A calender includes at least two roll stacks which each have at least three rolls, and in each of which the web path of a fibrous web meanders between each roll pair of the stack. In order to produce a selectable fibrous web grade, the web is passed between each roll pair of each stack, so that at least one roll pair in at least one stack is in nip contact to form a nip that calenders the web. The web runs between each roll pair of each roll stack and, in order to produce a selectable fibrous web grade, a selectable number of rolls is in nip contact with each other in each stack to form at least one nip that calenders the fibrous web.

The present invention relates to paper, pulp, board or other similar fibrous web machines. More specifically, the present invention relates to calenders of fibrous web machines and, in particular, the present invention relates to a method for calendering a fibrous web in a calender which includes at least two roll stacks which each have at least three rolls, and in which calender the fibrous web is passed to run between each roll pair of each roll stack. The invention also relates to a calender which includes at least two roll stacks which each have at least three rolls, and in which calender a fibrous web has been passed to run between each roll pair of each roll stack.
Calendering is a method by means of which attempts are generally made to improve the properties of a web-like material, such as a paper web, in particular, its thickness profile, smoothness, gloss, surface porosity and transparence. In the calendering process, a paper web is passed into a nip formed between rolls pressed against each other, in which nip the paper web is deformed due to the effect of temperature, moisture and nip pressure, whereby the physical properties of the paper web can be affected by regulating the above-mentioned parameters and the time of action. The good physical properties achieved by calendering result in improved print quality, thus giving a competitive advantage to the paper manufacturer.
Up to the mid 1990s, calenders comprised three main categories, which are typically single- or double-nip hard-nip calenders and soft calenders as well as multi-nip supercalenders. All these calender types have their advantages and disadvantages.
Shoe or so-called long-nip calendering has been found to be generally good for producing low-gloss paper grades, i.e. grades having a Hunter gloss % below 40. When a higher gloss is required, the nip pressure is, however, not sufficient to produce gloss. With continuously increasing running speeds, calendering is becoming a bottleneck in the papermaking process and adequate quality is not achieved by means of today's hard-nip calenders. The drawbacks of today's papermaking process also include the fact that the loss of bulk increases when gloss is improved and that to achieve adequate quality it is necessary to employ abundantly coated webs and/or use off-line calendering, in particular soft calendering and/or multi-nip calendering, whose known application is supercalendering. The direction in the processing of the fibrous web and thus also in calendering is, however, towards on-line arrangements to an ever-increasing degree, also when the intention is to produce higher-quality printing paper grades, such as SC and glossy coated papers. FIG. 2 illustrates with a broken line currently available different paper grades, which include, among other things,                NP (NewsPrint) newsprint paper grades,        SC (SuperCalendered) paper grades,        MFC (Machine Finished Coated) fine paper grades,        LWC (Light Weight Coated) paper grades, and        WFC (WoodFree Coated) fine paper grades,and today's calenders, which include        a hard-nip i.e. machine calender,        a soft calender, and        a supercalenderfor producing different paper grades. It can also be seen from FIG. 2 that a multi-nip supercalender is remaining as the only alternative when the aim is to manufacture high-quality, i.e. high-gloss and smooth, WFC, LWC and SC paper grades.
The good characteristics of the calendering technique common today are beginning to reach their physical limits and the surface properties of the fibrous web cannot be much improved any more without a risk of the surface being scratched. When running speeds simultaneously increase to be as high as 1600 m/min or more, a drawback is the shortening time of action of calendering, which leads to considerable capacity problems when producing high-quality paper grades, so that even three supercalenders are not necessarily sufficient to produce high quality at high speeds, but even a fourth supercalender is needed, which is expensive both as an investment and in respect of operation.
Because of the development of the soft calender technology, polymer-coated rolls can be used in the calender today. A problem associated with this is, however, that if more than three rolls in the supercalender are provided with an elastic polymer coating, the quality of the fibrous web begins to deteriorate. To meet increasing quality requirements, three new calender types have been developed, which are the OptiLoad® calender developed by Metso Paper, Inc., provided with a single roll stack and typically including 6-12 rolls and having as a special feature the possibility of affecting the linear loads of individual nips and providing the roll stack with a nip load even inversely increasing with respect to the force of gravity; the Janus® calender developed by Voith-Sulzer, provided with two roll stacks and typically including 6-10 rolls; and the Prosoft® calender developed by Küsters-Beloit, provided two roll stacks and typically including 6-14 rolls.
These new type of multi-nip calenders, which can be used both as on-line and off-line calenders, are standard types in today's calendering technique and they are based on enhanced utilization of an elastic roll coating, but they differ substantially from one another in respect of attainable calendering results.

Method for calendering a fibrous web and a calender


A method for measuring a price level of an option contract or a series of options contracts based upon a volatility of an underlying security. The method includes the process of calculating a rate of return index for an option series. The rate of return index includes factors such as the implied rate of return, the price of the underlying security, and a weighting factor. The rate of return index may be used for a series of call option contracts and a series of put option contracts. Both the series of call option contracts and series of put option contracts may be numerically set to provide an implied interest rate at a specific volatility.

