The present invention relates to cables made of twisted conductor pairs. More specifically, the present invention relates to twisted pair communication cables for high-speed data communications applications. A twisted pair including at least two conductors extends along a generally longitudinal axis, with an insulation surrounding each of the conductors. The conductors are twisted generally longitudinally along the axis. A cable includes at least two twisted pairs and a filler. At least two of the cables are positioned along generally parallel axes for at least a predefined distance. The cables are configured to efficiently and accurately propagate high-speed data signals by, among other functions, limiting at least a subset of the following: impedance deviations, signal attenuation, and alien crosstalk along the predefined distance.

The present invention relates to cables made of twisted conductor pairs. More specifically, the present invention relates to twisted pair cables for high-speed data communications applications.
With the widespread and growing use of computers in communications applications, the ensuing volumes of data traffic have accentuated the need for communications networks to transmit the data at higher speeds. Moreover, advancements in technology have contributed to the design and deployment of high-speed communications devices that are capable of communicating the data at speeds greater than the speeds at which conventional data cables can propagate the data. Consequently, the data cables of typical communications networks, such as local area network (LAN) communities, limit the speed of data flow between communications devices.
In order to propagate data between the communications devices, many communications networks utilize conventional cables that include twisted conductor pairs (also referred to as "twisted pairs" or "pairs"). A typical twisted pair includes two insulated conductors twisted together along a longitudinal axis.
The twisted pair cables must meet specific standards of performance in order to efficiently and accurately transmit the data between the communication devices. If cables do not at least satisfy these standards, the integrity of their signals is jeopardized. Industry standards govern the physical dimensions, the performance, and the safety of the cables. For example, in the United States, the Electronic Industries Association/Telecommunications Industry Association (EIA/TIA) provides standards regarding the performance specifications of data cables. Several foreign countries have also adopted these or similar standards.
According to the adopted standards, the performance of twisted pair cables is evaluated using several parameters, including dimensional properties, interoperability, impedance, attenuation, and crosstalk. The standards require that the cables perform within certain parameter boundaries. For instance, a maximum average outer cable diameter of 0.250″ is specified for many twisted pair cable types. The standards also require that the cables perform within certain electrical boundaries. The range of the parameter boundaries varies depending on the attributes of the signal to be propagated over the cable. In general, as the speed of a data signal increases, the signal becomes more sensitive to undesirable influences from the cable, such as the effects of impedance, attenuation, and crosstalk. Therefore, high-speed signals require better cable performance in order to maintain adequate signal integrity.
A discussion of impedance, attenuation, and crosstalk will help illustrate the limitations of conventional cables. The first listed parameter, impedance, is a unit of measure, expressed in Ohms, of the total opposition offered to the flow of an electrical signal. Resistance, capacitance, and inductance each contribute to the impedance of a cable's twisted pairs. Theoretically, the impedance of the twisted pair is directly proportional to the inductance from conductor effects and inversely proportional to the capacitance from insulator effects.
Impedance is also defined as the best "path" for data to traverse. For instance, if a signal is being transmitted at an impedance of 100 Ohms, it is important that the cabling over which it propagates also possess an impedance of 100 Ohms. Any deviation from this impedance match at any point along the cable will result in reflection of part of the transmitted signal back towards the transmission end of the cable, thereby degrading the transmitted signal. This degradation due to signal reflection is known as return loss.
Impedance deviations occur for many reasons. For example, the impedance of the twisted pair is influenced by the physical and electrical attributes of the twisted pair, including: the dielectric properties of the materials proximate to each conductor; the diameter of the conductor; the diameter of the insulation material around the conductor; the distance between the conductors; the relationships between the twisted pairs; the twisted pair lay lengths (distance to complete one twist cycle); the overall cable lay length; and the tightness of the jacket surrounding the twisted pairs.
Because the above-listed attributes of the twisted pair can easily vary over its length, the impedance of the twisted pair may deviate over the length of the pair. At any point where there is a change in the physical attributes of the twisted pair, a deviation in impedance occurs. For example, an impedance deviation will result from a simple increase in the distance between the conductors of the twisted pair. At the point of increased distance between the twisted pairs, the impedance will increase because impedance is known to be directly proportional to the distance between the conductors of the twisted pair.
Greater variations in impedance will result in worse signal degradation. Therefore, the allowable impedance variation over the length of a cable is typically standardized. In particular, the EIA/TIA standards for cable performance require that the impedance of a cable vary only within a limited range of values. Typically, these ranges have allowed for substantial variations in impedance because the integrity of traditional data signals has been maintained over these ranges. However, the same ranges of impedance variations jeopardize the integrity of high-speed signals because the undesirable effects of the impedance variations are accentuated when higher speed signals are transmitted. Therefore, accurate and efficient transmissions of high-speed signals, such as signals with aggregate speeds approaching and surpassing 10 gigabits per second, benefit from stricter control of the impedance variations over the length of a cable. In particular, post-manufacture manipulations of a cable, such as twisting the cable, should not introduce significant impedance mismatches into the cable.
The second listed parameter useful for evaluating cable performance is attenuation. Attenuation represents signal loss as an electrical signal propagates along a conductor length. A signal, if attenuated too much, becomes unrecognizable to a receiving device. To make sure this doesn't happen, standards committees have established limits on the amount of loss that is acceptable.
The attenuation of a signal depends on several factors, including: the dielectric constants of the materials surrounding the conductor; the impedance of the conductor; the frequency of the signal; the length of the conductor; and the diameter of the conductor. In order to help ensure acceptable attenuation levels, the adopted standards regulate some of these factors. For example, the EIA/TIA standards govern the allowable sizes of conductors for the twisted pairs.
The materials surrounding the conductors affect signal attenuation because materials with better dielectric properties (e.g., lower dielectric constants) tend to minimize signal loss. Accordingly, many conventional cables use materials such as polyethylene and fluorinated ethylene propylene (FEP) to insulate the conductors. These materials usually provide lower dielectric loss than other materials with higher dielectric constants, such as polyvinyl chloride (PVC). Further, some conventional cables have sought to reduce signal loss by maximizing the amount of air surrounding the twisted pairs. Because of its low dielectric constant (1.0), air is a good insulator against signal attenuation.
The material of the jacket also affects attenuation, especially when a cable does not contain internal shielding. Typical jacket materials used with conventional cables tend to have higher dielectric constants, which can contribute to greater signal loss. Consequently, many conventional cables use a "loose-tube" construction that helps distance the jacket from unshielded twisted pairs.
The third listed parameter that affects cable performance is crosstalk. Crosstalk represents signal degradation due to capacitive and inductive coupling between the twisted pairs. Each active twisted pair naturally produces electromagnetic fields (collectively "the fields" or "the interference fields") about its conductors. These fields are also known as electrical noise or interference because the fields can undesirably affect the signals being transmitted along other proximate conductors. The fields typically emanate outwardly from the source conductor over a finite distance. The strengths of the fields dissipate as the distances of the fields from the source conductor increase.
The interference fields produce a number of different types of crosstalk. Near-end crosstalk (NEXT) is a measure of signal coupling between the twisted pairs at positions near the transmitting end of the cable. At the other end of the cable, far-end crosstalk (FEXT) is a measure of signal coupling between the twisted pairs at a position near the receiving end of the cable. Powersum crosstalk represents a measure of signal coupling between all the sources of electrical noise within a cable entity that can potentially affect a signal, including multiple active twisted pairs. Alien crosstalk refers to a measure of signal coupling between the twisted pairs of different cables. In other words, a signal on a particular twisted pair of a first cable can be affected by alien crosstalk from the twisted pairs of a proximate second cable. Alien Power Sum Crosstalk (APSNEXT) represents a measure of signal coupling between all noise sources outside of a cable that can potentially affect a signal.
The physical characteristics of a cable's twisted pairs and their relationships to each other help determine the cable's ability to control the effects of crosstalk. More specifically, there are several factors known to influence crosstalk, including: the distance between the twisted pairs; the lay lengths of the twisted pairs; the types of materials used; the consistency of materials used; and the positioning of twisted pairs with dissimilar lay lengths in relation to each other. In regards to the distance between the twisted pairs of the cable, it is known that the effects of crosstalk within a cable decrease when the distance between twisted pairs is increased. Based on this knowledge, some conventional cables have sought to maximize the distance between each particular cable's twisted pairs.
In regards to the lay lengths of the twisted pairs, it is generally known that twisted pairs with similar lay lengths (i.e., parallel twisted pairs) are more susceptible to crosstalk than are non-parallel twisted pairs. This increased susceptibility to crosstalk exists because the interference fields produced by a first twisted pair are oriented in directions that readily influence other twisted pairs that are parallel to the first twisted pair. Based on this knowledge, many conventional cables have sought to reduce intra-cable crosstalk by utilizing non-parallel twisted pairs or by varying the lay lengths of the individual twisted pairs over their lengths.
It is also generally known that twisted pairs with long lay lengths (loose twist rates) are more prone to the effects of crosstalk than are twisted pairs with short lay lengths. Twisted pairs with shorter lay lengths orient their conductors at angles that are farther from parallel orientation than are the conductors of long lay length twisted pairs. The increased angular distance from a parallel orientation reduces the effects of crosstalk between the twisted pairs. Further, longer lay length twisted pairs cause more nesting to occur between pairs, creating a situation where distance between twisted pairs is reduced. This further degrades the ability of pairs to resist noise migration. Consequently, the long lay length twisted pairs are more susceptible to the effects of crosstalk, including alien crosstalk, than are the short lay length twisted pairs.
Based on this knowledge, some conventional cables have sought to reduce the effects of crosstalk between long lay length twisted pairs by positioning the long lay length pairs farthest apart within the jacket of the cable. For example, in a 4-pair cable, the two twisted pairs with the longer lay lengths would be positioned farthest apart (diagonally) from each other in order to maximize the distance between them.
With the above cable parameters in mind, many conventional cables have been designed to regulate the effects of impedance, attenuation, and crosstalk within individual cables by controlling some of the factors known to influence these performance parameters. Accordingly, conventional cables have attained levels of performance that are adequate only for the transmission of traditional data signals. However, with the deployment of emerging high-speed communications systems and devices, the shortcomings of conventional cables are quickly becoming apparent. The conventional cables are unable to accurately and efficiently propagate the high-speed data signals that can be used by the emerging communications devices. As mentioned above, the high-speed signals are more susceptible to signal degradation due to attenuation, impedance mismatches, and crosstalk, including alien crosstalk. Moreover, the high-speed signals naturally worsen the effects of crosstalk by producing stronger interference fields about the signal conductors.
Due to the strengthened interference fields generated at high data rates, the effects of alien crosstalk have become more significant to the transmission of high-speed data signals. While conventional cables could overlook the effects of alien crosstalk when transmitting traditional data signals, the techniques used to control crosstalk within the conventional cables do not provide adequate levels of isolation to protect from cable to cable alien crosstalk between the conductor pairs of high-speed signals. Moreover, some conventional cables have employed designs that actually work to increase the exposure of their twisted pairs to alien crosstalk. For example, typical star-filler cables often maintain the same cable diameter by reducing the thickness of their jackets and actually pushing their twisted pairs closer to the jacket surface, thereby worsening the effects of alien crosstalk by bringing the twisted pairs of proximate conventional cables closer together.
The effects of powersum crosstalk are also increased at higher data transmission rates. Traditional signals such as 10 megabits per second and 100 megabits per second Ethernet signals typically use only two twisted pairs for propagation over conventional cables. However, higher speed signals require increased bandwidth. Accordingly, high-speed signals, such as 1 gigabit per second and 10 gigabits per second Ethernet signals, are usually transmitted in full-duplex mode (2-way transmission over a twisted pair) over more than two twisted pairs, thereby increasing the number of sources of crosstalk. Consequently, conventional cables are not capable of overcoming the increased effects of powersum crosstalk that are produced by high-speed signals. More importantly, conventional cables cannot overcome the increases of cable to cable crosstalk (alien crosstalk), which crosstalk is increased substantially because all of the twisted pairs of adjacent cables are potentially active.
Similarly, other conventional techniques are ineffective when applied to high speed communications signals. For example, as mentioned above, some traditional data signals typically need only two twisted pairs for effective transmissions. In this situation, communications systems can usually predict the interference that one twisted pair's signal will inflict on the other twisted pair's signal. However, by using more twisted pairs for transmissions, complex high-speed data signals generate more sources of noise, the effects of which are less predictable. As a result, conventional methods used to cancel out the predictable effects of noise are no longer effective. In regards to alien crosstalk, predictability methods are especially ineffective because the signals of other cables are usually unknown or unpredictable. Moreover, trying to predict signals and their coupling effects on adjacent cables is impractical and difficult.
The increased effects of crosstalk due to high-speed signals pose serious problems to the integrity of the signals as they propagate along conventional cables. Specifically, the high-speed signals will be unacceptably attenuated and otherwise degraded by the effects of alien crosstalk because conventional cables traditionally focus on controlling intra-cable crosstalk and are not designed to adequately combat the effects of alien crosstalk produced by high-speed signal transmissions.
Conventional cables have used traditional techniques to reduce intra-cable crosstalk between twisted pairs. However, conventional cables have not applied those techniques to the alien crosstalk between adjacent cables. For one, conventional cables have been able to comply with specifications for slower traditional data signals without having to be concerned with controlling alien crosstalk. Further, suppressing alien crosstalk is more difficult than controlling intra-cable cross-talk because, unlike intra-cable crosstalk from known sources, alien crosstalk cannot be precisely measured or predicted. Alien crosstalk is difficult to measure because it typically comes from unknown sources at unpredictable intervals.
As a result, conventional cabling techniques have not been successfully used to control alien crosstalk. Moreover, many traditional techniques cannot be easily used to control alien crosstalk. For example, digital signal processing has been used to cancel out or compensate for effects of intra-cable crosstalk. However, because alien crosstalk is difficult to measure or predict, known digital signal processing techniques cannot be cost effectively applied. Thus, there exists an inability in conventional cables to control alien crosstalk.
In short, conventional cables cannot effectively and accurately transmit high-speed data signals. Specifically, the conventional cables do not provide adequate levels of protection and isolation from impedance mismatches, attenuation, and crosstalk. For example, the Institute of Electrical and Electronics Engineers (IEEE) estimates that in order to effectively transmit 10 Gigabit signals at 100 megahertz (MHz), a cable must provide at least 60 dB of isolation against noise sources outside of the cable, such as adjacent cables. However, conventional cables of twisted conductor pairs typically provide isolations well short of the 60 dB needed at a signal frequency of 100 MHz, usually around 32 dB. The cables radiate about nine times more noise than is specified for 10 Gigabit transmissions over a 100 meter cabling media. Consequently, conventional twisted pair cables cannot transmit the high-speed communications signals accurately or efficiently.
Although other types of cables have achieved over 60 dB of isolation at 100 MHz, these types of cables have shortcomings that make their use undesirable in many communications systems, such as LAN communities. A shielded twisted pair cable or a fiber optic cable may achieve adequate levels of isolation for high-speed signals, but these types of cables cost considerably more than unshielded twisted pairs. Unshielded systems typically enjoy significant cost savings, which savings increase the desirability of unshielded systems as a transmitting medium. Moreover, conventional unshielded twisted pair cables are already well-established in a substantial number of existing communications systems. It is desirable for unshielded twisted pair cables to communicate high-speed communication signals efficiently and accurately. Specifically, it is desirable for unshielded twisted pair cables to achieve performance parameters adequate for maintaining the integrity of high-speed data signals during efficient transmission over the cables.


