Methods and apparatus for testing of Internet-Protocol packet network perimeter protection devices, e.g., Border Gateways such as Session Border Controllers, including 5 dynamic pinhole capable firewalls are discussed. Analysis and testing of these network perimeter protection devices is performed to evaluate the ability of such device to perform at carrier class levels. The efficiency of state look table functions as well as call signaling processing capacity, implemented in a particular perimeter protection device, are determined and evaluated. Proper performance and efficiency of such perimeter protection devices are evaluated as a function of incoming call rate and as a function of total pre-existing active calls. Various different network perimeter protection devices, e.g., of different types and/or from different manufactures, can be benchmarked for suitability to carrier class environments and comparatively evaluated. Test equipment devices, e.g., enhanced Integrated Intelligent End Points (IIEPs), for fault testing, 15 evaluating and stressing the network perimeter protection devices in a system environment are described. Typically these specialized test devices are used in pairs, one on each side of the firewall under test. These test equipment devices include a heavy duty traffic generator module, monitoring and analysis capability including a utilization analysis module, and a graphical output capability.

Some local telecommunications service providers have begun programs for the delivery of advanced voice and data services over IP that will require the implementation of security measures in order to protect both the service providing network assets as well as the customer networks from service affecting malicious intrusions that can cause either network losses or customer grievances. Additionally, the changing paradigm in the area of new services makes it beneficial for such a service provider to position itself ahead of its competitors by being the first to offer the new services afforded by the transformation from a switch based network to an IP based network. Common to both of these efforts are the challenges that are faced by a large size telecommunications service provider namely the impact on scalability and performance.
Security and performance are typically a zero sum game since improved security often results in reduced throughput and performance. This is the case in the area of perimeter protection of customer and network assets as well as in the development of new multimedia and multi-technology services for millions of customers. These challenges are manifested most tellingly in the deployment of a Softswitch infrastructure that will facilitate a telecommunication service provider achieving a position as "first to market" advanced services. Securing the Softswitch assets from potential attack by a malicious intruder is a vitally important component to consider in future IP based networks and services. A security failure in this realm can be extremely costly to the telecommunication service provider both in real economic terms as well as in reputation. The security capability, however, should be implemented in a scalable manner.
Interconnection of large-scale IP networks presents new twists to security challenges that can benefit from added perimeter protection measures. Distinct from traditional data, broadband, Voice over Internet Protocol (VoIP) and multimedia services are interactive, utilize separate signaling and transport flows, and place unique Quality of Service (QoS) and security requirements on the network that take into account users and policies derived from signaling and downstream network topology. Carrier-to-carrier VoIP peering, Hosed IP Centex and other multimedia packet-based services present new challenges for IP networks and edge networking technologies. These services are to be delivered between different IP network "islands" traversing borders between carrier and customer and carrier-to-carrier often between private and public networks. Carriers are confronted with deployment barriers such as security, service level assurance and Network Address Translation (NAT) traversal. Layer 3 and 5 (application) security enhancements are difficult to implement, either because of the inherent very-distributed nature of VoIP networks (many hops), or because they involve the use of digital certificate-based key systems which are notoriously difficult to manage, especially, at the carrier class scale of a network of a typical local service provider's size. An alternative is to protect crucial network assets such as the Softswitch infrastructure components, namely media gateways, signaling gateways, and application servers, through the use of network perimeter protection devices that will block potentially nefarious unwanted traffic from ever reaching those assets.
The network edge has evolved to be not only an access point but also a demarcation point and identifies the boundary of trust between the carrier's service network and its external customers and peers. The state of the art in VoIP security today is centered on the protection of these network "borders". These border devices, of necessity, need to implement firewall capabilities in both stateless and stateful modes thereby introducing new challenges for carrier class implementations, as stateful modes carry the burden of being extremely consumptive of CPU cycles for the devices performing the function.
In VoIP, the ports used to carry the media part of the call, are dynamically assigned through signaling, taken down upon call termination, and reused for a subsequent call at a later time. This technology is denominated "dynamic pinhole filtering" as firewalls need to filter traffic dynamically by opening/closing ports (pinholes) depending on the state and progress of a call. The correct implementation of this technology, at the network edge, provides indeed a good level of protection at a level of granularity not otherwise achievable with other current security technologies.
At least one local service provider is currently involved in major projects that should involve the eventual deployment of this stateful capability of "dynamic pinhole filtering". Value Added Data Security Services (VADSS) may include such things as stateful pinhole filtering and the provisioning of VADSS capabilities to customers from a network's edge and can be provided as a value-added revenue generating service. Another application could involve the large scale deployment of a Softswitch that will provide customers with hosted VoIP based services and advanced features. One of the possible devices considered for the security architecture of a Softswitch infrastructure is a Session Border Controller (SBC). Such SBCs would include, as an important component, the capability of stateful packet filtering for the media streams. These SBCs with stateful packet filtering would be used in place of conventional devices that perform Network Address Translation (NAT) techniques, but do not include a dynamic filtering capability.
A major issue of concern associated with the testing of this dynamic stateful filtering capability, for both of these potential services, is the verification of its performance at the rates demanded by a carrier class network, namely Gigabit-Ethernet (GigE) interfaces with typical concurrent sessions of the order of up to 100K or higher. It would be beneficial for service providers to develop the methodology and the integrated tools to perform testing of stateful capable "dynamic pinhole filtering" for evaluating functional operation and performance of firewalls at carrier class traffic levels.
Value Added Data Security Services will now be described. Value Added Data Security Services (VADSS) may be implemented as a suite of network-bases services that complement and add value to the basic capabilities of a local carrier's network-based IP-Virtual Private network (VPN) service and, represent a novel way of revenue generation. An exemplary VADSS service suite includes:                Virtualized firewall providing basic stateful firewall-customer-configurable rule sets for packet filtering, and full stateful firewall with dynamic pinhole filtering to protect customer assets from threats outside their network        Internet Offload—an Internet access capability directly from the IP/MPLS infrastructure; and        IPSec tunnel terminations
The ability of VADDS to provide security services and Internet access from within a provider network is what distinguishes VADSS from similar offerings that depend on managed Customer Premise Equipment (CPE). By leveraging the economies of scale of platforms capable of running multiple instances of such applications as firewalls, a local service provider can offer these virtualized services at the Service Edge Router level. Internet threats are kept at arm's length, away from the customer access link through network-based firewalls and address translation within the provider infrastructure. VADDS could include the provisioning of virtualized firewalls, each supporting a host of stateless protocols, as well as Application Layer Gateway capabilities for SIP, H.323, Skinny, and MGCP, at GigE rates and supporting 100K concurrent sessions.
Session Border Controllers for Softswitch Infrastructure will now be described. Existing edge functions such as aggregation, class based queuing and packet marking, address translation, security and admission control are insufficient to meet the requirements for the new Softswitch based VoIP services. In addition to these traditional edge functions, VoIP and multimedia services present new requirements on the network edge including QoS and bandwidth theft protection, inter-working of incompatible signaling networks, Lawful intercept, e.g., anonymous replication & forwarding of packets, and most significantly, the capability to perform stateful packet inspection, e.g., for voice streams, also called "dynamic packet filtering", at carrier-class rates. The service delivery network should be augmented with solutions that address these unique requirements. The existing edge router, complemented by a new class of product called a Session Border Controller (SBC), become the border element in the next generation network (NON) architecture.
Session Border Controllers are a new category of network equipment designed to complement existing IP infrastructures, to deliver critical control functions to enable high quality interactive communications across IP infrastructures, to deliver critical control functions to enable high quality interactive communications across IP network borders. A "session" is any real-time, interactive voice, video or multimedia communication using IP session signaling protocols such as SIP, H.323, MGCP or Megaco/H.248. The "border" is any IP-IP network border such as those between service provider and customer/subscriber, or between two service providers. "Control" functions minimally include security and service assurance. Security functions provide access control and topology hiding at layers 3 and 5. Service assurance functions guarantee session capacity and control.
Security and address preservation features include network access control based on stateful packet inspection, with firewall dynamic pinholes created only for authorized media flows, and network topology hiding at both layer 3 and 5 via double network address and port translations. SBCs additionally protect softswitch, gatekeeper, gateway, application server, media server and other service other service infrastructure equipment from Denial of Service (DoS) attacks and overload with rate limiting of both signaling messages and media flows. SBCs simultaneously support SIP, MGCP and H.323 networks by actively participating in session signaling and can be controlled by a third part, multi-protocol softswitch, H.323 gatekeeper or MGCP call agent using a pre-standard MIDCOM protocol. The Performance requirements for some typical SBCs in a carrier class environment typically range in the order of 5 Gig with 100K concurrent sessions.
Strict verification of the correctness of a security implementation through testing, however, is of paramount importance as any defective implementation could result in windows of vulnerability that could be exploited by a malicious intruder to invade the very assets being protected. In the realm of security, a faulty implementation of a security device is doubly dangerous, as unnoticed backdoors that can be used for malicious intent, will contribute to a false sense of security. These windows of vulnerability can in turn be used by a malicious attacker for a Denial of Service attack, in the simplest case, up to a takeover of network assets that can be used to control and disrupt other parts of the network. The penalty associated with this security capability, however, is a considerable degradation in performance. The consequence of this performance degradation can result in two equally unappealing outcomes: (i) excessively long windows of vulnerability; and (ii) a self-inflicted Denial of Service attack as the underperforming device shuts out subsequent calls.
In view of the above discussion there is a need to properly benchmark and verify the performance of various firewall security devices. Methods and apparatus that will permit a quantification of functionality and performance at carrier-class scales would be especially beneficial.

