Abstract:
The present invention discloses sandwich type fingerprint recognition devices, one embodiment of the sandwich type fingerprint recognition device includes a first transparent layer, a spatial filter layer with multiple through holes, a second transparent layer and an optical sensor. Another embodiment of the sandwich type fingerprint recognition device includes a first transparent layer, a spatial filter layer with multiple through holes and an optical sensor. With the implementation of the present invention, complex production process or equipment are not required for producing fingerprint recognition device that reduce costs; the size of the fingerprint recognition device is reduced; a variety of thickness choices for the first transparent layer or second transparent layer and a variety of colors can be used and more applications are thus possible; and the contrast of fingerprint signal is enhanced to enable clarifying fingerprint features and characteristics and thus recognition accuracy of fingerprints.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to fingerprint recognition devices, and more particularly to sandwich type fingerprint recognition devices. 
         [0003]    2. Description of Related Art 
         [0004]    Traditional optical fingerprint recognition system or device uses an imaging system to acquire the image of fingerprint. Due to the bulk size of traditional device or system, positive lens can be adopted to commence imaging in the imaging system. 
         [0005]    However, as the increasingly widespread of the fingerprint recognition system or device to handheld or portable devices that is relatively small in size, the space reserved for fingerprint recognition system or device becomes quite small. 
         [0006]    Therefore, when adopting fingerprint recognition system or device to apparatus relatively small, positive lens imaging method cannot be applied due to such physical limitation. 
         [0007]    It is therefore highly desirable to have the development of a thin type, high imaging quality fingerprint recognition device with multi-layer spatial filter and pillar structure to apply in limited space in thin or small size portable or mini devices or smart handheld devices. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    The present invention discloses sandwich type fingerprint recognition devices, one embodiment of the sandwich type fingerprint recognition device includes a first transparent layer, a spatial filter layer with multiple through holes, a second transparent layer and an optical sensor. Another embodiment of the sandwich type fingerprint recognition device includes a first transparent layer, a spatial filter layer with multiple through holes and an optical sensor. With the implementation of the present invention, complex production process or equipment are not required for producing fingerprint recognition device that reduce costs; the size of the fingerprint recognition device is reduced; a variety of thickness choices for cover glass (first transparent layer or second transparent layer); a variety of colors can be used and more applications are thus possible; and the contrast of fingerprint signal is enhanced to enable clarifying fingerprint features and characteristics and thus recognition accuracy of fingerprints. 
         [0009]    The present invention provides a sandwich type fingerprint recognition device, being a multi-layer structure used to sense or recognize a fingerprint, comprising: a first transparent layer, being made of light transmitting substance, includes an upper surface and a lower surface opposite to the upper surface, wherein the thickness of the first transparent layer is in the range from 1 micrometer to 800 micrometer; a filter layer, being formed on the lower surface; and an optical sensor, being fixedly provided beside the filter layer in a way that the filter layer being in between the first transparent layer and the optical sensor. 
         [0010]    The present invention provides another sandwich type fingerprint recognition device, being a multi-layer structure used to sense or recognize a fingerprint, comprising: a first transparent layer, being made of light transmitting substance, includes an upper surface and a lower surface opposite to the upper surface, wherein the thickness of the first transparent layer is in the range from 1 micrometer to 800 micrometer; a filter layer, being formed on the lower surface; a second transparent layer, being formed on the filter layer in a way that the filter layer being sandwiched in between the first transparent layer and the second transparent layer; and an optical sensor, being fixedly provided beside the second transparent layer. 
         [0011]    The present invention provides another sandwich type fingerprint recognition device, being a multi-layer structure used to sense or recognize a fingerprint, comprising: a first transparent layer, being made of light transmitting substance, includes an upper surface and a lower surface opposite to the upper surface, wherein the thickness of the first transparent layer is in the range from 1 micrometer to 800 micrometer; a filter layer, being formed on the upper surface; and an optical sensor, being fixedly provided beside the lower surface. 
         [0012]    Implementation of the present invention at least provides the following advantageous effects: 
         [0013]    1. Structure simplicity to ensure ease of manufacturing and to reduce manufacturing costs. 
