create magnetic fields that oppose the impinging field. Thin aluminium is not going to be very suitable for this purpose, and the depth of current penetration required for a given SE depends on the frequency of the field. The SE also depends on the characteristics of the metal used for the shield which is known as the "skin effect".
The skin depth of the shield material known as the "skin effect" makes the currents caused by the impinging magnetic field to be reduced by approximately 9 dB. Hence a material which was as thick as 3 skin depths would have an approximately 27 dB lower current on its opposite side and have an SE of approximately 27 dB for that M field.
The skin effect is especially important at low frequencies where the fields experienced are more likely to be predominantly magnetic with lower wave impedance than 377Ω. The formula for skin depth is given in most textbooks; however, the formula requires knowledge of the shielding material's conductivity and relative permeability.
Copper and aluminium have over 5 times the conductivity of steel, so are very good at stopping electric fields, but have a relative permeability of 1 (the same as air). Typical mild steel has a relative permeability of around 300 at low frequencies, falling to 1 as frequencies increase above 100 kHz. The higher permeability of mild steelgives it a reduced skin depth, making the reasonable thicknesses better than aluminium for shielding low frequencies. Different grades of steels (especially stainless) have different conductivities and permeabilities, and their skin depths will vary considerably as a result. A good material for a shield will have high conductivity and high permeability, and sufficient thickness to achieve the required number of skin-depths at the lowest frequency of concern. 1 mm thick mild steel plated with pure zinc (for instance 10 microns or more) is suitable for many applications.
It is easy to achieve SE results of 100 dB or more at frequencies above 30 MHz with ordinary constructional metalwork. However, this assumes a perfectly enclosing shield volume with no joints or gaps, which makes assembly of the product rather difficult unless you are prepared to seam-weld it completely and also have no external cables, antenna, or sensors (rather an unusual product). In practice, whether shielding is being done to reduce emissions or to improve immunity, most shield performance are limited by the apertures within it. Considering apertures as holes in an otherwise perfect shield implies that the apertures act as half-wave resonant "slot antenna". This allows us to make predictions about maximum aperture sizes for a given SE: for a single aperture, SE=20 log(Ω/2d) where Ω is the wavelength at the frequency of interest and d is the longest dimension of the aperture. In practice, this assumption may not always be accurate, but it has the virtue of being an easy design tool which is a good framework. It may be possible to refine this formula following practical experiences with the technologies and construction methods used on specific products.
The resonant frequency of a slot antenna is governed by its longest dimension—its diagonal. It makes little difference how wide or narrow an aperture is, or even whether there is a line-of-sight through the aperture.
Even apertures, the thickness of a paint or oxide film, formed by overlapping metal sheets, still radiate (leak) at their resonant frequency just as well as if they were wide enough to poke a finger through. One of the most important EMC issues is keeping the product's internal frequencies internal, so they don't pollute the radio spectrum externally.
The half-wave resonance of slot antenna (expressed in the above rule of thumb: SE=20 log(2d)) using the relationship v=fλ (where v the speed of light: 3.108 meters/sec, f is the frequency in Hz, and is the wavelength in meters). We find that a narrow 430 mm long gap along the front edge of a 19-inch rack unit's front panel will be half-wave resonant at around 350 MHz. At this frequency, our example 19″ front panel is no longer providing much shielding and removing it entirely might not make much difference. For an SE of 20 dB at 1 GHz, an aperture no larger than around 16 mm is needed. For 40 dB this would be only 1.6 mm, requiring the gaskets to seal apertures and/or the use of the waveguide below cut-off techniques described later. An actual SE in practice will depend on internal resonances between the walls of the enclosure itself, the proximity of components and conductors to apertures (keep noisy cables such as ribbon cables carrying digital busses well away from shield apertures and joints) and the impedances of the fixings used to assemble the parts of the enclosure, etc.
Wherever possible, it is desirable to break all necessary or unavoidable apertures into a number of smaller ones. Unavoidably long apertures (covers, doors, etc) may need conductive gaskets or spring fingers (or other means of maintaining shield continuity). The SE of a number of small identical apertures nearby each other is (roughly) proportional to their number (SE=20 log n, where n is the number of apertures), so two apertures will be worse by 6 dB, four by 12 dB, 8 by 18 dB, and so on. But when the wavelength at the frequency of concern starts to become comparable with the overall size of the array of small apertures, or when apertures are not near to each other (compared with the wavelength), this crude 6 dB per doubling rule breaks down because of phase cancellation effects.
Apertures placed more than half a wavelength apart do not generally worsen the SEs that achieves individually, but half a wavelength at 100 MHz is 1.5 meters. At such low frequencies on typical products smaller than this, an increased number of apertures will tend to worsen the enclosure's SE.
Apertures don't merely behave as slot antenna. Currents flowing in a shield and forced to divert their path around an aperture will cause it to emit magnetic fields. Voltage differences across an aperture will cause the aperture to emit electric fields. The author has seen dramatic levels of emissions at 130 MHz from a hole no more than 4 mm in diameter (intended for a click-in plastic mounting pillar) in a small PCB-mounted shield over a microcontroller.
The only really sensible way to discover the SE of any complex enclosure with apertures is to model the structure, along with any PCBs and conductors (especially those that might be near any apertures) with a 3-dimensional field solver. Software packages that can do this now have more user-friendly interfaces and run on desktop PCs. Alternatively, the user will be able to find a university or design consultancy that has the necessary software and the skills to drive it.
Since an SE will vary strongly with the method and quality of assembly, materials, and internal PCBs and cables, it is always best to allow an SE 'safety margin' of 20 dB. It may also be advantageous to at least include design-in features that will allow improvement of the SE by at least 20 dB if there are problems with the final design's verification/qualification testing.