1. Technical Field
This invention relates to business models for determining returns attainable on a set of options traded on options markets based upon a volatility factor.
2. Description of the Prior Art
An option is a right to buy or sell a specific amount or value of a particular underlying interest at a fixed price through exercising the option before its stated expiration date. In actuality, an option is a contract between two parties, the buyer of the option and the seller of the option. The buyer of an option is also known as its owner or holder, and the seller of an option is also known as its writer or assigned writer if the seller has been assigned an exercise right or obligation. An option which provides the right to buy the underlying interest is called a "call" option, and an option which provides the right to sell the underlying interest is called a "put" option. The buying and selling of call and put options are independent of one another and, irrespective of the type and classification of the option, options contracts give the buyer/owner the right, but not the obligation, to buy or sell an underlying interest.
There are two kinds of options. Physical delivery options and cash-settled options. Physical delivery options provide the option owner with the right to physical delivery of the underlying interest if the option is a call option or the right to make physical delivery of the underlying interest if the option is a put option. Cash-settled options provide the option owner with the right to receive a cash payment based on the difference between the underlying value of the underlying interest at the time of option exercise and the fixed exercise price of the option. A cash-settled call option allows the option owner to receive a payment if the value of the underlying interest at exercise exceeds the fixed exercise price, and a cash-settled put option allows the option owner to receive a payment if the exercise price exceeds the value of the underlying interest. Irrespective of the type and classification of the option, options contracts give the buyer/owner the right, but not the obligation, to buy or sell an underlying security at a fixed price for a specific period of time.
The most commonly known and traded options are options traded on various options exchanges in the United States and throughout the world. Examples of such exchanges are the New York Stock Exchange, American Stock Exchange, Chicago Board Options Exchange, Pacific Stock Exchange, Philadelphia Stock Exchange, and the European Options Exchange in Amsterdam. However, many additional options markets may exist. As a result of the existence of options markets, options contracts have become relatively uniform in standardized terms which allows for easy trading of options on the options markets. However, each U.S. options market publishes its own specifications for options traded on that market which sets out the standardized terms of the options traded on that options market. Options with the same standardized terms are identical and comprise an options "series." Examples of the standardized terms are such terms as the form and amount of the underlying interest, the expiration date, the exercise price, classification of the option as a call or put and as a physical delivery option or a cash-settled option, the specific terms of any cash-settled option, the style of option, and if there is an automatic exercise provision or adjustment provision to the option. The use of standardized terms increase the likelihood that the options markets will function as a secondary market for the purchase and sale of options contracts. This provides holders and writers of options with a means to close out their option positions by offsetting sales and purchases. By selling an option of the same series as the one bought, an options holder may closeout his position in that option. By buying an option of the same series as the one sold, an option writer may closeout his position in that option as well. Accordingly, standardized terms and the existence of options series increases the ability of investors to trade options and create a market for the buying and selling of options at prices determined by market factors.
Individual options markets determine the availability of options for selected underlying interests. There are four common types of underlying interest for which options are available: equity securities, futures and stock indexes, government debt securities, and foreign currencies. However, one should keep in mind that these are not the only types of underlying interests which may exist.
The writer, or assigned writer, of an option is obligated to perform according to the terms of the options contract. The contract may have terms for selling the underlying interest at the contracted price for a writer of a call option, or purchasing the underlying interest for a writer of a put option. However, these terms will only impact the writer if the options contract is exercised by the holder. The price that a holder of an option pays is called its premium. The premium is a non-refundable payment for the rights contained in the option. The potential loss to the holder of an option can be no greater than the initial premium paid for the option. As such, a holder controls the amount of the assumed risk. Conversely, the seller of an option assumes the risk of being assigned if the contract is exercised. In such a case, depending upon whether or not the option was "covered" (i.e. the writer owned the underlying interest or is short the underlying interest) or uncovered or naked (i.e. the writer does not have a position in the underlying interest), the writer's risk may be substantial. All options of a series expire on a certain date, known as the expiration date. The option contract may be exercised at any time between the date of purchase of the contract and the expiration date of the contract. Accordingly, an option is a contract providing a holder with the right to purchase or sell an underlying interest without an obligation to actually purchase or sell the underlying interest.
Both call options and put options are known as derivative securities. Their value is derived from the value of an underlying interest. The most common type of underlying interest is the equity security. Equity securities include common stock as well as many other forms of equity such as limited partnership interests. Options on equity securities are commonly known as "stock options" since the majority of such options are on an underlying interest of stock in a corporation. Each physical delivery option contract will have a "unit of trading" or "contract size" which will fix the amount of the underlying interest to be delivered upon exercise. Cash-settled options have a contract size determined by a multilayer which determines the aggregate value of each point of the difference between the exercise price of the option and the settlement value of the underlying interest. Options will have a fixed exercise price, also known as the "strike price," at which price the holder has the right to either buy or sell the underlying stock if the option is a physical delivery option or at which price the holder had the right to receive a cash settlement amount if the option is a cash-settlement option.
Writers and holders of options contracts take positions in the options. When a writer sells an option or a holder purchases an option they are said to have taken an "open" position in the option. A writer or holder is said to have "closed" their position when, prior to expiration, the holder has made an offsetting sale of an identical option (i.e. the same series) or a writer has made an offsetting purchase of an identical option. Two other common positions in options trading are spreads and straddles which are two types of combination positions. Combination positions are positions in more than one option at the same time which are not the same series and may be also used as a "hedge" or "spread" or "straddle". A hedge position is when the investor owns or is short the underlying interest and has an opposing position in options on that underlying interest; that is, long the underlying interest and short call options or long put options on that interest, or short the underlying interest and long calls or short puts on that interest. A spread position is when the investor is both the holder and writer of the same type of option in the same underlying interest with the options having different exercise prices and/or expiration dates. A straddle position is when the investor either holds or writes both a put and call option on the same underlying interest, with the same exercise price and expiration date.
Various methods are known for calculating a fair price for options. One common method for calculating a fair price for options is known as the "Black Scholes" model. A common saying in the investment community is "Buy low and sell high". This logic is applied equally to the options trading markets, as options traders commonly attempt to purchase options for less than the fair value calculated by the investor's Black Scholes model and to sell options for more than the fair value calculated by their Black Scholes model.
One factor in determining a fair price for an option is volatility of the underlying interest, which is usually computed as a measure of changes in price expressed in percentage terms. The volatility that affects the value of the option and that is used in options models like the Black Scholes model is the volatility of the underlying between the time of the valuation and the expiration of the option. Mathematically, the volatility of the underlying interest over a specific period is usually measured as the annualized standard deviation of daily returns during that specific period. Accordingly, the future volatility is an annualized standard deviation of daily returns during some future period. However, future volatility by its nature cannot be known but only estimated. Various methods of estimating the future volatility are used. The most common is to use the volatility of the underlying interest over a recent time period, and perhaps extrapolating it using a trend analysis. Options prices are themselves used to estimate volatility, by using the "implied volatility", which is that volatility value that "explains" the current market price of an option, meaning that volatility value which, if used in the option model such as Black Scholes, makes the theoretical fair value equal to the market price of the option. Different options series on the same underlying may, and usually do, yield different implied volatilities, so that difference options express different, and therefore inconsistent, market "opinions" about the future volatility of the underlying. Implied volatility of an options series is often used as a measure of the degree of pricing extremity of the options series, and the implied volatilities of different options are compared by investors and traders to determine which series on an underlying are the best "buys" or "writes". Further, the implied volatilities of options on different underlyings are often compared with one another and with the estimates of future volatilities of the underlyings, in order to determine which of the underlyings offer the best opportunities for hedging or spreading. In determining a fair price for an option, it is common to evaluate the relationship between implied volatility and estimated future volatility. Volatility calculations used in options pricing formulas are only estimates of future volatility, but they are critical in determining the value of an option.
The Black Scholes model also provides a conventional method of calculating an implied interest rate. The Black Scholes method of options valuation has two significant suppositions: 1) a riskless hedge could be constructed between an underlying interest and a variable quantity of call options on the underlying interest, with the variable quantity selected continuously so that the behavior of the call option positions imitate the reverse underlying interest position and produce a riskless return, and 2) the rate of return on money invested in the riskless hedge should be equal to the rate of return on any other riskless investment. The Black Scholes equation is DNRR r, where DNRR is the "delta neutral rate of return" on a continuously adjusted hedge and r is the riskless rate of return, often taken to be the T-bill rate for the period of time until expiration of the option. In the case of a call option on a stock that pays no dividends, this equation leads to a formula that allows traders to derive the value of the call option given its strike price and expiration date and the volatility of the underlying between the time of the valuation and the expiration of the call. However, this mathematical formula has two uncertain factors, the future volatility of the underlying interest's price until expiration and the riskless interest rate. The volatility of the underlying interest's price was assumed by Black and Scholes to be known and constant. However, in actuality the future volatility of the underlying interest's price is unknown and difficult to ascertain with precision. In practice, most traders estimate the future volatility by looking at the recent past. If this practice is followed, often options are not priced by the market according to the Black Scholes model.
The only prior art calculation that attempts to measure the general implied volatility level of a collection of calls and puts on a given underlying is the Volatility Index (VIX) which was proposed by Robert Whaley of Duke University in a paper entitled "Derivative on Market Volatility: Hedging Tools Long Overdue" published in the Journal of Derivatives 1 (Fall 1993), 71-84. The broadcasting of VIX was introduced by the Chicago Board of Options Exchange in 1993 on a real time basis. VIX provides a simple measure of the general implied volatility level for the general class of options, both puts and calls, on the OEX index. VIX is created from eight options that are near-the-money and within thirty days of expiration. However, VIX has the following limitations: (1) VIX applies only to options on the OEX index, (2) it considers both calls and puts together and does not distinguish call levels from put levels, (3) it is not a uniquely defined number but is rather a function of the riskless interest rate assumed, (4) it uses a fixed interest rate and does not consider the interest rate to be a measure of return on delta neutral hedging, (5) it cannot be used to derive a unique and unequivocal estimate of future volatility for an arbitrary given time period, and (6) it cannot be used to derive a unique and unequivocal estimate of future volatility for an arbitrary expiration of the options on the underlying. Accordingly, there is a need to have a good estimate of future volatility of the underlying based upon the market prices of the options on the underlying, and the usual inconsistency of implied volatility estimates provided by the different options series on an underlying makes it highly desirable to have a method of estimating volatility from market prices that is consistent with all market prices of options on an underlying interest.


A bottle cap is disclosed, which displays an opened state and cannot contain contents again once it is opened. The bottle cap includes a cap having a screw formed on its inner surface to be engaged with a screw formed on an outer surface of a nozzle of a bottle, a reverse moving means connected to the cap and ascending in a direction opposite to a descending direction of the cap as the cap is rotated downwardly, a rod shaped nut having a screw engaged with the reverse moving means and moving up and down in a screw direction without rotation, and a display installed in the lower portion of the nut, displaying an opened state of the cap by hanging a part of the cap in the nozzle as the cap is moved downwardly by being pushed by the nut if the cap is opened.

Generally, there are different kinds of products that contain contents such as liquid. The most general product is completed by sealing a bottle with a bottle cap after containing contents in the bottle. The bottle is of glass, plastic and metal.
Such a bottle product includes a bottle and a bottle cap. There are different kinds of bottle caps. That is, there is a simple bottle cap that can be opened using an opener. There is another bottle cap that can be opened by turning the cap through a screw. In this case, the screw is formed on an outer surface of a bottle nozzle and is engaged with a screw formed in the bottle.
The products based on the above bottle caps do not have any special problems in case that they contain cheap contents. However, in case that they contain expensive contents, problems are likely to occur. That is, the expensive contents may be exchanged with the cheap contents.
To prevent such a problem, various methods for sealing a bottle cap are being contrived but there is no method for solving the problem at present.


A method controls a continuously variable transmission including: an oil pump disposed in an oil passage between a primary oil chamber and a secondary oil chamber to control a flow of oil from the secondary oil chamber to the primary oil chamber; and an oil supply source to supply oil to the secondary oil chamber, and the method includes: calculating a secondary hydraulic-pressure command value based on a required primary hydraulic pressure that is a pressure in the primary oil chamber required to transmit an input torque to an output side; and controlling the oil supply source in accordance with the secondary hydraulic-pressure command value.

JP 4248147 discloses a control method of a continuously variable transmission having such a configuration. The method controls the pressure of the secondary oil chamber to adjust the clamping force to clamp the belt and accordingly controls the amount of oil supplied to and discharged from the primary oil chamber, and control the speed ratio. That is, this control method controls the speed ratio based on the piston position of the primary pulley that is determined based on the known volume of the primary oil chamber and the amount of oil supplied to and discharged from the primary oil chamber.

Control method and control device for continuously variable transmission


An ophthalmological measuring apparatus has a display that displays a digital image of an imaged ocular fundus of a subject eye. A specifying device specifies an arbitrary point on the displayed digital image. An extracting device extracts from the displayed digital image an image region whose brightness value is higher than a brightness value of the specified arbitrary point.

