Methods and compositions for synthesizing cDNA in vivo are disclosed, wherein a synthetic polynucleotide molecule which anneals in vivo to an RNA template molecule is utilized as a primer for reverse transcriptase in vivo.

The present invention relates to methods and compositions for DNA synthesis, and, more particularly, for the synthesis of complementary DNA in vivo.
The present invention is a tool for molecular biology. An introduction to the nomenclature of molecular biology, the structure of DNA, RNA and proteins and the interrelationships between these molecules, is provided in Chapter 4, Synthesis of Proteins and Nucleic Acids of Darnell et al., Molecular Cell Biology, Scientific American Books (1989). A more detailed treatment of these issues is set forth in the full text of Darnell et al., (1989) and in Lewin, Genes IV, Oxford University Press (1990).
Hereditary information is encoded in the genes of an organism. Genes are made of polymers of nucleic acids, usually deoxyribonucleic acid (DNA). DNA is composed of a series of four nucleotide bases; the hereditary information carried by a gene is encoded by the specific sequence of nucleotide bases in the DNA molecule. The genetic information within structural genes encodes proteins; the sequence and structure (and therefore function) of a particular protein is determined by the order of the nucleotide bases within the gene that encodes that protein. Proteins determine an organism""s identity; from cellular structures to the organism""s response to its environment. Thus, the genes that encode these proteins determine an organism""s identity.
The information encoded within a structural gene is xe2x80x9cexpressedxe2x80x9d by a cell through the processes of transcription and translation. Transcription results in the production of an intermediate carrier of the genetic code, termed messenger RNA (mRNA). Messenger RNA is effectively a copy of the gene; it is a polymer of ribonucleic acid (hence xe2x80x9cRNAxe2x80x9d) rather than of deoxyribonucleic acid.
In eukaryotic organisms (which are generally more complex organisms than bacteria), genes are made up of coding regions (termed xe2x80x9cexonsxe2x80x9d) and non-coding regions (termed xe2x80x9cintronsxe2x80x9d). Exons directly encode the protein sequence of the gene. Introns may be very large and there may be a large number of intron sequences within a particular gene. The role of the non-coding intron sequences is unclear. However, there is evidence that these intervening sequences serve two critical purposes: first they divide the exon coding regions into smaller protein coding units and so minimize the chances of errors during transcription and translation; second, they relegate discrete portions or cassettes of protein sequence to exon units which can be more easily shuffled during the course of evolution and therefore facilitate the development of new proteins which may ultimately enhance the survival of the species.
The transcription process involves the formation of an mRNA copy of the entire gene. That is, the mRNA produced by the transcription process contains a copy of both the non-coding intron sequences and the protein-encoding exon sequences. Thus the mRNA first produced by transcription is the same length as the gene from which it was copied. Subsequently, this immature mRNA undergoes a processing stage during which the non-coding intron sequences are spliced out. The resulting processed mRNA molecules thus contain only the information required to encode the protein (i.e. they contain copies of only the joined exon sequences). These processed mRNA molecules are thus considerably shorter in length than the xe2x80x9cgenomic sequencexe2x80x9d (the gene exons and introns as they exist in the chromosome) from which the mRNA was initially copied. The processed mRNA is also modified at this stage to include a polyriboadenylic acid, poly(A), tail at one end of the molecule (the 3xe2x80x2 end) and a xe2x80x9ccapxe2x80x9d structure at the other end of the molecule (the 5xe2x80x2 end) (standard nomenclature assigns one end of DNA and RNA molecules as the 5xe2x80x2 end and the other as the 3xe2x80x2 end, according to the terminal chemical groupings of the molecule). An mRNA molecule that has been processed to remove introns and has a 5xe2x80x2 cap and a 3xe2x80x2 poly(A) tail is termed a xe2x80x9cmaturexe2x80x9d mRNA molecule. A greatly simplified diagram of the transcription process, illustrating removal of the non-coding intron sequences is shown in FIG. 1.
The step of converting the information carried by the mature messenger RNA into a protein is termed translation. Translation is the final step of the means by which the information encoded by the nucleotide sequence within a structural gene is converted into a specific protein composed of a sequence of amino acids.
The cloning of genes became possible in the 1970""s. In early experiments, small genes were cloned from bacteria. Since that time advances in molecular biology and genetic engineering have developed at an extraordinary rate, such that the sequence of the entire human genome is now being determined. Despite rapid advances in the technology of this field, a number of limitations are still apparent. One of these is the difficulty of cloning very large structural genes.
The size of a gene is measured in the number of nucleotide bases that it contains, usually expressed in terms of thousands of bases (kilobases or Kb). Although there are several examples of larger genes, the total coding sequence of most structural genes (the exons) typically totals 1-10 Kb. However, the presence of multiple large intron sequences between the exon segments means that at the genomic level these genes are spread out over a much larger area, frequently spanning tens or even hundreds of kilobases. Present gene cloning vectors such as YACs (Yeast Artificial Chromosomes) allow the cloning of very large (100-300 Kb) genomic segments; however, these genomic inserts include the noncoding intron sequences, which precludes the expression of protein in an artificial system. A partial genetic sequence, or sequence containing introns, results in the expression of a nonfunctional, truncated protein, or, when the sequence for the 5xe2x80x2 translation start site is missing, results in expression of a unrelated garbled protein sequence. Even if a partial gene may be identified through a screening process, it is then necessary to recover the remaining portions of the gene. This can be an extremely complicated process. If the gene contains many intron sequences, and is thus large, years of effort can be expended in attempting to recover the remaining pieces of the gene. Additional effort may then be required to determine the relative order of the gene fragments and to distinguish exon from intron sequences. The ability to clone a gene as a contiguous protein coding cassette is particularly important where identification of the gene is achieved by means of a detection technique which relies on production of the protein in a recombinant bacterial or viral system and xe2x80x9cscreeningxe2x80x9d for the function or structure of the desired proteinxe2x80x94a common technique of detecting cloned genes.
To clone structural genes, molecular biologists have taken advantage of the cellular mRNA processing function described above whereby intron sequences are spliced out of the immature mRNA to produce a mature mRNA that is considerably smaller that the original gene. By converting the mature mRNA molecule back into a DNA molecule (hence the term, xe2x80x9creverse transcriptionxe2x80x9d), one can obtain the original coding sequence (the exons) without the extraneous intron sequences. Such a DNA molecule is termed a complementary DNA because it is complementary to the mRNA molecule from which it was derived. Complementary DNA (cDNA) synthesis is the preferred technique for gene cloning because it results in the recovery of the desired gene in a relatively small, contiguous protein coding cassette amenable to recombinant protein production.
An additional and important use of cDNA technology is to identify those genes that are being expressed by a cell at a particular time. Gene expression requires substantial energy expenditure on the part of the cell, and mRNA molecules are designed to be short-lived xe2x80x9cprotein requestsxe2x80x9d; therefore, with a few exceptions (notably in the egg during development), only those genes that code for proteins which are immediately needed are transcribed into mRNA. By making cDNA copies of the existing mRNA population in a cell, and cloning the cDNAs produced, researchers are able to produce a cDNA library from the genes which were being expressed at that time. Researchers can thus determine specifically which genes are expressed in a given tissue type, at a given stage of development, or in response to an applied stimulus.
Complementary DNA clones are extremely important in both research and industry. Research requires expression of the cloned gene in order to determine the protein""s function and structure. In addition, large amounts of protein are required for the production of polyclonal or monoclonal antibodies which are indispensable for following small amounts of the protein through research protocols, and in determining the location of the protein in the cell. Bacteria are commonly used as hosts in which a cloned gene is expressed. The genes of prokaryotes, including bacteria, do not contain introns, and so these cells do not have the splicing machinery necessary to process immature mRNA into a mature mRNA that can be translated into a functional protein. Genomic clones of eukaryotic genes (i.e., containing introns and exons) can not be expressed in a bacterial host, whereas a cDNA copy of the same gene can be expressedxe2x80x94either in procaryotes or eukaryotes. Thus, cDNA clones are routinely used for large scale protein production. This artificial protein expression is termed xe2x80x9crecombinant proteinxe2x80x9d production and is an increasingly common way of producing many of the pharmaceuticals which for years were accessible in small amounts by tedious extraction from other animal""s tissues.
Techniques presently used for cDNA synthesis are reviewed in Berger and Kimmel, Guide to Molecular Cloning Techniques in Methods in Enzymology Volume 152, Academic Press Inc. (1987), in Sambrook et al., Molecular Cloning, Cold Spring Harbor Laboratory Press (1989), and in Okayama, H., et al., Meth. Enzymol. 159:3-27 (1987). A review of mRNA isolation techniques is presented in Chapters 7 and 8 of Sambrook et al. (1989).
Isolation of mRNA is a long, tedious process with a number of technically difficult steps. In summary, a typical procedure for isolating mRNA from a cell requires (1) disruption of cells to release cellular contents, (2) isolation of total RNA from the cell, (3) selection of the mRNA population by running the extracted RNA through an oligo(dT) cellulose column and (4) size fractionation of the isolated mRNA. At all stages, great care is required to ensure that the preparation does not come into contact with active ribonuclease enzymes which can destroy the RNA. Because the goal of the cDNA cloning procedure is to obtain xe2x80x9cfull lengthxe2x80x9d cDNA clones that contain the entire coding sequence of the gene, it is extremely important to use procedures that maintain the integrity of the mRNA. Ribonuclease (RNAse) enzymes are very stable and so even a very small amount of the active enzyme in an mRNA preparation will cause problems. RNAse is present on virtually all surfaces, including human skin, and is thus very easily introduced into the RNA preparation. To avoid contamination problems, all solutions, glassware and plasticware must be specially treated. The cells from which the mRNA is to be isolated are disrupted in solutions which are extremely harsh and contain components which immediately inactivate the omnipresent ribonuclease enzymes; all subsequent solutions used in RNA preparation are treated with diethylpyrocarbonate (DEPC), a suspected carcinogen) which inactivates RNAse. Often a laboratory will set aside particular equipment and work space that is designated to be xe2x80x9cribonuclease freexe2x80x9d. The potential for RNA degradation starts at the first step of breaking open the cells (the cells themselves contain ribonucleases which, upon lysis of the cells, come into contact with the RNA), and continue throughout the procedure.
Total RNA extracted from a cell is made up of messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA). The mRNA typically makes up only 1-3% of the total cellular RNA (approximately 1xc3x9710xe2x88x9212 g mRNA per eukaryotic cell, Sargent, T. D., Methods Enzymol. 152:423-432 (1987)). Most cDNA synthesis reactions rely on the presence of the poly(A) tail present only in mature mRNA transcripts. The mature RNA transcripts are selectively extracted from the bulk of the cellular RNA, usually by affinity chromatography. This is an essential step for successful in vitro cDNA synthesis; failure to enrich for the mature mRNA will result in a low yield of poor quality cDNA.
