A sealing method, comprising: introducing a moving stream of curable material into an opening; and curing a portion of the moving stream of curable material flowing back out of the opening to form a cured layer of curable material. The cured layer restricts or prevents at least a further portion of the curable material from flowing back out of the opening.

Pipeline systems for delivering fluids, such as gas and water distribution networks, incorporate a large number of pipe joints. Gas pipeline systems, for example, frequently employ pipe lengths which are as short as 9 feet (2.74 m) long, meaning that a large number of joints are required to form the individual pipe lengths into a useable network.
The vast majority of pipe joints utilise a socket and spigot method, as shown in FIG. 1, in which a spigot 1 formed at an end of a first pipe 2 is inserted into a socket 3 of enlarged diameter formed at an adjacent end of a second pipe 4.
Another commonly-used pipe joint, known as a collar joint, is shown in FIG. 2. This type of joint involves spigots 5, 6 formed at the ends of adjacent pipes 7, 8 being inserted into either end of a double ended socket or collar 9, so as to join the pipes 7, 8 together.
A number of pipe joint sealing methods have been proposed, with the aim of preventing fluids in the pipeline from leaking at the pipe joints. For many years (in the UK, at least) gas pipeline networks employed cast iron pipes with lead-yarn sealed joints. An example of this type of seal is shown in FIG. 3. This type of seal is formed by first forcing a layer of yarn 10 into the circumferential cavity C present in the joint 11 between the spigot of a first pipe 12 and the socket of a second pipe 13. After the yarn 10 is in place, molten lead is poured into the gap in the joint 11, and allowed to set to form a further lead seal layer 14.
Previously, moisture in the gas carried by the pipeline kept the yarn of lead-yarn sealed joints moist and swollen (thus preserving the integrity of the seal). However, the changeover of UK gas supplies to North Sea gas in the 1960s resulted in a change to a "dry" gas product, without the previous levels of moisture, which has led to the shrinking of the yarn and subsequent leakage of gas from the joints.
Mechanical joints incorporating an elastomeric layer 15 (see FIG. 4) which is compressed within the joint have since been increasingly employed to seal joints in cast iron and steel pipelines. The elastomeric seals in mechanical joints are however prone to hardening and cracking, resulting in leakage over time. Such leakage in utilities pipework is endemic throughout the UK and indeed the world.
Pipe joints are also typically subjected to movement in service. One source of movement results from thermal expansion and contraction of the pipes, for example owing to changes between summer and winter temperatures. Another source of movement stems from the fact that pipelines are frequently routed under roads and streets, meaning that they are subject to significant and variable loading due to road traffic running over the route of the pipes. This loading subjects the pipe joints to rotational movement (i.e. joint bending) and longitudinal movement in service. As will be appreciated, pipe joint movement, from sources such as thermal expansion and traffic loading, can result in further joint seal damage and leakage over time. The malleable nature of the lead sealing layer of a lead-yarn sealed joint renders it particularly susceptible to degradation from joint movement, as it will not return to its original shape after deformation caused by joint movement.
Leaking joints naturally present concerns to pipeline operators in terms of revenue losses, as well as potential pollution and safety issues. Leakage from compromised joints may also detrimentally add to the carbon footprint of a pipeline operator, for example where the operator is a gas supplier. Methods have therefore been proposed to repair leaking pipe joint seals.
Currently, pipe joint seal repair is conducted by excavating the pipeline at the joint, drilling into the joint at specific locations and then injecting a sealant into the joint, which cures to form a blockage in the body of the joint. This technique has now been developed to include keyhole excavation techniques to minimise disruption, in which only a localised "core" of earth is extracted from the ground to expose the pipe joint at the desired repair point.
Internal robotic deployment of sealant is now also being carried out to repair point joints. This technique employs a pipe crawling robot, which is used to travel through the pipe network and then drill into the body of the joint from the inside of the pipe, before injecting sealants into the joint cavity to repair the joint seal.
All of these joint repair techniques require mechanical intervention into the joint itself, however, and as such disturb the joint and surrounding area during the repair operation. This disturbance can itself potentially cause additional problems, observed after the repair as the pipeline re-settles over time. Further, these methods are time consuming and risk potentially introducing additional leak paths into the system, for example in the event of a pipe cracking during the joint drilling process. Also, in the case of a collar joint it is very unlikely that the collar will be central to the joint. This can make drilling from the inside too risky, due to the possibility of drilling out of the pipe wall, potentially creating a new leak. Yet further, existing joint repair techniques can lead to sealant material dripping down and collecting at the bottom of the pipe, to the detriment of free fluid flow in the pipes.
Similar issues apply to the repair of other leak sources in pipelines, such as cracks and other openings in the pipeline wall, which may for example extend longitudinally along the pipeline (rather than around the circumference of the pipeline, as is typically the case for a pipe joint).
Aspects of the present invention seek to address problems associated with the prior art. It will however be appreciated that embodiments of the present invention may be applied to situations other than the repair of pipelines. For example, embodiments of the present invention may for example be employed to seal joints or other desired areas of a pipeline during its initial manufacture, rather than in a repair process. Yet further, embodiments may for example be applied to the manufacture and/or repair of seals, cracks holes or other openings in structures and articles other than pipelines.
According to a first aspect of the present invention, there is provided a sealing method, comprising:
a. introducing a moving stream of curable material into an opening; and
b. curing a portion of the moving stream of curable material flowing back out of the opening to form a cured layer of curable material, wherein the cured layer restricts or prevents at least a further portion of the curable material from flowing back out of the opening.
Preferably, said curing comprises applying electromagnetic radiation to the portion of the moving stream of curable material flowing back out of the opening.
Preferably, the curable material comprises light-curable material, and said applying electromagnetic radiation comprises irradiating the portion of the moving stream of light-curable material flowing back out of the opening with light to form the cured layer of light-curable material.
Preferably, the light-curable material comprises a light-curable sealant or light-curable adhesive.
Preferably, the moving stream of curable material is introduced into the opening using at least one nozzle.
Preferably, at least one light source is provided adjacent the at least one nozzle to locally irradiate the portion of the moving stream of light-curable material in the vicinity of the at least one nozzle.
Preferably, the at least one light source and the at least one nozzle are provided on a single body or are attached to each other.
Preferably, introducing the moving stream of light-curable material into the opening comprises using the at least one nozzle to introduce a moving stream of light-curable material into the opening in turn at plural locations of the opening, and wherein the method further comprises moving the at least one nozzle and the at least one light source between the plural locations.
Preferably, the at least one nozzle comprises a plurality of nozzles, the at least one light source comprises a plurality of light sources, and each one of the plurality of light sources is provided adjacent a respective one of the plurality of nozzles to irradiate an area in the vicinity of its respective one of the plurality of nozzles.
Preferably, at least one light source is provided to irradiate the entire opening.
Preferably, the moving stream of light-curable material is introduced into the opening at a single location of the opening to form a cured layer around the entire opening.
Preferably, the opening comprises the opening of a joint on an interior side of a pipeline, and the single location is at the bottom of the pipeline interior.
Preferably, the light-curable material comprises a UV-light curable material, and the light comprises UV light.
Preferably, the irradiating is such that the moving stream of light-curable material flowing back out of the opening is irradiated with UV light at an intensity of 30 W/cm2 or less, and more preferably 100 mW/cm2 or less.
Preferably, the curing is such that the cured layer of curable material is formed in five seconds or less, and more preferably between two and five seconds or in under two seconds.
Preferably, the method further comprises introducing additional curable material into the opening after the cured layer has been formed.
Preferably, the opening comprises an opening of a joint between two or more components.
Preferably, the opening leads to a cavity within the joint.
Preferably, the joint comprises a pipe joint joining pipes of a pipeline and the opening comprises an opening of the pipe joint, wherein the opening is present between the pipes.
Preferably, the opening leads to a cavity within the pipe joint.
Preferably, the opening comprises a crack in a surface.
Preferably, the opening comprises a crack, hole or gap in a surface or a gap between two surfaces.
Preferably, the opening is present on an interior side of a or the pipeline, and said introducing comprises introducing a moving stream of light-curable material into the opening from within the pipeline.
Preferably, said irradiating comprises irradiating the portion of the moving stream of light-curable material with light from at least one light source located within the pipeline.
Preferably, the curable material has a viscosity below 3000 cP, and more preferably 1500 cP or less.
Preferably, said curing is performed using a first curing process, and the curable material is also curable by at least one additional curing process.
Preferably, the at least one additional curing process is slower acting than the first curing process.
Preferably, the at least one additional curing process comprises one or more of an anaerobic curing process, a moisture-based curing process, a heat-based curing process or a curing process which is triggered by the addition of one or more additional chemical components and/or activators to the curable material.
Preferably, the at least one additional curing process is catalysed by metal ions.
Preferably, the opening is provided in a metal body or structure, and the method further comprises removing corroded material from a surface of the metal body or structure and mixing the corroded material with the curable material prior to said introducing a moving stream of curable material into the opening.
Preferably, the method is employed to repair a previously provided seal of the opening.
Preferably, the method is employed to provide a seal of the opening as part of a manufacturing process of an article or structure which includes the opening.
Preferably, the at least one nozzle comprises a plurality of nozzles.
According to a second aspect of the present invention, there is provided sealing apparatus, comprising:
a. at least one outlet which is operable to introduce a moving stream of curable material into an opening; and
b. curing means operable to cure a portion of the moving stream of curable material flowing back out of the opening to form a cured layer of curable material which restricts or prevents at least a further portion of the curable material from flowing back out of the opening.
Preferably, the curing means comprises at least one source of electromagnetic radiation.