1. Field of the Invention
The present invention relates to an ophthalmological measuring apparatus, and more particularly relates to an ophthalmological measuring apparatus that derives an actual distance on an ocular fundus based on a fundus image on a screen.
2. Description of the Prior Art
With fundus cameras, there is a demand to be able to view a photograph taken of a fundus and derive the size of a lesion part, the distance on the retina from the lesion part to the macula lutea, and the like. This is because Japanese Patent Publication No. 2000-60893, for example, discloses a photodynamic therapy (PDT) that treats age-related macular degeneration by irradiating a spot of the lesion part with a laser beam, and the actual distance on the retina is needed in this therapy in order to form an appropriate laser spot. When providing treatment by irradiating a lesion part with a laser spot in this manner, it is a problem if the spot size of the beam to be shone is either too large or too small, and there is consequently a demand to form a laser spot of a prescribed size with high precision. Generally, it is said that the optimal spot size is the lesion maximum diameter plus 1 mm. Consequently, the maximum diameter of the lesion part must be accurately measured beforehand, and the beam spot size must be set to a size of the lesion part maximum diameter plus 1 mm.
The distance between prescribed points on a retina has conventionally been derived by assuming that the diopter of the affected eye is 0 diopters, setting a conversion magnification for determining the actual length from the taken image based on the specifications of the optical system of the fundus camera, applying that magnification to a taken image, and then deriving the length on the retina. Actually, there are individual differences that naturally arise in optical systems of fundus cameras, so that such differences must be eliminated. For this purpose, a model eyeball whose eye diopter is 0 diopters is used, and the conversion magnification is determined by using a simulation to derive a length at which the retina can be fully imaged in the mask when imaging the model eyeball with the fundus camera.
Nevertheless, the diopters of actual subject eyes vary, and the eye axial lengths, the corneal curvatures, and the like, also vary. In addition, there is a problem in that the operation of focusing the fundus camera varies the focal length (magnification) of the fundus camera, as is noted by Japanese Patent Publication No. 2003-225208. Accordingly, it is conventionally problematic to accurately derive the actual distance on an ocular fundus because there is considerable error in the distance calculation, which is based on the assumption that the affected eye diopter is 0 diopters.
On the other hand, it is necessary to recognize the position of the lesion part on the retina and to accurately derive the distance of that portion in order to form a laser spot having the appropriate size as mentioned above. To detect the position of the lesion part, a technology as disclosed in Japanese Patent Publication No. 1980-49778 is used that extracts the contour of an image based on, for example, brightness because the brightness at the lesion part varies.
In addition, Japanese Patent Publication No. 1994-125876 discloses a method wherein the papilla part and a pale part are also extracted from the fundus image based on the brightness, and Japanese Patent Publication No. 2003-310555 discloses a method wherein the average brightness of the papilla part is derived and the lesion part is thereby specified from the average brightness thereof.
It is therefore an object of the invention to provide an ophthalmological measuring apparatus capable of accurately deriving the actual distance on an ocular fundus.
It is another object of the invention to provide an ophthalmological measuring apparatus capable of easily specifying a prescribed region within a fundus image and capable of accurately measuring that region.


A method of estimating a change of a variable over a measurement window, including the steps of taking multiple samples of the variable during the measurement window, defining a weight to be associated with each sample, the weight varying as a function of position of the sample within the measurement window, processing the samples taking account of their weight to form an estimate of the change in the variable.

It is often desirable to be able to estimate the parameter, such as a current, by integrating the current over time. The slope of the integral represents an average value of a current. The average value is then digitised, for example by taking a sample at a first instant in time, taking a sample at a second instant in time, and subtracting the difference between the two values to obtain the difference, and hence infer a gradient during the sample period. Relying on one or two samples like this may render the measurements susceptible to noise. Whilst over sampling a signal can provide improvements in measurements of a parameter, the over sampling can give rise to a computational overhead.

Method for determining the change of a signal, and an apparatus including a circuit arranged to implement the method


A porous film which is produced using a resin composition containing an ultra-high-molecular-weight polyolefin and a polyolefin wax having a weight average molecular weight of 3000 or less, in which the number of branches per 1000 carbon atoms that constitute the main chain of the polyolefin wax is 15 or less; a porous film which is produced using a resin composition containing an ultra-high-molecular-weight polyolefin and a polyolefin wax having a weight average molecular weight of 3000 or less, and which does not substantially contain a component that melts at a temperature of 60° C. or lower; a laminated porous film which comprises one of the porous films and a heat-resistance porous layer laminated on at least one surface of the porous film; and a separator for batteries, which comprises the porous film or the laminated porous film.

A porous film is used for various applications, such as hygiene material, medical material and battery separator. In the case of using a porous film as a battery separator of a lithium ion secondary battery or the like, high puncture strength is required.
As a porous film superior in the puncture strength, it is known to use a porous film obtained by kneading a high-molecular-weight polyolefin having a weight average molecular weight of 5×105 or more, a thermoplastic resin having a weight average molecular weight of 2×104 or less, and a fine particle; shape-forming the kneaded product into a sheet; and then stretching the sheet (see, JP2002-69221A (Patent Document 1)). Such a porous film can be easily obtained from the polyolefin having a high molecular weight, without using an organic solvent in the production process, and the obtained porous film is superior in the puncture strength.
Also, it is known to obtain a laminated porous film as a battery separator by laminating a porous heat-resistant layer on a porous film made of a thermoplastic polymer (see, JP2000-30686A (Patent Document 2)). A battery using this laminated porous film as the separator is superior in safety, since even when the porous film melts upon extraordinary heat generation due to overcharge or the like, the heat-resistant layer can prevent contact between the positive electrode and the negative electrode.
Such a laminated porous film can be obtained by a method of applying a solution containing a heat-resistant resin on a porous film and then volatilizing the solvent from the solution to form a heat-resistant layer, or by a method of applying the above-described solution on a porous film and then exposing the resultant to a poor solvent to precipitate the heat-resistant resin. These methods are simple and superior in productivity. However, the laminated porous film obtained by such a method is required to have more improved adhesive strength between the heat-resistant layer and the porous film.

Porous film, battery separator, and battery


An MOS-controlled, lateral SCR device including a semiconductor substrate of a first doping type; a first well region formed in the substrate and being of a second doping type which is different from the first doping type; a second well region formed in the substrate, being of the second doping type, and being spaced apart from the first well region so as to define an intermediate region separating the first and second well regions from each other; a first region formed within the first well region and extending into the intermediate region between the first and second well regions, the first region being of the second doping type; a second region formed within the second well region and extending into the intermediate region between the first and second well regions, the second region being of the second doping type; and a control gate bridging over the intermediate region between the first and second regions.

The invention relates generally to a CMOS output buffer.
In CMOS IC's, an output buffer generally has a pull-up device to pull up the voltage on its output node and a pull-down device to pull down the output voltage on its output node. In digital circuits, the pull-up output voltage is near VDD, and the pull-down output voltage is near VSS. There are several patents relating to output buffer design, including for example: U.S. Pat. No. 5,391,939, entitled "Output Circuit of a Semiconductor Integrated Circuit"; U.S. Pat. No. 4,638,187, entitled "CMOS Output Buffer Providing High Drive Current with Minimum Output Signal Distortion"; U.S. Pat. No. 4,825,101, entitled "Full-Level Fast CMOS Output Buffer"; U.S. Pat. No. 5,189,319, entitled "Power Reducing Buffer/Latch Circuits"; and U.S. Pat. No. 5,367,205, entitled "High Speed Output Buffer with Reduced Voltage Bounce and No Cross Current".
Several conventional CMOS output buffers are shown in FIGS. 1(a-c). In FIG. 1(a), a commonly-used CMOS output buffer configuration includes a PMOS device as a pull-up transistor and an NMOS device as a pull-down transistor. The turn-on and turn-off behavior of output buffer is controlled by a prebuffer (i.e., control circuit). The prebuffer is also used to control the operational characteristics of the output buffer, e.g. producing a high-impedance state, low di/dt current, or some other special functional characteristics.
To handle the high driving or sinking currents, the output PMOS and NMOS transistors must be designed with large device dimensions and this causes the turn-on and the turn-off of the output PMOS or NMOS transistors to become very slow. Referring to FIG. 1(b), to solve this problem transient-handling circuits are added to the output buffer to improve its pull-up and pull-down operating speed. The transient-handling circuits only work within a short time duration when the output level has to be changed rapidly. The transient-handling circuits deliver the required high transient currents from either VDD or from VSS to the output node.
Alternatively, in circuits with particularly large device dimensions, complex prebuffer circuits are utilized to control the output buffer. For example, in high-speed applications, a CMOS tape buffer, such as is shown in FIG. 1(c), has been used so as to quickly drive the output buffer on or off. Even larger device dimensions of the CMOS output buffer results in having to use larger tape buffers, which in turn requires much more circuit layout area to achieve the required output functions.
In these circuits, the drains of the output PMOS and NMOS transistors are directly connected to the output pad, which is bonded to the pin of IC package. If the IC experiences an ESD (Electrostatic Discharge) event, the ESD voltage could easy cause damage to the output buffer. In submicron or deep-submicron CMOS processes, an LDD (lightly-doped drain) structure is used to overcome the hot-carrier phenomenon and a silicided diffusion is used to reduce sheet resistance of the MOS devices. But using these two advanced fabrication process techniques considerably degrades the robustness of the ESD protection of CMOS output buffer. Thus, even if the output buffer has much larger device dimensions, as a result of using these advanced CMOS processes, it is still very vulnerable to ESD stress.
Several papers have been published regarding the degradation on ESD protection reliability of CMOS IC's due to using the advanced fabrication processes. Among these papers are the following:
C. Duvvury and A. Amerasekara, "ESD: A pervasive reliability concern for IC technologies," in Proc. of IEEE, vol. 81, no. 5. pp. 690-702, May 1993. PA1 A. Amerasekara and C. Duvvury, "The impact of technology scaling on ESD robustness and protection circuit design," 1994 EOS/ESD Symp. Proc., EOS-16, pp. 237-245. PA1 C. Duvvury, et al., "ESD protection in 1-um CMOS technologies," Proc. of IRPS, pp. 190-205, 1986. PA1 C. Duvvury, et al., "ESD phenomena and protection issues in CMOS output buffer," Proc. of IRPS, pp. 174-180, 1987. PA1 C. Duvvury and R. N. Rountree, "Output ESD protection techniques for advanced CMOS process," EOS/ESD Symp. Proc., pp. 206-211, 1988. PA1 C. Duvvury and C. Diaz, "Dynamic gate coupling of NMOS for efficient output ESD protection," Proc. of IRPS, pp. 141-150, 1992. PA1 A. Chatterjee and T. Polgreen, "A low-voltage triggering SCR for on-chip ESD protection at output and input pads," IEEE Electron Devices Letters, vol. 12, pp. 21-22, 1991. PA1 M. -D. Ker, et al., "Area-efficient CMOS output buffer with enhanced high ESD reliability for deep submicron CMOS ASIC," Proc.of IEEE International ASIC Conference and Exhibit, pp. 123-126, 1995. PA1 M. -D. Ker, et al., "ESD protection for deep-submicron CMOS technology using gate-couple CMO-Strigger lateral SCR structure," Technical Digest of IEEE International Electron Devices Meeting, pp. 543-546, 1995.
Because it is difficult to uniformly turn on an output transistor having large device dimensions, a gate-coupling technique, which is described in the last cited reference above, has been used to improve uniform turn-on behavior.
To summarize, having to use a CMOS output buffer of large device dimensions has two important disadvantages. One is the requirement of larger layout area, and the other is that the non-uniform turn-on behavior results in weaker ESD reliability. The present invention provides a novel solution which avoids these two disadvantages.
From a study of ESD protection circuits, it is apparent that an SCR device provides the highest ESD protection robustness in the smallest layout area. The SCR device has been successfully implemented as an ESD-protection element in CMOS IC's. Some typical references describing the use of an SCR device as ESD-protection element include the following:
In the first two of these three references, the triggering of lateral SCR device is controlled by the drain breakdown of short-channel PMOS or NMOS devices. For output ESD protection, a typical circuit, which is shown in FIG. 2, uses a PTLSCR (PMOS-Trigger Lateral SCR) device to protect the output PMOS device, and an NTLSCR (NMOS-Trigger Lateral SCR) device to protect the output NMOS device. In the third reference, the device behavior of PTLSCR and NTLSCR is more clearly explained. It also shows that the PTLSCR and NTLSCR devices can be further controlled by applying voltage to the gates of PMOS and NMOS, which are inserted into the PTLSCR and NTLSCR structures.
This invention fully uses the natural advantages of the SCR device to work as both an output device and an ESD-protection device.