Methodology, measurements and analysis of performance and scalability of stateful border gateways


A touch input device includes a touch panel, a press detection signal generating unit and a touch detection signal generating unit. The touch panel is formed by laminating a piezoelectric sensor and a capacitive sensor. The piezoelectric sensor is connected to the press detection signal generating unit, and the capacitive sensor is connected to the touch detection signal generating unit. The piezoelectric sensor includes a piezoelectric film, and first and second press detecting conductors disposed with the piezoelectric film sandwiched therebetween. The piezoelectric film is disposed such that a polarity of electric charges produced by a press in the piezoelectric film, and a polarity of excited electric charges produced in the piezoelectric film when the capacitive sensor detects a touch become reverse polarities.

Conventionally, various touch input devices which each detect a touch position and a press on an operation surface have been devised. For example, Patent Literature 1 discloses a resistive touch panel. The touch panel in Patent Literature 1 includes a first conductive film and a second conductive film including principal surfaces parallel to an operation surface, and the first conductive film and the second conductive film are disposed at an interval in a direction orthogonal to the principal surfaces. When the operation surface is pushed, the first conductive film and the second conductive film contact with each other at a pushed position. The touch input device in Patent Literature 1 detects a touch position based on a partial pressure at this touched position, and detects a press based on the partial pressure and a resistance.
Such a configuration and an operation need a switch circuit which switches a touch position detection circuit and a press detection circuit to the first conductive film and the second conductive film to connect. Further, according to the configuration of Patent Literature 1, if a first electrode film and a second electrode film do not contact, i.e., if the operation surface is not pushed to some degree, it is not possible to detect a position.
Meanwhile, conventionally, a touch input device whose position detection sensor and press detection sensor are formed by using different base members, and which employs a configuration obtained by overlaying the position detection sensor and the press detection sensor has also been devised. According to this configuration, the position detection sensor is connected to a touch position detection circuit, and the press detection sensor is connected to a press detection circuit, and therefore a switch circuit is not necessary. Further, according to this configuration, it is possible to detect a position even when an operation surface is softly touched.
In this regard, by using a capacitive position detection sensor as the position detection sensor, it is possible to detect a touch position based on a change in a capacitance. Even when the operation surface is softly touched, i.e., even when the operation surface is not strongly pushed, it is possible to detect a touch position.
Further, while such a position detection sensor is used, a piezoelectric sensor for which a piezoelectric film is used is used as the press detection sensor in some cases.    PTL 1: Japanese Patent Application Laid-Open No. 2000-283869.
However, a combination of the capacitive position detection sensor and the press detection sensor formed by the piezoelectric sensor causes a following problem.
Electric charges are regularly injected to the position detection sensor to enable the capacitive position detection sensor to measure a capacitance. This injection amount changes according to the capacitance, and therefore changes between the case when a dielectric such as a finger touches the operation surface and the case when the dielectric does not touch the operation surface.
When the position detection sensor and the press detection sensor are disposed close to each other, the press detection sensor and the position detection sensor are capacitively coupled. In this case, electric charges are produced in the press detection sensor due to an influence of part of the electric charges injected to the position detection sensor.
The press detection sensor formed by the piezoelectric sensor detects whether or not there is a press or a pressing force based on electric charges produced when a piezoelectric film is deformed by a press on the operation surface.
Hence, when electric charges produced by the influence of the electric charges of the position detection sensor are produced in the press detection sensor, the press detection sensor erroneously detects these electric charges as electric charges produced by the piezoelectric sensor in response to a press. Therefore, it is not possible to accurately detect a pressing amount in some cases.

Touch input device that detects a touch position and a pressing input


Disclosed is a catalyst for converting nitrogen oxide into ammonia, which is capable of converting nitrogen oxide into ammonia under fuel lean exhaust gas conditions of more than theoretical air-fuel ratio (A/F=14.7), and a method for manufacturing the same. The catalyst according to the present invention comprises a metal oxide support impregnated with a precious metal, such that conversion of nitrogen oxide into ammonia under fuel lean exhaust gas conditions of more than theoretical air-fuel ratio (A/F=14.7) is possible.

