Liquid crystal display device with dummy segment electrodes and dummy common electrodes
A liquid crystal display device has a liquid crystal panel comprised of a liquid crystal material disposed between segment and common electrodes defining pixels arranged in a matrix. A driver integrated circuit generates driving segment signals and driving common signals to drive preselected ones of the segment and common electrodes, respectively, to display an image on the liquid crystal panel. The driver integrated circuit also generates a segment signal waveform and a common signal waveform to drive one of the segment electrodes and one of the common electrodes, respectively, each placed in a normally ON state and not corresponding to the preselected ones of the segment and common electrodes, respectively, so that a frame is displayed at a portion of the liquid crystal panel not corresponding to the pixels.
1. A liquid crystal display device comprising: a first transparent plate having a plurality of segment electrodes for receiving driving segment signals and a dummy segment electrode; a second transparent plate having a plurality of common electrodes for receiving driving common signals and a dummy common electrode, the second transparent plate being spaced-apart from and opposite to the first transparent plate to define a gap therebetween; and a liquid crystal layer disposed in the gap between the first and second transparent electrodes; wherein the plurality of segment and common electrodes define a plurality of pixels arranged in a matrix for displaying an image, the dummy segment electrode is disposed outside of the segment electrodes defining the pixels for displaying an image, and the dummy common electrode is disposed outside of the common electrodes defining the pixels for displaying an image; wherein the dummy segment electrode receives a dummy segment signal waveform so that an effective voltage value between the dummy segment signal waveform and any waveform of the driving common signals exceeds a selection voltage applied across the liquid crystal layer, and the dummy common electrode receives a dummy common signal waveform so that an effective voltage value between the dummy common signal waveform and any waveform of the driving segment signals exceeds the selection voltage applied across the liquid crystal layer, whereby dots formed by the dummy segment electrode and the common electrodes and dots formed by the dummy common electrode and the segment electrodes are placed in a normally ON state.
2. A liquid crystal display device according to claim 1 ; wherein the dummy common signal waveform is asynchronous to a frame line marker signal, has an equal H·L time in one period, and does not coincide with a liquid-crystal AC-field generating signal.
3. A liquid crystal display device according to claim 2 ; wherein the dummy common signal waveform is obtained by dividing down the liquid-crystal AC-field generating signal for level shift to the same potential as that of a segment voltage.
4. A liquid crystal display device according to claim 2 ; wherein the dummy common signal waveform is a signal waveform obtained by dividing down the liquid-crystal AC-field generating signal to ½.
5. A liquid crystal display device according to claim 1 ; wherein the dummy segment signal waveform has the same period as a liquid-crystal AC-field generating signal and the same potential as the waveform applied to the dummy common electrode.