A diffusional gas transfer system and method having a membrane disposed between a first gas domain and a second gas domain. The first gas domain includes a first mechanism for directing a first environmental gas flow transversely over and in contact with a first surface of the membrane. The second gas domain includes a second mechanism for directing a second environmental gas flow transversely over and in contact with a second surface of the membrane. The membrane is a diffusional gas transfer medium having a multiplicity of tortuous pathways extending from the first surface of the membrane to the second surface of the membrane. The void volume fraction of the membrane is at least 0.2. The membrane is capable of substantially blocking the transfer of particles from the first gas domain to the second gas domain, while permitting the diffusion of gases between the first and second gas domains.

Various ventilation systems have been used to control the content of carbon dioxide and oxygen in enclosed spaces. The enclosed space could be for example an automobile, a home, a high rise building, the inside of a respirator, a factory, a clean room, or a hospital room. The ventilation systems remove excess carbon dioxide and replenish depleted oxygen from the enclosed spaces.
In carrying out this type of operation, conventional ventilation systems typically use a filter media to prevent airborne particles from entering the enclosed space from an external environment. The air typically passes normally or perpendicularly through the filter media, and an energy source is used to force the air therethrough. If the air entering the enclosed space is not filtered, the inhabitants may suffer from toxic or allergic reactions to inanimate airborne particles, or may suffer adverse health effects from airborne microorganisms. Air must be purged from the enclosed space through an exhaust port when filtered air is forced into the enclosed space to prevent pressure build up.
Conventional ventilation's systems possess a number of drawbacks.
A first drawback is that it is difficult for particle filters to remove essentially all airborne particulates from the admitted air without using so much filter media that high pressure drops are created when the air passes through the filter media. Consequently, conventional filtration systems typically allow a substantial number of particles to enter the enclosed space in the admitted air stream.
A second drawback is that the admitted air must pass normally or perpendicularly through the filter media. When particle-containing air flows through a filter in such a manner, the filter's pores become filled with the particles and a corresponding increase in pressure drop results. The filter must be frequently replaced if good flow rates are to be maintained.
A third drawback is that significant amounts of energy are needed in conventional systems to force the admitted air through the filter media. Filters whose pores are not plugged nonetheless exhibit significant frictional forces or barriers to air entry. The energy requirements may be substantial in large structures.
Another drawback is that conventional ventilation systems need an exhaust network to allow excess air to be purged from the enclosed space. Otherwise it would be very difficult, if not impossible, to carry out a continuous ventilation operation.
Conventional ventilation filtration systems also are disadvantageous because they require significantly more air flow than is needed for oxygen consumption. Consider an enclosed space surrounded by contaminated air where filtered air is forced into the enclosed space to provide oxygen for the inhabitants and internal ambient air is removed therefrom to avoid increased pressure. Carbon dioxide passes from the enclosed space to the surrounding environment in the exhaust air stream. It is commonplace to supply 20 cubic feet per minute (566 liters per minute) of outside air per building inhabitant. For sedentary office workers, CO.sub.2 is generated at a rate of about 0.35 liters per minute (lpm) per inhabitant. Under these conditions, and at a steady state, the outside air having a CO.sub.2 concentration of about 0.03% would have a CO.sub.2 concentration of 0.09% when exhausted from the building ((0.35 lpm/566 lpm)+0.03%=0.09%). CO.sub.2 levels above 0.1% may be uncomfortable or adverse to the inhabitants. Outside air at sea level generally has an O.sub.2 concentration of 20.95%. After an inhabitant consumes approximately 0.28 liters per minute of O.sub.2, air having an O.sub.2 concentration of about 20.0% is exhausted from the enclosed space. This value of exhausted oxygen reflects a dynamic room oxygen concentration that is much higher than needed for safety. CO.sub.2 levels, therefore, govern ventilation rates from the standpoint of satisfying the physiological needs of people in enclosed spaces.
U.S. Pat. No. 3,369,343 (Robb) discloses the use of a permeable nonporous wall made of materials such as silicone rubber to exchange CO.sub.2 or O.sub.2 via permeation. Permeation as used in Robb is limited to a solution process in which the gases dissolve in the film and then diffuse through the film in the dissolved state. The film forms a pore free barrier to any solid, liquid or gas which does not chemically dissolve in the silicone rubber. Robb discloses various air purifying systems utilizing the silicone rubber membranes.
Soviet Patent No. SU 1710951 discloses a ventilation device that uses a nuclear membrane as a gas exchange medium to ventilate a closed structure. Partial pressures of O.sub.2 and CO.sub.2 on opposite surfaces of the nuclear membrane provide a driving force for the gas exchange. Additionally, the membrane is useful in blocking harmful aerosols and micro particles present in the outside air. Nuclear membranes are typically formed by accelerating atomic particles at a polymeric film to form generally parallel holes through the film. The holes in nuclear membranes can become clogged or loaded with particles, rendering the membrane less effective as a gas exchange medium.
Soviet Patent No. SU 1119197 discloses a respirator using a thin elastic porous gas permeable polymeric membrane as a diffusional gas exchange medium. The membrane is disclosed as a nuclear filter type made of polyethyleneterephthalate or polycarbonate film having a porosity of about 10% (at higher porosities the mechanical strength of the filter falls off quickly). It is alleged that protection from aerosols of any size can be provided by the porous polymeric membranes having a pore size from 3 to 0.03 micrometers. Due to the high uniformity of pore sizes, the efficacy of protection from aerosols having sizes equal to or greater than the pores is generally 100%.

Diffusional gas transfer system and method using same


To provide a method for producing a ceramic porous material which has a high strength, though it has a high porosity, and which is excellent in permeability without dust generation. In a ceramic porous material having a three-dimensional mesh-like skeleton structure with a large number of substantially spherical adjacent cells communicating with each other via communication holes, the crystal particle size at the rim of each communication hole in the skeleton structure is provided substantially equal to the crystal particle size in the other parts.

1. Field of the Invention
The present invention relates to a ceramic porous material having a bubble-like appearance to be used as a filter, a bubbler, a gas supplying member, a semiconductor producing device member, an artificial bone, a cell culturing supporter, an artificial organ, a catalyst supporter, or the like, and a production method therefor.
2. Description of the Related Art
Conventionally, as a ceramic porous material of this kind, one having a three-dimensional mesh-like skeleton structure with a large number of substantially spherical adjacent cells (pores) communicating with each other via communication holes has been known (see the official gazette of the Japanese Patent Laid Open Application (JP-A) No. 4-202071 (U.S. Pat. No. 2,506,502).
The ceramic porous material is produced by preparing a slurry by dispersing or dissolving in a solvent a ceramic powder and an organic substance to be hardened by the cross-linking polymerization, adding a cross-linking agent to the slurry, molding and hardening (gellation molding) in an agitated and bubbled state, drying the compact and baking (fireing, sintering).
However, according to the conventional ceramic porous material, problems are involved in that the mechanical strength is low, dusts (particles) are generated, and the transmissivity is poor.
In order to find the cause of the problems, the periphery of the communication holes in the skeleton structure was observed with a scanning type electron microscope so that an abnormal form of crystal particles forming the rim of the communication holes was observed.
That is, at the rim of the communication holes, single particles of a cockscomb shape and a cactus shape were observed. Moreover, the fact that minute holes of the size equivalent to the crystal particle size, communicating the adjacent pores were found at the rim part of the communication holes and the growth of the crystal particles are restrained at the rim of the communication holes was found.
It can easily be assumed that the above-mentioned crystal particle growth abnormal part became the breakage starting point when the external force was applied to the ceramic porous material so as to cause stress concentration, and furthermore, the cockscomb shaped and cactus shaped parts were peeled off so as to generate dusts.
Accordingly, it is considered that the abnormal form of the crystal particle growth forming the rim of the communication holes is generated in the production process of the ceramic porous material.
That is, the cells of the slurry stage are formed by the liquid medium containing the ceramic powder, and in most cases by the aqueous slurry. The slurry before hardening is moved by the surface tension and parts between the adjacent cells are partially thinned and broken so as to form the communication holes. The communication hole rims linking the cells accordingly formed are of a sharp shape because they are broken after thinning and the viscosity of the slurry at the time of breaking is high and the flowability after film breakage to rounding the rims is low. Or in the case of forming the communication holes by breaking the thin film at the time of expansion and shrinkage of the air in the cells due to the temperature change after drying, or the like, the small pieces of the dried substances generated by the breakage can be adhered on the wall surface of the cells.
The average particle sizes of the crystal particles at the rim of the communication holes of the alumina ceramic porous material of the 80% porosity (baked at 1,600° C. for 2 hours in the air), at a position 2 μm away from the rim, and at a position 4 μm away from the rim were 0.80 μm, 1.67 μm, and 1.81 μm, respectively, and it was 8.52 μm at a position 100 μm away from the rim. The average particle sizes of the crystal particles at the rim of the communication holes of the hydroxyl apatite porous material of the 75% porosity (baked at 1,200° C. for 2 hours in the air), at a position 0.5 μm away from the rim, at a position 1 μm away from the rim, and at a position 1.5 μm away from the rim were 0.42 μm, 0.5 μm, and 0.55 μm, and 0.62 μm, respectively. Moreover, the average particle sizes of the crystal particles at the rim of the communication holes of the silicon carbide porous material of the 75% porosity (baked at 2300° C. for 2 hours in the reduced pressure argon gas atmosphere), at a position 2 μm away from the rim, and at a position 4 μm away from the rim were 0.49 μm, 4.38 μm, and 4.38 μm, respectively.

