TWI530887B - Anti-fake method of fingerprint and fingerprint recognizing apparatus - Google Patents

Description

Fingerprint anti-counterfeiting method and fingerprint identification device

The invention relates to a fingerprint identification method, in particular to a fingerprint identification method suitable for a fingerprint identification device with a photosensitive element and having a fingerprint anti-counterfeiting function.

In general, users usually set a password to control access to the computer, allow online transactions through the network, or pass through the home and company access control devices. However, these passwords may be stolen or guessed by someone who is interested. Since each person's fingerprints are unique, techniques for using fingerprints for various encryptions have become more and more widely used in daily life.

In view of the above, the current common fingerprint sensors are both capacitive and optical. FIG. 1A is a schematic diagram of a conventional optical fingerprint sensor. As shown in FIG. 1A, optical fingerprint sensor 100 includes a light source 102, a Mitsubishi mirror 104, and a camera 106. When the finger 108 presses the Mitsubishi mirror 104, the different shades of the fingerprint on the fingerprint will absorb and destroy the incident light 102-1 emitted by the light source 102, and then generate the reflected light 102-2, and then the corresponding fingerprint image is captured by the camera 106. News. FIG. 1B is a schematic diagram of a conventional capacitive fingerprint sensor. As shown in FIG. 1B, the capacitive fingerprint sensor 101 includes a wafer 101, and the wafer 101 There are a plurality of capacitive sensors 105 integrated therein. When the finger 107 presses the surface of the wafer 101, the capacitive sensor 105 senses different amounts of charge according to different shades of lines on the fingerprint, and collects these differences via the electrodes 103. The amount of charge of the value forms the corresponding fingerprint information.

With the advancement of fingerprint counterfeiting technology, fake fingerprints made of materials such as resin and silicone can easily fool the general fingerprint sensor. Therefore, the identification of the authenticity of the fingerprint has become a goal studied by those skilled in the art.

The invention provides a fingerprint anti-counterfeiting method which has better anti-counterfeiting effect than the prior art.

The present invention further provides a fingerprint identification device suitable for performing the above-described fingerprint anti-counterfeiting method.

The invention provides a fingerprint anti-counterfeiting method, which comprises the following steps: detecting a change amount of transmittance of a finger; determining whether the finger is authentic or not according to whether the detected change amount of transmittance is within a preset range; If the finger is true, fingerprint sensing is performed on the finger.

The invention further provides a fingerprint identification device, which comprises a backlight unit, a fingerprint sensing unit and a photosensitive unit. The backlight unit is configured to emit detection light. The fingerprint sensing unit is disposed adjacent to the backlight unit and is used to sense a fingerprint of the finger. The photosensitive unit is configured to sense the light intensity of the detected light or the ambient light after penetrating the finger to determine the amount of change in the transmittance of the finger. Wherein, when the finger presses the fingerprint sensing unit, the thickness of the finger changes due to different pressing pressure paths, and the detecting light or the ambient light has different penetrating power for fingers of different thicknesses and generates a change in transmittance within a preset time. . The photosensitive unit judges the authenticity of the finger according to whether the amount of change in transmittance is within a preset range, and when the finger is judged to be true, the fingerprint sensing The unit senses the fingerprint of the finger.

The invention determines the authenticity of the finger by detecting the amount of change in the transmittance of the finger and whether the amount of change in the detected transmittance is within a preset range.

