EP0478371A2
Expired / Lapsed
EP
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Liquid crystal display driver circuitry
Assignee: Fujitsu Ltd
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Filing: 1991-09-27
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Granted: —
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Expires: 2011-09-27
Abstract
Abstract Display driving circuitry is employed for providing to a liquid crystal display device connected with the circuitry a drive signal of a voltage level that can be selected from among a plurality of different predetermined voltage levels by application of respective digital selection signals (D₀,..,D₃) to the circuitry. The circuitry includes a voltage source for providing a set of supply voltage signals (V₀, V₁,...V n ) of respective different predetermined magnitudes; a plurality of switching elements (10,...17), each having an input terminal connected to the said voltage source for receiving therefrom one of the said supply voltage signals (V₀,...V n ) of the said set and also having an output terminal connected to a common output node (Yn) of the circuitry at which such a display device is connected when the circuitry is in use; and voltage selection means (21, 22) for connection to receive such digital selection signals and operable in response to receipt of one such selection signal to activate a predetermined group of the said switching elements, so as to cause such drive signal, of a predetermined voltage level that is associated individually with the selected switching elements, to be produced at the said common output node of the circuitry, the activation of the said switching elements being so controlled by the voltage selection means that the number of different predetermined voltage levels in the said plurality is greater than the number of supply voltage signals in the said set. Such circuitry can provide a desirably large number of different predetermined voltage levels to permit fine gray-scale control of a liquid crystal display element, without requiring an unacceptably large chip area.
Inventors
- 👤 Kazuhiro Takahara
- 👤 Tadahisa Yamaguchi
- 👤 Masami Oda
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 18:36
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/2007; G09G3/2011; G09G3/34; G09G3/36; G09G3/3611; G09G3/3648; G09G3/3685; G09G3/3688; G09G2310/00; G09G2310/02; G09G2310/0264; G09G2310/027
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
242 words
Display driving circuitry for providing to a display device connected with the circuitry a drive signal of a voltage level that can be selected from among a plurality of different predetermined voltage levels by application of respective digital selection signals (D₀, ,,,, D₃) to the circuitry, which circuitry includes: a voltage source for providing a set of supply voltage signals (V₀, V₁,,,,V n ) of respective different predetermined magnitudes; a plurality of switching elements (10,,,,17), each having an input terminal connected to the said voltage source for receiving therefrom one of the said supply voltage signals (V₀,,,,V n ) of the said set and also having an output terminal connected to a common output node (Yn) of the circuitry at which such a display device is connected when the circuitry is in use; and voltage selection means (21, 22) for connection to receive such digital selection signals and operable in response to receipt of one such selection signal to activate a predetermined group of the said switching elements, so as to cause such a drive signal, of a predetermined voltage level that is associated individually with the selected switching elements, to be produced at the said common output node of the circuitry, the activation of the said switching elements being so controlled by the voltage selection means that the number of different predetermined voltage levels in the said plurality is greater than the number of supply voltage signals in the said set.
Claim 2
Dependent Claim
70 words
Display driving circuitry as claimed in claim 1, wherein the said voltage selection means are operable in response to receipt of another such selection signal to activate just a predetermined one of the said switching elements, so as to cause such a drive signal, of a predetermined voltage level that is associated individually with the selected switching element, to be produced at the said common output node of the circuitry.
Claim 3
Dependent Claim
38 words
Display driving circuitry as claimed in claim 1, wherein the said voltage selection means are operable in response to receipt of the said respective digital selection signals to activate respective different predetermined groups of the said switching elements.
Claim 4
Dependent Claim
159 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale comprising: a plurality of power source voltage terminals (V0, V1 to Vn) applied with different voltage levels; an output terminal (Y) for providing a voltage to a display panel according to voltages applied through the voltage terminals (V0, V1 to Vn); a plurality of analog switches (10, 11 to 1n) with load resistances each having an input terminal connected to one of the power source voltage terminals (V0, V1 to Vn) , an output terminal connected to the output terminal (Y), and switching terminals switched to ON according to an input ON signal; and a selection circuit (2) having output terminals connected to plurality of analog switches (10, 11 to 1n) respectively and input terminals connected to a display data source that selectively transmits an ON signal to one or a plurality of the analog switches (10, 11 to 1n) according to a received data signal.
