An endoscopic needle device includes an inner fluid conduit, an outer sheath extending over the length of the conduit, a longitudinally stiff wire extending through the conduit, and a needle fixedly attached to the distal end of the conduit. The distal end of the wire is coupled to one or both of the needle and the distal end of the conduit. The needle includes a proximal opening such that the hollow of the needle is in fluid communication with a lumen of conduit. A proximal handle includes a stationary member and a movable member longitudinally movable relative to the stationary member. The proximal end of the outer sheath is coupled to the stationary member, and the stationary member includes structure to mount the handle to a port of an endoscope. The movable member includes a passageway, and the proximal end of the conduit is coupled to the distal end of the movable member, and a port is provided at the proximal end of the movable member. A syringe may be coupled to the port and operated to inject a fluid which travels through the passageway, the lumen of the conduit, and the needle. In addition, the proximal end of the wire is coupled to the movable member. The handle assembly also includes a knob rotatably coupled to the stationary member, wherein rotation of the knob results in reciprocal movement of the movable member relative to the stationary, and consequently the needle relative to the distal end of the outer sheath.

1. Field of the Invention
This invention relates broadly to endoscopic instruments. More particularly, this invention relates to endoscopic injection needle devices.
2. State of the Art
An endoscopic injection needle device is inserted through a lumen of a flexible endoscope to inject fluids under endoscopic visualization in body structures such as the esophagus, the stomach, and the colon. For example, during a colonic polypectomy, it is customary to inject saline solution into the tissue surrounding and underlying a polyp in order to raise the polyp to facilitate excision of the polyp by means of an endoscopic forceps or snare. Visible dyes and radiological contrast dyes are sometimes injected to mark the location of areas explored endoscopically so that the structures can be located during subsequent procedures. Additionally, sclerosing agents are sometimes injected into vascular structures, such as esophageal varicoceles, in order to cause clotting and to necrose the tissue so that it can be resorbed by the body.
Typically, an injection needle device consists of a flexible inner tubing (or fluid conduit), usually made of polytetrafluoroethylene (PTFE), surrounded by a loose-fitting outer jacket made of PTFE, fluorinated ethylene propylene (FEP), or similar flexible plastic, a handle assembly at the proximal ends of the inner tubing and outer jacket for relative axial movement thereof, and a needle attached to the distal end of the inner tubing.
In practice, a physician grips the outer jacket of the injection needle device with one hand to introduce it through a sealing port on the endoscope handle which communicates with the working channel of the endoscope and to position the distal end of the device proximate the desired tissue at the distal end of the endoscope. With his or her other hand, the physician holds the proximal handle of the endoscope so that the steering knobs on the endoscope handle can be manipulated while viewing the endoscopic image. The handle assembly of the endoscopic needle device is held and manipulated by an assistant, according to the oral commands of the physician. The assistant moves one component of the handle assembly relative to the other to move the inner tubing axially relative to the outer jacket, thus retracting the needle into the outer jacket or extending it beyond the distal tip of the outer jacket. Once the needle is in position, the assistant then injects a fluid or medicament into the tissue by means of a syringe attached to the handle assembly of the device.
The amount of penetration of the needle into the tissue is not easily controlled by either the physician or the assistant. The depth of penetration of the needle is limited only by the fact that the fluid conduit (or the connector joining the needle point to the fluid conduit) which is larger in diameter than the needle, abuts the tissue. In an alternative procedural method, the physician pushes the jacket up against the tissue, and then the physician orders the assistant to fully advance the needle. In this manner, there is no visualization or degree of control to the penetration of the needle point, except as limited by the abutment of the fluid conduit or connector against the tissue. If the physician determines that a different amount of needle penetration is desired, another device with a needle point of a different length must be used.
While it is customary for a physician to standardize his practice with a needle of a certain penetration length, it sometimes is necessary to inject more superficially, to reduce the possibility of penetrating the tissue structure, or more deeply, to reach a plane of dissection to separate layers of tissue. Therefore, it is necessary to stock several injection needle devices in each gastroenterology suite, each device having a needle with a different length to accommodate the needs of the physician.
A few prior art devices have been built which allow the assistant to control the depth of needle projection beyond the distal end of the jacket, but these devices are imprecise and awkward. For example, the devices described in U.S. Pat. No. 5,380,292 to Wilson and U.S. Pat. No. 4,763,667 to Manzo attempt to achieve a measure of adjustability of the needle projection by utilizing an adjustable stop on the handle assembly of the device. The Wilson and Manzo devices do not have a calibrated control mechanism, and there is no way for the assistant to accurately adjust the depth of needle penetration while the device is in place in the endoscope, because such would require visualization of the needle point and measurement of its projection beyond the distal end of the jacket while turning an adjustment nut. Rather, the Wilson and Manzo devices simply provide a manner by which the device can be prepared prior to use for a specific amount of needle projection. Unfortunately, even the adjustable stop is of limited value, because the design of these prior art devices is such that the length of needle point projection beyond the jacket is highly variable despite the stop. In fact, the position of the needle is strongly influenced by the shape of the endoscope and by forces acting on the needle point. Depending on the degree to which the endoscope is flexed to negotiate the anatomy of the patient, the length of needle projection of most prior art devices is variable because of the various possible positions of the fluid conduit tubing within the loose-fitting outer jacket of the device. Thus, as the device is flexed, the needle point moves relative to the distal end of the jacket. Also, such designs which use a flexible plastic tube for the fluid conduit, are not amenable to precise control of the needle projection, because their needles will retract to some degree, typically a few millimeters, when forced against tissue. That is, the fluid conduit compresses. Thus, these devices do not teach a practicable means of controlling the length of needle projection while the device is being used.
U.S. Pat. No. 5,766,184 to Matsuno et al. describes another needle device having an outer tubular sheath, an inner tubular member extending through the outer tubular sheath and longitudinally and axially rotatably movable relative thereto, a shaft extending through the inner tubular member and coupled to the needle, a needle at the distal end of the inner tubular member, and a handle assembly including a knob which permits axial rotation of the shaft, and therefore the inner tubular member and needle, relative to the sheath. The needle and the distal end of the outer sheath are threadably connected. This threaded connection permits helical rotation of the inner tubular member relative to the outer tubular sheath to cause longitudinal movement of the needle relative to the distal end of the outer tubular sheath. Fluid is injectable through the inner tubular member and the needle into the patient. However, the device has severe drawbacks. It is generally desirable that the pitch of the threads be sufficiently small to permit the fine and precise adjustment of the extension of the needle, e.g., movement of the needle to within a half millimeter. Such fine adjustment requires that the pitch of the thread in the connection preferably be no more than a half millimeter. Yet, this requires that the inner tubular member be rotated a very large number of times relative to the outer tubular member in order to move the needle the required distance. For example, at a pitch of a quarter millimeter, the inner tubular member and outer tubular sheath would need to be completely rotated thirteen times relative to each other in order to effectuate a 6.5 millimeter movement of the needle. Such device operation is impractical for two reasons. First, it is impractical for the physician or assistant to keep count of how many times he or she has rotated the knob which causes the inner tubular member to rotate relative to the outer tubular member. However, keeping count is required as there is no other means by which to determine how far the needle has been extended. As such, absent reliance on the physician""s or assistant""s memory as to how may times the inner tubular member and outer tubular sheath have been rotated relative to each other, it is not possible to determine from the proximal end of the instrument the extension of the needle from the distal end of the instrument. Second, even if the physician or assistant could accurately keep count of the number of rotations, such repetitive rotational movement is uncomfortable, resulting in hand strain. Therefore, this needle device is undesirable to both the physician and the assistant. In addition, the patent fails to adequately describe a handle assembly which can correctly accommodate axial movement of the shaft and inner tubular member relative to the outer sheath as the needle is helically advanced and retracted.
It is therefore an object of the invention to provide an endoscopic needle device having a proximal handle assembly which accurately indicates the extension of the needle from the distal end of the device.
It is another object of the invention to provide an endoscopic needle device which may be conveniently and comfortably operated.
It is a further object of the invention to provide an endoscopic needle device in which the needle is precisely adjustable to deliver different depths of penetration of the needle point while the device is in use.
It is also an object of the invention to provide an endoscopic needle device which precisely controls the position of the needle relative to the distal end of the jacket.
It is an additional object of the invention to provide an endoscopic needle device in which extension of the needle is not affected by such factors as compressibility of the tubular components.
In accord with these objects, which will be discussed in detail below, an endoscopic needle device is provided which includes an inner fluid conduit, an outer sheath extending over the length of the conduit, an elongate longitudinally stiff wire or other element extending through the conduit, and a needle fixedly attached to the distal end of the conduit. The distal end of the wire is coupled to one or both of the needle and the distal end of the conduit. The needle includes a proximal opening such that the hollow of the needle is in fluid communication with a lumen of conduit. A proximal handle assembly includes a stationary member and a movable member longitudinally movable relative to the stationary member. The proximal end of the outer sheath is coupled to the stationary member, and the stationary member includes structure to mount the handle to a port of an endoscope. The movable member includes a passageway, and the proximal end of the conduit is coupled to the distal end of the movable member, and a port, e.g., a luer connector, is provided at the proximal end of the movable member. A syringe may be coupled to the port and operated to inject a fluid (injectate) which travels through the passageway, the lumen of the conduit, and the needle. In addition, the proximal end of the wire is coupled to the movable member. The handle assembly also includes a shaft rotatably coupled to the stationary member, wherein rotation of a knob coupled to the shaft results in reciprocatory (proximal-distal and distal-proximal) movement of the movable member relative to the stationary member, and consequently the needle relative to the distal end of the outer sheath.
According to a first embodiment of the invention, the movable member includes a rack, and the knob is provided with a pinion which engages the rack. Rotation of the knob relative to the stationary member causes the pinion to rotate relative to the movable member, and thus causes reciprocatory movement of the movable member relative to the stationary member which operates to move the position of the needle relative to the distal end of the endoscope. Precise movement is facilitated by the longitudinally stiff wire which extends through the fluid lumen, of the conduit. The wire counters the compressive force to which the conduit is subject when the movable member is moved distally relative to the stationary member. The knob and the stationary member are provided with indicia which indicate the movement of the needle.
According to a second embodiment of the invention, substantially similar to the first embodiment, the conduit is provided with at least two lumina, one for the injectate and the other for the wire. As such, the wire is not in contact with the injectate.
According to a third embodiment of the invention, a gear reduction assembly includes a change gear including two gears of different diameters on a common shaft. The smaller diameter gear engages the rack and the larger diameter gear engages the pinion. The gear reduction assembly permits larger gear teeth to be used on the pinion and rack, thereby facilitating manufacture and assembly of the device.
According to a fourth embodiment of the invention, a rolling band mechanism is utilized to reciprocate the movable member relative to the stationary member. In the rolling band mechanism, a band is wrapped one turn around a shaft attached to the knob, and the ends of the band are held taught at or adjacent ends of the movable member. The band and the shaft frictionally interfere. Rotation of the shaft by the knob causes the shaft to engage the band and results in reciprocal movement of the movable member relative to the stationary member.
According to a fifth embodiment of the invention, the movable member includes a portion provided with a rack, and a screw provided with threads engages the rack. Rotation of a knob portion of the screw causes reciprocatory movement of the movable member relative to the stationary member.
In each embodiment, the position of the knob relative to the housing provides an indication of the extension of the needle. In addition, the longitudinal stiffness of the wire ensures that proximal movement of the conduit relative to the sheath results in like movement of the distal end of the conduit relative to the sheath. As such, the injection needle device of the invention permits controllable movement of the needle such that the needle can be easily, reliably, and precisely advanced and withdrawn.
Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.

