A radiation-recording plate (104) can be constructed and arranged to form an image upon exposure from both a front side and a back side. The plate can include a marker (201) detectable in the image (205) after exposure and indicative of which of the front side and the back side the plate is exposed from. The marker may comprise a medium opaque to the radiation coating a region that does not interfere with reading the image when the plate is exposed from either side, or may be a void in the sensitive layer of the plate. The marker may have horizontal asymmetry about a vertical axis relative to a normal image orientation, or the marker may have vertical asymmetry about a horizontal axis relative to a normal image orientation. The marker may further comprise a front side marker and a back side marker whose appearance in an image on the plate indicates exposure from the front side or the back side respectively. A method of identifying a side from which a radiation-recording plate has been exposed to radiation may comprise: incorporating in the plate (104), in a position that substantially does not interfere with an image area of the plate, a marker (201) whose appearance in the image identifies which side the plate is exposed from; exposing the plate to the radiation; and observing the image (205) for the identification of the side of the plate exposed. A method of making a radiation sensitive plate having at least one radiation sensitive layer may comprise: providing a film sensitive to the radiation on a first side of the radiation sensitive plate; and applying a suspension of a heavy metal in a binder to a region of a second side of the radiation sensitive layer.

This application relates generally to image processing. More specifically, the application relates to identifying image orientation. Yet more specifically, the application relates to identifying image orientation in medical and dental X-ray shadow-grams.
Images produced in conventional roll-film cameras, on film, are easy to orient correctly because the camera is constructed in such a way that the emulsion of the film always faces the lens. Because of the shapes of film cassettes and cameras, the film cannot be inserted in modern cameras with the emulsion facing away from the lens, so it is always known that the light, or other radiation recorded by the film, struck the film from the emulsion side. Thus, when orienting slides for projection, or film images for viewing on a light box, it is always known to put the emulsion toward the projection lens in the slide projector, or to put the film on the light box with the emulsion towards the viewer. When that is done, the image seen by the viewer, whether projected or viewed on the light box, will have a known defined correspondence with the orientation of the objects in the original scene. Moreover, even if orientation is lost, reorienting based on determining where the emulsion is will reestablish proper orientation.
Likewise, digital images produced using cameras with detectors such as charge-coupled devices (CCDs) that are sensitive to exposure from one side only are inherently unambiguous. The cameras used to produce such images are physically constructed and arranged with a lens or lens mount in a fixed position relative to the detector, so that the direction from which the exposing radiation strikes the detector is always known. CCD sensors used in dental digital radiography also are physically constructed and arranged to produce a diagnostic image only when exposed from the proper direction. Such CCD sensors include a radiopaque element on the side away from the intended direction of exposure.
The problem is somewhat more complicated for dental or medical diagnostic images produced on conventional film. One common type of dental or medical diagnostic image is a shadow-gram produced by placing a radiographic film on one side of the object to be imaged and a source of radiation to which the film is sensitive on a diametrically opposite side of the object to be imaged. The radiation, for example X-radiation, casts a shadow of the object to be imaged on the film, thus revealing density variations within the object whose shadow has been cast. When a standard orientation of the examined object is used, and the film is viewed from the same side as the radiation source exposing the emulsion, the laterality, i.e. right versus left, of the object is preserved, because the viewer can unambiguously discern right from left side by observing the image alone. However, medical or dental X-ray film can be exposed and viewed from either side because the film is transparent to both X-rays and visible light. To further complicate matters of orientation, an emulsion is often applied to both sides of the film in order to lower the dosage of radiation required to produce the diagnostic image, by increasing the sensitivity of the film. However, film thus constructed cannot be oriented on the basis of which side has an emulsion. Thus, it is desirable to identify from which side the film was exposed to radiation and so indicate the side from which it should be viewed.
Conventionally, and due in part to its high sensitivity to visible light, as well as to X-rays, radiographic film is usually held in an opaque cassette which not only prevents exposure to visible light, but also limits X-ray exposure to one side of the film, only. The side of the cassette through which large format film, such as that used for medical X-ray applications, is exposed often includes radiopaque labels indicating various patient information, including patient name, date of exposure, side of the patient (e.g., left or right arm), etc., for example, which provide a clear indication embedded in the image of the side of the film from which the exposure was made. If such labels are used, reversal of the image by viewing from the side opposite the side of exposing incident rays also causes the label characters to reverse, clearly indicating the reversed orientation of the diagnostic image. Systems also exist (e.g., Planmeca's pantomograph) which incorporate within the film cassette a mechanism which automatically optically imprints on the margin of the film, and therefore the image, pertinent patient, exposure, and orientation data during the exposure of the film. Often physical features, e.g., notches in the edge or corner of the film or keyways that orient the cassette itself to a cassette holder within the apparatus exposing the object, are used to further ensure that a consistent orientation of the film in the cassette and the exposure apparatus, and thus, the relative orientation of film and the image recorded on it to the object, is obtained and retrievable independently of the structure represented in the diagnostic image itself. The "back side" of the cassette is itself at least partially radiopaque over its entire surface, so as to prevent accidental exposure from the wrong side. The spatial orientation of the original form creating the shadow in the image is thus clearly and unambiguously defined. However, this clear and unambiguous outcome relies either upon the mechanical features noted above, or upon the X-ray technician properly loading the cassette and placing the orienting labels, followed by exposing from the correct side. Otherwise, if the positioning of the film or the cassette is improper, the image produced visually reflects the improper orientation and the process and must be repeated.
Unlike the large format films described above, dental intraoral films are conventionally provided prepackaged in packets, which may be disposable and which are often flexible. Because intraoral films must be small enough to be positioned within the mouth, there is little room available for the types of labels described above. In the case of conventional dental intraoral films, proper orientation is identified by a raised or embossed bump on the film and packet that points away from a radiopaque backing in the packet that prevents or limits inadvertent exposure from the wrong side. The bump, which projects from the plane of the film in the direction from which the shadow is cast, is a permanent feature of the film and persists as marker of the orientation in the dimension perpendicular to the plane of the film, providing a method by which the viewer can identify the side of exposure. If an exposure is made from the wrong side, the resulting image is recognizably undiagnostic because of its degradation caused by the radiopaque backing contained within the packet. The radiopaque backing, typically a textured heavy metal foil, causes exposure from the wrong side to appear in the image as a textured pattern, while the embossed feature preserves and identifies the orientation information for the viewer. As with medical X-rays in which a proper outcome is assured by correct loading of the cassette, a proper outcome using intraoral dental films is assured only by correct assembly of the packet at the factory, followed by correct handling by the dental X-ray technician. The degradation of the image evidencing improper exposure orientation of the film, which results in the reversal of the diagnostic image when the bump feature is used to orient the image, is, however, immediately obvious to the viewer, assuring that mistaken identification of features in the image is highly unlikely and traceable. This combination of an orientation feature and a feature preventing exposure from the wrong side is now conventional.
By convention, dental intraoral films are produced in a variety of generally rectangular standard sizes, with rounded corners. Also by convention, when prepared for viewing, they are grouped in an anatomical arrangement in a holder called a mount. Standard mounts hold films in one of two orientations only: with the longer dimension of the film in a horizontal orientation, henceforth in this application referred to as "landscape" orientation; and with the longer dimension of the film oriented vertically, henceforth referred to in this application as "portrait" orientation.
In keeping with conventions of viewing of radiographic images, on film or on a computer monitor, and for nonambiguity and clarity of the descriptions, the frame of reference for principal directions is based on the image plane, itself. Up shall be a direction generally from any point in the image toward a top of the edge of the image, while down is in an opposite direction. With the up direction oriented in a natural fashion for a viewer, left and right correspond to the viewer's left and right. Vertical corresponds to the direction of a line running up and down from any point in the image.
U.S. Pat. No. 4,625,325 describes a method which incorporates both conventional radiographic film and phosphor in the same process with radiopaque material. The device described patented therein includes a film packet, similar to the intraoral dental film packet described above. The device also incorporates a pocket for holding a plate which is inserted by the technician prior to the exposure of the film. The plate, which is coated with a phosphor on the side facing the film and radiation source and which incorporates radiopaque material on the opposite side, is positioned adjacent to the film in the packet. The plate is an image amplifier. During the exposure, the film is exposed both by X-rays impinging directly on the film and by the phosphorescence emitted by the plate phosphor stimulated by the same X-rays. Those X-rays which have passed both the film and the phosphor are absorbed by the radiopaque backing, thereby limiting tissue exposure downstream of the recording surfaces. The packet, film and plate are held by a jig in a position such that the film and plate can only be exposed from one side. The phosphor only functions as an amplifier to provide improved signal-to-noise ratio and to lower the radiation dose per exposure. The phosphor film does not function as a storage phosphor holding a latent image, and is not scanned to produce a diagnostic digital image. Furthermore, no issues of image orientation ambiguity from a digital electronic image result from the process, because the image is recorded on conventional radiographic film, as before.
