TWI517054B - Fingerprint image capturing device - Google Patents

Description

Fingerprint imaging device

The present invention relates to an image taking device, and more particularly to a fingerprint image capturing device.

In general, the fingerprint recognition device reads the fingerprint by contacting the fingerprint surface of the finger with the reading area, for example, by using a pressing plate for finger contact, and then using a plurality of light-emitting elements to provide a fingerprint image of the finger of the lens-collecting contact plate. In order to meet the principle of total reflection, the fingerprint recognition device must have a certain angle between the lens, the finger and the light source in order to extract the clear and clear fingerprint, so that the conventional optical type Fingerprint identification devices generally have problems of large size and inability to be thinned.

In addition, since the focal length of the lens mounted on the fingerprint recognition device is related to the accommodation space of the fingerprint recognition device, only the lens with the fixed focal length range can be limited in the limited accommodation space of the fingerprint identification device. In this way, in the design of the fingerprint identification device, the fingerprint recognition quality cannot be improved by selecting the lens of the remaining focal length range.

The invention provides a fingerprint image capturing device, which can improve the fingerprint identification device and can not be thinned, and can not be improved due to lens focal length limitation. Improve the quality of fingerprint recognition.

The fingerprint imaging device disclosed in the present invention comprises a finger pressing member, a light source module, a reflection module and an image capturing module. The finger pressing has a top surface and a bottom surface. The opposite sides of the finger pressing member respectively have a light incident surface and a light exit surface. The light source module corresponds to the light incident surface. The light source module has a light emitting surface. The light emitting surface faces the light entrance surface. The reflection module corresponds to the light exit surface. The image capture module corresponds to the reflection module. The reflection module is configured to reflect the light emitted from the light surface to the image capturing module.

According to the fingerprint identification device disclosed in the present invention, the fingerprint image is reflected through at least one reflective surface to change the transmission path and distance of the fingerprint image. Thereby, the placement position of the image capturing module is changed. In order to make the fingerprint identification device thin.

The above description of the present invention and the following description of the embodiments are intended to illustrate and explain the principles of the invention, and to provide a further explanation of the scope of the invention.

10‧‧‧Finger identification device

20‧‧‧ fingers

100‧‧‧ finger press

110‧‧‧ top surface

120‧‧‧ bottom

130‧‧‧Into the glossy surface

140‧‧‧Glossy

200‧‧‧Light source module

210‧‧‧Light emitting surface

300‧‧‧Light diffuser

400‧‧‧reflection module

410‧‧‧First reflector

411‧‧‧First reflecting surface

420‧‧‧second reflector

421‧‧‧Second reflective surface

500‧‧‧Image capture module

510‧‧‧ takes the image

Fig. 1 is a schematic view of a fingerprint image pickup apparatus according to a first embodiment of the present invention.

Fig. 2 is a schematic diagram of a fingerprint image capturing apparatus according to a second embodiment of the present invention.

3 is a schematic view of a fingerprint image capturing apparatus according to a third embodiment of the present invention. Figure.

Referring to FIG. 1, FIG. 1 is a schematic diagram of a fingerprint image capturing apparatus according to a first embodiment of the present invention.

The fingerprint image capturing device 10 of the present embodiment includes a finger pressing member 100, a light source module 200, a light diffusing member 300, a reflecting module 400, and an image capturing module 500. The light-conducting medium inside the fingerprint image capturing device 10 is air, and the refractive index n1 of the air is 1.000293.

The finger pressing member 100 is a light transmissive plate body, and the material thereof can be glass (model specification: BK7) or polymethylmethacrylate (PMMA). The refractive index n2 of the finger pressing member 100 ranges from 1.49 to 1.52.