Knob-controlled endoscopic needle device


An articulated saw chain for cutting aggregate material and the like. The saw chain has cutting blocks affixed to pairs of side links and guards formed or attached to side link pairs positioned between successive cutting blocks. A guard portion is thus adjacent each end of the cutting block. The guard portions extend to substantially the same height as the cutting block to protect the edge of the cutting block from impacting against an object. The guards wear at a rate that does not significantly impede or interface with the cutting action of the cutting block.

1. Field of the Invention
This invention relates to a cutting chain (saw chain) for cutting aggregate materials and more particularly to a cutting chain having guard links with guard portions that precede the cutting links and permit efficient cutting while protecting the leading edge of the cutting links.
2. Background Information
Cutting chains are commonly used to cut trees and logs and more recently have been successfully applied to the cutting of aggregate materials such as masonry, stone and the like. However, there is a very significant difference in the cutting technique that is applied to cutting wood as compared to aggregate. For wood, the cutting link of the cutting chain includes a forwardly projected cutting edge. This cutting edge is designed to penetrate into the wood material and develops a kerf by repeatedly gouging out particles of wood. For aggregate, the cutting link of the cutting chain includes a diamond impregnated flat face (the upper surface of a cutting block provided on the link) that rubs against the aggregate and develops a kerf by abrading away the aggregate.
For a wood cutting chain, it is not only desirable but essential that the leading edge of the cutting link be exposed and engage the wood being cut. The corresponding "face" of the wood cutting chain is relieved to avoid rubbing contact. For an aggregate cutting chain, it is desirable to provide a surface-to-surface rubbing contact (cutting block surface to aggregate kerf bottom). Exposing the leading edge of the cutting block serves no useful purpose and conversely should the leading edge impact a hard object imbedded in the aggregate, e.g. reinforcing rods or rebar, in concrete, the edge can become chipped. In a short time, the cutting efficiency will be undesirably reduced. Avoidance of such edge impact is desirable.
Providing guard portions on guard links of cutting chain are not uncommon for cutting chains used for cutting wood. However, they are used for protecting the depth gauge of the cutting link and not the cutter. Furthermore, the guard portion and the depth gauge are intentionally set below the peak (i.e., the cutting edge) of the cutter by a significant amount. The depth gauge is set, e.g. to a depth of 0.030 inch below the cutting edge and has to be periodically filed to maintain sufficient exposure of the cutting edge of the cutter. The guard portion is set below the depth gauge by an extent to provide sufficient exposure that will not interfere with the cutting operation throughout the life of the cutter. The concept of the depth gauge and/or guard portion as applied to wood cutting chain is not applicable to aggregate cutting chain where the material is abraded.
U.S. Pat. No. 4,920,947 directed to aggregate cutting chains provides side links preceding the cutting blocks with depth gauge portions on the side links that extend to the height of the cutting blocks and presumably protect the leading edge of the cutting block. However, the depth gauge portion that has been used is a hard steel that interferes with the cutting action of the cutting block. The hardness is necessary to achieve adequate wearability of the side links, i.e. the material surrounding the rivet holes and along the bottom edge that slides on the guide bar wears rapidly and a softer material would have inadequate life. Thus, if the hardness of the depth gauge of the '947 patent is maintained, the cutting action must be repeatedly stopped and the guard portions filed down below the cutting block height. A tedious procedure and one that is not acceptable.


An endoscope includes an observation mode switch to switch observation modes. The observation modes include a dye valid observation mode allowed to acquire an image in which the dye is visually recognized well, and a dye invalid observation mode allowed to acquire an image in which the dye is substantially not visually recognized.

1. Field of the Invention
The present invention relates to an endoscope.
2. Description of the Related Art
At present, a "dye observation method" to disperse various dyes during an endoscopic inspection and observe their reactions and others are considered to be effective in early recognition of lesions, particularly cancer, determination of a lesion range, and assessment of the degree of invasion. There are various kinds of dyes that are characterized by, for example, being different from one another in principle and color. Dyes to be used differ depending on parts and lesions. However, living bodies principally show red-based colors, and a blue dye, which absorbs long-wavelength-side yellow and red components, is often used in order to form a contrast with the red-based colors.
Jpn. Pat. Appln. KOKAI Publication No. 2008-273900 discloses a such dye observation method. According to this literature, it is possible to easily recognize a boundary between a lesion part and a normal part by dispersing an indigo carmine aqueous solution having a density of 0.08 to 0.25 w/v % and an acetic acid aqueous solution having a density of 3.0 to 5.0 w/v % to an observation part at the same time or at an interval of a predetermined time during an endoscopic inspection.


A synthetic quartz glass to be used for light with a wavelength of from 150 to 200 nm, wherein the OH group concentration is at most 100 ppm, the hydrogen molecule concentration is at most 1xc3x971017 molecules/cm3, reduction type defects are at most 1xc3x971015 defects/cm3, and the relation between xcex94k163 and xcex94k190, as between before and after irradiation of ultraviolet rays, satisfies 0 less than xcex94k163 less than xcex94k190, and a process for its production.

