Optical proximity sensing circuit comprising - an optical emitting device which is prepared to send a signal (S1) having a wavelength of the invisible spectrum, - a light conversion material 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 (S1) off a human user and the detectable signal (S3) having a wavelength of the visible spectrum, and - an optical receiving device arranged apart from but in a visual range of the optical emitting device 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 , wherein the conversion material is mounted to the optical receiving device , and wherein each of the signal (S1), the reflected signal (S2) and the detectable signal (S3) is an optical signal, and wherein the optical conversion material is semi transparent, wherein the optical receiving device is arranged in relation to the optical conversion material such that the reflected signal (S2) passes through the optical conversion material to hit the optical receiving device , characterized by wherein the optical proximity sensing circuit further comprises a blocking layer which covers a surface of the optical receiving device and a surface of the optical emitting device , the blocking layer being prepared to prevent the detectable signal (S3) from leaving the optical proximity sensing circuit. - an optical emitting device which is prepared to send a signal (S1) having a wavelength of the invisible spectrum, - a light conversion material 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 (S1) off a human user and the detectable signal (S3) having a wavelength of the visible spectrum, and - an optical receiving device arranged apart from but in a visual range of the optical emitting device 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 , wherein the conversion material is mounted to the optical receiving device , and wherein each of the signal (S1), the reflected signal (S2) and the detectable signal (S3) is an optical signal, and wherein the optical conversion material is semi transparent, wherein the optical receiving device is arranged in relation to the optical conversion material such that the reflected signal (S2) passes through the optical conversion material to hit the optical receiving device , characterized by wherein the optical proximity sensing circuit further comprises a blocking layer which covers a surface of the optical receiving device and a surface of the optical emitting device , the blocking layer being prepared to prevent the detectable signal (S3) from leaving the optical proximity sensing circuit. wherein the conversion material is mounted to the optical receiving device , and wherein each of the signal (S1), the reflected signal (S2) and the detectable signal (S3) is an optical signal, and wherein the optical conversion material is semi transparent, wherein the optical receiving device is arranged in relation to the optical conversion material such that the reflected signal (S2) passes through the optical conversion material to hit the optical receiving device , characterized by wherein the optical proximity sensing circuit further comprises a blocking layer which covers a surface of the optical receiving device and a surface of the optical emitting device , the blocking layer being prepared to prevent the detectable signal (S3) from leaving the optical proximity sensing circuit. <EOS>