US6069676A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sequential color display device
Assignee: Citizen Electronics Co Ltd
•
Filing: 1997-04-08
•
Granted: 2000-05-30
•
Expires: 2017-04-08
Abstract
Abstract Red, green and blue light sources, and a shutter are provided. Photosensors are provided for detecting the luminance of each of the light sources. A controller is provided for sequentially operating each of the light sources, the shutter, and the photosensor in synchronism with each other at regular intervals. A luminance control circuit is provided for comparing a luminance detected by the photosensor with a reference value and for controlling the luminance of each of the light sources based on the comparison so as to keep a color balance of the light emitted from the color display device.
Inventors
- 👤 Harumi Yuyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 09:53
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/3406; G09G3/3413; G09G2310/00; G09G2310/02; G09G2310/0235; G09G2320/00; G09G2320/06; G09G2320/0666; G09G2360/00; G09G2360/14; G09G2360/145
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
106 words
A sequential color display device comprising: a plurality of light sources, each emitting different color light from other light sources; a shutter for sequentially passing color light beams from the light sources; at least one photosensor for detecting luminance of each of the light sources; a controller for sequentially operating each of the light sources, the shutter, and the photosensor in synchronism with each other at regular intervals; and luminance control means responsive to a luminance detected by the photosensor for controlling the luminance of each of the light sources so as to keep a color balance of the light emitted from the color display device.
Claim 2
Dependent Claim
106 words
A sequential color display device comprising: a plurality of light sources, each emitting different color light from other light sources; a shutter for sequentially passing color light beams from the light sources; at least one photosensor for detecting luminance of each of the light sources; a controller for sequentially operating each of the light sources, the shutter, and the photosensor in synchronism with each other at regular intervals; and luminance control means responsive to a luminance detected by the photosensor for controlling the luminance of each of the light sources so as to keep a color balance of the light emitted from the color display device.
Claim 3
Dependent Claim
15 words
The display device according to claim 1 wherein the color balance is the white balance.
Claim 4
Dependent Claim
15 words
The display device according to claim 1 wherein the light sources are light emitting diodes.
Claim 5
Dependent Claim
15 words
The display device according to claim 1 wherein the shutter is a liquid crystal shutter.
Claim 6
Dependent Claim
13 words
The display device according to claim 1 wherein the photosensor is a photodiode.
Claim 7
Dependent Claim
29 words
The display device according to claim 1 wherein the controller is provided for sequentially producing operating signals for applying the output of the photosensor to the luminance control means.
Claim 8
Dependent Claim
38 words
The display device according to claim 1 wherein the luminance control means comprises a subtracter for comparing an input signal dependent on the detected luminance with a reference value and producing an output signal based on the comparison.
Claim 9
Dependent Claim
41 words
The display device according to claim 7 wherein the luminance control means has a driving circuit responsive to the output signal of the subtracter for controlling a current passing each of the light sources so as to keep the color balance.
Claim 10
Dependent Claim
49 words
The display device according to claim 7 wherein the luminance control means has an integrating circuit for integrating an input signal dependent on the output of the photosensor, and a Zener diode for applying the output of the integrating circuit to the subtracter when exceeding the breakdown voltage thereof.
Claim 11
Dependent Claim
29 words
The display device according to claim 7 wherein the reference value is set to such a value that each of the light sources produces light of a maximum luminance.
Claim 12
Dependent Claim
22 words
The display device according to claim 7 wherein the reference value is a reference voltage set by a reference value setting circuit.
Claim 13
Dependent Claim
25 words
The display device according to claim 7 wherein the reference value is a reference voltage dependent on a luminance of one of the light sources.
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) | 2003-05-30 | 2003-11-29 | 2004-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-05-30 | 2007-11-29 | 2008-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-05-30 | 2011-11-29 | 2012-05-30 | $7700.00 | Window Closed / Lapsed |