The present invention relates to a synthetic quartz glass for optical components to be used for an apparatus employing ultraviolet lights having wavelengths of from 150 to 200 nm as a light source, and a process for producing it, particularly to a synthetic quartz glass to be used as optical components such as a lens, a prism, a photomask, a pellicle and a material for windows, to be used for light within a range of from the vacuum ultraviolet region and the ultraviolet region, such as an ArF excimer laser (wavelength: 193 nm), a F2 laser (wavelength: 157 nm), a low pressure mercury lamp (wavelength: 185 nm) or a Xe2★ excimer lamp (wavelength: 172 nm).
A synthetic quartz glass has such characteristics that it is a transparent material within a wavelength range of as wide as from the near infrared region to the ultraviolet region, it has an extremely small thermal expansion coefficient and is excellent in dimensional stability, and it contains substantially no metal impurity and has a high purity. Accordingly, a synthetic quartz glass has been mainly used for optical components of a conventional optical apparatus employing g-line or i-line as a light source.
Along with high-integration of LSI in recent years, techniques to draw finer and thinner lines have been required in an optical lithography technology to draw an integration circuit pattern on a wafer, and accordingly use of light having a shorter wavelength as an exposure light source has been promoted. For example, for a light source of a stepper for optical lithography, an ArF excimer laser (hereinafter referred to simply as an ArF laser) or a F2 laser is now to be used, as advanced from conventional g-line (wavelength: 436 nm) and i-line (wavelength: 365 nm).
Further, a low pressure mercury lamp or a Xe2★ excimer lamp is used for an apparatus such as optical CVD, an apparatus for cleaning silicon wafers or an ozone-generation apparatus, and it is being developed to apply it to the optical lithography technology in future.
It is necessary to use a synthetic quartz glass for a gas filled tube of a lamp to be used for a low pressure mercury lamp or an excimer lamp, or an optical element to be used for an optical apparatus employing the above-mentioned short wavelength light source.
A synthetic quartz glass to be used for such optical systems, is required to have light transmittance within a wavelength range of from the ultraviolet region to the vacuum ultraviolet region, and it is required that the light transmittance at the service wavelength will not decrease after irradiation of light.
With a conventional synthetic quartz glass, if it is irradiated with light from a high energy light source such as an ArF laser or a F2 laser, a new absorption band will be formed in a ultraviolet region, and such has been problematic for an optical component to be used for constituting an optical system employing an ArF laser or a F2 laser as a light source.
If an ArF laser or a F2 laser is applied for a long time, an absorption band (hereinafter referred to as a 214 nm absorption band) having a wavelength of 214 nm at the center, so-called an Exe2x80x2 center (xe2x89xa1Si.), and an absorption band (hereinafter referred to as a 260 nm absorption band) having a wavelength of 260 nm at the center, so-called NBOHC (non-crosslinked oxygen radical: xe2x89xa1Sixe2x80x94O.), will be formed.
As a technique to suppress formation of such absorption bands, a method of incorporating at least 100 ppm of OH groups and at least 5xc3x971016 molecules/cm3 of hydrogen molecules into a synthetic quartz glass which contains substantially no reduction type defects or oxidation type defects, has been proposed (JP-A-3-101282). It is disclosed that hydrogen molecules in the synthetic quartz glass have a function to mend defects such as Exe2x80x2 centers or NBOHC formed by the ultraviolet ray irradiation, and the OH groups have a function to reduce the concentration of defect precursors which become Exe2x80x2 centers or NBOHC when irradiated with ultraviolet rays.
However, as a result of a detailed research on the change in light transmittance of a synthetic quartz glass by ultraviolet ray irradiation, the present inventors have found that in the synthetic quartz glass, an absorption band (hereinafter referred to as a 163 nm absorption band) having a wavelength of 163 nm at the center, will be formed in addition to the 214 nm absorption band and the 260 nm absorption band. When it is used as an optical component for an apparatus employing light with a wavelength of at least 200 nm as a light source, the service wavelength and the 163 nm absorption band are apart, whereby there will be no substantial influence of the decrease in light transmittance due to formation of the 163 nm absorption band. However, in a case where it is used as an optical component for an apparatus employing light with a wavelength of from 150 to 200 nm as a light source, the light transmittance in the vicinity of the service wavelength will decrease due to formation of the 163 nm absorption band.
The present invention has an object to provide a synthetic quartz glass which is to be used for an apparatus employing ultraviolet rays having wavelengths of from 150 to 200 nm as a light source and which has high light transmittance at a wavelength of from 150 to 200 nm and is excellent in ultraviolet ray resistance (the light transmittance in the vicinity of the service wavelength will not decrease even when irradiated with light employing ultraviolet rays with wavelengths of from 150 to 200 nm as a light source), and a process for its production.
The present invention provides a synthetic quartz glass to be used for light with a wavelength of from 150 to 200 nm, wherein the OH group concentration in the synthetic quartz glass is at most 100 ppm, the hydrogen molecule concentration is at most 1xc3x971017 molecules/cm3, reduction type defects are at most 1xc3x971015 defects/cm3, and the relation between the change xcex94k163 in the absorption coefficient at a wavelength of 163 nm and the change xcex94k190 in the absorption coefficient at a wavelength of 190 nm, as between before and after irradiation of ultraviolet rays with a wavelength of at most 250 nm, satisfies 0 less than xcex94k163 less than xcex94k190.
It is important that the OH group concentration is at most 100 ppm (meant for weight ppm), and in a case where it is used as an optical component for an apparatus employing light in a vacuum ultraviolet region having a wavelength of at most 180 nm as a light source, the OH group concentration is preferably at most 50 ppm, particularly preferably at most 10 ppm. The lower the OH group concentration, the higher the light transmittance.
When a synthetic quartz glass containing hydrogen molecules is irradiated with ultraviolet rays, the 163 nm absorption band will be formed. The 163 nm absorption band is attributable to reduction type defects (xe2x89xa1Sixe2x80x94Sixe2x89xa1 bonds) and will substantially lower the light transmittance of ultraviolet rays with wavelengths of at most 200 nm. With a view to suppressing formation of the 163 nm absorption band, it is important that the hydrogen molecule concentration in the synthetic quartz glass is at most 1xc3x971017 molecules/cm3, particularly preferably at most 3xc3x971016 molecules/cm3.
To accomplish the object of the present invention, it is necessary to suppress formation of the 163 nm absorption band. The degree for suppression of formation of the 163 nm absorption band can be evaluated from the relation between the change xcex94k163 in the absorption coefficient at a wavelength of 163 nm and the change xcex94k190 in the absorption coefficient at a wavelength of 190 nm, as between before and after irradiation of ultraviolet rays with a wavelength of at most 250 nm. Namely, in the present invention, it is important that the relation of 0 less than xcex94k163 less than xcex94k190 is satisfied.
Further, when irradiated with ultraviolet rays, reduction type defects (xe2x89xa1Sixe2x80x94Sixe2x89xa1 bonds) in the synthetic quartz glass permit formation of the 214 nm absorption band (xe2x89xa1Si.) by the formula xe2x89xa1Sixe2x80x94Sixe2x89xa1+hxcexdxe2x86x92xe2x89xa1Si.+xe2x89xa1Si. thereby to lower the light transmittance of ultraviolet rays at a wavelength of from 150 to 200 nm. Accordingly, in the present invention, it is important that the reduction type defects in the synthetic quartz glass are at most 1xc3x971015 defects/cm3. The concentration of the reduction type defects can be obtained from the absorption intensity at a wavelength of 163 nm (Phys. Rev., B38, 12772 (1988)).
Further, when irradiated with ultraviolet rays, the oxidation type defects (xe2x89xa1Sixe2x80x94Oxe2x80x94Oxe2x80x94Sixe2x89xa1 bonds) in the synthetic quartz glass permit formation of the 260 nm absorption band (xe2x89xa1Sixe2x80x94O.) by the formula xe2x89xa1Sixe2x80x94Oxe2x80x94Oxe2x80x94Sixe2x89xa1+hxcexdxe2x86x92xe2x89xa1Sixe2x80x94O.+xe2x89xa1Sixe2x80x94O., whereby the light transmittance of ultraviolet rays at a wavelength of from 150 to 200 nm will be adversely affected depending upon the degree of the formation. Accordingly, in the present invention, it is preferred that the oxidation type defects in the synthetic quartz glass are at most 2xc3x971017 defects/cm3. The concentration of the oxidation type defects can be obtained from the OH group concentration increased by heat treatment of the synthetic quartz glass (10 mm in thickness) in 100% hydrogen gas at 1 atm at 900xc2x0 C. for 24 hours.
Further, in the present invention, chlorine element and metal impurities (such as alkali metals, alkaline earth metals, transition metals, etc.) in the synthetic quartz glass not only reduce the initial light transmittance in a wavelength range of from the vacuum ultraviolet region to the ultraviolet region but also cause to reduce the ultraviolet ray resistance. Accordingly, the smaller their contents, the better. The content of the metal impurities is preferably at most 100 ppb (meant for weight ppb), particularly preferably at most 10 ppb. The concentration of the chlorine element is preferably at most 100 ppm (meant for weight ppm), particularly preferably at most 10 ppm, further preferably at most 2 ppm.
The synthetic quartz glass of the present invention can be prepared by a direct method, a soot method (VAD method, OVD method) or a plasma method. Particularly preferred is a soot method, whereby control of the OH group concentration in the synthetic quartz glass is relatively easy, and the temperature of the preparation is low, which is advantageous with a view to avoiding inclusion of impurities such as chlorine and metals.
Further, the present invention provides a process for producing a synthetic quartz glass, which comprises carrying out in this order:
(1) a step of depositing and growing, on a substrate, fine particles of quartz glass obtained by subjecting a glass-forming material to flame hydrolysis in an oxidizing atmosphere, to form a porous quartz glass body;
(2) a step of heating the porous quartz glass body at a temperature of at least 1,400xc2x0 C. to obtain a transparent glass body;
(3) a step of heating the transparent glass body in an atmosphere containing hydrogen to dope it with hydrogen; and
(4) a step of heating the transparent glass body in an atmosphere containing no hydrogen for dehydrogenation treatment to obtain the above described synthetic quartz glass.
The glass-forming material may, for example, be a halogenated silicon compound (for example, a halide such as SiCl4, SiHCl3, SiH2Cl2 or CH3SiCl3, a fluoride such as SiF4, SiHF3 or SiH2F2, a bromide such as SiBr4 or SiHBr3, or an iodide such as SiI4) or an alkoxysilane (for example, RnSi(OR)4xe2x88x92n (wherein R is a C1-4 alkyl group, and n is an integer of from 0 to 3)). With a view to reducing inclusion of impurities such as metals and chlorine, an alkoxysilane (particularly methyl trimethoxysilane, tetramethoxysilane, etc.) is preferred. Further, from the viewpoint of the operation efficiency or cost, SiCl4 or the like is preferably employed.
As the substrate, a seed rod made of quartz glass can be used. Further, not only a rod shape, but also a plate-shaped substrate may be employed.
In the present invention, it is preferred to include, between steps (1) and (2), a step (1a) of heating the porous quartz glass body at a temperature of from 900 to 13000C to remove water, with a view to adjusting the OH group concentration to at most 100 ppm. The atmosphere in this step (1a) is preferably an atmosphere comprising an inert gas such as helium as the main component (inclusive of a case where the inert gas is 100%). The pressure (the absolute pressure, the same applies hereinafter) is preferably a reduced pressure or atmospheric pressure, particularly preferably at most 100 Torr (1.33xc3x97104 Pa), more preferably at most 10 Torr (1.33xc3x97103 Pa).
Further, in the present invention, it is preferred to include, between steps (1) and (2), a step (1b) of exposing the porous quartz glass body to an atmosphere containing a fluorine-containing gas to dope it with fluorine, with a view to adjusting the OH group concentration to at most 100 ppm. In such a case, fluorine will be contained in the synthetic quartz glass in an amount of from 100 to 10000 ppm, preferably from 1000 to 8000 ppm, particularly preferably from 3000 to 8000 ppm. As the fluorine-containing gas, SiF4, SF6, CHF3, CF4 or F2 may, for example, be mentioned. The atmosphere containing the fluorine-containing gas, is preferably an inert gas containing from 0.1 to 100 vol %, particularly from 0.1 to 25 vol %, of the fluorine-containing gas. In such a case, the temperature is preferably at most 600xc2x0 C. In a case where fluorine is doped at a high temperature of from 500 to 1150xc2x0 C., it is preferred to suppress formation of reduction type defects by using an atmosphere containing the fluorine-containing gas in an amount of from 0.1 to 100 vol %, particularly from 0.1 to 25 vol %, and further oxygen in an amount of from 5 to 95 vol %, particularly from 50 to 95 vol %. The pressure at the time of fluorine doping, is preferably from 0.1 to 10 atm (from 1.013xc3x97104 to 1.013xc3x97106 Pa). Further, the time is preferably from a few hours to a few tens hours.
In the present invention, when both steps of steps (1a) and (1b) are to be carried out, it is preferred to carry out step (1b) prior to step (1a).
In the present invention, it is preferred that the heating temperature in step (3) is at most 600xc2x0 C. with a view to suppressing formation of reduction type defects.
Further, in the present invention, it is preferred that the heating temperature in step (4) is at most 600xc2x0 C. with a view to suppressing formation of reduction type defects.

