WO2000039744A1

WO2000039744A1 - Device for identifying a person

Info

Publication number: WO2000039744A1
Application number: PCT/EP1999/010385
Authority: WO
Inventors: Hans Jürgen PÖHS
Original assignee: Delsy Electronic Components Ag
Priority date: 1998-12-23
Filing date: 1999-12-23
Publication date: 2000-07-06
Also published as: AU2286300A; JP2002533848A; EP1141881A1

Abstract

The invention relates to a device for identifying a person by means of at least one finger print. Said device comprises at least one light source for illuminating and/or transilluminating the front part of a finger by means of light pulses; and at least one fibre-optic finger support surface for taking an optical image of the finger print, by means of which the optical image can be sent to at least one sensor unit in which the optical image can be converted into electrical signals. The at least one light source is positioned to one side of the finger support surface and the light can be emitted by the light source towards the side of the finger support surface which faces away from the sensor unit and serves to support the front part of the finger. The duration and/or intensity of the light pulses emitted by the at least one light source can be adjusted in accordance with ambient light conditions.

Description

DEVICE FOR PERSONAL IDENTIFICATION

The present invention relates to a device for personal identification by means of at least one fingerprint with at least one light source for illuminating and / or for illuminating the front region of a finger by means of light pulses and with at least one fiber-optic finger support surface for taking an optical image of the fingerprint, through which finger support surface the optical image can be transported to at least one sensor unit in which the optical image can be converted into electrical signals, the at least one light source being arranged laterally next to the finger support surface and the light from the light source in the direction of that facing away from the sensor unit for laying on the front area of the finger provided side of the finger support surface can be radiated.

Devices of this type are used to record and process fingerprints and can be used in any areas in which personal identification is necessary. Examples in this context include the field of computer technology, entry systems, criminalistics, medicine, protection systems in general, and the banking and finance sector.

Systems are now known in the field of devices for personal identification by means of at least one fingerprint (cf. international publication WO 98/27509) which have a light source which is arranged above the finger to be x-rayed, so that the finger is placed on the finger support surface when it is placed on it between the light source and the finger rest. After passing through the front area of the finger and picking up the information relating to the fingerprint, the light emitted by the light source passes through the fibers of the finger support surface into the sensor unit arranged below the finger support surface and is then analyzed by means of the evaluation unit arranged downstream of the sensor unit.

In connection with this so-called direct optical method, however, it proves to be extremely problematic that the person to be identified by means of their fingerprint has to insert the finger in question into a cavity or an opening between the light source and the finger support surface.

From a psychological point of view, this is extremely unfavorable and, according to experience, increases the inhibition threshold for using a generic device in a significant manner because the one to be identified Person is, as it were, forced to insert an exposed part of the body in the form of the front area of the finger into a cavity that cannot be visually detected, which is often accompanied by an increased feeling of fear.

The aforementioned problem of psychological overcoming does not exist in a generic device for entering irregular patterns (cf. German laid-open specification DE 44 04 918 AI). This device contains an optical fiber bundle, at the two ends of which an entry surface and an exit surface are formed. An illumination device emits irradiation light in such a way that a light pattern is formed corresponding to a convex part of an object in contact with the entry surface and corresponding to a concave part of the object out of contact with the entry surface. If an angle of incidence of the irradiation light is obtained which is greater than a critical angle at an interface between a core part of a respective optical fiber of the optical fiber bundle and the air, it is possible to have a total reflection at the entrance surface apart from contact with the concave part of the object and at the Entry surface in contact with the convex part of the object to achieve no total reflection, which results in reflection light with a light pattern corresponding to an irregular pattern. The resulting light pattern is entered into a photoelectric conversion device via the exit surface and converted into electrical information by the latter.

The device known from DE 44 04 918 AI However, it proves to be disadvantageous in that it works with light of constant intensity and is based on the principle of disturbed total reflection. This makes both the type of lighting and the light guide rigid and inflexible, because with an illuminance of the ambient light of more than about 3,000 lux, the photoelectric is very quickly saturated

Converter device, so that no reliable results can be achieved with the conventional device.

Based on the disadvantages and inadequacies set out above, the object of the present invention is to develop a generic device for personal identification in a manner which enables adequate, reliable results in the front area of the finger to be brought out with timely results, and in which both the personal identification device completely visible and the process of person identification is comprehensible and transparent for the person to be identified and with which ultimately good and reliable results can always be achieved regardless of the ambient light conditions.

This object is achieved in a device according to the preamble of the main claim in that, according to the teaching of the present invention, the duration and / or the intensity of the light pulses emitted by the at least one light source can be regulated as a function of the ambient light conditions.

It is therefore unpredictable for the person skilled in the art An adaptive light control (= ALR or ALC = "adaptive light control"), that is to say a type of "intelligent light control" is provided, by means of which the deficits in changing ambient lighting conditions, such as changing room lighting or changing solar radiation, can be compensated by changing the Device according to the present invention or the algorithm controlling the device adapts to the respective lighting conditions.

For this purpose, at least one control means for regulating the duration and / or the intensity of the light pulses is preferably provided in the device according to the present invention. With this control means, a continuous or temporary measuring method can be carried out, with which a permanently good image quality can be determined and with which, if necessary, optimal saturation can be achieved by means of short-term light pulses, matched to contrast and depth of field, the short-term light pulses in their duration and / or in their Intensity are dosed exactly to the actually required amount of light.

According to an advantageous development of the present invention, the control means has: at least one detection module for detecting the ambient light conditions, the detection module being able to be embodied uniformly with the sensor unit and / or as part of the sensor unit; at least one evaluation module for determining the duration and / or the intensity of the light pulses in adaptation to those detected by the detection module Ambient light conditions, wherein the evaluation module can be formed uniformly with at least one evaluation unit and / or as part of at least one evaluation unit, which is preferably arranged downstream of the sensor unit; and at least one memory module for storing threshold values intended for regulating the duration and / or the intensity of the light pulses, the memory module being able to be embodied uniformly with at least one memory unit and / or as part of at least one memory unit which is preferably arranged downstream of the sensor unit .

The mode of operation and function of the control means is, for example, such that the detection module detects the respective

Ambient light conditions are detected, these are evaluated and analyzed in the evaluation module, and a comparison is made in the evaluation module with predetermined threshold values stored in the memory module.

Depending on the result of this comparison, the light source, which is connected to the control means and here in particular to the evaluation module, is then addressed by the control means, the duration and / or the intensity of the light pulses emitted by the light source being adapted to the ambient light conditions determined.

As a result, the light pulses can be designed dynamically and adaptively both in terms of their duration and their intensity, so that they can be used for any type of ambient light (e.g. strong sunlight, weak sunlight, dim light, diffuse light, gas light, moonlight, artificial lighting, ...) to provide the necessary light irradiation and thus to obtain a high-contrast and deep image of the fingerprint.

In particular, with the adaptive light control illuminances from zero lux to about 40,000 lux can be realized, the latter illuminance value roughly corresponding to direct sunlight. The results that can be achieved with this adaptive light control have a contrast and depth of field increase of up to about eighty percent compared to conventional lighting systems with continuous light, the type of light control according to the invention having the advantage that it changes the amount of light required in a time range of less than with changing lighting conditions can dose and provide one hundred milliseconds, so that an almost constant image quality can be obtained in all conceivable lighting conditions.

The advantage of the present device, which is essential to the invention, is therefore to be seen in the "intelligent control" which, as it were, self-adjusts the amount of light irradiated and calculates it separately for each area around the object to be illuminated, ie around the front area of a finger and makes it available so that overexposure or underexposure is excluded with a probability bordering on certainty.

In this context, constant lighting units, such as those used in conventional devices for Personal identification by means of at least one fingerprint are provided, the further disadvantage that the amount of light provided by them cannot be emitted object-related, i.e. a ten millimeter strong object is illuminated with the same amount of light as a five millimeter strong object, resulting in blurring and also partial overexposure result.

In contrast to this, the present invention enables the uniform illumination of an object, for example the front region of a finger, regardless of the strength of the object, which may also have a more or less strong light conductivity or a more or less strong reflectivity , as well as regardless of whether this object is now illuminated frontally, laterally and / or from the rear by stray light. Accordingly, it does not matter in the present invention at what angle and from which point light is irradiated onto the object to be illuminated; only the duration and / or the intensity of the additional light required is to be regulated individually for each area.

The advantages of the present adaptive light control ultimately lead to the fact that a finger image can be determined without any significant change in the exposure times while maintaining the full contrast and depth of field.

The control means for the adaptive light control is expediently designed as at least one logic component and / or as at least one logic circuit, in particular as at least one Standard logic component or designed as at least one programmable logic (FPGA = field programmable gate array). Alternatively or in addition to this, the control means can also be designed as at least one digital signal processing unit (DSP digital signal processor) and / or as at least one microcontroller.

As already stated above, the control means provided for the implementation of the adaptive light control in accordance with an expedient embodiment has at least one detection module, at least one evaluation module and at least one memory module. If the detection module is now preferably configured uniformly with the sensor unit and / or as part of the sensor unit, the photosensitive surface and / or the photosensitive layer of the sensor unit can use the adaptive light control to a certain extent self-regulate the amount of light required for each of its areas request what works particularly well if the evaluation module of the control means is designed uniformly with the evaluation unit and / or as part of the evaluation unit.

