A mirror having low density, low CTE, high thermal conductivity, high elastic modulus, and a reflective, polishable surface. The instant mirror features a silicon-based metal coating as the reflective surface, and a composite body as a support or substrate for the reflecting surface. The composite body features carbon fibers reinforcing a matrix containing silicon metal and optionally some silicon carbide. The metal coating can be elemental silicon metal, possibly in amorphous form, and can be applied by a vapor deposition process such as chemical vapor deposition (e.g., plasma enhanced CVD) or physical vapor deposition such as evaporation or electron beam PVD.

1. Field of the Invention
The present invention relates to articles made from metal-ceramic composite materials featuring a particular kind of fibrous reinforcement. In particular, the invention relates to metal-ceramic composite mirrors having low thermal expansion coefficient.
2. Discussion of Related Art
Light-weight mirrors and structures are required in many government as well as commercial systems, including space systems. There are some very specific property demands on the materials used for construction of these mirrors and structures. These include lightweight, high stiffness, low to zero coefficient of thermal expansion (CTE), high thermal conductivity, polishability and adequate strength and toughness. Traditionally, low or ultra low expansion glasses and glass ceramics have been used along with metallic coatings for mirror constructions. However, there are several disadvantages of glasses such as low specific stiffness, low toughness, etc. Recently, beryllium, silicon carbide, and carbon fiber/polymer composites have been proposed for this application. However, each of these has its own limitations such as toxicity, non-zero expansion (Be); shape making difficulty, non-zero expansion (SiC); and environmental instability and low thermal conductivity (Cf/polymer). The only way to achieve zero-CTE in a composite requires use of negative CTE reinforcement, such as ultra high modulus carbon fibers as a reinforcement.
It has been known for a long time to add fibrous reinforcement to metals to increase mechanical properties such as specific strength and specific stiffness. One of the early such reinforcements was carbon or graphite fiber, produced from polymer precursors. The resulting composite material offered double or triple the strength or stiffness compared to the bulk, unreinforced metal. Processing was difficult, however, as the metals either tended not to wet the carbon fibers, or reacted with the carbon. Considerable energy has been devoted to developing ways to preserve the chemical and physical integrity of the fibers while rendering them more chemically compatible with the metal matrix.
Carbon fibers can be manufactured with high degrees of anisotropy. The graphite form of carbon in particular features a hexagonal crystallographic structure, with the covalent bonds within the {001} planes being strong, and the bonds between the {001} planes consisting of weak van der Waals bonds. It is possible to preferentially align the crystallographic planes in a graphite fiber such that the {001} planes tend to be parallel to the graphite fiber axis. By increasing the relative amount of covalent bonds in the fiber axis direction, a fiber possessing high strength and high elastic modulus in the direction of the fiber axis is produced. An interesting and unusual phenomenon that accompanies the alignment of the high strength, high modulus direction is that this particular direction also possesses a negative CTE. Thus, instead of expanding upon heating like most materials, these fibers actually shrink in the axial direction. In the radial direction of such fibers, however, the strength and elastic moduli are relatively low and the CTE is positive and relatively high.
When a reinforcement material having a negative CTE is incorporated into a composite material whose matrix component has a positive CTE, the individual CTE's tend to offset or cancel one another, yielding a composite or overall CTE somewhere between the two values. Because of this counterbalancing or offset effect, it is theoretically possible to engineer a metal matrix composite material, such as a metal-ceramic composite material, to have a net overall CTE of zero. By incorporating parallel arrays of such fibers into a positive CTE isotropic matrix, a composite material having a high modulus and a zero or near-zero CTE in the axial direction of the fibers can be produced. In the direction transverse to the fiber axes, the modulus would be relatively low and the CTE would be relatively high. Because of the axial stiffness, the properties of the composites tend to be dominated by the axial properties.
The degree of anisotropy can be reduced by distributing the fiber orientations. One technique for accomplishing this is to arrange the fibers in parallel within a thin sheet or "ply", and to place a number of such plies on top of one another such that fibers in one ply are skew with respect to fibers in an adjacent ply. With suitable arrangements of the plies it is possible to produce quasi-isotropic sheet materials. Quasi-isotropic lay-ups of thin plies of the composite can be achieved by orienting successive plies at 0°, +45°, −45° and 90°; or 0°, +60° and 60° with respect to the fiber axes. The distribution of the fiber directions, however, significantly reduces the CTE influence of the fibers (as will be illustrated later); thus, it becomes that much more difficult to produce composites that have zero or near-zero CTE's in the dominant plane of the composite.
U.S. Pat. No. 3,807,996 to Sara teaches a carbon fiber reinforced nickel matrix composite material. Sara discloses the use of high strength, high modulus carbon fibers, as well as various geometrical arrangements of the fibers, such as arrays (plates) of parallel fibers and cross-plies (laminates) of such arrays.
U.S. Pat. No. 4,083,719 to Arakawa discloses a carbon fiber reinforced copper composite featuring a low thermal expansion coefficient and no directional characteristic of the mechanical properties. The resulting composite bodies featured CTE as low as 4×10−6 cm/cm per degree K (hereinafter referred to as "parts per million per degree Kelvin" or ppm/K).
U.S. Pat. No. 4,157,409 to Levitt et al. discloses treating carbon fibers with molten NaK to permit wetting by molten aluminum, magnesium, copper, zinc, tin or lead matrix metals.
U.S. Pat. No. 5,834,115 to Weeks, Jr. et al. discloses protecting carbonaceous reinforcement materials such as fibers with molybdenum carbide and then infiltrating with a molten metal to produce a composite body. A woven fabric of coated graphite fibers reinforcing a copper matrix exhibited a CTE between about 4 and 7 ppm/K).
High modulus carbon fibers have also been incorporated into polymeric matrices. U.S. Pat. No. 5,330,807 to Williams discloses a composite laminated tubing intended for offshore oil extraction operations. There the problem was the need to transfer oil in a tube over appreciable distances and in which the tube may undergo considerable temperature excursions due to the elevated temperature of the extracted oil. To minimize the expansion of the tube length and thereby ameliorate the propensity for the tube to fail by buckling, the tubing is made of a plurality of layers of fibers fixed in a plastic matrix. The fibers may be graphite fibers, glass fibers, ceramic fibers or polymer fibers, but in any case the fibers have a sufficiently low CTE as to impart to the tubing an overall CTE of no more than about 1.1 ppm/K, and a Poisson's ratio near 0.5.
In many environments, however, polymer matrix composites cannot be used because of insufficient resistance to extremes of temperature, corrosion or radiation. Accordingly, some workers have used glass as the matrix material. Glass has several attractive properties for these types of materials, including fluidity or flowability, wettability to the fibers and the potential for relatively low CTE's. For a laser mirror application, for example, Stalcup et al. (U.S. Pat. No. 4,451,118) hot pressed a mixture of a low expansion borosilicate glass and alternating plies of high modulus graphite fibers. Some of the graphite fibers were arranged perpendicular to the reflecting surface so as to be better able to conduct heat away from the mirror surface. Still, cooling passages had to be placed into the mirror structure to permit circulation of a heat exchange fluid.
Similarly, in U.S. Pat. No. 4,791,076 Leggett et al. discloses a graphite fiber silica matrix composite composition having a near-zero overall CTE. In addition to silica, the matrix contains boron phosphate and beta-spodumene, and Leggett states that the composite CTE is tailorable between −1 and +1 ppm/K by varying the matrix composition. As a consequence of the low CTE, very little thermal distortion occurred in for example, a laser mirror application, particularly at low coolant flow rates. This glass matrix composite material exhibited much less thermal distortion than did other laser mirror materials such as single crystal molybdenum or silicon. Although the cooling requirements were reduced, active cooling techniques involving heat transfer media flowing through channels in the mirror still were required.
As mentioned above, glass matrix composites have been used in environments where low expansion polymer composites would be insufficiently durable. Many of these applications, however, require high thermal conductivity, and most glasses are deficient in this area. Thus, composites workers have attempted to address the thermal conductivity problem by relying on the carbon fibers to carry this responsibility, the carbon fibers possessing relatively high thermal conductivity in the fiber axis direction. Another problem with glass matrix composites, though, is that they tend to be brittle. In many applications in which such composites are subjected to accelerations and stresses, such as with semiconductor fabrication equipment, it would be preferable to have a tougher, more impact resistant material.
A number of metals such as aluminum and magnesium are intrinsically highly thermally conductive and tough, and possessing low specific gravity and sufficient durability in harsh environments as to make them candidates for aerospace or precision equipment applications. Unfortunately, these metals suffer from having relatively high CTE's—typically around 20 ppm/K or higher. There seem to be no successes or even proposals to make composites using these high modulus carbon fibers as the reinforcement of a light metallic matrix for the express purpose of producing very low CTE metal matrix composites. The lowest CTE achieved for such MMC's appears to be the 4 ppm/K of U.S. Pat. No. 4,083,719, which represents work done years ago. While quite low in comparison to unreinforced metals, there are applications, such as in optical systems that undergo temperature fluctuations, where even lower CTE's would be desirable.
The CTE of the composite body is also influenced by the elastic modulus of the individual composite constituents. More specifically, Equation 1 shows the mathematical relationship among CTE, elastic modulus, and volume fraction.
            Equation                                      1        :                            α      11        =                    V        ·                  E                      11                        f                          ·                  α                      1                        f                              +                        (                      1            -            V                    )                                              E            m                    ·                      α            m                                              V        ·                  E                      11                        f                              +                        (                      1            -            V                    )                ·                  E          m                    where:
V is the volume fraction of fibers;
Em is the elastic modulus of the matrix;
E11f is the elastic modulus of the fibers in the axial direction;
α1f is the CTE of the fibers in the axial direction;
αm is the CTE of the matrix; and
α11 is the CTE of the composite body in the fiber axial direction.
Obviously, the larger the contributing CTE's of reinforcement and matrix, the larger the overall CTE of the composite. As Equation 1 also demonstrates, however, the CTE of the composite is related to the elastic moduli of the matrix and reinforcement phases. Moreover, this equation shows that reducing the modulus of the matrix relative to the modulus of the reinforcement reduces the CTE contribution of the matrix to the overall composite CTE, therefore causing the composite CTE to trend toward the CTE of the reinforcement. For reinforcement materials possessing negative CTE such as certain high modulus carbon fibers (at least in the axial direction), the averaging of the matrix and reinforcement CTE's to yield the CTE of the composite tends to produce a CTE "cancellation". Thus, it is at least theoretically possible with a proper balancing of CTE's to engineer the overall CTE of the composite to be zero.
One must bear in mind, though, that the situation described immediately above represents the case in which the fibers are aligned. Such a composite would be highly anisotropic, and the composite CTE would be zero or near-zero only in the direction parallel to the fiber axes. In other directions, the overall CTE of the composite body would be non-zero and positive.
Over the years, there has been a significant amount of work directed to reinforcing SiC composites, e.g., reaction-bonded SiC composites, with carbon fibers. See, for example, U.S. Pat. Nos. 4,118,894; 4,944,904 and 6,248,269. None of these patent documents expressly state low CTE as an objective; however, because the matrices of these composite materials consist of low CTE substances, i.e., SiC, typically interconnected, and typically also some residual, unreacted Si, also typically interconnected, the resulting composite bodies are expected to inherently feature a low CTE, e.g., on the order of about 2.6–2.8 ppm/K for Si/SiC composites. For example, U.S. Pat. No. 6,248,269 to Dietrich et al. discloses a reaction-bonded SiC composite suitable for braking applications, e.g., disk and pad, for motor vehicles, consisting of carbon fibers arranged isotropically and embedded in a matrix of 40–50 volume percent SiC and not more than 15 volume percent Si. The carbon fibers are protected from chemical reaction with the Si infiltrant by infiltrating a pitch resin into the mass of fibers prior to the Si infiltration step.
U.S. Pat. No. 4,944,904 to Singh et al. discloses a similar composite material system intended mostly for high temperature, aerospace applications, such as a turbine engine component, but also mentioning applications such as wear parts and acoustic parts. The matrix comprises at least 5 volume percent SiC but preferably at least 45 percent, and 1–30 volume percent Si but preferably 1–2 percent. The fibers may be carbon or SiC, but are not disclosed as being arranged isotropically or quasi-isotropically. The fibers similarly are protected from attack by the molten silicon, but here, the protective coating consists of boron nitride plus an overcoat of a silicon-wettable material such as carbon or metal carbides such as SiC. The BN also provides a debond layer so that the fibers can move relative to the matrix under mechanical loading, thereby providing a toughening aspect to the resulting composite body. Again, low CTE does not appear to be an express objective of either of these reaction-bonded SiC composite patents; however, the formed composites are expected to inherently possess a low CTE, as most of the constituents are low CTE materials.
Ealey et al. applied RBSC technology to the problem of fabricating a mirror requiring low CTE, high thermal conductivity, high elastic modulus and low density ("CERAFORM SiC: roadmap to 2 meters and 2 Kg/m2 areal density", Advanced Materials for Optics and Precision Structures, SPIE Critical Reviews, Vol. CR67, pp. 53–70, ISBN 0-8194-2598-2, September 1997). Normally, it is difficult to obtain a smooth polish of a reaction-bonded SiC surface because the silicon phase tends to be removed at a much faster rate than does the SiC phase; however, Ealey at al. claim to have overcome this problem through careful control of the polishing conditions, particularly of the pH of the polishing slurry. They report a CTE for their CERAFORM SiC of about 2.44 ppm/K. Although such a CTE generally is considered to be low, there are applications that desire still lower CTE, or even zero CTE, if possible. Further, a key requirement of reaction-bonded SiC mirrors is polishability. Even if the SiC and Si phases can be polished at the same rate, they report that the polish rate is only ⅓ to ½ that of glass. Further, they have experimented with polishing amorphous Si coatings applied to CERAFORM SiC by a vapor deposition process.