Synthetic quartz glass and method for preparing the same


The present invention provides an air tightness detection device for an aluminum alloy wheel hub, which is characterized by precision air pressure sensors, a lower clamp, a cone cylinder pressure plate, air pipes, a pressure plate, guide posts, an air inlet pipe, and a compressed gas control and detection system. A technical solution of the present invention has the following advantages that the cone cylinder pressure plate of the detection device reduces the space of an inner cavity of the wheel hub to further reduce inflating volume, thereby increasing detection efficiency; the characteristics of readily availability for preparation, no pollution and low cost are achieved by taking compressed air as a leakage indication gas.

The air tightness of an aluminum alloy wheel hub is an important index for measuring the performance of the aluminum alloy wheel hub. In wheel hub manufacturing enterprises, every aluminum alloy wheel hub must be inspected on the conformity with an air tightness requirement.
Common detection methods adopted include a helium gas-tightness detection method and a water air-tightness detection method. When a helium gas is adopted for detection, an inert gas of helium gas and a helium mass spectrometer need to be used. The detection equipment are expensive and the consumption of helium gas is large, leading to high overall cost. The principle for the helium gas-tightness detection is that a wheel hub needs to be placed in an air-tight space during detection; an inner cavity of the wheel hub is vacuumized; when a vacuum value is small enough, a helium gas with a certain pressure value is filled to the outer side of the wheel hub; if a leaking point exists in the wheel hub rim, molecules of the helium gas will pass through the leaking point to reach the inner cavity of the wheel hub; since the inner cavity of the wheel hub is in a vacuum environment, the molecules of the helium gas will be extracted into the helium mass spectrometer, which detects the number of helium molecules, thereby determining whether the air tightness of the wheel hub is within an acceptable range.
The principle of the water air-tightness detection is that inner and outer sides of the wheel hub are closed during detection; the wheel hub is immersed into water; then the inner cavity of the wheel hub is inflated with compressed air under certain pressure; and if an obvious leaking point exists in the wheel hub, high-pressure air in the inner cavity will form air bubbles in the water; and whether the air tightness of the wheel hub is acceptable can be further determined. Regarding the water air-tightness detection, water quality becomes worse after long-term continuous detection and needs to be changed, which consumes a large amount of clean water; in addition, a detection process needs to be observed by human eyes, which easily results in missed determination, and moreover, the detection time is long and the overall efficiency is low.
It follows that the traditional detection methods have the following defects that 1. with the helium gas, the equipment investment is large and the consumption of helium gas is high, leading to high overall cost; 2. with water air-tightness detection, a large amount of clean water needs to be consumed, with the detection time being long and the overall cost being high; therefore, the air tightness detection to the aluminum alloy wheel hub is in need of improvement.

Air tightness detection device for aluminum alloy wheel hub and method for detecting air tightness of wheel hub


Desired information is recovered from a communications signal that includes interference by processing the communications signal to produce a baseband signal and detecting a spreading sequence from the baseband signal. An estimate of an interfering signal component of the baseband signal associated with the detected spreading sequence is generated, and new version of the baseband signal is generated from a previous version of the baseband signal based on the generated estimate of the interfering signal component. The desired information is estimated from the new version of the baseband signal. The spreading sequence preferably is detected by resolving, e.g., descrambling, a version of the baseband signal into a plurality of signal components, respective ones of which are associated with respective propagation paths. The resolved plurality of signal components are correlated with a set of spreading sequences to generate respective sets of correlations for respective ones of the resolved signal components. The correlations are combined, preferably using maximal ratio combining (MRC) to generate a plurality of combined correlations, respective ones of which correspond to respective ones of the spreading sequences. The spreading sequence associated with the interfering signal component is detected from the generated combined correlations.

