An optical structure fingerprint identification module based on collimated light extraction and a preparation method thereof

Abstract

The invention discloses a fingerprint identification module of an optical structure based on collimated light extraction and a preparation method of the fingerprint identification module. The fingerprint identification module comprises a fingerprint identification sensor array and further comprises the optical structure arranged on the fingerprint identification sensor array and used for collimated light extraction. The optical structure comprises an upper nanometer grating layer, a lower nanometer grating layer and a polymer dispersed liquid crystal (PDLC) layer arranged between the upper nanometer grating layer and the lower nanometer grating layer. By applying the method, the process flow can be simplified, the thickness of the fingerprint identification module is reduced, and Miss-is avoided. And moreover, the fingerprint identification precision can be improved.

Description

technical field [0001] The invention relates to the technical field of fingerprint identification, in particular to a fingerprint identification module based on an optical structure extracted from collimated light and a preparation method thereof. Background technique [0002] Compared with ordinary screens, full-screen visual effects have higher impact and more stunning display effects, and have become the new favorite of smart display terminals. However, with the increase in screen-to-screen ratio, the design of fingerprint recognition modules based on fingerprint recognition sensors has become an urgent problem for mobile phone terminal manufacturers to solve. [0003] Display devices with full-screen fingerprint recognition technology using collimated light solutions, such as figure 1 As shown, its fingerprint recognition module includes: a fingerprint recognition sensor array and its backplane, and an optical structure layer arranged above the fingerprint recognition s...

AI Technical Summary

Problems solved by technology

[0006] 1. Since the optical structure layer needs to form a multi-layer BM layer and a PI (polyimide film) layer separating adjacent BM layers, at least 5-6 masking processes are required in the entire process of the fingerprint identification module, 5- 6 times of PI film coating, the process is very complicated

[0007] 2. The multi-layer BM layer and PI layer cause the overall thickness of the optical structure of the fingerprint identification module to reach 100um, which is not conducive to the overall thinning and thinning of the display device, and the overall thickness is greater than 100um, which will also cause a large internal stress of the device, such as Figure 5a As shown, there is a risk of shards from glass bending

[0008] 3. If Figure 5b As shown, in the process of etching round holes in the BM layer, PI residues often appear; because the granular residues in the holes will affect the optical path through the holes, thereby reducing the accuracy of fingerprint recognition

[0009] 4. If Figure 5c As shown, there needs to be a certain deviation between the multi-layer hole pairs, but it is difficult to control the deviation within an appropriate range in the actual production process, resulting in the Miss-align (alignment deviation) problem

[0010] 5. Limited by the influence of 5-layer BM aperture ratio and multi-layer PI transmittance, the light intensity finally reaching the fingerprint recognition sensor is reduced, which seriously reduces the accuracy of fingerprint recognition

[0011] To sum up, the existing fingerprint recognition module based on the optical structure extracted by collimated light has the problems of very complicated manufacturing process, large overall thickness, Miss-align problem, and low fingerprint recognition accuracy.

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