Production method for ceramic porous material


A projectile with a payload protection mechanism protects, prior to and during firing, a fragile payload, where the payload must be positioned forward in the nose of the projectile, within a frangible ogive which provides little protection to rough handling, at time of downrange function. The payload protection mechanism allows the payload to move axially within the projectile, and initially slid rearward in the more robust metal body of the projectile. The payload is retained within the body by a locking and release mechanism, until the launching of the projectile triggers (by environmental forces such as setback or spin) the release of a locking and release mechanism. Unlocking the mechanism allows the payload to slide forward within the projectile into the ogive so the payload can function as required.

Projectile-delivered payloads are used in a multitude of applications. For example, military or law enforcement applications, remote sensing applications and space applications are just a few of the many potential uses for projectiles housing payloads.
In certain applications, the payload must be positioned forward in the nose of the projectile at time of downrange function, within a frangible ogive which provides little protection to rough handling.
A need exists for an apparatus which allows for a payload to be better protected while not impacting operation of the payload.

Payload protection and deployment mechanism

The United States of America as Represented by the Secretary of the Army


The invention provides a low-wear screw structure which comprises a screw head, a rod body, a first thread and at least a crushing rib, wherein the rod body extending out from the screw head and being successively formed with a rod extension part, a reaming part and a taper part, the first thread being annularly arranged on an outer peripheral surface of the rod body at a distance from the taper part to the rod extension part through the reaming part, the crushing ribs being arranged on the rod body at the reaming part, wherein a first included angle is formed between the first side surface and the outer peripheral surface of the rod body, a second included angle is formed between the second side surface and the outer peripheral surface of the rod body, and the first included angle is different from the second included angle.

When the wood screw is locked into the wood, the wood with higher hardness has high density and strong resistance, and the friction force between the screw teeth of the wood screw and the wood block is gradually increased in the screwing process, so that the wood screw needs more and more force to be locked into the wood. Therefore, the abrasion of the screw teeth is easy to occur, and the wood screw is unfavorably locked into the wood. The wood screw also needs more and more force to be locked into the wood, and the wood crack is easy to occur. Accordingly, there is a need for a solution to these problems.


A transmit power control circuit, which can control a transmit power of a transmit power control circuit through wide dynamic range and can reduce an insertion loss. A first attenuator inputs a radio-frequency signal and outputs an output signal after controlling the inputted radio-frequency signal. A selective switch inputs the output signal of the first attenuator, and outputs it to one of a main transmission line and an auxiliary transmission line. One directional coupler is provided to the main transmission line and has one and another ends respectively connected to selective switches. The selective switches are switched by a signal from a microcomputer. When the selective switch is switched to the main transmission line, one end of the directional coupler is connected to a terminator, and another end thereof is connected to a wave detector. On the contrary, when the selective switch is switched to the auxiliary transmission line, one end of the directional coupler is connected to the auxiliary transmission line, and another end thereof is connected to a terminator.

This application is based upon Japanese Patent Application No. Hei. 11-133165 filed on May 13, 1999, the contents of which are incorporated herein by reference.
1. Field of the Invention
This invention relates to transmit power control circuits, and particular to a transmit power control circuit suitable for a radio communication apparatus.
2. Related Art
Recently, transmit power (power level of transmit output signal) is controlled in a radio communication apparatus such as a portable telephone.
FIG. 5A shows a schematic block diagram of a transmit power control circuit according to a related art. The transmit power control circuit is basically provided with an attenuator 51 and a power amplifier 52. The attenuator 51 inputs a radio-frequency signal (RF signal) as an input signal, attenuates the input signal by attenuation depending on a control voltage from a control device such as a not-shown microcomputer, and outputs the attenuated signal as an output signal. The power amplifier 52 amplifies the output signal of the attenuator 51 with a predetermined gain, and supplies the amplified signal to an antenna as a transmit output signal. According to this transmit power control circuit, the transmit power of the transmit output signal can be controlled by changing the attenuation of the attenuator 21, as shown in FIG. 5B.
Furthermore, when the transmit power is detected to control the transmit power, as shown in FIG. 5A, a directional coupler 53 is provided at later stage of the power amplifier 52. One end of the directional coupler 53 is connected to a terminator 54, and another end is connected to a wave detector 55, so that voltage in proportion to the transmit power is measured by detecting the power by using the wave detector 55.
However, in the transmit power control circuit described in the above, since a dynamic range of the attenuation of the attenuator has a limitation, it is difficult to control the transmit power through wide range. Particularly, in a case where the CDMA (Code Division Multiple Access) method is applied to the radio communication apparatus such as the portable telephone, since the radio communication apparatus needs to control own transmit power through wide dynamic range based on a command from a base station, it is difficult to apply the above-described transmit power control circuit to the radio communication apparatus using the CDMA method.
This invention has been conceived in view of the background thus far described and its first object is to control a transmit power of a transmit power control circuit through wide dynamic range.
Its second object is to control a transmit power of a transmit power control circuit through wide dynamic range and to reduce an insertion loss.
According to the present invention, when the output signal of the variable gain circuit is outputted to the main transmission line, one end of the directional coupler is connected to a first terminator, and another end of the directional coupler is connected to a wave detector. On the contrary, when the output signal of the variable gain circuit is outputted to the auxiliary transmission line, the one end of the directional coupler is connected to the auxiliary transmission line, and said another end of the directional coupler is connected to a second terminator.
According to the above structure, a transmit power can be controlled through wide dynamic range by switching between the main transmission line and the auxiliary transmission line. Furthermore, since the directional coupler is used both for detecting the transmit power using the wave detector and for controlling the transmit power using the auxiliary transmission line, by selecting one of them, an insertion loss can be reduced.
According to another aspect of the present invention, a first switching circuit selects one of a main transmission line (A) and an auxiliary transmission line (B). An amplifying circuit, provided to the main transmission line, amplifies the output signal of the variable gain circuit, which is outputted to the main transmission line. A one end of a directional coupler is electrically connected to an auxiliary transmission line, and another end of the directional coupler is electrically connected to a terminator.
According to the above structure, a transmit power can be controlled through wide dynamic range by switching between the main transmission line and the auxiliary transmission line.


A vehicle for use on a live line. The vehicle is provided with three coplanar traction wheels mounted on a frame and spaced along a first longitudinal axis parallel to the live line and above therefrom. The vehicle is also provided with two movable coplanar pressure wheels mounted on the frame and spaced along a second longitudinal axis parallel to the line and below therefrom. The vehicle has a driving motor mounted on the frame, for driving the traction wheels. The motor has a source of energy, such as batteries. The vehicle has a pressure mechanism mounted on the frame and coupled to the pressure wheels, for maintaining the line squeezed between the traction wheels and the pressure wheels. The vehicle has a control mechanism coupled to the motor for controlling the motor. Thereby, in use, the vehicle is moved along the line. The vehicle can also be provided with a de-icing tool. The de-icing tool has a collar with two parts opening and closing around the line. The collar supports several blades concentrically spaced apart from each other and forming an open cone in a forward moving direction of the vehicle.

The present invention relates to an improvement to small vehicles known as remotely operated vehicles (ROVS) which move along a conductor of a power line or an overhead earth wire.
The present invention also relates to a de-icing tool which is mounted on a remotely operated vehicle.
ROVs are known devices which are used to take measurements of electric, physical and/or environmental parameters and to check certain conditions associated with the power lines mounted between pylons.
The following documents describe known ROVs: U.S. Pat. No. 4,904,996 (FERNANDES); U.S. Pat. No. 5,901,651 (BOYD); and PCT patent application WO 94/18046 (SCOTT).
The main problem associated with known ROVs is their difficulty to generate a traction force (or pulling force) sufficiently strong for moving along a power line. Typical power lines can be made out of steel or aluminum and can have various diameters. In some cases, the line can be wet and, in other cases, it can even be covered with ice residues. The problem of traction arises particularly from the choice of materials of which are made up the wheels.
A known ROV has a weight of approximately 110 lb and a measured pulling force of 75 lb. This ROV has only two traction wheels of simplistic form. It measures about 25 in.xc3x9710 in.xc3x9714 in. The size of this ROV is somewhat large, and consequently cumbersome for handling and for using on live lines. Furthermore, this ROV is not designed for moving along a live line, which can be wet or covered with ice residues.
De-icing tools for cables are described in the following documents: U.S. Pat. No. 4,227,304 (OKAMURA) and JP-1081613 (MATSUMOTO). These de-icing tools are not adapted for being mounted on an ROV.
A first object of the present invention is to provide an ROV having a traction force sufficient for operating on a live line, which is wet or covered with ice residues.
A second object of the present invention is to provide an ROV which is smaller than most known ROVs, which is easier to handle, and which facilitates the operations of cleaning, de-icing and inspection of power lines.
A third object of the present invention is to provide an ROV which can be move along a live line and which can be easily be installed thereon.
A fourth object of the present invention is to provide an ROV which can be adapted to fit different conductors diameters, and can cross conductor joints of live lines.
According to the present invention, there is provided a vehicle for use on a live line, comprising:
three coplanar traction wheels mounted on a frame and spaced along a first longitudinal axis parallel to the live line and above therefrom;
two movable coplanar pressure wheels mounted on the frame and spaced along a second longitudinal axis parallel to the line and below therefrom;
a driving motor mounted on the frame, for driving the traction wheels, the motor having a source of energy;
pressure means mounted on the frame and coupled to the pressure wheels, for maintaining the line squeezed between the traction wheels and the pressure wheels; and
control means coupled to the motor for controlling the motor; and thereby in use, the vehicle is moved along the line.
Another object of the present invention is to provide a de-icing tool for breaking the ice which has accumulated on a live line or on overhead earth wire.
According to another aspect of the present invention, there is also provided a de-icing tool mounted on a vehicle for use in a live line, comprising:
a collar having two parts opening and closing around the line, the collar supporting blades concentrically spaced apart from each other and forming an open cone in a forward moving direction of the vehicle.

