Light modulating devices having grey scale levels using multiple state selection in combination with temporal and/or spatial dithering
First Claim
1. A light modulating device comprising an addressable matrix of modulating elements, and addressing means for selectively addressing each element in order to vary the transmission level of the element relative to the transmission levels of the other elements, wherein the addressing means includes spatial and/or temporal dither means for addressing separately addressable spatial bits of each element with different combinations of spatial dither signals and/or for addressing at least part of each element with different combinations of temporal dither signals applied to separately addressable temporal bits corresponding to subframes of different periods to produce a plurality of different transmission levels, and state selection means for switching the spatial and/or temporal bits between different states corresponding to different transmission levels in response to different state switching signals, whereby a plurality of different overall transmission levels are obtainable by selection of different combinations of spatial and/or temporal dither signals and state switching signals, characterized in that the state selection means is adapted to switch each of at least two bits of each element between more than two different states, at least one bit of each element being switchable between a lesser number of different states than other bit or bits of each element.
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Accused Products
Abstract
A ferroelectric liquid crystal display comprises an addressable matrix of pixels, and addressing circuitry for selectively addressing each pixel in order to vary the transmission level of the pixel relative to the transmission levels of the other pixels. The addressing circuitry includes spatial and/or temporal dither circuits for addressing separately addressable subpixels with different spatial dither signals and/or for addressing each pixel or subpixel with different temporal dither signals in separate subframes. In addition to such spatial and/or temporal dither, the addressing circuitry switches each pixel or subpixel between different grey states corresponding to different transmission levels, with at least two of the bits of spatial or temporal dither being switchable between more than two different grey states and at least one bit being switchable between a lesser number of different grey states than the or each other bit, so that a plurality of different overall transmission levels are achievable by different combinations of spatial and/or temporal dither and such grey states. This allows a larger number of substantially linearly spaced or suitably weighted grey levels to be produced than has previously been possible without giving rise to unacceptable complications.
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Citations
17 Claims
- 1. A light modulating device comprising an addressable matrix of modulating elements, and addressing means for selectively addressing each element in order to vary the transmission level of the element relative to the transmission levels of the other elements, wherein the addressing means includes spatial and/or temporal dither means for addressing separately addressable spatial bits of each element with different combinations of spatial dither signals and/or for addressing at least part of each element with different combinations of temporal dither signals applied to separately addressable temporal bits corresponding to subframes of different periods to produce a plurality of different transmission levels, and state selection means for switching the spatial and/or temporal bits between different states corresponding to different transmission levels in response to different state switching signals, whereby a plurality of different overall transmission levels are obtainable by selection of different combinations of spatial and/or temporal dither signals and state switching signals, characterized in that the state selection means is adapted to switch each of at least two bits of each element between more than two different states, at least one bit of each element being switchable between a lesser number of different states than other bit or bits of each element.
- 4. A light modulating device comprising an addressable matrix of modulating elements, and addressing means for selectively addressing each element in order to vary the transmission level of the element relative to the transmission levels of the other elements, wherein the addressing means includes spatial and/or temporal dither means for addressing separately addressable spatial bits of each element with different combinations of spatial dither signals and/or for addressing at least part of each element with different combinations of temporal dither signals applied to separately addressable temporal bits corresponding to subframes of different periods to produce a plurality of different transmission levels, and state selection means for switching the spatial and/or temporal bits between different states corresponding to different transmission levels in response to different state switching signals, whereby a plurality of different overall transmission levels are obtainable by selection of different combinations of spatial and/or temporal dither signals and state switching signals, characterised in that the state selection means is adapted to switch at least one bit of each element between more than two different states, at least one of the more significant bits of each element being switchable between a greater number of states than at least one other bit of each element.
Specification