A telecommunications network comprises a virtual transport server (VTS) for making network routing decisions and establishing call connections. Each VTS is interconnected to each signal transfer point in a common channel signaling (CCS) system associated with the network. Each VTS is also interconnected to at least one switch in a transmission network, such as an asynchronous transfer mode (ATM) switch. The VTS maintains routing tables identifying trunk groups associated with each central office switch in the network. During operation, an initial address message received from a signal transfer point in the VTS is processed and subsequently extended to an ATM switch so that a call connection can be established. Upon completion of the established call, the VTS releases resources associated with the ATM switch.

The existing public-switched telephone network (PSTN) comprises: a large number of central office switches for serving local subscriber lines and trunks; a smaller number of tandem (also referred to as "toll" or "transit" switches) for providing connections between central office switches; a plurality of analog and digital communication paths for interconnecting the central office switches and tandem switches; optional databases for storing information; and a common channel signaling (CCS) system for transmitting messages used by the switches to establish call connections. The CCS system includes many inter-connected signal transfer points (STPs) which relay messages among network nodes to establish, manage, and release call paths in the PSTN. To facilitate accurate message delivery, each PSTN switch is assigned a discrete "point code" for identification purposes.
Calls are routed by an "originating" central office switch (that is, the central office switch that serves the caller) to a "destination" central office switch (the central office switch that serves the called party) on the basis of the directory number received in the originating switch from the caller. In the United States, directory numbers are assigned in accordance with a numbering plan requiring each subscriber line to be identified by ten digits. The ten digit directory number comprises a three digit area code which defines a specific geographic region followed by a three digit office code which identifies a particular central office switch in the network. The office code is followed by a four digit subscriber line identifier which establishes the network address of a particular subscriber line on the central office switch associated with the office code digits.
In accordance with current protocol, a call is routed over a call path by the originating switch subsequent to CCS messages being relayed between the originating switch, other network nodes, and the destination switch. Particularly, an initial address message (IAM) is extended from the originating switch to the destination switch, either directly or via tandem switches, to establish trunk connections using a process well-known in the art. The call path between the originating switch and the destination switch is completed by a series of switch "hand-offs" of the call over the established trunk connections. In other words, the originating switch performs both routing (selecting a call path) and switching (establishing call connections on the selected call path) functions to connect a call to a desired called party upon receipt of a dialed directory number.
It is the dual role of determining routes and performing switching functions, however, that induces the inefficient operation of present-day telecommunications networks. This is because the determination of the call path is made by the originating switch and subsequently, any intermediate switches. A problem arises if unforeseen system blockages necessitate an alternate call path. In such cases, the call must be extended back to the originating switch from the node at which the blockage is detected so that the originating switch can devise a new call path. Return of the blocked call to its origination point causes undue delay and taxes network resources. Therefore, there is a need in the art to effectively and efficiently make routing determinations in a telecommunications network.

Method and arrangement for establishing call connections in a telecommunications network using a virtual transport server


In an ophthalmic apparatus for measuring an eye to be examined, an picture image photographed by a TV camera is processed by image processing circuit, and a position of alignment target image is detected so as to detect an alignment condition of measuring unit opposite to the eye to be examined. The suitability of the alignment condition is judged by a microcomputer, and when it is judged that the alignment condition is proper, a trigger signal is generated so as to start a measurement. Upon the measurement or after the measurement is completed, in case that the alignment condition is detected, the suitability of the alignment condition is judged, and it is judged that the alignment condition deviates from a predetermined allowable condition, a measured result which is obtained by a measurement performance is cancelled, or the measured result is corrected based on a detected result by an alignment detection. The apparatus continues the measurement by generating the trigger signal based on the suitable judged result of the alignment condition until the measured results of predetermined times are obtained, and when the measured results of predetermined times are obtained, a generation of trigger signal is stopped, so that it is monitored whether an alignment target image is not detected within a predetermined period. By this monitoring, when the target is not detected within the predetermined period, it is cancelled that the trigger signal is stopped generating.

1. Field of the Invention
The present invention relates to an ophthalmic apparatus, and more particularly to the ophthalmic apparatus for starting measurement by positioning the apparatus at a predetermined positional relation to an eye to be examined.
2. Description of Related Art
Regarding ophthalmic apparatuses such as an ophthalmic apparatus for measuring a refractive power of an eye to be examined or an ophthalmic apparatus for measuring a corneal curvature, after an alignment adjustment of measurement optical system of the apparatus to the eye is performed, a trigger signal for starting measurement is inputted so as to start measurement. Further, another apparatus has been proposed such as it provides a detecting mechanism for detecting an alignment condition, also measurement is to be started by automatically generating trigger signal when it is judged that an alignment condition is under a predetermined condition level.
Incidentally, another ophthalmic apparatus such as an ophthalmic apparatus for measuring a refractive power of an eye have a disadvantage that some alignment displacement can be caused during measurement, because it takes times to complete measurement after the trigger signal is generated, and therefore it may be possible that an apparatus will be shifted or the eye will be moved unexpectedly. In this case, such an obtained measured result tends to be improper. However, since there may be another case that an operator cannot realize that alignment displacement has been caused during measurement, it resulted in another disadvantage that some improper measured result were selected.
Generally, a plural measurements of the same eye are repeated in order to take process for obtaining its average value or central value as a measured result. Therefore, in case of an apparatus having means for automatically starting measurement, a continuous measurement has to be carried out until predetermined measurement times are achieved. Among these sort of ophthalmic apparatuses, it has been proposed that an apparatus comprises a TV monitor for observation to display which direction the apparatus should be shifted.
However, in case that such a continues measurement is performed for measurements of predetermined times, it may result in another disadvantage that a switch for separately starting measurement should be pressed, if it is necessary for the same eye to be measured once again after the continues measurement is completed. Although it has been set that measurement can be started automatically, the apparatus used to be necessary to equip with an optional switch for starting measurement. As a switch for starting measurement, the apparatus is generally equipped with a joystick in order to shift an apparatus opposite to an eye to be examined by the operator, but connecting of the joystick with electrical wire may cause some troubles such as break.
In addition, alignment adjustment has a following disadvantage. It had been much desirable to distinguish a direction indication that the apparatus should be moved by handling the joystick during alignment adjustment, especially for even operators who do not accustom himself to use an apparatus, the apparatus may be desirable to distinguish a directional indication that the apparatus should be shifted by handling the joystick.

Ophthalmic apparatus for measuring an eye to be examined


A game assembly utilizing sound identification as a method of determining the length of a player's move, wherein the player forfeits his turn if he fails to recognize the sound. A first player uses a keyboard to identify a randomly-generated sound, while a second player attempts to anticipate the random sound to be generated by moving panels over certain keys of the keyboard Additionally, the game assembly keyboard includes a processor which randomly appends the generated sound with a bonus sound, the player receiving an additional turn upon successful identification of the generated sound during such a bonus condition.

1. Field of the Invention
The present invention relates to a game assembly utilizing sound identification and, more particularly, to a game assembly wherein sound dictates various moves on a game board.
2. Description of Related Art
The toy field is generally cognizant of games that use prerecorded audible sounds, such as U.S. Pat. No. 3,169,768, wherein a sound is produced as a result of the insertion of a peg into a preselected opening in a game board.
U.S. Pat. No. 4,169,601 discloses a sound bingo game. U.S. Pat. No. 4,308,017 discusses a hand-held electronic learning aid utilized for teaching and testing association between pictorial representations and the correct responses to the pictorial representations. U.S. Pat. No. 4,572,513 teaches an educational game having prerecorded questions and answers. U.S. Pat. No. 4,703,573 relates to an audibly activated book. Finally, U.S. Pat. No. 4,884,974 discloses an interactive talking book and audio player assembly including a ROM module within which is stored digitally-recorded spoken texts corresponding to text printed on pages of the book.
The prior art is still seeking innovative play action in sound-activated game boards.

Game assembly utilizing sound identification for moves on a game board


A method of forming sidewall gates for vertical transistors includes depositing a gate dielectric layer over polysilicon channel structures, and depositing a gate polysilicon layer over the gate dielectric. The gate polysilicon layer is then etched back to form separated gate electrodes. Filler portions are then formed between gate electrodes, which are then etched from the top down while their sides are protected.

