An apparatus and method are provided for processing hydrocarbon feeds. The method enhances the conversion of hydrocarbon feeds into conversion products, such as ethylene and propylene. In particular, the present techniques utilize a high-severity reactor integrated with another reactor type to convert hydrocarbons to other petrochemical products.

The oil, gas and petrochemical industry desires to efficiently obtain hydrocarbons and process the hydrocarbons to produce desired products. Refining processes involve upgrading, converting or separating hydrocarbons (e.g., crude oil) into different streams, such as gases, light naphtha, heavy naphtha, kerosene, diesel, atmospheric gas oil, asphalt, petroleum coke and heavy hydrocarbons or fuel oil. Similarly, natural gas may be converted into industrial fuel gas, liquefied natural gas (LNG), ethane, propane, liquefied petroleum gas (LPG), and natural gas liquids (NGLs). The oil and gas processes are also often integrated with petrochemical systems to convert refinery streams into chemical products, such as ethylene, propylene or polyolefins.
To convert hydrocarbon feeds into petrochemical or basic chemicals, chemical conversion processes may be utilized. These processes typically involve using thermal or chemical reactors or furnaces to produce reactive hydrocarbon products, such as acetylene, ethylene or propylene in different proportions. As an example, steam cracking reactors are commonly utilized to convert the hydrocarbon feed into ethylene and acetylene, which may be further processed into various chemical products. The steam cracking reactors are utilized because they provide feed flexibility by being able to utilize gas (e.g., ethane) and liquid (e.g., naphtha) feeds.
Historically, the oil and gas refineries utilize the higher value distillates from the hydrocarbon feed, which are typically fungible fuels, such as mogas, natural gas and diesel. As a result, the petrochemical refineries utilize the remaining fractions, such as ethane, propane, naphtha and virgin gas oil, in their processes. However, few chemical conversion processes are able to directly employ natural gas or the lower value refinery feeds, such as aromatic gas oils or fuel oils. As such, there is a need for a process that can produce ethylene and acetylene from different feeds, such as advantaged feeds (e.g., natural gas and/or aromatic gas oils, for example).
To process these feeds, high-severity conditions (e.g., more severe operating conditions, such as higher temperatures) are generally involved to produce products having a higher value than the feed. High-severity conditions enable methane cracking and aromatic ring cracking, which do not occur at appreciable rates at typical low-severity conditions (e.g., conventional steam cracking conditions). At high-severity conditions, the primary products of thermal chemical conversion processes are acetylene and ethylene along with hydrogen (H2) and coke, which may vary in proportion depending on the temperatures, pressures, residence times and feed type utilized in the conversion process. Low-severity conditions may be still be used to convert higher hydrogen content refinery byproduct streams. At lower severity conditions, saturates may be converted to ethylene, propylene and butenes and alkyl aromatics may be converted to benzene, toluene and gasoline blend stock. Low-severity reactors operate above 700° C. to enable cracking or conversion to light olefins. Typically, low-severity reactors do not include lower temperature thermal processes, such as cokers or visbreakers, heat soakers, which do not produce substantial light olefins (≧10 wt % light olefin yield). The lower temperature thermal processes may typically operate at temperatures below 700° C. and even more commonly below 600° C. High-severity and low-severity conversion processes are typically based on different pyrolysis reactors, which may include pyrolysis alone or integrated with combustion chemistry. These reactors can be divided into eight different types: low-severity partial combustion, high-severity partial combustion, low-severity indirect combustion, high-severity indirect combustion, low-severity arc process, high-severity arc process, low-severity thermal pyrolysis and high-severity thermal pyrolysis. These pyrolysis reactor types differ in the means of generating and transferring the heat for the pyrolysis and/or in the severity utilized in the operating conditions. For simplicity, these differ types are discussed below as techniques, which include the low-severity and high-severity.
The first technique involves a partial combustion reactor. The partial combustion reactor burns part of the hydrocarbon feed to supply the heat to pyrolyse the remaining portion of the hydrocarbon feed. The partial combustion reactor includes pyrolysis chemistry (e.g., thermochemical decomposition of feed at elevated temperatures in the absence of oxygen) and combustion chemistry (i.e., exothermic chemical reactions between a fuel and an oxidant), with both chemistries occurring at the same time and with the products of both chemistries being an integral part of the reactor product. An example of this process is German Patent No. 875198 and U.S. Pat. Nos. 3,242,223 and 7,208,647. Specifically, U.S. Pat. No. 7,208,647 describes a partial combustion process that utilizes partial oxidation to convert methane into ethylene, while U.S. Pat. No. 3,242,223 describes a partial combustion process that utilizes partial oxidation to convert liquids into ethylene. Due to the nature of this process, however, an air separation plant is typically required and combustion products (e.g., carbon monoxide (CO) and carbon dioxide (CO2)) are significant components of reactor effluent that have to be managed. As a result, the partial combustion process has certain limitations, such as the requirement to remove the high levels of combustion products and associated processing or additional processing equipment.
The second technique involves an indirect combustion reactor. The indirect combustion reactor contacts a combustion product with the feed to be cracked in the reactor. As such, this process involves pyrolysis and combustion chemistry, but typically the combustion chemistry may occur at a different time or location and the pyrolysis chemistry, while occurring in the presence of combustion products, proceeds in a largely non-oxidative environment, resulting in the products of the two chemistries being an integral part of the reactor product. In a process used by Hoechst (High Temperature Pyrolysis) in the 1960s, the thermal energy from a hot combustion product is used to crack a feed in direct contact. Examples of these types of reactors are described in G.B. Patent No. 834419 and German Patent No. 1270537. As another example, the Kureha/UCC process is similar, except that the primary purpose of this process is to make ethylene. In this process, which is described generally in U.S. Pat. No. 3,419,632, the hydrocarbon feed is a crude oil or a distillate having a boiling point less than (<) 1050° C. Further, U.S. Pat. No. 7,208,647 describes an indirect combustion process, which directly contacts the combustion gas with the feed to be cracked. Similar to the discussion for the partial oxidation process, this approach suffers from the same limitations of having to have an air separation plant and manage the combustion products. Accordingly, this type of reactor and associated process also requires an expensive active quench step to stop the pyrolysis chemistry (e.g., water or oil).
The third technique involves an arc reactor, which includes plasma arc reactors and electric arc reactors. This process typically involves only pyrolysis chemistry. Arc reactors are commercially limited and typically operated in a few small plants and described in U.S. Pat. No. 1,860,624. This process involving this type of reactor typically uses a water absorption process for recovery of acetylene, which was initially developed in the 1940s. The electric arc process utilizes electric power to heat a feed. As an example, U.S. Pat. No. 7,119,240 describes an electric arc reactor and process. The drawback of the arc process is the high cost of utilities, such as electricity, required to generate the "arc" or plasma. As a result, this process is limited to small units integrated with supplies of "cheap" electricity, such as a hydroelectric plants or nuclear facilities.
The fourth technique involves a thermal pyrolysis reactor. Thermal pyrolysis reactors involve heating a solid material (e.g., by combustion) and using the heated solid material to provide heat to crack the pyrolysis feed (e.g., via pyrolysis chemistry alone). In the thermal pyrolysis processes, the combustion products are typically maintained separate from the pyrolysis hydrocarbon products or effluent. This pyrolysis technique involves various different types of reactors, such as a furnace (e.g., as used in steam cracking), a regenerative reactor (e.g., as used in the Wulff process) and others. For instance, thermal cracking is generally described in various references, such as U.S. Pat. Nos. 7,138,047 and 7,119,240. U.S. Pat. No. 7,119,240 describes an exemplary process for the conversion of natural gas into ethylene. In this process, natural gas is cracked in a furnace, actively quenched, and processed in a reactor to produce ethylene. As another example, U.S. Pat. No. 7,138,047 describes another steam cracking process that mixes a hydrocarbon feed with a dilution steam, flashing the mixture, and vaporizing a portion of the mixture in a pyrolysis reactor. In the process, the pyrolysis feed is passed through tubes in the radiant section of a pyrolysis reactor to crack the pyrolysis feed without contaminating it with combustion products. However, due to the nature of a tubular (metal) furnace, steam cracking is limited to effective cracking temperatures of below 1000° C. and residence times of≧100 milliseconds (ms), which do not allow conversion of either methane or aromatics, thereby limiting the feedstock selection. In addition, energy or furnace heat not used in cracking is partially lost in the furnace flue gas or in the quench, as products are quickly cooled to stop undesired reactions.
The "Wulff" reactor, as described in the IHS, SRI Consulting's Process Economics Program "Acetylene" Report Number 16 (1966) and 16A (1982) along with U.S. Pat. Nos. 2,319,679; 2,678,339; 2,692,819; 3,024,094, and 3,093,697, uses a reverse-flow pyrolysis reactor, which is typically operated at temperatures of<1400° C., to produce olefins and alkynes, such as acetylene. The pyrolysis feed is heated by refractories which have previously been heated by combustion reactions. The pyrolysis feed is cracked, and then cooled outside of the reactor. The relatively slow quenching is a characteristic of the Wulff process that leads to coke and soot formation from using inefficient indirect heat transfer (e.g., from checker brick). Coke formation in the reactor provides fuel during the combustion cycle and excess coke or soot may be alleviated by using a light feed, i.e., a hydrocarbon containing a high proportion of hydrogen. However, because the indirect heat transfer limits the rate of heat input in the Wulff process, certain pyrolysis feeds, such as methane, may not be economically processed, which limits the feed flexibility for this process. As a result, these reactors typically have limitations, such as poor heat transfer and greater soot generation resulting in poorer selectivity to desired products.
While the prior art describes using different pyrolysis reactors, these reactors described include various limitations, which reduce the efficiency of the process. For example, steam cracking is efficient in converting naphtha, but not efficient in converting methane. Likewise, certain high temperature pyrolysis techniques are more effective in converting methane, but too expensive to effectively convert naphtha. Accordingly, it is desirable to provide a process that converts hydrocarbon feeds into olefins, such as ethylene, in an enhanced manner with different reactors types to efficiently convert a broader range of feed molecules. In particular, it is desirable to provide a configuration that provides flexibility in the hydrocarbon feed utilized for olefin recovery. Accordingly, various combinations of different pyrolysis reactors are envisioned, where each type of pyrolysis reactor may efficiently crack a preferred portion of a hydrocarbon feed, which are described further below. These pyrolysis reactors may be coupled together with each of the reactors being associated with a different portion of the hydrocarbon feed.