CMOS output buffer with CMOS-controlled lateral SCR devices

Industrial Technology Research Institute


Disclosed herein is an apparatus for sterilizing ballast water. Ultraviolet lamps are installed in a body, and a cross-section of the body that is perpendicular to the orientation of the ultraviolet lamps is rectangular. The ultraviolet lamps are arranged at regular intervals in the rectangular cross-section of the body so that the number of ultraviolet lamps arranged per a unit cross-sectional area can be minimized. Thereby, the power consumption of the apparatus and the space required for installation thereof can be reduced. Furthermore, lines, each of which includes ultraviolet lamps arranged in a row perpendicular to the direction of the flow of ballast water, are arranged in the rectangular cross-section of the body. The ultraviolet lamps of each line are disposed between the ultraviolet lamps of the preceding or following line. Thus, ballast water can be prevented from being discharged out of the body without colliding with any ultraviolet lamp.

Ballast water refers to sea water that is charged into a ballast tank of a vessel to maintain balance of the vessel when the vessel sails without cargo.
As marine transportation rates have gradually increased along with an increase in international trade, the number of vessels used has increased, and the vessels used are becoming larger. As a result, the amount of ballast water used in vessels has greatly increased. As the amount of ballast water used in vessels is increased, occurrence of damage to indigenous ocean ecosystems attributable to the introduction of foreign marine creature species is also increased. To solve such international environmental issues, in 2004, the IMO (International Maritime Organization) established 'International Convention for the Control and Management for ships' Ballast Water and Sediments'. Since 2009, ballast water treatment apparatuses have been obligatorily installed in newly constructed vessels.
Of apparatuses for treating ballast water, ultraviolet ballast water treatment apparatuses that sterilize ballast water using ultraviolet rays are widely used. FIG. 1 is an exploded perspective view of a conventional ultraviolet ballast water treatment apparatus. FIG. 2 is a sectional view of the conventional ultraviolet ballast water treatment apparatus.
Referring to FIGS. 1 and 2, the conventional ultraviolet ballast water treatment apparatus includes a cylindrical body 1001. Due to the cylindrical shape of the body 1001, ultraviolet lamps 1002 provided in the body 1001 are also arranged in a circumferential shape corresponding to the cylindrical shape of the body 1001. As shown in FIG. 2, when the number of ultraviolet lamps 1002 is comparatively large, the ultraviolet lamps 1002 are arranged in a plurality of rows having different diameters.
However, in the conventional ultraviolet ballast water treatment apparatus, because the ultraviolet lamps 1002 must be densely arranged at regular intervals in the body 1001 having a circular cross-section, the number of ultraviolet lamps per a unit cross-sectional area is increased, and the power consumption is thus increased. When it is intended to increase the number of ultraviolet lamps and thus increase the ballast water treatment capacity, a circumferential row must be added. Therefore, the cross-sectional area of the body 1001 is greatly increased by the square of an increased radius (the area of a circle=πr2). In addition, the number of ultraviolet lamps of the added circumferential row must be greater than that of the existing outermost row (the circumference of the added circumferential row is larger than that of the existing outermost row). As such, it is impossible to increase the capacity scale of ballast water treatment by a small degree. Thus, it is difficult to increase the treatment capacity by only the required degree.
Moreover, as shown in FIG. 2, when the ultraviolet lamps 1002 are arranged in a circumferential direction, there is the possibility of ballast water linearly passing between the ultraviolet lamps 1002 without making direct contact with the ultraviolet lamps 1002 while passing through the ultraviolet ballast water treatment apparatus (refer to the arrows designated by {circle around (a)}, {circle around (b)}, and {circle around (c)}). Given the fact that the treatment effect using ultraviolet rays is proportional not only to the intensity of ultraviolet rays but also the time for which ultraviolet rays are applied to ballast water, the ballast water treatment effect of the conventional technique is largely reduced because the speed of the flow of ballast water (refer to {circle around (a)}, {circle around (b)}, and {circle around (c)}) that linearly flows without making contact with any ultraviolet lamp 1002 is increased and thus the time for which ultraviolet rays are applied to ballast water is reduced.

Apparatus for treating ballast water with ultraviolet rays, having square cross-section


A heated windshield wiper assembly which employs heated forced air generated by a heater-blower powered by a cigarette lighter accessory that flows therefrom through conduits attached to each wiper arm that, in turn, are attached to inlet ports on the blade housing disposed at the outer end of the wiper arms. Each blade housing has an air chamber, fluidly connected to the inlet port, with a pocket on each side of the wiper blade therein to keep both the blade housing and wiper blade warm and a plurality of outlets on a bottom side of the blade housing through which the heated air flow generated by the heater-blower also exits onto the wiper blade and onto the windshield.

Various types of heated windshield wipers are known in the prior art, which include inductively heated windshield wiper assemblies, but do not employ heated forced air as a source of heat for preventing the accumulation of ice and snow on a blade housing and the windshield wiper blade. The present heated windshield wiper assembly employs heated forced air generated by a heater-blower powered by a cigarette lighter accessory that flows therefrom through conduits attached to each wiper arm that, in turn, are attached to inlet ports on the blade housing disposed at the outer end of the wiper arms. Each blade housing has an air chamber, fluidly connected to the inlet port, having a pocket on each side of the wiper blade therein to keep both the blade housing and wiper blade warm and a plurality of outlets on a bottom side of the blade housing through which the heated air flow generated by the heater-blower also exits onto the wiper blade and onto the windshield.


A support system through which a first extrusion roll is operatively mounted upon a frame. The first extrusion roll has a shaft that has a first operating axis and axially spaced first and second ends. A first support assembly at the first shaft end has a first housing. A second support assembly acting between the frame and the first support assembly and has a second housing. The second housing is movable relative to the frame to selectively change a relationship between the first extrusion roll and a second extrusion roll on the frame that has a second operating axis and cooperates with the first extrusion roll during formation of a product. The first housing is movable guidingly relative to the second housing along a first path to thereby change an angular relationship between the first and second operating axes.

1. Field of the Invention
This invention relates to rolls as used in systems to extrusion form products and, more particularly, to a roll that can be selectively skewed relative to a cooperating roll.
2. Background Art
In conventional extrusion forming systems, moldable material is deposited at a nip location between cooperating rolls that are supported at their axial ends upon a frame. By turning the rolls around parallel axes, material is formed to a thickness determined by the gap between the rolls. A problem that is commonly encountered with these systems is the deformation of typically a smaller diameter roll in a cooperating roll pair caused by the thickness of the extruded material during product formation. The material tends to produce a wedging action that causes the unsupported central region of the smaller diameter roll in the cooperating roll pair to deform to a shallow arch shape. It is difficult to maintain a uniform product thickness when this condition occurs. If no accommodation is made for this roll deformation, the quality of the formed product may be compromised.
Further, the arching of the roll tends to produce significant forces upon the ends of a shaft that support the roll upon the frame. In anticipation of this occurring, the shaft and supporting structure may be made with a more robust, and potentially more expensive, construction.
It is also known to skew the deformed roll to place its axis at a slight angle to the axis of the cooperating roll. This causes the arch shape to more closely conform to the cooperating roll, as a result of which there is a more uniform gap dimension over the full axial extent of the rolls, even with the deformation of the one roll maintained.
Heretofore, skew mechanisms have been designed so that the shaft ends on the skewed roll are offset in a manner whereby the supports for the shaft ends on the frame are subjected to potentially large forces. In essence, the parts become misaligned so that as the system is operated, the interacting parts, such as the shaft ends, bearings, and supports, are prone to becoming worn, and may ultimately be prone to failing.
A failure of a part or parts on cooperating components on an extrusion forming line may necessitate shutting the entire line down. This down time can have significant economic consequences, particularly in operations where profit margins are thin.
This industry continues to develop overall system designs that are economically feasible, yet highly reliable in operation, thereby to avoid, or minimize, system downtime. The same design criteria drive the design of skew mechanisms. In spite of designers' striving to meet the above objectives, existing, commercially available systems that allow roll skewing are deficient in one or more respects. The industry continues to seek out improved designs for skew mechanisms on extrusion forming systems.