Preferably, the at least one source of electromagnetic radiation comprises at least one light source which is operable to irradiate the portion of the moving stream of curable material flowing back out of the opening to form the cured layer of curable material.
Preferably, the at least one light source is provided adjacent the at least one outlet to locally irradiate an area in the vicinity of the at least one outlet.
Preferably, the sealing apparatus further comprises a body on which the at least one outlet and the at least one light source are provided.
Preferably, the at least one outlet and the at least one light source are attached to each other.
Preferably, the at least one outlet comprises a plurality of outlets, the at least one light source comprises a plurality of light sources, and each one of the plurality of light sources is provided adjacent a respective one of the plurality of outlets to irradiate an area in the vicinity of its respective one of the plurality of outlets.
Preferably, the at least one light source is operable to irradiate the entire opening.
Preferably, the curable material comprises a UV-light curable material and the at least one light source comprises at least one UV light-emitting light source.
Preferably, the at least one light source is arranged such that the portion of the moving stream of light-curable material is irradiated with UV light at an intensity of 30 W/cm2 or less, and more preferably 100 mW/cm2 or less.
Preferably, the curing means is arranged such that the cured layer of curable material is formed in five seconds or less, and more preferably between two and five seconds or in under two seconds.
Preferably, the at least one outlet is further operable to introduce additional curable material into the opening after the cured layer has been formed.
Preferably, the opening comprises an internal pipe joint opening of a pipeline, and the apparatus is arranged to be located within the pipeline.
Preferably, the at least one outlet comprises a plurality of outlets.
According to a third aspect of the present invention, there is provided a sealing system, comprising:
a. sealing apparatus according to the above-mentioned second aspect;
b. a movable platform which carries the sealing apparatus; and
c. a sealant supply system to supply curable material to the movable platform.
Preferably, the movable platform and sealing apparatus are arranged to be located within a pipeline.
Preferably, the opening comprises an internal pipe joint opening of the pipeline, and the movable platform is provided with means to move the at least one outlet of the sealing apparatus around the pipe joint opening.
Preferably, the opening comprises an internal pipe joint opening of the pipeline, and the movable platform is arranged to insert the at least one outlet of the sealing apparatus into the internal pipe joint opening at the bottom of the pipeline.
Preferably, the opening comprises a crack in an interior surface of the pipeline, and the movable platform is provided with means to move the at least one outlet of the sealing apparatus into the vicinity of the crack.
Preferably, the movable platform is movable in accordance with control signals transmitted to the movable platform from a remote location.
Preferably, the sealant supply system comprises a pump and an umbilical.
Preferably, the system is provided with a camera and/or sensor arrangement to identify the location of the opening.
According to a fourth aspect of the present invention, there is provided a method of delivering curable material, comprising:
a. producing a moving stream of curable material; and
b. selectively forming a cured layer of curable material to direct the movement of the curable material.
Preferably, said curable material comprises light-curable material, and said selectively forming comprises irradiating at least a portion of the moving stream of light-curable material with at least one light source to selectively form the cured layer.
Preferably, the method further comprises varying the intensity of the at least one light source to selectively form the cured layer.
Preferably, the at least one light source comprises a plurality of light sources, and wherein the intensities of the plurality of light sources are varied to selectively form the cured layer.
Preferably, producing the moving stream of curable material comprises extruding a stream of curable material from a nozzle, wherein the cured layer directs the movement of the stream.
According to a fifth aspect of the present invention, there is provided curable material delivery apparatus, comprising:
a. at least one outlet arranged to produce a moving stream of curable material; and
b. curing means arranged to selectively form a cured layer of curable material, wherein the cured layer is selectively formed to direct the movement of the curable material.
Preferably, the curing means comprises at least one light source arranged to irradiate at least a portion of the moving stream of light-curable material to selectively form the cured layer.
Preferably, the intensity of light output by the at least one light source is variable.
Preferably, the at least one light source comprises a plurality of light sources located at different positions relative to the at least one outlet.
Preferably, the intensity of light output by each of the plurality of light sources is independently variable.
FIG. 5 shows generally at 16 a robotic pipe repair system according to an embodiment of a sealing system aspect of the present invention. The robotic pipe repair system 16 comprises a robot 17 which carries sealing apparatus 18 according to an embodiment of a sealing apparatus aspect of the present invention and which is linked via an umbilical 19 to an on-surface metering pump unit 20. The robot 17 may be introduced into the pipeline 21 via an access point 22, after which the robot 17 is remotely operable from the surface to move to and access pipe joints 23 from the interior of the pipeline 21. The robot 17 is also provided with a suitable camera (not shown) to enable the location of the pipe joints 23 to be identified e.g. by an operator at surface level. The pipeline 21 in the present embodiment is illustrated as being horizontal, but it is to be understood that the robot 17 may be operated to move within pipelines of any orientation e.g. sloping or vertical.
The umbilical 19 is used to supply liquid sealant material to the robot 17. The liquid sealant material may comprise a sealant or adhesive. In the present embodiment, the liquid sealant material comprises a low-viscosity (below 3000 cP), Ultraviolet (UV)-curable liquid sealant material, which may be permanently cured (i.e. solidified) by the application of UV light. UV-curable sealant materials suitable for use in the present embodiment are for example manufactured by Permabond of Winchester, United Kingdom.
In addition to liquid sealant, the umbilical 19 is also used to supply electrical power to the robot 17, together with the necessary command signals to control movement of the robot 17 within the pipeline 21. The umbilical 19 may also be used to retrieve the robot 17 in the event of failure.
Robots suitable for use in the present system include, for example, the CISBOT robot manufactured by ULC Robotics of Hauppauge, N.Y. 11788, USA, the Versatrax Crawler System manufactured by Inuktun Services Ltd of Nanaimo, British Columbia, Canada, and the Covercat 900 Series Pipe Snake manufactured by Hyperion Equipment Ltd of Stockton-on-Tees, United Kingdom.
Sealing apparatus 18 according to a first embodiment of a sealing apparatus aspect of the present invention is shown in FIG. 6, and comprises a baffle 24 to which a nozzle 25 and a UV-light source (shown generally at 26) comprising an array of UV-light emitting LEDs 27 are mounted. The baffle 24 of the present embodiment is planar and substantially rectangular, and is flexible, preferably being of flexible polyurethane, although other suitable materials may be used e.g. an epoxy material or similar. In the present embodiment, both the outlet 28 of the nozzle and the LEDs 27 are located flush with a front surface of the baffle 24, with ones of the LEDs 27 mounted adjacent to and on either side of the nozzle outlet 28. In the present embodiment, the array comprises a total of six LEDs 27, although a greater or lesser number of LEDs may be used, including a single LED, depending upon the operational requirements of the sealing apparatus 18.
Operation of the sealing apparatus 18 of the first embodiment will now be described with reference to FIGS. 7, 8 and 9.
Once the robot 17 is located within the pipeline 21 and moved to a position adjacent a first joint 23 to be repaired, the sealing apparatus 18 is inserted into the joint opening 29 on the interior side of the pipeline 21, as shown in FIG. 7 and as indicated by step 801 in the flow chart of FIG. 8. The sealing apparatus 18 may for example be carried by the robot 17 using a movable arm (not shown) to facilitate insertion of the sealing apparatus 18 into the joint opening 29, and the proper insertion of the sealing apparatus 18 into the joint opening may optionally be confirmed using the camera (not shown) also carried by the robot 17. The flexible material of the baffle 24 of the present embodiment enables it to adapt to the joint opening 29 e.g. by bending, and may for example adopt a substantially U-shaped cross-sectional profile upon further insertion into the joint opening 29.
UV-curable liquid sealant material, supplied to the robot 17 via the umbilical 19, is then injected into the joint opening 29 from the nozzle outlet 28 of the sealing apparatus 18. Simultaneously, the UV-emitting LEDs 27 are powered to irradiate the joint opening 29 with UV light in the vicinity of the sealing apparatus 18 (step 802).
As noted above, the liquid sealant 30 of the present embodiment has a low viscosity (below 3000 cP) and accordingly readily flows into the cavity C of the joint 23 via the joint opening 29. However, the nature of the joint opening 29 means that injected liquid sealant 30 will be free to run back out of the joint opening 29 and into the pipeline 21; this is particularly the case for a low viscosity sealant, as in the present embodiment.
Indeed, the path of least resistance of a sealant injected into a joint is back out of the joint opening itself. This is illustrated by FIGS. 9A to 9E. FIG. 9A is a cross-sectional view through a typical mechanical joint, similar to that shown in FIG. 4, and FIG. 9B is a detail showing part of the mechanical joint of FIG. 9A in a flat representation, and showing the seal volume profile S (i.e. the joint cavity created between the spigot of the first pipe and the socket of the next) as a hatched area. FIG. 9C is a cut-away perspective view showing the seal volume profile S in isolation, and FIG. 9D shows the seal volume profile S rolled flat. As shown in FIG. 9E, the preferential flow path of liquid sealant injected into the seal volume profile S in the direction indicated by the arrow A at the injection point P is back out of the joint in the direction of the arrows B.
However, any liquid sealant 30 seeking to leave the joint opening 29 in the vicinity of the sealing apparatus 18 will be cured by the UV light emitted from the array of LEDs 27. This results in a cured layer 31 of solidified sealant being created in the vicinity of the sealing apparatus 18 (step 803). This cured layer 31 prevents further liquid sealant 30 from passing out of the joint opening 29 at the injection point, and hence promotes the flow of sealant into the body of the joint cavity. The presence of this cured layer 31 also means that pressure will increase on the liquid sealant 30 as further liquid sealant 30 is injected into the joint opening 29 after the cured layer 31 has been created. This increased pressure results in the uncured liquid sealant material 30 being forced still deeper into the joint cavity C, enabling the joint cavity C to be filled with sealant material to maximise the strength of the seal. The sealing apparatus 18 is then moved (e.g. using a robotic arm, not shown) to further positions around the entire circumference of the joint opening 29 (step 804) whilst the above-described sealant injection and curing process is continued, until a complete seal of the joint opening 29 has been formed. This joint repair process may then be repeated at further joints 23, simply by moving the robot 17 within the pipeline 21 to further joint locations.
The power of the UV light source 26 may be selected to form the cured layer of liquid sealant almost instantaneously e.g. in one second or less. In practice, this means that escape of uncured liquid sealant from the joint opening can be significantly restricted or avoided altogether, even when the liquid sealant 30 is injected directly upwards (and hence, against gravity) into the joint opening 29 at the top of the inside of the pipeline 21.