Low CTE metal-ceramic composite articles, and methods for making same


A surface acoustic wave device includes a piezoelectric substrate and interdigital electrodes disposed on the piezoelectric substrate, wherein each of the interdigital electrodes includes a main electrode layer made of Cu or an alloy that has Cu as its main component. The surface acoustic wave device also includes a tightly adhering layer which is disposed between the main electrode layer and the piezoelectric substrate and whose main component is NiCr, or a tightly adhering layer whose main component is Ti and whose film thickness is within a range of about 18 nm to about 60 nm.

1. Field of the Invention
The present invention relates to a surface acoustic wave device for use, for example, as a resonator, a filter, or other such device, and more specifically, relates to a surface acoustic wave device in which interdigital electrodes are constructed using Cu as the main material.
2. Description of the Related Art
Surface acoustic wave devices are electronic components utilizing surface acoustic waves propagated by mechanical vibration energy being concentrated only in the vicinity of a solid surface. A surface acoustic wave device generally has a piezoelectric substrate and interdigital electrodes disposed on the piezoelectric substrate, and is used as a filter or a resonator.
Al or an Al-type alloy using Al as the main component, which is low in electrical resistivity and low in specific gravity, has generally been used as the material constituting the electrodes in a surface acoustic wave device. However, with electrodes made of Al or an Al-type alloy, short-circuiting of electrodes is caused due to stress migration, and insertion loss tends to increase. Furthermore, the power resistance is not sufficient, either.
For the purposes of the following discussion, Patent Reference 1 is Japanese Patent Application Kokai No. H9-98043, Patent Reference 2 is Japanese Patent Application Kokai No. H9-199976, and Patent Reference 3 is Japanese Patent Application Kokai No. 2002-26685.
The use of Cu as the electrode material in a surface acoustic wave device is proposed in Patent References 1 through 3 listed below. Specifically, in the surface acoustic wave device described in Patent Reference 1, interdigitated electrodes are constructed from copper or a copper alloy whose main component is copper.
Furthermore, electrodes for the surface acoustic wave element described in Patent Reference 2 are constructed from an alloy having the composition CuxMy. Here, x and y are values expressed by weight percentage, and the metal M is a metal selected from among Zn, Ni, Sn, Al, Mg, and other suitable metals. It is indicated that a Cu alloy including Zn, Ni, Sn, Al, Mg, or other suitable metal is used to achieve an improvement in electrode oxidation resistance.
In addition, it is disclosed in Patent Reference 2 that the electrode oxidation resistance is further increased by forming an inorganic protective layer such as SiON, SiO2, and Al2O3 on the electrodes made of a Cu alloy.
In the surface acoustic wave element described in Patent Reference 3, on the other hand, a first electrode layer composed of Ti or a Ti alloy with a thickness of 10 nm is disposed on the piezoelectric substrate, a second electrode layer composed of Cu or a Cu alloy is disposed on the first electrode layer, and a third electrode layer disposed of Al, an alloy whose main component is Al, Au, or an alloy whose main component is Au is arranged so as to cover the second electrode layer. It is indicated that the provision of a first electrode layer composed of Ti or a Ti alloy makes it possible to increase the adhesion between the piezoelectric substrate and electrodes, and the formation of a third electrode layer makes it possible to increase the oxidation resistance in the surface acoustic wave device described in Patent Reference 3.
Electrodes composed of Cu have the problem of insufficient adhesion to the piezoelectric substrate. Furthermore, because Cu is susceptible to oxidation, the electrodes composed of Cu also have the problem of insufficient oxidation resistance.
In view of this, a protective film consisting of an inorganic insulating material such as SiON and SiO2 is disposed on the electrodes in the surface acoustic wave device described in above-mentioned Patent Reference 2, in order to increase oxidation resistance. Furthermore, an alloy of Cu with an element such as Zn, Ni, and Sn is used in the method described in Patent Reference 2.
Meanwhile, with the recent trend toward higher frequencies in communication devices, an increasingly higher power resistance has been required particularly in filters and splitters used on the transmission side of communication devices. Accordingly, a higher adhesion between the electrodes and piezoelectric substrate has been strongly desired.
In the surface acoustic wave devices described in Patent References 1 and 2, the adhesion of the electrodes to the piezoelectric substrate is insufficient, so that it is difficult to achieve an improvement in power resistance.
In the surface acoustic wave element described in Patent Reference 3, furthermore, although the adhesion between the piezoelectric substrate and the electrodes is increased by the formation of the first electrode layer consisting of Ti or a Ti alloy having a thickness of about 10 nm, an adequate power resistance could not be obtained even with such a structure.


The present invention is to solve the problems caused in various methods used to improve the performance of the device by improvement of conventional base layer. The present invention discloses a hot electron device which can improve the performance of the device such as the improvement in the current density and decrease in transition time by reducing the dispersion phenomenon by introducing indium arsenide layer having v-shape conduction band due to the graded composition as the base layer of hetero structure hot electron device (HET).. In addition, the present invention discloses a resonant tunneling hot electron device which is constructed by adding an emitter electron projection layer to the hot electron device of the present invention so that the Fermi energy and alignment can occur due to the stark shift and the projection of hot electron to the base region can occur through the Fermi energy and alignment.

