HK1114219B - Finger guide device - Google Patents

Description

Finger guide device

Technical Field

The present invention relates generally to a finger guide, referred to as a finger guide device, for positioning a finger, thumb or human finger containing unique minutiae on a scanner or sensor or other device to capture an image of the minutiae or minute features of the relevant portion of subcutaneous tissue, which is also equivalently referred to as a fingerprint. Such finger guide devices may be used with electronic, optical, electromagnetic, capacitive, electroluminescent or similar scanners or sensors that require repeated and suitably precise positioning to align the scanner or sensor. Applications include accurate authentication or identification of individuals with minimal number of false rejects or iterations of the process for scanning or reading the enrolled portion of the fingerprint.

Background

U.S. patent application No.2004101172(Lane) discloses a finger imaging system for a recipient's finger that acquires its fingerprint using an automated fingerprint reader. The system includes a finger imaging device having a finger receiving portion for receiving a finger of an acquired fingerprint. The locator bar extends outwardly from the finger receiving surface and engages a skin fold of the subject finger when the finger is approximately in the desired position. Us patent application 2004101171(Lane et al) discloses a finger imaging system for receiving and holding a human finger, the fingerprint of which is acquired with an automatic fingerprint reader. The system includes a finger imaging device having a finger receiving portion and a finger positioning portion that together form a reduced size recess so that a subject finger forcibly inserted therein is held in a stable position. And finally, U.S. patent application No.2004076314(Cheng) discloses an apparatus that includes a fingerprint sensor and a guide device. The sensing portion of the fingerprint sensor forms an opposite and obtuse angle with the guide plane of the guide means.

Traditionally, to record a fingerprint, ink is applied to a finger and then the finger is "rolled" across a paper or other ink receiving surface to print a fingerprint image. Fingerprints left by contacting the surface and leaving residual oil are captured by various techniques, which "lift" and reveal the fingerprint.

In recent years, alternative techniques have been proposed that can reveal fine features in a fingerprint and capture the fingerprint directly from the finger. Electronic sensing techniques include holding a finger on a sensing system while the system detects skin or living tissue differences through the finger area or just a relevant portion of the finger area to reveal an image of the fingerprint or to form an electronic representation of the fingerprint, for example as a digital file. Examples include, but are not limited to, optical scanners, electroluminescent pressure sensing systems, integrated circuits capable of measuring capacitance across individual pixels, and the like.

The cost of production of some types of fingerprint scanning systems is driven by the size of the finger area being sensed. This is particularly true for silicon-based or Integrated Circuit (IC) type sensors. Like most ICs, the larger the IC, the higher its production cost if the device geometry and number of layers are equal. The production cost of the sensor is directly related to the sensing area, and mass production of the sensor, the size of the thumb is not optimal when only the relevant portion of the fingerprint needs to be scanned to create a fingerprint authentication system. If only a portion of the fingerprint is used to reduce system cost, it is important that for each authentication or identification event, a portion be placed on the sensor that is substantially identical to the relevant portion of the finger that was originally enrolled.

Obviously smaller sensors are less costly and, given that the relevant area of the sensed fingerprint must still be large enough to provide an acceptable matching capability or security level, the best solution would be such smaller sensors, not considering the unwanted part of the entire fingerprint area. The finger guide device of the present invention is one that can be used to reliably reposition the finger on a small sensor for more efficient identification. The device reduces false rejects caused by not positioning the finger sufficiently close to the location or locations at which it was initially enrolled so that the sensor can read the relevant portion of the fingerprint match. The finger guide device reduces the occurrence of false rejects by naturally, intuitively, and non-forcibly guiding a subject finger to approximately the same and initial enrollment position each time the fingerprint identification system is used.

When using smaller sensors, if a finger is enrolled in such a way that a relevant area of the finger, or possibly multiple overlapping relevant portions of the fingerprint, is scanned and then electronically assembled by a computer into a complete "template" representing an area of the original subject's fingerprint that is larger than any individual scan can alone produce, then the system relies on the subject's individual or user being able to consistently touch the sensor in the same approximate location so that the relevant portions of the fingerprint are read by the sensor to be able to be matched and thus authenticated or identified. Failure to precisely reposition the finger on the fingerprint sensor or scanner results in false rejects; or in other words, because the sensor sees a different area of the fingerprint, it cannot match a previously enrolled fingerprint area or portion, and because of the non-match, it rejects known subjects. This is a false rejection. The known subject is accepted (identified or "authenticated") if the system makes additional attempts, and if a second or subsequent attempt finally aligns the minutiae containing the relevant portion of the fingerprint that was originally stored with the scanner or sensor during enrollment. By providing a simple funnel-like or inverted cone-shaped guide for the finger that, in effect, non-forcibly urges the finger into the correct position so that the relevant part of the finger is aligned with the sensor or scanner, and providing the subject user with various tactile and other feedback means so that it is easier to "find" the correct position again, the finger guide device reduces the average number of attempts to authenticate a known subject even though a long time has passed between enrollment and the next authentication event. If the finger is in the correct position, but the contact pressure is too high or too low, the scanner or sensor may capture a distorted image and this may also cause false rejects. The finger guide device also assists the user in learning and repeating the correct contact pressure using a variety of feedback devices including, but not limited to, tactile feedback, mechanical motion feedback, audio and visual feedback, the fields of possible feedback devices being known to those skilled in the art of human factors engineering. In contrast, with basic flat surface sensors or even poorly designed sensors, the false rejection rate may range from ten to twenty percent of all subjects for untrained subjects. A system using the finger guide device will have less than ten percent false rejects and a fingerprint authentication system using the finger guide device can be optimized to achieve even lower false reject rates.

