CN104751103A - Finger fingerprint reading system and fingerprint reading method - Google Patents

Abstract

The invention discloses a finger fingerprint reading system and a fingerprint reading method. The lens module has a detection unit, an image acquisition unit, a liquid lens unit, and an illumination unit. The control module is electrically connected to the lens module to control the elements in the lens module. When the detection unit detects a starting signal, the control module starts the image acquisition unit, the liquid lens unit and the illumination unit, the liquid lens unit modulates the focusing distance to scan the finger fingerprints from far to near, the image acquisition unit continuously acquires a plurality of finger fingerprint image photos through the process of modulating the focusing distance from far to near by the liquid lens unit, and the signal processing module selects a photo focused correctly from the finger fingerprint image photos acquired by the image acquisition unit and converts the photo focused correctly into a fingerprint image.

Description

Fingerprint reading system and fingerprint reading method

technical field

The invention relates to a fingerprint reading system and method, in particular to a non-contact fingerprint reading system and method.

Background technique

Electronic products for personal use, such as computers or mobile phones, usually contain personal data stored inside. Usually, in order to prevent others from obtaining personal data, a password lock is set up, and a preset password is required to enter and use the electronic product during use. However, this method of inputting the password is still very easy for others to obtain the password through other means, so that the personal data can be obtained by others.

Therefore, another contact-type fingerprint reader is developed to identify the user through the fingerprint identification function, which destroys the condition of total reflection through the contact of the fingerprint protrusion and the mirror surface of the prism, so that light and dark fingerprint photos can be obtained. However, this kind of contact fingerprint reader is expensive and bulky due to the high cost of the prism, and the mirror surface of the prism needs special surface treatment to prevent scratches or corrosion from damaging the glass surface due to the contact with the finger, and the dirt on the finger or Fingerprints will remain on the surface of the prism, making subsequent identification difficult and need to be cleaned. In addition, contact-type fingerprint readers cannot distinguish fake fingerprints.

In addition, although there are also non-contact fingerprint readers, traditional non-contact fingerprint readers usually need to use a macro lens for the camera lens in order to obtain clear fingerprint photos, and the shooting distance must be close enough to Getting a good enough magnification to have a clear photo of a finger print means that the photo has a shallow depth of field, must either have a definite finger rest mechanism to hold the finger in place or require an expensive high-end macro lens to get Optical effect of close up deep depth of field.

To sum up, the present inventor feels that the above-mentioned defects can be improved, and Naite devoted himself to research and combined with the application of theories, and finally proposed an invention with reasonable design and effective improvement of the above-mentioned defects.

Contents of the invention

In view of the above problems, the present invention provides a fingerprint reading system and method, which can avoid the problems caused by the aforementioned prior art through the non-contact fingerprint reading system and method.

In order to achieve the above object, one embodiment of the present invention provides a fingerprint reading system, which includes: a lens module, a control module and a signal processing module. The lens module has a detection unit, an image acquisition unit, a liquid lens unit and an illumination unit. The control module is electrically connected to the lens module to control the image acquisition unit, the liquid lens unit and the lighting unit. Wherein, when the detection unit detects an activation signal, the control module activates the image acquisition unit, the liquid lens unit and the lighting unit, and the liquid lens unit modulates the focus distance from far to near to scan the finger fingerprint, and the image acquisition The unit continuously acquires a plurality of fingerprint image photos through the process of modulating the focus distance of the liquid lens unit from far to near, and the signal processing module selects one of the fingerprint image photos acquired by the image acquisition unit with the correct focus photo, and convert that properly focused photo into a fingerprint image.

Another embodiment of the present invention provides a fingerprint reading method, including the following steps: detecting an object within the reading range; determining the attribute of the object; activating a lighting unit; activating an image acquisition unit and a liquid lens unit ; Modulate and scan the focusing distance of the liquid lens unit from far to near; Obtain multiple continuous photos of the liquid lens unit from far to near; Close the image acquisition unit, the liquid lens unit and the lighting unit; Select one from the image Acquiring a photo with correct focus in the continuous photos obtained by the image acquisition unit; and converting the photo with correct focus in the continuous photos obtained by the image acquisition unit into a picture.

