Patent US4899141A successfully refreshed from Google Patents.
US4899141A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Matrix panel with an active driving system
Assignee: Seiko Epson Corp
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Filing: 1986-02-20
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Granted: 1990-02-06
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Expires: 2006-02-20
Abstract
Abstract In the matrix, a positive type liquid crystal of the twisted nematic type is driven by a thin film transistor arranged on a transparent substrate. The polarity of the video signal, originally generated for a cathode ray tube, is inverted within a driving circuit and the inverted negative video signal is used to drive the positive type liquid crystal display. In the range of voltages of the video signal which correspond to the white level, the active matrix panel is driven by stretching the voltage of the video signal such that comparable voltage-contrast characteristics are achieved with the liquid crystal display as with the cathode ray tube. Leakage current of the thin film transistor during off-periods is reduced by setting a gate voltage during the off-period which is within the range of voltage level of the power source.
Inventors
- 👤 Shinji Morozumi
- 👤 Toshiyuki Misawa
- 👤 Yoshio Nakazawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:09
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/12; H04N3/127
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
127 words
An active driving system for a liquid crystal matrix panel having a plurality of cells each including switching means having a switching terminal for switching the cell on and off during selected and non-selected periods respectively and a picture element, said matrix panel receiving an external video signal adapted to a cathode ray tube display and a frame signal, the active driving system comprising: scaling means for amplifying the external video signal to produce two scaled video signals having bias voltages and amplitudes of opposite polarities, the scaling means being adapted to produce voltages in a range between a high driving voltage and ground and the switching terminal voltage of each of the switching means during non-selected periods is in the voltage range of the scaling means.
Claim 2
Dependent Claim
127 words
An active driving system for a liquid crystal matrix panel having a plurality of cells each including switching means having a switching terminal for switching the cell on and off during selected and non-selected periods respectively and a picture element, said matrix panel receiving an external video signal adapted to a cathode ray tube display and a frame signal, the active driving system comprising: scaling means for amplifying the external video signal to produce two scaled video signals having bias voltages and amplitudes of opposite polarities, the scaling means being adapted to produce voltages in a range between a high driving voltage and ground and the switching terminal voltage of each of the switching means during non-selected periods is in the voltage range of the scaling means.
Claim 3
Dependent Claim
38 words
The active driving system of claim 1 wherein the scaling means includes means for varying the amplitude and bias voltages of the two scaled video signals to correspond to the brightness-voltage characteristics of the liquid crystal matrix panel.
Claim 4
Dependent Claim
58 words
The active driving system of claim 1 further comprising stretching means for extending the range of voltages of the external video signals from the narrow voltage for a cathode ray tube display to a broader voltage range necessary to cover a fuller range of contrasts in the liquid crystal than would be possible with the external video signal.
Claim 5
Dependent Claim
19 words
The active driving system of claim 1 wherein the switching terminal voltages are proximate to the common voltage level.
Claim 6
Dependent Claim
59 words
The active driving system of claim 2 further comprising stretching means for extending the range of voltages of the external video signal from the narrow voltage range for a cathode ray tube display to a broader voltage range necessary to cover a fuller range of contrasts in the liquid crystal than would be possible with the external video signal.
Claim 7
Dependent Claim
25 words
The active driving system of claim 5 wherein the selector means alternates selecting between the two scaled video signals in synchronization with the frame signal.
Claim 8
Dependent Claim
24 words
The active driving system of claim 1 wherein each of the switching means comprises a transistor and the switching terminal is the gate electrode.
Claim 9
Dependent Claim
32 words
The active driving system of claim 1 further comprising selector means coupled to the scaling means for producing a new scaled video signal by alternately selecting between the two scaled video signals.
Claim 10
Dependent Claim
161 words
An active driving system for a liquid crystal matrix panel having a plurality of cells each including a switching means including a switching terminal for switching the cell on and off during selected and non-selected periods, respectively, and a picture element, said matrix panel receiving an external video signal adapted to a cathode ray tube display and a frame signal, the active driving system comprising: scaling means for amplifying the external video signal to produce two scaled video signals having amplitudes which are symmetrical with respect to a common voltage level, and first and second bias voltages which have opposite voltage polarities, the scaling means being adapted to produce voltages in a range between a high driving voltage and ground and the switching terminal voltage during the nonselected period is in the voltage range of the scaling means; and selector means coupled to the scaling means for producing a composite scaled video signal by alternately selecting the two scaled video signals.