Conventional devices for

Personal identification by means of at least one fingerprint cannot do this because such known devices - if at all - regulate the incident light inflexibly and rigidly for the entire area of the sensor unit; in contrast, only the adaptive light control is able, for each area of the surface and / or the layer of the sensor unit, in view of the Ambient lighting conditions to calculate the amount of light required in terms of duration and / or intensity in the evaluation module with regard to optimal saturation and to deliver it immediately.

According to a particularly advantageous development of the present invention, it can be part of the adaptive light control (= ALR or ALC = "adaptive light control"), that is to say the "intelligent light control", the amplification of the electrical signals in the sensor unit and / or in the To design the evaluation unit to be variable over the different areas of the optical image.

The background of this particularly advantageous further development is the fact that the intensity distribution and consequently the contrast of the light scattered inside the front area of the finger are neither uniform nor constant over the entire width of the optical image, but are lower in the central areas of the optical image than in the Edge areas of the optical image is, which is connected among other things with the fact that the at least one light source is arranged laterally next to the finger support surface and that the light from the light source in the direction of the side of the finger support surface facing away from the sensor unit and intended for placing the front region of the finger is radiated. As a result, less light reaches the central areas covered by the front area of the finger on the side of the finger support surface facing away from the sensor unit than the lateral areas, so that the intensity and - directly proportional to this - the contrast of the scattered light is weaker in the central areas than in the lateral areas.

To remedy this shortcoming, according to a preferred development of the present invention, the amplification of the electrical signals in the central regions of the optical image can be greater, and in this case, for example, about a factor of 2 to 3 larger than the amplification of the electrical signals in the peripheral regions of the optical image his. Such electronic modulation by means of variable amplification factors can be carried out in every line of the optical image.

In this way, the fact that the intensity and the contrast of the scattered light in the central areas is weaker than in the lateral areas can be compensated in an elegant, electronically accomplished manner, the gain being selectable over the different areas of the optical image, that the output signal, which is directly proportional to the product of the respective scattered light intensity / contrast and the respective amplification factor, is of approximately constant intensity; This technical measure significantly improves the quality of the results that can be obtained with the present device.

According to a further development of the present device, which is essential to the invention, it is designed for the transition to an idle state. This is the case, for example, in the context of the use of the present device in mobile telephones or in motor vehicle parts, such as steering wheels Switch knobs or door locks, an advantage, because in such applications the electrical voltage required to operate the device is mostly obtained from batteries, optionally also with the help of solar collectors, so that potential savings in this regard are highly welcome by providing the device in a state of rest.

For this purpose, at least one capacitive circuit, preferably integrated in the control means, can expediently be provided, by means of which the device switches to the idle state (= so-called “sleep” mode) after a predetermined period of non-use, and by means of which the device when the front area is put on Fingers is "woken up" again on the finger support surface, that is to say goes back into an operational state; So seen, both a "sleep" function and a "wake up" function can be implemented in the present device for personal identification.

As already indicated above, the at least one light source fulfills an important function in the adaptive light control in the context of the present invention. It should be taken into account here that for the purpose of uniform illumination of the front area of the finger, in most practical applications, more than one light source is provided, for example two light sources or in particular four light sources, which can be arranged symmetrically to one another and / or which can be arranged laterally or annularly, in this case in particular essentially evenly distributed in order the finger support surface can be arranged around.

According to a development of the present device that is particularly important to the invention, the respective duration and / or the respective intensity of the light pulses emitted by the respective light source can be selectively regulated in adaptation to the ambient light conditions; In other words, this means that the respective duration and / or the respective intensity of the light pulses emitted by the individual light sources can be controlled independently of one another, in this case in particular as a function of predetermined threshold values. All of the light sources can therefore be controlled independently of one another, the respective duration and / or the respective intensity preferably being calculated individually in the evaluation module for each light source.

Not only the control of the light sources and the number of light sources, but also their arrangement plays an important role in the present invention. By arranging the light source laterally next to the finger support surface and emitting the light from the light source in the direction of the side of the finger support surface facing away from the sensor unit and intended for placing the front area of the finger, adequate, reliable results are achieved which illuminate the front area of the Fingers allows.

Here, the light falls on the front area of the finger essentially from the side, with at least part of the light entering the inside of the finger penetrates the front area of the finger and is scattered there, the scattering taking place essentially in all directions, including in the direction of the fiber-optic finger support surface; the present invention is therefore based to a certain extent on the transmitted light technology, that is to say the optical image of the fingerprint is processed as a transmitted light image.

In that, during the process of personal identification, the surface of the front area of the finger bearing the skin strips or papillary lines rests on the finger support surface, the skin strips or papillary lines "close" in places the inputs of the fibers of the finger support surface, so that in these areas of the areas closed by the skin strips or papillary lines fiber-optic finger rest surface, so-called passage light that is scattered in the interior of the front region of the finger, or only very little, reaches the finger rest surface.

In the areas of the recesses between the skin strips or papillary lines, however, more scattered light enters the fibers of the finger support surface and consequently through the finger support surface to the sensor unit, which preferably has at least one photosensitive surface and / or at least one photosensitive layer, so that an extremely sensitive instrument for identifying People is provided on the basis of the fingerprint, in particular on the areas of the skin strips or papillary lines and on the areas between the skin strips or papillary lines. The recorded optical image of the fingerprint thus passes through the fibers of the finger support surface into the sensor unit downstream of the finger support surface and is then analyzed and processed by means of the evaluation unit which is preferably downstream of the sensor unit. In this case, the data and information obtained during the analysis and during processing can preferably be collected and stored in at least one storage unit downstream of the sensor unit.

In this context, it is important that both the device according to the present invention is completely visible and the process of person identification is comprehensible and transparent for the person to be identified, since this person only touches the front area of his finger in a psychologically favorable manner Place the finger rest, but does not have to put the finger in a cavity or in an opening.

Furthermore, as an optional feature of the device that is essential to the invention, the design for life detection (so-called "life support") is to be mentioned, that is to say with the present invention because of the differences in brightness between the areas of the skin strips or papillary lines and the areas between the skin strips or papillary lines it is possible to observe or examine whether the illuminated object, for example the front area of the finger, is alive, that is to say, for example, through which blood flows and / or has a pulse. In this context, the device according to the present invention can be designed, for example, by comparing the results obtained for the two different wavelengths to determine the oxygen saturation in the blood of the front region of the finger.

With the present invention, for example, a person could only be identified as authenticated or authorized if his or her current pulse rate deviates up or down from the stored pulse rate by no more than ten percent; the pulse frequency thus becomes a further criterion for personal identification.

These additional biometric data, for example relating to the pulse rate, reduce the likelihood of errors in the identification process because they make it possible to distinguish the living finger of the person to be identified from an earlier impression of this finger. The existing data on the changes in the transparency of the front area of the finger make it possible to determine the pulse rate of the person to be identified, preferably in the evaluation unit, and the transparency curve obtained in this way is analogous to one

Use electrocardiogram (EKG) for medical purposes.

Furthermore, the device according to the present invention can also be used to determine optical images whose degree of sharpness is so high that even the sweat glands located in the front area of the finger, which are arranged differently in a person-specific manner, are clearly and clearly recognizable, so that within the scope of the operation of the present device there is the possibility of also using the sweat glands for person identification.

According to an advantageous further development of the present invention, the light source is arranged on the side of the finger support surface facing the sensor unit. This is a sufficient prerequisite for the light from the light source to be able to be emitted in the direction of the side of the finger support surface facing away from the sensor unit and intended for placing the front area of the finger, i.e. the front area of the finger of the person to be identified is illuminated from the side below.

Furthermore, the light source can expediently be arranged laterally spaced from the sensor unit. This structural separation of the light source and sensor unit is recommended insofar as, in order to achieve correct operation of the device, it should be avoided that light gets directly from the light source into the sensor unit; rather, only light should get into the sensor unit, which preferably operates on a semiconductor basis, in particular on a silicon basis, which was previously scattered in the interior of the front area of the finger and consequently carries information with regard to the skin strips or papillary lines, that is to say with regard to the fingerprint. According to a further development of the present device for person identification which is essential to the invention, the light from the light source can be laterally irradiated onto the side of the finger support surface facing away from the sensor unit and intended for placing the front area of the finger. This development is particularly suitable when the light source is preferably arranged laterally next to or already just on the side of the finger support surface facing away from the sensor unit; in this development, the light source can also be arranged to lie horizontally and emit the light "flat" onto the front area of the finger.

Optionally, the light source can be designed as a pulsed light source, which is designed for the emission of pulsed light, so that the device according to the present invention can, for example, also be battery-operated as a result of the pulsed, precisely metered light. In any case, a significant reduction in the current required to operate the device according to the present invention can be achieved because the ambient light can be used and the additionally required light can be precisely metered by means of the adaptive light control. The pulse duration of the emitted light pulses advantageously ranges from almost zero milliseconds to approximately ninety milliseconds.

In correspondence to this, the device according to the present invention can have at least one pulse generator unit for controlling the light source have, the pulse generator unit is expediently arranged between the light source and at least one control element for the sensor unit.

In order to signal the respective operating state of the device to the person to be identified, according to a preferred embodiment of the present invention at least one display device is provided for displaying the different operating states of the device. In this case, the display device can expediently have at least one single-color or different-colored light display which signals the various operating states of the device (for example green light: "device is ready for person identification" or "device has properly identified person"; red light: "device is not for Personal identification ready "or" Device did not correctly identify person ").

