| 摘要 |
<p>In order to simplify and reduce the dimensions of wiring, a light-emitting section (3) and a light receiving section (4) are each formed from a semi-conductor bare chip (a light-emitting diode chip and a photo-diode chip), and the optical path of the infrared light from the light-emitting section (3) to the light-receiving section (4) is altered so as to be a polygonal line rather than a straight line. Therefore, in comparison to conventional examples (see patent documents 1 and 2) in which package-type light-emitting diodes and photo-diodes are used, this embodiment has the benefit of simplifying the wiring. Additionally, in this embodiment the optical path of the infrared light (see the dashed line in fig. 1) is altered by a first reflecting mirror (80) and a second reflecting mirror (81) so as to be approximately a 'C' shape, and thus the dimensions of the vertical height of the optical path can be reduced (given a low profile) without reducing the length of the optical path, in contrast to the conventional example disclosed in document 2 in which the optical path is approximately a 'V' shape.</p> |
