Abstract: In an optical finger image system, a platen is provided to receive and support a finger to be interrogated. A light beam source orients an interrogating light beam onto the platen, so that the beam forms a shallow angle with the platen and intersects the platen at a trace. The light beam illuminates ridge, valley, and ridge/valley edge portions of the finger. An image of the finger generated by the interrogating light beam is focused by imaging optics onto an image plane. A photo-electric transducer array is positioned at the image plane, the transducer array having a window region. The window region is positioned such that illuminated ridge and ridge/valley edge portions of the finger are imaged within the window; while illuminated valley portions of the finger are not imaged in the window. The angle of the light beam incident on the platen is compounded to generate an image of enhanced brightness at ridge/valley edges.

Abstract: The invention relates to a fusible stabiliser combination for thermoplastic polymers with the features of the main claim. The invention also relates to a process for the preparation of said combination, and thermoplastic polymers produced by the use thereof.

Abstract: The invention concerns basic layered lattice compounds of the general formula (I) Me.sup.III.sub.a Me.sup.II.sub.b (Me.sup.IV).sub.c (OH).sub.d O.sub.e A.sup.n.sub.f .times.mH.sub.2 O, a process for producing the same and the use thereof in a halogen-containing resin composition having improved thermal stability, initial coloring and improved color fastness.

Abstract: A mine roof support frame has a pair of spaced-apart floor skids on which hydraulic props support a roof engaging structure. A shifting mechanism with a ram in a trough-like housing and a guide beam is positioned between the skids and serves to displace the frame relative to a scraper-chain conveyor and vice versa. The guide beam is a flat plate with a width more or less the same as the space between the skids and rests directly on the floor. The piston rod of the ram is coupled to the guide beam near the conveyor, the ram cylinder is coupled to the housing and the housing is coupled to the skids at the stowage end. The ram housing has a guide rail on the underside which mates with a guide element on the top of the guide beam. Levers pivotably coupled to the floor sills in front of the ram housing are operated by piston and cylinder units to engage on the guide beam to lift the floor skids partially during advancement of the frame.

Abstract: A plumbing box mounted in fluid communication with fluid pipes within wall structure is arranged to provide for threaded bores for securement of the pipes thereto, with a front wall of the box or housing structure having a plug member frictionally retained within a front wall smooth bore. Upon freezing of fluid within the box structure, the plug member is displaced relative to the box indicating pipe freezing, with the plug member arranged with its cap portion coplanar with a wall surface for visual indication of a freezing condition within the pipe structure directed into the box.

Abstract: A layer of liquid, such as alcohol, water or a mixture thereof, on the finger touching surface of a platen provides an image in an optical fingerprint imaging system which assures valley and ridge definition and continuity by virtue of the liquid filling in the cracks and holes in the ridge zone, by creating an air pocket in the valley zone that holds the valleys open and by otherwise interacting with the finger to reinforce the distinction between valley and ridge zones in the optically imaged picture. Multiple interrogating light beams, each incident at greater than the critical angle on the finger touching surface of the platen assure imaging all minutia and that the valley zones in the image will be black. The technique is useful for roll prints and touch prints.

Abstract: A layer of liquid, such as water, on the finger touching surface of a platen provides an image in a optical fingerprint imaging system which assures valley and ridge definition and continuity by virture of the water filling in the cracks and holes in the ridge zone and by creating an air pocket in the valley zone that holds the valleys open. Multiple interrogating light beams, each incident at greater than the critical angle on the finger touching surface of the platen assure imaging all minutia and that the valley zones in the image will be black.

Abstract: The technique for optically scanning a finger to produce a fingerprint image involves positioning the finger surface to be optically scanned so that it is exposed and, in particular, is not pressed against a platen. A slit light beam along the length of the forward part of the finger is circumferentially rotated about an axis about the nominal center of the finger. A reflected slit light beam carries modulation information which is focused on a linear array of photo-electric transducers to provide the fingerprint image. The interrogating light is coherent, substantially collimated, light. The plane of the interrogating slit light beam and the plane of the reflected modulated slit light beam are coplanar thereby establishing an illumination plane. The illumination plane is parallel to the axis of the finger and is rotated about that axis during the interrogating scan.

