In accordance with the present disclosure a directionally biased staple is provided for use in all types of surgical staplers having anvil structure against which the staple is formed. The directionally biased staple may be constructed in a wide variety of cross-sectional configurations including rectangular, elliptical, trapezoidal, etc. All of the configurations are distinguished by having a bending region requiring more force to twist or malform the staple than is required to properly form the staple. Preferably, these staples have Moment of Inertia Ratios on the order of between about 1.1 to about 3.0. The staple preferably corresponds in other respects to conventional formed staples, i.e. having at least a pair of leg members interconnected by a crown portion wherein the leg members are formed by direct contact with the anvil. An anvil assembly is also provided for minimizing the malformation of staples.

1. Technical Field
This invention relates to formable surgical fasteners and, more particularly, to directionally biased formable staples for use in surgical staplers having anvil pockets for forming the staples. This invention also relates to anvil assemblies including anvil pockets for use with surgical staplers.
2. Background of Related Art
Surgical stapling instruments have become critical to many life saving surgical procedures. Surgical staples are usually mechanically inserted into tissue with surgical stapling instruments such as those known as anastomosis devices, including gastrointestinal anastomosis devices and transverse anastomosis devices. In such devices, the staples are loaded in one or more elongated rows into a cartridge. A mechanism for pushing, or driving the stapler is actuated to drive the staples through two or more sections of tissue toward a deforming anvil. At the conclusion of the driving operation, the legs of each staple are conventionally clamped or bent, by the anvil, to a closed configuration to complete the suture and join the tissue sections together. Gastrointestinal anastomosis-type devices drive and bend the staples aligned in a row sequentially in rapid sequence, while transverse anastomosis-type devices drive and bend all staples simultaneously. See, e.g. U.S. Pat. Nos. 4,520,817 and 4,383,634. Circular anastomosis-type devices simultaneously apply annular rows of staples to tissue. See, e.g. U.S. Pat. No. 4,304,236.
One type of conventional staple 20, shown in FIGS. 1-3, used with both gastrointestinal anastomosis and transverse anastomosis-type surgical stapling devices is made of stainless steel or titanium. The undeformed staple 20 (FIG. 1) is generally U-shaped and includes a back span 22 and two legs 24 depending substantially perpendicularly from the back span. Each leg 24 has a sharp chiseled end point 26 for piercing body organs or tissue. The chisel point also creates torque in the staple, allowing it to form. The staple penetrates the tissue from one side to engage an anvil spaced apart and located at an opposing side of the tissue. The staple is bent by having the legs engage and follow an anvil 25 to form a B-shaped closed staple 28 as shown in FIG. 2. In this closed configuration tissue is compressed between the legs and backspan of the staple.
Because of their substantially circular cross-section (FIG. 3), these conventional staples require approximately the same amount of force to form the staple into its final shape as is required to twist or malform it.
For example, referring back to FIG. 3, a conventional round cross section staple has a moment of inertia in the x forming dimension (Ix) given by the equation:Ix=¼—r4 Its moment of inertia in the y twisting dimension (Iy) is given by the same equation:Iy=¼—r4 Using a round wire stock of uniform 0.009 in diameter (r =0.0045),
                              I          x                =                              I            y                    =                                    1              /              4                                    _                                                      (                .0045                )                            4                                                              =                  3.22          ×                      10                          -              10                                                                                in            4                              The Moment of Inertia Ratio, given by the equation:is Iy/Ix
            3.22      ×              10                  -          10                                                            in        4                    3.22      ×              10                  -          10                                                            in        4              =  1In order to insure accurate and consistent formation of these conventional staples, considerable research and development has been conducted in the areas of forming and driving structures. For example, anvils have been developed with specific coatings and/or structure, see, e.g. U.S. Pat. Nos. 5,173,133 and 5,480,089. Also, staple cartridges have been configured with driver structure to balance forces encountered during staple formation. See, commonly assigned U.S. Pat. No. 4,978,049 to Green. Thus, to control and insure consistent staple formation without twisting or deformation, extremely strict manufacturing tolerances have been implemented.
Other types of staples for different types of instruments are also found in the prior art. Some have non-circular cross-section. FIGS. 4, 4A and 4B illustrate by way of example a staple of this type marketed by United States Surgical of Norwalk, Conn. for use with its MULTIFIRE ENDO HERNIA and ENDO UNIVERSAL 65 staplers. The anvil in these staplers, as shown in FIGS. 4C and 4D, is adjacent the backspan of the staple as tissue is approached from only one side. Unlike the staples described above which are formed by contact of the staple legs with anvil pockets, these staple legs are bent around an anvil abutting the backspan. This staple has a side portion H with a height dimension greater than the dimension of the base portion B (i.e. 0.020 in vs. 0.015 in.).
The Moment of Inertia Ratio is given by the equation:
                              Moment                                                              of                                                              Inertia                                                              Ratio                =                              I            y                                I            x                                                  =                                                                              Moment                                                                                of                                                                                Inertia                                                                                About                                                                                Twisting                                                                                Axis                                                                                Moment                                                                                of                                                                                Inertia                                                                                About                                                                                Forming                                                                                Axis                                                                        where Ix=( 1/12)bh3 and Iy=( 1/12)hb3, with h=0.020 in. and b=0.015 in.Thus, Ix=( 1/12)(0.015)(0.020)3=1.0×10−8 in4, andIy=( 1/12)(0.020)(0.015)3=6.0×10−9 in4.Accordingly,
      Moment                          of                          Inertia                          Ratio    =                    6.01        ×                  10                      -            9                                                                              in          4                            1.10        ×                  10                      -            8                                                                              in          4                      =                  .60        /        1            =      .60
This staple is specifically configured to accommodate twisting during staple formation to permit the legs of the staple to cross as shown in FIG. 4E. Thus, it is engineered so the force to form the staple is slightly greater than the force to malform or twist the staple. The forming is accomplished by bending the staple legs around an anvil positioned adjacent the inner surface 32 of the backspan 34.
U.S. Pat. No. 5,366,479 describes a hernia staple with adjacent anvil having a height of 0.38 mm and a thickness of 0.51 mm. This staple is formed the same way as in FIGS. 4C and 4D. The moment of inertia ratio of this staple in accordance with the foregoing formula is as follows:Ix=( 1/12)(0.51)(0.38)3=2.33×10−3 Iy=( 1/12)(0.38)(0.51)3=4.2×10−3
      Moment                          of                          Inertia                          Ratio    =                    4.2        ×                  10                      -            3                                      2.33        ×                  10                      -            3                                =    1.8
This staple for use as described would actually result in greater force to produce the desired shape. In fact, the staple legs would likely contact each other before crossing over into their crossed configuration.
Thus, it is apparent that this type of hernia staple, i.e. where the anvil is adjacent the backspan as the tissue is approached from only one side, is quite different than the staple of the present invention, e.g. the B-shaped staple, wherein the legs penetrate through the tissue to contact anvil pockets. These anvil pockets direct the staple legs to form the staple into a closed configuration. Thus staple configuration and considerations of twisting, bending and staple formation of these hernia staples are inapplicable to these considerations for anvil pocket directed staples, such as the B-shaped staples.
It would therefore be desirable to provide a staple configuration for a staple designed to penetrate tissue and contact an anvil pocket on the opposing side of tissue, which, in complement with conventional cartridge and anvil technology, enhances correct staple formation while reducing twisting/malformation caused by misalignment or unusual tissue while minimizing reliance on strict manufacturing tolerances. It would also be desirable to provide an anvil assembly which would minimize staple malformations by misalignment or twisting during formation of the staple.

Directionally biased staple and anvil assembly for forming the staple


A front end structure of a vehicle body may include: a pair of left and right front side members each extending in a vehicle front-rear direction; a pair of left and right apron upper members each extending in the vehicle front-rear direction and being located outward of the pair of left and right front side members in the vehicle left-right direction; a pair of left and right connection members, the left connection member extending between an intermediate portion of the left front side member and the left apron upper member and the right connection member extending between an intermediate portion of the right front side member and the right apron upper member; and a component mount frame comprising a first mount crossmember extending between the pair of left and right connection members in the vehicle left-right direction.

A front end structure of a vehicle body is described in Japanese Patent Application Publication No. 2011-20628. This front end structure includes a pair of left and right front side members each extending in a vehicle front-rear direction and a pair of left and right apron upper members each extending in the vehicle front-rear direction, with the left apron upper member located outward of the left front side member and the right apron upper member located outward of the right front side member. A component mount frame on which components such as a power conversion unit are mounted is fixed to the pair of left and right front side members.

This patent is subject to a terminal disclaimer.


A telephone call initiated from a first network and directed to a second network at which network resources are temporarily unavailable to route and/or switch that call, is completed by a) estimating the anticipated time before these resources can become available, b) offering the caller the option of being called back, based on that estimation, c) calling back the caller when network resources are expected to become available, d) establishing a connection from the first network to the called party at the second network, and e) merging the two calls.

Over the last few years, unprecedented growth in international business transactions has resulted in a corresponding increase in the demand for international communications services. To satisfy that increased demand, international communications carriers have deployed and continue to deploy additional transmission facilities, such as satellite communication links and undersea fiber optic cables, to connect, for example, international gateway switches between different countries. In addition, a number of carriers have implemented in their international telecommunications transmission systems alternate routing systems as part of a comprehensive plan for disaster recovery and network overflow management. These systems allow the establishment of communication paths between two international destinations via alternate transmission facilities when point-to-point first choice-circuit routes are unavailable (not in service or busy).
In spite of these investments and technological advances, calls to certain international destinations are sometimes completed only after a substantial number of repeated call attempts. The root cause of this unfortunate situation has been traced back to the overloaded and/or outdated conditions of the telecommunications systems of these destinations. Indeed, during busy hour periods at those destinations, even repeated call attempts are too often unavailing.
As is well known, high incidences of repeated unsuccessful call attempts cause increased congestion and reduced traffic-carrying capacity in a network. Callers' frustration and inefficient use of domestic and international trunks are the ultimate results. Furthermore, for international business callers who have to conduct critical business transactions over the phone within time windows sometimes made smaller by time zone differences, predictability in the call completion process is of paramount importance. Callers from countries accustomed to near one hundred percent, first try call completion, are clamoring for at least greater convenience if not their accustomed level of service for their international calls to these destinations.

