FINGERPRINT DETECTING TERMINAL COMPRISING AN ERGONOMICALLY OPTIMIZED FINGER LOCATION PLATE

Abstract: A fingerprint detecting terminal is disclosed, including a fingerprint sensor with a contact surface (18) for a finger under investigation. The contact surface (18) is arranged within an ergonomically optimised finger location plate (13) comprising a distal joint location ridge (21) for controlling axial location of the finger relative to the contact surface (18), and at least one finger trough (26) for controlling transverse motion and angular twist of the finger.

Description: H Fingerprint detecting terminal comprising an ergonomically 5J optimized finger location plate The. invention relates to a fingerprint detecting terminal in¬ cluding a fingerprint sensor wit -a contact surface for a fin¬ ger: under investigation, iαr Fingerprint detecting terminals of the type indicated above, having many different shapes and serving different purposes, are previously known. IS Norr ally such terminals, as described for example in US-Patent 4,322,163, comprise a finger location plate with a contact sur¬ face to support the finger during the investigation process. In order to position or locate the finger relative to said contact surface, a stop is arranged at the end of the finger location 2XT plate. The area of the .inger having the greatest concentration of fingerprint details or minutiae must be located on the contact surface in a certain angular position. Finger location means 25 must accomodate the wide variety of finger sizes, shapes, and softnesses, and various fingernail lengths. A stop located at the end of a finger location plate has proved inadequate. Different fingernail lengths may cause different jσ positioning of said minutiae. Furthermore, such a stop may damage long fingernails. In addition, a location plate of this type provides no control of transverse motion and angular twist of a finger under investigation. r- 35 European patent application, serial no. 86 10 62 31.3, filed Mcy 1986, incorporated by reference herein, describes an appa- I ratus and procedure for determining the authorization of indi¬ viduals by verifying their fingerprints. The apparatus of the invention uses a portable data carrier e.g. a plastic card, which has magnetic tracks to store data., Stored data can con- 5 sist αf the degree of correlation between a fingerprint of an authorized individual and a selected reference image, and the code number of the selected reference image. A fingerprint de¬ tection terminal with a sensor includes a memory in which the selected reference image is stored. The terminal compares the iα actual fingerprint of an individual to be checked with the corresponding reference image identified on the plastic card arrd stored in the fingerprint detection terminal. The deter¬ mined degree of correlation is in turn compared to the degree αf correlation stored on the plastic card. As a function of the 15 result of this comparison, an appropriate decision signal is generated. The data are written on the plastic card in such a way that, based on the data alone, only ambiguous conclusions concerning the identity of the individual are possible. 2T The apparatus of the invention permits the use of independent, convenient terminals. These terminals can serve to control the entry to and exit from access-controlled security areas. Fur¬ thermore, it is possible, for example, to combine a device of this kind with each of the automated teller machines commonly ~ 5 located at banks. Such terminals can also be used to ensure the security of financial transactions of any kind. Thereby, the unlawful use of credit cards, for example, can be almost en¬ tirely eliminated. 3d In order to perform under these conditions, the terminals must be robust and of simple, solid construction. Furthermore, the terminals should be hygienic and comfortable, and the user should not be afraid that he will damage his finger. A wide variety of finger sizes, shapes, and softnesses, and various 35 fingernail lengths will be expected. 1 It is therefore an object of the invention to provide an ergonomically optimized fingerprint detecting terminal which reliably locates or positions an individual's finger. It 5 The above object is achieved by a fingerprint detecting termi¬ nal according to the invention as defined herein. According to the invention, the terminal is characterised in that a contact surface is arranged within an ergonomically optimised finger location plate comprising a distal joint location ridge for 10 controlling axial location of the finger relative to the con¬ tact surface, and at least one finger trough for controlling transverse motion and angular twist of said finger. The previous problems of finger location in a fingerprint de- 15 tecting terminal are eliminated, because the area of the fin¬ gerprint containing the greatest concentration of details or minutiae is reliably located on said contact surface. It has been shown that this detail area may be defined from- the nom¬ inal line of the distal joint. Consequently, the finger locator 20 ideally also references from this joint. Transverse location of said fingerprint is achieved by providing two guiding rails, arranged in parallel on said contact surface. The guiding rails may be small rectangular bars bounding or limiting said contact surface. .25 Additionally, in order to control transverse motion and angular twist of the whole finger, to provide a standardized repeatable location, and to obtain a uniform pressure distribution over the entire contact surface, said