Method and apparatus for converting hydrocarbons into olefins


The invention provides a process for efficient and reliable preparation of organic peroxides, preferably dialkyl peroxides, peroxycarboxylic acids, peroxycarboxylic esters, diacyl peroxides, peroxycarbonate esters, peroxydicarbonates, ketone peroxides and perketals with the aid of at least one static micromixer and an apparatus for performing the process.

1. Field of the Invention
The invention provides a process for efficient and reliable preparation of organic peroxides, preferably dialkyl peroxides, peroxycarboxylic acids, peroxycarboxylic esters, diacyl peroxides, peroxycarbonate esters, peroxydicarbonates, ketone peroxides and perketals with the aid of at least one static micromixer and an apparatus for performing the process.
2. Description of Related Art
Organic peroxides are very reactive chemical substances. Since they decompose readily to extremely active free radicals and oxygen, they are used as initiators in the plastics and rubber industry. Fields of use of the organic peroxides are the polymerization of monomers for plastics production, the crosslinking and the modification of polymers, and the curing of polyester resins. In addition, organic peroxides are used as oxidizing agents in medical preparations and for complicated chemical syntheses.
A significant feature of organic peroxides is the SADT (Self-Accelerating Decomposition Temperature). It is the lowest temperature at which self-accelerating decomposition in the transport packaging can occur. A dangerous self-accelerating decomposition reaction, and under unfavorable circumstances explosion or fire, can be caused by thermal decomposition at or above the temperature specified. Contact with incompatible substances and also increased mechanical stress can cause decomposition at or below the SADT.
Organic peroxides are now prepared by continuous or batchwise processes (Chem. Ztg. 98 (tg. 12), 583 (1974), W. Mayr. Ullmann's encyclopedia of industrial chemistry, 6th edition, vol.25, 463 (2002)), DE 698 12 430 T2, DE 699 04 337 T2 or else U.S. Pat. No. 6,268,523. A typical example is the preparation of tert-butyl peroxy-2-ethylhexanoate. This organic peroxide is prepared from tert-butyl hydroperoxide and 2-ethylhexanoyl chloride at a temperature below 35° C. (=SADT) and an average residence time of up to 2 hours in a 500 kg reaction batch in a stirred tank. Specifically, the following illustrative reaction schemes are relevant for the preparation of individual peroxide classes:
Acid chlorides and hydrogen peroxide form diacyl peroxides:

Chloroformates and hydrogen peroxide form peroxydicarbonates:

Acid chlorides and organic hydroperoxides form peroxyesters:

Chloroformates and organic hydroperoxides form percarbonate esters:
where R is any organic radical.
A significant parameter in the preparation of organic peroxides is optimal temperature control while maintaining the required residence time for the reaction. Experience has shown that the required reaction temperature is in the range of the aforementioned SADT, such that localized exceedance of the reaction temperature in the reactor, which can lead to uncontrollable decomposition of the reaction mixture or of the reaction products, must be prevented. This likewise leads to long reaction times. In the known preparation processes, large amounts of a few hundred liters of the very reactive and explosive reaction mixture accordingly have to be maintained with maximum turbulence in vessels or other reaction systems. This procedure entails a not inconsiderable level of special safety devices, for example in the temperature and turbulence monitoring sector.
Moreover, to increase the reaction safety, the reaction has to be performed at high dilution. This gives rise to a significant additional employment of diluent and a corresponding requirement for downstream removal, purification and workup processes. In addition, this slows the reaction and also the overall preparation process. Furthermore, virtually all preparation methods are biphasic reactions, since the reactants are not entirely miscible with one another. In order to achieve a sufficient reaction rate, intensive finely dispersed mixing of the two phases is necessary. This can be achieved only insufficiently, for example, in a conventional stirred tank reactor. Preparation in other static mixers or tubular reactors is inadvisable, even with incorporation of pressure release devices, for reasons of inhibition of the explosive organic peroxides.
DE 69618646 T2 discloses continuous and batchwise processes for preparing acyl peroxides. In these processes, vigorous stirring of the reactants by means of jet mixers, static mixers or else ultrasound mixers is intended to avoid problems with the stability of the reaction mixtures.
In the continuous processes, yields up to a maximum of 95.5% can be achieved, while the advantage is at shorter reaction times in the batchwise processes, but this is at the expense of the product yield.
Accordingly, no process which enables the preparation of organic peroxides without the above-described disadvantages, i.e. safe and rapid preparation in a high yield, is known in the prior art.

Method for the production of organic peroxides by means of a microreaction technique

Pergan Hilfsstoffe fur Industrielle Prozesse GmbH


A vehicle front camera module integrated with a rearview mirror includes a windshield bracket module fixed to a central upper end of a windshield of a vehicle, a camera module fixed to the windshield bracket module and at which a pair of lenses for taking forward images of the vehicle are disposed to be laterally spaced apart from each other, and a rearview mirror coupled to the windshield bracket module through a supporter which is coupled to the windshield bracket module in front of the pair of lenses and extending downward so as not to interfere with respective angles of view of the pair of lenses. This arrangement enables the camera module to have a compact design with improved visibility for a safe driving experience.

1. Field of the invention
The present invention relates to a vehicle front camera module integrated with a rearview mirror, and more particularly, to a vehicle front camera module integrated with a rearview mirror, in which a camera module for taking a forward image of a vehicle in a direction of travel and a rearview mirror for displaying the image captured by the camera module or for reflecting and projecting a rear view image of the vehicle to a driver or passenger depending on a user selection are integrally incorporated so as to enable a compact design, wherein the rearview mirror is disposed so as not to interfere with viewing angles of the camera module.
2. Description of the Related Art
A vehicle is typically provided with side mirrors installed at both sides of a vehicle body and a rearview mirror installed at a front and upper position of a vehicle interior in order to assure a driver's clear field of view during forward and rearward traveling.
The recent trend is that a black box device equipped with a camera for taking a forward image of a vehicle in a direction of travel is provided at a front position of a vehicle interior so as to analyze causes of accidents occurring during driving of the vehicle or parking of the vehicle using images stored in the black box device.
The camera, which may be considered as an essential component for taking the overall situation in front of a vehicle, is typically fixed to an upper area of a windshield via an additional coupling element in order to assure a sufficient field of view.
The black box device may be provided with a display unit for displaying an image captured by the camera depending on a user selection.
In such a conventional vehicle which is constructed in the above manner, since a rearview mirror and a black box device are discretely disposed at separate positions of a windshield and thus interfere with a user's field of view during driving, they may cause an accident during driving.
Furthermore, since a camera of the black box device serves only to take and store a forward image of a vehicle in a direction of travel but does not serve to analyze a specific object in a captured image or to detect risk factors, an application range of the device is limited.
In addition, although a black box device should be inevitably provided with a display unit as described above, a front area of a vehicle interior corresponding to a front area of a driver's seat and a front passenger's seat should be previously provided with various observation instruments such as an instrument cluster assembly, a navigation device and an AVN system which are inevitably required for reliable driving, thus making it difficult to assure safe driving.