International priority calling system with callback features


A transmission frame comprises a synchronization flag and data bits. It is formed of at least a first subframe in which occur the synchronization flag and an identification field which specifies the number of subframes. Each of the other subframes comprises blocking bits disposed so that the synchronization flag cannot occur in the subframes unless in conjunction with the first subframe.

Description of the Prior Art
In a system of synchronous communication between data processing equipments one of the most widely used methods for sending messages consists in defining a frame structure characterized by:
a synchronization flag, PA1 special coding of the data to be transmitted so that the synchronization flag cannot be recognized in the middle of the data stream transmitted. PA1 if a first subchannel is identified the second subchannel corresponds to a second subframe, PA1 if a half-rate frame is identified, recognition of the synchronization pattern in the second subchannel implies the presence of a half-rate frame.
One of the best known ways to implement this method is to choose a flag which is a constant stream of P binary zeros followed by a binary 1. The data is then coded simply by inserting a binary 1 each time that a series of (P-1) binary 0 has been transmitted. For example, if the flag is `00001`, the message `0010 0000 10` is transmitted in the form: `00001 0010 00100 10`. The six underlined digits represent the synchronization flag and the inserted binary 1 (the spaces are included only to facilitate reading).
This method has a drawback: the time to transmit a message depends on its contents, which is a serious problem if a fixed routing time is required.
The known solution to this problem is to insert a binary 1 every (P-1) data bits transmitted: it is then certain that P consecutive binary zeros will never be encountered and the transmission time is always the same, regardless of the data transmitted. A well-known example of this method is the use of V.110 frames as defined by the CCITT (Comite Consultatif International du Telephone et du Telegraphe). These frames comprise a flag made up of eight binary zeros followed by a binary 1, a binary 1 being then inserted every seven bits to form a frame of 80 bits, 17 bits used for synchronization and 63 bits for the data.
A frame can be represented by a table with P columns and L rows. The first row, known as the locking row, includes P binary zeros and subsequent rows, known as data rows, each comprise a synchronization bit at binary 1 followed by (P-1) data bits.
When data is transmitted by means of such frames the transmission channel often has a data signaling rate which is greater than that required to convey the frames produced by an equipment.
To economize on transmission channels it is natural to use multiplexing whereby the channels are divided into subchannels so that the data signaling rate of one subchannel conveys the data from one equipment.
For example, a full-rate channel comprises two half-rate subchannels, the bits of the channel being bits from each of the two subchannels alternately. Thus the odd-numbered bits of the channel are from a first subchannel and the even-numbered bits of the channel are from a second subchannel.
This use of a channel to convey two subchannels is feasible but it rules out the interchangeable use of two half-rate subchannels or one full-rate channel because the simultaneous reception of two subchannels can be interpreted as the reception of a single full-rate channel.
If a full-rate frame of P columns and L rows and a half-rate frame of P' columns and L' rows are chosen, with an even value for P an advantageous solution is to take P'=P/2 and L'=L.
The full-rate frame can be divided into first and second subframes respectively comprising the odd-numbered bits and the even-numbered bits of the full-rate frame. The first subframe is identical to the half-rate frame and the second subframe begins with a locking row of P' consecutive binary 0 followed by P'.multidot.(L-1) data bits.
Given that the first subframe is identical to the half-rate frame and that the locking row of P' consecutive binary 0 can appear in the second subframe or in the half-rate frame, some means of discrimination is required.
One simple means of discrimination is to provide an identification field which is substituted for data bits and indicates either a subframe or a half-rate frame. For example, a header bit can be replaced with a binary 0 in the subframe so that the receiver detects a synchronization error in the full-rate frame. The receiver must always receive a binary 1 at the start of a data row. However, if the header bit is forced to binary 0, binary 1 bits must be inserted on either side of this binary 0 bit to prevent the occurrence of P' consecutive binary 0.
A synchronization pattern is then defined as the combination of the synchronization flag and the identification field.
The synchronization pattern can occur in a half-rate frame or in the second subframe of a full-rate frame, since the latter includes a sequence of P'.multidot.(L-1) indeterminate bits.
It is assumed that the first and second subframes of a half-rate frame are conveyed by respective first and second subchannels.
It is clear that it is not possible to tell whether the subchannel is conveying a half-rate frame or the second subframe of a full-rate frame by analyzing the subchannel only. The data specifying the nature of the second subchannel is available only in the first subchannel. It is therefore necessary to wait for the processing to identify the first subchannel:
Thus if the second subchannel conveys a half-rate frame, processing of this frame is deferred until the end of the identification processing. This introduces an undesirable time-delay into the transmission system.
Although the processing of the first subchannel is independent, the processing of the second subchannel is conditioned by the processing of the first subchannel. It follows that the modules processing each subchannel must communicate with each other, which complicates the implementation of the receiver.
An object of the present invention is therefore a frame structure defining a full-rate frame and a halfrate frame and a transmitter and a receiver between which such frames are exchanged and which can process a halfrate frame without any time-delay.

Transmitter, receiver and frame supporting various data signaling rates


Antimicrobial/pharmaceutical preparations (e.g., solutions, gels, ointments, creams, sustained release preparations, etc.) which comprise chlorite (e.g., a metal salt of a chlorite) in combination with a peroxy compound (e.g., hydrogen peroxide), and methods for using such preparations for disinfection of articles or surfaces (e.g., contact lenses, counter tops, etc.), antisepsis of skin or other body parts, prevention or deterrence of scar formation and/or treatment and prophylaxis of dermal (i.e., skin or mucous membrane) disorders (e.g., wounds, burns, infections, cold sores, ulcerations, psoriasis, acne, or other scar-forming lesions).