For example, experimental testing has shown that "UV683" UV-curable sealant, manufactured by Permabond of Winchester, UK, can be cured in around 1 second by application of UV light of sufficient power to result in a received intensity, at the surface of the UV-curable sealant, of 30 W/cm2. The actual received intensity which will be necessary to quickly form a cured layer will depend on a number of factors, including the UV-curable material being used, as well as the speed at which the cured layer is desired to be formed. It is however envisaged that a suitably fast cure will in many circumstances be obtained by application of UV light of sufficient power to result in a received intensity, at the surface of the UV-curable sealant, of 100 mW/cm2. Further UV-curable adhesives and sealants which have been employed in successful testing of an embodiment of the invention include PK51381, PK51201, UV683 and PK20024, all manufactured by Permabond of Winchester, UK; UV7000 and UV2000 manufactured by Sureloc Adhesives Ltd of Barton Upon Humber, UK and Vitralit 6128 and Vitralit 4282 manufactured by Panacol-Elosol GmbH of Steinbach/Taunus, Germany. It is however to be understood that the foregoing are merely examples and by no means limiting, and that embodiments of the present invention may employ a wide range of different UV-curable adhesives and sealants.
Rapid formation of a cured layer may be particularly desirable where a low-viscosity liquid sealant is used, which may be more prone to quickly running back out of the joint opening 29. It is however to be understood that rapid formation of a cured layer will not always be necessary or desirable (e.g. when a higher viscosity sealant material is used which may only flow back out of the joint opening 29 at a slower rate, and/or where a certain amount of sealant leakage back out of the joint opening is acceptable before the cured layer is formed) and the present invention is by no means limited to the rapid formation of a cured layer.
The baffle 24 of the present embodiment further assists in the sealing process by physically directing liquid sealant 30 into the body of the joint opening 29 and away from the interior of the pipeline 21.
In terms of sealant penetration into the joint, testing of an embodiment according to the present invention has demonstrated the liquid sealant 30 injected into the joint opening 29 reaching each of Volumes 1, 2 and 3 of the joint (see FIG. 10), with Volume 3 being adjacent the lead-yarn seal area 10, 14 deep within the joint. That is, the entire joint cavity C may be filled by the liquid sealant 30 (in areas not already occupied by any pre-existing sealing material e.g. from a previous lead-yarn seal), to maximise the strength of the seal.
Through continued application of the UV light source, it is possible to cure the sealant present at increasing depths into the joint. For example, experimental testing has indicated that, where UV light falls on the joint opening and is not obscured e.g. by the contours of the joint opening, curing of the liquid sealant is possible in Volume 1 and up to the boundary of Volume 2 of the joint cavity as shown in FIG. 10. It is also possible to provide cured sealant at areas deeper within the joint by employing a UV-curable sealant which is also curable by one or more additional curing mechanisms, as discussed in greater detail hereinafter.
However, where the pipeline 21 carries fluid at low pressure (typically 75 mBar or below in a typical gas supply network), it may not be necessary to cure the sealant deeply into the joint, as the mere presence of uncured liquid sealant at increasing depths may be sufficient to preserve the integrity of the seal.
The present embodiment may beneficially be employed whilst fluid (such as gas) is still present in the pipeline 21. This avoids the need to place the pipeline 21 out of service during the joint seal repair process. Additionally, the liquid sealant 30 injected into the joint opening 29 will be preferentially directed towards the leak site by the fluid itself, to enable a seal to be formed at the exact location of the leak. This is particularly facilitated in the present embodiment as a low-viscosity liquid sealant is employed, which will readily flow to the leak site together with fluid escaping from the pipeline.
As will be appreciated, the rapid UV curing process employed in the present embodiment allows for a low-viscosity (i.e. less than 3000 cP) liquid sealant to be employed whilst minimising or avoiding altogether liquid sealant running back into the pipeline. It is envisaged that a target viscosity of 1500 cP for the liquid sealant will be routinely achievable according to embodiments of the present invention, however viscosities as low as 100 cP have been successfully deployed in testing to seal a joint using the UV curing technique according to an embodiment of the present invention. As noted above, it is however to be understood that rapid formation of a cured layer will not always be necessary or desirable (e.g. when a higher viscosity sealant material is used which may only flow back out of the joint opening 29 at a slower rate, and/or where a certain amount of sealant leakage back out of the joint opening is acceptable before the cured layer is formed) and the present invention is by no means limited to the rapid formation of a cured layer.
The use of a low viscosity sealant maximises the effectiveness of the seal, as a low viscosity sealant will act to completely fill the joint cavity by readily wicking into available cracks and gaps in the joint. Further, the use of a low-viscosity sealant facilitates sealant delivery to the robot 17 via the umbilical 19, as lower viscosity sealants are more easily pumped along the umbilical 19. This can also allow for longer lengths of umbilical 19 to be used, enabling the robot 17 to be deployed to joints 23 further from the access point 22. At the same time, the tendency of the low viscosity sealant to run back out of the joint opening 29 and back into the pipeline 21 during the sealing process is reduced or avoided altogether, owing to the rapid formation of a cured layer 31 of sealant. However, use of higher-viscosity sealants may be acceptable or preferable, depending upon operational requirements, and the present invention is by no means limited to the use of low viscosity sealants.
Although the present sealing apparatus 18 is provided with a single nozzle 25 and light source 26, according to further variants, also being embodiments of the present invention, it may instead be provided with a plurality of nozzles 25 and a corresponding plurality of light sources 26, wherein each light source 26 irradiates an area in the vicinity of a respective one of the plurality of nozzles 25. This may beneficially decrease the time necessary to seal a given joint opening 29, and/or may be useful where a particularly large joint cavity needs to be filled.
Sealing apparatus 18 according to a second embodiment of a sealing apparatus aspect of the present invention will now be described with reference to FIG. 11, in which like parts are given the same reference numerals.
In the present embodiment, the baffle is omitted and the sealing apparatus 18 comprises a nozzle 25 to which a UV light source 26 is attached so as to be adjacent the nozzle 25. In the present embodiment, the UV light source 26 comprises a pair of UV LEDs 27 on a housing 32 mounted to a rearward part of the nozzle 25, such that the nozzle outlet 28 is located forwardly of the UV light source 26. This allows for the nozzle 25 to be inserted further into the joint opening 29. The UV LEDs 27 are arranged to illuminate in the circumferential plane of the joint. In the present embodiment, the UV LEDs 27 are high-powered, each being a 5W LED. This need not be the case, however, and different power LEDs, as well as a greater or lesser number of LEDs, may be employed as desired.
The sealing apparatus 18 of the present embodiment may be mounted to the robot 17 in place of the sealing apparatus 18 of the first embodiment, and the operation of the sealing apparatus 18 of the present embodiment is the same as for the first embodiment described above in relation to FIG. 8.
As with the first embodiment of sealing apparatus 18 described above, the present embodiment of sealing apparatus 18 may, according to further variants also being embodiments of the present invention, instead be provided with a plurality of nozzles 25 and a corresponding plurality of light sources 26, wherein each light source 26 irradiates an area in the vicinity of a respective one of the plurality of nozzles 25. This may beneficially decrease the time necessary to seal a given joint opening 29, and/or may be useful where a particularly large joint cavity needs to be filled.
Sealing apparatus according to a third embodiment of a sealing apparatus aspect of the present invention will now be described with reference to FIG. 12, in which like parts are given the same reference numerals.
The sealing apparatus of the present embodiment, shown generally at 18 in FIG. 12, again comprises a nozzle 25 for ejecting liquid sealant and a UV light source 26. However, unlike the first and second embodiments, in which the UV light is directed locally at the sealant injection point, the UV light source 26 of the present embodiment is instead arranged to irradiate the joint opening 29 over a wider area, in a floodlit manner. In particular, in the present embodiment, the UV light source is arranged to produce a band of UV light which extends completely around the inner circumference of the pipeline 21, so as to irradiate the entire joint opening 29, as shown in FIG. 13. This is achieved in the present embodiment by providing a plurality of UV lights 27 (which may for example comprise UV LEDs) at regular intervals around the entire outer circumference of a UV light source support member 33. The support member 33 is preferably mounted to the robot 17 so as to be located at a radially central position within the pipeline 21, to create an even UV intensity distribution around the joint opening 29.
The nozzle 25 of the present embodiment is located separately from the UV light source 26, and is mounted to the robot 17 (e.g. using a movable arm, not shown) to permit its selective insertion into joint openings 29 present on the interior side of the pipeline 21.
Operation of the present embodiment will now be described, with reference to FIG. 14.
Once the sealing apparatus 18 of the present embodiment has been moved into the region of a pipe joint 23 of the pipeline 21 using the robot 17, the nozzle 25 is inserted into the internal opening 29 of the pipe joint at a desired insertion point, such as at the bottom of the pipeline interior (step 1401). Once the nozzle 25 is in place, liquid UV-curable sealant, preferably of a low viscosity (under 3000 cP) in view of the benefits outline above, is then injected from the nozzle 25 into the opening of the pipe joint, and the UV light source 26 is operated so as to irradiate the entire internal pipe joint opening 29 with UV light (step 1402). In the same way as the first and second embodiments, liquid sealant seeking to escape from the pipe joint opening 29 will be cured by the UV light source 26 to form a cured layer which will prevent further liquid sealant from escaping from the joint. In the present embodiment, the entire joint opening is irradiated by the UV light source 26, meaning that it is not necessary to move the nozzle 25 around the joint opening 29. Rather, the nozzle 25 may be kept in position at a single insertion point, as liquid sealant seeking to escape from any point of the joint opening 29 as the joint cavity C fills with liquid sealant will be cured by the UV light source 26 (step 1403).
Preferably, the nozzle 25 is inserted at the bottom (i.e. lowest point) of the joint opening 29. This acts to maximise the quality of the seal, as injected liquid sealant will then tend to flow laterally, deep into the joint cavity C, before increasing pressure forces the sealant against gravity to flow to increasingly higher levels within the joint cavity C. In this manner, the sealant can be injected at a single point into the joint opening 29 to completely fill vacant areas within the joint cavity C, with the cured layer forming a wall as the height of the sealant within the joint cavity C increases. However, a seal may equally be created by inserting the nozzle 25 at other points within the pipe joint opening 29, including at the top of the pipeline 21, as well as at the sides.
