Abstract: The present invention provides a headrest (1C, 2C) in which a bone-conduction microphone (1B, 2B) is mounted in such a position as to be in contact with the back side of the head of the operator. The invention also provides a mobile body comprising the headrest (1C, 2C) as a constituent member and characterized in that the output of the bone-conduction microphone is used for a telephone voice or for speech recognition control of a device such as one installed on a vehicle. The invention further provides a mobile body comprising the headrest as a constituent member and characterized in that sleep of the operator is detected by the output of the bone-conduction microphone (1B, 2B).

Abstract: A double directional image development HUD includes a combiner having individual spectral distributions perfectly separated from each other, wherein the image displayed on an LCDU is formed using green light with a sharp spectral distribution and using another color light with a different wavelength, and wherein light beams projected from the LCDU onto a combiner are perfectly divided into two beams, i.e., a reflection light beam and a transmission light beam both of which are perfectly separated from each other, thereby obtaining a clear projected image to be observed by the observers inside and outside the combiner without any contamination.

Abstract: A head up display is provided for projecting as a virtual image the information from control meters in an airplane or an automobile in the front visual field. The display includes a light source disposed at the bottom of a casing, an LCD shutter disposed just above the light source, a first Fresnel lens disposed on the upper surface of the casing for the purpose of enlarging information on the LCD shutter, and a combiner disposed at an adjustable angle on the upper surface of the casing for the purpose of producing a virtual image of the information on the LCD shutter. The first Fresnel lens is disposed on the same face as that of the dashboard, and another Fresnel lens is provided on the front side of the casing so that the meter can be directly viewed through the casing.