Remotely operated vehicle for inspection and intervention of a live line


A 4-methyl-1-pentene resin composition comprising (A) 20 to 60 parts by weight of poly-4-methyl-1-pentene or a copolymer chiefly composed of 4-methyl-1-pentene, (B) 30 to 60 parts by weight of an ethylene/butene copolymer, (C) 5 to 40 parts by weight of poly-1-butene or a copolymer chiefly composed of 1-butene and another .alpha.-olefin, and (D) 0 to 30 parts by weight of a propylene/butene copolymer is provided. The composition of the present invention has excellent heat resistance, transparency, gas permeability, mold releasability, liquid drainability, heat seal strength, and impact resistance. Especially, it has excellent adhesive properties to 4-methyl-1-pentene resin and other resins and is preferably used for the production of laminated products.

1. Field of the Invention
This invention relates to an industrially useful resin composition, especially an adhesive resin composition for the production of a laminated body, and to a laminated body using the resin composition.
More specifically, the invention relates to a 4-methyl-1-pentene resin composition preferably used for the production of a laminated body having excellent heat resistance, transparency, gas permeability, mold releasability and liguid drainability as attributes of 4-methyl-1-pentene polymer, and having excellent heat sealing strength, excellent mechanical properties such as impact resistance and particulary, excellent in adhesiveness not only to 4-methyl-1-pentene resin but also to other type of resins, and also relates to a laminate body such as bottles, containers, films and sheets using the resin composition.
2. Prior Art
4-Methyl-1-pentene polymers by utillizing its good properties such as heat resistance, transparency, gas permeability and releasability plan to extend uses to various usages such as tableware for electronic cooking ovens, releasable films for FPC, paper or baking cartons for the step of making artificial leather, medical treatment syringes or containers for preserving medicines, agricultural chemicals, cosmetics or blood or measuring instruments therefor and preservation containers for vegetables and fruits. However, there are problems in that their heat sealing strength and impact resistance are inferior, and their practical properties are desired to be increased further. In the case of forming containers, it was desired to improve their rigidity, especially their properties such as their rigidity at high temperatures. Thus, the 4-methyl-1-pentene type resin and another thermoplastic resin such as a polyolefin, polyesters or polyamides were investigated to form multilayered structures. For example, it is investigated that 4-methyl-1-pentene type resin and another polyolefin resin having excellent heat sealability and impact strength, especially an ethylene type polymer, are multilayered to supplement each other.
However, 4-methyl-1-pentene polymer has poor adhesiveness to another resin such as an ethylene type polymer, even when both belong to the same category of olefin polymer, owing to its low surface tension. Accordingly, it was difficult to directly adhere the above resin and to prepare multilayer laminate.
For this reason, adhesive resins to be used as an adhesive layer to be an intermediate medium have been variously investigated (Japanese Patent Publication No. 59768/1992, Japanese Laid-Open Patent Publication No.145844/1985). There are uses in which a certain result has been obtained by these techniques, but there are new uses in which a further improvement in performance is required for further improvement. 4-Methyl-1-pentene resin composition in which a balance in properties is good, a laminated body using a 4-methyl-1-pentene composition and a 4-methyl-1-pentene resin composition for adhering for the preparation of a laminated body are desired in the above new uses. Furthermore, a thermoplastic resin other than the polyolefins was also investigated to form multilayer laminate with the 4-methyl-1-pentene resin (Japanese Laid-Open Patent Publication No. 107438/1992). But according to this technique, interlayer adhesiveness was not enough, and a further improvement was desired.

4-methyl-1-pentene resin composition and a laminated body using the resin composition


A method of producing an optical waveguide grating by exposure to light. An optical waveguide having a core composed of a material wherein the refractive index changes due to exposure to UV light is formed into an optical waveguide grating by applying a grating portion formation step wherein a grating portion is formed by irradiation with UV light at a predetermined spacing, and an overall exposure step after formation of the grating portion wherein the entire grating portion is irradiated with UV light. As a result, the effective refractive index of the grating portion is changed so as to allow the central wavelength to be adjusted without changing the rejection. Consequently, the grating properties can be precisely and easily controlled.

