An Optical Coherence Tomography (OCT) device irradiates a biological tissue with low coherence light, obtains a high resolution tomogram of the inside of the tissue by low-coherent interference with scattered light from the tissue, and is provided with an optical probe which includes an optical fiber having a flexible and thin insertion part for introducing the low coherent light. When the optical probe is inserted into a blood vessel or a patient""s body cavity, the OCT enables the doctor to observe a high resolution tomogram. In a optical probe, generally, a fluctuation of a birefringence occurs depending on a bend of the optical fiber, and this an interference contrast varies depending on the condition of the insertion. The OCT of the present invention is provided with polarization compensation means such as a Faraday rotator on the side of the light emission of the optical probe, so that the OCT can obtain the stabilized interference output regardless of the state of the bend.

1. Field of the Invention
The present invention relates to an optical imaging device which irradiates the subject with low coherence light, to produce a tomogram of the subject, from data on light scattered by the subject.
2. Description of Related Art
Recent U.S. Pat. No. 5,321,501, for example, discloses a device which can obtain optical information from the inside of the tissue, in order to diagnose the biological tissue, and which performs optical coherence tomography (OCT) of interference type, using low coherence light, to produce a tomogram of the subject. U.S. Pat. No. 5,321,501 also discloses an optical probe which has a flexible insertion unit to be introduced into the patient""s body cavity, and which enables the doctor to introduce the insertion unit into a blood vessel, using an optical probe that includes a single mode fiber for sending low coherence light to the inside so that the doctor can observe the inside of the patient""s body cavity, using a catheter or endoscope. When introduced into the patient""s body cavity, the optical probe is necessarily bent according to the tortuosity of the body cavity. Because of the bending, stress-induced birefringence is induced in the optical fiber which varies according to the extent of the bending. In OCT, the doctor uses an interference signal of a reference beam with reflection from the subject, to observe the subject. It is necessary, generally, to orient polarization of the reflection from the subject, toward that of the reference beam so that interference with the reference beam may be maximized. The stress-induced birefringence varies depending on the bending in the patient""s body cavity; polarization, therefore, varies depending on the bending. As introduced into the patient""s body cavity, the insertion unit varies interference contrast. The doctor may turn an integrated irradiation optical system that includes the single mode fiber. Every rotation of the bent system, particularly in such cases, causes a great variation in the stress-induced birefringence of the fiber. Interference contrast varies, so that detection sensitivity greatly varies depending on the direction of rotary scanning. Such a great variation is a problem.
xe2x80x9cPolarization-insensitive fiber optic Michelson interferometerxe2x80x9d (Electr. Lett. Vol. 27, pp. 518-519, 1991 ) discloses a method of inserting an element that rotates polarization by 45 degrees in a non-reciprocal manner such as a Faraday rotator, in order to compensate for a variation in interference contrast due to the fluctuations in stress-induced birefringence of such a fiber. A general Faraday rotator, however, requires a garnet crystal, and magnetic material that provides a magnetic field for the garnet crystal. It is impossible to provide such substances at the narrow probe tip to be introduced into the patient""s body cavity.
xe2x80x9cIn vivo video rate optical coherence tomographyxe2x80x9d (A. M. Rollins et al., Internet, 1998 Optical Society of America) discloses a method of high-speed scanning of an interference location in OCT, with the reference arm group delay mechanism using a galvanometer mirror. To scan the location at a high speed by rotating the mirror, the inertia of the mirror will dictate that the rotational position of the mirror, if plotted with respect to time, would approach a sine wave oscillation. The depth scan of the interference location is proportional to the mirror rotational position. Because the mirror rotates first in one direction and then in the other, it is difficult to reproduce a two-dimensional image from the obtained interference signals. If the device uses an interference signal obtained by scanning in only one direction, it will neglect half the actually obtained signal data. In such cases, if the doctor continues rotary scanning of the optical system in the optical probe, he or she will provide only half the resolution and dynamic range for a two-dimensional image. Such a decrease in resolution and dynamic range is a problem.
In the above-mentioned high-speed scanning, the use of a resonant scanner, for example, ensures that the time vs. scanning angle curve is a sine wave, not linear. A two-dimensional position and intensity graph, however, may be used to represent an interference signal. Otherwise a shaded image may be used to express intensity as shades, based on the two-dimensional interference locations and detection positions. In such cases, to display interference signals accurately, it is impossible to use the interference signals obtained in time series, because the interference signals are linear with respect to time, and because the interference location is nonlinear with respect to time. A tomogram of the biological tissue inside, for example, may be produced. In such cases, if the device fails to indicate accurately the interference location and the detection position, the image produced will be warped, and it is impossible to accurately measure length with a scale.
As described above, the device may use a nonlinear scanning means such as a resonant scanner. Depending on the scanning angle, in such cases, the Doppler frequency (which characterizes the interference signal produced) varies in proportion to the scanning speed of the interference location. Optical heterodyne detection in OCT uses this Doppler frequency for detection; therefore, it ensures high signal-to-noise ratio. If the scanning is nonlinear, the Doppler frequency may vary. In such cases, if the frequency characteristics of the demodulator circuit are set so that the demodulator can detect all possible interference frequencies in a wide range, then the detection will include excess noise, and result in a decrease in the signal-to-noise ratio. The inferior signal-to-noise ratio is a problem.
If the subject is scanned in a two-dimensional manner, methods of enlarging a part of the displayed image include: a method of cutting unnecessary parts away from that part; and a method of changing the scanning range. Changing the scanning range may require adjusting the speed of scanning the interference location, to the change in scanning range. To improve the signal-to-noise ratio, scanning the interference location may be slowed. In these cases, the Doppler frequency may also vary; therefore, setting the frequency characteristics of the demodulator will pose a similar problem.
As disclosed in U.S. Pat. No. 5,321,501, an optical probe to be introduced into the patient""s body cavity, generally, needs to be detachable from the observation device body for the purpose of cleaning and sterilizing. If detachable, a broken optical probe can be easily replaced with a new one. During assembly, single mode fibers undergo various stresses. Consequently, when provided in each optical probe, each single mode fiber may produce a distinct intrinsic birefringence. Whenever replacing probes, the doctor has to use a polarization plane adjustment means to orient, toward polarization of the reference beam, polarization of reflection that can be obtained by the optical probe, from the subject. It is necessary to maximize contrast of interference with the reference beam. The work is troublesome.
As disclosed in xe2x80x9cIn vivo video rate optical coherence tomographyxe2x80x9d (A. M. Rollins et al.), a galvanometer mirror or resonant scanner mirror may be used for high-speed scanning of the interference location in OCT. Because of the inferior temperature characteristics, the galvanometer mirror and the resonance scan mirror vary the scanning range and scanning speed, depending on the variation in temperature.
As disclosed in the above cited Rollins et al. Publication xe2x80x9cIn vivo video rate optical coherence tomographyxe2x80x9d, a galvanometer mirror or resonant scanner mirror may be used for high-speed scanning of the interference location in OCT. In such cases, in order to maximize drive speed, the mirror will be driven so that the drive curve may approach a sine wave. As described above, the nonlinear drive results in a nonlinear relationship between the interference location and interference signals obtained in time series. Such a nonlinear relationship is difficult to handle. The inferior signal-to-noise ratio, aggravated by setting the frequency characteristics of a demodulator, is a problem.
When displayed on the screen, an OCT tomogram is drawn using optical length, which greatly differs depending on the medium. As the medium, air, for example, has a refractive index n of approximately 1; whereas the biological tissue has a refractive index n of 1.3 to 1.5. When displayed on the screen, optical length is n times the actual length. Such difference causes a significant error, and that is a problem.
The outer sheath with optical permeability is generally made of a resin tube such as fluorine resin and polyamide (nylon). Since the refractive index of the resin tube greatly differs from that of air sealed between the optical element and the outer sheath, significant light reflection occurs at the index of refraction interface between the air inside the outer sheath and the sheath material itself. Similarly, significant reflection also occurs at the index of refraction interface between the outer sheath surface and the air, water or gastrointestinal fluid outside the sheath. The reflection attenuates the irradiation and observation light, thus degrading the S/N ratio for observation.
Since OCT, in principle, detects the correlation between the reflection intensity on the optical path and the optical path length, presence of two faces with intense reflection in the vicinity will cause a degradation in the amount of optical power available for image formation. They will also result in the formation of reflections at the probe sheath surfaces which could be large compared to any tissue reflections, and will thus tend to overwhelm the dynamic range of the detection electronics and make it difficult to display weak tissue reflections on the same screen as the strong sheath reflections. Furthermore, multiple reflections may form between the reflecting surfaces, resulting in the generation of ghost images of the tissue where no actual reflection surface exists. The observation light, which is light scattered and reflected by the living body, is relatively weak light when compared with the above mentioned reflection intensity, the ghost will considerably deteriorate the observation performance. This is especially damaging if the ghost image appears at the same location as the actual tissue image, in which case there is no simple way to separate them.
On the other hand, xe2x80x9cIn vivo Endoscopic Optical Biopsy with Optical Coherence Tomographyxe2x80x9d (G. J. Tearny et.al, Science vol.276) disclosed an OCT optical probe which has a transparent sheath to cover and seal up to the optical element such as the prism at the tip end.
The prior art suffers from problems that when the endoscope with the probe inserted through its insertion opening is inserted into a body cavity or when the probe is bent, the rotating support for the optical element at the tip end comes into contact with the interior of the outer sheath and damages the interior, that optical characteristics of the outer sheath are degraded by irregular reflection of lights at the damaged portion, and that the observation quality deteriorates as the OCT irradiation light emitted by the optical element and observation light reflected by the living body are shielded.
Even when the damage on the sheath does not coincide with the irradiation or observation light position, the damage appears at the location of observation light since the rotary sheath reciprocates against the outer sheath because of the bending shape of the probe.
Furthermore, probe sheaths made from such materials as fluorine resin and polyamide have very poor optical quality, such that they have randomly spaced internal index of refraction boundaries, internal striations, and particulate scatterers which act to degrade the wavefront of light propagating though them and to scatter a significant portion of light into unpredictable directions. Since the probe design depends upon light being directed to a diffraction-limited focussed spot in the tissue and then being re-coupled into the single mode fiber on the return path, any passage through elements which degrade the optical wavefront or scatter light severely degrades the re-coupling of image-forming light into the probe and the heterodyne efficiency of the OCT interferometer. Thus, a probe window of high optical quality would be highly advantageous to obtain the best possible OCT image quality.
As mentioned above, recently an OCT device has been developed for observing tomography structure of a living body by using a low coherence light length of interference. For observing the tomography structure by using the low coherence light, a method is used for dividing light from a light source for generating the low coherence light into signal light and reference light, irradiating the signal light to an observed object, after that, composing the reflected light from the object measured with the reference light again, and detecting the interference light between both of them. Then, as it is possible to obtain the interference light at only the place that length of an optical path of a flux of the signal light is agreed with that of the reference light when changing the length of the optical path on the side of the reference light, it is possible to obtain the same effect as scanning the place for observing the measured object by changing the length of the optical path on the side of the reference light, and to possible to observe the tomography structure of the measured object.
FIG. 1 shows an example that of OCT is applied to an endoscope. The light from a low coherence light source 202 is combined with a single mode fiber 205 and is led to a coupler 204. The light is divided the light into the signal light 206 and the reference light 207 by the coupler 204. The light on the side of the reference light 207 divided is lead via lens 209 to a means 214 (scanning mirror) for changing the optical path 214 by the single mode fiber 205. The light returned from the means for changing the optical path 214 is returned to the coupler 204 by the single mode fiber 205 again.
On one hand, the light divided on the side 206 of the signal light is led to the end optical system 208 on the side of the signal light 206 by the single mode fiber 205 different from on the side of the reference light 207, irradiated to the measured object, reflected from the measured object, returned, therefore, is composed to the light returned from the side of the reference light by the coupler 204 through the end optical system on the side of measuring and the single mode fiber again. The composed light returned on the side of referring and measuring is led to a detector 212 by the single mode fiber 205 and the interference signal is detected by the detector 212.
FIG. 2 is a cross-sectional view showing non-prior art enlarged details of an end part on the side of measuring in the FIG. 1.
The end optical system 208 is constructed at the end of the single mode fiber 205. In the end optical system, a lens unit 220 contains a refractive index distribution lens (Gradient Index lens: GRIN lens) 221 for gathering the light to a living body, a Faraday rotator 222 for canceling the influence of polarization caused by bending of the single mode fiber 205 and prism 223 for changing the direction of the light. Further, the cylindrical transparent sheath 225 covers the outside of the lens unit. As shown by arrow 219, the single mode fiber 205 and the lens unit 220 are rotated as the longitudinal direction (the central axis of the cylindrical sheath 225) is an axis. As above mentioned by rotating the mechanism, it is possible to observe the measured object not only in the cross-sectional direction but also radially.
In the above described related art, the end optical system 208 has a problem in that after light outgoing from a single mode fiber 205 is reflected several times on the boundary surface of a optical elements such as a Faraday rotator 222, a refractive index lens 221, prism 223 and sheath 225 and returned to the single mode fiber 205 again, an image of a living body and ghost overlaps and quality of the picture is degraded.
The reasons for that are described in reference FIGS. 3(A)-3(E).