The subject matter of this application is the structure, use, and making of re-programmable non-volatile memory cell arrays, and, more specifically, to methods of making select transistors used in three-dimensional arrays of memory storage elements.
Re-programmable non-volatile mass data storage systems are widespread for storing data of computer files, camera pictures, and data generated by and/or used by other types of hosts. A popular form of flash memory is a card that is removably connected to the host through a connector. There are many different flash memory cards that are commercially available, examples being those sold under trademarks CompactFlash (CF), the MultiMediaCard (MMC), Secure Digital (SD), miniSD, microSD, Memory Stick, Memory Stick Micro, xD-Picture Card, SmartMedia and TransFlash. These cards have unique mechanical plugs and/or electrical interfaces according to their specifications, and plug into mating receptacles provided as part of or connected with the host.
Another form of nonvolatile memory systems in widespread use is the flash drive, which is a hand held memory system in a small elongated package that has a Universal Serial Bus (USB) plug for connecting with a host by plugging it into the host's USB receptacle.
In yet another form of nonvolatile memory system, a large amount of memory is permanently installed within host systems, such as within a notebook computer in place of the usual disk drive mass data storage system. Memory systems may contain their own memory controller and drivers but there are also some memory only systems that are instead controlled at least in part by software executed by the host to which the memory is connected. The memory is typically formed on one or more integrated circuit chips and the controller on another circuit chip. But in some memory systems that include the controller, especially those embedded within a host, the memory, controller and drivers are often formed on a single integrated circuit chip.
A type of re-programmable non-volatile memory cell uses variable resistance memory elements that may be set to either conductive or non-conductive states (or, alternately, low or high resistance states, respectively), and some additionally to partially conductive states and remain in that state until subsequently re-set to the initial condition. The variable resistance elements are individually connected between two orthogonally extending conductors (typically a bit line and a word line) where they cross each other in a two-dimensional array. The state of such an element is typically changed by proper voltages being placed on the intersecting conductors. These voltages are necessarily also applied to a large number of other unselected resistive elements because they are connected along the same conductors as the selected elements being programmed or read, diodes are commonly connected in series with the variable resistive elements in order to reduce leakage currents that can flow through them.
The desire to perform data reading and programming operations with a large number of memory cells in parallel results in reading or programming voltages being applied to a very large number of other memory cells along long conductors. This may require conductors (e.g. bit lines) to be supplied with significant current so that they can rapidly charge up to an appropriate voltage. Select transistors may be placed to supply current to selected conductors and to isolate unselected conductors. An example of an array of variable resistive memory elements and associated diodes is given in patent application publication no. US 2009/0001344 A1.


There is disclosed an impedance-heated furnace for processing a nonflowable but conveyable material at the processing temperature comprising a nonrotating shell having electrical-conducting properties, and heated to a processing temperature using electrical impedance as the heat source. The shell includes an inlet and an outlet and a conveyor means, which also may be heated by impedance, for transporting or carrying the material along or through the shell. The resulting solids and any generated or volatilized gases are recovered separately.

Furnaces, dryers, roasters, and other heat transfer devices have been used in the processing industries for many decades. Some of the more common furnace designs are rotary kilns, multiple-hearth roasters, and fluid-bed roasters. Direct heating for these furnace designs is common, but other processing devices also utilize indirect heat or energy transfer for heating the material being processed in the devices.
Heat transfer devices which circulate preheated liquids or vapors in an indirect heat transfer configuration typically comprise a jacketed trough into which single or multiple rotating shafts are inserted. Hollow paddles or screws are attached to the shafts and are the means of conveyance for the feed material through the furnace system. The paddles and screws may be intermeshed to facilitate self cleaning. Heat is transferred to the feed material by the introduction of a preheated medium into the jacket and rotating shaft(s) through a set of rotary joints on each end of the shaft. After passing through the system, the heating medium is returned to a heating device for reheating prior to its return to the heat transfer system. Heating limitations of the feed material in this type of heat transfer device depend on the temperature limitations of the heat transfer medium and the rotary joint seals (which deteriorate with excessive temperature) through which the medium passes. Practical limitations are currently in the 650 to 700 degrees Fahrenheit range.
A multiple-hearth roaster consists of a vertical, refractory-lined metal shell containing tiers or hearths mounted one above each other. Material movement is provided by rabble arms on each hearth attached to a central rotating shaft extending through the center of each hearth from the bottom to the top of the roaster. Material is moved by pitched teeth (material is moved toward the outside on one hearth and toward the center on the next lower hearth) attached to each rabble arm. Material enters the furnace at the top hearth and drops through a hole to the hearth below as the material is rabbled back and forth. Burners may be mounted on all or some of the hearths, and the combustion gas flow is generally from lower-to-upper hearths and countercurrent to the flow of the material being processed. Heat transfer is directly from contact between the combustion gases and the feed material. Disadvantages of a hearth furnace are excessive dusting as the processed material falls from hearth to hearth and large discharge gas volumes requiring treatment since generated process gases are combined with combustion gases.
A fluidized-bed roaster generally consists of a vertical, refractory-line metal shell with single or multiple hearths containing a suspension of the coarser fraction of the feed. In some cases where all process feed exits with the fluidizing gases, an inert bed material such as silica sand is added to the system to act as a heat sink. The fluidization of the coarse feed fraction or inert solids is provided by the flow of air, combustion gases, or other types of gases which enter a plenum chamber and pass upward through a constriction plate having a plurality of orifices and then into the fluidized bed. The fluidizing gases may be preheated, or the heat source may be the combustion of gaseous, liquid, or solid fuels in the bed; or electrical means; or by the exothermic nature of the feed. Material to be processed is injected into or above the fluid bed for direct-contact heat transfer. Processed material is removed from the roaster by overflowing from the lowest fluid bed through a conduit and sealed valves and also by the overhead dust collection system. When inert materials are used for bed material, they are recycled to the system. Major disadvantages of fluid bed roasters are high energy costs, the requirement to handle very large volumes of gases, and a limitation on feed material particle size which generally contain material smaller than one-quarter of an inch.
Rotary kilns are comprised of a horizontally-declined shell rotating on trunnions. Material movement through the shell is provided by rotation of the shell and the decline of the shell from feed to discharge end. Mechanical pitched lifters may also be attached to the inside of the shell to facilitate material movement and mixing. Kilns may be heated either directly or indirectly. Like other furnaces, rotary kilns are usually operated under slightly negative pressure to prevent the escape of process gases (those gases generated during thermal treatment) and particulates to the atmosphere. Direct-fired kilns can often contribute to the contamination of the material being processed because of the direct contact of the flame or combustion gases.
Heat to directly-heated kilns is provided by fuel combustion inside the shell or by the introduction of preheated gases from outside the shell. Burner firing may be in either a concurrent configuration (with the flow of the feed) or in a countercurrent configuration (against the flow of the feed). Combustion and generated process gases are combined when direct-firing configurations are used therefore greatly increasing the volume of gas (above the generated process gases) that require treatment for particulate and often acid-gas removal. Direct-fired kilns are usually refractory-lined to prevent metal shell erosion, heat loss from the system, and to protect the metal shell from over heating causing loss of structural integrity. Operating temperatures may range up to 2000 to 3000 degrees Fahrenheit depending on the refractory thickness, insulating ability, and the temperature of the outer shell.
Indirectly-heated kilns use burners fired to impinge a flame on the outside of the rotating shell. Combustion and process gases are kept separated during operation of an indirectly-fired kiln, and therefore, the process gases requiring subsequent treatment is significantly smaller than for a directly-fired kiln. Indirectly-heated kilns are usually internally unlined and employ insulated combustion chambers surrounding the outside of the shell to promote heat transfer to the kiln and processed material. Indirectly heated kilns generally operate at temperatures significantly lower than a directly fired kiln because of metal shell temperature limitations. Maximum operating temperatures typically do not exceed approximately 1000 to 1500 degrees Fahrenheit, depending on the shell material of construction.
For both types of kilns, fuel efficiency is quite low since the heat is either passing over the top of the material being treated in a direct-fired kiln or impinging on the outside of the shell during an indirect-fired application. Fuel efficiencies, without waste heat recovery devices, are usually in the 30- to 40-percent range.
Indirectly-heated kilns may also employ numerous resistance-type heaters surrounding the outside of, but not attached to, the rotating shell. For larger-size, rotary kiln-type systems heated in this manner, there is often uneven heating or cooling of the kiln's surface which may result in severe warping of the shell. Also, since the heating apparatus is not attached to (but surrounded by) the shell, energy transfer to the processed material inside the shell is still quite inefficient.
Regardless of the type of rotary kiln, a relatively complicated set of seals (single or double) or end plates is generally required on each end of the rotating shell. These seals or end plates, which are nonrotating and the same diameter as the rotating shell diameter, are particularly critical when it is essential to control the composition of the process gases or prevent the discharge of fugitive emissions to the atmosphere. Because the kiln operates under negative pressure, the seals are usually directly purged (or purged between the seals in the case of double seals that are separated from each other) with relatively large quantities of inert gas, such as nitrogen or steam, to prevent the ingress of air or other vapor into the system. These purge gases contaminate the internal process environment, and when combined with the process gases, significantly increase the total volume of the gases through the shell, therefore requiring increased sizing of down stream vapor-handling equipment.
Because the shell is constantly rotating, the use of instrumentation, such as internal temperature- and pressure-measuring devices, in long kilns is often difficult. The sensing probes are usually introduced through the fixed kiln end plates which limits the zones for taking measurements. Further, the tumbling action of the material being processed, caused by the rotation of the shell, often tends to create excessive dusting resulting in excessive particulate loading of the process vapors. This tumbling action also tends to promote material size segregation.
U.S. Pat. No. 4,931,610 to Hughes et al describes a kiln-type apparatus heated by induction. Alternating current energizing a conducting coil wound around, and insulated from, an internal rotating metal shell generates an alternating electromagnetic field that induces a current in the metal shell. Heat is then generated in the metal shell by electrical resistance of the metal. The shell is not connected directly to the power source, and the rotating shell still requires lip seals for containment of internal gases and exclusion of the outside atmosphere.
U.S. Pat. No. 5,144,108 to Passarotto describes a stationary, cylindrical-type apparatus for the conversion of massicot to litharge. The metal shell is surrounded by, and insulated from, a wound coil energized by an alternating current source similar to that described in the Hughes patent. Material is conveyed through the shell by paddles mounted on a rotating shaft extending the length of the shell. Heat is induced in the metal shell and not connected directly to the power source.
U.S. Pat. No. 4,039,794 to Kasper describes an induction-heated system for heating ferromagnetic abrasive shot in a rotating, cylinder-shape apparatus using lip seals for the exclusion of the external atmosphere from the interior of the cylinder. Also U.S. Pat. No. 3,961,150 to Lewis et al describes an induction-heated device for sterilizing sealed, electrically conductive containers.
Impedance heating of liquids and gases conveyed in pipelines has been used in four basic applications: namely, (1) applying heat to increase the fluidity of static, viscous materials so they can be pumped, particularly for oil transportation through pipelines; (2) maintaining temperature (offset heat loss) of transported liquids and gases flowing through a pipe and for freeze protection; (3) heating fluid liquids and gases passing through a pipe; and (4) heating fluid liquids stored in tanks. Representative examples of materials commonly transported through an impedance-heated line include crude oil, fuel oil, tar, paraffin, resin, sulfur, and chocolate, all of which are fluid and flowable at the elevated temperature of the line.
U.S. Pat. No. 3,777,117 to Othmer describes an impedance heating device suitable for heating fluid in long pipelines relying on the "skin effect" of the pipe's inner surface created by the alternating current. Location of the power cable and the use of internal fins inside the pipeline are used to more effectively transfer the heat to the fluid.
Additional impedance-heated devices disclosed in U.S. Pat. Nos. 3,632,975 and 4,578,564 to Ando and Takagi describe an improved impedance-heated pipe for heating fluids. The invention relates to a long heat-generating pipe utilizing the skin effect of alternating current having one or more impedance elements in the circuit in order to offset nonuniformity of current through the pipeline. U.S. Pat. No. 4,110,599 to Offermann describes a method of reducing the heat output of an impedance-heated pipe by making a segment of the pipe of a non-electrically-conducting or non-ferromagnetic material such as aluminum. U.S. Pat. No. 4,408,117 to Yurkanin describes a "skin effect" impedance heating system for tanks or vessels containing a liquid. A pipe (or several pipes) is inserted through the side of a tank wall, and the insulated power cable is run down the center of the pipe to produce the electromagnetic magnetic flux to generate the "skin effect" heating.
This invention has as its purpose to provide for a processing device or furnace for the thermal treatment of materials which are nonflowable at processing temperatures, while eliminating or overcoming many of the disadvantages or limitations of prior art devices.


