KR100615540B1 - Information terminal with fingerprint image acquistion device - Google Patents

Abstract

The present invention relates to an information terminal for acquiring a fingerprint image by capturing a finger away from a lens by simply providing a macro function without greatly changing the configuration of a camera-informed information terminal. An image sensing means for converting an image into an electrical signal ; Mode selection means for causing a user to select one of a general subject photographing mode and a fingerprint photographing mode; When the user selects the normal subject shooting mode, it functions as a wide-angle lens for inputting the image of the general subject to the image sensing means, and when the user selects the fingerprint shooting mode, it functions as a macro lens for inputting the fingerprint image to the image sensing means. Lens means; Storage means for storing image data output from the image sensing means; And transmitting means for transmitting the image data output from the image sensing means to an external device.

Fingerprint, fingerprint authentication, fingerprint image, camera, macro, macro, mobile communication, mobile phone

Description

Information terminal with fingerprint image acquisition device {Information terminal with fingerprint image acquistion device}

1 is a schematic diagram of a conventional optical fingerprint image acquisition device.

2a to 2c is a conceptual view of the basic principle of the present invention.

Figure 3a, b is an illustration of a typical camera built-in mobile phone.

4A and 4B show a state of use of a cellular phone equipped with a fingerprint image acquisition device according to an embodiment of the present invention.

5A, 5B, 5B, 5B, 5B, 5B, 5B, 5B, 5B, 5B, 5B, 5B, 5B, 5B, 5B, BB, BB, and BB will show an exemplary embodiment of selecting a wide-angle lens and a macro lens in a mobile phone according to an embodiment of the present invention;

Figures 6a-6c is an illustration showing an embodiment of the finger support in the present invention.

7a to 7d are exemplary views showing various embodiments of the lighting apparatus of the present invention.

8A to 8D are images showing the results of each step in the process of extracting fingerprint data from the fingerprint image acquired by the fingerprint image acquisition device of the present invention.

<Description of Drawing>

An image forming prism 1, a light source 3, a condenser lens 4, an image sensor 5, a finger fingerprint 20, an image sensing element 21, a lens combination 23, a finger support 25, Lighting device 27, camera unit 101, camera lens 103, 105, fingerprint 109, ridge portion 109a, valley portion 109b, first lens 115, first lens holder 117 ), The second lens 119, the second lens holder 121, the pivot pin 123, the mobile phone body 125, the second lens holder 127, the handle 129, the pivot pin 131, fingers Support 133, light emitting diodes 135, 135a, b, c, d, light source 137, first light source 137a, second light source 137b, diffraction grating 139, first diffraction grating 139a , The second diffraction grating 139b, the diffracted light 140, the focusing lens 141, the first focusing lens 141a, the second focusing lens 141b, the parallel light 142, and the diffraction gratings 143a and 143b.

The present invention relates to a fingerprint image acquisition, and more particularly, to an apparatus for acquiring a fingerprint image by photographing a fingerprint using a camera function of an information terminal such as a mobile phone or a PDA.

Fingerprint image acquisition device is a device that obtains by comparing the input fingerprint with the fingerprint of the user registered in advance to input the fingerprint applied to the fingerprint reader used in the lock of the door or safe, access management, time and attendance, computer access control. . Fingerprint image acquisition apparatuses are roughly classified into optical and non-optical systems according to a fingerprint image acquisition method.

Optical fingerprint image acquisition device is to reflect the fingerprint image formed in the image sensing device by reflecting the light on the fingerprint placed on the image forming prism and the shape of the valley (valley) or ridge (ridge) of the fingerprint and stored in advance and It is a device for contrasting. The principle of a representative optical fingerprint image acquisition device is shown in FIG.

