WO2018138067A1

WO2018138067A1 - Wearable biometric data acquisition device

Info

Publication number: WO2018138067A1
Application number: PCT/EP2018/051509
Authority: WO
Inventors: Johan Bergqvist
Original assignee: Smart Secure Id In Sweden Ab
Priority date: 2017-01-24
Filing date: 2018-01-23
Publication date: 2018-08-02

Abstract

A wrist-worn device (1), preferably a wristwatch, for biometric data acquisition comprising : a case (10) dimensioned to be worn on a wrist of an individual and a wrist strap (20) for holding the case to the wrist; the case (10) being provided with a sensor (30) for acquiring biometric characteristic data from a region of interest of the individual; wherein the case (10) is releasably connected to the wrist band (20) in a hinge-mounted manner such that the case (10) is movable around a pivot axis (A) from a locked position to a sensing position, wherein in the sensing position the case (10) is tilted such that a field of view (40) of the sensor (30) is directed onto the desired region of interest of the hand of the individual.

Description

Wearable biometric data acquisition device

Technical Field

The invention is directed to a wrist-worn device, preferably a wristwatch, for biometric data acquisition, comprising a case dimensioned to be worn on a wrist of an individual and a wrist strap for holding the case to the wrist.

Prior Art

Wearable biometric data acquisition devices comprising a wrist strap and a sensor for acquiring biometric characteristic data from a body part of a user are known. Wrist-worn biometric data acquisition devices typically comprise a case dimensioned to be worn on a wrist of an individual and a wrist strap for holding the case to the wrist.

US6799726 describes a wrist watch comprising a case and a strap for holding the case to the wrist. An infrared sensor is mounted to an undersurface of the case so as to be directed to the wrist. The infrared sensor is configured to detect the pattern of subcutaneous blood vessels on the wrist. Due to the short distance between sensor and wrist, the maximal field of view is strongly restricted.

US8019126 and US2010237990 describe a wrist-worn biometric data acquisition device having a light source on the upper side of the wrist and a plurality light receiving elements on the opposite side detecting light being transmitted through the wrist for acquiring a vein pattern. Again, the maximal field of view is restricted to the area of the receiving elements.

US2014196131 describes a wrist contact sensor device for capturing a wirst vein pattern. The device comprises at least one illuminator and a plurality of sensors, both for contacting the skin on a palmar side of the wrist. The devise detects reflected IR light from the at least one illuminator to generate a vein pattern. Again, the maximal field of view is restricted to the area of the receiving elements. US2016283809 describes a biometric sensor apparatus for capturing images of blood vessel patterns on the inner side of a wrist. The apparatus comprises a portion of a wrist strap and a near IR camera. The camera. Although the camera is not in direct contact with the wrist but may be arranged for capturing images at a distance greater than 20 mm, its field of view is still limited to a relatively small area of the inner side of the wrist.

WO2016018083 describes a wearable device comprising a case attached to a wrist strap. The case is provided with a light source and a camera for obtaining a vein pattern. In a first variant of the device, the light source and camera are arranged on the side of the case directed at the dorsal side of the hand . Due to the relatively flat case the field of view that can be in focus is restricted to a small area of the dorsal side of the hand. In a second variant of the device, the light source and the camera are arranged on the dorsal side of the case (front surface) and may be used to capture an image of the other hand . However, placing the hand at the right position and distance to obtain accurate image for robust authentication is difficult.

Summary of the invention

It is an objective of the invention to provide a device, which does not have the disadvantages of the prior art. In particular a device for obtaining accurate biometric data over a large region of interest in order to achieve robust authentication.

At least one of the objectives of the invention is achieved by a wrist-worn biometric data acquisition device according to claim 1. The wrist-worn device for biometric data acquisition comprises a case dimensioned to be worn on a wrist of an individual and a wrist strap for holding the case to the wrist. The case is provided with a sensor for acquiring biometric characteristic data from a region of interest of the individual. The case is releasably connected to the wrist band in a hinge-mounted manner such that the case is movable from a locked position to a sensing position, wherein in the sensing position the case is tilted such that a field of view of the sensor is directed onto the desired region of interest of the hand of the individual . With the hinged-mounted case a sensor positioned in the upper surface of the case may be moved into the sensing position and thereby placed at a well- defined distance over the dorsal side of the hand thereby having sufficient distance to the hand to capture images from almost the entire dorsal side. The maximal possible region of interest is considerably increased with respect to known devices, which also increases robustness and accuracy of the authentication.