Pilot fuel injected from fuel injection ports 21 of a pilot nozzle 2 bumps against an inner wall surface of a tapered portion of an inner circumference of a cone 41 of a pilot cone 4. At this time, the position where a pilot fuel from the fuel injection ports 21 hits is located in a range from a middle of the tapered portion of the inner circumference of a cone 41 to a downstream-side tip thereof.

In recent years, in order to reduce air pollution, at electric generation facilities utilizing gas turbines, it is demanded to reduce NOx which is included in exhaust gas thereof. NOx in a gas turbine is generated in a combustor which performs combustion behavior in order to rotate the gas turbine. Therefore, conventionally, in order to reduce NOx being generated in a combustor, is employed a combustor having main nozzles which perform combustion (premixed combustion) by mixing the fuel with the air.
By having the main nozzles perform premixed combustion, it is possible to reduce the amount of NOx being exhausted from the combustor. However, combustion state thereof is unstable, and combustion vibrations occur. Therefore, in order to restrain the aforementioned combustion vibrations so as to make the combustion state stable, such a combustor is employed as is further equipped with a pilot nozzle which diffuses and burns the fuel (diffusion combustion). FIG. 20 shows a schematic block diagram of a combustor being provided with a pilot nozzle and main nozzles as mentioned hereinabove.
As shown in FIG. 20, inside a combustor main body 1, a pilot nozzle 2 is inserted into the center thereof. At the same time, main nozzles 3 are inserted so as to be located around the pilot nozzle 2. Then, a pilot cone 4 is installed so as to cover the tip portion of the pilot nozzle 2. Additionally, main burners 5 are installed so as to cover the tip portions of the main nozzles 3. Moreover, pilot swirls 6 are installed around the tip portion of the pilot nozzle 2, and main swirls 7 are installed around the tip portions of the main nozzles 3, so that the pilot nozzle 2 and the main nozzles 3 will be supported.
In a combustor being constructed as mentioned hereinabove, the surrounding area of the tip portion of the pilot nozzle 2 is constructed as shown in FIG. 21. The outer circumference of the tip of the pilot nozzle 2 has a plurality of fuel injection ports 21 installed so as to diffuse and inject the fuel. The fuel which is to be injected by the pilot nozzle 2 will be referred as "pilot fuel" hereinafter. Additionally, the air which is to be supplied to the surrounding area of the pilot nozzle 2 by way of the comb ustor main body 1 ("pilot air") flows along the inner wall of the pilot cone 4 after passing through the pilot swirls 6. As a result, the pilot fuel being diffused and injected by the pilot nozzle 2 burns, forming diffusion flame (F); and furthermore, a part of the pilot fuel burns and at the same time, high temperature combustion gas from the pilot diffusion flame enters, forming a low-speed flame-stabilizing zone "X" which serves as a flame stabilizing point for the main remixed flame, thereby maintaining combustion.
Additionally, the fuel being injected from the main nozzles 3 ("main fuel") flows into the main burners 5 together with the air ("main air"), passing through the main swirls 7 and is mixed inside the main burners 5, thereby letting the main fuel and the main air being mixed by the main burners 5 flow out. When an air-fuel pre-mixture which is a mixture of the main air and the main fuel flows out from the main burners 5, the air-fuel pre-mixture is burned toward the inner wall of the combustor main body 1 from the downstream-side tips of the main burners 5, based on combustion in the low-speed flame-stabilizing zone "X." Herein, "downstream" means the downstream of the fuel and the air flows.
Moreover, as a conventional technology, in order to have a low-speed flame-stabilizing zone "X" formed easily in order to maintain combustion of the air-fuel pre-mixture from the main burners 5, as shown in FIG. 22, is provided a combustor, wherein a pilot cone 4 is formed to be in such a manner as the downstream-side tip thereof projects toward the main burners 5, serving as a pilot cone 4f By forming the pilot cone 4f in the above-mentioned manner, a low-speed flame-stabilizing zone "X" is formed in the vicinity of the downstream-side tip of the pilot cone 4f.
However, in a combustor being provided with a pilot nozzle 2 and main nozzles 3 as shown in FIG. 21, in order to maintain stability of combustion state thereof, flame-stabilizing effect being supplied by diffusion combustion of the pilot nozzle 2 is necessary. However, because the rate of production of NOx is high when combustion is performed by the pilot nozzle 2, it is necessary to restrain combustion by the pilot nozzle 2 in order to reduce NOx.
Consequently, NOx emission from a combustor is reduced by decreasing the ratio of the fuel being provided to the pilot nozzle versus the entire fuel being provided to the combustor ("pilot ratio"). However, as mentioned hereinabove, when the pilot ratio is low, the flame-stabilizing effect cannot be obtained from the pilot nozzle 2. As a result, combustion vibrations occur, making the combustion state unstable, thereby deteriorating energy efficiency of a gas turbine.
Additionally, stability of combustion can be achieved by forming a low-speed flame-stabilizing zone "X" as shown in FIG. 22. However, in order to promote reduction in NOx further, it is necessary to decrease pilot diffusion flame, but the current low-speed flame-stabilizing zone "X" is not large enough. In addition, because the downstream-side tip of the pilot cone 4f is formed so as to project toward the main burners 5, a stagnant area "Y" where the air-fuel pre-mixture flowing from the main burners 5 forms vortex is formed in the portion at the outlets of the main burners 5 where the pilot cone 4f projects. There is a concern that formation of a stagnant area "Y" might lead to generation of flashback.