If the present invention is to be designed in a particularly elegant and / or compact manner in this context, it is advisable to integrate the display device into the light source and / or to design the display device and the light source uniformly.

In order, for example, to enable people with color vision problems to detect the respective operating state of the device, the display device can also use the various operating states of the device in accordance with an advantageous alternative or additional embodiment signal by at least one flashing and / or pulsating light signal. -

According to a particularly inventive development of the present invention, the light source is followed by at least one optical system. On the one hand, such an optical system has a certain protective function, that is to say the optical system prevents the person who can be identified by means of his fingerprint from touching the sensitive and easily damaged light source when placing the front area of the finger on it.

In a particularly advantageous manner, however, the optical system is designed to deflect the light emitted by the light source onto the side of the finger support surface facing away from the sensor unit and / or the light emitted from the light source on the side of the finger support surface facing away from the sensor unit uniformly and / or to distribute diffusely.

This ensures uniform illumination of the front area of the finger, which creates an informative optical image of the fingerprint originating from the front area of the finger. This is essential for a convincing functioning of the device according to the present invention.

The optical system is preferably at least one filter, at least one lens, at least one prism, at least one Light guide, designed as at least one light guide element and / or as at least one mirror, the use of the aforementioned optical elements being used alone or in combination, for example, depending on the available space or the required degree of illumination.

In order to fulfill the protective function explained above and also with regard to the light distribution, it makes sense to choose plastic for the material of the optical system. Plastic is an inexpensive and robust material that has convincing optical properties, particularly in a transparent version.

In order to fulfill the protective function explained above, it may further be expedient if at least the side of the optical system facing away from the light source is coated with at least one material which is transparent to the light of the light source, in particular material which is transparent to infrared light and / or visible light is. This protects the not infrequently sensitive optical system from damage, for example from being scratched by vandals, and / or from dirt, the cleaning of the optical system also being made easier by the coating with translucent material.

According to a particularly inventive development of the present device, there is at least one on the side of the finger support surface facing away from the sensor unit and intended to be placed on the front area of the finger advantageously ergonomically shaped finger guide is provided. Such a finger guide, which can be designed, for example, in the form of a "finger shoe", substantially simplifies the handling of the device not only in psychological but also in practical terms for a user of the device, for example a person to be identified, since the person to be identified instinctively detects through the arrangement of the finger guide, in which position and at which point the front area of the finger is to be placed on the side of the finger support surface facing away from the sensor unit for detecting the fingerprint.

If the device according to the present invention is to be developed in a particularly skillful manner, it is advisable to design the optical system as a finger guide. In this way, the advantages of finger guidance, namely, among other things, ensuring an optimal placement of the front area of the finger for capturing the fingerprint, are expediently combined with the advantages of the optical system, namely, among other things, the function as a deflection component for the light generated and the Ensure a clean, uniform illumination of the front area of the finger to be illuminated, connected.

In this context, a special mention needs to be made that the adaptive light control can be used to achieve smooth and smooth transitions for the most varied areas of the composable overall picture in a particularly advantageous manner. Therefore, through the interaction of Adaptive light control with the optional finger guidance implemented in the optical system guarantees uniform light distribution on the object to be illuminated with the greatest possible contrast.

The provisions set out above with regard to the coating of the optical system with translucent material also apply to an advantageous embodiment of the present invention, in which at least the side of the finger support surface facing away from the sensor unit has at least one material which is permeable to the light of the light source, in particular for infrared light and / or material permeable to visible light, is coated. In this case, such a coating of the finger support surface can be of essential importance in so far as an undamaged, that is, among other things, unscratched, and clean finger support surface is essential for the proper functioning of the present device for personal identification.

In the case of the optical system as well as in the case of the finger support surface, the material which is permeable to the light of the light source is, according to an advantageous embodiment, lacquer.

In relation to the present invention, it can be advantageous if the light source is a light-emitting diode (LED), the advantage of such light-emitting diodes being in particular that they are very small and consequently also in devices according to the present invention for Come in use little space is available in the course of miniaturization. The low weight, the robust design, the low operating voltage and the long service life of the light-emitting diodes are further plus points.

According to a preferred development of the present invention, the light source emits infrared light, wherein the infrared light can have a wavelength of approximately 900 nanometers, for example. The light source, which can also emit infrared light of two different wavelengths in an expedient embodiment, should have a power of, for example, about 0.1 milliwatt to about five watts, in particular a power of about two milliwatts to about, to avoid a disproportionately high heating of the device 100 milliwatts.

In order to give the present device for personal identification a certain stability, the sensor unit is expediently arranged on at least one carrier unit. This carrier unit in turn can be arranged on at least one circuit board unit.

In order to ensure proper transport of the light originating from the front region of the finger and bearing the optical image of the fingerprint through the finger support surface to the sensor unit, the fibers in the finger support surface are essentially perpendicular to the entry surface and / or to the finger surface according to an embodiment essential to the invention Exit surface of the finger rest surface oriented.

For the same purposes, the fibers in the finger rest area are arranged essentially parallel to one another in accordance with a preferred embodiment of the present invention. As an alternative to this, the fibers in the finger support surface can essentially have two directions, which are arranged at an angle to one another, according to a further development that is essential to the invention. In this case, an embodiment is preferred in which the fibers are arranged in layers in the finger support surface, the fibers within a layer being essentially parallel to one another and the fibers of mutually adjacent layers being arranged at an angle to one another.

In the aforementioned preferred embodiment, the fibers of the finger support surface arranged in one direction at an angle to the other direction are expediently provided for the transport of light to the side of the finger support surface facing away from the sensor unit, while the fibers of the finger support surface arranged in the other direction are expediently intended for transport of the optical image of the fingerprint to the sensor unit are provided.

A special mention needs in this connection that the arrangement of an optical system can be obsolete by the aforementioned preferred embodiment with two preferred directions for the fibers, as a uniform illumination of the front area of the finger by the in the one direction at an angle to the other direction fibers of the finger support surface is guaranteed.

According to a particularly inventive development of the present device for personal identification, at least some of the fibers in the finger support surface are at least partially surrounded by (light) absorbent material in the form of a coating and / or in the form of a sheath. As a result, light incident from outside through a side surface of the fibers and / or light incident from an adjacent fiber is absorbed, so that via each fiber only the light entering the finger rest area in a certain area is passed through the finger rest surface to the exit surface thereof. In this way, a change in the light pattern obtained on the entry surface of the finger support surface is reliably avoided.

According to an alternative or supplementary, also particularly inventive further development of the present device for person identification, at least some of the fibers in the finger support surface are at least partially surrounded by (light) reflecting material in the form of a coating and / or in the form of an envelope which surrounds the light in the respective fiber is preferably reflected back from the wall of this fiber into the interior of this fiber. As a result, the transport of the optical image through the finger support surface to the sensor unit is favored insofar as each fiber has only that on one transmits certain area entering the finger rest surface through the finger rest surface to the exit surface thereof. In this way, a change in the light pattern obtained on the entry surface of the finger support surface is reliably avoided.

Regardless of the aspect of omitting the optical system, there is an extension for the finger support surface that extends into the area above the light source, so that the latter is covered and protected from manual intervention.

Since the sensor unit should of course only be reached by light that carries the information relating to the optical image of the fingerprint, that is to say that is scattered from the front area of the finger, it is advisable to provide at least one opaque barrier layer within the finger contact surface, since this means that it is opaque Barrier layer is prevented that light emitted by the light source reaches the sensor unit directly, that is to say without scattering in the front region of the finger. The barrier layer can be implemented, for example, in the form of closed fibers.

The same purposes as the barrier layer within the finger support surface serve at least one opaque barrier layer, which can be provided between the light source and the sensor unit. In this context, the material of the barrier layer impermeable to the light of the light source can be, for example, lacquer. If the present device for person identification is to be further developed in a manner essential to the invention, at least one filter, preferably a linear filter, is provided in order to absorb disturbing and excess ambient light and consequently to rule out oversaturation of the sensor unit with certainty.

In other words, this means that the adaptive light control has its optimum effect if, for example, the sensor unit does not go into a supersaturation state, for example, to some extent by normal daylight, such a supersaturation state being expediently prevented precisely by the arrangement of the filter can, because with this filter, the present device for person identification can also work with an illuminance of the ambient light of more than about 3,000 lux, a realistic upper limit being an illuminance of the ambient light of about 40,000 lux. For this purpose, the filter expediently has an absorption level of about 99 percent, that is to say the light-absorbing filter acts as a "dark room" as a result (in contrast to the filter with "window" disclosed in German Offenlegungsschrift DE 44 04 918 AI, that do not offer effective protection against oversaturation and cannot function as a "darkroom").

The arrangement of the filter within the present Device for personal identification is determined by the structure, dimensions and purpose of the device. However, it seems appropriate to arrange the filter between the finger rest and the sensor unit; and / or to arrange the filter on the side of the finger support surface facing away from the sensor unit; and / or to arrange the filter on the side of the finger support surface facing the sensor unit; and / or to provide the filter within the finger support surface.

According to a particularly advantageous development of the present invention, it can be part of the adaptive light control (= ALR or ALC = "adaptive light control"), that is to say the "intelligent light control", to make the degree of absorption of the filter variable over the various areas of the optical image .