As a final stage prior to cDNA synthesis, the mRNA preparation may be size selected. This is usually performed to remove the smaller size molecules (usually degraded forms of larger mRNAs) which would otherwise interfere with the cDNA cloning procedure. Size selection may also be performed to enrich for an mRNA species of known size. Size selection may be performed by electrophoresis through agarose gels, by column chromatography, or by sedimentation through sucrose gradients. These techniques result in lower yields, and may require the presence of methylmercuric hydroxide to disrupt secondary intramolecular structure. Methylmercuric hydroxide is extremely toxic and volatile, and requires great care in handling. Safer alternatives (such as the use of gels containing glyoxal/dimethyl sulfoxide or formaldehyde) are available, but these techniques also involve dangerous chemicals and have associated disadvantages.
Additional disadvantages arise from the necessity of extracting mRNA from cells prior to cDNA synthesis. For example, cDNA cloning is often used to assess which genes are expressed in a cell under particular conditions or at a particular stage in the development of the organism. The time and conditions required to extract the mRNA may themselves produce alterations in the gene expression pattern of the cell. Furthermore, mRNA molecules which are present in very low abundance (estimated at 20 copies per cell) or which are unstable may be lost during the RNA isolation procedure. There is currently a lower limit on the number of cells necessary to produce a cDNA library due to the inherent losses incurred in mRNA isolation procedures. This invention addresses this problem by completely circumventing the initial mRNA isolation requirement.
Following extraction and purification of the mRNA, cDNA synthesis is performed in vitro. All methodologies presently used for cDNA synthesis follow mRNA extraction and purification, or are performed on dead cells under in vitro conditions. These methodologies are reviewed in detail in Kimmel and Berger (1987); Okayama, H., et al., (1987); and Embleton, M. J., et al., Nucleic Acids Res. 20:3831-3837 (1992)).
All of the presently available techniques utilize RNA-dependent DNA polymerase enzymes (more commonly termed reverse transcriptase enzymes) to synthesize the first strand of the cDNA from the mRNA template. Reverse transcriptase, like other DNA polymerases, cannot initiate nucleic acid synthesis de novo. Rather, it adds the first nucleotide of the nascent cDNA strand to the hydroxyl group at the 3xe2x80x2 end of a preexisting RNA or DNA strand that is annealed to the mRNA template. This preexisting strand to which the enzyme adds the first nucleotide is called a primer and appears to be absolutely required for reverse transcriptase activity. In their natural role, reverse transcriptase enzymes enter the cell within the infecting retrovirus. The enzyme is already associated with both a specific cellular transfer RNA (tRNA) molecule (present in all host cells), which the virus scavenged from a host cell during the previous infection, and a viral RNA chromosome. Transfer RNA molecules are short (70 to 80 nucleotides long) RNA molecules which are folded into complex three-dimensional structures; their usual cellular role is in the translation process (Darnell et al. (1989), chapter 4). After the virus enters a newly infected cell the reverse transcriptase-tRNA complex acts as primer for an in vivo (in the cell) reverse transcriptase reaction, using the viral RNA molecule, to which this complex is already bound, as the RNA template. The cDNA made from this in vivo reaction is then converted to double-stranded DNA by the same reverse transcriptase enzyme complex, and integrated into a chromosome of the infected cell. It is important to note that the reverse transcriptase-tRNA primer complex necessary for viral replication will not act as a primer for cDNA synthesis from cellular mRNA templates because the tRNA species (2 of about 40 types present in the cell) which have affinity for the reverse transcriptase enzyme are complementary to, and will therefore only prime from, sequences present on specific RNA molecules. It is interesting to note, however, that there are viruslike 30S (VL30) elements present in mouse cells which have regions of strong homology to retroviruses. These elements have properties of defective type C viruses, are reverse transcribed and are packaged into retroviral virions (Howk, R. S., et al., J. Virol. 25:115-123 (1978); Besmer, P. U., et al., J. Virol. 29:1168-1176 (1979)).
When reverse transcriptase enzymes are utilized for in vitro (outside the cellular environment) cDNA synthesis, the requirement of the enzyme for a primer molecule is usually satisfied by the inclusion of a oligodeoxynucleotide primer(s) in the reaction mixture. Most commonly, the primer is an oligomer of deoxyribothymidylic acid, oligo(dT). This primer is complementary to the poly(A) tail located at the 3xe2x80x2 and of the mRNA molecule (xe2x80x9cAxe2x80x9d nucleotides are complementary to, an anneal to xe2x80x9cTxe2x80x9d or xe2x80x9cUxe2x80x9d nucleotides). Thus, this oligo(dT) primer molecule anneals to the poly(A) tail region and serves as a primer for the reverse transcriptase enzyme. Alternatively, in vitro cDNA synthesis may utilize an oligonucleotide primer that is complementary to other sequences within the RNA molecule; however, because of the extensive stretch of complementary nucleotides necessary for annealing to occur, such a primer will be xe2x80x9csequence specificxe2x80x9d for the mRNA molecule to which it is designed to anneal. Synthesis of such a sequence specific primer requires prior knowledge of the nucleotide sequence of part of the mRNA. The primer requirements of reverse transcriptase enzymes are discussed in Chapter 5 of Sambrook, et al. (1989).
The product of the initial reverse transcriptase reaction in vitro is a single-stranded complementary DNA copy of the mRNA molecule. This reaction is often referred to as xe2x80x9cfirst strand cDNA synthesis.xe2x80x9d Thereafter, various techniques are used to generate the second strand of the cDNA. The resultant double-stranded DNA (dsDNA) molecules are then modified at the ends, and inserted into a xe2x80x9cvectorxe2x80x9d which allows growth, selection, and amplification of each copy. Most commonly used techniques (eg. Okayama and Berg, Molecular and Cellular Biology 2:161-170 (1982)) may be summarized as follows: Following extraction and purification of the mRNA and in vitro reverse transcription of the mRNA to produce single-stranded cDNA molecules, the mRNA template is eliminated to allow synthesis of the second strand of DNA and thereby form a double-stranded cDNA molecule; specific DNA linkers are then attached to the blunted end of the double-stranded cDNA,and the cDNA is ligated into a suitable cloning vector.
In all presently used techniques, the reverse transcriptase-catalyzed step of making a cDNA copy of the mRNA is always performed under in vitro conditions. The quality of the cDNA synthesis (that is, the ability to generate both accurate and full-length complementary DNA) depends upon the fidelity and the processivity of the enzyme chosen, and the conditions under which the reaction is performed. Clearly less than full-length cDNA is not acceptable, and a high error rate will compromise the utility of the cDNA produced. The use of the reverse transcriptase in vitro, rather than under the in vivo conditions which the enzyme has evolved to function, appears to adversely affect both the fidelity and processivity of the enzyme. The in vitro fidelity of MuLV reverse transcriptase has been estimated to be 10xe2x88x924 (i.e. one wrong nucleotide per 10,000 bases or 10 errors per 100 kb), and recent studies have determined that the in vivo fidelity is approximately 2xc3x9710xe2x88x925 (1 error for every 50,000 bases copied, 2 errors per 100 kb; Mont et al., J. Virol. 66:3683-3689 (1992)). In addition, it is difficult to obtain full length first strand synthesis in an artificial environment whereas the processivity of the enzyme in the in vivo cDNA synthesis reactions is excellent; with cDNA incorporation extending well past the 10 kb range (see included data). While conditions have been developed to optimize the performance of reverse transcriptase enzymes in vitro, these conditions do lead to a certain frequency of errors, and premature termination of first strand cDNA synthesis. It is clear that the in vitro conditions do not reflect the optimal conditions for the enzyme.
Thus, present techniques for cDNA synthesis are limited by (1) the requirement that the mRNA be extracted and purified from cells and (2) the performance of the reverse transcriptase enzyme under in vitro conditions. In combination, these factors limit: the ease of cDNA synthesis; the efficiency of cDNA synthesis; the size of cDNA molecules that can be produced (thereby the genes that are readily clonable by this technique); the accuracy of cDNA synthesis in determining which genes are expressed under particular conditions; and the fidelity of the cDNA produced.
It is an object of the present invention to provide a technique of cDNA synthesis that does not require the isolation of mRNA molecules from cells.
It is a further object of the present invention to provide a technique of cDNA synthesis that does not require in vitro activity of reverse transcriptase.
It is an additional object of the present invention to provide a technique of cDNA synthesis wherein the efficiency of the technique, the fidelity of the cDNA produced and the size of cDNA that the technique is capable of producing are superior to all presently used techniques.
The present invention relates to methods and compositions for the synthesis of complementary DNA copies of RNA templates in vivo.
In accordance with the present invention, a method for synthesizing a complementary DNA copy of an RNA template molecule is provided. The method comprises providing a polynucleotide molecule which is capable of annealing in vivo to an RNA template molecule, providing at least one reverse transcriptase enzyme which is capable of initiating DNA synthesis using the polynucleotide molecule as a primer, introducing the polynucleotide molecule into a viable target cell in the presence of the reverse transcriptase enzyme and incubating the target cell under conditions which permit the synthesis of a DNA molecule complementary to the RNA template molecule.
A further aspect of the invention provides a method for producing in vivo a complementary DNA copy of an RNA template molecule of which at least a partial sequence is known. This method comprises providing a DNA molecule comprising a sequence which encodes a promoter operatively linked to a sequence which encodes a polynucleotide molecule which is capable of annealing in vivo to an RNA template molecule and further capable of functioning as a primer for at least one reverse transcriptase enzyme; providing a first nucleotide primer wherein said primer is homologous to a sequence located 5xe2x80x2 to the end of the promoter sequence, and providing a second nucleotide primer wherein said primer comprises a 3xe2x80x2 sequence that is complementary to a 3xe2x80x2 region of the polynucleotide molecule joined to a 5xe2x80x2 sequence that is complementary to a portion of the known RNA template molecule sequence. Thereafter, the DNA molecule is contacted with the first and second primers, and the mixture is then treated under conditions and with reagents suitable for amplifying the cloned DNA molecule. At least one amplified DNA molecule produced thereby is then treated under conditions and with reagents suitable for production of an encoded RNA molecule, which is introduced into a viable target cell in the presence of at least one reverse transcriptase enzyme which is capable of initiating DNA synthesis using said RNA molecule as a primer. The target cell is then incubated under conditions such that a DNA molecule complementary to at least one RNA template molecule is produced.
Also provided in accordance with the present invention are compositions useful in the practice of the present method. Such compositions include polynucleotide molecules which are capable of annealing in vivo to an RNA template molecule and further capable of functioning as primer molecules for at least one reverse transcriptase enzyme, together with DNA molecules and recombinant DNA vectors encoding such polynucleotide molecules, and kits containing such compositions.

