Fingerprint acquisition device, system and method

Abstract

The fingerprint acquisition device includes a removable, magnetically attached finger aperture selector to facilitate reconfiguration of the device to image various finger sizes and body regions. The housing and selector of the device are also configured for single hand use as a function of the angle and position of the imaging actuator and selector relative to the device handle. The apparatus includes a camera calibration bracket to facilitate adjustment of camera alignment. Software usable with the device may normalize the fingerprint characteristics as a function of the age and individual characteristics of the imaged subject.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 410,561, filed on September 27, 2022, the entire content of which is incorporated herein by reference. This application is also related to U.S. Patent No. 10,496,870, filed on March 6, 2018, U.S. Patent No. 11,003,883, filed on March 7, 2018, U.S. Patent Application Publication No. 2022 / 0071489, filed on December 20, 2019, and PCT Application No. PCT / US2019 / 068369, filed on December 20, 2019, published as WO / 2020 / 132645A1, the entire content of all of these documents is incorporated herein by reference. Background Art

[0003] The present invention generally relates to fingerprint acquisition, and more particularly to methods and devices for non-contact fingerprint acquisition of newborns, infants, toddlers, children, and adults. Summary of the Invention

[0004] In one embodiment, the fingerprint acquisition device includes a detachable, magnetically attachable finger orifice selector to facilitate reconfiguring the device to image various finger sizes and body regions. The housing and selector of the device are also configured for single-handed use depending on the angles and positions of the imaging actuator and selector relative to the device handle. The device includes a camera calibration bracket to facilitate adjusting camera alignment. Software that can be used with the device can normalize fingerprint characteristics based on the age and individual characteristics of the subject being imaged.

[0005] In one embodiment, a fingerprint input system is provided, comprising: a main housing including an elongate handle (which includes a longitudinal axis) and a rotating hub integrally formed with the elongate handle, the hub including an upper convex surface, an imaging opening in the upper convex surface, and a circular flange surrounding the upper convex surface, the circular flange including an upper wavy surface, a central hub magnet located at the center of the rotating hub, a plurality of peripheral hub magnets equally spaced around the circular flange, and each of the plurality of peripheral hub magnets being located at the same hub radial distance from the center of the rotating hub; an actuator located on the front surface of the elongate handle; an imaging assembly located inside the elongate handle and including an imaging axis; a detachable rotating orifice top configured to form a rotating interface with the rotating hub; the selector including a lower concave surface configured to form a complementary rotating interface with the upper convex surface of the hub; a plurality of finger receiving orifices, each orifice having a different size and including a chamfered peripheral edge located in the plane of the orifice; and a plurality of flanges surrounding the lower concave surface and configured to radially extend outwardly beyond the circular flange of the rotating hub, wherein the plurality of flanges are radially offset from the plurality of finger receiving orifices, and wherein each of the plurality of flanges includes a wavy surface complementary to the wavy surface portion of the circular flange of the rotating hub; and a central top magnet located at the center of the detachable rotating orifice top, wherein the center of the detachable rotating orifice top and the center of the rotating hub define a rotation axis; and a plurality of peripheral top magnets equally spaced around the plurality of flanges, and each of the plurality of peripheral top magnets being located at the same top radial distance from the top center.

[0006] In another embodiment, a fingerprint input system is provided, comprising: a main housing including an elongated handle (which includes a longitudinal axis) and a rotating hub integrally formed with the elongated handle, the hub including a hub interface surface, a center, an imaging opening in the hub surface, and a first plurality of alignment structures equidistantly distributed around the rotating hub, each of the plurality of alignment structures being located at the same hub radial distance from the center of the rotating hub; an actuator located on the elongated handle; an imaging assembly located inside the elongated handle and including an imaging axis; a detachable rotating orifice top configured to form a rotating interface with the rotating hub; the selector including a top interface surface configured to form a complementary rotating interface with the upper convex surface of the hub and including a center, wherein the center of the top and the center of the hub define a rotation axis; a plurality of finger receiving orifices, each orifice having a different size and including a chamfered peripheral edge located in the plane of the orifice; a plurality of flanges surrounding the top interface surface and configured to extend radially outward beyond the rotating hub, wherein the plurality of flanges are offset from the plurality of finger receiving orifices in the radial direction; and a second plurality of alignment structures arranged in a complementary configuration with the first plurality of alignment structures located on the rotating hub. The device may further include an adjustable camera alignment bracket. The adjustable camera alignment bracket may include a frame and three adjustment screws. The frame may include a polygonal shape having four sides and four corners, wherein a first of the three adjustment screws is located in the middle of one of the four sides and the second and third adjustment screws are located at two of the four corners farthest from the first screw. The adjustable camera alignment bracket may be releasably connected to the imaging assembly by a bracket magnet attached to the frame. The imaging assembly may be located in a frame opening of the frame. Three magnets may be embedded in the frame, and the three adjustment screws may be magnetically attached to the magnets. The three adjustment screws may be attached to the main housing. The system may further include a first heat sink thermally coupled to the imaging assembly. The system may further include an illumination assembly having a plurality of light sources located within the main housing. The illumination assembly may include a circular base. The system may further include a light diffuser located above the illumination assembly. The system may further include an illumination heat sink thermally coupled to the lower surface of the illumination assembly. The system may further include a camera support located between the imaging assembly and the adjustable camera alignment bracket. The first plurality of alignment structures and the second plurality of alignment structures may each include magnets. The system may further include a third plurality of alignment structures located on the rotating hub and a fourth plurality of alignment structures complementary to the third plurality of alignment structures and located on the detachable rotating orifice top. The third plurality of alignment structures may include a plurality of alternating wavy or ramp surfaces, and the fourth plurality of alignment structures may include a plurality of alternating wavy or ramp surfaces complementary to the third plurality of alignment structures.The third plurality of alignment structures may be positioned along an upper peripheral circular surface of the rotary hub. The fourth plurality of alignment structures may be located on a lower surface of the plurality of flanges. The system may also include an elongated planar measurement tool that includes a plurality of different apertures arranged in size order along the tool. The measurement tool may also include a plurality of serial number markings corresponding to the plurality of different apertures. The fingerprint device described herein is designed to collect unpressured fingerprints and other body parts within a consistent manner across a wide range of ages and body sizes. The system design addresses many problems associated with collecting fingerprints using traditional contactless devices, primarily mobile phone-based camera biometric systems. For mobile phone-based camera systems, the camera and the finger of the imaging subject are each independently held in free space. The subject places a finger in front of the camera, and the distance between the finger and the camera may vary, thereby changing the image size and the spatial resolution of the finger pixels. Each mobile phone also has a focusing range that must be adhered to in order to obtain a clear image. Before analyzing the fingerprint image and storing it as a fingerprint template, the inconsistent spatial resolution needs to be normalized to a standard 500 pixels per inch to be compatible with other Automated Biometric Identification Systems (ABIS). The finger is also placed in free space in front of the camera; thus the user needs to concern about whether the fingerprint is correctly facing the camera and aligned with it. Additionally, concern also needs to be given to what is visible in the background behind the subject. Bright light and / or a background scene of a similar color may make it difficult to isolate the finger image. Mobile phone fingerprint systems with cameras do not use specific hardware but are software applications that can be hosted on various mobile phone devices. Each mobile phone device manufacturer and model has different total pixel counts, optical resolutions, fields of view, as well as light source power and light source spectral characteristics. All of these variables need to be considered by fingerprint software programs that use mobile phones to collect finger images. Mobile phone-based systems are also designed only for adult use and have not been corrected for infants or children.The current device herein is designed to eliminate or minimize the described problems, including for all ages from infants to adults, and is also an improvement over the early development designs described in U.S. Patent No. 10,496,870, U.S. Patent No. 11,003,883, U.S. Publication No. 2022 / 0071489, PCT Publication No. WO / 2020 / 132645A1, and "Biometric recognition of newborns and infants by non-contact fingerprinting: lessons learned," by Saggese S, Zhao Y, Kalisky T et al., Gates Open Research 2019, 3:1477. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A and 1B are left and right views of an embodiment of a fingerprint acquisition device; Figure 1C and 1D are Figure 1A and 1B are front and rear views of the device in Figure 1E and 1F are Figures 1A to 1D top and bottom views of the device in Figure 1G are Figures 1A to 1F a perspective exploded view of the device in Figure 1H is Figures 1A to 1F a top perspective view of the device in Figure 1I illustrates Figure 1H the usage state of the device shown in Figure 1J schematically depicts the alignment relationship between the top of the rotary orifice and the main housing;