The background of this particularly advantageous further development is the fact that the intensity distribution and consequently the contrast of the light scattered inside the front area of the finger are neither uniform nor constant over the entire width of the optical image, but are lower in the central areas of the optical image than in the Edge areas of the optical image is, which is connected among other things with the fact that the at least one light source is arranged laterally next to the finger support surface and that the light from the light source is directed towards the side facing away from the sensor unit and intended for placing the front area of the finger the finger rest surface can be blasted. As a result, less light reaches the central areas covered by the front area of the finger on the side of the finger support surface facing away from the sensor unit than the lateral areas, so that the intensity and - directly proportional to this - the contrast of the scattered light in the central areas is weaker than in the side areas.

To remedy this shortcoming, according to a preferred development of the present invention, the degree of absorption of the filter in the edge regions of the optical image can be greater, and in this case, for example, by a factor of 2 to 3 and / or by about six decibels to about ten decibels greater than the degree of absorption of the filter in the middle areas of the optical image.

It is therefore an optional technical measure that is essential to the invention, in which the density of the optical filter is designed to be variable over the various areas of the optical image such that the density in the edge areas of the filter is greater, for example by a factor of 2 to 3 and / or greater by approximately six decibels to approximately ten decibels than the density of the filter in the central regions of the optical image.

As a result, the fact that the intensity and the contrast of the scattered light in the central areas are weaker than in the lateral areas can be compensated for in an elegant manner, which is accomplished by means of optical modulation is, the degree of absorption can be selected selectively over the various areas of the optical image such that the output signal, which is directly proportional to the quotient of the respective scattered light intensity / contrast and the respective degree of absorption, is of approximately constant intensity; This technical measure significantly improves the quality of the results that can be obtained with the present device.

In this context, it should not be overlooked that the optional technical measure of optical modulation set out above has the further advantage over the optional technical measure of electronic modulation by means of a gain factor that amplification of interference, such as electronic noise or the like, has especially in the middle areas of the optical image when optical modulation is excluded; on the contrary, such undesirable interferences can even be reduced by optical modulation.

In order to enable a direct detection of the light signals by the sensor unit which is not falsified by interference, an embodiment is preferred in which the sensor unit is directly adjacent to the finger support surface and / or in which the sensor unit is attached to the exit surface of the finger support surface.

The sensor unit can expediently have at least one based on CMOS technology Have component or at least one circuit based on CMOS technology (CMOS = complementary MOS).

Alternatively or in addition to this, at least one charge-coupled device or at least one charge-coupled circuit (CCD = charge coupled device) can be provided. In particular, this can be at least one single-area CCD which functions as a light-sensitive unit and which has no separate light-protected area.

In this context, the person skilled in the art will appreciate as advantageous that a semiconductor area is required in the case of CCD sensor units which corresponds to only half of the area conventionally required, since in the case of CCD sensor units the image obtained can be read out immediately in the dark phase and does not have to be , as in conventional sensor units, are transported into a light-insensitive area, which usually takes up fifty percent of the sensor area and from which it is finally read.

The image build-up and the reading of the charges take place in the light-sensitive unit in an integrated form, the process of the image build-up and the process of reading the charges being temporally separate from one another in contrast to two-area CCDs. One-area CCDs are distinguished, inter alia, by the fact that they are significantly easier and cheaper to produce than two-area CCDs, because the number of single-area CCDs Components with essentially the same dimensions of the light-sensitive unit is only half as large as in two-area CCDs.

In this context, however, it must be taken into account that single-area CCDs cannot be used with continuous or steady illumination of the object to be illuminated, since an undesired mixing of the resulting images would occur if the image construction process and the reading process were carried out simultaneously.

For this reason, as already stated above, the light source can be designed as a pulsed light source which is designed for the emission of pulsed light. In correspondence to this, the device according to the present invention can have at least one pulse generator unit for controlling the light source, the pulse generator unit advantageously being arranged between the light source and at least one control element for the sensor unit.

The person skilled in the art will appreciate in this connection as particularly advantageous that the illumination of the front area of the finger with light pulses results in a significant reduction in the instabilities and irregularities in the optical image of the fingerprint obtained and, as a result, also in the electrical signals generated.

These effects are a direct consequence of the temporally short light pulses, preferably lasting about one millisecond, the influence of the Blood flow in the front area of the finger to be examined on the quality of the optical image of the fingerprint obtained becomes a negligible size.

Furthermore, the influence of the ambient light conditions on the optical image of the skin relief is decisively reduced by the reduction in the image construction time.

Accordingly, by using the device for personal identification according to the present invention, it is possible to obtain clear and sharp optical images of the fingerprint, in which all, instead of blurry optical images, which arise when using constant lighting and an exposure time corresponding to the image lead time Information about the interior and / or the surface of the front area of the finger at a given time is included.

This improvement in the quality of the images obtained makes it possible to significantly reduce the frequency and probability of errors in person identification. It is now also possible to increase the information content of the dactyloscopic images as a result of obtaining additional biometric data, for example the peculiarities of the pulse, of the person to be identified by image sequence processing and thus to further improve the security of the person identification.

The use of pulsed light sources not only leads to Significant improvement in image quality described above, but also allows at least one camera with single-area CCDs to be used as light-sensitive units. The use of single-area CCDs enables high-quality images of larger areas to be obtained. This enlargement of the areas, together with the improvement in the stability of the optical images, leads to a further reduction in the probability of errors in the

Personal identification.

The production of single-area CCDs with a diagonal of the light-sensitive area of, for example, approximately 16 millimeters to, for example, approximately 24 millimeters and with a fiber-optic input is a technically rather uncomplicated task, which makes it possible to produce relatively simple and inexpensive devices for personal identification. Furthermore, devices according to the present invention with single-area CCDs have less information distortion than devices with other types of charge transfer.

The use of single-range CCDs in devices that work with continuous or steady lighting is not possible because the continuous or steady light falls on the CCDs not only during the image build-up phase, but also during the readout phase, and thus the charges would mix, which would make it impossible to obtain clear optical images of the skin relief of the front area of the finger. Further refinements, features and advantages of the present invention are described below in the drawing with reference to FIGS. 1 to 4C, by way of example three exemplary embodiments of the device for person identification according to the present invention are illustrated.

It shows :

Figure 1 shows a first embodiment of a

Personal identification device according to the present invention;

Figure 2 shows a second embodiment of a device for personal identification according to the present invention;

Figure 3A shows a third embodiment of a device for personal identification according to the present invention;

Figure 3B shows a section of the

Finger support surface of the device for person identification from FIG. 3A;

FIG. 3C shows the section from the finger rest area from FIG. 3B in partial elevation;

FIG. 4A is a diagram in which the contrast of the light scattered in the interior of the front region of the finger is plotted schematically over the width of the optical image; Figure 4B is a diagram in which the at

Device for personal identification from Figure 1 selected amplification of the electrical signals is applied schematically across the width of the optical image; and

Figure 4C is a diagram in which the at

Device for personal identification from Figure 2 selected absorption is applied schematically across the width of the optical image.

Identical or similar components or features of the invention are provided with identical reference symbols in FIGS. 1 to 4C.

The three exemplary embodiments of a device for personal identification by means of a fingerprint shown in FIGS. 1 to 3A serve to record and process fingerprints and can be used in any areas in which personal identification is necessary. Examples in this context include the field of computer technology, entry systems, criminalistics, medicine, protection systems in general, and the banking and finance sector.

The three exemplary embodiments of a device for personal identification by means of a fingerprint shown in FIGS. 1 to 3A are characterized in that, on the one hand, one Sufficient, reliable results, timely illumination of the front area of the finger is possible, on the other hand, however, both the device for person identification itself is completely visible and the process of person identification is comprehensible and transparent for the person to be identified.

This is realized in that the three exemplary embodiments of a device for person identification by means of a fingerprint shown in FIGS. 1 to 3A each have four light sources 10 arranged symmetrically to the sensor unit 40 for illuminating the front area of a finger (four of which are light sources 10 each in FIGS. 1 and 4) to 3A for reasons of clarity, only two are shown) and have a fiber-optic finger support surface 30 for removing an optical image of the fingerprint.

Through the finger support surface 30, the optical image of the fingerprint is transported to a sensor unit 40, in which the optical image of the fingerprint is converted into electrical signals. The sensor unit 40 is arranged on a carrier unit 50, which in turn is arranged on a circuit board unit 60.

It is crucial that the light sources 10 are arranged laterally next to the finger support surface 30 and that the light from the light sources 10 can be emitted in the direction of the side of the finger support surface 30 facing away from the sensor unit 40 and intended for placing the front region of the finger. The light falls on the front area of the finger essentially from the side, with at least some of the light penetrating into the interior of the front area of the finger and being scattered there, the scattering essentially in all directions, including in particular in Direction of the fiber optic finger rest 30 takes place; consequently, the invention illustrated with reference to FIGS. 1 to 4C is based to a certain extent on the transmitted light technology, ie the optical image of the fingerprint is processed as a transmitted light image.

Since the surface of the front area of the finger carrying the skin strips or papillary lines rests on the finger support surface 30 during the process of the person identification, the skin strips or papillary lines "close" the entrances of the fibers 310 (see FIGS. 3B and 3C) of the finger support surface 30, so that in these areas of the fiber optic finger support surface 30 which are closed by the skin strips or papillary lines, so-called passage light which is scattered or only very little in the interior of the front region of the finger reaches the finger support surface 30.