The cross section of the finger pressing member 100 has a trapezoidal shape. The edge of the cross section of the finger pressing member 100 is surrounded by a top surface 110, a bottom surface 120, a light incident surface 130, and a light exit surface 140. The top surface 110 of the finger pressing member 100 is for contact with a finger 20, and the width of the top surface 110 is greater than the width of the bottom surface 120. The light-incident surface 130 and the light-emitting surface 140 are respectively connected between the top surface 110 and the bottom surface 120 and are located on opposite sides of the finger pressing member 100.

It should be noted that the bottom surface 120 of the vertical finger pressing 100 can be defined as a first normal line N1. The first normal line N1 and the light exit surface 140 form a first angle θ1. The first angle θ1 is between 30 degrees and 60 degrees. Preferably, the first angle θ1 is 45 degrees.

The light source module 200 corresponds to the light incident surface 130. The light source module 200 has a light emitting surface 210. The light emitting surface 210 faces the light incident surface 130. The light source module 200 is configured to be vertically emitted from the light emitting surface 210. It should be noted that the vertical light emitting surface 210 can be defined as a second normal line N2. The first normal line N1 and the second normal line N2 form a second angle θ2. When the second angle θ2 is greater than or equal to The light projected onto the top surface 110 can be reflected to the light exit surface 140 under the condition of total reflection, and the top plate 110 can reflect a clear fingerprint image.

The light diffusing member 300 is interposed between the light incident surface 130 and the light emitting surface 210. In the present embodiment, the light emitting surface 210 and the light diffusing member 300 are parallel to the light incident surface 130.

The reflection module 400 corresponds to the light exit surface 140. In this embodiment, the reflective module 400 includes a first reflective member 410. The first reflecting member 410 has a first reflecting surface 411. The first reflecting surface 411 faces the light emitting surface 140 and is at an acute angle with the light emitting surface 140. In addition, the first reflective surface 411 is coplanar with the bottom surface 120, but is not limited thereto. In other embodiments, the first reflective surface 411 may also be located at any horizontal plane parallel to the bottom surface 120.

The image capturing module 500 corresponds to the first reflecting surface 411. The image capturing module 500 has an image capturing surface 510. The image taking surface 510 faces the first reflecting surface 411, and the image capturing surface 510 and the first reflecting surface 411 are at an acute angle. The image capturing module 500 is configured to capture a fingerprint image reflected by the first reflecting surface 411.

In this embodiment, the length ratio of the top surface 110 to the bottom surface 120 is z ratio y, and the length of the effective contact portion between the top surface 110 and the finger 20 is z1. And z1 < z. However, in order for the image capturing module 500 to capture a complete fingerprint image, the following conditions are met: (1) the length (y) of the bottom surface 120 is greater than or equal to the length of the effective contact portion between the top surface 110 and the finger 20 (z1) ). (2) The length (x) of the first reflecting surface 411 is greater than or equal to the double height of the finger pressing multiplied by the tangent function of the first angle θ1 (2h × tna θ1).

Since the fingerprint recognition device 10 of the embodiment is provided with the first reflection member 410 to reflect the fingerprint image to change the transmission path of the light forming the fingerprint image, the position of the image capturing module 500 can be changed, thereby making the fingerprint identification device 10 thin. Formalization. In addition, the first reflector 410 can also change the light transmission distance between the image capturing module 500 and the fingerprint, and can be combined with the image capturing module 500 of different focal length ranges in the limited space of the fingerprint identification device 10.

The number of the reflectors in the embodiment of the first embodiment is one, but not limited thereto. In other embodiments, the number of the reflectors may be two or more. Please refer to FIG. 2, which is a schematic diagram of a fingerprint image capturing apparatus according to a second embodiment of the present invention. This embodiment is similar to the above embodiment, and therefore only the differences will be described.

The fingerprint identification device 10 of the present embodiment includes a finger pressing member 100, a light source module 200, a light diffusing member 300, a reflecting module 400, and an image capturing module 500.