Disclosure of Invention

Much like a round or rectangular funnel directs fluid into a container; the finger guide device includes a finger recess for guiding a finger in a repeatable manner towards the same location on the sensor. Another simple analogy is to describe a ball located on the apex of the cone, which is unstable compared to a ball in an inverted cone, where the ball always rolls to the same global minimum position by the natural force action of gravity and the guiding action of the side walls of the inverted cone recess. In the case of the finger guide device, a similar action is initiated by muscles which exert a force to move the finger into the finger guide device recess towards the sensor area, this movement being guided by the disclosed and described physically shaped recess elements in the finger guide device invention. The guiding action of the mechanical recess and the overall performance of the finger guide device may be further enhanced by tactile or other feedback communication with the body, such as feedback caused by tactile properties of the finger guide material or surface, additional physical shape elements intended to cause tactile feedback, mechanical movement, or other visual or audible feedback means. The sensor will sit in the correct position and adjacent to the ideal area of the finger in alignment with the finger guide device to "see" the preferred portion (bulge) of the fingerprint.

Previous devices for positioning a finger for fingerprint imaging focused on the requirement to hold (nearly squeeze and flatten) the finger onto a flat scanning surface and tended to roughly position the finger from the leading edge of the nail or skin wrinkles located under the first joint in the finger. This intent is intended to replace the effect of rolling a fingerprint and the pressure used to flatten the finger is an important element. Modern semiconductors or sensors require only light contact and, as observed, often focus on repeatedly scanning or capturing the same relevant portion of the fingerprint. There is a need for a device that reduces the average number of attempts to authenticate a known subject by providing a simple circular, oval, rectangular or square funnel-like recess or guide for the finger that actually urges the finger into the correct position relative to the scanner or sensor, and that can be further improved by providing various tactile, mechanical movement, audio or visual feedback means for the subject user so that it more easily and naturally "finds" the correct finger position again, even if a long time has passed between enrollment and the next authentication attempt. In contrast, with basic flat surface sensors or even poorly designed sensors, this false rejection rate ranges from ten to fifteen percent of all attempts for untrained subjects.

The finger guide device of the present invention provides an effective aid that helps position the finger in substantially the same location on a repeatable basis, as well as a learning mechanism to help the subject user obtain the correct position and contact (pressure), and through a set of basic design and construction elements including physical shape, material properties, and surface finish properties. Additional feedback devices may also be used to facilitate the effect of the finger guide device.

In practice, the preferred embodiment of the finger guide device of the present invention is designed to reposition the relevant portion of the finger between 0.20 and 0.90 inches from the underside of the fingernail of the alignment sensor or scanner, and thus from the tip of the finger rather than the ridge below the first joint in the finger. In addition, the top edge of the finger guide device at the front has a low enough profile to avoid contacting the fingernail. This contact will introduce errors because the subject trims their nails to different lengths and most will also find the pressure on the nail tip uncomfortable, both of which are present in previous devices that purport to be used to locate a finger on a fingerprint reader or scanner.

The physical design of the finger guide device enables a finger to be placed on the sensor with sufficient accuracy to significantly increase the percentage of first time acceptance (of enrolled subjects), which results are equivalent to reducing the percentage of false rejects. The preferred embodiment includes a relatively short concave radius (or relatively steep slope) at the front of the finger guide device where the tip of the finger just below the fingernail contacts or is near the front of the finger guide device; and a longer radius concave shape (or less steep slope) adjacent the opposite side of the sensor where the guide extends along the finger toward the body. The side portion opposite the scanner or sensor is very steep to keep the finger centered laterally. In general, the finger guide device is sized for a typical finger, yet accommodates a wide range of finger sizes, as it only contacts the finger or a small curved portion of the finger, including the relevant portion of the finger.

The tolerances allowed for placing a finger on a small electronic sensor mounted on a flat surface are quite forgiving, however positioning a finger on these devices is difficult for untrained subjects. The relevant portion of the fingerprint may be limited to approximately half to two thirds of the fingerprint area to be scanned, depending on the algorithm used and the accuracy of the system, which must overlap the relevant portions of the fingerprint previously scanned (enrolled) and present in the matching template. The low precision system may operate such that even less than half of the sensor windows overlap. The actual relevant part for the security matching requirement depends on the algorithm and, in the algorithm, the security level or security setting actually required. This relates to the relevant portion of the fingerprint of the scanned subject that is associated with the enrolled template for that subject.

The ability to place substantially identical portions of a fingerprint on the active area (window) of the sensor on a consistent and repeatable basis facilitates quick and accurate matching and significantly reduces false rejection rates. In enrolled but unskilled subjects, the finger guide device of the present invention reduces false rejects to less than ten percent. Practice using the finger guide device or system optimization or a combination of both will further reduce the false rejection rate.

On average, a reduction in false rejection rate of about 15% to less than 10% is significant in terms of security system acceptance and market acceptance. Frustration in the user population is significantly reduced if one does not need to touch the sensor multiple times and is therefore accepted. In the end of 2003, a new keyboard was introduced to approximately 250,000 users and did not have an effective finger guide solution. There is considerable frustration in the user base and the companies that deploy the system face severe criticism. This problem causes the user to question the performance of the system even if the problem is technically perceived as a mistake or user error in the user's inaccurate finger placement during the authentication process. The finger guide device reduces such anticipated user error and increases the likelihood that the subject is accepted in the first contact. This saves a lot of time over the lifetime of the system and is a key element for developing biometric systems that can be consistently compared to passwords or passwords in terms of user time and efficiency.