(a) Technical Field
The present invention relates to a catalyst for converting nitrogen oxide into ammonia, and a method for manufacturing the same. More specifically, the present invention relates to a catalyst for converting nitrogen oxide into ammonia, which can efficiently produce NH3 even at a fuel lean region (A/F>14.7, λ (lambda)>1), and a method for manufacturing the same.
(b) Background Art
Recently, with the rapidly increasing oil prices, there is a growing interest in developing a lean burn engine for improving energy efficiency and reducing CO2 emissions. In general, the exhaust gas of a lean burn engine contains excess oxygen, and carbon, thus, carbon monoxide (CO) and hydrocarbon (HC), in the exhaust gas can be easily removed by a conventional after-treatment method. However, nitrogen oxide (NOx) cannot be easily removed from the exhaust gas. Therefore, a Lean NOx Trap (LNT) technology and Selective Catalytic Reduction (SCR) technology using urea (NH3) were developed as after-treatment technologies to reduce NOx produced from the lean burn engine.
The LNT technology is a technology to remove NOx by trapping using a NOx trap material-containing NOx trap catalyst (Lean NOx Trap (LNT) or NOx Storage Catalyst (NSC)).
The SCR technology is a method for spraying an aqueous solution, particularly a urea solution, into an exhaust pipe. The sprayed urea solution is pyrolyzed by heat in the exhaust pipe or catalytically cracked by contact with a catalyst, resulting in the conversion of one molecule of urea into two molecules of NH3. Using this technology, NOx is exhausted as harmless nitrogen and water by reacting NOx in the exhaust gas with the SCR catalyst using the converted NH3.
While both technologies are effective in removing NOx in exhaust gas containing excess oxygen, their application to an actual vehicle is problematic. Namely, the SCR technology using urea needs an infrastructure which can supply urea periodically, to provide NH3 as a reducing agent, and further requires extra equipment for storing and inserting urea into the vehicle.
The LNT technology is also limited because it should use an excess amount of a precious metal to activate the catalyst, it requires a complicated engine operation, and it presents difficulties in removing NOx at higher temperatures (400° C. or more) and lower temperatures (250° C. or less).
Thus, a three-way catalyst (TWC) converter has been broadly used which does not highly modify the existing after-treatment system for a gasoline vehicle. Further, studies have been focused on developing a passive SCR technology, which produces NH3 using the TWC converter and removes NOx using the produced NH3.
However, to carry out the existing passive SCR technology, the air-fuel (A/F) ratio of exhaust gas is decreased to a fuel rich region (A/F<14.7, λ (lambda)<1), which is lower than the theoretical A/F ratio necessary in order to efficiently produce NH3 As such, this existing technology causes further fuel consumption.
Therefore, there is a need for the development of a technology which can efficiently produce NH3 even at a fuel lean region (A/F>14.7, λ>1).

Catalyst for converting nitrogen oxide into ammonia and method for manufacturing the same


An improved process control sytem wherein objects having functions for configuring a process control system are distributed and arranged in a plurality of computers connected to a network and each distributed and arranged object shares the functions of the process control system; information component cassettes are provided having individual information related to monitoring and operation and methods to display the information in an optimum display form, and the cassettes are provided according to the types of information; an information component deck is provided which arranges the information component cassettes and offers a unified interface for accessing the information component cassettes; and control objects are provided for controlling a plant and display objects for monitoring and operation of the plants, the control objects and display objects being related to each other and operated in association with each other.

1. Field of Invention
This invention relates to a process control system that performs control and operation of a plant by controlling the process variables thereof, such as temperature, pressure, etc.
2. Description of the Prior Art
Conventional process control systems usually comprise an information command station and a plurality of control stations connected to a communication bus, wherein the control stations handle plant control and the command station handles plant monitoring and operation. According to the scale of the plant that is the target of control, a plurality of control stations is distributed and arranged throughout the plant.
FIG. 1 shows a conventional process control system, wherein information command station ICS and a plurality of field control stations FCS are connected to communication bus BS. The field control stations FCS control plant PLT. According to the scale of the plant, a plurality of control stations are distributed and arranged throughout the plant. Information command station ICS comprises display unit 1 comprising, for example, a CRT (cathode ray tube) which has a man-machine interface function, etc.; display control unit 2 which controls the display unit 1 and causes display unit 1 to show various screens or windows required for plant control and monitoring; input unit 3 which may comprise, for example, a keyboard, a mouse, etc, and handles data input for plant operation and control, etc; monitoring unit 4 which monitors the plant; operation unit 5 which carries out operations for plant control with the results of monitoring and operation of the plant being displayed on the display unit 1; and communication unit 6 which exchanges data with each control station via communication bus BS according to a specified communication protocol.
Field control station FCS comprises control unit CU which handles control of plant PLT; and input-output unit (I/O unit) which receives various types of signals as inputs from or transmits signals as outputs to plant PLT. For example, an I/O unit inputs and/or outputs analog signals of 4 to 20 mA or 1 to 5 V, thermocouple signals, contact signals, etc. The FCS further comprises communication unit 11 which exchanges data with the information command station or with each field control station via the communication bus BS according to a specified protocol.
In each plant PLT, sensor SN detects a process value, such as temperature and pressure. The opening of valves V1 and V2 is control led by the manipulated signal provided by the field control station FCS. For example, an analog signal of 4 to 20 mA or 1 to 5 V provided by sensor SN is applied to I/O unit 10. Based on this input, control unit CU carries out control calculations and determines a manipulated variable. This manipulated variable is outputted from I/O unit as an analog signal of 4 to 20 mA or 1 to 5 V, which is used to control the opening of valves V1 and V2.
In the system of FIG. 1, plant control is executed by controlling the process variables, such as temperature and pressure, that exist in the plant.
FIG. 2 shows the status of storing data nd programs of a function block process in the control units of the system. Function blocks are the elements of a control system and, for example, include PID computation block (PID), indication block (PVI), etc. Various control systems are constructed by combining these function blocks. As shown in FIG. 2, data and programs are stored in database DB and program library PL, respectively. Data blocks to which tag names are attached are stored in the database DB. Examples of these tag names are: FIC101, PIC102, PI201. Programs used for processing the data of the function blocks corresponding to each data block are prepared in program library PL. More than one program is prepared because there are two or more algorithms for the processing of the function blocks.
Interpreter INT reads the data blocks in turn, selects and calls up a processing program specified in a read data block from the program library PL. The called up processing program executes calculation process using the data in the corresponding data block. For example, interpreter INT reads data block fIC101 , selects and calls up a processing program PID specified in the data block from program library PL. The processing program PID executes calculation processing using the data in the data block FIC101. However, the conventional system of FIG. 1 has the following problems:
Since each function, such as monitoring and control, is designed to have its optimum function, it is necessary to have individual dedicated hardware and software board (OS) for each function. For example, the control function mounted in control unit CU is designed on the premise of a dedicated interface for the I/O unit 10. Accordingly, physical restrictions are imposed on the control function so that the control function and the I/O unit 10 must be mounted on the same hardware, i.e. field control station fCS. In addition, if a function is to be mounted on a separate device, reconfiguration of the function is required, such as program modification or recompiling.
As shown in FIG. 2, programs and data are maintained separately. For the programs, algorithms for processing all types of function blocks in the system are integrated into the library. Thus, when changing an algorithm for function blocks, the entire program library must be updated even if only one algorithm for one type of function block is changed. Moreover, to change or add a function, it is necessary to recompile and reload the entire program library, which requires temporrary shut down of the entire system.
As shown in the program library of FIG. 2, the functions not being used are mounted and integrated together with the functions actually used. For this reason, the required range of shared parts increases regardless of whether the system is large or small in scale. This results in increased system cost even when constructing a small scale system. In other words, it is not possible to group functions according to the user""s needs.
Accordingly, an object of the invention is to overcome the afore-mentioned and other problems, disadvantages and deficiencies of the prior art.
Another object is to provide a process control system which is more cost effective and offers better scalability or expandability of process control systems.