Installation structure of pilot nozzle of combustor


An edge pixel is extracted from an input image by an edge determination section, an object image section is extracted by an object-image extraction section, and a first characteristic amount of the object image section in a first local pixel block containing a first target pixel is calculated by a first-characteristic-amount calculation section. A classification is made as to whether the first target pixel is a character edge pixel or a dot edge pixel by an edge-class determination section on the basis of the result of extraction for the edge pixel and the first characteristic amount. A second characteristic amount of a second local pixel block containing a second target pixel is calculated by a second-characteristic-amount calculation section on the basis of the edge classification result. The image of the second target pixel is classified by an image-class determination section on the basis of the second characteristic amount.

1. Field of the Invention
The invention relates to an image processing method for classifying which of a plurality of image areas each pixel belongs to, such as a character area, a dot area, and an on-dot character area, a program for executing the method, a recording medium in which the program is recorded, an image processing apparatus, and an image forming apparatus having the same.
2. Description of the Related Art
Related-art image forming apparatus read the overall image of an original with an image sensor that uses a charge coupled device (abbreviated as a CCD) and performs various processing to improve the reproducibility of the original during the formation of the image. For improving the reproducibility of the original, it is determined which of a plurality of image areas an image area containing a plurality of pixels in the whole image belongs to, on the basis of an image signal representing the entire image of the original; thus, various image areas such as a character area, a dot area, and a photograph area are extracted on the basis of the result of determination.
As a method for classifying a plurality of image areas, there are image classification methods by pattern matching and by using a character parameter. In the method of pattern matching, the entire image is divided into local pixel blocks containing a plurality of pixels, which are compared with a predetermined plurality of patterns, and thus the individual local pixel block is classified.
Specific examples with the character parameter are image classification methods disclosed in Japanese Unexamined Patent Publication JP-A 62-147860 (1987), Japanese Examined Patent Publication JP-B2 6-66884 (1994), and Japanese Unexamined Patent Publication JP-A 6-178097 (1994).
The image classification method disclosed in JP-A 62-147860 employs a halftone facsimile system. In the halftone facsimile system, a plurality of local pixel blocks contained in the entire image is subjected to an image-area classification processing. For a plurality of pixels in each local pixel block, the maximum pixel value and the minimum pixel value are obtained and the difference between the maximum pixel value and the minimum pixel value is calculated. The value of the difference calculated in each local pixel block is compared with a preset value, respectively. When the difference value is lower than the preset value, the local pixel block is classified as an image area containing a photograph section in which the value of the pixel varies gradually as it moves in a predetermined scanning direction. When the difference value is higher than the preset value, the local pixel block is classified as an image area containing a character section, the outline of a photograph section, or a dot photograph section in which the value of the pixel changes drastically as it moves in a predetermined scanning direction. Furthermore, for each local pixel block, the respective numbers of changes in the values of adjacent two pixels as it moves in a predetermined scanning direction and a sub scanning direction. The numbers of changes and a preset value are compared, wherein when the numbers of changes are larger than the preset value, the local pixel block is determined as a dot area containing a dot section, and when the numbers of changes are smaller than the preset value, the local pixel block is determined as being not a dot area. The pixels in the local pixel blocks are subjected to various processing on the basis of the result of classification.
The image classification method disclosed in JP-B2 6-66884 employs a dot-photograph-area classification method. In the dot-photograph-area classification method, the image-area classification is given to each of a plurality of local pixel blocks contained in the entire image. For the set of adjacent two pixels in one local pixel block, the numbers of changes of the value of adjacent two pixels are obtained individually in the case where the values of the two pixels continue in the main scanning direction and in the case where the values of the two pixels continue in the sub scanning direction, and the sum total of the numbers of changes is obtained. The sum total of the numbers of changes obtained for each local pixel block is compared with the preset value, and thus, the image area is classified on the basis of the result of comparison.
In the dot extracting apparatus disclosed in JP-A 6-178097, the number of pixels between two horizontal poles in the main scanning direction and the number of pixels between two vertical poles in the sub scanning direction are counted, respectively, and the counts are used as characteristic parameters, and thus, dot pixels contained in a dot area are extracted. For the main scanning direction, while setting either one of the maximum point at which the concentration rises to a maximum and the minimum point at which the concentration is reduced to a minimum as a horizontal pole, with digital multilevel data as input, the number of pixels between the two horizontal poles is counted. Also for the sub scanning direction, while setting either one of the maximum point at which the concentration becomes maximum and the minimum point at which the concentration becomes minimum as a vertical pole, two vertical poles are determined and the number of pixels between the two vertical poles is counted. When the number of the pixels between the horizontal poles is within a predetermined range, only pixels in which the number of pixels between the vertical poles is within a predetermined range among the pixels between the horizontal poles are extracted as dot pixels.
The image classification method by pattern matching requires a lot of patterns, thus posing a problem in that the capacity of a memory for storing a plurality of patterns must be increased and the general versatility is low.
In the image classification method using the characteristic parameter, the values of the characteristic parameters are not conforming, that is, the values of the characteristic parameters do not represent the respective characteristics of the image areas; therefore, the respective image areas cannot be accurately classified, so that pixels that belong to a desired image area cannot be extracted. For the dot area, a dot section having a small number of lines has a characteristic similar to the character section. Accordingly, it is difficult to discriminate the dot section from the character section, so that the dot section cannot be accurately extracted. An on-dot character area, in which the substrate in the character area is formed of a plurality of dot pixels, is not classified as a character area but is classified as a dot area, so that it is subjected to an optimum process for the dot area, for example, smoothing filter processing for reducing moire. Accordingly, the reproducibility of the character area is significantly damaged, so that the reproducibility of the on-dot character area is also reduced to form a low-quality image. For the dot photograph area in which a photographic image is formed of a plurality of dot pixels, an inter-area edge that is the boundary between a figure and the back in a dot photograph having a large of lines and dot pixels having a small number of lines are determined erroneously as a character area. Therefore, the reproducibility of the dot photograph area is damaged significantly, thus producing a problem of generating the degradation of image quality during the formation of an image.

Image processing apparatus, image processing method, program, recording medium, and image forming apparatus having the same


The present invention provides an encrypting device including an encryption unit and a communications unit. Paired encrypting devices allow for communication of trusted data between trusted devices over an untrusted network. Data received by the encryption unit is encrypted and provided with a connectionless header for delivery to the communications unit. Data received by the communications units is provided with a complex header for delivery to the paired encrypting device. The encrypting devices may be implemented in hardware or may be virtualized on a server or a plurality of servers. Arrangement of the encrypting devices in a hub-and-spoke topology allows for communication amongst a plurality of trusted devices. The encrypting devices can be used to convert commercially available equipment suitable for high assurance environments.