1. Field of the Invention
The present invention relates to a hot electron device (HET), and particularly to a hot electron device in which an indium arsenide (InAs) epitaxlal layer which has high electron mobility due to small effective electron mass is specially formed as a base layer material in a hetero structure hot electron device.
The present invention also relates to a resonant tunneling hot electron device which induces a resonant tunneling by adding an emitter electron projection layer to the hot electron device.
For several years, developments of semiconductor devices using the heterostructure have been vigorous' as the semiconductor growth technology such as the molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD) has been developed. Among the devices, the hot electron device using very short and quick transition time of hot electron in the base region has been given a great interest and the research thereof have been under progress. In case of using an indium arsenide having high electron mobility as the base material, the electron transition time is further improved so that the performance of the device is improved.
The conventional techniques that improve the electrical characteristics of the base layer are as follows:
1) n-GaAs (emitter) /i-AlGaAs (emitter barrier layer) /n-GaAs (base) /i-AlGaAs (collector barrier layer) /n-GaAs (collector) /GaAs (substrate);
2) n-GaAs (emitter) /i-AlGaAs (emitter barrier layer) /n-InGaAs (base) /i-AlGaAs(collector barrier layer) /n-GaAs (collector) /GaAs (substrate);
3) n-InGaAs (emitter) /i-InAlAs (emitter barrier layer) /n-InGaAs (base) i-InAlAs (collector barrier layer) /n-InGaAs (collector) /InP (substrate);
4) n-AlSbAs (emitter) /n-InAs (base) /i-GaSb (collector barrier layer) /n-GaSb (collector) /GaSb (substrate).
Classifying the hot electron device according to the technique which can improve the performance of the device due to the improvement of the base layer, the device can be classified into a gallium arsenide based (GaAs-based) ,indium phosphide based (InP-based) and gallium antimonide based (GaSb) series. In case of GaAs-based series hot electron device, a doped gallium arsenide layer is used as an emitter, base and collector layers. An aluminum gallium arsenide (Al.sub.x Ga.sub.1-x As), x=0.3-1.0, is used as an emitter barrier layer between the emitter layer and base layer and as a collector barrier layer between the base layer and collector layer. In case of using a doped gallium arsenide layer as the base layer, the ratio of current that can move from the emitter to collector is small so as to lower the height of the collector barrier layer so that the collector current gain is raised. However, as the height of the collector barrier layer is lowered, the collector-base voltage V.sub.CB with which the operation of device is possible without leak current of collector layer is lowered. Therefore, high electron mobility indium gallium arsenide (In.sub.x Ga.sub.1-x As), x=0.53-0.8, is introduced as the base layer to improve the electrical characteristics. In this case, .GAMMA.-L separation is large so that dispersion of electrons due to L valley is reduced and the conduction band discontinuity with collector barrier layer is increased thereby reducing the content of aluminum arsenide AlAs of collector barrier layer and raising the collector-base voltage V.sub.CB. An indium gallium arsenide (In.sub.x Ga.sub.1-x As) base layer of indium composition of 0.53 to 0.8 is lattice mismatched with gallium arsenide layer. The lattice mismatch causes strain and crystal defects in the lattice thereby raising device operation voltage. To solve this problem, it is necessary to reduce the thickness and doping concentration of base layer, or to lower the height of collector barrier layer. However, as the doping concentration of base is reduced, scattering within the base layer reduces and current gain increases, resulting in increase in device ohmic resistance. It is known that, in general, an indium arsenide layer can lower base resistance and raise current gain at the same doping concentration compared with indium gallium arsenide (In.sub.x Ga.sub.1-x As), x=0.53-0.8. For example, ohmic resistance can be improved by lowering the height of Schottky barrier layer by introducing an indium arsenide layer at the surface. However, about 7% lattice mismatch exists between a gallium arsenide layer with a 5.6532 .ANG. lattic constant and an indium arsenide layer with a 6.0583 .ANG. lattice constant. The critical thickness which can grow due to the lattice mismatch exists, and the degradation of electrical characteristics occurs became of misfit dislocations, stacking faults, etc., at the grown epitaxial layer. Because of such problems, the indium phosphide material family is used wherein an InP substrates can accomplish lattice match.
In case of indium phosphide series hot electron device, doped indium gallium arsenide (InGaAs) is used as emitter, base and collector layers. An indium alluminium gallium arsenide (InAlGaAs) layer of a variety of aluminum composition is used as the emitter barrier layer between the emitter layer and base layer and as the collector barrier layer between the base layer and collector layer. Also in this case, since indium arsenide material having high electron mobility is applied, about 4% lattice mismatch exists between the indium phosphide layer with 5.8687 .ANG. lattice constant and indium arsenide layer with 6.0583 .ANG. lattice constant. There are various problems regarding critical thickness which can grow without crystal defects from lattice mismatch and the strain in an epitaxial layer. When growing the epitaxial layer, there is no problem if the layer is grown within its critical thickness, and electron transition time can be improved by reducing base layer resistance. This is accomplished base layer by reducing thickness, however, a significant problem arises since the device may be destroyed by metal diffusion at the time of forming ohmic contact to the base layer after growth of the epitaxial layer. Therefore, the base layer of thickness of about 300 .ANG. is necessary.
In case of gallium antimonide series, when an indium arsenide layer is applide, there is no substantial lattice mismatch between the gallium antimonide layer of unit length of crystal structure of 5.8687 .ANG. and indium arsenide layer of that of 6.0583 .ANG., therefore theoretically the lattice match is obtained and the epitaxial growth is possible. However, there were various problems in the manufacture of actual device due to difficulty in manufacture of high cost gallium antimonide substrate, unestablishment of thin film growth technology, and instability of device manufacturing process and soon.

Hot electron device and a resonant tunneling hot electron device

Electronics And Telecommunications Research Institute


The present invention relates to a method of driving a photosensitive device comprising a matrix of photosensitive pixels distributed at the intersections of rows and columns of the matrix. The invention relates more particularly to the control of such devices used for the detection of radiological images. The method consists in subjecting the matrix to an image cycle that includes a reset phase prior to an image acquisition phase. The rows of the matrix are distributed in several groups, and during the reset phase, the method consists in resetting all the rows in any one group simultaneously and in resetting each group of rows in succession.

The present invention relates to a method of driving a photosensitive device comprising a matrix of photosensitive pixels of the type produced in particular by techniques for depositing semiconductor materials. The invention relates more particularly (but not exclusively) to the driving of such devices used for radiological image detection.
Techniques for the thin-film deposition of semiconductor materials, such as hydrogenated amorphous silicon (a-SiH), on insulating, for example glass, supports that are used to produce matrices of photosensitive pixels that can produce an image from visible or near-visible radiation. To use these matrices for the detection of radiological images, all that is required is to interpose, between the X-radiation and the matrix, a scintillator screen that converts the X-radiation into light radiation within the band of wavelength at which the photosensitive pixels are sensitive.
The photosensitive pixels that form such a matrix generally comprise a photosensitive element associated with an element providing a switch function. The photosensitive pixel is mounted between a row conductor and a column conductor of the matrix. Depending on the requirements, the photosensitive device then comprises a plurality of photosensitive pixels arranged as a matrix or as a linear array.
The photosensitive element usually consists of a diode connected in series with the switch element. The switch element may, for example, be a transistor produced by thin film deposition techniques. These techniques are known as TFT (thin film transistor) techniques. The switch element may also be a switching diode whose "closed" or "on" state corresponds to the bias that drives it into forward conduction and whose "open" or "off" state corresponds to its reverse bias. The two diodes are connected with opposed conduction directions in a configuration called "back-to-back". Such an arrangement is well known, for example from French patent application 86/14058 (publication No. 2 605 166) which describes a matrix of photosensitive pixels of the type with two diodes in a "back-to-back" configuration, a method of reading the photosensitive pixels and a way of producing such a photosensitive device. The components forming the matrix are produced from an amorphous semiconductor material that produces persistence. This is due to its amorphous structure, which includes a large number of traps, much more than in crystalline materials. These traps are structure defects which extend over the entire band gap. They retain charges generated during image acquisition. The material stores an image corresponding to a given irradiation and restores the charges relating to this image while the following image is being read, or even while several following images are being read. The quality of the images is thereby degraded.
To attempt to obtain a useful image of optimum quality, a correction is applied to the useful image on the basis of what is called an "offset image", also known as "dark image" that is generally acquired and stored at the start of an operating cycle. This offset image is the image obtained when the photosensitive device is exposed to a signal of zero intensity and corresponds to a kind of background image. The offset image varies according to the electrical state of the components of the photosensitive pixels and to the dispersion in their electrical characteristics. The useful image is that read whenever the photosensitive device has been exposed to a useful signal that corresponds to exposure to X-radiation. It includes the offset image. The correction consists in subtracting the offset image from the useful image.
To produce a useful image or an offset image, an image cycle is performed, that is to say a sequence formed by an image acquisition phase followed by a read phase and then by an erase and reset phase, as explained in patent application FR-A-2 760 585. During the image acquisition phase, the photosensitive pixels are exposed to a signal to be picked up, whether this signal is a maximum illumination signal or the dark signal. During the read phase, a read pulse is applied to the row conductors addressed for reading the amount of charge stored during the image acquisition. During the erase phase, the photosensitive pixels are erased, generally optically by means of a light flash uniformly distributed over all the photosensitive pixels. During the reset phase, the photosensitive pixels are reset to a state in which they are receptive to a new image acquisition. This resetting is performed by temporarily making the switching element, switching diode or transistor, conducting by means of an electrical pulse sent to the row conductors for addressing the matrix.
Hitherto, the photosensitive pixels of a matrix have been reset by generating a single electrical pulse simultaneously for all the photosensitive pixels of the matrix via the row conductors of the matrix. Unfortunately, the photosensitive pixels are not perfect. They are subject to parasitic elements, the modeling of which will be presented later with the aid of FIG. 3. These parasitic elements are essentially capacitive couplings. The rising edge of the electrical pulse sent to the row conductors of the matrix in order to turn on the switching elements injects charges onto column conductors of the matrix. The rising edge that opens the switching element is critical. The charges created on the column conductors by this rising edge can be discharged only via read circuits connected to the column conductors. These charges take a certain amount of time to be discharged and therefore temporarily cause a variation in the voltage on each column conductor. This voltage variation occurs at the moment when the photosensitive pixel is isolated. More precisely, it is the moment when the potential of the common point A between the photodiode and the switching element is fixed. This potential is essential as it is this which changes during the image acquisition phase owing to the effect of the light radiation received by the photodiode. This potential therefore depends on the voltage of the corresponding column conductor at the precise moment when the switching element opens. The presence of this voltage on the column conductor causes an average offset shift and therefore a loss of dynamic range in the useful image.
In addition, the moment when the switching element opens is not strictly identical for all the photo-sensitive pixels. This moment depends on the dispersion in the threshold voltages for each switching element and on the dispersion of the parasitic elements. This results in a dispersion in the offset for each photo-sensitive pixel.
It has been attempted to reduce the voltage on the column conductor, on the one hand by reducing the amplitude of the electrical pulse sent to the row conductors during the reset phase relative to the amplitude of the electrical pulse sent to the row conductors during the read phase and, on the other hand, by extending the rising edge that opens the switching element so that the switching time of the switching element is longer than the time needed to drain away the charges in the column conductors. This palliative remains somewhat unsatisfactory as it improves only few of the problems encountered. In addition, owing to the dissymmetry of the pulses between the reset phase and the read phase, this palliative results in a few offset stability defects.