Radiosensitive storage phosphor plates have recently started displacing conventional radiographic emulsion film for recording medical and dental images. Advantages including superior sensitivity, lack of dependence on toxic chemical processing fluids, relative insensitivity to ambient light, reusability, and the ease of digital data storage and transmission all stimulate the growth of this technology. The image orientation issues noted above with respect to conventional film; however, as well as new image orientation problems, for example resulting from the use of image processing software, manifest themselves in the use of such radiosensitive plates. As discussed above, the orientation of the image produced by film technology was identified unambiguously by the presence of a three-dimensional object, namely the bump protruding from the film surface toward the object casting the shadow, providing a permanent and absolute reference in a dimension perpendicular to the plane of the film. The other two dimensions, superior-inferior and anterior-posterior are inferred from the anatomical structures in the image. Unlike the image incorporated into a three-dimensional physical object, i.e., the film with a bump, the images produced by existing phosphor plate technologies are stored and displayed as two-dimensional views without a complete, definite, and permanent indicator of the direction of exposure or of viewing. Incomplete references or markers, as discussed below are incorporated into the existing systems; however, none of the systems are unambiguous, permanent, or complete by virtue of their design.
Although radiosensitive plates are sensitive to a specific, diagnostic radiation type, e.g., X-rays, they are substantially insensitive to visible light for the purposes of registering an image. They can be handled in ordinary room light, absent the usual cassette until the time of the exposure. They are, for sanitary and other purposes such as reducing wear and tear on the phosphor, inserted into radiolucent plastic film sleeves before each use. The plates are also reusable to produce multiple images over a period of time. Erasure, by prolonged exposure to intense visible light, and repackaging in the disposable radiolucent plastic film sleeves is done by a technician at the point of use, rather than at the point of manufacture.
A scanner, through laser illumination, stimulates the phosphor to emit light in an amount which depends on the amount of prior exposure to X-rays, and which in turn is registered as data signal. Currently, commercially available phosphor-based digital radiology systems use plates having a polymer sheet substrate supporting a pastel-colored phosphor layer applied to one surface of the substrate. The other surface of the substrate appears black. For the purpose of this application, the side of the plate which is intended by the manufacturer as the preferred side to be read, e.g., by the scanner, to produce the diagnostic image shall be referred to as the "front side", while the opposite side of the plate and sensitive layer shall be referred to as the "back side" henceforth. For practical reasons related to the current technology, the side of the plate that is generally intended as the side to be scanned ("front side") is also the side on which the sensitive layer is nearer the surface of the plate and is visible, thereby available for excitation by the scanning mechanism.
Even though the sensitive layer, e.g., phosphor, is available for scanning from one side, the "front side", only, it can be exposed and register a latent image from either side, and in some commercial systems equally well. As a result of the possibility that the shadow recorded by the sensitive layer, e.g., phosphor, could have been cast from either side of the plane of the plate, the recorded latent image as well as the visible image resulting from its scan are ambiguous with respect to their laterality. Thus, when recording bilaterally symmetric structures, e.g., left or right jaw, mirror images result, which can be easily confused since they are not uniquely oriented. Therefore, the two sides of the body (or mouth) can be confused by the viewer of the image, resulting in erroneous diagnosis and/or treatment. As a result, current commercially available phosphor plate systems, such as those produced by Air Techniques Inc. and Gendex™, provide detailed explicit instructions to package and expose plates in a specific orientation, so as to preserve image orientation.
Some digital systems employ techniques analogous with technology used in conventional emulsion film. For example, Digora™ (available from Soredex) system phosphor plates incorporate a slightly radiopaque layer on the "back side" of the plate, which reduces patient irradiation by rays that pass through the plate and into the patient. The radiopacity of the backing is featureless, but the backing degrades an image exposed by irradiation from the "back side."
Systems such as Scan-X™ (available from Air Techniques Inc.) and Denoptics™ (available from Gendex Dentsply) each feature a distinctive marker. The markers are distinctively shaped, either a lower case letter "a" opaquely printed over the "front side" of the phosphor or a small open circle evident as an absence of the phosphor in a localized area, respectively. These markers are incorporated at the time of fabrication of the plates by the manufacturer and are constructed in such a way as to always be read from the phosphor by the scanner in a constant fashion independent of any exposure variables. The result of the presence of a marker produced by either of the above variants, i.e. Scan-X and Denoptics, in fabrication is a diminution, or absence, of phosphorescence from the area of the plate so altered, during scanning. This relative lack of signal is reflected in the visible scan image as a distinct shape corresponding to the shape and the location of the marker on the phosphor plate.
Any features of such a marker that are either asymmetric or placed asymmetrically with respect to a vertical axis of symmetry of the plate, or both, become represented by similarly asymmetric features in the image of the plate following a scan. Furthermore, this marker image becomes reversed with respect to its laterality either in respect to its asymmetric location or its internal asymmetry as a result of software horizontal reflection of the scanned image. As the placement of the source of the radiation during the exposure has no influence over the appearance of the image of such marker, this marker is well suited as an indicator of any reversal of laterality of the entire image following the completion of the scan.
For practical reasons, namely because the image produced by each of the commercially available phosphor plate technology systems can be displayed and viewed in one of four orientations only, which orientations correspond to the conventional orientations for emulsion-based radiographic film mounts, and which orientations are separated by steps of ninety degree rotation relative one another, the rotational transformations of the image (and the plate position) in this application will also be confined to ninety degree steps, or multiples thereof. Thus the available set of orientations to consider for any image will be the two "landscape" and two "portrait" possibilities, i.e., one right side up and one up side down for each category.
The configuration shown in FIG. 1 illustrates generally how a dental X-ray plate can be used to produce images, X-ray shadowgrams, of a patient's lower jaw and teeth. The particular physiological structure is illustrative of the symmetry problem discussed above. However, the problem occurs in connection with many physiological structures as a result of the inherent symmetry present in most biological systems, particularly humans and animals. The configuration of FIG. 1 is now described as it relates to conventional digital dental X-ray plates. Later, in the DETAILED DESCRIPTION, the configuration of FIG. 1 is referenced as it relates to aspects of the invention, which may be practiced in this configuration, as well as other suitable configurations.
The anatomical structure illustrated in FIG. 1 is a human lower jaw, i.e., a human mandible 101, having a set of teeth 102 set therein. Although not shown, for clarity, it may be assumed that the mandible 101 and teeth 102 are part of a living patient's body, covered with the soft tissues, etc. This particular patient has a diagnostically significant condition, e.g., an abscess, denoted by filled circle 103. A dental technician, dentist or other has placed a conventional digital dental X-ray plate 104 in the patient's mouth in a position suitable for capturing a shadowgram of three of the patient's posterior teeth 105 on either side of the patient's mouth. Although in actual practice, the plate 104 would be placed close to the teeth whose shadowgram is being recorded, so as to produce a clear image, for the convenience of illustration the plate 104 is shown centered between the teeth of the left side and the teeth of the right side of the patient's mouth. Finally, two alternative locations for X-ray sources, SOURCE L and SOURCE R, are shown. X-ray source, SOURCE R, produces the images shown in FIGS. 2 and 3, while X-ray source, SOURCE L, produces the images shown in FIGS. 4 and 5. FIGS. 2, 3, 4 and 5 are now described, with reference back to FIG. 1, as required.
FIGS. 2, 3, 4 and 5 illustrate four images that can be produced using a conventional digital X-ray plate exposed from each of two sides, using each of two differently located sources, e.g., positioned at SOURCE L and SOURCE R. Because the reference conventional commercial plate has an open circle mark on the "front side" of the plate, in one corner, an open circle 201 appears in each of the images. Images produced by source, SOURCE L, include images 205 of posterior teeth 105 and images produced by source, SOURCE R, include both images 205 of posterior teeth 105 and an image 203 of diagnostically significant condition 103. In conventional digital X-ray plate usage, the open circle is present on the "front side" of the plate and is intended to direct the technician, dentist or other to face that side of the plate toward the exposure source. However, such a consistent usage is not guaranteed.
If the plate were to be consistently exposed from only one side (e.g., "front side"), then this marker would provide an absolute reference of laterality by eliminating confusion introduced by horizontally flipping of the image. Such reflection results in the displacement of the open circle marker from the lower right or the upper left corners of the image to the lower left or the upper right in the images which are in "landscape" orientation. The displacement would be the reverse for "portrait" orientation. Although recommended, and consistent with best practice, such a consistent exposure of the plate from the sensitive side is not guaranteed either in the loading of the plate into the sleeve or in its placement during exposure itself.