The present invention relates generally to medical compositions and methods, and more particularly to certain disinfectant/antimicrobial preparations and methods for using such preparations i) to disinfect articles or surfaces, ii) as a topical antiseptic for application to body parts, and iii) to prevent or deter scar formation and iv) to treat dermatological disorders such as wounds, burns, ulcers, psoriasis, acne and other scar forming lesions.
The prior art has included numerous antimicrobial agents which have purportedly been useable for disinfection of various articles and/or for topical application to a living being for antisepsis and/or treatment of dermal disorders (e.g., wounds, burns, abrasions, infections) wherein it is desirable to prevent or deter microbial growth to aid in healing. Such topical antimicrobial agents have contained a variety of active microbicidal ingredients such as iodine, mercurochrome, hydrogen peroxide, and chlorine dioxide.
Chlorite, a precursor of chlorine dioxide, is known to be useable as a disinfectant for drinking water and as a preservative for contact lens care solutions. However, chlorite exhibits only weak microbicidal activity within a concentration range that is acceptable and safe for topical application to the skin (e.g., 200-1000 parts per million). Thus, chlorite has not been routinely used as an active microbicidal ingredient in preparations for topical application to the skin.
In view of the limited usefulness of chlorite as an antiseptic or topical microbicide, various compositions and methods have been proposed for activation or enhancement of the microbicidal activity of chlorite. Examples of such compositions and methods for activation or enhancement of the microbicidal activity of chlorite are described in U.S. Pat. No. 4,997,616 (describing general activation); U.S. Pat. No. 5,279,673 (describing acid activation) and U.S. Pat. No. 5,246,662 (describing transitional metal activation).
Chlorine dioxide (ClO2) and xe2x80x9cstabilized chlorine dioxidexe2x80x9d are known to be useable as antiseptics. Chemically, chlorine dioxide is an oxidizing agent which has strong microbicidal activity. Chlorine dioxide is generally regarded as superior even to gaseous chlorine, in certain water treatment applications where it is used as to eliminate algae and other organic material and/or to remove odors or tastes. Chlorine dioxide is also effective as a microbicide, for elimination of bacteria, viruses, and microbial spores.
In addition to its use as a microbicide, chlorine dioxide is a highly reactive, unstable radical which is useable as an oxidizing agent in a number of other chemical and biochemical applications. For example, as described in U.S. Pat. No. 4,855,135, chlorine dioxide can be used for (a) oxidation of double bonds between two carbon atoms; (b) oxidation of unsaturated fatty acids (lipids) via double bonds between two carbon atoms; (c) acceleration of hydrolysis of carboxylic anhydrides; (d) oxidation of aldehydes to the corresponding carboxylic acids; (e) oxidation of alcohols; (f) oxidation of amines; (g) oxidation of phenols, phenolic derivatives and thiophenolic compounds; (h) moderate oxidation of hydroquinones; (i) oxidation of amino acids, proteins and polyamides; (j) oxidation of nitrates and sulphides; and (k) alteration of the CHO and CH2OH radicals of carbohydrates to produce carboxylic functionality.
Concentrated chlorine dioxide in its liquid or gaseous state is highly explosive and poisonous. As a result, concentrated chlorine dioxide must be handled and transported with great caution. For this reason, it is generally not feasible to dispense pure chlorine dioxide for use as a topical antimicrobial agent or disinfectant. Instead, same antimicrobial or disinfectant preparations have been formulated to provide for xe2x80x9cacid generationxe2x80x9d of chlorine dioxide. Such acid generation solutions contain a metal chlorite (i.e., a precursor of chlorine dioxide available in powdered or liquid form) in combination with an acid which will react with the chlorite to liberate or release chlorine dioxide. Generally, any acid may be used for acid generation of chlorine dioxide, including strong acids such as hydrochloric acid and sulfuric acid and relatively weak acids such as citric and tartaric acid. Drawbacks or problems associated with these prior chlorine dioxide generating systems include a) the inconvenience of handing two separate containers or chemical components, b) the difficulty of delivering such two-component systems to the intended site of application, and c) the fact that these prior systems are of acid, rather than neutral, pH. Moreover, the prior chlorine dioxide generating systems which utilize acid-induced generation of chlorine dioxide can, if uncontrolled, cause the generation of chlorine dioxide to occur quite rapidly and, as a result, the disinfectant or antimicrobial potency of the solution may be short lived. Increasing the concentration of chlorite and acid within the solution may prolong its disinfectant or antimicrobial shelf life, but such increased concentrations of these chemicals can result in toxicities or (in topical applications) skin irritation. Such increased concentrations may also result in the generation of more chlorine dioxide than is required.
Various methods have been described to limit or control the rate at which chlorine dioxide is produced in xe2x80x9cacid generationxe2x80x9d solutions. For instance, U.S. Pat. No. Re. 31,779 (Alliger) describes a germicidal composition which comprises a water soluble chlorite, such as sodium chlorite, in combination with lactic acid. The particular composition possesses improved disinfectant properties, properties not attained by using the same composition but replacing the lactic acid with other acids such as phosphoric acid, acetic acid, sorbic acid, fumaric acid, sulfamic acid, succinic acid, boric acid, tannic acid, and citric acid. The germkilling composition is produced by contacting an acid material containing at least 15% by weight of lactic acid with sodium chlorite in aqueous media, the amount of lactic acid being sufficient to lower the pH of the aqueous media to less than about 7. The methods disclosed of disinfecting and sanitizing a germ-carrying substrate, such as skin, include either application of the germ-killing composition, or application of the reactants to provide in situ production thereof. Also, U.S. Pat. No. 5,384,134 (Kross) describes acid induced generation of chlorine dioxide from a metal chlorite wherein the chlorite concentration is limited by the amount of available chlorous acid. In particular, the Kross patent describes a method for treating dermal disorders wherein a first gel, which comprises a metal chlorite, is mixed with a second gel, which comprises a protic acid. The chlorite ions present in such solution as chlorous acid purportedly comprise no more than about 15% by weight of the total chlorite ion concentration in the composition, and the mixture of the two gels purportedly generates chlorine dioxide over an extended time of up to 24 hours.
Other prior patents have purported to describe the use of xe2x80x9cstabilizedxe2x80x9d chlorine dioxide as a means of chlorine dioxide generation. The term stabilized chlorine dioxide refers to various compositions in which the chlorine dioxide is believed to be held in solution in the form of a labile complex. The stabilization of chlorine dioxide by the use of perborates was disclosed in U.S. Pat. No. 2,701,781 (de Guevara). According to the de Guevara patent, an antiseptic solution of stabilized chlorine dioxide can be formed from an aqueous solution of chlorine dioxide and an inorganic boron compound with the boron compound and the chlorine dioxide being present in the solution as a labile complex. The chlorine dioxide, fixed in this stable condition, is an essential ingredient of the antiseptic solution. The de Guevara patent discloses that the chlorine dioxide may be introduced into the compositions either by in situ generation or it may be generated externally and introduced into the solution, as by bubbling the chlorine dioxide gas into the aqueous solution. Various methods may be employed for the external production of the chlorine dioxide, such as reaction of sulfuric acid with potassium chlorate or the reaction of the chlorate with moist oxalic acid. Alternatively, chlorine dioxide can be generated in situ by reaction of potassium chlorate and sulfuric acid. Note that whether the chlorine dioxide is produced in situ or externally, it is essentially an acid induced liberation of the chlorine dioxide from potassium chlorate.
U.S. Pat. No. 4,317,814 (Laso) describes stabilized chlorine dioxide preparations for treatment of burns in humans. Aqueous mixtures of perborate stabilized solutions of chlorine oxides, such as chlorine dioxide, in combination with glycerin are described for topical application to burned areas and may also be administered by oral application for treatment of burns. The aqueous solutions of perborate stabilized chlorine oxides are disclosed as being prepared by mixing with water the following: sodium chlorite, sodium hypochlorite, hydrochloric acid, sulfuric acid, an inorganic perborate, and a peroxy compound, such as sodium perborate. Thus, the solutions prepared in accordance with the Laso patent contain chlorine dioxide, hypochlorite and peroxy compounds as strong oxidizing agents and appear to utilize acid activation of the chlorine dioxide. The Laso patent states that the methods disclosed therein resulted in an immediate subsidence of burn related pain in many cases, that healing was rapid and characterized by an absence of infection or contraction, and that the burn scars were smooth and resembled normal tissue, thus eliminating the need for plastic surgery in certain cases. However, long term storage and stability are issues with the aqueous solutions described in the above-identified Laso patent, because such mixtures tend to generate chlorine dioxide very quickly, thus diminishing the long term stability of such mixtures.
U.S. Pat. No. 3,271,242 (McNicholas et al.) describes stabilized chlorine dioxide solutions which are formed by combining chlorine dioxide gas with an aqueous solution containing a peroxy compound, and subsequently heating the solution to a temperature which is high enough to drive off all free peroxide, but low enough not to destroy the chlorine dioxide. McNicholas et al. States that temperatures xe2x80x9cmuch belowxe2x80x9d 70 degrees C. are ineffective to drive of the free peroxide in the solution and that tempratures should not exceed 92 degrees C. because at higher temperatures the chlorine dioxide will be driven off. McNicholas further states that, although not xe2x80x9centirely understood,xe2x80x9d it was believed that heating of the solution to drive off free peroxide was necessary because any free hydrogen peroxide allowed to remain in the solution would act as a leaching agent to release the chlorine dioxide from the solution.
Antibiotic compounds have also been commonly used for the therapeutic treatment of burns, wounds and skin infections. While antibiotics may provide an effective form of treatment, several dangers are often associated with the use of antibiotics in the clinical environment. These dangers may include but are not limited to: (1) changes in the normal flora of the body, with resulting xe2x80x9csuperinfectionxe2x80x9d due to overgrowth of antibiotic resistant organisms; (2) direct antibiotic toxicity, particularly with prolonged use which can result in damage to kidneys, liver and neural tissue depending upon the type of antibiotic; (3) development of antibiotic resistant microbial populations which defy further treatment by antibiotics.
While even minor wounds and abscesses can be difficult to treat in certain patients and/or under certain conditions, there are well known dermal disorders such as psoriasis and dermal ulcerations, which present particular challenges for successful treatment.
Psoriasis is a noncontagious skin disorder that most commonly appears as inflamed swollen skin lesions covered with silvery white scale. This most common type of psoriasis is called xe2x80x9cplaque psoriasisxe2x80x9d. Psoriasis comes in many different variations and degrees of severity. Different types of psoriasis display characteristics such as pus-like blisters (pustular psoriasis), severe sloughing of the skin (erythrodermic psoriasis), drop-like dots (guttate psoriasis) and smooth inflamed lesions (inverse psoriasis).
The cause of psoriasis is not presently known, though it is generally accepted that it has a genetic component, and it has recently been established that it is an autoimmune skin disorder. Approximately one in three people report a family history of psoriasis, but there is no pattern of inheritance. There are many cases in which children with no apparent family history of the disease will develop psoriasis.
The occurrence of psoriasis in any individual may depend on some precipitating event or xe2x80x9ctrigger factor.xe2x80x9d Examples of xe2x80x9ctrigger factorsxe2x80x9d believed to affect the occurrence of psoriasis include systemic infections such as strep throat, injury to the skin (the Koebner phenomenon), vaccinations, certain medications, and intramuscular injections or oral steroid medications. Once something triggers a person""s genetic tendency to develop psoriasis, it is thought that in turn, the immune system triggers the excessive skin cell reproduction.