Processes for the continuous production of fermented, trehalulose-containing beverages, in particular ready-to-drink beverages or beverage concentrates.

Trehalulose (1-O-α-D-glucopyranosyl-D-fructose) is a heterodisaccharide in which glucose and fructose form an α-1,1 bond. It is known as a digestible, non-cariogenic sweetener which has similar physiological properties to isomaltulose. However, the sweetening strength of trehalulose is only 40 to 50% of that of sucrose.
According to DE 32 41 788, trehalulose is cleaved only with difficulty by the enzyme system in the human small intestine and is therefore absorbed only partly and at a delayed time. EP 1 424 074 discloses a nutritional composition for controlling the blood sugar level and for preventing obesity, which comprises isomaltulose or trehalulose. EP 1 393 637 A1 discloses agents for improving concentration and attentiveness which, besides isomaltulose, also comprise trehalulose.
EP 0 483 755 B1 discloses a process for producing trehalulose and isomaltulose from sucrose. According to the procedure disclosed therein, a sucrose-containing solution is brought into contact with a trehalulose-forming enzyme, and a trehalulose syrup is obtained. The trehalulose-forming enzyme is an enzyme which originates from a microorganism of the genus Pseudomonas or Agrobacterium. The specification discloses that the use of these microorganisms leads to a high trehalulose yield, with only very little monosaccharides being produced as by-products at the same time. In view of the virtually complete conversion, described in this specification, of sucrose to a trehalulose-containing mixture having only approximately half of the sweetness of a comparable sucrose solution, the disclosed trehalulose-containing mixture cannot therefore be used as sucrose substitute in beverages without additional process steps such as the addition of sweeteners. The processes known from EP 0 794 259 B1 for producing trehalulose-containing beverages are accordingly disadvantageous insofar as they provide for the separate addition of further sweeteners in order to obtain a consumable beverage.

Process for the production of fermented beverages


An original (1) to be reproduced is held in holder (11) and then the holder (11) is loaded into a projector (10). An image of the original (1) is projected on a layout sheet (18) which is placed on a digitizer (17). Data representative of the position of a desired region of the original (1) is then obtained. The holder (11) is then set in an image scanner (19) and photoelectric scanning is performed in accordance with the data.

1. Field of the Invention
The present invention relates to a method of and an apparatus for setting an original in an image scanner of a process scanner system and the like.
2. Description of the Prior Art
In a process scanner system, each scanning line of an image of an original is read with an image scanner to obtain image data. The image data is then processed and delivered to a control unit for directing an exposure beam to photosensitive material. Such image scanning should be carried out under two important conditions: one, the original should be properly set in the image scanner, and two various parameters or "scan data" required for scanning and image data processing should be optimally set to obtain a desired reproduced image.
With respect to condition one, a conventional technique involves clipping a desired area from the original and pasting the clipped area on a layout sheet or a transparent sheet (such as a transparent resin film.) The sheet is then set on an image scanner. In another conventional technique, the entire original is pasted on a layout sheet so that the desired area of the original is located in a trimming region previously indicated on the layout sheet. The layout sheet is then set in the image scanner and each scanning line of the image of the desired area is read.
In the conventional techniques, the layout sheet or the transparent sheet must be thrown away after use. This is uneconomical. Another disadvantage is that careful handling of the original is required since the original is used not only in the image reader but also during a layout process on a digitizer and it is sometimes damaged due to careless handling.
In order to meet requirement two, a conventional technique involves mutually setting optimum values of parameters (such as the optical densities of highlight and shadow points) in the image scanner. Sometimes, the parameter values with respect to a particular original are mistaken for those of To prevent such a mistake, the parameter values may be transmitted from a setup apparatus to the image scanner with on-line transmission. However, such a system is complicated and expensive.

Method of and apparatus for setting original in image


A software application implementable on a computer system is used to create a model of a hydraulic system to perform calculations. The user visually constructs a two-dimensional (2-D) connectivity model in the computer system. The 2-D connectivity model has a plurality of node points defined at various elements (sources, outlets, equipment, and junctions) of the hydraulic system and has segments interconnecting the node points. The user visually constructs a three-dimensional (3-D) segment model for each segment so that each segment model has the 3-D layout of the piping and the fittings for the segment. A 3-D system model of the entire hydraulic system is visually created in the computer system by combining the 3-D segment models. The software application performs calculations using the 3-D system model, and the 3-D system model can be visually or automatically verified to determine whether the model substantially corresponds to the 3-D layout of the hydraulic system, and has been laid out without errors.