In the areas of the recesses between the skin strips or papillary lines, on the other hand, more scattered light enters the fibers 310 of the finger support surface 30 and consequently through the finger support surface 30 to the sensor unit 40, so that an extremely sensitive instrument for identifying people on the basis of the fingerprint, in particular on the basis of the areas the skin strips or Papillary lines and based on the areas between the skin strips or papillary lines is provided.

The fibers 310 in the finger support surface 30 are surrounded by (light) reflecting material in the form of a coating, which reflects the light in the respective fiber 310 back from the wall of this fiber 310 into the interior of this fiber 310. As a result, the transport of the optical image through the finger support surface 30 to the sensor unit 40 is favored to the extent that each fiber 310 only transmits the light entering the finger support surface 30 at a certain area through the finger support surface 30 to the exit surface thereof. In this way, a change in the light pattern obtained on the entry surface of the finger support surface 30 is avoided.

The optical image of the thus recorded

The fingerprint thus passes through the fibers 310 of the finger support surface 30 into the sensor unit 40 downstream of the finger support surface 30 and is then analyzed and processed by means of the evaluation unit downstream of the sensor unit 40.

Because of the differences in brightness between the areas of the skin strips or papillary lines and the areas between the skin strips or papillary lines, the invention shown in FIGS. 1 to 4C also makes it possible to observe or examine whether the illuminated object, for example the front area of the finger, lives, that is, for example, through which blood flows and / or has a pulse (so-called "life support").

Thus, with the invention illustrated in FIGS. 1 to 4C, a person can only be identified as authenticated or authorized if their current pulse rate deviates up or down by no more than ten percent from the stored pulse rate; the pulse frequency thus becomes a further criterion for personal identification.

These additional biometric data relating to the pulse beat reduce the likelihood of errors in the identification process because they make it possible to distinguish the living finger of the person to be identified from an earlier impression of this finger. The existing data on the changes in the transparency of the front area of the finger allow the pulse rate of the person to be identified to be determined mathematically and the transparency curve obtained in this way analogously to

Use electrocardiogram (EKG) for medical purposes.

Furthermore, the device according to FIGS. 1 to 3A can also be used to determine optical images whose degree of sharpness is so high that even the sweat glands located in the front region of the finger, which are arranged differently for each person, are clearly and clearly recognizable, so that during operation The device illustrated with reference to FIGS. 1 to 3A offers the possibility of also using the sweat glands for personal identification. The device according to the present invention, shown by way of example in FIGS. 1 to 3A, is completely visible, and the process of person identification is comprehensible and transparent for the person to be identified, since this person only psychologically expediently places the front area of his finger on the finger support surface 30 must put, but does not have to put the finger in a cavity or in an opening.

The invention illustrated with reference to the three exemplary embodiments shown in FIGS. 1 to 3A is characterized in that the duration and the intensity of the light pulses emitted by the light sources 10 can be regulated as a function of the ambient light conditions, i.e. adaptive light control (= ALR or ALC = "adaptive light control"), thus providing a type of "intelligent light control", by means of which the deficits in changing ambient light conditions, such as changing room lighting or changing solar radiation, can be compensated for by the ones shown in FIGS. 1 to 3A adapt three exemplary embodiments of the device or the algorithm controlling the device to the respective lighting conditions.

For this purpose, in the three exemplary devices for person identification illustrated in FIGS. 1 to 3A, a control means 40, 70 is provided for regulating the duration and the intensity of the light pulses. With this control 40, 70, which is designed as a digital signal processing unit (DSP = digital signal processor) with a microcontroller, a continuous or temporary measuring method can be carried out, with which a permanently good image quality can be determined and with which, if necessary, an optimal saturation that is matched to the contrast and depth of field short-term light pulses can be achieved, the duration and intensity of the short-term light pulses being metered exactly to the actually required amount of light.

The control means 40, 70 has a detection module 40 for detecting the ambient light conditions, the detection module 40 in the three exemplary embodiments in FIGS. 1 to 3A being embodied uniformly with the sensor unit 40.

The detection module 40 is followed by an evaluation module 70a for determining the duration and the intensity of the light pulses in adaptation to the ambient light conditions detected by the detection module 40, the evaluation module 70a being designed uniformly with an evaluation unit 70a, which is arranged downstream of the sensor unit 40 and after which will be discussed in detail.

A storage module 70b for storing threshold values intended for regulating the duration and the intensity of the light pulses is likewise connected downstream of the detection module 40, the storage module 70b being configured uniformly with at least one storage unit 70b, which is arranged downstream of the sensor unit 40 and to which subsequently is discussed in detail. If the detection module 40 has detected the respective ambient light conditions, these are evaluated and analyzed in the evaluation module 70a, a comparison being made in the evaluation module 70a with predetermined threshold values stored in the memory module 70b.

Depending on the result of this comparison, the light sources 10, which are connected to the control means 40, 70 and in this case in particular to the evaluation module 70a, are addressed by the control means 40, 70, the duration and the intensity of the light pulses emitted by the light sources 10 being indicated the ambient light conditions determined are adapted.

As a result, the light pulses can be designed dynamically and adaptively both in terms of their duration and their intensity, so that they can be used for any type of ambient light (e.g. strong sunshine, weak sunshine, dim light, diffuse light, gas light, moonlight, artificial lighting, ...) to provide the required light exposure and thus to obtain a high-contrast and deep image of the fingerprint.

In particular, with the adaptive light control illuminances from zero lux to about 40,000 lux can be realized, the latter illuminance value roughly corresponding to direct sunlight. The results that can be achieved with this adaptive light control have a contrast and depth of field increase of up to approximately eighty percent compared to conventional lighting systems with continuous light, the results using FIGS. 1 to 3A Exemplarily illustrated type of light control has the advantage that it can meter and provide the required amount of light in a time range of less than one hundred milliseconds with changing lighting conditions, so that an almost constant image quality can be obtained in all conceivable lighting conditions.

The decisive advantage of the device shown by way of example with reference to the three exemplary embodiments in FIGS. 1 to 3A can thus be seen in the "intelligent control" which, as it were, adjusts the amount of light radiated to a certain extent and adjusts it around the object to be illuminated, that is to say all around the front area of a finger, calculated separately for each area and made available, so that overexposure or underexposure in the device for person identification according to FIGS. 1 to 3A is excluded with a probability bordering on certainty.

The invention shown in FIGS. 1 to 4C also enables uniform illumination of an object, for example the front region of a finger, regardless of the thickness of the object, which, moreover, also has a more or less strong light conductivity or a more or less strong one Can have reflectivity, and regardless of whether this object is now illuminated frontally, laterally and / or from the back by stray light.

As a result, it doesn't matter at what angle and from which point light is shining towards it illuminating object is irradiated; only the duration and the intensity of the additional light required must be regulated individually for each area. The advantages of the present adaptive light control ultimately lead to the fact that a finger image can be determined without any significant change in the exposure times while maintaining the full contrast and depth of field.

As already indicated above, the control means 40, 70 provided for the implementation of the adaptive light control in FIGS. 1 to 3A has a detection module 40, an evaluation module 70a and a memory module 70b. If the detection module 40 is now embodied uniformly with the sensor unit 40 (cf. FIGS. 1 to 3A), the photosensitive surface of the sensor unit 40 can to a certain extent itself request the required amount of light for each of its areas by means of the adaptive light control works excellently, because the evaluation module 70a of the control means 40, 70 is formed uniformly with the evaluation unit 70a.

The adaptive light control is therefore able to calculate and immediately deliver the amount of light required in view of the ambient light conditions with regard to duration and intensity in the evaluation module 70a with respect to an optimal saturation for each area of the surface.

With regard to the effects of the adaptive light control, the three exemplary embodiments shown in FIGS In the present invention it is of substantial importance that a filter 90 designed as a linear filter is provided in order to absorb disturbing and excess ambient light and consequently to rule out oversaturation of the sensor unit 40 with certainty.

In other words, this means that the adaptive light control has its optimal effect in FIGS. 1 to 3A if the sensor unit 40 does not, for example, go into a state of supersaturation "by itself" as a result of normal daylight, such a state of supersaturation being precisely due to that Arrangement of the filter 90 is prevented, because the filter 90, the device exemplified with reference to Figures 1 to 3A for

Personal identification also work with an illuminance of the ambient light of more than about 3,000 lux, with a realistic upper limit being an illuminance of the ambient light of about 40,000 lux. For this purpose, the filter 90 has an absorption level of approximately 99 percent, that is to say the light-absorbing filter 90 acts as a "dark room" as a result.

The arrangement of the filter 90 within the respective device for personal identification is determined by the structure, dimensions and purpose of the device. In the first exemplary embodiment (cf. FIG. 1), the filter 90 is arranged between the finger support surface 30 and the sensor unit 40; in the second exemplary embodiment (see FIG. 2) the filter 90 on that of the sensor unit 40 facing side of the finger support surface 30 and arranged here within the finger support surface 30; and in the third exemplary embodiment (cf. FIG. 3) the filter 90 is arranged on the side of the finger support surface 30 facing away from the sensor unit 40.