It should be noted that certain predictable rules of translocation govern a system composed of a radiographic plate, the image it holds, the long and the short axes of symmetry of the plate or its image, and a universe of combinations of two motions, a reflection through a vertical plane perpendicular to that of the image and a 90 degree rotation around an axis perpendicular to the plane of the plate at the intersection of its long and short axes of symmetry.
The reflection of the image within this system can occur through one of two modes. The first mode involves casting the shadow, i.e., registering the image, onto the sensitive layer, e.g., phosphor, from one side of the plate, e.g., "back side", and reading it off the opposite aspect of the sensitive layer, e.g., "front side". Only one instance of this mode may occur per image. This mode of reflection shall henceforth be referred to as "pre-exposure" reflection in this application. The second mode involves the use of an image processing software tool which reflects right-for-left any selected image. The number of instances of this mode of reflection is not theoretically limited. This mode of reflection shall henceforth be referred to as "software" reflection in this application.
Rotation has two distinct modes. The first mode is a physical rotation of the plate, together with its markers, relative to the object to be imaged prior to exposure involved in changing the orientation from "landscape" to "portrait", and if continued, back to "landscape". This mode of rotation shall be referred to henceforth in this application as the "pre-exposure" mode of rotation. The second mode of rotation can occur several ways. After exposure, the plates, being small, unattached objects are free to be moved and become randomized in orientation. These plates are later removed from their sleeves and arbitrarily rotated as to fit into a plate holder mechanism of the scanner, the constraint at this stage being that the "front side" must face the sensor. Once the images are produced on the computer screen, the operator uses the image processor to align the images in proper superior-inferior orientation by rotating them. This software-mediated rotation is limited to multiples of ninety degrees and is the mechanism through which correct "landscape" and "portrait" orientation as well as superior-inferior relationship is achieved as needed. All three of the rotations given above maintain the relationship between the location of the marker and the details of the shadow-gram. They also preserve laterality. The several mechanisms of rotation comprising the second mode of rotation occur after the sensitive layer is exposed and will henceforth in this application be referred to as "post-exposure" mode of rotation. When a "post-exposure" rotation results in a 180 degree rotation, the resulting transformation is equivalent to a reflection of the entire recorded image through a point located at the intersection of the long and the short axes of symmetry of the plate.
In order to better understand the discussion below in the DETAILED DESCRIPTION of how the structures according to aspects of the invention unambiguously identify correct and incorrect image orientation, first a discussion of possible transpositions of the image is given.
Within the context of this application, the two modes of reflection and two modes of rotation comprise the universe of orientation transformations allowed by the laws of physics and by the graphic functions included in the software of the image processors typically provided with digital radiography systems. For the purposes of this example, and in order to demonstrate the inability of only a conventional marker to differentiate various transformations, a marker 3811, as defined earlier, shall be placed in the lower right corner, as viewed from the "front side", of a plate in a "landscape" orientation. In FIG. 38 the images 3801, 3802, 3803, 3804, 3805, 3806, 3807 and 3808 within the same row (e.g., 3801, 3802, 3803 and 3804; or 3805, 3806, 3807 and 3808) are related to their neighboring images by one ninety-degree "post-exposure" rotation for each step. On the other hand images within the same column (e.g., 3801 and 3805, etc.) are related by a "software" reflection through a vertical plane perpendicular to that of the plate. As the images 3801, 3802, 3803 and 3804 and also the images 3805, 3806, 3807 and 3808 illustrate, rotation alone allows only two marker 3811 locations each for both the "portrait" and the "landscape" orientations of the image. That is to say that if the image is only rotated (i.e. they lie within the same row in FIG. 38), there are two allowed locations of the marker 3811 for the "landscape" orientation 3801 and 3803 or, the lower right and the upper left corner, and two allowed locations for the marker in the "portrait" orientation 3802 and 3804: lower left and upper right corner of the image. It is also evident from FIG. 38 that for both the "portrait" and for the "landscape" orientation a combination of rotation within the plane and reflection through a perpendicular plane manipulation, as described earlier, is sufficient to generate all the possible locations of the marker. It is also evident that all paths involving an odd number of reflections (i.e. one which generates a net shift of the image to a different row in FIG. 38) are qualitatively different from the paths involving an even number of reflections (i.e. no net shift of row generated in the process). Therefore, assuming an original position of the marker 3811 in the lower right corner in a "landscape" orientation as in image 3801, it is clear that relative to original image 3801, the laterality of image 3803 has not been reversed but that of image 3809 has been. Furthermore, without the knowledge of the original image 3809, 3810 it is possible to deduce its laterality by observation of the marker location and the "portrait" vs. "landscape" orientation of the plate. It should also be noted that teeth of the lower and the upper jaw are significantly enough different to allow their recognition in radiographic images thereby preserving orientation in the superior-inferior dimension. By analogy, if the long arrow 3810 is assumed to serve as a recognizable index for the superior direction, and the short arrow 3809, the forward direction, then only images 3801 and 3805 represent images properly oriented with respect to the superior-inferior dimension. Furthermore, of those two, only image 3801 has preserved the original laterality of the object casting the shadow. Further complicating the situation is that the plate could have been exposed from the "back side" and viewed from the "front side", resulting in image 3805. This image must be reflected horizontally to be viewed in the "correct" orientation of image 3801.
Suppose, for the purpose of analyzing the images in FIGS. 2, 3, 4 and 5, that the technician, dentist or other exposing this patient's digital dental X-ray plate 104 has oriented the "front side" defined above, carrying the open circle, and consequently the sensitive side of the plate 104, toward the X-ray source located at the position SOURCE L, and in the lower right corner of the plate 104 as viewed from the direction of the X-ray source located at the position SOURCE L. FIG. 3 is the image read from the "front side" of the plate 104, when the plate so oriented is exposed by an X-ray source at the location designated SOURCE R. If the dentist reading such an image is aware that the exposure has been made from the "wrong" side, i.e., the "back side", of the plate, the dentist can use image processing software to reorient the image by horizontally flipping the image, as shown in FIG. 2. Mark 201 is transposed from the right to the left, side of the image. The same plate 104, oriented the same way, but exposed from an X-ray source at the location designated SOURCE L, when read from the sensitive side of the plate 104, produces the image shown in FIG. 5. The image of FIG. 4 can be inadvertently produced by manipulation of the image processing software to horizontally flip the image of FIG. 4. Since FIGS. 2 and 4, and FIGS. 3 and 5, are respectively indistinguishable without knowing from which side the plate 104 was exposed, there is no way to determine which side of the patient's jaw the condition 103, seen only in the images in FIGS. 2 and 3, is on. If condition 103 does not produce any externally observable symptoms, the X-ray image may be the only evidence upon which the dentist can rely for determining the location to treat. An ambiguity is introduced into the record that cannot be resolved without another exposure of the patient to radiation. Digital plate technology in its current form does not assure that the orientation of the image can be ascertained. Current technology instead relies on the statistical likelihood that the technician will expose the film correctly vast majority of the time. However, no unambiguous marker of the exposure orientation exists within the image. The following four examples illustrate the problem of a lack of an internal reference:
1. If only one image is available for viewing independently of other patient information, the viewer will not be able to identify the correct orientation of the image, except by making an assumption that it was exposed from the "front side".
2. If a technician is consistently making the error of exposing the films from the "back side", unknown to the viewer, the viewer will conclude when comparing images that images (in fact) exposed and oriented correctly are incorrectly oriented (which is not factually correct), thus compounding the problem.
3. A disgruntled or incompetent employee can wreak havoc with the records without anyone realizing it, or having a way of tracing the problem by using software to alter the apparent orientation of images in the records.
4. A person with fraudulent intent can expose the plate intentionally from the "back side" in order to make the image appear as though it depicts the opposite side of the body.
The analysis of FIGS. 6, 7, 8 and 9 is similar to FIGS. 2, 3, 4 and 5, respectively, except for the initial orientation of the plate. These images are produced by a plate 104 oriented with an open circle, and consequently the sensitive side of the plate 104 oriented toward the X-ray source located at the position SOURCE L, but in the top left corner of the plate as viewed from the direction of the X-ray source located at the position SOURCE L.
FIGS. 10, 11, 12 and 13 represent images produced by a plate 104 oriented with an open circle, and consequently the sensitive side of the plate 104 oriented toward the X-ray source located at the position SOURCE R, but in the bottom right corner of the plate as viewed from the direction of the X-ray source located at the position SOURCE R.
FIG. 10 shows the image produced by SOURCE R, in which the open circle 201 is in the lower right corner. FIG. 11 can be inadvertently produced by a horizontal flip of the image of FIG. 10 using image processing software. FIG. 12 shows the result of exposing the plate using SOURCE L. In order to view the image in an orientation expected by the dentist, the image of FIG. 12 can be horizontally flipped to produce the image of FIG. 13. Similarly to the situation described above in connection with FIGS. 2, 3, 4 and 5, FIGS. 10 and 12 are inherently indistinguishable, as are FIGS. 11 and 13.
The analysis of FIGS. 14, 15, 16 and 17 is similar to FIGS. 10, 11, 12 and 13, respectively, except for the initial orientation of the plate. These images are produced by a plate 104 oriented with the open circle, and consequently the sensitive side of the plate 104 oriented toward the X-ray source located at the position SOURCE R, but in the top left corner of the plate as viewed from the direction of the X-ray source located at the position SOURCE R.