Vehicle front camera module integrated with rearview mirror


An apparatus for controlling energy from a skylight of a structure including a plurality of vanes positioned beneath the skylight and angularly adjustable to control solar radiation entering the structure through the skylight. The vanes are substantially S-shaped. A first light sensor is disposed proximate the skylight side of the vanes for providing a signal over time representative of changing incident solar radiation at the skylight side of the vanes, and a second light sensor disposed proximate the structure side the vanes for providing a signal over time representative of changing incident solar radiation at the structure side of the vanes. A control assembly is operably connected to the vanes for automatically controlling the angle of each of the vanes in response to the signals of the first and second light sensors which signals vary due to changes in incident solar radiation over time. A light deflecting member is positioned below the vanes a selected distance so as to cause a first portion of the light that passes through the vanes to be reflected toward the ceiling of the structure and a second portion of the light to pass directly toward the floor of the structure.

1. Field of the Invention
The present invention relates generally to a light control apparatus, and more particularly, but not by way of limitation, to an apparatus for a skylight that uses solar radiation as the control parameter and as the power source for automatic adjustment of shade devices to control solar energy entering a structure through the skylight.
2. Brief Description of Related Art
Skylights were widely used to provide light to industrial and warehouse buildings before the widespread use of fluorescent lighting. Around 1995, "big box" retailers began to install skylights over product sales areas. The original objective was to improve the appearance of products by admitting daylight. Natural light has a color rendition index (CRI) of 100%. Thus, products were more appealing than when viewed under the weak fluorescent or high intensity discharge lighting then in use with CRI's of around 40-60%. In addition, natural light reduces the cost of artificial lighting, which accounts for 40% to 50% of the energy consumption in many commercial buildings. When sufficient natural light or daylight is available, a good daylighting system can significantly reduce artificial lighting requirements and the associated energy costs.
While skylights perform well in both improving the quality of store lighting and reducing the need for artificial lighting, they have a significant disadvantage. Daylighting is composed of the visible light spectrum plus direct solar gain. Direct solar gain increases air-conditioning loads resulting in increased utility costs.
The skylight industry does not have any advanced technology in the control of solar loading. The approaches used so far include adding tint to the skylight and thereby increase the shading coefficient. The problem with this solution is that it, in turn, decreases the light admitted into the structure. The window industry has also responded to government insistence in the form of low-e glazings and thermal blocking frames.
Technologies to provide active control, such as electro-chromic glazing (ECG), which has been in development for the past ten years and still not available to the mass market, are extremely expensive. While ECG will limit solar heat gain through windows it still will not optimize daylighting. Further, it offers no solution to the retro-fit market, nor does it offer any fire resistance.
To this end, a need exists for an apparatus for controlling solar energy entering a structure through a skylight which uses solar radiation as the control parameter. It is to such an apparatus and method that the present invention is directed.

Apparatus for controlling energy through a skylight

The Board of Regents of the University of Oklahoma


A stent and method comprising inserting within a vessel an unexpanded stent that includes a first zone comprising a plurality of adjacent ring elements, not less than three in number, that are distributed along the stent with a first spacing, and a second zone comprising a plurality of adjacent ring elements that are distributed along the stent with a second spacing, and expanding the stent to cause the plurality of ring elements in the first zone to redistribute to a third spacing that is smaller than the first spacing and to cause ring elements in the second zone to distribute to a fourth spacing larger than the first spacing.

The present invention relates to stents having a radial stiffness that varies along the length of the stent. Specifically, the invention relates to a stent that actively changes the density of rings in different zones along the axial length of the stent when the stent is expanded from a compressed condition to an expanded condition.
Surgical stents have long been known which can be surgically implanted into a body lumen, such as an artery, to reinforce, support, repair or otherwise enhance the performance of the lumen. For example, in cardiovascular surgery it is often desirable to place a stent in the coronary artery at a location where the artery is damaged or is susceptible to collapse. The stent, once in place, reinforces that portion of the artery allowing normal blood flow to occur through the artery. One form of stent which is particularly desirable for implantation in arteries and other body lumens is a cylindrical stent which can be radially expanded from a first smaller diameter to a second larger diameter. Such radially expandable stents can be inserted into the artery by being located on a catheter and introduced internally through the arterial pathways of the patient until the unexpanded stent is located where desired. The catheter is fitted with a balloon or other expansion mechanism which exerts a radial pressure outward on the stent causing the stent to expand radially to a larger diameter. Such expandable stents exhibit sufficient rigidity after being expanded that they will remain expanded after the catheter has been removed. An example of a stent known in the art is shown in FIG. 4 and FIG. 5. With initial reference to FIG. 4, the stent 50 shown there generally comprises a plurality of radially expandable cylindrical elements or rings 52 disposed generally coaxially along the axis 2 of the stent and interconnected by elements 54, 56 disposed between adjacent cylindrical elements. While FIG. 4 shows the stent 50 in a compressed or unexpanded condition suitable for delivery into the vasculature of a patient, FIG. 5 shows the same stent 50 in an expanded condition after placement and expansion in the vasculature.
Yet, known prior art stents suffer from a variety of drawbacks when certain types of deficiency or damage in an artery is encountered by a surgeon. For example, a surgeon may encounter an arterial situation where a stent is required to have greater radial support stiffness at the ends of the stent, and less radial support stiffness in the middle between the two ends. Another situation may be encountered requiring a stent having a greater radial support stiffness in the middle, and less radial support stiffness at the ends.
Certain stents have been developed to satisfy these requirements, but they suffer from drawbacks. For example, one approach describes a stent with greater radial support stiffness in the middle of the stent, wherein the struts are made thicker in the middle of the stent and thinner towards the ends. Another approach describes a stent with varying radial strength, wherein the desired effect is accomplished by increasing the width of the struts, or increasing the length of a cylindrical element. Yet another approach describes a stent in which the structural members are provided with regions having different widths, and tapering widths of selected segments. However, these solutions may result in a stent that is expensive to manufacture, and has non-uniform bending characteristics about the longitudinal axis and this latter aspect may introduce complications during delivery. Yet another approach describes a stent of differentiated stiffness that is achieved with the use of a superelastic material that transitions between a relatively soft and malleable phase to a stiffer phase at a transition temperature that is adjustable along the length of the stent. By differentially adjusting the transition temperature of different portions of the stent, a differentiation in the stiffness of the structure is achieved upon the stent being subjected to body temperature. However, this solution entails complex differentiated metallurgical application in a single stent in order to achieve the desired result.
Thus there is a need in the art for a simple and effective stent that possesses varying degrees of radial support stiffness over its length, that is easy to manufacture, and has substantially uniform longitudinal flexibility. The present invention addresses these and other needs.

Stent with actively varying ring density


A support system for tents and other shelters. The support system includes base support members that are in the shape of an arch. These base support members are secured in a desired configuration by an upper support member that is in the shape of a circle or other geometrical shape. A roof support may be added as well. The size and configuration of the shelter may be easily changed by adding or deleting the number of base support members.

Tents are used for a wide variety of purposes ranging from camping, for storage, for day use shelters, for commercial purposes and many other purposes. Each use typically requires a particular size, shape and configuration. For example, a camping tent may range from a small backpacking tent to a larger expedition tent to a multiple person family style tent. A backpacking tent may include two or more support poles that are supported together by tent materials and tensioning cords. A larger expedition tent may require multiple poles that require tensioning cords. The structures that support these tents are relatively complex to assembly and are not free-standing without the tent covers and/or tensioning cords. The larger family style tents and even commercial use tents require multiple components and the use of tension cords and stakes. Also, the roof structure is designed as part of the tent and is not able to changed.
Another area that is currently being expanded is the use of a tent structure to expand the use of vehicles. For example, it is becoming popular to use a tent structure with a camping vehicle such as a recreational vehicle or camping trailer to create more usable space. The tent structures currently being used tend to be complex and only suitable for a particular vehicle.
Another area where tent structures are becoming popular is as temporary or semi-permanent storage facilities. Often it is desirable to store equipment, vehicles or other items in places where no permanent storage is available. However, most of these temporary structures are complex and not easily set up.
Each different use normally requires an additional tent. This can become expensive as well as requiring space for storage and transport. Additional tents may be required if additional space is needed. Also, an existing tent may be too large for many purposes.
There presently is a need for a tent support system that may be configured in many different shapes and sizes and for many different purposes.


An assist device which is applied to a treatment instrument including an insertion body to be inserted through a channel of an endoscope, and which is configured to assist movement of the insertion body relative to the channel, includes: a flexible tube including a passage into which the insertion body of the treatment instrument is inserted; a connector provided on the flexible tube and configured to connect to the endoscope to allow communication between the channel and the passage; a first retainer provided on the flexible tube and configured to hold an outer circumference of an insertion section of the endoscope or an outer circumference of an operation section connected to the insertion section; and a second retainer being movable relative to the first retainer and configured to hold the insertion body of the treatment instrument.