Extrusion roll with selectable skew capability

Processing Technologies International, LLC


A liquid phase deposition method involves the use of a supersaturated hydrofluosilicic acid aqueous solution for growing a silicon dioxide film at low temperature (30.degree. C.-50.degree. C.) on a III-V semiconductor, such as a gallium arsenide substrate. The silicon dioxide film may be used in a bipolar transistor or as a field oxide of MOS (metal oxide semiconductor). The III-V semiconductor substrate is chemically treated with an alkaline aqueous solution such as ammonium hydroxide so that the surface of the III-V semiconductor substrate is modified to facilitate the growth of the silicon dioxide film by liquid phase deposition. The growth rate of the silicon dioxide film is as fast as 1265 .ANG./hr. The silicon dioxide film has a refractive index ranging between 1.372 and 1.41.

In the recent years, the application of the III-V semiconductor, such as gallium arsenide, as a high speed device in the ULSI (ultra large scalar integral) technology has received more attention than the similar application of the silicon semiconductor, in view of the fact that the III-V semiconductor has a relatively high saturation speed and a relatively low consumption rate of electricity. In the past, the passivation of gallium arsenide (GaAs) in the multilevel interconnection was attained by the thermal oxidation or the anodica. The protective layer so formed is generally composed of the gallium oxide or the arsenic oxide, which is as nonstoichiometrically unstable as the arsenic ion. As a result, the oxide layer of gallium arsenide was seldom used as an insulator.
The silicon dioxide (SiO.sub.2) is devoid of free electrons capable of taking part in the conduction of electrical current in view of the fact that the valence electrons of the silicon dioxide and the adjoining atom form a strong bond which can not be easily severed. As a result, the silicon dioxide has been widely used as the insulation film (band gap=11 eV).
The growth of a silicon dioxide film on the silicon substrate may be achieved by a liquid phase deposition method, which is known as the LPD method for short. For more information on the LPD method, please refer to the publications, such as VLSI FABRICATION PRINCIPLES by S. K. Ghandhi, Wiley, New York, 1983; THIN SOLID FILMS by U. Mackens and U. Merkt, 97, 53 (1982); and C. Chiang, D. B. Fraser and D. R. Denison, IEEE VLSI MULTILEVEL INTERCONNECTION CONFERENCE, 381 (1990). According to the above publications, the LPD method involves a first step in which the silicon dioxide powder is dissolved in an aqueous solution containing 34% of hydrofluosilicic acid so as to form the saturated hydrofluosilicic acid aqueous solution at room temperature. The undissolved silicon dioxide powder is subsequently removed from the saturated hydrofluosilicic acid aqueous solution by means of a filter paper having the diameter of 0.2 .mu.m. The saturated hydrofluosilicic acid aqueous solution is then transformed into a supersaturated solution by adding water, boric acid aqueous solution, or ammonium hydroxide to the saturated solution. The silicon substrate is first cleaned and then immersed in the supersaturated solution in which a silicon dioxide film is formed on the surface of the silicon substrate by deposition. Such reactions as described above may be expressed in terms of the following chemical equations. EQU .DELTA.H+H.sub.2 SiF.sub.6 +2H.sub.2 O.rarw..fwdarw.6HF+SiO.sub.2 .dwnarw.(1) EQU H.sub.3 BO.sub.3 +4HF.rarw..fwdarw.BF.sub.4 +H.sub.3 O.sup.+ +2H.sub.2 O(2) EQU NH.sub.4 OH+HF.rarw..fwdarw.NH.sub.4.sup.+ +F.sup.- +H.sub.2 O(3)
The LPD method has not been used in gallium arsenide substrate. However, the growth of the silicon dioxide film on the gallium arsenide substrate or the III-V semiconductor substrate by the LPD method has become an important technical subject in view of the promising application potential of the gallium arsenide in the ULSI technology.

Liquid phase deposition method for growing silicon dioxide film on III-V semiconductor substrate treated with ammonium hydroxide


An apparatus for simultaneously treating a plurality of cords for use in power transmission belts. The apparatus has a heating chamber, heated air in the chamber, and a guide system for simultaneously guiding a first cord in a first predetermined path and a second cord in a second predetermined path through the heating chamber. The guide system has at least a first roller with a first axis and first structure for causing the first cord and the second cord to move at least partially around the axis of the first roller progressively axially relative to the first roller as the first cord moves in the first predetermined path and the second cord moves in the second predetermined path through the heating chamber.

1. Field of The Invention
This invention relates to cords of the type used in power transmission belts and, more particularly, to an apparatus for pretreating the cords, as by the steps of applying a liquid substance thereto, and curing the substance. The invention is also directed to the method of treating cords through this type of apparatus.
2. Background Art
It is known to use load carrying cords in all types of power transmission belts, i.e. V-belts, V-ribbed belts, toothed belts, etc., and particularly those used in industrial applications. Typically, the cords are made from fiber material, such as polyester fiber, aramid fiber, glass fiber, and the like. To improve adhesion with the belt rubber, it is known to pretreat the fiber cords. For example, it is known to treat the cords with resorcinol formalin latex (RFL) alone or to use the RFL treatment after pretreating the cords with an epoxy or isocyanate compound. It is also known to adhere rubber gum after the RFL treatment.
It is further known to either individually treat a cord or simultaneously treat a plurality of cords by applying a substance thereto and heating the cords to cure the applied substance. In those portions of a treating apparatus in which multiple passes of the cord are required, such as in the heating chamber, guiding rollers for the cords have been arranged in multiple stages so that the cords follow a circuitous path through the heating chamber. For example, the cords may be wrapped in an "S" shape around the various rollers. The multiple cords travel together in substantially parallel relationship through the paths.
With this multiple stage arrangement, the cords are separately threaded on independent sets of rollers to move through an apparatus in parallel relationship with a fixed spacing and are not required to move back and forth in the same plane. This facilitates cord mounting and rethreading of the cords.
However, because of the above multiple stage arrangement, the overall apparatus may be undesirably large. This may result in an increase in the cost of the apparatus, as well as a need for a large amount of operating space, which is often at a premium. This design also has some safety problems associated with setup, maintenance, and periodic cord inspection.
Apparatus for processing a single cord are shown in Japanese Unexamined Patent Publication No. H4-146232 and Japanese Unexamined Patent Publication No. H4-146230. In these apparatus, a cord is directed in a back and forth pattern around a pair of rollers. The single processed cord is wound between the rollers several times and moves axially thereof as the cord is advanced. While these systems eliminate problems associated with multiple stages, they do not permit the simultaneous processing of multiple cords.
Another problem with prior art apparatus is that the treating substance adhered to the cords may foul certain operating elements of the apparatus. For example, when the cords are dip processed in a liquid, the liquid may harden and accumulate on roller surfaces, particularly those first contacting the cords after dipping. The adhered liquid may accumulate progressively to the point that the diameter of the roller appreciably increases. Without making adjustments elsewhere in the system, the cord tension thus becomes higher than intended. The adhered liquid may also cause a contamination problem.
To eliminate this problem, the heating temperature in prior art systems has been raised. It is also known to reduce the processing speed to increase the heating time and to extend the length of the heating ovens. However, certain temperatures produce optimum cord properties. By altering this temperature, the quality of the cord may be compromised. By reducing the processing speed, the capability of the apparatus is reduced. By extending the oven length, the overall size of the equipment may be increased, increasing costs and necessary operating space. Such modifications may make system inspection more difficult, which could ultimately result in a compromise in system safety.

Apparatus for treating a cord for use in a power transmission belt and method for treating such a cord


A method for developing a tire model for use with an effective road profile in testing an automotive vehicle on a spindle-coupled road simulator defines a flat surface road plane in a three coordinate reference system to represent the effective road profile with the three coordinates comprising a plane vertical deflection, a plane radial contact angle, and a plane lateral contact angle. The tire is then excited over a predetermined range while on a tire test apparatus for developing the tire model. The tire test apparatus includes a flat tire contact plane moveable so as to contact the tire, the flat tire contact plane defining a three coordinate reference system to represent the effective road profile in the three coordinates.

The use of large-deflection tire models to predict vehicle loads for design or simulation testing has become an important application in the automotive vehicle development process. A wide range of tire models have been used to simulate the tire. In general, current tire models can be divided into three categories: simple models, ring elastic foundation (REF) models, and detailed models.
Two simple tire models are shown in FIGS. 1 and 2. These models assume that the tire envelopes an obstacle and that the effect the tire tread has on contact and deformation is negligible. In a radial spring model (FIG. 1), the tire envelopes the terrain with springs that are radially attached to center of the tire. Another simple model, commonly referred to as an ADAMS model (FIG. 3), uses an "equivalent ground plane" to calculate the longitudinal and vertical spindle forces. In both models, the net spindle force is generated by summing the individual spring forces in the vertical and horizontal directions.
In contrast to simple models, a Ring Elastic Foundation (REF) model represents the tire as an elastic foundation supporting a tread. REF models can be represented either with partial differential equations or with finite elements. Detailed tire models are three dimensional finite element representations of the complete tire (FIG. 4). These models are more representative of an actual tire than the previously discussed models, but a major disadvantage of this type of model is the large number of degrees-of-freedom needed and consequently the intensive computing time required.
Many existing tire models use a finite element analysis (FEA) approach to determiine vehicle loads. However, these currently available models have inaccurately estimated tire loads through computer simulation. In addition, all of the tire finiteelement models discussed above are time-intensive to build and run. Vehicle spindle-coupled simulation requires a tire model that is relatively easy to model from readily-measurable parameters, which is not computationally intensive, and which is easy to implement with a spindle-coupled simulation controller utilizing an effective road profile.