FIGS. 3(A) through 3(E) show an example of causes for generating ghosts, and behavior of the light outgoing from the single mode fiber is schematically shown as time passes.
FIG. 3A: When the light outgoing from a single mode fiber 205 comes to the boundary surface between the refractive index distribution lens 221 and a Faraday rotator 222, part of the light, light a, but part b penetrates is reflected rearwardly toward the single mode fiber 205 again.
FIG. 3B: Light b is then again reflected by the rear surface of the refractive index distribution lens 221 and is directed toward the object. Light a, however, passing as it was in the FIG. 3A, proceeds through the Faraday rotator (FR) 222 and the prism 223 to the middle of the sheath 225 and the tissue 226 of a living body.
FIG. 3C: Light a is reflected in tissues 226 of a living body and directed back toward the single mode fiber 205. Meanwhile, light b is proceeding though the refractive index distribution lens 221 to the side of the object.
FIG. 3D: Light b is reflected on the boundary surface between prism 223 and FR 222, and is directed back toward the single mode fiber 205 again. Then, light a arrived at the boundary surface between the prism 223 and the FR 222, and overlaps light b.
FIG. 3E: Overlapped light a and light b is return to the single mode fiber 205.
In case of the conditions above mentioned, the signal light from the tissue 226 of the living body and light b reflected in the end optical system several times overlap, and an image when seeing the tomography structure of the living body is that the image 228 (FIG. 4) of the ghost due to light b overlaps the image 227 of the tissue of the living body.
The image 228 of the ghost is often remarkable when the number of times of reflection on the end surface of the optical element is less than three times. Generally, as strength of reflection per surface of the optical element is fromis xe2x88x9220 dB to xe2x88x9230 dB relative to the incident light, when the number of times of reflection on the end surface of the optical element is three times, total strength of reflection is from xe2x88x9260 dB to xe2x88x9290 dB, and when the number of times of reflection is four times, it is from xe2x88x9280 dB to xe2x88x92120 dB. On the other hand, strength of the signal from the living body is xe2x88x9250 dB to xe2x88x9270 dB. Therefore, when the number of times of reflection on the end surface of the optical element is even less than three times, it can be almost the same level as the strength of the signal of the living body and causes difficulty in observation.
The path of the reflective light as above mentioned is an example; multiple reflection in the real end optical system occurs in various paths except besides the path as above mentioned. Particularly, there are problems when the shape of the sheath is cylindrical because it is difficult to treat to prevent reflection from the surface of the sheath, and it is easy then for light reflected three times to overlap on the observing position.
One more problem of the above mentioned end optical system is the structure of the end optical system in that the light outgoing from the single mode fiber is reflected on the boundary surface of the optical element and the reflected light is directly returned to the single mode fiber 205. If the such structure as is called the structure of once reflection, xe2x80x9cstructure of once reflectionxe2x80x9d, in the optical system, the structure of once reflection will reflect the reflected light from all the boundary surfaces except the end surface on the side of the fiber of the refractive index distribution lens.
If the structure of the optical system is the structure of once reflection and the light reflected from the end surface of the optical element is incident on the single mode fiber, unnecessary light will return to the single mode fiber and an S/N ratio when detecting the interference signal will be significantly reduced. Therefore, if the structure of the optical system is the structure of once reflection, it will be hard to see an observing screen.
FIGS. 5A and 5B show an example of the structure of once reflection that the light is reflected on the boundary surface between a Faraday rotator 222 and prism 223, wherein FIG. 5A represents the actual optical path, and FIG. 5B represents by folding the optical system from the reflected surface so that it is easy to understand the optical path. It is known from FIG. 5A that the reflected light returns to the single mode fiber 205 again. In the optical system, the light reflected by another boundary surface returns to the single mode fiber 205 again similarly to the example as above mentioned.
Next, FIG. 57A is a schematical view showing an end optical system of an optical scanning probe from the side of en end and FIG. 57B is a schematical view showing from a side surface. As shown in FIGS. 57A and 57B, the end optical system includes a transparent Teflon tube 320, a prism 308, a GRIN lens 311 and a single mode fiber 301. Light guided into the single mode fiber 301 is incident on GRIN lens 311, prism 308 and Teflon tube 320 and becomes an observing beam 317. The Teflon tube 320 has a concave lens effect in the peripheral direction of a cylindrical surface of the tube. Therefore, a focal distance 319 a in the peripheral direction to a sheath cylindrical surface of the observing beam 317 is longer than a focal distance 319 b in the longitudinal direction of the sheathe.
In the related art shown in the FIGS. 57A and 57B, relation of positions between the focal position 319a in the peripheral direction and the focal position 319b in the longitudinal direction to the sheath cylindrical surface of the observing beam 317 is fixed and impossible to change.
In view of the above problems of the related art, an object of the present invention is to provide a optical imaging device to compensate for a variation in interference intensity, due to the variation in birefringence of the fiber in an optical probe, even if the optical probe is bent in a patient""s body cavity. Further, the optical imaging device provides a physically small birefringence compensation means such that it can be included at the optical probe tip. Further, the device compensates for a variation in interference contrast, due to the variation in birefringence of the fiber, caused by every rotation of the bent and turned system. Further, the device makes the birefringence compensation means of the Faraday rotator function effectively. Further, the device provides a physically small composition of the distal optical member for the optical probe.
Another object of the present invention is to provide an optical imaging device to obtain an interference signal corrected so that scanning can be regarded as performed in the same direction, even if the scanning direction oscillates due to the swing of the swing mirror in the propagation delay time-varying means. Further, the optical imaging device prevents the corrected interference signal from deviating, even if slight hysteresis or deviation, during scanning to and fro, is caused by the hysteresis of temperature characteristics and dynamic characteristics, when the device uses a high-speed scanning mirror, such as a galvanometer mirror and a resonance scan mirror in particular. Further the device performs the above-mentioned correction automatically.
Furthermore, an object of the present invention is to provide an optical imaging device to obtain an interference signal which is linear with respect to spatial distance from the probe tip, even if scanning the interference location is nonlinear with respect to time.
Furthermore, an object of the present invention is to provide an optical imaging device to enable the demodulator to detect the envelope of the interference signal with a high signal-to-noise ratio, even if the Doppler frequency of the interference signal is varied by the variation in speed of scanning the interference location.
Furthermore, an object of the present invention is to provide an optical imaging device to adjust the plane of polarization automatically.
Furthermore, an object of the present invention is to provide an interference location scanning means which has a scanning range and scanning speed that are difficult to disturb from the outside.
Furthermore, an object of the present invention is to provide an interference location scanning means which has the ability to perform high-speed scanning that is nearly linear.
Furthermore, an object of the present invention is to provide an optical imaging device to measure length on the screen correctly, whatever the refractive index may be.
Furthermore, an object of the present invention is to provide means for attenuating the reflection on the inner or outer surface of the outer sheath.
Furthermore, an object of the present invention is to make the inner side of the outer sheath resistant against damage by the rotating optical element and to have a sheath with good optical quality in the region of the probe where signal light is transmitted.
Furthermore, an object of the present invention is to provide an end optical system on the side of the signal light of OCT in which ghosts do not appear, the S/N ratio is good, and the ability to observe is excellent considering the problems as above mentioned.
Furthermore, an object of the present invention is to provide an optical scanning probe for advancing the S/N ratio.
Furthermore, another object of the present invention is to provide the optical scanning probe in which the observing depth degree is large
Furthermore, an object of the present invention is to provide the optical scanning probe with optics that are easy to assemble and manufacture.
According to the present invention, variations in interference intensity, due to the variation in birefringence of the fiber in the probe, are compensated for, by the provision of a polarization compensation means on an optical path, from the emission end of the single mode fiber in the optical probe to the subject. Further, a physically small polarization compensation means can be provided at the optical probe tip, because the Faraday rotator uses a magnetic garnet crystal. Further, almost all substantially parallel rays incident on the Faraday rotator will cause the plane of polarization to rotate by 45 degrees accurately, to produce high efficiency in polarization compensation.
Further, according to the present invention, the device has a first memory means for preserving an interference intensity signal that corresponds to a particular one-way swing based on the detection by the reference position detection means, and a second memory means for preserving an interference signal that corresponds to a swing in the opposite direction to the particular one-way swing. Backward reading of data stored in the first memory means and forward reading of data stored in the second memory means produces interference signals that indicate scanning in the same direction. Further, different delays are provided for first memory means and the second memory means so that data, stored in the first memory means and the second memory means, may be read at delayed points of time. Controlling the delays correct hysteresis and deviation caused by slight differences in the scanning directions to and fro. Further, a reference signal is detected in each interference signal, and the delay setting means is adjusted so that both reference signals coincide with each other at the position of the reference signal. It is possible, thereby to correct automatically hysteresis and deviation caused by the to and fro scanning.
Further, according to the present invention, the use of a memory means for preserving interference intensity signals in time series, and a calculation means for calculating a memory address that corresponds to the interference location, to calculate the address, and to read data stored in the memory, produce an interference signal that corresponds to the interference location.
Further, according to the present invention, the device uses a calculation means to calculate the Doppler frequency of an interference signal produced by scanning the interference location. Changing the frequency characteristics of the demodulator, according to the calculated Doppler frequency, can constantly set the demodulator, to produce a high signal-to-noise ratio.
Further, according to the present invention, the device uses reference reflection means provided close to an end of the optical probe insertion unit, and obtains reflection data from the reference reflection means, in the form of an interference intensity signal produced from the interference means. Only setting a polarization adjustment means so that the interference contrast signal may be maximized, generally, is needed to adjust the plane of polarization for each probe automatically.
Further, according to the present invention, the propagation delay time-varying means has a dispersive means, imaging means, and reflection mirror. The reflection mirror includes a polygon mirror. The rotation of the polygon mirror enables scanning the interference location. It is easy to stabilize the scanning range and scanning speed, because the polygon mirror scanning is nearly linear with respect to the time series, and because it is easy to stabilize rotation speed.
Further, according to the present invention, when the reflection mirror is scanned by a resonant mechanical scanner, the scan becomes more linear by providing a specialized drive signal including one or more additional higher frequency harmonic components.
Further, according to the present invention, the optical imaging device comprises one or more scales that include a scale indicating an optical length in medium, or a scale indicating an optical length in the tissue, or a scale indicating optical length in the medium in those regions of the image representing the medium and which indicates optical length in the tissue in those regions of the image representing the tissue.
Also, a rigid light permeability part made from an optical quality material such as glass or fused silica has no internal index of refraction boundaries, striations, or scatterers, and can be manufactured or polished in such as way as to provide a good optical surface on the inside and the outside.
Further, according to the present invention, as light that the number of times of reflection on the end surface of an optical element of an end optical system on the side of signal light of an optical tomography diagnosis device is less than three times does not return to a single mode fiber, it is possible to obtain the end optical system on the side of the signal light of the optical tomography diagnosis device that ghost does not appear and a S/N ratio is advanced.
Further, according to present invention, by matching agreeing the focal position in the peripheral direction of the cylindrical surface of a sheathe with the focal position in the longitudinal direction of the sheathe and by concentrating the focal point to a point in an observing beam outgone from the optical scanning probe, an optical scanning probe for advancing the S/N ratio is provided.
Further, according to present invention, by making the beam spot diameter of an observing beam almost uniform over a long distance in the direction of the major axis of the observing beam., the optical scanning probe that observing depth degree is large is provided.
Further, according to the present invention, by placing reflection reduction coating inside or outside or both of the probe sheath, the reflection on the border of inner or outer medium to the sheath is reduced and thus the ghost and the light intensity reduction caused by reflection is avoided.
Further, according to the present invention, by placing a rigid light permeability part on the optical window where an optical emitter and receiver are located, the optical characteristics of the outer sheath are not degraded even when the rotating support for the optical element at the tip end comes into contact with the interior of the outer sheath. Also, a rigid light permeability part made from an optical quality material such as glass or fused silica has no internal index of refraction boundaries, striations, or scatterers, and can be manufactured or polished in such a way as to provide a good optical surface on the inside and the outside.
Further, according to the present invention, as light does not return to a single mode fiber when the number of times of reflection of light on the end surface of an optical element of an end optical system on the side of signal light of an optical tomography diagnosis device is less than three times, it is possible to obtain the end optical system on the side of the signal light of the optical tomography diagnosis device so that ghosts do not appear and the S/N ratio is advanced.
Further, according to the present invention, by matching the focal position in the peripheral direction of the cylindrical surface of a sheath with the focal position in the longitudinal direction of the sheath and by concentrating the focal point to a point in an observing beam outgone from the optical scanning probe, an optical scanning probe for advancing the S/N ratio is provided.
Further, according to present invention, by making the beam spot diameter of an observing beam almost uniform over a long distance in the direction of the major axis of the observing beam, the optical scanning probe that observing depth degree is large is provided.