The frequency of 50 Hz is problematic, and an SE at this frequency with any reasonable thickness of ordinary metals is desirable. Special materials such as Mumetal and Radiometal have very high relative permeabilities, often in the region of 10,000. Their skin depth is correspondingly very small, but they are only effective up to a few tens of kHz. It is advantageous to take care not to knock items made of these materials, as this ruins their permeability and they have to be thrown away or else re-annealed in a hydrogen atmosphere. These exotic materials are used rather like channels to divert the magnetic fields away from the volume to be protected. This is a different concept to that used by ordinary shielding.
All metals shield materials with relative permeability greater than 1 can saturate in intense magnetic fields, and then don't work well as shields and often heat up. A steel or Mumetal shield box over a mains transformer to reduce its hum fields can saturate and fail to achieve the desired effect. Often, this is all that is necessary to make the box larger so it does not experience such intense local fields. Another shielding technique for low frequency shielding is active cancellation, and at least two companies have developed this technique specifically for stabilizing the images of CRT VDUs in environments polluted by high levels of power frequency magnetic fields.
FIG. 1D shows that if we extend the distance that a wave leaking through an aperture has to travel between surrounding metal walls before it reaches freedom, we can achieve respectable SEs even though the apertures may be large enough to put a fist through. This very powerful technique is called "waveguide below cut-off". Honeycomb metal constructions are really a number of waveguides below cut-off stacked side-by-side, and are often used as ventilation grilles for shielded rooms, similar to high-SE enclosures. Like any aperture, a waveguide allows all its impinging fields to pass through when its internal diagonal (g) is half a wavelength. Therefore, the cut-off frequency of our waveguide is given by: fcutoff=150,000/g (answer in MHz when g is in mm.) Below its cut-off frequency, a waveguide does not leak like an ordinary aperture (as shown by FIG. 1A) and can provide a great deal of shielding: for f<0.5fcutoff SE is approximately 27d/g where d is the distance through the waveguide the wave has to travel before it is free.
FIG. 1A shows examples of the SE achieved by six different sizes of waveguides below cut-off. Smaller diameter (g) results in a higher cut-off frequency, with a 50 mm (2 inch) diameter achieving full attenuation by 1 GHz. Increased depth (d) results in increased SE, with very high values being readily achieved.
Waveguides below cut-off do not have to be made out of tubes, and can be realized using simple sheet metalwork which folds the depth (d) so as not to increase the size of the product by much. As a technique, it is only limited by the imagination, but it must be taken into consideration early in a project as it is usually difficult to retro-fit to a failing product .not intended for use. Conductors should never be passed through waveguides below cut-off, as this compromises their effectiveness. Waveguides below cut-off can be usefully applied to plastic shafts (e.g. control knobs) so that they do not compromise the SE where they exit an enclosure. The alternative is to use metal shafts with a circular conductive gasket and suffer the resulting friction and wear. Waveguides below cut-off can avoid the need for continuous strips of gasket, and/or for multiple fixings, and thus save material costs and assembly times.
Gaskets are used to prevent leaky apertures at joints, seams, doors and removable panels. For fit-and-forget assemblies, gasket design is not too difficult, but doors, hatches, covers, and other removable panels create many problems for gaskets, as they must meet a number of conflicting mechanical and electrical requirements, not to mention chemical requirements (to prevent corrosion). Shielding gaskets are sometimes required to be environmental seals as well, adding to the compromise.
FIG. 1B shows a typical gasket design for the door of an industrial cabinet, using a conductive rubber or silicone compound to provide an environmental seal as well as an EMC shield. Spring fingers are often used in such applications as well.
It is worth noting that the green/yellow wire used for safety earthing of a door or panel has no benefits for EMC above a few hundred kHz. This might be extended to a few MHz if a short wide earthing strap is used instead of a long wire.
A huge range of gasket types is available from a number of manufacturers, most of whom also offer customizing services. This observation reveals that no one gasket is suitable for a wide range of applications. Considerations when designing or selecting gaskets include: (1) mechanical compliance; (2) compression set; (3) impedance over a wide range of frequencies; (4) resistance to corrosion (low galvanic EMFs in relation to its mating materials, appropriate for the intended environment); (5) the ability to withstand the expected rigors of normal use; (6) shape and preparation of mounting surface (7) ease of assembly and dis-assembly; and (8) environmental sealing, and smoke and fire requirements.
There are four main types of shielding gaskets: conductive polymers, conductively wrapped polymers, metal meshes and spring fingers. (1) Conductive polymers (insulating polymers with metal particles in them double as environmental seals, and have low compression set but need significant contact pressure, making them difficult to use in manually-opened doors without lever assistance. (2) Conductively wrapped polymers (polymer foam or tube with a conductive outer coating can be very soft and flexible, with a low compression set. Some only need low levels of contact pressure. However, they may not make the best environmental seals and their conductive layer may be vulnerable to wear. (3) Metal meshes (random or knitted) are generally very stiff but match the impedance of metal enclosures better and so have better SEs than the above types. They have poor environmental sealing performance, but some are now supplied bonded to an environmental seal, so that two types of gaskets may be applied in one operation. (4) Spring fingers ("finger stock") are usually made of beryllium copper or stainless steel and can be very compliant. Their greatest use is on modules (and doors) which must be easy to manually extract (open), easy to insert (close), and which have a high level of use. Their wiping contact action helps to achieve a good bond, and their impedance match to metal enclosures is good, but when they don't apply high pressures, maintenance may be required (possibly a smear of petroleum jelly every few years). Spring fingers are also more vulnerable to accidental damage, such as getting caught in a coat sleeve and bending or snapping off. The dimensions of spring fingers and the gaps between them causes inductance, so for high frequencies or critical use a double row may be required, such as can be seen on the doors of most EMC test chambers.
Gaskets need appropriate mechanical provisions made on the product to be effective and easy to assemble. Gaskets simply stuck on a surface and squashed between mating parts may not work as well as is optimal—the more their assembly screws are tightened in an effort to compress the gasket and make a good seal, the more the gaps between the fixings can bow, opening up leaky gaps. This is because of inadequate stiffness in the mating parts, and it is difficult to make the mating parts rigid enough without a groove for the gasket to be squashed into, as shown by FIG. 1B. This groove also helps correctly position and retains the gasket during assembly.