The hinge for releasably connecting the hinge-mounted case to the wrist band may be a fixed mechanical hinge or an electro magnetically controlled hinge. The case may be released via an electromagnetic mechanism.

The wrist-worn device may be part of the biometric authentication system and using the biometric authentication method according to the Swiss patent application No. 01404/16 of the same applicant, which is hereby incorporated by reference.

Further embodiments of the invention are set forth in the dependent claims.

In some embodiments the sensor may be arranged in an upper surface of the case facing away from the wrist strap. Preferably, the sensor is arranged in a border area of the upper surface of the case opposite of the pivot axis. By such placement of the sensor, it is at the farthest position above the hand, when the case is moved into the sensing position.

In some embodiments the wrist strap may be provided with a revolving guiding track, into which the case is mountable when in the sensing position for revolving the case around the wrist in its sensing position. The revolving guiding track may be positioned at the distal edge of the wrist strap, i.e. the edge closer to the hand. By revolving the case around the wrist in a clockwise or anti-clockwise direction, a series of images over the entire surface of the hand may be captured and analysed for authentication purposes.

The revolving of the case around the guiding track may be controlled electromagnetically. Alternatively, the case can be manually moved by pushing it and gears may be present to control the speed of the revolving case. The wrist strap or the guide track may be provided with a series of electromagnets, which interact with corresponding electromagnets on the case. The case may trigger a current to drive the watch over and along the electromagnets on the wrist strap for one complete circular motion around the wrist. The wrist strap or the guide track may be provided with piezo electric sensors to sense the position of the case and guide it around the wrist in a controlled manner.

In some embodiments the sensor may comprise an illumination unit for illuminating the region of interest of the hand and an image capturing unit for capturing at least one image of the illuminated region of interest of the hand. The wrist-worn device may further comprise a processing unit for extracting the biometric characteristic data from the image captured by the image capturing unit and an authentication unit for verifying the extracted biometric data against registered characteristic data to authenticate the individual. Such as sensor is described in Swiss patent application No. 01404/16 of the same applicant, which is hereby incorporated by reference.

In some embodiments the illumination unit may comprise at least one light source of visible light source and/or at least one light source of near infra-red (NIR) light, and wherein the light source preferably comprise a plurality of light emitting diodes (LEDs). The light sources or LEDs may be placed in a circular manner around the capturing unit. Different light sources may be placed alternately. Preferably, the illumination unit comprises light sources for visible and NIR light to detect e.g. hand or palm print/creases and hand or palm veins, respectively. That way the authentication analysis can be based on polygons having print/crease patterns and vein patterns present.

In some embodiments the illumination unit may be a backlight of a viewing screen of the case or at least one separately arranged light source. The illumination unit may be provided with at least one pattern mask in order to project a mask pattern onto the region of interest such that the projected mask pattern is included in the captured image. The pattern mask may be arranged strip-like along at least one edge of the viewing screen. Such a pattern mask is described in Swiss patent application No. 01404/16 of the same applicant, which is hereby incorporated by reference.

The projected mask pattern, which preferably consists of identically shaped polygons of the same area, can be used to find the optimal distance between body part placed over the device and illumination or capturing unit in an entirely contact-free manner by comparing the average size of the individual pattern shapes projected onto the body part to the size of the individual pattern shapes obtain during a previous calibration step. The same mask pattern projected onto the body part and therefore included in the captured image can also be used to define a region of interest of the body part and to extract the characteristic biometric data in that individual pattern shapes are identified, which include structures of interest of the body part (e.g. palm crease/print and palm vein). In addition, the same mask pattern can be used to perform a liveliness test based on the unevenness of the body part. Unevenness of the body part leads to a distortion of the mask pattern. This distortion can hardly be reconstructed by a dummy body part and can therefore be used as an indication of liveliness of an individual to be authenticated.

In some embodiments the pattern mask may have a regular pattern of polygons, preferably triangle, tetragon, square, pentagon or hexagon. I.e. the polygons have identical shape and area.

