Apparatus for capturing a high quality image of a moist finger
First Claim
1. A fingerprint image capturing apparatus comprising:
- a prism having an imaging plane on which a finger having valleys and ridges is placed, a bottom plane parallel to the imaging plane and a reflective plane intercepting the imaging plane and the bottom plane at an angle α
;
a light source for generating a light with an incident angle of approximately 0°
with respect to a surface normal of the imaging plane;
a lens for capturing light reflected from the reflective plane;
an image sensor for generating an image of the valleys and ridges of the finger; and
an adjuster for adjusting the reflective plane to change the value of α
in such a way to meet the following equation;
α
>
45+(arc sin (n1/n2))/2,where n1 is a refraction index of medium filled between the valleys of the finger and the imaging plane, and n2 is refraction index of the prism.
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Accused Products
Abstract
An apparatus for capturing the image of a wet/moist fingerprint. The apparatus includes: a prism having an imaging plane on which a finger having valleys and ridges is place, a bottom plane parallel to the imaging plane and a reflective plane intercepting the imaging plane and intercepting the bottom plane at an angle α; a light source for generating a light with an incident angle of approximately 0° with respect to a surface normal of the imaging plane; and a lens for capturing light reflected from the reflective plane. The apparatus further includes an image sensor for generating an image of the valleys and ridges of the finger, wherein the reflective plane is arranged in such a way to meet the equation of α>45 +(arc sin (n1/n2))/2, where n1 is a refraction index of medium filled between the valleys of the finger and the imaging plane, and n2 is refraction index of the prism.
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Citations
15 Claims
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1. A fingerprint image capturing apparatus comprising:
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a prism having an imaging plane on which a finger having valleys and ridges is placed, a bottom plane parallel to the imaging plane and a reflective plane intercepting the imaging plane and the bottom plane at an angle α
;a light source for generating a light with an incident angle of approximately 0°
with respect to a surface normal of the imaging plane;a lens for capturing light reflected from the reflective plane; an image sensor for generating an image of the valleys and ridges of the finger; and an adjuster for adjusting the reflective plane to change the value of α
in such a way to meet the following equation;
α
>
45+(arc sin (n1/n2))/2,where n1 is a refraction index of medium filled between the valleys of the finger and the imaging plane, and n2 is refraction index of the prism. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A fingerprint image capturing apparatus comprising:
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a prism having an imaging plane on which a finger having valleys and ridges is placed, a bottom plane parallel to the imaging plane and a reflective plane intercepting the imaging plane and the bottom plane at an angle α
;a light source for generating a light with an incident angle of approximately 0°
with respect to a surface normal of the imaging plane;a lens for capturing light reflected from the reflective plane; and an image sensor for generating an image of the valleys and ridges of the finger, wherein the reflective plane is manually adjustable to change the value of α
in such a way to meet the following equation;
α
>
45+(arc sin (n1/n2))/2,where n1 is a refraction index of medium filled between the valleys of the finger and the imaging plane, and n2 is refraction index of the prism. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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Specification
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- Resources
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Current AssigneeThales DIS France SAS (Thales SA)
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Original Assignee3M Cogent Incorporated (Thales SA)
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InventorsHsieh, Ming, Wang, Ankuo, Zhou, Fei, Chen, Wheshi
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Primary Examiner(s)Mehta, Bhavesh
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Assistant Examiner(s)Shah, Utpal
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Application NumberUS12/105,212Publication NumberTime in Patent Office1,622 DaysField of Search382/124, 382/128, 382/127US Class Current382/127CPC Class CodesG06V 40/1324 by using geometrical optics...