Methods and compositions for cDNA synthesis


The present invention provides OLEDs of the top emission type comprising organic light-emitting (LE) elements by preventing the problems such as the widening of the power lines, the reduction in the aperture ratio caused by the widening of the upper and the lower capacitor electrodes and the short circuit between the upper and the lower electrodes caused by the roughness of the flattening layers. Two kinds of the OLEDs are provided. One is an OLED comprising a region of LE layer sandwiched between the upper and lower electrodes is formed on a power line of TFT for driving the pixel. Another comprises a region of the LE layer formed on an electrode of capacitor connected to the TFTs to control the light-emitting element. Accordingly, without forming a flattening layer on the light-emitting layer, there is no electric short circuit between the lower electrode and the upper electrode.

1. Field of the Invention
The present invention relates to an organic light-emitting display device. More specifically, the present invention relates to an organic light-emitting display device which can prevent short circuit between two electrodes driving an organic light-emitting element in a light-emitting element due to the surface roughness of the substrate and provide an improved aperture ratio.
2. Description of the Related Art
As real multi-media era is coming up, flat panel displays (hereinafter, abbreviated to FPDs) used as a man-machine interface are being widely noticed. Conventionally, liquid crystal displays (hereinafter, abbreviated to LCDs) have been used as the FPDs. However, the LCDs have drawbacks such as their slow response and a narrow viewing angle compared with CRT displays.
Recently, as one of the next generation FPDs, display devices using organic light-emitting devices have attracted a great deal of attention. The device using the organic light-emitting device (hereinafter abbreviated to OLED) has superior properties such as spontaneous light emission, wider viewing angle, faster response speed and the like. Conventional structure of OLED is based on a stack of a first electrode preferably formed on glass, an organic light-emitting layer comprising a hole transport layer, a light-emitting layer and an electron transport layer formed on the first electrode, and a second electrode as an upper electrode with a low work function formed on the organic light-emitting layer. Then, by applying a voltage of several volts between the first and the second electrodes, holes and electrons are injected into the hole transport layer and the electron transport layer, respectively. Next, excitons are formed in the light-emitting layer where the holes and the electrons are combined. Finally, light is emitted from the light-emitting layer when the excitons formed return to their ground states. In the case of a so-called bottom emission type using the first electrode which is transparent, the emitted light passes the first electrode and is taken out from the back of the substrate.
Display devices using OLEDs are classified into two groups. One is the OLED of a simple matrix type and another is the OLED of an active matrix type. In the case of the simple matrix type, organic layers, comprising hole transport layers, light-emitting layers and electron transport layers, are formed on the positions where a plurality of anode lines (or anode wirings) and cathode lines (or cathode wirings) cross each other. Each pixel is lit up only for a preset period during one frame. The preset period is the time interval of the one frame divided by the number of the anode lines. The OLED of the simple matrix type has an advantage of its simpler structure.
However, in the case of the simple matrix type, if the number of pixels increases, the preset period should become shorter. Therefore, to achieve a required value for averaged luminance, it is necessary to increase the luminance of the pixel during the preset period. In this case, it causes a problem of a shortened life of the OLED. Furthermore, particularly for a large display-panel of OLED, as the OLED is driven by DC, non-uniform potential is applied to each pixel because of the potential drop due to elongated lengths of the anode and cathode lines. As a result, non-uniform luminance is generated over the entire display area. Therefore, qualities in terms of high definition of the pictures and scaling-up of the display size are limited for the simple matrix type.
On the other hand, in the case of an OLED of an active matrix type, each organic light-emitting element comprising each pixel is connected to an element driving circuit (or a pixel driver) comprising 2 to 4 switching elements such as thin film transistor (hereinafter abbreviated to TFT) and capacitors. Also, power lines are formed to supply current to each light-emitting element and thereby all pixels can be simultaneously operated during the period of one frame. Thus, it is not necessary to increase the luminance of the pixels all together and their lives can be elongated. From these reasons, to achieve high definition of pictures and scaling-up (or large display size), the OLED of the active matrix type has an advantage over other types of the OLEDs. Hereinafter, TFTs are used for the switching elements but other active elements can be used instead.
The OLED of the active matrix type which emits light from the back of the substrate is called "bottom emission type". In the OLED of this type, as the pixel driving elements are installed between the substrate and organic light-emitting elements, as the pixel driving elements obstruct the light emitted from the light-emitting elements and aperture ratio is restricted. Particularly, in the case of large area displays, widths of power lines are widened to reduce the non-uniformity of the luminance of pixels due to potential drop along the power lines, which brings a problem that the aperture ratio of the display becomes smaller. Additionally, if the capacitances of the capacitors are increased to preserve the bias and signal voltages of the transistors to drive the OLED, the area of the capacitor electrodes increases, which accordingly causes a problem that the aperture ratio becomes extremely small.
To solve above problems, efforts to emit the light from the upper electrode using transparent electrode are being made. The OLED with the structure of light emission from the upper electrode is called "a top emission type". However, in the structure of the top emission type, light-emitting units of OLED are formed on the TFTs, capacitor electrodes or wirings, which causes a problem of a short circuit between the bottom and the upper electrode. It is because the organic light-emitting layer which forms a light-emitting unit and is very thin (about 50–200 nm) can not cover the surface roughness of its underlying layer. This is one of the problems to be sorted out.
To solve this problem, an OLED using a polyimide film as a flattening layer to reduce the surface roughness of its underlying layer was disclosed in JP-A No. 10-189252, which is incorporated herein by reference. FIG. 11 illustrates a sectional view of a structure of a pixel region in the conventional OLED showing the flattening layer formed on its underlying layer. Referring to FIG. 11, a gate insulating film 117 covering a lower capacitor electrode 105 and an upper capacitor electrode 108 are formed on a glass substrate 116. A capacitor which consists of a stack of the lower capacitor electrode 105, the gate insulating film 117 and the upper capacitor electrode 108 is formed.
A 1st insulating interlayer 118 is formed on the stack of the capacitor. On the capacitor, a power line 110 is formed and connected to the upper capacitor electrode 108. Here, a signal line 109 is formed simultaneously. A 2nd insulating interlayer 119 is formed covering the power line 110 and the signal line 109. The flattening layer 136 is formed on the 2nd insulating interlayer 119 and provides a flat surface for a deposition of a lower electrode 115 to form an organic light-emitting element. Reference numeral 120 denotes a 3rd insulating interlayer 120 which prescribes a region of a light-emitting unit 135. Reference numeral 126 denotes a protective layer.
FIG. 12 shows a schematic equivalent circuit diagram of a driving circuit for the organic light-emitting element in the OLED shown in FIG. 11. The same reference numerals shown in FIG. 11 are correspondingly numbered in FIG. 12. Referring to FIG. 12, one pixel consists of an organic light-emitting element 100, a 1st TFT 101 connected to a scanning line 106 and a signal line 109, a 2nd TFT 102 connected to a power line 110 and a capacitor 104. The scanning line 106 selects the TFT 101 and a signal (i.e. data to be displayed) from the signal line 109 is stored in the capacitor 104. Based on the signal stored in the capacitor 104, the 2nd TFT 102 provides a current from the power line 110 for the organic light-emitting element 100 and then the organic light-emitting element 100 emits light.
Therefore, in the conventional OLED, the surface roughness of the lower capacitor electrode 105 and the upper electrode for the capacitor 108 and steps formed by the power line 110 and the signal line 109 can not be eliminated by the 2nd insulating interlayer 119. Accordingly, a thick flattening layer 136 must be formed to flatten the light-emitting unit 135 consisting of the lower electrode 115, an electron injection layer 124, an electron transport layer 123, a light-emitting layer 122, a hole transport layer 121 and the upper electrode 125. However, to introduce the above flattening layer 136, it requires additional processes such as a spin coating, a baking process, a patterning process using a photolithography, etc, which degrades the reliability of the total process.
In short, based on the prior art, the structure of the OLED of the top emission type is required to ensure a high aperture ratio. Accordingly, the flattening layer 136 with thickness of several μm is necessary to avoid a short circuit between the lower electrode 115 and the upper electrode 125 herewith, where the short circuit is caused by the surface roughness originated from the underlying layers comprising the TFT, wirings, etc.
Thus, a purpose of the present invention is to provide an OLED of the top emission type comprising organic light emitting elements by preventing the previous problems such as the widening of the power lines, the reduction in the aperture ratio caused by the widening of the upper and the lower capacitor electrodes and the short circuit between the upper and the lower electrodes caused by the roughness of the flattening layers.

