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Sharp expands its repertoire of LCD-plus displays for in-car use

The display-research arm of Sharp Electronics has revealed some of its advanced work exploring options in LCD-display technology for automotive use, including an enhanced version of its dual-view LCD panel and a dual-depth panel that shows information on two visual planes.

Sharp already supplies its dual-view panels to two European car manufacturers, who install them in the centre console of the dashboard. The dual-view panel shows two completely separate images when viewed off-centre from either side of the display. In the automotive application, the driver can see only relevant information such as navigation or car-systems menus, while the front-seat passenger can view entertainment content. In the fi rst generation of panels, now in production, Sharp achieves the image separation with a parallax barrier: the two images appear on interleaved vertical pixel strips, and a vertical linear grating in front of the screen obscures the set of pixel strips corresponding to the “hidden” image on the respective side.

Now, Sharp has developed an enhanced version of the screen, which, the company hints, may use micro-lens arrays rather than an aperture grating. This allows the company to tune the performance to different use cases; you can have twice the brightness of the previous version at the cost of a somewhat wider region of “mixing”—that is, where the viewer sees both images superimposed (see the example in the photo sequence). Or, you can achieve almost no region of mixed images, but with similar brightness to that of the fi rst-generation panels. Sharp’s researchers say that a threeimage panel—right, left and centre—is also now possible.

The second innovation is a dual-depth panel. This is not a 3-D panel, but one in which there are, visually, two distinct image planes that appear at different distances. The optics involve a standard panel with a layered arrangement of optical planes, including a partially refl ecting mirror and polarisers, in front of it. The light path through the extra optics is electrically switchable. In one state, light passes straight through, and the viewer sees the LCD screen directly. In the alternative state, light from the panel internally refl ects within the arrangement of polarisers before exiting in the direction of the viewer. The optical-path length is increased by twice the thickness of the polariser/ mirror-assembly layer, and therefore the image appears to the viewer to be displaced backwards by that amount. You might use it to display, say, destination information over a map; or to highlight which of a set of touch-screen buttons are active at any given time. The extra layer can be an air gap for maximum transparency, or a high-index plastic for maximum depth illusion. Due to the multiple internal refl ections, the primary image appears to be 25% as bright as the native LCD screen, and the “deeper” image 12.5%. The illusion is maintained for viewing angles up to ±15° from the axis perpendicular to the screen.

Sharp has also indicated that it is exploring technologies to manufacture—economically— LCD panels for automotive dashboards that are not rectangular— they are circular, for example, or with rounded corners—and are not fl at. A spokesman confi rmed the company’s belief that, of all currently available display technologies, and despite the challenges of non-rectangular formats, adapting LCDs remains the most favoured option for the foreseeable future, in contrast to less-developed alternatives such as OLED.

Sharp, www.sharpsme.com