Patent ID: 8783884
Filing Date: 2014-07-22
Classification: G09F,H01H

Abstract:
1. A display device for displaying two graphics, the display device comprising: a first light transmitting substrate having a front surface and a rear surface, and the first light transmitting substrate including, on its rear surface, at least one etched region corresponding to a first graphic to be displayed; a second light transmitting substrate located behind and spaced apart from the first light transmitting substrate, the second light transmitting substrate having a front surface and a rear surface, and the second light transmitting substrate including, on its front surface, at least one etched region corresponding to a negative of the first graphic; a first light source arranged to emit light into the first light transmitting substrate such that the first light transmitting substrate acts as a light pipe conveying said emitted light within the first light transmitting substrate to said at least one etched region; a second light source positioned behind the second light transmitting substrate and arranged to emit light through the first and second light transmitting substrates towards a viewer of the display; and a mask layer comprising at least one opaque region, said at least one opaque region defining at least one light transmissive region corresponding to a second graphic to be displayed, the mask layer being provided between the second light source and the rear surface of the first light transmitting substrate; wherein, in use, when the first light source is illuminated and the second light source is not illuminated, light conveyed within the first light transmitting substrate is incident on said etched region(s) on the rear surface of the first light transmitting substrate and is directed out of the front surface of the first light transmitting substrate thereby displaying only the first graphic to a viewer of the display, and when the second light source is illuminated and the first light source is not illuminated, light emitted by the second light source is blocked by said opaque region(s) of the mask layer and passes through said light transmissive region(s) and through the first and second light transmitting substrates thereby displaying only the second graphic to a viewer of the display, said passed light also passing through either the etched region(s) on the rear surface of the first light transmitting substrate or through the etched region(s) on the front surface of the of the second light transmitting substrate so that the first graphic is concealed when the second graphic is displayed.