Using the finger guide device of the present invention for enrollment and authentication improves the efficacy of the finger guide device. This is because the natural feel of the finger guide device non-forcibly and ergonomically guides the user to approximately the same position or aligns the relevant part of the finger with the active sensor area each time. This guidance process is physical and neutral, providing tactile feedback for first use and subsequent learning. During enrollment, the system may require the subject to touch and remove the finger multiple times. The finger guide device is basically designed to accommodate the fingers, thumb or any digit of the left or right limb. This means that it facilitates such placement but does not strictly limit such placement to accurate and repeatable placement; instead, it only allows such placement to be within the tolerance of the sensor and fingerprint template matching algorithm. This allows the template to exceed the strict limits of an ideal or "fit" window frame (protrusion) and thus form a template with a guard band designed to accommodate future misalignments within the tolerance and alignment capabilities of the finger guide device. This functionality is important for long-term, repeatable performance, and the alignment capability facilitated by the finger guide device need only be raised to the limits required by the matching system, template size, and algorithm safety level. In a fine-tuning (optimized) system, the false rejection rate of experienced user subjects can be reduced to less than two percent with the finger guide device of the present invention.

Some sensors drive potentials into the finger tissue. This may be a radio frequency or RF electromagnetic signal. The finger guide device may be electrically conductive to facilitate such use during enrollment and subsequent authentication events. In this case, the conductive material properties and mechanical design elements of the finger guide device may help "illuminate" the subject finger tissue with the necessary RF signals generated by the sensor and passed through or reflected by the finger guide device or its smooth and conductive surface. The substantially parabolic shaped elements of one preferred embodiment of the finger guide device of the present invention emit and reflect such electromagnetic radiation into the relevant finger tissue and assist the sensor in image data capture of the relevant portion of the fingerprint. The flat sloping conductive side will also cause the relevant area of the fingerprint to be illuminated.

The mechanical surface properties and materials selected for the finger guide device are important to performance. Because the finger should slide easily into place, a low coefficient of friction (either the sliding coefficient or the static coefficient or both) is useful to allow the finger to rest at its natural local minimum, which is at the bottom of the finger guide device properly positioned on the scanner or sensor. This surface characteristic and the un-forced guiding process constantly position the finger in the same proximity location, with relevant portions of the fingerprint captured thereby reducing false rejection rates and reducing the need to additionally touch the sensor. Examples of materials having such low coefficients of friction include, but are not limited to, smooth metals, smooth plastics, and even painted, polished, or waxed surfaces. Lubricants may also be used. If the surface material has a high coefficient of friction (e.g., rubber, polyurethane-based material, or rough plastic), the utility and function of the finger guide device may be reduced or impaired because the finger cannot slide into place as easily.

Other feedback elements may be included in various additional preferred embodiments of the present invention. One will create the ability to feel the correct position. The finger guide device may be made of a material having a high thermal conductivity. Examples include, but are not limited to, metals, metal plated surfaces, certain ceramics, or certain carbon based materials. In this case, the finger guide device will feel cooler to contact at room temperature, not due to its absolute temperature, but because it has a thermal conductivity that quickly conducts heat away from the finger when contacted. If the finger guide device is made of metal, this characteristic will make it feel like a metal touch (e.g., a cold feel). By feeling colder than the rest of the component and colder than the sensor, the subject will perceive the correct "feel" of the finger guide device and will also better feel the sensor to determine its position.

Additional projections may be added to help orient the fingers or to cause the subject to "fine tune" their finger position. These may not be necessary for normal or average sized fingers, but are valuable in applications where the body has very small fingers that contact very little of the finger guide device surface area.

Braille may be added to the finger guide device to facilitate blind or visually impaired users.

The finger guide device may also use physical elements and material properties to prevent inaccurate use. For example, one preferred method of practicing the present invention surrounds the finger guide device with a relatively hard and distinct ridge. Rather than being a "sharp" object that is perceived as dangerous, such ridges are intended to provide discomfort to the user. When a finger is placed on this ridge, although harmless, it is uncomfortable because it applies high Pressure (PSI) to the skin over a narrow area. This high pressure per square inch signal indicates through contact sensing (tactile feedback) that the finger guide device is not being used properly. The feel of the misaligned finger is an unnatural feel and the user will instinctively reposition his or her finger to achieve a more natural and comfortable feel in the recess of the finger guide device. The natural tendency is to avoid placing a finger on the uncomfortable outer ridge of the finger guide, but to slide the finger or thumb down into the finger guide and onto the sensor (the desired location). It is in this correct position that the finger or thumb placement feel is natural and safe for the subject user.

Additional embodiments of the present invention may include feedback mechanisms, including feedback designed to alert (and train) subjects as to the correct positioning of their fingers or to alert subjects to the fact that they have been accepted in the system (i.e., their fingerprints have been scanned, compared and correctly matched). The sound may be used to "guide" the finger to the sensor. Visual indicators may also be used. Examples include, but are not limited to, icons, fingerprint drawing marks, fiducial marks, light sources (e.g., LEDs), and colored circles. Finally, a physical mechanical motion feedback mechanism such as vibration or "click" feedback can be used in a manner very similar to stick-type vibrators that alert the pilot of stall warnings when flying an aircraft or keys present in keyboards and control panels, all such feedback methods being known to those skilled in the art of human factors engineering and incorporated herein by reference rather than by detailed description.