Method of driving a photosensitive device


The invention relates to a probe for measuring volatile components in an aqueous solution, for example to determine the alcohol concentration of an aqueous solution, with a probe body with a continuous lumen and a membrane disposed transversely with respect to the lumen, which isolates the lumen from the outside, and with a semiconductor gas sensor disposed in a housing inside the lumen at a distance from the membrane forming a measuring chamber filled with air, said sensor responding to the gases permeating the membrane by changing its electrical resistance, with an open continuous pressure relief channel being provided for the outflow of the gases permeating into the measuring chamber on the side of the sensor and the measuring chamber facing away from the membrane, and the pressure relief channel being connected at one end through an opening to the measuring chamber and at the other end on the outlet side having an outlet opening of a size such that the volume flow of the gas permeating through the membrane into the measuring chamber is always slightly larger than the volume flow of the gas leaving the measuring chamber through the outlet opening of the pressure relief channel.

The invention relates to a probe for measuring volatile components in an aqueous solution, for example to determine the alcohol concentration of an aqueous solution, with a probe body with a continuous lumen and a membrane disposed transversely with respect to the lumen, which isolates the lumen from the outside and with a semiconductor gas sensor disposed in a housing inside the lumen at a distance from the membrane forming a measuring chamber filled with air, said sensor responding to the gases permeating the membrane by changing its electrical resistance.
A probe for measuring organic solvents in a liquid using a semiconductor gas sensor in a closed measuring chamber with a liquid-impermeable membrane, through which the gases diffuse, is known from DE 31 26 648 C2. As the concentration of the measured components decreases, the gas enriched in the measuring chamber diffuses back through the membrane into the liquid. This probe however operates very slowly and is therefore unsuitable for use in industrial processes due to the very slow gas circulation by back-diffusion through the membrane.
Other probes for removal of volatile components from liquids or gases, for example to determine the concentration, and which operate with a permeation membrane as well as a sensor, are known for example from EP-A 0174 417 and EP-A 0054 537. In these known probes, permeation membranes based on a tubular silicone body are used, through which membranes the volatile components to be measured permeate at various rates depending on their concentrations and then reach the sensor, which, because of its electrical properties, changes its resistance according to the concentration of the components to be measured and emits corresponding measuring signals. To increase the measurement efficiency, the tubular permeation membrane is flushed with a carrier gas.
The disadvantage of these known probes is that, by using the tubular silicone membranes, which do not have substance-specific separating effects, not only is the desired substance/gas to be measured separated from the liquid and measured, but other gases and substances also distort the measurement result for a desired substance.
Moreover, the known silicone membranes have well-delimited diffusion rates, particularly with respect to alcohol, so that it becomes necessary to have a very large membrane surface area.
Thus, DE 196 04 606 A1 has already proposed a measuring device for one of at least two volatile components of a liquid, in which a permeation membrane composed of at least two layers with different permeation resistances and a carrier gas used in conjunction with a sensor.

Probe for measuring volatile components in an aqueous solution


A skateboard truck assembly (10) having a main body (11) for mounting to the underside of a skateboard deck, an axle (24) carrying skateboard wheels (25) and mounted intermediate its opposite ends to the main body (11) via a rotatable steering adjustment body (20) for pivotal movement in a steering plane, the steering adjustment body (20) being mounted to the main body (11) for rotation about an axis extending transversely of the body (11) such that a change in the rotational position of the steering adjustment body (20) adjusts the pivot axis of the axle (24) and thus the steering characteristics of the truck assembly (10)

Skateboards in many different designs have developed since introduction of the basic skateboard configuration. In the basic configuration, the skateboard comprises a deck having on its lower side front and rear truck assemblies, each of which supports opposite pairs of wheels on a transversely extending axle. The axles are mounted for pivotal movement about axes which extend at an obtuse angle to the plane of the skateboard deck and usually, the pivot axes of the axles of the front and rear truck assemblies are of an opposite inclination. Skateboard are therefore able to be steered by the rider leaning or shifting his or her weight to one side or other of the skateboard board thereby pivoting the deck in opposite directions relative to the longitudinal axis of the skateboard, this causing fore and aft pivotal movement of the truck axles in opposite directions. Usually the skateboard truck assemblies incorporate resilient pads which resist pivoting of the axle of the wheels and tend to return the axle and wheels to a neutral position.
More recently longboard skateboards have been introduced which include a deck of extended length. Skateboards of this type also incorporate truck assemblies however some difficulties are associated with steering of this type of board and maintaining their stability if conventional truck assemblies are used. It is also desirable to the enable adjustment of the steering characteristics of this type of skateboard to suit different applications. For this purpose it has been known to place an angled or wedge-shaped packer between the skateboard truck assembly and the underside of the skateboard deck to adjust the pivot axis of the truck assembly axle. This procedure however is obviously time-consuming as it involves removal of the truck assembly and then reassembling with the use of the angled packer between the truck assembly and board. A further disadvantage is that each time a different angle is required for the plane of operation of the axles of the skateboard wheels, a packer of a different angle is required.
Other truck assemblies have means for varying the type or characteristics of the resilient pads used to resist pivotal movement of the truck wheel axles such that for example a greater or lesser weight is required to be applied to one side or other of the skateboard deck obtain the same steering movement of the skateboard truck assemblies. These types of truck assemblies however have disadvantages as steering then becomes dependent on the weight applied and as a result control is compromised.


The height from floor surface contact ends of leg linkages 2 to shoulder joints of a biped robot 1 when the biped robot is in an upright posture is defined to be a value falling within a range (Havg±½σ) set based on an averaged value Havg obtained by averaging the heights of a group of objects (subject to operation) from the floor surface and the standard deviation σ thereof, specifically a value in a range of from approximately 700 mm to 1000 mm. By this, the installation height of shoulder joints from the floor surface can be optimally determined in accordance with the heights of the objects, thereby improving operating efficiency in an existing operating space.

This applicant has led the world in research and development aimed at realizing biped robots capable of walking activities closely resembling those of human beings. And through the biped robots it proposed up to now has enabled stable robot walking on level ground, upgrades and downgrades, one-leg standing, and ascent/descent of stairs and level differences, thus realizing biped robots capable of adapting to various existing locomotion environments.
Further, it has made feasible use of arms connected to the robot body for operations such as tightening of screws and nuts with a driver (screwdriver) or wrench (spanner), and, in addition, has, by systematically coordinating movements of the legs and arms, made it possible to conduct complex operations such as opening/closing and passing through doors and pushing hand carts. These operations are the result of arm-leg cooperation achieved on a high-order and can be said likely to be a major factor in markedly upgrading compatibility with humans.
Thus the biped robots being researched and developed by the applicant have replaced people in performing various operations in existing operating venues (home, factory etc.) and, for the first time ever, suggested their potential to make coexistence with humans a reality.
In its research and development of these biped robots, however, the applicant has given the robots heights (total length in the vertical direction when in upright posture) of 1600 mm to 1800 mm, near average adult height, not only to make their walking movements close to those of human beings but also to give them a more human-like appearance.
Moreover, various technologies have been put forward regarding biped robots, including diverse proposals with respect to their size. In papers such as "Design and Development of Research Platform for Perception-Action Integration in Humanoid Robot: H6" (5th Robotics Symposia) and "Preliminary Motion Experiments of a Humanoid Robot Saika-3" (18th Annual Conference of the Robotics Society of Japan), for example, biped robots given a height of 1200 mm to 1300 mm are proposed from the aspects of enabling activities in existing operating spaces and achieving small size and light weight.
A number of inconveniences arise when an attempt is made to put a biped robot of the approximately 1600 mm to 1800 mm height adopted by the applicant heretofore into operation in an existing operating space. One that can be mentioned is the amount of battery power consumption. Moreover, greater height is accompanied by increased weight, but the lightest weight possible is preferable when coexistence with people at home, factories and the like is a consideration.
Further, there are many objects subject to operation (working) in an operating space, particularly in a home environment, which are ergonomically located at heights facilitating use not only by adults but also by children, wheelchair users and others, so that it cannot be said that a size near the average adult height (more exactly, the height of the shoulder joints determined therefrom, still more exactly, the arm linkage swing range (height) determined by the shoulder joint height) is necessarily appropriate for the height of the objects subject to operation. Furthermore, in the interest of still better compatibility with people, a robot should preferably be of a size that makes it more likable to people, and from this point also, it cannot be said that a size near average adult height is necessarily appropriate.
On the other hand, points such as weight reduction and likability can be improved by adopting a height of or near 1200 mm to 1300 mm as indicated by the aforesaid prior art. The fact is, however, that the aforesaid prior art etc. has fallen short of giving any consideration to joint height in actually performing operations or to size-related issues such as arm linkage length and the like, and when such a biped robot has actually been set to performing operations, it has been merely scaled down without optimizing the height relationship with the objects, which has made performance efficiency low and led to the following various problems being left unresolved.
For example, in the multi-degree-of-freedom arms of a robot (in a biped robot, the leg linkages and the arm linkages; the shoulder joints of the arm linkages being a particular concern here) there are generally present singularities (singular points) that restrict their movement, and, where consideration is given to performance, these singularities should preferably avoided in determining operation procedures.
Further, in performing different kinds of operations, the position of the object needs to be accurately ascertained with a visual sensor and, therefore, the relative positional relationship between the visual sensor and the object must be thoroughly taken into account.