The fingerprint image acquisition device shown in Fig. 1 represents a device called "scattering" in optical type, and is composed of an image forming prism 1, a light source 3, a condenser lens 4, and an image sensor 5. Since light from the light source 3 is incident on the fingerprint input window 2 of the image forming prism 1 at a right angle or an angle smaller than the critical angle, light is emitted from the valley of the fingerprint not reaching the fingerprint input window 2. Since it passes through the fingerprint input window 2, it does not reach the image sensor, and the incident light is scattered by being reflected by the ridge at the ridge of the fingerprint. The scattered light is incident on the condenser lens 4 and detected by the image sensor 5. Therefore, the amount of light incident on the image sensor 5 is different depending on the valleys and ridges of the fingerprint, and eventually the image sensor 5 outputs electrical signals having different levels according to the pattern of the fingerprint. An image processor (not shown) forms an output value of the image sensor 5 as a digital signal and processes the image to recognize a fingerprint pattern by a predetermined algorithm.

As can be seen in the conventional fingerprint image acquisition device shown in Fig. 1, in the prior art, a fingerprint must be closely attached to the fingerprint input window 2 to obtain an accurate fingerprint. For example, in a state in which a fingerprint image acquisition device configured as shown in FIG. 1 is embedded in a housing having a predetermined shape and only a fingerprint input window is exposed to the outside and installed in a place requiring fingerprint recognition such as an entrance door or a computer, the user fingerprints a registered finger. It must be in close contact with the fingerprint input window of the image acquisition device to receive accurate fingerprint authentication.

On the other hand, with the recent development of digital camera technology, a model equipped with a small digital camera in an information terminal such as a mobile phone or a PDA has been developed. This is a method in which a lens and an image sensing device are built in a terminal to photograph a subject, and the captured image is stored in a memory in the terminal or transmitted to another person. In general, a digital camera mounted on an information terminal uses a wide-angle lens, and thus does not have a macro function of photographing a subject located near the focus because it is infinitely fixed.

In addition to the case where a fingerprint is acquired only when the fingerprint is in close contact with the fingerprint input window as in the conventional fingerprint acquisition apparatus, it is sometimes necessary to acquire a fingerprint image from a finger spaced apart from a fingerprint input window.

For example, there may be cases where the fingerprint cannot be in close contact with the fingerprint input window due to the space required for fingerprint authentication. In particular, an error occurs in fingerprint authentication because a remaining fingerprint remains after the fingerprint is touched on the fingerprint input window. Cases can arise and complex fingerprint authentication algorithms are needed to solve this. In addition, when a fingerprint authentication such as micropayment is to be performed in a camera built-in information terminal, which is widely used in recent years, embedding a fingerprint image acquisition device separately from the camera is disadvantageous in terms of miniaturization of a product.

Accordingly, it is an object of the present invention to provide an information terminal for acquiring a fingerprint image by photographing a finger away from a lens by simply providing a macro function without greatly changing the configuration of a camera-informed information terminal.

<Introduction>

The idea of the present invention is basically to acquire a fingerprint image by photographing a fingerprint using a camera. In the conventional case, as shown in FIG. 1, the fingerprint input window is configured as one surface of the prism so that the fingerprint input window is properly input to the image sensor through the optical device only when the fingerprint is in close contact with the fingerprint input window. On the other hand, the present invention basically relates to an apparatus for acquiring a fingerprint image by photographing a fingerprint in a spaced apart position by using a macro function of a camera.

Due to the nature of the lens in a camera, a wide-angle lens that is generally used is designed to minimize aberration when shooting infinity. In other words, the lens is designed on the assumption that the light incident on the lens is a group of parallel rays, and this assumption alone often deviates from the shooting conditions, so it is also designed based on a distance corresponding to 50 times the focal length of the lens (eg For example, about 2.5 meters for a 50mm lens). However, the performance of the lens deteriorates as the lens is taken out of the design criteria, so the quality of the image is greatly increased when the lens is photographed in close proximity to the subject with a general wide-angle lens (defined as a lens focused on a subject at a distance or more). Will fall. A macro lens (also called a macro lens) is a lens designed based on a distance of about 1/10 of a real object (for example, about 60 cm in the case of a 50 mm lens) in order to solve such a defect. It is a lens designed to obtain a clear image by attaching a subject at a close distance with high magnification. By using the macro lens, you can focus on a subject at a distance of 7 to 8 cm and shoot 1: 1 equally.

<Overview of invention>

With reference to the macro function of such a camera looks at the outline of the fingerprint image acquisition device according to the present invention.