Referring to FIG. 1, an exemplary hydraulic system 10 having fittings, piping, and equipment is schematically illustrated. In one example, the hydraulic system 10 can be a relief system, such as used for a flare stack in a chemical plant. Thus, the present example of the hydraulic system 10 has pressure vessels 12, relief valves 16, a knockout drum 13, and an elevated flare stack 18 interconnected by piping 14 and junctions 15. The relief valves 16 discharge overpressure from the vessels 12 to the knockout drum 13 and elevated flare stack 18 in the event of an overpressure contingency. Of course, such systems 10 are typically more complex than illustrated in the example of FIG. 1 and will have a number of elements which are not shown but which would be present to circuit the piping 14 in an actual implementation.
During a hydraulic analysis, a user performs hydraulic calculations to determine pressure drops, flow rates, or other hydraulic parameters that may occur in the system 10 under various conditions. As a first step in the analysis process, a user typically starts with an isometric drawing or blueprints of the system 10 to be analyzed, and inputs that system into a software application to provide further details relevant to modeling the system that may not be reflected in the isometric drawings alone. Such an isometric drawing is typically created with a three-dimensional (3-D) drawing program, such as AutoCAD, and information from the isometric drawing is usually entered into the software application by a user by hand, although the start drawing could also be conceivably be loaded into the software application even if it lacks some information pertinent to the subsequent modeling of the system.
In particular, 3-D information concerning the size and orientation of piping, fitting, equipment, etc. is entered into the software application because such information is important to accurately model the hydraulics. Additionally, information concerning the expected hydraulic operation and limits of the various elements is entered into the software application, and to the extent that a particular element has already been modeled and entered into the software application, it can be retrieved from a library of elements. For example, information concerning the trip pressure for a relief valve 16 would be entered into the software application, and/or would already be stored in the application for ready retrieval by a user.
Various software applications of the type described above for creating a model of a system 10 are known in the art such as Visual Flow™, Flare Net, and Tri-Header, which are all incorporated by reference herein. Another software application is Pressure Protection Manager™ by Berwanger, Inc. disclosed in U.S. Pat. No. 5,774,372, which is incorporated herein by reference.
To create the model for performing the hydraulic calculations in the software application, the system 10 is divided into primary elements of segments and node points. Using a node-segment convention known in the art for hydraulic calculations, node points (e.g., N1 to N7 in FIG. 1) are defined at particular elements in the process, and segments are defined as the collection of fittings (not shown) and piping 14 between the node points. The elements where node points are defined conventionally include sources (e.g., relief valves 16), outlets (e.g., elevated flare tip 18), junctions (e.g., tees 15), or pieces of network equipment (e.g., knockout drum 13).
Defining node points at these elements in the system 10 is required for performing the hydraulic calculations. For example, a junction 15 must be defined as a node point because the hydraulic calculations must resolve the mass flow rates and other variables occurring at the three openings of the junction 15. Similarly, sources and outlets must be defined as node points of the system 10 because the mass flow rates from all the sources must equal the mass flow rates to all the outlets. In addition, equipment, such as a relief valve, is conventionally defined as a node point because the fluid dynamics of such equipment can be complex and the equipment's characteristics for the hydraulic calculations are approximated. It may also be beneficial to define changes in orifice dimension, such as changes in pipe diameter or ANSI expansions, as node points.
Some prior art software applications require the user to create a model of the hydraulic system by manually entering information concerning node points (sources, outlets, equipment, and junctions) and segments (piping and fittings) into a tabular form. Because a hydraulic system can have hundreds of pieces of equipment, pipe lengths, fittings, etc., entering the information manually in tabular form is time consuming and prone to errors. To overcome these difficulties, prior art software applications such as those mentioned above allow a user to visually construct a model of the hydraulic system instead of using mere tables. Referring to FIGS. 2A-2B, interfaces 20 and 40 of a prior art software application, Visual Flow™ (also known as Visual Flare) by SimSci-Esscor, are illustrated. Using the first interface 20 of FIG. 2A, the user constructs a two-dimensional (2-D) system model 30 of the hydraulic system. Then, using the second interface 40 of FIG. 2B, the user constructs 3-D segment models of the segments of the hydraulic system.
In FIG. 2A, the first interface 20 includes a pallet 22 for constructing the 2-D system model 30 using tools 24 on a toolbar. The node-segment convention discussed above is used to construct the 2-D system model 30. Thus, node points are defined at conventional elements (e.g., sources 32, outlets 33, equipment 34, and junctions 36). In addition, segments (e.g., line 38) interconnect the node points and represent the piping and fittings of the system.
The tools 24 include buttons for adding nodes or segment to the pallet 22. To add a node element (e.g., source 32, valve 34, outlet 33, or junction 36), the user selects the desired node tool 25 and clicks on a location of the pallet 22 to add the node element. A dialog box (not shown) then allows the user to define aspects of the element, such as tag numbers, flow rates, pressures, etc., or again such information may already be populated in an element library and automatically retrieved. To add segments between node points, the user selects the segment tool 27 and connects the node points on the pallet 22 with an interconnecting line 38, which merely represents the connection between the node points and which (at this point) lacks any details on the piping and fittings used or their orientations. In this prior art software application, the user does not define node points at changes in orifice dimensions, expansions, contractions, or changes in pipe diameters, and thus a given segment can include such features.
Once the 2-D system model 30 has been created, the user double clicks on a segment (e.g., line 38 in FIG. 2A) to bring the user to the second interface 40 of FIG. 2B. In this interface 40, the user constructs a 3-D segment model 46 of the segment, which, in short, allows the user to portray the actual physical layout of the segment in question (i.e., does it travel up or down, left or right, what sorts of fitting or elbows are used, etc.). The second interface 40 includes a pallet 42 for visually constructing the segment and includes tools 44 for selecting piping sizes and fitting types. After selecting a piping size, the user clicks at a starting point on the pallet 42 with the mouse pointer 41, and the starting node point (e.g., junction 36) of the selected segment is then displayed on the pallet 42. Using this 3-D view, the user moves the mouse pointer 41 in the required direction for the piping, which is represented by line 48 on the pallet 42. As the user moves the mouse pointer 41, a length dimension (not shown) is displayed adjacent the line 48 to indicate the length of piping being drawn. After moving the desired direction and length, the user clicks on the pallet 42, and a selected fitting 47 from the tools 44 is inserted at that location. The user repeats the above drawing steps until the user reaches the end of the segment and double clicks on the pallet 42 to enter the ending node point (e.g., outlet 33).
After constructing the 3-D segment model 46 for the selected segment, the user returns to the 2-D system model 30 in FIG. 3A. Another segment can thereafter be selected in the 2-D interface 20 of FIG. 2A to access the second interface 40 of FIG. 2B and to construct or view a 3-D segment model of the newly selected segment.
When the required piping lengths and fittings have been entered for all the segments of the hydraulic system into the software application, the user accesses a hydraulic solver in the software application to perform hydraulic calculations and modeling based upon the inputted 3-D data and other relevant hydraulic data present in the model (e.g., relief valve trip pressures, etc.). The algorithms used by hydraulic solvers are well known in the art, such as Beggs, Brill and Moody; Moody; Beggs and Brill high velocity; and Lockhart and Martinelli, Berwanger NetMaster 1.0, for example, but which are incorporated herein by reference. The hydraulic solvers allow a user to determine the performance of the hydraulic system during a specific global scenario or common contingency, such as a fire. By inputting the scenario, the flow rates, fluid properties at all sources, pressures at the outlets, and other required conditions and information into the hydraulic solver, the solver can determine (for example) backpressure results, which the user can then use to determine whether the backpressures will cause a catastrophic failure, for example. As hydraulic solvers are well known, they are not further discussed.
One disadvantage of this prior art software application is that the user is unable to split a segment into two segments from the second interface 40. For example, if the user realizes that a node point (e.g., a junction) should have been located somewhere in the segment (e.g., on line 48 in FIG. 2B), the user must exit the 3-D interface 40, return to the 2-D interface 30 to add the node point to the segment (e.g., line 38), and return to the 3-D interface 40 to reenter segment information. In another disadvantage, the user may find it difficult to move the mouse pointer 41 to draw the precise length of piping. Consequently, the user may simply approximate piping lengths while constructing the segment with the mouse pointer 41 and may use a dialog window (not shown) to manually enter the actual piping lengths for the segment.
Perhaps more importantly, constructing a 3-D segment model 46 of FIG. 2B for each segment of a hydraulic system can still produce errors in the entire system model, and accordingly can produce errors in the hydraulic calculations based on such an erroneous model. For example, when constructing a 3-D segment model 46 for a given segment, the user is not provided feedback whether the pipe lengths, 3-D orientations, etc. are physically accurate in light of the entirety of the hydraulic system. This is because the user can only view one 3-D segment model 46 at a time in the second interface 40 of FIG. 2B, and cannot view two or more adjoining 3-D segment models 46 together in a 3-D context. The only other avenue for viewing the entirety of the hydraulic system, or multiple segments, is provided by the a 2-D interface of FIG. 2A, which (like a typical circuit schematic) indicates the positions and lengths of the segments in only a functional, non-physical manner. Therefore, it is possible for the user to produce unrecognized errors which respect to the 3-D layouts of the segments. For example, a portion of one segment may inadvertently occupy the same physical location as another segment. For example, valve 34 in FIG. 2A (segment 39) may occupy the same 3-D space as the outlet 33 (segment 38) because the user has entered an incorrect pipe length or orientation in one of the segments 38 or 39. This might never be noticed by the user, and as a result any calculations performed using the 3-D modeling information, which necessarily relies on the 3-D data from input for each of the segments, would likely be incorrect.
Without the ability to view the 3-D system model of the entire hydraulic system (or at least two adjoining 3-D segment models), the user is offered no visual feedback of such an error. Having two elements occupy the same space is not physically possible, and any hydraulic calculations performed on an incorrect model will produce erroneous results as just noted. Therefore, a need exists in the art of hydraulic modeling for a software application that allows a user to construct a model efficiently, and in a manner that reduces errors such as those just noted. The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.