Another embodiment of the present invention provides a method for reading fingerprints, including the following steps: detecting an object within the reading range; judging the attribute of the object; activating a lighting unit, wherein the lighting unit is illuminated for the first time; activating An image acquisition unit and a liquid lens unit; modulate and scan the focusing distance of the liquid lens unit from far to near; acquire multiple continuous photos of the liquid lens unit from far to near; illuminate the lighting unit for the second time; modulate and scan the liquid Focusing distance of the lens unit from far to near; acquiring a plurality of continuous photos of the liquid lens unit from far to near; closing the image acquisition unit, the liquid lens unit and the lighting unit; selecting one from the image acquisition unit A photo with correct focus in the continuous photos; and converting the photo with correct focus in the continuous photos obtained from the image acquisition unit into a picture.

The beneficial effects of the present invention may lie in that the fingerprint reading system and method provided by the embodiments of the present invention can be composed of a lens module, a control module and a signal processing module, so that the fingerprint reading system of the present invention has automatic The activated mechanism can eliminate the problem of recognition error caused by finger movement.

In order to further understand the features and technical content of the present invention, please refer to the following detailed description and accompanying drawings of the present invention. However, the accompanying drawings are for reference and illustration only, and are not intended to limit the present invention.

Description of drawings

FIG. 1 is a schematic block diagram of a fingerprint reading system according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of the principle of focal plane scanning.

FIG. 3 is a schematic diagram of the steps of the fingerprint reading method according to the second embodiment of the present invention.

FIG. 4 is a schematic diagram of the steps of the fingerprint reading method according to the third embodiment of the present invention.

【Symbol Description】

Fingerprint Reading System F

Lens module 1

Detection unit 11

Image acquisition unit 12

Liquid lens unit 13

Lighting unit 14

Control Module 2

Signal processing module 3

Depth of Field 1 R1

Depth of Field 2 R2

Depth of Field 3 R3

Depth of Field 4 R4

Detailed ways

[First embodiment]

Please refer to FIG. 1, the first embodiment of the present invention provides a fingerprint reading system F, which includes a lens module 1, a control module 2 and a signal processing module 3, wherein the lens module 1, control module 2 and The signal processing modules 3 are electrically connected to each other.

First, as shown in FIG. 1 , the lens module 1 has a detection unit 11 , an image acquisition unit 12 , a liquid lens unit 13 and an illumination unit 14 . The control module 2 controls the image acquisition unit 12 , the liquid lens unit 13 and the lighting unit 14 . Wherein, when the detection unit 11 detects the start signal, the control module 2 will start the image acquisition unit 12 , the liquid lens unit 13 and the lighting unit 14 . For example, the activation signal may be that the detection unit 11 detects the correct shape of the finger, the correct color of the finger, or the finger occupies a predetermined obtainable area, for example, the finger occupies 1/3 or 1/2 of the entire image captured by the image acquisition unit 12 area, or the position of the finger can be detected by active detection elements, such as general infrared scanning, ultrasonic detector or radar, but the present invention is not limited to this example. Through the detection of the detection unit 11, the finger and fingerprint reading system F can have an automatic start-up mechanism.

After the image acquisition unit 12 , the liquid lens unit 13 and the lighting unit 14 are activated, the lighting unit 14 irradiates the finger, so that the fingerprint on the finger can form a strong light-dark contrast with the background. For example, the light source of the lighting unit 14 may be white light, infrared light, ultraviolet light or other monochromatic light sources.

At the same time, the liquid lens unit 13 modulates the focusing distance from far to near to scan the finger and fingerprint. The image acquisition unit 12 continuously acquires a plurality of finger fingerprint image photos through the liquid lens unit 13 during the process of modulating the focus distance from far to near, and transmits the acquired plurality of continuous photos to the signal processing module 3 . Please refer to Figure 2 at the same time, which is a schematic diagram of the scanning principle of the focal plane. The short vertical line in the figure represents the focal plane, and the upper horizontal line represents the depth of field. Generally speaking, the closer the focal plane is to the image acquisition unit 12 , the shallower the depth of field is. In order to solve the problem of difficulty in focusing in close-range photography, and the user does not need to fix his fingers at a specific position, the present invention adopts the mechanism of liquid lens unit 13 to scan the focal plane to continuously obtain photos of different focal planes from far to near. The modulation amount design of the liquid lens unit 13 enables continuous photos to cover the set shooting distance.