Gasket contact areas must not be painted (unless it is with conductive paint), and the materials used, their preparation and plating must be carefully considered from the point of view of galvanic corrosion. All gasket details and measures must be shown on manufacturing drawings, and all proposed changes to them must be assessed for their impact on shielding and EMC. It is not uncommon, when painting work is transferred to a different supplier, for gaskets to be made useless because masking information was not put on the drawings. Changes in the painting processes used can also have a deleterious effect (as can different painting operatives) due to varying degrees of overspray into gasket mounting areas which are not masked off.
FIG. 1C shows a large aperture in the wall of the shielded enclosure, using an internal "dirty box" to control the field leakage through the aperture. The joint between the dirty box and the inside of the enclosure wall must be treated the same as any other joint in the shield.
A variety of shielded windows are available, based on two main technologies: thin metal films on plastic sheets and embedded metal meshes. (1) Thin metal films on plastic sheets, usually indium-tin-oxide (ITO). At film thicknesses of 8 microns and above, optical degradation starts to become unacceptable, and for battery-powered products, the increased backlight power may prove too onerous. The thickness of these films may be insufficient to provide good SEs below 100 MHz. (2) Embedded metal meshes, are usually made of a fine mesh of blackened copper wires. For the same optical degradation as a metal film, these provide much higher SEs, but they can suffer from Moiré fringing with the display pixels if the mesh is not sized correctly. One trick is to orient the mesh diagonally.
Honeycomb metal display screens are also available for the very highest shielding performance. These are large numbers of waveguides below cut-off, stacked side by side, and are mostly used in security or military applications. The extremely narrow viewing angle of the waveguides means that the operator's head prevents anyone else from sneaking a look at their displays.
The mesh size must be small enough not to reduce the enclosure's SE too much. The SE of a number of small identical apertures near to each other is (roughly) proportional to their number, n, (DSE=20 log n), so two apertures will make SE worse by 6 dB, four by 12 dB, 8 by 18 dB, and so on. For a large number of small apertures typical of a ventilation grille, mesh size will be considerably smaller than one aperture on its own would need to be for the same SE. At higher frequencies where the size of the ventilation aperture exceeds one-quarter of the wavelength, this crude "6 dB per doubling" formula can lead to over-engineering, but no simple rule of thumb exists for this situation.
Waveguides below cut-off allow high air flow rates with high values of SE. Honeycomb metal ventilation shields (consisting of many long narrow hexagonal tubes bonded side-by-side) have been used for this purpose for many years. It is believed that at least one manufacturer of highly shielded 19″ rack cabinets claims to use waveguide below cut-off shielding for the top and bottom ventilation apertures that use ordinary sheet metalwork techniques.
The design of shielding for ventilation apertures can be complicated by the need to clean the shield of the dirt deposited on it from the air. Careful air filter design can allow ventilation shields to be welded or otherwise permanently fixed in place.
Plastic enclosures are often used for a pleasing feel and appearance, but can be difficult to shield. Coating the inside of the plastic enclosure with conductive materials such as metal particles in a binder (conductive paint), or with actual metal (plating), is technically demanding and requires attention to detail during the design of the mould tooling if it is to stand a chance of working.
It is often found, when it is discovered that shielding is necessary, that the design of the plastic enclosure does not permit the required SE to be achieved by coating its inner surfaces. The weak points are usually the seams between the plastic parts; they often cannot ensure a leak-tight fit, and usually cannot easily be gasketted. Expensive new mould tools are often needed, with consequent delays to market introduction and to the start of income generation from the new product.
Whenever a plastic case is required for a new product, it is financially vital that consideration be given to achieving the necessary SE right from the start of the design process.
Paint or plating on plastic can never be very thick, so the number of skin-depths achieved can be quite small. Some clever coatings using nickel and other metals have been developed to take advantage of nickel's reasonably high permeability in order to reduce skin depth and achieve better SE.
Other practical problems with painting and plating include making them stick to the plastic substrate over the life of the product in its intended environment. This is not easy to do without expert knowledge of the materials and processes. Conductive paint or plating flaking off inside a product can do a lot more than compromise EMC—it can short out conductors, causing unreliable operation and risk fires and electrocution. Painting and plating plastics must be done by experts with long experience in that specialized field.
A special problem with painting or plating plastics is voltage isolation. For class II products (double insulated), adding a conductive layer inside the plastic cases can reduce creepage and clearance distances and compromise electrical safety. Also, for any plastic-cased product, adding a conductive layer to the internal surface of the case can encourage personnel electrostatic discharge (ESD) through seams and joints, possibly replacing a problem of radiated interference with the problem of susceptibility to ESD. For commercial reasons, it is important that careful design of the plastic enclosure occurs from the beginning of the design process if there is any possibility that shielding might eventually be required.
Some companies box cleverly (pun intended) by using thin and unattractive low-cost metal shields on printed circuit boards or around assemblies, making it unnecessary for their pretty plastic case to do double duty as a shield. This can save a great deal of cost and headache, but must be considered from the start of a project or else there will be no room available (or the wrong type of room) to fit such internal metalwork.
Volume-conductive plastics or resins generally use distributed conductive particles or threads in an insulating binder which provides mechanical strength. Sometimes these suffer from forming a "skin" of the basic plastic or resin, making it difficult to achieve good RF bonds without helicoil inserts or similar means. These insulating skins make it difficult to prevent long apertures which are created at the joints, and also make it difficult to provide good bonds to the bodies of connectors, glands, and filters. Problems with the consistency of mixing conductive particles and polymers can make enclosures weak in some areas and lacking in shielding in others.
