Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Patent
1994-01-03
1996-11-19
Powell, Mark R.
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
345 96, 345208, G09G 336
Patent
active
055767290
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 PCT/JP 93/00639 filed May 14, 1993.
FIELD OF THE INVENTION
The present invention relates to liquid crystal display devices and electronic equipment using the same for displaying characters, figures and the like on a liquid crystal display panel by means of passive-matrix addressing.
BACKGROUND OF THE INVENTION
The driving method known as amplitude selective addressing has been conventionally used to drive passive-matrix display devices. The 6-level driving method is most commonly used of the methods categorized as amplitude selective addressing. An example of the 6-level driving method is given in Japanese Patent Application Laid-open No. Hei2-89. The 6-level driving method will now be explained with reference to FIGS. 23 through 25C.
FIG. 23 shows the configuration and display components of a liquid crystal display panel. The figure shows a liquid crystal display panel 300 comprising a liquid crystal layer (not shown) and a pair of substrates 302 and 304, sandwiching the liquid crystal layer. Scanning electrodes Y1-Y6 are formed horizontally within substrate 302. The other substrate 304 contains signal electrodes X1-X6. Pixels are formed at intersections between scanning electrodes Y1-Y6 and signal electrodes X1-X6. In FIG. 23, on-status pixels are shown with hatching, and off-status pixels are shown without hatching.
The liquid crystal display panel 300 shown in FIG. 23 has only 6.times.6 pixels in order to simplify the explanation. The number of pixels in liquid crystal display panels in actual use will normally be far greater than this.
Either a selection voltage or non-selection voltage is applied in sequential order to each of the scanning electrodes Y1 to Y6. The period required to apply the selection voltage once to each of the scanning electrodes Y1-Y6 is called one frame.
At the same time as when either a selection voltage or non-selection voltage is applied to each of the scanning electrodes Y1-YG, either an on-voltage or off-voltage is applied to each of the signal electrodes X1-X6. That is, in order to turn on a pixel at an intersection between a scanning electrode and a signal electrode, an on-voltage is applied to the signal electrode when the scanning electrode is selected. In order not to turn on the pixel, an off-voltage is applied to the signal electrode when the scanning electrode is selected.
FIGS. 24A, 24B, 240, and FIGS. 25A, 25B, 25C show examples of driving voltage (applied voltage) waveforms.
FIGS. 24A, 24B, and 24C respectively show a signal voltage waveform applied to signal electrode X5, a scanning voltage waveform applied to scanning electrode Y3, and a voltage waveform applied to a pixel (on-status) at the intersection between signal electrode X5 and scanning electrode Y3.
Also, FIGS. 25A, 25B, and 25C respectively show a signal voltage waveform applied to signal electrode X5, a scanning voltage waveform applied to scanning electrode Y4, and a voltage waveform applied to a pixel (off-status) at the intersection between signal electrode X5 and scanning electrode Y4.
In FIGS. 24A, 24B, 24C, 25A, 25B, and 250, both F1 and F2 indicate one frame.
In the frame F1, frame F1, and frame F2.
Also, a 6-level driving method whereby the polarity is periodically switched in intervals other than those corresponding to frames F1 and F2 is disclosed in Japanese Patent Application Laid-open No. Sho62-31825.
An alternative to the 6-level driving method is the so called IHAT method. This method, proposed by T. N. Ruckmongathan, makes driving at low voltages possible and enables display uniformity to be achieved (1988 International Display Research Conference). In this driving method, N lines of line electrodes are bundled to p (p=N/M) groups of subgroups, each of which consists of M lines of line electrodes selected together. This method is disclosed in Japanese Patent Application Laid-open No. Hei5-46127.
Incidentally, driving a liquid crystal display panel by such methods as the aforementioned 6-level driving method and the IHAT method may require significant po
REFERENCES:
patent: 5117298 (1992-05-01), Hirai
patent: 5184118 (1993-02-01), Yamazaki
patent: 5270697 (1993-12-01), Takeda
Luu Matthew
Powell Mark R.
Seiko Epson Corporation
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