An article carrier formed from a unitary blank and comprising a bottom wall (1), side wall means (2, 3, 32, 37) secured to the side edges of the bottom wall, a pair of end walls (20,53) secured respectively to the ends of the bottom wall, a top panel (30) secured to the upper edges of the side wall means and the end walls, a secondary bottom panel (6) secured to an end edge of the bottom wall and disposed in overlying relationship therewith, handle means (8, 11) secured to the secondary bottom panel and upstanding therefrom, and the top panel being removable with at least one V-shaped bend line (51,52) formed therein.

Various methods have been utilized in the past in order to render conventional nonreturnable article carriers suitable for use in connection with returnable articles such as are currently widely accepted by the consuming public. An example of this type of carrier in one form is disclosed in U.S. Pat. No. 3,356,258. A recurring problem with these carriers is that whenever the carrier is opened to gain access to the articles, it is severely weakened which hampers or renders impossible its use in connection with returnables.


To provide a vehicle air-conditioning apparatus which can ensure a dehumidifying ability even during an intermediate thermal load time where an outside air temperature becomes high during a dehumidifying heating operation time. In a vehicle air-conditioning apparatus, at least a compressor 6, a first heat exchanger 2, a first refrigerant control part 9 which is formed by connecting a first expansion device 7 and a first open/close valve 8 in parallel to each other, a vehicle exterior heat exchanger 4, a second refrigerant control part 13 which is formed by connecting a second expansion device 12 and a second open/close valve 11 in series, and a second heat exchanger 3 are connected in the preceding order in a loop.