[0008] Figure 2A is a schematic top view of the alignment of the top of the rotary orifice with the magnetic interface; Figure 2B schematically depicts the rotation of the top of the rotary orifice; Figure 2C is Figure 2A a schematic top view of the realignment of the top of the rotary orifice in a position different from Figure 2D and 2E are side elevation views of the device, showing the peripheral interface between the hub and the rotary top, where the rotary top is in a partially seated and fully seated position, respectively;

[0009] Figures 3A to 3CIs a rear perspective view of a fingerprint acquisition device attached to the top of a different rotating orifice;

[0010] Figures 4A to 4D Are respectively a perspective view, a top view, a bottom view, and a side view of an exemplary embodiment of the top of the rotating orifice; Figures 4E to 4H Are respectively a perspective view, a top view, a bottom view, and a side view of another exemplary embodiment of the top of the rotating orifice; Figures 4I to 4L Are respectively a perspective view, a top view, a bottom view, and a side view of yet another exemplary embodiment of the top of the rotating orifice;

[0011] Figure 5A Is a longitudinal cross-sectional view of the main housing showing the optical centerline. Figure 5B Is an orthogonal side view of the longitudinal cross-sectional view of the main housing. Figure 5C Is an orthogonal side view of the longitudinal cross-sectional view of the fully assembled fingerprint acquisition device. Figure 5D Is a perspective view of the main housing showing the alignment of the camera and the orifice.

[0012] Figure 6A Is a perspective view of the fixed optical configuration relative to the top of the rotating orifice. Figure 6B Is Figure 6A A side view of the fixed optical configuration relative to the top of the rotating orifice in . Figure 6C Is Figure 6A And 6B A perspective view of the longitudinal cross-sectional view of the fixed optical configuration relative to the top of the rotating orifice in and . Figure 6D Is Figures 6A to 6C A side view of the longitudinal cross-sectional view of the fixed optical configuration relative to the top of the rotating orifice in .

[0013] Figure 7A Is a perspective exploded view of the imaging configuration. Figure 7B Is Figure 7A A side exploded view of the imaging configuration in . Figure 7C Is a perspective view of the fixed optical configuration. Figure 7D Is Figure 7C A side view of the fixed optical configuration in .

[0014] Figure 8A Shows a perspective view of the camera alignment configuration. Figure 8B Illustrates in perspective the Figure 8A Arrangement of the hidden lines and magnets visible in the camera alignment configuration shown in . Figure 8C Shows Figure 8A And 8B A perspective view and variable alignment angles of the camera alignment configuration shown in and .

[0015] Figure 9A Is a schematic superimposed profile of seven finger orifices. Figure 9BShows a top view of the finger selector guide.

[0016] Figures 10A to 10C Shows a perspective view of the point positions on the top of the rotating orifice. Figures 10D to 10F Shows Figures 10A to 10C The captured image of the orifice and the point in

[0017] Figure 11A Shows the arrangement of all points on the top of the baby's rotating orifice. Figure 11B Shows the arrangement of all points on the top of the adult's rotating orifice. Figure 11C Shows all points superimposed along the bounding box.

[0018] Figures 12A to 12C Shows the boundary line for detecting the orifice size.

[0019] Figures 13A to 13F Shows the finger images captured using different orifice sizes.

[0020] Figure 14A Shows the fingerprint image on the day of birth. Figure 14B Shows the fingerprint image of a 1-year-old child. Figure 14C Shows the fingerprint of an adult. Figure 14D Shows Figure 14A The normalized minutiae map of the fingerprint image on the day of birth in Figure 14E Shows Figure 14B The normalized minutiae map of the fingerprint image of a 1-year-old child in Figure 14F Shows Figure 14C The normalized minutiae map of the adult fingerprint image in

[0021] Figure 15A Shows the relationship data between the little finger size and age. Figure 15B Shows the relationship data between the middle finger size and age.

[0022] Figure 16A Shows the original image of the finger, Figure 16B Shows the binary mask of the orifice used, Figure 16C Shows the finger image after applying the mask to the original image, Figure 16D Shows the magnified finger image to be presented to the user.

[0023] Figure 17A Shows the original finger image with the automatically detected core point shown, Figure 17B Shows five different positions where the user is advised to place the core point during the image acquisition process.

[0024] Figure 18 Is a flowchart of the system operation.

[0025] Figure 19A is a perspective view of another embodiment of a fingerprint acquisition device, where the rotating top is separated from the main housing. Figure 19B is Figure 19A a detailed longitudinal cross-sectional view of the upper region of the fingerprint acquisition device in Figure 19C is Figure 19A an exploded view of exemplary components of the device in Figure 19D is Figure 19A a perspective detailed view of the rotation hub of the main housing and the optical cover in Figure 19E is Figure 19A a perspective cross-sectional view of the main housing in Detailed Description of the Invention

[0026] The device includes a self - contained camera system, which also has a dedicated camera with a fixed - focal - length optical element, an integrated light source, and a fixed optical configuration that positions a subject's finger (or other body part) at a specific location by using an adjustable aperture on which the subject can place their finger. The device 100 is small enough to be operated with one hand. Figures 1A to 1F depicts an exemplary overall design, including an external view of the assembled device 100, which includes a main housing 102, a rotating top 104a configured to select the size of the finger - support apertures 106a - d, a trigger or actuator 108 to initiate image acquisition, and a communication link 110 (such as a USB cable connecting the device to a computer). In some variations, a wireless communication link via Bluetooth or other wireless communication protocols can be provided. Figure 1G shows an exploded view of the device 100, depicting internal and external system components. Figure 1H shows the device in the use position, Figure 1I shows a subject's finger placed on the aperture for image acquisition when the user holds the device.

[0027] In this exemplary embodiment, the main housing 102 can include a two - piece shell 102a, 102b, which are configured to form a complementary fit with each other and define an internal cavity for accommodating a camera assembly 112 with a lens 114, a lighting assembly 116, and a window / diffuser. The two shells 102a, 102b together form a handle region 120 of the housing 102, and one shell 102a includes or the two shells together form a rotation hub 122 to which the rotating top 104a is detachably attached. Additionally, the device can also include a camera bracket assembly 170 (which can be used to adjust the alignment of the camera assembly 112 during manufacturing and / or repair), one or more heat sinks in the camera assembly and / or lighting assembly, additional optical devices such as a camera aperture structure 152 and an aperture support structure 154, an optically transparent window 156, and a window seal to protect the internal contents of the device 100.

[0028] The main housing 102 may include a generally elongated shape having a proximal end 124 (from which a wired communication link or cable 110 may extend), a distal end 126 (where the rotating hub 122 is located), a ventral surface 128 (where the actuator 108 may be located), and a dorsal surface 130. The main housing 102 may also include a grip structure on its outer surface to reduce slippage and improve stability when using the device 100. In this particular embodiment, optionally, a flat palm grip structure 132 is provided on the dorsal surface to increase contact with the user's curved palm when holding, which may reduce twisting or rotation of the device 100 during use.

[0029] As Figure 1E shown, the rotating top 104a includes a generally dome-shaped structure 134a having a plurality of apertures 106a-d spaced about the center of rotation 136a of the top 104a, where each aperture 106a-d has a different size, but the center-to-center spacing of adjacent apertures 106a-d is the same, and where the aperture plane angle of each aperture 106a-d relative to the central axis of rotation passing through the center of rotation 136a of the rotating top 104a is the same. This arrangement allows the user to maintain imaging consistency with the camera assembly regardless of which aperture 106a-d is selected. Markings 138a may be provided on the top 104a to facilitate identification of the aperture size range, subject age, and / or body part associated with each rotating top. To facilitate rotation of the rotating top 104a to select the desired aperture 106a-d, a series of alternating flanges 140a and finger grooves 142a may be provided around the edge or perimeter of the dome structure 143a. The flanges 140a may include a radially outward height of 3 mm to 4 mm, 3 mm to 8 mm, or 2 mm to 10 mm; a circumferential length of 20 mm to 25 mm, 22 mm to 30 mm, or 15 mm to 35 mm; and a longitudinal height of 8 mm to 10 mm, 6 mm to 15 mm, or 5 mm to 15 mm. The grooves may have complementary radially outward heights and longitudinal heights corresponding to the flanges 140a, but the circumferential length may be the same as, smaller than, or larger than the flanges 140a, having a circumferential length of 10 mm to 13 mm, 8 mm to 20 mm, or 11 mm to 15 mm. To facilitate image capture, the middle of each groove 142a may be radially aligned with the center of each aperture 106a-d, except for the grooves 142a (if any) located near the markings 138a.