This patent is subject to a terminal disclaimer.


Embodiments of a projectile are disclosed herein. According to various embodiments, a projectile includes a substantially solid core of a material, and two or more petals attached to the core. The two or more petals can be formed from the same material used to form the core and can include a trocar tip. A cavity can be bound by the core and inner surfaces of the plurality of petals.

Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Firearms are believed to have first been invented around the thirteenth or fourteenth centuries. At that time, "firearms" consisted of bamboo rods used to guide shrapnel or other projectiles using the force of combusting gunpowder. Over the years, firearms have evolved tremendously, as have the projectiles fired from firearms.
Many early firearms relied on various forms of shrapnel for projectiles. With the evolution of firearms, bullets and other projectiles similarly have evolved. With the evolution of the musket and similar firearms, spherical lead balls were used for projectiles as the soft lead could be pushed into the barrel easily and provided a relatively effective projectile. With the advent of modern firearms, particularly in the early part of the nineteenth century, bullets evolved into pointed or conical projectiles. For example, Norton's bullet, named for John Norton of the British Army, was among the earliest pointed projectiles, the precursor of modern bullets and other projectiles.
In the late nineteenth century, copper jacketing processes were introduced to firearm projectiles. Copper jacketing was used to protect the projectile from melting and/or otherwise deforming in the barrel of the firearm due to pressures and heat in the barrel. Thus, copper jacketing allowed bullets to evolve from flying chunks of lead with limited accuracy, speed, and effectiveness into carefully aimed high speed projectiles that maintained their shape in the barrel and during flight.
In the twentieth century, ballistics took many leaps. In the twentieth century, for example, the spitzer bullet shape was introduced, which is essentially the shape of the modern rifle bullet. Similarly, boat tail bullets were introduced, which further enhanced the accuracy of bullets, as well other shapes and modifications introduced during this time period. During the twentieth century, evolution of overall bullet shape essentially was completed. Thus, bullet makers began increasing the lethality and/or damaging effect of bullets, particularly in the last half of the twentieth century. In particular, the hollow point was introduced to bullets to increase and/or control the expansion (sometimes referred to as the "mushrooming" effect) of the bullet when penetrating a target. The hollow point evolved considerably during the last fifty years or so to provide many types of self-defense and hunting ammunition.
One tradeoff often encountered by bullet makers is that penetration of bullets often must be sacrificed for expansion of the bullet in the target. In some targets, the lack of penetration can limit the effectiveness of the bullet. For example, the bullet may expand to a large size, but not contact any vital organs of a target if the bullet does not penetrate into a body cavity of the target. Thus, while the bullet may damage the cutaneous, subcutaneous, and/or even some internal organs of the target, the bullet may lack the effectiveness to neutralize the target due to a lack of penetration.
Similarly, if penetration is prioritized over expansion, the effectiveness of the bullet can be diminished. In particular, a bullet may penetrate a target or even pass through the target without contacting any vital organs and/or without causing sufficient damage to the vital organs to incapacitate the target. Of course, penetration through the target can create or increase a risk of collateral damage to people or objects in the vicinity of the target. For example, a small caliber bullet may pass through a target and pierce organs without neutralizing the target. In the realm of self-defense ammunition, the goal generally is to provide maximum expansion and maximum penetration to attempt to ensure that a threat is neutralized as quickly as possible. Another goal of self-defense ammunition is to expend as much of the projectiles energy as possible within the target.


In a device (3) for fastening balancing weights to rotors (2) with a plurality of compensation planes, in particular to propeller shafts or Cardan shafts, preferably in a balancing machine (1) that includes at least one gripper-like device which can be positioned along the rotor axis, and with which a balancing weight is placed on the external periphery of the rotor (2) and can be fastened there, the gripper-like device (5) includes plural receivers for receiving a plurality of the balancing weights.

Devices and methods of the type mentioned at the outset are used in series production to economically balance relatively large unit numbers of rotors which comprise a plurality of compensation planes, for example propeller shafts or cardan shafts.
It is known from DE 44 40 812 A1 to arrange a rotor, for example a cardan shaft, in a balancing machine, to ascertain the imbalance in terms of size and angular position and to then place balancing weights in the compensation planes of the cardan shaft on the periphery of the rotor by means of at least one gripper-like device associated with the balancing machine, and to fasten them. For this purpose, the balancing weight is received by a unit of the gripper-like device, which gripper-like device is brought into the compensation position and the rotor rotated into the correct angular position. The balancing weight is then fastened, for example, by means of a gluing or welding operation. A gripper-like device is provided in each compensation plane for compensating imbalances in a plurality of compensation planes. Instead of this, a gripper-like device displaceable only along the rotor axis may be provided which is displaced into the relevant compensation plane in each case. Irrespective of whether one or more gripper-like devices are provided, there is expensive equipping of the gripper-like device with a balancing weight which is required at this balancing point for each balancing step.

Device and method for fastening balancing weights to rotors, in particular to propeller shafts or cardan shafts


A multiply-multiply-accumulate (MMA) system (10) efficiently evaluates matrix products X=F*C. Matrix C is dissected into submatrices A and B taking advantage of symmetry in C. LOG unit (14) converts B, A, and F to LOG values B', A' and F'. These are summed in K parallel calculating units CU's (18) and converted back to Normal domain as P=F*B*A in ALOG units (22) and sent to accumulators ACU's (24). The ACU's (24) accumulate the results. An output buffer (26) combines the results. The B', A' values (32,34) are held in a cache memory (20) and the LOG sums are performed in two steps with intermediate storage.

It is often necessary in the electronic arts to evaluate expressions of the general form given in Eq. (1): EQU X.sup.(I,J) =F.sup.(I,N) *C.sup.(N,J) (1)
where X.sup.(I,J) is a matrix with dimensions (I,J), F.sup.(I,N) is a matrix with dimensions (I,N) and C.sup.(N,J) is a matrix with dimensions (N,J). For example, F can be a data stream while C is a coefficient matrix. F can also be a vector, i.e., a one-dimensional matrix.
It is known that such expressions can be evaluated by means of the following equation: ##EQU1## where i, j and p are indices. Examples of such functions are the Forward Discrete Cosine Transform (FDCT) and the Inverse Discrete Cosine Transform (IDCT) and Two Dimensional Discrete Fourier Transform (2-d DFT), and general matrix multiplication. Operations of the type illustrated by Eq. 2 are referred to generally as a Multiply-Accumulate, abbreviated as MA.
Because of the importance of MA operations in modem electronics, especially in communication electronics, there is an ongoing need for means and methods which permit MA operations to be carried out more quickly or with fewer resources or both. For example, it desirable to be able to perform such operations with simpler or more compact or higher speed microelectronic circuits or less on-chip memory or combinations of such advantages. It is especially desirable to be able to evaluate MA expressions such as Eqs. (1)-(2) while using less on-chip cache memory space.

Apparatus and methods for performing arithimetic operations on vectors and/or matrices


A catalyst for improving combustion of fluid fuels which comprises three layers. An inner or core layer of complex oxides of a mixture of Mn, Ni, Co and Cu; an intermediate layer containing alumina and silicate and optionally silicon carbide and an outer layer comprising a fired mixture of a Pt--Pd,Rh alloy on Al.sub.2 O.sub.3, Mo--Al.sub.2 O.sub.3, mixed oxides of La--Sr--Co and at least one of Vanadium oxide on alumina and Ag on Alumina. The catalyst can contact the fluid fuel in a storage tank, in a pipeline or in a combustion chamber. The invention also comprises combustion engines which incorporate the described catalyst.

This invention relates to internal combustion engines and more particularly, to a fluid fuel reforming ceramic catalyst that effectively increases combustion efficiency and decreases obnoxious substances in gasoline, light oil and other liquid fuels and natural gas and other gaseous fuels by reforming them and to transporting and power-generating means employing such internal combustion engines using the catalyst.
Gasoline, for example, contains approximately 30 percent of benzene, acetaldehyde and other difficultly combustible and environment polluting substances and approximately 10 percent of octane-number increasing substances, anti-freeze agents and other additives, in addition to approximately 60 percent of combustible substances. The difficultly combustible and environment polluting substances are discharged as obnoxious substances in exhaust gases as a result of incomplete combustion. Reforming these difficultly combustible and environment polluting substances into combustible substances will increase the ratio of combustible substances that are conducive to efficient combustion.
To efficiently burn the reformed substances, however, the oxygen supply (or air supply) must be increased. However, larger quantities of air inevitably contain greater amounts of nitrogen. Then, the content of nitrogen oxides in the exhaust gases inevitably increases. Although some air is dissolved in fuels, not all of the oxygen contained in the dissolved air contributes to the combustion reactions. If the dissolved oxygen not contributing to the combustion reactions is activated, then the additional combustible substances obtained by reforming difficultly combustible and environment polluting substances can be efficiently burned without increasing the amount of air supplied from the outside.
Accordingly, efficient burning of combustible substances in internal combustion engines using the fluid fuels mentioned above and in transporting and power-generating means employing such internal combustion engines will be conducive to a reduction in environmental pollution and attainment of higher energy efficiency.
Thus, the object of this invention is to provide catalysts that reform difficultly combustible and environment polluting substances contained in fluid fuels to readily combustible substances, increase combustion efficiency and decrease the content of obnoxious substances in exhaust gases by activating the oxygen in the air dissolved in fuels and internal combustion engine systems utilizing a catalyst and transporting and power-generating means employing such internal combustion engines.