Conventionally, as a vehicle air-conditioning apparatus having a dehumidifying heating function, there has been known a vehicle air-conditioning apparatus having the constitution disclosed in the following patent literature 1 (JP-A-6-341732).
As shown in FIG. 8, this vehicle air-conditioning apparatus includes a first heat exchanger 2 where a supply amount of air to the first heat exchanger is adjusted by a damper 5 and a second heat exchanger 3 which is arranged upstream of the first heat exchanger 2 in the inside of an air conditioning unit 1. A closed loop is formed by connecting a compressor 6, the first heat exchanger 2, a first expansion device 7, a vehicle exterior heat exchanger 4 arranged outside the air conditioning unit, an open/close valve V2, a second expansion device 41, the second heat exchanger 3 and an accumulator 10 by piping in this order. A passage which is opened or closed by an open/close valve V1 is provided between an inlet side and an outlet side of the first expansion device 7, a passage which is opened or closed by an open/close valve V3 is provided between an outlet side of the first heat exchanger 2 and an inlet side of the second expansion device 41, and a passage which is opened or closed by an open/close valve V4 is provided between an outlet side of the vehicle exterior heat exchanger 4 and a suction side of the compressor 6 (an inlet side of the accumulator 10). By controlling opening/closing of the respective open/close valves V1 to V4 and the degree of opening of the damper 5, an operation mode can be changed over among a cooling operation mode, a heating operation mode and a dehumidifying heating operation mode.
To be more specific, in the cooling operation mode, the open/close valve V1 is opened, the open/close valve V2 is opened, the open/close valve V3 is closed, and the open/close valve V4 is closed. The damper 5 is set at a full-cool position such that an air supply amount to the first heat exchanger 2 is set to 0, and all air which passes through the second heat exchanger is made to bypass the first heat exchanger 2. A refrigerant compressed by the compressor 6 is made to pass through the first heat exchanger 2 and, thereafter, heat of the refrigerant is radiated by the vehicle exterior heat exchanger 4, a pressure of the refrigerant is reduced by the second expansion device 41, and some heat is absorbed by the refrigerant at the second heat exchanger 3 and, thereafter, the refrigerant is made to return to the compressor 6 through the accumulator 10.
In the heating operation mode, the open/close valve V1 is closed, the open/close valve V2 is closed, the open/close valve V3 is closed, and the open/close valve V4 is opened. The damper 5 is set at a full-hot position such that all air which passes through the second heat exchanger 3 is made to pass through the first heat exchanger 2. Heat of the refrigerant compressed by the compressor 6 is radiated by the first heat exchanger 2 and, thereafter, a pressure of the refrigerant is reduced by the first expansion device 7 and some heat is absorbed by the refrigerant at the vehicle exterior heat exchanger 4 and, thereafter, the refrigerant is made to return to the compressor 6 through the accumulator 10.
In the dehumidifying heating operation mode, the open/close valve V1 is closed, the open/close valve V2 is closed, the open/close valve V3 is opened and the open/close valve V4 is opened. The damper is set at the full-hot position or at an intermediate position. As shown in FIG. 9, heat of the refrigerant compressed by the compressor 6 is radiated by the first heat exchanger 2 and, thereafter, a pressure of a part of the refrigerant is reduced by the second expansion device 41 and some heat is absorbed by the refrigerant at the second heat exchanger 3, while a pressure of a remaining part of the refrigerant is reduced by the first expansion device 7 and some heat is absorbed by the remaining refrigerant at the vehicle exterior heat exchanger 4 and, thereafter, the refrigerant is made to return to the compressor 6 through the accumulator 10.


The present invention provides an encoding apparatus, comprising means (21) for generating a checksum for incoming data, means (22) for constructing frames on the basis of said incoming data and said generated checksum, and means (23) for multidimensionally coding said frames. Further, the present invention comprises a decoding apparatus for iterative decoding of multidimensionally decoded information, comprising means (28) for performing at least one decoding iteration on multidimensionally coded information, and means (32) for checking the decoded information after each decoding iteration and for causing said decoding iteration means (28) to perform a further decoding iteration on the basis of a checking result. The present invention further comprises the corresponding encoding method and decoding method. The average processing delay and the computational complexity is significantly reduced, since only the required number of iteration steps is adaptively performed in the decoding apparatus.