[0030] The detachable attachment between the hub 122 and the top 104a may be provided by a ball lock or snap-fit bracket, or in this particular embodiment, by providing a plurality of complementary arranged magnets on the hub 122 and the rotating top 104a, as Figure 1JAs shown. The plurality of magnets on the hub 122 may include a central magnet 144 and peripheral magnets 146a - e, which are equidistantly distributed around and at a certain distance from the central magnet 144. As Figure 4C shown, the complementary rotating top magnets include a rotating top central magnet 148 and peripheral magnets 150a - e, which are also equidistantly distributed around and at a certain distance from the rotating top central magnet 148. Placing the magnets around the outer edge of the top not only connects it to the housing but also provides repeatable, discrete rotational positions to align each individual orifice to an exact position within the camera's field of view (FOV). The central magnet pairs 144, 148 located on the axis of rotation (for centering the rotating top 104) act like shoulder screws or shafts to prevent lateral movement of the rotating top 104a. Figure 1J A configuration with five pairs of magnets is shown, with one set on the top (neodymium magnets, 3 / 16 inch in diameter × 3 / 16 inch in thickness, 2.2 pounds of pull force per magnet) and a second set in the main housing (neodymium magnets, 3 / 16 inch in diameter × 1 / 8 inch in thickness, 1.6 pounds of pull force per magnet). The typical pull force strength of the six sets of magnets on the main housing has been tested to reach 5 pounds. Thus, when the magnets are aligned, the top will be firmly locked onto the subject. The top has a diameter of approximately two inches, suitable for the average grip size of an adult hand. The shear strength of the magnet sets between the top and the main housing is less than a value to be determined in pounds. At this force level, the user can rotate the top with the thumb and index finger of the hand holding the device, as Figure 1I shown. The selection of magnet strength makes the top firmly attached but allows the thumb and index finger to easily overcome the shear force to rotate the top to the next position. One function provided by the magnetic configuration is the ability to easily remove the rotating top and replace it with another rotating top of a different size or configuration, enabling a single base device to accommodate various sizes and body parts for scanning. In some further variations, the interface between the rotating top and the rotating hub may selectively include complementary mechanical pawls and protrusions to facilitate alignment (or registration) of the orifice of the rotating top with the imaging orifice of the hub. The pawls can be provided on the hub or the top, and correspondingly, the protrusions are provided on the hub or the top. In other embodiments, complementary central axes and central openings may be provided between the hub and the top to further facilitate alignment between the hub and the top and potentially prevent accidental separation between the hub and the top. In some variations, the axis and opening can be a supplement or alternative to the central magnets of the hub and the top.

[0031] Figures 2A to 2C shows how to adjust the rotating top 104a to access different orifice positions. When all the magnets 146a - e and 150a - e are aligned, the top 104a will be positioned such that one of the orifices (e.g. Figure 2AThe orifice 106b) therein is aligned with the center of the camera's field of view, as indicated by the arrow. The magnets 146a-e, 150a-e are strong enough to hold the top 104a in place, but if a lateral force is applied, the magnetic attachment of the peripheral magnets 146a-e, 150a-e will undergo rotational separation ( Figure 2B ), and allow for easy rotation until the magnets realign themselves and automatically position to the next or nearest alignment position, at which point the user does not need to manually align to the next orifice (e.g., Figure 2C the orifice 106a) shown. However, if the rotation of the top 104a is stopped halfway or partially, resulting in misalignment of the magnet pairs 146a-e, 150a-e, the top 104a can be easily removed and replaced with another top, such as Figure 3B and 3C the tops 104b or 104c shown respectively. Figures 2A to 2C The example in shows five pairs of magnets 146a-e, 150a-e, thus forming five rotational positions. In other embodiments, more or fewer magnet pairs can be provided, resulting in more or fewer rotational positions. The five-position top strikes a balance between maximizing the number of positions and the diameter of the device. The position with the marker 138a can be used as a storage position to prevent debris from contacting the camera orifice or window. As the number of light points increases, the diameter of the top must increase to accommodate the orifice. The diameter of the current design is just right for an adult's gripping diameter. The size of the orifice also affects the required diameter, and only tops with smaller orifices can have more than five positions without increasing the diameter of the device and single-handed usability. If the orifice is small enough to fit, tops with six or seven positions can be used without increasing the diameter.

[0032] To further facilitate the alignment of the rotating top 104a with the hub 122, or otherwise bias the rotating top 104a towards the alignment position between the hub magnets 146a-e and the rotating top magnets 150a-e, the rotating top 104a and the hub 122 can include complementary wavy surfaces or alternating inclined ramp surfaces 160, 162, as Figure 2D and 2E shown, such that when the rotating top 104a is placed on the hub 122, the attraction between the central magnets 144, 148 of the hub 122 and the top 104a will attempt to align the central magnets 144, 148a (as Figure 1J and 4CMinimize the clearance distance between the top 104a as shown) and the top 104a. The wavy or alternating ramp surfaces 160, 162 will bias the top 104a to slide and rotate to minimize the clearance distance, which in turn will rotate the top 104a into a position closer to the peripheral magnets 146a - e of the hub 122a of the peripheral magnets 150a - e, aligning the rotating top 104a perfectly. The wavy surface or alternating ramp surface 160 of the hub 122 can be located on the annular or ring-shaped surface 164 of the central dome 166 surrounding the hub 122, and the peripheral hub magnets 146a - e are located on this surface. The magnets and the wavy surface work together to facilitate the selective alignment of the apertures 106a - e of the top 104a with the imaging aperture 167 of the hub 122. The corresponding wavy surface or alternating ramp surface 162 of the rotating top 104a can be positioned along the lower surface of the flanges 140a - e and / or the lower surface of the rotating top 104a adjacent to the grooves 142a - e.

[0033] The self-alignment of multiple magnets provides the main alignment method for positioning the apertures at the center of the camera's field of view. The main housing and each top are designed such that pairs of magnets are close to each other without touching. This helps reduce the strength of these magnets and allows the user to easily rotate the top to the next position. To provide additional alignment accuracy, the housing and the rotating dial have interlocking features between the top and the housing, further helping to maintain the accuracy and repeatability of the rotational alignment of the top with the main housing.

[0034] When used for neonates and infants, the device size and the magnetic design of the rotating top assist the biometric collector in collecting fingerprints. For an adult-only system, the subject can interact with the device. For an infant, the device must be brought to the subject, and the biometric collector needs to align the subject's finger with one hand and interact with the device with the second hand. This means being able to hold the subject and perform all functions of the device (such as rotating the top to obtain the optimal aperture size for a particular finger without releasing the subject and triggering image collection).

[0035] To be used for fingerprint collectors across a wide range of ages (i.e., neonates, infants, children, and adults), the device needs to be configured to properly support fingers of different sizes. This is achieved by having apertures of different sizes to support various finger sizes. If the aperture is too small, the scanned area will result in insufficient fingerprint minutiae points that cannot be detected for accurate analysis; if the aperture is too large, the finger may fall into the device, not lie flat on the image plane, and will allow external light to enter the sample chamber. When scanning each finger of the subject, an appropriately sized aperture provides: 1) support for the finger, 2) allows the camera to observe the finger unobstructed, 3) positions the finger within the fixed focal length range of the optical system, 4) sets the finger at a known distance with a known optical resolution, and 5) blocks external light sources from reaching the camera.

