US5818553A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Contrast control for a backlit LCD
Assignee: Norand Corp
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Filing: 1997-10-06
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Granted: 1998-10-06
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Expires: 2017-10-06
Abstract
Abstract A contrast controller for a liquid-crystal display maximizes the display contrast by using a light sensor to detect ambient light levels and light blocked by the LCD panel. The display contrast is maximized by maximizing the difference between the ambient and blocked light levels. Further contrast maximization is accomplished through variable control of the LCD backlight in accordance with sensed light levels.
Inventors
- 👤 Steven E. Koenck
- 👤 II William Henry Keehn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:53
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/13306; G02F1/13318; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/3406; G09G3/36; G09G2320/00; G09G2320/06; G09G2320/0626; G09G2320/066; G09G2360/00; G09G2360/14; G09G2360/144
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
114 words
A contrast controller for a liquid-crystal display, comprising: (a) at least one light sensor for detecting varying levels of light impinging thereupon and producing a varying electrical output related to the varying levels of light; (b) a sensor pixel positioned between the impinging light and said at least one light sensor for controlling the light impinged upon said at least one light sensor proportional to the amount of light transmitted through the liquid-crystal display, wherein the impinging light includes light from a backlighting device of the liquid-crystal display; and (c) contrast maximizing means responsive to the varying electrical output of said at least one light sensor for maximizing the contrast of the liquid-crystal display.
Claim 2
Dependent Claim
114 words
A contrast controller for a liquid-crystal display, comprising: (a) at least one light sensor for detecting varying levels of light impinging thereupon and producing a varying electrical output related to the varying levels of light; (b) a sensor pixel positioned between the impinging light and said at least one light sensor for controlling the light impinged upon said at least one light sensor proportional to the amount of light transmitted through the liquid-crystal display, wherein the impinging light includes light from a backlighting device of the liquid-crystal display; and (c) contrast maximizing means responsive to the varying electrical output of said at least one light sensor for maximizing the contrast of the liquid-crystal display.
Claim 3
Dependent Claim
17 words
The contrast controller of claim 1 wherein said sensor pixel is a pixel of said liquid-crystal display.
Claim 4
Dependent Claim
21 words
The contrast controller of claim 1 wherein said sensor pixel is electrically driven by the drive circuitry of the liquid-crystal display.
Claim 5
Dependent Claim
26 words
The contrast controller of claim 1 wherein said sensor pixel is electrically driven at a rate equivalent to the average drive rate of the liquid-crystal display.
Claim 6
Independent Claim
69 words
A method for controlling the contrast of a liquid-crystal display comprising: (a) detecting the level of light incident upon the liquid-crystal display including light produced by a backlighting device of the liquid-crystal display; (b) detecting the level of light transmitted through the liquid-crystal display; and (c) adjusting the contrast of the liquid-crystal display until a maximum difference between the incident light level and the transmitted light level is reached.
Claim 7
Independent Claim
69 words
A method for controlling the contrast of a liquid-crystal display comprising: (a) detecting the level of light incident upon the liquid-crystal display including light produced by a backlighting device of the liquid-crystal display; (b) detecting the level of light transmitted through the liquid-crystal display; and (c) adjusting the contrast of the liquid-crystal display until a maximum difference between the incident light level and the transmitted light level is reached.
Claim 8
Dependent Claim
35 words
The method according to claim 5 further including the step of adjusting the backlighting level of the liquid-crystal display until a maximum difference between the incident light level and the transmitted light level is reached.
Claim 9
Independent Claim
120 words
An apparatus for controlling the contrast of a liquid-crystal display, comprising: a driver circuit for electrically driving the liquid-crystal display; a sensor pixel being electrically connected to said driver circuit; a first light sensor being disposed relative to the liquid-crystal display to detect ambient light directly impinging thereupon including light produced by a backlighting device of the liquid-crystal display, said first light sensor providing an output proportional to the ambient light; and a second light sensor being disposed relative to said sensor pixel to detect light transmitted therethrough, said second light sensor providing an output proportional light transmitted through said sensor pixel wherein said driver circuit adjusts the contrast according the outputs from said first and said second light sensors.
Claim 10
Independent Claim
120 words
An apparatus for controlling the contrast of a liquid-crystal display, comprising: a driver circuit for electrically driving the liquid-crystal display; a sensor pixel being electrically connected to said driver circuit; a first light sensor being disposed relative to the liquid-crystal display to detect ambient light directly impinging thereupon including light produced by a backlighting device of the liquid-crystal display, said first light sensor providing an output proportional to the ambient light; and a second light sensor being disposed relative to said sensor pixel to detect light transmitted therethrough, said second light sensor providing an output proportional light transmitted through said sensor pixel wherein said driver circuit adjusts the contrast according the outputs from said first and said second light sensors.
Claim 11
Dependent Claim
18 words
An apparatus as claimed in claim 1, wherein said sensor pixel is a pixel of the liquid-crystal display.
Claim 12
Dependent Claim
17 words
An apparatus as claimed in claim 1, wherein said sensor pixel is driven by said driver circuit.
Claim 13
Dependent Claim
26 words
An apparatus as claimed in claim 7, wherein said sensor pixel is driven at a rate equivalent to the average drive rate of the liquid-crystal display.
Claim 14
Dependent Claim
31 words
An apparatus as claimed in claim 7, wherein the contrast of the liquid-crystal display is controlled by maximizing the difference between the outputs of said first and said second light sensors.
Claim 15
Dependent Claim
33 words
An apparatus as claimed in claim 7, wherein the contrast of the liquid-crystal display is maximized as a function of the difference of the outputs of said first and said second light sensors.
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) | 2001-10-05 | 2002-04-06 | 2002-10-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-10-05 | 2006-04-06 | 2006-10-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-10-05 | 2010-04-06 | 2010-10-06 | $7700.00 | Window Closed / Lapsed |