The present invention relates to an encoding method and an encoding apparatus for multidimensionally coding information to be transmitted in a communication system. The present invention further relates to a decoding method and a decoding apparatus for iterative decoding of multidimensionally coded information. The encoding method, the encoding apparatus, the decoding method and the decoding apparatus of the present invention may be implemented in a communication unit of a communication system, e. g. a wireless telecommunication system.
During the transmission of information from a transmission unit to a receiving unit, e. g. from a base station to a mobile station of a wireless telecommunication system, errors may occur in disturbed transmission channels. These errors have to be detected and eventually corrected in the receiving unit. Channel coding is used to provide a possibility for the detection and correction of errors in the transmitted information. The channel code usually comprises additional error code symbols or error code bits, which are added to the information to be transmitted. These redundant error bits are transmitted with the information and are decoded on the receiving side, so that errors in the transmitted information can be detected and eventually corrected.
In order to provide a channel code, an encoding apparatus comprised in the transmission unit derives error code bits from the information bits by means of a corresponding coding method. On the receiving side, the error code bits enable to detect disturbed information bits. Depending on the size and the location of the error and the amount of error code bits it is eventually possible to correct the errors.
For such a channel coding, multiple encoding methods may be used. One of these encoding methods is the multidimensional coding. One of the multidimensional coding types are parallel concatenated systematic recursive codes, so-called turbo-codes, which are e. g. described in C. Berrou xe2x80x9cNear Shannon limit error-correcting and decoding:
Turbo-Codes (1)xe2x80x9d, Proc. ICC""93, May 1993.
Multidimensional codes are decoded on the receiving side by means of an iterative decoding processing. Thereby, a fixed number of iterations or iteration steps are performed to achieve a certain bit error rate or frame error rate. A fixed number of iterations or decoding loops, e. g. 8 or 16, is performed in the turbo decoding process to ensure a sufficient overall performance.
In FIG. 1, a known encoding structure of an encoding apparatus with a code rate of {fraction (1/3)} is shown. The input information is an encoded block of N bits, which are encoded in the encoding apparatus and output on three output lines. The known encoding apparatus shown in FIG. 1 generally consists of a first constituent encoder 1 and a second constituent encoder 2. The first constituent encoder 1 is provided with unchanged input information, whereas the second constituent encoder 2 is provided with input information processed in a turbo interleaving means 3.
The first constituent encoder 1 comprises a first delay means 4 and a second delay means 5. Both delay means 4 and 5 delay the respective input information by one bit. The unchanged input information supplied to the first constituent encoder 1 is input to the first delay means 4, delayed by one bit and then supplied to the second delay means 5 and there delayed by a further bit. The output signal from the second delay means 5 is fed back and added to the unchanged input information and the output signal of the first delay means 4 in an adding means 6. The output signal from the adding means 6 is supplied to the delay means 4 as well as to an adding means 7. In the adding means 7, the output signal from the adding means 6 is added to the output signal of the second delay means 5. The output signal of the adding means 7 is the second output (output 1) of the shown turbo encoding apparatus.
The input information of the encoding apparatus shown in FIG. 1 is further supplied to a turbo interleaving means 3, where the information bits are interleaved and then supplied to a second constituent encoder 2. The input information of the second constituent encoder 2 is supplied to a first delay means 8, delayed by one bit, supplied to a second delay means 9 and delayed by a second bit there. The output signal from the second delay means 9 is fed back to an adding means 10, in which the output signal from the first delay means 8, and the output signal from the turbo interleaving means 3 and the output signal from the second delay means 9 are added. The output signal from the adding means 10 is the input of the first delay means 8. The output signal of the second delay means 9 is further fed to an adding means 11, in which it is added to the output signal of the adding means 10 to provide the third output signal (output 2) of the shown encoding apparatus.
The first output signal (output 0) of the encoding apparatus shown in FIG. 1 is the unchanged input information.
The three output signals of the encoding apparatus shown in FIG. 1 are then further processed and transmitted in a transmission channel to a receiving apparatus, in which they are turbo decoded, e. g. by a turbo decoding apparatus 12 as shown in FIG. 2. The known turbo decoding apparatus 12 shown in FIG. 2 is supplied with three input signals corresponding to the three output signals of the known encoding apparatus shown in FIG. 1. The received information bits, which correspond to the first output signal of the encoding apparatus of FIG. 1 are the unchanged information bits, which are fed to a first constituent decoder 13 of the turbo decoding apparatus 12. The received parity bits of the first code are soft parity information, which are also supplied to the first constituent decoder 13, correspond to the second output (output 1) of the encoding apparatus of FIG. 1. The received parity bits of the second code are soft parity information, which are fed to the second constituent decoder 14 of the turbo decoding apparatus 12 correspond to the third output (output 2) of the encoding apparatus shown in FIG. 1. The second output (output 1) and the third output (output 2) of the encoding apparatus of FIG. 1 are therefore error code bits (parity bits), which are transmitted together with the unchanged information bits to provide an error code, which is used on the receiving side to detect and eventually correct errors in the transmitted information signal (output 0).
The received parity bits of the first code and the received information bits are supplied to the first constituent decoder 13 of the turbo decoding apparatus 12 and processed to provide decoded soft decision values, which are supplied to and processed in a deinterleaver 15. The deinterleaved soft decision values from the deinterleaver 15 are supplied to the second constituent decoder 14 of the turbo decoder apparatus 12. The received information bits are further supplied to an interleaver 16. The interleaved information bits from the interleaver 16 are also supplied to the second constituent decoder 14. The received parity bits of the second code are supplied to the second constituent decoder 14. In the second constituent decoder 14, the three input signals are decoding processed. The output signal from the second constituental decoder 14 comprises soft decision values, which are fed back to an deinterleaver 18. The deinterleaved soft decision values from the deinterleaver 18 are fed back and supplied to the first constituent decoder 13.
In the known turbo decoding apparatus 12 shown in FIG. 2, the number of iterations through the deinterleaver 18 is a fixed number of iterations, e. g. 8 or 16 to provide a sufficient overall performance in terms of the bit error rate or frame error rate. Thereby, in each iteration step, the second constituent decoder improves the soft decision likelihood values of the first constituent decoder 13 and the deinterleaver 15. In each iteration step, the soft decision likelihood values are therefore changed and improved to improve the performance in term of the bit error rate and the frame error rate. After a predetermined fixed number of iteration steps, the soft decision likelihood values output from the second constituent decoder 14 are supplied to a deinterleaver 17. The deinterleaved soft decision likelihood values from the deinterleaver 17 are supplied to a hard decision means 19, in which the soft decision likelihood values are transformed into hard decision values, e. g. bits of the values xe2x80x9c0xe2x80x9d or xe2x80x9c1xe2x80x9d to provide an output signal. Since always the same high number of iteration steps is performed, the computational load and thus the power consumption and also the processing delay, since each iteration loop needs a certain processing time, are very high.
One proposal to determine an adaptive stop criteria in iterative decoding of multidimensionally decoded information is described in EP 0 755 122 A2. In this proposed structure, a comparison of the soft decision values output from the second constituent decoder after each iteration step with the soft decision values of the immediately preceding iteration step is performed. If the soft decision values between two immediately succeeding iteration steps do not change, the decoding iteration is stopped. However, if the transmitted information bits are erroneous, this proposed method does not provide a possibility to detect and correct errors. Further, always one iteration step more than needed is performed, since the proposed stop criteria requires that two succeeding iteration steps result in the same soft decision likelihood values.
The object of the present invention is therefore to provide an encoding apparatus, an encoding method, a decoding apparatus and a decoding method, which enable an optimized and effective iterative decoding of multidimensionally coded information.
This object is achieved by a decoding apparatus according to claim 1, a decoding method according to claim 8, an encoding apparatus according to claim 9 and an encoding method according to claim 11.
The decoding apparatus for iterative decoding of multidimensionally encoded information according to the present invention comprises means for performing at least one decoding iteration on multidimensionally coded information, and means for checking the decoded information after each decoding iteration and for causing said decoding iteration means to perform a further decoding iteration on the basis of a checking result. The decoding method for iterative decoding of multidimensionally coded information according to the present invention comprises the steps of performing at least one decoding iteration on multidimensionally coded information, and checking the decoded information after each decoding iteration step and for causing a further decoding iteration to be performed on the basis of a checking result.
The encoding apparatus according to the present invention comprises means for generating a checksum for incoming data, means for constructing frames on the basis of said incoming data and said generated checksum, and means for multidimensionally coding said frames.
The encoding method according to the present invention comprises the steps of generating a checksum for incoming data, constructing frames on the basis of said incoming data and said generated checksum, and multidimensionally coding said frames.
The present invention therefore provides an encoding apparatus and method and a decoding apparatus and means, which enable an optimized and effective iterative decoding of multidimensionally coded information. Particularly, no more decoding iteration steps are performed if the information has been decoded correctly. Thereby, the mean number of iteration steps is reduced without sacrificing the performance of the turbo decoding. The reduction of the iteration steps ensures less computational complexity and less processing delay, whereby at the same time the decoding performance is maintained. Since the maximum numbers of iteration steps in the decoding processing can still be fixed, the overall performance in terms of the bit error rate and the frame error rate is the same as in the state of the art, however, the mean number of iteration steps is reduced dramatically. This is particularly due to the fact that many transmitted data frames can be decoded and corrected completely with a much less number of iteration steps compared to the maximum possible number of iteration steps.
Advantageously, the checking means of the decoding apparatus according to the present invention comprises an error detection means for detecting an error in said decoded information. In this case, the multidimensionally coded information may comprise a cyclic redundancy checksum, whereby said error detection means performs a cyclic redundancy check on said decoded information. Thereby, a small cyclic redundancy checksum might be appended to each information frame.
Alternatively, the checking means of the decoding apparatus according to the present invention may comprise an error detection and correction means for performing an error detection and correction on said decoded information. This construction is very effective in correcting bit errors in the transmitted information even if the decoding iteration means was not able to correct all errors even after the maximum number of decoding iteration steps.
Further advantageously, the checking means provide a control signal for causing said decoding iteration means to perform another iteration if the checking result is negative. Thus, the decoding iteration means only performs one iteration at a time and is controlled or triggered by a control signal from the checking means to continue the decoding processing in case that the checking result indicates, that the decoded information are not yet correct.
The means for performing at least one decoding iteration on multidimensionally coded information in the decoding apparatus of the present invention is preferably a decoding means known in the state of the art, so that the decoding apparatus according to the present invention can be built in a simple and effective way using a known decoding iteration means.
Further advantageously, the decoding apparatus according to the present invention comprises a counting means for counting the number of decoding iteration steps performed by said decoding iteration means and for causing decoded information to be output if a predetermined maximum number of iteration steps is reached even if said checking result is negative. In other words, the maximum number of decoding iteration steps is limited to a predetermined maximum number. The checking result of the decoded information, which usually are soft decision likelihood values, can still be used in a further stage of the processing, since a reliability value of the decoded information is provided by the checking result, even if the checking result is negative. On the basis of this reliability information, one of the next stages of the processing of the information can decide how to deal with the corresponding information data frame still containing errors.
Further advantageously, the decoding apparatus according to the present invention comprises means for extracting data from said decoded information if said checking result is positive and for outputting said extracted data. If, e. g. the decoded information contain a checksum appended to the transmission data, the checksum data are removed and the information data of interest are extracted to be further processed.
In the encoding apparatus of the present invention, the checksum generating means advantageously generates a checksum for a cyclic redundancy check. New data frames are then constructed using the original incoming data bits and the generated cyclic redundancy check bits. Although this creates some overhead, this overhead is very small and is used on the receiving side to significantly reduce the power consumption and the computational complexity.

Encoding apparatus and encoding method for multidimensionally coding and encoding method and decoding apparatus for iterative decoding of multidimensionally coded information


An electrical penetration graph (EPG) system includes a monitoring device with a buffered and stabilized voltage source assembly and a buffered internal amplifier with switched gain control. The system also includes a head stage amplifier. During the EPG process, the voltage source assembly directs an electrical current through a feeding insect. As the current passes through the insect, the insect's feeding process modulates the current and creates voltage waveform data. A head stage amplifier with selectable input resistance receives and amplifies the voltage waveform data. The data is transmitted back to the monitoring device where it is manipulated and further amplified by the monitoring device internal amplifier assembly. The waveform data is then transmitted to a controller and ultimately to an output device where the data is displayed.

The current invention was designed to record the feeding processes of aphids and other soft-bodied, piercing-sucking agricultural pests. These insects spread numerous, deleterious plant viruses that cause many millions of dollars in damage to crops worldwide every year.
Aphids and other piercing-sucking insects acquire plant pathogens from infected plants and inoculate them to healthy plants. After aphids acquire the pathogens, it remains in the insect's body throughout its life. Researchers (including the inventors) are attempting to combat these plant diseases by better understanding how aphids and other vectors of plant pathogens carry and spread the pathogen via their feeding processes.
One means of studying the transmission of the disease is through an understanding of the way the insects feed. Direct current electrical penetration graph (EPG) technology provides information regarding the way that the insect draws its fluid food from plants. The EPG process is initiated by attaching a gold wire to the body of a sharpshooter and placing the sharpshooter in a feeding position on the leaf of a host plant. A plant electrode is then placed in the soil adjacent to the plant or attached directly to a part of the plant. A lead wire from the plant electrode and the gold wire attached to the insect are then connected to a monitoring device.
When the stylets (the probing and penetrating mouth parts of the insect) connect with the host plant, an electrical circuit is completed. As the insect's stylets probe the host plant, the voltage in the circuit fluctuates. The voltage fluctuations are depicted as waveform data on a computer monitor or on a time-based chart in a similar manner to an electrocardiogram (EKG) chart. Researchers have been able to correlate the waveform data (i.e. voltage fluctuations) with certain feeding activities to better understand the biological mechanisms that facilitate the spread of the Xylella fastidiosa bacteria.
Although the hardware associated with the direct current EPG monitoring process has been around since the 1970s, no meaningful update of the monitoring system design has apparently been attempted since its inception. The currently available monitor has been marketed under the name "Giga 8" or "Giga8", although a cursory search of the US Patent and Trademark Office, Trademark Electronic Search System indicates that neither name is trademarked in the US.
The Giga 8 is a direct current EPG monitor that was originally designed primarily for aphids and other small piercing-sucking insects. Aphids are very tolerant of direct current excitation signals and consequently direct current EPG monitors continue to be used to study aphids. However, even for these direct current tolerant insects, the Giga 8 is no longer sufficiently suited for scientific inquiry. The direct current EPG system of the current invention eliminates several problems with the Giga 8, and also expands its usefulness for other, direct current-tolerant insects, especially larger insects such as large leafhoppers and heteropterans.
Among other things, the excitation voltage source of the Giga 8 is unregulated and uncompensated. The excitation control potentiometer has a negative DC voltage applied to one end of a fixed resistance element and a positive voltage applied to the other. Further, the excitation voltage cannot be precisely and reproducibly set. No means is available to determine the actual excitation voltage selected because the instrument is not capable of calibration. The excitation voltage is fed directly out from the control potentiometer wiper, without compensation to stabilize the voltage at any set level and the instrument has no index or dial settings available for reference and adjustment.
Although the Giga8 has a head stage amplifier (i.e. "head amp"), the head amp is limited to a single, fixed input resistance setting. This severely limits the sensitivity of the Giga 8, making it only useful for aphids and closely related insects. The main internal amplifier of the Giga 8 has a very low gain. This is not problematic for the small range of insect species that it was designed to monitor, but the Giga 8 design limits the instrument's ability to study other species of arthropod.
Further, as with other aspects of the Giga 8, the gain control has no scale. An operator simply arbitrarily adjusts the gain control until he/she is satisfied with the result. Consequently there is no means of documenting the exact instrument settings associated with the produced waveform data, therefore the results obtained from an evaluation using the Giga 8 are not precisely reproducible and verifiable by other researchers.
As indicated above, most of the electronic components of the Giga 8 are obsolete. For example, the Giga 8 operational amplifier is a μA741, which was designed in the 1970's. It has a very limited ability to change the output voltage to follow the input signal (i.e. slew rate). At even a moderate gain, the output may not closely resemble the shape of the input waveform, especially when the amplitude changes rapidly. Thus, output signals may be inaccurate and artifactual.
Because of the limitations described supra, the Giga 8 is only marginally useful. The need exists for a new EPG monitor that includes updated components as well as a wider range of applicability.
The current invention provides an EPG monitoring system that includes the ability to produce more detailed, accurate, and higher-resolution waveforms than the prior art system. The EPG monitoring system of the current invention also provides switchable amplifier sensitivities and expands the utility of the direct current EPG process to essentially all direct current-tolerant piercing-sucking arthropods.

