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1. (WO2019008081) OPTICAL PROXIMITY SENSING CIRCUIT AND METHOD FOR OPTICAL PROXIMITY SENSING
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Claims

1. Optical proximity sensing circuit (1) comprising

an optical emitting device (10) which is prepared to send a signal (SI) having a wavelength of the invisible spectrum,

a light conversion material (11) being prepared to convert a reflected signal (S2) into a detectable signal (S3), the reflected signal (S2) being a function of a reflection of the signal (SI) off a human user (20) and the detectable signal (S3) having a wavelength of the visible spectrum, and

an optical receiving device (12) arranged apart from but in a visual range of the optical emitting device (10) and prepared to detect the detectable signal (S3) and

therefrom provide a measurement signal which is a

function of a distance between the optical proximity sensing circuit and the human user (20),

wherein the conversion material (11) is mounted to the optical receiving device (12), and

wherein each of the signal (SI), the reflected signal (S2) and the detectable signal (S3) is an optical signal.

2. Optical proximity sensing circuit (1) according to claim 1,

wherein the light conversion material (11) comprises a stimulated anti-stokes raman scattering material.

3. Optical proximity sensing circuit (1) according to claim 1 or 2,

wherein the optical emitting device (10) comprises at least one light-emitting diode which is prepared to emit light with a wavelength of approximately 1200nm as the signal (SI) , or

wherein the optical emitting device (10) comprises a vertical-cavity surface-emitting laser which is prepared to emit light with a wavelength of approximately 1500nm as the signal (SI) .

Optical proximity sensing circuit (1) according to any of claims 1 to 3,

wherein the optical receiving device (12) comprises at least one photo-diode which is sensitive for light in the range of 300nm to llOOnm.

Optical proximity sensing circuit (1) according to claim 4,

wherein the photo-diode is realized as a silicon photo-diode which is doped with an up-conversion material, the up-conversion material representing the conversion material (11).

Optical proximity sensing circuit (1) according to any of claims 1 to 5,

further comprising an optical barrier (13) which is mounted between the optical emitting device (10) and the optical receiving device (12) .

Optical proximity sensing circuit (1) according to any of claims 1 to 6,

further comprising

a first filter (131) mounted between the conversion material (11) and the optical receiving device (12), the first filter (131) being prepared to transmit light with a wavelength of about 950nm,

and / or

a second filter (132) mounted to the conversion material (11) such that the reflected signal (S2) passes the second filter (132) before reaching the conversion material (11), the second filter (132) being prepared to transmit light with a wavelength in the range of 1400nm to 1500nm.

Optical proximity sensing circuit (1) according to any of claims 1 to 7,

further comprising

a first optical lens (151) which is mounted to the optical emitting device (10), the first optical lens (151) representing a light-beam shaping means for the signal (SI) ,

and / or

a second optical lens (152) which is mounted to the conversion material (11), the second optical lens (152) representing a light-beam shaping means for the reflected signal ( S2 ) .

Optical proximity sensing circuit (1) according to any of claims 1 to 8,

wherein the optical conversion material (11) is semi transparent,

wherein the optical receiving device (12) is arranged in relation to the optical conversion material (11) such that the reflected signal (S2) passes through the optical conversion material (11) to hit the optical receiving device ( 12 ) , and

wherein the optical proximity sensing circuit (1) further comprises a blocking layer (14) which covers a surface of the optical receiving device (12) and a surface of the optical emitting device (10), the blocking layer (14) being prepared to prevent the detectable signal (S3) from leaving the optical proximity sensing circuit.

10. Optical proximity sensing circuit (1) according to any of claims 1 to 8,

wherein the optical conversion material (11) is

reflective, and wherein the optical receiving device (12) is arranged in relation to the conversion material (11) such that the reflected signal (S2) passes through the optical receiving device (12) to hit the conversion material (11).

11. Handheld device having

a bezel (17) which is prepared to form an outer surface of the device, wherein the bezel (17) faces a human user (20), and

the optical proximity sensing circuit (1) according to any of claims 1 to 10,

wherein the bezel (17) has a coating layer (171) which is transparent to the signal (SI), and wherein the optical proximity sensing circuit (1) is arranged beneath the coating layer (171) of the bezel (17) .

12. Handheld device according to claim 11,

further comprising a display (18) mounted between the bezel (17) and the optical proximity sensing circuit (1), wherein the display (18) comprises a liquid-crystal display or an active matrix organic light-emitting diode display, and

wherein the display (18) has a backside (19) which is transparent to the signal (SI) and the optical proximity sensing circuit (1) is arranged beneath the backside (19) of the display (18) ,

wherein the coating layer (171) of the bezel (17)

comprises an opening for receiving the display (18) .

13. Handheld device according to claim 11 or 12,

further comprising a post-processing component having an integrator circuit and an inverter circuit which can be selectively coupled to an input of the inverter circuit, the post-processing component being prepared to receive the measurement signal and to provide a measurement result as a function of an integration of the measurement signal .

14. Method for optical proximity sensing having the following steps

generating and sending a signal (SI) having a wavelength of the invisible spectrum,

receiving a reflected signal (S2) which is a function of a reflection of the signal (SI) off a human user (20), converting the reflected signal (S2) and therefrom providing a detectable signal (S3) having a wavelength of the visible spectrum,

receiving the detectable signal (S3) and therefrom providing a measurement signal which is a function of a distance between an optical proximity sensing circuit (1) and a human user (20),

wherein each of the signal (SI), the reflected signal (S2) and the detectable signal (S3) is an optical signal.

15. Method for optical proximity sensing according to claim 14,

wherein converting the reflected signal (S2) is realized by up-converting a wavelength of the reflected signal (S2) from a wavelength of the invisible spectrum into a wavelength of the visible spectrum as the wavelength of the detectable signal (S3) .

16. Method for optical proximity sensing according to claim 14 or 15,

further comprising

shaping the signal (SI) and / or the reflected signal (S2) ,

and / or,

filtering the reflected signal (S2) .