Method and apparatus for modelling a tire for use with a vehicle spindle-coupled simulator


A photomask inspection apparatus includes a photoelectric converting portion, a first comparator, buffer memories, a design data converting portion, and second and third comparators. The photoelectric converting portion converts the respective beams of light having separately scanned adjoining identical unit patterns formed on a photomask into electrical signals. The first comparator compares these electrical signals with each other to find whether there is any inconformity between the unit patterns, and when any inconformity is found, the first comparator outputs coordinate information of the inconformity. The buffer memories store the electrical signals respectively when the inconformity is found by the first comparator. The design data converting portion converts only design data of peripheral coordinates of the coordinate information in the design data stored in the external memory into an inspection signal. The second and third comparators compare the electrical signals from the buffer memories with the inspection signal to identify a photomask pattern having a defect.

The present invention relates to a photomask inspection apparatus and, more particularly, to a photomask inspection apparatus to be used upon manufacturing semiconductor integrated circuit.
There are two inspection methods for inspecting a defect on a photomask. A first inspection method is a pattern comparison method in which adjacent unit patterns are compared with each other to inspect the difference therebetween. A second inspection method is a database verifying inspection method in which an actual pattern is compared with a design pattern to make an inspection.
A photomask inspection apparatus capable of simultaneously executing the inspections according to the above-mentioned two methods is disclosed in Japanese Patent Laid-Open Publication No. Hei 2-108947. FIG. 2 is a structural view of the apparatus disclosed by the above reference. As shown in the figure, a central control unit 12 operates so that a flush switch 3 turns on light sources 4R and 4L, and then optical signals D.sub.R1 and D.sub.L1 from right and left unit patterns 2R and 2L on a mask 2, which has been obtained through lenses 5R and 5L, are converted into comparison signals D.sub.R2 and D.sub.L2 by a photoelectric converting portion 6.
The comparison signal D.sub.R2 is subjected to intensity adjustment and division by an amplifier 13 and a division circuit 14 so as to be converted into signals D.sub.R3 and D.sub.R4 which are inputted into two comparators 9a and 9b respectively. The comparator 9a compares the comparison signal D.sub.L2 with the signal D.sub.R3 and stores defect information obtained by the pattern comparison method between the unit patterns 2L and 2R on the photomask 2 into a buffer memory 10a.
On the other hand, the comparator 9b compares the comparison signal D.sub.R4 with a comparison signal D.sub.2 which is generated by a design data converting portion 8 from design data D.sub.1 recorded in an external memory 7, and stores defect information obtained by the database verifying inspection method into a buffer memory 10b. When an output instruction is inputted from a console 1, each defect information stored in the buffer memories 10a and 10b is outputted to an external output unit 11.
However, in the above conventional photomask inspection apparatus, since the defect information shown in the external output unit 11 must be analyzed, there are some cases where it is difficult to determine which of adjoining chips contains defects such as an error in size of a contact hole.
Further, in the conventional photomask inspection apparatus, since the design data converting portion 8 must convert all the design data in the external output unit 11, there is a problem that a long time is required to convert the design data.


Aliphatic tricarboxylic acids, as exemplified by 9-carboxy-1,18-octadecanedioic acid, may be prepared by the biotransformation of an olefinic monocarboxylic acid such as oleic acid to the corresponding olefinic dicarboxylic acid, preferably 1,18-octadec-9-enedioic acid, in the presence of a strain of yeast, such as a strain of Candida tropicalis, followed by the carboxylation of the olefinic dicarboxylic acid by reaction with carbon monoxide and water in the presence of a catalyst. The product tricarboxylic acids are useful as branching agents for polycarbonates.