[0036] Figure 9A is a schematic diagram depicting the outlines of seven orifices 1, 2, 3, 4, 5, 6, and 7, which span the finger size range from newborn to adult, with each orifice located at a common center. Table 1 lists the lengths and widths of the orifices, and the sizes of these orifices are designed proportionally to span from the minimum diameter of a newborn's little finger ( Figure 15A ) to the size of a teenager / adult middle finger when the finger is fully developed ( Figure 15B ). Figure 15A is a data graph depicting the average, 5th percentile, and 95th percentile ranges of the diameter (or width) of a newborn's fifth finger or little finger, which can be as small as 5 mm and will increase to 13 mm at 13 years old. Similarly, Figure 15B shows that according to the anthropometric data disclosed in the "Report on Child Physical Characteristics" (UM-HSRI-BI-75-5, final report, May 31, 1975) by the University of Michigan Highway Safety Research Institute, within the same age range, the size of the width of the third finger or middle finger ranges from 6 mm to 15 mm.

[0037] Table 1:

[0038] Orifice Length (mm) Width (mm) #1 7.4 5.5 #2 9.35 7 #3 11.4 8.5 #4 13.5 10 #5 15.7 12.25 #6 17.85 13.4 #7 20.3 15.25

[0039] These sizes are chosen to span this range in seven steps, but any other sizes or combinations of sizes can be used for specific applications. A scale 900, which may include cardboard or a rigid polymer, can be provided, having orifices 902a-g arranged in series and corresponding markings 904a-g to facilitate determination of the size of the orifice required for a specific subject's finger, where the selected orifice 902a-g should be able to support the maximum finger width without allowing the finger to pass through the orifice 902a-g. The diameters of these orifices 902a-g correspond respectively to the widths 5.5 mm, 7 mm, 8.5 mm, 10 mm, 12.25 mm, 13.4 mm, and 15.25 mm listed in the table above. In other variants, the orifice widths can span a range of 5 to 16 mm, 4 to 18 mm, or 3 to 20 mm, and 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 orifices can be used for setting. Although the exemplary markings 904a-g in the scale 900 include numbers, letters or other symbols can also be used and can correspond to the markings adjacent to each orifice 106a-I on the rotary tops 104a-c or the rotary top markings 138a-c.

[0040] Figures 3A to 3CShows three different examples where the device 100 is configured or set with a series of rotating tops 104a-c, which are configured with a series of different orifice sizes for a specific application. Among the orifice groups set in these tops 104a-c, the size of each orifice is different, but in other variants, the size ranges may overlap between different tops. Figure 3A Shows the top 104a mounted on the device 100, which is intended for newborns and children, and includes orifices #1, #2, #3, and #4 in Table 1, as well as a closed position marked by the label 138a. This top 104a is also shown in Figure 4A , 4B , 4G and 4J. Figure 3B Shows the top 104b mounted on the device 100, which is intended for teenagers and adults, and includes orifices #4, #5, #6, and #7 in Table 1, as well as a closed position marked by the label 138b. This top 104b is also shown in Figure 4C , 4D , 4H and 4K.

[0041] Figure 3C Shows an optional top 104c, which is configured to correctly position the subject's hand to scan the palm pad directly under the fingers. In this top 104c, the "fin" structure 168 on the top is located at the top edge of the field of view of the orifice 106i, so that the interdigital folds (i.e., webbing) between two fingers can be placed against both sides of this structure 168 to align the hand and image the palm pad. In this top design 104c, the orifice is fully open, so as to image the largest possible area of the finger pad. An inclined, wider flange 140k can be set near the orifice 106i to further support the subject's hand or palm during image acquisition. This top 104c is also shown in Figure 4E , 4F , 4I and 4L. The inner edges of the orifices 106a-h can be sharp, angled, or can include rounded edges. It is assumed that the rounded edges can reduce the light and shadow near the contact between the imaging finger and the inner edge of the orifice 106a-h by allowing more direct or indirect light at the inner edge.

[0042] The positions of the detailed feature points on the finger are in an area, and its shape is very similar to Figure 9A the shape of the orifices 1 to 7 shown in, and these orifices include a generally oval or egg-shaped shape, with a smaller distal end and a larger base. The shapes of the orifices 106a-h on the tops 104a, 104b can be configured to keep the most detailed feature points exposed while also supporting the finger. A rectangular orifice cannot support the finger well because the fingertip is usually smaller than the knuckle area. The three-dimensional shape of the orifice simulates the circular shape of the finger, so that the finger is supported by an edge that fits the finger surface. Figures 4A to 4D andFigures 4G to 4K It is shown that the shapes of the apertures 106a - h mimic finger shapes, including generally oval or ovoid shapes with a smaller distal end and a larger base, and the dimensions are as shown in Table 1. Each aperture 106a - h is configured at a certain distance from the camera, which generally places the middle of the aperture and thus the finger (the center being from the fingerprint to the nail) at the desired focus. Since finger shapes and sizes vary, this is a general guideline and the actual finger position will differ. The device can image over a wide depth range and is capable of maintaining good focus in the range from 10 mm below the aperture to above the aperture to keep the fingerprint in focus.

[0043] The main housing 102 has various features that simplify manufacturing and ensure stable and consistent optical alignment between the camera and finger placement among different devices. The main housing 102 may include a main housing body 102a and a housing cover 102b, where the main housing body 102a can be a single part that is printed, cast, or machined, and contains relatively more alignment and retention features compared to the housing cover 102b. Using a single part as the main housing body 102a allows for more precise control of dimensions compared to using multiple parts for different functions, thus providing higher precision and repeatability when placing internal components and achieving the required camera alignment.

[0044] As Figures 5A to 5D shown, the main housing body 102a includes features for supporting the optical components, which include a camera assembly 112 with an integrated lens, a camera bracket 170, an LED printed circuit board (PCB) 116 with an optical diffuser, aligning all these components along the optical centerline 500 and through the imaging aperture 167 of the rotating hub 122 and the attached rotating top 104b. The main housing 102 may also have features to block scattered LED light from reaching the camera, and it also blocks any external light source from leaking into the device through other apertures on the top. These features include light - blocking inner walls and light - absorbing or diffusing coatings. The rotating hub 122 has a concave circular chamber 172 below the hub 122, which helps to equalize the light for diffused illumination.

[0045] By fixing all the optical components and the position of the finger, the optical resolution, field of view, light source intensity, and spectral composition are all kept consistent or have reduced variations, and the finger can be kept at the position of the desired focus for each image acquisition. Additionally, when the finger is placed on the aperture, the design of the present disclosure can reduce external light sources that may block the finger and may maintain the consistency of the (non - finger) background part of the image. The result of using all these features is higher - quality and higher - contrast images. Figures 6A to 6D is a view of the sub - assembly 600, where the exemplary top 104b shows the alignment of various optical components 112, 114, 116, 118, and each position is set by the main housing body 102a.Figures 7A to 7D An additional view is shown in which a pinhole aperture structure 700 and a pinhole aperture support 702 are added on top of the standard f / 3 lens 114 to increase the f / # to f / 10, so that the depth of field of the camera assembly 112 can be increased, so that even if the finger is bent and different parts of the finger are at different distances from the camera assembly 112, a clear image of the finger surface can be obtained.

[0046] For the camera assembly 112, the main housing 102a provides high-precision x-y-z alignment that is accurate enough that only small alignment adjustments are required. However, variations in the camera assembly 112 may benefit from finer angular alignment. For example, the relative positions of the camera chip, lens mount, lens, aperture, and camera mount are not always exactly the same for each camera assembly 112, which may cause the center of the camera FOV to vary between each camera / optical component. To correct this, slight angular alignment and / or Z-axis translation adjustments can be made to each camera assembly to improve alignment and / or depth-of-field position.