Skin cells are programmed to follow two possible programs: normal growth or wound healing. In a normal growth pattern, skin cells are created in the basal cell layer, and then move up through the epidermis to the stratum corneum, the outermost layer of the skin. Dead cells are shed from the skin at about the same rate as new cells are produced, maintaining a balance. This normal process takes about 28 days from cell birth to death. When skin is wounded, a wound healing program is triggered, also known as regenerative maturation. Cells are produced at a much faster rate, theoretically to replace and repair the wound. There is also an increased blood supply and localized inflammation. In many ways, psoriatic skin is similar to skin healing from a wound or reacting to a stimulus such as infection.
Lesional psoriasis is characterized by cell growth in the alternate growth program. Although there is no wound at a psoriatic lesion, skin cells (called xe2x80x9ckeratinocytesxe2x80x9d) behave as if there is. These keratinocytes switch from the normal growth program to regenerative maturation. Cells are created and pushed to the surface in as little as 2-4 days, and the skin cannot shed the cells fast enough. The excessive skin cells build up and form elevated, scaly lesions. The white scale (called xe2x80x9cplaquexe2x80x9d) that usually covers the lesion is composed of dead skin cells, and the redness of the lesion is caused by increased blood supply to the area of rapidly dividing skin cells.
Although there is no known cure for psoriasis, various treatments have been demonstrated to provide temporary relief in some patients. However, the effectiveness of the currently accepted treatments for psoriasis is subject to considerable individual variation. As a result, patients and their physicians may have to experiment and/or combine therapies in order to discover the regimen that is most effective. The currently available treatments for psoriasis are often administered in step-wise fashion. Step 1 treatments include a) topical medications (e.g., topical steroids, topical retinoids), b) systemic steroids, c) coal tar, d) anthralin, e) vitamin D3, and sunshine. Step 2 treatments include a) phototherapy (e.g, ultraviolet radiation), b) phochemotherapy (e.g., a combination of a topically applied radiation-activated agent followed by radiation to activate the agent) and c) combination therapy. Step 3 treatments include a) systemic drug therapies such as methotrexate, oral retinoids and cyclosporine and b) rotational therapy.
Dermal ulcerations are known to occur as a result of pressure, wear, or primary/secondary vascular disorders. Dermal ulcerations are generally classified according to their etiology, as follows:
a. Decubitus/Pressure Ulcers
A decubitus ulcer or pressure sore is a lesion caused by unrelieved pressure resulting in damage of the underlying tissue. Decubitus ulcers usually develop over a bony prominence such as the elbow or hip. The unrelieved pressure, along with numerous contributing factors, leads to the skin breakdown and persistent ulcerations.
b. Venous Ulcers
Venous ulcers may result from trauma or develop after chronic venous insufficiency (CVI). In CVI, venous valves don""t close completely, allowing blood to flow back from the deep venous system through the perforator veins into the superficialvenous system. Over time, the weight of this column of blood causes fluid and protein to exude into surrounding tissues, resulting in swollen, hyperpigmented ankles, tissue breakdown, and ulceration. Venous ulcers may be shallow or extend deep into muscle.
c. Arterial Ulcers
Leg ulcers also can develop in patients with arterial insufficiency caused by arterial vessel compression or obstruction, vessel wall changes, or chronic vasoconstriction. Smokers face an especially high risk of arterial disease because nicotine constricts arteries, encourages deposits of atherosclerotic plaque, and exacerbates inflammatory arterial disease (Buerger""s disease) and vasoconstrictive disease (Raynaud""s disease or phenomenon). Arterial ulcers, caused by trauma to an ischemic limb, can be very painful.
d. Diabetic Ulcers
Arterial insufficiency can be the cause of a nonhealing ulcer in a patient with diabetes. However, most diabetic ulcers result from diabetic neuropathyxe2x80x94because the patient can""t feel pain in his foot, he""s unaware of injuries, pressure from too-tight shoes, or repetitive stress that can lead to skin breakdown.
There remains a need in the art for the formulation and development of new disinfectants and topically applicable preparations for the treatment of dermal disorders, such as wounds, burns, abrasions, infections, ulcerations, psoriasis and acne.
The present invention provides antimicrobial preparations (e.g., solutions, gels, ointments, creams, etc.) for disinfection of articles or surfaces (e.g., contact lenses, counter tops, etc.), antisepsis of skin or other body parts, prevention or minimization of scarring, and/or treatment or prophylaxis of dermal (i.e., skin or mucous membrane) disorders (e.g., wounds, burns, infections, cold sores, ulcerations, psoriasis, scar forming lesions, acne). The antimicrobial preparations of this invention generally comprise from about 0.001% to about 0.10 by weight of a metal chlorite in combination with from 0.001% to 0.05% of a peroxy compound such as hydrogen peroxide. Additionally, the chlorite/peroxide preparations of the present invention may contain additional components such as polymeric lubricants and surfactants, and/or may be formulated in a polymeric drug delivery system or liposomal preparation. The chlorite/peroxide preparations of the present invention have broad antimicrobial activity, including for example activity against gram negative and gram positive bacteria, yeasts and fungi. Moreover, when applied or administered to treat dermal disorders (e.g., wounds, burns, infections, ulcerations, acne and psoriasis), the chlorite/peroxide preparations of the present invention will not only prevent or lessen microbial infection, but will additionally provide oxygen to the affected tissue, aid in healing and deter scar formation.
Further in accordance with the invention, there are provided methods for disinfection of items (e.g., contact lenses) and methods for treatment of dermal disorders (e.g., wounds, burns, infections, ulcerations and psoriasis) by application or administration of a chlorite/peroxide preparation of the present invention.
Further in accordance with the invention, there are provided methods for deterring scar formation by application or administration of a chlorite/peroxide preparation of the present invention.
Further aspects and objects of the present invention will become apparent to those of skill in the art upon reading and understanding of the following detailed description and the examples set forth therein.
The following detailed description and examples are provided for the purpose of describing certain exemplary embodiments of the invention only, and are not intended to limit the scope of the invention in any way.
The present invention provides preparations which contain chlorite (e.g., a metal chlorite) in combination with a small amount of hydrogen peroxide in neutral aqueous (pH 6.8-7.8, preferably pH 7.0-7.4) solution. These preparations exhibit synergistic antimicrobial activity without generating chlorine dioxide during storage, thereby rendering the stability of these solutions acceptable for pharmaceutical use. For example, an aqueous solution containing 400 ppm chlorite plus 100 ppm hydrogen peroxide remains stable beyond 18 months at room temperature, and is effective to reduce candida albicans activity by 1.0 log within a 6 hrs of challenge, even though the individual components of such solution are ineffective when applied separately at the same concentrations, to reduce candida albicans activity. Additionally, the hydrogen peroxide present within the chlorite/peroxide solutions of the present invention readily decomposes into molecular oxygen and water, upon contact with the peroxidase and catalase enzymes present in tissue and/or some body fluids. Such in situ generation of molecular oxygen contributes to cell vitality and enhances wound healing.
The chlorite/H2O2 solutions of the present invention are sufficiently stable to be formulated in combination with polymeric lubricants (non-ionic and/or anionic; e.g., HPMC, methylcellulose, CMC, etc.) and/or in combination with block polymer based surfactants (e.g., (Pluronic(trademark) surfactants. For example, an aqueous chlorite/hydrogen peroxide system can be formulated together with methocel as a lubricant and pluronics as a surfactant for contact lens disinfectant solution (viscosity up to 50 cps at 25 degrees C.) in an ophthalmically acceptable tonicity (e.g., osmolality of at least about 200 mOsmol/kg) and a buffer to maintain the pH of the formulation within an acceptable physiological range. The formulation of the contact lens disinfection solution contains chlorite preferably from about 0.03 to about 0.06 weight/volume percent and hydrogen peroxide preferably from about 0.0002 to about 0.05 weight/volume percent. Again, the presence of hydrogen peroxide provides the beneficial oxygen molecule to the cornea upon contact with catalase in the tear.
The chlorite/peroxide preparations of the present invention may be formulated in various ways, including liquid solutions, gels, ointments, creams, sprays, etc. Set forth herebelow are but a few examples of the types of specific formulations which may be prepared in accordance with this invention.
i. A Stable Chlorite/Peroxide Liquid Solution
The following Formula 1 is a presently preferred formulation of a liquid chlorite/peroxide solution of the present invention:
Sodium Chlorite . . . 0.02%-0.10%
Hydrogen Peroxide . . . 0.005%-0.01%
methylcellulose (Methocel A(trademark)) . . . 0.05%-0.2%
Boric Acid . . . 0.15%
Sodium Chloride . . . 0.75%
surfactant (Pluronic F-68(trademark)) . . . 0.1%
HCl or NaOH . . . Adjust pH 7.4
Purified water . . . Q.S. to volume
The chlorite/peroxide solutions of the present invention, such as the solution of the above-shown preferred formulation, may be used for a variety of medical and non-medical applications including but not necessarily limited to a) disinfection of articles and surfaces such as contact lenses, medical/dental instruments, counter tops, treatment tables, combs and brushes, etc; antisepsis of skin or body parts (e.g., a disinfectant hand wash, antiseptic facial scub, etc.) and b) treatment or prophylaxix of dermal (I.e., skin or mucous membrane) disorders such as wounds, burns, infections, ulcerations, cold sores, psoriasis, acne, and c) deterrence or prevention of scar formation.
As pointed out earlier, the chlorite/hydrogen peroxide system of the present invention is sufficiently stable to be formulated in a polymeric gel form or in a paste form. Furthermore, such polymeric gel or paste formulation can contain polymers which delay or control the release of the chlorite/hydrogen peroxide (e.g., a sustained release delivery system). Such sustained release formulations provide outstanding benefits of increasing therapeutic index by maintaining the effective concentration of chlorite/H202 for a prolonged time on the injured sites, by preventing the injured sites from external microbial contamination by forming a seal over the injured sites, and by providing oxygen molecule to the injured tissues. Unlike the conventional ointment, the polymeric gel provides a dry, clean, and comfortable coating on the injured sites upon application. Such gel formulations may contain polymeric drug delivery vehicles like hydroxypropyl methylcellulose (HPMC), methylcellulose (Methocel(trademark)), hydroxyethylcellulose (HEC), and carboxymethylcellulose (CMC), etc.
ii. A Stable Chlorite/Peroxide Gel
The following Formula 2 is a presently preferred formulation of a chlorite/peroxide gel of the present invention:
Sodium Chlorite . . . 0.02%-0.10%
Hydrogen Peroxide . . . 0.005%-0.01%
Methocel A . . . 2.0%
Boric Acid . . . 0.15%
Sodium Chloride . . . 0.75%
Pluronic F-68 . . . 0.1%
HCl or NaOH . . . Adjust pH 7.4
Purified water . . . Q.S. to volume
Any of the preparations of the present invention may be formulated for sustained release of the active components by forming liposomes of the preparing in accordance with well known liposomal forming techniques and/or by adding to the formulation a pharmaceutically acceptable and effective amount (e.g., typically 1-20 percent by weight) of a sustained release component such as a polymer matrix or one or more of the following:
a cellulose ester;
hydroxymethylpropyl cellulose;
methylhydroxyethyl cellulose;
hydroxypropyl cellulose;
hydroxyethyl cellulose;
carboxymethyl cellulose;
a salt of a cellulose ester;
cellulose acetate;
hydroxypropylmethyl cellulose phthalte;
methacrylic acid-methyl methacrylate copoymer;
methacrylic acid-ethyl acetate copolymer;
polyvinylpyrrolidone;
polyvinyl alcohol;
a phospholipid;
cholesterol;
a phospholipid having a neutral charge;
a phospholipid having a negative charge;
dipalmytoyl phoshatidyl choline;
dipalmytoyl phoshatidyl serine; and,
sodium salts thereof.