As already indicated above, the light sources 10 (cf. FIGS. 1 to 3A) perform an important function in the adaptive light control in the context of the present invention. It should be taken into account here that for the purpose of uniform illumination of the front area of the finger, in the three exemplary embodiments illustrated with reference to FIGS. 1 to 3A, more than one light source is provided (four light sources in each of the three exemplary embodiments of FIGS. 1 to 3A), which are symmetrical are arranged in relation to one another and are arranged in a ring, in this case in particular essentially uniformly distributed, around the finger support surface 30.

The respective duration and the respective intensity of the light pulses emitted by the respective light source 10 can be selectively regulated in the three exemplary embodiments of FIGS. 1 to 3A in adaptation to the ambient light conditions; In other words, this means that the respective duration and the respective intensity of the light pulses emitted by the individual light sources 10 can be controlled independently of one another, in this case in particular as a function of predetermined threshold values. Thus, all light sources 10 can be controlled independently of one another, the respective duration and the respective intensity in the evaluation module 70a is calculated individually for each light source 10.

The evaluation unit 70a and the memory unit 70b have already been mentioned above. In the first exemplary embodiment (cf. FIG. 1), these are provided in a structural unit as control means 70, which is connected to the light sources 10 and via the carrier unit 50 and via the circuit board unit 60 to the sensor unit 40; in the second exemplary embodiment (cf. FIG. 2) in structural separation as control means 70, which is connected to the light sources 10 via the circuit board unit 60 and to the sensor unit 40 via the carrier unit 50 and via the circuit board unit 60; and in the third exemplary embodiment (cf. FIG. 3) integrated structurally and functionally into the circuit board unit 60.

As can be seen from FIGS. 1 to 3A, the evaluation unit 70a is arranged downstream of the sensor unit 40 and has the function of acquiring the recorded optical image of the fingerprint, which has reached the sensor unit 40 arranged downstream of the finger rest surface 30 through the fibers 310 of the finger rest surface 30 analyze and process. Here, the data and information obtained during the analysis and during processing can be collected and stored in a storage unit 70b which is also arranged downstream of the sensor unit 40.

The data and information, in particular the data, are furthermore in the storage unit 70b Fingerprint data and fingerprint information, stored by persons to be identified, the data and information calculated in an evaluation process from the current optical image of the fingerprint in the evaluation unit 70a being able to be related to and compared with the data and information stored in the storage unit 70b.

If there is a match during this comparison, the person using the device is considered to be identified, authenticated or authorized, so that, for example, access is permitted; if, on the other hand, there is no match, the person using the device is not identified, not authenticated or not authorized, so that, for example, access is denied.

In the first two exemplary embodiments of the present invention shown in FIGS. 1 and 2, the light sources 10 are each followed by an optical system 20 made of plastic and designed as a lens. On the one hand, this optical system 20 has a certain protective function, that is to say that the optical system 20 prevents the person to be identified by means of their fingerprint from touching the sensitive and easily damageable light sources 10 when the front area of the finger is placed on it.

In particular, however, the optical system 20 is designed to redirect the light emitted by the light sources 10 to the side of the finger support surface 30 facing away from the sensor unit 40 and that to diffusely distribute light emitted by the light sources 10 on the side of the finger support surface 30 facing away from the sensor unit 40.

The first two exemplary embodiments of the present invention shown in FIGS. 1 and 2 are distinguished in this context in particular by the fact that the optical system 20 is designed as an ergonomically shaped finger guide. Accordingly, a finger guide is provided on the side of the finger support surface 30 facing away from the sensor unit 40 and intended to place the front area of the finger, which is designed in the form of a finger holder and by which a user of the device, for example a person to be identified, the handling of the device is substantially facilitated not only in psychological but also in practical terms, since the person to be identified instinctively detects the position and position of the front area of the finger on the side facing away from the sensor unit 40 by the arrangement of the finger guide Side of the finger support surface 30 is to be placed to capture the fingerprint (see FIGS. 1 and 2). In this way, in the first two exemplary embodiments of the present invention shown in FIGS. 1 and 2, the advantages of finger guidance, namely, among other things, ensuring optimal placement of the front region of the finger for capturing the fingerprint, are combined with the advantages of optical system 20, namely, inter alia, the function as a deflection component for the generated light and ensuring a clean, uniform illumination of the front area of the finger to be illuminated.

In this context, a special mention needs to be made that the adaptive light control enables smooth and uniform transitions to be achieved for the most diverse areas of the overall composite picture. Thus, the interaction of the adaptive light control with the finger guidance implemented in the optical system 20 (see FIGS. 1 and 2) guarantees a uniform light distribution on the object to be illuminated with the greatest possible contrast.

In the first exemplary embodiment of the present invention shown in FIG. 1, the side of the optical system 20 facing away from the light sources 10 is coated with a material 80 which is permeable to the light of the light sources 10, that is to say with material 80 which is permeable to infrared light. This protects the not infrequently sensitive optical system 20 from damage, for example from being scratched by vandals, and / or from contamination, the cleaning of the optical system 20 also being made easier by the coating with translucent material 80 becomes .

In the same way, in the first exemplary embodiment of the present invention shown in FIG. 1, the side of the finger support surface 30 facing away from the sensor unit 40 is coated with the material which is permeable to the light from the light sources 10, that is to say with material 10 which is permeable to infrared light. Such a coating of the finger support surface 30 can be of essential importance insofar as an undamaged, that is, among other things, unscratched, and clean finger support surface 30 is essential for the proper functioning of the device for person identification shown in FIG.

Both in the case of the optical system 20 and in the case of the finger support surface 30, the material 80 which is permeable to the light from the light sources 10 is lacquer.

With regard to the first exemplary embodiment of the present invention shown in FIG. 1, it also needs to be mentioned that it is part of the adaptive light control (= ALR or ALC "adaptive light control"), that is to say the "intelligent light control", which Design the amplification of the electrical signals in the sensor unit 40 or in the evaluation unit 70a to be variable over the different areas x (cf. FIGS. 4A and 4B) of the optical image.

The background to this is the fact that the intensity distribution and consequently the contrast of the inside of the front area of the finger scattered light over the entire width x of the optical image is neither uniform nor constant, but is lower in the central regions of the optical image than in the edge regions of the optical image (cf. the diagram in FIG. 4A, in which the contrast of the inside of the front Area of the finger scattered light is applied schematically over the width x of the optical image); This is due, among other things, to the fact that the light sources 10 are arranged laterally next to the finger support surface 30 and that the light from the light sources 10 can be emitted in the direction of the side of the finger support surface 30 facing away from the sensor unit 40 and intended for placing the front region of the finger . As a result, less light reaches the central areas covered by the front area of the finger on the side of the finger support surface 30 facing away from the sensor unit 40 than the lateral areas, so that the intensity and directly proportional to this - the contrast of the scattered light in the central area Areas is weaker than in the side areas.

In order to remedy this shortcoming in the first exemplary embodiment of the present invention illustrated with reference to FIG. 1, the amplification of the electrical signals in the central regions of the optical image is greater by approximately a factor of 2 to 3 than the amplification of the electrical signals in the peripheral regions of the optical image (cf. the diagram in FIG. 4B, in which the amplification of the electrical signals selected in the device for person identification from FIG. 1 is plotted schematically over the width x of the optical image). Such electronic modulation by means of variable amplification factors is carried out in every line of the optical image.

In this way, the fact that the intensity and the contrast of the scattered light in the central areas is weaker than in the lateral areas (cf. FIG. 4A) can be compensated for electronically, the amplification being selective over the different areas x of the optical image can be chosen so that the product of each / m

Scattered light intensity / contrast (cf. FIG. 4A) and respective amplification factor (cf. FIG. 4B) is a directly proportional output signal of approximately constant intensity; This technical measure significantly improves the quality of the results that can be obtained with the first exemplary embodiment shown in FIG.

The second exemplary embodiment shown in FIG. 2 differs from the first exemplary embodiment shown in FIG. 1 not only in that a material which is permeable to the light of the light sources 10 is not applied to the optical system 20 or to the finger support surface 30, but above all in that the light sources 10 are arranged on the side of the finger support surface 30 facing the sensor unit 40, that is to say are located below the finger support surface 30 in FIG. 2.

This is a sufficient requirement for the light from the light sources 10 in the direction of the Sensor unit 40 facing away, intended for placing the front area of the finger side of the finger support surface 30 is emitted, that is, the front area of the finger of the person to be identified is illuminated from the side below.

With regard to the second exemplary embodiment of the present invention shown in FIG. 2, it also needs to be mentioned that it is part of the adaptive light control (= ALR or ALC "adaptive light control"), that is to say the "intelligent light control" To design the degree of absorption of the filter 90 to be variable over the different regions x (cf. FIGS. 4A and 4C) of the optical image.

The background to this is the fact that the intensity distribution and consequently the contrast of the light scattered inside the front region of the finger are neither uniform nor constant over the entire width x of the optical image, but rather less in the central regions of the optical image than in the edge regions of the is an optical image (cf. the diagram in FIG. 4A, in which the contrast of the light scattered in the interior of the front region of the finger is plotted schematically over the width x of the optical image); This is due, among other things, to the fact that the light sources 10 are arranged laterally next to the finger support surface 30 and that the light from the light sources 10 can be emitted in the direction of the side of the finger support surface 30 facing away from the sensor unit 40 and intended for placing the front region of the finger . Hereby less light reaches the central areas covered by the front area of the finger on the side of the finger support surface 30 facing away from the sensor unit 40 than the lateral areas, so that the intensity and directly proportional to this - the contrast of the scattered light in the central areas is weaker than in the side areas.