For example, R1 in depth of field 1 in Figure 2 is the depth of field when the focus distance is 2 cm, R2 in depth of field 2 is the depth of field when the focus distance is 2.5 cm, R3 in depth of field 3 is the depth of field when the focus distance is 3.5 cm, and depth of field R4 of 4 is the depth of field when the focusing distance is 5 cm. The liquid lens unit 13 modulates the focusing distance from far to near, and the distance for fingerprint scanning is between 10 centimeters and 1 centimeter. The most preferred scanning range is between 5 centimeters and 2 centimeters, and the scanning time for fingerprint scanning is less than 0.5 seconds , more preferably the scan time is less than 0.3 seconds. The image acquisition unit 12 acquires 3 to 10 fingerprint image photos through the liquid lens unit 13 , more preferably 4 to 6 images, and transmits the acquired fingerprint image photos to the signal processing module 3 . Among the captured photos, there must be a photo with correct focus, and because the liquid lens unit 13 has a fast adjustment time for the focus plane (at the level of <10ms), the time to complete the entire scanning distance is not more than 0.5 seconds, thereby eliminating the need for fingers Blurred photos caused by shaking. Therefore, the finger print reading system of the present invention can relax the restriction on the position of the finger to 10 cm to 1 cm, and relax the freedom of the user to place the position of the finger.

Then the signal processing module 3 selects one of the photos with correct focus from the fingerprint image photos obtained by the image acquisition unit 12, and then performs image processing on the photo with correct focus, first detects the position of the finger in the photo, and then Remove the background other than the fingers, strengthen the contrast, do negative processing, remove noise, etc., and finally convert the photo format into a standard fingerprint image and send it to the fingerprint recognition software for fingerprint comparison. For example, the signal processing module 3 may be a computer, so that the image judgment and image processing are performed by the computer. In addition, the signal processing module 3 and the control module 2 can be embedded systems, which are similar in function to computers, and can complete fingerprint identification.

The finger and fingerprint reading system F provided by the first embodiment of the present invention can firstly determine whether a finger is detected to be within the reading range of the finger and fingerprint reading system F through the detection unit 11, and then start the lighting unit 14. This avoids the problem that the lighting unit 14 is already activated because the finger is not placed within the reading range of the fingerprint reading system F, thereby generating glare and glare, which affects the user's sight. And when the fingerprint reading system F does not detect the activation signal, the lens module 1 can be used as a general camera module, which can be used as a face camera or a video camera.

[Second Embodiment]

Please refer to FIG. 3 , the second embodiment of the present invention provides a fingerprint reading method F200, which includes the following steps. As shown in step S200 , to detect whether an object is within the reading range, for example, an active detection element, such as a common infrared scanner, an ultrasonic detector, or a radar, can be used to determine whether the object is within the reading range. As shown in step S202, it is then judged whether the attribute of the object is a finger, wherein the attribute of the object can be determined by judging whether the object is a correct finger shape, a correct finger color, or whether the finger occupies a predetermined obtainable area. For example, it can be determined first that the object occupies 1/3 or 1/2 of the area of the entire image captured by the image acquisition unit 12 , and then it can be determined whether it is a correct finger shape or finger color.

As shown in step S204, if the object is judged to be a finger, the lighting unit 14 is activated to focus the lighting light on the fingerprint of the finger, and the fingerprint on the finger and the background can form a strong light and dark contrast through the lighting unit 14 irradiating the finger. For example, the light source of the lighting unit may be white light, infrared light, ultraviolet light or other monochromatic light sources. Next, as shown in steps S206 , S208 and S210 , the image acquisition unit 12 and the liquid lens unit 13 are activated, and the liquid lens unit 13 modulates the focusing distance from far to near to scan the fingerprint. The image acquisition unit 12 continuously acquires a plurality of finger fingerprint image photos through the liquid lens unit 13 during the process of modulating the focus distance from far to near, and transmits the acquired plurality of continuous photos to the signal processing module 3 . For example, the liquid lens unit 13 modulates the focus distance from far to near, and the distance for fingerprint scanning is between 10 centimeters and 1 centimeter, and the most preferred scanning range is between 5 centimeters and 2 centimeters for scanning fingerprints. The time is less than 0.5 seconds, more preferably the scanning time is less than 0.3 seconds. The image acquisition unit 12 acquires 3 to 10 fingerprint image photos through the liquid lens unit 13 , more preferably 4 to 6 images, and transmits the acquired fingerprint image photos to the signal processing module 3 . Among the photos obtained, there must be a photo with correct focus, and because the liquid lens unit 13 has a fast adjustment time for the focus plane (at the level of <10ms), the time to complete the entire scanning distance is not more than 0.5 seconds, thereby eliminating the need for fingers Blurred photos caused by shaking.