According to a variant, also being an embodiment of the present invention, sealing apparatus of the present embodiment may also be provided with one or more additional nozzles (not shown), which enables the sealing apparatus 18 to inject liquid sealant into the joint opening 29 at a plurality of locations, simultaneously. This may beneficially decrease the time necessary to seal a given joint opening 29, and/or may be useful where a particularly large joint cavity C needs to be filled. As the UV light source 26 illuminates the entire joint opening 29 in a floodlit manner in the present embodiment, it is not necessary to provide any further light sources to cure liquid sealant leaking back from the joint opening 29 following ejection from the plurality of nozzles 25, although plural light sources 26 may be provided, as desired. Further, plural lights sources 26 may be provided to illuminate the entire joint opening 29, irrespective of whether or not a plurality of nozzles 25 are provided.
Although the above described embodiments utilise a UV light source and a UV-curable sealant, other light sources may instead be used according to further embodiments of the present invention, such as infra-red (IR) light sources and visible light sources, in combination with a sealant curable by the light source employed. In the present specification, "light" is accordingly to be interpreted as including any and all of UV light, IR light and visible light, and references to "light-curable material", "light source" and similar are to be interpreted accordingly.
More generally, embodiments of the present invention may employ any electromagnetic radiation source e.g. light or heat, as appropriate to cure the liquid sealant selected for a given application.
In still further embodiments, the curing of liquid sealant may be performed in ways other than the application of electromagnetic radiation. For example, where a two-part additive-based sealant is used, in which a second chemical component or activator is added to the liquid sealant to perform curing, the second chemical component or activator may be selectively applied around an opening to be sealed, so as to cure the sealant seeking to escape from the opening.
In addition to being curable by a primary curing mechanism such as light curing, the sealant used may according to further embodiments also be curable by one or more additional curing mechanisms e.g. one or more of an anaerobic curing process, curing with moisture, curing with heat, an addition-type curing process which is triggered by adding a second chemical component and/or activator to the liquid sealant, any other suitable additional curing mechanism, and any combination of the foregoing. In the case of the above-described embodiments, use of a sealant curable by one or more additional curing processes will allow it to be cured at regions deeper into the joint cavity C which would not otherwise be reached by UV light from the UV light source 26. This may be used to provide an enhanced and/or longer lasting seal.
In particular, the cross-section of the joint cavity C shown in FIG. 15A may generally be considered as comprising three areas, labelled as Area 1, Area 2 and Area 3 in the Figure, with boundary regions present on either side of Area 2. Movement of the joint in use (e.g. caused by expansion and contraction and/or loading from traffic etc.) can result in joint movement to and from positions 1 and 2 shown in FIG. 15B from the usual resting position 3 mid-way between these extremes. As shown by FIGS. 15C and 15D, this movement results in cured sealant present at Area 1 to be subject to compression and extension forces, which can degrade the seal by causing the cured sealant at Area 1 to peel away from the joint over time. On the other hand, cured sealant present at Areas 2 and 3 will instead be subject to shearing forces which are less likely to result in cured sealant peeling away from the joint, meaning that the seal provided at those areas will typically have a longer useful lifespan. This is particularly the case for cured sealant present at Area 3, which is subject to lower shearing forces than is experienced by cured sealant at Area 2.
Preferably, the one or more additional curing processes is/are slower acting than the primary curing process. For example, an additional anaerobic curing process will typically take between 1 and two hours to form an initial cured surface or "skin", and 2 to 3 weeks to cure completely. The use of a significantly slower additional curing process(es) will permit liquid sealant to reach deeper into the joint e.g. to Areas 2 and 3 in FIG. 15A, before being cured over time by the additional curing mechanism, further enhancing seal strength.
As noted above, the one or more additional curing mechanisms may for example include one or more of an anaerobic curing process, curing with moisture, curing with heat, an addition-type curing process which is triggered by adding a second chemical component or activator to the liquid sealant, or any other suitable additional curing mechanism.
As a leak site will enable dampness to enter the pipeline at the leak site, using a sealant which is curable by an additional moisture curing process beneficially means that the additional curing process will be triggered at the leak site itself, thus providing a seal directly at the leak site.
As for addition-type curing processes, a secondary curing process which is catalysed by the addition of metal ions may be selected in the case of sealing metal pipes such as iron or steel pipes. This is beneficial, as corrosion typically results in iron or steel pipes building up a layer of so-called "black powder", which is predominantly iron oxide, and is rich in metal ions. The metal ions from the black powder may therefore be used to catalyse the secondary anaerobic curing process, and to encourage the sealant to solidify and hence bind with the pipeline where the metal has corroded, further enhancing the seal. The robot 17 may also be provided with means (not shown) to scrape or otherwise obtain black powder from the interior surface of the pipeline and to mix the obtained black powder with the liquid sealant 30 prior to injection into the joint opening. This enables the additional curing process to be triggered by metal ions conveniently obtained from the black powder.
The foregoing embodiments have been described with reference to specific application in joint sealing and repair, and more specifically in sealing and repairing pipe joints in fluid-carrying pipelines such as gas pipelines. It will however be appreciated that the invention may be applied to sealing other pipeline leak sources, such as cracks or holes in a pipeline wall, or for example in sealing in the vicinity of a "cotter plate" repair to a pipeline, wherein a plate is bolted over a leak source area of a pipeline. In these types of applications, a suitable sensor array, user-operated camera or other device may be used to help identify the location of the crack, hole or other opening and/or gap between two bodies (e.g. a gap in the joint between the pipeline wall and a "cotter plate" repair plate). In embodiments employing a robot 17, the robot 17 may beneficially be provided with the sensor array, camera or other device for identifying the location of the crack or other opening.
Once the location of the crack or other opening has been identified, the foregoing processes are simply modified to conduct a repair accordingly.
For example, if using the robotic pipe repair system 16 shown in FIGS. 5 to 7 to repair a crack, the flow chart of FIG. 8 may be generally followed, but applied to repair the crack instead of a pipeline joint. Specifically, and as shown in FIGS. 16 and 17, crack repair may be conducted by moving the sealing apparatus 18 into contact or close proximity with a crack Cr in a pipeline 21 (Step 1601), injecting liquid sealant into the crack Cr whilst irradiating the crack Cr with UV light (Step 1602) and forming a boundary layer of cured sealant in the vicinity of the sealing apparatus 18 (Step 1603). If the crack is entirely covered by the area illuminated by the array of UV LEDs 27, performance of Steps 1601 to 1603 should repair and seal the crack. However, assuming that the crack Cr extends by a distance which is greater than the area illuminated by the array of UV LEDs 27 (as is the case in FIG. 17), the sealing apparatus 18 may then be moved to a further location along the crack Cr (Step S1604), with Steps S1601 to S1604 being repeated as necessary until a satisfactory crack repair is achieved.
Similarly, if for example the sealing apparatus 18 of FIGS. 12 and 13 is used e.g. in the repair of a crack, the process of FIG. 14 may generally be followed, but with Step S1401 modified by bringing the sealing apparatus 18 into contact or close proximity with the crack, instead of inserting the sealing apparatus 18 into a joint opening.
Yet further, embodiments of the invention may be applied in other areas going beyond pipelines, such as in repairing or sealing joints, cracks and other openings in articles and structures in general, and not merely pipelines alone. Also, embodiments of the invention may for example be employed in the filling of labyrinthine cavities in structures other than pipelines, whilst preventing sealant extruding back from the cavity opening.
A method embodying a sealant material delivery aspect of the present invention will now be described with reference to FIGS. 18A and 18B.
According to the present embodiment, a stream of UV curable liquid sealant material 34 (such as a UV curable sealant or adhesive) is ejected from a nozzle 35 into a region surrounded by a plurality of UV lights 36 (for example, UV emitting LEDs). The intensity of UV light produced by the surrounding UV lights 36 is adjusted to selectively harden the exterior of the ejected stream of UV curable material 34 into a cured layer extending partly or completely around the outer circumference of the stream of sealant. In this way, the ejected sealant material 34 can be formed into a tube which acts as an extension of the sealant nozzle 35. The illumination from the UV lights 36 is however such that the sealant nozzle 35 does not become blocked by cured sealant. In particular, the illumination from the UV lights 36 is such that UV light does not enter the sealant nozzle 35 itself; a baffle or shade may optionally be provided to guard against this occurrence.
The direction of the tube can be affected by suitable control of the intensity of the UV lights 36 surrounding the tube, enabling the tube to be selectively steered as desired, as shown in FIG. 14B, as the tube will act to move away from the most intense UV light source incident upon it.
In this manner, the sealant material 34 may itself be used to dynamically form the boundary of the vessel containing the uncured sealant material. In the present embodiment, this vessel is a tube, although this need not be the case, and suitable control of the UV lights 36 may be employed to dynamically create other shaped vessels. According to the present embodiment, it is also possible to direct the ejected sealant material by curing only a portion of the surface of the ejected sealant material 34. For example, by suitable control of the UV lights 36 it is possible to cure (i.e. harden) the stream of ejected sealant material on just one side. This results in the stream bending away from the light causing the hardening.
In a variant, a single UV light 36 is employed in the present embodiment, rather than a plurality of UV lights. The single UV light my for example be movable around the stream of ejected sealant material 34, to preferentially cure the surface of the stream of ejected sealant material 34 and hence direct its movement as described above.
The present embodiment, and its variant described above, may for example be used to facilitate the penetration of the sealant deep into a volume to be filled. This can also be used, for example, when joining two bodies or filling a cavity between two bodies where the cavity is open in more than one place. Although the present embodiment employs a UV-light source, other light sources including IR and visible light sources may instead be used, in combination with a sealant material 34 curable by the light source used. In still further embodiments, other curing mechanisms may be used instead of a light-based curing mechanism e.g. a heat-based curing mechanism.
When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.
The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.
Thus, the foregoing embodiments of the invention have been described by way of example only. It will be appreciated by a person skilled in the art that various modifications can be made without departing from the scope of the invention as defined by the claims.


