Method and apparatus for reducing power consumption in an AC-exc

Details Method and apparatus for reducing power consumption in an AC-exc Method and apparatus for reducing power consumption in an AC-exc

1991-06-19

1994-05-24

Hjerpe, Richard

Computer graphics processing and selective visual display system

Plural physical display element control system

Display elements arranged in matrix

345212, G09G 330

Patent

active

053153111

ABSTRACT:
The present invention relates to a method and apparatus for driving an AC-excited thin-film electroluminescent display based on a display matrix of rows and columns, in which method each row of the display matrix is alternately driven by positive (Vwrp) and negative (Vwrn) row drive pulses in which the magnitudes of successive pulses are different, each column of the display matrix is driven individually by modulation voltage pulses synchronized to the row addressing sequence, said pulses having a maximum amplitude (Vm) and an "ON"-state polarity equal to that of the larger-magnitude row drive pulse. According to the invention in a limit-load situation the maximum amplitude of the modulation voltage (Vm) is allowed to drop, the amplitude of the smaller-magnitude row drive pulse (Vwrn) is feedback controlled from the modulation voltage (Vm) so that a drop in the maximum amplitude of the modulation voltage (Vm) is compensated by an increase of the magnitude of the smaller-amplitude row drive voltage (Vwrn), said increase being essentially equal to the drop in the modulation voltage (Vm), and the higher-amplitude row drive voltage (Vwrp) is maintained essentially constant. The circuit configuration according to the invention provides an essential reduction in the power consumption of the display.

REFERENCES:
patent: 4636789 (1987-01-01), Yamaguchi et al.
patent: 4733228 (1988-03-01), Flegal
patent: 4801920 (1989-01-01), Ohba et al.
patent: 5027040 (1991-06-01), Ikeda et al.
patent: 5093654 (1992-03-01), Swift et al.
Linear and Interface Circuit Applications, vol. 2, Display Drivers & Data Transmission Line Circuit, TI, 1986, pp. 9-75.
ICs for Industrial Electronics, Data Book 1989/1990, Siemens, pp. 243-260.
Linear Integrated Circuits Data Book, 1987, Unitrode, pp. 3-107 to 3-112.

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