A battery pack includes at least one battery cell, a microcomputer having a first voltage measuring terminal, a second voltage measuring terminal, and a reference voltage output terminal, the microcomputer being configured to control recharge and discharge of the at least one battery cell by detecting an abnormality of a reference voltage at the reference voltage output terminal in accordance with first and second voltages at respective first and second voltage measuring terminals, a voltage distribution unit connected between the reference voltage output terminal and a ground, the voltage distribution unit being configured to distribute voltage and to output to the microcomputer a medium voltage as the first voltage, and a voltage measuring unit connected between the reference voltage output terminal and the ground, the voltage measuring unit being configured to output to the microcomputer a forwarding direction voltage of a diode as the second voltage.

1. Field
One or more embodiments relate to battery packs that perform a protective operation by determining whether the battery packs are normal or not and methods of controlling the same.
2. Description of the Related Art
Generally, with the development of portable electronic devices, e.g., cellular phones and personal digital assistants (PDAs), studies about rechargeable secondary batteries have been actively performed. In particular, various kinds of rechargeable secondary batteries, e.g., a nickel metal hybrid battery (NiMH), a lithium ion battery, a lithium polymer battery, a metal lithium battery, and an air zinc battery, have been developed. The rechargeable secondary battery includes a battery pack with a circuit, and charges and discharges are performed through external terminals of the battery pack.
A conventional battery pack may include battery cells and a peripheral circuit having a rechargeable circuit. The peripheral circuit may be combined with the battery cells, after the peripheral circuit is formed as a printed circuit substrate. When the battery pack is connected to an external power through the external terminals of the battery pack, the battery cells are charged by the external power supplied through the external terminals and the rechargeable circuit, and when a load is applied to the battery pack through the external terminals, the power of the battery cells is supplied to the load through the rechargeable circuit and the external terminals. At this point, the rechargeable circuit of the peripheral circuit controls the recharge and discharge of the battery cells connected to the external terminals. Generally, a plurality of battery cells is connected in parallel or in series.

Battery pack and method of controlling the same


A mass spectrometer for producing a primary beam of ions for bombarding a sample under vacuum. The mass spectrometer includes a detector for detecting a secondary beam of ions released from the sample. The primary beam of ions includes water clusters where each water cluster contains between 1 and 10,000 water molecules. The primary beam of ions, in one embodiment, is produced by adiabatic expansion of water vapor. An auxiliary beam of ions for bombarding the sample includes a different species to those of the primary beam of ions.

In 1910, the British physicist J. J. Thomson observed that positive ions and neutral atoms were released from a solid surface when bombarded with ions. Later, in 1949, improvements in vacuum pumps and associated technologies enabled the first prototype experiments on Secondary Ion Mass Spectrometry (SIMS) to be carried out by Herzog and Viehbock at the University of Vienna in Austria. Since the earliest days, the potential for SIMS to be a very powerful analytical technique has been recognised but has not yet realised its fullest potential. In the intervening years to now, the SIMS technique has expanded to encompass many different and useful methods of material analysis, many of which are not achievable by other analytical methods. These include 2 dimensional chemical mapping or imaging, depth profiling and more recently the capability to obtain detailed chemical and compositional information from biological and bio-chemical materials. The range of probes of the material has also increased, starting from elementary ion probes, such as argon or oxygen, but now including large molecular clusters such as C60, giant gas clusters and laser ablation. Other improvements to the SIMS technique have included improved mass and spatial resolution, the possibility to measure non-ionised material removed from the sample by post ionisation, the so called Secondary Neutral Mass Spectrometry (SNMS) that permits analysis of the removed material in a mass spectrometer and the ubiquitous advances in computing technology that has led to a vast array of instrument control, data capture and analysis facilities.
Several methods of analysis in a mass spectrometer are used for SIMS. These include mass separation by using powerful electromagnets, the so called Magnetic Sector instrument, mass separation by the application of Radio Frequency (RF) electric fields, the so called Quadrupole and the Ion Trap, and the separation of masses by their arrival time at a detector, the technique known as Tine of Flight (ToF). The Time of Flight SIMS technique is particularly well suited to analysis of organic samples, because it can simultaneously detect ions from a wide mass range, allowing for a very high efficiency in detecting a large proportion of secondary ions. FIG. 1 shows a typical arrangement inside the vacuum chamber of a ToF-SIMS instrument. The sample to be analysed is mounted on a holder (1) which is introduced into a vacuum chamber (2) and secured on a motion stage (3). A primary ion beam (4) is generated by an ion source (not shown), accelerated and directed at the sample. The vacuum housing (5) that encloses the ion source is shown in part. The impact of primary ions on the sample surface causes secondary ions to be ejected from the sample and these are captured and accelerated by the extraction optics (6). These ions travel in the direction (7) to enter a time of flight analyser (not shown) and ultimately to hit an ion detector. The vacuum housing (8) for the analyser is shown in part. The time of flight analyser can be simply a flight tube, but may also contain other ion-optical components such as energy-compensating devices, focusing or alignment devices or pulsing devices.
During the latter part of the twentieth century SIMS developed largely as a technique for elemental analysis. Atomic or small molecular ion beams, made of species such as Ga+, Cs+, O2+, Ar+, were used as primary ion beams to stimulate emission of secondary ions. Such primary beams cause too much damage at the sample surface and too much fragmentation of emitted material to produce large molecular secondary ions. So, the technique was limited to elemental analysis or, at best detection of small molecular fragments. Ion beams of different species offered a range of features, suiting them to different variants of SIMS analysis. For example, a small probe size is advantageous for high spatial resolution imaging or a good beam shape is advantageous for depth profiling. Oxygen beams enhance yields of positive secondary ions, whilst caesium beams enhance negative secondary ion yields.
Around the year 2000, cluster ion beams were introduced to extend the mass range of the SIMS technique and to enable organic analysis. The earliest cluster ion primary beams were small metallic clusters produced by a liquid metal ion source (LMIS), for instance gold clusters of 2 or 3 gold atoms (N. Davies, D. E. Weibel; N P. Lockyer, P. Blenkinsopp, R. Hill, J C. Vickerman Appl. Surf. Sci. 203-204 (2003) 223-227), followed by similar sources using alternative metals such as bismuth. Such beams were able to release secondary ions of whole organic molecules and large fragments, but they cause too much damage to underlying sample to continue analysis beyond the top monolayer or so of the sample surface, when used by themselves. The first cluster beam that was routinely capable of analysing a polymer or organic sample whilst etching through its bulk was the C60 ion beam (D. Weibel, S. Wong, N. Lockyer, P. Blenkinsopp, R. Hill, J C. Vickerman, Anal. Chem. 75 (2003) 1754). C60 was found to produce higher yields of organic molecules with much reduced damage to the underlying sample. This is because, with 60 atoms in its cluster, the beam energy is dissipated only in the top few layers of the sample, releasing intact secondary ions by shaking them from the surface surrounding each impact site and leaving underlying chemistry largely undamaged.
The next significant development in ion beams for organic SIMS was the Gas Cluster Ion Beam (GCIB). Cluster formation through a supersonic expansion was first studied by Becker et al. for thermonuclear fuel applications (E. W. Becker, K. Bier, W. Henkes, Z. Phys. 146 (1956) 6511). Clusters are typically formed by creating an adiabatic expansion of a gas from a high pressure region into a low pressure region through a small orifice. As the gas expands, it cools, and clusters are formed. These clusters can range from 2 atoms up to tens of thousands of atoms. By ionising the clusters, it is possible to produce charged clusters, which can then be mass filtered if required, and accelerated to produce an ion beam that can be directed onto a sample. Cluster beams can deliver a large amount of the cluster material to the sample at relatively low energies per atom within the cluster. This has opened out new applications using them for cleaning surfaces, reducing surface roughness, and depositing material on the surface.
Over the past decade, there has been much work done with argon gas cluster ion beams for use in modifying surface properties of materials (Isao Yamada, Jiro Matsuo, Noriaki Toyoda, Norihisa Hagiwara, Nucl. Instr. and Meth. B 161-163 (2000) 980-985). More recently, argon gas cluster ion beams have been used for sputtering material in SIMS, where they have been shown to be able to sputter large organic molecules with less fragmentation and damage then occurs when atomic ion beams are used (Sadia Rabbani, Andrew M. Barber, John S. Fletcher, Nicholas P. Lockyer, and John C. Vickerman, Anal. Chem. 2011, 83, 3793-3800).
In present day organic SIMS analysis, the C60 and argon cluster beams are used as low-damage beams either for etching away layers of sample between analyses by another ion beam, or for direct SIMS analysis. The use of these cluster beams has opened out the use of SIMS in analysis of polymers and biological material. However, there is a remaining problem of sensitivity to large molecular species which may be present in very small concentrations in the sample. This problem arises from the need to detect such large molecules from within a very small area of the sample. One of the most promising fields for organic SIMS is in the imaging of cells, tissue, or other structures with very fine features. The imaging technique usually proceeds by scanning the primary ion beam across the sample in steps, thus acquiring a mass spectrum from a series of pixels. With a suitable scan pattern, a complete image of a sample area is built up, with a mass spectrum for each pixel in the image. With present day ion beams (C60 and argon clusters) detection of important organic molecules, such as lipids or peptides, becomes unsatisfactory when the pixel size decreases below a few square microns. The number of molecules available for interrogation within such a small area is limited and the technique may need to be sensitive to less than an attomole presence of a particular molecule in each pixel. ToF SIMS instrumentation has been improved to give high transmission and dynamic range in order to maximise sensitivity; there remains little room for improvement through instrument development. However, there is an opportunity to achieve significantly higher sensitivity by increasing the yield of secondary ions. Most of the material that is sputtered from the surface leaves as neutral molecules or fragments. By causing the ionisation of more of this material, sensitivity in organic analysis would be increased proportionately.
We have invented a water cluster primary ion beam that provides a surprisingly good enhancement in ion yields. Water clusters formed by adiabatic gas expansion have been previously studied for their effects on smoothing and oxidation of surfaces (Hiromichi Ryuto, Keiji Tada, Gikan, H. Takaoka, Vacuum Vol. 84, Issue 5, 10 Dec. 2009, Pages 501-504), and methods for generating such clusters have been described. Droplets of protonated water (ie. H(H2O)n+) produced by squirting a liquid mixture of water, methanol and acetic acid through a fine capillary have been found to give a small increase in ionisation when sprayed at low energy onto a surface during SIMS analysis (Guangtao Li, Jobin Cyriac, Liang Gao and R. Graham Cooks, Surface and Interface Analysis Vol. 43, Issue 1-2, 498-501, January-February 2011) compared to the significant increase in ion yield that can be achieved with the present disclosure. This experiment used a wide spray of protonated droplets rather than a focussed beam of water clusters. In our disclosure, the beam can be focused to less than 5 microns, allowing the use of the beam for analysis at high spatial resolution or for precise co-targeting of an analysis point with another beam performing analysis. Organic samples are often frozen for SIMS analysis in order to preserve the hydrated structures of the samples, for instance in analysis of cells or tissues, or to stabilise chemistry under ion bombardment, as in some multi-interface polymer analysis. A broad water cluster ion beam or a water vapour jet is undesirable for frozen samples owing to the danger of frost formation over the sample surface.