Internal combustion engines, fluid fuel reforming ceramic catalyst and transporting and power-generating means employing them


A method and an apparatus for measuring an electric insulated conductor, in particular a medium-voltage and/or high-voltage insulated conductor, are proposed. Seen in profile cross-section, the insulated conductor (50) includes a copper conductor, an inner semiconductor, an insulation and an outer semiconductor and is produced in an extrusion device (90) having an appropriately assigned crosslinking section (40). To achieve an even distribution of the two semiconductor layers and of the insulation layer, the insulated conductor (50) is radiated through immediately at the outlet from the crosslinking section (40) and a correction of the die setting in the extrusion device is carried out by means of values thus determined.

The invention relates to a method of measuring the cross-section of an electric insulated conductor, in particular a medium-voltage and/or high-voltage insulated conductor, as well as to an apparatus for carrying out the method, in which method/apparatus an inner semiconductor, an insulation and an outer semiconductor are applied to a copper conductor in an extrusion device provided with appropriate dies, and the individual layers of the insulated conductor are crosslinked in an appropriate installation.
EP-A 0 400 310 discloses an apparatus for controlling the outside diameter of an insulated conductor, in which apparatus the outside diameter of the plastics strand emerging from the extruder is measured by means of a first measuring device immediately following the extruder and by a second measuring device following a cooling section and the actual diameter determined by this way of measuring is compared with the set diameter. A signal is formed from the difference values and this signal is used for controlling the speed of the extruder or for controlling the take-off rate of the plastics strand emerging from the extruder. With the known apparatus, only the outer diameter is measured and, in the event of any deviations, the extruder corrected correspondingly.
EP-A 0 387 508 discloses an apparatus for vulcanising or crosslinking an insulated conductor strand, which apparatus essentially comprises a tubular body which is designed with an inspection-glass fitting and essentially forms the heating and cooling zone.
With current requirements for such insulated conductors, but in particular in the case of medium-voltage and high-voltage insulated conductors having a plurality of plastic layers surrounding a copper conductor, it is necessary that, on the one hand, the copper conductor is arranged centrally in the insulated conductor and, on the other hand, the individual plastic layers have minimum possible difference in thickness over the circumference of the insulated conductor, i.e. that the individual layers are evenly distributed on the finished insulated conductor.

Method and apparatus for the cross-sectional measurement of electric insulated conductors


An electrical fuse circuit including: a capacitor composing an electrical fuse; a write circuit breaking an insulating film of the capacitor by applying voltage to between both terminals of the capacitor in accordance with a write signal; and a precharge circuit precharging with respect to the terminal of the capacitor, is provided.

1. Field of the Invention
The present invention relates to an electrical fuse circuit, a memory device and an electronic part.
2. Description of the Related Art
FIG. 16 is a view showing a semiconductor memory chip including a laser fuse. The semiconductor memories in recent years include a redundant memory cell using a laser fuse, in which a defective memory cell is replaced with a redundant memory cell in general. The laser fuse is a nonvolatile ROM cutting a wiring layer with a laser beam to write (for example, in an uncut state, it is in an electrically connected state being "0 (zero)", and in a cut state, it is in an electrically unconnected state being "1"), and the replacement to the redundant memory cell is performed by letting this ROM memorize the address of the defective memory cell. However, after a memory chip 1601 using the laser fuse is packaged in a package 1602, no laser LS is emmittable thereto. It is known as a phenomenon that a DRAM in the memory chip 1601 is degraded in refresh characteristic and the like, affected by heat or the like at the time of the packaging. However, it is impossible to emit the laser LS thereto after the packaging. Therefore, a method, in which an electrically writable electrical fuse is used as a nonvolatile ROM and the ROM is made to memorize the address of the defective memory cell to replace the defective memory cell with the redundant memory cell, is under study.
FIG. 17 is a view showing a configuration example of an electrical fuse circuit. Hereinafter, a field-effect transistor is simply called a transistor. An electrical fuse capacitor 101 is connected to between a voltage VRR and a node n3. An n-channel transistor 102 is a protection transistor connected to a voltage VPP with a gate thereof, to the node n3 with a drain thereof, and to a node n2 with a source thereof. The voltage VPP is for example 3V. An n-channel transistor 103 is a write circuit connected to a write signal WRT with a gate thereof, to the node n2 with a drain thereof, and to a ground with a source thereof.
Subsequently, the description will be given of the configuration of a read circuit 110. An n-channel transistor 111 is connected to a read signal RD with a gate thereof, to the node n2 with a drain thereof, and to a node n4 with a source thereof. An n-channel transistor 113 is connected to a node n5 with a gate thereof, to the node n4 with a drain thereof, and to a ground via a resistance 114 with a source thereof. A p-channel transistor 112 is connected to the node n5 with a gate thereof, to a voltage VII with a source thereof, and to the node n4 with a drain thereof. The voltage VII is for example 1.6 V. A nonconjunction (NAND) circuit 115 is connected to a power supply voltage VII and an input terminal thereof is connected to the node n4 and the line of a signal RSTb, and an output terminal thereof is connected to the node n5. A NOT circuit 116 is connected to the node n5 with an input terminal thereof and to the line of a signal EFA with an output terminal thereof.
FIG. 18 is a view showing a configuration example of an electrical fuse circuit 215 and a peripheral circuit thereof and FIG. 19 is a timing chart showing an example write operation of an electrical fuse circuit. The electrical fuse circuit 215 corresponds to the electrical fuse circuit in FIG. 17. A booster circuit & level control circuit 201 boosts the voltage and controls the level to supply the voltage to a plurality of unit circuits 203. An electrical fuse control circuit 202 outputs the signal RD, the signal RSTb, a signal EF-WRITE, a signal EF-START, a signal EF-CLK, a signal EF-STRB to the plurality of unit circuits 203. Each of the unit circuits 203 includes flip-flops (FFs) 211, 212, a NAND circuit 213, and a NOT circuit 214 and an electrical fuse circuit 215. The flip-flops 211 in the plurality of unit circuits 203 input address signals A0 (zero) to A2 and a valid signal VALID and compose address resistors 204, respectively. For convenience's purpose of description, the case of 3-bit address signals A0 (zero) to A2 is described as an example. The valid signal VALID is a signal indicating whether or not to validate memorized contents of the electrical fuses corresponding to the address signals A0 (zero) to A2. For instance, when no defective memory cell exists and no replacement to the redundant memory cell is required, just make the valid signal VALID to low level. The flip-flops 212 in the plurality of unit circuits 203 compose shift resistors 205.
Before a time t1, the pulse of the signal EF-STRB is inputted into clock terminals of the flip-flops 211 and the address signals A0 (zero) to A22 are inputted into the input terminals of the flip-flops 211, respectively.
The description will be given of a writing example in the case where the signals such as the address signal A0 (zero) at low level, the address signal A1 at high level, the address signal A2 at low level, and the valid signal VALID at high level, as an example, are written into the electrical fuse. The register 211 of the address signal A0 (zero) outputs low level. The register 211 of the address signal A1 outputs high level. The register 211 of the address signal A2 outputs low level. The register 211 of the valid signal VALID outputs high level.
At and after the time t1, a clock signal CLK becomes a clock pulse having a constant frequency. The signal EF-WRITE is a pulse having the same cycle as of the clock EF-CLK. At the time t1, the start signal EF-START is turned from high level into low level. Then, the shift resister 212 shifts the start signal EF-START to output it to the next shift register 212. With this, the resister 212 of the address signal A0 (zero), the resister 212 of the address signal A1, the resister 212 of the address signal A2 and the resister 212 of the valid signal VALID output the shifted pulse, respectively.
After the time t1, the NOT circuit 214 of the address signal A0 (zero) keeps low level to output no pulse as a write signal WRT. After the time t2, the NOT circuit 214 of the address signal A1 outputs a high-level pulse as a write signal WRT. After the time t3, the NOT circuit 214 of the address signal A2 keeps low level to output no pulse as a write signal WRT. After the time t4, the NOT circuit 214 of the valid signal VALID outputs a high-level pulse as a write signal WRT.
In FIG. 17, when the write signal WRT becomes high level, the transistor 103 is turned on. The high voltage VRR (for example, 8V) is applied to the capacitor 101. The electrical fuse is composed of the capacitor 101, and is in the electrically unconnected state when nothing is done. When the high voltage (for example, 8V) is applied to both the terminals of the capacitor 101, an insulating film of the capacitor 103 is broken so that the capacitor is put into the electrically connected state. These two states are assigned to data 0 (zero) and data 1, respectively. For example, when it is in the electrically unconnected state where the insulating film of the capacitor is not broken, "0 (zero)" is assigned, and when it is in the electrically connected state where the insulating film of the capacitor is broken, "1" is assigned. The capacitor 101 can be used as a nonvolatile ROM.
The high voltage required to perform a breaking operation of the insulating film of the electrical fuse (hereinafter called the "write operation") is generated by the booster circuit 201 provided in the semiconductor chip. Further, when trying to write into the plurality of capacitors 101 at a time as a write operation, huge current may flow, so that the writing is performed to the capacitors on the one by one basis by providing the shift registers 205.
The description will be given of the write operation into the capacitor (electrical fuse) 101. First, the booster circuit 201 boosts the voltage VRR at the common node of the plurality of capacitors 101 to high voltage (for example, 8V). At this time, the other terminal node n3 of the capacitor is in the floating state, so that the potential of the node n3 increase as well. In this state, the difference between the potentials of both the terminals of the capacitor 101 is still small. After that, the transistor 103 into which the write signal WRT selected by the shift resistor 205 is written is turn on and the high voltage is applied to between both the terminals of the capacitor 101 using the node n3 as a ground to break the insulating film of the capacitor 101. At this time, in the capacitor 101 corresponding to the unselected write signal WRT, the node n3 is still in the floating state, so that the high voltage is not applied to between both the terminals of the unselected capacitor 101. Should the high voltage be applied, the insulating film of the capacitor into which the writing is not intended to be performed actually, will be broken.
FIG. 20 is a timing chart of the semiconductor memory chip including the electrical fuse circuit when the power supply starts. A power supply voltage VDD is the power supply voltage for the semiconductor memory chip, and is for example 1.8 V. With the power supply starting, the voltages VDD, VRR and RC increase gradually. After a while, the voltage VRR keeps around 1.6 V. The signal RSTb keeps low level. In FIG. 17, when the signal RSTb is low level, the node n5 becomes high level. Then, the transistor 112 is turned off and the transistor 113 is turned on. As a result, the node n4 turns from the floating state into low level. After that, the signal RSTb turns from low level into high level. When the capacitor 101 is in the connected state, the node n4 becomes high level and the output signal EFA becomes high level. Meanwhile, when the capacitor 101 is in the unconnected state, the node n4 becomes low level and the output signal EFA becomes low level. After that, the voltage VRR and the read signal RD becomes the ground, the transistor 111 turns off, and the output signal EFA is kept. Based on the above operation, the read circuit 110 outputs the state of the capacitor 101 as a signal EFA.
In Japanese Patent Application Laid-Open No. 2006-147651 (Patent document 1), there is described a semiconductor integrated circuit, in which, a fuse metal being unconnected by being applied Vdd to one end portion thereof and at the same time by being applied a laser beam is provided above a semiconductor substrate with the other end portion thereof being provided on the substrate, and the fuse metal is electrically connected to a drain of an N-channel transistor for programming being applied Vss as a back bias.
Also, in Japanese Patent Application Laid-Open No. Hei9-185897 (Patent document 2), there is described a redundant fuse circuit including: a node determining a logic state of a redundant addressing signal, a fuse provided in parallel with the node, and a precharge circuit precharging the node in accordance with a clock.
FIG. 21 is a timing chart showing an example writing malfunction of a fuse circuit, which corresponds to FIG. 19. The description of the same signals as in FIG. 19 will be omitted here. In the voltage VRR, a pulse of 8V is generated at the same cycle as of the signal EF-WRITE. When the write operation writing into the plurality of capacitors (electrical fuses) 101 on the one by one basis is repeated, the potential of the node n3 in the unselected electrical fuse circuit downs gradually due to a junction leakage or the like. When the number of the entire bits of the electrical fuse is large, a high voltage 2101 is caused to be applied to both the ends of the capacitor 101 of the unselected electrical fuse, and thereby the writing is caused to be performed into the capacitor which is not intended to be written actually, leaving a problem.