[0047] Due to space constraints, it may be difficult to finely align and fix the position of the camera assembly in a small handheld device. In some examples, a three-point magnetic motion camera mount and alignment assembly 170, as shown ​ is provided to allow adjustment of the camera assembly 112 so that the lens aperture is at the center of the field of view and to permanently fix the camera pointing angle to maintain alignment. Motion mounts are typically designed for components that need to be repeatedly disassembled and replaced with high positional and angular repeatability requirements. For the devices of the present disclosure, the camera assembly may only need to be aligned once and then firmly held in alignment for long-term use. The alignment assembly 170 includes three adjustable magnetic screws 802a-c that are attached to corresponding internal locations within the main housing, the heads 804a-c of which will insert into the retention cavities 806a-c of the alignment frame 808 and be magnetically fixed. The overall alignment of the camera assembly 112 can be achieved through standard alignment features and structures built into the device housing. By adjusting the height of the three screws to change the camera pointing angle, the field of view (FOV) of the camera can be finely adjusted onto the hub and the orifice of the rotating top. ​ Shows the camera assembly 112 located in the alignment frame 808 of the camera mount assembly 170 and the three screws 802a-c for aligning the angle of the camera assembly 112 relative to the device housing. ​ In the configuration shown, the camera mount 170 includes three magnets 810a-c, as ​ shown, arranged in a triangle around the camera central axis within the frame 808, where each magnet 810a-c is located at the bottom of the cavity 806a-c. After being installed in place, the screws 802a-c will be magnetically attracted to the magnets 810a-c, and the angular position of the camera 112 is set by the depth of the screws 802a-c. As​ As shown, adjustment screws 802a-c will change the pointing angle of camera assembly 112. Adjustment screw 802a can modify the y-axis rotation and / or adjustment of screws 802b-c along one side of frame 808 can modify the x-axis rotation. Thus, during the alignment process, screws 802a-c can be adjusted to change the pointing angle to align the center of the FOV with the center of the hub and the orifice of the rotating top. This configuration does not require translation because the initial alignment based on the main housing features is sufficient and only fine-tuning is needed. However, in other variants, translation along the Z-axis can be achieved by adjusting all three screws 802a-c. This can improve the depth-of-field placement along the Z-axis, thereby improving image focus, and fix the range of the field of view (FOV) to obtain a constant image resolution.

[0048] ​ Another embodiment of fingerprint acquisition device 1900 is depicted, which also includes an optional optically transparent window structure or cover 1902 along the optical path or centerline 500 of camera assembly 112. Other components of device 1900 can be arranged and configured in a manner similar to that of device 100 in ​ , such as the aforementioned camera assembly 112 and actuator 108, wired communication link or cable 110, lens, optical PCB 116, light diffuser, camera aperture, aperture support 154, and action camera bracket and alignment assembly 170, etc.

[0049] As ​ and 19C shown, optical cover 1902 can be attached to rotating hub 1912 through groove 1906. However, in other embodiments, the cover can be attached to the main housing rather than the rotating hub through an annular or circumferential groove of the housing. Groove 1906 can be provided on an annular or circumferential flange or support 1908 of hub 1912 to place cover 1902 higher for easy cleaning. As ​ shown, groove 1906 or support 1908 does not have to have the same angular orientation as the rotation plane of hub 1912. For example, cover 1902 can be partially above and / or below the rotation plane of hub 1912, as ​ shown. This difference may help reduce reflection artifacts from light sources and / or ambient light during use. Cover 1902 can help protect camera assembly 112 from dust or other contaminants, which may help maintain long-term image quality. Cover 1902 can include a polymer material such as polycarbonate or glass. Cover 1902 can be adhered to the groove or form a mechanical fit with groove 1906, and a rubber or other polymer seal can be provided between cover 1902 and groove 1906 to enhance the sealing and / or retention force of cover 1902 with housing 1904a / b.

[0050] The cover 1902 can be configured to have light filtering characteristics for various wavelength ranges and / or polarities. The cover 1902 may include one or more coatings on the outer surface and / or the inner surface, such as hydrophobic and / or oleophobic coatings, to make the cover waterproof and / or fingerprint-resistant, and / or scratch-resistant, and / or anti-reflective, thereby minimizing glare and / or ghosting. The cover 1902 may include a substantially planar material, but in other variations, the cover 1902 may have a concave and / or convex surface to provide magnification and / or other lens characteristics. The lens characteristics may supplement or replace any lens provided in the camera assembly 112. In ​ In the illustrated embodiment, the cover 1902 includes a planar material with a central or average thickness of 8 millimeters, made of standard glass. In other variations, based on the type of material and its strength, the cover 1902 may have a central or average thickness in the range of 1 millimeter to 10 millimeters, 1 millimeter to 8 millimeters, or 2 millimeters to 6 millimeters. The diameter of the cover may be 30 millimeters, or the diameter may be in the range of 5 millimeters to 50 millimeters, 10 millimeters to 40 millimeters, or 25 millimeters to 35 millimeters. The surface area of the cover may be 700 square millimeters, but in other variations, the surface area may be in the range of 700 square millimeters to 900 square millimeters, 600 square millimeters to 800 square millimeters, or 650 square millimeters to 750 square millimeters.

[0051] In ​ In the illustrated exemplary embodiment, the cover 1902 may be oriented at an angle of 11 degrees relative to the optical centerline 500 of the camera assembly 112. In other variations, the direction angle (orientation angle) of the cover relative to the optical centerline 500 of the camera assembly 112 may be in the range of 0 degrees to 45 degrees, 5 degrees to 30 degrees, or 10 degrees to 15 degrees. The direction angle of the cover relative to the plane of the rotary hub 1912 may be -30 degrees, but in other variations, for example, it may be in the range of -45 degrees to +0 degrees, -40 degrees to -15 degrees, -35 degrees to -25 degrees, -30 degrees to +5 degrees, or -15 degrees to +0 degrees.

[0052] Another optional feature of the fingerprint collection device 1900 is that the rotary hub 1912 may not have ​ the central dome 166 of the rotary hub 122 as shown in ​ and thus may not have the central magnet 144. Instead, ​ the rotary hub 1912 of the device 1900 in ​(similar to those in). Although there is no central dome, the rotating hub 1912 may still include an annular peripheral flange 1916 (on which the rotating top 1914 is located), and an inner protruding flange 1918 received by the inner cavity of the rotating top 1914. As shown, due to the orientation angle of the cover 1902, the inner protruding flange 1918 may have a variable or non-uniform protruding height. Since the rotating hub 1912 does not have a central dome, the rotating top does not need to have a central dome-shaped structure 1922, but may alternatively include, for example, a flat-end cylindrical shape, a frustum shape, or a polygonal cross-sectional shape.

[0053] Magnetic attachment also allows for easy removal of the camera assembly to adjust the three screws 802a-c and for easy replacement to check alignment. Once aligned, the magnetic attraction between the magnets 810a-c of the camera mount 170 and the base screws 802a-c will maintain the alignment of the camera over a long period without fixing the camera assembly 112 in any other way. This magnetic mount 170 also allows the camera assembly 112 to be repeatedly removed for maintenance and then reinserted without further alignment.

[0054] Fine alignment of movement is very useful for correctly aligning the rotating top to the camera field of view. This alignment can facilitate any top fixed to the main housing hub to correctly align the center of the field of view with the in-place orifice.

[0055] Precise alignment of the camera relative to the orifice helps to correctly detect the orifice selected and placed in the field of view by the user, and by providing a repeatable physical alignment, the imaging processing requirements for correcting imaging variations can be reduced. To reduce complexity, the rotating top may not have any position sensors to detect the position of the orifice, and instead, the camera can be used to detect the position of the orifice in real time. In some variants, image processing can be used to detect the orifice in the camera field of view and can be used to identify the current orifice in place. The size and other image features can also be used to normalize or calibrate the camera assembly and images on a per-image and / or per-subject basis. To indicate which orifice has been selected, different markings or marking positions can be provided on the inner surface of the rotating top to facilitate identification of the orifice located in the camera field of view. Such markings can also be used to normalize or calibrate the camera assembly and images on a per-image and / or per-subject basis. In some variants, a white dot can be placed at the unique position of each orifice and can be easily and quickly identified through image analysis. Return reference ​ Schematic diagram, the positions of the points 906a-h on the left correspond to orifices 1 to 7 respectively. In this exemplary embodiment, the points 906a-h are all vertically aligned but located at different positions, which can simplify detection and also help to confirm the alignment of the corresponding orifices 1 to 7. There are eight unique orifices in the current configuration, including one for the closed position. More (or fewer) orifices and points can be used, and different regions of the camera field of view can be utilized.