Water cluster ion beam mass spectrometer apparatus and method


The present invention is directed to compositions and methods for stabilizing a protein without a surfactant. The present invention is further directed to compositions comprising a protein and at least one excipient selected from the group consisting of hindered amines, anionic aromatics, functionalized amino acids, oligopeptides, low molecular weight aliphatic polyacids, zwitterions, phospholipids, cyclodextrins, polyethylene glycols, gelatins, urea, ethanol, glycerin, dextran, xanthan gum, 2-(2-ethoxyethoxy)ethanol, hydroxypropyl cellulose, propylene glycol, a short-chain organic acid, deoxycholate, sodium nitrate, sodium sulfate, proline and lysine.

Auto-immune diseases affect nearly 24 million people in the United States (roughly 8% of the population) alone making it one of the most prevalent diseases. By comparison, heart disease affects 22 million and cancer 9 million. Many auto-immune diseases are correlated with elevated levels of a naturally occurring protein in the body known as tumor necrosis factor ("TNFα"). TNFα is a cytokine capable of inducing fever, cell death and inflammation among other illnesses. TNFα works by binding to and activating cell surface receptors which lead to the activation of genes involved in inflammation.
Adalimumab is an anti-inflammatory drug targeted to inhibiting TNFα from binding to these cell surface receptors. Adalimumab is the first fully human monoclonal antibody approved by the United States Food and Drug Administration (FDA) and is sold by AbbVie Biotechnology LTD under the trademark Humira® (Humira is a registered trademark of AbbVie Biotechnology LTD). Humira® has been approved by the FDA for several auto-immune diseases including rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, Crohn's disease, ulcerative colitis, moderate to severe chronic psoriasis and juvenile idiopathic arthritis.
Pharmaceutical formulations need to be stable to allow for storage and efficacy of the active ingredient drug product. Excipients are frequently added to formulations to increase stability. However, interactions between compounds and the drug product are complex and unpredictable. Especially for large complex molecules like antibodies. While some excipients are known to stabilize formulations in one aspect, they may destabilize them in another.
For example, the surfactant polysorbate 80 is a non-ionic excipient prevalently known to increase physical stability of proteins upon exposure to hydrophobic-hydrophilic interfaces such as air-water and ice-water. However, as shown herein, polysorbate 80 decreases colloidal stability of adalimumab. All formulations of adalimumab drug products (Humira® and Amjevita™) contain polysorbate 80. New formulations of adalimumab without surfactants can improve product stability.
Thus, there is still need for new liquid formulations of pharmaceutical proteins (e.g. adalimumab) that are stable and allow for product storage without substantial loss in efficacy.

This patent is subject to a terminal disclaimer.

Stable protein compositions and methods of their use


Disclosed is a method for detecting a leak in a closed loop heat transfer system comprising monitoring the pressure of the heat transfer composition inside said heat transfer system, wherein a drop in pressure indicates a leak. Also disclosed is a heat transfer system comprising an evaporator, a compressor, a condenser, an expander and a device for measuring internal system pressure. The system pressure measuring device is disposed inside the closed loop heat system. The internal system pressure measuring means may be located either between the evaporator and the condenser, between the expander and the evaporator, between the compressor and the condenser, or between the condenser and the expander.

1. Field of the Invention
The present disclosure relates to a method of detecting a leak of a heat transfer composition from a closed loop heat transfer system. In particular, it relates to locating a pressure monitoring device inside the closed loop system for monitoring pressure changes inside the system to indicate a leak.
2. Description of Related Art
Currently used heat transfer compositions for mobile and stationary refrigeration, air conditioning, and heat pump systems comprise single component compositions. Most commonly hydrofluorocarbons, such as 1,1,1,2-tetrafluoroethane (HFC-134a), are used as the heat transfer compositions in such systems. Leaks of hydrofluorocarbon from a system are generally only detected when the system fails to operate properly, e.g. an air conditioner that no longer provides cooling. This causes large amounts of heat transfer composition to be released to the environment and results in essentially a complete break-down of the system prior to detection of a leak. Early detection of a leak would be advantageous in reducing emissions and providing more reliable cooling performance.
Certain multi-component mixtures have been proposed or are being used as replacement heat transfer compositions. For some of these compositions, especially where a leak produces a significant pressure change in a heat transfer system, a new method for early detection of leaks is desirable.

Method for leak detection in heat transfer systems


A liquid ejection head includes a print element board and an electric wiring board electrically connected to a bump of the print element board using an interconnecting wire. The bump has a first surface and a second surface. The height of the second surface from a surface of a base plate is higher than that of the first surface. The first surface has a protrusion formed therein, and the bump is connected to the interconnecting wire in the second surface.

1. Field
Aspects of the present invention generally relate to a liquid ejection head and a method for manufacturing a liquid ejection head.
2. Description of the Related Art
A liquid ejection head used in, for example, ink jet printing apparatuses includes a print element board and an electric wiring board. FIG. 2A illustrates a print element board of a liquid ejection head. The print element board includes a base plate 1 and an energy generating device 15 that generates energy for ejecting droplets of liquid. The base plate 1 has a supply port 11 formed therein. The supply port 11 supplies liquid to the energy generating device 15. In addition, the base plate 1 includes an ejection port forming member 12 for forming an ejection port 13. The ejection port 13 ejects droplets of the supplied liquid.
As described in Japanese Patent Laid-Open No. 2007-307833, electric power is supplied from an external electric wiring board to the energy generating device 15 using an electrode pad (not illustrated) of the print element board and a bump 7 formed on the electrode pad. The electrode pad is electrically connected to the energy generating device. Electric power is supplied from the electric wiring board by connecting the bump 7 to the electric wiring board using an interconnecting wire.
For example, the bump 7 is formed by plating, such as gold plating. FIG. 2B is a cross-sectional view taken along a line IIB-IIB of FIG. 2A, that is, an enlarged view of the bump formed by plating. The bump 7 is formed on an electrode pad 3 made of, for example, aluminum. An insulation layer 2 made of, for example, SiO2 is disposed between the base plate 1 and the electrode pad 3. The electrode pad 3 is disposed between protective layers 4 made of P—SiN. In order to increase adhesiveness between the electrode pad 3 and the bump 7 and prevent a decrease in connection reliability caused by mutual metal diffusion, a diffusion prevention layer 5 is formed between the electrode pad 3 and the bump 7.

Liquid ejection head and method for manufacturing liquid ejection head


In a buffer and a state included in a pseudorandom number generating apparatus, the state has the configuration of assuming that the unit length of data processing is n, the state has a size of 3×n bits, and the buffer has a capacity of 32×n bits, and according to clock control, a state transformation section (state transformation function) for conducting a state alteration from time t to time t+1 uses a nonlinear function F (having an n-bit input and an n-bit output) twice, or two different nonlinear functions F and G respectively once. The state transformation section has such a configuration that a nonlinear function such as a round function of a block cipher sufficiently evaluated as to the cryptographic security and implementation.