Methods of creating tooling designs for, and the production of, one or more polarizer groups on a workpiece. Each such group includes an optically transmitting substrate with one or more discrete polarizer pixels thereon. The polarizer groups are used with optical instruments having a number of optical channels. In the method, one or more physical characteristics of at least one optical channel of the optical instrument are measured. Based on the determined physical characteristics, one or more discrete polarizer groups to be created on the substrate are defined, by defining for each such group a location on the substrate for the group, the size, shape and location within the group of each polarizer pixel of the group, and the polarization orientation for each such polarizer pixel of the group. The area of each polarizer pixel is then filled with tooling information that will establish its polarization orientation.

Methods of Optical Analysis
Photons from the ultraviolet, optical, and infrared portions of the electromagnetic spectrum have been used for over 100 years to investigate the properties of matter. These techniques, hereinafter referred to as "methods of optical analysis", include but are not limited to Raman spectroscopy, infrared (IR) spectroscopy, atomic absorption spectroscopy, diffuse reflectance spectroscopy, fluorescence spectroscopy, photoluminescence spectroscopy, and elastic scattering spectroscopy.
In Raman spectroscopy, a sample is irradiated with a substantially monochromatic light source. A small percentage of the incident photons absorbed by the sample are instantaneously re-emitted at slightly different wavelengths. These shifts in wavelength, referred to as Stokes or anti-Stokes shifts, result from changes in the rotational and vibrational states of the constituent molecules. The emitted spectra, captured in a backscattered configuration and analyzed with the spectrometer, reveal very specific information about the chemistry and structure of the sample, particularly information related to carbon-carbon bonds.
IR spectroscopy is similar to Raman, but operates at longer wavelengths. The method is sensitive to functional group vibrations especially OH stretch in water, and is good for studying the substituents on organic molecules. Also, the method can use the unique collection of absorption bands to confirm the identity of a pure compound or to detect the presence of specific impurities
Fluorescence spectroscopy is similar to Raman spectroscopy, in that a sample is irradiated with a substantially monochromatic light source and the re-emitted spectra is captured and analyzed by a spectrometer. However, in the case of fluorescence the emitted spectrum is derived from certain electronic transitions in the sample's constituent molecules. This spectrum is broader and more intense than Raman spectra, lacks Raman's fine structure, and occurs over an extended time frame. Fluorescence spectroscopy is used to determine the chemical constituents of a sample.
In diffuse reflectance spectroscopy (DRS), a broadband light source irradiates a turbid, translucent, or opaque sample. Certain wavelengths of light are selectively absorbed by the sample, and some are scattered. A spectrometer configured to capture backscatter analyzes the spectrum of the scattered rays. "Dips" in the spectrum, caused by absorption in the sample, reveal information about the molecular content of the sample.
In DRS, scattered photons captured by the spectrometer may have undergone elastic or inelastic scattering, or both. Elastic scattering spectroscopy (ESS) is similar to DRS, except that the geometry of the optical system is controlled so that only rays that have undergone high-angle elastic scattering are captured by a spectrometer. Mie scattering theory may then used to analyze the spectra. These spectra reveal information about the size of the scatterers, their index of refraction, the average distance between scatterers, and ranges of values on these measures. This technique has been used to analyze industrial materials such as slurries containing liquids and suspended particles. It has also been used to assess biological tissues. In this case, the ESS spectrum reveals the size of intracellular components such as nuclei and mitochondria. Enlargement of these components above normal levels may indicate a disease state such as cancer. The technique also reveals changes in chromatin density and granularity that may be associated with dysplasia.
In atomic absorption spectroscopy, a broadband light source and a spectrometer are arranged in an "opposed" configuration (facing each other) to measure gas-phase atoms. Since the samples of interest are usually liquids or solids, the analyte atoms or ions must be vaporized in a flame or graphite furnace in order to be analyzed. The atoms absorb ultraviolet or visible light and make transitions to higher electronic energy levels. The analyte concentration is determined from the amount of absorption as the light passes through the vaporized sample. This technique is capable of detecting very small concentrations of atoms or molecules in a sample.
Fourier transform (FT) techniques may alternatively be used with many of the optical analysis methods described above. FT techniques convert a time domain measurement to a frequency domain measurement, or vice versa. Instruments employing FT basically reveal the same information about a sample as a comparable instrument without FT, but an FT instrument may be optimized for higher resolution, higher speed, higher sensitivity, or other parameters.
The Use of Polarization in Optical Analysis Techniques
The term "polarization" refers to the spatial orientation of each photon's electromagnetic field relative to its direction of travel. Most naturally-occurring and manmade light sources produce photons with random polarization states. Lasers are generally highly polarized. In all of the optical analysis methods described above, non-polarized light may be used. However, with some of these techniques, the use of polarized light may enable benefits such as higher sensitivities, improved signal-to-noise ratios (SNRs) or additional capabilities.
For example, polarized atomic absorption spectroscopy systems such as the Hitachi Z-5000 offer lower detection limits with a smaller, simpler instrument design compared to non-polarized instruments.
Polarized Raman spectroscopy is used, for example, to determine the secondary and tertiary structures of membrane proteins in biological samples. By studying these aligned proteins with polarized Raman spectroscopy, additional data about the orientation of the bond-polarizability tensors with respect to the known polarization direction of the lazer is obtained. This information is combined with molecular models to infer details about the structure of the protein.
In the materials science field, optical strain gauges may also employ polarized Raman spectroscopy. Sensors are constructed by embedding carbon nanotubes in a polymer. Polarized Raman analysis is very sensitive to the strain transferred from the matrix to the nanotubes.
External Reflection Spectroscopy (IRRAS) is used to examine thin films on mirror-like substrates such as coatings and adhesives on metal surfaces. Using a grazing angle technique, the beam makes a high-angle reflection of approximately 88° from the sample and is polarized in the plane of incidence (p-polarization). Polarization sensitivity makes IRRAS useful in determining the orientation of molecules in relation to the metal.
In the polarized variant of ESS (PESS), a polarized broadband source is used to irradiate a sample such as biological tissue. Instead of the single optical channel used to measure the backscattered light in ESS, two channels are used in PESS. One channel is linearly polarized with the same spatial orientation as the source channel, while the other channel is cross-polarized. Since the polarization of backscattered photons depends on the number of scattering events the photon has undergone, and their subtended scattering angle, this detection method collects photons mostly from a well-defined region of the tissue and filters out many of the photons scattered from underlying and surrounding tissue. This enables measurements with high spatial sensitivity and high signal-to-noise ratio. Recent clinical studies have demonstrated the utility of PESS for the analysis of the surface layers of human tissues lining the outside of the body and body canals (epithelia). Carcinomas originate in epithelial layers, so sampling of this layer independently of the sub-epithelial layers enables the detection of atypical tissues at the earliest stages of growth. ESS and PESS investigations are currently being conducted in many parts of the body, including the gastrointestinal tract (oral cavity, esophagus, stomach, intestines), mammary ducts, bladder, urethra, cervix, and skin.
Fiberoptic Sampling Probes
In many applications, it is desirable to measure a sample in situ, rather than removing a sample from its original location for analysis in a laboratory. Examples in the medical field include measurements of human or animal tissue in vivo, either on the surface of the body, just below the surface using a percutaneous technique, or deep inside the body using an endoscope. Pharmaceutical and cosmetic applications include measurements of powders, slurries, suspensions, and solids. Environmental applications include field measurements of water in lakes and streams, and gases in smokestack emissions. Industrial applications include process control measurements in locations such as chemical plants, oil refineries, food processing plants, breweries, and fuel depots. Public safety, security, and forensic applications include detection of explosives residue, illegal drugs, and biohazards such as biological warfare agents, toxic chemicals, and microbial contamination.
In a number of these applications, physical access to the sample is limited. For example, in a lake it may be desired to take a measurement at a depth of 2 meters. In the body, a sample may be required deep in the esophagus. In a cosmetics factory, a sample may be required of a slurry inside a vat or flowing in a pipe. For many of these applications, it may not be possible or economical to bring the analytical instrument to the sample. Instead, fiberoptic probes often provide the optimal means of conveying light from the instrument to the sample, and/or from the sample to the instrument. Fiberoptic probes are efficient conductors of broadband light, are immune to electromagnetic interference, can be very long (up to hundreds of meters in length), and may be constructed to be flexible, with very small cross sections that can fit into tiny spaces.
Polarized Fiberoptic Probes
Implementing polarized detection in fiberoptic probes has advantages, but had historically been difficult to implement. Following is a discussion of issues pertaining to the use of fiberoptic probes for Polarized ESS (PESS). However, the main points of the discussion are also applicable to the other optical analysis methods discussed above, and are intended to illustrate the general case.