These feedback mechanisms may also be used to correct for misuse of the system. For example, extreme pressure on the sensor or lack of contact pressure may cause scanning problems. Too high a pressure can flatten the detail and saturate the sensor and make it unable to accurately resolve the detail. Conversely, a lack of pressure in the form of too light a contact may cause the details to be indistinguishable by the sensor and not produce a good image. In either case, voice commands or sound or vibration or other feedback means may be used to communicate the need to relax the grip or even to squeeze more strongly. The feedback means may communicate to the subject a desire to relax the contact pressure or to lift the finger slightly. The use of a click feedback device requires the user to apply the minimum acceptable pressure required by the scanner or sensor to "see" the relevant part of the finger. Another possibility is to move the sensor up and down slightly in the finger guide device sensor window to accommodate differences in finger pressure on the scanner or sensor.

A preferred method of implementing the invention is to assemble the sensor and finger guide device designed to work together as a unit, i.e. a system. This requires that the sensor be constructed to operate on a circuit board that likewise contains additional supporting circuitry for its application. The combination of the finger guide device, sensor, sealing gasket and printed wiring board with connector may or may not be placed in its own housing. Thus, the subassembly can be placed in a variety of devices for its application. The unit is a secure platform with multiple uses. Examples include, but are not limited to, vehicle doors or dashboards, countertops, doors or door frames, keyboards, personal digital assistants, telephone devices, secure facsimile machines, computing devices, appliances, tools, machine controllers, medical devices, cash registers, and more.

Fingerprint sensors or scanners use various schemes to sense and capture image data detailing the unique personal characteristics of the fingerprint minutiae or live minutiae tissue directly beneath the fingerprint. In this discussion, and throughout this document, the use of the words finger and fingerprint refers to any finger of the left or right appendage and its unique minutiae, and is equivalent to using the word thumb or thumb fingerprint. The words his or her use are not gender-limiting and are equivalent to her or her use.

The finger guide device of the present invention may be used as a means to provide input from a user to the system. This embodiment of the invention would include mechanically communicating the finger guide device with one or more pressure sensors or capacitive sensors to sense when the finger guide device is touched or pressed. When the device is touched, it may be used as an input or switch control device and when the device is pressed in one or more directions and with different pressure or surface contact motions, it may be used as part of an input device for various input applications, including but not limited to controlling machinery or equipment or as a pointing device for a computer. Placing a finger in the finger guide device and applying pressure in the axial or lateral direction or a combination of directions will allow a second practical use of the finger guide device as a pointing device when the finger guide device is in communication with a pressure sensor or switch. Changing or moving the contact location with the sides of the recess also facilitates practical application of the finger guide device as a pointer or control device if the surface contains sensors to detect such changes, said contact sensor devices being known to those skilled in the art of producing contact sensing pointing and control devices and being incorporated herein by reference rather than being fully described.

The user may be stressed during use of the finger guide device of the present invention; for example, a crime may be underway in which the user is at the muzzle and is forced to sign. In such a situation, it is desirable for the user to have a different finger registered as an emergency signal to indicate that the device user is in danger, which is not necessarily known to others. If the user is experiencing another emergency or is even illegally forced to use the device, he can use the "911" finger to ask for help. In this case, the system cannot match the enrolled fingerprint, but it will recognize the match with the user's emergency finger and therefore recognize its requirements and make a different and corresponding response.

For a fuller understanding of the finger guide device of the present invention, reference is made to the following detailed description and accompanying drawings, in which the presently preferred embodiments of the invention are shown by way of example. As the present invention may be embodied in many forms without departing from the spirit of the essential characteristics thereof, it is expressly understood that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. Throughout the description, like reference numerals refer to like parts throughout the several views.

Brief description of the drawings

FIG. 1 discloses a preferred embodiment of the finger guide device of the present invention mounted in alignment with a fingerprint sensor and mounted in a commonly used biometric contact pad similar to that commonly used in computers for identifying and authenticating users of systems;

FIG. 2 is an assembled view of the preferred embodiment of the finger guide device of FIG. 1 including the finger guide device, a fingerprint sensor with a gasket aligned with the drive ring, and a printed circuit board;

FIG. 3A discloses a top view of the preferred embodiment of the finger guide device of FIG. 1 with a finger placed thereon, the finger positioned on the finger guide device and the relevant portion of the finger aligned with the fingerprint sensor such that the relevant partial fingerprint matches the matching template; and FIG. 3B discloses a side view of a steep forward slope of the finger guide device that aligns the finger in an axial direction to align a relevant portion of the finger with the sensor;

FIGS. 4A and 4B disclose another preferred embodiment of the finger guide device of the present invention mounted in a grip portion of a handheld computer such that the fingerprint sensor is continuously contacted and aligned while holding the handheld computer and, accordingly, the authentication or identification process is continuously or frequently repeated; and the number of the first and second groups,

FIG. 5 illustrates another preferred embodiment of a finger guide device having a flat side surface forming a recess for receiving a finger to position it in alignment in a fingerprint sensor and mounted in a computer display such that a user contacts the finger guide device and aligns a relevant portion of the finger with the sensor for identification and authentication to obtain data to be displayed on the computer display; and, when used to control a computer pointer, placing a finger in the finger guide device to apply pressure or contact movement in an axial or lateral or combined direction to use the finger guide device as a pointing control device; and, if necessary, scans or senses the relevant portion of the fingerprint to continuously or frequently repeat the authentication or identification.

Detailed Description

Fingerprint scanners or sensors are used in a variety of applications to capture image data about a fingerprint for comparison with one or more stored fingerprint images or fingerprint templates. The device comprising the fingerprint sensor may be designed for capturing only the relevant part of the fingerprint or the fingerprint sensor device may be included as part of a device having other further purposes, such as a keyboard or a door lock or other device. The finger guide device of the present invention is intended for use in all such devices and applications where a fingerprint scanner or sensor is required.