Next, as shown in steps S212 and S214, after the interception is completed, the image acquisition unit, the liquid lens unit and the lighting unit are turned off, and a photo with correct focus is selected from the continuous photos obtained by the image acquisition unit through the signal processing module 3, Then do image processing on this photo with correct focus, first detect the position of the finger in the photo, then remove the background other than the finger, and strengthen the contrast, do negative film processing, remove noise, etc., finally, as shown in step S216, convert this A photo with correct focus is in the format of a standard fingerprint picture and then sent to the fingerprint identification software for fingerprint comparison.

The fingerprint reading method F200 provided by the second embodiment of the present invention can first determine whether an object is detected within the reading range through the detection step, and then determine that the object is a finger before activating the lighting unit 14, which can avoid the The lighting unit 14 is already activated when the finger is not placed within the reading range, thereby generating glare and glare, affecting the user's line of sight. And when the start signal has not been detected, the lens module can be used as a general camera module, which can be used as a face camera or a video camera.

[Third embodiment]

Please refer to FIG. 4, the third embodiment of the present invention provides a fingerprint reading method F300. From the comparison between FIG. 4 and FIG. The different light rays emitted by the unit 14 make the fingers have different display effects under different light source environments, and then the signal processing module 3 judges whether the obtained fingerprint is a fingerprint of a fake finger.

Firstly, as shown in step S300 , it is detected whether an object is within the reading range, for example, an active detection element, such as a general infrared scanner, ultrasonic detector or radar, can be used to determine whether the object is within the reading range. Next, as shown in step S302, it is determined whether the attribute of the object is a finger, wherein the attribute of the object can be judged by judging whether the object is a correct finger shape, a correct finger color, or whether the finger occupies a predetermined available area. For example, it can be determined first that the object occupies 1/3 or 1/2 of the area of the entire image captured by the image acquisition unit 12 , and then it can be determined whether it is a correct finger shape or finger color.

As shown in step S304, if the object is judged to be a finger, the lighting unit 14 is activated to focus the lighting light on the fingerprint of the finger, and the fingerprint on the finger can form a strong contrast with the background by illuminating the finger through the lighting unit 14 . For example, the light source of the lighting unit may be white light, infrared light, ultraviolet light or other monochromatic light sources. According to the third embodiment of the present invention, in order to distinguish whether it is a real finger or a fake finger, the light emitted by the lighting unit for the first time is white light, so that the finger print is in a white light environment.

Next, as shown in steps S3061 , S3081 and S3101 , the image acquisition unit 12 and the liquid lens unit 13 are activated, and the liquid lens unit 13 modulates the focus distance from far to near to scan the fingerprint. The image acquisition unit 12 continuously acquires a plurality of finger fingerprint image photos through the liquid lens unit 13 during the process of modulating the focus distance from far to near, and transmits the acquired plurality of continuous photos to the signal processing module 3 . For example, the liquid lens unit 13 modulates the focus distance from far to near, and the distance for fingerprint scanning is between 10 cm and 1 cm, and the most preferred scanning range is between 5 cm and 2 cm for scanning fingerprints. The time is less than 0.5 seconds, more preferably the scanning time is less than 0.3 seconds. The image acquisition unit 12 acquires 3 to 10 fingerprint image photos through the liquid lens unit 13 , more preferably 4 to 6 images, and transmits the acquired fingerprint image photos to the signal processing module 3 .

Next, as shown in steps S3062, S3082, S3102, and S312, after the fingerprint image photo obtained by the first illumination is transmitted to the signal processing module 3, the light emitted by the illumination unit for the second illumination is red light, near-infrared light, etc. Light or other monochromatic light sources, at this time, the liquid lens unit 13 modulates the focus distance to scan the fingerprint from far to near. The image acquisition unit 12 continuously acquires a plurality of finger fingerprint image photos during the modulation of the focus distance from far to near through the liquid lens unit 13, and transmits the acquired multiple continuous photos to the signal processing module 3, and turns off the image. An acquisition unit 12 , a liquid lens unit 13 and an illumination unit 14 .

Then, as shown in step S314, through the multiple consecutive photos acquired by the first illumination and the second illumination and transmitted to the signal processing module 3, one of the consecutive photographs acquired by the image acquisition unit 12 is selected to be correctly focused. Then take this photo with correct focus for image processing, first detect the position of the finger in the photo, then remove the background other than the finger, and strengthen the contrast, do negative film processing, remove noise, etc. Finally, as shown in steps S316 and S318, convert the correctly focused photo format into a standard fingerprint picture, and compare the photos obtained by the first lighting and the second lighting through the signal processing module 3 to determine whether the finger is a real finger or fake finger.