Materials based on carbon fibres (which are themselves conductive) and self-conductive polymers are starting to become available, but they do not have the high conductivity of metal and so do not give as good an SE for a given thickness. The screens and connectors (or glands) of all screened cables that penetrate a shielded enclosure, and their 360° bonding, are as vital a part of any "Faraday Cage" as the enclosure metalwork itself. The thoughtful assembly and installation of filters for unshielded external cables is also vital to achieve a good SE. Refer to the draft IEC1000-5-6 (95/210789 DC from BSI) for best practices in industrial cabinet shielding (and filtering). Refer to BS IEC 61000-5-2:1998 for best practices in cabling (and earthing).
Returning to our original theme of applying shielding at as low a level of assembly as possible to save costs, we should consider the issues of shielding at the level of the PCB. The ideal PCB-level shield is a totally enclosing metal box with shielded connectors and feedthrough filters mounted in its walls, which is in fact just a miniature version of a product-level shielded enclosure as described above. The result is often called a module which can provide extremely high SEs, and is very often used in the RF and microwave worlds.
Lower cost PCB shields are possible, although their SE is not usually as good as a well-designed module. It all depends upon a ground plane in a PCB used to provide one side of the shield, so that a simple five-sided box can be assembled on the PCB like any other component. Soldering this five-sided box to the ground plane at a number of points around its circumference creates a "Faraday cage" around the desired area of circuitry. A variety of standard five-sided PCB-mounted shielding boxes are readily available, and companies who specialize in this kind of precision metalwork often make custom designs. Boxes are available with snap-on lids so that adjustments may easily be made, test points accessed, or chips replaced, with the lid off. Such removable lids are usually fitted with spring-fingers all around their circumference to achieve a good SE when they are snapped in place.
Weak points in this method of shielding are obviously the different variations of apertures such as the following: the apertures created by the gaps between the ground-plane soldered connections; any apertures in the ground plane (for example clearances around through-leads and via holes); and any other apertures in the five-sided box (for example ventilation, access to adjustable components, displays, etc.) Seam-soldering the edges of a five-sided box to a component-side ground plane can remove one set of apertures, at the cost of a time-consuming manual operation.
For the lowest cost, we want to bring all our signals and power into the shielded area of our PCB as tracks, avoiding wires and cables. This means we need to use the PCB equivalents of bulkhead-mounting shielded connectors and bulkhead-mounting filters.
The PCB track equivalent of a shielded cable is a track run between two ground planes, often called a "stripline." Sometimes guard tracks are run on both sides of this "shielded track" on the same copper layer. These guard tracks have very frequently via holes bonding them to the top and bottom ground planes. The number of via holes per inch is the limiting factor here, as the gaps between them act as shield apertures (the guard tracks have too much inductance on their own to provide a good SE at high-frequencies). Since the dielectric constant of the PCB material is roughly four times that of air, when FIGS. 1A-1E are used to determine via spacing, their frequency axes should be divided by two (the square root of the PCB's dielectric constant). Some designers don't bother with the guard tracks and just use via holes to "channel" the track in question. It may be a good idea to randomly vary the spacings of such rows of via holes around the desired spacing in order to help avoid resonances.
Where striplines enter an area of circuitry enclosed by a shielded box, it is sufficient that their upper and lower ground planes (and any guard tracks) are bonded to the screening can's soldered joints on both sides close to the stripline.
The track which only has a single ground plane layer parallel, the other side being exposed to the air, is said to be of "microstrip" construction. When a microstrip enters a shielded PCB box, it will suffer an impedance discontinuity due to the wall of the box. If the wavelength of the highest frequency component of the signals in the microstrip is greater than 100 times the thickness of the box wall (or the width of box mounting flange), the discontinuity may be too brief to register. But where this is not the case, some degradation in performance may occur and such signals are best routed using striplines.
All unshielded tracks must be filtered as they enter a shielded PCB area. It is often possible to get valuable improvements using PCB shielding without such filtering, but this is difficult to predict. Therefore, filtering should always be designed-in (at least on prototypes, only being removed from the PCB layout after successful EMC testing).
The best filters are feedthrough types, but to save cost it is advantageous to avoid wired types. Leaded PCB-mounting types are available and can be soldered to a PCB in the usual manner. Then the leaded PCB mount is hand-soldered to the wall of the screening box when it is fitted at a later stage. Quicker assembly can be achieved by soldering the central contact of the filter to the underlying ground plane, making sure that solder joints between the shielding box and the same ground plane layer are close by on both sides. This latter construction also suits surface-mounted "feed-through" filters, further reducing assembly costs.
But feed-through filters, even surface mounted types, are still more expensive than simple ferrite beads or capacitors. To allow the most cost-effective filters to be found during development EMC testing, whilst also minimizing delay and avoiding PCB layout iterations, multipurpose pad patterns can easily be created to take any of the following filter configurations: (1) zero-ohm link (no filtering, often used as the starting point when EMC testing a new design); (2) a resistor or ferrite bead in series with the signal; ((3) a capacitor to the ground plane; (4) common-mode chokes; (5) resistor/ferrite/capacitor combinations (tee, LC, etc. see Part 3 of this series for more details); (6) feed-through capacitor (i.e. centre-pin grounded, not truly feed-through) and; (7) feedthrough filter (tee, LC, etc., center-pin grounded, not truly feedthrough). Multipurpose padding also means the invention not restricted to proprietary filters and be created to best suit the requirements of the circuit (and the product as a whole) at the lowest cost.
In finding EMI/EMC solutions, the existing technology is inelegant and cumbersome. For example, the prior art uses spoons, which are these little projections with dimples in them that stick out; so that they go into compression and go opposite. One goes over the other so that they go together and they have to make physical contact. These structures bend and when one of them bends at a plane and they don't make contact anymore, they lose their electrical conduct. Then the prior art starts to have EMI leaks. They become tolerance nightmares and they're expensive. In addition, prior art manufacturing techniques designed to counter these problems requires forming the enclosure so that it has to have a tongue and groove or other prohibitive solutions.