Referring now to the drawings, in FIG. 1, a preferred embodiment of the finger guide device 12 of the present invention is shown aligned with the fingerprint sensor 16, with both the finger guide device and the fingerprint sensor being located in a simple touch pad 26 housing that sits against a table, countertop, or other surface. This simple fingerprint pad configuration of the preferred embodiment is typically used in a computer or terminal or payment register to identify a subject for authorization to obtain data, file or network communications or to identify a subject for another purpose; such as completing a payment transaction. The touch pad in combination with a computer and fingerprint matching software algorithm is a fingerprint identification system. The finger guide device reduces the number of false rejects experienced during repeated use of the fingerprint identification system.

Figure 2 discloses an exploded view of a preferred embodiment of the finger guide device 12 of the present invention including the finger guide device 12, the washer 14, the sensor 16 and drive ring 17, and the printed circuit board 18. The left and right sides of the finger guide device near the sensor area are steeper than the front (lower in fig. 2) and rear (upper in fig. 2) and have a concave feature in this embodiment. The front of the finger guide device is concave from the sensor alignment portion to the top ridge and has a shape derived from a set of short radii to form its substantially concave profile. The fingertip will contact this front portion of the finger guide device (see figure 3B below). This feature also helps maintain a secure grip for certain handheld devices, including but not limited to handheld computers (see fig. 4A and 4B) or remote controls. The posterior radius forms the least steep concave profile and serves to guide the portion of the finger or digit between the relevant portion of the finger and the rest of the finger near the body. The end of the finger guide device furthest from the fingernail contains a continuous relatively sharp feedback ridge but is not intended to use the finger joint or the fold of skin under the joint as a means for locating the fingerprint adjacent to the sensor. Rather, such relatively sharp ridges provide tactile feedback to the user to convey information that the finger is improperly placed and needs to be repositioned in the finger guide device recess.

The sides of the finger guide device form a recess for receiving a user's finger and guiding the finger laterally to center the relevant portion of the fingerprint on the fingerprint sensor 16 and drive ring 17. Accordingly, the side of the finger guide device has the same basic shape as the finger. In a first preferred embodiment of the finger guide device 12 of the present invention, the sides are concave with varying radii of curvature. This includes a relatively short concave radius (or relatively steep slope) at the front of the finger guide device where the tip of the finger just below the nail contacts or is near the front of the finger guide device, and a longer radius concave shape (or less steep slope) adjacent the opposite side of the sensor where the guide extends over the finger toward the body. The side opposite the sensor portion is very steep to keep the finger centered laterally. In summary, the finger guide device is sized for a typical finger, but is adaptable to a wide range of finger sizes because it only contacts the finger or a small curved portion of the finger. In a second preferred embodiment of the invention (see fig. 5), the finger guide device has a plurality of flat sides, the opposing sides having equal slopes while still practicing the invention in the second preferred embodiment.

The first preferred embodiment of the present invention (figure 2) of the finger guide device 12 contains a window for the sensor 16 and drive ring 17 to align and expose it to the relevant fingerprint portion of the subject finger or digit. Both the AES3400 sensor or the AES3500 sensor, both produced by AuthenTec corporation of melbourne, florida, may be equally suitable for use as a fingerprint sensor to sit in alignment with the finger guide device, as may other similar devices made by various different manufacturers known to those skilled in the art of fingerprint identification and authentication systems. This window may be sufficient for housing the drive ring 17 required for the particular type of sensor (shown) or it may cover the drive ring and replace the conductivity provided by the drive ring with its own conductivity. In the preferred embodiment, this may also be the case, and its performance is equivalent, the only significant difference being aesthetics. In FIG. 1, the drive ring is equally exposed and the finger guide device 12 is used as a supplement to the drive ring and is conductive and reflective of electromagnetic energy. This feature is desirable but not necessary for the function of the finger guide device. Thus, in yet another preferred embodiment, the finger guide device is non-conductive, yet the electrical signal provided by the drive ring is sufficient by itself to illuminate the relevant minutiae portion of the fingerprint, wherein the function of the assembly is sufficient but not necessarily optimal.

The surface of the fingerprint sensor 16 lies on a plane and the top of the window is at the bottom of the finger guide device 12; however, meeting this plane is not critical to performance within reasonable limits, so long as the subject finger is able to contact the finger guide device and the exemplary fingerprint sensor. The compliant nature of the live finger facilitates this and, while practical from the best match of vertical position (plane), the present invention works over a range of vertical positions. In some cases, performance may be further improved by adjusting the fingerprint sensor plane up or down to change the fingerprint image characteristics. A further preferred embodiment, not shown, allows the relative mounting plane of the finger guide device or fingerprint sensor to be changed by adjustment during the authentication contact to optimize the distance between the sensor and the relevant part of the minutiae tissue of the finger or the contact pressure between the fingerprint sensor and the relevant part of the finger to obtain the best image or fingerprint data that can be achieved. This adjustment can be made manually or automatically using an electronic control system.

In the preferred embodiment of the invention shown in fig. 2, a gasket 14 (or equivalent protective means) is provided to keep oil, fluid, dirt or other undesirable material away from the sensor lens and circuit board. The gasket is made of a flexible material that is impervious to solvents and other undesirable contaminants. In another preferred embodiment, not shown, the gasket and its function may be replaced by a conformal coating applied in liquid form, which cures or partially cures to form a protective barrier, or an equivalent sealing material known to those skilled in the art of electronic device design and assembly and incorporated by reference and which does not affect the function and purpose of the invention. The invention may not include a sealing gasket or equivalent seal or means to form a protective barrier.