Claim 5
Dependent Claim
60 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 4 , wherein the selection circuit (2) divides the analog switches (10, 11 to 1n) into a plurality (m) of groups, and selectively transmits an ON signal to one or a plurality of the analog switches in each of the m groups.
Claim 6
Dependent Claim
70 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 4 , wherein the selection circuit (2) divides the analog switches (10, 11 to 1n) into a plurality (m) of groups, and selectively transmits an ON signal to one analog switch in each of the groups, or a plurality of analog switches to which adjacent ones of the voltage levels are applied.
Claim 7
Dependent Claim
84 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 4 , wherein the analog switches (10, 11 to 1n) each have two parallel transistors having different conduction types connected between the voltage terminals (V0, V1 to Vn) and the output terminal (Y), and a voltage selection signal provided by the selection circuit (2) and an inverted signal of the voltage selection signal are supplied to control terminals of the two transistors having different conduction types.
Claim 8
Dependent Claim
86 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 4 , wherein the analog switches (10, 11 to 1n) each have a p-channel MOSFET and an n-channel MOSFET connected parallel to each other between the voltage terminals (V0, V1 to Vn) and the output terminal (Y), and a voltage selection signal provided by the selection circuit (2) and an inverted signal of the voltage selection signal are supplied to gate terminals of the p-channel and n-channel MOSFETs.
Claim 9
Dependent Claim
39 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 4 , wherein additional resistances (r0, r1to rn) are connected in series to the analog switches (10, 11 to 1n), respectively.
Claim 10
Dependent Claim
60 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 9 , wherein the selection circuit (2) divides the analog switches (10, 11 to 1n) into a plurality (m) of groups, and selectively transmits an On signal to one or a plurality of the analog switches in each of the m groups,
Claim 11
Dependent Claim
67 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 9 , wherein the selection circuit (2) divides the analog switches (10, 11 to 1n) into a plurality (m) of groups, and selectively transmits an ON signal to one analog switch in each of the groups, or a plurality of analog switches to which adjacent voltage levels are applied.
Claim 12
Dependent Claim
84 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 9 , wherein the analog switches (10, 11 to 1n) each have two parallel transistors having different conduction types connected between the voltage terminals (V0, V1 to Vn) and the output terminal (Y), and a voltage selection signal provided by the selection circuit (2) and an inverted signal of the voltage selection signal are supplied to control terminals of the two transistors having different conduction types.
Claim 13
Dependent Claim
86 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 9 , wherein the analog switches (10, 11 to 1n) have each a p-channel MOSFET and an n-channel MOSFET connected parallel to each other between the voltage terminals (V0, V1 to Vn) and the output terminal (Y), and a voltage selection signal provided by the selection circuit (2) and an inverted signal of the voltage selection signal are supplied to gate terminals of the p-channel and n-channel MOSFETs.
Claim 14
Dependent Claim
43 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 9 , wherein the values of the additional resistances (r0, r1to rn) are higher than the values of the load resistances of the analog switches,
Claim 15
Dependent Claim
47 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 9 , wherein the additional resistances (r0, r1 to rn) are formed according to a diffusion resistance method, an ion implantation resistance method, or a thin film resistance method.
Claim 16
Dependent Claim
155 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale comprising: a plurality of power source voltage terminals (V0, V1 to Vn) applied with different voltage levels; an output terminal (Y) for providing a voltage to a display panel according to voltages applied through the voltage terminals (V0, V1 to Vn); a plurality of analog switch groups consisting of at least two analog switches with parallel load resistances each having switching terminals switched to ON according to an input ON signal, and each group having an input terminal connected to one of the power source voltage terminals (V0, V1 to Vn) and an output terminal connected to the output terminal (Y); and a selection circuit (2) having output terminals connected to each analog switch and input terminals connected to a display data source that selectively transmits at least one ON signal to each analog switch group according to a received data signal.