The cross section of the finger pressing member 100 is a trapezoidal shape, and the cross section of the finger pressing member 100 is surrounded by a top surface 110, a bottom surface 120, a light incident surface 130 and a light exit surface 140. The top surface 110 of the finger pressing member 100 is for a finger 20 contacts, and the width of the top surface 110 is greater than the width of the bottom surface 120. The light-incident surface 130 and the light-emitting surface 140 are respectively connected between the top surface 110 and the bottom surface 120 and are located on opposite sides of the finger pressing member 100.

The light source module 200 corresponds to the light incident surface 130. The light diffusing member 300 is interposed between the light incident surface 130 and the light emitting surface 210. In the present embodiment, the light emitting surface 210 and the light diffusing member 300 are parallel to the light incident surface 130.

The reflection module 400 corresponds to the light exit surface 140. In this embodiment, the reflective module 400 includes a first reflective member 410 and a second reflective member 420. The first reflecting member 410 has a first reflecting surface 411. The first reflecting surface 411 faces the light emitting surface 140 and is at an acute angle with the light emitting surface 140. The second reflecting member 420 has a second reflecting surface 421. The second reflecting surface 421 faces the first reflecting surface 411. In this embodiment, the first reflective surface 411 is coplanar with the bottom surface 120, and the second reflective surface 421 is coplanar with the top surface 110. However, in other embodiments, the first reflective surface 411 and the second reflective surface 421 may be disposed on the parallel bottom surface 120, and the second reflective surface 421 is located away from the bottom surface 120 of the first reflective surface 411. .

It should be noted that the fingerprint recognition device 10 of the present embodiment has a second reflection member 420 added to the embodiment of the first embodiment. The first reflecting surface 411 and the second reflecting surface 421 can further change the transmission path of the fingerprint image to make the fingerprint identifying device 10 thinner.

Please refer to FIG. 3, which is a schematic diagram of a fingerprint image capturing apparatus according to a third embodiment of the present invention.

The fingerprint identification device 10 of the present embodiment includes a finger pressing member 100, a light source module 200, a light diffusing member 300, a reflecting module 400, and an image capturing module 500.

The cross section of the finger pressing member 100 is a trapezoidal shape, and the cross section of the finger pressing member 100 is surrounded by a top surface 110, a bottom surface 120, a light incident surface 130 and a light exit surface 140. The top surface 110 of the finger pressing member 100 is for contact with a finger 20, and the width of the top surface 110 is greater than the width of the bottom surface 120. The light-incident surface 130 and the light-emitting surface 140 are respectively connected between the top surface 110 and the bottom surface 120 and are located on opposite sides of the finger pressing member 100.

It should be noted that the bottom surface 120 of the vertical finger pressing 100 can be defined as a first normal line N1.

The light source module 200 corresponds to the light incident surface 130. The light diffusing member 300 is interposed between the light incident surface 130 and the light emitting surface 210. In the present embodiment, the light emitting surface 210 and the light diffusing member 300 are parallel to the first normal line N1. By the light emitting surface 210 and the light diffusing member 300 being parallel to the first normal line N1, the entire surface area of the top surface 110 can be uniformly received. In this way, the edge of the fingerprint image does not have obvious dark areas, and the recognition accuracy of the fingerprint identification device 10 can be improved.

According to the fingerprint identification device disclosed in the present invention, the fingerprint image is reflected through at least one reflective surface to change the transmission path and distance of the fingerprint image. Thereby, the placement position of the image capturing module is changed. In order to make the fingerprint identification device thin.

In addition, the number of reflectors of the reflective module and the position of the mirror are not The light transmission distance between the image capturing module and the fingerprint can be changed, and the image capturing module of different focal length ranges can be matched in the limited space of the fingerprint identification device to improve the identification quality of the fingerprint identification device.

Furthermore, the light emitting surface and the light diffusing member are parallel to the first normal line N1, so that the entire surface area of the top surface can be uniformly received. In this way, the edge of the fingerprint image does not have obvious dark areas, which can improve the recognition accuracy of the fingerprint identification device.