1. Field of the Invention
The present invention relates to optical waveguide gratings and production methods therefor.
2. Description of the Related Art
Optical waveguide gratings can be obtained by making regular periodic changes, such as periodic changes in the refractive index of the core, along the longitudinal direction of optical fibers or planar optical waveguides.
In general, gratings can be divided into radiative mode-coupled types and reflective mode-coupled types. Radiative mode-coupled gratings are capable of attenuating light of specific wavelengths due to radiation from the optical waveguide by coupling modes propagating in the core with modes propagating in the cladding. Reflective mode-coupled gratings reflect light of specific wavelengths by coupling modes propagating through the core in a positive direction and modes propagating through the core in the opposite direction (negative direction).
For example, in the case of optical fiber gratings formed by making periodic changes in the core refractive index of optical fibers, radiative gratings are obtained by making the period of the changes in the core refractive index (hereinafter sometimes referred to as the grating pitch) approximately several hundred microns, and reflective gratings are obtained by making the grating pitch approximately 1 micron.
Radiative mode-coupled gratings have wavelength-transmission loss properties (transmission spectra) as shown in FIG. 4, wherein the transmission loss of light in a specific wavelength band is selectively increased. The width of the wavelength band with an increased transmission loss is referred to as the rejection bandwidth, the central wavelength thereof is referred to as the central wavelength of the rejection band, and the magnitude of the change in transmission loss is referred to as the rejection.
Wavelength-transmission loss properties (transmission spectra) similar to those of FIG. 4 can also be obtained by reflective mode-coupled gratings.
These grating properties of optical waveguide gratings are known to change with the parameters of the gratings, i.e. the amount of change in the core refractive index, the grating pitch, the grating shape (profile of the core refractive index), the grating length in the longitudinal direction of the optical fiber, and the effective refractive index.
The following Table 1 summarizes the influence that each parameter of a grating has on the grating properties. In the table, .times. indicates no influence, .smallcircle. indicates some influence, and .DELTA. indicates a small influence. Additionally, the arrows .uparw. (.dwnarw.) indicate whether the value of the cladding property will increase (decrease) in response to an increase in the parameter value.
Precise control of the central wavelength and the rejection are important when using the optical waveguide gratings as optical components in optical communication systems.
TABLE 1 ______________________________________ Central Rejection PARAMETER Wavelength Rejection Bandwidth ______________________________________ Change in Refractive Index .smallcircle..uparw. .smallcircle..uparw. x Grating Pitch .smallcircle..uparw. .DELTA. x Grating Shape .smallcircle. .smallcircle. x Grating Length x .smallcircle..uparw. .smallcircle..dwnarw. Effective Refractive Index .smallcircle..uparw. x x ______________________________________
As conventional methods for making periodic changes in the core refractive index of optical waveguide gratings, there are methods which take advantage of the properties of silica glass doped with germanium, of which the refractive index will increase when exposed to strong UV radiation, depending on the amount of exposure.
For example, methods are known wherein a silica glass based optical fiber having a core doped with germanium oxide is hydrogenated in a hydrogen-pressurized container (at 100 atm), and then either exposed to UV radiation at a constant period along the longitudinal direction of the optical fiber using a photomask, or exposed to UV radiation at regularly spaced intervals along the longitudinal direction of the optical fiber.
FIG. 7 shows an example of a conventional optical fiber grating production apparatus.
In the drawing, reference numeral 11 denotes an excimer laser, which can generate UV light having a wavelength of 248 nm. Reference numeral 12 denotes an optical system, which is constructed to increase the spot size of the UV light emitted from the laser 11 to a predetermined size on the order of millimeters to tens of millimeters. Reference numeral 13 denotes a metallic mask, having slits which are cut at regularly spaced intervals on the order of tens to hundreds of microns. Reference numeral 14 denotes an anchoring block to which is anchored an optical fiber 1 having the jacket layer 4 partially removed. The UV light emitted from the laser 11 is directed by the optical system 12 through the mask 13 so as to irradiate the portion of the optical fiber 1 with the jacket layer 4 removed.
In order to make an optical fiber grating using an apparatus having this type of structure, the UV light should be emitted from the laser 11 so as to irradiate the optical fiber 1 through the mask 13. As a result, the core refractive index is raised at only the portions of the optical fiber 1 which have been exposed to UV light, so as to form a grating portion 5 in which the core refractive index periodically changes.
However, while this conventional production method requires the grating properties to be controlled by means of the shape of the mask 13 and the UV light irradiation conditions, such control is complicated because the central wavelength and the rejection cannot be independently controlled.
For example, with the above-mentioned production method, it is necessary to find the optimum combination for the shape of the mask 13 (grating pitch, grating shape) and the UV light irradiation conditions (UV light intensity, irradiation time) before forming the grating portion. In order to determine the shape of the mask 13 to use, a number of different irradiation conditions are tried on a first mask 13, and if the desired central wavelength and rejection are not able to be obtained, then the shape of the mask 13 is changed and the irradiation conditions are tried on the new mask. This process of trial and error must be repeated many times, so that a lot of time is expended in order to select the shaped of the mask 13 and the irradiation conditions.
Particularly in the case of radiative mode-coupled gratings, several masks must be used in order to adjust the central wavelength and rejection to their desired values because the amount of change in the central wavelength is large in comparison to the amount of change in the core refractive index.
Additionally, the monitoring of the transmission properties during the UV light irradiation process is difficult because the amount of change in the refractive index changes over time, i.e. the transmission properties (central wavelength and rejection) change over time, until the hydrogen is removed by dehydrogenation.
Furthermore, it is impossible to irradiate the mask with a uniform UV beam because the spatial distribution of the intensity of a laser beam is not uniform, i.e. the laser beam intensity within the spot of a laser is non-uniform. For this reason, the core refractive index change in each part of the grating portion 5 cannot be made uniform, so as to make the transmission spectra of the optical fiber gratings broader or asymmetric, thereby degrading the grating properties.
FIG. 8 shows another example of a conventional optical fiber grating production apparatus. The elements which are identical to those in FIG. 7 are given the same reference numerals and their explanations will be omitted below.
Reference numeral 22 denotes an optical system which is constructed so as to converge the UV light emitted from the laser 11 to a predetermined spot size on the order of tens to hundreds of microns. Reference numeral 24 denotes a mobile stage to which is affixed an optical fiber 1 having the jacket layer 4 partially removed. The mobile stage 24 is controlled so as to be capable of jogging by predetermined distances along the longitudinal direction of the optical fiber. The UV beam emitted from the laser 11 passes through the optical system 12 to irradiate the portion of the optical fiber 1 having the jacket layer 4 removed.
In order to produce an optical fiber grating using an apparatus of this structure, a UV beam is first emitted from the laser 11 for irradiation of the optical fiber 1. After irradiation for a standard period of time, the mobile stage 24 is jogged in order to shift the optical fiber 1 in the longitudinal direction by a predetermined distance, then the optical fiber 1 is once again exposed to the UV beam for a standard period of time. This process of irradiation with the UV beam followed by shifting of the optical fiber 1 is repeated until the total distance by which the optical fiber 1 has shifted has reached a predetermined distance, thereby completing the process. In this way, the grating portion 5 can be formed because the core refractive index is changed at only the portions of the optical fiber 4 which are exposed to the UV beam.
According to this method, the core refractive index change in the grating portion 5 can be made uniform by repeatedly duplicating UV beam irradiation under identical irradiation conditions. However, since the grating pitch is determined by the spot size of the laser beam and the shifting pitch of the optical fiber 1, the spot size of the laser beam and the shifting pitch of the optical fiber 1 must be changed in order to change the grating pitch. While the spot size of the laser beam can be changed by using slits, lenses, or a combination of these, it is difficult to precisely control the spot size by means of any of these methods. Therefore, there is a drawback in that a complicated process of finding the laser beam irradiation conditions is required in order to change the grating properties, thus making design changes difficult.
On the other hand, reflective mode-coupled gratings can achieve wavelength-reflected optical intensity loss properties (reflection spectra) such as shown in FIG. 20, wherein the reflected optical intensity of light in a specific wavelength band is selectively increased. The width of this wavelength band with an increased reflected optical intensity is referred to as the reflection bandwidth, of which the central wavelength is referred to as the central wavelength of the reflection band, and the proportion of the reflected optical intensity with respect to the incident optical intensity is referred to as the reflection.
These grating properties are known to change according to the parameters of the grating such as the amount of change in the core refractive index, the grating pitch, the grating shape (profile of core refractive index change) the grating length along the longitudinal direction of the optical fiber, and the effective refractive index. The effective refractive index is a refractive index which is locally averaged along the longitudinal direction and the transversal direction of the core of the optical fiber, which can be experimentally determined by the following relation: 2.pi./.LAMBDA..multidot.effective refractive index=propagation constant at central wavelength of reflection band (wherein .LAMBDA. is the grating pitch).
In this case, "locally along the longitudinal direction of the optical fiber" signifies a region having a length of about a single period of the grating.
FIG. 21 shows a closeup of the relevant portions when using a phase mask with the method shown in FIG. 7.
For example, one known method for making a reflective mode-coupled grating is to hydrogenate a silica optical fiber 31 having a core 31a doped with germanium oxide in a hydrogen-pressurized container (at 100 atm), then to expose the optical fiber 31 to a UV beam 34 via a phase mask 32 composed of a silica glass plate having a plurality of slits formed therein at regular intervals. According to this method, when the UV beam 34 is orthogonally incident on the top surface of the phase mask 32, the diffracted light forms an interference pattern. This interference pattern causes periodic changes in the intensity of the UV beam 34 irradiating the optical fiber 31, so as to form a grating portion 310 having periodic changes in the refractive index of the core 31a.
As another technique for making reflective mode-coupled gratings, there is a technique referred to as apodization, wherein the core refractive index change is gradually varied along the longitudinal direction of the optical fiber 31. For example, if the change in the core refractive index at the grating portion 310 due to exposure to the UV beam 34 is constant along the longitudinal direction of the optical fiber 31, then anomalous ripples will occur around the central wavelength in the reflection spectrum as shown in FIG. 22. Apodization is a process for preventing the occurrence of these anomalous ripples by varying the core refractive index change in the grating portion 310 along the longitudinal direction of the optical fiber 31 so as to outline the curve shown in FIG. 23, instead of making the core refractive index change constant along the longitudinal direction of the optical fiber 31. In the graph of FIG. 23, the solid lines indicate the core refractive index change along the longitudinal direction of the optical fiber 31 and the dashed curve indicates the distribution of the core refractive change along the longitudinal direction of the optical fiber 31.
The shape of the distribution of the core refractive index change can be made into a variety of shapes without being restricted to the example of FIG. 23, and the reflection properties of the reflective mode-coupled gratings are known to change depending on the differences in the shape of the distribution of the core refractive index change (see BSTJ., vol. 55, pp. 109-126, 1976, "Filter Response of Nonuniform Almost-periodic Structures", H. Kogelnik et al.).
Specifically, as methods for performing apodization during the formation of the grating portions such as the method wherein the grating portions are formed by using a phase mask 32 as explained above, there is a method wherein the UV beam is shifted along the optical fiber 31 while changing the irradiation intensity of the UV beam 34, or a method wherein the optical fiber 31 and phase mask 32 are shifted in the longitudinal direction of the optical fiber 31 while changing the irradiation intensity of the UV beam 34 and holding the UV beam 34 stationary.
However, in the case wherein the UV beam 34 is moved, the structure of the optical system in the production apparatus becomes complicated, so that the costs required for production such as those for temperature and humidity regulation rise and it becomes extremely difficult to shift the UV beam 34 with precision.
On the other hand, in the case wherein the optical fiber 31 and the phase mask 32 are moved, the optical fiber 31 and phase mask 32 are affected by the vibrations of drive devices such as motors. Particularly when forming the grating portion using a phase mask 32, the positional precision of the phase mask 32 and the optical fiber 31 must be in submicron units. For this reason, when the optical fiber 31 and the phase mask 32 are moved, extreme care is necessary in order to stabilize them to prevent mutual displacement of their relative positions, thus requiring the use of expensive fixation devices and increasing the number of production steps.

Method of making an optical waveguide grating with two dissimilar irradiating steps

610 Moa-Crest Alphas Sakura, 121-1 Tamachi


A spray actuator which has an inlet which communicates with a discharge orifice outlet via a passageway and a discharge cavity. The discharge cavity accommodates a central post therein which supports a plurality of axial fins that may be each provided with stop shoulder. An insert member, carrying a discharge orifice, is received within the discharge cavity and engages with the support fins and the stop shoulders. The insert member is provided with an annular lip which has an interference fit with the inner side wall, defining the discharge cavity, to retain permanently the insert member within the discharge cavity. An end face of the side wall of the insert member abuts against the stop shoulders to prevent overinsertion of the insert member into the discharge cavity and thereby prevent inadvertent deformation or crushing of the mechanical break-up. An end face of the central post has a mechanical break-up molded therein which impart a tangential spin to pressurized product as the product flow therethrough.

One major the problem associated with the known prior art mechanical break-ups, for aerosol spray actuators, is that the mechanical break-ups are frequently crushed, deformed or distorted during the manufacturing process. Such crushing, deformation and/or distortion of the mechanical break-up causes an alteration of the product flow characteristics, through supply passages provided in the mechanical break-up, and thus the discharge characteristics of the product from the discharge orifice of the spray actuator. If the mechanical break-up is significantly crushed, deformed or distorted, adequate flow of product through the mechanical break-up may be significantly restricted or prevented. Therefore, such alteration is undesirable and should be avoided.


A system for controlling a multiple cylinder internal combustion engine having a plurality of cylinders with electronically actuated valves (EVA) is presented. The system is designed to improve the torque delivery of an EVA engine that operates a portion of cylinders in an HCCI combustion mode.