In order to remedy this shortcoming in the second exemplary embodiment of the present invention illustrated in FIG. 2, the density of the optical filter 90 and consequently the degree of absorption in the edge regions of the optical image are greater by about a factor of 2 to 3 or by about six decibels to about ten decibels the degree of absorption of the filter 90 in the central regions of the optical image (cf. the diagram in FIG. 4C, in which the absorption of the filter 90 selected in the device for person identification from FIG. 2 is plotted schematically over the width x of the optical image).

In this way, the fact that the intensity and the contrast of the scattered light in the central areas is weaker than in the lateral areas (see FIG. 4A) can be compensated for by means of optical modulation, the degree of absorption being selective over the different areas x of the optical image can be chosen so that the output signal, which is directly proportional to the quotient of the respective scattered light intensity / contrast (cf. FIG. 4A) and the respective degree of absorption (cf. FIG. 4C), is of approximately constant intensity; through this technical Measure is the quality of the results obtainable with the second embodiment shown in Figure 2 significantly improved.

Furthermore, the light sources 10 in the three exemplary embodiments of the present invention shown in FIGS. 1 to 3A are arranged laterally spaced apart from the sensor unit 40. This structural separation of light sources 10 and sensor unit 40 is advantageous in that, in order to achieve proper operation of the device, it is to be avoided that light comes directly from the light source 10 into the sensor unit 40; rather, only light should come into the sensor unit 40 that was previously scattered inside the front area of the finger and consequently carries information with regard to the skin strips or papillary lines, that is to say with regard to the fingerprint.

The first two exemplary embodiments shown in FIGS. 1 and 2 differ from the third exemplary embodiment shown in FIG. 3 essentially in that the fibers 310 in the finger support surface 30 are arranged essentially parallel to one another, in order to ensure that the material originating from the front region of the finger is transported properly to ensure the optical image of the fingerprint-bearing light through the finger support surface 30 to the sensor unit 40.

As an alternative to this, the fibers 310, 320 in the finger support surface 30 of the third exemplary embodiment (cf. FIGS. 3A, 3B and 3C) have essentially two directions which are under one Angles of about 45 degrees to each other are arranged. Here, the fibers 310, 320 are arranged in layers in the finger support surface 30, that is to say the fibers 310, 320 within a layer are essentially parallel to one another and the fibers 310, 320 of adjacent layers are arranged at an angle of approximately 45 degrees to one another.

Here, in the third exemplary embodiment (see FIGS. 3A, 3B and 3C), the fibers 320 of the finger support surface 30, which are arranged in one direction at an angle of approximately 45 degrees to the other direction, for transporting the light from the light source 10 onto that from the sensor unit 40 opposite side of the finger support surface 30 is provided, while the fibers 310 of the finger support surface 30 arranged in the other direction are provided for transporting the optical image of the fingerprint to the sensor unit 40.

In this context, a special mention is required that the arrangement of an optical system 20 according to FIGS. 1 and 2 can be obsolete to the extent that the configuration illustrated in FIGS. 3A, 3B and 3C with two preferred directions for the fibers 310, 320 can be obsolete in that one Uniform illumination of the front area of the finger is ensured by the fibers 320 of the finger support surface 30 arranged in one direction at an angle of approximately 45 degrees to the other direction.

Regardless of the point of view of omitting the optical system 20, the following offers itself for the Finger support surface 30 an extension, which extends into the area above the light source 10, so that the latter is covered and protected from manual intervention (see. Figures 2 and 3).

Since the sensor unit 40 is of course only to be reached by light which carries the information relating to the optical image of the fingerprint, that is to say that is scattered from the front area of the finger, in the second exemplary embodiment of the present invention shown in FIG. 2 there are two within the finger support surface 30 Barrier layers 130 are provided which are opaque to the light from the light sources 10. These barrier layers 130 prevent light emitted by the light sources 10 from reaching the sensor unit 40 directly, that is to say without scattering in the front region of the finger.

The same purposes as the barrier layers 130 within the finger support surface 30 (see FIG. 2) serve two barrier layers 140, which are provided between the light source 10 and the sensor unit 40 in the three exemplary embodiments of the present invention shown in FIGS are opaque to the light from the light sources 10.

It should also be mentioned that also in the third exemplary embodiment of the present invention shown in FIG. 3A (comparable to the first exemplary embodiment of the present invention shown in FIG. 1), the side of the finger support surface 30 facing away from the light sources 10 has a material 80 that is transparent to the light of the light sources 10, that is to say coated with material 80 that is transparent to infrared light, for example with commercially available clear lacquer. This protects the not infrequently sensitive finger support surface 30 from damage, for example from scratching by vandals, and / or from dirt, the cleaning of the finger support surface 30 also being facilitated by the coating with translucent material 80.

Furthermore, the third exemplary embodiment of the present invention shown in FIG. 3A has a display device 65 for displaying the various operating states of the device. In order to signal the particular operating state of the device to the person to be identified, the display device 65 is provided with an illuminated display which also enables people with color vision problems to detect the respective operating state of the device by means of a correspondingly flashing light signal.

Finally, the device in accordance with the third exemplary embodiment in FIG. 3A is also designed for the transition to an idle state (= so-called “sleep” mode), which creates savings potential with regard to the power consumption of the device. For this purpose, a capacitive circuit 75 integrated in the control means 40, 70 is provided, by means of which the device according to FIG. 3A switches to "sleep" mode after a predetermined period of non-use and by means of which the device according to FIG. 3A when the front area is put on of a finger on the finger support surface 30 is "woken up" again, that is, goes back to an operational state; So seen, both a "sleep" function and a "wake up" function are implemented in the device for personal identification.

Claims

EXPECTATIONS

1. Device for personal identification by means of at least one fingerprint with at least one light source (10) for illuminating and / or for shining through the front area of a finger by means of light pulses and with at least one fiber-optic finger support surface (30) for removing an optical image of the fingerprint, through which finger support surface (30) the optical image can be transported to at least one sensor unit (40) in which the optical image can be converted into electrical signals, the at least one light source (10) being arranged to the side of the finger support surface (30) and the light from the Light source (10) can be emitted in the direction of the side of the finger support surface (30) facing away from the sensor unit (40) and intended for placing the front area of the finger,

characterized ,

that the duration and / or the intensity of the light emitted by the at least one light source (10) Light pulses can be regulated depending on the ambient light conditions.

2. Device according to claim 1, characterized in that the sensor unit (40) is followed by at least one evaluation unit (70a).

3. Device according to claim 1 or 2, characterized in that the amplification of the electrical signals in the sensor unit (40) and / or in the evaluation unit (70a) is variable over the different areas of the optical image.

4. The device according to claim 3, characterized in that the amplification of the electrical signals in the central regions of the optical image is greater than the amplification of the electrical signals in the edge regions of the optical image.

5. The device according to claim 4, characterized in that the amplification of the electrical signals in the central regions of the optical image by about a factor of 2 to 3 is greater than the amplification of the electrical signals in the edge regions of the optical image.

6. The device according to at least one of claims 1 to 5, characterized in that the Sensor unit (40) is arranged at least one storage unit (70b).

7. The device according to at least one of claims 1 to 6, characterized in that at least one control means (40, 70) is provided for regulating the duration and / or the intensity of the light pulses.

8. The device according to claim 7, characterized in that the control means (40, 70) at least one detection module for detecting the ambient light conditions; at least one evaluation module for determining the duration and / or the intensity of the light pulses in adaptation to the ambient light conditions detected by the detection module; and has at least one memory module for storing threshold values intended for regulating the duration and / or the intensity of the light pulses.

9. The device according to claim 8, characterized in that the detection module is formed integrally with the sensor unit (40) and / or as part of the sensor unit (40).

10. The device according to claim 2 and according

Claim 8 or 9, characterized in that the

Evaluation module uniform with the evaluation unit

(70a) and / or as part of the evaluation unit (70a) is trained

11. The device according to claim 6 and according to at least one of claims 8 to 10, characterized in that the memory module is formed integrally with the memory unit (70b) and / or as part of the memory unit (70b).

12. The device according to at least one of claims 7 to 11, characterized in that the control means (40, 70) is designed as at least one logic component and / or as at least one logic circuit.

13. The apparatus according to claim 12, characterized in that at least one standard logic component or programmable logic (FPGA = field programmable gate array) is provided as control means (40, 70).

14. The device according to at least one of claims 7 to 13, characterized in that the control means (40, 70) is designed as at least one digital signal processing unit (DSP = digital signal processor) and / or as at least one microcontroller.

15. The device according to at least one of claims 1 to 14, characterized in that the device for the transition to an idle state is designed

16. The apparatus according to claim 15, characterized in that at least one capacitive circuit (75) is provided, by means of which the device goes into the idle state after a predetermined period of non-use.

17. The device according to at least one of claims 7 to 14 and according to claim 16, characterized in that the capacitive circuit (75) is integrated in the control means (40, 70).

18. The device according to at least one of claims 1 to 17, characterized in that more than one light source (10) is provided.

19. The apparatus according to claim 18, characterized in that four light sources (10) are provided.

20. The apparatus according to claim 18 or 19, characterized in that the light sources (10) are arranged symmetrically to each other.

21. The device according to at least one of claims 18 to 20, characterized in that the light sources (10) are arranged laterally or annularly around the finger support surface (30).