Claim 11
Dependent Claim
161 words
An active driving system for a liquid crystal matrix panel having a plurality of cells each including a switching means including a switching terminal for switching the cell on and off during selected and non-selected periods, respectively, and a picture element, said matrix panel receiving an external video signal adapted to a cathode ray tube display and a frame signal, the active driving system comprising: scaling means for amplifying the external video signal to produce two scaled video signals having amplitudes which are symmetrical with respect to a common voltage level, and first and second bias voltages which have opposite voltage polarities, the scaling means being adapted to produce voltages in a range between a high driving voltage and ground and the switching terminal voltage during the nonselected period is in the voltage range of the scaling means; and selector means coupled to the scaling means for producing a composite scaled video signal by alternately selecting the two scaled video signals.
Claim 12
Dependent Claim
24 words
The active driving system of claim 9 wherein the bias voltages for a first and second of the two scaled video signals are unequal.
Claim 13
Dependent Claim
33 words
The active driving system of claim 9 wherein the scaling means varies the bias voltages of the two scaled video signals to correspond to the brightness-voltage characteristics of the liquid crystal matrix panel.
Claim 14
Dependent Claim
33 words
The active driving system of claim 10 wherein the scaling means varies the bias voltages of the two scaled video signals to correspond to the brightness-voltage characteristics of the liquid crystal matrix panel.
Claim 15
Dependent Claim
59 words
The active driving system of claim 10 further comprising stretching means for extending the range of voltages of the external video signal from the narrow voltage range for a cathode ray tube display to a broader voltage range necessary to cover a fuller range of contrasts in the liquid crystal than would be possible with the external video signal.
Claim 16
Dependent Claim
23 words
The active driving system of claim 9 wherein the switching terminal voltages of the switching means are proximate to the common voltage level.
Claim 17
Dependent Claim
24 words
The active driving system of claim 9 wherein each of the switching means comprises a transistor and the switching terminal is the gate electrode.
Claim 18
Dependent Claim
151 words
An active driving system for a liquid crystal matrix panel having a plurality of cells each including a switching means including a switching terminal for switching the cell on and off during selected and non-selected periods, respectively, and a picture element, said matrix panel receiving an external video signal adapted to a cathode ray tube display and a frame signal, the active driving system comprising: scaling means for amplifying the external video signal to produce two scaled video signals having amplitudes and first and second bias voltages which have opposite voltage polarities, the scaling means being adapted to produce voltages in a range between a high driving voltage and ground and the switching terminal voltage during the nonselected period is in the voltage range of the scaling means; and selector means coupled to the scaling means for producing a composite scaled video signal by alternately selecting the two scaled video signals.
Claim 19
Dependent Claim
151 words
An active driving system for a liquid crystal matrix panel having a plurality of cells each including a switching means including a switching terminal for switching the cell on and off during selected and non-selected periods, respectively, and a picture element, said matrix panel receiving an external video signal adapted to a cathode ray tube display and a frame signal, the active driving system comprising: scaling means for amplifying the external video signal to produce two scaled video signals having amplitudes and first and second bias voltages which have opposite voltage polarities, the scaling means being adapted to produce voltages in a range between a high driving voltage and ground and the switching terminal voltage during the nonselected period is in the voltage range of the scaling means; and selector means coupled to the scaling means for producing a composite scaled video signal by alternately selecting the two scaled video signals.
Claim 20
Dependent Claim
31 words
The active driving system of claim 16 wherein the scaling means includes amplifying means for modifying the external video signal whereby the amplitudes of the two scaled video signals are unequal.
Claim 21
Dependent Claim
115 words
An active driving system for a flat panel display having a plurality of cells each including a transistor having a gate, source and drain for switching a corresponding cell on and off during selected and non-selected periods, respectively, and a picture element, each transistor characterized by a flow of leakage current which can vary during the non-selected period, the active driving system comprising: gate means for providing a gate signal to each transistor for increasing during the selected period and decreasing during the non-selected period the current flow between the drain and source of each transistor; and leakage current minimizing means for minimizing the flow of leakage current for each transistor during its non-selected period.