There are several design difficulties in trying to make small-diameter PESS probes suitable for certain applications, especially in the medical field for needle- or endoscopic-delivery in-vivo.
In order for PESS to work properly, broadband polarized light must be delivered to a sample, and two detection channels must conduct broadband light to spectrometers for analysis of the scattered light. The two detection channels must have orthogonal polarizations with high extinction ratios (at least 10:1, and preferably >100:1). Achieving high extinction ratios for two polarization modes over broad passbands is the principal challenge. For the PESS application, "broadband" means a passband of about 600 nm. For other applications, "broadband" may mean a passband as narrow as 20 nm.
Fabricating polarized optical probes may be approached in two ways. FIG. 1 shows the first approach. An analysis instrument 1 is optically coupled 2 to an optical probe 3. The probe contains one delivery channel 4 and two collection channels 5 and 6. The probe is in optical communication 7 with tissue or another type of sample 8. The polarizers 9 are placed between the probe 3 and instrument 1, and polarize the light as it is transmitted. This is the easier approach because the polarizers are inside the analysis instrument instead of being part of the probe, and so there is little constraint on their size or cost. However, with this arrangement the optical channels 4, 5 and 6 must maintain the polarization of the incident light as the light propagates along the length of the probe 3. If the channels are constructed using conventional optical fiber, polarization is lost, thus invalidating the measurement. While fibers that maintain the polarization state of transmitted light ("polarization-maintaining fibers") exist, they only offer acceptable performance over a maximum passband on the order of 20 nm. They are thus unsuitable for optical analysis methods employing broadband light.
The optimum optical architecture for PESS and other polarization-based architectures is to place the polarizers at the sample end of the probe. This is advantageous, as the light is polarized as it exits the delivery fiber on its way to the sample, and the scattered light is polarized as it enters the detection fibers. Since only light of the correct polarization enters each detection channel, loss of polarization as the light propagates along the length of the channel does not affect the measurement. This allows the probe to be constructed, for example, with relatively low-cost, commercially available broadband fiber (such as silica-clad-silica).
Nevertheless, this approach presents a number of difficulties. First, for the PESS application, since the probe is mainly intended for measurements of epithelial tissues, it is desirable to confine the sensing volume to the first 300 microns of tissue depth. This constrains the optical geometry of the distal tip—the delivery and collection fibers must be separated by no more than a few hundred microns, and their end faces must be in very close proximity to the tissue. To eliminate crosstalk caused by Fresnel reflections (i.e., light leakage from one optical channel to another caused by reflections from optical surfaces), any polarizer placed between the fibers and the tissue must have a thickness significantly less than the spacing between the fibers. This puts further constraints on the size and shape of the polarizers, as well as the fibers.
To be commercially viable, a single-use medical probe must also have a low manufacturing cost. This eliminates the use of any fabricated parts that have a high labor content. If the probe is reusable, the manufacturing cost can be higher, but the probe must withstand high temperature sterilization by steam autoclave. This puts additional constraints on materials, adhesives and optical coatings.
None of the conventional polarizer technologies has the necessary characteristics for this application. Dielectric thin film cube beam splitters rely on the difference in the reflectance of S and P polarization states with angle. This means that the surface on which the coating is deposited must be mounted at an angle to the optical axis. This is typically achieved by depositing the polarizing coating onto a 45° surface inside a cube beam splitter. Unpolarized light is split into S and P components at the 45° surface. However, placing a tiny cube at the sample end of a small diameter probe presents several difficulties. First, because the ray bundles exiting the delivery channels diverge, the cube must be significantly larger than the channel diameter, driving the overall probe size up. This makes its use infeasible in certain applications, especially certain parts of the body. Second, the cross-polarized collection channel requires the use of a second cube that is rotated 90° to the aligned cube. This complicates the design and increases the probe size further. For these reasons, probes using dielectric thin film cube beam splitters are typically in the range of 1″–4″ in diameter. Third, in order to prevent Fresnel reflections from the sample side of the beam splitter cubes, those optical surfaces must either be tilted or coated with a high efficiency anti-reflection coating, further increasing complexity and cost. The use of cube beam splitters thus does not lead to a commercially-viable disposable probe manufacturing cost in any volume.
Dichroic Sheet Polarizers have also been used by some researchers to construct fiberoptic probes. "Dichroism" is selective absorption of one polarization plane over the other during transmission through a material. Sheet-type dichroic polarizers are generally manufactured using films of organic materials. The film is stretched, aligning molecules into a birefringent geometry, and then dyed. The dye molecules selectively attach themselves to aligned polymer molecules, so that absorption is high in one plane and weak in the other. The stretched film is then bonded to a transparent substrate or sandwiched between a pair of sheets (glass, plastic, fused silica, etc.) to stabilize it and protect it from the environment. The transmitted beam is linearly polarized. Polarizers made of such material are very useful for low-power and visual applications. The main advantages of this type of polarizer are good performance vs. angle of incidence and thin substrate thickness. However, there are several problems with using dichroic polarizers for fiberoptic probes. First, none of the organic compounds used in these polarizers remains stable when exposed to the temperatures required for steam autoclave (>120° C.). Since steam autoclaving is the most common method of sterilizing reusable medical devices, this is a major impediment to commercialization. Second, none of the dichroic polarizers has the desired spectral bandwidth. Some are optimized for the UV, some for the visible, but none for both. This limits the clinical utility of the probe. Third, though the dichroic sheet polarizers have the shortest optical path of any polarizer, the commercially available ones are still too thick (˜200 microns—Polaroid Corp.). This results in Fresnel reflections from the sample side of the polarizer, which compromises signal to noise ratio. Fourth, it is difficult to cut, handle, and bond such a tiny disk of filter material to the end of a fiber probe. Because the films have been stretched in one axis, when mounted on thin substrates, these polarizers curl very strongly, contributing to difficulties in handling. This is exacerbated by the fact that tiny pieces of the film must be mounted with their polarization axes orthogonal to each other. Fifth, since the bonding area is so small, the polarizers could detach, especially if prone to curling, and especially if the probe is used multiple times. If they detached in-vivo, this could pose a health hazard.
Birefringent crystal polarizers have also been considered, but the crystals are typically in the range of several millimeters thick, making them impractical for small diameter probes. They are also too fragile to be placed at the distal end of a probe, and are too expensive for typical commercial applications, especially disposable devices.
Wire grid array polarizers use a periodic series of parallel wires etched or deposited onto a substrate, as described in U.S. Pat. No. 6,122,103. This array passes one polarization mode and reflects the orthogonal one. It offers very high transmission, high extinction, large acceptance angle, high temperature tolerance, and may be used oriented normal or inclined to the optical axis. Semiconductor lithographic methods are used to form the array of wires on the transparent substrate. However, commercial wire grid polarizers are typically deposited on substrates several mm thick. Using such a thick polarizer at the distal end of a small diameter probe would result in unacceptable performance due to Fresnel reflections. Also, wire grid polarizers have been used mainly in the display industry. Thus, the substrates typically have a large area, all with the same polarization orientation. This arrangement is called a "sheet polarizer".
For macro-sized optical systems employing individual free space optical elements, polarization management usually presents no problem, since individual polarizers may be placed in various parts of the beam path to achieve the desired result. In this case, conventional, macro-sized polarizers suffice. However, there are cases where the packaging constraints on the system prohibit the use of macro-sized optical elements, for example, where the optical system is designed to measure the characteristics of fluids in a narrow pipe. Further, there are cases where the geometry of individual optical channels themselves prohibits the use of macro-sized optical elements, as in a system where individual optical fibers comprise the separate optical channels.
Micro-optical systems are designed to operate in extremely small spaces, e.g., in the human body. For such micro-optical systems, optical channels may be spaced apart by as little as tens of microns. These channels are often formed by fiberoptics. Channels may be arranged in a linear fashion, in circles, or any fixed or random pattern. For certain optical systems it is necessary to polarize the light passing through these optical channels. Furthermore, adjacent channels may require different polarization orientations. A method is therefore needed to create a polarizer with multiple pixels with different polarization orientations. Conventional polarizer manufacturing technology cannot produce multiple polarizer pixels on a single substrate with the small size and placement accuracy necessary to reliably separate the individual channels.
In sum, none of the existing polarizer technologies has the combination of bandwidth, small size, thinness, low cost, durability, sterilizability, or ability to be formed into discrete elements (pixels) that would enable the construction of small diameter polarized probes. In addition, none of the polarizer technologies discussed is manufactured via processes that easily lend themselves to "mass customization", i.e., the production of large numbers of components that all have similarities, but unique differences as well.