Radiation sensitive recording plate with orientation identifying marker, method of making, and of using same


A a blood-contacting medical device with improved biocompatibility. The device is coated with a layer of water-soluble heparin, overlaid by a porous polymeric coating through which the heparin can elute. The inclusion of a porous polymer in intimate contact with a heparin on the device controls the administration of heparin following implantation or other blood contact. The adhesion of the coating and the rate at which the heparin is delivered can be controlled by the selection of an appropriate bioabsorbable or biostable polymer.

This invention relates to intravascular devices for contact with blood having blood-contacting surfaces of improved biocompatibility and particularly to stents for treatment of injuries to blood vessels.
Medical devices which serve as substitute blood vessels, synthetic and intraocular lenses, electrodes, catheters, stents and the like in and on the body or as extracorporeal devices intended to be connected to the body to assist in surgery or dialysis are well known. However, the use of such biomaterials in medical devices can stimulate adverse body responses, including rapid thrombogenic action. Various plasma proteins play a role in initiating platelet and fibrin deposition on plastic surfaces. These actions lead to vascular constriction to hinder blood flow, and the inflammatory reaction that follows can lead to the loss of function of the medical device.
A "biomaterial" may be defined as a material that is substantially insoluble in body fluids and that is designed and constructed to be placed in or onto the body or to contact fluid of the body. Ideally, a biomaterial will not induce undesirable reactions in the body such as blood clotting, tissue death, tumor formation, allergic reaction, foreign body reaction (rejection) or inflammatory reaction; will have the physical properties such as strength, elasticity, permeability and flexibility required to function for the intended purpose; can be purified, fabricated and sterilized easily; will substantially maintain its physical properties and function during the time that it remains implanted in or in contact with the body.
As used herein, the solid surface of a biomaterial is characterized as "biocompatible" if it is capable of functioning or existing in contact with biological fluid and/or tissue of a living organism with a net beneficial effect on the living organism. Long term biocompatibility is desired for the purpose of reducing disturbance of the host organism. One approach to improved biocompatibility for biomaterials is to attach various "biomolecules" such as growth factors, antimicrobial agents, antithrombogenic agents, and cell attachment proteins to the surface of the material.
Immobilization of polysaccharides such as heparin to biomaterials has been researched extensively to improve bio- and hemocompatibility. The mechanism responsible for reduced thrombogenicity of heparinized materials is believed to reside in the ability of heparin to speed up the inactivation of serine proteases (blood coagulation enzymes) by AT-III. In the process, AT-III forms a complex with a well defined pentasaccharide sequence in heparin, undergoing a conformational change and thus enhancing the ability of AT-III to form a covalent bond with the active sites of serine proteases such as thrombin. The formed TAT-complex then releases from the polysaccharide, leaving the heparin molecule behind for a second round of inactivation.
Usually, covalent immobilization of heparin to a biomaterial consists of activating the material in such a way that coupling between the biomaterial and functional groups on the heparin (--COOH, --OH, --NH.sub.2) can be achieved. Thromboresistant surfaces are not necessarily obtained using these processes. Heparin can be bound too tightly to the surface due to the high abundance of functional groups on the heparin, or coupling may result from bonds between the active pentasaccharide sequence on the heparin and the biomaterial, preventing activation of AT-III and thus catalytic deactivation of the proteases. In order to obtain truly anti-thrombogenic surfaces, proper immobilization of the biomolecules is key. Larm presented (in U.S. Pat. No. 4,613,665) a method to activate heparin via a controlled nitrous acid degradation step, resulting in degraded heparin molecules of which a part contains a free terminal aldehyde group. Heparin in this form can be covalently bound to an aminated surface in a reductive amination process. Although the molecule is degraded and as a result shows less catalytic activity in solution, the end point attachment of this type of heparin to a surface results in true anti-thromogenicity due to the proper presentation of the biomolecule to the surface. In this fashion, the molecule is freely interacting with AT-III and the coagulation enzymes, preventing the generation of thrombi and microemboli.
Besides the coupling of heparin via its natural functional groups or through a terminal aldehyde group, coupling of heparin via aldehyde groups randomly introduced into the chain by means of periodate oxidation has also been described. Solomon et al (in U.S. Pat. Nos. 4,600,652 and 4,642,242) and Hu et al (in U.S. Pat. Nos. 4,720,512; 4,786,556; 5,032,666 and 5,077,372) coupled heparin after periodate oxidation to an aminated polyurethane obtaining a material with high loading of stably bound heparin with the inventors claiming excellent antithrombogenicity for the material.
On metal or glass surfaces, the binding of the base layer of such multi-layer coatings can be a problem since there is no organic structure to provide covalent bonds between the metal or glass substrate and the grafted base layer. Others have addressed the problem of binding to metals and glass by applying aminosilanes to adhere to the surface and then attaching the biomolecule to the aminosilane through the amine functionality of the aminosilane. This can be seen in U.S. Pat. No. 5,355,433 issued to Rowland et al in which an aminosilane is used to adhere a heparin molecule to the oxidized tantalum surface of a stent. Aminosilanes are also disclosed for attachment of a heparin molecule to glass or metal surfaces in U.S. Pat. No. 4,118,485 issued to Eriksson et al. However, the use of aminosilanes in coatings of this sort has not been very good in producing a surface with a high level of both bioeffectiveness and stability.
It is therefore an object of the present invention to provide a medical device having a therapeutically significant amount of heparin applied to a blood-contacting surface.
It is also an object of the present invention to provide a stent which may be delivered and expanded in a selected blood vessel without losing a therapeutically significant amount of the heparin applied thereto.
It is also an object of the present invention to provide a heparinized medical device which allows for a sustained release of the heparin.
It is also an object of the present invention to provide a simple method for applying a coating of heparin to a medical device.

Blood contacting medical device and method


The present invention relates to an electronic circuit and a method for the monitoring of the driving force of a drive mechanism. To reduce the costs for such a circuit by simple technical circuit measures it is provided that the comparator unit used for monitoring is designed as an analog component, while the set-point adjuster is still integrated into the digital control unit of the drive mechanism. The set points stored in the set-point adjuster are fed to a digital-analog converter in such a manner that an analog reference signal can be generated which can be compared with the analog measuring signal of a power pick-up via the comparator unit.

The present invention relates to an electronic circuit and a method with such a circuit for the monitoring of the driving force of a drive mechanism, preferably an electromotive drive mechanism.
To monitor the driving load of a drive mechanism, electronic circuits are used in driving technology which generate an error signal as soon as the operating state of the drive mechanism deviates from a defined value. In the case of automatically driven doors, for example, such a monitoring circuit serves above all to prevent persons from being injured when they unforeseeably enter the closing area during the closing of the door. A monitoring circuit of this type can generally also protect the drive mechanism against overload and so against destruction.
The monitoring circuits which are usually employed are based on the fact that a measured value characterizing the driving load and a defined set point are supplied to a comparator unit. This generates an error signal as soon as the measured value exceeds the set value with the set value then representing the maximally permissible driving load in this case. If the monitoring circuit is realized within the framework of a microprocessor control system, then the set value is generally available in digital form, for example as a value stored in a memory. The detection of the measured value is usually performed with an analog-digital converter so that the measured values can be evaluated in the microprocessor control system. However, such an arrangement has the disadvantage that high component costs are incurred due to the use of an analog-digital converter. In addition, an analog-digital converter for the detection of measured values requires a complicated filter wiring to avoid aliasing effects.

Electronic monitoring of the driving force of a drive mechanism

Marantec Antriebs-und Steuerunqstechnik GmbH & Co., Produktions KG


A landing net is described and comprises a hoop shaped net body member (17), which is secured to one end of a handle (13). A hinge (15) is located between the two ends of the handle (13) and which permits a section of the handle (13) to be folded from a first fully extended configuration to a second folded configuration in which the other end of the handle (13) is adjacent to the hoop shaped net body member (17). When the folding section of the handle (13) is in the second configuration, it is selectively attachable to the net body member (17).

In this field it is already known that landing nets are used to assist in the landing of fish caught by rod and line by using the landing net to support the fish as it is removed from the water.
Folding versions of landing nets are also known, whereby the landing net comprises a rigid handle of a distinct length, and a hoop shaped net frame on which the net is carried, where the net frame is coupled to one end of the handle by a hinge mechanism. The net frame is moveable between an in-use position where it and the handle coincide in the same plane, and a folded position in which the net frame is pivoted around the end of the handle such that the handle lies across the middle of the net frame for ease of transportation.
In the fly fishing art, it is also known for rigid or collapsible fly line trays to be used to aid casting during fly fishing, whereby the fly line tray helps to prevent the line from tangling, allowing the line to shoot and cast farther.
However, by having separate landing nets and fly line trays, this clearly means that the fisher would have to purchase both items, and further means that the line tray must be carried by the fisher over and above the landing net. Further, although a line tray will be used by the fisher throughout the days fishing, the landing net will not be used until a fish is caught.
Further, conventional folding landing nets have the disadvantage in that there is a tendency for the net to become entangled in the hinge mechanism when it is being unfolded. Also the loose netting is prone to snagging on trees, bushes and reeds which normally populate the riverbank fishing environment.


The present invention provides a method for producing a Group III nitride compound semiconductor, which method permits only minimal reaction of the semiconductor with a hetero-substrate during epitaxial growth and induces no cracks in the Group III nitride compound semiconductor even when the semiconductor is cooled to room temperature. The method includes a buffer layer formation step for forming a gas-etchable buffer layer on the hetero-substrate, and a semiconductor formation step for epitaxially growing the Group III nitride compound semiconductor on the buffer layer through a vapor phase growth method, wherein at least a portion of the buffer layer is gas-etched during or after the semiconductor formation step.