An important principle of high assurance systems is that the data in transit must remain secure against attacks from adversaries under all operating conditions. This is what is meant by "high assurance". In some instances, for example in the case of government national security systems, the time frame for maintaining confidentiality of the traffic is often decades. Maintaining confidentiality over this time period requires that the code protecting the data in transit runs only as expected; that the encryption key remains a secret; that the cryptographic algorithm and its implementation remain strong enough to resist cryptanalysis at the time the data was transmitted and future cryptanalysis utilizing future more powerful computer processing power; and the code must remain compatible with network technology that is constantly changing. Meeting these goals is challenging and dictates tradeoffs that often don't need to be considered in systems which do not require high assurance. This has created a high assurance community and has led to well-understood design and implementation choices for high assurance.
FIG. 1 illustrates the basic requirement of a high assurance system 10 where isolation is provided between a trusted environment 12 and untrusted environment 14 via a cryptographic trust boundary 16 provided by a cryptographic engine; i.e., no data from the trusted network must be able to leave the trusted network before entering the cryptographic engine (see arrow 20) and no data must be able to enter the trusted network without entering the cryptographic engine first (22). If data from the untrusted network enters the trusted network without first passing through the cryptographic engine or if data from the trusted network is provided to the untrusted network before passing through the cryptographic engine, these events are identified as breaches. Breaches can be accidental or intentional. A high assurance system requires the ability to thoroughly analyze all communications passing between the trusted and untrusted networks. A formal boundary is necessary to enable such a thorough analysis of the communications. A concrete boundary with explicit delineation between the trusted and untrusted network makes it easier to validate isolation between the trusted and untrusted networks and thus easier to certify the appropriate assurance level of a design or implementation. Conversely, the less defined a boundary is, the harder it is to validate a design or implementation at a high level of assurance.
Another important requirement of high assurance system is that before any information on the trusted network is compromised, the breach resulting in such compromise must only have occurred by overcoming multiple countermeasures. A system in which a single event can result in a breach of the trust boundary, the system does not meet the requirements of a high assurance system. As noted above, breaches may be induced intentionally or accidentally. For example, intentional breaches may occur when an adversary injects malicious data from either the trusted network or the untrusted network, or when an adversary places a probe on a bus where plain text data is traveling (before it enters the crypto engine). An accidental breach may occur when a critical circuit, such as for example, a randomizer fails on its own. A high assurance system requires additional protection built into the system to make single event faults ineffective. The cryptographic engine must also enforce the multiple-failure principle to protect the integrity of the algorithm implementation and the confidentiality of the cryptographic key. Generally speaking if a failure is detected, then the high assurance system must fail "closed"; i.e. the high assurance systems must fail in such a way that data is not allowed to enter or leave the trusted network. Meeting this type of fail-safe methodology can be challenging using normal commercial architectures because for practical reasons, they combine many functionalities within the same trust boundary. All of these functionalities aren't required for a particular application and they introduce millions of lines of code to the system. Thus, it is impossible to study all possible failure paths without also analyzing an entire large, complex system.
Generally speaking an adversary's attacks on the cryptographic engine fall in two categories 1) attacks on the cryptographic algorithm mathematically; or 2) attacks on the cryptographic engine itself and the key management. A typical attack on the engine might be to send malformed data at it to induce a fault that is poorly handled or was not considered by the system developer. This causes a leak of trusted data. In today's world, many of the publicly available cryptographic algorithms implemented are sufficient to defeat mathematical attacks on the cryptographic algorithm at high assurance levels (e.g. AES 256 bit). There is no general solution, however, to mitigate the second category of attacks. Thus, the challenge for high assurance evaluators, designers and implementers to confirm that a device defends against the cryptographic engine itself requires an understanding of the entire functionality of a device in order to predict (or test) where failures might occur and how they are prevented. The more complete the understanding is, the more likely a device will maintain data confidentiality/the trusted boundary. Most cryptographic implementations are non-trivial because the intended use cases aren't trivial. For example, a trivial system might be designed to use a single algorithm on a single link and intended for pre-vetted users. This is a very simple model to validate. As time progresses and it's re-implemented for other situations as more demands are applied (e.g. it must also handle un-vetted users and must handle multiple kinds of network interfaces and more algorithms), the accesses into and out of the overall system become difficult to fully understand as the features increase the complexity geometrically not linearly. The result is an increased accepted risk present over the lifetime of the device.
There are three general models of cryptographic engines 1) a software-based encryption model, 2) a dedicated hardware model and 3) a software-hardware hybrid model. The software model generally incudes cryptographic software running in a process on an operating system running on a conventional microprocessor (e.g. Windows on an x86-based computer using transport layer security (TLS) in a browser or networking with a VPN). The dedicated hardware model provides for the use of hardware (e.g. an ASIC or FPGA) with specific cryptographic functionality. The hybrid model provides very limited software performing a single, dedicated task on hardware such as a microcontroller (e.g. Arduino). The microcontroller runs a single program and does not include an operating system. Each cryptographic engine model has strengths and weaknesses.
A software-based encryption model 30 is illustrated in FIG. 2. The trusted environment 32 includes an operating system hosting any number of software address space components represented by 34a-c, 38a-c, 40, and 42. A number of software applications 34a-34c interacting with a number of devices 36a-36c in an untrusted environment. Interface drivers 38a-38c are provided for communicating with the untrusted devices 36a-36c. A VPN 40 controls access to the network stack 42 and serves as the cryptographic engine protecting the data in transit to the software applications 34 a-34c. The isolation between any software component is accomplished logically, not physically. The dashed lines within the operating system in FIG. 2 represent examples of the many feasible, implicit but unintended paths between the components. Effectively, every software component has at least an implicit path to every other software component. The VPN provides cryptographic isolation between the application 34a-34c and the untrusted network 36b. Because there are alternative paths to get to the applications, however, the VPN does not provide a robust and complete form of isolation unless all of the alternative paths can be accounted for. These unintended paths result from a failure in any of the software components to operate as intended and represent a potential unexpected path for attacker-influenced network packets to bypass the VPN and reach the trusted application address spaces. The requirement that the network packets be correctly processed by the extensive amount of software through all of these potential paths presents an impossible challenge for a device like FIG. 2 to achieve high assurance properties. If any of the paths between the untrusted network and the trusted network are not carefully constrained, the trust boundary will be breached. Because of the difficulty in constraining all of these paths, historically very few software-based systems have been successfully secured to high assurance.
A dedicated hardware model 50 is illustrated in FIG. 3. As illustrated in FIG. 3, the isolation between the trusted environment 54 and untrusted environment 56 is physically provided by microcontroller 52. The paths across the trusted boundary are conclusively analyzable and therefore can be the basis for a strong security implementation. The disadvantage of using a dedicated hardware model is that the functionality of microcontroller is not significantly flexible to function in a typical system. A further disadvantage is that a microcontroller does not have the horsepower to do high strength cryptography. Yet a further disadvantage is that in order to provide the necessary redundancy to be fail-safe, two microcontrollers are required.
A hybrid hardware-software model 60 is illustrated in FIG. 4 and provides the preferred model to be used for high assurance implementation. This hybrid model utilizes an FPGA 62 or an ASIC to provide physical isolation between the trusted and untrusted environments 63, 64. Unlike the dedicated hardware model, the FPGA/ASIC retains the programmability and therefore can be customized to perform specific operations. In addition, an FPGA/ASIC is powerful enough to do high strength cryptography. Custom built hardware such as an FPGA can allow one to claim complete knowledge of what went into the logic (and didn't) as it can be built from the ground up by trusted developers. In addition, the FPGA/ASIC logic can be designed to perform unique custom operations not typically available with a conventional CPU. As illustrated in FIG. 4, the FPGA layout can meet the fail-safe principle by forcing at least two failures. Modules A and C of the FPGA perform cryptographic functions that encrypt or decrypt data presented by the EUD or Network respectively. Module B is a comparator. The results from modules A and C are provided to module B for comparison. If the results compared by module B are equal, the data is allowed through the trusted boundary in the respective direction. This FPGA layout allows the cryptographic engine to meet the fail-safe principle because only two identical failures in modules A and C will result in a breach of the trusted boundary.