Figure 2a shows a conceptual configuration of the fingerprint image acquisition device according to the present invention. In the configuration of FIG. 2A, the image sensing element 21 having a window for receiving an image and the fingerprint 20 of a finger at a spaced apart position focus on the image input window of the image sensing element 21. It shows the camera comprised from the lens assembly 23 which has a function.

The configuration of FIG. 2A can be implemented by a camera embedded in an information terminal such as a mobile phone. By doing so, even if a fingerprint image acquisition function is added to the camera-embedded terminal, the existing camera structure can be used as it is, so that the function can be easily added. That is, by providing a macro function to a small camera built in the terminal, it is possible to acquire not only a general subject but also a fingerprint image.

In order to apply the configuration of FIG. 2A to an information terminal such as a cellular phone, the macro lens described above should be used as the lens combination 23. Depending on the macro lens, even a subject separated by only a few mm can be clearly photographed, and thus it can be optimally applied to the fingerprint image acquisition device according to the present invention. However, in order for the fingerprint image acquisition device according to the present invention to be applied to a mobile phone with a built-in camera, the lens combination 23 does not just need to be a macro lens. It would be more desirable to have a user select a function.

On the other hand, as shown in Figure 2b, the information terminal according to the present invention may further include a finger support 25 for maintaining a constant distance between the lens combination 23 and the finger 20. The finger support 25 serves to obtain a clearer fingerprint image by preventing the shaking of the subject (ie, the finger). In addition, the finger support 25 allows the subject to be positioned at the optimum distance d from the lens assembly 23.

In addition, as shown in FIG. 2C, an illumination device 27 for illuminating the fingerprint surface of the finger may be further included to acquire a clear fingerprint image. Infrared LEDs can be used as the lighting device, which is invisible to the naked eye but is recognized as an image sensing device.

Hereinafter, one of the embodiments for implementing the technical idea of the information terminal according to the present invention.

<Example>

3A and 3B show an example of a camera-equipped cellular phone currently on the market. Figure 3a is a form of a separate camera unit 101 is attached to the side of the mobile phone body, Figure 3b shows a form of being installed directly in the mobile phone body, not a separate unit form. It can be seen that the camera lenses 103 and 105 are installed in the camera unit 101 or the body of the cellular phone. As described above, these camera lenses 103 and 105 are, of course, wide-angle lenses in which the focal length is fixed at infinity (usually, a distance of about 3 to 5 m).

There are various types of camera-equipped cellular phones in addition to those shown in Figs. 3A and 3B. In the present embodiment, an embodiment of the present invention will be mainly described with reference to the cellular phones of the type shown in Fig. 3B. However, the technical idea of the present invention can be applied to any type of mobile phone by easy design by those skilled in the art. This will become apparent from the specific embodiments described below.

When the fingerprint acquisition function is added to the camera-equipped mobile phone, the user can take a fingerprint by placing a finger in front of the camera lens 107 to which the macro function is added while holding the mobile phone in the usual manner as shown in FIG. 4A. .

In addition, the fingerprint acquisition function mobile phone according to the present invention should be provided with a mode selection function 110 that selects whether a user photographs a general subject or acquires a fingerprint image as shown in FIG. 4B. When the user selects the normal subject shooting mode 111, the subject is photographed using a wide-angle lens in the same manner as the conventional method, and the captured image data is stored in its own memory or transferred to another mobile phone by a mobile communication protocol. Transfer to PC using USB. If the user selects the fingerprint acquisition mode 113, replace the lens with a macro lens to take a photograph of the fingerprint, obtain the fingerprint data, store it in the memory of the cellular phone, transfer it to another cellular phone or a fingerprint authentication server according to the mobile communication protocol, or USB. Transfer to PC using.

As described above, the configuration of an information terminal having a fingerprint acquisition device according to the present invention is summarized as follows: image sensing means for converting an image into an electrical signal; Mode selection means for causing a user to select one of a general subject photographing mode and a fingerprint photographing mode; When the user selects the normal subject shooting mode, it functions as a wide-angle lens for inputting the image of the general subject to the image sensing means; Lens means; Storage means for storing image data output from the image sensing means; Transmission means for transmitting the image data output from the image sensing means to an external device.