EMI-shielding solutions for computer enclosures using combinations of two and three-dimensional shapes formed in sheet metal


A device for measuring out coffee in a coffee-maker with conical paper or synthetic fibre filter, characterised in that it comprises at least a slide (300) including at least a mark for measuring out an amount of coffee when the slide (300) is arranged inside a volume defined by a wall (2) of the filter, the slide (300) being arranged along the wall (2) when measuring out at least an amount of coffee.

This invention concerns a device for measuring out coffee tipped straight from the packet into the conical filter of a coffee-maker.
Traditionally coffee is measured out using a special measuring scoop or a spoon. The coffee is taken from the packet and placed in the coffee-maker filter in the amounts required. For example ten scoops for twelve cups of coffee. Each operation involves filling the scoop inside the packet, checking the level, bringing the scoop over to the coffee-maker and tipping the coffee into the filter. As the packets are taller than the scoops, the consumer has to put his fingers in the packet. The packets are black and visibility inside is poor, so this old-fashioned method of measurement is inaccurate, time-consuming, tedious, and messy involving spillage of coffee and loss of aroma.


Apparatus and methods to receive and display digital television signals are described. In one embodiment, an apparatus to receive digital television signals comprises an antenna assembly coupled to the signal processing circuitry and comprising a first antenna positioned to maximize reception in a first direction and a second antenna positioned to maximize reception in a second direction, different from the first direction, and a processor coupled to the antenna assembly and comprising a selection logic module to select an antenna to receive a digital television signal for a specific channel, and a tuning logic module to configure the antenna assembly to receive a signal via a selected antenna.

The subject matter described herein relates generally to the field of electronic communication and more particularly to digital television signal reception.
In some environments, digital television signals may be broadcast for reception with appropriate receiving equipment. Digital television signals are subject to multipath effects, particularly in urban environments and in buildings. Receiving equipment should compensate for multipath effects.

System and apparatus for receiving digital television signals


A battery pack has a housing with a plug portion mateably receivable in a socket of a battery-powered power hand tool on which the battery back is designed to be mounted. The battery pack also has a connector cable with a connector plug at its distal end mateably receivable in the tool socket so that the battery pack can be disposed remotely from the tool. The battery pack can be mounted on tools with which it does not mate by use of an adapter having a plug portion mateably receivable in the tool socket, and an adapter socket mateably receiving the battery pack plug portion. Multiple battery packs may be interconnected on a wearable carrier and connected to the tool by a cable with a plug connector.

This application relates to power tools and, particularly, electrically powered tools. The application relates in particular to battery-powered power tools and battery packs for powering same.
Various types of power hand tools have been utilized for many years, including both electrically powered tools and pneumatically powered tools. Originally, such tools had to be connected by an electrical cable or a pneumatic hose to a source of electricity, typically AC, or a source of compressed air or the like. This limited the usefulness of the tools to the length of the cable or hose connecting the tool to the power source.
Accordingly, cordless electric tools have been provided for a number of years. Such tools typically include a DC electric motor powered by a battery, which is typically embodied in a battery pack which may be either built into the power tool or embodied in a portable battery pack which may be removably attached to the power tool. The size of such battery packs is necessarily limited, otherwise the power tool will become too heavy and/or unwieldy for convenient use. Thus, the power delivery capacity and running time of such cordless power tools is necessarily limited.
This application discloses an improved battery-powered power tool and battery pack therefor which avoid the disadvantages of prior battery-powered tools, while affording additional structural and operating advantages.
An important feature is the provision of a power tool and a battery pack therefor which can be positioned remotely from the tool being powered.
In connection with the foregoing feature, another feature is the provision of a battery-powered tool of the type set forth, wherein the battery pack can be disposed either on the tool or remotely therefrom.
Another feature is the provision of a battery-powered tool which can have large power delivery capacity and/or running time while maintaining an ergonomic design characterized by relatively small size and light weight.
Still another feature is the provision of a remote battery pack which is usable with existing battery-powered power tools without modification of the tools.
In connection with the foregoing feature, another feature is the provision of an adapter for use with an existing battery-powered power tool to permit it to be powered by the remote battery pack in accordance with the present invention.

Power tool and convertible remote battery pack therefor


An optical disk apparatus is disclosed which includes a first printed circuit board, on which a first circuit pattern is formed; a rotor, on which an optical disk may be placed, and which is electrically connected with the first circuit pattern; a second printed circuit board, which is stacked adjacent to the rotor on a surface of the first printed circuit board, and on which a second circuit pattern is formed; a sensor unit, which is mounted on the second printed circuit board in electrical connection with the second circuit pattern, and which is configured to sense a rotation of the optical disk; and a support plate, which supports the first printed circuit board and the rotor. In this optical disk apparatus, a separate printed circuit board can be utilized to support the sensor unit, whereby manufacturing costs can be reduced and working efficiency can be improved.