The finger guide device 12 of the present invention shown in FIG. 2 contains one or more mounting projections which are shown as opposing and adjacent in the preferred embodiment. These projections are used to align the finger guide device with the sensor and its printed circuit board or other mounting device and to mount the sub-assembly of the fingerprint sensor, gasket and finger guide device to a housing, countertop, appliance housing or other device or system housing. The present invention works with any mounting means known to those skilled in the art of mechanical assembly and alignment of mounting components, and all such means are incorporated herein by reference. Examples include, but are not limited to, adhesive mounting, welding, soldering, pinning, fastening, clamping, hooking or locking.

The front portion of the finger guide device 12 serves as a stop and position reference that is designed to contact the fingertip or thumb below the nail and avoid positional discrepancies that may result from differences in the length of the subject user's finger or thumb nail. This is a significant advantage over devices that clip on or through the top (fingernail) side of the finger.

FIG. 3A discloses a top view of a preferred embodiment of the finger guide device 12 with a finger placed thereon, the finger being positioned onto the finger guide device so that the relevant portion of the finger is aligned with the fingerprint sensor 16 to enable an accurate match of the relevant portion of the fingerprint; and figure 3B discloses a side view of a steep forward slope 27 of the finger guide device 12 that aligns the finger in an axial position to align the relevant part of the finger with the sensor and thus enable an accurate match of the relevant partial fingerprint part. The top edge of the finger guide device is lower than the extension of the long fingernail so that the fingernail will not contact the finger guide device. This feature avoids the possibility of misalignment due to differences in fingernail length that may occur between enrollment and subsequent use of the finger guide device, either due to normal fingernail growth or trimming of the fingernail during the time between enrollment and use of the finger guide device.

Figures 4A and 4B disclose another preferred embodiment of the finger guide device 12A of the present invention that is mounted in the grip of a handheld computer 22 to enable continuous contact with the fingerprint sensor and, correspondingly, continuous authentication or identification. Some devices may be made more secure by requiring continuous or frequent repetition of user authentication. This avoids the potential safety hazard of having authorized personnel touch the finger guide device and fingerprint sensor to enter the system or open the device and then transfer or release the device to an unauthorized user in a security breach known as a "back door". The formation of a back door may be avoided by mounting the finger guide device 12A with flat side surfaces, each pair of opposing sides having substantially equal slopes, and the combination of sides forming a recess for non-forcible receipt of a finger for placing the finger in alignment over a fingerprint sensor in a handheld computer 22 in a manner consistent with normal holding and retention of the handheld device, as shown in fig. 4A and 4B, thereby enabling continuous and frequent authentication to be conveniently achieved without changing the grip on the device or deviating from other data entry behaviors during repeated authentication by the user.

FIG. 5 illustrates and discloses another preferred embodiment of the finger guide device 12A wherein the finger guide device 12A has flat side surfaces, each pair of opposing side surfaces having a substantially equal slope, and the combination of the side surfaces forms a recess for non-forcibly receiving a finger to place it in alignment over the fingerprint sensor 16; and, in this application example of FIG. 5, is mounted in the housing of a computer display such that the user contacts the finger guide device 12 and aligns the relevant portion of the finger with the sensor in a suitably repeatable position for identification and authentication to obtain data to be displayed on the computer display; and is also used to control the computer pointer by applying additional pressure to the finger guide device 12A, the pressure being communicated to one or more pressure sensing devices in mechanical communication with the finger guide device. Another similar preferred embodiment uses touch and position sensitive material on the inner surface of the finger guide device for use as a pointing control device, such material being known to those skilled in the art of designing computer pointing control devices and incorporated herein by reference.

Instead of a computer mouse device, the finger guide device of this preferred embodiment shown in FIG. 5 allows the subject user to place his finger in the finger guide device to apply pressure in an axial or lateral or combined direction to use the finger guide device as a pointing control device; and if necessary, when authenticating or identifying himself to the system. Another similar preferred embodiment includes mounting the finger guide device in mechanical communication with one or more electromechanical switches or equivalent switching devices to allow the finger guide device 12 to be used as a means of pressure activated single pole, three way rocker switch or nine way bilateral rocker switch wherein the subject user is authenticated just prior to or during the switching process.

In each of the different preferred embodiments described herein, additional protrusions may be added to the finger guide device 12 or 12A to help further orient the subject's fingers or to cause the subject to "fine tune" their finger position. These may not be necessary for normal or average sized fingers, but are valuable in applications where the body has very small fingers that contact very little of the finger guide device surface area. Braille may be added to the finger guide device to facilitate blind or visually impaired users.

Each of the finger guide devices of the present invention as described in the various preferred embodiments herein may also use physical elements and special material properties to prevent inaccurate use. For example, one preferred method of practicing the present invention shown in FIG. 1 utilizes a relatively hard and distinct ridge around the finger guide device 12. Rather than being a "sharp" object that is perceived as dangerous, such ridges are intended to provide discomfort to the user. When a finger is placed on this ridge, although harmless, it is uncomfortable because it applies high pressure Per Square Inch (PSI) to the skin over a narrow area. This high pressure per square inch indicates through touch sensing that the finger is not properly placed in the recessed area. The feeling of a misaligned finger is an unnatural feeling and the user will instinctively reposition his finger to achieve a more natural and comfortable feeling. The natural tendency is to avoid placing a finger on the outer ridge of the finger guide device, but rather to easily slide the finger or thumb down comfortably and non-forcibly into the finger guide device and onto the sensor (the desired location).