Brief Explanation of the Figures

The invention is described in greater detail below with reference to embodiments that are illustrated in the figures. The figures show:

Fig. 1 a top view of an embodiment of a wrist-worn device for biometric data acquisition;

Fig. 2 a top view of an embodiment of a wrist-worn device for biometric data acquisition;

Fig. 3 the wrist-worn device of Fig . 1 or 2 attached to the wrist of a user in its locked position; Fig. 4 the wrist-worn device of Fig . 1 or 2 in a partially unlocked position;

Fig. 5 the wrist-worn device of Fig. 1 or 2 in a sensing position for capturing images of a dorsal side of a hand;

Fig. 6 the wrist-worn device of Fig . 1 or 2 in a sensing position partially revolved for capturing images of an inner side of a hand;

Fig. 7 the wrist-worn device of Fig . 1 or 2 in a sensing position partially revolved for capturing images of a palmar side of a hand;

Fig. 8 the wrist-worn device of Fig . 1 or 2 in a sensing position partially revolved for capturing images of an outer side of a hand; and

Fig. 9 the wrist-worn device of Fig. 1 or 2 used for authentication in a locked position of the case.

Description of the Invention

Fig. 1 and Fig. 2 each show a top view of an embodiment of a wrist-worn device 1 for biometric data acquisition. The device 1 comprises a case 10 dimensioned to be worn on a wrist of an individual and a wrist strap 20 for holding the case to the wrist of the individual . The device 1 is a wristwatch with a viewing screen 13. The case 10 of the device is releasably attached to the wrist band 20 in hinge-mounted manner such that it can be tilted around a pivot axis A towards the hand into a sensing position (see Fig . 5(a)). Fig. 1 and Fig . 2 show the case 10 in a locked position secured to the wrist band 20.

The case 10 is provided with a sensor 30 for acquiring biometric characteristic data from a region of interest of the individual . The sensor 30 comprises an illumination unit 31 for illuminating the region of interest of the hand and an image capturing unit 32 for capturing at least one image of the illuminated region of interest of the hand . The capturing unit 32 of the device is arranged in a border area 12 of an upper surface 11 of the case 10 facing away from the wrist strap 20.

In the embodiment as shown in Fig . 1 the illumination unit 31 is arranged along the edge region of the viewing screen 13 and the backlight of the viewing screen 13 may be used for illuminating the region of interest. In the embodiments as shown in Fig . 2 the illumination unit 31 is arranged circularly around the image capturing unit 32. Other placements of illumination unit 31 and image capturing unit 32 are also possible. Ideally, the image capturing unit 32 and the illumination unit are arranged at the opposite side of the case as the pivot axis A or a guiding track 21, which will be explained in more detail below.

In the embodiments shown, the illumination unit 31 comprises a pattern mask 33 for in order to project a mask pattern onto the region of interest such that the projected mask pattern is included in the captured image. In the embodiment of Fig . 1 the pattern mask 33 has a strip-like shape and is arranged along two opposite edges of the viewing screen 13 and parallel to the pivot axis A. In the embodiment of Fig. 2 the pattern mask 33 is arranged on LED units of the illumination unit 31 arranged circularly around the image capturing unit 32.

The function of the pattern mask 33 is explained in more detail in the Swiss patent application No. 01404/16 of the same applicant, which is hereby incorporated by reference. The pattern mask, which pattern consists of identically shaped polygons of the same area, projects a mask pattern onto the region of interest. The projected mask pattern can be used to find the optimal distance between body part placed over the device and illumination or capturing unit in an entirely contact-free manner by comparing the average size of the individual pattern shapes projected onto the body part to the size of the individual pattern shapes obtain during a previous calibration step. Therefore, the device can also be used as authentication device with the case in its locked position, as shown in Fig. 9. The same mask pattern projected onto the body part and therefore included in the captured image can be used to define a region of interest of the body part and to extract the characteristic biometric data in that individual pattern shapes are identified, which include structures of interest of the body part (e.g . palm crease/print and palm vein). In addition, the same mask pattern can be used to perform a liveliness test based on the unevenness of the body part. Unevenness of the body part leads to a distortion of the mask pattern. This distortion can hardly be reconstructed by a dummy body part and can therefore be used as an indication of liveliness of an individual to be authenticated.