1. Technical Field
The present invention relates to an optical disk apparatus.
2. Description of the Related Art
The optical disk has established itself as the industry standard for data storage in the areas of computers, videos, and music. The various types of optical disks include CD's, DVD's, and disks for various game systems, where a commercially produced optical disk typically holds recorded digital data on one side and a printed visual label on the other.
While in some cases, an optical disk is manufactured that is capable of storing data on both sides, in the majority of cases, the other side of a disk is reserved for printed texts, patterns, or images, with the optical disk data stored on just one side of the disk. The label printed on the non-data side of the optical disk may include text that describes the data stored on the disk, or may provide a decorative design function.
The labeling on the disk, for most consumers, is typically performed by printing a separate adhesive label and attaching the label onto the non-data side of the disk, or by writing by hand directly on the disk, or by writing by hand on an attached label.
However, with the development label printing technology, techniques have been presented for directly printing a label onto the non-data side of the disk, using the laser of the optical disk drive.
FIG. 1 is a perspective view of an optical disk apparatus according to the related art, and FIG. 2 is a magnified perspective view of the holder in the optical disk apparatus shown in FIG. 1.
As illustrated in FIGS. 1 and 2, with the application of Light Scribe technology to the optical disk drive (ODD) for label printing, there has appeared a need to install a Light Scribe sensor (L/S sensor) 50, as a critical component, on the motor or the deck to control rotation.
For this, in the optical disk apparatus according to the related art, a socket type holder 40 is employed that is fabricated by a separate molding process. However, the method of using such socket type holder 40 requires solder terminals 42, not to mention the holder 40 itself, so that material costs may be increased and production efficiency may be decreased.


A cup washing machine includes a first transmission shaft and a second transmission shaft respectively coupled to a motor drive by a set of gears, a third transmission shaft eccentrically coupled to the second transmission shaft, a first cylinder brush and a second cylinder brush respectively coupled to the first and third transmission shafts, a toothed lock block controlled by a lock control knob to lock the third transmission in a desired angular position for permitting the pitch between the first and second cylinder brushes to be adjustably set. A detergent dispensing can with a dispensing tube is mounted on the housing of the machine and controlled to disperse detergent to the cylinder brushes for cleaning cups.

The present invention relates to a cup washing machines, and more specifically the present invention relates to such a cup washing machine which can be conveniently adjusted to change the pitch between two cylinder brushes according to the size of the cup to be washed.
Various fully automatic dish washing machines have been disclosed for cleaning dishes, cups, and the like, and have appeared on the market. However, these fully automatic dish washing machines are expensive. There is also disclosed a vertical cup washing apparatus, as illustrated in FIG. 1, which is specifically designed for cleaning cups or like containers. This structure of cup washing apparatus is generally comprised of a plurality of cylinder brushes vertically mounted on the top of a base and driven by a belt drive. When in use, the cup washing apparatus should be placed in water within a washing-up sink. This structure of cup washing apparatus is heavy and inconvenient to deliver, and it needs a spacious washing-up sink to fit. Further, the problem of electric leakage may occur easily because it must be placed in water during its operation, and it is not sanitary to wash cups in standing water. FIG. 2 illustrates a horizontal cup washing apparatus which eliminates the disadvantages of the aforesaid vertical cup washing apparatus. This structure of horizontal cup washing apparatus is generally comprised of a motor, two transmission shafts coupled to the output shaft of the motor through a transmission gear, and two parallel cylinder brushes respectively coupled to the transmission shafts. When in use, the horizontal cup washing apparatus can be mounted on the casing of a water tap on a sink with the cylinder brushes suspended in the washing-up sink below the outlet pipe of the water tap. Different cylinder brushes may be alternatively used for cleaning cups of different sizes. However, this structure of horizontal cup washing apparatus is still not fully satisfactory in function. It is time consuming to replace different cylinder brushes according to different sizes of cups to be washed. Further, a detergent must be separately supplied while washing.

No. 7, 39th Str., Lane 399, Sec. 3, Chungshan Rd.


In a reflection type liquid crystal display device having a front light and a reflection type liquid crystal panel including a reflection electrode of uneven structure, average tilt angles of the uneven structure of the reflection electrode are changed to form a high directivity reflective region having a characteristic reflecting an incident light from the front light in a vertical direction and a wide viewing angle reflective region having a characteristic reflecting an outside light incident slantingly from the front in a vertical direction, thereby forming the high directivity reflective region and the wide viewing angle reflective region to be mixed in the reflection electrode in the same display device.