Vehicles having an internal combustion engine can operate in a variety of modes. As one example, an engine may operate in a spark ignition (SI) mode, wherein a charge of a mixture of air and fuel is ignited by a spark performed by a sparking device within a combustion chamber. As another example, an engine may operate in a compression ignition mode, wherein a mixture of air and fuel are compressed within a combustion chamber by a piston, causing ignition of the charge without necessarily requiring the addition of a spark from a sparking device.
One type of compression ignition known as homogeneous charge compression ignition (HCCI) utilizes compression of a substantially homogeneous mixture of air and fuel to achieve controlled auto-ignition (CAI). In HCCI engines, ignition occurs virtually simultaneously throughout a combustion chamber as a result of compression instead of spark ignition, making the combustion process challenging to control. HCCI engines are similar to conventional gasoline engines in having a homogeneous charge, but are similar to conventional diesel engines in having compression ignition. HCCI engines may be used to combine gasoline engine low emissions with diesel engine efficiency.
HCCI combustion engines typically change operation conditions more slowly than other combustion processes. The engine hardware used to control initial cylinder conditions such as internal residuals, intake air temperatures, and the combustion process stability window, limits dynamic response. Further, during HCCI operation and while transitioning to and from an HCCI combustion mode, undesired torque pulses can negatively impact driving torque response and noise, vibration and harshness.
In one approach, as described in U.S. Pat. No. 6,390,054, issued to Yang, an engine controller smoothes transitions between combustion modes by transitioning a first cylinder group between combustion modes and at a different time transitioning a second cylinder group between combustion modes. In another approach, as described in European Patent Application EP 1612393, by Almkvist et al., a method is provided for controlling a four-stroke multi-cylinder spark ignition combustion engine using cylinder deactivation of a subgroup of cylinders while another subgroup is working, during operation with an engine torque below a predetermined level. Almkvist further discusses a low engine speed strategy of operating inlet and exhaust valves normally and gradually opening a throttle until maximum engine stability is achieved.
However, the inventors herein have recognized disadvantages with either approach. First, an approach that smoothes undesired torque pulses while transitioning two separate cylinder groups between an HCCI combustion mode and a non-HCCI combustion mode, does not address undesired torque pulses arising from non-HCCI cylinders when an engine is no longer transitioning cylinders between combustion modes. Second, an approach that operates engine valves normally for non-HCCI cylinders and modulates a throttle for torque balancing affects all cylinders served by the throttle, irrespective of if the cylinders operate in HCCI mode.
The inventors herein have recognized the above-mentioned disadvantages and have developed a system that improves torque delivery in an engine with a first portion of cylinders operating in HCCI combustion mode and a second portion of cylinders not firing.


The present invention is directed to biologically mutant forms of the cell growth regulatory factor Oncostatin M. The Oncostatin M mutants of the invention comprise deletion, substitution and insertion mutants and may be prepared using recombinant DNA, in vitro mutagenesis and heterologous expression techniques. Oncostatin M mutants may be useful in eliciting Oncostatin M biological responses and, as such, may find a variety of therapeutic uses including but not limited to the treatment of neoplasias.

Oncostatin M, originally identified for its inhibitory effects on human tumor cell lines, was first isolated from phorbol 12-myristate 13-acetate (PMA)-induced human histiocytic lymphoma cells (Zarling et al., 1986, Proc. Natl. Acad. Sci. USA 83: 9739-9743) and from activated T lymphocytes (Brown et al., 1987, J. Immunol. 139: 2977-2983). The molecule is a heat and acid stable protein comprised of a single polypeptide chain M.sub.r =28,000. Like other naturally occurring growth regulators, Oncostatin M exhibits a variety of biological activities. Growth inhibition is observed with some, but not all, human tumor cell lines. In contrast, the growth of some normal fibroblasts, such as human foreskin fibroblasts or WI-38 cells, is stimulated by exposure to Oncostatin M (Zarling et al., 1986, Proc. Natl. Acad. Sci. USA 83: 9739-9743).
The gene for Oncostatin M has been cloned and sequenced, and an active form of recombinant Oncostatin M has recently been expressed in mammalian cells (copending U.S. Application Ser. No. 144,574 filed Jan. 15, 1988, which is incorporated herein by reference in its entirety). The mature form of Oncostatin M is a glycoprotein containing 228 amino acids, five of which are cysteine residues. The protein has an extremely hydrophilic carboxy terminal domain. Although Oncostatin M is not structurally related to other known cytokines, its mRNA contains an AU-rich region at its 3' untranslated end. This region in the Oncostatin M message is homologous to that of many cytokines, lymphokines and other growth-regulatory moelcules, suggesting a common mode of regulating gene expression. A cellular receptor for Oncostatin M has been found on a variety of mammalian cells. The major Oncostatin M receptor molecule is a specific protein of M.sub.r =150,000-160,000 (Linsley et al., 1989, J. Biol. Chem. 264: 6528 -6532).

Proteins with Oncostatin M activity and process for their preparation


A tracking error detection apparatus comprises a phase difference detection circuit for receiving two sequences of digital signals, and performing phase comparison using a distance between zerocross points of the two sequences of digital signals to output a result of phase comparison, and an LPF for generating a tracking error signal from the result of phase comparison. The phase difference detection circuit does not carry out phase composition in a position that is not appropriate as a target position to perform phase comparison, and outputs the result of phase comparison as a pulse signal corresponding to one sampling clock. Therefore, even when a disc is played at CAV or a flaw or the like exists on the disc, an accurate tracking error signal can be detected.

In recent years, a technique called "phase difference method" has been employed as a method for obtaining a tracking control signal from an optical disc on which information is recorded by projecting and depressing pits, such as a CD (Compact Disc) or a DVD (Digital Video Disc).
Japanese Published Patent Application No. Hei.2001-67690 discloses an example of such phase difference method.
Hereinafter, a conventional tracking error detection apparatus disclosed in Japanese Published Patent Application No. Hei.2001-67690 will be described with reference to FIG. 19.
FIG. 19 is a block diagram illustrating the construction of the conventional tracking error detection apparatus.
As shown in FIG. 19, the conventional tracking error detection apparatus is provided with a photodetector 101 having photoreceptor elements 101a, 101b, 101c, and 101d that receive a reflected light beam from a light spot, and outputting photo currents according to the amounts of light received by the respective photoreceptor elements; first to fourth current-to-voltage converter 102a to 102d for converting the photo currents outputted from the photodetector 101 into voltage signals; signal generators, i.e., first and second adders 103a and 103b, for generating two signal sequences whose phases change depending on a tracking error of the light spot, from the voltage signals obtained by the first to fourth current-to-voltage converter 102a to 102d; first and second analog-to-digital converters (ADC) 104a and 104b for obtaining first and second digital signal sequences from the two signal sequences; first and second interpolation filters 105a and 105b for subjecting the inputted digital signals to interpolation; first and second zero cross point detection circuits 106a and 106b for detecting zero cross points of the first and second digital signal sequences which are interpolated by the first and second interpolation filters 105a and 105b, respectively; a phase difference detection circuit 107 for detecting a phase difference between the zero cross point of the first digital signal sequence and the zero cross point of the second digital signal sequence; and a low-pass filter (LPF) 108 for subjecting a phase comparison signal outputted from the phase difference detection circuit 107 to band restriction to obtain a tracking error signal. The photodetector 101 comprises the four photodetector elements 101a, 101b, 101c, and 101d that are partitioned in a tangential direction and a perpendicular direction with respect to an information track that is recorded as an information pit line on the recording medium. Among the signals which are generated according to the amounts of light received by the respective photoreceptor elements and are outputted from the photodetector 101, the output signals from the photoreceptor elements positioned on a diagonal line are added by each of the first and second adders 103a and 103b, thereby generating two sequences of digital signals. Further, a zerocross point is a point where an inputted digital signal intersects a center level of the digital signal that is calculated from an average value or the like of the digital signal.
Next, the operation of the conventional tracking error detection apparatus will be described.
Initially, in the photodetector 101, the respective photoreceptor elements 101a, 101b, 101c, and 101d receive a reflected light beam from a light spot that is obtained by irradiating a track on an optical recording medium (not shown) with a light beam, and output photo currents according to the amounts of received light.
The photo currents outputted from the respective photoreceptor elements of the photodetector 101 are converted into voltage signals by the first to fourth current-to-voltage conversion circuits 102a, 102b, 102c, and 102d, and the first adder 103a adds the outputs of the first and third current-to-voltage circuits 102a and 102c while the second adder 103b adds the outputs of the second and fourth current-to-voltage circuits 102b and 102d.
Then, the signals outputted from the first and second adders 103a and 103b are subjected to sampling by the first and second ADCs 104a and 104b to be converted into first and second digital signal sequences, respectively.
Then, the digital signals outputted from the first and second ADCs 104a and 104b are input to the interpolation filters 105a and 105b to obtain interpolation data between the sampling data of the digital signals. Thereafter, zerocross points at the rising edges or falling edges of the two interpolated data sequences are detected by the zerocross point detection circuits 106a and 106b, respectively. For example, as a method of interpolation, "Nyquist interpolation" may be employed. As a method of detecting zerocross points at the rising or falling edges of two data sequences, change points of signs (+→− or −→+) in the interpolated data sequences may be obtained.
In the phase error detection circuit 107, a distance between the zerocross points in the waveforms of the first and second signal sequences is obtained using information of the zerocross points outputted from the zerocross point detection circuits 106a and 106b, and a phase comparison signal is detected on the basis of the distance between the zerocross points, and finally, band restriction is carried out by the LPF 108 to generate a tracking error signal of a frequency band that is required for tracking servo control.
Next, the construction and operation of the conventional phase difference detection circuit 107 will be described in more detail with reference to FIGS. 20 and 21.
FIG. 20 is a block diagram illustrating the construction of the conventional phase error detection circuit 107.
In FIG. 20, the phase difference detection circuit 107 comprises a phase difference calculation unit 201, a pulse generation unit 202, and a data updation unit 203.
The phase difference calculation unit 201 calculates a distance between the zerocross points of the two sequences of digital signals on the basis of the zerocross information detected by the zerocross point detection circuits 106a and 106b, and successively outputs it as a result of phase comparison to the data updation unit 203.
The pulse generation unit 202 generates pulse signals each corresponding to one sampling clock at the zerocross positions in the respective data sequences to be used for phase comparison, and outputs a pulse signal that appears later at the point where phase comparison is carried out, as a phase comparison end pulse, between the generated pulse signals corresponding to the respective data sequences.
The data updation unit 203 updates the output data for every phase comparison end pulse outputted from the pulse generation unit 202, using the phase comparison results that are successively outputted from the phase difference calculation unit 201, and maintains the output level of the output data until the next phase comparison end pulse arrives.
FIG. 21 is a diagram for explaining the operation of the phase difference detection circuit 107. FIG. 21 shows, from top to bottom, a first signal sequence outputted from the first zerocross point detection circuit 106a (phase comparison input A), a second signal sequence outputted from the second zerocross point detection circuit 106b (phase comparison input B), a phase comparison end pulse outputted from the pulse generation unit 202, and a phase comparison output from the phase difference detection circuit 11.
With reference to the phase comparison inputs A and B shown in FIG. 21, ∘ indicates sampling data obtained by the first or second ADC 104a or 104b, Δ indicates interpolation data sequences obtained by the first or second interpolation filters 105a or 105b, and ● and ▴ indicate zerocross points obtained from the sampling data sequences and the interpolation data sequences. Further, the phase comparison signal shown in FIG. 21 is obtained with respect to a vicinity of a specific track, and it is obtained at the falling edges of the two data sequences whose phase difference should be obtained. Further, the number of interpolation data is 3 (n=3).
When the outputs from the zerocross point detection circuits 106a and 106b are input to the phase difference detection circuit 107, the phase difference calculation unit 201 calculates a distance between the zerocross points detected by the zerocross point detection circuits 106a and 106b. Then, the pulse generation unit 202 generates a pulse signal corresponding to one sampling clock at a position where each of the data sequences (the phase comparison inputs A and B) to be used for phase comparison performs zerocross, and outputs a pulse signal that appears later between the generated pulse signals corresponding to the respective data sequences, as a phase comparison end pulse (refer to the phase comparison end pulse shown in FIG. 21).
Then, the data updation unit 203 performs updation of the output data using the phase comparison result outputted from the phase difference calculation unit 201, for every phase comparison end pulse outputted from the pulse generator 202, and maintains the output level of the output data until the next phase comparison end pulse arrives (refer to the phase comparison output shown in FIG. 21).
Thereby, the phase difference detection circuit 107 detects a phase comparison signal as shown by the phase comparison output in FIG. 21, and the tracking error signal obtained by performing band restriction to the phase comparison signal becomes an approximately straight signal when paying attention to a vicinity of a specific track. Then, the tracking error signal is observed over plural tracks, thereby obtaining, as a whole, an approximately sinusoidal waveform that is repeated for every track as shown in FIG. 22.
As described above, since the conventional tracking error detection apparatus can detect a tracking error by digital signal processing, it can deal with speedup of an optical recording/playback apparatus and an increase in recording density on a recording medium, which cannot be achieved by tracking error detection using analog signal processing. Furthermore, the constituents relating to analog signal processing can be significantly reduced, thereby realizing small-sized and low-cost optical recording/playback apparatus.
In the above-mentioned conventional tracking error detection apparatus, however, since AD conversion by the first and second ADCs 104a and 104b is carried out with the sampling rate being fixed, the amplitude of the obtained tracking error signal varies between the inner track and the outer track of the disc during CAV playback.
That is, since the channel rate is low at the inner track while it is high at the outer track during CAV playback, when the first and second ADCs 104a and 104b performs AD conversion with the sampling rate being fixed, the number of sampling data to be sampled within the same phase interval becomes larger at the inner track than at the outer track, resulting in a variation in the amplitudes of the tracking error signals obtained at the inner track and the outer track on the disc.
FIGS. 23(a) and 23(b) show tracking error signals detected by the conventional tracking error detection apparatus during CAV playback. To be specific, FIG. 23(a) shows a tracking error signal at the inner track of the disc while FIG. 23(b) shows a tracking error signal at the outer track of the disc.
As shown in FIG. 23(a), at the inner track, the number of sampling data to be sampled within the same phase interval increases, and therefore, the phase difference detected as the distance between the zerocross points by the phase difference detection circuit 107 increases, resulting in an increase in the output amplitude of the tracking error signal. On the other hand, at the outer track, as shown in FIG. 23(b), the number of sampling data to be sampled within the same phase interval is small, and therefore, the phase difference detected as the distance between the zerocross points by the phase difference detection circuit 107 becomes small, resulting in a reduction in the output amplitude of the tracking error signal.
Further, in the above-mentioned conventional tracking error detection apparatus, in order to realize a small-size and low-cost optical recording/playback apparatus, bit resolution of the first and second ADCs 104a and 104b possessed by the conventional tracking error detection apparatus is set at a minimum bit resolution required for phase comparison. Therefore, when the amplitude of the analog signal to be input to the first and second ADCs 104a and 104b is not sufficiently obtained due to defect or the like, sampling is not correctly carried out by the first and second ADCs 104a and 104b, leading to false detection of the phase difference detection circuit 107.
Further, in the conventional tracking error detection apparatus, when the voltage level of the analog signal to be input to the first and second ADCs 104a and 104b varies due to defect or the like, the zerocross point detection circuits 106a and 106b cannot correctly detect zerocross points, and the phase difference detection circuit 107 cannot detect a phase difference.