The present invention relates to a technique for generating a practical random number sequence and its application technique.
In signature generation utilizing a public key cryptosystem, generation of a key in conducting secret communication, and a stream cipher technique, a random number sequence is highly needed. However, it is impracticable to attempt to use a truly random number sequence in these situations. In practice, there is used a pseudorandom number (hereafter simply referred to as random number) generated by a pseudorandom number generating method or an apparatus using the pseudorandom number generating method. As conditions required of the pseudorandom number as regards use in cryptograph, there are properties concerning the security, such as that the pseudorandom number is unpredictable and the initial value for determining the random number cannot be derived. In addition, in order that the pseudorandom number generating method or the pseudorandom number generating apparatus may withstand the practical use, high speed processing is demanded in software implementation or hardware implementation. In addition, the pseudorandom number generating method or the pseudorandom number generating apparatus needs to be efficient from the aspect of the implementation cost as well. For example, the number of gates required in the case of hardware implementation, and the number of steps and required memory region at the time of execution in the case of software implementation need to be small. As a general purpose cryptographic algorithm, an algorithm having no drawbacks in all of these evaluation items is desirable.
Many of currently known algorithms are suitable for either software or hardware in the aspect of performance or implementation.
For example, in the case of an algorithm especially suitable for software implementation, the circuit scale becomes large because the situation at the time of hardware implementation has not been considered.
As an example using an algorithm suitable for hardware processing, there is a pseudorandom number generating apparatus based on a linear feedback shift register (LFSR) that is small in hardware implementation scale and that is capable of realizing high speed processing as well. However, this is not sufficient in processing speed in the case where software implementation is conducted.
As such a pseudorandom number generating method that practical implementation is possible in both software and hardware, the OFB mode and the counter mode, which utilize the block cipher technique are known. However, their random number generating speed is the same as the processing speed of the block cipher. In general, the processing speed is not sufficient as compared with dedicated pseudorandom number generating apparatuses.
As the application field of the cryptographic technique spreads, there is desired a pseudorandom number generating technique that satisfies the above-described conditions in both hardware and software and that has a degree of freedom and flexibility enough to put it to practical use.
Furthermore, a pseudorandom number generating technique having high security is demanded.

Pseudorandom number generating apparatus or encryption or decryption apparatus using the same


The disclosure concerns packaging and dispensing of fluid products. The disclosed device comprises at least two sealed flexible bags arranged in a single common rigid container, associated with at least a pump or valve, actuated by an actuator, wherein the bags cooperate with at least a ring for being fixed to the container and with the pumps or valves. The device is designed to dispense fluids separately or mixed.

1. Field of the Invention
The present invention relates to a device for packaging and dispensing fluid products, and more particularly a novel device for packaging and dispensing fluid, liquid or pasty products, of the type comprising at least two flexible bags placed in a single rigid container and connected to one or more pumps or valves, for the storage, protected from the air, of at least two fluid products and for dispensing them, as a mixture or separately, in an efficient manner.
2. Description of the Related Art
Devices of the pocket flask type for packaging and dispensing fluids are well known. They generally comprise a container with a rigid shell in which is placed a flexible bag that contracts as the product is extracted from it. The product may be expelled from the bag using an airless pump or under the pressure of a propellant gas acting within the flask, on the wall of the bag. When the product is expelled from the bag using an airless pump, a vent is provided, generally in the base or neck of the flask, to allow external air to enter the space between the flask and the bag each time the pump is actuated, thus allowing the bag to contract while maintaining sufficient pressure on its walls. An example of an embodiment using this method is described in patent FR 2 723 356 relating to a device comprising a flexible bag made of plastic, such as polyethylene or polypropylene, in a rigid container whose neck has an air inlet.
Another device using this method and designed for the selective dispensing of one or two products, separately or as a mixture, is described in patent FR 2 804 666, according to which a first product is introduced into the bag whereas the second, together with the propellant gas, are in the rigid container, around the bag, the whole being supplemented with a selective valve. However, this system is relatively complex and requires a special valve.
U.S. Pat. No. 5,411,176 describes a rigid container containing two flexible bags, in which the container is provided with a circular flange under which are fastened two bags inserted through the flask's removable base, and bearing two airless pumps. Another device comprising a rigid container associated with two bags and two valves is described in utility model DE-91 05 565 in which the bags are fastened via tubular sleeves and connecting tubes to a plate housing the valves.
The problems with this method are often linked to the deformations in the wall of the bag as it contracts, which can hold back considerable amounts of product and limit the efficiency with which the fluid is dispensed. Another problem is to ensure satisfactory sealing of the bag so as to preserve the integrity of the product contained therein. Specifically, the products contained in the bags are often sensitive to oxidation caused by oxygen in the air and can deteriorate if air enters the bag. Sealing defects are often found at the junction between the bag and the pump. They can also result from a degree of porosity of the materials used to make the bag. Lastly, the folds formed by the wall of the bag as it contracts can lead to tears that can let air in which degrades the product contained in the bag.
These problems are exacerbated when it is desired to use two or more bags within the same rigid container to dispense, simultaneously or separately, two or more complementary products.

Device with rigid container and multiple flexible bags for packaging and dispensing fluids


A speaker device includes: a frame, a vibration unit and a magnetic circuit unit. The vibration unit includes a diaphragm and a voice coil. The magnetic circuit unit includes a yoke and a magnet. The yoke includes a yoke body, a yoke side wall and yoke extension portions protruding from the yoke side wall toward the frame. The magnet is fixed to the yoke body and is spaced apart from the yoke side wall to form a magnetic gap. The voice coil is inserted into the magnetic gap. The yoke side wall is fixed to the frame. The frame body includes a frame body having a ring shape, and frame fixing portions extending from the frame body toward the yoke side wall. The speaker device of the present disclosure can achieve a simple structure, high strength, easy assembly and positioning, and high reliability.

With the advent of the Internet era, the number of smart mobile devices is continuously rising. Among innumerous mobile devices, mobile phones are undoubtedly the most common and most portable mobile terminal devices. At present, mobile phones have extremely diverse functions, one of which is a high-quality music function. Therefore, speaker devices for playing music are widely used in smart mobile devices.
In the related art, a speaker device includes a frame, a vibration unit fixed to the frame and a magnetic circuit unit driving the vibration unit to vibrate and produce sound. The magnetic circuit unit includes a yoke fixed to the frame and a magnet accommodated in the yoke. The yoke is fixed to the frame by gluing.
However, since the frame of the speaker device is typically made of low-strength plastic, the speaker device is prone to be deformed. In addition, the yoke and the frame are prone to move when they are fixed by gluing, which makes it hard for the accurate positioning of the magnetic circuit unit, thereby leading to low reliability of the speaker device.
Therefore, it is necessary to provide a speaker device to solve the above technical problem.


A semiconductor memory device includes a first memory block, a second memory block, and a signal controller. The first memory block is configured to generate a first blocking signal, a second blocking signal, and a first enable signal in response to a row address, and to block and enable wordlines of the memory block in response to the first blocking signal and the first enable signal, respectively. The second memory block is configured to generate a third blocking signal, a fourth blocking signal, and a second enable signal in response to the row address, and to block and enable wordlines of the second memory block in response to the third blocking signal and the second enable signal, respectively. The signal controller is connected between the first memory block and the second memory block and is configured to enable the third blocking signal when the second blocking signal is enabled, and to enable the first blocking signal when the fourth blocking signal is enabled.

The inventive concepts described herein relate to semiconductor memory devices, and more particularly, the inventive concepts relate to semiconductor memory devices in which redundancy wordlines are shared between memory blocks.
Semiconductor memory devices include a plurality of memory cells arranged in a matrix of rows and columns. Among the large numbers of memory cells within the matrix, some of the memory cells may be defective as the result of a variety of causes, including substrate imperfections, layout defects, processing defects, and the like. Rather than scraping the entire memory device when defects occur, yields can be improved by replacing a defective with a redundancy memory cell included within the device. Generally, repair operations of this type are carried out by enabling a redundancy wordline in lieu of a wordline containing one or more defective memory cells.

Semiconductor memory device including signal controller connected between memory blocks


A sign post kit having an anchor post member is secured to the ground by a pair of stakes driven through two PVC pipes disposed in diagonally opposite corners thereof, a main post member is slid over a portion of the anchor post member and stake combination and securely snapped into place, and an arm member is snapped onto the main post member. A brochure holder is formed out of one end of the arm member and is covered by a flap. Signs are hung from the arm member or ride on top of the arm member. A flag can be inserted into a flag pole holder formed in the top the main post member or in a portion of the arm member. A stake puller jack is provided for removing the stakes from the ground.

Arm post signs have been in use for a very long time. This type of sign has been very effective in real estate, building, and advertising markets. These signs arc usually manufactured out of 4.times.4 salt treated or pressure treated lumber, and are therefore very heavy, and difficult to install and to remove. Usually a professional installer is hired for the installation and removal of such signs. The installation and removal time factor also needs to be considered. It is important to get the sign up and down as fast as possible. It becomes a burden to contact the installer, wait for the sign to be installed, then install the advertisement sign. Contact the installer again for removal, remove the advertisement sign again and wait again for the installer to remove the sign. Attempts have been made to construct light weight signs, most of which are complicated to install or have small parts, such as nuts and bolts, which are easily lost or misplaced. Ground anchoring systems are difficult to remove. Especially after the ground stake as been implanted for several month or the ground is frozen.
Brochure or flyer boxes are also being used in combination with the arm post sign, and are usually attached to the vertical main post of the sign, or are attached to the advertisement sign and hang from it in the horizontal position. These brochure boxes need be removed again before the sign can be removed by the professional installer, or such box may be damaged in transport.
Flags are often used and attached to the arm post sign. Either a bracket is screwed onto the main post of the sign, into which the flag pole is inserted. This bracket is again easily damaged in transport and easily damaged during installation. Another method is to drill a hole into the 4.times.4 main post, into which the flag pole is fitted. After prolonged use this drilled hole becomes loose, and the flag pole will no longer stay in place.
The continued use of such a sign can become quite expensive over a period of time.