1. Field of the Invention
The present invention relates to an assist device which is attached to an endoscope to assist an operation of a treatment instrument, and also to an endoscope system including the assist device.
2 Description of the Related Art
A treatment instrument, which is configured to be inserted. through a channel of an endoscope, may be inserted into the channel or removed therefrom by a person other than the operator of the endoscope, an as to the operator. If the operator can operate the treatment instrument without the help of the assistant, this would enhance the efficiency. For example, International Publication No. 2013/065509 discloses an assist device including an operation member that enables the operator to insert a treatment instrument into a channel and remove the treatment instrument from the channel (namely, an advancing operation and a retreating operation) by himself or herself. A fixing member of this assist device is attached (fixed) to the outer circumference of the insertion section of the endoscope.


A wiping arrangement for wiping a vehicle window has a rotatable output shaft, a wiper shaft connected with a wiping element, and pendulum elements for converting the rotary movement of the output shaft into the pendulum movement of the wiper shaft. The pendulum elements include a crank member connected with and rotatable by the output shaft, a rocker arm connected with the wiper shaft, and a connecting rod which is pivotally connected with the crank member and the rocker arm. Elements are provided which allow swinging of the connecting rod even when the wiper shaft is blocked, for example as a result of snow accumulation in the region behind the wiper shaft. Thus, the connecting rod can swing about a hinge which connects the same to the rocker arm, and thereby the crank member can rotate despite the blocking of the wiper shaft.

The present invention relates to a wiping arrangement for wiping a vehicle window.
Wiping arrangements for wiping vehicle windows are widely used. In known wiping arrangements in condition of snow-fall, snow is moved by a wiping element of the arrangement to marginal regions of an area of the vehicle window to be wiped and continuously reduces this area until the arrangement is blocked. This leads to premature deflection of the hinges of the pendulum drive of the arrangement, to deformation of rods of the pendulum drive and occasionally to breakage of an electric motor of the arrangement.

Wiping arrangement for wiping a vehicle window


Energy transfer dyes, their preparation, and their use as labels in biological systems is disclosed. The dyes are preferably in the form of cassettes which enable their attachment to a variety of biological materials. The dyes and the reagents that can be made from them offer a wide variety of fluorescent labels with large Stokes' shifts enabling their use in a variety of fluorescence applications over a wide range of the visible spectrum.

The following describes certain relevant art, none of which is admitted to be prior art to the appended claims.
Various methodologies are available for the visualization of cells or molecules in cells and for the measurement of analyte concentrations in fluids. Fluorescence microscopy utilizes fluorescent dyes, generally connected to specific probes, such as antibodies, for the localization of proteins and complexes in cells.
For the measurement of analyte concentrations, detection of an analyte of interest, determination of the particular sequence of a nucleic acid molecule, immunoassays and various hybridization methods have become popular over the last 40 years. Radioimmunoassays were developed because the high specific activity of the radionucleotide allowed measurement of very low concentrations of analyte. However, because of the concerns for the environment and human health, the use of radionucleotides in immunoassays is becoming less popular. The use of enzymes in immunoassays to amplify a signal has been a very important advance in the field of immunoassays because their use does not involve environmental or human health hazards or risks. Enzyme-linked immunoassays, however, can be problematic because the activity of the enzyme is temperature dependent and the instability of the enzyme or the substrates can result in inaccurate quantitation of the target ligand. Still other immunoassays monitor fluorescence as the signal, with or without enzymes, for the measurement of analyte concentrations.
Bi-fluorophore energy transfer dyes have been described which provide a novel methodology for monitoring processes in biological systems. The fluorescent nature of such dyes enables them to monitor processes in which the biological systems are involved. The fluorescent signal is measured by a fluorometer which is tuned to excite the fluorescent molecule at a specific wavelength and to measure the emission of fluorescence at another wavelength. The difference in the excitation and emission wavelengths is referred to as the Stokes shift.
Previously, a variety of combinations of bi-fluorophore dyes have been described. U.S. Pat. No. 5,688,648, entitled "Probes Labelled with Energy Transfer Coupled Dyes" Mathies et al., filed Dec. 19, 1995, which is incorporated herein by reference in it's entirety, including any drawings, discloses sets of fluorescent labels carrying pairs of donor and acceptor dye molecules wherein the labels can be attached to nucleic acid backbones for sequencing. Included is a method for identifying and detecting nucleic acids in a multi-nucleic acid mixture by using different fluorescent labels, wherein the fluorescent moieties are selected from families such as cyanine dyes or xanthenes. The fluorescent labels comprise pairs of fluorophores where one fluorophore donor has an emission spectra which overlaps the fluorophore acceptor's absorption so that there is energy transfer from the excited member to the other member of the pair.
UK Patent No. 2301 833 B entitled "Fluorescent Labelling Complexes with Large Stokes' Shifts Formed by Coupling Together Cyanine and Other Fluorochromes Capable of Resonance Energy Transfer" Waggoner et al., filed May 30, 1996, which is incorporated herein by reference in it's entirety, including any drawings, discloses complexes comprising a first fluorochrome having first absorption and emission spectra and a second fluorochrome having second absorption and emission spectra. The linker groups between the fluorochromes are alkyl chains. The fluorescent nature of the dyes enables them to be of use in sequencing and in nucleic acid detection.
In bi-fluorophore dye construction, aspects of particular importance are the distance between the acceptor and donor molecules, and the structure of the linker groups. There remains a need for additional improvements in dye construction, for example in order to accommodate selection of biological molecules of various sizes.


Systems and methods are provided for performing a search based on a snapshot image captured from media content presented to a user. The snapshot image contains features of the media content that the user wishes to target for the search. A search system recognizes features of the snapshot image and creates a search query based on the snapshot image. The search query is used to identify features of the snapshot image, and search results related to the identified features are presented to the user. Supplemental data or user input received with the snapshot image may be used in analyzing and identifying features of the snapshot image.

The present invention relates generally to performing a search based on media content, and more particularly, to performing a search based on a snapshot image captured from media content.
Image-based search systems can be utilized to perform a search using an image that contains features relevant to the search. A search system may analyze an image received from a user to recognize and identify features in the image. To identify the features, the search system may use patterns in the search image to locate other images that exhibit similar patterns. When an image with a suitable level of pattern similarity is found, the search system uses known information for the image to identify the similar feature in the search image. The identified feature is then presented to the user.
Image matching systems may often include a large number of images and information that can be used to find matches for search image features. The feature matching algorithm can be slowed by the number of images available as each image is compared individually to the search image. Identifying features contained in search images may include comparing the features with many potential matching images, and the search system may require a large amount of memory and/or time to perform the search. If images with very similar features are available, the search system may have difficulty selecting one image as a match and may return a false match containing features that are very similar but not the same as features in the search image. Accordingly, it would be desirable to provide an image-based search system that is capable of performing an efficient search based on an image captured from media content.

Systems and methods for performing a search based on a media content snapshot image


A condenser is provided that makes a liquid droplet of a liquid phase medium drop effectively, the liquid phase medium residing in a lower end opening of a medium passage of the condenser, thereby preventing any degradation in the performance of the condenser. In the condenser, vapor, which is supplied to a cooling pipe (14) connected to cooling fins (16), is cooled, condensed into water, and recovered in a water-collecting tray (21) provided beneath the cooling pipe (14), and a needle-shaped member (24) provided so as to face the lower end opening of the cooling pipe (14) ruptures the droplet that, due to surface tension, resides in the lower end opening of the cooling pipe (14) and makes it drop into the water-collecting tray (21). A plate-form filter can be used instead of the needle-shaped member (24), and in this case not only can the droplet be made to drop from the lower end opening of the cooling pipe (14) more effectively due to the capillary action of the filter, but also dust contained in the water can be removed.

Japanese Patent Application Laid-open No. 58-48076 discloses a Rankine cycle system comprising a vane-type expander. This converts the pressure energy of high temperature high pressure vapor generated in a vaporizer employing a gas burner as a heat source into mechanical energy via a vane-type expander, and the vapor thereby generated, whose temperature and pressure have decreased, is condensed in a condenser and then returned to the vaporizer via a water supply pump.
As shown in FIGS. 9A to 9C, a condenser that condenses and coverts a gas phase medium into a liquid phase medium generally comprises a large number of cooling fins 01 that are stacked with gaps through which a cooling medium can pass, and a large number of cooling pipes 02 that run vertically through these cooling fins 01, the gas phase medium supplied from the upper end of the cooling pipe 02 being drained of heat by the cooling fins 01, so as to condense into the liquid phase medium while passing through the interior of the cooling pipe 02, and dripping from the lower end of the cooling pipe 02.
In order to reduce the dimensions of the condenser for condensing and converting a gas phase medium into a liquid phase medium and maintain a high level of heat exchange per unit volume with the gas phase medium, it is necessary to reduce the diameter of the cooling pipe 02, but when the cooling pipe 02 is narrow, it is easy for a droplet D that has been formed into a sphere from the liquid phase medium due to surface tension to reside in the lower end of the cooling pipe 02 under the influence of the surface tension and it becomes difficult for it to drop. When the lower end of the cooling pipe 02 is blocked in this way by the droplet D, it becomes difficult for the gas phase medium to flow through the interior of the cooling pipe 02, thus greatly degrading the performance of the condenser, and it is therefore necessary to remove by some means the droplet D residing in the lower end of the cooling pipe 02.