Abstract: A curved cylindrical segment platen has a concave touching surface. An interrogating slit light beam is scanned around the platen to scan a finger held against the touching surface. An optical imaging system images the zone illuminated onto an array of photo-transducers to provide a signal representing the fingerprint. The optical system is rotated around the platen. The axis of the interrogating light beam is substantially normal to the touching surface. The axis of the imaging system is off normal by about 56 degrees, an amount which is greater than a critical angle equal to the maximum angle of refraction in the platen. This critical angle is approximately 41 degrees. The axis of the imaging system is also off normal to the non-touching surface by an angle that is less than this critical angle of 41 degrees and thus less than the angle of total internal reflection. As a consequence, the image at the photo-transducers provides a completely dark valley zone and a sharply contrasting light image ridge zone.

Abstract: An automatic fingerprint enrollment and identification technique is provided for automatically processing an input image represented by pixels having either a one or zero value. The automatic processing involves a series of steps in which the initial processing is a rough screening technique for eliminating a reasonable portion of the noise while passing through almost all of the minutia. As the steps proceed, the processing becomes more complex to provide a tighter screening out of noise while passing through as much of the minutia as possible. The later steps by operating on relatively fewer minutia or anomaly points that the earlier steps can be economical though more complex so as to be more discriminate than the earlier steps. The processing provides an optimum trade off between enrolling as large a proportion of the population as possible while minimizing the number of false identification errors.

Abstract: An optical and electronic scan produces an image composed of binary value pixels. An automatic picture compression routine reduces the number of pixels in the image. A first stage four to one reduction in the number of pixels is achieved by treating each mutually exclusive four pixel unit as a separate set. A binary value is assigned to each four pixel set. That binary value is assigned to a single pixel in a first output image. The same process is repeated a second time to provide a final output image that has one-sixteenth the number of pixels as has the original input image. The value assigned to each four pixel unit set is a weighted function of the binary value of each of the sixteen pixels in a four pixel by four pixel subfield in which the unit set is centered. The greatest weight is give to the center pixels, that is, to the four pixels of the unit set. Lesser weight is given to the peripheral pixels.

Abstract: A set of Search identification points derived from an optical scan of a finger are compared against File identification points for the same finger. A multiple comparator divides the finger image into multiple segments. The Search and File points from each segment are compared separately. A difference table (D.T.) provides a proximity value Q for each search point. The D.T. is purged of all entries representing multiple Search points. The purge keeps those entries having the highest Q value. The purged D.T. with recalculated Q values is the basis for correcting the position of each Search point on the image plane to compensate for shift in finger position and for the variable distortion and changes that come about in a finger over time and upon successive applications of the finger to input scan. The corrected Search points are compared against the File points to establish a new D.T. A proximity value Q for each entry on this D.T. is calculated and a proximity value Q for the entire table is calculated.

Abstract: A gray scale image of a fingerprint composed of a field of pixels is converted to a binary image composed of a field of pixels by a technique which takes into account the directivity of the ridge and valley structure. Three intermediate binary images are developed, one by the use of a vertical filter, one by the use of a horizontal filter and a reference image by the use of a filter which is not directionally biased. Corresponding subfields around each pixel in each of the three images are compared. If the subfield for the vertically derived image is closer to that of the reference image then is the subfield for the horizontally derived image, then the binary value for the pixel from the vertically derived image is used in the final image; and vice versa. In this fashion, a fourth a final binary image is derived from a combination of the vertically derived image and horizontally derived image which includes the best imagery from each of those two intermediate images.

Abstract: In a matcher mechanism for verifying a match of a set of subject points having positional parameters against a set of reference points having positional parameters, the improvement of employing a set of Group tables derived from the difference table. Each line entry on the difference table constitutes a lead entry of a separate Group table. The Group table are overlapping subsets of the entries on the difference table. The members of the Group table are limited to only one line entry representing each reference point. That line entry is the one which is closest to the lead entry on the difference plane. In addition, all line entries within a Group are limited to those that are within a predetermined window on the difference plane around the lead line entry for the group. A quality score is determined for each of the Group tables based on a weighted proximity value between each pair of line entries in the Group involved.