         [0014]    2. Reduction of space occupation enabling further applications. 
         [0015]    3. Provides high resolution and accurate fingerprint recognition 
         [0016]    4. Applicable to filling of material or materials of a variety of colors. 
         [0017]    5. Capable of enhancing the contrast of fingerprint signal. 
         [0018]    6. Capable of enhancing the discrimination of characteristics of fingerprint signal and preventing false recognition. 
         [0019]    The features and advantages of the present invention are detailed hereinafter with reference to the preferred embodiments. The detailed description is intended to enable a person skilled in the art to gain insight into the technical contents disclosed herein and implement the present invention accordingly. In particular, a person skilled in the art can easily understand the objects and advantages of the present invention by referring to the disclosure of the specification, the claims, and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0020]    The invention as well as a preferred mode of use, further objectives and advantages thereof will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein: 
           [0021]      FIG. 1  is a structural perspective view of a sandwich type fingerprint recognition device in an embodiment of the present invention. 
           [0022]      FIG. 2  is a structural perspective view of a sandwich type fingerprint recognition device in another embodiment of the present invention. 
           [0023]      FIG. 3  is a structural perspective view of a sandwich type fingerprint recognition device in still another embodiment of the present invention. 
           [0024]      FIG. 4A  is a longitudinal perspective section view of a filter layer in an embodiment of the present invention. 
           [0025]      FIG. 4B  is a lateral perspective section view of a filter layer in an embodiment of the present invention. 
           [0026]      FIG. 5  is a sectional perspective view of the optical sensor being not in contact with the filter layer in the embodiment of  FIG. 1 . 
           [0027]      FIG. 6  is a sectional perspective view of the optical sensor being not in contact with the second transparent layer in the embodiment of  FIG. 2 . 
           [0028]      FIG. 7  is a sectional perspective view of the optical sensor being not in contact with the first transparent layer in the embodiment of  FIG. 3 . 
           [0029]      FIG. 8  is a structural perspective view of a sandwich type fingerprint recognition device further comprises a pillar layer in an embodiment of the present invention. 
           [0030]      FIG. 9  is a structural perspective view of a sandwich type fingerprint recognition device further comprises a pillar layer in another embodiment of the present invention. 
           [0031]      FIG. 10A  is a structural perspective view of a filter layer in an embodiment of the present invention. 
           [0032]      FIG. 10B  is a structural perspective view of a filter layer in another embodiment of the present invention. 
           [0033]      FIG. 10C  is a structural perspective view of a filter layer in still another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    Please refer to  FIG. 1 , an embodiment of a sandwich type fingerprint recognition device  100  comprises: a first transparent layer  10 , a filter layer  20  and an optical sensor  30 . 
         [0035]    As shown in  FIG. 2  is another sandwich type fingerprint recognition device  200 , which comprises: a first transparent layer  10 , a filter layer  20 , a second transparent layer  50  and an optical sensor  30 . 
         [0036]    Further shown in  FIG. 3  is still another sandwich type fingerprint recognition device  300 , which comprises: a first transparent layer  10 , a filter layer  20  and an optical sensor  30 . 
         [0037]    As shown in  FIG. 1  to  FIG. 3 , the first transparent layer  10  of the sandwich type fingerprint recognition device  100 , or of the sandwich type fingerprint recognition device  200 , or of the sandwich type fingerprint recognition device  300  can be a transparent plate or film made of glass or any material or materials transparent to light in visible frequency region, infrared frequency region or ultraviolet frequency region. 
         [0038]    In applications of finger print recognition or detection, the thickness of the first transparent layer  10  can be chosen in the range from 1 μm to 800 μm. 
         [0039]    As shown in  FIG. 1  and  FIG. 2 , when in actual detection of fingerprint  800 , the finger of a user with the fingerprint  800  to be detected or recognized or processed rests on the first transparent layer  10 . The light reflected from at least one ridge portion  801  and at least one valley portion  802  of the fingerprint  800  passes through the first transparent layer  10  and reaches the filter layer  20  to be then modulated by the filter layer  20 . 