A computer-implemented method for performing radiation dose assessment includes acquiring a plurality of parameters related to an image scanner configured to apply a heat or radiation dose to a subject during imaging. A plurality of features is extracted from the plurality of parameters. A dose map of a region of interest in the room is generated by applying a machine learning model to the plurality of features and the interventional room scene.

With the growing use of interventional imaging, concerns about increased exposure of the operators to ionizing radiation have become more prominent. Concern about increasing exposure to radiation is one of the biggest challenges facing radiology towards the future. Another major source of concern is studies which show a very wide degree of variation in the levels of exposure for the same procedure across different centers.
Currently, operator exposure to radiation exposure is handled by having operators wear a mobile dosimeter, such as the RaySafe i2 system. This system has been incredibly useful in increasing awareness of the radiation exposure. However, the radiation exposure is only measured at a single location. It is well known that the exposure can vary greatly across the operators' skin surface based on the C-arm angulation, the scan parameters, whether or not any shielding or protective devices are used, etc. For instance, studies indicate that the left and middle parts of the cranium received significantly higher doses than the right part for interventional cardiologists. The information provided by dosimeters, while valuable, cannot handle this heterogeneous nature of radiation distribution.
Monte-Carlo methods are considered the most accurate method of estimating the transport of radiation. Monte Carlo methods use discrete simulation of millions of individual particles (primarily photons and electrons), using stochastic models for simulating the transport of radiation along with different scattering modes like Rayleigh scattering and Compton scattering. In regions with tissue, the simulation can provide detailed information about the deposited radiation energy as the particles move through the tissue. Historically, these methods have been computationally expensive, requiring powerful supercomputers for generating results. With modern developments in computer architecture and graphical processing units (GPUs), powerful simulations can now be carried out in a few minutes on standard computing workstations.
For applications such as radiation therapy planning, where there is no urgent clinical need for real-time dose computation, such GPU based Monte Carlo simulation engines are sufficient. However for real-time applications that typically arise during image acquisition, such as planning an X-ray based image acquisition (e.g., Computed Tomography, C-arm CT etc.), dose calculation that take multiple minutes are not practical. In a dynamic operating environment, there is a need to update (in real-time) the dose map in an imaging room to alert the operators and provide real-time feedback on the dose received by the patients and/or by the operator.

Machine learning based real-time radiation dose assessment


A magnetic-tape-cassette apparatus (1) includes a head-mounting plate (10) and a magnetic head (3) arranged on the head-nounting plate (10) and having a cylindrical tape-contact face (12) and an air gap (25). The magnetic head (13) forms part of a head unit comprising a head support (16) which, viewed in the direction of tape transport, includes a tape guide (18) before and after the magnetic head (13), which tape guide has cylindrically curved guide surfaces (21) which at one side are bounded by alignment surfaces (23) at one of their axial ends. Each of the guide surfaces (21) is adjoined by a control edge (24) which is inclined relative to the guide surface (21) to urge the magnetic tape against the relevant alignment surface (23) during tape transport, the axial length of the guide surfaces (21) being smaller than or equal to the tape width (b). At a distance fromthe guide surface (21) each control edge (24) of the head support (16) changes to a movement-limiting surface (26), the distance between the facing alignment surface (23) and movement-limiting surfaces (26), starting from the transition (27), being greater than the tape width (b) in such a way that as the magnetic tape (11') is lifted off the guide surfaces (21) while the magnetic tape remains in contact with the tape-contact face (12) of the head (13) the position of the magnetic tape (11') in the direction of its width (22) is limited with play, said distance increasing from the centre of the relevant movement-limiting surface (26) towards its lateral edges (26a, 26b).

The invention relates to a magnetic-tape-cassette apparatus comprising a head-mounting plate and a magnetic head arranged on the head-mounting plate and having a cylindrical tape-contact face and air gap, the magnetic head forming part of a head unit comprising a head support which, viewed in the direction of tape transport, comprises a tape guide situated before and after the magnetic head and having cylindrically curved guide surfaces bounded at one side by alignment surfaces at each time one of its axial ends, an imaginary surface connecting the alignment surfaces extending perpendicularly to a plane through the air gap, a control edge adjoining each of the guide surfaces at the other axial end and being inclined relative to the guide surfaces to urge the magnetic tape with one end against the relevant alignment surface during tape transport, and the axial length of the guide surfaces being smaller than or equal to the tape width.
Such a magnetic-tape-cassette apparatus comprising a head unit and a support forming part of the head unit is known from EP-PS 0,120,518 . The advantage of the head support in this magnetic-tape-cassette apparatus is that the magnetic tape is always in the correct azimuth position during its transport over the tape-contact face. This is important when prerecorded tapes are used, which have been recorded on other apparatuses. For a correct reproduction the azimuth position of the magnetic-tape-cassette apparatus should correspond to the azimuth position of the recording apparatus. Moreover, the manufacturer of the magnetic head can manufacture the head together with the support as a complete unit. The manufacturer of the apparatus then need no longer carry out any azimuth adjustments.
When the tape is thus guided the tape runs from one tape-guide surface directly before the magnetic head past the type-contact face of the magnetic head towards the tape-guide surface directly after the head. The tape in this tape path is slightly curved and is tautened. This stiffens the tape, so that the control edges can perform their control function in that they urge the magnetic tape in one direction against the alignment surfaces. In the Cue or MSS (Music Sensing System) mode, which is used for pause detection, the magnetic head is withdrawn. The tape is then no longer urged against the alignment surfaces.
From US-PS 4,646,186 it is known to arrange a pair forks, which serve to provide tape guidance in the play mode and whose tooth spacing corresponds substantially to the tape width, in the proximity of the magnetic head and to arrange a tape-guide fork having a larger tooth spacing and intended for the Cue mode further away from the magnetic head. When the magnetic head is withdrawn only the last-mentioned tape-guide fork is active. The tape guidance at the head will then be lost. At higher tape speeds this may give rise to oscillations, which may impair the reproduction of the signals from the audio track or even result in damage to the tape edges.

Magnetic head mounting plate with tape movement limiting surface


A piston-cylinder unit including a cylinder in which a piston is guided so as to be displaceable axially, wherein the piston separates the cylinder into two work spaces which communicate via at least one bypass groove in the cylinder depending on the stroke position of the piston, wherein the cylinder is formed of multiple parts and a portion of the cylinder with the at least one bypass groove is displaceable axially relative to at least one further portion of the cylinder.

1. Field of the Invention
The invention is directed to a piston-cylinder unit of the type wherein the piston separates the cylinder into two work chambers which communicate via a bypass groove in the cylinder depending on piston stroke position.
2. Description of the Related Art
xe2x80x9cMotor Vehicle Shock Absorber [Kraftfahrzeugstoxcex2dxc3xa4mper]xe2x80x9d, Bibliothek der Technik, Vol. 185, Verlag Moderne Industrie, pages 38 to 41, discloses a piston-cylinder unit which has a stroke-dependent damping based on at least one bypass groove in the cylinder. This proven method of stroke-dependent damping has the disadvantage that vehicles with different empty weights, e.g., because of differences in their outfitting, cannot make use of a part of the bypass groove and, therefore, cannot make use of a region of the comfortable stroke position of the shock absorber. It is endeavored, when the vehicle is stationary, to move the piston out as centrally as possible within the bypass groove. In vehicles with leveling control, this task is taken on by a supply system which raises or lowers the vehicle body in relation to the vehicle axis. A leveling control cannot be used for many vehicles and applications, for example, because of excessive technical expenditure.
It is the object of the present invention to provide a piston-cylinder unit with at least one bypass groove between the work spaces in which the problem known from the prior art is overcome.
According to the invention, this object is met in that the cylinder is formed of multiple parts and a portion of the cylinder with the at least one bypass groove is displaceable axially relative to at least one further portion of the cylinder.
With this very simple method, the bypass groove can be displaced within limits independent from a normal position of the piston without great expenditure. Accordingly, in a vibration damper in a vehicle, the bypass groove can be adapted to the normal position of the vehicle when the vehicle is stationary.
However, application is not restricted only to vibration dampers. Bypass grooves are often used in air springs, e.g., as employed in vehicle flaps, and correspond to an opening angle of the vehicle flaps. When the bypass groove is displaced, the opening angle also changes.
In a further construction, the cylinder has a first portion which is guided coaxially inside a second portion.
The second portion of the cylinder advantageously has a base and the first portion carries a piston rod guide for a piston rod.
In order to ensure a continuous adjustment of the position of the bypass groove, the two portions of the cylinder are connected with one another via a thread.
The two portions of the cylinder are clamped via a retaining screw for operating reliability.
According to a feature of the invention, the first portion and the second portion of the cylinder overlap or cover one another, at least one seal being arranged in this area.
Further, the second portion of the cylinder has an adjusting length area having a fastening thread for the retaining screw.
In an application of a vibration damper indicated by way of example, it is possible that an axially movable dividing or separating piston which separates a work space from a compensation space is arranged inside the second portion of the cylinder. Accordingly, there is a larger cross-sectional surface available for the separating piston, so that a gas pressure in the compensation space can be comparatively small.
In another construction, the portions of the cylinder which are displaceable relative to one another have at least one axial projection and a recess or cutout in the direction of the longitudinal axis of the piston-cylinder unit which engage one inside the other, the length of the at least one bypass groove being changeable with the position of the projection within the cutout.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