The present invention relates to communications methods and apparatus, and more particularly, to spread spectrum communications methods arid apparatus.
Wireless communications systems are commonly employed to provide voice and data communications to subscribers. For example, analog cellular radiotelephone systems, such as those designated AMPS, ETACS, NMT-450, and NMT-900, have long been deployed successfully throughout the world. Digital cellular radiotelephone systems such as those conforming to the North American standard IS-54 and the European standard GSM have been in service since the early 1990""s. More recently, a wide variety of wireless digital services broadly labeled as PCS (Personal Communications Services) have been introduced, including advanced digital cellular systems conforming to standards such as IS-136 and IS-95, lower-power systems such as DECT (Digital Enhanced Cordless Telephone) and data communications services such as CDPD (Cellular Digital Packet Data). These and other systems are described in The Mobile Communications Handbook, edited by Gibson and published by CRC Press (1996).
FIG. 1 illustrates a typical terrestrial cellular radiotelephone communication system 20. The cellular radiotelephone system 20 may include one or more radiotelephones (terminals) 22, communicating with a plurality of cells 24 served by base stations 26 and a mobile telephone switching office (MTSO) 28. Although only three cells 24 are shown in FIG. 1, a typical cellular network may include hundreds of cells, may include more than one MTSO, and may serve thousands of radiotelephones.
The cells 24 generally serve as nodes in the communication system 20, from which links are established between radiotelephones 22 and the MTSO 28, by way of the base stations 26 serving the cells 24. Each cell 24 will have allocated to it one or more dedicated control channels and one or more traffic channels. A control channel is a dedicated channel used for transmitting cell identification and paging information. The traffic channels carry the voice and data information. Through the cellular network 20, a duplex radio communication link may be effected between two mobile terminals 22 or between a mobile terminal 22 and a landline telephone user 32 through a public switched telephone network (PSTN) 34. The function of a base station 26 is to handle radio communication for a cell 24. In this capacity, a base station 26 functions as a relay station for data and voice signals.
As illustrated in FIG. 2, a satellite 42 may be employed to perform similar functions to those performed by a conventional terrestrial base station, for example, to serve areas in which population is sparsely distributed or which have rugged topography that tends to make conventional landline telephone or terrestrial cellular telephone infrastructure technically or economically impractical. A satellite radiotelephone system 40 typically includes one or more satellites 42 that serve as relays or transponders between one or more earth stations 44 and terminals 23. The satellite conveys radiotelephone communications over duplex links 46 to terminals 23 and an earth station 44. The earth station 44 may in turn be connected to a public switched telephone network 34, allowing communications between satellite radiotelephones, and communications between satellite radio telephones and conventional terrestrial cellular radiotelephones or landline telephones. The satellite radiotelephone system 40 may utilize a single antenna beam covering the entire area served by the system, or, as shown, the satellite may be designed such that it produces multiple minimally-overlapping beams 48, each serving distinct geographical coverage areas 50 in the system""s service region. The coverage areas 50 serve a similar function to the cells 24 of the terrestrial cellular system 20 of FIG. 1.
Several types of access techniques are conventionally used to provide wireless services to users of wireless systems such as those illustrated in FIGS. 1 and 2. Traditional analog cellular systems generally employ a system referred to as frequency division multiple access (FDMA) to create communications channels, wherein discrete frequency bands serve as channels over which cellular terminals communicate with cellular base stations. Typically, these bands are reused in geographically separated cells in order to increase system capacity.
Modern digital wireless systems typically utilize different multiple access techniques such as time division multiple access (TDMA) and/or code division multiple access (CDMA) to provide increased spectral efficiency. In TDMA systems, such as those conforming to the GSM or IS-136 standards, carriers are divided into sequential time slots that are assigned to multiple-channels such that a plurality of channels may be multiplexed on a single carrier. CDMA systems, such as those conforming to the IS-95 standard, achieve increased channel capacity by using xe2x80x9cspread spectrumxe2x80x9d techniques wherein a channel is defined by modulating a data-modulated carrier signal by a unique spreading code, i. e., a code that spreads an original data-modulated carrier over a wide portion of the frequency spectrum in which the communications system operates.
Conventional spread-spectrum CDMA communications systems commonly use xe2x80x9cdirect sequencexe2x80x9d spread spectrum modulation. In direct sequence modulation, a data-modulated carrier is directly modulated by a spreading code or sequence before being amplified by a power amplifier and transmitted over a communications medium, e.g., an air interface. The spreading code typically includes a sequence of xe2x80x9cchipsxe2x80x9d occurring at a chip rate that typically is much higher than the bit rate of the data being transmitted.
In a typical CDMA system, a data stream intended for a particular user (terminal) is first direct-sequence spread according to a user-specific spreading sequence, and the resultant signal is then scrambled according to a cell-specific scrambling sequence. The spread and scrambled user data stream is then transmitted in a communications medium. Spread-spectrum signals for multiple users generally combined to form composite signal in the communications medium.
Downlink signals for different physical channels within a cell are typically transmitted from a base station in a synchronous fashion. The user-specific spreading codes are typically orthogonal, creating mutually orthogonal downlink signals at the transmitter. However, channel dispersion typically results in a loss of orthogonality at the receiver, giving rise to intra-cell multi-user interference that can lead to degradation of receiver performance. This interference can be exacerbated by the xe2x80x9cnear-farxe2x80x9d problem, i.e., the higher contribution of signal energy from interferers that are closer to the receiver than the station transmitting a desired signal. Although the near-far problem can be alleviated by power control techniques on the uplink, power control is generally impractical on the downlink.
These problems may be exacerbated in xe2x80x9cthird generationxe2x80x9d systems such as wideband CDMA (WCDMA) systems. Such systems typically are intended to support several kinds of communications services, including voice and data applications that have varying information rate requirements. Generally, these systems are designed to support higher data rates than their predecessors, and also are designed to support a wide variety of data rates. However, the higher data rates and increased bandwidth of such wideband systems can combine to cause severe inter-cell and intra-cell interference among users. Such wideband third-generation systems are typically designed to support multiple spreading factors, which means that signals with low spreading factors generally require higher transmit power to achieve the same link quality as signals transmitted using higher spreading factors. This power differential can further increase intra-cell multiuser interference.
Several techniques for canceling such interference have been proposed, but many of these are more suitable for uplink interference cancellation, i.e., are highly complex and/or presuppose a priori knowledge of the spreading sequences being used in the system. Although such techniques can provide effective interference cancellation, in the presence of increasing demand for wireless services there is an ongoing need for interference cancellation techniques to further improve resource utilization.
In light of the foregoing, it is an object of the present invention to provide methods and apparatus for recovering information in composite spread spectrum signals transmitted in a communications medium.
It is another object of the present invention to provide methods and apparatus for recovering information transmitted according to a spreading code in the presence of interference from other spread spectrum signals.
It is a further object of the present invention to provide methods and apparatus for recovering a selected user signal in a cellular CDMA system in the presence of intra-cell multiuser interference.
These and other objects, features and advantages may be provided, according to the present invention, by methods and apparatus in which a baseband signal is recursively modified based on an estimate of interfering signal components constructed from spreading sequences detected in the baseband signal. More particularly, in embodiments according to the present invention, the baseband signal is descrambled to into multipath components that are correlated with a set of spreading sequences, for example, a set of possible spreading sequences used in a wireless CDMA communications system, yielding sets of correlations that are maximal ratio combined (MRC) to detect spreading sequences associated with interfering signal components in the baseband signal. Associated symbol estimates may be generated from the MRC results, and processed according to the detected spreading code, scrambling code and a channel estimate to generate an estimate of the interfering signal component. The estimate of the interfering signal component may then be used to cancel interference in the baseband signal using, for example, subtraction or signal projection techniques.
In one embodiment according to the present invention, desired information is recovered from a communications signal that includes interference by processing the communications signal to produce a baseband signal and detecting a spreading sequence from the baseband signal. An estimate of an interfering signal component of the baseband signal associated with the detected spreading sequence is detected. A new version of the baseband signal is generated from a previous version of the baseband signal based on the generated estimate of the interfering signal component. The desired information is estimated from the new version of the baseband signal.
The spreading sequence preferably is detected by resolving, e.g., descrambling, a version of the baseband signal into a plurality of signal components, respective ones of which are associated with respective propagation paths. The resolved plurality of signal components are correlated with a set of spreading sequences to generate respective sets of correlations for respective ones of the resolved signal components. The correlations are combined, preferably using MRC, to generate a plurality of combined correlations, respective ones of which correspond to respective ones of the spreading sequences. The spreading sequence associated with the interfering signal component is detected from the generated combined correlations. For example, the detected spreading sequence may be the sequence having the highest energy as indicated by the combined correlations, indicating that the interfering signal component associated with the detected signal has the highest signal strength in comparison with other interferers in the baseband signal.
The estimate of the interfering signal component preferably is generated by generating an estimate of a symbol transmitted according to the detected spreading sequence from the combined correlation associated with the detected spreading sequence. The estimate of the symbol is then processed according to the detected spreading sequence, the scrambling sequence and a channel estimate to generate an estimate of the interfering signal component.
According to another embodiment of the present invention, a plurality of spreading sequences are detected from the resolved plurality of signal components, respective ones of the detected plurality of spreading sequences being associated with respective ones of a plurality of interfering signal components in the communications signal. An estimate of the interfering signal component is then generated by generating respective estimates of symbols encoded according to respective ones of the detected spreading sequences from the combined correlations associated with the detected spreading sequences. Respective ones of the estimates of the encoded symbols are spread according to respective corresponding spreading sequences, and the spread estimates of the encoded symbols are combined to generate a composite signal. The composite signal is scrambled according to the scrambling sequence and processed according to a channel estimate to generate a composite estimate of the plurality of interfering signal components. A new version of the baseband signal is generated from a previous version of the baseband signal and the generated composite estimate of the plurality of interfering signal components. The new version of the baseband signal may be generated, for example, by subtracting the estimate of the interfering signal component from the previous version of the baseband signal to generate the new version of the baseband signal, or by determining a projection of the previous version of the baseband signal in a direction in signal space orthogonal to the estimate of the interfering signal component.
According to a xe2x80x9csubspace cancellationxe2x80x9d aspect of the present invention, respective ones of the estimates of the encoded symbols are spread according to respective corresponding spreading sequences. The spread estimates of the encoded symbols are then scrambled separately according to the scrambling sequence to generate a plurality of scrambled spread signals. The scrambled spread signals are then separately processed according to the channel estimate to generate respective estimates of respective ones of the plurality of interfering signal components. A new version of the baseband signal is generated from a previous version of the baseband signal and the generated estimates of the plurality of interfering signal components, preferably by determining a projection of the previous version of the baseband signal in a direction in signal space orthogonal to the generated estimates of the plurality of interfering signal components. The projection may be determined using, for example, a Gram-Schmidt orthogonalization.
According to another aspect of the present invention, the recursively generated baseband signal may be used to estimate desired information in the baseband signal using similar techniques to those used to generate the estimates of interfering signal components. The new version of the baseband signal is resolved into a plurality of interference-canceled signal components, and the resolved plurality of interference-canceled signal components correlated with a desired spreading sequence to generate a set of correlations for the resolved signal components. The correlations are then combined and the desired information estimated from the combined correlations.
According to yet another embodiment of the present invention, spreading sequences are detected for selected symbol periods, and used to generate estimates of interfering signal components for other symbol periods. A spreading sequence is detected from a first portion of the baseband signal corresponding to a first transmitted symbol. An estimate of an interfering signal component is generated from a second portion of the baseband signal associated with a second transmitted symbol based on the detected spreading sequence. A new version of the second portion of the baseband signal is estimated from a previous version of the second portion of the baseband signal and the generated estimate of the interfering signal component, and the second transmitted symbol is estimated from the new version of the second portion of the baseband signal.
According to yet another aspect of the present invention, an apparatus for recovering information from a communications signal comprises means for processing the communications signal to produce a baseband signal. Means for detecting a spreading sequence from the baseband signal are provided, along with means for generating an estimate of an interfering signal component of the baseband signal associated with the detected spreading sequence. Means are also provided, responsive to the means for generating an estimate of an interfering signal component, for generating a new version of the baseband signal from a previous version of the baseband signal based on the generated estimate of the interfering signal component. In addition, means are provided, responsive to the means for generating a new version of the baseband signal, for estimating the desired information from the new version of the baseband signal.
According to another aspect of the present invention, a receiver includes a recursive baseband processor that detects a spreading sequence from the baseband signal, generates an estimate of an interfering signal component of the baseband signal associated with the detected spreading sequence, generates an interference-canceled version of the baseband signal from the baseband signal based on correlations of the baseband signal with a set of spreading sequences, and generates an estimate the desired information from the interference-canceled version of the baseband signal. The baseband processor preferably includes a descrambler operative to resolve a version of the baseband signal into a plurality of multipath signal components. A correlator is responsive to the descrambler, correlating the resolved plurality of multipath signal components with a set of spreading sequences to generate respective sets of correlations for respective ones of the resolved signal components. A maximal ratio combiner is responsive to the correlator and operative to combine correlations to generate a plurality of combined correlations, respective ones of which correspond to respective ones of the spreading sequences.
A spreading sequence detector is responsive to the maximal ratio combiner and operative to detect the spreading sequence associated with the interfering signal component from the generated combined correlation. A symbol estimator is also responsive to the maximal ratio combiner and operative to generate a symbol estimate for the interfering signal component. A spreader is responsive to the spreading sequence detector and to the symbol estimator, and spreads the generated symbol estimate according to the detected spreading sequence. A scrambler is responsive to the spreader and operative to scramble the spread symbol estimate according to the scrambling sequence. A channel emulator is responsive to the scrambler and operative to process the scrambled spread symbol estimate according to a channel estimate to generate an estimate of the interfering signal component. A baseband interference canceler is responsive to the channel emulator, generating a new version of the baseband signal from a previous version of the baseband signal and the generated estimate of the interfering signal component.
In another embodiment according to the present invention, the descrambler is further operative to resolve the new version of the baseband signal into a plurality of signal components, respective ones of which are associated with respective propagation paths. The correlator is further operative to correlate the resolved plurality of signal components of the new version of the baseband signal with a desired spreading sequence to generate a set of correlations for the resolved signal components of the new version of the baseband signal. The maximal ratio combiner is further operative to combine the set of correlations for the resolved signal components of the new version of the baseband signal to generate a decision statistic for a symbol transmitted according to the desired spreading sequence. The receiver further comprises a symbol estimator responsive to the maximal ratio combiner and operative to generate an estimate of a symbol transmitted according to the desired spreading sequence from the generated decision statistic.