1. Field of the Invention
The present invention relates to a method for producing a Group III nitride compound semiconductor. More particularly, the invention relates to a method for producing a thick-film Group III nitride compound semiconductor or for producing a Group III nitride compound semiconductor having a thickness which allows the semiconductor to be handled as an epitaxial growth substrate. As used herein, the term "Group III nitride compound semiconductor" refers to a semiconductor having arbitrary compound crystal proportions and represented by AlxGayIn1−x−yN (0≦x≦1; 0≦y≦1; 0≦x+y≦1), and encompasses 2-component semiconductors such as AlN, GaN, and InN; 3-component semiconductors such as AlxGa1−xN, AlxIn1−xN, and GaxIn1−xN (in each case, 0<x<1); and 4-component semiconductors represented by AlxGayIn1−x−yN (0<x<1; 0 <y<1; 0<x+y<1). Unless otherwise specified, in the present specification the term "Group III nitride compound semiconductor" also encompasses such semiconductors which are doped with an impurity for determining a conduction type of p or n.
2. Background Art
When Group III nitride compound semiconductors such as those represented by AlxGayIn1−x−yN (0≦x≦1; 0≦y≦1; 0≦x+y≦1) are produced through epitaxial growth, a substrate for growth is required. However, Group III nitride compound semiconductor substrates for use in epitaxial growth having a manageable thickness are not commercially available. Therefore, substrates produced from dissimilar materials other than Group III nitride compound semiconductors, such as a sapphire substrate, a silicon carbide (SiC) substrate, and a silicon (Si) substrate, have been employed instead.
As is well known, the dissimilar substrates have lattice constants which differ considerably from those of Group III nitride compound semiconductors. Thus, generally, a so-called buffer layer is grown on a dissimilar substrate in advance, and a Group III nitride compound semiconductor is epitaxially grown on the buffer layer. Even when this approach is employed, large thermal stress is generated by difference in thermal expansion coefficient between the dissimilar substrate and the Group III nitride compound semiconductor during cooling to room temperature after epitaxial growth conducted at a considerably high temperature of approximately 1,000° C. In other words, even though epitaxial growth can be successfully performed at high temperature, a significant difference in thermal expansion coefficient between the substrate and the Group III nitride compound semiconductor induces a large number of cracks in the dissimilar substrate and the Group III nitride compound semiconductor during cooling to room temperature. There is another drawback that the Group III nitride compound semiconductor and the dissimilar substrate are reacted with each other during crystal growth, affecting the quality of the epitaxial growth layer.
Specifically, approximate linear expansion coefficients (at about room temperature, along the a-axis) of gallium nitride (GaN), aluminum nitride (AlN), sapphire (Al2O3), and silicon (Si) are 5.6×10−6/K, 4.2×10−6/K, 7.5×10−6/K, and 3.6×10−6/K, respectively. Accordingly, when thick-film GaN is formed on a sapphire (Al2O3) substrate or a silicon (Si) substrate, followed by cooling by 1,000 K (or ° C.), a difference in shrinkage as large as 0.2% arises along the a-axis. Particularly when a GaN layer having a thickness of some mm is formed on a sapphire (Al2O3) substrate or a silicon (Si) substrate, cracks are inevitably generated in the formed GaN layer and in the sapphire (Al2O3) substrate or the silicon (Si) substrate, due to thermal stress during cooling.
From another viewpoint, production, through epitaxial growth, of a Group III nitride compound semiconductor, particularly gallium nitride (GaN), of an excellent single-crystalline state has been considered to require a high temperature of approximately 1,000° C. Even if a thick-film Group III nitride compound semiconductor crystal is produced, the dissimilar substrate is difficult to remove. When the dissimilar substrate is removed through chemical polishing, the two-layer structure consisting of the thick-film Group III nitride compound semiconductor crystal and the dissimilar hetero-substrate tends to be warped.

Method for producing Group III nitride compound semiconductor


An exemplary embodiment of the invention relates to a method, system and storage medium for providing supplier branding services over a communications network. The system comprises an information exchange system including a server in communication with a data storage device via a communications link. The server executes web server software for hosting and serving web pages and applications software including a branding tool for creating and disseminating branded information. The data storage device houses a database storing supplier subscription records for facilitating portal services. The supplier subscription records include customer target records. The database also stores customer profile records. The system also includes a link to an enterprise portal site of a registered customer system; and a link to a subscribing supplier system. The branding tool maps the branded information provided in the supplier subscription records to profile information provided in the customer profile records and transfers the resulting targeted branded information to the customer system. The invention also includes a method and storage medium for facilitating the implementation of the supplier branding services.

The present invention relates generally to business-to-business marketing services, and more particularly, to a method, system, and storage medium for providing supplier branding services over a communications network.
Many businesses have recently begun opening up their system firewalls to receive email messages from external sources. While there are obvious advantages in allowing outside information into a business, the reported inundation of unsolicited information has often resulted in overburdened system storage devices, diminished processing speeds, and sometimes overwhelmed system users. Accumulating junk mail (e.g., spam) can quickly consume system resources in a given network, slowing down the users' ability to retrieve important information which can further lead to diminished productivity as users sift through this sea of information
An increasing number of companies are beginning to implement enterprise portals for their employees, including personalized home pages similar to MY YAHOO™ in the public domain. Portals are World Wide Web (WWW) sites that are used as a starting point for users upon connecting to the web or are WWW sites that users visit as an anchor site upon connecting to the web. A portal may be set as a default homepage for users who employ a browser program that includes the homepage. Enterprise portals make it possible for employees to become more productive, by filtering out unwanted information and organizing the barrage of electronic data that inundate their desks each day. However, for suppliers faced with the challenge of one-to-one marketing (e.g., marketing engineering, design, purchasing, production control, logistics, etc.) with the employees of this type of customer organization, these enterprise portals provide both a challenge and a unique opportunity for suppliers to provide branded and timely messages to targeted constituencies within the customer organization. Customer employees could benefit by receiving tailored information to assist them in doing their jobs more effectively.
Recently, Industry Exchanges (IE), (e.g., Covisint™, Transora™, etc.), have been established as trusted third-party systems that facilitate information exchange, particularly for the buyer or customer side. Covisint™ is a business-to-business (B2B) exchange geared toward the automobile industry. It provides product development, procurement, and supply chain management collaboration capabilities for its members via a web-architected information portal. Transora™ is a similar system geared toward the consumer packaged goods industry. Currently, there are no known solutions that provide and manage supplier-branded marketing and related services to targeted constituencies within a customer organization utilizing information exchanges.
The above discussed and other drawbacks and deficiencies of the prior art are overcome or alleviated by the supplier branding tool of the invention.

Method, system and storage medium for providing supplier branding services over a communications network


A photoconductor containing an optional supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the photogenerating layer contains a Type V hydroxygallium phthalocyanine having incorporated therein a silanol.

This disclosure is generally directed to layered imaging members, photoreceptors, photoconductors, and the like. More specifically, the present disclosure is directed to multilayered flexible, belt imaging members, and rigid drum photoconductors comprised of an optional supporting medium like a substrate, a hydroxygallium containing photogenerating layer, and a charge transport layer, including a plurality of charge transport layers, such as a first charge transport layer and a second charge transport layer, an optional adhesive layer, an optional hole blocking or undercoat layer, and an optional overcoating layer, and wherein at least one of the charge transport layers contains at least one charge transport component, a polymer or resin binder, and an optional antioxidant. The photoconductors illustrated herein, in embodiments, have excellent wear resistance, extended lifetimes, elimination or minimization of imaging member scratches on the surface layer or layers of the member, and which scratches can result in undesirable print failures where, for example, the scratches are visible on the final prints generated. Additionally, in embodiments the photoconductors disclosed herein possess excellent, and in a number of instances low Vr (residual potential), and allow the substantial prevention of Vr cycle up when appropriate, high sensitivity; low acceptable image ghosting characteristics, low background and/or minimal charge deficient spots (CDS), and desirable toner cleanability. More specifically, there is illustrated herein in embodiments the formation of Type V hydroxygallium in the presence of suitable silanols. At least one in embodiments refers, for example, to one, to from 1 to about 10, to from 2 to about 7; to from 2 to about 4, to two, and the like.
Also included within the scope of the present disclosure are methods of imaging and printing with the photoconductor devices illustrated herein. These methods generally involve the formation of an electrostatic latent image on the imaging member, followed by developing the image with a toner composition comprised, for example, of thermoplastic resin, colorant, such as pigment, charge additive, and surface additive, reference U.S. Pat. Nos. 4,560,635; 4,298,697 and 4,338,390, the disclosures of which are totally incorporated herein by reference, subsequently transferring the image to a suitable substrate, and permanently affixing the image thereto. In those environments wherein the device is to be used in a printing mode, the imaging method involves the same operation with the exception that exposure can be accomplished with a laser device or image bar. More specifically, flexible belts disclosed herein can be selected for the Xerox Corporation iGEN3® machines that generate with some versions over 100 copies per minute. Processes of imaging, especially xerographic imaging and printing, including digital, and/or color printing, are thus encompassed by the present disclosure. The imaging members are in embodiments sensitive in the wavelength region of, for example, from about 400 to about 900 nanometers, and in particular from about 650 to about 850 nanometers, thus diode lasers can be selected as the light source. Moreover, the imaging members of this disclosure are useful in high resolution color xerographic applications, particularly high speed color copying and printing processes.