Synergistic antimicrobial preparations containing chlorite and hydrogen peroxide


A capacitor structure of a semiconductor memory cell such as a FERAM has an upper electrode less susceptible a damage even by heat-treatment in a hydrogen gas atmosphere. The capacitor structure includes a lower electrode, a capacitor thin film formed of a ferroelectric thin film formed on the lower electrode, and an upper electrode formed on the capacitor thin film. The upper electrode is made of Ru.sub.1-x O.sub.x (0.1<x<0.64).

1. Field of the Invention
The present invention relates to a capacitor structure of a semiconductor memory cell using a ferroelectric thin film and a fabrication process thereof, and particularly to a capacitor structure of a nonvolatile semiconductor memory cell (so-called FERAM) or DRAM using a ferroelectric thin film and a fabrication process thereof.
2. Description of the Related Art
In recent years, with advance of the film formation technique, applied researches have been extensively made on nonvolatile semiconductor memories using ferroelectric thin films. The nonvolatile semiconductor memory allows high speed rewriting by making use of high speed polarization reversal and its residual polarization of a ferroelectric thin film. The nonvolatile semiconductor memories including ferroelectric thin films, which are being studied at present, are classified into a type of detecting the amount of electric charges stored in a ferroelectric capacitor portion and a type of detecting a change in resistance of a semiconductor due to spontaneous polarization of a ferroelectric material. The semiconductor memory cell, to which the present invention is applied, is the former type.
The nonvolatile semiconductor memory cell of the type of detecting a change in the amount of electric charges stored in a ferroelectric capacitor portion, is basically composed of a ferroelectric capacitor portion and a selective transistor. The ferroelectric capacitor portion typically includes a lower electrode, an upper electrode, and a capacitor thin film composed of a ferroelectric thin film which is held therebetween and has a relatively high dielectric constant .epsilon.. Writing and reading of data in and from the nonvolatile semiconductor memory cell of this type are performed using a P-E hysteresis loop of a ferroelectric material shown in FIG. 13. When an external electric field is applied to a ferroelectric thin film and then removed therefrom, the ferroelectric thin film exhibits a spontaneous polarization. When being applied with a positive external electric field, the ferroelectric thin film exhibits a residual polarization+Pr. Besides, when being applied with a negative external electric field, the ferroelectric thin film exhibits a residual polarization-Pr. Here, the case where the ferroelectric thin film exhibits the residual polarization+Pr (see a state "D" of FIG. 13) is taken as "0", and the case where it exhibits the residual polarization-Pr (see a state "A" of FIG. 13) is taken as "1".
To identify the state "1" or "0", for example, a positive external electric field is applied to the ferroelectric thin film. The ferroelectric thin film thus applied with the positive electric field exhibits a polarization shown by character C of FIG. 13. At this time, if the data is "0", the polarization state of the ferroelectric thin film is changed from the state "D" to "C". On the other hand, if the data is "1", the polarization state of the ferroelectric thin film is changed from the state "A" to "C" by way of "B". That is, if the data is "0", the ferroelectric thin film does not exhibit any polarization reversal. On the other hand, if the data is "1", it exhibits the polarization reversal. As a result, there occurs a difference in the amount of electric charges stored in the ferroelectric capacitor portion. Thus, the stored electric charges are detected as a signal current by turning on the selective transistor of the selected memory cell. When the external electric field is made zero after read-out of the data, the polarization state of the ferroelectric thin film becomes the state "D" of FIG. 13 even if the state is "0" or "1". Accordingly, in the case where the data is "1", the data "1" is written by applying a negative external electric field to change the state "D" to "A" by way of "E".
Capacitor structures of a type in which a lower electrode is provided on a buffer layer formed of Ti on a SiO.sub.2 layer; a capacitor thin film is made from Pb(Zr.sub.1-y, Ti.sub.y)O.sub.3 ; and an upper electrode is made from Pt (platinum), are known, for example, from Ramton Corporation, "FRAM Cell", Thomas Boehm, HE6-94-2001; "Polarization Fatigue Characteristics of Sol-Gel Ferroelectric Pb(Zr.sub.0.4 Ti.sub.0.6)O.sub.3 Thin-Film Capacitors", T. Mihama, et al., Jpn. J. Appl. Phys. Vol. 33 (1994), pp 3996-4002; "Fatigue Characteristics of Sol-Gel Derived Pb (Zr, Ti)O.sub.3 Thin Films", K. Amanuma, et al., Jpn. J. Appl. Phys. Vol. 33 (1994), pp 5211-5214; and "Low-temperature Preparation Of Pb(Zr, Ti)O.sub.3 Thin Film", I. Kanno. et al., Jpn. J. Appl. Phys. Vol. 32 (1993), pp 4057-4060. Further, capacitor structures of a type in which a capacitor thin film is made from SrBi.sub.2 Ta.sub.2 O.sub.9 in place of Pb(Zr.sub.1-y, Ti.sub.y)O.sub.3, are known, for example, from WO93/12542, "Preparation and ferroelectric properties of SrBi.sub.2 Ta.sub.2 O.sub.9 thin film", K. Amanuma, et al., Appl. Phys. Lett. 66(2), Jan. 9, 1995; and "A 256 kb Nonvolatile Ferroelectric Memory at 3 V and 10 ns", ISSC 94, PP 268. The use of Ru (ruthenium) added with a trace of oxygen as an electrode material is known from "Application of Ru film added with trace oxygen to BST film capacitor electrode" (Proceedings No. 2 of the 57th Meeting of Jpn. Soc. of Appl. Phys., 8p-H-18).
A process of fabricating a semiconductor memory cell generally includes various heat-treatment steps performed at a hydrogen gas atmosphere at temperatures in a range of 280 to 450.degree. C. In such a heat-treatment, hydrogen gas may permeate an upper electrode. From this viewpoint, one example of a process of fabricating a semiconductor memory cell will be briefly described with reference to FIGS. 14A and 14B and FIG. 15 which typically show the partial cross-section of a semiconductor substrate and the like.
The description will be made of a so-called planar type volatile semiconductor memory cell including a MOS transistor element as a selective transistor and a capacitor structure (ferroelectric capacitor portion). The capacitor structure includes a lower electrode 22, a capacitor thin film 23 composed of a ferroelectric thin film formed on the lower electrode 22, and an upper electrode 24 formed on the capacitor thin film 23. The lower electrode 22 is electrically connected to one source/drain region 15 of the MOS transistor element through a contact plug 26A and an interconnection 29. The upper electrode 24 is connected to a plate line 28. The other source/drain region 15 of the MOS transistor element is connected to a bit line 30.
The MOS transistor is formed on a semiconductor substrate 10 in accordance with a known process, and a multi-layered interlayer insulating film 20 having, for example, a SiN layer, a BPSG layer, and a NSG layer, is formed over the entire surface by CVD. In the figures, the interlayer insulating film 20 having the multi-layered structure is shown as that having a single layer structure for simplification. A buffer layer 21 made from Ti, a lower electrode layer made from Pt, a ferroelectric thin film, and an upper electrode layer made from Pt are sequentially formed on the interlayer insulating film 20, and the upper electrode layer, ferroelectric thin film, lower electrode layer, and buffer layer are patterned, to form a capacitor structure shown in FIG. 14A. The ferroelectric thin film is made from a material expressed by EQU Bi.sub.x Sr.sub.y Ta.sub.2 O.sub.d (2)
where 1.7.ltoreq.X.ltoreq.2.5, 0.6.ltoreq.Y.ltoreq.1.2, and 8.0.ltoreq.d.ltoreq.10.0. In the figure, reference numeral 11 indicates an isolation region, 12 is a gate oxide film, 13 is a gate electrode, and 14 is a gate oxide wall.
A multi-layered insulating film 25, having a SiO.sub.2 layer formed using TEOS by plasma CVD, O.sub.3 -NSG layer, and a SiO.sub.2 layer formed using TEOS by plasma CVD, is formed. In the figures, the insulating layer 25 is shown as that having a single layer structure for simplification. The atmosphere for forming the SiO.sub.2 layer using TEOS by plasma CVD is a hydrogen rich atmosphere, and in this step, the semiconductor substrate is heated at about 400.degree. C. Next, openings 26 are formed in the insulating film 25 and the interlayer insulating layer 20 at positions over the source/drain region 15 of the MOS transistor by RIE (see FIG. 14B). To reduce a trap density at a SiO.sub.2 /Si interface of the MOS transistor, the semiconductor substrate is annealed in a forming gas composed of a mixed gas of N.sub.2 gas/H.sub.2 gas (5 vol %) at a temperature of 400 to 450.degree. C. At this time, hydrogen gas permeates the upper electrode 24 made from Pt through the insulating film 25, and further it permeates the capacitor film 23.
Openings 27 are formed in a portion of the insulating film 25 over the lower electrode 22 extending from the capacitor structure and also in a portion of the insulating film 25 over the upper electrode 24. A metal interconnection layer is formed by sputtering over the entire surface including the interiors of the openings 26 and 27, and is patterned to form the plate line 28, interconnection 29, and bit line 30 (see FIG. 15). Finally, a passivation film made from SiN is formed over the entire surface by plasma CVD. The concentration of hydrogen gas in the atmosphere used for formation of the. passivation film is 15-30 vol %, and in this step, the semiconductor substrate is heated at a temperature of 280 to 350.degree. C.
The upper electrode 24 made from Pt is damaged by the heat-treatments in the hydrogen gas atmosphere used for film formation by various CVD processes and for annealing in the forming gas. It is to be noted that the annealing in the forming gas is sometimes referred to simply to "annealing" hereinafter. The reason why the upper electrode 24 is damaged is that hydrogen gas, which has permeated the upper electrode 24 and further reached the capacitor thin film 23 formed of the ferroelectric thin film, reacts with oxygen atoms constituting the ferroelectric thin film, and thereby Bi atoms of the ferroelectric thin film made from Bi.sub.x St.sub.y Ta.sub.2 O.sub.d expressed in the equation (2) react with hydrogen to produce H.sub.2 O, as a result of which the upper electrode 24 made from Pt is damaged due to the attack of H.sub.2 O.
FIGS. 16A and 16B each show the result of microscopically observing a surface of an upper electrode of a capacitor structure provided on a buffer layer formed of Ti on an interlayer insulating film made from SiO.sub.2, wherein FIG. 16A shows a state of the upper electrode before annealing, and FIG. 16B shows a state of the upper electrode after annealing performed in a forming gas at 430.degree. C. for one hour. In addition, the capacitor structure is composed of a lower electrode layer made from Pt, a ferroelectric thin film made from Bi.sub.x St.sub.y Ta.sub.2 O.sub.d expressed in the equation (2), and the upper electrode made from Pt. As will be apparent from comparison between the states shown in FIGS. 16A and 16B, the upper electrode after annealing in the forming gas is damaged. In addition, an upper electrode made from Ru or RuO.sub.2 is also damaged after annealing in the forming gas.
The occurrence of a damage in the upper electrode leads to short-circuit or reduction in the value of 2Pr of a P-E hysteresis loop of the ferroelectric thin film. In the worst case, the upper electrode is peeled from the capacitor thin film. FIG. 17 shows a difference between the P-E hysteresis loops of a ferroelectric thin film before and after annealing in a forming gas. The values of 2Pr and Ec.sup.+ and Ec.sup.- (critical field voltage) of the P-E hysteresis loops of the ferroelectric thin film before and after annealing are shown in Table 1. As will be apparent from Table 1, the value of 2Pr of the ferroelectric thin film after annealing in the forming gas is largely smaller than that of the ferroelectric thin film before annealing.
TABLE 1 ______________________________________ before annealing after annealing ______________________________________ 2Pr (.mu.C/cm.sup.2) 23.11 15.46 Ec.sup.+ (kV/cm) 43.45 55.46 Ec.sup.- (kV/cm) -47.52 -47.22 ______________________________________