The United States of America, as Represented by the Secretary of Agriculture


An impulse response matrix of a received signal in a TDMA communications system is approximated using a plurality of indirect variables of a linear complex vector. The indirect variables are used for synchronizing to the received signal and for tracking and frequency offset estimation during successive samples of the received signal, the samples being equalized in dependence upon the indirect variables. A demodulated signal is derived from the equalized received signal samples. Individual synchronization and tracking units, and a single equalizer, can be provided for a two-antenna receiver. Tracking errors can be used to adapt a parameter of the equalizer to reduce interference in the received signal.

It is well known that it is necessary in a receiver of a cellular mobile radio system to recover each communicated signal under varying and challenging conditions. These conditions include, for example, the presence of multi-path signals and fading resulting in low signal-to-noise ratio (SNR), the presence of strong co-channel interfering (CCI) signals, and Doppler effects due to relative movement of the signal transmitter and receiver, as well as typical constraints due to factors such as limited channel bandwidth and equipment tolerances. In the case of a TDMA system, it is necessary to recover the timing and synchronize to the time division multiplex (TDM) frames and time slots of a received digital communications signal. It is also desirable to provide the receiver with the least possible cost and computational complexity.
International Publication Number WO 97/08867 dated division multiple access) systems. Mar. 6, 1997, in the name of Northern Telecom Limited and entitled "Timing Recovery And Frame Synchronization In A Cellular Communications System", discloses a method of timing recovery in which indirect variables of a linear complex vector are estimated using a maximum likelihood criterion in order to recover sampling delay and hence the timing and frame synchronization of the received signal.
There remains a need to provide improved receivers for cellular communications systems.

Cellular communications system receivers


A freight container in the form of a tractor-trailer or intermodal container which is convertible for selectively carrying solid freight or bulk liquid freight including a housing, a plurality of collapsible tanks in the housing, liquid outlets in the tanks and conduits in communication with the liquid outlets located entirely within the housing and an opening in the housing proximate the outlets of the conduits. A liquid washing assembly is permanently mounted on the tanks both in the expanded and collapsed conditions of the tanks. Guide structure is provided in association with the frame of the collapsible tanks for guiding the frame in a perfectly vertical direction both when the tanks are being expanded and being collapsed. The upper and lower edges of the tank sides are bolted and clamped to their associated frames. Hot air ducts encircle the liquid conduits in the bases of the tanks.

The present invention relates to an improved collapsible tank structure for a freight container which is convertible to selectively carry solid freight or bulk liquid freight.
By way of background, there are certain congealable liquids, such as printer's ink or chocolate, which are transported in freight containers. These liquids must be maintained at an elevated temperature to prevent congealing thereof. If the liquids are permitted to congeal, they will clog the liquid conduits. However, if the liquids are heated sufficiently to maintain their liquidity, congealing does not occur, and, further, the filling and emptying of the tanks is done more efficiently.
Also by way of background, there are variations in the placement of the liquid conduit associated with the opening in the bottom of a collapsible tank. These variations may be due to the requirement for different placements of the parts in different installations. However, it is necessary to insure that there is proper sealing of the tank liner and the gasket proximate the tank outlet. This requires that the bolts associated with the securing of the tank liner and the gasket be properly oriented regardless of the above-mentioned variations.

Collapsible tank for convertible freight container


This invention is therapeutically useful tetralins and pharmaceutically acceptable acid addition salts thereof of the formula ##STR1## wherein X.sub.1 is halogen, CF.sub.3, --OR.sub.3, or --SR.sub.4 ; wherein R.sub.3 is alkyl(C.sub.1 -C.sub.8); alkenyl(C.sub.1 -C.sub.8); --CH.sub.2 -cycloalkyl(C.sub.3 -C.sub.8) or benzyl; wherein R.sub.4 is alkyl(C.sub.1 -C.sub.3); wherein X.sub.2 is hydrogen, CF.sub.3 or halogen; wherein R.sub.7 is hydrogen or methyl; wherein R.sub.1 is hydrogen, alkyl(C.sub.1 -C.sub.3), or cyclopropylmethyl; wherein R.sub.2 is --CH.sub.2 -cycloalkyl(C.sub.3 -C.sub.8), alkyl(C.sub.1 -C.sub.8), --(CH.sub.2).sub.q --R.sub.5 or --CH.sub.2 CH.sub.2 --Z--(CH.sub.2).sub.r CH.sub.3 ; wherein R.sub.5 is phenyl, 2-thiophene or 3-thiophene; wherein Z is oxygen or sulfur; and wherein p is one or 2, q is 2 or 3, and r is zero to 3; with the provisos that (1) when X.sub.1 is --OR.sub.3, X.sub.2 is halogen or CF.sub.3 ; and (2) when X.sub.1 is halogen, X.sub.2 is hydrogen, and p is 2, X.sub.1 is in a position other than the 8-position. These compounds are useful to treat central nervous system disorders.

Evidence from depressed patients indicates the neurotransmission in the central nervous system (CNS) may be disturbed. These disturbances involve the neurotransmitters noradrenaline (NA) and 5-hydroxytryptamine (5-HT). The drugs most frequently used in the treatment of depression are considered to act by improving the neurotransmission of either or both of these physiological agents. The mechanism of action for conventional drugs used to treat mental depression is generally believed to be indirect. It is thought the drugs block the reuptake of the neurotransmitters released from nerve terminals in the CNS, NA and/or 5-HT, which increases the concentration of these transmitters in the synaptic cleft and restores an adequate neurotransmission. For example, the clinically documented antidepression drug, zimelidine (dimethyl-amino-1-(4-bromophenyl)-1-(3-pyridyl)propene) acts as such a reuptake inhibitor with high selectivity for 5-HT neurons.
Available data suggests enhancement of 5-HT neurotransmission will primarily improve depressed mood and anxiety, whereas enhancement of noradrenaline neurotransmission will improve the retardation symptoms occurring in depressed patients. In recent years many efforts have been made to develop new drugs with high selectivity for the improvement of the 5-HT neurotransmission in the CNS.
A fundamentally different way to improve the neurotransmission in the central 5-HT neurons would be to use a 5-HT receptor agonist acting directly upon the 5-HT receptors, and particularly the 5-HT.sub.1A receptor. In order to minimize undesired side effects, a high selectivity for this kind of receptor would be necessary.
Clinically, 5-HT.sub.1A agonists have also demonstrated anxiolytic properties. The drug, Buspirone, is the only currently available marketed 5-HT.sub.1A agonist having anxiolytic activity. This compound antagonizes dopamine receptors at the same dose it stimulates 5-HT.sub.1A receptors. These dopamine antagonist properties reduce the clinical utility of these compounds however because long term treatment with dopamine antagonists can produce tardive dyskinesias.
The search for new CNS active compounds is focused on finding compounds with selective 5-HT.sub.1A receptor agonist effects without detrimentally influencing central dopamine receptors.
In recent years a large body of pharmacological, biochemical and electrophysical evidence has provided considerable support in favor of the existence of a specific population of central autoregulatory dopamine receptors located in the dopaminergic neuron itself and belonging to the D.sub.2 receptor subclass of dopamine receptors. These receptors are part of a homeostatic mechanism that modulates nerve impulse flow and transmitter synthesis and regulates the amount of dopamine released from the nerve endings.
Drugs acting on central dopamine transmission are clinically effective in treating a variety of central nervous system disorders such as parkinsonism and schizophrenia. In parkinsonism, for example, the nigro-neostriatal hypofunction can be restored by an increase in postsynaptic dopamine receptor stimulation. In schizophrenia, the condition can be normalized by achieving a decrease in postsynaptic dopamine receptor stimulation. Classical antipsychotic agents directly block the postsynaptic dopamine receptor. The same effect can be achieved by inhibition of intraneuronal presynaptic events essential for the maintenance of adequate neurotransmission, transport mechanism and transmitter synthesis.
Direct dopamine receptor agonists, like apomorphine, are able to activate the dopamine autoreceptors as well as the postsynaptic dopamine receptors. The effects of autoreceptor stimulation appear to predominate when apomorphine is administered at low doses, whereas at higher doses the attenuation of dopamine transmission is outweighed by the enhancement of postsynaptic receptor stimulation. The antipsychotic and antidyskinetic effects in man of low doses of apomorphine are likely due to the autoreceptor-stimulator properties of this dopamine receptor agonist. This body of knowledge indicates dopamine receptor stimulants with a high selectivity for central nervous dopamine autoreceptors would be valuable in treating psychiatric disorders.