100, 101‧‧‧ Fingerprint sensor

102‧‧‧Light source

102-1‧‧‧Incoming light

102-2‧‧‧ Reflected light

104‧‧‧Mitsubishi mirror

106‧‧‧ camera

107, 108, 205‧‧‧ fingers

101‧‧‧ wafer

103‧‧‧electrode

105‧‧‧Capacitive sensor

200, 400, 500‧‧‧ fingerprint identification device

201‧‧‧Printed circuit board

202‧‧‧Backlight unit

202-1‧‧‧Detecting light

203‧‧‧Finger sensing unit

204‧‧‧Photosensitive unit, photoresistor

206‧‧‧ Ambient light

T‧‧‧ timeline

V‧‧‧ voltage axis

T1‧‧‧Preset time

a, b‧‧‧ voltage value

c‧‧‧Slope

D‧‧‧voltage difference

501‧‧‧ top

502‧‧‧ bottom

503‧‧‧Connecting Department

601, 602, 603‧ ‧ steps

1A is a schematic diagram of a conventional optical fingerprint sensor; FIG. 1B is a schematic diagram of a conventional capacitive fingerprint sensor; FIG. 2 is a schematic diagram of a fingerprint identification device according to an embodiment of the present invention; FIG. 4 is a schematic diagram of a fingerprint identification device according to another embodiment of the present invention; FIG. 5 is a schematic diagram of a hardware of a fingerprint identification device according to an embodiment of the present invention; FIG. A flowchart of a fingerprint anti-counterfeiting method according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a fingerprint identification apparatus according to an embodiment of the present invention. As shown in FIG. 2, the fingerprint recognition apparatus 200 includes a backlight unit 202, a fingerprint sensing unit 203, and a photosensitive unit 204. The backlight unit 202 is configured to emit detection light (or light) 202-1. In the present embodiment, the detection light 202-1 is used, for example, to cause the finger 205 to generate fingerprint image information, instead of detecting the authenticity of the finger 205. The fingerprint sensing unit 203 is disposed adjacent to the backlight unit 202 and is used to sense the fingerprint of the finger 205, that is, the fingerprint sensing unit 203 and the backlight unit 202 are stacked. The photosensitive unit 204 is configured to sense the intensity of the light after the ambient light 206 penetrates the finger 205 to determine the amount of change in the transmittance of the finger 205. In this embodiment, the photosensitive unit 204 is disposed on both sides of the backlight unit 202 and is used for detecting The amount of change in transmittance when the ambient light 206 penetrates the fingers 205 of different thicknesses can be regarded as the photosensitive unit 204 being disposed under the fingerprint sensing unit 203. Wherein, when the finger 205 presses the fingerprint sensing unit 203, the thickness of the finger 205 changes due to different pressing pressure paths, and since the ambient light 206 has different penetrating power for the fingers 205 of different thicknesses, it will be at a preset time. The photosensitive unit 204 determines the authenticity of the finger 205 according to whether the amount of change in the transmittance is within a preset range. When it is determined that the finger 205 is true, the fingerprint sensing unit 203 is correct. The fingerprint of the finger 205 is sensed. In addition, the backlight unit 202 is preferably disposed on the printed circuit board 201 for signal communication with other electronic components (not shown) of the fingerprint recognition device 200.

In detail, the photosensitive unit 204 in this embodiment may be implemented by a photoresistor, but is not intended to limit the present invention. The photoresistor has a resistance value of, for example, 55 K ohms to 5 K ohms depending on the change in light intensity, so that the amount of change in transmittance of the finger 205 can be converted into, for example, a voltage, which will be further described below with reference to FIG. Fig. 3 is a graph showing the amount of change in transmittance of a finger according to an embodiment of the present invention. As shown in FIG. 3, the horizontal axis T is represented by a time axis, and the vertical axis V is represented by a voltage axis. Referring to FIG. 2 and FIG. 3, when the finger 205 just comes into contact with the surface of the fingerprint sensing unit 203, since the ambient light 206 is shielded by the finger 205, the resistance value of the photoresistor 204 is relatively high, thereby generating a corresponding voltage value a. . When the finger 205 continues to press the fingerprint sensing unit 203 for a preset time t1, the thickness of the finger 205 gradually becomes thinner, and the transmittance of the finger 205 is increased, thereby enabling the ambient light 206 to penetrate more easily. The finger 205 is sensed by the photoresistor 204. At this time, the resistance value of the photoresistor 204 is lowered, so that a corresponding voltage value b is generated, and the corresponding slope c can be calculated by the voltage values a and b and the preset time t1. correspond When the slope c is within the preset range, it is judged that the finger 205 is a true finger. The preset time t1 and the preset range of the corresponding slope c can be adjusted according to different design requirements, and the present invention will not be repeated herein.

Similarly, in addition to the above-described use of the voltage values a, b corresponding to the slope c of the preset time t1 to determine the authenticity of the finger 205, those skilled in the art can also determine whether the voltage difference d between the voltage values a, b is The authenticity of the finger 205 is determined by being greater than a preset threshold. Similarly, the range of the voltage difference d can also be adjusted according to different design requirements, and thus the present invention will not be described again.

In addition, since the photoresistor 204 made of different materials has different photoelectric conversion efficiencies for light sources of different wavelengths, those skilled in the art can also replace the ambient light 206 for the photoresistor 204 made of different materials. The monochromatic light having a specific wavelength is used to make the photoresistor 204 have the best photoelectric conversion efficiency, thereby further improving the anti-counterfeiting performance of the fingerprint.

FIG. 4 is a schematic diagram of a fingerprint identification device according to another embodiment of the present invention. The same reference numerals in Fig. 4 and Fig. 2 denote the same elements or signals. As shown in FIG. 4, the various components of the fingerprint identification device 400 are configured in substantially the same manner as the fingerprint recognition device 200 of FIG. 2. The main difference is that the fingerprint recognition device 400 is detected by the backlight unit 202. The authenticity of the finger 205 is determined. Therefore, the photosensitive unit 204 in the embodiment must be disposed above the fingerprint sensing unit 203, that is, the finger 205 is sandwiched between the photosensitive unit 204 and the fingerprint sensing unit 203, and thus, when the finger When the fingerprint sensing unit 203 of the fingerprint recognition device 400 is pressed, the detection light 202-1 emitted by the backlight unit 202 is sensed by the photosensitive unit 204 disposed above the fingerprint sensing unit 203. The method for determining the authenticity of the finger 205 in this embodiment is substantially the same as the foregoing, and therefore will not be described again. In order to dispose the photosensitive unit 204 above the fingerprint sensing unit 203, it is required to be different from the previous embodiment. The body configuration mode, this hardware configuration mode will be described later.

