Communications: electrical – Land vehicle alarms or indicators – Internal alarm or indicator responsive to a condition of the...
Patent
1990-05-29
1992-07-21
Oberley, Alvin E.
Communications: electrical
Land vehicle alarms or indicators
Internal alarm or indicator responsive to a condition of the...
340783, 3408151, 34081527, 40476, 40491, G09G 316
Patent
active
051326752
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a display element or a pixel and to a display device comprising a plurality of such elements or pixels, and in particular to a lightreflective display element or pixel with controllable light reflecting properties. In the context of the present specification and claims, the term `pixel` means a dot or element within a display device which forms only a small proportion of the total image display area.
Display devices such as a large-scale picture devices in sports arenas and alpha-numeric display devices at airports and railway stations suffer from a number of disadvantages. For example with light-emitting colour displays such as tricolour displays only a fraction of the surface area is used to provide each colour. To indicate "blue" on a device employing the principle of colour television, less than a third of the available surface area may be used. With devices employing coloured bulbs, even a smaller fraction of the surface area may be used. The displays of mechanical lightreflective display devices employing shutters or flaps can be varied only relatively slowly; in addition the shutters are either visible, in which case they spoil the visual appearance of the display, or hidden behind fixed covers, which reduces the effective surface area of the display.
The present invention seeks to overcome or reduce one or more of the above disadvantages.
An earlier proposal in WO 87/07066 proposes a display device consisting of a plurality of pixels as hereinbefore defined arranged to form a matrix covering an area, and control means for individually setting the properties of each pixel whereby desired information can be displayed over said area, characterised by light reflective pixels which each comprise a plurality of sets of two or more vanes arranged one behind the other with a forward surface of each set visible from the front, the vanes within each set lying in closely adjacent parallel planes, the sets being also parallel but displaced one behind the other; driving means for individually driving each group formed by corresponding vanes in each set, except the foremost, so that the vane forward surfaces are selectively viewable from the front; each group of vanes being coloured with a respective plain colour different from that of the other group(s). Using pixels of the kind described allows a full spectrum of colour mixtures to be obtained by using one fixed and two movable groups of vanes, each group being coloured with one plain primary colour.
It has now been realised that a similar mechanism but employing only one fixed and one movable vane per set can be used to provide a wide spectrum of colour mixtures. According to the invention, there is provided a light reflective display element having a plurality of sets of two vanes arranged with a forward surface of each set visible from the front, the vanes within each set lying one behind the other in closely adjacent parallel planes, the sets being also parallel but displaced one behind the other; the rear group of vanes being drivable so that its forward surfaces are selectively viewable from the front; and driving means capable of positioning the movable vanes in two extreme positions and also in an intermediate position, whereby differently coloured areas on each vane are exposed or covered so as to provide at least three different colour mixes from the two vanes of each set. Such a display element allows the display of highly contrasted colours from fewer groups of vanes; thus it is cheaper to manufacture and simpler to control than the earlier proposal.
In a preferred form the vanes are divided into at least two areas extending across the vanes transversely to the direction of movement, which areas carry different plain colours.
Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which:
FIG. 1 shows a bottom perspective view of a display element in accordance with a first embodiment of the present invention.
FIG. 2 shows a side vi
REFERENCES:
patent: 3161726 (1964-12-01), Todt
patent: 4949488 (1990-08-01), Holk
patent: 4958150 (1990-09-01), Dabbaj
Nguyen Chanh
Oberley Alvin E.
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