Piston-cylinder unit with at least one bypass groove in the cylinder


Disclosed are various embodiments for providing a people search that uses proximity in ranking results. A search query for a person is obtained from a user. The search query is executed on a directory comprising profiles that each correspond to a respective person. Resulting profiles that match the search query are thereby obtained. The resulting profiles are ordered based at least in part on a measure of proximity of each respective person to the user.

Within a large organization, it may be difficult to keep track of email addresses, telephone numbers, and/or other information associated with employees. To this end, an employee directory may be provided to enable users to search for a profile and/or information associated with a specific employee. However, users sometimes may not know the full name of the employee for whom they seek information. For example, a user may search in the employee directory for an employee with only the first name of the employee.


A figurine system having interchangeable appendages features a body component having a general shape of a body of an animal. A body anterior end features a female head component slot. A body posterior end features a female tail component slot. A body first side features a female first anterior limb component slot and a female first posterior limb component slot. A body second side features a second female anterior limb component slot and a female second posterior limb component slot. The system features a head component, a tail component, a first anterior limb component, a first posterior limb component, a second anterior limb component, and a second posterior limb component. The system features a plurality of adapter components.

Toys resembling animals have been around for many years. Many of these toys feature movable parts or removable and replaceable parts to stimulate the learning experience for the child. The present invention features a figurine system featuring different types of animals having interchangeable appendages.
Any feature or combination of features described herein are included within the scope of the present invention provided that the features included in any such combination are not mutually inconsistent as will be apparent from the context, this specification, and the knowledge of one of ordinary skill in the art. Additional advantages and aspects of the present invention are apparent in the following detailed description and claims.


Embodiments of a rope tension device for cinching a load with a rope are disclosed. The rope tension device includes a frame and brake member. The frame includes a first rail and a second rail with a bracing structure extending between the first rail and the second rail such that the bracing structure defines an arcuate surface. The brake member is pivotably coupled to the frame. Further, the brake member defines a brake surface such that the brake surface is biased with a spring member toward the arcuate surface, the brake surface defining an axially extending concave feature that faces the arcuate surface of the bracing structure. With this arrangement, a gap defined between the arcuate surface and the axially extending concave feature varies in height along an axial width defined between the first and second rails so as to receive the rope within the gap for cinching the load.

Various versions of cam buckles have been provided over the years for obtaining a mechanical advantage to increase a tension force in a flat strap with a given pulling force exerted by the operator. Known cam buckles, such as are described in U.S. Pat. No. 6,877,189, for example, generally provide a cam portion spring biased against an opposing structure between which a flat strap may be cinched to hold a tension force in the flat strap. While these versions of cam buckles are effective for flat straps, they are incapable of being effectively employed with lines having a circular cross-section, such as rope. Often rope is the preferred medium for cinching down objects. Various complex rope tension devices have been introduced, but are bulky and/or complex and, therefore, are limited in their applied use and costly to manufacture. For example, rope tension devices employed for clamping to rope are described in U.S. Pat. Nos. 6,092,791 and 6,068,242 both to Kingery, describe effective clamping for tensioning rope, but require multifaceted structures and complex ratcheting mechanisms.
Therefore, based on the foregoing, it would be advantageous to provide a more compact rope tension device without the complexity of the current rope tensioning devices.


The present invention relates to improvements in erasing a flash memory. An object of the present invention is to shorten the erasing time. During pre-erase writing, at least either word lines or bit lines are selected in units of multiple lines at a time, and data are written in multiple selective transistors simultaneously.