Baseband interference canceling spread spectrum communications methods and apparatus


An anti-icing spray assembly includes a base housing having a generally open top and a cavity. The base housing is adapted to be mounted in a roadway. A spray housing is removably secured to the base housing with at least a portion of the spray housing being disposed in the cavity of the base housing. The spray housing defines an interior chamber and is watertight so as to substantially prevent water from entering the interior chamber. The spray housing includes at least one spray outlet adapted to spray an anti-icing agent onto the roadway. At least one valve assembly is disposed in the interior chamber of the spray housing. The valve assembly is operably connected to the at least one spray outlet. The valve assembly is moveable between a closed position and an open position, wherein the valve assembly is adapted to permit the flow of the anti-icing agent through the at least one spray outlet and onto the roadway when moved to the open position. An anti-icing spray system includes a plurality of anti-icing spray assemblies installed in a roadway having a surface. A fluid conduit communicates with and supplies an anti-icing agent to the respective spray assemblies. A method of installing an anti-icing spray system in a roadway includes installing a plurality of base housings in the roadway such that the base housings do not protrude above a surface thereof, inserting a plurality of spray housings into corresponding ones of the base housings and removably securing the plurality of spray housings to the base housings.

The present invention relates to an anti-icing spray assembly and system, and in particular, to an anti-icing spray assembly that includes a watertight spray housing mounted in a base housing.
Various spray systems have been developed to apply anti-icing or anti-icing agents onto various roadways, including highways and airport runways. In some spray systems, as shown for example in U.S. Pat. Nos. 6,102,306 and 6,126,083 and European Patent No. EP 0 461 295 B1, a plurality of spray heads or nozzles are embedded in the roadway and are flush therewith such that the spray head or nozzle does not interfere with vehicles traveling on the roadway and is not easily damaged thereby. Often, such systems have one or more centrally located valves controlling the discharge of anti-icing agent to a plurality of spray heads. As such, individual spray heads cannot be independently controlled to apply anti-icing agent.
In addition, flush-type spray heads are typically installed directly in the roadway, for example at the time the roadway pavement is poured or applied, or by way of various adhesives or bonding agents. However, if one or more components of the spray head becomes damaged, the spray head typically has to be removed, which can be difficult and expensive. Alternatively, the spray head, if defective or damaged, must be serviced on-sight, which can be difficult in inclement conditions and can disrupt the flow of traffic, whether vehicular or air.


An improved muffler for silencing the exhaust emitted from a marine engine employing a reverse entry inlet conduit, an attenuation chamber and an outlet conduit whereby exhaust gas and liquid is communicated through the inlet conduit and into the attenuation chamber against the direction of the outlet stream. Upon entering the attenuation chamber exhaust gases and liquids reflect off the inner walls of the chamber and incoming exhaust thereby attenuating exhaust noise until they are finally forced out of the attenuation chamber through the outlet conduit. The reverse entry design of the muffler provides protection against backwardly flowing water that commonly enters a marine exhaust system by orienting the direction of inlet flow at an angle which is greater than 0 degrees but less than 90 degrees relative to the direction of output flow from the muffler.

1. Field of the Invention
This invention relates generally to a muffler for quieting the exhaust from an internal combustion marine engine, and more particularly, to a muffler whose inlet is opposed to the direction of backflowing surge water.
2. Description of the Prior Art
The exhaust of the typical inboard marine vessel is directed through the transom. Such applications place the exhaust outlet near or below the water line leading to possible back flow situations when the exhaust gas does not present enough force to overcome a water surge, or where water enters the exhaust pipe while the engine is off. To prevent this back flow of water into the muffler or engine, a check valve or flapper valve is usually employed. Additionally, as shown in FIG. 1, in a typical prior art exhaust system a surge pipe may be employed such that the engine output is elevated with respect to the exhaust outlet thereby decreasing the possibility of back flow entering the marine engine. However, none of the prior art muffler designs have an attenuation chamber with an inlet that is opposed to the direction of backflowing surge water. Rather, the present state of the art flapper valves, having moving parts which quickly corrode and fail, leading to either a potentially dangerous blockage of exhaust flow or an open ended exhaust pipe that makes a marine engine more susceptible to backflowing surge water.
There are a variety of marine mufflers presently known in the art which are of the "axial flow" type such as the muffler disclosed in U.S. Pat. No. 4,167,987, issued to Turner. The Turner patent describes a multiple flow marine muffler wherein exhaust noise is attenuated by passing the exhaust gas through a series of longitudinally spaced opposing baffles. However, such a configuration requires an elongated cylindrical shell to provide the required baffling effect, thus precluding application in tight-fit areas such as smaller boats or other situations where space is at a premium. Additionally, the use of an axial flow muffler cannot be placed below the water line without some form of surge suppression.
Another marine muffler, known as a "lift muffler," is disclosed in U.S. Pat. No. 3,296,997, issued to Hoiby, et al. The Hoiby muffler is essentially an up-right drum-shaped housing having an exhaust inlet near the top and a stand pipe exhaust outlet centrally located with its opening spaced above the drum bottom. The stand pipe directs the muffled exhaust gas and collected cooling water upwardly and outwardly to a location where it can be discharged from the boat without further back pressure. However, Hoiby does not present a means to prevent a reverse flow of water when the exhaust outlet is submerged. Additionally, such a device precludes application in tight-fit areas as the centrally located stand pipe requires exhaust conduit modifications to accommodate the pipe.
The exhaust outlet of an inboard-powered marine vessel is usually placed at or about the water line of the boat. As a result, surges of water routinely enter the exhaust outlet and travel through the exhaust system. This surge water could disable the engine if it is permitted to travel far enough, possibly leading to disastrous results, especially if the vessel is far from port. No one has heretofore proposed a reverse entry anti-surge marine muffler in which exhaust flow and collected coolant enters the muffler against the direction of flow of the outlet stream.
Therefore, there exists a need for a muffler capable of replacing a conventional muffler and surge pipe wherein the exhaust inlet is angled such that exhaust flow enters the muffler against the direction of flow of the outlet stream and hence inhibits back flow into a marine engine without the addition of moving parts such as a check or flapper valve.

Reverse entry muffler with surge suppression feature


A swivel holder is disclosed herein having a base member detachably carried from a belt, auto dash-board, wall surface or the like for releasably supporting an item or article of personal use. The article is provided with a stud and the base member includes guide rails defining a receptacle for insertably receiving the stud and for holding the stud in rotatable or swivelling relationship. A resilient catch member retains the stud in swivelling position on the base member and a finger latch mechanism controls the catch member for retention or release of the stud.

1. Field of the Invention
The present invention relates to the field of personal article holders and more particularly to a holder having a swivel connection means for an article of personal use and a manually operated retention and release mechanism for detachably mounting the article with the holder.
2. Brief Description of the Prior Art
Presently, certain individual or personal use articles are wall mounted or carried on a person's belt in order that the article is immediately present when needed. Such belt carried articles, as an example, commonly have carrying Cases which themselves must be supported by the belt worn by the user. Personal telephone pager devices are an example of such an article.
With respect to personal paging articles carrying case or holders, such should be easily and quickly attachable to and also readily detachable from the belt. The connection between the case and the belt should be such as to be personally comfortable to the user or wearer.
Elongated articles which are belt supported usually require pivotal mountings so that, when the user sits down, the lower end of the device will not engage the seat or the arm of the chair. This sort of action requires a connection which not only permits attachment and detachment at will, but also arcuate or pivotal movement over a considerable angular distance while retaining attachment and securement to the belt.
Attempts have been made to provide suitable swivel attachment for such articles; however, problems and difficulties have been encountered which stem largely from the fact that attachment of the article is not positive nor convenient for release. The disclosure of U.S. Pat. 4,827,614 shows a release mechanism but no means for providing a swivel action. U.S. Pat. 4,718,586 discloses a swivel connection but does not provide for a quick release mechanism.
Therefore a long standing need has existed to provide a holder for a personal use article which combines both a quick release feature as well as a detachable swivel connection between the article and the holder.

Releasable swivel holder for personal articles


The present invention provides an image forming apparatus which is small-sized and is able to keep a longtime and stable cleaning function. The image forming apparatus includes an image carrier; a blade member contacting elastically with the image carrier; a semi-conductive member installed on the blade member; and a power unit for adding a voltage to the semi-conductive member. Further, the semi-conductive member is set apart from the contacting portion of the blade member by a predetermined isolation distance.