This patent is subject to a terminal disclaimer.


A system broadcast alarm messages from a server to a list of users among a plurality of multi-platform users sharing the server in a data transmission network which operates under Internet Protocol (IP) and uses the Java language. The system comprises a profile table containing the profiles of each user, a processing unit and a message sender enabling an administrator associated with the server to transmit alarm messages to the users of the list wherein the users have been selected by selecting profiles in the profile table. The alarm messages are displayed on the screen of the workstation associated with each selected user if this workstation is running.

The data transmission network based upon the Internet Protocol (IP) is becoming a universal network used by more and more people in the world. Since the users interconnected by such a network were operating on different platforms, there was need for a language tool to allow the users to communicate together irregardless of the platform they were using. The Java language that emerged to meet this need is simple and can be easily programmed by most developers without extensive programmer training while being attuned to current software practices. The Java language is object oriented to take advantage of modern software development methodologies and to fit into distributed user-server applications. It is also multithreaded for high performance in applications that need to perform multiple concurrent activities such as multimedia.
The Java language is designed to support applications that are deployed into heterogeneous network environments wherein the application must be capable of executing on a variety of hardware architectures. Within this variety of hardware platforms, the applications can execute atop various operating systems (OS/2, Windows 95, Windows NT, AIX, etc.) and interoperate with multiple programming language interfaces.
Nevertheless, despite the powerful performance of the Java language, there is at present no tool that enables information or an alarm message to be forwarded from a server and to be displayed to one or more users operating on different platforms while these users are running an application.

Method and system for broadcasting alarm messages to selected users of an IP network

International Business Machines Corporation


A method for activating and deactivating parameter sets comprising the steps of: (A) activating a first parameter set in response to a reference to a first identification value associated with the first parameter set and (B) deactivating the first parameter set in response to a reference to a second identification value associated with a second parameter set.

In the MPEG-2 and MPEG-1 compression standards, infrequently changing picture parameter information is transmitted as a picture header included with every coded picture. The H.264/MPEG4-AVC standard divides infrequently changing picture parameter information into sequence parameter sets (SPSs) and picture parameter sets (PPSs) that may be transmitted only infrequently. Examples of infrequently changing picture parameter information include picture dimensions (i.e., picture width and height in pixels), initial picture quantization parameters (QPs) and various other coding parameters that are specified at a picture level.
The existing solution only activates picture parameter sets when the picture parameter sets are first referenced and does not provide a process for deactivating the activated picture parameter sets. The existing solution has a number of interrelated disadvantages. The existing solution prevents re-assignment of a "the active parameter set" tag to a previously encountered parameter set unless the previously encountered parameter set is re-transmitted with a new id such that a new first reference can occur. A practical scenario that illustrates the disadvantage of restricting activation of parameter sets to the first reference is the scenario of commercial insertion. Because the re-assignment of the "the active parameter set" tag to a parameter set previously tagged as "the active parameter set" is not possible, the parameter sets for a main program must be re-transmitted with a new id when returning to the main program after each commercial insertion. Because only a finite number of ids are available, a bitstream may eventually run out of unique ids that can be used to activate a parameter set through a "first" reference (i.e., after a finite number of parameter changes no more changes to the parameters would be possible in the existing solution).
Another disadvantage of the existing solution is that the lack of a process for deactivating parameter sets allows an activated sequence parameter set to remain active for an entire coded video sequence and imposes no restriction on activation of new sequence parameter sets. As a result, a new sequence parameter set can be activated and be tagged as "the active parameter set" in the middle of the coded video sequence. A coded video sequence is defined as a sequence of pictures, in decoding order, beginning with an instantaneous decoding refresh (IDR) picture and followed by zero or more non-IDR pictures. An IDR picture prevents motion compensated prediction from previous (in decoding order) pictures. Because a new sequence parameter set can be tagged as "the active parameter set" in the middle of the coded video sequence, pictures with different resolution and dimensions can be motion compensated from each other. Permitting a new sequence parameter set to be tagged as "the active parameter set" in the middle of the coded video sequence could greatly complicate the implementation of decoders compliant with the standard.
A solution that provides for activation and deactivation of infrequently changing sequence and picture parameter sets would be desirable.

Method for activation and deactivation of infrequently changing sequence and picture parameter sets


Disclosed is an adaptive transmit and receive method and device in a multiple-antenna wireless communication system. A transmit mode comprises different main transmit modes each of which includes one or both of a sub-transmit mode based on STBC and a sub-transmit mode based on SM. A receiver calculates an STBC performance parameter and a SM performance parameter, and a transmitter uses the parameters to determine a main transmit mode with maximum data rates and select a sub-transmit mode for minimizing power consumption. The transmitter channel-encodes, modulates and antenna-maps input data according to the selected transmit mode, and outputs results to the receiver. The receiver antenna/symbol-demodulates and channel-decodes the received data.

(a) Field of the Invention
The present invention relates to a wireless communication system with multiple antennas. More specifically, the present invention relates to an adaptive transmission and receiving method and device in a wireless communication system with multiple antennas.
(b) Description of the Related Art
The MIMO (multiple input multiple output) method, which is a transmission and receiving method using a plurality of antennas at a transmitter and a receiver, is one of the most noteworthy techniques in the wireless/mobile communication systems because of its performance improvement possibilities in increasing spectral efficiencies and diversity of transmission and reception.
One method for increasing data rates from among the transmission and receiving methods with multiple antennas is an SM (spatial multiplexing) method, in which a symbol sequence is divided into a plurality of sequences and transmitted to different transmit antennas. The symbols transmitted through the different antennas according to the SM method can be detected by using an OSIC (ordered successive interference canceller) receiver, a linear receiver based on ZF (zero forcing) or the MMSE (minimum mean square error) criterion, or an optimal ML (maximum likelihood) receiver.
Meanwhile, antenna diversity schemes are widely used to reduce a multi-path fading effect without increasing the data rates. In particular, the transmit diversity method by the Alamouti scheme in the case of two transmit antennas is widely applied to 3rd generation mobile communication systems and broadband radio-access systems, because the transmit diversity method provides simple configurations of the transmitter and the receiver and enables acquisition of diversity of transmit and receive channels. The Alamouti antenna transmit method is an orthogonal STBC (space time block code) for two transmit antennas. However, an orthogonal code exists only when two transmit antennas are provided, and hence, pseudo orthogonal STBCs have been proposed for other numbers of transmit antennas. When such codes are applied in the frequency domain as in the OFDM (orthogonal frequency division multiplexing) transmission, they are called as SFBC (space frequency block code).
As described, since the SM method transmits a different symbol for each transmit antenna, its performance is substantially changed according to features of elements of an MIMO channel, but since the performance of an STBC method is determined not by each element of the MIMO channel but by the summation of the elements, the STBC method is less sensitive to the MIMO channel features, and hence, a desired antenna transmit method can be differentiated according to the channel environments.
A prior art for improving performance such as capacity and quality in the multiple antenna system is disclosed in U.S. Pat. No. 6,351,499 by Iospan which varies a number of transmit antennas for SM according to characteristics of the MIMO channel. However, since the number of the transmit antennas is varied, functions of a receiver become complicated, and the prior art does not exploit the advantages of an STBC.
Together with this, an actively applied method for increasing the data throughput in the current state is the adaptive modulation coding method which selects a modulation order and a code rate suitable for desired performance according to an instantaneous state of fading and background noise intensity of a wireless channel, and transmits them variably, thereby increasing the data throughput. The above-noted adaptive modulation coding method is applied to the HSDPA and the 1xEV-DV which are evolved 3rd generation mobile communication systems, and to the wireless LAN system and to the broadband radio access system, and it has been currently developed and commercialized.
However, selection references for channel state information and a modulation and coding method used by the conventional adaptive modulation coding methods are difficult to directly apply to wireless communication systems with multiple antennas that use spatial multiplexing, performance of which is greatly varied according to characteristics of the MIMO channel.

Adaptive transmission and receiving method and device in wireless communication system with multiple antennas

Electronics and Telecommunications Research Institute


A photoconductor for electrophotography is composed of a conductive substrate, an undercoat layer formed on the conductive substrate, a charge generating layer formed on the undercoat layer and a charge transporting layer formed on the charge generating layer. The undercoat layer comprises a crosslinked polyamide represented by the following formula, ##STR1## wherein m and n stand for positive integers.