FIG. 5 is a schematic diagram of a hardware of a fingerprint identification apparatus according to an embodiment of the present invention. As shown in FIG. 5, the fingerprint recognition device 500 has a top portion 501, a bottom portion 502, and a connection portion 503. The top 501 and the bottom 502 are spaced apart from each other by a predetermined distance and form a receiving space to accommodate a finger. The connecting portion 503 is used to connect the top portion 501 and the bottom portion 502. Referring to FIG. 4 and FIG. 5 , the bottom portion 502 includes a fingerprint sensing unit 203 and a backlight unit 202 . The top portion 501 includes a photosensitive unit 204 for detecting that the detecting light 202-1 emitted by the backlight unit 202 penetrates different thicknesses. The amount of change in transmittance when the finger 205 is used.

The invention can be summarized as a fingerprint anti-counterfeiting method. FIG. 6 is a flowchart of a fingerprint anti-counterfeiting method according to an embodiment of the present invention. As shown in FIG. 6, the fingerprint anti-counterfeiting method includes steps 601-603. Step 601: Detect the amount of change in transmittance of a finger. Step 602: Determine whether the finger is authentic or not according to whether the detected amount of change in transmittance is within a preset range. Step 603: When it is determined that the finger is true, a fingerprint sensing is performed on the finger.

In summary, since the amount of change in the transmittance of the finger varies from person to person, when the fingerprint recognition device is pressed, the transmittance of the finger changes depending on the thickness of the finger. The invention measures whether the change amount of the transmittance of the finger meets the value of the preset range in the preset time by the photosensitive unit, and if the change amount of the transmittance measured by the photosensitive unit meets the value within the preset range, It is judged that this finger is a real finger, so the effect of fingerprint anti-counterfeiting can be achieved.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

601~603‧‧‧Steps

Claims (8)

A fingerprint anti-counterfeiting method is applicable to a fingerprint identification device having a photosensitive element, comprising: detecting a change in transmittance of a finger; determining whether the amount of change in transmittance is within a preset range The authenticity of the finger; and when determining that the finger is true, performing a fingerprint sensing on the finger, wherein the photosensitive element generates a voltage having a corresponding slope according to the amount of change in transmittance of the finger within a predetermined time period The value, when the absolute value of the slope is within the preset range, determines that the finger is true. The fingerprint anti-counterfeiting method according to claim 1, wherein the change in transmittance of the finger is related to a first transmittance of the finger and a second transmittance, and the photosensitive element is in the pre-preparation Setting a first voltage value according to the first transmittance and generating a second voltage value according to the second transmittance, when the difference between the first voltage value and the second voltage value is greater than a pre- When the threshold is set, it is judged that the finger is true. The fingerprint anti-counterfeiting method according to claim 1, wherein the change in transmittance of the finger is related to a change in finger thickness when the finger presses the fingerprint recognition device. A fingerprint recognition device includes: a backlight unit for emitting a detection light; and a fingerprint sensing unit disposed adjacent to the backlight unit for sensing a fingerprint of the finger; and a photosensitive unit for sensing the light intensity of the detected light or an ambient light penetrating the finger to determine the amount of change in transmittance of the finger; wherein the finger presses the fingerprint sensing unit The thickness of the finger changes due to different pressing strokes, and the detecting light or the ambient light has different penetrating power for fingers of different thicknesses to generate the transmittance change amount within a preset time. The photosensitive unit determines the authenticity of the finger according to whether the amount of change in transmittance is within a preset range. When it is determined that the finger is true, the fingerprint sensing unit senses the fingerprint of the finger, wherein the photosensitive sensor senses The unit generates a voltage value having a corresponding slope according to the amount of change in transmittance of the finger during the preset time. When the absolute value of the slope is within the preset range, determining that the finger is true. The fingerprint anti-counterfeiting method of claim 4, wherein the change in transmittance of the finger is related to a first transmittance of the finger and a second transmittance, and the photosensitive element is in the pre-preparation Setting a first voltage value according to the first transmittance and generating a second voltage value according to the second transmittance, when the difference between the first voltage value and the second voltage value is greater than a pre- When the threshold is set, it is judged that the finger is true. The fingerprint identification device of claim 4, wherein the photosensitive unit is disposed on both sides of the backlight unit and configured to detect a change in transmittance when the ambient light penetrates a finger of a different thickness. The fingerprint recognition device of claim 6, wherein the ambient light comprises at least one monochromatic light having a specific wavelength. The fingerprint identification device of claim 4, wherein the fingerprint identification device has a top portion, a bottom portion and a connecting portion, the top portion and the bottom portion are separated by a predetermined distance and form a receiving space to accommodate The finger is connected to the top portion and the bottom portion, the bottom portion includes the fingerprint sensing unit and the backlight unit disposed adjacent to each other, and the top portion includes the photosensitive unit to detect the detection light emitted by the backlight unit The amount of change in transmittance when penetrating fingers of different thicknesses.