1. Field of the Invention
The invention relates to an image forming apparatus.
2. Related Background Art
Conventionally, in an image forming apparatus, for example, a printing apparatus with electrophotography, copying apparatus or facsimile apparatus, in order to form an image, first an electrostatic latent image is formed on a photoconductor drum by using an electrifying device to electrify the surface of the photoconductor drum and using a LED (Light Emitting Diode) head to expose the surface of the photoconductor drum. Then a toner image is formed by using an image developing device made up of a blade and a developing roller and the like to develop the electrostatic latent image. The toner image is transferred on a recording medium, for example, a sheet or film by using a transference device. An image is formed by using a fixing device to fix the toner image transferred on the recording medium.
FIG. 2 is a drawing showing the main part of a conventional image forming apparatus.
In FIG. 2, 11 is a photoconductor drum set rotating-freely along an arrow direction, 12 is an electrifying device to electrify uniformly and equally the photoconductor drum 11. The electrifying device 12 comprises an electrifying roller 13 which contacts with the photoconductor drum 11 and is set rotating-freely, and a power unit 14 supplies a surface electric potential of −700V to the electrifying roller 13.
Further, 15 is a cleaning device for removing the toner (hereinafter: residual toner) remaining on the surface of the photoconductor drum 11. The cleaning device 15 comprises a cleaning blade 16 formed from an elastic material, for example, urethane rubber, and a bracket 17 for supporting the cleaning blade 16. The cleaning blade 16 has a JIS hardness of 60 degrees, a thickness of 2.0 mm, and a projecting portion with a length of 9.5 mm, projecting from the tip of the bracket 17. Further, the cleaning blade 16 has a slant angle H (53.4°) with respect to a line extending from the center of the photoconductor drum 11 along the radial direction and is pressed with a predetermined pressure by the photoconductor drum 11. Thus, while the photoconductor drum 11 rotates, the residual toner is scraped away by the cleaning device 15. Moreover, the photoconductor drum 11, the electrifying device 12 and the cleaning device 15 construct the image forming apparatus.
When the image forming apparatus starts to be used, in order to prevent the tip of the cleaning blade 16 from being rolled up, the toner with insulation efficiency is previously smeared on the tip of the cleaning blade 16. Thus, the early torque of the photoconductor drum 11 becomes small.
However, because the electrifying device 12 and the cleaning device 15 are set in the conventional image forming apparatus, the image forming apparatus becomes big.
Therefore, a cleaning blade which has an electrifying function for electrifying the surface of a photoconductor drum and a cleaning function for removing residual toner is provided (refer to the Japanese Patent Publication No. 6-130778).
FIG. 3 is a drawing showing the main part of a conventional image forming apparatus.
In FIG. 3, 11 is a photoconductor drum set rotating-freely along an arrow direction, and 21 is an electrifying/cleaning device for electrifying uniformly and equally the photoconductor drum 11, while removing residual toner after transferring. The electrifying/cleaning device 21 comprises a cleaning blade 22 with semi-conductivity, a bracket 23 for supporting the cleaning blade 22, and a power unit 24 supplying a predetermined voltage to the cleaning blade 22 so that the photoconductor drum 11 has a predetermined surface electric potential.
The cleaning blade 22 is formed by mixing conductive particles, for example, carbon black into urethane rubber serving as an elastic material, and has a cubic resistance of 106-109 (Ω·cm).
However, in other conventional image forming apparatus, when performing printing continually, the edge portion of the cleaning blade 22 is worn away so as to become nicked. Thereby, it is impossible to keep a cleaning function. This is because the hardness of the rubber drops so that the durability of the cleaning blade 22 is gone.

Image forming apparatus having a blade member with a semi-conductive member installed there on


According to some embodiments, a switch having an “on” state and an “off” state is exhibiting a low impedance in the “on” state, and a very high impedance in the “off” state. The switch comprises three series MOS transistors, the first transistor having its drain connected to the input. The switch also comprises additional circuitry which reduces, in the “off” state, the leakage current of the MOS transistor connected to the input of the switch by connecting its source and bulk to an electrical node replicating the voltage of the input node. According to some embodiments, the said switch is used in a voltage amplifier for capacitive sensing devices, such as MEMS gyroscopes and MEMS microphones; the voltage amplifier uses an operational amplifier used in a trans-capacitance configuration, with the feedback path comprising the said switch and a capacitor, wherein the said switch is connected to the input of, the voltage amplifier. According to some embodiments, the said switch is used in an integrated circuit which processes the voltage across a sensing device.

This invention relates to a switch used in electronic systems in which the voltage across a capacitor is amplified by a trans-capacitance operational amplifier.
Electronic systems which process the voltage provided by a sensing device approximately modeled by a capacitor (such as a MEMS gyroscope or a MEMS microphone) use a voltage amplifier implemented as a continuous' time trans-capacitance operational amplifier. The operational amplifier feedback path comprises a capacitor in series with a switch. It is desirable that the switch is connected to the input of the operational amplifier (and hence to the sensing device), while the capacitor is connected to the output of the operational amplifier. The sensing device provides a very low voltage, so it is critical that the current leakage due to the imperfections of the switch in the "off" state is minimized. Therefore, the switch used in the sampling circuitry requires a very high impedance (>1 TOhm) in the "off" state, and a low impedance (<1 kOhm) in the "on" state.
Conventional techniques use one or two MOS transistors to implement the switch. These transistors must have a ratio W/L high enough to allow a low impedance in the "on" state. However, the larger this ratio is, the larger the leakage of the switch becomes in the "off" state. Such conventional techniques can only achieve an equivalent "off" impedance on the order of a few GOhms. To avoid the unacceptable leakage from the sensing device, conventional switches are connected at the output of the operational amplifier. This solution has significant disadvantages, such as the increase of the noise of the amplifier due to the switching of the capacitor in parallel to the sensing device.

Voltage amplifier for capacitive sensing devices using very high impedance


A pump actuator assembly for mounting on a disposable plastic container having a neck and a cap mounted on the neck. A spring trapped between the pump actuator and the cap. The spring formed from a tubular sleeve of elastic plastic material with longitudinally extending slits formed in the tubular sleeve. In one embodiment, the sleeve is independent of the cap and sleeve. In another embodiment, the sleeve is formed integrally with the cap. In a third embodiment, the sleeve is formed integrally with the pump actuator. In a fourth embodiment, the sleeve is hooked to the cap.

Small finger operated pumps are commonly used for dispensing liquids, especially personal care products, from small hand held containers. These pumps and their containers are conventionally made of plastic and a typical pump, its container and contents are sold together. The container is filed with a personal care product such as a cream, soap, cosmetic or other liquid or gel. The pump and container are usually disposed of when the contents of the container are consumed, making the entire product a consumable item. Recycling the pump and its container has been difficult because the pump conventionally a includes a metal return spring.
This invention is directed to a plastic spring for a disposable plastic container having a finger operated pump which is attractive, functional and disposable.
An object of this invention is a plastic spring which may be adapted for installation on a conventional personal products container having a finger operated pump.
Another object of this invention is a plastic spring which is sufficiently attractive to be mounted where it is visible on dispensing container.
Yet another object of this invention is a compressible plastic spring that may be formed by injection molding.
Still another object of this invention is a compressible plastic spring that may be integrally molded with a container cap.
A further object of this invention is a compressible plastic spring that may be molded integrally with the pump actuator to facilitate assembly of the pump.


A harvesting reel of an agricultural harvester having a plurality of support members mounted to a frame and a plurality of tines press-fitted onto the support member is disclosed. The plurality of tines includes a cam for securely attaching the tine to the support member via a press-fit application to forego the need for any additional separate fasteners and tools necessary for production of the harvesting reel and maintenance upkeep of the plurality of tines on the harvesting reel.

The subject application relates generally to a reel tine for a harvesting reel of a harvester and a method of assembling a tine to a harvesting reel. In particular, the subject application relates to an improved fastener for connecting a tine to a harvesting reel.
Harvesting reels, such as a pickup reel, a draper reel and a gathering reel, are used on agricultural machines and include a plurality of parallel tine bars arranged in a substantially cylindrical pattern which is rotated about a central axis. Individual tines are connected to the tine bars and extend generally outwardly to engage crop material. The tine bars may be individually rotated dependent upon the reel rotational position of the tines relative to the reel rotational position, such as for folding the tines inwardly at a point in the rotation to release the crop material for feeding into the agricultural machine. Tines are typically connected to the tine bars using a variety of separate bolts, clips, or cast mounts, all of which increase the total part count of the reel and hence, increase production costs and maintenance costs.

Reel tine for a harvesting reel of a harvester and a method of assembling a tine to a harvesting reel


In the method of the invention for sequencing parcels in mail-sorting facilities having rows of stacking compartments, a sorting plan is used for sorting the parcels in which an overfilling of the individual stacking compartments is avoided so that, during one sorting procedure, the stacking compartments are not emptied, and that, after a sorting procedure has ended, an in-sequence transfer of the parcels is effected from the stacking compartments into a conveying device disposed opposite the stacking compartments or into containers.

