US4845489A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electroluminescent display drive circuitry
Assignee: Chrysler Motors Corp
•
Filing: 1985-12-23
•
Granted: 1989-07-04
•
Expires: 2005-12-23
Abstract
Abstract An electroluminescent display drive circuit which compensates for the decrease in capacitance of the electroluminescent display panel that is experienced as the panel ages; this is accomplished by use of an RC time constant which will effectively increase the voltage presented across the electroluminescent display panel as the capacitive element of the RC time constant decreases with the age of the panel. Also presented is high frequency power supply to excite electroluminescent displays without a transformer such that the voltage across the display is in phase with the current through the display thereby reducing the effect of power factor and electromagnetic interference.
Inventors
- 👤 Ronald F. Hormel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:21
CPC Classifications
H; H05; H05B; H05B44/00; Y; Y02; Y02B; Y02B20/00; Y02B20/30
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
107 words
An non-inductive electroluminescent display drive circuit comprising: a high voltage low power source; an electroluminescent display panel; two low power signal transistors; a source of two input signals presented to the base of each signal transistor where the input signals to one transistor is 180 degrees out of phase with the input signals to the second transistor; the electroluminescent display panel being connected between the collectors of each transistor; and the electroluminescent display panel further being connected to the high voltage source through two resistors such that the voltage generated across the electroluminescent display panel is in phase with the current passing through the electroluminescent display panel.
Claim 2
Dependent Claim
107 words
An non-inductive electroluminescent display drive circuit comprising: a high voltage low power source; an electroluminescent display panel; two low power signal transistors; a source of two input signals presented to the base of each signal transistor where the input signals to one transistor is 180 degrees out of phase with the input signals to the second transistor; the electroluminescent display panel being connected between the collectors of each transistor; and the electroluminescent display panel further being connected to the high voltage source through two resistors such that the voltage generated across the electroluminescent display panel is in phase with the current passing through the electroluminescent display panel.
Claim 3
Dependent Claim
19 words
The electroluminescent display drive circuit of claim 1 where the emitters of each signal transistor are connected to ground.
References Cited (Backward Citations)
US2937298A
Cited
US3107314A
Cited
US3343128A
Cited
US3566014A
Cited
US3611177A
Cited
US3629653A
Cited
US3975661A
Cited
US4210848A
Cited
JPS5440586A
Cited
US4247854A
Cited
US4323895A
Cited
US4319164A
Cited
US4320169A
Cited
US4388554A
Cited
US4527096A
Cited
US4633141A
Cited
JPH05258388A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-07-03 | 1993-01-02 | 1993-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-03 | 1997-01-02 | 1997-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-03 | 2001-01-02 | 2001-07-04 | $7700.00 | Window Closed / Lapsed |