Electrical fuse circuit, memory device and electronic part


A Ni-based superalloy component includes a bond coat layer having a chemical composition not allowing interdiffusion to occur on a Ni-base superalloy substrate, and by allowing the bond coat layer to have Pt and/or Ir content equal to or higher than 0.2% but not exceeding 15% by mass, generation of an SRZ, which occurs at an interface between the Ni-base superalloy substrate and the bond coat layer in a high-temperature oxidizing atmosphere, can be suppressed, and at the same time adhesion at the interface between a ceramic thermal barrier coat layer and the bond coat layer is improved. Thus, a long-life Ni-based superalloy component with suppressed elemental interdiffusion between the Ni-base superalloy substrate and the bond coat layer even at temperatures exceeding 1100° C. is provided.

As heat-resistant components for turbine rotor blades and turbine stator blades for jet engines and industrial gas turbines, Ni-based superalloys with improved heatproof temperature have been developed. With these heat-resistant components for turbine rotor blades and turbine stator blades, to further improve durability, a ceramic thermal barrier coating is widely used. Furthermore, to promote adhesion of the ceramic thermal barrier coating to Ni-based superalloy jet engine parts and prolong parts life, a number of highly oxidation-resistant bond coat materials have been proposed for use between a Ni-based superalloy component and a ceramic thermal barrier coating material. These bond coating materials are, in most cases, Al-containing alloys such as Ni- or Co-aluminide, MCrAlY (M is at least one metal selected from Ni, Co and Fe), and platinum-aluminide (Patent Literatures 1 to 4).
However, if a turbine blade made of a Ni-based superalloy adopting these bond coat materials is used at a high temperature for a long time, elemental interdiffusion progresses in proximity to the interface between the Ni-base superalloy substrate and the bond coat material and/or between the ceramic thermal barrier coat material and the bond coat material. Consequently, material technological problems, such as material degradation and decrease in durability of the Ni-based superalloy and decrease in durability of the bond coat material, arise, resulting in decrease in durability of turbine blades themselves. In particular, since gas temperature of jet engines and gas turbines has recently been increasing, turbine blade temperature is also increasing, thereby further accelerating the occurrence of a phenomenon of elemental interdiffusion. In addition, high-pressure turbine blades have a hollow structure to facilitate cooling, and because thinning is progressing, suppression of elemental interdiffusion is becoming an increasingly significant technical challenge.
To suppress elemental interdiffusion in the proximity of the interface between a Ni-base superalloy substrate and a bond coat material, a diffusion barrier coating has been studied, but sufficient effect has yet to be obtained.
Paying attention to the fact that elemental interdiffusion occurs, thereby causing Ni-base superalloy substrate to degrade, because the alloy composition of the Ni-base superalloy substrate and that of the bond coat material are not in a state of thermodynamic equilibrium, the inventors have proposed to use an alloy that is in a state of thermodynamic equilibrium with a Ni-base superalloy substrate as a bond coat material(hereinafter referred to as EQ coat material). Specifically, it has been clarified that by coating one or more layers containing at least one of γ phase, γ′ phase, and B2 phase having a composition that is in a state of thermodynamic equilibrium with the Ni-base superalloy substrate on the Ni-base superalloy substrate, elemental diffusion is suppressed significantly, and that degradation of the coated Ni-based superalloy can thus be suppressed (Patent Literature 5).
In the case heat-resistant gas turbine components using a Ni-based superalloy as a substrate, in order to increase heat resistance of the Ni-base superalloy substrate, currently, a ceramic thermal barrier coat layer is coated on the surface of the substrate. However, since long-term adhesion property of the interface between the Ni-base superalloy substrate and the ceramic thermal barrier coat layer is insufficient, the Ni-base superalloy substrate and the ceramic thermal barrier coat layer are bonded via a bond coat layer. The bond coat layer is made of a bond coat material. Of various bond coat materials that have thus far been proposed, EQ coat material is an excellent bond coat material capable of suppressing generation of a secondary reaction zone (SRZ), which occurs in proximity to the interface between the Ni-base superalloy substrate and the bond coat layer. However, even if the EQ coat material is used, detachment of ceramic coat layer occurs as a result of generation of an oxide layer under high-temperature oxidizing conditions in proximity to the interface between the ceramic thermal barrier coat layer and the EQ coat material. Thus, the life of Ni-based superalloy components is not necessarily considered to be sufficient.

NATIONAL INSTITUTE FOR MATERIALS SCIENCE


An active carbon suitable for use in electrodes for an organic solvent type electric double layer capacitor, which is obtained by calcining an easily graphitizable organic substance and then activating the resultant carbonized product with an alkali, wherein a mode in the pore size distribution of the active carbon according to a transmission electron microscope (TEM) image analysis method falls within a range of 10-20 angstroms, and an conjunctive pore rate, which is expressed by a proportion of the total area of pores having an area not smaller than 500 square angstroms to the whole pore area in the TEM image, is at least 20%.