1. Field of the Invention
The present invention relates to a reflection type liquid crystal display device. More specifically, the present invention relates to a reflection type liquid crystal display device having a front light.
2. Description of the Related Art
Reflection type liquid crystal display devices are suitable for low power consumption since their back light need not be illuminated at all times. They are employed for cellular phones and portable information terminal devices so called PDA (Personal Digital Assistant).
The reflection type liquid crystal display devices use mainly a light from an outside light for display. In many cases, they have an auxiliary light source called a front light by assuming their use under an environment in which an outside light cannot be expected. The basic construction of a reflection type liquid crystal display device with a front light will be described below.
FIG. 10 and FIG. 11 show the constructions of a reflection type liquid crystal panel and a front light of a prior art. A reflection type liquid crystal panel 17 has a liquid crystal layer 173 interposed between a pixel substrate 171 having a reflection pixel electrode and a color filter substrate 172.
As shown in FIG. 10, a front light 16 is arranged at the frontward side (observer's side) of the reflection type liquid crystal panel 17, and has a function of allowing a light from a light source part 18 to be incident onto the reflection type liquid crystal panel 17 to pass the light reflected in the inner part of the reflection type liquid crystal panel 17 through the observer's side.
As shown in FIG. 11, the reflection type liquid crystal panel 17 has a reflection electrode 1 of uneven structure for reflecting a light onto a TFT substrate, and forms one pixel 19 by three display devices 2 corresponding to red, green, and blue colors (R, G, and B) for color display. A method for forming a random uneven pattern in one display device 2 or one pixel 19 as a basic unit is typical.
FIG. 12 is a diagram showing change in brightness of an emitted light from the front light 16 to observation angles. As seen from the drawing, to obtain bright display at illuminating the front light, the light is emitted in a direction almost vertical to the reflection type liquid crystal panel 17.
FIG. 13 shows the characteristic of a reflector of the prior art. It shows light-receptive angle dependence of reflectivity to a parallel incident light having an incident angle of 30°.
As shown in FIG. 13(a), the reflection type liquid crystal display device is often used outdoors. In this case, an outside light such as a sunlight or fluorescent lamp is used to see display of the liquid crystal panel.
The brightness is highest at the regular reflection position of the outside light. Since the image of the outside light is observed, the display of the liquid crystal panel is hard to see. The reflector of the prior art has been designed so as to obtain bright display at an angle shifted several tens of degrees from the regular reflection position (30°) of the outside light, as indicated by the arrow in FIG. 13(a).
In the reflection type liquid crystal panel having a front light, as shown in FIG. 13(b), such a reflector is proposed to emphasize the effective use of a light from the front light.
A white-color light-emitting diode is often employed as a substitute for a cold-cathode tube in view of low power consumption and low noise. Since the light-emitting diode has a smaller input power compared to that of the cold-cathode tube, it is hard to obtain a brightness higher than that of the cold-cathode tube.
Specifically, to obtain high brightness at illuminating the front light, the flat part of the reflector is increased to make a regular reflection component larger.
As a result, as shown in FIG. 13(b), bright display can be obtained at an angle near the regular reflection.
The prior art reflection type liquid crystal device having a front light, however, has a reflective characteristic in which a viewing angle is narrow although high brightness can be obtained at illuminating the front light. A bright display cannot be obtained with outside light when not illuminating the front light.
Light usage, in an optical system, is different for outside light than for a front light. Thus, a prior art reflection type liquid crystal device having a front light has difficulty obtaining a bright display under both the environments.


An object photographer and corresponding method are disclosed that enable the capturing images of an object for later electronic stitching. The photographer has an object stand, which rotates the object to be photographed, and a camera frame, which supports a camera to swing through an arc around the object. To facilitate stitching, the height of the object stand is adjustable so that the object coincides with an axis of rotation of the camera frame. Further, the camera is preferably mounted on an adjustable bracket to enable adjustments in the height of the camera relative to the camera frame. At least one counter weight mechanism is preferably used to balance the camera frame for smooth pivoting motion.

Virtual reality computer applications seek to mimic the sensory experience associated with moving through three dimensional space using only a two dimensional display device. The process requires that displayed images be updated in response to the location or position of a viewer in a defined virtual space. Significant data processing capabilities are required to determine the appropriate displayed images, and large data storage capabilities are necessary to store the images for each potential view.
Although sometimes entirely fanciful, in many applications the displayed images are in whole or in part taken from real world scenes. This is common in applications in which the objective is education. For example, the viewer could be shown scenes from a Roman piazza in order to provide an understanding of day-to-day life in the city. Marketing or advertising applications also draw from this use, showing potential customers the marketed goods in an intended or showroom environment.
Panoramic images provide the continuous scenic backdrop in these applications. Usually these images extend continuously, entirely through 360.degree.. Available software allows discrete images to be converted into the continuous panorama. The process involves rotating a common chemical-film camera around its optical center or nodal point. During the rotation, a series of overlapping photographs are taken. Rotation about the optical center ensures that perspective does not change from photograph to photograph. Thus, common portions of the panorama in successive photographs should perfectly match-up. U.S. patent application No. 08/577,292, filed on Dec. 22, 1995 by the present inventor, which is incorporated herein in its entirety by this reference, discloses a "Panoramic Indexing Camera Mount" that facilitates the photography process.
Once taken, the photographs are developed and digitized, then scanned into a computer. There, the stitching software aligns successive photographs and removes any visible seams, thus creating a continuous panoramic image.
Foreground images in virtual reality applications are constructed by a different but related process. Whereas the panorama is represented by a sphere or ring of inwardly displayed images that surround the viewer's virtual space location, foreground images are represented by a sphere of outwardly directed images of objects. The viewer may move around the objects within the virtual space and virtually manipulate those objects.


A method, apparatus, and related beverage profiles for on-demand heating of liquid used for beverage dispensing where such heating is dynamically variable according to the applicable profile. The apparatus includes a heating unit, electronic controller, and sensing devices. A water tank supplies the heating unit via a water pump controlled by the controller that also controls the heating unit. Feedback control loops provide control data to the controller to optimize liquid temperatures for a given beverage type in accordance with predetermined profiles.

