US5977942A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiplexed display element sequential color LCD panel
Assignee: Hanger Solutions LLC
•
Filing: 1996-12-20
•
Granted: 1999-11-02
•
Expires: 2016-12-20
Abstract
Abstract In a color sequential system using LCDs, the LCD must operate faster than the frame rate because red, green, and blue are done sequentially. Ferroelectric LCDs can do this, but they are not analog devices and so cannot provide analog display levels. Instead, a pulse width modulation (PWM) technique is used. In the system of the present invention, each pixel has three storage devices to hold RGB analog levels. A latch is used to load these values in parallel. Then an analog 3:1 multiplexer is used to select the proper storage device for the current sequential color. The multiplexer output goes to a comparator, which has a sawtooth waveform input at much faster than the frame rate. The comparator output changes with the sawtooth level, so that PWM control is provided for each pixel. As an alternative, standard analog LCD pixels can be sequentially switched between three color input storage devices.
Inventors
- 👤 Dale S. Walker
- 👤 Richard M. Knox
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 12:09
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3611; G09G3/3648; G09G3/3651; H; H04; H04N; H04N5/00; H04N5/66; H04N9/00; H04N9/12; H04N9/30; G09G2300/00; G09G2300/08; G09G2300/0809; G09G2300/0814; G09G2300/0842; G09G2300/0852; G09G2310/00; G09G2310/02; G09G2310/0235; G09G2310/0243; G09G2310/0259; G09G2310/06; G09G2310/066; G09G2320/00; G09G2320/02; G09G2320/0271; G09G2320/0276; G09G3/2007; G09G3/2014; H04N5/74; H04N5/7416; H04N5/7441; H04N2005/745
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
179 words
A display apparatus comprising: a plurality of ferroelectric liquid crystal display pixels; a controller for each ferroelectric liquid crystal display (FLCD) pixel, each controller including: a first storage device for storing an analog voltage signal corresponding to a first color of light to be emitted from the pixel during a video frame; a second storage device for storing an analog voltage signal corresponding to a second color of light to be emitted from the pixel during a video frame; a third storage device for storing an analog voltage signal corresponding to a third color of light to be emitted from the pixel during a video frame; a comparator device for sequentially comparing the analog voltage signals to a voltage input signal, the comparator device having an output signal which is fed to the ferroelectric liquid crystal display pixel; a voltage input signal generator providing the voltage input signal; means for sequentially selecting the first, second, and third storage devices of each controller for the FLCD pixels; a light source; and a filter for sequentially selecting different colors of light.
Claim 2
Dependent Claim
179 words
A display apparatus comprising: a plurality of ferroelectric liquid crystal display pixels; a controller for each ferroelectric liquid crystal display (FLCD) pixel, each controller including: a first storage device for storing an analog voltage signal corresponding to a first color of light to be emitted from the pixel during a video frame; a second storage device for storing an analog voltage signal corresponding to a second color of light to be emitted from the pixel during a video frame; a third storage device for storing an analog voltage signal corresponding to a third color of light to be emitted from the pixel during a video frame; a comparator device for sequentially comparing the analog voltage signals to a voltage input signal, the comparator device having an output signal which is fed to the ferroelectric liquid crystal display pixel; a voltage input signal generator providing the voltage input signal; means for sequentially selecting the first, second, and third storage devices of each controller for the FLCD pixels; a light source; and a filter for sequentially selecting different colors of light.
Claim 3
Dependent Claim
17 words
The display apparatus of claim 1, further comprising: a video controller for providing the input video signal.
Claim 4
Dependent Claim
12 words
The display apparatus of claim 1, wherein said storage devices are capacitors.
Claim 5
Dependent Claim
29 words
The display apparatus of claim 1, wherein the means for sequentially selecting the first, second, and third storage devices of each controller for the FLCD pixels comprises a multiplexer.
Claim 6
Dependent Claim
19 words
The display apparatus of claim 1, wherein said filter is a rotating disk with red, green, and blue filters.
Claim 7
Dependent Claim
14 words
The display apparatus of claim 1, wherein said filter is a digitally switched filter.
Claim 8
Dependent Claim
12 words
The display apparatus of claim 1, said filter is a reflective filter.
Claim 9
Dependent Claim
20 words
The display apparatus of claim 1, wherein the plurality of pixels is located between the light source and the display.
Claim 10
Dependent Claim
16 words
The display apparatus of claim 1, wherein the voltage input signal comprises a falling sawtooth signal.
Claim 11
Dependent Claim
16 words
The display apparatus of claim 1, wherein the voltage input signal comprises a gamma-corrected sawtooth signal.
Claim 12
Dependent Claim
25 words
The display apparatus of claim 1, wherein the voltage input signal comprises a sawtooth signal having a different gamma-corrected waveform corresponding to each light color.
Claim 13
Dependent Claim
46 words
The display apparatus of claim 1 further comprising: three analog switches coupled to said storage devices and receiving red, green, and blue analog signals, wherein said switches pass said red, green, and blue analog signals responsive to a decoded row column address corresponding to the pixel.
Claim 14
Dependent Claim
43 words
The display apparatus of claim 1, wherein the ferroelectric liquid crystal display pixels are provided by a ferroelectric liquid crystal display with a reflective surface, wherein the controller for each pixel is located beneath the reflective surface as part of an integrated surface.
Claim 15
Dependent Claim
19 words
The display apparatus of claim 1, wherein the frequency of the voltage signal is at least about 600 Hz.
References Cited (Backward Citations)
US4874228A
Cited
US4799137A
Cited
US5054885A
Cited
US5486949A
Cited
US5122906A
Cited
US5122905A
Cited
US5612820A
Cited
US5083857A
Cited
US5148157A
Cited
US5404076A
Cited
US5682080A
Cited
US5670842A
Cited
US5606220A
Cited
US5471584A
Cited
US5225823A
Cited
US5190370A
Cited
US5233385A
Cited
US5686793A
Cited
US5504391A
Cited
US5467154A
Cited
US5692820A
Cited
US5523881A
Cited
US5404171A
Cited
US5313479A
Cited
US5416618A
Cited
US5453859A
Cited
US5508841A
Cited
US5381309A
Cited
US5573324A
Cited
US5642129A
Cited
US5467146A
Cited
US5555324A
Cited
US5626800A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-11-01 | 2003-05-03 | 2003-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-11-01 | 2007-05-03 | 2007-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-11-01 | 2011-05-03 | 2011-11-02 | $7700.00 | Window Closed / Lapsed |