[0056] ​ depicts an exemplary top 1000a-c, where each orifice 1002a-c or closed position has a hole or cavity 1004a-c at a unique position of the rotating top 1000a-c so that in ​ the resulting images 1006a-c of the field of view, corresponding points 1008a-c are formed along the vertical edges 1010a-c (or other positions) of the corresponding images 1006a-c. In this particular example, the holes 1004a-c are filled with white silicone to form white "dots" that can be optically detected. Other methods can also be used, such as dotting on the surface, the top can be a 3D print of multiple colors, or physical pins can be placed to produce a detectable pattern. ​ shows current configuration images of three different orifices 1012a-c. Using an image processing algorithm that detects points, the algorithm is effective within the dashed regions 1014a-c of the images 1006a-c, so detection only occurs when the magnet is engaged and the top is in place. ​ depicts ​ the point detection regions 1100a-e of the selected orifices of the rotating top 104a shown. Each of the five vertical images 1100a-e shows the points 1102a-e detected by the image processing algorithm for each orifice 106a-e and closed position, and is indicated by placing detection boxes 1104a-e around them. The position along the vertical axis of the images 1100a-e determines the selected orifice. The black horizontal lines 1106a-h represent the expected potential positions of the points used for detection. The rightmost image 1100f shows all the points 1102a-e and boxes 1104a-e of this top superimposed on a single image to show that they are separate and distinguishable from each other. ​ shows ​ the imaging data of the top 104b shown, which has different combinations of orifices 106e-h and corresponding point positions, thus generating images 1100f-j with points and boxes 1102a / c / f / i / j and 1102b / c / f / i / j. In this particular embodiment, the smaller orifices on the top 104b are the same size as the largest orifice on the top 104a, so they share the same point positions, as do their closed positions. Images 1100k depict all the points and boxes 1102a / c / f / i / j, 1104b / c / f / i / j respectively. ​Shows all the points and detection positions of the eight positions of the two sets of tops 104a, 104b, including three unique apertures on the smaller top 104a, corresponding to point 1102e at position 1106c, point 102d at position 1106d, and point 1102b at position 1106f; three unique apertures on the larger top 104b, corresponding to point 1102f at position 1106h, point 1102i at position 1106b, point 1102j at position 1106a; and the same aperture 1102a at position 1106g, which is the largest aperture on top 104a and the smallest aperture on top 104b; and the closed positions on each of the tops 104a and 104b, which have the same point 1102c at position 1106e. In use, the user can place either of the tops 104a or 104b on the device 100, and the device will detect whether the apertures 106a - h are in place. The point positions of the closed positions of each different top can be the same or different, so that even in the closed position, it can be detected that the top is attached to the device.

[0057] In addition to identifying the rotational positions and apertures of the tops, the optical detection of points is used in a variety of ways to support the user in collecting fingerprints. One use of point detection is to indicate that the device is ready for collection. Once points are detected in the search box, the software control system will enable the ability to acquire an image by pressing a trigger on the device or through software, thus minimizing the acquisition of incorrect images when the apertures are not properly positioned.

[0058] Another aspect of identifying the aperture positions is that the generated image can be cropped using a binary mask specifically designed for a particular aperture. This requires much less computational power compared to other image analysis and correction algorithms. During collection, a specific aperture mask is used to remove the non - finger background and speed up processing by reducing the number of image pixels. If points are accurately detected in the correct position, the position of the binary mask is fixed. If necessary, the coordinates of the points can be detected, and when the aperture is slightly misaligned, the mask can be translated and / or scaled. ​ Shows such an example. ​ Shows the original image 1600 of a finger 1602 located in aperture 1604, which contains marked points 1606; ​ Shows the binary mask 1608 for this aperture 1604; ​ Illustrates applying the mask 1608 to ​ the original image 1600 to obtain the resulting image 1610 of the finger 1602.

[0059] Another optional feature for identifying the orifice location is to facilitate consistent magnification or "zooming" to the maximum size of the orifice. This can be helpful when scanning the smallest neonatal fingers, as features and alignment need to be visually inspected on a computer screen. The predetermined fixed limits corresponding to each orifice on the display screen and the images acquired therefrom can be presented to the user in a standard size, and the finger can be magnified according to the detected orifice. ​ Shows a magnified or enlarged image 1612 of finger 1602 as it would be presented to the user on the display screen.

[0060] Identifying the orifice size selected by the user also helps to determine the finger size. If the finger size is initially determined, image processing can adjust the age adjustment calculation to obtain faster results.

[0061] Identifying that the orifice is not in its expected position when one or more imaging expected features are absent or not detected also allows the software to reduce calculations by not performing certain unnecessary functions. For example, the automatic exposure function only occurs when the orifice is in place.

[0062] Other markers can also be used to display the size and current position of the orifice. Among them, vertical lines 1204a-c and 1206a-c can be printed or formed on the bottom surface of the rotating top. These vertical lines can be optically detected and used to determine which orifice is within the field of view (FOV) of the camera. It may be simpler to detect the vertical lines 1204a-c, 1206a-c through imaging processing, and the distance between the vertical lines 1204a-c, 1206a-c can be used to determine the orifice size or the corresponding orifices 1202a-c. Other top configurations not based on the rotating design can also be used to adjust the size of the orifice. A movable orifice can be used, where one side of the orifice is fixed and the other side can be moved to adjust the size of the opening. In this case, lines and / or points can be optically detected to determine the size of the orifice in real time. Examples of various movable orifices are described in U.S. Patent 10,496,870 and U.S. Patent 11,003,883. Each orifice can also use a different bar code or QR code and be detected by the camera.

[0063] ​Shows an overview of the system operation and software architecture 1800. Specifically, the flowchart shows the process of collecting an image of a single finger 1800, and this process can be repeated for each finger as needed by the operator. As shown in the figure, during the collection process, the raw image is streamed 1802, and other processes only start when an orifice point is detected 1804. Once the point is detected, other processes are initiated, such as exposure control 1806 and trigger activation 1808. Once the trigger for collection is detected 1810, the image is acquired 1812, processed to the desired image resolution (in pixels per inch (PPI)), quality processed, and displayed back to the user. This process includes applying a mask 1814, contrast enhancement 1816, and pixel / ridge line analysis 1818. If the required PPI level is provided 1820, the image is converted to the desired PPI 1822. Then fingerprint analysis is performed on the converted image 1824, and various features and scores 1826 (such as binary image quality scores and the number of minutiae points) are generated and displayed along with the processed image and / or the raw image 1828. A second trigger press 1830 will restart the process.

[0064] For infants and small children, the biometric collector needs to physically place and align the finger onto the device without the assistance of the subject. Since assistance is needed for the subject, it is helpful if the device can be operated with one hand, freeing the second hand to place and properly align the subject's finger onto the device.

[0065] The device is also symmetrically designed so that right-handed and left-handed users can operate it in the same way. Specific designs can be made to make it easier to operate with one hand specifically, such that the external features of the device are specifically molded for use with one hand or the other. Having dedicated left- and right-handed devices may be more comfortable for the user.

[0066] One feature of the device's operation is its ability to acquire fingerprint images across a wide range of ages and finger sizes. Industrial standard fingerprint devices are not used for collecting images of children for several reasons: 1) The optical resolution of standard fingerprint collectors is not detailed enough to detect smaller ridge features, and 2) Children grow over time, and fingerprint images will be inconsistent and change over time.

[0067] The ridge features of children's fingerprints are very small. The image resolution of standard fingerprint collector devices is 500 pixels per inch (PPI), and some newer models have been upgraded to 1000 PPI. This resolution is sufficient to image the ridges of adult fingerprints.

[0068] Whether the adult image is acquired at 500 PPI or 1000 PPI, the standard fingerprint processing algorithm requires the image to have a resolution of 500 PPI because the image processing algorithms are trained on images at this resolution and most fingerprints in the fingerprint database are scanned and saved at this resolution.