Although the embodiments of the present invention are disclosed above, it is not intended to limit the present invention, and those skilled in the art, regardless of the spirit and scope of the present invention, the shapes, configurations, and features described in the scope of the present application. And the number of modifications may be made, and the scope of patent protection of the present invention shall be determined by the scope of the patent application attached to the specification.

10‧‧‧Finger identification device

20‧‧‧ fingers

100‧‧‧ finger press

110‧‧‧ top surface

120‧‧‧ bottom

130‧‧‧Into the glossy surface

140‧‧‧Glossy

200‧‧‧Light source module

210‧‧‧Light emitting surface

300‧‧‧Light diffuser

400‧‧‧reflection module

410‧‧‧First reflector

411‧‧‧First reflecting surface

500‧‧‧Image capture module

510‧‧‧ takes the image

Claims (12)

A fingerprint image capturing device comprises: a finger pressing member having an opposite top surface and a bottom surface, wherein the opposite sides of the finger pressing member respectively have a light incident surface and a light exit surface, and the vertical bottom surface is defined as a first a normal line, the first normal line and the light exiting surface form a first angle; a light source module corresponding to the light incident surface, the light source module has a light emitting surface facing the light incident surface; and a reflective module a first reflecting member having a first reflecting surface corresponding to the light emitting surface, and an image capturing module corresponding to the first reflecting portion of the first reflecting member The first reflective surface is configured to reflect the light emitted from the light exiting surface to the image capturing module; wherein the length of the bottom surface of the finger pressing member is greater than or equal to the length of the top surface actually contacting the fingerprint, and the first The length of the reflecting surface is greater than or equal to twice the height of the finger pressing multiplied by the tangent function of the first angle. The fingerprint image capturing device of claim 1, wherein the first angle is between 30 degrees and 60 degrees. The fingerprint image capture device of claim 2, wherein the first angle is 45 degrees. The fingerprint image capturing device of claim 3, wherein the light emitting surface is defined as a second normal line, and the first normal line and the second normal line form a second angle, wherein the second angle is greater than or equal to Where n ₁ is the refractive index of air and n ₂ is the refractive index of the finger pressing member. The fingerprint image capturing device of claim 4, wherein the image capturing module corresponds to the first reflecting surface. The fingerprint image capturing device of claim 5, wherein the first reflecting surface is parallel to the bottom surface. The fingerprint imaging device of claim 5, wherein the first reflective surface is coplanar with the bottom surface. The fingerprint image capturing device of claim 1, wherein the reflective module comprises a first reflecting member and a second reflecting member, the first reflecting member having a first reflecting surface corresponding to the light emitting surface, the first The second reflecting member has a second reflecting surface corresponding to the first reflecting surface, and the image capturing module corresponds to the second reflecting surface. The fingerprint image capturing device of claim 8, wherein the first reflecting surface and the second reflecting surface are parallel to the bottom surface. The fingerprint imaging device of claim 8, wherein the first reflective surface is coplanar with the bottom surface, and the second reflective surface is coplanar with the top surface. The fingerprint image capturing device of claim 1, further comprising a light diffusing member interposed between the light incident surface and the light emitting surface, and the light emitting surface and the light diffusing member are parallel to the light incident surface. A fingerprint image capturing device comprising: a finger pressing member having an opposite top surface and a bottom surface, the finger pressing portion a light source module corresponding to the light incident surface, the light source module has a light emitting surface facing the light incident surface; and a reflective module corresponding to the light source module a light-emitting surface; an image capturing module corresponding to the reflective module, the reflective module for reflecting light emitted from the light-emitting surface to the image capturing module; and a light diffusing member interposed between the light-incident surface and the light-receiving surface Between the light emitting surfaces, the bottom surface is defined as a first normal line, and the light emitting surface and the light diffusing member are parallel to the first normal line.