         [0040]    As shown in  FIG. 3 , while applying the sandwich type fingerprint recognition device  300 , the finger of a user with the fingerprint  800  to be detected or recognized or processed rests on the first transparent layer  10  touching the filter layer  20 , the light reflected from the ridge portion  801  and the valley portion  802  of the fingerprint  800  first being modulated by the filter layer  20  and then passes through the first transparent layer  10 . 
         [0041]    As shown in  FIG. 1  to  FIG. 3 , the filter layer  10  of the sandwich type fingerprint recognition device  100 , or of the sandwich type fingerprint recognition device  200 , or of the sandwich type fingerprint recognition device  300  being used as a spatial filter that modulates incident light, which is the light signal reflected from the fingerprint  800 , to suppress, isolate or reflect oblique incident portion of the incident light and enhance the contrast of the light signal. 
         [0042]    As shown in  FIG. 1  to  FIG. 4B , the aforesaid filter layer  20  can be an optical film, plural microstructures or light blocking layer  20 ′ with plural through holes  21 . 
         [0043]    Referring to  FIG. 4A  and  FIG. 4B , when light blocking layer  20 ′ with plural through holes  21  is used as the filter layer  20 , only the light signal incidents to the through holes  21  will pass, other part of the light blocking layer  20 ′ blocks light signal in visible frequency region, infrared frequency region or ultraviolet frequency region. 
         [0044]    In embodiments, transparent material or materials can be filled in the through holes  21  to make the filter layer  20  better endurable while the light still passes through the through holes  21 . And on the other hand, the diameter of any of the through holes  21  can be made to be larger than 2 μm, or in between 2 μm and 100 μm. 
         [0045]    Further, the surface of the filter layer  20  with through holes  21  can also be a light reflecting surface that reflects large angle oblique incident light to reduce its intensity of passing through the filter layer  20 , thus reduces noise signal and enhance the contrast of the light signal reflected by fingerprint  800  and received by the optical sensor  50  in sandwich type fingerprint recognition device  100 , sandwich type fingerprint recognition device  200  or sandwich type fingerprint recognition device  300 . 
         [0046]    And hence, the scattering of reflected light signal by fingerprint  800  that generates blur effect in the optical sensor  50  is reduced or even eliminated. 
         [0047]    As shown in  FIG. 2 ,  FIG. 4A  and  FIG. 4B , the light blocking layer  20 ′ can be formed of colored structure of a specific color or specific colors with the effect that color of the overall appearance when observed from top of the sandwich type fingerprint recognition device  100 , sandwich type fingerprint recognition device  200  or sandwich type fingerprint recognition device  300  is being changed or modified according to various applications. 
         [0048]    Please refer to  FIG. 2 , the second transparent layer  50  can also be a transparent plate or film made of glass or any material or materials transparent to light in visible frequency region, infrared frequency region or ultraviolet frequency region. 
         [0049]    The second transparent layer  50  is implemented attached to the filter layer  20  making the filter layer  20  being sandwiched between the second transparent layer  50  and the first transparent layer  10 . 
         [0050]    As for the thickness of the second transparent layer  50 , it can also be chosen to be in the range from 1 μm to 800 μm. 
         [0051]    With continuous reference to  FIG. 1  to  FIG. 3 , optical sensor  30  is formed or implemented in under the first transparent layer  10  or under the filter layer  20 , or under the sandwich structure of first transparent layer  10 , the filter layer  20  and the second transparent layer  50 . 
         [0052]    The optical sensor  30  shown in  FIG. 1  to  FIG. 3  is used to receive the light signal reflected from at least one ridge portion  801  and at least one valley portion  802  of the fingerprint  800  that passes through the first transparent layer  10  and the filter layer  20  or the first transparent layer  10  and the filter layer  20  and the second transparent layer  50 , and then generates a pattern light signal of the fingerprint  800  for post processing. 
         [0053]    Further, the aforesaid optical sensor  30  can be composed of at least one optical sensor chip. 