Typically, once a hardware implementation is certified, the hardware is built and supplied by a trusted supplier. Thus, a hardware implementation is less vulnerable than an otherwise secure software implementation of the same algorithm to a supply chain attack. At scale, it is just harder to maliciously change a custom chip than it is to change software. Hardware implementations are however non-trivial to implement. Implementing an algorithm for an FPGA or ASIC requires specialized skills and equipment and the chips must be physically integrated into an overall solution. In addition, updating a hardware implementation is difficult. In comparison, software implementations are not costly or difficult to implement. The manufacture or update of software only requires compilation of source code for a cryptographic application/library and the download and installation of the application. No soldering iron necessary. It is easier/cheaper/etc. to mold software-based encryption into a typical enterprise IT network versus a dedicated hardware model or a hybrid model. Ostensibly, an encrypted network packet is agnostic as to how it was created. If the adversary only has access to the encrypted packet (i.e. not access to the device that generated it), it is no more or less cryptographically strong if it was AES 256 bit encrypted by software or AES 256 bit encrypted by hardware. So software-based encryption is "good enough" for many commercial cases. The "value" of the data drives the adversary and the consequence of loss of the data determines the amount of effort that will be made to protect the data.
Obviously, loss or discovery of the key is a catastrophic failure. Thus, an additional cryptographic boundary is required to protect the confidentiality of the key. For example, while the key in use (thus exposed), it must be ensured that the key is not easily leaked/accessible by any other part of the system; or that the key can't be inferred by side channels, etc. A traditional hardware implementation like FIG. 4 illustrates a concrete boundary. In theory, module A and C are the only places in the entire system where the unwrapped key exists. Thus, only the paths to unwrap and place the key into A and C need to be analyzed to validate the integrity of the key is maintained.
Cryptographic systems typically implement a bypass in order to communicate in the clear across the trust boundary during some part of their lifecycle. For example, when initially negotiating cryptographic parameters between two anonymous parties (e.g. TLS) to establish a route to a new endpoint before beginning encryption; or to manage some aspect of the network on the untrusted side. Any bypass represents a breach potential and must be carefully validated. This adds to the design and validation costs required to achieve high assurance.
The overall cost of a high assurance system is a result of interplay between three distinct communities: vendors who propose a design and produce product; evaluators who validate that the design/product meets high assurance standards; and users who purchase the product. Vendors and evaluators are not typically the same entity and often do not share the same goal. However, the adversarial nature between the vendors and evaluators will produce a high assurance solution for the users.
Historically, producing a certified high-assurance implementation within this ecosystem is costly and lengthy. Vendors must create solutions from the ground up using complex, expensive technologies. Maintaining a high-assurance certification with the inevitable change in the IT ecosystem will force new certification. Evaluators must understand many of these unique implementations thoroughly in order to certify that the solution will survive the test of time. This does not scale well and it creates a perverse incentive to lock in yesterday's technology given the heavy lift needed to stay technologically current while being certified.
Key management is necessary as the number of devices grows in a system. Keys and certificates must be securely created, delivered, updated, revoked, and validated throughout the long time-frame that the system is operational. Creating the infrastructure required to manage keys securely is costly and operating the infrastructure adds sustainment costs for the users.
Given the high (sunk) cost of high assurance devices, users are reluctant to refresh them more frequently. This perpetuates a costly support tail for both the users and the vendors as the lifecycle goes out a few decades due to limited availability of parts and keeping personnel on the payroll. High assurance crypto gear is not disposable.
For all of the reasons described, high assurance cryptography remains hard to achieve for vendors, evaluators and users. Low cost, easy to use, sustainable, and high performance is difficult to accomplish in a single standalone package. Adding the size, weight and power (SWAP) requirements that a mobile use case demands makes this accomplishment even harder.
An example of a mobile use case in which high assurance is desired is a mobile phone. Stock commercial mobile devices fail as high assurance devices because the radios associated with the mobile phone is within the trusted boundary. Radios host and run an extensive amount of software (often millions of lines of C code), most of which has unknown provenance, all of which is directly accessible from the untrusted network, all of which has access to the rest of the device, and none of which has been seriously analyzed from a high-assurance failure point of view. The radio package is not under the control of the user. The radio's implementation is dictated by the device manufacturer, the radio chipset manufacturer and the network operator(s). It may or may not have a security feature. The radio's underlying implementation can be changed at any time, often remotely and outside of the user's awareness or control. The radio is highly privileged and has direct connectivity to many other modules on the phone. Even if a radio is physically separate, it will remain logically connected (thus trusted) to other parts of the platform to maintain low cost, flexibility and a good user experience. Furthermore, the addition of traditional FPGA encryption modules by the vendor to safely isolate the rest of the platform, where critical user data lives, from the toxic radio subsystem is undesirable because FPGA's are power hungry, large, and run hot. Any security benefit provided by a radio of a commercial-off-the-shelf (COTS) device is accidental. No piece of code of the size associated with a COTS radio in history has ever been immune from exploitation. Worse, any failure within the radio software can be leveraged to an immediate compromise of the whole device because the radio subsystem is a highly privileged trusted part of the platform that must work with other parts of the platform such as the power management subsystem, the application processor, etc. in order to deliver a competitive user experience.
SWAP dictates how COTS devices are built and how the supply chain of components are built. To get the best SWAP that market pressures dictate, mobile architectures strive to have the fewest additional parts, thus the least amount of separation possible, logical or physical. As the manufacturing technology improves, components are shrinking and condensing multiple functionalities into fewer chips to get more performance, to lower power and to shrink integration cost. If it takes x microseconds to copy data from one subsystem to another and for generation 1 of a device and only x-y microseconds to copy the data between those systems in a combined part, the device manufacturer will use the combined part for generation 2, thereby reducing the isolation between those 2 subsystems. As sub-systems condense into fewer parts, they become more invisible to an analysis by a third party (i.e. the evaluator/certification) while they continue to process the exact same data that was capable of exploiting an earlier version of the system. Even if they are using battle tested standards, mobile platforms have additional proprietary features in order to differentiate from competitors or to support multiple price points for the same underlying product. This makes careful evaluation of any COTS mobile platform unique and effectively impossible without the multiple vendor's involved in the supply chain providing proprietary information. This creates a perverse incentive that prevents a user from using new commodity devices for high assurance purposes. For example, when users want to exchange a high assurance device with a newer model/device, the new model high assurance device must be reevaluated in order to certify that the new model meets the high assurance requirements. Combined with the opacity of condensed functionality, and immense amount of software, a high assurance evaluation of a commercial platform does not scale. Market forces (speed, low SWAP, time to market, cost, differentiation, etc.) continue to prevent the commercial supply chain from achieving the necessary radio isolation to deliver a high assurance off-the-shelf mobile phone that can defend against an untrusted network.
FIG. 5 illustrates a prior art approach for adapting a conventional mobile phone 70 to achieve a high assurance. The trusted processor 72 handles conversion of the trusted device data from USB input 74 and the untrusted processor 76 handles the conversion of the network data from USB input 78. An FPGA module 80 encrypts or decrypts data as it passes between input 1 and input 2. Optionally, the trusted and/or the untrusted processor interface translation functions could be added to the FPGA module 80 and the processors 72, 76 removed as discrete parts. This would increase the code in the FPGA 80 and possibly the size of the part. Nonetheless, the trust boundary is enforced between the FPGA 80 and the untrusted processor 76, much like hybrid hardware-software model of FIG. 4. However, the FPGA 80 presents power and heat problems for small form factors such as a mobile phone. And FPGA's are complex to program. Thus, once the FPGA 80 has been programmed for use in the mobile phone, its functionality cannot be easily changed. A key is placed into the device using USB input 82. Adding the key to the device via this input 82 adds cost in two ways; key protection and port protection. First, the key must be protected during generation and delivery, and the mechanism for generation and delivery of the key must be unprotected when key is brought into the device. Protecting the mechanism for generation and delivery of the key requires a non-trivial amount of key management infrastructure to maintain. Further, additional code to unwrap the key is required. Key port protection also adds cost. Additional mechanisms inside the trust boundary must ensure the key fill port 82 cannot be used to attack the device 70 since the key fill port 82 is a connection directly to the trusted side of the device. The additional complexity needed to ensure protection of the key port increases the cost to evaluate high assurance of the device. As illustrated in FIG. 5, the device 70 includes a bypass between the trusted processor 72 and the untrusted processor 76. This bypass is required in order to configure the untrusted processor. As a result, the bypass path must be carefully inspected in order to certify that the device can achieve high assurance. Thus, there remains a need to find a solution that takes advantage of the commercially available products without inheriting the vulnerability that comes with commodity hardware and software.