The fingerprint reading method F300 provided by the third embodiment of the present invention can first determine whether an object is detected within the reading range through the detection step, and then determine that the object is a finger before activating the lighting unit 14, which can avoid accidents. The lighting unit 14 is already activated when the finger is not placed within the reading range, thereby generating glare and glare, affecting the user's line of sight. And by comparing and obtaining photos of different light sources emitted by the first lighting and the second lighting of the lighting unit 14 by the signal processing module 3, the method of judging whether the detected finger is a real finger or a fake finger can make the interpretation result more accurate . And when the start signal has not been detected, the lens module 1 can be used as a general camera module, which can be used as a face camera or a video camera.

The above descriptions are only preferred feasible embodiments of the present invention, and do not limit the patent scope of the present invention. Therefore, all equivalent technical changes made by using the description and drawings of the present invention are included in the protection scope of the present invention.

Claims (10)

1. A fingerprint reading system, characterized in that, the fingerprint reading system comprises: A lens module, the lens module has a detection unit, an image acquisition unit, a liquid lens unit and an illumination unit; a control module, the control module is electrically connected to the lens module to control the image acquisition unit, the liquid lens unit and the lighting unit; and a signal processing module; Wherein, when the detection unit detects an activation signal, the control module activates the image acquisition unit, the liquid lens unit and the lighting unit, and the liquid lens unit modulates the focus distance from far to near Fingerprint scanning, the image acquisition unit continuously acquires a plurality of finger fingerprint image photos through the process of modulating the focus distance of the liquid lens unit from far to near, the signal processing module acquires Select one of the photos with correct focus among the fingerprint image photos, and convert the photo with correct focus into a fingerprint picture. 2 . The fingerprint reading system according to claim 1 , wherein when the detection unit has not detected the activation signal, the lens module is used as a camera. 3 . 3. The finger and fingerprint reading system according to claim 1, wherein the liquid lens unit modulates the focus distance from far to near to scan the fingerprint, and the distance to scan the fingerprint is between 10 centimeters and 1 centimeter. The scanning time is less than 0.5 seconds, and the image acquisition unit acquires 3 to 10 fingerprint image photos of the finger through the liquid lens unit. 4. The finger and fingerprint reading system according to claim 1, wherein the start signal is the correct finger shape detected by the detection unit, the correct finger color or a predetermined acquisition area occupied by the finger . 5. The finger and fingerprint reading system according to claim 1, wherein the finger and fingerprint reading system further comprises: an indicator light, and when the detection unit detects the start signal, start the light. 6. The finger and fingerprint reading system according to claim 1, wherein, when the continuous acquisition of multiple fingerprint image photos is completed, the image acquisition unit, the liquid lens unit and the lighting unit are turned off . 7. A fingerprint reading method, characterized in that, said fingerprint reading method comprises the following steps: detecting an object within the read range; determine the attributes of the object; activate a lighting unit; Start an image acquisition unit and a liquid lens unit; Modulating and scanning the focusing distance of the liquid lens unit from far to near; Obtain multiple continuous photos of the liquid lens unit from far to near; turning off the image acquisition unit, the liquid lens unit and the lighting unit; selecting a properly focused photograph from the sequence of photographs acquired by said image acquisition unit; and Converting the correctly focused photos among the continuous photos acquired by the image acquisition unit into fingerprint pictures. 8. The fingerprint reading method according to claim 7, characterized in that, the liquid lens unit modulates the focus distance from far to near for fingerprint scanning, and the distance for fingerprint scanning is between 10 centimeters and 1 centimeter. The scanning time is less than 0.5 seconds. 9. The fingerprint reading method according to claim 7, wherein the step of judging the attribute of the object comprises: judging by correct finger shape judgment, correct finger color judgment or a predetermined obtainable area occupied by the finger . 10. The fingerprint reading method according to claim 7, characterized in that the step of starting the lighting unit further comprises: using white light as the first lighting light, and then starting the image acquisition unit and the The step of the liquid lens unit is to obtain a plurality of continuous photos of the liquid lens unit from far to near, and then use red light or near-infrared light as the second illumination light of the illumination unit, and start the From the steps of the image acquisition unit and the liquid lens unit to the step of converting the photos with correct focus in the continuous photos acquired from the image acquisition unit into pictures, and then analyze the first illumination by a signal processing module Acquired photographic images vs. photographic images acquired for the second lighting.