Abstract: An optical scanning apparatus is equipped with a light source for outputting a scanning beam having a single fixed direction polarization component. A polarization control element is provided for changing the polarization direction of the scanning beam outputted from the light source. An optical element is provided for splitting the scanning beam outputted from the polarization control element into two linearly polarized beams that orthogonally cross each other. An image formation element is utilized for forming images with the two linearly polarized beams outputted from the optical element at independent locations on a scanning surface. A signal processing device is provided for controlling the light source and the polarization control element, and for switching on and off the two linearly polarized beams.

Abstract: A headup display apparatus consists of a projection optical system unit installed in the dashboard of a car and a reflection member on the windshield. The projection optical system unit contains an indicator and an off-axis reflective hologram which reflects display light of the indicator toward the windshield, which in turn reflects it toward the viewing point of a driver. As a result, the display is seen superimposed on the exterior view. When external light as from the sun enters the projection optical system unit traveling in a direction reverse to the path of the display light, the off-axis reflective hologram reflects the incident external light toward a direction different from that of the outgoing display light to minimize an abnormal illumination of the indicator surface which would otherwise render the display unrecognizable. Behind the hologram is installed a heat dissipating member that receives infrared rays that have transmitted the hologram in order to dissipate heat.

Abstract: A display unit including an indicator (1) for projecting a predetermined image, an image forming optical system (3) for forming a real image at a predetermined position according to the image projected by the indicator, and a transparent hologram screen (10) disposed at the image forming position of the image forming optical system to diffract the real image in a predetermined direction with a directivity.

Abstract: In construction of a tremolo unit for an electric guitar, a bridge is coupled to a swingable bridge base in an arrangement movable in the string direction and provided with a string hole formed there through, a presser piece is received in the string hole for movement in the string direction, and a lock bolt screwed into the bridge forces the presser piece to press a string to the wall of the string hole with a string bead being locked against the lower end of the string hole. A dual fixing mechanism based on string pressing and bead locking well alleviates damage on the string construction caused by pressure application. The bridge and the presser piece are both made of iron-type metal for improvement in tone color of musical tones generated by the electric guitar.

Abstract: A tremolo unit mechanism for an electric guitar includes a bridge base vertically disposed to be pivotal about a support point on a body, balancing springs for causing a balance moment along a direction opposite to that of a moment due to a tension of strings to act on the bridge base, bridge main bodies, disposed on the bridge base, for holding one end of each of the strings, octave adjusting screws, threadably engaged with the bridge base, for moving the bridge base along a front-to-rear direction, a tremolo arm, mounted in the bridge base, for moving the bridge base vertically, and a control mechanism for controlling pivotal movement of the bridge base. The control mechanism includes an engaging member for engaging with the bridge base and a screw member for controlling pivotal movement/displacement of the engaging member.