[0069] For adults, the distance between fingerprint ridges on an adult finger is approximately 400 - 500 microns. Thus, for 500 PPI, with a sampling distance of 50 microns, 8 - 10 pixels will be placed between adjacent ridges. On the other hand, children have the same number of ridges. Although a child's fingerprint is fully formed, the ridges are distributed on a smaller finger that changes with age, so the ridges are closer together. In the smallest newborns, the distance between ridges may be only 125 microns, and a 500 PPI imager sampling at only 2 - 4 pixels cannot adequately distinguish adjacent ridges. Additionally, the image processing algorithms used in standard fingerprint devices expect 8 - 10 pixels between ridges, so the image processing algorithms used to detect and enhance ridge contrast will not work properly, thus incorrectly evaluating the child's image. Moreover, as a child grows, the positions of the minutiae points on the fingerprint change over time, and a newborn's fingerprint changes so much that it cannot be matched to the fingerprint of an older child.

[0070] The design of the device addresses these issues by using a high - resolution imager and an image processing algorithm that can correct for size changes during a child's growth. To have 10 pixels between an infant's ridges, the image size of a single pixel on the image plane needs to be approximately 12.5 microns, which corresponds to an image resolution of approximately 2000 PPI. Current device resolution exceeds 3000 PPI to ensure that the fine details of a child's finger can be resolved.

[0071] Since the age and size of fingers vary from person to person and change over time, the image processing performed here normalizes all images to a constant number of pixels between each fingerprint ridge. The image processing algorithm is used to evaluate the average distance between the ridges of each finger, then the image is resampled to place 8 - 10 pixels between the ridges and create an image with a 500 PPI "adult - equivalent" image that can be evaluated by a standard fingerprint biometric image enhancement system. All different finger sizes are resampled to have the same number of pixels between the ridges, regardless of the original size of the finger.

[0072] For example, ​ depicts images of fingers of different subjects of different ages and sizes. ​ is an infant finger with approximately 20 pixels between each ridge of the fingerprint. ​ is an infant with approximately 24 pixels between each ridge of the fingerprint. ​There are 28, 32, and 36 pixels respectively between each ridge line. ​ is the finger of an adult with 40 pixels between each ridge line.

[0073] The size difference can be addressed by generating a high-resolution fingerprint image and downsampling it to a standard 500PPI equivalent image, thereby normalizing the fingerprint to a single size. ​ shows an image of a baby finger, ​ is an image of the finger of a 1-year-old child, ​ is an image of an adult finger, and each image is shown in its appropriate relative size with respect to each other. To evaluate such images with significantly different sizes, the fingerprints are normalized to a standard 500PPI image, where there are 8 - 10 pixels between each fingerprint ridge line. ​ , 14E and the processed images in 14F respectively show the results of this processing for a newborn, a 1-year-old child, and an adult. In ​ , all finger sizes have been normalized to a consistent resolution. After normalization, the fingers of various sizes are resampled, and regardless of the starting age, the resulting minutiae maps may be of the same size.

[0074] The minutiae position map will expand as the child grows, and researchers have developed mathematical models that can be used to correct for age (and size) differences during a child's growth. If the first fingerprint is collected when the child is 1 year old and the second fingerprint is collected when the child is 6 years old, these models can be used to attempt to infer or "grow" the early fingerprint minutiae template by 5 years to attempt to match the later image. The growth factor is typically the average of a set of child data. This averaging can be problematic because children grow at different rates or have different sizes at any given age.

[0075] Some exemplary image processing methods directly measure the ridge distance of each finger of a child or infer the ridge density in real time. Some existing algorithms may use the average distance based on the child's age or age range to correct the image. However, in some embodiments of fingerprint acquisition herein, the size of that particular finger of the child is measured and resampled to a consistent 500PPI "adult equivalent size". This is done for the same child or person regardless of the image, and each image will reach the same nominal pixel / ridge value according to the image attributes (rather than the reported age of the child), i.e., 8 - 10 pixels per ridge line, as shown in FIG. 11. In this method, all finger images will reach a known pixel / ridge value regardless of the child's age or size, thereby eliminating the problems associated with assuming the child is of average size. This can be done on a per-image basis, or it can be calculated once for each subject and then reapplied to each subsequent image, repeating the PPI normalization process.

[0076] On a standard contact fingerprint acquisition device, a finger can be placed on a platen and rolled to acquire data of the entire finger surface, which is commonly referred to as "nail-to-nail" (N2N). For non-contact devices, it may not be possible or easy to perform this operation using a single camera, but in some variants, multiple images of the finger can be acquired from multiple angles by instructing the subject and / or user to rotate the finger appropriately. Then, multiple images can be stitched together to create an N2N composite image. This can be achieved through a standard aperture or an N2N custom aperture, which can assist the user in aligning and rotating the finger to acquire image data.

[0077] To assist the user in acquiring the highest quality images, the device can provide feedback during the acquisition process to guide the user on various image features and the adequacy of the acquired images. One exemplary method is to utilize one or more minutiae detection algorithms to mark the image to show the user the location of the fingerprint minutiae. For non-contact imaging, the curvature of the finger is a variable that can make registration and matching difficult or challenging. Some data shows that matching performance may be assisted when the fingerprint minutiae of the fingerprint image and the verification fingerprint image are closely aligned. One way to ensure this is to always acquire images centered on the minutiae and / or instruct the user to acquire multiple pictures with the minutiae located at other well-defined positions. In some variants of the system, the standard acquisition procedure guides the user to acquire multiple positions by tracking the location of the minutiae and provides feedback showing when the desired images have been acquired. This can be achieved by providing an image overlay with fiducial marks that the user needs to align the minutiae of the subject's finger with. Once an image that meets the desired minutiae location has been acquired, the fiducial marks can be changed to indicate that the location image has been acquired and the user can move on to the next location. ​ Shows an original image of a finger, where the automatically detected minutiae 1700 are shown by the box 1702, and ​ Shows a set of five potential positions 1704 that suggest to the user where to position the minutiae during image acquisition.

[0078] Another implementable exemplary and alternative quality feedback process involves detecting the pressure exerted by a finger on the device. When the user and subject place a finger on the orifice, during some image acquisition processes, it is preferable to have the finger gently touch the orifice. If the finger presses too hard on the device, the finger may be pushed into the orifice, causing skin stretching. When the skin stretches, the ridge lines and valley lines become less distinct, and the contrast between the two decreases. This makes it more difficult to analyze the ridge endings and bifurcations (i.e., minutiae points) in the image. The image processing algorithm can provide pressure feedback in a variety of ways. One is through image processing, looking for an increase in blood pooling at the center of the finger based on the color or relative color change of pixels, or the brightness or relative brightness change of pixels. As the finger pressure increases, blood flow is restricted, a blood pool forms at the center of the finger, and the blood around the finger / orifice contact point decreases. This can be optically detected by evaluating the contrast of the finger image. Other methods can also be used to directly detect blood through spectral analysis, similar to the method used in a pulse oximeter, but detecting this pressure effect through the finger image. By observing the contrast of the image in real time, excessive pressure can be inferred. When the contrast (between the ridge lines and valley lines of the fingerprint) decreases significantly, we can provide feedback to the user, suggesting to reduce the pressure applied to the device.

[0079] Some of the variations described herein relate to computer storage products having a non-transitory computer-readable medium (also referred to as a non-transitory processor-readable medium) having instructions or computer code thereon for performing various computer-implemented operations. The computer-readable medium (or processor-readable medium) is non-transitory, meaning that it does not itself include transitory (instantaneous) propagated signals (e.g., propagated electromagnetic waves carrying information in a transmission medium such as space or a cable). The medium and the computer code (also referred to as code or algorithm) can be designed and constructed for a particular purpose or purposes. Examples of non-transitory computer-readable media include, but are not limited to: magnetic storage media such as hard disks, floppy disks, and magnetic tapes; optical storage media such as optical discs / digital video discs (CD / DVD); compact disc read-only memory (CD-ROM) and holographic devices; magneto-optical storage media such as optical discs; solid-state storage devices such as solid-state drives (SSD) and solid-state hybrid hard drives (SSHD); carrier signal processing modules; and hardware devices specifically configured to store and execute program code such as application-specific integrated circuits (ASIC), programmable logic devices (PLD), read-only memory (ROM), and random access memory (RAM) devices. Other variations described herein relate to computer program products, which may, for example, include the instructions and / or computer code disclosed herein.