Abstract: An input fingerprint image consists of ones and zeros pixels representing light and dark pixels which in turn correspond to ridge and valley formations. This image is compared with a reference file fingerprint to verify the identity of the input fingerprint. The reference file has two relatively small segments which are subfields of the entire field of pixels that constituted the original fingerprint image for the individual involved. Two substantially larger domain subfields are extracted from the input fingerprint image. The center of each segment corresponds to the center of a respective one of the domains. Each segment is scanned over its corresponding domain to determine the position of maximum ones correlation and maximum zeros correlation between each segment and its corresponding domain.

Abstract: In an optical fingerprint image processing apparatus a light beam is scanned across a finger placed against a transparent platen in order to provide a reflected modulated light beam carrying fingerprint information. The modulated light beam is imaged and the image is intercepted by an array of photo receptors that detect the image and convert the optical signal into electrical signals. The improvement is in placing a diffuser element, which may be a ground glass wafer, in the interrogating light beam. The diffusion of the light beam acts as an effective filter to eliminate the higher spatial frequency components of the optical image and thus provide a fingerprint image having improved continuity.

Abstract: A finger pressed against a platen or a fingerprint card provides a fingerprint object which is scanned by an interrogating beam of collimated light that is linearly displaced across the platen thereby maintaining a constant angle between the interrogating light beam and the plane of the object being scanned. As the beam scans across the fingerprint object, the reflected light beam is modulated. The modulated beam is imaged onto a linear array of photo-responsive devices to provide a series of output signals indicative of modulation information. The outputs of the devices are serially interrogated at each of successive scan positions to provide a set of signals containing fingerprint information.

Abstract: A finger pressed against a platen provides a fingerprint object which is scanned by an interrogating beam of collimated light in the form of a slit and that is linearly displaced across the platen. As the slit-beam scans across the back surface of the platen, the reflected light beam is modulated. The modulated beam is imaged onto a linear array of photodiodes to provide a series of output signals indicative of modulation information. The outputs of the diodes are serially interrogated at each of successive scan positions to provide a set of signals containing fingerprint information. The platen has a transparent glass base. A layer of transparent, compressible, resilient epoxy is on the back of the glass base. The epoxy layer has a flat back surface. A thin silver reflecting layer on the back surface of the epoxy provides a flat mirrored surface to reflect the light beam. A further epoxy layer on top of the silver provides mechanical filtering. A lacquer layer at the back protects the platen from wear.

Abstract: A slit beam of coherent light is scanned across a flat finger print or fingerpress to provide a modulated reflected light beam. A Fourier transform of the modulated light beam is projected onto a hologram of a standard character plate. The character plate, from which the hologram is made, contains standardized minutia; specifically, line bifurcations and line endings, that are typical of a finger surface image. Correspondence between one of the minutia being scanned and one of the minutia in the character plate results in correlation of the Fourier transform of the minutia being scanned with the hologram of the corresponding minutia on the character plate to produce a correlation beam. An array of photocells is placed optically downstream from the hologram. Excitation of one of the photocells by one of the correlation light beams serves to identify the minutia being scanned by type of minutia, position of minutia and angular orientation thereof.

Abstract: A fingerpress is formed by pressing a finger against the back surface of a transparent glass plate and holding it in a predetermined position thereon. This fingerpress is interrogated by a light beam directed through the front surface of the glass plate. The interrogating beam is partially reflected at the back surface to provide a signal beam carrying fingerpress information. The signal beam is created by virtue of the optical discontinuity between the glass plate and the fingerpress. There is one discontinuity between the glass plate and the air underlying the valleys of the fingerpress and another discontinuity between the glass plate and the finger oil at the crests of the fingerpress. The two discontinuities cause differing amounts of light to be reflected and the signal beam is thus created. The signal beam is correlated against a hologram of the same fingerpress to provide identification. The hologram is created either from a film image of the fingerpress or from the fingerpress in real time.