This invention relates to the preparation of branched polycarbonates. More particularly, it relates to new tricarboxylic acid branching agents and the polycarbonates derived therefrom.
Polycarbonate resins are a well known class of synthetic polymeric resins which may be prepared by various methods including the reaction of a dihydroxy compound, preferably a dihydroxyaromatic compound, with a carbonate precursor; see for example U.S. Pat. No. 3,028,365. For certain purposes such as blow molding, branched polycarbonates are superior to the linear polymers by reason of their melt rheology behavior. In particular, they exhibit high melt elasticity and high melt strength. Melt elasticity is the recovery of the elastic energy stored within the melt from distortion or orientation of the molecules by shearing stresses. Melt strength may be simply described as the tenacity of a molten strand and indicates the ability of the melt to support a stress. These advantageous properties of the branched resins are in large part a result of their non-Newtonian flow characteristics.
In the typical preparation of branched polycarbonates, a linear polycarbonate or its precursor undergoes reaction with a branching agent. Commonly employed branching agents include 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) and trimellityl trichloride (TMTC). However, THPE is very expensive, partly by reason of its method of preparation in which an essential reactant is the expensive 4-hydroxyacetophenone. Branched polycarbonates prepared with TMTC are photochemically unstable.
It is of interest, therefore, to provide new branching agents which are relatively inexpensive. In one embodiment of the present invention, aliphatic branching agents are produced by a series of reactions which can include a biosynthesis step. This series of reactions has potential for being very inexpensive to conduct. The product is an aliphatic tricarboxylic acid which is capable of being used to produce branched polycarbonates having excellent properties.
One aspect of the invention is aliphatic tricarboxylic acids having the formula
wherein each of R1 and R2 is independently a divalent aliphatic hydrocarbon radical containing about 5-10 carbon atoms.
Another aspect of the invention is a process for making an aliphatic tricarboxylic acid having the formula
wherein each of R1 and R2 is independently a divalent aliphatic hydrocarbon radical containing about 5-10 carbon atoms, which comprises the steps of
(a) converting an olefinic monocarboxylic acid to an olefinic dicarboxylic acid by biotransformation in the presence of a yeast, such as strains of Candida tropicalis; and
(b) carboxylating the olefinic dicarboxylic acid to a tricarboxylic acid with carbon monoxide and water in the presence of a catalyst.
Still another aspect of the invention is branched polycarbonates comprising structural units of the formula
wherein each A is independently a divalent aliphatic, alicyclic or aromatic radical, and branching units of formula III derived from at least one compound of formula I:
wherein R1 and R2 are as previously defined.
The R1 and R2 radicals in the tricarboxylic acids of this invention are divalent aliphatic hydrocarbon radicals containing about 5-10 carbon atoms. Most often, each of R1 and R2 is a straight chain alkylene radical. In preferred embodiments R1 is xe2x80x94(CH2)7xe2x80x94 and R2 is xe2x80x94(CH2)8xe2x80x94. Thus, the preferred tricarboxylic acid is 9-carboxy-1,18-octadecanedioic acid, hereinafter sometimes designated xe2x80x9cCODDAxe2x80x9d.
The tricarboxylic acids of the invention may be prepared from olefinic monocarboxylic acids, preferably oleic acid, by a two-step reaction sequence. The first step is the biotransformation of the olefinic monocarboxylic acid to the corresponding olefinic dicarboxylic acid, preferably 1,18-octadec-9-enedioic acid. This biotransformation occurs in the presence of various strains of yeast, including strains of Candida tropicalis, as disclosed in U.S. Pat. Nos. 5,620,878 and 5,962,285, the disclosures of which are incorporated by reference herein. As noted in those patents, a preferred strain of C. tropicalis for this purpose is designated AR40 and that strain was deposited Mar. 9, 1990, with the American Type Culture Collection as ATCC 20987.
The second step is the carboxylation of the olefinic dicarboxylic acid to the acid of formula I. Such carboxylation may be effected by reaction of the olefinic dicarboxylic acid, preferably 1,18-octadec-9-enedioic acid, with carbon monoxide and water in the presence of a catalyst, typically one comprising a transition metal or a noble metal and a ligand, such as palladium chloride-triphenylphosphine. A typical reaction is disclosed in Frankel et al., J. Am. Oil Chem. Soc., 50, 39-43 (1973), the disclosure of which is incorporated herein by reference. Following preparation, the tricarboxylic acid product may be isolated by conventional means.
The tricarboxylic acids of the invention may also be prepared by catalytic carboxylation of oleic acid, followed by biotransformation. It is believed, however, that the preferred method employs biotransformation as the first step.
The A value in the branched polycarbonates of this invention, occurring in the structural units therein having formula II, may be the same or said polycarbonates may contain two or more different units of that formula. Said A values may be aliphatic, alicyclic, aromatic or mixed; those which are aliphatic or alicyclic generally contain up to about 8 carbon atoms. Suitable A values include ethylene, propylene, trimethylene, tetramethylene, hexamethylene, dodecamethylene, 1,4-(2-butenylene), 1,10-(2-ethyldecylene), 1,3-cyclopentylene, 1,3-cyclohexylene, 1,4-cyclohexylene, m-phenylene, p-phenylene, 4,4xe2x80x2-biphenylene, 2,2-bis(4-phenylene)propane, benzene-1,4-dimethylene and similar radicals such as those which correspond to the dihydroxy compounds disclosed by name or formula (generic or specific) in U.S. Pat. No. 4,217,438, the disclosure of which is incorporated by reference herein. Also included are radicals containing non-hydrocarbon moieties. These moieties may be substituents such as chloro, nitro, alkoxy and the like, and also linking radicals such as oxy, thio, sulfoxy, sulfone, ester, amide, ether and carbonyl. Most often, however, all A radicals are hydrocarbon radicals.
Preferably at least about 60% and more preferably at least about 80% of the total number of A values in the mixtures, and most desirably all of said A values, are aromatic. The aromatic A radicals preferably have the formula
xe2x80x83(IV) xe2x80x94A1xe2x80x94Yxe2x80x94A2xe2x80x94,
wherein each of A1 and A2 is a monocyclic divalent aromatic radical and Y is a bridging radical in which one or two atoms separate A1 from A2. The free valence bonds in formula IV are usually in the meta or para positions of A1 and A2 in relation to Y.
The A1 and A2 values may be unsubstituted phenylene or substituted derivatives thereof, illustrative substituents (one or more) being alkyl, alkenyl, halo (especially chloro and/or bromo), nitro, alkoxy and the like. Unsubstituted phenylene radicals are preferred. Both A1 and A2 are preferably p-phenylene, although both may be o- or m-phenylene or one o- or m-phenylene and the other p-phenylene.
The bridging radical, Y, is one in which one or two atoms, preferably one, separate A1 from A2. It is most often a hydrocarbon radical and particularly a saturated radical such as methylene, cyclohexylmethylene, 2-[2.2.1]-bicyclohep-tylmethylene, ethylene, isopropylidene, neopentylidene, cyclohexylidene, cyclopentadecylidene, cyclododecylidene or adamantylidene, especially a gem-alkylene (alkylidene) radical. Also included, however, are unsaturated radicals and radicals which contain atoms other than carbon and hydrogen; for example, 2,2-dichloroethylidene, carbonyl, phthalidylidene, oxy, thio, sulfoxy and sulfone. For reasons of availability and particular suitability for the purposes of this invention, the preferred units of formula IV are 2,2-bis(4-phenylene)propane carbonate units, which are derived from bisphenol A and in which Y is isopropylidene and A1 and A2 are each p-phenylene.
Said branched polycarbonates may be prepared by conventional polycarbonate synthesis methods such as interfacial, transesterification and redistribution methods, or by solid state polymerization as described, for example, in U.S. Pat. Nos. 4,948,871, 5,204,377, 5,266,659 and 5,288,838, the disclosures of which are incorporated by reference herein. All of these methods are the subject of many issued patents and publications, and need not be described in detail herein.
In interfacial and transesterification procedures, the at least one tricarboxylic acid of the invention is typically part of the reaction mixture which includes phosgene or a diaryl carbonate. In redistribution procedures, a tricarboxylic acid is typically added to the polymer to be redistributed. In solid state procedures, a tricarboxylic acid may be incorporated in a reaction mixture which includes a polycarbonate oligomer, with a crystallinity enhancing operation preceding or following incorporation of the acid. The proportion of the at least one tricarboxylic acid employed will depend on the extent of branching desired; most often about 0.05-7.0 mole percent and preferably about 0.1-5.0 mole percent of total tricarboxylic acid based on dihydroxy compound structural units is suitable.
The preparation of the branched polycarbonates of this invention by solid state polymerization employs a precursor polycarbonate as a reactant. Suitable precursor polycarbonates may be prepared by the first step of a melt polycarbonate process or by bischloroformate oligomer preparation followed by hydrolysis and/or endcapping and isolation. Such oligomers most often have an intrinsic viscosity in the range of about 0.06-0.30 deciliters per gram (dl/g), all intrinsic viscosity values herein being as determined in chloroform at 25xc2x0 C.
The precursor polycarbonate may also be a high molecular weight homo- or copolycarbonate; i.e., one having an intrinsic viscosity above 0.30 dl/g. Numerous kinds of suitable high molecular weight homo- and copolycarbonates are suitable, including conventional linear polycarbonates in virgin form. They may be prepared from any of the known dihydroxy compounds useful as monomers, including dihydroxyaromatic compounds such as bisphenol A, SBI and others designated by name or structural formula (generic or specific) in U.S. Pat. No. 4,217,438.
Recycled polycarbonates, for example from compact disks, may also be employed as precursor polycarbonate. Such recycled material typically has a molecular weight which has been degraded from that of the originally polymerized material as shown by an intrinsic viscosity in the range of about 0.25-1.0 dl/g. It may he obtained from scrap polycarbonate by dissolution in a chlorinated organic solvent such as chloroform, methylene chloride or 1,2-dichloroethane followed by filtration of the insoluble material or by other art-recognized procedures for separation of non-polycarbonate constituents. Other types of polycarbonate, such as interfacially prepared polycarbonate and polycarbonate extruder wastes, may also be employed as precursors.
The precursor polycarbonate and at least one tricarboxylic acid of this invention are brought into contact under conditions promoting reaction between them. Such conditions generally involve temperatures in the range of about 170-250xc2x0 C., frequently including staged heating at progressively increasing temperatures. The conditions may be those known in the art to be effective to enhance the crystallinity of the precursor polycarbonate; if not, a subsequent crystallinity enhancement step may be performed. Said conditions may include progressively decreased pressures, starting at atmospheric and terminating at about 100 torr or even lower, although decreasing pressure is not always necessary or even preferred. Diaryl carbonates such as diphenyl carbonate may also be present to provide conditions for an increase in molecular weight.
It is usually preferred, sometimes even necessary, to employ a catalyst during the branching step. Suitable catalysts include those effective in such polycarbonate reactions as melt polymerization, redistribution, equilibration and solid state polymerization. A wide variety of bases and Lewis acids are useful for this purpose. They include the catalysts disclosed in U.S. Pat. Nos. 5,414,057 and 5,717,056, the disclosures of which are incorporated by reference herein. Examples are alkali metal hydroxides and alkoxides; metal, especially alkali metal, hydrides and borohydrides; organotin and organotitanium compounds; aliphatic and heterocyclic amines; phosphines; and tetraalkylammonium and tetraalkylphosphonium hydroxides, alkoxides, carboxylates and tetraphenylborates. Also included are quaternary bisphenolates such as those disclosed in U.S. Pat. No. 5,756,843, all of said patents being incorporated by reference herein. The quaternary bisphenolates may be represented by the formula
xe2x80x83H3Q[(OA)2Y]2,
wherein A is unsubstituted p-phenylene, Q is a monocationic carbon- and nitrogen-containing moiety containing 9-34 atoms and Y is a bridging radical in which one or two carbon atoms separate the A values. Particularly suitable quaternary bisphenolates are those in which Y is isopropylidene and Q is a hexaalkylguanidinium cation, especially hexaethylguanidinium.
The product of the branching step is a branched polycarbonate precursor, generally of enhanced crystallinity. The solid state polymerization step may be effected thereon (or, if necessary, after a conventional crystallinity enhancement step) at a temperature between the glass transition temperature and the melting temperature of the enhanced crystallinity polycarbonate precursor, most often about 10-50xc2x0 C. below its melting temperature. In general, temperatures in the range of about 150-270xc2x0 and especially about 180-250xc2x0 C. are suitable.
As disclosed in U.S. Pat. No. 4,948,871 and the aforementioned U.S. Pat. Nos. 5,204,377 and 5,717,056, the solid state polymerization step may be achieved in the absence or presence of catalysts. When present, catalysts may often be the same as those employed in the branching step and may function in both steps without further catalyst addition.
Solid state polymerization may be conducted in a mixer capable of producing intimate gas-solid contact, such as a fixed bed, fluidized bed or paddle mixer, in contact with an inert gas such as nitrogen or argon which serves as the fluidizing gas if a fluidized bed is employed. Said inert gas may serve one or both of the purposes of fluidizing the mixture, and volatilizing and removing by-products, including water, hydroxyaromatic compound (such as phenol) corresponding to the carbonate employed to produce the branched precursor copolycarbonate, and any volatile carbonate formed as a by-product. Programmed heating may be advantageously employed. As an alternative to conditions of intimate gas-solid contact, the polymerization may be conducted at reduced pressure, typically less than about 100 torr, preferably with efficient mixing.
Ester unit s may be incorporated in the polycarbonate by the use of a corresponding dicarboxylic acid or acid chloride in an interfacial procedure or the use of a dialkyl or diaryl, most often a diphenyl, ester of said acid in a melt or solid state procedure.

Tricarboxylic acids, method, and branched polycarbonates prepared therefrom


An image processing apparatus includes a first log conversion unit configured to execute gradation conversion processing for copying on an image signal generated by reading an original, an output-signal converting unit configured to generate an output signal from the image signal subjected to the gradation conversion processing for copying and output the output signal to an output apparatus, a second log conversion unit configured to be provided independently from the first log conversion unit and execute gradation conversion processing for specific original detection on the image signal generated by reading the original, and a specific-original detecting unit configured to detect whether the original is a specific original from the image signal subjected to the gradation conversion processing for specific original detection.

In general, in an image forming apparatus such as a digital copying machine that handles image information, reading means such as a scanner reads an original. Image information read and digitized is multi-valued, processed according to a purpose, and outputted from an output apparatus such as a laser printer.
An image forming apparatus such as a color multifunction peripheral that forms a color image has a specific image discriminating function. The specific image discriminating function discriminates whether a read original is a specific original such as a bill or a marketable security. When an input image is the specific original, an output apparatus prohibits copying of the input image by, for example, entirely painting the image in black (JP-A-2005-184497).