The material properties of high thermal conductivity can be used to make each of the preferred embodiments of the finger guide devices described herein feel cooler when contacted than the surrounding surfaces and the sensor surface. Although all surfaces are usually at the same temperature, the ability to extract heat from the skin (thermal conductivity) causes a cooler feel. For example, by having the finger guide device (or surface coating) made of metal (or other thermally conductive material such as ceramic or nanoparticle ceramic paint), either preferred embodiment will have this property of being perceived as cooler than the surrounding surface if the surrounding surface is made of a material with low thermal conductivity, such as plastic or cloth. The result is that the subject user obtains the ability to distinguish the finger guide device surface from other surfaces based on haptic feedback and thereby guide his finger onto the finger guide device.

A smooth inner surface is also important to any of the preferred embodiments of the finger guide device disclosed herein. The low coefficient of sliding friction allows the subject finger to slide down into the recess in a non-forced manner until it reaches a stable global minimum position, which corresponds by design to a finger position that is suitably repeatable to align the fingerprint sensor with the relevant part of the finger. The low coefficient of static friction allows the subject finger to begin to slide into position in a non-forced manner and also prevents the subject finger from stopping halfway in the recess at the local minimum position, rather than at the desired and most stable global minimum position, which by design corresponds to a final finger position that is suitably repeatable for aligning the fingerprint sensor with the relevant portion of the finger. The lower the coefficient of friction, the better the preferred embodiment works; such an acceptable coefficient of friction may be obtained by surface characteristics of materials such as, but not limited to, polished metals, polished plastics, plated metals such as chrome, surface waxes, lubricants or special paints or coatings. Examples of materials that may be used after cleaning the finger guide device or, alternatively, formulated in a cleaning wipe include, but are not limited to, wet and dry lubricants (such as those used as bottle lubricants by bottle makers) and fatty acid-based static inhibitors such as Jojoba oil.

Any of the preferred embodiments of the finger guide device disclosed herein may be designed with active feedback mechanisms, including those designed to alert subjects or training subjects as to the correct positioning of their fingers or other feedback devices designed to alert subjects to the fact that they have been accepted in the system (i.e., their fingerprints have been scanned, compared and correctly matched). Voice or voice commands may be used to guide the user how to guide the finger to properly align the sensor. Any of the preferred embodiments of the finger guide device disclosed herein may also use active or passive visual indicators. Examples include, but are not limited to, lighted indicators, icons, fingerprint drawings or marks, fiducial marks, text descriptions, or colored marks, where such indicators are known to those skilled in the art of human factors engineering and are incorporated herein by reference. Finally, physical motion such as vibration or "click" used as a mechanical motion feedback mechanism, known to those skilled in the art of human factors engineering, can be used in a manner very similar to a stick vibrator that alerts the pilot of a stall warning when flying an aircraft.

In any of the preferred embodiments of the finger guide device disclosed herein, these feedback mechanisms may also be used to correct for misuse of the system. For example, extreme pressure on the sensor or lack of contact pressure may cause scanning problems. Too high a pressure can flatten the detail and saturate the sensor and make it unable to accurately resolve the detail. Conversely, a lack of pressure in the form of too light a contact may cause the details to be indistinguishable by the sensor and not produce a good image. In either case, a voice command or sound or other feedback means as described above may be used to communicate the need to relax the pressure (or grip) or even press (or squeeze) more strongly. Indicator lights, vibrations, or other feedback devices as described above or known to those skilled in the art of human system engineering and incorporated herein by reference may communicate to the subject the need to relieve contact pressure or lift the finger slightly.

Another possible method is to move the sensor slightly up or down in the finger guide device sensor area. While the preferred embodiments of the finger guide devices 12 and 12A do not disclose the ability to adjust the sensor depth with respect to the plane of the bottom of the recess, additional preferred embodiments allow for this and this element may be incorporated into any of the preferred embodiments of the finger guide devices disclosed herein. One such preferred embodiment of the finger guide device allows for manual adjustment of the sensor level to vary the finger contact pressure to optimize the image or image data characteristics. Yet another preferred embodiment of the finger guide device communicates with the system computer to determine in real time the need for the movement sensor to be closer to or further from the plane at the bottom of the recess and thus closer to or further from the finger or living minutiae related portion, and thereby enables optimization of the image of the fingerprint related portion in real time, regardless of whether pressure is a determining factor in the image optimization. For example, if an optical sensor is used, the disclosed real-time adjustments may be related to focal length rather than contact pressure; alternatively, if a sensor is used that detects a secondary surface tissue property, the pressure on the finger causing the reduced blood circulation may require adjustment.

The user's body may be stressed or in danger during use of the finger guide device of the present invention; for example, a crime may be underway in which a subject is under the muzzle and forced to sign. In such a situation, it is desirable that the user have different fingers registered for an emergency signal indicating that the device user is in danger, the selection of which is not necessarily known to others. If the user is experiencing another emergency or is even illegally forced to use the device, as described above, he may use the "911" finger to request assistance. In this case, the system cannot match the enrolled fingerprint, but it will recognize the match with the user's emergency finger and therefore recognize its requirements and make a different and corresponding response. In one possible embodiment of the finger guide device of the present invention, the emergency finger match is processed as an instruction to trigger a so-called "silent alert" to provide immediate assistance (e.g. police assistance). Furthermore, the system, rather than rejecting the user agent, can be programmed to fail or for other reasons than the subject being unable to authenticate, so that the desired security controlled event cannot be completed or delayed to allow additional events to await assistance, a method for reducing the risk suffered by the subject under duress.