Matsushita Electric Industrial Co., Ltd.


A modified layer forming method of applying a pulsed laser beam having a transmission wavelength to a workpiece through a predetermined beam entrance surface in the condition where the focal point of the pulsed laser beam is set inside the workpiece, thereby forming a desired modified layer inside the workpiece. The modified layer forming method includes the step of reducing the power of the pulsed laser beam to a power that cannot process the workpiece when a surface adjacent to the beam entrance surface of the workpiece is located at the beam entrance position of the pulsed laser beam.

1. Field of the Invention
The present invention relates to a modified layer forming method of applying a pulsed laser beam having a transmission wavelength to a workpiece in the condition where the focal point of the pulsed laser beam is set inside the workpiece, thereby forming a modified layer inside the workpiece.
2. Description of the Related Art
There is in practical use an internal processing technique of applying a pulsed laser beam having a transmission wavelength to a transparent or translucent workpiece in the condition where the focal point of the pulsed laser beam is set inside the workpiece, thereby forming a modified layer inside the workpiece to create a pattern, figure, or character (see Japanese Patent Laid-open No. Hei 7-76167, for example).
There is also in practical use an internal processing technique of applying a pulsed laser beam having a transmission wavelength to a wafer such as a silicon wafer and a sapphire wafer along a plurality of crossing division lines partitioning a plurality of devices such as ICs, LSIs, and LEDs formed on the front side of the wafer, in the condition where the focal point of the pulsed laser beam is set inside the wafer, thereby forming a modified layer as a division start point inside the wafer along each division line (see Japanese Patent No. 3408805, for example).


A power supply apparatus is provided for energizing an electronic control unit mounted on a vehicle having a battery and a starter switch. The apparatus includes a coil connected to the power supply line, and a switch which operates for selectively enabling a current to flow through the coil and cutting off the current through the coil. A control circuit operates for selectively changing the switch between an ON state and an OFF state when the starter switch assumes an ON position. The ON and OFF states alternate in accordance with predetermined delays.

1. Field of the Invention
This invention relates to a power supply apparatus for an electronic control unit in an automotive vehicle.
2. Description of the Related Art
Most automotive vehicles have computer-based electronic control units (computer-based ECU's) for engine control such as spark timing control or fuel injection control. In general, the ECU's are powered by vehicle batteries. The ECU's are designed to normally operate at a power supply voltage in a predetermined range.
The automotive vehicles also have engine starters which can be powered by the vehicle batteries. When the starters are activated to start the engines, the power supply voltages to the ECU's tend to drop. In bad conditions, the power supply voltages drop below the predetermined range so that the ECU's can not operate normally.
To cope with such a problem, it is known that an electronic circuit able to operate at a low power supply voltage is provided separately from an ECU, and spark timing control and fuel injection control are implemented by the electronic circuit during the activation of an engine starter.
Electronics Engineer's Handbook, published by McGraw-Hill, Inc, 1989, pages 15-60 and 15-61, shows a boost dc--dc converter in which the positive terminal of a dc power source is connected to a first end of an inductor, and a second end of the inductor is connected to the anode of a freewheel diode (a flywheel diode) and a first terminal of a switch. The cathode of the freewheel diode is connected to a first end of a load. A second end of the load is connected to the negative terminal of the dc power source. A capacitor is connected across the load. A second terminal of the switch is connected to the negative terminal of the dc power source. The boost dc--dc converter can apply a voltage to the load which is higher than the voltage across the dc power source.
Japanese published examined patent application 7-118908 discloses a switching power supply circuit including a boost dc--dc converter and an oscillator. A switch in the boost dc--dc converter is periodically changed between an open state and a closed state by the output signal of the oscillator which has a variable duty cycle.
Japanese published unexamined patent application 2-51334 discloses a battery power supply apparatus including a battery used in powering both an engine starter and an engine controller. The apparatus of Japanese application 2-51334 has a boost dc--dc converter and an oscillator. A switch in the boost dc--dc converter is periodically changed between an open state and a closed state in response to the output signal of the oscillator. The apparatus of Japanese application 2-51334 also has a comparator serving to compare the output voltage of the boost dc--dc converter with a reference voltage. When the output voltage of the boost dc--dc converter exceeds the reference voltage, the comparator holds the switch in the open state to make ineffective the voltage boosting process.
Japanese published unexamined patent application 2-133064 discloses a boost dc--dc converter provided with first and second comparators. The first comparator responds to the output voltage of the boost dc--dc converter. The first comparator controls a switch in the boost dc--dc converter in response to the output voltage of the boost dc--dc converter. The second comparator responds to a current which flows through an inductor in the boost dc--dc converter when the switch is closed. The second comparator controls the switch in response to the current through the inductor.