         [0054]    Please refer to  FIG. 5  to  FIG. 7 , the optical sensor  30  can be implemented to not being in contact with the filter layer  20  of the sandwich type fingerprint recognition device  100  or the second transparent layer  50  of the sandwich type fingerprint recognition device  200  or the lower surface  12  of the sandwich type fingerprint recognition device  300 . 
         [0055]    As shown in  FIG. 8 , a pillar layer  40  is further formed in between the second transparent layer  50  and the optical sensor  30  of the sandwich type fingerprint recognition device  200 . 
         [0056]    Wherein the pillar layer  40  can be formed by plural hollow cylinders  41 , and the spacing between any two of the hollow cylinders  41  is filled with non-transparent filler material  42  with the effect that the light signal incident to the pillar layer  40  is blocked by the non-transparent filler material  42  and passes only through the hollow cylinders  41 , large angle oblique incident light is thus further reduced in intensity or blocked that the contrast of the fingerprint light signal is further enhanced. 
         [0057]    Then as shown in  FIG. 9 , a pillar layer  40  can further be formed in between the first transparent layer  10  and the optical sensor  30  of the sandwich type fingerprint recognition device  300 . 
         [0058]    Again, the pillar layer  40  being formed by plural hollow cylinders  41 , and the spacing between any two of the hollow cylinders  41  is filled with non-transparent filler material  42  with the effect that the light signal incident to the pillar layer  40  is blocked by the non-transparent filler material  42  and passes only through the hollow cylinders  41 , large angle oblique incident light is thus further reduced in intensity or blocked that the contrast of the fingerprint light signal is further enhanced. 
         [0059]    Further, transparent material or materials can be filled inside the hollow cylinders  41  as shown in  FIG. 8  and  FIG. 9  to make the hollow cylinders  41  better endurable while the light can still pass through, wherein the diameter of any of the hollow cylinders  41  can be made larger than 2 μm or in between 2 μm and 100 μm. 
         [0060]    All in all, with the implementation of the filter layer  20  in sandwich type fingerprint recognition device  100 , sandwich type fingerprint recognition device  200  or sandwich type fingerprint recognition device  300 , large angle oblique incident light is reduced in intensity or isolated to greatly enhance the contrast of the fingerprint light signal and thus being capable of enhancing the discrimination of characteristics of fingerprint signal and preventing false recognition. 
         [0061]    Further with the implementation of the pillar layer  40 , the benefit is further strengthened and the contrast of the fingerprint light signal in sandwich type fingerprint recognition device  200  or sandwich type fingerprint recognition device  300  is further enhanced. 
         [0062]    Moreover, as shown in  FIG. 10A , the aforesaid filter layer  20  in the embodiments can be formed as a colored layer  60  or a replaceable colored layer  60  that makes sandwich type fingerprint recognition device  100 , sandwich type fingerprint recognition device  200  or sandwich type fingerprint recognition device  300  even more widely applicable. 
         [0063]    While as shown in  FIG. 10B , the aforesaid filter layer  20  can also be formed as a spatial filter layer  70  which being an optical film, plural microstructures or a light blocking layer with plural perforated holes. 
         [0064]    Or as shown in  FIG. 10C , the aforesaid filter layer  20  can also be formed by a said colored layer  60  and a said spatial filter layer  70  altogether. 
         [0065]    With this and as shown in  FIG. 1  to  FIG. 3  and  FIG. 10A  to  FIG. 10C , the filter layer  20 , being a colored layer  60 , a replaceable colored layer  60  or a colored layer  60  together with a spatial filter layer, can be formed or implemented on the first transparent layer  10 , or implemented in between the first transparent layer  10  and the optical sensor  30 , or even implemented on the first transparent layer  10  and in between the first transparent layer  10  and the optical sensor  30  at the same time, provides the benefit of enhancing the contrast of the fingerprint light signal and thus being capable of enhancing the discrimination of characteristics of fingerprint signal and preventing false recognition. 
         [0066]    The embodiments described above are intended only to demonstrate the technical concept and features of the present invention so as to enable a person skilled in the art to understand and implement the contents disclosed herein. It is understood that the disclosed embodiments are not to limit the scope of the present invention. Therefore, all equivalent changes or modifications based on the concept of the present invention should be encompassed by the appended claims.