Within the self-service vending machine industry, many machines exist to prepare heated mixtures. Often, repetitive preparation of multiple, varied beverages and soups occurs using a single serve package from the same machine. Each single serve package is typically in the form of a capsule that contains a measured amount of a dry substance. One such capsule is shown by Denisart et al. within International Publication Number WO 03/059778 A2 published on Jul. 24, 2003.
When a liquid, typically hot water, is introduced to contents of a capsule, a food liquid such as a beverage or soup is thus formed. Different food liquids have different requirements to produce the best drinking experience depending upon the given food liquid. Such requirements include crema/foam volume, texture, and the in-cup temperature. Further, the in-cup temperature is related to the foam volume and texture.
Existing liquid heating technology used often in such self-service vending machines is typically only able to deliver hot liquid at one fixed temperature for all products. Most commonly, the heated liquid is water drawn from a public water main with or without filtration, but may also include water drawn from a private source such as a well or compact water tank. Heating water to a fixed temperature for all products limits the possibility to prepare different beverages each with the best quality. In addition, such self-service vending machines cool down during idle periods. Accordingly, the first dispensing of beverage prepared after a machine has been idle for a period of time would deliver beverages with a significant lower in-cup temperature due to the heat lost to the mixing device itself, or alternatively, the machine would require a significant warm-up time in order for the water to reach the desired in-cup temperature.
On-demand or instant heaters are known for the use in beverage systems. Such on-demand or instant heaters are generally defined as heating assemblies that are able to provide an accurate water temperature without requiring a pre-warming time. Such heaters generally include a series of heating components, such as electrical resistors or heating cartridges (e.g., Calrods®), where an initial heating component is controlled to heat the water within a preset temperature range lower than the final preset temperature desired and a second heating component is controlled to adjust, or fine tune, the water to a final preset temperature from the first preset temperature. There exists other sorts of instant heaters which are not based on Calrods® or ceramic insulated type heating elements, but rather on thick film technology. Such heaters may be formed by a hollow annular member with thick film type resistors printed thereon as shown by U.S. Pat. No. 6,459,854 issued to Yoakim et al. on Oct. 1, 2002 or as shown by Boussemart et al. within International Publication Number WO 2004/006742 published Jan. 22, 2004.
It would accordingly be desirable to provide a system for dispensing food liquids that overcomes difficulties associated with existing self-service vending machines. It is, therefore, desirable to provide an improved beverage dispensing system that would benefit from incorporation of an on-demand heater that is able to deliver hot liquid/water at any temperature and ideally vary such temperature dynamically. What would be needed is an improved beverage dispensing system optimized for delivering improved crema/foam and in-cup temperature, in terms of efficient dissolution of the powder/liquid, creation of foam inside the capsule, and compensation for the heat loss during the beverage flowing into the cup.

Method and apparatus for optimizing variable liquid temperatures


A fan clutch for a vehicle may include a shaft rotated by a drive force and having a first oil line formed in the shaft in a radial direction thereof, a rotor rotated in combination with the shaft, wherein the rotor includes an oil storage chamber formed in the rotor and the oil storage chamber communicates with the first oil line, a valve formed in an end of the oil storage chamber and being selectively opened, wherein the valve may be configured to allow oil stored in the oil storage chamber to flow to an outside of the rotor through the first oil line, and a housing formed to surround the rotor, and provided with a second oil line through which the oil that has flowed through the valve flows to the first oil line through an actuation chamber surrounding the rotor.

1. Field of the Invention
The present invention relates, in general, to a fan clutch for a vehicle and, more particularly, to a fan clutch for a vehicle which can minimize the amount of oil that has been supplied into an actuation chamber before an engine is started, thereby improving both the cold start performance and the acceleration performance of the vehicle.
2. Description of Related Art
Typically, a cooling fan is a device that is installed in an engine compartment of a vehicle and functions to improve the cooling efficiency of cooling water charged in a radiator, thereby allowing the cooling water circulating in the engine to be maintained at a constant temperature.
The cooling fans for vehicles are typically classified into automatic fan type devices and mechanical fan clutch type devices. Of the related art cooling fans, the mechanical fan clutch type device is configured such that it responds to the temperature of the cooling water charged in the radiator, and drives a cooling fan only when the temperature of the cooling water is higher than a predetermined temperature.
FIG. 1 is a sectional view illustrating the construction of a conventional liquid fan clutch for a vehicle.
As shown in FIG. 1, the conventional fan clutch includes: a fan housing 10 that is formed by assembling left and right housing parts into a single body, and a rotor 40 that is installed in the inner space of the fan housing 10 such that the rotor 40 can be rotated. The rotor 40 is connected to a rotating shaft 20 such that the rotor 40 can be rotated by the drive force of an engine which is transmitted from an engine crankshaft (not shown).
Here, a bearing 30 is set between the fan housing 10 and rotating shaft 20, so, when the rotating shaft 20 is being rotated, the fan housing 10 is not rotated by the rotating force of the rotating shaft 20.
The inner space of the fan housing 10 is divided into an oil storage chamber S and an actuation chamber D by a partition plate 50. In the fan housing 10, oil is stored in the oil storage chamber S, and the rotor 40 is installed in the actuation chamber D. Further, an oil supply valve 60 is installed on a side surface of the partition plate 50, and functions to feed oil from the oil storage chamber S to the actuation chamber D. In FIG. 1, the reference numeral 61 denotes a pulley, and the reference numeral 70 denotes an oil line.
Due to the above-mentioned construction, when the rotating shaft 20 is rotated, the rotor 40 is rotated in the actuation chamber D of the fan housing 10. In the above state, the oil supply valve 60 is opened and feeds oil from the oil storage chamber S to the actuation chamber D, so a viscosity resistance is produced in the actuation chamber D by the oil, and this causes the fan housing 10 to be rotated along with the rotor 40. Here, the rotating speed of the fan housing 10 is increased in proportion to an increase in the viscosity resistance that is produced in the actuation chamber D by the oil, in which the increase in the viscosity resistance is in proportion to an increase in the amount of oil charged in the actuation chamber D, and reduces the slipping of the fan housing 10 relative to the rotating rotor 40.
However, in the related art technique, before starting the vehicle, oil that has been stored in the oil storage chamber flows from the oil storage chamber into the actuation chamber through a return line due to gravity.
Accordingly, the related art technique is problematic in that, when starting the vehicle in the above-mentioned state, both the rotor and the fan housing are rotated at the same time due to the viscosity resistance of oil that has been introduced into the actuation chamber, so a shearing force is generated in the fan clutch and the load imposed on a starter is increased when the vehicle is started.
Further, due to the above-mentioned problem, the cooling fan is not separated from the fan clutch when initially starting the vehicle, and the rpm of the cooling fan is increased following an increase in the engine rpm, so the acceleration performance of the vehicle is reduced.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.