The invention relates to a method for improved sequencing of letters in mail-sorting facilities.
In mail-sorting facilities, mailed items, particularly letters, are sorted in a pre-sorting procedure and deposited into a number of stacking compartments. The extent of sorting that can be achieved is determined by the number of stacking compartments into which the mailed items are distributed. Often it is neither desired nor possible, for practical reasons, to provide each of the smallest classes of a sorting procedure with its own sorting compartment. For example, when the mailed items are to be sorted corresponding to the sequence of a distribution in the postal route, a separate sorting compartment for each mail recipient is not necessary. Rather, the mailed items are distributed into a specific number of stacking compartments in the same sequence in which they will later be distributed by the sorter during the distribution process. The mailed items are arranged inside each sorting compartment to correspond to the stipulated sequence so that, in a corresponding arrangement of the stacking compartments, all of the mailed items are arranged according to the stipulated sequence. To permit sorting facilities to use a relatively small number of stacking compartments, the mailed items are sorted multiple times and possibly indirectly, as described, for example, in the Proceedings USPS Advanced Technology Conference, Washington, D.C., of Dec. 2, 1992, pp. 1061-1974.
Mail-sorting facilities are known in which the stacking compartments are disposed opposite the mail input, so that after each sorting procedure that is followed by a further sorting procedure, the mailed items can be quickly taken manually from the stacking compartments and reinserted into an input module. In manual transfer, the mailed items are respectively transferred by the handful from the compartment into containers opposite the stacking compartments and that are mounted on a mobile base. It is conventional that the containers possess a larger holding capacity than the stacking compartments, which must be emptied multiple times for transfer during each sorting procedure. A prerequisite for sequencing in accordance with the above-described method is that the sequence of the parcels be strictly maintained, i.e., the sequence integrity after the first and all subsequent sorting procedures. It is thus necessary that the containers be brought back into the correct sequence after each sorting procedure with the mobile base or additional transport means for mail input, or sorted into suitable groups for further processing after the last sorting procedure. Particular drawbacks of the prior art are that at least two operators are required for mail input and emptying the compartments. Further, restacking or interim stacking of the mailed items in containers requires a greater space requirement and increases the risk of disturbing the sequence integrity, because the stacks in the containers can easily capsize when the container is only partly filled, and the produced sequence can thus be disturbed. Further, the stacks can inadvertently be loaded into the wrong containers, or the sequence of the containers can be disturbed.

Method for sequencing letters in mail-sorting facilities


A sheathed catheter system is described where the sheath comprises a distal portion and a proximal portion that are moveable axially relative to each other, and relative to a tube carrying a medical device thereon. The distal and proximal sheath portions can be brought together in order to enclose therewithin the medical device. The distal sheath has a proximal section that is configured to bias radially inwardly to minimize an otherwise exposed annular surface catching on protruding surfaces that may exist on the catheter or other medical tool in use at the time, or to minimize scraping the inner native lumen of the patient upon retrieval.

1. Field of the Invention
The present invention relates generally to an apparatus and method for deploying a medical device from a minimally invasive delivery system, such as a delivery catheter, and deploying the device within a patient.
2. Description of the Related Art
Percutaneous aortic valve replacement (PAVR) technology is emerging that provides an extremely effective and safe alternative to therapies for aortic stenosis specifically, and aortic disease generally. Historically, aortic valve replacement necessitated open heart surgery with its attendant risks and costs. The replacement of a deficient cardiac valve performed surgically requires first placing the patient under full anesthesia, opening the thorax, placing the patient under extracorporeal circulation or peripheral aorto-venous heart assistance, temporarily stopping the heart, exposing and excising the deficient valve, and then implanting a prosthetic valve in its place. This procedure has the disadvantage of requiring prolonged patient hospitalization, as well as extensive and often painful recovery. Although safe and effective, surgical aortic valve replacement (SAVR) presents advanced complexities and significant costs. For some patients, however, surgery is not an option for one or many possible reasons. As such, a large percentage of patients suffering from aortic disease go untreated.
To address the risks associated with open-heart implantation, devices and methods for replacing a cardiac valve by less invasive means have been developed. For example, CoreValve, Inc. of Irvine, Calif. has developed a prosthetic valve fixed to a collapsible and expandable support frame that can be loaded into a delivery catheter. Such a bioprosthesis may be deployed in-situ minimally invasively through the vasculature at significantly less patient risk and trauma. A description of the CoreValve bioprosthesis and various embodiments appears in U.S. Pat. Nos. 7,018,406 and 7,329,278, and published Application Nos. 2004/0210304 and 2007/0043435. By using a minimally invasive replacement cardiac valve, patient recovery is greatly accelerated over surgical techniques. In the case of the CoreValve device, the support frame is made from shape memory material such as Nitinol. Other catheter-delivery valve replacement systems use stainless steel, or do not rely upon a rigid frame.
As demonstrated successfully to date, using a transcatheter procedure, percutaneous aortic valve replacement proceeds by delivering a prosthetic valve to the diseased valve site for deployment, either using a balloon to expand the valve support against the native lumen or exposing a self-expanding support in situ and allowing it to expand into place. With the latter, the self-expanding frame remains sheathed during delivery until the target site is reached. Advantageously, the frame may be secured to the catheter to avoid premature deployment as the sheath is withdrawn. In the CoreValve valve prosthesis, a hub is employed with two lateral buttons or ears around each of which a loop or alternatively a frame zig may reside during delivery. The internal radial force of the sheath keeps the frame compressed against the catheter, including the frame zigs in place around the lateral buttons. The catheter generally comprises at least two tubes, an inner tube that carries the prosthesis and a central tube that carries the sheath, permitting the sheath to move relative to the prosthesis.
As with traditional cardiovascular interventional therapies, transcatheter device deployment may proceed retrograde against normal blood flow, or antegrade, with blood flow. For percutaneous aortic valve replacement, entry through the femoral arteries proceeds in a retrograde format up through the iliac, the descending aorta, over the arch and to the native annulus. In some cases, entry has been made closer to the arch; for example through the left subclavian artery. Antegrade procedures have been performed where delivery takes place through the venous system transeptally to the native aortic annulus. More recently, transapical procedures have been performed whereby a cardiac surgeon delivers a catheter through the patient's chest wall, then through the exposed left ventricle apex and then to the target site.
With retrograde deployment, it is generally desired that the catheter be advanced within the vasculature so that the device is positioned where desired at the annulus site. With some embodiments under development, the desired site is the annulus itself With the CoreValve device, the desired site extends from the annulus to the ascending aorta, given its relative length. In the transfemoral approach, when the CoreValve device is positioned at the desired site, the sheath is withdrawn to the point where the inflow end of the device (preferably positioned at the native annulus) expands to engage and push radially outwardly the native valve leaflets. The sheath continues to be withdrawn proximally as the prosthesis continues to expand as it is exposed until the sheath covers just the outflow portion of the prosthesis still secured to the hub ears. Any readjustment of the axial position of the device in situ can be made during this process based upon electronic visual feedback during the procedure. Once well positioned, the sheath is fully withdrawn, the device fully expands in place, and the catheter is withdrawn through the center of the device and out through the vasculature. While it would be possible to deploy the prosthetic device such that the sheath could be withdrawn distally so that the outflow end of the prosthesis deploys first, such an arrangement would require advancing distally the central tube of the catheter connected to the sheath distally. In the case of transfemoral retrograde delivery, that would cause the central tube to project well into the left ventricle, which is not desirable. In a antegrade approach, for example transapical delivery, the reverse situation exists. There it is more desirable to advance the sheath distally to expose the inflow end of the prosthesis at the native annulus first. The native anatomy can accommodate this distal deployment because the central tube carrying the sheath is advanced up the ascending aorta towards the arch. Like the retrograde approach, once the valve prosthesis is fully deployed, the catheter may be withdrawn through the center of the prosthesis and removed through the apex of the heart.
Regardless of the direction of approach, with self-expanding frame technology, it is sometimes observed that even well-placed prosthetic valves inadvertently shift from the intended target site a small distance during the final delivery stage. The valve may still function effectively, but it is not optimized when, for example, the valve is placed so that it projects more than desired into the left ventricle. If the frame is implanted too low into the left ventricle, there is a risk of paravalvular leak where a portion of the blood ejected from the ventricle returns through the frame below the annulus.
In doing so, the catheter may sometimes inadvertently advance into the left ventricle for one of several possible reasons. One theory is that conical expansion of the zigs of the frame may influence positioning by following the path of least resistance until the inflow section is completely deployed in both the annulus and the ascending aorta may cause the prosthesis to shift. Another is the friction between the catheter sheath and the vessel wall, which may limit retraction of sheath even though the operator is pulling on it through the handle button. Consequently, the valve is pushed distally through the forward action of the plunger rather than the valve remaining stationary relative to the target site by the retraction of the sheath in the proximal direction. If the valve is not fully deployed (i.e., the sheath is not fully retracted) so that the valve frame is still secured to the catheter, axial adjustment is still possible. This is known as dynamic catheter positioning. In some cases, however, it is not determined until after full deployment that the frame is deployed amiss. In that circumstance, a repositioning procedure might need to be taken to correct placement. While possible in one of several different ways, it adds a level of complexity to the medical procedure that would be preferably avoided if possible. The problem is exacerbated because with transcatheter delivery, unlike surgical implantation, the clinician is unable to directly see the target site and must rely upon videographic technology to assess appropriate placement of the prosthesis.
One solution is to split the sheath into two discrete sections; a proximal section and a distal section. Doing so permits a controlled deployment that is central to the device, rather than at the distal or proximal end as with a single sheath. In U.S. Pat. No. 7,238,197, Seguin et al. have suggested such an arrangement, without any specificity or demonstration. See col. 14:36-42. No mention is made of the benefits or advantages of doing so, nor the particular configuration. Another example is shown in U.S. Pat. No. 7,022,133 to Yee et al. However, the distal and proximal portions are overlapping. Moreover, that disclosure does not address the issue regarding minimizing inaccurate deployment once the prosthesis is positioned at the target site. With an ill-configured split sheath arrangement, it has been observed that withdrawal of the catheter post-deployment may cause the proximal portion of the distal sheath to cause trauma to the native lumen where the vasculature is arcuate, such as the aortic arch. The problem may be encountered regardless of whether delivery proceeds antegrade or retrograde.
It is therefore desired to provide a transluminal catheter that enables prosthesis implantation accurately at the target location without the need for dynamic catheter positioning upon sheath retrieval. It is expected that, with such a solution, the prosthesis implantation procedure would become easier to manage with the desirable result that final positioning becomes more consistent.

Delivery system for deployment of medical devices