This patent is subject to a terminal disclaimer.

Apparatus and method for creating scaled, three-dimensional model of hydraulic system to perform calculations


A cartridge for actuating a piston-like or accordion-like dispenser-vial for applying medicament to an eye. The cartridge includes a housing for holding the dispenser-vial and a telescoping cylinder for compressing the dispenser-vial in the longitudinal direction to actuate the vial. The cartridge includes a locking mechanism for locking the telescoping cylinder to restrict its movement and a lever mechanism for releasing the cylinder from the locked position so that a drop is released from the dispenser. The housing includes a finger for engaging the lower eyelid and exposing the conjunctival cul-de-sac.

1. Field of the Invention
The invention relates to a cartridge for applying medicament to an eye from a vial-dispenser of the type which is actuated by compression of the vial between its nozzle and its bottom wall.
2. Description of Related Art
There are various dispensers which are known for applying medicament to an eye. A typical eye-drop container includes a flexible vial storage portion and a nozzle for dispensing drops of medicament into the eye by squeezing the vial between its side walls. Less common, but more precise, are accordion-like or piston-like dispensers which are actuated by squeezing the vial between a bottom wall and the nozzle so as to compress the vial in its longitudinal direction, rather than from its sides. It is these accordion-like or piston-like dispensers with which the cartridge of the present invention is particularly adapted for use. An example of a new and improved piston-like dispenser which propels micro-drops into the eye is the subject of my U.S. application Ser. No. 07/801,243 which is expressly incorporated herein by reference.
Most people encounter difficulty in applying drops to their eyes. The eye is a very sensitive body part and individuals find it difficult to control reflexive blinking when applying drops thereto. Also, eye drop users often have poor vision. Poor vision makes it difficult to position the tip of the dropper bottle over the eye and frequently causes drops to be incorrectly applied to the nose or cheek. Additionally, elderly people often have difficulty holding a dropper bottle steady or encounter difficulty in squeezing the bottle to apply a proper quantity of the medicament.
Even if the liquid medicament is properly applied to the eye, the medicament's effectiveness is limited. The minimum volume of a drop of liquid medicament which can ordinarily be introduced into contact with an eye at one time is about 30 .mu.l. Any amount which is greater than about 25 .mu.l usually spills over the eyelid onto the cheek since this is the maximum volume which the eye can ordinarily handle. When eye drops are applied to the surface of the eyeball, blinking and natural tear flow combine to limit the time to a few minutes that liquid medicament will remain effective.
On the other hand, if medicament is applied to the cul-de-sac of the conjunctiva, the medicament will remain effective for a longer period of time, maximizing the benefits of applying drops of liquid medicament to the eye. This is because the conjunctiva is an area of low sensitivity and low tear turnover such that blinking and tearing are avoided. However, because of the difficulty encountered in steadying the dropper and accurately positioning it over the conjunctiva, maximizing the effectiveness of the medicament remains elusive.
U.S. Pat. No. 4,543,096 describes and illustrates an apparatus having finger-like projections which are attached to the front of an eye drop bottle to spread the eyelids apart during the eye drop dispensing process. One moveable finger is connected to a lever for both depressing the lever and simultaneously causing the eyelids to spread apart while forcing a drop from the dropper bottle. However, the apparatus described in U.S. Pat. No. 4,543,096 cannot be used with the accordion-like or piston-like dispensers which are actuated by compression in the longitudinal direction rather than from the sides. Furthermore, this apparatus will not properly expose the cul-de-sac.
Similarly, U.S. Pat. No. 4,531,944 depicts an apparatus for steadying the tip of a dropper over the eye and further includes a sighting hole to distract the eye. However, this apparatus does not have a means to expose the cul-de-sac nor keep the lower eyelid depressed.
Typical eye-drop dispensers also have the disadvantage that the force which is necessary to actuate the dispenser to emit a drop is not in the same direction as the motion which is necessary to lower the lower eyelid and expose the cul-de-sac. It would be desirable to have a device which actuates the dispenser with a motion which is in the same direction as that which is necessary to lower the lower eyelid.
U.S. Pat. No. 5,267,986 describes a device which meets all of the above-described needs. Additional improvements and variations on this device are described herein.

Cartridge for applying medicament to an eye


An electronic parking brake support system for a vehicle includes an electric parking brake having at least one brake member associated with a wheel of the vehicle. The system also includes a service brake system constructed and arranged to control service brakes of the vehicle. The service brake system includes at least one circuit constructed and arranged to determine an occurrence of a failure or degradation condition of the service brake system and, in response to the detected condition, to send a request signal to the electric parking brake instructing the electric parking brake to activate the at least one brake member.

Service brake systems degrade and fail. Vehicles with these degradations and failures must meet minimum performance requirements established by Original Equipment (OE) manufacturers and legal entities, such as the United States (US) Government and Commission of the European Communities (ECE). The US Federal Motor Vehicle Safety Standard (FMVSS) 135 outlines several minimum vehicle performance requirements, including the following as examples:                Cold Effectiveness (reduced effectiveness of brake linings),        Antilock Functional Failure (failed wheel pressure outlet valve or failed hydraulic pump in Anti-lock Brake System, ABS, hydraulic control unit),        Hydraulic Circuit Failure (primary, secondary or both),        Brake Power Unit or Brake Power Assist Unit Inoperative (low or no vacuum), and        Hot Performance (reduced effectiveness brake linings).
The service brake system can be configured to provide adequate brake torque and meet minimum vehicle performance requirements. Examples include providing larger pedal ratio, higher friction linings, larger booster diameter, larger rotors, smaller master cylinder bore, etc. There are other brake torque support functions that increase brake torque to meet minimum vehicle performance requirements. Examples include an Electric Vacuum Pump (EVP) that increases brake booster vacuum and ABS/stability control pump. The above possible solutions may involve weight, packaging, durability, cost and other service brake performance and subjective brake feel characteristic compromises that are not desired.
Thus, there is a need to provide a system that provides brake torque in order to meet minimum performance requirements in the cases of degraded and failed service brakes that uses existing brake system components, does not increase weight, and does not compromise service brake performance and subjective brake feel characteristics

Electronic brake support system for use when service brake system has failed or is degraded


A knife sharpener having a specially configured sharpening groove for sharpening knives or the like to a particularly narrow and sharp edge. The sharpener comprises a body member having a rectangular extension which has a recess for engaging the sharpening blades. The body member has grooves therein for engaging support members, one of which acts as a guard from the knife sharpening activity. A second embodiment includes the supports being angled so as to place the knife sharpener at an angle for easy access thereto. The blades are substantially triangular in shape wherein the corners of each blade are rounded, all having equivalently-sized radii. The blades are detachably attached to the body member within the recess so that the blades can be rotated or flipped for exposing additional and fresh sharpening edges. The recess is shaped so as to secure the blades in an abutting fashion wherein the bottom of each blade is angled from the horizontal and the sharpening groove between the blades is relatively narrow. Because of the rounded edges of the blades, a special sharpening groove is formed wherein the straight edge of each blade forming the groove transforms into an arc which leads to a point. Accordingly, a very narrow and sharp knife edge is formed from this groove arrangement.