Image processing apparatus, image processing method and image reading apparatus


Osmium, when combined with boron alone, or in combination with rhenium, ruthenium or iron, produces compounds that are ultra-hard and incompressible. These osmium diboride compounds are useful as a substitute to for other super or ultra-hard materials that are used in cutting tools and as abrasives. The osmium diboride compounds have the formulaOsxM1-xB2 where M is rhenium, ruthenium or iron and x is from 0.01 to 1, except when x is not 1 and M is rhenium, x is from 0.01 to 0.3.

1. Field of the Invention
The present invention relates generally to super hard, incompressible materials. More particularly, the invention is directed to the discovery that osmium, when combined with boron alone, or in combination with rhenium, ruthenium or iron, produces compounds that are ultra-hard and incompressible. These osmium diboride compounds are useful as a substitute to for other super or ultra-hard materials that are presently being used in cutting tools and as abrasives.
2. Description of Related Art
The publications and other reference materials referred to herein to describe the background of the invention and to provide additional details regarding its practice are hereby incorporated by reference. For convenience, the reference materials are numerically referenced and identified in the appended bibliography.
High bulk modulus, superhard materials are of great interest due to their usefulness in a wide variety of industrial applications. These include abrasives, cutting tools, and coatings where wear prevention, scratch resistance, surface durability and chemical stability are a priority.[1,2] Therefore, the development of a new class of superhard materials is of great practical interest. Past research suggests the general idea that melting points can be related to hardness and that the addition of carbon, nitrogen, or boron to transition metals will often form hard materials.[3]
Hardness is a measure of a material's resistance to plastic indentation under an applied load. The deformation of the material is manifested through shear deformation, volume compression, bond-bending, and dislocations.[4] A high shear modulus reflects the material's ability to undergo compression without deforming in any direction. This is related to the material's ability to resist volume compression and is reflected in a high bulk modulus.[5,6] Therefore, a design goal is to find a material that possesses a high bulk modulus.[7-9]
The compressibility of a wide variety of substances can be directly correlated with the densities of their valence electrons, electrons/Å3.[10] For example, diamond, the hardest known substance, has a valence electron density of 0.705 electrons/Å3 and an exceptionally high bulk modulus (B0=442 GPa).[11] Maximizing the valence electron density is therefore a potentially useful design parameter in the search for new high bulk modulus materials. Osmium metal has one of the highest valence electron densities for a pure metal (0.511 electrons/Å3) and recent measurements of its bulk modulus give values in the range of 411-462 GPa.[12,13] While one measurement actually suggests that osmium metal is less compressible than diamond, both experiments agree that it is a highly incompressible material. Although the bulk moduli of diamond and osmium are very close, their hardnesses vary greatly due to differences in the mobilities of their dislocations.[5] Diamond has a hardness of 8000-10,000 kg/mm2, while osmium metal has a hardness of only 400 kg/mm2.[14,15] The deviation can be explained simply: osmium is metallic, whereas diamond is purely covalent. The atomic orbitals in diamond are all sp3 hybridized, and overlap to form short, directional, highly covalent bonds in an infinite tetrahedral network. The strength and directionality of the bonds determine the material's ability to resist deformation.[4,8] In contrast, osmium's hexagonally close-packed crystal structure has a Fermi-liquid of valence electrons which do not participate in localized or directional bonding, and therefore offer little resistance to dislocation motion.
While many transition metals are soft in their pure elemental state, they can be converted into hard materials by combining them with small, covalent main group elements such as boron, carbon or nitrogen. For example, consider the third row transition metal tungsten. The hardness of tungsten is increased from 900 kg/mm2 to 1400 kg/mm2 by the addition of boron to form tungsten diboride, WB2. Alternatively, tungsten can be combined with carbon to form tungsten carbide, WC, which increases the hardness to 3000 kg/mm2.[14]

Osmium diboride compounds and their uses

The Regents of the University of California


A cowl for an outboard marine propulsion device having an internal combustion engine. The cowl comprises a first cowl portion; a second cowl portion that mates with the first cowl portion to enclose the internal combustion engine; a service door on the second cowl portion, wherein the service door is positionable in an open position and in a closed position; and a carrying handle on the second cowl portion, wherein the carrying handle is accessible when the service door is in the open position and inaccessible when the service door is in the closed position. A plurality of latches are spaced apart around the perimeter. The latches latch the second cowl portion to the first cowl portion. An actuator assembly actuates each of the plurality of latches. The actuator assembly can be actuated by movement of the carrying handle.

U.S. patent application Ser. No. 14/721,106 is hereby incorporated herein by reference in entirety and discloses a latching apparatus for a cowl on an outboard marine engine. The cowl has a first cowl portion and a second cowl portion, which are latched together by the latching apparatus in a closed cowl position and unlatched from each other in an open cowl position. The latching apparatus comprises a retainer on the first cowl portion; an actuator device on the second cowl portion; and a wire coupled to the actuator device. The wire is coupled to the retainer in the closed cowl position and the wire is uncoupled from the retainer in the open cowl position. Actuation of the actuator device in a first direction rotates the wire so as to couple the wire to the retainer and actuation of the actuator device in a second direction rotates the wire so as to uncouple the wire from the retainer.
U.S. Pat. No. 4,348,194 is hereby incorporated herein by reference in entirety and discloses a cowl for the power head of an outboard motor that includes two bottom cowl members attached together by screws which also mount a latch bracket and a hinge member. The latch bracket supports a latch mechanism which, with the hinge member serves to hold a top cowl member in place.

Cowls and latching assemblies for cowls on outboard marine propulsion devices


A circuit for controlling the read cycle includes plurality of shift stages configured to sequentially shift read signals; and an activating unit configured to activate a read cycle signal which represents a read cycle, by performing logical operation for output signals of the plurality of the shift stages, wherein the plurality of the shift stages are configured to sequentially shift the read signals for a period corresponding to burst setting information.

The present invention relates to a semiconductor memory device, and more particularly, to a technology for controlling a read cycle of a semiconductor memory device.
A semiconductor memory device continuously outputs the number of bits of data depending on a Burst length BL. For a burst length BL of 4, 4 bits of data are continuously outputted, and for a burst length BL of 8, 8 bits of data are continuously outputted. Therefore, a duration of a read cycle of the semiconductor memory device varies depending on a set value of the burst length BL.
FIG. 1 is a block diagram of a circuit for controlling a conventional read cycle.
As shown in FIG. 1, the circuit for controlling the conventional read cycle includes an SR latch 110, and a counter block 120.
The SR latch 110 activates a read cycle signal ROUTEN in response to a read signal RD, and inactivates a read cycle signal ROUTEN in response to a reset signal RST.
The counter block 120 activates the reset signal RST after 2 clock cycles or 4 clock cycles from a timing point at which read cycle signal ROUTEN is activated. The timing point at which the counter block activates the reset signal is determined by burst setting information. When the burst length BL is set to 8, the counter block activates a reset signal RST after 4 clock cycles from the timing point at which the read cycle signal ROUTEN is activated. When the burst length BL is set to 4, the counter block activates a reset signal RST after 2 clock cycles from the timing point at which the read cycle signal ROUTEN is activated.
The read signal RD is activated when a read commend is applied from an outside of a chip, and the read cycle signal ROUTEN is used to define a period at which bits of data are outputted from the memory device. Therefore, the read cycle signal ROUTEN has a period varied depending on the burst length BL.
FIGS. 2A and 2B are timing diagrams illustrating an operation of FIG. 1.
FIG. 2A illustrates an operation of the circuit for controlling the read cycle when the burst length BL is set to 4 (in a BC4 mode for DDR3 where a BL4 is impossible in principle). FIG. 2B illustrates an operation of the circuit for controlling the read cycle when the burst length BL is set to 8.
Referring to FIG. 2A, the SR latch 110 activates the read cycle signal ROUTEN simultaneously while the read signal RD is active.
The counter block 120 activates the reset signal RST after 2 clock cycles from the timing point at which the read cycle signal ROUTEN is activated. Then, the SR latch 110 inactivates the read cycle signal ROUTEN in response thereto. In this case, the read cycle signal ROUTEN is active for 2 clock cycles, which corresponds to time required for stream output of 4 bits of data.
Referring to FIG. 2B, the SR latch 110 activates the read cycle signal ROUTEN simultaneously with the activation of the read signal RD. The counter block 120 activates the reset signal RST after 4 clock cycles from the timing point at which the read cycle signal ROUTEN is activated. Then, the SR latch 100 inactivates the read cycle signal ROUTEN in response thereto. In this case, the read cycle signal ROUTEN is active for 4 clock cycles, which corresponds to time required for stream output of 8 bits of data.
FIG. 3 is a timing diagram illustrating a problem with respect to the circuit for controlling the conventional read cycle shown in FIG. 1 when a read command is continuously applied.
Due to a short margin for distinguishing signals in the semiconductor memory device, the reset signal RST is not activated at an accurate timing, and is activated after a slight delay. FIG. 3 illustrates such a problem.
As shown in FIG. 3, when a reset signal RST 304 corresponding to a first read signal RD 301 is activated at a timing later than that of a second read signal RD 302, a read cycle signal ROUTEN corresponding to the second read signal RD 302 is inactivated simultaneously while the reset signal RST 304 is active. Therefore, in this case, a read cycle corresponding to the second read signal RD 302 is skipped, and a read operation fails to be performed in the memory device.

Circuit and method for controlling read cycle