1. Field of the Invention
The present invention relates to active carbon suitable for use in polarizable electrodes for an electric double layer capacitor making use of an electrolytic organic solvent solution.
2. Description of the Background Art
Since an electric double layer capacitor has a large capacity of the farad level and is also excellent in charge and discharge cycle properties, it is used in applications such as back up power supplies for electronic equipment and batteries for automobiles.
In this electric double layer capacitor, for example, as illustrated in FIG. 4, a pair of polarizable electrodes 1, 1 composed of active carbon are arranged in an opposed relation to each other through a separator 2, and the polarizable electrodes 1, 1 are impregnated with an organic solvent solution of a tetraalkylammonium salt or the like as an electrolytic solution so as to function as positive and negative electrodes, respectively. In the electric double layer capacitor illustrated in FIG. 4, the polarizable electrodes 1, 1 opposed to each other through the separator 2 are contained in an aluminum container 3 which is closed with an aluminum lid 5 through a packing 4. In the above-described construction, the container 3 and the lid 5 come into separate contact with the polarizable electrodes 1, 1 in such a manner that the container 3 serves as a current collector member on the cathode side to the polarizable electrode 1, and the lid 5 serves as a current collector member on the anode side to the other polarizable electrode 1.
Although active carbon having fine pores is used for the polarizable electrodes for such an electric double layer capacitor, there is a demand for development of active carbon capable of more heightening the capacity density of the polarizable electrodes for the purpose of providing a smaller and lighter electric double layer capacitor having a greater capacity.
Therefore, various properties of active carbon have been investigated with a view toward providing active carbon capable of heightening the capacity density of the polarizable electrodes. For example, the hypothesis that "A capacity density per weight of active carbon in an electrode has an almost linear proportional relationship with a specific surface area of the active carbon, and the capacity of an electric double layer on the active carbon electrode is about constant without being affected by the kind of carbon and pore characteristics thereof" has been proposed (Electrochemistry, 59, No. 7, pp. 607-613, 1991).
For example, Japanese Patent Application Laid-Open No. 302735/1995 describes active carbon the capacity density per weight of which has been heightened by subjecting a carbonaceous material to activation to enlarge its specific surface area on the basis of the above hypothesis. The active carbon described in the publication is such that the carbonaceous material is subjected to the activation, thereby forming pores suitable for adsorption of the electrolytic solution ions.
However, the active carbon described in the publication involves a disadvantage that its capacity density per volume is lowered when the activation is conducted until the capacity is developed.
In order to solve the above disadvantage, the present inventors attempted to investigate the above hypothesis. The investigation by the present inventors revealed that when a theoretical value of the capacity of an electric double layer capacitor comprising polarizable electrodes making use of such active carbon is found from a value observed by a mercury electrode or the like as the capacity of the electric double layer of the active carbon and a specific surface area of the active carbon, the theoretical value may not consist with the found value of the capacity of the electric double layer capacitor in some cases.
For example, assuming that the capacity of the electric double layer capacitor so constructed that a pair of polarizable electrodes 1, 1 are arranged with a separator 2 held therebetween as illustrated in FIG. 4 is C.sub.0, and capacities of the polarizable electrodes 1, 1 are C.sub.1 and C.sub.2, the following equation is satisfied: EQU 1/C.sub.0 =1/C.sub.1 +1/C.sub.2 ( 1)
Here, the capacity of the electric double layer of the active carbon observed by the mercury electrode is about 20 .mu.F/cm.sup.2. Therefore, the capacity of the electric double layer of active carbon having a specific surface area of 1,500 m.sup.2 /cc amounts to: EQU 20 (.mu.F/cm.sup.2).times.1,500 (m.sup.2 /cc)=300 (F/cc)
Then, 300 (F/cc) is substituted for C.sub.1 and C.sub.2 in the equation (1) to find C.sub.0. As a result, C.sub.0 amounts to 150 (F/cc). Since C.sub.0 is a capacity for two volumes of the polarizable electrode 1, the theoretical capacity of the electric double layer capacitor should amount to 75 F/cc obtained by dividing the C.sub.0 value by 2.
In reality, the capacity of the electric double layer capacitor amounts to only about 13 F/cc. Even when different kinds of active carbon having the same specific surface area are used, the capacities of the resultant electric double layer capacitors may be entirely different from each other in some cases.
Then, the present inventors paid attention to the fact that the above hypothesis is based on the specific surface area measured by nitrogen gas absorption in accordance with the BET method, and attempted a special image analysis capable of analyzing even fine pores smaller than the limit by the BET method by using an image through a transmission electron microscope, thereby investigating the relationship between capacity density and specific surface area as to various kinds of active carbon for electrodes different in specific surface area. As a result, the conclusion that there is no linear proportional relationship between them, and so factors affecting the capacity exist in some others was reached.
The present inventors carried out a further investigation on the basis of this finding. As a result, it was found that in the above electrolytic solution, the organic solvent is solvated with ions of an electrolyte such as the tetraalkylammonium salt or the like to form electrolytic solution ions, and so many pores having a pore size suitable for adsorption of the electrolytic solution ions are formed in active carbon, thereby providing active carbon excellent in capacity density per volume.
Based on this finding, the reason why in the active carbon described in Japanese Patent Application Laid-Open No. 302735/1995, the capacity density per volume is lowered when the activation is performed until the capacity is developed is considered. The active carbon is such that the carbonaceous material is subjected to the activation, thereby forming pores suitable for adsorption of the electrolytic solution ions. However, it is considered that the pore size distribution of pores formed by such activation widely ranges from a small size to a large size. As a result, it is considered that the number of pores having a pore size suitable for the adsorption of the electrolytic solution ions relatively decreases in such active carbon, in other words, the number of pores noncontributory to capacity increases, so that a sufficient capacity density per volume cannot be obtained.
Further, the present inventors found active carbon suitable for use in electrodes for an electric double layer capacitor, in which the pore size suitable for the adsorption of the electrolytic solution ions takes a mode in its pore size distribution, on the basis of the above finding. Such active carbon was previously applied for patent (Japanese Patent Application No. 46912/1996). The active carbon described in the above specification is such that a carbonized product obtained by calcining a vinyl chloride resin is activated with an alkali at a temperature ranging from 400.degree. to 1,000.degree. C. The mode in its pore size distribution is within a range of 10-20 angstroms, which are pore sizes suitable for adsorption of the electrolytic solution ions. According to such active carbon, a polarizable electrode high in electrode density and capacity density per volume can be formed because the mode in its pore size distribution falls within the above range. In particular, when the alkali activation is performed for 15-20 hours at the temperature within the above range, the capacity density per volume becomes a maximum value.
Incidentally, the mode in the above specification means a value of a pore size which shows the highest relative frequency in the frequency distribution of pore sizes, which is found from a power spectrum obtained by converting the image of the active carbon through a transmission electron microscope into a binary image and subjecting this binary image to Fourier transformation.
According to such active carbon, a polarizable electrode high in capacity density per volume can be constructed, and an electric double layer capacitor high in energy density can hence be constructed by such polarizable electrodes. However, there is a demand for development of active carbon more improved.

Active carbon used for electrode for organic solvent type electric double layer capacitor


A first beacon slot is selected by a wireless communications device in a repeating time interval. Accordingly, beacons of the wireless communications device are transmitted during the first beacon slot. However, when an announcement of the first beacon slot selection of step is not received from a remote device within a predetermined amount of time, a second beacon slot is selected. Upon this selection, beacons of the wireless communications device are transmitted during the second beacon slot instead of the first beacon slot.

Short-range wireless proximity networks typically involve devices that have a communications range of one hundred meters or less. To provide communications over long distances, these proximity networks often interface with other networks. For example, short-range networks may interface with cellular networks, wireline telecommunications networks, and the Internet.
A high rate physical layer (PHY) standard is currently being selected for IEEE 802.15.3a. The existing IEEE 802.15.3 media access control layer (MAC) is supposed to be used as much as possible with the selected PHY. Currently, there are two remaining PHY candidates. One of these candidates is based on frequency hopping application of orthogonal frequency division multiplexing (OFDM). The other candidate is based on M-ary Binary offset Keying. The OFDM proposal is called Multiband OFDM (MBO). Moreover, in order to further develop the OFDM proposal outside of the IEEE, a new alliance has been formed called the MultiBand OFDM Alliance (MBOA).
MBO utilizes OFDM modulation and frequency hopping. MBO frequency hopping may involve the transmission of each of the OFDM symbols at various frequencies according to pre-defined codes, such as Time Frequency Codes (TFCs). Time Frequency Codes can be used to spread interleaved information bits across a larger frequency band.
Presently, there is an interest within the MBOA to create a Medium Access Control (MAC) layer that would be used with the OFDM physical layer instead of the IEEE 802.15.3 MAC layer. A current version of the MBOA MAC involves a group of wireless communications devices (referred to as a beaconing group) that are capable of communicating with each other. The timing of beaconing groups is based on a repeating pattern of "superframes" in which the devices may be allocated communications resources.
MAC layers govern the exchange among devices of transmissions called frames. A MAC frame may have various portions. Examples of such portions include frame headers and frame bodies. A frame body includes a payload containing data associated with higher protocol layers, such as user applications. Examples of such user applications include web browsers, e-mail applications, messaging applications, and the like.
In addition, MAC layers govern the allocation of resources. For instance, each device requires an allocated portion of the available communication bandwidth to transmit frames. The current MBOA MAC proposal provides for the allocation of resources to be performed through communications referred to as beacons. Beacons are transmissions that devices use to convey non-payload information. Each device in a beaconing group is assigned a portion of bandwidth to transmit beacons.
Such transmissions allow the MBOA MAC to operate according to a distributed control approach, in which multiple devices share MAC layer responsibilities. Accordingly, the current MBOA MAC Specification (version 0.95, Apr. 11, 2005) provides various channel access mechanisms that allow devices to allocate portions of the transmission medium for communications traffic. These mechanisms include a protocol called the distributed reservation protocol (DRP), and a protocol called prioritized contention access (PCA).
This distributed control approach allows for devices a certain degree of autonomy in joining MBOA networks. While this may be efficient in certain circumstances, it may cause contention and inaccessibility in certain high demand scenarios. Accordingly, an improvement to the existing solution is needed.

Reducing beacon slot acquisition time in distributed media access control network


Various aspects described herein are directed to different techniques for enabling ad server systems to dynamically determine minimum floor prices for individual incoming impressions, in which the determination of the minimum floor value for a given incoming impression may be based upon the value(s) of specifically identified impression parameters associated with that particular impression. Additional aspects are directed to various feedback techniques for measuring the effectiveness of the various Entity-based and/or Segment-based floors, and for dynamically adjusting various floor computation parameter values based on measured floor metrics and heuristics.