Power supply apparatus for electronic control unit in automotive vehicle


A method and a structure are provided for improving the contact of two adjacent GMR memory bits. Two adjacent bit ends are connected by utilizing a single via.

1. Field of Invention
The present invention relates to a static memory. More particularly, the present invention relates to magnetoresistive random access memory (MRAM).
2. Description of Related Art
Magnetoresistive random access memory is a type of non-volatile memory with fast programming time and high density. A MRAM cell has two ferromagnetic layers separated by a non-magnetic layer. Information is stored as directions of magnetization vectors in the two ferromagnetic layers.
In conventional MRAM of a standard structural design, a single via is utilized for each GMR (Giant Magnetoresistance) memory bit end, and a metal is deposited into each via. However, the via in such conventional design is usually small, which results in residue remained inside the via after etching. In addition, the smaller via also causes unfavorable electrical contact between two adjacent GMR memory bits.
For the forgoing reasons, there is a need for developing a method and a structure to improving the contact of two adjacent GMR memory bit.

Method and structure for contacting two adjacent GMR memory bit


In a condenser microphone unit in which a microphone capsule and a capsule support are connected to each other via a screwed ring coupler, shield is maintained stably regardless of the degree of tightening of the ring coupler. On one end side on which a microphone cord 30 is drawn into the capsule support 20, a shield covering wire exposure part 33a is formed. Also, a shield cup 40 including a small-diameter cylindrical part 41 and a large-diameter cylindrical part 42 is arranged in the capsule support 20, the small-diameter cylindrical part 41 is fixed to the shield covering wire exposure part 33a by staking, a flange part 421 having a diameter almost equal to the outside diameter of a circuit board 21 is formed on the surface on which the large-diameter cylindrical part 42 is in contact with the circuit board 21, and a staking allowance 274 that goes around to the lower surface side of the flange part 421 is connectingly provided on the lower edge side of the ring coupler 270, by which the circuit board 21 and the flange part 421 are integrated with each other by staking the staking allowance 274.

A condenser microphone is mounted with an impedance converter because the impedance of an acoustoelectric converter formed by a diaphragm and a backplate in a unit is high. In most cases, a field effect transistor (FET) is used as the impedance converter, but a vacuum tube is used on rare occasions.
Also, to fulfill the performance and function as a microphone, a sound output circuit, a power supply circuit, a low cut circuit, and the like are provided in the microphone. For a microphone for conference, a microphone for choir, a tie clip microphone attached to the chest part, and the like, the microphone must be inconspicuous.
For this reason, the condenser microphone is separated, in terms of configuration, into a microphone unit, which includes the acoustoelectric converter formed by the diaphragm and the backplate and the impedance converter, and a power module section (output module section) including the sound output circuit, the power supply circuit, the low cut circuit, and the like, and the microphone unit and the power module section are connected to each other by a dedicated microphone cord.
In this case, as the dedicated microphone cord, a two-core shield covered wire is used. This two-core shield covered wire includes a power wire for supplying power from the power module section to the microphone unit, a signal wire for giving sound signals, which are generated from the impedance converter in the condenser microphone unit, to the power module section, and a shielding wire that electrostatically shields the power wire and the signal wire and connects them to the ground.
This dedicated microphone cord is vulnerable to noise (disturbance) coming from the outside because the sound signals are transmitted unbalancedly. Therefore, if strong electromagnetic waves are applied to the dedicated microphone cord, the electromagnetic waves intrude into the microphone unit, being detected by the impedance converter, and therefore noise is sometimes generated.
In recent years, cellular phones have come into wide use rapidly. In the case where a cellular phone is used near a microphone, the microphone receives considerably strong electromagnetic waves (for example, within the range of about several centimeters to several tens centimeters, a field intensity reaching tens of thousands times of field intensity produced in the city by commercial electric waves). Therefore, in the field of microphone, measures against cellular phones are urgently needed.
Conventionally, when the microphone cord is drawn into the microphone unit and is connected to a circuit board on which the impedance converter is mounted, a knot for preventing coming-off is formed in the microphone unit. However, the length of wiring in the microphone unit increases accordingly, so that the electromagnetic waves easily intrude into the microphone unit through the microphone cord.
The applicant of the invention has proposed a condenser microphone unit that takes measures to solve the above problems as Patent Document 1 (Japanese Patent Application Publication No. 2006-74107). The configuration of the proposed condenser microphone unit is explained by reference to FIG. 4.
This condenser microphone unit includes a microphone capsule 10 and a capsule support 20 as a basic configuration, and is connected to a power module section, not shown, via a dedicated microphone cord 30.
The microphone capsule 10 includes a cylindrical capsule case 11 formed of, for example, a brass material. In the housing (cupsule case) 11, a diaphragm 12 stretchedly provided on a support ring 13 and a backplate 14 supported on an insulating seat 15 are housed in the state of being arranged opposedly via an electrical insulating spacer (not shown).
The back surface side of the housing 11 is closed by a back lid 16, and a contact pin 17 that is connected to the backplate 14 via a wiring, not shown, protrudes from the back lid 16. Also, on the rear end side of the capsule case 11, an internally threaded cylinder 18 for connecting with the capsule support 20 is fixed so as to be electrically conducting with the capsule case 11.
The capsule support 20 includes a cylindrical housing 201 formed of, for example, a brass material, and the microphone capsule 10 is detachably connected to the capsule support 20 via a ring coupler 27 formed with external threads at the outer periphery thereof.
On one end side (the upper end side in FIG. 4) of the housing 201, internal threads 202 are formed. The lower half of the external threads of the ring coupler 27 is threadedly engaged with the internal threads 202, and the internally threaded cylinder 18 is threadedly engaged with the upper half of the external threads of the ring coupler 27 in this state, by which the microphone capsule 10 and the capsule support 20 are connected to each other.
Also, the housing 201 is formed with a concave step part 203 at a lower position of the internal threads 202, and as a receiver of the concave step part 203, a circuit board 21 is arranged on one end side of the housing 201 so as to close the interior of the housing 201.
In the example shown in FIG. 4, an FET 22 is mounted on the lower surface side of the circuit board 21 as an impedance converter. The circuit board 21 is a double-sided circuit board. FIG. 5A shows the wiring pattern on the upper surface of the circuit board 21, and FIG. 5B shows the wiring pattern on the lower surface on which the FET 22 is mounted.
The wiring pattern on the lower surface on which the FET 22 is mounted includes lead wirings for electrodes of gate, drain, and source of the FET 22, and the lead wiring for gate of these lead wirings is connected to a gate electrode terminal 211, which is formed in the center on the upper surface side of the circuit board 21, via a wiring in a through hole.
On the upper surface side and the lower surface side in the outer peripheral edge part of the circuit board 21, ground patterns 212a and 212b connected to the drain or source of the FET 22 are formed, respectively, so as to be conducting with each other via a wiring in a through hole.
On the upper surface of the circuit board 21 shown in FIG. 5A, a contact terminal 23 consisting of a plate spring that is in contact with the contact pin 17 is mounted in a state of being held on a spacer 24 of a rubber elastic body. The lower end of the contact terminal 23 is in contact with the gate electrode terminal 211 connecting with the lead wiring for gate of the FET 22.
Thereby, when the microphone capsule 10 is connected to the capsule support 20 via the ring coupler 27, the backplate 14 is connected to the gate of the FET 22 via the contact pin 17, the contact terminal 23, and the gate electrode terminal 211.
Also, the outer peripheral edge part of the circuit board 21 is held between the lower end part of the ring coupler 27 and the concave step part 203 of the housing 201. Thereby, the ground pattern 212a formed on the upper surface side in the outer peripheral edge part of the circuit board 21 is brought into tight contact with the ring coupler 27, and the ground pattern 212b formed on the lower surface side in the outer peripheral edge part of the circuit board 21 is brought into tight contact with the housing 201.
On the other end side (the lower end side in FIG. 4) of the capsule support 20, a cord introduction hole 25 having a cord bush 26 is provided. Through this cord introduction hole 25, the dedicated microphone cord 30 extending from the side of the power module section, not shown, is drawn into the capsule support 20.
As the microphone cord 30, a two-core shield covered wire is used which includes a power wire 31 for supplying power to the microphone capsule 10, a signal wire 32 for sending sound signals generated from the FET 22 to the power module section, not shown, and a net-shaped shield covering wire 33 that electrostatically shields the power wire and the signal wire and connects them to the ground.
According to the invention described in Patent Document 1, the microphone cord 30 is provided with a shield covering wire exposure part 33a, in which the shield covering wire 33 is stripped out, in a portion in which the microphone cord 30 is drawn into the capsule support 20, and a fastening fixture 40 is fixed in the shield covering wire exposure part 33a.
The shield covering wire exposure part 33a can be formed, for example, by removing the skin on the tip end side of the microphone cord 30 connected to the circuit board 21 to strip out the shield covering wire 33 and by folding back the stripped-out shield covering wire 33.
The fastening fixture 40 is formed as an annularly-shaped body of a washer shape (doughnut shape) that is thick and has a diameter larger than that of the cord introduction hole 25. The outside diameter thereof has a size such that the outside diameter is in close contact with the inner surface of the capsule support 20. Also, on the inner periphery side through which the microphone cord 30 is inserted, a staking sleeve 41 that is fixed to the shield covering wire exposure part 33a by plastic deformation is formed integrally.
When the microphone cord 30 is attached to the capsule support 20, after the microphone cord 30 has been inserted through the cord introduction hole and the tip end side thereof has been drawn out to the outside of the capsule support 20, the fastening fixture 40 is fitted on the shield covering wire exposure part 33a of the microphone cord 30, and the sleeve 41 is staked to fix the microphone cord 30.
After the power wire 31 and the signal wire 32 of the microphone cord have been soldered to a predetermined lead wiring on the circuit board 21, the tip end side of the microphone cord 30 is drawn into the capsule support 20 to engage the circuit board 21 with the concave step part 203 of the housing 201, and also the outer periphery side of the fastening fixture 40 is brought into contact with the inner surface of the capsule support 20.
Thereby, the microphone cord 30 is prevented from coming off, and also the shield covering wire 33 is electrically connected surely to the capsule support 20 via the fastening fixture 40, so that a high-frequency current caused by strong electromagnetic waves applied to the microphone core 30 flows to the capsule support 20 side, and does not intrude into the capsule support 20. Therefore, the generation of noise caused by electromagnetic waves is prevented.
As described above, according to the invention described in Patent Document 1, a knot for preventing coming-off of microphone cord need not be formed in the capsule support 20, and also the shield covering wire 33 is electrically connected surely to the capsule support 20. However, since the microphone capsule 10 and the capsule support 20 are connected to each other via a ring coupler 27, a problem as described below may occur.
When the ring coupler 27 is loosened by vibrations or shocks applied from the outside, or when the microphone capsule 10 is screwed firmly onto the ring coupler 27 with an excessive force, the stress between the ring coupler 27 and the capsule support 20 decreases.
As a result, the ring coupler 27 and the capsule support 20 become in bad contact with the ground patterns 212a and 212b of the circuit board 21, and therefore the shield between the microphone capsule 10 and the capsule support 20 becomes incomplete. Therefore, noise is generated by the high-frequency current, and in an extreme case, a trouble such that the sound signal is broken off occurs.
Accordingly, an object of the present invention is to provide a condenser microphone unit configured by connecting a microphone capsule to a capsule support via a screwed ring coupler, in which shield is maintained stably regardless of the degree of tightening of the ring coupler.