Methods and systems for providing accurate, scalable, and predictive 3D printing simulations using numerical methods for part-level simulations. Complex parts can be discretized into finite elements using independent and arbitrary meshing. The real additive manufacturing tooling path and printing time of a printing machine are simulated and applied to the mesh of finite elements using an intersection module that combines the finite element mesh with the tool path information of the printing machine in a geometric sense. This allows for localized heating effects to be simulated very accurately, and for cooling assessments to be precisely computed given the intersection module's computation of partial facets and volumes of the finite elements at any given time in the printing simulation.

The impetus of 3D printing technology in recent years is significant. Many printer manufacturers exist and new companies seem to appear overnight. Despite this wave of new developments, in many (if not most) cases, the reliability of the technology is limited, and printed, or additive manufactured ("AM"), parts suffer from defects that lead to subpar strength and fatigue life when compared to parts manufactured with conventional technologies. This negative aspect limits severely the spread of the technology. Computer simulations are sought to provide insight into the process so that progress in raising the quality of AM parts can be achieved.
Many physics-related aspects of the additive manufacturing process are similar to some of the conventional manufacturing technologies, such as casting and welding. Material is added in a hot and fluid state and then it cools down. In additive manufacturing, the material is added incrementally in a molten state or is brought to a molten state by a moving heat source (e.g., laser) after which cooling occurs on a continuously evolving surface. The additional challenges with AM, particularly with metal fabrication, have to do with the vast disparity in time and length scales that one has to deal with during manufacturing: very localized and rapidly evolving physics in the "action" zone while the manufacturing process for the whole part takes hours or perhaps days.
The efforts to develop numerical techniques to simulate certain aspects of an additive manufacturing process are numerous and span several communities of scientists and engineers from academics to applied research commercial entities. The difficulties to capture/predict via computer simulations such processes are many, including: (1) vastly different time scales of the melting/solidification physics (milliseconds) and the overall manufacturing time of a typical part (hours of printing on the machine); (2) wide range of scale lengths, from microns associated with melt pools to hundreds of millimeters necessary to model a typical part; (3) rapidly evolving high temperature gradients around the "action" zone, which leads to highly anisotropic material final properties (before eventual heat treatment); (4) assuming that adequate models are employed, very large simulation times are typically necessary to model such processes in order to capture all of the above.
Developing novel numerical schemes would be necessary to cope with all these challenges. The following are examples of existing technologies, each of which do not solve the difficulties described above:
3DSIM is a company that claims it develops efficient numerical simulation technology based on finite elements. 3DSIM's method appears to take advantage of adaptive mesh refinement/coarsening techniques while leveraging advanced metal modeling constitutive behavior. See www.3dsim.com and I. Gibson, D. Rosen, B. Stucker, Additive manufacturing technologies: rapid prototyping to direct digital manufacturing, Springer, N.Y., 2009. The technology is intended for laser melting/sintering AM applications and employs an automated mesh refinement technique in the "action" zone (e.g., current laser location). However, it does not leverage actual laser path information and recoater/spreader bar throughout the part. Consequently, the overall cooling by convection and radiation for the whole part loses accuracy/predictiveness as a result. Moreover, the automated refinement/coarsening of the mesh has negative implications on the overall computational performance when analyses are run in parallel on multiple CPUs (especially on a large number of CPUs).
PANCOMPUTING is another example of a company that leverages finite element-based solutions. PANCOMPUTING's method also incorporates adaptive mesh refinement techniques and is able to make predictions of undesired distortions during the printing process. See www.pancomputing.com and P. Michaleris, "Modeling metal deposition in heat transfer analyses of additive manufacturing processes In situ monitoring." Finite Elements in Analysis and Design (2014): 51-60. The technology is similar to 3DSIM and faces similar limitations.
The United State National Labs have also been investing on the topic with Los Alamos and Lawrence Livermore leading the effort. At Los Alamos, long time existing casting simulation software is currently being adapted/re-purposed to study numerically AM processes (see Truchas casting software available at www.lanl.gov). At Lawrence Livermore, comprehensive simulation technology is being developed to address at a micro-scale the complex physics of phase transitions from powder, to liquid, to solid and attempting to predict residual stresses for very small parts. See N. E. Hodge, R. M. Ferencz, J. M. Solberg, "Implementation of a thermomechanical model for the simulation of selective laser melting" Comput Mech (2014) 54:33-51). The US National labs do not seem to focus on accurate predictions for part-level simulations. Instead, they seem to be spending much effort in understanding the basic behavior on very small-scale models without paying enough attention on overall behavior as far as realistic parts are concerned.
Academics researching the topic are too numerous to list here in a comprehensive fashion. Many leverage old existing models developed originally for welding or casting, such as described in J. B. Leblond, "Mathematical Modeling of Transformation Plasticity in Steels," International Journal of plasticity, Vol 5, 573-591, 1989. More recent works (such as in Xipeng Tan, Yihong Kok, etc. "An experimental and simulation study on build thickness dependent microstructure for electron beam melted Tie6Ale4V, Journal of Alloys and Compounds 646 (2015) 303-309) focus on more or less sophisticated material constitutive behavior models that are quite valuable and practical. Academics of all sorts, similar to the National Labs, also do not have a focus on part-level simulations for scalable predictive solutions. When part-level presentations are included, the geometry associated with the shape is severely simplified to accommodate for the lack of technology in dealing with realistic parts.
Numerical modeling of heat treatment related applications has a significant relevance in modeling, in the case of metals, of metallurgical transformation throughout the part being modeled. See www.dante-solutions.com and B. Lynn Ferguson and Zhichao Li, "Using Simulation for Heat Treat Process Design: Matching the Quenching Process", ICTPMCS-2010, 31 May-2 Jun. 2010, Shanghai, China. Heat treatment software packages, while very relevant for AM process simulation from a variety of perspectives, suffer from a severe limitation: they lack the ability of simulating local thermal aspects (such as laser heating) and managing evolving surfaces of an additive manufacturing process
Thus, despite the numerous prior efforts for developing the various numerical modeling technologies, there is still a number of rather significant limitations associated with these developments.

Scalable finite element simulation of additive manufacturing


Edge faces with level differences are formed by assembling blocks constructing a coating head, and level difference variances in the width direction of a web are measured by a level difference variance measurement device. Then, the level difference variances are adjusted with reference to measured results, so that the level difference variances can be reduced. Therefore, coating layers can be uniformly formed on the web.