1. Field of the Invention
The present invention relates to a photoconductor for electrophotography and more particularly to a photoconductor having an undercoat layer for preventing the influence by the circumferential humidity and improving reliability thereof.
2. Description of the Prior Art
Up to the present, a low-price and pollution-free organic photosensitive material is used generally as a photoconductor for electrophotography (hereinafter to be referred to as a photoconductor) used in copying apparatuses of an electrophotographic system. Various photoconductors are known, for instance, a photoconductive resin type represented by polyvinylcarbazole (PVK), an electron-transfer complex type represented by PVK-TNF (2, 4, 7 trinitrofluorene), a pigment dispersion type represented by a phthalocyanine binder and a functionally distinguishable type using a charge generating substance in combination with a charge transporting substance. Among them, a functionally distinguishable photoconductor is specifically noticed.
When the Carlson process is used for image formation, these high sensitive photoconductors of functionally distinguishable organic types have the following problems:
(1) The photoconductor is hardly electrificated and its ability to retain an electric charge is poor, that is, the dark attenuation is high and the deterioration of characteristics is considerably high in repeated use.
(2) Non-uniformity of density and fog happen on the images obtained.
(3) Scumming happens in the case of the reversal development.
For the purpose of solving the above-mentioned problems, it is known that an intermediate layer is provided between a conductive substrate and a photosensitive layer as an undercoat layer of the photosensitive layer. The intermediate layers in which use are made of nylon type resins are disclosed in Japanese Patent Application Laying-open Nos. 47344/1973, 25638/1977, 30757/1983, 63945/1983, 95351/1983, 98739/1983 and 66258/1985. The intermediate layers in which use are made of maleic acid type resins are disclosed in Japanese Patent Application Laying-open Nos. 69332/1974 and 10138/1977. In addition, an intermediate layer in which use is made of polyvinylalcohol resin is disclosed in Japanese Patent Application Laying-open No. 105155/1983.
However, since an insulating resin is used as the undercoat layer in many cases, there were problems that the residual voltage of the photoconductor became high and the contrast of an image became poor. When a polyamide (Nylon(Trademark)) having a low electric resistance is used, it is possible to control the residual voltage. However, since a polyamide has a high water absorption, the characteristics of the photoconductor vary under the influence of a circumferencial humidity. For instance, in the reversal development system, fog occures under a high humidity circumstance and a density of the image decreases under a low humidity circumstance. In addition, there were also problems that the adhesion of a polyamide to an aluminum substrate with a rough surface is poor and it is impossible to cover the pinholes of the surface of the substrate.

Photoconductor for electrophotography having an undercoat layer


A method of manufacturing a device having embedded memory including a plurality of memory cells. During manufacturing test, a first test stress is applied to selected cells of the plurality of memory cells with a built-in self test. At least one weak memory cell is identified. The at least one weak memory cell is repaired. A second test stress is applied to the selected cells and the repaired cells with the built-in self test.

An application-specific integrated circuit or "ASIC" is an integrated circuit ("IC") designed to perform a particular function by defining the interconnection of a set of basic circuit building blocks drawn from a library provided by the circuit manufacturer. An ASIC is an IC with functionality customized for a particular use, such as particular equipment or a particular project, rather than being for general-purpose use. For example, a chip designed solely to run a cash register is an ASIC. In contrast, a microprocessor is not application specific because it can be adapted to many purposes.
An "embedded system" is a special-purpose computer system built into a larger device. An embedded system is typically required to meet very different requirements than a general-purpose personal computer. Nearly all companies use embedded memory. Because many embedded systems are produced in the tens of thousands to millions of units range, reducing cost is a major concern. Embedded systems often use a relatively slow processor and small memory size to minimize costs.
Nearly all ASIC chips contain "static random access memory" or "SRAM" as embedded memory. SRAM is a type of semiconductor memory. Random access indicates that locations in the memory can be accessed, i.e., written or read, in any order regardless of the memory location that was previously accessed. A SRAM cell involves random access memory in which each bit of storage is a bi-stable flip-flop, commonly consisting of cross-coupled inverters. The memory cell is called "static" because it will retain a value as long as power is supplied, unlike dynamic random access memory or "DRAM," which must be regularly refreshed. Nevertheless, a SRAM cell is still volatile: it will lose its contents when the power is switched off (in contrast to a read-only memory or "ROM" cell). SRAM is usually faster than DRAM. It is used for the parts of a computer that require highest speed, such as cache memory.
Some memory cells, including SRAM cells, may be marginally functional. They might pass initial testing, but then fail in the field under normal operating conditions which are slightly different from the conditions that are present during the initial testing. Even if cells are tested at operational speed, there might be a cell that is right on the edge of failure and can fail in the field after it is shipped to the customer and while the customer is using it in the customer's application. When SRAM cells fail in the field, the failure creates a "shipped product quality level" or SPQL problem. If the SPQL number gets too high, the customers are dissatisfied. Even though the supplier of the memory cells can give the customer a new part, the customer may have experienced unnecessary delays. SPQL is becoming more and more important in embedded memory.
Although IC manufacturers strive to make chips with minimum defects, as a practical matter defects still occur for various reasons. For example, particles of dust may settle on the surface of a silicon wafer during processing. Embedded memories are increasingly susceptible to such defects as the density and quantity of memory on ICs increases. The impact of a defect within the embedded memories on overall yield, or the ratio of acceptable to unacceptable total components, has also increased significantly. Because a single defect in a single memory cell can render the whole IC unusable, techniques to test for such defects and repair them by using extra storage cells have been implemented. These techniques seek to improve the overall yield and, therefore, reduce the cost of the IC.
Conventional test and repair techniques are known. For example, U.S. Pat. No. 6,246,618 issued to Yamamoto et al. discloses test-repair control logic for choosing a random access memory or "RAM" test and repair mode and for choosing an ordinary mode for carrying out ordinary operations. The control logic tests multiple RAMs on a chip and replaces bad RAMs as a whole.
A built-in self test or "BIST" is a technique of designing circuits with additional logic which can be used to test proper operation of the primary (functional) logic. U.S. Pat. No. 6,343,366 issued to Okitaka discloses selectors for changing data paths during a normal operating mode and a test operating mode. A BIST circuit built in a LSI SRAM device and a self repair circuit are also disclosed. This patent teaches a basic BIST.
Various devices and methods to test memory cells have been developed. But testing to identify problem cells is only a first step. Once identified, the problem cells must be repaired. A built-in self repair or "BISR" is a technique of designing circuits with additional logic which can be used to repair the operation of the primary logic. Conventional BIST and BISR techniques are known.
U.S. Pat. No. 6,560,740 issued to Zuraski, Jr. et al. discloses an apparatus and method for BIST and BISR of an embedded memory formed of random logic on a semiconductor substrate. A control signal determines the operating mode during testing. Input and output signals are used during normal operation. The patent shows a simple BIST that does not have the flexibility to test the memory in a harder or easier manner.
U.S. Pat. No. 6,496,947 issued to Schwarz discloses BIST and BISR operations for testing and repairing of weak, leaky, or faulty SRAM cells. During normal operation, the test input is inactive and external address inputs are used to access selected memory locations. Disclosed are two modes, a factory mode and a field mode (basically test and customer). Schwarz addresses a particular type of fail called a retention fail. The system adds an extra test in the factory that takes longer to find these fails. It weeds out retention failures with a pause in the testing. If the testing procedure waits long enough (for example, two or three milliseconds), thereby inserting a pause, the system will find a fail. When the customer receives the SRAM, the customer does not have the extra delay. This system tests the system in a slower condition than the customer's operational mode.
U.S. Pat. No. 6,246,617 issued to Urakawa discloses a test process for a large scale integrated ("LSI") SRAM including a redundant circuit for BIST and BISR methods. After the test and repair, a reading circuit chooses between a proper memory array and a redundancy program array during a normal read operation. The patent shows a basic BIST and repair.
U.S. Pat. No. 6,085,334 issued to Giles et al. discloses a method of testing an array of SRAM cells for defects which are sensitive to environmental conditions. A BIST is used for the testing and a BISR is used for replacing failed memory locations with spare memory elements. Normal operation through an interface is also disclosed. The patent shows a basic BIST and discusses tests under several environmental conditions or corners.
U.S. Pat. No. 6,067,262 issued to Irrinki et al. discloses a methodology for screening out field errors at the factory using BIST and BISR circuitry. A "march" test and a "neighbor pattern sensitive" test are used on SRAMs. The circuitry includes data bus signals during normal operation. The patent shows a basic BIST and also discusses tests under several environmental conditions.
U.S. Pat. No. 5,987,632 issued to Irrinki et al. discloses performing a BIST to detect marginal memory cells at degraded conditions after each power-up in the field. A BISR replaces a failing cell with a spare row or column. After testing is complete, normal operation is commenced. No SRAM is disclosed. The BIST runs at various corners.
U.S. Pat. No. 5,909,404 issued to Schwarz discloses applying BIST and BISR to DRAMs rather than SRAMs due to the higher storage capacity of DRAMs. After testing is complete, normal read is performed. The patent shows a BIST that looks for retention fails.
WO 02/103,522 was published on behalf of Templeton and discloses an embedded memory device. Both BIST and BISR are performed on memory cells which are detected as being weak once the operating conditions change from the normal operation by increasing the duration of the read or write. A BIST runs with a stress clock and a BISR is used during each power-up of the memory device. Thus, a testing algorithm runs every time the power is turned on. When the customer turns on the power, the system runs through the algorithm and both tests and repairs itself. But the customer has to wait every time the system is powered up for the entire sequence to complete.
To overcome the shortcomings of memory cell failures, specifically SRAM failures, in the field and to obtain lower SPQL levels, a new method and apparatus of testing SRAM cells is provided. An object of the present invention is to provide an improved method of testing memory cells, including SRAM cells, during the manufacturing process to eliminate defective cells and cells that might fail in the field. A related object is to improve and raise SPQL levels by decreasing the number of memory cells, including SRAM cells, that fail in the field under normal operating conditions when they are in use by the customer.