The nonvolatile semiconductor memory has an overall configuration, for example, as that shown in FIG. 1. In FIG. 1, N cell blocks 11.sub.1 to 11.sub.N (for example, eight blocks) each having multiple transistor cells are arranged in a row. The cell blocks 11.sub.1 to 11.sub.N are provided with bit line select circuits 12.sub.1 to 12.sub.N and sense amplifiers/sense buffers 13.sub.1 to 13.sub.N respectively.
A row address signal is supplied from a row address buffer to each of the cell blocks 11.sub.1 to 11.sub.N via a row decoder 15. A column address signal is supplied from a column address buffer 16 to each of the bit line select circuits 12.sub.1 to 12.sub.N via a column address decoder 17. A voltage V.sub.S sent from a source power supply circuit 18 is applied to each of source electrodes of the transistor cells of the cell blocks 11.sub.1 to 11.sub.N.
FIG. 2 shows the cell block 11, one of the cells blocks in the aforesaid nonvolatile semiconductor memory, and its peripheral circuitry. In FIG. 2, components identical to those in FIG. 1 bear the same reference numerals, of which a description will be omitted. In FIG. 2, the bit line select circuit 12 comprises n-channel MOS field-effect transistors Q1 to Qn. Column address signals Y1 to Yn are fed from the column decoder 17 to the gates of the transistors Q1 to Qn.
The cell block 11 comprises a total of n by n field-effect transistors Q11 to Qnn having floating gates and control gates. The gates of n transistors Qil to Qin (where, i=1, 2, etc., and n) arranged in tandem are provided with row address signals Xi sent from the row decoder 15 via word lines.
The drains of the n transistors Qli to Qni arranged in tandem are connected to the drains of the transistors Qi in the bit line select circuit 12 via bit lines. Voltage from the source power circuit 18 is applied to each of the sources of the transistors Qll to Qnn. A cell amplifier 13a and a write buffer 13b are connected to each of the sources of the transistors Q1 to Qn.
In the foregoing semiconductor memory, when row addresses Xi and column addresses Yi are selected for writing, data read from the write buffer 13 are written in the transistors Qij of the cell blocks 11.sub.l to 11.sub.N. Writing is performed simultaneously on one bit per each of the cell blocks 11.sub.1 to 11.sub.N or a total of N bits designated with the row addresses and column addresses. Data erasing is performed concurrently on all transistors in the cell blocks 11.sub.1 to 11.sub.N.
In a flash memory, information is retained depending on the presence or absence of a charge in a memory cell. FIG. 3 shows an example of a structure of a memory cell. As shown in FIG. 3, a gate has a two-layered structure consisting of a control gate (CG) 25 and a floating gate (FG) 24. The control gate 25 is connected to a word line WLi and a drain (D) 23 is connected to a bit line BLi. Reference numeral 26 denotes a tunneling oxide film.
The flash memory is broadly divided into two types of what are referred to as NOR and NAND. These types differ from each other in a method of writing, reading, or erasing information into or from a memory cell. Taking the NOR type flash memory as an example, writing, reading, or erasing information into or from a memory cell will be described below.
When information is to be written in a memory cell having the aforesaid structure, as shown in FIG. 4, the word line WLi is set to Vpp (approx. 12 V), the bit line BLi is set to approx. 6 V, and the source S is set to 0 V. High voltage is then applied to the control gate CG and drain D. Current then flows into the memory cell. Part of the electrons flowing through the memory cell are accelerated due to the high electric field in the vicinity of the drain D, gain energy, and then goes beyond the energy barrier of an insulating film of the floating gate. The electrons are finally injected into the floating gate FG. The floating gate FG is not electrically coupled with other circuits, so it therefore can retain charges on a semi-permanent basis.
When information is to be read from a memory cell, as shown in FIG. 5, the word line WLi is set to Vcc (about 5 V), the bit line BLi is set to about 1 V, and the source S is set to 0 V. The memory cell is then selected by specifying the word line WLi and bit line BLi. The threshold value of the cell transistor varies depending on the charges retained in the floating gate FG. Current flowing through the selected memory cell varies depending on the information stored therein. The information therefore can be read out by detecting and amplifying the current.
The voltage levels of the control gate CG, drain D, source S, and substrate PS in the aforesaid operative states are set to the values listed in Table 1.
TABLE 1 ______________________________________ Voltages in modes in a prior art CG D S PS ______________________________________ Reading Vcc to 1 V 0 V 0 V Writing Vpp to 6 V 0 V 0 V Erasing 0 V Float Vpp 0 V ______________________________________
When information is to be erased from a memory cell, as shown in FIG. 6, the word line WLi is set to about 0 V and the bit line BLi is opened. In this state, the drain D is opened, about 0 volt is applied to the control gate CG, and a high voltage of about 12 volts is applied to the source S.
Since a high voltage is applied to the source S, deep diffusion is required in order to increase the resistivity of the diffused layer in the source. This hinders reduction in cell area.
For divided erasing, it is required that the Vss line in the source must partly have a different voltage. This leads to disconnection or an increased number of drive circuits. Eventually, chip size increases.
A solution to the above problem is to apply a negative voltage to the word line WLi. To be more specific, as shown in FIG. 7, a negative voltage (about -10 V) is applied to the control gate CG and Vcc (about 5 V) is applied to the source S. The drain D is opened. Erasing is then executed.
In this case, since a low voltage is applied to the source S, the resistivity of the source need not be intensified. This contributes to reduction in cell size. Partial erasing is enabled by selectively applying negative voltage to the control gates CG.
The aforesaid erasing method is a source erasing method in which charges in the floating gate FG are routed to the source. A channel erasing method is also available, wherein charges in the floating gate are routed to a channel; that is, a substrate. Even in this method, negative voltage is applied to the control gate. The channel erasing method is sometimes employed for the aforesaid NAND-type flash memory.
FIGS. 8 to 11 show the states of a memory cell with voltage applied according to various erasing methods. In FIGS. 8 to 11, the memory cell is an n-channel transistor.
FIG. 8 shows a state in which positive voltage is applied according to a channel erasing method. The drain D and source S are opened, and the control gate CG is set to 0 V. The high voltage Vpp is applied to the P well equivalent to a channel. In channel erasing, a triple-well structure shown in FIG. 8 is adopted because positive bias is applied to the channel.
FIG. 9 shows a state in which a positive voltage is applied according to the source erasing method. The drain D is opened, and then the control gate CG is set to 0 V. The high voltage Vpp is applied to the source S. The substrate is opened or set to 0 V.
FIG. 10 shows a state in which a negative voltage is applied according to the channel erasing method. The drain D and source S are opened, and the control gate CG is set to a negative voltage V.sub.BB. A positive voltage Vcc is applied to the p well equivalent to a channel. V.sub.BB -Vcc is applied between the control gate CG and channel.
FIG. 11 shows a state in which negative voltage is applied according to the source erasing method. The drain D is opened, and then the control gate CG is set to the negative voltage V.sub.BB. The source S is set to the positive voltage Vcc.
The methods for erasing a flash memory which have been described so far, have lots of problems with actual erasing. The problems will be described below.
Erasing of a flash memory is either concurrent erasing, in which all memory cells are erased concurrently, or block-by-block erasing in which erasing is performed block by block. Some of the memory cells to be erased concurrently contain data, while other cells do not contain data. In other words, some cells hold electrons in their floating gates, while other cells do not. If erasing is performed on a memory cell in which no electrons are held, a state in which too many electrons are extracted (that is, a state in which holes are injected) is set up. This is referred to as excessive erasing. When excessive erasing occurs, a "Normally On" state in which a memory cell is on even during normal operation is established disabling normal operation. Pre-erase writing is then performed, wherein data are written in all memory cells before erasing is done. The time required for erasing therefore includes the time required for pre-erase writing. In order to reduce the erasing time, the time required for pre-erase writing must be diminished.
In erasing a flash memory, whichever is adopted; channel erasing or source erasing, voltage applied between the control gate CG and channel or source S greatly affects the erasing. For stable erasing, the voltage to be applied between the control gate and the channel or source must be held constant irrelevant of the fluctuation in external power supply. A memory for a portable device is one of currently conceivable application fields for a flash memory. This kind of portable equipment use batteries as a power supply. When employed for portable equipment, a flash memory is therefore subjected to a voltage fluctuation in an external power supply. Under these circumstances, there is an increasing demand for an erasing method for a flash memory that permits stable erasing irrelevant of a fluctuations in an external power supply, and for a flash memory that can be erased according to the erasing method.
Furthermore, when the source erasing method is employed, the foregoing fluctuation in external power supply may cause the voltage that is applied from a source to vary, or the characteristics of memory cells or drive circuits to differ from one another. As a result, the electric field in the source region becomes stronger and avalanche current increases. When the avalanche current flows, the memory cells deteriorate. Consequently, the rewritable frequency of a flash memory decreases or memory cells are destroyed.
The foregoing problems relate to the principle of erasing. The circuitry in a flash memory for performing the aforesaid erasing has several problems; such as, how to downsize the circuitry, reduce power consumption, or speed up processing.
As mentioned above, the resistivity of a junction in a source region can be improved by applying negative voltage to a control gate during erasing. This has the advantage of enabling reduction of a cell area. It is, however, a big problem how to realize application of negative voltage to the control gate.
It is, for example, conceivable to apply negative voltage from a row decoder to word lines. The voltage to be applied to a word line is changed depending on whether the word line is selected or not. In a flash memory, the voltage to be applied to a word line must be varied depending on whether the read mode or write mode is selected. When the row decoder is used to apply a negative voltage, the voltage to be applied to a word line must be changed to a negative voltage. A word line selected in the read or write mode has a higher voltage than other unselected word lines. For erasing, however, the selected word line must have a lower voltage than the unselected word lines. The level of applied voltage must therefore be reversed depending on the logic of selected or unselected word lines. This results in complex circuitry, making downsizing in possible.
A flash memory includes an internal power switching circuit for switching supply voltages depending on a mode. A conventional internal power switching circuit has a simple circuitry but is likely to cause a latch-up phenomenon. The switching speed is decreased in order to avoid the latch-up phenomenon. This contradicts efforts to speeding up processing.
Furthermore, for negative voltage erasing, bias voltage must be applied to a substrate or part of a well. A conventional substrate bias circuit is realized with a p-channel depletion-type transistor. The manufacturing process is complex and downsizing is hard to do.
Moreover, in a flash memory, the logic of a word line, selected or unselected, must be reversed depending on whether the erase mode or any other mode is specified. An exclusive-OR circuit is employed for the logical reversal. This circuit is also complex, posing an obstacle to downsizing.
DISCLOSURE OF THE INVENTION
The present invention attempts to solve the aforesaid problems, and has the following objects:
(1) To speed up an erasing operation including a pre-erase writing operation;
(2) To enable stable erasing for a specified period of time;
(3) To prevent deterioration of memory cells and increase rewritable frequency;
(4) To minimize the negative effect of excessive erasing by suppressing the influence of excessive erasing of a certain memory cell on other memory cells;
(5) To realize a simple structure that enables selective application of negative voltage to word lines;
(6) To realize an internal power switching circuit that can operate at a high speed with simple circuitry;
(7) To realize a substrate (well) voltage control circuit that consumes limited power and can be downsized; and
(8) To realize exclusive-OR and exclusive-NOR circuits that can be downsized.