The present disclosure relates to online advertising techniques and, more particularly, relates to segment-based floors for use in online ad auctioning techniques.
A significant quantity of content published on the Internet is supported by advertisements ("ads"). Publishers of Internet-based content often make use of a robust infrastructure of Advertising Networks and/or exchanges that handles the selection, placement, and insertion of ads in web pages. These Advertising Networks and/or exchanges generally select from a set of available ads, based on various factors such as geographic location, subject matter, and the like, in an effort to present ads that are most likely to be maximize revenue in a given context. Advertisers pay the Advertising Networks and/or exchanges for ad exposures based on, among other factors, expected or actual performance of the ad determined, for example, by counting the number of times users click on the ad. Accordingly, revenue can be increased by placing ads to maximize response and effectiveness.
As the online advertising industry continues to grow, the amount of control that publishers (entities who have an inventory of advertising space to sell) want with respect to selling this ad space inventory also grows. As a result, there is an increasing desire among publishers to carve out specific inventory buckets for their ad space inventory. On the advertiser side, advertisers are now increasingly particular about how much they will pay to place their ads on Web pages.
Various mechanisms for measuring performance and effectiveness of advertisements are available. One well-known measurement of ad performance is effective cost per mille (e-CPM), which indicates a cost (or price) of showing an ad one thousand times. e-CPM is therefore a measurement of revenue that a publisher can expect to receive from an Advertising Network based on the number of impressions, or page views, of the content, e-CPM is often determined on an estimated basis. Revenue for an Internet publisher is maximized when an advertisement having high e-CPM is shown. Higher e-CPM means that an Advertising Network is willing to pay more because of an expectation that an ad will be more effective.
It would be desirable to provide publishers with greater level of control in determining which ads are served to them for display based on a variety of demographic and other categories. Overall this would also be desirable for the advertisers and entities providing services to advertisers. Advertisers would like to be able to target a specific audience and have the flexibility of paying more or less for a given ad segment depending on who will see the ad.

Segment-based floors for use in online ad auctioning techniques


A process for preparing liquid personal cleansing compositions which provides enhanced perfume deposition on the skin and which provides increased on-skin fragrance longevity. The liquid personal cleansing compositions contain from about 0.01% to about 5% of a cationic polymer; from about 1% to about 80% of an anionic surfactant; from about 0.01% to about 5% of a volatile perfume; and water. The ratio of the cationic polymer to the anionic surfactant ranges from about 1:100 to about 1:2. The process involves first forming a premix comprising the cationic polymer, the volatile perfume and water, and then adding the premix to a personal cleansing base composition which comprises anionic surfactant and water.

Perfumes and fragrances are typically added to personal cleansing compositions to provide a fresh, clean impression for the compositions. Many consumers would prefer for the perfumes present in the compositions to deposit on their skin and to remain there for an extended period of time to convey a lasting impression of freshness. However, due to the volatility of many perfumes, it can be difficult to deliver this benefit to consumers.
Cationic deposition polymers have been used in the past to enhance deposition of certain nonvolatile components from shampoos and other personal cleansing compositions. For example, U.S. Pat. Nos. 5,037,818 and 5,085,857 describe the use of cationic guar gum to enhance the deposition of antidandruff particles and insoluble nonvolatile silicone respectively. Deposition polymers have also been proposed to enhance the deposition of sunscreen materials from a shampoo composition. In EP 386 898 a cationic polygalactomannan gum derivative is used. WO 95/22311 describes the use of certain cationic polymers to increase the deposition of nonvolatile benefit agents which include silicones, fats and oils, waxes, hydrocarbons, fatty acids and fatty alcohols, lipids, vitamins and sunscreens.
It would be desirable, however, to increase the deposition of volatile ingredients, such as perfumes, and to provide increased on-skin longevity with respect to these ingredients. This benefit is provided by the present invention.

Process for preparing liquid personal cleansing compositions which provide enhanced perfume deposition


A camera head unit including an image sensor configured to generate an image signal, a main unit configured to perform a signal process to the image signal, and first and second cables are included. Further, a determining section configured to determine whether a connection state is in a first connection state in which the camera head unit and the main unit are connected with each other via a first cable without a second cable or a second connection state in which the camera head unit and the main unit are connected with each other via the first cable and the second cable, and a transmission section configured to transmit the image signal between the camera head unit and the main unit at least via the first cable according to a determination result determined by the determining section are included.

As disclosed in Patent Document 1 listed below, a camera system has been known, which is configured to capture an image with such a camera that a camera head unit including an image sensor (camera head unit) and a main unit of the camera are detached from each other but connected via a cable.


An article supporting device includes a tray for receiving articles to be supported by the device, an arm having one end secured to one side of the tray and extending longitudinally of the tray at the one side thereof; and a crossbar connected at one end to the opposite end of the arm. The crossbar extends substantially perpendicularly to the arm across the width of the tray with the opposite end of the crossbar spaced from the opposite side of the tray to define a space for the application of the device to the body of a person, thereby enabling the person to support the tray by the person's body alone and without the use of the person's hands.

The present invention relates to article supporting devices, and particularly to such devices for use as a body-supported tray.
Situations frequently arise wherein a person is required to carry articles on a tray but cannot hold the tray by the person's hands. One such situation is a person requiring crutches for moving around, the person's hands being engaged in gripping the crutches and therefore unavailable for holding a tray.

Article supporting device for use as body-supported tray assembly


In the semiconductor laser including a diffraction grating in which a first diffraction grating region with a first pitch, a second diffraction grating region with a second pitch and a third diffraction grating region with the first pitch, an anti-reflection film coated on an end facet to the light-emitting side, and a reflection film coated on an opposite end facet, the first diffraction grating region is greater than the third diffraction grating region, and the second diffraction grating region is formed, in such a manner that phases of the first and third diffraction grating regions are shifted in a range of equal to or more than 0.6 π to equal to or less than 0.9 π, phases are successive on a boundary between the first and second diffraction grating regions and the phases are successive on a boundary between the second and third diffraction grating regions.

1. Field of the Invention
The present invention relates to a semiconductor laser and an optical semiconductor device using the semiconductor laser and particularly to improvements in frequency characteristics and in fabrication yield of a semiconductor laser that has diffraction grating.
2. Description of the Related Art
At present, a higher transmission speed of an optical semiconductor device is desired. For example, a semiconductor laser for a wavelength-division multiplexing method is used in the optical semiconductor device using a communication light source for optical fiber communication to realize a transmission speed of 100 Gb/s that has become recently standardized. The optical semiconductor device includes a 4 channel semiconductor laser that is driven at the transmission speed of 25 Gb/s or 28 Gb/s per one channel, outputs light of different wavelengths, and realizes high capacity transmission. At present, an electroabsorption-modulated DFB-laser is used as the semiconductor laser that has the transmission speed of 25 to equal to or more than 28 Gb/s. For the optical semiconductor device, an optical transmitter and receiver using the laser element as a transmission light source has been in practical use. However, for the perspective of high-density integration into a high-speed router, there is a high demand for smaller size, lower power consumption, and lower cost in an optical communication transmitter and receiver with the speed of 100 Gb/s. Because a directly modulated laser element is simple in structure and thus is simple in implementation if high-speed operation of the directly modulated laser element can be realized, it is expected smaller size, lower power consumption, lower cost, and the like in the optical semiconductor device can be realized. In the transmission at the transmission speed of 10 Gb/s over a short distance of equal to or less than 10 km, the directly modulated laser element is already in practical use. The directly modulated laser element is a distributed feedback (hereinafter referred to as the DFB) laser element in which the structure of a cavity is DFB that oscillates with a single wavelength in a manner that makes the transmission over the distance of 10 km possible. For example, it is considered that the DFB laser element is also used in the directly modulated laser element with the high transmission speed of 25 to 28 Gb/s. Moreover, for example, a directly modulated semiconductor laser still on the drawing board, as the directly modulated laser element with the higher transmission speed, which is driven at the speed of 25 Gb/s or 28 Gb/s, is disclosed in "G. Sakiano, et al, '25.8 Gbps Direct Modulation AlGaInAs DFB Lasers with Ru-doped InP Buried Heterostructure for 70° C. operation,' OFC/NFOEC 2012 Technical Digest, OTh3F.3, 2012."
The DFB laser element has a structure in which diffraction grating is formed along an optical axis direction inside the element. Because oscillation occurs with two wavelengths in principle in the uniform diffraction grating structure, a contrivance is provided that oscillates in a single mode in a semiconductor laser with the diffraction grating. As one technology relating to the contrivance, there is a quarter-wave phase shifted (λ/4-shifted) diffraction grating structure. Furthermore, a dielectric film is coated on each of both facets of the semiconductor laser. The dielectric film in which light reflectivity on the end facet is low reflectivity is an anti-reflection film (a low reflection film) and the dielectric film in which the light reflectivity on the end facet is high reflectivity is a reflection film (a high reflection film). The semiconductor laser that has λ/4-shifteded diffraction grating structure is disclosed in JP 62-95886 A, JP 61-216383 A, JP 61-47685 A, and JP 2000-286502 A. In the semiconductor laser disclosed in the patent documents, an improvement in characteristics is made by combining an arrangement of a shift position of the λ/4-shift in the diffraction grating and a selection of dielectric films coated on the both facets of the semiconductor laser.
The semiconductor laser that has the λ/4-shifted diffraction grating structure has a problem in that the single mode cannot be maintained at the time of high optical output because optical intensity is localized in the shift position of the λ/4-shift. Therefore, the semiconductor laser that has a corrugation-pitch-modulated (CPM) diffraction grating structure as a structure for reducing the localization of the light intensity is disclosed in "Makoto Okai, 'Spectral characteristics of distributed feedback semiconductor lasers and their improvements by corrugation-pitch-modulated structure,' Journal of Applied Physics, Vol. 75, No. 1, pp. 1-29, 1994." In the semiconductor laser that has the CPM diffraction grating structure, the diffraction grating has a diffraction grating region for phase shift, and λ/4-shift is spatially made in the diffraction grating region in a gradual manner.

Semiconductor laser and optical semiconductor device