EP0523797A2
Expired / Lapsed
EP
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Matrix display device and its method of operation
Assignee: Philips Electronics UK Ltd
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Filing: 1992-07-10
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Granted: —
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Expires: 2012-07-10
Abstract
Abstract A matrix display device comprises a row and column array of picture elements (12) each of which consists of a display element (14), e.g. a LC display element, connected in series with a two-terminal non-linear device 15, such as a MIM, between associated row and column address conductors (16,17) to which selection and data signals are applied by a scanning signal drive circuit (20) and a data signal drive circuit (22) respectively, and a reference element circuit (34), comprising a non-linear device (35) in series with a capacitor (36), forming part of a feedback arrangement through which picture element drive voltages are controlled (25) so as to compensate for the effects of ageing of the non-linear devices. The reference circuit is driven like the picture elements, with a scanning signal waveform and voltage signal (V A ) applied to opposite sides, and the picture element drive voltages are adjusted in accordance with predetermined changes in the voltage across the capacitor (36). The reference non-linear device (35) can be provided on the same support (10) as the picture element devices (15). The capacitor (36) can be constituted by an electro-optic element corresponding to the display elements (14). A plurality of such reference circuits may be employed, extending in one or more rows and driven by row and column conductors.
Inventors
- 👤 Alan George Knapp
- 👤 Martin John Edwards
- 👤 Roger Pook
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 13:45
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3611; G09G3/367; G09G2310/00; G09G2310/06; G09G2310/061; G09G2320/00; G09G2320/04; G09G2320/043
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
209 words
A matrix display device comprising sets of row and column address conductors, a row and column array of picture elements operable to produce a display, each of which comprises an electro-optic display element connected in series with a two terminal non-linear device exhibiting a threshold characteristic between a row conductor and a column conductor, and picture element drive means connected to the sets of address conductors for applying drive voltages to the picture elements comprising a scanning signal drive circuit for applying selection signals to the conductors of one set and a data signal drive circuit for applying data signals to the conductors of the other set, characterised in that the display device includes a reference circuit comprising a capacitor connected in series with a non-linear device of the same kind as those of the picture elements, means for applying to one side of the reference circuit a waveform corresponding to that applied by the scanning signal drive circuit to the conductors of the one set and a voltage signal to the other side of the reference circuit, and control means for adjusting the drive voltages applied by the drive means to the picture elements according to predetermined changes in the voltage across the capacitor of the reference circuit.
Claim 2
Dependent Claim
31 words
A matrix display device according to Claim 1, characterised in that the control means adjusts the level of the selection signals according to predetermined changes in the voltage across the capacitor.
Claim 3
Dependent Claim
48 words
A matrix display device according to Claim 2, characterised in that the control means includes a comparator which compares a time-averaged value of the voltage across the capacitor with a reference voltage and controls the level of the selection signals in accordance with the output of the comparator.
Claim 4
Dependent Claim
55 words
A matrix display device according to Claim 2, characterised in that the scanning signal drive circuit applies to the conductors of the one set a scanning signal waveform which comprises reset signals in addition to the selection signals and in that the control means is arranged also to adjust the level of the reset signals.
Claim 5
Dependent Claim
23 words
A matrix display device according to Claim 1, characterised in that the voltage signal applied to the reference circuit has a preset level.
Claim 6
Dependent Claim
36 words
A matrix display device according to Claim 1, characterised in that the level of the voltage signal applied to the reference circuit is determined according to the level of data signals applied to the picture elements.
Claim 7
Dependent Claim
37 words
A matrix display device according to Claim 1, characterised in that the non-linear device of the reference circuit is carried on a support separate to that on which the non-linear devices of the picture elements are carried.
Claim 8
Dependent Claim
40 words
A matrix display device according Claim 1, characterised in that the non-linear device of the reference circuit and the non-linear devices of the picture elements are carried on a common support together with one of the sets of address conductors.
Claim 9
Dependent Claim
31 words
A matrix display device according to Claim 8, characterised in that the non-linear device of the reference circuit is connected to an address conductor of the set carried on said support.
Claim 10
Dependent Claim
28 words
A matrix display device according to Claim 9, characterised in that the set of address conductors carried on the support are connected to the scanning signal drive circuit.
Claim 11
Dependent Claim
26 words
A matrix display device according to Claim 9, characterised in that the capacitor of the reference circuit is provided at least in part on said support.
Claim 12
Dependent Claim
27 words
A matrix display device according to Claim 11, characterised in that the capacitor comprises an electro-optic element having a structure corresponding to that of the display elements.
Claim 13
Dependent Claim
44 words
A matrix display device according to Claim 12, characterised in that the electro-optic element of the reference circuit is connected to an address conductor of the other of the sets of address conductors through which the voltage signal is applied to the reference circuit.
Claim 14
Dependent Claim
44 words
A matrix display device according to Claim 12, characterised in that the display device includes a plurality of reference circuits arranged as a set to which a scanning signal waveform is applied through an address conductor common to the reference circuits of the set.
Claim 15
Dependent Claim
22 words
A matrix display device according to Claim 14, characterised in that the display device includes a plurality of sets of reference circuits.
Claim 16
Dependent Claim
49 words
A matrix display device according to Claim 15, characterised in that at least one set is arranged adjacent to one side of the area occupied by the array of picture elements and in that at least one other set is arranged adjacent to the opposing side of said area.
Claim 17
Dependent Claim
19 words
A matrix display device according Claim 1, characterised in that the electro-optic display elements comprise liquid crystal display elements.
Claim 18
Dependent Claim
16 words
A matrix display device according to Claim 1, characterised in that the non-linear devices comprise MIMs.
Claim 19
Independent Claim
183 words
A method of operating a matrix display device comprising sets of row and column address conductors, a row and column array of picture elements operable to produce a display, each of which comprises an electro-optic display element connected in series with a two terminal non-linear device exhibiting a threshold characteristic between a row conductor and a column conductor, in which drive voltages are applied to the picture elements by applying scanning signals comprising selection signals to the conductors of one set and data signals to the conductors of the other set, characterised by the steps of driving a reference circuit comprising a capacitor connected in series with a non-linear device of the same kind as those of those of the picture elements by applying to one side of the reference circuit a waveform corresponding to the scanning signals applied to the conductors of the one set and a voltage signal to the other side of the reference circuit, and controlling the drive voltages applied to the picture elements in accordance with predetermined variations in the voltage across the capacitor of the reference circuit.
Claim 20
Dependent Claim
26 words
A method according to Claim 19, characterised in that the level of the selection signals is controlled in accordance with predetermined variations in the capacitor voltage.
Claim 21
Dependent Claim
44 words
A method according to Claim 20, characterised by the steps of deriving a signal indicative of the time averaged value of the capacitor voltage, comparing this signal with a reference value, and varying the level of the selection signals according to the difference therebetween.
Claim 22
Dependent Claim
25 words
A method according to Claim 19, characterised in that the voltage signal is determined by the level of data signals applied to the picture elements.
Claim 23
Dependent Claim
46 words
A method according to Claim 19, characterised in that a plurality of reference circuits are provided and in that the picture element drive voltages are controlled in accordance with predetermined variations in the average of the voltages across the capacitors of the plurality of reference circuits.
References Cited (Backward Citations)
No citation records indexed.
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