For attaining the object (1), in a flash memory based on the first mode of the present invention, each of multiple word lines is connected to the gates of multiple transistor cells arranged in a row, each of multiple bit lines is connected to the drains of multiple transistor cells arranged in tandem, and data can be written electrically in any transistor cell or data can be erased electrically from all transistor cells concurrently. When data of specified values are written in all transistor cells before data erasing, at least either all the bit lines or all the word lines are selected in units of multiple lines. The data of specified values are then written in multiple transistor cells connected to the selected multiple bit lines or word lines.
In a conventional flash memory, pre-erase writing as well as writing is performed for each memory cell. Therefore, too much time is taken up by this for pre-erase writing. In the flash memory based on the first mode of the present invention, pre-erase writing is performed in units of multiple memory cells. The time required for pre-erase writing can therefore be reduced.
For attaining the object (2), a flash memory based on the second mode of the present invention, which performs channel erasing or source erasing by applying a negative voltage to a control gate, includes a voltage restriction means for restricting the negative voltage to be applied to the control gate so that the negative voltage will be a constant value relative to the voltage of a channel or source, or two voltage restriction means for restricting the negative voltage to be applied to the control gate and the voltage to be applied to the source so that the voltages will be a constant value relative to a common reference voltage.
In the flash memory based on the second mode of the present invention, the voltage between a control gate and a channel or source is held constant all the time, so errors in erasing time will be diminished.
For attaining the object (3), a flash memory based on the third mode of the present invention includes a cell matrix in which rewritable nonvolatile memory cells are arranged at intersections between multiple word lines and multiple bit lines, and a power circuit for feeding a supply voltage to each of the sources of transistors forming the nonvolatile memory cells, and performs source erasing by applying a high voltage to the sources. The power circuit includes a current restriction element that has a specified load characteristic.
In the flash memory based on the third mode of the present invention, the power supply for applying high voltage to the sources of memory cells has a current restriction element. Despite the fluctuation in source voltage, as long as the load characteristics of the current restriction element are defined so that a specified voltage, which is equal to or lower than an avalanche voltage, will be applied, injection of holes during erasing can be suppressed. Deterioration of memory cells is therefore minimized.
For attaining the object (4), in a flash memory based on the fourth mode of the present invention, memory cells are grouped in units of a specified number of memory cells on the same word line, select lines are provided to select a specified memory cell group among the memory cell groups, the gates of MOS transistors are connected to the word lines of the memory cell groups and the sources thereof are connected to the sources of the memory cells in each memory cell group, and the memory cell groups including the MOS transistors are formed in a well. When specified data previously written in the memory cell groups are to be erased electrically, a negative voltage is applied to the word lines.
In the flash memory based on the fourth mode of the present invention, MOS transistors are employed and the gates of the MOS transistors are connected to the word lines of memory cell groups. The sources of the MOS transistors are connected to those of the memory cells of each memory cell group. When data is to be read, since only a selected memory cell group is connected to the sources of the MOS transistors, even if excessive erasing occurs in one cell of unselected memory cell groups, since the sources of the unselected memory cell groups are disconnected, the influence of the excessive erasing can be suppressed.
Complex control is unnecessary for erasing. Moreover, since one MOS transistor is added to each memory cell group, the cell area hardly deviates from that in a conventional memory. Eventually, the negative effect of excessive erasing can be prevented, and an increase in cell size can be minimized.
For attaining the object (5), in a flash memory based on the fifth mode of the present invention, a row decoder outputs the negative voltage to be applied to word lines for erasing. Herein, the row decoder includes drive units for supplying decoded signals to word lines. The drive unit selectively outputs a voltage to be applied to a first power terminal and a voltage to be applied to a second power terminal. The drive unit can enter either a first operation mode in which a first voltage is applied to the first power terminal and a second voltage that is lower than the first voltage is applied to the second power terminal or a second operation mode in which a third voltage is applied to the first power terminal and a fourth voltage that is higher than the third voltage is applied to the second power terminal. Output voltages are thus changed depending on whether the first or second operation mode is selected.
In the flash memory based on the fifth mode of the present invention, the levels of voltages to be applied to the power terminals of a drive unit in a row decoder are varied between two modes; that is, the levels of voltages to be applied to the power terminals of a drive unit in a row decoder are varied depending on which of the modes is specified. This obviates the need of changing the logic of each word line between selected and unselected. Simple circuitry ensues.
In a flash memory based on the sixth mode of the present invention or another mode for attaining the object (5), a row decoder includes a level change circuit comprising a first connection switch element whose first terminal is connected to an input terminal for inputting an input signal and whose second terminal is connected to a first output terminal for outputting a first output signal, a second connection switch element whose first terminal is connected to the input terminal and whose second terminal is connected to a second output terminal for outputting a second output signal, a first inverter whose input terminal is connected to the second terminal of the first connection switch element, whose output terminal is connected to the second output terminal, and whose power terminals are connected respectively to a first voltage line for feeding a desired voltage that is higher than a supply voltage and a second voltage line for feeding a desired voltage that is lower than a ground voltage, and a second inverter whose input terminal is connected to the second terminal of the second connection switch element, whose output terminal is connected to the first output terminal, and whose power terminals are connected respectively to the first voltage line and second voltage line.
In the flash memory based on the sixth mode of the present invention, the level change circuit has the capacity for level change and logic change. A row decoder capable of applying negative voltage selectively to word lines can thus be realized with a small-scale circuitry.
For attaining the object (5), a flash memory based on the seventh mode of the present invention is provided with a negative voltage source independently of a row decoder. The negative voltage source is connected to word lines via a negative voltage bias circuit comprising a capacitor to one end of which a clock pulse is supplied, a first p-channel MIS field-effect transistor whose drain is connected to a negative voltage output terminal and whose gate and source are connected to the other end of the capacitor, and a second p-channel MIS field-effect transistor whose drain is connected to the source of the first p-channel MIS field-effect transistor, whose gate is connected to the negative voltage output terminal, and whose source is provided with negative voltage. When negative voltage is applied, the row decoder outputs a word line application signal whose logic is reversed. A logic circuit extends control so that when a word line application signal whose logical value is low is output, a clock pulse will be fed to the negative voltage bias circuit.
In a flash memory based on the seventh mode of the present invention, the foregoing negative voltage bias circuit is used to control whether or not to apply negative voltage depending on whether or not a clock signal is to be input. The input of a clock signal is controlled by a decoded signal sent from the row decoder, which enables selective application of negative voltage. Although another system independent of the row decoder is employed for negative voltage application, since an existing row decoder is used to select word lines, a simple circuitry ensues. Moreover, downsizing is possible.
The eight mode of the present invention is an internal power switching circuit for use in a flash memory or the like, comprising a first MOS transistor of a first polarity one of whose drain and source electrodes is connected to a first power line and the other of whose drain and source electrodes is connected to a second power line;
a second MOS transistor of a second polarity one of whose drain and source electrodes and whose well are connected to a third power line having a higher voltage than the first power line, and the other one of whose drain and source electrodes is connected to a node; and
a third MOS transistor of the second polarity one of whose drain and source electrodes is connected to the node and the other of whose drain and source electrodes is connected to the second power line. The internal power switching circuit further includes a fourth MOS transistor of the first polarity one of whose drain and source electrodes is connected to the third power line and the other of whose drain and source electrodes is connected to the second power line.
In the internal power switching circuit based on the eighth mode of the present invention, when a low voltage is switched to a high voltage, the fourth MOS transistor assists in boosting the voltage of the second power line. This helps minimize the channel current in the second MOS transistor. A latch-up phenomenon can therefore be avoided.
The ninth mode of the present invention is a substrate (well) voltage control circuit for use in a flash memory or the like. For attaining the object (7), the substrate voltage control circuit comprises a negative voltage source for outputting a negative voltage to a power line connected to a component whose voltage is to be controlled, a first n-channel transistor whose substrate (well) and source are connected to the power line and whose drain is connected to a ground power supply, a second n-channel transistor whose substrate (well) and source are connected to the power line and whose drain is connected to the gate of the first n-channel transistor, a first switch installed between the gate of the first n-channel transistor and a positive power supply, a second switch for use in selecting whether the gate of the second n-channel transistor is to be connected to the positive power supply or ground power supply, or opened, and a capacitative element connected between the gate and source of the second n-channel transistor. When negative voltage is not applied, the negative voltage source is put into a non-output state, the first switch is made, and the second switch is connected to the ground power supply. When negative voltage is to be applied, the first switch is opened and the second switch is connected to the positive power supply at the same time. Thereafter, the second switch is opened and the negative voltage source is put into an output state.
In the substrate (well) voltage control circuit based on the ninth mode of the present invention, when negative voltage is applied, the gate-source voltage of the second n-channel transistor is held at a specified value owing to the charges retained in the capacitative element before switching is done. The second n-channel transistor therefore remains in the on state. The gate of the first n-channel transistor therefore assumes a negative voltage. The first n-channel transistor is then turned off. The power line is then disconnected from the ground power supply. A large voltage will not be applied between the gate and source of the second n-channel transistor, which obviates the need of improving resistivity, and downsizing becomes possible.
The tenth mode of the present invention is an exclusive-OR circuit for use in a flash memory or the like. For attaining the object (8), the exclusive-OR circuit includes a first CMIS inverter in which the source of a first pMIS transistor is connected to a high-voltage power supply line, the source of a first nMIS transistor is connected to a low-voltage power supply line, the gates of the first pMIS transistor and first nMIS transistor are connected to each other to serve as an input terminal, the drains of the first pMIS transistor and first nMIS transistor are connected to each other to serve as an output terminal, a second pMIS transistor whose source is connected to the input terminal of the first CMIS inverter and provided with a first input, and a second nMIS transistor whose drain is connected to the output terminal of the first CMIS inverter, whose source is connected to the drain of the second pMIS transistor, and whose gate is connected to the date of second pMIS transistor and provided with a second input. The exclusive OR of the first and second inputs is output from a contact point between the drain of the second pMIS transistor and the source of the second nMIS transistor.

Drive circuit for flash memory with improved erasability