As a repetitive explanation, if the fingerprint image can be acquired by the macro shooting method as shown in Figs. 4A and 4B, the problem of space utilization when the conventional optical fingerprint image acquisition device having a different configuration from the camera is incorporated in the cellular phone is solved. In addition, since the user does not have to touch the finger directly to the fingerprint input window, the user can input the fingerprint in a natural phone use pose state and there is an advantage of not leaving a residual fingerprint on the fingerprint input window.

As such, in order for the cellular phone to support the general subject mode and the fingerprint mode, the user should be able to easily replace the camera lens with a wide-angle lens or a macro lens. 5A to 5C show examples of a method in which a wide-angle lens is used during normal operation (when photographing a general subject) and the macro lens can be selected when fingerprinting is taken.

5A and 5B show a structure in which a second lens can be superimposed on an existing camera lens as needed as an example. The first lens 115 is attached to the body of the cellular phone by the first lens holder 117, and the second lens holder 121 fixing the second lens 119 is attached to the first lens holder 117. It is installed on the body of the mobile phone to be rotatable about the adjacent pivot pin 123. 5A shows a state in which a general subject is photographed using the first lens 115 as a wide-angle lens when the user selects the general subject photographing mode. When the user selects the fingerprint acquisition mode, the second lens holder 121 is rotated to overlap the first lens holder 117 as shown in FIG. 5ab. In this way, the first lens 115 and the second lens 119 work together to perform a macro function so that macro shooting can be performed.

5B and 5B show side cross-sectional views of examples of other structures in which a second lens can be superimposed on an existing lens as needed. The first lens 115 is fixed to the first lens holder 117 and installed in the cellular phone body 125, and the second lens holder 127 fixing the second lens 119 is the first lens. It is installed to be slid relative to the mobile phone body 125 in a position adjacent to the holder 117. When taking a general subject as shown in FIG. 5B, the knob 129 of the second lens holder 127 is pushed to a position where the second lens 119 does not overlap with the first lens 115. As shown in 5bb, the handle 129 of the second lens holder 127 is pushed in the opposite direction so that the second lens 119 overlaps with the first lens 115. Here too, the first lens 115 and the second lens 119 work together to perform a macro function, thereby allowing macro photography.

5ca and cb show a structure similar to that of a conventional zoom function as another example. The first lens 115 is fixed to the mobile phone body 125 and the second lens 119 is installed on the front surface of the first lens 115 to be horizontally moved so that the distance to the first lens 115 is adjusted. This is possibly installed. When the general subject photographing mode is selected, as shown in FIG. 5C, the second lens 119 is moved close to the first lens 115 to act as a wide-angle lens to form an image of a general subject on the image sensing means. When the fingerprint photographing mode is selected, the second lens 119 is moved away from the first lens 115 as shown in FIG. 5cb to act as a macro lens to form a fingerprint image on the image sensing means.

In the above three embodiments, the rotation or reciprocation of the second lens may be performed manually, but may also be performed by electric power by a small motor or a solenoid. Since the rotation or reciprocation of the second lens is implemented by electric motors, it will be obvious to those skilled in the art, and the description thereof will be omitted. In addition, in addition to the above three embodiments will be able to select a wide-angle function and a macro function of the camera lens in various ways within the technical scope of the present invention.

On the other hand, as described with reference to Figure 2b in <Overview of the invention>, if the finger is in a position away from the macro lens, the finger is shaken may cause a problem that can not obtain a clear fingerprint image to prevent this Finger support can be installed.

Specific embodiments of the finger support are shown in FIGS. 6A-6C. That is, the finger support 133 is installed on a part of the body of the cellular phone (preferably near the camera lens 107) so as to rotate about the pivot pin 131. The finger support 133 is installed to be rotatable by the pivot pin 131 installed on the side of the mobile phone, and is composed of a support rod having a length substantially equal to the focal length of the macro lens formed by the first lens and the second lens. It is preferable.

6A and 6B, the finger support 133 is normally placed in close contact with the side of the mobile phone so as not to interfere with a call and general subject shooting, and the finger is taken at a certain distance (focal length of the close-up lens) during fingerprint shooting. Spaced apart and has a structure that can be rotated to rise to the front of the mobile phone body in order to prevent shaking of the finger. The actual use state of the finger support 133 is shown in Fig. 6C. By setting the finger support 133 to put a finger on it can maintain a constant distance from the camera lens 107 and can prevent the shaking of the finger.