Fabrication process of a capacitor structure of semiconductor memory cell


Implementations include a display assembly for a switch assembly, comprising a display assembly touch overlay plate, wherein at least a portion of the display assembly touch overlay plate is comprised of a transparent or translucent material; a display, wherein the display is disposed underneath the display assembly touch overlay plate and wherein at least a portion of the display is visible through the portion of the display assembly touch overlay plate; a display assembly first housing and a display assembly second housing, wherein the display assembly touch overlay plate is in communication with the display assembly first housing, wherein a force applied to the display assembly touch overlay plate is at least partially transmitted from the display assembly touch overlay plate to the display assembly first housing to a switch assembly through a central portion of the display assembly first housing.

Conventional capacitive sense touchscreen technologies, such as those used in smartphones and tablet devices, require significant visual engagement by a driver, which is a distraction for the driver and compromises safety. Conventional mechanical switches and knobs are less distracting because they can be safely used without requiring the driver to remove his eyes from the road, but they tend to have limited flexibility, with each switch controlling a single function or feature.
Thus, there is a need in the art for a switch assembly that provides sufficient feedback to the driver upon receiving driver input to avoid distracting the driver and that provides the ability to control multiple functions and/or vehicle systems with a minimal footprint.

Display-based switch assembly and methods of use


The present invention in various implementations provides for a method and system for removing suspect duplicate data in a database having a plurality of datasets for a suspect processing transaction, using a plurality of matching engines, comparing results of matching engines in a logically predetermined comparative assessment, and thereafter providing an ordered priority of results of matching engines to identify suspect candidates.

Customer records and varied information that are often a part of complex data systems and business applications present a variety of challenges in management, identification, analysis and segregation, for example. It is generally believed, based on estimates in certain industries, that the amount of unstructured data that may reside in planned and developing databases could easily exceed eighty percent. With such an amount of unstructured data, additional complexities arise, especially when the data is present on different platforms, is of varying freshness, and may be inconsistent across the platforms.
Determining which records are duplicates of one another, for instance, where within a complex data system there may exist multiple databases, each having records comprising particular data within, can be a particularly difficult issue. Quality issues also arise in which data stewardship matters become a central concern. Further, in matters concerning customer relationship management (CRM) which often necessitate data integrity to realize optimal returns on data structure investments, removing "bad customer data" and especially duplicate customer data is of key concern.
The IBM Websphere® Customer Center (WCC) is a real-time, service-oriented customer application that provides users with a single view of the customer and also with business processes which provide for maintaining customer data shared between a front and back office arrangement. The WCC effectively acts as an intelligent customer data hub to manage customer data through its Customer Master Data Management (CMDH) hub. Via the CMDH, the WCC manages business rules, event detection, data validation and duplicate suspect processing (DSP). While other vendors have attempted to merely singly match search results to transactional records as a solution to searching in response to the issues raised previously, the WCC via its DSP, enables a client to persist and process duplicate suspects of any customer (i.e., customer data) in the system.
In operation, the DSP searches for potential suspect candidates for a given customer (or party as used herein) and then provides the suspect candidate list to a matching engine which then scores values for each of the candidates residing on the list of suspect candidates. The DSP creates a suspect table (i.e., SuspectTable) as part of the process. The values determined by the DSP in this process are then assessed to determine similarity or dissimilarity as between candidate suspects.
A challenge in the process of assessment of candidate suspects, is the final decision to remove customer data that only appears to be "similar" to that of other data in the system. In particular, the deletion of one set of customer data based on the similar presence of a second but different set of other customer data also present, in relation to a determinative evaluation by a single matching engine and its respective scoring scheme, without a significant confidence of accuracy, is often disconcerting to business management. Typically then, for business management to gain additional confidence in the initial determination of results to make a final decision, further analysis is often conducted and additional searching, comparison, scoring and assessments are performed over time in multiples "passes" on data which is then both different in content and time-value to the original data analyzed.
Unfortunately, as a result, business management may often have multiple results and suspects created for data sets which are neither static nor original in content when compared to the initial set of data, thereby creating further hesitation and confusion in making a final decision. Operatively, data users typically direct findings determined from the traditional process above for further integration steps and processes, thereby creating multiple reviews and assessment passes. Certain of these additional integration activities may involve further matching engine investigation or analysis tool, undertaking data transformation steps, and using Extract, Transform and Load (ETL) tools, for instance.
It is therefore desirable to have an improved method for determining and identifying, in one pass and with heightened confidence, suspect candidates from customer data in relation to results of a plurality of predetermined matching engines via comparative assessments at a predefined time. The present invention addresses such a need.

Method and system for tracking, evaluating and ranking results of multiple matching engines

International Business Machines Corporation


A virtual computer system including multiple virtual machines (VMs) is implemented in a physical computer system that uses address space identifiers (ASIDs). Each VM includes a virtual translation look-aside buffer (TLB), in which guest software, executing on the VM, may insert address translations, with each translation including an ASID. For each ASID used by guest software, a virtual machine monitor (VMM), or other software unit, assigns a unique shadow ASID for use in corresponding address translations in a hardware TLB. If a unique shadow ASID is not available for a newly used guest ASID, the VMM reassigns a shadow ASID from a prior guest ASID to the new guest ASID, purging any entries in the hardware TLB corresponding to the prior guest ASID. Assigning unique shadow ASIDs limits the need for TLB purges upon switching between the multiple VMs, reducing the number of TLB miss faults, and consequently improving overall processing efficiency.

1. Field of the Invention
This invention relates to the field of computer virtualization, that is, to systems and methods for implementing computers as software running on an underlying host hardware platform.
2. Description of the Related Art
The preferred embodiment of the invention is described relative to a virtual memory system for a virtual computer system. Consequently, this description begins with an introduction to virtual computing and virtual memory systems.
Virtualization has brought many advantages to the world of computers. As is well known in the art, a virtual machine (VM) is a software abstraction—a "virtualization"—of an actual physical computer system that runs as a "guest" on an underlying "host" hardware platform. As long as a suitable interface is provided between the VM and the host platform, one advantage is that the operating system (OS) in the guest need not be the same as the OS at the system level in the host. For example, applications that presuppose a Microsoft Windows OS can be run in the VM even though the OS used to handle actual I/O, memory management, etc., on the host might be Linux.
It usually requires less than 10% of the processing capacity of a CPU to run a typical application, although usage may peak briefly for certain operations. Virtualization can more efficiently use processing capacity by allowing more than one VM to run on a single host, effectively multiplying the number of "computers" per "box." Depending on the implementation, the reduction in performance is negligible, or at least not enough to justify separate, dedicated hardware "boxes" for each user.
Still another advantage is that different VMs can be isolated from and completely transparent to one another. Indeed, the user of a single VM will normally be unaware that he is not using a "real" computer, that is, a system with hardware dedicated exclusively to his use. The existence of the underlying host will also be transparent to the VM software itself. The products of VMware, Inc., of Palo Alto, Calif. provide all of these advantages in that they allow multiple, isolated VMs, which may (but need not) have OSs different from each other's, to run on a common hardware platform.

Virtualization system for computers that use address space indentifiers


A fishing lure is provided which is adapted to simulate the behavior of a minnow at rest. Specifically, the new and improved fishing lure described herein is equipped with a pedestal on its bottom, whereby the pedestal is adapted to make contact with a bottom surface at a single contact point. The single contact point is aligned with the lure's center of balance, such that when the lure rests on the bottom surface it has a tendency to remain balanced on the single contact point. This allows the lure to be wobbled by the water turbulence, thereby imitating the behavior of a minnow at rest.