A differential transformer type magnetic sensor includes a first coil layer, a second coil layer, and an insulating layer formed between the first coil layer and the second coil layer. The first coil layer includes a detection coil and a first drive coil. The second coil layer includes a reference coil and a second drive coil. The first drive coil and the second drive coil are electrically connected together so that a direction of drive current flowing in the first drive coil is the same as a direction of drive current flowing in the second drive coil. The detection coil and the reference coil are electrically connected together so that a direction of induced current flowing in the detection coil is reverse to a direction of induced current flowing in the reference coil.

The present disclosure relates to differential transformer type magnetic sensors and image forming apparatuses.
Image forming apparatuses using toner as developer exploit a magnetic sensor to detect the residual amount or density of the toner. Various types of magnetic sensors are proposed. A magnetic sensor of differential transformer type as one of the types has a configuration in which a drive coil, a detection coil, and a reference coil are arranged on the same core.
The use of planer coils as the coils can reduce the size of the differential transformer type magnetic sensor. As one example of the differential transformer type magnetic sensor using the planer coils, there has been proposed a sensor in which a first coil (drive coil), a second coil (reference coil), a third coil (detection coil), and a fourth coil (drive coil) are arranged in a first layer, a second layer, a third layer, and a fourth layer, respectively, and insulating substrates are disposed between the respective layers.

Differential transformer type magnetic sensor and image forming apparatus