Claim 17
Dependent Claim
37 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 16 , wherein the load resistances of the analog switches in an analog switch group differ from one another.
Claim 18
Dependent Claim
47 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 17 , wherein the number of the analog switches in one analog switch group is two, and a ratio of the load resistance values thereof is 1 to 2.
Claim 19
Dependent Claim
109 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 16 , wherein the selection circuit (2) selects only one analog switch from only one analog switch group corresponding to a voltage level corresponding to one gray-scale level according to the input signal, or selects at least one analog switch from each of two different analog switch groups simultaneously corresponding to voltage levels representing a plurality of gray-scale levels, thereby an output voltage is one of the source voltage level or the intermediate level of the two different source voltage levels divided by the load resistances of the selected analog switches.
Claim 20
Dependent Claim
37 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 19 , wherein the load resistances of the analog switches in an analog switch group differ from one another.
Claim 21
Dependent Claim
47 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 20 , wherein the number of the analog switches in one analog switch group is two, and a ratio of the load resistance values thereof is 1 to 2.
Claim 22
Dependent Claim
87 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 19 , wherein, when the selection circuit (2) selects at least one analog switch from each of two different analog switch groups simultaneously, according to the input ON signal, the selection circuit (2) changes the number of the ON signal to transmit to one analog switch group for changing a combined value of the load resistances and thus the divided voltage level at the output terminal (Y) is changed.
Claim 23
Dependent Claim
37 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 22 , wherein the load resistances of the analog switches in one analog switch group differ from one another.
Claim 24
Dependent Claim
47 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 23 , wherein the number of the analog switches in an analog switch group is two, and a ratio of the load resistance values thereof is 1 to 2.
Claim 25
Dependent Claim
35 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 16 , wherein additional resistances (r00 to rnk) are connected in series with the every analog switch.
Claim 26
Dependent Claim
37 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 25 , wherein the load resistances of the analog switches in an analog switch group differ from one another.
Claim 27
Dependent Claim
47 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 26 , wherein the number of the analog switches in one analog switch group is two, and a ratio of the load resistance values thereof is 1 to 2.
Claim 28
Dependent Claim
110 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 25 , wherein the selection circuit (2) selects only one analog switch from only one analog switch group corresponding to a voltage level corresponding to one gray-scale level according to the input signal, or selects at least one analog switch from each of two different analog switch groups simultaneously corresponding to voltage levels representing a plurality of gray-scale levels, thereby an output voltage is one of the source voltage levels or the intermediate level of the two different source voltage level, divided by by the load resistances of the selected analog switches.
Claim 29
Dependent Claim
37 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 28 , wherein the load resistances of the analog switches in an analog switch group differ from one another.
Claim 30
Dependent Claim
47 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 29 , wherein the number of the analog switches in one analog switch group is two, and a ratio of the load resistance values thereof is 1 to 2.
Claim 31
Dependent Claim
85 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 28 , wherein, when the selection circuit (2) selects at least one analog switch from each of two different analog switch groups simultaneously according to the input ON signal, the selection circuit (2) changes the number of ON signals transmitted to one analog switch group for changing a combined value of the load resistances and thus the divided voltage level at the output terminal (Y) is changed.
Claim 32
Dependent Claim
37 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 31 , wherein the load resistances of the analog switches in one analog switch group differ from an another.
Claim 33
Dependent Claim
47 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 32 , wherein the number of the analog switches in one analog switch group is two, and a ratio of the load resistance values thereof is 1 to 2.
Claim 34
Dependent Claim
43 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 25 , wherein the values of the additional resistances (r00 to rnk) are higher than the values of the load resistances of the analog switches.
Claim 35
Dependent Claim
46 words
A digital data driver circuit of liquid crystal display for achieving digital gray-scale as set forth in claim 25 , wherein the additional resistances (r00 to rnk) are made according to a diffusion resistance method, an ion implantation resistance method, or a thin film resistance method.
References Cited (Backward Citations)
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