It is well known that it is desirable to use artificial baits when fishing. It is also well known that such artificial baits are more efficient the more they resemble the actual live bait they are meant to imitate, whether in appearance or in behavior. Accordingly, the prior art has several examples of fishing lures designed to imitate the appearance and behavior of live bait. As the minnow is a very commonly used bait, many prior art lures attempt to reproduce the appearance and behavior of the minnow.
One such prior art lure is described in U.S. Pat. No. 5,396,728 to Weber. Weber teaches a fishing lure shaped to resemble a minnow and to produce a wiggling motion when pulled through the water. The lure according to Weber is weighted in the head portion, such that as it settles, the lure orients itself with the head lower than the remainder of the body.
The use of weights in lures is also well known and allows for different lures to behave differently based on the distribution of the weights. An example of such a lure is described in U.S. Pat. No. 5,822,912 to Kato et al., and is made by providing two hollow guide sections within the body of the lure, in which spherical weights are allowed to move. This arrangement is meant to improve the distances achieved when casting, as well as placing the lure's center of gravity near the back end while in the water, thereby stabilizing the lure's movements.
However, none of the prior art fishing lures effectively imitate the behavior of a bait fish at rest. Weber, discussed above, does teach to place weights in the head portion such that, when at rest, the head is lower than the remainder of the body. Hence, Weber teaches how to achieve the proper orientation of a fishing lure at rest, but is silent on how to achieve the wobbling motion of the lure while it is not being pulled through water.
Accordingly, there is a need for a fishing lure which not only orients itself properly while at rest, but which also reproduces the multidirectional motion of a bait fish while at rest. Obviously, the term "at rest" as used herein means that the fishing lure is not being pulled through the water via the fishing line, and does not mean a completely motionless lure.


A mechanism for synchronizing backend peripheral devices with a virtual machine (VM) running state is disclosed. A method of the invention includes modifying a running state of a (VM managed by a hypervisor of a host machine, and updating a VM state indication associated with the VM to reflect the change in running state of the VM, wherein a peripheral device associated with the VM accesses the VM state indication to determine wh her to continue processing a VM state changing instruction.

In computer science, a virtual machine (VM) is a portion of software that, when executed on appropriate hardware, creates an environment allowing the virtualization of an actual physical computer system. Each VM may function as a self-contained platform, running its own operating system (OS) and software applications (processes). Typically, a virtual machine monitor (VMM) manages allocation and virtualization of computer resources and performs context switching, as may be necessary, to cycle between various VMs.
A host machine (e.g., computer or server) is typically enabled to simultaneously run multiple VMs, where each VM may be used by a local or remote client. The host machine allocates a certain amount of the host's resources to each of the VMs. Each VM is then able to use the allocated resources to execute applications, including operating systems known as guest operating systems. The VMM virtualizes the underlying hardware of the host machine or emulates hardware devices, making the use of the VM transparent to the guest operating system or the remote client that uses the VM.
Often times, a VM will utilize peripheral devices. These peripheral devices may be software that is implemented by the hypervisor for the VM, or hardware devices outside of the hypervisor that are assigned to the VM. For example, peripheral devices may include, but are not limited to, a mouse, graphics card, serial device, or network device.
A current problem with utilizing peripheral devices with VMs is that the hypervisor may stop and/or start a VM at any moment. This stopping and starting is not concurrent with the peripheral device stopping and starting. In other words, when the hypervisor stops a VM, the peripheral devices of that VM are not affected by this change in status. For instance, a peripheral device implemented as software is run on a separate thread than the VM and does not have much information about the VM.
A hardware or software peripheral device may still receive events from a VM or end user and will typically acts on these events regardless of whether the VM is stopped or not. Consequently, the peripheral device may change the VM state (e.g., VM memory) after the VM has stopped. This scenario can cause problems for a VM and the hypervisor, such as complicating debugging because the debugger will not be aware of the changed state of the VM and assumes that VM memory does not change once stopped.

Synchronizing backend peripheral devices with a virtual machine running state


A process for modifying at least one dendron that is intended to form part of a dendrimer is disclosed. One reacts at least one reactable unsaturated group in a chemoselective manner to form a less unsaturated group. Also disclosed is a process for modifying dendrimers in a similar manner.

Dendrimers are branched macromolecules with a core and attached dendrons, also known as dendrites. Dendrons are branched structures comprising branching units and optionally linking units. The generation of a dendron is defined by the number of sets of branching groups; see FIG. 1. Dendrons with the same structure (architecture) but a higher generation, or order, are composed of the same structural units (branching and linking units) but have an additional level of branching. There can be surface groups on the periphery or distal units of the dendrons.
Dendrimers of different generations can have different types of branching points and linking units. Dendrimers are generally synthesised by convergent or divergent routes. Convergent routes require a functional group at the dendron foci which can either be reacted directly to give a higher generation dendron or dendrimer or activated before the reaction to form a higher generation dendron or dendrimer. For divergent routes the distal functional groups are used, either after activation or directly, to form the next higher generation dendrimer. Once the dendrimer is formed it has been demonstrated that the surface groups can be modified, e.g. t-butylcarbonates can be removed to leave hydroxyl moieties. The linking, branching, and core units of a dendrimer can either be made up of saturated or unsaturated units. The presence of unsaturated units within a dendron or dendrimer gives rise to the possibility of modifying the structure to form a final dendrimer that has beneficial properties and which could not be formed easily by another method. In particular this invention pertains to a chemical conversion of one or more unsaturated units within a dendron or dendrimer to give bonds which are more saturated between the atoms within the unit. The process is different from other reported reactions of unsaturated units. For example it has previously been shown that when di-substituted vinylene units are present within a dendrimer they can be isomerised (see J. N. G. Pillow et al, Macromolecules, 1999, 32, 5985). Although this is a chemical transformation it does not change the level of saturation and therefore falls outside the scope of this invention. In addition, it has been reported that phenylene based dendrimers have been oxidised to form graphite like structures (FIG. 8A illustrates one component of a dendrimer) (M. D. Watson et al, Chem. Rev., 2001, 101, 1267). Although this is a reaction within the dendron and/or dendrimer structure it does not constitute a reduction in the level of saturation of the sp2 hybridised carbons of the benzene rings. In this case the carbon-proton bond is merely converted to a carbon-carbon bond. Similarly di-dendroned substituted 4,4′-d iphenylacetylene dendrons have been cyclised to form larger benzene centered dendrimers (M. D. Watson et al, Chem. Rev., 2001, 101, 1267). The starting material in FIG. 8B is a dendron where the acetylene unit is the focus with two dendrons attached. The foci of three of these dendrons react to form the central benzene unit of the dendrimer and the other components of the dendrons are unchanged. Recently dendrimers that have unsaturated units have been shown to be useful as the light emitting-layer in organic light-emitting diodes.
Organic light-emitting diodes (OLEDs), also known as organic electroluminescent (EL) devices, are an emerging display technology. In essence an OLED comprises a thin organic layer or stack of organic layers sandwiched between two electrodes, such that when a voltage is applied visible or other light is emitted. At least one of the electrodes must be transparent to light. For display applications the light must of course be visible to the eye, and therefore at least one of the electrodes must be transparent to visible light.
There are two principal techniques that can be used to deposit the organic layers in an OLED: thermal evaporation and solution processing. Solution processing has the potential to be the lower cost technique due to its potentially greater throughput and ability to handle large substrate sizes. Significant work has been undertaken to develop appropriate materials, particularly polymers.dendrimers that are photoluminescent in the solid state have been shown to have great promise as solution processible light-emitting materials in OLEDs (S.-C. Lo, et al Adv. Mater., 2002, 13, 975; J. P. J., Markham, et al Appl. Phys. Lett, 2002, 80, 2645).
Light-emitting dendrimers typically have a luminescent core and in many cases an inherently at least partially conjugated dendrons. As used herein, an inherently at least partially conjugated dendritic structure is one in which there is conjugation between the groups making up the dendritic structure, but the pi-system is not necessarily fully delocalised. The delocalisation of the pi-system is dependent on the regiochemistry of the attachment of the different groups. Such dendrons can also be conjugated dendrons. Further examples of light-emitting dendrimers include those found in P. W. Wang, et al Adv. Mater., 1996, 8, 237; M. Halim, et al Adv. Mater., 1999, 11, 371; A. W. Freeman, et all Am. Chem. Soc., 2000, 122, 12385; A. Adronov, et al Chem. Comm., 2000, 1701.; C. C. Kwok, et al Macromolecules, 2001, 34, 6821. Light-emitting dendrimers have the advantage over light-emitting polymers that the light-emitting properties and the processing properties can be independently optimised as the nature of the core, dendrons and surface groups can be independently altered. For example with dendrimers that contain light-emitting cores the emission colour of the dendrimer can be changed by simply changing the core. Although dendrimers with a light-emitting core are preferred, when the core is not luminescent the chromophores in the dendron can be light-emitting.
Other physical properties, such as viscosity, may also make dendrimers more easily tailored to the available manufacturing processes than polymers. Organometallic dendrimers have previously been used in OLED applications as a single component in a film (i.e. a neat film) or in a blend with a molecular material or in a blend of more than one dendrimer of different type (i.e. different cores), e.g. J. M. Lupton et al. Adv. Funct. Mater., 2001, 11, 287 and J. P. J., Markham, et al Appl. Phys. Lett., 2002, 80, 2645.
Intermolecular interactions play an important role in the opto-electronic properties of organic light-emitting and transport materials. Close contact and good order can lead to high charge mobilities but can also give rise to reduced emission due to the formation of excited-state dimers. In previous work we have shown that intermolecular interactions can be controlled by the generation of the dendrons attached to a dendrimer (J. M. Lupton, et al Phys. Rev. B, 2001, 63, 5206; J. P. J., Markham, et al Appl. Phys. Lett., 2002, 80, 2645). However the nature of the intermolecular interactions is affected by the type of dendron that is attached to the core. Generally, when the dendrimers are prepared via a convergent or divergent route the main structure of the final dendrimer is defined by the dendron branching groups and linking units used in the synthesis. This gives a limitation over the control of the dendrimer architecture and properties. Within a dendron or dendrimer there is potential for the surface groups, branching groups and linking units, where present, and foci in the case of dendrons, and core in the case of dendrimers, to be modified. It is known that surface groups of dendrimers and dendrons and the foci of dendrons can be modified. However, as many dendrimers contain saturated linking units and branching groups the modification of these units can be difficult. In contrast dendrons or dendrimers containing unsaturated units within the linking units and branching groups of the dendrons and the core offer an unexpected advantage for modifying the dendron and dendrimer structures. This is different from the reactions used in the divergent or convergent route where a surface or focal group that contains unsaturation is converted into a surface group for further generation building. For example, in a divergent route the surface groups of the lower generation are typically activated to make them reactive to the species added in the next stage. This is illustrated in the synthesis of poly(iminopropane-1,3-diyl) (PPI) dendrimers which are formed by the Michael addition of acrylonitrile to 1,4-diaminobutane. After the addition the resultant terminal nitrite groups are reduced to form the primary amine terminated first generation dendrimer, which can then be reacted with more equivalents of acrylonitrile. The reduction is repeated to form the next generation dendrimer (Topics in Current Chemistry, Dendrimers III, p 86, Springer-Verlag, Berlin Heidelberg, 2001). This approach is different from that of the current invention, in which the entire dendron or dendrimer structure is built such that it contains unsaturated units within the branching groups and/or linking units and/or core, and then the dendron or dendrimer is modified by reaction of some or all of said units. In particular unsaturated groups such as acetylenyl and vinyl groups within the dendron of a dendrimer are reacted. With this method we have been able to produce dendrimers with aryl branching groups linked by ethylene units using the powerful Pd catalysed coupling of aryl halides and alkenes, followed by simple hydrogenation. In contrast, previous routes to saturated links between aromatic branching groups have involved a complex series of reactions where the hydrocarbon linking unit is introduced via a number of steps prior to the Pd coupling to form the dendrimer (Z. Bo, A. D. Schlüter J. Org. Chem. 2002, 67, 5327). A further advantage of this invention is that it gives additional flexibility in the choice of end product. After the coupling to form the unsaturated unit a range of reactions, such as halogenation and hydrogenation of alkenes and acetylenes can be used to give a variety of alternative products from the same intermediate material. We have discovered that by using dendrons that contain acetylene and vinylene links between branching points in dendrons and further reacting them it gives a way of advantageously modifying the dendrons and hence the dendrimers.