A pivot axis A is located in an edge region of the wrist strap 21 at the side of the case being nearer to the hand . When moving the case 10 into a sensing position as shown in Fig. 5(a) by tilting it around the pivot axis A the sensor 30 is moved upwards and towards the hand such that the field of view 40 of the sensor 30 covers almost the entire surface of the dorsal side of the hand . Thereby a region of interest can be chosen for the authentication analysis, which cover a larger part of the hand's surface. Depending on the type of sensor e.g. images of vein patterns and/or crease patterns may be captured.

The wrist strap 20 of the wrist-worn device 1 is provided with a revolving guide track 21 arranged at the distal side of the wrist strap 21 - when worn by the individual - near the pivot axis A. When moving the case 10 into the sensing position, the case 10 may engage the guide track 21 in order to revolve the case 10 around the wrist. By revolving the case 10 around the wrist, a series of images of the hand may be captured from all sides as depicted in Figures 5 to 8. In Figures 5(a) to 8(a) the device 1 is shown in a side view of the tilted case 10 parallel to the region of interest covered by the field of view 40 of the sensor 30. In Figures 5(b) to 8(b) the device 1 is shown in a top view perpendicular to the region of interest covered by the field of view 40 of the sensor 30. In Fig . 5 the field of view 40 of the sensor 30 is directed onto the dorsal side of the hand. In Fig . 6 the field of view 40 of the sensor 30 is directed onto the inner side of the hand. In Fig . 7 the field of view 40 of the sensor 30 is directed onto the palmar side of the hand . In Fig . 8 the field of view 40 of the sensor 30 is directed onto the outer side of the hand.

In order to tilt the case around the pivot axis A and engage it into the guide track 21, the case may be unlocked by slightly moving it away from the guide track 21 as indicated by the arrow in Fig . 4 and then tilted around the pivot axis A in to the sensing position as indicated in Fig. 5. It is understood that the present invention is not limited to the embodiments as discussed above. The person skilled in the art will be able to derive further variants with knowledge of the invention which also belong to the subject matter of the present invention.

Reference Signs

1 wrist-worn device

10 case

11 upper surface

12 border area

13 viewing screen

20 wrist strap

21 revolving guide track

30 sensor

31 illumination unit

32 image capturing unit

33 pattern mask

40 field of view

50 vein pattern

60 crease/print pattern

A pivot axis

Claims

1. A wrist-worn device (1), preferably a wristwatch, for biometric data acquisition comprising : a case (10) dimensioned to be worn on a wrist of an individual and a wrist strap (20) for holding the case to the wrist; the case (10) being provided with a sensor (30) for acquiring biometric characteristic data from a region of interest of the individual; characterized in that the case (10) is releasably connected to the wrist band (20) in a hinge- mounted manner such that the case (10) is movable around a pivot axis (A) from a locked position to a sensing position, wherein in the sensing position the case (10) is tilted such that a field of view (40) of the sensor (30) is directed onto the desired region of interest of the hand of the individual .

2. The wrist-worn device (1) according to claim 1, wherein the sensor (30) is arranged in an upper surface (11) of the case (10) facing away from the wrist strap (20).

3. The wrist-worn device (1) according to one of the preceding claims, wherein the sensor (30) is arranged in a border area (12) of the upper surface (11) of the case (10) opposite of the pivot axis (A). The wrist-worn device (1) according to one of the preceding claims, wherein the wrist strap (20) is provided with a revolving guiding track (21), into which the case (10) is mountable when in the sensing position for revolving the case (10) around the wrist in its sensing position.

The wrist-worn device (1) according to one of the preceding claims, wherein the sensor (30) comprises an illumination unit (31) for illuminating the region of interest of the hand and an image capturing unit (32) for capturing at least one image of the illuminated region of interest of the hand .

The wrist-worn device (1) according claim 5, wherein the illumination unit (31) is a backlight of a viewing screen (13) of the case (10) or at least one separately arranged light source.

The wrist-worn device (1) according to one of claims 5 or 6, wherein the illumination unit (31) is provided with at least one pattern mask (33) in order to project a mask pattern onto the region of interest such that the projected mask pattern is included in the captured image.

The wrist-worn device (1) according to claim 7, wherein the pattern mask (33) is arranged strip-like along at least one edge of the viewing screen (13).