Method of producing polarizers for polarized optical probes


A computer-implemented method, apparatus, and computer program product are disclosed for managing direct memory access (DMA) write page faults using a pool of substitute pages. A computer system platform resolves a DMA write page fault for a page that is dedicated to an Input/Output (I/O) adapter. The I/O adapter attempts to write DMA data to the page. A determination is made that the page is unavailable for writing. The DMA data is then written to data locations in a substitute page that was selected from the pool of substitute pages. A flag is then set in a flag location for each one of the data locations. The flag locations correspond to the data locations. When a flag is set, the flag indicates that DMA write data is present in the data location that corresponds to that flag's flag location.

1. Field of the Invention
The preferred embodiment relates generally to data processing systems and, more specifically, to a computer-implemented method, apparatus, and computer program product for managing DMA write page faults using a pool of substitute write buffer pages.
2. Description of the Related Art
According to a trend in computer systems, a system can be reconfigured while running without disrupting data processing. For example, with multiple operating systems running on the computer, while a first one of the operating systems is using a particular block of memory there can arise a need to reallocate the block of memory for use by a second one of the operating systems. In this case, the first operating system must first stop using the block of physical memory before the memory can be reallocated. Or, for example, a problem may be detected in a block of physical memory, in which case it may be desirable to remove the memory from operation so that it can be replaced. Once again, whatever operating system was using the block of memory must stop using it.
In certain respects it is relatively straightforward to stop using one block of physical memory and start using another, since mechanisms related to virtual memory management already exist in conventional operating systems to handle aspects of this problem that relate to operating system access to this memory. But these mechanisms depend upon the block of memory being used for only program data that is subject to access by operating systems and that is not subject to access by I/O devices. If the block of memory is subject to access by I/O devices the problem is more difficult. This access by I/O devices is commonly direct memory access (DMA), although this may not always be the case.
Blocks of memory subject to access by an I/O device, through the I/O device's I/O adapter, are conventionally "pinned," that is, exempted from being moved because access to them is restricted by essentially endless I/O programs that run as long as the operating system runs. It is disruptive to the system to stop such an I/O program that pins memory. By pinning these blocks of memory, the blocks of memory are essentially dedicated for use by the I/O device that has pinned the memory. One or more individual blocks of memory can be reserved, by being pinned, for use by a particular individual I/O device.
Pinning blocks of memory, however, is not particularly efficient for the computer system that includes the I/O device that has pinned memory for its use. These blocks of memory are typically underutilized. Although an I/O device may at some point need to use its pinned memory by writing to that memory, the memory often sits unused.

Computer-implemented method, apparatus, and computer program product for managing DMA write page faults using a pool of substitute pages

International Business Machines Corporation


A disk device is constituted such that a latch lever formed with a contact body and a latching body latches a slider and releases its latching action when a disk cartridge is inserted so that the disk cartridge is lowered and properly positioned. The latching body is formed with: a latching part for latching an engaging pawl of an engagement part of the slider; and a releasing part obliquely formed so as to separate the contact body from the end of the disk cartridge main body in response to the movement of the latching pawl in a latching releasing action.

1. Field of the Invention
The present invention generally relates to disk devices, and more particularly to a disk device constructed such that a disk cartridge accommodating a disk-shaped recording medium is inserted in the device and mounted therein. Still more specifically, the present invention relates to an improvement relating to a mechanism for mounting an inserted disk cartridge so as to be in a state in which recording/reproducing is enabled.
2. Description of the Background Art
A magnetic disk device is known as one type of disk devices described above. A magnetic disk device performs magnetic recording and reproduction using a disk cartridge accommodating a flexible magnetic disk (disk-shaped recording medium), wherein the cartridge is inserted from outside and mounted in the device (the device is loaded).
A conventional magnetic disk apparatus mainly comprises, for example, a slider and a holder provided on a chassis. The slider is latched to a predetermined position by means of a latch lever.
Specifically, when a magnetic disk cartridge accommodating a disk (recording medium) is inserted into a disk device and held in a holder, the cartridge activates a latch lever so as to allow the slider to slide toward a cartridge insertion opening. In an ejection operation, the slider is made to slide so as to release the latch lever from latching engagement, whereupon the cartridge is thrust and ejected out of the device.
FIG. 1 explains a latching operation of a latch lever of a conventional disk device. In a disk device 11 of FIG. 1, a latch lever 12 is rotatable around a pin 13. The latch lever 12 comprises: a contact part 12a which comes into contact with a disk cartridge 14; and an latching part 12b engageable with an engaging pawl 17 of an engagement part 16 of a slider 15.
The slider 15 is urged in the A direction by means of a spring 18. A groove 16a for allowing substantially conically shaped positioning pins 19a and 19b (the pin 19b is not shown) formed on a chassis (not shown) to be exposed is formed in the engagement part 16. The disk cartridge 14 has a shutter 14a which is openable and closable using the contact part 12a of the latch lever 12. Engaging depressions 14b1 and 14b2 (see FIGS. 2A and 2B) engageable with the positioning pins 19, respectively, are formed in the disk cartridge 14.
When the disk cartridge 14 is not inserted in the disk device 11, the engaging pawl 17 of the engagement part 16 of the slider 15 is latched to an inner curved edge 12b1 of the latching part 12b of the latch lever 12, and the contact part 12a is at a terminal position displaced toward the cartridge insertion opening (in the A direction).
When the disk cartridge 14 is inserted (in the B direction) into a holder (not shown) via the insertion opening, the end of the disk cartridge 14 is engaged with the contact part 12a of the latch lever 12. By thrusting the disk cartridge 14 further into the device, the latch lever 12 is rotated in the C direction indicated by an arrow. Due to the rotation of the latch lever 12, the shutter 14a of the disk cartridge 14 is moved in the D direction indicated by an arrow so that a head window 14c is opened. The engaging pawl 17 is unlatched from the inner curved edge 12b1 of the latching part 12b of the latch lever 12 and slides to a straight part 12b2.
Thereupon, the engaging pawl 17 moves along the straight part 12b2 in the E direction indicated by an arrow. That is, the slider 15 slides in the A direction indicated by an arrow by a force of the spring 18. In this state, the holder is lowered so that the disk medium in the disk cartridge 14 is chucked by a spindle motor (not shown), and the engaging depressions 14b1 and 14b2 of the disk cartridge 14 are engaged with the positioning pins 19a and 19b, respectively. Thus, the disk cartridge 14 is properly positioned.
Even when the engaging pawl 17 of the slider 15 is disengaged from the latch lever 12 due to the insertion of the disk cartridge 14 so that the slider 15 is allowed to slide, the contact part 12a of the latch lever 12 urges the disk cartridge 14 in the F direction indicated by an arrow.
FIGS. 2A and 2B show a relationship between the latch lever and the disk cartridge shown in FIG. 1. FIG. 2A is a top view, and FIG. 2B is a side cross sectional view. Referring to FIGS. 2A and 2B, the maintaining of the urging force exerted in the F direction by the contact part 12a of the latch lever 12 even when the latching engagement is absent, may result in the engaging depressions 14b1 and 14b2 settling on the slope of the conically shaped positioning pins 19a and 19b, respectively, while the disk cartridge 14 is being lowered due to the lowering of the holder. Accordingly, there is a problem in that a loading error may occur, wherein the disk cartridge 14 is not lowered to a preset position.
There is another problem that may occur in a process including the insertion and mounting of the disk cartridge. This problem will be described below with reference to FIGS. 3 and 4.
FIGS. 3 and 4 are plan views showing the shutter 14a of the magnetic disk cartridge 14. FIG. 3 is a top view, and FIG. 4 is a cross sectional view of the cartridge 14.
A cartridge main body 10 constituting the cartridge 14 is provided with a groove 10c at the lower major surface thereof, the groove 10c extending in the X1-X2 direction. Pawls 14a-2 and 14a-3 formed in the shutter 14a are engaged with the groove 10c. The shutter 14a moves in the X1-X2 direction while the pawls 14a-2 and 14a-3 are guided by the groove 10c. FIG. 3 shows a state in which the shutter is closed and resides at an end position displaced in the X2 direction.
However, when the cartridge 14 is inserted forcibly in the conventional disk device 11, a relatively large force is exerted on the shutter 14a as the shutter 14a begins to be opened. As a result, the pawls 14a-2 and 14a-3 of the shutter 14a may be dislodged from the groove 10c so as to reside on the surface of the cartridge main body 10 near the groove 10c. Thus, the conventional magnetic disk 11 has a problem in that the shutter 14a and the cartridge main body 10 may come apart.
Still another problem that may occur during the disk cartridge 14 insertion and mounting operation will be described below.
FIGS. 5A and 5B are cross sectional views of a conventional thin magnetic disk device comprising a frame 2 and a front bezel 3. The frame 2 is provided with raised parts 19c and 19d for positioning the magnetic disk cartridge 14 at a preset position. The raised part 19c has, at its center, the positioning pin 19a (19b) tapered toward the top. As shown in FIG. 6 on an enlarged scale, the front bezel 3 has a lower beam 3A and a upper beam 3B. The beams 3A and 3B are formed with notches 3A-1 and 3B-1, respectively, so that the magnetic disk cartridge insertion operation is easily performed. The lower beam 3A has a recessed step portion 3A-2 adjacent to the frame 2. The front of the lower beam 3A has a raised portion 3A-3 formed by the presence of the recessed step portion 3A-2. The recessed step portion 3A-2 forms, above its upper major surface, a space 4 for accommodating a rear edge 14b of the magnetic disk cartridge 14 when the magnetic disk cartridge 14 is inserted. As shown in FIG. 5B, the raised portion 3A-3 acts to hide a part of the inserted magnetic disk cartridge 14.
The magnetic disk device shown in FIGS. 5A and 5B has a magnetic disk cartridge mounting mechanism 5 comprising a holder 5A.
As shown in FIG. 5B, the magnetic disk cartridge 14 is mounted in a preset position such that the positioning depression 14d of a lower face 14c are engaged with the positioning pins 19a (19b), the lower face 14c rests on the raised parts 19c and 19d, and the rear edge 14b is accommodated in the space 4.
The mounting operation of the magnetic disk cartridge 14 is carried out in the following manner.
(1) An operator inserts the magnetic disk cartridge 14 from an opening 3a into the holder 5A, the shutter 14A at the leading edge of the cartridge.
(2) As shown in FIG. 5A, the operator uses his or her finger to thrust a rear end 14e of the magnetic disk cartridge 14 until the tip of the finger comes into contact with the notches 3A-1 and 3B-1 of the front bezel 3. In this way, the entirety of the magnetic disk cartridge 14 introduced into the magnetic disk device.
(3) When the magnetic disk cartridge 14 is settled in a position shown in FIG. 5A, the magnetic disk cartridge 14 releases the magnetic disk cartridge mounting mechanism 5 from a latch (not shown) so that the magnetic disk cartridge mounting mechanism 5 is activated.
In this state, the magnetic disk cartridge 14 is positioned such that the positioning depression 14d reside directly above the positioning pin 19a (19b), the rear end 14e resides at a position P2 slightly displaced in the A direction indicated by an arrow with respect to a position P1 of the edge of the raised portion 3A-3 of the lower beam 3A, and a front end 14i of the disk cartridge 14 resides at a position P10.
When the magnetic disk cartridge mounting mechanism 5 is activated, the holder 5A is moved in the Z2 direction to reach a height H2.
The magnetic disk cartridge 14 is lowered vertically together with the holder 5A so as to be mounted as shown in FIG. 5B.
It will be noted that, in order for the magnetic disk cartridge 14 to be mounted properly, the rear end 14e needs to be introduced deep enough into the device to reach the position P2 beyond the raised portion 3A-3 of the front bezel 3.
However, in thin magnetic disk devices in which the opening 3a of the front bezel is relatively narrow, the magnetic disk cartridge 14 may not be positioned at the position P2 (P10) without the finger of the operator being pressed hard against the front bezel 3.
As described above, the conventional magnetic disk device has a drawback with regard to the operability of the magnetic disk cartridge mounting operation.
There is another drawback with the conventional magnetic disk device in that, when the cartridge 14 is ejected forcibly, an oscillation may cause the latch lever 12 to be disengaged from the shutter 14a with the result that a magnetic head may be gripped by the shutter 14a.