An improved modulation circuit and method for TDMA are provided, wherein the transmission data (TD) in odd-numbered time-slots are processed based on a transmission-window signal (Twe) with a differential encoder (10o), a timing generator (20o), a filter (30o), an amplitude data generator (40o), a multiplier (50o), and an I/Q-discriminator (60o), which are configured as odd-dedicated units, and is output from an adder (71) as transmission signal data (IT) and (QT). The transmission data (TD) in even-numbered time-slots is processed with a differential encoder (10e) and other components, which are configured as even-dedicated units, and is output from the adder (71) in common. Thereby, the appropriate data transmission can be achieved in spite of a decrease of guard bits between a couple of time-slots.

FIG. 2 is a schematic diagram explaining such a TDMA communication system as disclosed in Japanese Patent Kokai 09-153919. The TDMA system is operable with Personal Handy-phone System (PHS) standard RCR STD-28 (the second generation cordless telephone system standard) recognized by the Association of Radio Industries and Businesses (ARIB) in Japan.
As shown in FIG. 2, a frame of 5 ms is divided into eight time-slots of 625 μs. The preceding four time-slots of each frame are assigned to CH1-CH4 which are provided for a transmission of signals from a base station to mobile terminals. The succeeding four time-slots of each frame are assigned to CH1-CH4 which are provided for the transmission of signals from mobile terminals to a base station. Each of the former CH1-CH4 and the corresponding one of the latter CH1-CH4 are combined with one another so as to accomplish bi-directional communication in a time divisional manner.
An information block of 240 bits can be conveyed by each of time-slots at the transmission rate of 384 Kbps. The leading 4 bits of the information block are ramp bits for a rising edge, the succeeding 220 bits are a transmission data block to be transmitted, the further succeeding 4 bits are ramp bits for a trailing edge, the remaining 12 bits are guard bits.
The ramp bits provide a gradually rising of the information block and insures a certain margin for a duration of trailing of the block so as to suppress some spurious components caused by an abrupt rising and trailing edge of the information block successively emitted from each channel in a burst form. The guard bits are provided to designate a null signal period so as to prevent the transmission signals from colliding with each other between channels due to a drift of transmission timing.
The transmission data block of 220 bits includes information data, start bits, a preamble, and error correction check bits to provide 32 Kbps full-duplex communication through each of CH1-CH4. The standard in PHS stipulates that a carrier should be transmitted while being modulated in the π/4 shift QPSK orthogonal modulation.
FIG. 3 shows an exemplary block diagram illustrating a prior art modulation circuit for TDMA shown in FIG. 2.
This modulation circuit includes a differential encoder 10 which is provided with transmission data TD and a transmission clock TC from a S/R (Send/Receive) control circuit (not shown), a timing generator 20 provided with the transmission clock TC and a transmission-window signal TW, and a filter 30. The differential encoder 10 generates a signal IA of the in-phase component and a signal QA of the quadrature-phase component in the π/4 shift QPSK orthogonal modulation from the transmission data TD of 384 Kbps which is burst and synchronized with the transmission clock TC of 384 KHz, thereby supplying the signals IA and QA to the filter 30. The timing generator 20 generates timing signals required for the respective parts of this modulation circuit based on the transmission clock TC and the transmission-window signal TW corresponding to the transmission data TD of 220 bits.
The filter 30 includes shift registers 31 and 32, a selector (SEL) 33, a counter (CNT) 34, and a read only memory 35 (referred to as a ROM 35 hereinafter) to transform the signals IA and QA to signals in a narrow-band (referred to as narrow-banded signals hereinafter) using Nyquist Filter Method.
The shift registers 31 and 32 convert the signals IA and QA into signals IB and QB in a parallel form in accordance with a shift clock SC of 192 kHz supplied from the timing generator 20 and outputs them. The contents of the shift registers 31 and 32 are cleared in response to a reset signal RS supplied from the timing generator 20. The output ports of the shift registers 31 and 32 are coupled with input ports of the selector 33.
The selector 33 selects an alternate one of the signals IB and QB in response to a clock CK1 supplied from S/R control circuit (not shown) and output it as a signal IBQ. The frequency of the clock CK1 is 1.92 MHz, which is 10 times as long as the shift clock SC. The counter 34 counts the clock CK1 repetitively from 0 to 9 in increments of 1. Its count value CN is provided as an address signal for the ROM 35 together with the signal IBQ. The counter 34 is configured to reset at a rising edge of the shift clock SC supplied from the timing generator 20.
The ROM 35 stores data of narrow-banded signal waveforms which contain in-phase components and quadrature-phase components of the π/4 shift QPSK orthogonal modulation signal. The ROM 35 is configured to store the values sampled from the signals IB and QB at the frequency being 10 times as long as a modulation rate (192 K symbol/s). Specifying an address for the ROM 35 by means of the signal IBQ and the count value CN, the corresponding stored value can be read as data IQC.
Furthermore, this modulation circuit includes an amplitude controller 40, a multiplier (MUL) 50, and an I/Q-discriminator 60.
The amplitude controller 40 is comprised of an up-down counter to generate an amplitude data AM for controlling the amplitude of transmission signals based on a count control signal TM supplied from the timing generator 20 and a clock CK1 supplied from a S/R control circuit (not shown). That is, the amplitude controller 40 will be reset to zero during the period when there is no transmission data and when the guard bits in the transmission time-slot appear. The amplitude controller 40 is caused to count up by the clock CK1 during a period of ramp bits in a rising edge. During a period of the transmission data etc., the amplitude controller 40 halts its counting operation, and then counts down with the clock CK1 during a period of ramp bits in a trailing edge. The amplitude controller 40 is configured to provide its count value to the multiplier 50 as an amplitude data AM.
The multiplier 50 multiplies the data IQC read from the ROM 35 and the amplitude data AM in response to a clock CK2 of 3.84 MHz supplied from the S/R control circuit (not shown), to generate a transmission signal data IQT. The I/Q-discriminator 60 divides the transmission signal data IQT into transmission signal data IT of in-phase and transmission signal data QT of quadrature-phase in response to the clock CK1.
The transmission signal data IT and QT are transformed to radio signals and are transmitted via a transmission unit (not shown).
The operation will be described below.
In a mobile station, when a transmission timing for a specified time-slot occurs, the transmission-window signal TW is supplied from S/R control circuit to the timing generator 20, and then the transmission data TD is supplied to the differential encoder 10.
The differential encoder 10 generates some codes according to the π/4 shift QPSK orthogonal modulation system from the transmission data TD in synchronism with the transmission clock TC, which are output as signals IA and QA to the shift registers 31 and 32 respectively. The timing generator 20 generates a shift clock SC, a reset signal RS, and a count control signal based on the transmission-window signal TW.
The shift registers 31 and 32 converts the signals IA and QA into parallel data signals in synchronism with the shift clock SC, the parallel data signals being sent to the selector 33. The selector 33 selects an alternate one of the signals IB and QB in response to the clock CK1, the selected one being supplied as a signal IBQ to the ROM 35. On the other hand, the counter 34 generates a count value CN in response to the clock CK1 with the repetitive range of 0 to 9, the value CN being supplied to the ROM 35. In the ROM 35, the stored contents which are associated with an address specified by the signal IBQ and the count value CN are read sequentially as data IQC including the in-phase component and the quadrature-phase component.
The amplitude controller 40 generates a amplitude data AM based on the count control signal TM and the clock CK1, the amplitude data AM being supplied to the multiplier 50. The multiplier 50 multiplies the data IQC read from the ROM 35 and the amplitude data AM in response to the clock CK2, to generate transmission signal data IQT. The I/Q-discriminator 60 divides the transmission signal data IQT into the transmission signal data IT of in-phase and the transmission signal data QT of quadrature-phase in response to the clock CK1.
When the transmission of a specified time-slot is completed, a reset signal RS is output from the timing generator 20, and then the contents held by the shift registers 31 and 32 are cleared to prepare for the next transmission data.
However, a prior art modulation circuit raises the following problems.
When the transmission of the specified time-slot is completed, a reset signal RS is output from the timing generator 20, and then the contents held by the shift registers 31 and 32 are cleared. The timing for outputting the reset signal RS arises after the signals IA and QA held by the shift registers 31 and 32 during a constant period are completely read out. For example, that timing of the reset signal RS might arise just 16 clocks late from the completion of the transmission-window signal TW.
Therefore, in order to transmit data at a rate such as 64 kbps, if the amount of guard bits become small due to timing gaps for use of two successive time-slots, it is likely that the effective reset signal RS will not be output, then appropriate data transmission might not be performed.

Modulation method and circuit for time division multiple access


In one aspect, a transistor comprises a metal emitter, a first semiconductor barrier, a metal base, a second semiconductor barrier, and a metal collector. The first semiconductor barrier separates the metal emitter and the metal base and has an average thickness based on a first mean free path of a charge carrier in the first semiconductor barrier emitted from the metal emitter. The second semiconductor barrier separates the metal base from the metal collector and has an average thickness based on a second mean free path of the charge carrier in the second semiconductor barrier injected from the metal base. The metal base comprises two or more metal layers and has an average thickness based on a multi-layer mean free path of the charge carrier.

Metal base hot-electron transistors (HETs) may be used for high-speed applications due to the fast electron transport speed and low resistive-capacitive (RC) delays across a metal base region of the transistor. However, some metal base HETs may exhibit low carrier transmission rate from the metal base into the semiconductor collector due to 1) the scattering inside the metal base, 2) the quantum reflection of carriers at the large potential step at the base-collector interface, and 3) the backward scattering by phonons inside the collector, which may cause the current gains of the metal base HETs to be less than unity.

Hot-electron transistor having multiple MSM sequences