Claim 22
Dependent Claim
115 words
An active driving system for a flat panel display having a plurality of cells each including a transistor having a gate, source and drain for switching a corresponding cell on and off during selected and non-selected periods, respectively, and a picture element, each transistor characterized by a flow of leakage current which can vary during the non-selected period, the active driving system comprising: gate means for providing a gate signal to each transistor for increasing during the selected period and decreasing during the non-selected period the current flow between the drain and source of each transistor; and leakage current minimizing means for minimizing the flow of leakage current for each transistor during its non-selected period.
Claim 23
Dependent Claim
36 words
The active driving system of claim 18, wherein the leakage current minimizing means includes gate bias means for biasing the voltage of the gate signal of each transistor during the non-selected period of the associated cell.
Claim 24
Dependent Claim
16 words
The active driving system of claim 19, wherein the display is a liquid crystal matrix panel.
Claim 25
Dependent Claim
56 words
The active driving system of claim 19, wherein the voltage of the gate signal of each transistor is biased during the non-selected period of the associated cell to a value corresponding to the approximate minimum level of current which flows between the drain and source of the transistor during the non-selected period of the associated cell.
Claim 26
Dependent Claim
18 words
The active driving system of claim 21, wherein the value of the gate signal voltage is above ground.
Claim 27
Dependent Claim
56 words
The active driving system of claim 18, wherein the voltage of the gate signal of each transistor is biased during the non-selected period of the associated cell to a value corresponding to the approximate minimum level of current which flows between the drain and source of the transistor during the non-selected period of the associated cell.
Claim 28
Dependent Claim
18 words
The active driving system of claim 23, wherein the value of the gate signal voltage is above ground.
Claim 29
Dependent Claim
16 words
The active driving system of claim 18, wherein the display is a liquid crystal matrix panel.
Claim 30
Dependent Claim
15 words
The active driving system of claim 18, wherein the transistors are thin film switching transistors.
Claim 31
Dependent Claim
36 words
The active driving system of claim 18, further including means for providing a video signal and scaling means for amplifying the video signal and producing a data signal which is nonsymmetrical relative to a common level.
Claim 32
Dependent Claim
31 words
The active driving system of claim 27, wherein said scaling means includes means for producing the data signal with amplitudes of opposite polarities which are unequal relative to the common level.
Claim 33
Dependent Claim
15 words
The active driving system of claim 28, wherein the transistors are thin film switching transistors.
Claim 34
Dependent Claim
26 words
The active driving system of claim 29, wherein said scaling means includes means for biasing the data signal at different voltages relative to the common level.
Claim 35
Dependent Claim
26 words
The active driving system of claim 28, wherein said scaling means includes means for biasing the data signal at different voltages relative to the common level.
Claim 36
Dependent Claim
15 words
The active driving system of claim 31, wherein the transistors are thin film switching transistors.
Claim 37
Dependent Claim
37 words
The active driving system of claim 19, further including means for providing a video signal and scaling means for amplifying the video signal and producing a data signal signal which is nonsymmetrical relative to a common level.
Claim 38
Dependent Claim
31 words
The active driving system of claim 33, wherein said scaling means includes means for producing the data signal with amplitudes of opposite polarities which are unequal relative to the common level.
Claim 39
Dependent Claim
26 words
The active driving system of claim 34, wherein said scaling means includes means for biasing the data signal at different voltages relative to the common level.
Claim 40
Dependent Claim
15 words
The active driving system of claim 35, wherein the transistors are thin film switching transistors.
Claim 41
Dependent Claim
56 words
The active driving system of claim 36, wherein the voltage of the gate signal of each transistor is biased during the non-selected period of the associated cell to a value corresponding to the approximate minimum level of current which flows between the drain and source of the transistor during the non-selected period of the associated cell.
Claim 42
Dependent Claim
18 words
The active driving system of claim 37, wherein the value of the gate signal voltage is above ground.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-02-05 | 1993-08-07 | 1994-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-02-05 | 1997-08-07 | 1998-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-02-05 | 2001-08-07 | 2002-02-06 | $7700.00 | Window Closed / Lapsed |