Rotation of the finger support 133 may be made simply by manual, but may also be made of electric by a small motor or a solenoid. This mode of operation is obvious to those skilled in the art.

In addition, as described with reference to FIG. 2C in <Overview of the Invention>, the mobile phone according to the embodiment of the present invention further includes an illumination device that illuminates the fingerprint surface of the finger to acquire a clear fingerprint image. desirable.

Referring to FIG. 7A, a light emitting diode is disposed around the second lens 119 in the second lens holder 121 or 127. The light emitting diode may be an infrared LED or a visible light LED, and other light emitting means other than the light emitting diode may be used.

7B shows four light emitting diodes 135a, b, c, and d installed in the second lens holder 121 or 127. In the case where one light emitting diode is installed as shown in FIG. 7A, only a portion of the fingerprint image is bright and other portions are shaded because the light is not uniformly illuminated on the round finger fingerprint surface. By installing a plurality of light emitting diodes as shown in Fig. 7b, it is possible to uniformly illuminate all fingerprint surfaces of round fingers.

On the other hand, in the case of Fig. 7A, the light emitting diodes can be controlled to be turned on at all times when the fingerprint is photographed. However, when a plurality of light emitting diodes are provided as shown in Fig. 7B, each light is sequentially flashed to acquire a partial image of the fingerprint. The entire fingerprint image may be obtained by synthesizing the obtained partial image. Since the image acquisition method in this manner is well known, a detailed description thereof will be omitted.

In addition to the illumination method of Figs. 7A and 7B, an illumination method such as Figs. 7C and 7D is also possible. Fundamentally, the fingerprint of a finger is a curved subject formed on a convex curved surface, not a flat surface, so that illumination cannot be uniformly radiated across all the fingerprint surfaces. This results in a large contrast difference between the center of the fingerprint and its periphery. In most cases, this problem can be compensated to some extent by brightening the light, but in the present invention, it is difficult to brighten the light above a certain level in terms of the size of the light source driving power or the physical size of the light source. Therefore, as a countermeasure against this, embodiments as shown in FIGS. 7C and 7D may be implemented.

FIG. 7C illustrates that the light exiting from the light source 137 is first diffracted by the diffraction grating 139 instead of directly illuminating the fingerprint 109, and then the light 140 diffracted and dispersed in multiple directions is focused. The concept of irradiating the fingerprint 109 by making it almost parallel light 142 as 141 is shown. In the case of direct irradiation by a single light source, the contrast difference between the regions to which light is irradiated is large, but as in the present embodiment, light is diffused by the diffraction grating 139 and the diffused light is fingerprinted by the focusing lens 141. By focusing and irradiating the surface, the contrast of light can be made more uniform in the amount of light over the entire fingerprint surface.

FIG. 7D is a further development of the embodiment of FIG. 7C, which shows a plurality of systems of FIG. 7C installed on both sides of the fingerprint surface. However, the diffraction gratings 139a and 139b are arranged such that the diffraction gratings 143a and 143b are shifted from each other by a predetermined angle. In FIG. 7D, the light source system on the left side is composed of the first light source 137a, the first diffraction grating 139a, and the first focusing lens 141a as in the embodiment of FIG. 7C, and the system on the right side is the second light source 137b. ), A second diffraction grating 139b and a second focusing lens 141b, and simultaneously irradiate light onto both surfaces of the fingerprint 109. As an effect of the present embodiment, since the amount of light irradiated to the fingerprint increases as compared with the embodiment of Fig. 7C, it is natural that a brighter subject environment can be created, but not only this embodiment is designed to achieve the following effects.