contact surface is arranged 30 within a finger trough. This finger trough is designed to suit the shape and position of the relaxed hand, so as to make use more acceptable and com¬ fortable, and to avoid a cramped position of the finger under 35 investigation. Therefore these finger troughs are slightly bowed according to a relaxed hand position. Tix improve these comfort features in a preferred embodiment of the invention, one central finger trough comprising said con¬ tact surface is arranged with adjacent finger location troughs designed to receive neighbouring fingers of the finger under investigation. The arrangement and length of adjacent troughs persuades the iπdiviual to place the appropiate finger under investigation into, the middle trough. ICC Th s is achieved independently of the individual being a right- σr a left-hander. It has been determined that it is most suitable to arrange the 15 a acent finger troughs at an angle with respect to each other, within the range of 2-5 degrees. It is advantageous to incorporate the finger troughs within a housing cover of the terminal, in order to provide a bearing 2U surface area for the hand. The housing cover can be cleaned easily. Trr another embodiment of the invention, guiding elements of a 25 card reader are formed at the adjacent front areas of the hous¬ ing cover designed as a finger location plate, and a housing enclosing electronic equipment of said terminal. The invention will be described in the following with reference 3U to embodiments which are shown in the drawings in which: Fig. 1 is a side view of a fingerprint detecting terminal ac¬ cording to the invention, for use in an access-control system, 25 Fig. 2 is a top view of the fingerprint detecting terminal of Fig. 1, Figs. 3a-g are schematic cross-sections through different em¬ bodiments of distal joint location ridges, Figs. 4a-d are schematic cross-sections through different em- bodiments of means provided for sideways location of a finger under investigation, Fig. 5 is a perspective view of an embodiment of a finger lo¬ cation plate comprising the locating elements of Figs. 3 and 4, and Fig. 6 is a schematic cross-sectional view of one embodiment of a finger location plate. The fingerprint detecting terminal shown in Figs. 1 and 2 com¬ prises a plastic moulded housing 10 in the form of a box which encloses the entire evaluation logic and power supply, and car¬ ries mounting elements 11 and power plug 12. The terminal is removably covered by a finger location .plate 13, an indication display 14 and an input keyboard 15. A card reader 16 designed to receive a card-like c ' ata carrier is located between the finger location plate 13 and the housing 10, whereby adjacent elements of the finger location plate 13 and the housing 10 form guiding elements 17 of the card reader 16. A fingerprint sensor 30 with a contact surface 18 is incorpo¬ rated in the finger location plate 13 and is arranged inside the housing 10. Normally, a contact surface 18 is a pressure sensitive contact surface made of a coated elastomer, for re¬ ceiving the contact pressure of a finger 19 under investiga¬ tion. An electric output signal, corresponding to the ridges and valleys of a finger 19 placed on the contact surface 18, is generated by the sensor 30. 6 1 The area of the finger 19 containing the greatest concentration of details or minutiae e.g. ridges and valleys, is the finger tipr of the index finger or any other finger of either the right or the left hand. This area must be accurately placed on the 5 contact surface 18 in order to ensure that reliable output sig¬ nals are generated by the fingerprint sensor 30. Accurate placement will be achieved when a given individual's finger is located so that the area of interest falls on the JXΣi contact surface, +/- 1 mm, both longitudinally and transver¬ sely. It is therefore necessary to provide means for con¬ trolling the axial and transverse location of this area of interest. 15 it has been found that ideal results are achieved when the area " of interest is defined from the nominal line of the distal .Joint 20 of a finger 19. Consequently, the locating or posi¬ tioning of a finger 19 ideally is also referenced from this joint. zα fts shown in Fig. 3 as well as in Figs. 1 and 2, a distal joint location ridge 21 is arranged in a finger trough 26, for lon¬ gitudinally locating a finger 19. The ridge 21 is designed to fit the distal joint-20 of a finger 19, so that it can easily Z5 ; fcce sensed by a person under investigation. Several embodiments of location ridges having a wedge- or rib- like design are shown in Figs. 3a-g. Finger supporting areas 22 of different slope angles are arranged on both sides of the 30. ridges 21. It has been found that the best results are achieved when the ridge 21 is designed -according to the distal joint shape of a finger in a relaxed position. A typical ridge has a height of about 1 - 3 mm with respect to the contact surface 18 and extends along the entire width of the contact surface 18. 25 However, it has been determined that even different sizes and shapes of ridges may be utilized, provided the person under investigation can feel the ridge and consequently controls his finger location. 