1. Field of the Invention
The present invention relates to an extrusion-type coating method and coating apparatus, particularly to an extrusion-type coating method and coating apparatus for coating a web with coating liquids to form thin and uniform magnetic recording layers in order to produce a magnetic storage medium with a high capacity and a high density.
2. Description of the Related Art
In order to produce a magnetic storage medium with a high capacity and a high density, a thin and uniform magnetic recording layer needs to be formed on a web. In an extrusion-type coating apparatus, the continuously-running web is relatively pressed against edge faces of a coating head, and one or more coating liquids supplied into the coating head are supplied to discharge mouths of the coating head through supply routes and discharged from the discharge mouths of the coating head formed in the width direction of the web, so as to coat the web with the coating liquids. Moreover, an extrusion-type coating method is performed by which plural coating layers having a first layer (bottom layer) as a non-magnetic layer and a second layer (top layer) as a magnetic layer are simultaneously formed, and an extremely thin magnetic recording layer is thus obtained.
In such extrusion-type coating method, a coating defect may occur such as an unevenness of a thickness of the magnetic recording layer in the width direction of the web if the web is coated unevenly in the width direction of the web. The higher the density of the magnetic recording layer is, the higher the required precision of the uniformity is.
In a conventional art, improvements in a form of the edge face, a tension condition of the web, and further a positional relationship of each of the edge faces with respect to the web surface, are attempted in or to attain the uniformity of the magnetic recording layer. Some of such prior arts are Japanese Patent Application Laid-open Nos. 60-238179, 62-132566, and 4-145977, in which discussions are described on properly setting a thickness of a back blade, on properly setting an entering angle of the web into the coating head and on adjusting a space between a trailing end of the edge face and the web. Further, Japanese Patent Application Laid-open No. 6-296917 teaches that a coating head which can be divided into plural blocks for each of the edge faces and a level difference is formed on each of the edge faces by sliding each block, whereby the positional relationship between the edge faces with respect to the web surface is appropriately set. Still further, Japanese Patent Application Laid-open No. 11-314065 teaches that a length of the perpendicular is adjusted in the width direction of a web, in which a leading end on an edge face of a block at the trailing end becomes A, and a trailing end on the edge face of the block at the leading end becomes B, the perpendicular being connected with a tangent line, that is written on the edge face of the block at the trailing end from the trailing end B on the edge face of the block at the leading end by passing a supply route.
When assembling a coating head in a method for setting level differences of the edge faces by using the coating head which can be divided into plural blocks for each of the edge faces mentioned above, each block is processed beforehand in a size with a height suitable for a level difference so that the level difference has a desired height, then the blocks are assembled and fastened while being placed on a reference plane. In another method, the heights as well as sizes of the blocks are measured beforehand when assembling the coating head, and the heights of the blocks are adjusted by laying a spacer at the bottom of each block and the blocks are fastened in that state. In short, the level differences of the edge faces are set by referring to manufacturing precision and flatness as a reference of the blocks.
However, when setting the level difference by the above-described method, a magnetic recording layer which is satisfactory uniform cannot be obtained if the manufacturing precision of the blocks is low, because the precision of the levels is determined by results of the manufacturing precision of the blocks. In a case where the width of the web is wide such as 1 meter or more, a technology for manufacturing the blocks with precision of a few micrometers is extremely cost-consuming as well as difficult.
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of an extrusion-type coating method and apparatus in which level difference of edge faces can be precisely set to form a uniform layer, and unnecessarily-high manufacturing precision of the blocks is not needed to avoid an increase of costs for block manufacturing.
In order to achieve the above-described objects, the present invention provides an extrusion-type coating method wherein a continuously-running web is relatively pressed against edge faces of a coating head, a coating liquid supplied into the coating head is supplied to a discharge mouth formed on the edge faces in a direction of a width of the web through a supply route and is discharged from the discharge mouth so as to apply the coating liquid on the web, and the coating head is divided into two blocks along the supply route so that a level difference between the edge faces can be set, the extrusion-type coating method comprising the steps of: preliminarily setting the level difference by assembling the blocks on a base with a reference plane so that the level difference between the edge faces is a desired level difference; then measuring a variance of the level difference preliminarily set in the width direction of the web; then finally setting the level difference according to results of the measurement; and then applying the coating liquid on the web by using the coating head into which the set blocks are assembled.
Further, in order to achieve the above-described objects, the present invention provides an extrusion-type coating apparatus wherein a continuously-running web is relatively pressed against edge faces of a coating head, a coating liquid supplied into the coating head is supplied to a discharge mouth formed on the edge faces in a direction of a width of the web through a supply route and is discharged from the discharge mouth so as to apply the coating liquid on the web, and the coating head is divided into two blocks along the supply route so that a level difference between the edge faces can be set, the extrusion-type coating apparatus comprising: a level difference variance measurement device which measures a variance of the level difference in the width direction of the web; and a level difference correction device which corrects the level difference according to results of the measurement by the level difference variance measurement device so that the variance of the level difference is reduced.
Accordingly, the extrusion-type coating method and apparatus of the present invention first forms the edge faces with the level difference by assembling the blocks constructing the coating head, and measures the variance of the level difference in the width direction of the web by the level difference variance measurement device, then adjusts the level difference to eliminate the variance with reference to the measured results. Thus, a uniform coating layer can be formed on the web. Furthermore, the coating layer can be still thinner because the coating layer can be uniform.

Extrusion-type coating method and apparatus


A facing element (10) includes a honeycomb carrier plate (12) which is clamped, sandwich-like, between two cover plates (14, 16) by clamping anchors (18). On the upper cover plate (14) is affixed by adhesion, a natural stone plate (22). The honeycomb carrier plate (12) projects at two diagonal edges by projections (21, 23) beyond the cover plate (14). At both other edges of the carrier plate (12), pocket-like depressions (25, 27) are formed which, in form and position, are complementary to the projections (21, 23) at the diagonal plate edges. In the plate connection the projections of a facing element engage the pocket-like depressions (25, 27) of two adjacent facing elements so as to form a form-fit connection whereby a strong plate connection is created.

The present invention relates in general to facing elements, and in particular to a new and useful facing element for floors, ceilings, walls and the like.
European Patent Document EP 406 991 A1 discloses a facing element of this type. A honeycomb carrier plate comprises regular hexagonal honeycombs. The edges of the carrier plate and a cover plate are flush, which also applies for a stone plate. Consequently, the four plates of the facing element are on all four sides in contact with the same imaginary lateral contact plane. In the case of a floor plate covering, this known facing element requires an adhesive type floor fastening since otherwise due to the absence of a form-fit interdigitation of the facing plates, no surface alignment can be achieved. For wall facings, these facing plates have anchoring means on the rear side with which they can be suspended from a wall fastening rail. Between the individual facing elements of a wall covering of this type remain gaps through which rain water can penetrate into the hollow space between the facing plane and the building wall. Due to the individual suspension of the facing plates, relative motions of the facing elements can occur in the event of wind incident and, depending on the type of suspension, the development of noise through the possibility of relative motion of the plates is also not excluded. In the known facing element the carrier plate and the two cover plates comprise aluminum, and the stone plate is fastened in spots by adhesive means to the upper cover plate and additionally mechanically anchored on the carrier plate.
U.S. Pat. No. 4,601,147 discloses a facing element in which a carrier plate comprises a continuous bottom with a number of webs projecting upwardly from it, on which the stone plate is fastened. The width of the carrier plate and the stone plate is identical, however, the carrier plate comprises at one end of its length a push-in tongue to which is assigned at the other end a lead-in groove for the push-in tongue of an adjacent plate. The carrier plates consequently engage each other in a form-fit manner in their longitudinal directions, however, in the transverse direction longitudinal joints result between the rows of facing elements with the disadvantages described above. In large-format facing elements the carrier plate implementation with the majority of parallel bearing webs has a disadvantage in comparison to a honeycomb bearing element because the stone plate between two bearing webs is not supported over the entire web length.

Facing element for floors, ceilings, walls and the like


A multi-layer Printed Circuit Board PCB and a wireless communication node are disclosed in the present invention. The multi-layer PCB which is to be assembled in the communication node may include multiple radio layers (501) on one side of the PCB and at least one antenna layer (502) on another side of the PCB. At least one radio component is to be mounted on a surface layer of the multiple radio layers and at least one antenna element is to be patched on a surface layer of the at least one antenna layer. In such way, legacy connectors from the filter unit respectively to the antenna unit and the radio unit in conventional PCB can be left out to decrease the size of the PCB.

This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to the prior art by inclusion in this section.
In telecommunication system, an access node or access point facilitates wireless communication between a terminal device, such as user equipment (UE), with a core network. An access node is also referred to as radio base station (RBS), node B (in 3G Networks), base transceiver station (BTS), evolved Node B (eNB) or, base station (BS). It mainly consists of three basic portions, a baseband unit, a radio unit and an antenna unit. The baseband unit is used for baseband signal processing such as modulation/demodulation, encoding/decoding, pre-coding, channel estimation and equalization, etc. The radio unit is used for frequency conversion to high band (Downlink) or to lower band (Uplink), output power amplification is also implemented in radio unit. Antenna unit comprising antenna elements is to transmit and receive radio frequency (RF) signal through air interface.
In a traditional macro configuration, baseband unit is physically bound to radio unit. In real deployment, both of the baseband unit and the radio unit are put together in a cabinet (102) as shown in FIG. 1 on the ground, while antenna unit (101) is always horizontally higher than the radio unit, usually located at the top of buildings in the city or on the mountains in countryside, to ensure the transmission and reception of electromagnetic waves. Long jumper cable is used to connect the radio unit and the antenna unit (101) in FIG. 1.
Along with development of technology, main-remote concept was raised during the evolution of access node. Radio unit (202) is not necessarily close to baseband unit (203) but installed considerably close to antenna unit (201), shown in FIG. 2. However, connection between antenna unit (201) and radio unit (202) still relies on jumper cable.
In recent years, antenna integrated radio unit (AIR) was designed to put radio unit and antenna unit into one physical "box" (301) as shown in FIG. 3. Long cable is needed between the physical box (301) and baseband unit (302). When a concept of Multiple In and Multiple Out (MIMO) became popular, number of antenna element has been increased from one or two to eight or even 16. On the other hand, antenna technology development turned it into reality that antenna element can be made into planar antenna element and be patched onto an antenna layer.
FIG. 4 illustrates how a radio unit and an antenna unit are connected in a same physical block of an AIR model. Radio Unit (401) includes a multi-layer Printed Circuit Board (PCB) with several radio components mounted on one side of the radio PCB. Antenna Unit (403) includes an antenna PCB and several antenna elements patched on one side of the antenna PCB. A Filter Unit (402) is between the radio PCB and antenna PCB to filter out unnecessary interference outside required spectrum. Each side of the filter unit is connected to the other side of the radio PCB and the antenna PCB respectively. Signals transmitted between the radio unit and antenna unit go through the wired connection.
In the above mentioned MIMO system, a plurality of antenna elements are designed to transmit signals through a plurality of radio branches. Assuming N radio branches are designed, there are N connectors between a filter unit and an antenna unit, and N connectors between the filter unit and a radio unit. The larger the N is, the more connectors are needed. Not only the cost of the connectors is rather high, but the difficulty of assembling the 2N connectors is considerable especially N increases to 64 which is popular in the 4th generation (4G) telecommunication system.

Multi-layer printed circuit board and a wireless communication node