That is, since the diffraction bals 143a and 143b of the first diffraction gratings 139a and the second diffraction gratings 139b on both sides are arranged at a predetermined angle, the first diffraction grating 139a and the second diffraction grating 139b are disposed. When each diffracted light is irradiated to the fingerprint at, the constructive or destructive interference phenomenon due to the wave nature of the light occurs. By using such interference phenomenon, the ridge portion 109a of the fingerprint 109 may be irradiated with light waves brightened by reinforcement interference and the light waves darkened by offset interference with the valley portions 109b of the fingerprint 109b. By doing so, the contrast between the valleys and the ridges of the fingerprint can be further emphasized, and as a result, the sharpness and contrast of the photographed fingerprint image can be increased.

The embodiments described above do not limit the technical scope of the present invention as an example of implementing the technical idea of the present invention. The technical scope or scope of the present invention is to be determined by reasonable interpretation of the appended claims.

8A to 8D illustrate a fingerprint image photographed by the fingerprint image acquisition device according to the present invention and a process of extracting fingerprint data therefrom. Figure 8a shows the original image of the fingerprint image taken, Figure 8b is binary data obtained by binarizing the fingerprint image, Figure 8c shows the fingerprint image converted to a line through the thinning process of the binarized image, Figure 8d is a predetermined It represents the fingerprint data (minutiae) extracted by the algorithm. 8A to 8D show that the apparatus of the present invention exhibits inferior characteristics compared to the conventional close-type fingerprint image capturing apparatus. According to the present invention, since it is not necessary to contact the finger fingerprint unit with the fingerprint input window in order to acquire a fingerprint image, fingerprint authentication can be performed in any case, and there is no fear that residual fingerprints remain in the fingerprint input window. This is reinforced. In addition, it is possible to easily add a fingerprint acquisition function without increasing the size of the recent camera-embedded mobile phone terminal.

Claims (15)

In the information terminal which has a camera which photographs a subject, Image sensing means for converting an image into an electrical signal; Mode selection means for allowing a user to select one of a normal subject mode and a fingerprint mode; When the user selects the fingerprint recording mode, the second lens to take a macro shot of the user's fingerprint and input it to the image sensing means, and if the user selects a normal subject shooting mode to shoot a normal subject to input to the image sensing means Lens means including a first lens, Transmission means for transmitting the fingerprint and the subject image data output from the image sensing means to the outside; And a finger support means for spaced apart a finger having a fingerprint photographed by the second lens of the lens means a predetermined distance. delete delete delete delete delete delete delete delete The method according to claim 1, wherein the finger support means is composed of a support rod of a length substantially the same as the focal length of the lens means, rotatably installed by a pivot pin installed on the side of the information terminal, When shooting a general subject, the support rod is close to the side of the mobile phone. An information terminal having a fingerprint image acquisition device, characterized in that the support rod rotates about a pivot pin to protrude toward the front side of the mobile phone so that a finger can be placed upon fingerprint photographing. The information terminal according to claim 10, wherein the supporting rod is rotated manually or by electric motor. delete delete The method of claim 1, further comprising a lighting means for illuminating the fingerprint surface of the finger when the fingerprint is photographed, the lighting means is And a light source, a diffraction grating for diffracting light emitted from the light source, and a focusing lens for focusing the light diffracted and dispersed at the diffraction grating to produce substantially parallel light to be irradiated to the fingerprint. Information terminal provided with. The method of claim 1, further comprising a lighting means for illuminating the fingerprint surface of the finger when the fingerprint is photographed, the lighting means is The first light source, a first diffraction grating arranged to diffract the light from the first light source and the diffraction grating is positioned in the first direction, and the first diffraction grating are focused on substantially parallel light by focusing the diffracted light diffracted and scattered in multiple directions. A first lighting unit comprising a first focusing lens to irradiate a fingerprint to make a light; A second diffraction grating arranged so as to diffract the second light source and the light from the second light source, the diffraction grating being positioned in the second direction so as to deviate a predetermined angle from the first direction, and diffracted and dispersed in multiple directions in the second diffraction grating It consists of a second lighting unit consisting of a second focusing lens for focusing the light so as to make a substantially parallel light to be irradiated to the fingerprint, By using the interference phenomenon between the light emitted from the first and second lighting units, the light waves brightened by the interference of the ridges of the finger fingerprint are irradiated and the light waves darkened by the offset interference are irradiated to the valleys of the fingerprint. An information terminal comprising a fingerprint image acquisition device.

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