7 12 ffis shown ? ire the cross-sectional .view of Fig. 6, the location ridge 211 and the adjacent supporting area 22 are designed as a απe-piece? element made of mouldable plastic material comprising SOT opening 23 for the contact surface 18. The one-piece element provides side covering for the contact surface 18, whereby the actual opening 23 for the contact surface is about 10 by 10 mm in size, or of a slightly rectangular or oval shape with simi¬ lar dimensions. in * In a further embodiment of the invention shown in Figs. 4 and 5, two guiding rails 24 in the form of small rectangular bars or even edges or grooves are arranged in parallel in order to provide sideways or transverse location of the fingerprint de¬ tails or minutiae. These guiding rails 24 extend longitudinally 15c- along the contact surface 18, preferably bounding or limiting the contact surface. When a person under investigation feels these rails 24, he may adjust his finger tip position according to the direction and position of the rails 24. Thus, the proper sideways location of the fingerprint minutiae on the contact 20- surface 18 is achieved. Irrespective of control means like ridges or rails associated with the contact surface 18, it has been found most advanta¬ geous to provide three finger troughs 25, 26, 27 as shown in -25c Figs. I and 2, for controlling transverse motion and angular twist of a finger or even a whole hand. A central finger trough 26 comprising a contact surface 18 near its fingertip end area is designed to receive an index finger, for example. Adjacent finger troughs 25, 27 are designed to receive neighbouring fin- 20 gers of the finger under investigation. For example, the index finger of the right hand would be placed in trough 26, while the middle finger of the right hand would be placed in trough 27. For the left hand, the index finger would be placed in trough 26 and the middle finger would be placed in trough 25. 25- To suit a relaxed hand position, the finger troughs 25, 27 are arranged at an angle 28 of about 2 to 5 degrees with respect to Z. the central trough 26, and all of the troughs 25, 26, 27 are slightly bowed or curved in shape. These finger troughs 25, 26, 27 are an integral part of the 55 finger location plate 13. To give support to the relaxed hand, the one-piece finger location plate 13 is bowed like the troughs. In order to activate a detecting terminal as shown in Figs. 1 ICE and 2 a card holder inserts his plastic ID-card into the card reader 16. Evaluation logic starts a preliminary check of the ID-card, and, if the card is valid, activates a control lamp 25 which indicates that the card holder should locate his fin¬ gers on the finger location plate 13. The fingerprint verifi- 15? cation process then starts. The result of the verification process is then displayed on the display means 14 by phrases like "enter code on keyboard" or ,r rejectεd" or any other instructions to the card holder, such 2H as instructions to place his other hand on the location plate 13 in case the fingerprint details are not detectable on one finger due to dust, grease or any other obstacles. ZS 2E 25

Claims: 9 Clairm I Fingerprint detecting terminal comprising a fingerprint sensor with a contact surface (18) for a finger (19) under investigation, characterised by an ergonomically optimised finger location plate (13) comprising a primary finger trough (26) for controlling axial location, transverse motion and angular twist of said finger, whereby said contact surface (18) is arranged within said finger location plate (13) and wherein said finger trough (26) is designed ergonomically to suit the relaxed hand shape and position. Claim 2. Fingerprint detecting terminal according to claim 1 wherein said primary finger trough (26) comprises a distal joint location ridge (21) for controlling axial location of said finger relative to contact surface (18). Claim 3 Fingerprint detecting terminal according to claim 1 or 2, further comprising secondary finger troughs (25, 27) arranged adjacent to said primary finger trough (26) and designed to receive neighbouring fingers of said finger (19) under investigation. Claim 4 Fingerprint detecting terminal according to claim 3, wherein said secondary finger troughs (25, 27) and said primary finger trough (26) are arranged at an angle (28) with respect to each other. Claim 5 Fingerprint detecting terminal according to claim 4 , wherein said angle (28 ) suits a relaxed hand position and is within the range of 2 - 5° . Claim 6 Fingerprint detecting terminal according to any of claims 1 to 3 wherein said finger location plate (13) is designed as a housing cover of said terminal. Claf 7 Fingerprint detecting terminal according to claim 6, further comprising a box-like housing (10) for an entire evaluation logic and a power supply, whereby said housing (10) is covered by said finger location plate (13), an indication display (14), and an input keyboard (15). Claim 8 Fingerprint detecting terminal according to any of claims 1 to 7T wherein said finger location plate (13) and said housing (10) carrying said finger location plate (13) are designed to form guiding elements (17) of a card reader to receive a card like data carrier placed between said guiding elements (17). Claim 9 Fingerprint detecting terminal according to any of claims 1 to ff: wherein said contact surface (18) comprises means such as guiding rails (24) arranged in parallel to each other for sideways location of said finger (19) with respect to said contact surface (18). Claim 10 Fingerprint detecting terminal according to any of claims 2 to 9 wherein said location ridge (21) has a wedge-like shape to fit the distal joint (21) of a human finger.

Inventors: ELLISON IAN, TIMMS IAN, ELLISON, IAN, TIMMS, IAN
Applicants: SIEMENS AG, SIEMENS LTD, SIEMENS AKTIENGESELLSCHAFT, SIEMENS, LTD.
Application year: 1988
Main classification: G07C9
IPC codes: A61B5, G06K9, G07C9