Patent ID: 8204383

Claim:
A wireless communication interface for a portable wireless terminal, which wirelessly communicates with another device via a free space, the interface comprising: a first light source for generating a data-modulated infrared output signal; a first optical system for receiving as an input the infrared output signal from the first light source and outputting the infrared output signal to the free space; a second light source for generating a visible light output signal; a second optical system for receiving as an input the visible light output signal output from the second light source, for adjusting an intensity distribution of the input visible light, and for outputting the visible light output signal to the free space, with a second divergence angle determined based on the intensity distribution of the visible light output, wherein the second divergence angle is larger than a first divergence angle of the infrared output signal; an optical detector for receiving an infrared input signal from the free space, for generating an electrical input signal by photoelectrically converting the infrared input signal received from the free space, and outputting the electrical input signal; and a demodulation unit for demodulating the electrical input signal from the optical detector, and outputting a data signal, wherein the infrared output signal output from the first optical system exhibits a Gaussian intensity distribution which is more intense at the center, and more weak at both ends, and the visible light output signal from the first optical system exhibits a bimodal intensity distribution which is less intense at the center, and more intense at both ends of the distribution, and wherein a single intensity peak of the Gaussian intensity distribution is disposed between two intensity peaks of the bimodal intensity distribution.