Disk device in which erroneous closing of recording medium shutter is prevented


Insulins to which there is connected an amino acid oligomer have satisfactory properties.

Many peptides and proteins are attractive as drug candidates, due to their high bioactivities and receptor selectivities. Peptide and protein drugs are usually administered by injections and this can lead to low patient compliance. Alternative routes of delivery are therefore in demand. Delivery by the pulmonary or oral routes is possible, but usually complicated by low bioavailability due to high proteolytic activity in the relevant organs, and due to low absorption through the relevant tissue. Furthermore, in the human body, peptide and protein drugs are often eliminated quickly from the circulation by proteolytic activity or by elimination via the kidney or liver. It is, therefore, generally desired or necessary to manipulate the drug by formulation or derivatization in order to achieve suitable in vivo half-life.
The object of this invention is to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
An aspect of this invention is to improve the absorption of insulins through human tissues.
Another aspect of this invention is to improve the in vivo half-life of insulins.
Another aspect of this invention is to find insulins having a satisfactory physical stability.
Another aspect of this invention is to find insulins having a satisfactory chemical stability.
Another aspect of this invention is to find insulins having a satisfactory proteolytic stability.
Another aspect of this invention is to find insulins having a satisfactory solubility.


A receiving part receives, over a plurality of pulse reception sections, the echo of a transmitted pulse in a first range cell after a lapse of a first time period from a pulse transmission, and outputs a first signal based on the received echo. The receiving part also receives, over a plurality of pulse reception sections, the echo of the transmitted pulse in a second range cell after a lapse of a second time period from the pulse transmission, and outputs a second signal based on the received echo. A signal integrating part integrates a first number of first signals and outputs an integration result as a first range integration signal. The signal integrating part also integrates a second number of second signals and outputs an integration result as a second range integration signal. A target detecting part detects, based on the first and second range integration signals, a target.

The main fields of application of a conventional radar technique are defense and meteorology. The production of radar apparatuses in a small quantity is sufficient for those fields, and the achievement of requested performance is demanded even at the expense of cost. For an on-vehicle radar, which is a new field of application of the radar technique, however, the scale of mass production can be from tens of thousands to hundreds of thousands in number depending on the degree of market saturation, even millions in some cases. For the diffusion of the on-vehicle radars, production cost thereof is required to be reduced.
In order to supply a low-cost radar apparatus satisfying such requirements, besides a low-load signal processing method which replaces a signal processing method requiring a high-performance processing circuit as employed in the conventional radar technique, an antenna configuration is required to be simplified and to lower transmission power.
On the other hand, the on-vehicle radar has an object of detecting an obstacle in driving to avoid danger, thereby enhancing the driving safety. In some cases, a crucial process involving a human life has to be executed with good accuracy. Therefore, although it is true that the cost is required to be reduced, the performance of detecting a target is not allowed to be sacrificed. More specifically, a target present in a relatively wide angle range, in the range of 0 m to about 200 m in terms of the relative distance, is required to be detected within several milliseconds with a resolution of about 1 m.
Conventionally known radar systems include a pulse system, a pulse compression system (spread spectrum radar), an FMCW system, and a dual-frequency CW system. In the pulse system or pulse compression system radar apparatus, for example, in order to obtain a resolution of 1 m, a broadband over 150 MHz is required. In the case of the pulse compression radar, in particular, a computation load for correlation processing is large, requiring signal processing at a high speed. As a result, those systems are disadvantageous in terms of production cost reduction.
On the other hand, in the systems such as the frequency modulated continuous wave (FMCW) system, the dual-frequency CW system, and a multi-frequency CW system, it is known that a desired range resolution is obtained through signal processing at relatively low speed. Therefore, because those systems have an advantage in that the demands for reduction in production cost and increase in resolution can be satisfied at the same time, they are expected to be used for the on-vehicle radar.
In reality, however, those systems using a continuous wave (CW) as a transmitted wave (hereinafter, the radar systems using a continuous wave are collectively referred to as "CW system") has significant tasks such as ensuring isolation between transmission and reception and taking countermeasures against unnecessary reflected wave with a small propagation loss from a short range (nearby clutter). Therefore, in order to cope with such problems, systems including a frequency modulated interrupted continuous wave (FMICW) system in which a continuous transmitted wave is pulsed are known.
Further, the on-vehicle radar is required to detect a target present in a wide angle range, such as vehicles running ahead in a plurality of lanes. In order to satisfy the requirement, an antenna system for mechanically driving an aperture antenna, a multi-beam antenna system, a phased-array system including an array antenna, a digital beam forming (DBF) system, and the like are known.
Among the above systems, the mechanical driving systems require a long observation time for observing a reflection source in a wide coverage. Therefore, it is difficult to enhance response performance. The multi-beam antenna system for simultaneously emitting transmitted beams in multiple directions and the phased-array system including an array antenna which uses electrical phase control to change a beam scanning direction within a short period of time have no problem in response performance. However, those systems are not suitable for mass production because the mechanism of the antenna is too complicated.
On the other hand, the DBF system realizes beam formation by digital signal processing and is advantageous in excellent process adaptability, scalability, and high-resolution. In particular, the on-vehicle radar is requested to detect an object present in a wide coverage within a short period of time (ideally, within several milliseconds). Therefore, the combination of a beam having a large beam width referred to as wide-angle beam or fan beam and the DBF system is advantageous as a system for the on-vehicle radar.
The wide-angle beam has such a wide beam width that a single pulse illuminates the entire requested coverage. With the combination of the wide-angle beam and the DBF method, after a beam having such a wide beam width that the requested coverage can be covered at one time is transmitted, an echo of the transmitted beam is captured by an array antenna. Thereafter, according to the DBF method, an output signal from each of element antennas of the array antenna which has captured the beam is subjected to digital signal processing to form a beam in an arbitrary direction (see, for example, Patent Documents 1 and 2).
In this manner, a mechanism of controlling a beam direction is simplified while the overhead of beam scanning is kept minimum. At the same time, a target in the requested coverage can be detected within a short period of time. In addition, the combination of the wide-angle beam and the DBF method can be further combined with the radar principle such as the FMCW system, the dual-frequency CW system, and the multiple-frequency CW system. Further, the pulsation of the wide-angle transmitted beam solves most of the problems caused in providing a practical on-vehicle radar.
Patent Document 1: U.S. Pat. No. 5,497,161 A
Patent Document 2: JP 3622565 B2

Target detecting method and target detecting apparatus