Method and apparatus for test and repair of marginally functional SRAM cells


The mirrored eye drop target is used in connection with an eye drop container. The drop or dropper target includes an elongated planar substrate having a mirrored or reflective first end segment and an adhering second end segment. In a preferred embodiment, the adhesive on the second end segment is initially covered by a removable substrate or cover. After removal of the substrate (which exposes the adhesive), the planar substrate is attached to the body of the eye drop container. The mirrored or reflective first end segment is substantially vertically aligned with the eye drop spout end such that when the composite structure (the planar substrate and eye drop container) is substantially horizontally disposed, eye drops ejected from the spout end substantially fall in a single vertical line established by the visual target or on the mirrored or reflective surface, the spout end and the user's eye. In other words, when the user visually centers his or her reflected eye image in the target and aligns the image with the spout end, and when the eye dropper is substantially horizontally disposed, fluid falls into the eye upon ejection from the spout end.

The present invention relates to a mirrored eye drop target and a method for directing eye drops into an eye of an user.
Eye drops are sometimes utilized by users to deliver medication to the eye or relieve eye strain or simply to clear debris from the eye. Commonly, the eye drops are carried by an eye dropper which normally includes a fluid containment body or container, an eye dropper spout and a spout end. To deliver eye drops into the eye, the user substantially horizontally positions his or her eye and substantially vertically positions the spout end preferably above the pupil of the eye or generally above the eyeball. Hopefully, the user maintains a distance of about 2-4 inches between his or her eyeball and the dropper spout in order to avoid damage to the eye due to inadvertent physical contact. It is relatively difficult to substantially horizontally position the head and eye and substantially vertically deliver the eye drops into the eye cavity and the eyeball. Various structures have been created to accurately position the spout end vertically above the eyeball. U.S. Pat. No. 4,344,430 to Astrove discloses a mirrored surface which is angularly disposed with respect to a substrate. The substrate is angularly attached to the base of the eye dropper. U.S. Pat. No. 3,913,575 to Windsor discloses an eye dropper device which includes a swing out mirror attached to the base of the eye dropper. U.S. Pat. No. 3,779,245 to Windsor discloses another eye dropper which includes a mirrored or reflective surface attached to the base of the eye dropper. All of these systems suffer from the defect that the reflective surface should be in a plane parallel to the axial centerline of the eye dropper and particularly vertically aligned with the eye drop spout and the spout end when the eye dropper is substantially horizontally disposed. The present invention overcomes these difficulties.

Mirrored eye drop target and method therefor


A system is provided for use with a multi-user detector MUD, which dramatically decreases the processing time for separating out interfering transmissions from a number of users by eliminating from each processing iteration consideration of those bit estimates for which the probability or estimate of their value exceeds a predetermined threshold and can therefore be declared “certain”. In a Turbo MUD environment in which the output of the MUD is coupled back to the MUD through an error correction system, the output of the error correction is thresholded such that those bit estimates having probabilities or estimates greater than a predetermined threshold are assigned a quantized value and are eliminated from further processing by the MUD. For certain low-complexity processing Turbo MUDs there can be as much of a reduction as one-third in processing time, whereas for full MUD processing, the reduction in processing time can be as much as 1/30th.

The problem of separating out or disambiguating interfering digital transmissions from different users has been resolved in the past by utilizing multi-user detectors as described in Verdu, "Multiuser Detector", Cambridge University Press, 1998 and by Wang and Poor, "Iterative Turbo Soft Interference Cancellation and Decoding for Coded CDMA, IEEE Transactions on Communications," July, 1999, as well as a patent application Ser. No. 09/923,709, filed by Rachel Learned et al on Aug. 7, 2001, entitled Method For Overusing Frequencies To Permit Simultaneous Transmission Of Signals From Two Or More Users On The Same Frequency and Time Slot, and incorporated herein by reference.
For full multi-user detection systems which examine the entire universe of possibilities for each bit from each user, the processing time is inordinately long. The processing time is, of course, exponentially proportional to the number of interfering signals that exist. In general, processing time has been reduced by several suboptimal methods through the examination of less than the entire number of possibilities for a given bit from a given user. A Turbo MUD is one such example.
More particularly, for terrestrial-based CDMA wireless communication systems, if it were possible to be able to accommodate a larger number of users on the same channel, meaning transmitting at the same frequency at the same time, then network utilization could be increased dramatically. CDMA systems exist that can accommodate a given number of simultaneous users and in general, use matched filtering techniques for separating out the signals. When, however, these systems have more users than they were designed for, or practical limitations result in a fewer number of users than can actually be accommodated, then a so-called over-saturated condition occurs.
One way of addressing the over-saturation issue is to utilize multi-user detectors to be able to separate out the interfering signals. One of the problems with the utilization of multi-user detectors, MUDs, in over-saturated environments is the processing time necessary to be able to separate out the interfering signals. In some over-saturated cases, only full MUD processing is available to be able to separate out the signals.
It will be appreciated that iteratively processing MUDs, called Turbo MUDs, are generally designed as a low-complexity way of being able to duplicate the functions of a full MUD. The low-complexity MUDs use considerably less processing time than full MUDs, making possible real-time recovery of the interfering signals. Note that Turbo MUDs in general utilize the information in forward error correction codes to be able to accomplish their task.
The result is that while Turbo MUD techniques have considerably improved processing times with respect to separating out the interfering signals, when either over-saturation occurs or becomes severe; or in fact, when processing times are to be reduced regardless, it is important to be able to quickly arrive at a value for a given bit for a given user, meaning that the error rate drops below an acceptable level for the particular communication scheme involved.
For an entire class of Turbo MUDs, the MUD processes the incoming signals on a time instant by time instant basis to provide for each user a series of best guesses as to what the individual bit should be for a given time. These best guesses, commonly known as soft outputs, are utilized in an error correction device, usually a single-user detector such as a BCJR Decoder, the purpose of which is to provide error correction for the bits for each user by comparing the present bit to a prior bit and/or a subsequent bit.
The result of such an error correction is a matrix of bit estimates which ordinarily are used by the MUD in the iterative process to provide better estimates of the particular bit. The number of iterations necessary to reduce the error rate to a predetermined acceptable level is a function of a number of factors, most notably the number of simultaneous users.
In the past, such processing has taken a long period of time, so long that the result is considered a non-real time response.
For instance, the conventional, minimum mean squared error, MMSE, multi-user detector which is described by Wang and Poor mentioned above, is relatively slow. It involves an iterative process for separating interfering signals in which the output of an error corrector is fed back to a multi-user detector for the purpose of obtaining better guesses as to the individual bits in the incoming data stream on the subsequent iterations.

System for decreasing processing time in an iterative multi-user detector system

BAE Systems Information and Electronic Systems Integration Inc.


A ceramic heating element has been conventionally driven by direct-current voltage, but the direct-current voltage causes a problem in the heating element. Therefore, in a method of the present invention, an alternating current is supplied to the heating element by changing a direct current, so that deformation of the heating element can be prevented and reliability can be improved.

The present invention relates to a driving method of a ceramic heating element which is used as a heating element for an infrared ray source.
FIG. 4 shows an example of a ceramic heating element, generally indicated by the numeral 1, as an infrared ray source.
A heating element 1 is constructed of a sheet member with a thickness of about 0.5 mm, which is formed by shaping a raw material powder into a sheet and burning or sintering the same. The sheet member is processed by an electrical discharge method to form a zigzag heating element 11 and linear lead members 12a, 12b and is attached to a ceramic tube 14 by heat-resistant adhesive material 13. Incidentally, 2a and 2b designate lead wires which are connected to the lead members 12a and 12b, respectively.
The ceramic heating element 1 as an infrared ray source shown in FIG. 4 is normally driven by a direct-current (DC) voltage so as not to cause unsteadiness or instability in the quantity of light. However, when a temperature at the heating element is around 1,500 .degree. C. and heating time becomes several hundred hours, a temperature distribution of the heating element may change locally or deformation might occur, ultimately resulting in disconnection.
Also, it is confirmed that this kind of abnormality remarkably occurs on the positive terminal side. It is presumed that this is not because of unevenness or heterogeneity of the material, but because of migration of atoms.
Therefore, an object of the invention is to prevent abnormality such as deformation being caused in the ceramic heating element as the infrared ray source, and to improve the reliability of the heating element.
Further objects and advantages of the invention will be apparent from the following description of the invention.

Driving method of ceramic heating element for an infrared ray source