US5459645A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Wide angle light coupler for image illumination
Assignee: Delco Electronics LLC
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Filing: 1994-01-10
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Granted: 1995-10-17
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Expires: 2014-01-10
Abstract
Abstract Back lighting for an transmissive display panel such as a transparency or a liquid crystal display for direct viewing or image projection is afforded by a light source spaced from the display panel and an intervening light coupler comprising a tapered duct with reflective inner walls such as a frustoconical mirror. The small end of the duct is adjacent the light source and may include a diffuser film to enhance light uniformity at the display. Light reflection from the reflective walls provides off-axis viewability with substantially uniform brightness. The light coupler is useful in a vehicular head up display.
Inventors
- 👤 Walter J. Sattler
- 👤 Neale R. Clark
- 👤 LeRoy E. Medendorp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:42
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/01; G02B27/0101; G01; G01D; G01D11/00; G01D11/28; G02B6/00; G02B6/0001; G02B6/0096; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/1336; G02F1/133602; G02F1/133605; G02B2027/0118
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
120 words
An image illumination apparatus for back lighting an display panel comprising: a light source spaced from the display panel and having an area smaller than the panel; an elongate tapered duct having a specular reflecting inner surface for coupling light from the light source to the display panel, the duct having a first opening at one end adjacent the light source and a second opening at the opposite end adjacent the panel, the second opening being larger than the first, and a first light diffusing element over the first opening and a second light diffusing element over the second opening of the elongated tapered duct for enhancing illumination uniformity, whereby the display panel is illuminated for direct and off-axis viewing.
Claim 2
Dependent Claim
120 words
An image illumination apparatus for back lighting an display panel comprising: a light source spaced from the display panel and having an area smaller than the panel; an elongate tapered duct having a specular reflecting inner surface for coupling light from the light source to the display panel, the duct having a first opening at one end adjacent the light source and a second opening at the opposite end adjacent the panel, the second opening being larger than the first, and a first light diffusing element over the first opening and a second light diffusing element over the second opening of the elongated tapered duct for enhancing illumination uniformity, whereby the display panel is illuminated for direct and off-axis viewing.
Claim 3
Dependent Claim
52 words
The invention as defined in claim 1 wherein the reflecting inner surface has an angle relative to the longitudinal axis of the duct sufficient to achieve a substantially uniform illumination for an off-axis view of the image panel with a maximum of two reflections of any light ray from the reflecting surface.
Claim 4
Dependent Claim
12 words
The invention as defined in claim 1 wherein the duct is frustoconical.
Claim 5
Dependent Claim
26 words
The invention as defined in claim 1 wherein the second opening is substantially rectangular and the tapered duct is shaped to conform to the second opening.
Claim 6
Dependent Claim
27 words
The invention as defined in claim 1 wherein the duct is frustoconical and has a cone angle on the order of 7 degrees from its longitudinal axis.
Claim 7
Dependent Claim
27 words
The invention as defined in claim 1 wherein the area of the second opening is on the order of four times the area of the first opening.
Claim 8
Dependent Claim
150 words
In a head up display for a vehicle wherein an image generated by a transmissive liquid crystal display (LCD) is projected via a plurality of reflective elements to the field of view of a vehicle operator, a back lighting arrangement comprising: a light source smaller than the LCD and spaced therefrom; an elongate tapered duct with a reflective internal surface between the light source and the LCD, the duct having a first opening at one end coupled to the light source and a second opening at the opposite end coupled to the LCD, and a first light diffusing element over the first opening and a second light diffusing element over the second opening of the elongated tapered duct for enhancing illumination uniformity, whereby light from the source substantially uniformly illuminates the LCD by direct passage through the duct and by reflection from the internal surface for on-axis and off-axis projection.
Claim 9
Dependent Claim
150 words
In a head up display for a vehicle wherein an image generated by a transmissive liquid crystal display (LCD) is projected via a plurality of reflective elements to the field of view of a vehicle operator, a back lighting arrangement comprising: a light source smaller than the LCD and spaced therefrom; an elongate tapered duct with a reflective internal surface between the light source and the LCD, the duct having a first opening at one end coupled to the light source and a second opening at the opposite end coupled to the LCD, and a first light diffusing element over the first opening and a second light diffusing element over the second opening of the elongated tapered duct for enhancing illumination uniformity, whereby light from the source substantially uniformly illuminates the LCD by direct passage through the duct and by reflection from the internal surface for on-axis and off-axis projection.
Claim 10
Dependent Claim
15 words
The invention as defined in claim 7 wherein the tapered duct comprises a frustoconical mirror.
Claim 11
Dependent Claim
25 words
The invention as defined in claim 8 wherein the conical mirror has an angle relative to the longitudinal axis of the order of 7 degrees.
Claim 12
Dependent Claim
29 words
The invention as defined in claim 7 wherein the internal surface is tapered sufficiently to establish substantially uniform illumination of the LCD for viewing up to 15 degrees off-axis.
Claim 13
Dependent Claim
23 words
The invention as defined in claim 7 wherein light rays experience a maximum of two reflections between the light source and the LCD.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-10-16 | 1999-04-17 | 1999-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-10-16 | 2003-04-17 | 2003-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-10-16 | 2007-04-17 | 2007-10-17 | $7700.00 | Window Closed / Lapsed |