For any of the preferred embodiments of the finger guide device disclosed herein, a preferred method of practicing the invention is to assemble the sensor and finger guide device designed and arranged to work together as a unit, i.e., a complete system. This requires that the sensor be configured to operate on a circuit board that likewise contains additional supporting circuitry for its application, and that the sensor communicate with the supporting circuitry. The combination of finger guide means, sensor, sealing gasket (or equivalent or no protective barrier means) and printed wiring board may or may not be placed in its own discrete housing. The subassembly may be placed in a variety of devices for its application. The disclosed system element is a security system platform device that has multiple uses in products or other more complex systems. Examples include, but are not limited to, vehicle doors or dashboards, countertops, doors or door frames, keyboards, personal digital assistants, telephone devices, secure facsimile machines, computing devices, displays, appliances, tools, machine controls, medical devices, cash registers, and more.

There are various patents/applications referenced throughout by application number and inventor. The disclosures of these patents/applications are hereby incorporated by reference in their entirety into this specification in order to more fully describe the prior art. To maintain the reasonable space of the present disclosure, additional elements using common means known to those skilled in the various arts are also incorporated by reference and such means are not included herein. Any of the preferred embodiments of the finger guide device disclosed herein may use future means for implementing the disclosed elements, and it is apparent that such means are not contemplated by the inventors at this time, but are incorporated herein by reference.

It is evident that many alternatives, modifications, and variations of the finger guide devices 12 and 12A of the present invention will be apparent to those skilled in the art in light of the disclosure herein. The scope of the invention is intended to be determined by the appended claims rather than by the words of the foregoing description, and all such alternatives, modifications and variations which form a combined equivalent are intended to be included within the spirit and scope of these claims.

Claims (10)

1. A finger guide device for mounting in alignment with a fingerprint sensor, the finger guide device having a side surface forming a recess for receiving a finger and for positioning the finger over the fingerprint sensor and axially and laterally aligning the fingerprint sensor, the recess being defined by axially directed concave end walls, the axially directed end walls adjacent the finger tip having a concave radius of curvature which is shorter than the concave radius of curvature of the axially directed end walls remote from the user's finger tip,

whereby the finger guide device aligns the finger with the fingerprint sensor along an axial direction to capture the relevant portion of the fingerprint for comparison with the enrolled portion of the fingerprint, the axial alignment being along the front and back of the finger guide device, and

whereby the finger guide device aligns the finger with the fingerprint sensor along a transverse direction to capture the relevant portion of the fingerprint for comparison with the enrolled portion of the fingerprint, the transverse alignment being between the side edges of the finger guide device, an

The finger guide device thus enables the relevant part of the finger to be placed on the fingerprint sensor in a stable position each time authentication or confirmation is required, the finger guide device reducing the occurrence of "false rejection" situations for identifying or authenticating a person touching the finger guide device.

2. The finger guide device of claim 1, wherein said finger guide device is designed to align an area on a finger with the fingerprint sensor, the area being in the range of 0.20 inches to 0.90 inches from the underside of the fingernail.

3. The finger guide device of claim 1 having surface friction characteristics to allow the finger to slide and settle at a local minimum of the fingerprint sensor.

4. The finger guide device of claim 1, wherein the finger guide device is used for repeated authentication on a frequent basis and the subject user generally keeps positioning a finger on the device.

5. The finger guide device of claim 1, wherein the sensor can be raised or lowered relative to the bottom plane of the finger guide device recess for changing the image characteristics of the relevant portion of the finger.

6. The finger guide device of claim 1, wherein the finger guide device communicates with an electromechanical sensor to allow the finger guide device to be used as an element in a pointing control device.

7. A finger guide device for mounting in alignment with a fingerprint sensor, the finger guide device enabling capture of a relevant part of a fingerprint during an enrolment procedure, the finger guide device having side surfaces forming a recess, the recess being defined by axially directed concave end walls, said axially directed end walls adjacent to said finger tip having a concave radius of curvature which is shorter than the concave radius of curvature of said axially directed end walls remote from the finger, the recess having the same basic shape as the finger, the finger guide device guiding the finger both in the axial direction and in the transverse direction onto the sensor during a subsequent identification or authentication requirement, the finger guide device enabling placement of the relevant part of the finger on the fingerprint sensor in a stable position in a repeatable manner each time the finger guide device is used for subsequent identification or authentication, the finger guide device reduces the occurrence of "false reject" situations for identifying or authenticating a person contacting the finger guide device;

whereby the finger guide device has a surface friction characteristic such that the finger slides and stabilizes in a local minimum position on the fingerprint sensor.

8. The finger guide device according to claim 7 wherein the finger guide device or finger guide device surface is conductive or partially conductive to convey the necessary electrical signal, frequency or potential to human tissue to facilitate proper operation of the fingerprint sensor.

9. The finger guide device according to claim 7 having a higher thermal conductivity than the surrounding portion so that heat is transferred out of the skin more quickly by said finger guide device than the surrounding portion, said finger guide device having a tactile characteristic that feels cooler when in contact than the surrounding portion, thereby indicating to the user that the finger is placed in the correct area.

10. A finger guide device for positioning a finger onto a fingerprint sensor, the finger guide device comprising:

a. a finger guide having a side surface forming a recess having the same basic shape as a finger; and

b. a fingerprint sensor aligned with the finger guide device;

whereby said recess is defined by an axially-directed concave end wall, said axially-directed end wall adjacent said finger tip having a concave radius of curvature that is shorter than the concave radius of curvature of said axially-directed end wall remote from the finger,

whereby the finger guide device reduces the occurrence of "false rejection" situations for person identification or authentication by positioning a user's finger axially in a front-to-back direction on the fingerprint sensor using a portion of the finger just below the fingernail to place the relevant portion of the finger in a repeatable manner in a stable position in alignment with the fingerprint sensor each time authentication or confirmation is required.