22. Device according to at least one of the

Claims 18 to 21, characterized in that the

Light sources (10) are evenly distributed around the finger support surface (30).

23. The device according to at least one of claims 18 to 22, characterized in that the respective duration and / or the respective intensity of the light pulses emitted by the respective light source (10) can be selectively regulated in adaptation to the ambient light conditions.

24. The device according to at least one of claims 18 to 23, characterized in that the respective duration and / or the respective intensity of the light pulses emitted by the individual light sources (10) can be controlled independently of one another.

25. The device according to at least one of claims 18 to 24, characterized in that the respective duration and / or the respective intensity of the light pulses emitted by the individual light sources (10) can be controlled as a function of predetermined threshold values.

26. The device according to at least one of claims 1 to 25, characterized in that the light source (10) on the sensor unit (40) facing side of the finger support surface (30) is arranged

27. The device according to at least one of claims 1 to 26, characterized in that the light source (10) from the sensor unit (40) is arranged laterally spaced.

28. The device according to at least one of claims 1 to 27, characterized in that the light from the light source (10) on the side facing away from the sensor unit (40) for placing the front region of the finger provided the finger support surface (30) is.

29. The device according to at least one of claims 1 to 28, characterized in that the light source (10) is designed as a pulsed light source.

30. The device according to claim 29, characterized in that the light source (10) is designed to emit light pulses with a pulse duration of almost zero milliseconds to about ninety milliseconds.

31. The device according to claim 29 or 30, characterized in that at least one pulse generator unit is provided for controlling the light source (10).

32. Device according to at least one of claims 1 to 31, characterized in that at least one display device (65) is provided for displaying the various operating states of the device.

33. Device according to claim 32, characterized in that the display device (65) has at least one monochrome or differently colored light display which signals the different operating states of the device.

34. Apparatus according to claim 32 or 33, characterized in that the display device (65) is integrated in the light source (10) and / or that the display device (65) and the light source (10) are formed uniformly.

35. Device according to at least one of claims 32 to 34, characterized in that the display device (65) signals the various operating states of the device by at least one flashing and / or pulsating light signal.

36. Device according to at least one of claims 1 to 35, characterized in that the light source (10) is followed by at least one optical system (20).

37. Device according to claim 36, characterized in that the optical system (20) deflects the light emitted by the light source (10) onto the side of the finger rest surface (30) facing away from the sensor unit (40) and / or that the optical system ( 20) the light emitted by the light source (10) is evenly and / or diffusely distributed on the side of the finger support surface (30) facing away from the sensor unit (40).

38. Apparatus according to claim 36 or 37, characterized in that the optical system (20) as at least one filter, as at least one lens, as at least one prism, as at least one light guide, as at least one light guide element and / or as at least one mirror is trained.

39. Device according to at least one of claims 36 to 38, characterized in that the optical system (20) is made of plastic.

40. Device according to at least one of claims 36 to 39, characterized in that at least the side of the optical system (20) facing away from the light source (10) is coated with material (80) which is permeable to infrared light and / or visible light.

41. Device according to at least one of claims 1 to 40, characterized in that on the sensor unit (40) facing away from Placing the front area of the finger side of the finger support surface (30) at least one finger guide is provided.

42. Device according to claim 41, characterized in that the finger guide is ergonomically shaped.

43. Device according to at least one of claims 36 to 40 and according to claim 41 or 42, characterized in that the optical system (20) is designed as a finger guide.

44. Device according to at least one of claims 1 to 43, characterized in that at least the side of the finger support surface (30) facing away from the sensor unit (40) is coated with material (80) which is permeable to infrared light and / or visible light.

45. Device according to claim 40 or 44, characterized in that it is the material which is permeable to infrared light and / or visible light (80) is lacquer.

46. Device according to at least one of claims 1 to 45, characterized in that the light source (10) is a light-emitting diode (LED).

47. Device according to at least one of claims 1 to 46, characterized in that the light source (10) emits infrared light.

48. Device according to claim 47, characterized in that the infrared light has a wavelength of about 900 nanometers.

49. Device according to at least one of claims 1 to 48, characterized in that the light source (10) emits infrared light of two different wavelengths.

50. Device according to at least one of claims 1 to 49, characterized in that the light source (10) has a power of about 0.1 milliwatts to about five watts.

51. Apparatus according to claim 50, characterized in that the light source (10) has a power of about two milliwatts to about 100 milliwatts.

52. Device according to at least one of claims 1 to 51, characterized in that the sensor unit (40) is arranged on at least one carrier unit (50).

53. Device according to claim 52, characterized in that the carrier unit (50) is arranged on at least one printed circuit board unit (60).

54. Device according to at least one of claims 1 to 53, characterized in that the fibers (310) in the finger support surface (30) are oriented substantially perpendicular to the entry surface and / or to the exit surface of the finger support surface (30).

55. Device according to at least one of claims 1 to 54, characterized in that the fibers (310) in the finger support surface (30) are arranged essentially parallel to one another.

56. Device according to at least one of claims 1 to 54, characterized in that the fibers (310, 320) in the finger support surface (30) have essentially two directions which are arranged at an angle (α) to one another.

57. Device according to claim 56, characterized in that the fibers (310, 320) in the finger support surface (30) are arranged in layers, the fibers (310, 320) within a layer essentially parallel to one another and the fibers (310, 320 ) mutually adjacent layers are arranged at an angle (α) to one another.

58. Apparatus according to claim 56 or 57, characterized in that the fibers (320) of the finger support surface (30) arranged in one direction at an angle (α) to the other direction for transporting light onto the surface facing away from the sensor unit (40) Side of the finger support surface (30) are provided and that the fibers (310) of the finger support surface (30) arranged in the other direction are provided for transporting the optical image of the fingerprint to the sensor unit (40).

59. Device according to at least one of claims 1 to 58, characterized in that at least some of the fibers (310, 320) in the finger support surface (30) are at least partially surrounded by absorbent material in the form of a coating and / or in the form of a sheath .

60. Device according to at least one of claims 1 to 59, characterized in that at least some of the fibers (310, 320) in the finger support surface (30) are at least partially surrounded by reflective material in the form of a coating and / or in the form of a sheath .

61. Device according to at least one of claims 1 to 60, characterized in that the finger rest surface (30) has an extension, which extends into the area above the light source (10).

62. Device according to at least one of claims 1 to 61, characterized in that at least one opaque barrier layer (130) is provided within the finger support surface (30).

63. Device according to claim 62, characterized in that the barrier layer (130) is realized in the form of closed fibers (310).

64. Device according to at least one of claims 1 to 63, characterized in that between the light source (10) and the sensor unit

(40) at least one opaque barrier layer

(140) is provided.

65. Device according to claim 62 or 64, characterized in that the material of the opaque barrier layer (130, 140) is lacquer.

66. Device according to at least one of claims 1 to 65, characterized in that at least one filter (90) is provided.

67. Device according to claim 66, characterized characterized in that the filter (90) is a linear filter.

68. Device according to claim 66 or 67, characterized in that the filter (90) is arranged between the finger support surface (30) and the sensor unit (40).

69. Device according to at least one of claims 66 to 68, characterized in that the filter (90) on the side of the finger support surface (30) facing away from the sensor unit (40) and / or on the side of the finger support surface facing the sensor unit (40) (30) is arranged.

70. Device according to at least one of claims 66 to 69, characterized in that the filter (90) is provided within the finger support surface (30).

71. Device according to at least one of claims 66 to 70, characterized in that the filter (90) has an absorption level of about 99 percent.

72. Device according to at least one of claims 66 to 71, characterized in that the degree of absorption of the filter (90) is variable over the different areas of the optical image.

73. Device according to claim 72, characterized in that the degree of absorption of the filter (90) in the edge regions of the optical image is greater than the degree of absorption of the filter (90) in the central regions of the optical image.

74. Device according to claim 73, characterized in that the absorption of the filter (90) in the edge regions of the optical image is greater by approximately a factor of 2 to 3 and / or greater by approximately six decibels to approximately ten decibels than the absorption of the filter ( 90) is in the middle areas of the optical image.

75. Device according to at least one of the

Claims 1 to 74, characterized in that the

Sensor unit (40) directly to the

Finger support surface (30) adjoins and / or that the

Sensor unit (40) is attached to the exit surface of the finger support surface (30).

76. Device according to at least one of claims 1 to 75, characterized in that the sensor unit (40) has at least one photosensitive surface and / or at least one photosensitive layer.

77. Device according to at least one of claims 1 to 76, characterized in that the Sensor unit (40) operated on a semiconductor basis

78. Device according to claim 77, characterized in that the sensor unit (40) operates on a silicon basis.

79. Device according to at least one of claims 1 to 78, characterized in that the sensor unit (40) has at least one component based on CMOS technology or at least one circuit based on CMOS technology (CMOS = complementary MOS).

80. Device according to at least one of claims 1 to 79, characterized in that the sensor unit (40) has at least one charge-coupled device or at least one charge-coupled circuit (CCD = Charge coupled device).

81. Device according to at least one of claims 1 to 80, characterized in that the device is designed for life detection (so-called "life support").

82. Device according to claim 49 and according to claim 81, characterized in that the device is designed by comparison of the results obtained for the two different wavelengths for determining the oxygen saturation in the blood of the front region of the finger. o 0

83. Device according to at least one of claims 1 to 82, characterized in that the device is battery operated.