[0080] The systems, devices, and / or methods described herein can be implemented by software (executed on hardware), hardware, or a combination thereof. Hardware modules can include, for example, a general-purpose processor (or microprocessor or microcontroller), a field-programmable gate array (FPGA), and / or an application-specific integrated circuit (ASIC). Software modules (executed on hardware) can be expressed in a variety of software languages (e.g., computer code), including C, C++, Python, Ruby, VISUAL and / or other object-oriented, procedural, or other programming languages and development tools. Examples of computer code include, but are not limited to, microcode or microinstructions, machine instructions (e.g., instructions generated by a compiler), code for generating web services, and files containing high-level instructions executed by a computer using an interpreter. Other examples of computer code include, but are not limited to, control signals, encrypted code, and compressed code.

[0081] In some variations, these systems and methods can communicate with other computing devices (not shown) via, for example, one or more networks, where each network can be any type of network (e.g., a wired network, a wireless network). A wireless network can refer to any type of digital network that is not connected by any cables. Examples of wireless communication in a wireless network include, but are not limited to, cellular communication, radio communication, satellite communication, and microwave communication. However, a wireless network can be connected to a wired network in order to interface with the Internet, other carrier voice and data networks, commercial networks, and personal networks. Wired networks typically transmit via copper twisted-pair, coaxial cable, and / or fiber optic cable. There are many different types of wired networks, including wide area networks (WANs), metropolitan area networks (MANs), local area networks (LANs), Internet area networks (IANs), campus area networks (CANs), wireless personal area networks (PANs) (e.g., Bluetooth, Bluetooth Low Energy), global area networks (GANs) (e.g., the Internet), and virtual private networks (VPNs). The networks referred to hereinafter refer to any combination of wireless, wired, public, and private data networks that are typically interconnected via the Internet to provide a unified network and information access system.

[0082] Cellular communication can include technologies such as GSM, PCS, CDMA, or GPRS, W-CDMA, EDGE, or CDMA2000, LTE, WiMAX, and 5G network standards. Some wireless network deployments combine networks from multiple cellular networks, or use a mix of cellular, Wi-Fi, and satellite communication. In some variations, the systems, devices, and methods described herein may include radio frequency receivers, transmitters, and / or optical (e.g., infrared) receivers and transmitters to communicate with one or more devices and / or networks.

[0083] Although the various embodiments have been specifically shown and described above in connection with their examples, those skilled in the art should understand that various changes in form and detail can be made therein without departing from the scope of the embodiments. For all of the above embodiments, the method steps need not be performed in order.

Claims

1. A fingerprint input system, characterized in that, Comprising: A main housing, the main housing comprising: A slender handle, the slender handle comprising a longitudinal axis; and A rotary hub integrally formed with the slender handle, the hub comprising: An upwardly convex surface; An imaging opening in the upwardly convex surface; and A circular flange surrounding the upwardly convex surface, the circular flange comprising an upper undulating surface; A plurality of peripheral hub magnets equidistantly distributed around the circular flange, each of the plurality of hub magnets being located at the same hub radial distance from the center of the rotary hub; An actuator located on the front surface of the slender handle; An imaging assembly located inside the slender handle and comprising an imaging axis; A detachable rotary orifice top configured to form a rotary interface with the rotary hub, the selector comprising: A downwardly concave surface configured to form a complementary rotary interface with the upwardly convex surface of the hub; A plurality of finger receiving orifices, each orifice having a different size and comprising a chamfered peripheral edge located in the plane of the orifice; and A plurality of flanges surrounding the downwardly concave surface and configured to extend radially outwardly beyond the circular flange of the rotary hub, wherein the plurality of flanges are offset from the plurality of finger receiving orifices in the radial direction, and wherein each of the plurality of flanges comprises an undulating surface complementary to the undulating surface portion of the circular flange of the rotary hub; A plurality of peripheral top magnets equidistantly distributed around the plurality of flanges, and each of the plurality of peripheral top magnets being located at the same top radial distance from the center of the top; and An optically transparent cover located between the imaging assembly and the detachable rotary top.

2. The system according to claim 1, wherein The optically transparent cover is oriented at an offset angle of ** degrees to ** degrees relative to the imaging axis.

3. The system according to claim 2, wherein The optically transparent cover is oriented at an offset angle relative to the plane of the circular flange of the rotary hub.

4. The system according to claim 2, wherein The rotary hub further comprises a central hub magnet located at its center, and a central top magnet located at the center of the detachable rotary orifice top, wherein the center of the detachable rotary orifice top and the center of the rotary hub define a rotation axis.

5. A fingerprint input system, characterized in that, Comprising: A main housing, the main housing comprising: A slender handle, the slender handle comprising a longitudinal axis; and A rotary hub integrally formed with the slender handle, the hub comprising: A hub interface surface; A center; An imaging opening in the hub surface; and A first plurality of alignment structures equidistantly distributed around the rotary hub, each of the plurality of alignment structures being located at the same hub radial distance from the center of the rotary hub; An actuator located on the slender handle; An imaging assembly located inside the slender handle and comprising an imaging axis; A detachable rotary orifice top configured to form a rotary interface with the rotary hub, the selector comprising: A top interface surface configured to form a complementary rotary interface with the upwardly convex surface of the hub and comprising a center, wherein the center of the top and the center of the hub define a rotation axis; A plurality of finger receiving apertures, each aperture having a different size and including a chamfered peripheral edge lying in the plane of the aperture; A plurality of flanges that surround the top interface surface and are configured to extend radially outward beyond the rotary hub, wherein the plurality of flanges are staggered with respect to the plurality of finger receiving apertures in the radial direction; and A second plurality of alignment structures arranged in a complementary configuration with the first plurality of alignment structures located on the rotary hub.

6. The system according to claim 5, wherein The device further includes an adjustable camera alignment bracket.

7. The system according to claim 6, wherein The adjustable camera alignment bracket includes a frame and three adjustment screws.

8. The system according to claim 7, wherein The frame includes a polygonal shape having four sides and four corners, wherein a first one of the three adjustment screws is located at the middle of one of the four sides and the second and third adjustment screws are located at two of the four corners that are farthest from the first screw.

9. The system according to claim 7, wherein The adjustable camera alignment bracket can be releasably connected to the imaging assembly by a bracket magnet attached to the frame.

10. The system according to claim 7, wherein The imaging assembly is located within a frame opening of the frame.

11. The system according to claim 7, wherein Three magnets are embedded in the frame, and the three adjustment screws are magnetically attachable to the magnets.

12. The system according to claim 11, wherein The three adjustment screws are attached to the main housing.

13. The system according to claim 5, characterized in that A first heat sink thermally coupled to the imaging assembly is further included.

14. The system according to claim 5, wherein A lighting assembly having a plurality of light sources within the main housing is further included.

15. The system according to claim 14, wherein The lighting assembly includes a circular base.

16. The system according to claim 14, wherein A light diffuser located above the lighting assembly is further included.

17. The system according to claim 14, wherein A lighting heat sink thermally coupled to the lower surface of the lighting assembly is further included.

18. The system according to claim 6, wherein A camera support located between the imaging assembly and the adjustable camera alignment bracket is further included.

19. The system according to claim 6, characterized in that, Both the first plurality of alignment structures and the second plurality of alignment structures include magnets.

20. The system according to claim 19, wherein A third plurality of alignment structures located on the rotary hub and a fourth plurality of alignment structures complementary to the third plurality of alignment structures and located on the top of the detachable rotary aperture are further included.

21. The system according to claim 20, wherein The third plurality of alignment structures includes a plurality of alternating wavy or ramp surfaces, and the fourth plurality of alignment structures includes a plurality of alternating wavy or ramp surfaces complementary to the third plurality of alignment structures.

22. The system according to claim 21, characterized in that, The third plurality of alignment structures is positioned along the upper peripheral circular surface of the rotary hub.

23. The system according to claim 21 or 22, characterized in that, The fourth plurality of alignment structures is located on the lower surface of the plurality of flanges.

24. The system according to claim 5, wherein An elongated planar measuring tool is further included, which includes a plurality of different apertures arranged in dimensional order along the tool.

25. The system according to claim 24, wherein The measuring tool further includes a plurality of serial number markings corresponding to the plurality of different apertures.

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