Assembly and quality of an electronic cigarette (“e-Cig”) may be tested and verified using imaging techniques. Infrared (“IR”) imaging may identify whether a temperature is uniform in an e-Cig during usage. Potential burning locations may be identified through the imaging by identifying locations whose temperature is unusually high or non-uniform. This temperature information may be used to calibrate the power of the e-Cig.

An electronic cigarette ("e-cigarette" or "e-Cig") is a device that emulates tobacco cigarette smoking, by producing smoke replacement that may be similar in its physical sensation, general appearance, and sometimes flavor (i.e., with tobacco fragrance, menthol taste, added nicotine etc.). The e-Cig may include a battery portion and a cartomizer portion (i.e. "cartridge"). The battery portion of the e-Cig includes a controller and battery for powering the device and the cartomizer portion generates an aerosol mist (i.e. e-smoke or vapor) that is a replacement for cigarette smoke. In particular, the cartomizer may use heat, ultrasonic energy, or other means to atomize/vaporize an "e-Liquid" solution (e.g. based on propylene glycol, or glycerin, for example including taste and fragrance ingredients) into an aerosol mist. The atomization may be similar to nebulizer or humidifier vaporizing solutions for inhalation. The cartomizer may include, or may be referred to as an atomizer, and the atomization may be caused by a heating element that heats the e-Liquid to generate the mist/vapor/e-smoke. The heating element may become quite hot in order to properly heat the e-Liquid and depending on the duration of usage of the e-Cig. Excessive heat within the e-Cig may cause burning of the internal components of the e-Cig. For example, burning may occur when a cartridge filled with a liquid becomes empty, such as when the liquid has evaporated or been vaporized as part of the e-Cig smoking process. Burning may result in bad taste and less pleasure when smoking and a smoker of an e-Cig may not be able to predict when the burning will occur. Calibration of the power provided from the battery to the cartridge may reduce the chances of burning.

Imaging for quality control in an electronic cigarette


An ion-exchange membrane including a porous unstretched polyethylene sheet in which fine pores are piercing, the pores being filled with an ion-exchange resin.

Ion-exchange membranes have been industrially used in many fields as electrolytic membranes for conducting the electrodialysis in the step of desalting for producing salts and foods, in the fuel cells, and as membranes for diffusion dialysis for recovering acids from the acids that contain metal ions generated in the steel industries. The ion-exchange membranes have a structure in which a base sheet that serves as a reinforcing material is provided as a core material in the ion-exchange resin so as to impart a predetermined membrane strength and shape stability for the membranes. Without the core material, the ion-exchange membrane, due to its much ion-exchange groups, easily undergoes the swelling if it is dipped in an electrolytic aqueous solution, and loses the strength or is deformed.
There has heretofore been known an ion-exchange membrane using a porous resin sheet as the base sheet. In the ion-exchange membrane of this form, voids in the porous resin sheet which is the base material are filled with the ion-exchange resin offering an advantage of a small electric resistance of the membrane (hereinafter membrane resistance). As the porous resin sheet, there has, usually, been used a thin film of a polytetrafluoroethylene or a high molecular polyethylene resin, the thin film being stretched in a monoaxial direction or in biaxial directions to avoid a decrease in the strength caused by the porosity. For example, a patent document 1 discloses a cation-exchange membrane for producing salts that includes a porous stretched polyethylene sheet (HIPORE manufactured by Asahi Kasei Chemicals Co. or SETELA manufactured by Tonen-Kagaku-Nasu Co.) as the base sheet.

Abstract: The ion-exchange membrane exhibits excellent concentration property.


A method is disclosed for providing electrical connections to electronic elements within a multilayer module. The method includes providing first and second active layers having first and second edges, respectively. Each active layer includes a flexible, polymer substrate and at least one electronic element formed within the substrate. Electrically-conductive traces provide electrical connections from the first and second edges to the electronic elements. An adhesive is applied to at least one of a top surface of the first active layer and a bottom surface of the second active layer and the top surface of the first active layer is adhered to the bottom surface of the second active layer. The first edge and the second edge are aligned with each other thereby forming a side of the multilayer module. Electrically-conductive lines are applied along the side of the multilayer module to provide electrical connections to the traces.

1. Field of the Invention
This invention relates to the field of electronics packaging, and in particular, to high-density electronic modules for housing and interconnecting electronic components located on stacked substrate layers.
2. Description of the Related Art
Increasing the volume density of electronic packaging is crucial for reducing device sizes for a given functionality. Efforts to provide high-density electronic packaging have included three-dimensional stacking technology in an attempt to avoid the inherent geometric constraints of standard two-dimensional semiconductor integrated circuits ("ICs"). By stacking electronic modules on top of one another and providing interconnections between the modules, the multiple layers can provide additional circuit elements without extending the two-dimensional footprint beyond that of a single module. Certain embodiments have also included heat-conducting, electrically insulating layers to improve heat dissipation during operation of these stacked electronic modules.
Numerous packaging schemes have been developed for stacking silicon-based ICs to increase the volume densities of electronic devices. However, while the silicon wafers of the silicon-based ICs provide rigidity and stability for the electronic elements, the ultimate volume densities of the multilayer stacks are inherently limited due to the thicknesses of the silicon wafers. Lapping off excess silicon from the back side of silicon wafers before stacking has been used to decrease the thickness of the silicon layers, and hence increase the number of layers per unit height. However, this procedure is time-consuming and requires precise machining to avoid damaging the circuit elements.

Process of manufacturing multilayer modules


An apparatus and method for catheter-based sensing and injection at a target site within a patient's body. An injection catheter is equipped with electrodes at its distal end which contact the surface of a target site, such as an AV node of the heart. Electrical signals detected at the target site by the electrodes are fed via leads to the proximal end of the catheter, where they are received by a monitor, such as an EKG monitor. If the electrical signals satisfy predetermined criteria, a needle within the catheter is extended into the target site, and a therapeutic agent is injected into the target site.

Medical catheters are used for innumerable minimally invasive medical procedures. Catheters may be used, for example, for delivery of therapeutic drug doses to target tissue and/or for delivery of medical devices such as lumen-reinforcing or drug-eluting stents. Likewise, catheters may be used to guide medical instruments to a target site to perform a surgical procedure, such as tissue rescission, ablation of obstructive deposits or myocardial revascularization.
Currently, catheter-based systems that are equipped with sensors (for example, electrodes) have a sensor tip at the distal end of the catheter. The sensor tip may or may not have an opening to permit a needle or a medical device to pass through the opening and into target tissue in the patient. These systems usually have one or more additional return sensors implemented as bands circumferentially around the catheter. In some systems, tissue contact is determined by measuring the impedance between the tip sensor when it is in contact with tissue and a return sensor that is not in contact with the tissue but is only in contact with a fluid, for example, blood, that is surrounding the tissue. However, this determination is based on known, that is, pre-determined, impedance values when the electrode is in contact with tissue and when only in contact with body fluids (for example, blood). Unfortunately, this method is not without problems, since the impedances of tissue and body fluid (for example, blood) are known to change during a procedure and different tissue will have different impedances depending on whether the tissue is healthy or diseased.
Alternatively, other sensor systems using a tip sensor and one or more band sensors around the catheter determine tissue contact by measuring impedance between sensors when the sensors are both contacting the tissue. Consequently, for this type of catheter to be able to detect the impedance, it must be lying flat against the target tissue area so that at least two of the sensors are in contact with the tissue. Unfortunately, this position does not enable the optimal targeted delivery of therapeutic agents to provide the most effective treatment regimen, since the tissue determined to be the target is usually not directly in line with the tip of the catheter.

Catheter with sensor tip and method of use of same