This invention is directed toward knife sharpeners, and more particularly, toward an improved sharpening blade configuration for forming a sharper cutting edge on a knife or the like.
Many knife sharpeners have been developed over the years that are directed toward new and improved methods for sharpening a knife edge. The numerous sharpeners include different configurations for blade shapes, blades having a plurality of sharpening edges wherein the blades are adapted to be moved or the like for exposing new edges, and supports and combined tools directed toward more conveniently placing the sharpening blades in position for use. The blade configurations include circular cutting blades, triangular cutting blades and square or rectangular cutting blades. Supports and the like include those which can be permanently attached to a work bench or the like, those which can be hand held and others which are self-supportive. In addition, tools have been invented which combine a knife sharpener with another tool such as a file or screwdriver.
U.S. Pat. No. 469,615 to Wardwell discloses a knife sharpener having abutting circular blades lying in the same vertical plane. The knife sharpener includes a support base which is adapted to attach to a permanent structure. While the Wardwell sharpener would seem to apply a circular and narrow configuration to the edge being sharpened, because of the large radius inherent in circular disks, the lead-in groove is relatively large, forming only a broad based edge having a sharp point.
U.S. Pat. No. 584,933 to Friedrich discloses a sharpener having square and rotatably attached overlapping sharpening blades also having bevelled edges. The blades in the Friedrich sharpener overlap, using the overlapping configuration to apply pressure to the knife edge being passed through the blades. The blades are rotatably attached and have a plurality of sharpening edges thereon so that the blades can be rotated to expose a fresh sharpening edge when others become dull. The sharpener in Friedrich, however, does not have rounded intersections or corners or the like which give to the knife edge, a rounded and more streamlined configuration. Additionally, the Friedrich blades, being of the overlapping nature, are in conflict with the general principles of this invention.
The patent to Keezer et al., U.S. Pat. No. 1,622,197, discloses a knife sharpener having a support and base for attachment to a permanent structure. The blades therein are elongated and triangularly shaped and are arranged to be mutually engaging. However, unlike the instant invention, the corners of the blades are not rounded and the blades engage and intersect at a point, having no lead-in radius. Therefore, again no streamlined edge is produced on the knife through sharpening the same.
In addition to the above, the patents to Jones, U.S. Pat. No. 2,436,810; Pleasants, U.S. Pat. No. 3,289,498; and Judd et al., U.S. Pat. No. 1,474,636 disclose additional knife sharpeners having circularly-shaped blades which also exhibit the same shortcomings as those patents discussed above. U.S. Pat. No. 4,731,957 to Weisinger and U.S. Pat. No. 562,223 to Hausse disclose knife sharpeners using triangular blades which are also adapted to be rotated for exposing fresh sharpening surfaces. However, and as discussed above, these blades do not exhibit rounded corners for the streamlined sharpening effect which is the purpose of this invention.


A garage lift system which aids in lifting and storing various objects such as ATV's within an enclosed area. The garage lift system generally includes a frame adapted to be secured between a floor and a ceiling utilizing upper mounts and lower footings. The frame includes a guide rail extending horizontally between two or more vertical supports. A drive assembly is provided which includes a motor driving a pair of reels. The reels are wound with cables, with a first cable extending downwardly to connect to a first end of a lift member and a second cable extending along the guide rail and through a pulley wheel prior to extending downwardly to connect to a second end of the lift member. Various objects such as vehicles may be positioned on the lift member and the drive assembly utilized to raise or lower the lift member.

Field of the Invention
The present invention relates generally to a lift and more specifically it relates to a garage lift system which aids in lifting and storing various objects such as ATV's within an enclosed area.
Description of the Related Art
Any discussion of the related art throughout the specification should in no way be considered as an admission that such related art is widely known or forms part of common general knowledge in the field.
Enclosed storage areas like garages often become cluttered with various objects such as vehicles, tools, boxes, and the like. With such limited space in such storage areas, there is always a demand for new and innovative ways for making the most out of the limited square footage.
Particularly in garages, clutter can lead to damage to vehicles which either hit such cluttered objects or risk having such cluttered objects falling over and causing damage. It can also be time-consuming to move objects or vehicles out of the way to gain access to something, such as a recreational vehicle, that may be stored in the back of the storage area.
Because of the inherent problems with the related art, there is a need for a new and improved garage lift system which aids in lifting and storing various objects such as ATV's within an enclosed area.


A buffer circuit includes an input for receiving a logic signal, and a transfer circuit for transferring the logic signal from the input to an output of the buffer circuit. The transfer circuit includes at least one logic gate having a trip point sensitive to a supply voltage of the buffer circuit. The buffer circuit further includes a delivery circuit for delivering an inhibit signal having a predetermined duration when the logic signal has a trailing edge and/or leading edge, and an inhibit circuit for inhibiting the transfer circuit and for isolating the output of the buffer circuit from the input of the buffer circuit when the inhibit signal is delivered. A storage circuit holds a logic value of the logic signal at the output of the buffer circuit when the inhibit signal is delivered.

