Patent EP0848369A2 successfully refreshed from Google Patents.
EP0848369A2
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Light Modulating devices
Assignee: Qinetiq Ltd
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Filing: 1997-12-16
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Granted: —
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Expires: 2017-12-16
Abstract
Abstract A ferroelectric liquid crystal display comprises an addressable matrix of pixels 32, and addressing circuitry 30, 31 for selectively addressing each pixel 32 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.
Inventors
- 👤 Jones John Clifford
- 👤 Hughes Jonathan Rennie
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 13:51
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3607; H; H04; H04N; H04N9/00; H04N9/12; H04N9/31; H04N9/3102; H04N9/3105; G09G3/3611; G09G3/3622; G09G3/3629; G09G3/364; G09G3/3648; G09G3/3651; H04N9/3129; G09G3/2007; G09G3/2011; G09G3/2018; G09G3/2044; G09G3/2051; G09G3/207; G09G3/2074; G09G3/2077; G09G3/2081
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
199 words
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 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 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 the or each other bit
of each element.
Claim 2
Dependent Claim
47 words
A light modulating device according to claim 1, wherein the state selection
means is adapted to switch at least two bits of each element between at least two
different states and at least one other bit between a lesser number of states, such as
only two states.
Claim 3
Dependent Claim
34 words
A light modulating device according to claim 1 or 2, wherein the state selection
means is adapted to switch said at least two bits of each element between the same
number of different states.
Claim 4
Dependent Claim
188 words
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 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
5 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 of the
more significant bits of each element between a greater number of states than at least
one other bit of each element.
Claim 5
Dependent Claim
41 words
A light modulating device according to claim 4, wherein the state selection
means is adapted to switch at least the most significant bit of each element between a
greater number of states than at least one other bit of each element.
Claim 6
Dependent Claim
39 words
A light modulating device according to claim 5, wherein the state selection
means is also adapted to switch the next most significant bit of each element between a
greater number of states than said other bit of each element.
Claim 7
Dependent Claim
82 words
A light modulating device according to any one of claims 1 to 6, wherein the
dither means is arranged to address the elements in only one dither dimension, and
such that the maximum number of overall transmission levels obtainable by selection
of different combinations of spatial or temporal dither signals and state switching
signals is n 1 x n 2 x......n i , where n 1 , n 2 ... n i are the numbers of different states of the bits,
1,2...i.
Claim 8
Dependent Claim
42 words
A light modulating device according to claim 7, wherein the relative
weightings of the i bits of dither are in the ratio (n 1 -1) : n 1 (n 2 -1) : ..... n 1 n 2 ... ni-1 (n i -1).
Claim 9
Dependent Claim
64 words
A light modulating device according to any one of claims 1 to 6, wherein the
dither means is arranged to address each element with i bits of spatial dither and j bits
of temporal dither where i and j are integers greater than or equal to 2, each bit being
switchable between an integral number of different states greater than or equal to 2.
Claim 10
Dependent Claim
72 words
A light modulating device according to any one of claims 1 to 6, wherein the
dither means is arranged to address each element with i bits of spatial dither along one
spatial dimension and j bits of spatial dither along another spatial dimension where i
and j are integers greater than or equal to 2, each bit being switchable between an
integral number of different states greater than or equal to 2.
Claim 11
Dependent Claim
53 words
A light modulating device according to claim 10, wherein the dither means is
arranged to further address each element with k bits of temporal dither where k is an
integer greater than or equal to 2, each bit being switchable between an integral
number of different states greater than or equal to 2.
Claim 12
Dependent Claim
103 words
A light modulating device according to claim 9, 10 or 11, wherein the dither
means is arranged to address each element in two dither dimensions, such that the
maximum number of overall transmission levels obtainable by selection of different
combinations of spatial and/or temporal dither signals and state switching signals is n 1 j x n 2 j x......n i j where n 1 , n 2 ... n i are the number of different states of the bits and the
same number of states are provided in each bit of the one dimension as in the
corresponding bit of the other dimension.
Claim 13
Dependent Claim
74 words
A light modulating device according to claim 12, wherein the relative
weightings of the i bits of dither in the one dimension are (n 1 -1) : n 1 (n 2 -1) : ... n 1 n 2 ...n i-1 (n i -1), and of the j bits of dither in the other dimension are 1 : n 1 n 2 ....n i : ...n i j-1 n 2 j-1 ....n i j-1 .
Claim 14
Dependent Claim
67 words
A light modulating device according to claim 13, wherein the dither means is
arranged to address each element in one dimension with two bits of dither with relative
weightings 1 : X representing a ratio which is chosen for manufacturing reasons, and
in the other dimension with an integral number of bits of dither with relative
weightings chosen to provide the desired range of overall transmission levels.
Claim 15
Dependent Claim
70 words
A light modulating device according to claim 14, wherein three bits of dither
are selected in the other dimension having n 1 , n 2 and n 3 different states respectively,
where n 1 , n 2 and n 3 are integers greater trim or equal to 2, with relative weightings (n 1 -1)
: {(n 1 -)(X+1)+1}(n 2 -1) : [{(n 1 -1)+[(n 1 -1)(X+1)+1](n 2 -1)}(X+1)+1](n 3 -1).
Claim 16
Dependent Claim
51 words
A light modulating device according to any preceding claim, wherein the
relative weightings of the bits of dither are chosen so as to minimise the redundancy of
overall transmission levels obtained by the different combinations of spatial and/or
temporal dither signals and state switching signals whilst maintaining the desired
greyscale progression.
Claim 17
Dependent Claim
32 words
A light modulating device according to any preceding claim, wherein the dither
means is arranged to vary the weightings of the bits of dither in dependence on the
temperature of the device.
References Cited (Backward Citations)
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