Method for optically detecting a fingerprint or an object, and device with at least one screen

1. A method for optically capturing a fingerprint or an object on a surface ( 2 ) of a cover plate ( 1 ) of a screen, comprising the following steps:

providing a plurality of photosensors ( 4 );

providing a plurality of display pixels ( 6 );

assigning each of said photosensors ( 4 ) to a respective display pixel ( 6 ), wherein the display pixels ( 6 ) emit light radiation and the photosensors ( 4 ) capture light radiation from the display pixels ( 6 ) reflected by the surface ( 2 ) of the cover plate ( 1 ) of the screen within a scan angle ( 8 ), wherein the scan angle ( 8 ) corresponds in a virtual mirror image plane ( 9 ) to the size of a selected one of the display pixels ( 6 ), and wherein the scan angle ( 8 ) does not exceed the following size:

α≤2 arctan( d/ 4 h 1 )

wherein:

α=scan angle 8

d=edge length of the display pixel 6

h 1 =distance from the upper side of the display pixel to the surface 2 of the cover plate.

2. The method as defined in claim 1 , wherein, for capturing a fingerprint, a plurality of display pixels ( 6 ) emit light radiation, wherein a proportion of said light radiation that is emitted and that are reflected by the surface ( 2 ) are received by the photosensor ( 4 ) that is respectively assigned to the display pixel ( 6 ).

3. The method as defined in claim 1 , wherein, for capturing the object placed on the surface, a plurality of display pixels ( 6 ), emit light radiation to form a chessboard pattern, wherein reflected proportions of said light radiation that is emitted are received by the photosensor ( 4 ) that is respectively assigned to the display pixel ( 6 ) that emits no light radiation.

4. The method as defined in claim 3 , wherein the object is a document ( 10 ) placed on the surface ( 2 ).

5. The method as defined in claim 3 , wherein the display pixels ( 6 ) are arranged in the form of a matrix or in columns and lines.

6. The method as claimed in claim 3 , wherein, for recording two half images of the object that can be combined to form one image, the display pixels ( 6 ) sequentially emit light radiation or the photosensors ( 4 ) associated with the display pixels ( 6 ) receive reflected light radiation.

7. An apparatus for performing the method as defined in claim 1 , comprising:

at least one screen comprising an upper optical cover plate ( 1 );

a plurality of display pixels ( 6 ) arranged under said upper optical cover plate ( 1 ) as light sources for an image to be represented; and

a plurality of photosensors, wherein a respective one of the photosensors is assigned in each case in a centered fashion to a plurality of display pixels ( 6 ).

8. The apparatus as defined in claim 7 , wherein the photosensors ( 4 ) are arranged in a central free space of the associated display pixel ( 6 ) and are surrounded by subpixels ( 5 ).

9. The apparatus as defined in claim 7 , wherein the photosensors ( 4 ) are arranged on a side of the display pixels ( 6 ) that is opposite the cover plate ( 1 ), wherein each display pixel ( 6 ) comprises a plurality of subpixels ( 5 ).

10. The apparatus as defined in claim 7 , wherein at least one of the display pixels ( 6 ) or a subpixel ( 5 ) of the display pixel ( 6 ) emits radiation in the infrared or ultraviolet range.

11. The apparatus as defined in claim 7 , wherein the display pixels ( 6 ) or subpixels ( 5 ) of the display pixels ( 6 ) emit monochromatic or colored light.

12. The apparatus as defined in claim 7 , wherein the display pixels ( 6 ) are component parts of an OLED.

13. The apparatus as defined in claim 7 , wherein each photosensor ( 4 ) comprises a color filter and/or each photosensor ( 4 ) is assigned a mask ( 7 ) for screening against direct illumination by the display pixels ( 6 ).

14. The apparatus as defined in claim 13 , wherein the mask ( 7 ) is a metallized mask.

15. The apparatus as defined in claim 7 , wherein each photosensor ( 4 ) comprises a plurality of sub-photosensors with one color filter.

16. The apparatus as defined in claim 7 , wherein each photosensor ( 4 ) or at least one of its sub-photosensors is sensitive to infrared light and/or comprises an infrared filter.

17. The apparatus as defined in claim 7 , wherein each photosensor ( 4 ) is assigned a microlens ( 3 ).

18. The apparatus as defined in claim 7 , wherein the microlens ( 3 ) is configured as a Fresnel lens or a holographic lens.

19. The apparatus as defined in claim 7 , wherein the microlens ( 3 ) is arranged between the cover plate ( 1 ) and the photosensor ( 4 ).

20. The apparatus as defined in claim 7 , wherein the screen is configured as a touch screen.

21. The apparatus as defined in claim 7 , wherein at least the display pixels ( 6 ) and the photosensors ( 4 ) are connected to a computer unit and a memory module.

22. The apparatus as defined in claim 7 , further comprising a switching device, wherein said switching device is coupled to a computer unit to actuate either a fingerprint recognition mode, wherein in in said fingerprint recognition mode, all display pixels ( 6 ) emit light radiation and the photosensors ( 4 ) of said display pixels ( 6 ) that are assigned thereto capture reflected light radiation, or a scan mode, wherein in said scan mode, the display pixels ( 6 ) are switched on and off sequentially in the pattern of a chessboard so as to emit light radiation, and the photosensors ( 4 ) of the respectively switched-off display pixels ( 6 ) are switched on to receive the reflected light radiation.

23. The apparatus as defined in claim 7 , wherein the cover plate ( 1 ) is configured as a flexible plastic film.

24. The apparatus as defined in claim 23 , wherein the plastic film is uncoated, hard-coated or covered by a further film, and/or consists of a plurality of layers film.

25. The apparatus as defined in claim 23 , wherein the further film is a graphene film.

26. The use of the apparatus as defined in claim 7 as a fingerprint sensor and/or a document scanner and/or a touch screen for a mobile telephone, a smart phone, a tablet computer and/or a stationary work screen computer.