Liquid crystal display device

Abstract

In a case where a frame display is provided on a display screen of a liquid crystal panel, the prior art necessitates data for frame display to be directly written to all the display data or 2 screenful of data to be prepared and overwritten on each other. To overcome this problem, a liquid crystal display device of the invention has an arrangement wherein a segment electrode and a common electrode constituting a pixel to be driven for normal image display are applied with a driving waveform from a driver IC, and wherein a common electrode to be placed in a normally ON state is applied with a waveform exceeding a selection voltage of any segment signal waveform for liquid crystal selection while a segment electrode to be placed in a normally ON state is applied with a waveform exceeding a selection voltage of any common signal for liquid crystal selection. This permits a frame to be displayed on the display screen.

Description

BACKGROUND-OF THE INVENTION [0001] The present invention relates to a driving device for liquid crystal display panel of a passive drive system and to a liquid crystal display device and an electronic device employing the same. [0002] A passive-drive liquid crystal display panel widely used in electronic devices has a structure wherein a liquid crystal layer is sealed between a transparent plate formed with a plurality of line-shaped common electrodes and a transparent counter plate formed with a plurality of line-shaped segment electrodes. Individual intersections of the common electrodes and the segment electrodes define individual pixels which constitute a display screen. That is, the display screen of m×n pixels is essentially composed of m segment electrodes and n common electrodes. ON / OFF control of each pixel is accomplished by way of a signal (driving signal waveform) applied to the segment electrode and the common electrode. Such a liquid crystal display device has a proble...

AI Technical Summary

Benefits of technology

The invention is about a liquid crystal display device that has dummy electrodes around the display screen to show a frame outside the screen. The dummy electrodes are applied with a waveform that is synthesized with the driving waveform applied to the segment electrodes. This allows for a more effective waveform to be applied to the dummy electrodes. The waveform applied to the dummy common electrodes is asynchronous to the FLM signal and does not coincide with an M signal. This allows for a more complex waveform to be applied. The waveform applied to the dummy segment electrodes has the same period and potential as the M signal. This allows for easy and cost-effective control of the frame display without increasing the size of the driving circuit.

Problems solved by technology

Such a liquid crystal display device has a problem that an observer cannot instantaneously determine whether a pixel is OFF because it is located outside a display screen or because an OFF signal is inputted thereto.

Therefore, when a photo or game graphic with a black background is displayed on such a panel, the outermost portion of the display screen (display area) is unrecognizable.

On the other hand, the current cellular phones or portable information terminals are generally limited in the number of display pixels in order to expedite the display of information provided via network services or by add-on applications.

However, commonly used liquid crystal drivers and controllers are not equipped with such a capability so that liquid crystal panels adapted for the frame display based on this method are limited.

In addition, there is another problem that the IC having such a capability is more expensive than the common ICs.

This imposes restriction on the specification of the liquid crystal display device.

In addition, a significant cost must be borne in order to utilize the IC having such a capability.

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