The University Court of the University of St. Andrews


An object of the invention is to provide a Mach-Zehnder type optical modulator that can reduce wavelength chirp occurring in a modulated light, and also can reduce an optical loss with a small sized configuration. To this end, according to the present Mach-Zehnder type optical modulator, in a configuration where optical waveguides and a coplanar electrode are formed on a substrate having an electro-optical effect, a polarization inversed region is formed in a part of an interaction portion of the substrate, and a signal electrode is arranged above one of parallel waveguides in a polarization inversed region and is arranged above the other parallel waveguide in a non-inversed region. Furthermore, a surface area of the substrate positioned on both sides of each of the parallel waveguides is lowered to provide a ridge structure section, and a buffer layer is formed on a ridge side face thereof.

1. Field of the Invention
The present invention relates to an optical waveguide device to be used for optical communications, and in particular, relates to a Mach-Zehnder type optical modulator.
2. Description of the Related Art
For example, an optical waveguide device in which an electro-optic crystal such as lithium niobate (LiNbO3), lithium tantalite (LiTaO2) or the like is used, is manufactured by forming a metal film on a part of a crystal substrate to perform thermal diffusion or proton exchange in benzoic acid after patterning, thereby forming an optical waveguide, and afterwards providing electrodes in the vicinity of the optical waveguide. A Mach-Zehnder type optical modulator with a branching interference type optical waveguide structure is known as one of optical waveguide devices using such electro-optical crystal.
FIG. 6 is a plan view showing the structure of a typical Mach-Zehnder type optical modulator. In this Mach-Zehnder type optical modulator, an optical waveguide 110 is formed such that a titanium (Ti) film is formed on a substrate 101, patterned in a Mach-Zehnder shape, and afterwards heated for seven to ten hours at 1050° C. to be subjected to the thermal diffusion. This optical waveguide 110 comprises an incoming waveguide 111, a branching section 112, parallel waveguides 113A and 113B, a multipplexing section 114, and an outgoing waveguide 115. A coplanar electrode 120 comprising a signal electrode 121 and a ground electrode 122 is provided along the parallel waveguides 113A and 113B. In the case where a Z-cut substrate 101 is used, in order to utilize a change in refractive index due to an electric field in a Z direction, the signal electrode 121 is positioned just above the optical waveguide 113A. Further, the signal electrode 121 and the ground electrode 122 are formed on the substrate 101 via a buffer layer (not shown in the figure) formed of silicon oxide (SiO2) or the like, in order to prevent the absorption of lights which are propagated through the parallel waveguides 113A and 113B.
In the case where such a conventional Mach-Zehnder type optical modulator is driven at a high speed, one end of the signal electrode 121 is grounded via a resistor (not shown in the figure) to be made a traveling-wave electrode, and a high frequency electrical signal M, such as a microwave or the like, is applied from the other end of the signal electrode 121. At this time, since the refractive indexes of the parallel waveguides 113A and 113B are both changed due to an electric field generated between the signal electrode 121 and the ground electrode 122, phase differences of the lights being propagated through the parallel waveguides 113A and 113B are changed, and an intensity modulated optical signal is output from the outgoing waveguide 115.
For the above described conventional Mach-Zehnder type optical modulator, it has been known that by changing the cross-section of the signal electrode 121 to control the effective refractive index of microwave, and matching propagation speeds of the light and the microwave, broadband optical response characteristics can be obtained. Furthermore, as shown in FIG. 7 and FIG. 8 for example, by providing a curved section 110A in a part of the optical waveguide 110 to form an approximately U-shaped or S-shaped optical waveguide 110, it is possible to achieve the miniaturization (especially, miniaturization in the longitudinal direction) of the substrate 101.
In the case where the curved section is formed in the part of the optical waveguide, an optical loss (radiation loss) occurring in the curved section is a problem. Conventionally, a technique has been proposed for reducing the loss in the curved section of optical waveguide, in which a reflecting section is disposed on an outer periphery of the curved section, to again couple the light emitted from the curved section in the optical waveguide (refer to Japanese Unexamined Patent Publication No. 11-167032).
However, the above described conventional Mach-Zehnder type optical modulator has the following problems.
(1) Problem Regarding Wavelength Chirp
In the conventional Mach-Zehnder type optical modulator, since the intensity of the electric field applied to each of the parallel waveguides 113A and 113B differs from each other depending on a difference in arranged positions of the parallel waveguides 113A and 113B relative to the signal electrode 121, a change amount (Δns) of the refractive index of the parallel waveguide 113A, which is closer to the signal electrode 121, is greater than a change amount (Δng) of the refractive index of the parallel waveguide 113B, which is further from the signal electrode 121. Therefore, absolute values of the phase changes of the lights being propagated through the parallel waveguides 113A and 113B differ from each other. Thus, there is a problem in that when the signal is switched from "0" to "1" or from "1" to "0", a wavelength change (wavelength chirp) in a modulated light occurs, which degrades the signal waveform after transmission.
In order to reduce the wavelength chirp, for example there is a method in which an X-cut crystal substrate is used, or a method in which two signal electrodes are arranged on the respective parallel waveguides to push-pull drive the Mach-Zehnder type optical modulator.
In the case where the X-cut crystal substrate is used, by applying electric fields to the two parallel waveguides in a +Z direction and a −Z direction utilizing an electric field parallel to the substrate, it becomes possible to perform modulation whereby the wavelength chirp does not occur. However, since it is not possible to arrange the parallel waveguides directly below the signal electrode, there is a large distance between the signal electrode and the waveguides. Therefore, there is a disadvantage in that a high drive voltage must be applied.
Furthermore, in the case where the push-pull drive is performed using two signal electrodes, two input connectors for high frequency electrical signals are required, and also electrical signals with their data inverted must be applied to the two signal electrodes, while their phases being controlling. Therefore, there is a disadvantage in that the circuit structure of drive system becomes complicated.
(2) Problem Regarding Miniaturization
In order to miniaturize the Mach-Zehnder type optical modulator, even if the curved section is formed in the part of the optical waveguide, and furthermore, the optical loss occurring in the curved section is suppressed using the above described technique of Japanese Unexamined Patent Publication No. 11-167032, it is difficult to reduce the curvature of the curved section of the optical waveguide. Therefore, there is a problem in that miniaturization of the optical modulator is limited. For example, in the case where the curvature of the curved section of the optical waveguide is made small as approximately a few mm, the lights are not again coupled sufficiently by the reflecting section, and hence the optical loss is increased significantly. In the case where the curvature of the curved section of the optical waveguide cannot be made small in this manner, it is difficult to make the whole of the optical waveguide small, which leads to a limitation to the miniaturization of optical modulator.
Here, for the above described problem (1), the inventor of the present application has proposed a technique for reducing the wavelength chirp occurring in the modulated light, by forming a polarization inversed region in a part of a portion where the lights being propagated through the parallel waveguides and the microwave being propagated through the signal electrode interact, arranging the signal electrode above one of the parallel waveguides in the polarization inversed region, and arranging the signal electrode above the other parallel waveguide in a non-inversed region, and thereby offsetting the difference between the amounts of phase change of the lights being propagated through the two parallel waveguides (refer to a prior application, International Application No. PCT/JP02/12824). However, this prior invention has not show a specific configuration in which the curved section is formed in the part of the optical waveguide as described above, and a problem remains regarding the miniaturization of optical modulator.
Further, for the above problem (2), a technique has been proposed for miniaturizing an optical device, by lowering areas of the substrate on both sides of the curved optical waveguide along the curved section shape to form a ridge structure section, and forming a buffer layer on at least a side face of the ridge structure section that faces the curved section by the use of a material whose refractive index is lower than the refractive index of the substrate, so that it is possible to reduce the radiation loss or the like even if the curvature of the curved section is small (refer to a prior application, Japanese Patent Application 2003-079116,). However, this prior invention leaves a problem regarding the above described wavelength chirp. Moreover, by forming the ridge structure section, the substrate under the signal electrode has a side face inclined diagonally. Therefore, there is a problem in that the design for matching the speeds of the lights being propagated through the optical waveguides and the speed of the microwave being propagated through the signal electrode becomes complicated.