The present invention relates to a buffer circuit with transfer means for transferring a logic signal received at its input to its output, with the transfer means comprising at least one logic gate having a trip point sensitive to the supply voltage of the buffer circuit.
In integrated circuits, external logic signals are often received through buffer circuits that shape the signal. Such buffer circuits generally comprise logic gates having a trip point sensitive to the variations in the supply voltage applied to the integrated circuit. Certain operations sometimes prompt a substantial current draw in the output state of the integrated circuit leading to a temporary but significant drop in the supply voltage. A supply voltage drop of this kind leads to a drop in the tripping threshold of the buffer circuits. This drop gives rise to the transmission of erroneous signals, as will be understood more clearly by the following example.
FIG. 1 illustrates an integrated circuit 1 on an interconnection support 10. The integrated circuit 1 has contact zones P1 to P5 connected to zones P1xe2x80x2 to P5xe2x80x2 of the support 10 by ultrasonically soldered metal wires 11. The zone P1 receives a ground potential GND, the zone P2 receives the supply voltage VCC, the zone P3 receives an external clock signal CLKEXT, the zone P3 is designed to receive data DTR, and the zone P5 is designed to send data DTX.
Due to the resistivity of the wires 11 and their parasitic inductance, the ground potential GND present at the zone P1, under the conditions described below, may be different from the external ground potential GNDEXT present at the zone P1xe2x80x2. Similarly, the supply voltage VCC received at the zone P2 may be different from the external supply voltage VCCEXT present at the zone P2xe2x80x2.
The external clock signal CLKEXT received at the zone P3 is applied to the core 2 of the integrated circuit (represented schematically by a block) by a buffer circuit 3 comprising two cascade-connected inverter gates 4, 5 whose output delivers an internal clock signal CLK that copies the variations of the external clock signal CLKEXT.
The data DTX sent by the core 2 of the integrated circuit are delivered to the zone P5 by an output buffer 6 comprising two cascade-connected inverter gates 7, 8. The output inverter gate 8 comprises a large-sized pull-up transistor 8-1 capable of delivering high current when sending a 1 in the presence of a highly capacitive load. Similarly, the gate 8 comprises a large-sized pull-down transistor 8-2 capable of receiving substantial current during the sending of a 0 (GND) in the presence of a highly capacitive load. A capacitive load of this kind is, for example, a data bus connected to the zone P5xe2x80x2, having a high parasitic capacity.
Thus, when the integrated circuit 1 sends data on the zone P5, in the presence of a highly capacitive load, the high current that is output during the transmission of a 1 leads to a drop in voltage in the supply wire 11 connecting the zone P2 to the zone P2xe2x80x2, and the reduction of the internal supply voltage VCC in relation to the external voltage VCCEXT. Similarly, the high current that is input during the transmission of a 0 causes a drop in voltage in the supply wire 11 connecting the zone P1 to the zone P1xe2x80x2, and an increase in the internal ground potential GND in relation to the external ground GNDEXT.
In synchronous data transmissions, the sending of data is generally synchronized with the clock edges, generally the trailing edges, so that a fluctuation of this kind in the internal supply voltage VCC or the ground potential GND occurs simultaneously with the reception of an edge corresponding to a variation of the external clock signal CLKEXT.
FIGS. 2A to 2D illustrate the consequences of a drop in the voltage VCC when a trailing edge is received from the clock signal. FIG. 2A shows the clock signal CLKEXT received on zone P3 at the time of a trailing edge, and FIG. 2D shows a clock signal CLK delivered by the output of the buffer 3. FIG. 2B shows data DTX sent by the zone P5, and FIG. 2C shows the internal supply voltage VCC received by the zone P2. In FIG. 2A, the line of dashes represents the trip point Vt of the inverter gates 4, 5 which is generally equal to VCC/2.
At the instant t0, the clock signal CLKEXT shows a trailing edge and starts diminishing. At an instant t1, the clock signal CLKEXT reaches the trip point of the gates 4, 5 so that the output of the buffer 3 trips, and the clock signal CLK also goes to 0. The passage to 0 of the clock signal CLK activates the sending of data, herein data at 1 (FIG. 2B), and the sending of data prompts a significant drop in the voltage VCC (FIG. 2C).
It follows that the trip point Vt of the gates 4, 5 also drops (FIG. 2A) and becomes lower than the clock signal CLKEXT at an instant t2, so that the gates 4, 5 again trip. The clock signal CLK delivered by the buffer 3 thus goes to 1 whereas it should have stayed at 0. At an instant t3, the supply voltage VCC rises again, the trip point Vt rises and becomes higher than the clock signal CLKEXT, and the clock signal CLK goes back to 0.
Ultimately, after the passage to 0 of the external clock signal CLKEXT, a short-duration parasitic signal appears at the output of the buffer circuit 3. This parasitic signal risks being processed by the integrated circuit as a clock pulse, leading to errors of operation, such as the sending of data before the xe2x80x9ctruexe2x80x9d trailing edge following the external clock signal appears, for example.
In the prior art, there are known ways of avoiding this problem by making input buffers using inverter gates with switching hysteresis, generally inverter Schmitt triggers. Schmitt inverters of this kind have a low-state trip point or tripping threshold Vtl and a high-state tripping threshold Vth that are distinct, the former being lower than the latter.
However, according to observations made by the Applicant, Schmitt inverters cannot totally eliminate the risk of transmission of parasitic signals. This is shown in FIGS. 3A to 3D which show the appearance of the signals of FIGS. 2A to 2D when the input buffer 3 comprises two cascade-mounted Schmitt inverters. It can be seen that a major drop in the supply voltage VCC (FIG. 3C) following the transmission of data at 1 (FIG. 3B) can also cause the high-state trip point Vth of the Schmitt triggers to drop, at the instant t2, below the level of the clock signals CLKEXT (FIG. 3A). Thus, the internal clock signal CLK herein also has a parasitic pulse which disappears at the instant t3 when the low state trip point Vt1 of the Schmitt inverters become higher than the external clock signal CLKEXT.
In view of the foregoing background, an object of the present invention is to provide a buffer circuit that is not sensitive to a drop in the supply voltage taking place after a leading and/or trailing edge of a signal is received at its input.
This and other objects, advantages and features of the present invention are provided by a buffer circuit comprising means for the transfer, to its output, of the logic signal received at its input, with the transfer means comprising at least one logic gate having a trip point sensitive to the supply voltage of the buffer circuit. The buffer circuit further comprises means to deliver an inhibit signal of a determined duration when the logic signal has a trailing edge and/or a leading edge, means for inhibiting the transfer means by insulating the output from the input of the buffer circuit when the inhibit signal is delivered, and storage means for holding at the output of the buffer circuit the logic value that is present therein when the inhibit signal is delivered.
According to one embodiment, the means for delivering the inhibit signal comprises a delay line receiving a reference signal at its input, and a logic gate receiving at a first input the output of the delay line and at a second input the reference signal. The reference signal has the same trailing and/or leading edges as the logic signal. According to another embodiment, the means for delivering the inhibit signal receives a reference signal at its input, with the reference signal being taken at the output of the buffer circuit.
According to yet another embodiment, the transfer means comprises a first inverter gate and a second inverter gate in series, and the inhibiting means comprises a first switch between the two inverter gates. According to another embodiment, the storage means comprises a third inverter gate receiving the output of the second inverter gate at its input, and the output of the third inverter gate is connected to the input of the second inverter gate by a second switch. The first and second switches may be driven by inverter signals so that the first switch is closed when the second switch is open, and vice versa.
According to another embodiment, the buffer circuit comprises means to block the means delivering the buffer circuit inhibit signal.
The present invention also relates to an electronic circuit comprising at least one buffer circuit as defined above, having its input connected to a terminal of the electronic circuit designed to receive a clock signal.
According to one embodiment, the electronic circuit comprises means to send data in synchronization with trailing edges and/or leading edges of the clock signal. According to another embodiment, the electronic circuit comprises a memory array and means for the transmission, in synchronization with trailing and/or leading edges of the clock signal, of data read in the memory array. The buffer circuit inhibit signal may be sent only during periods of data transmission.

Buffer circuit for the reception of a clock signal