A passive electro-optical display cell comprising, on the internal face of each of its plates, at least one of which is transparent, sets of control electrodes and sets of screen electrodes, the control electrodes and the screen electrodes being separated by an insulating layer. The screen electrodes and the insulating layers have apertures therein facing the control electrodes. In order to reduce the number of conducting tracks, the cell is controlled by multiplexing. This type of control is made possible by virtue of the particular combination of the control electrodes and the screen electrodes. The control and screen electrodes of either plate will select two segments for display, but a selection between the two segments is made possible because they face different screen electrodes of the other plate. Such a cell makes it possible to display more data than a normal cell and may be used in an electronic watch which has a large number of functions.
A liquid crystal display panel (10) in a watchcase (41) displays time information and/or calendar information. In the liquid crystal display panel (10), a liquid crystal layer (3) is disposed between an upper substrate (1) and a lower substrate (2). On the upper substrate (1) are formed segment electrodes (5g) and an auxiliary electrode (11) that surrounds the segment electrodes with gaps (G1), and the segment and auxiliary electrodes are composed of the same transparent conductive film. An opposite electrode (6) is formed over the entire display area of the lower substrate (2). The overlaps between the opposite electrode (6) and the segment electrodes (5g) form pixel areas (32), while the overlap between the opposite electrode (6) and the auxiliary electrode (11) forms a background area (33). Voltage is selectively applied to the liquid crystal layer (3) in the pixel areas (32) and the background area (33) respectively to change the state of the transmission, scattering or absorption of the light incident on the liquid crystal layer (3) as desired, so that time information and calendar information are displayed.
A liquid crystal device can be controlled by applying a positive (or negative) voltage to certain pixels and by removing the applied voltage through a main electrode arrangement in the form of a matrix. The liquid crystal layer embodying the liquid crystal device is entirely subjected, during operation, to a reverse electric field by a reverse voltage applied to an adjunct electrode arrangement. With this structure, each pixel defined in the liquid crystal layer is always subjected to an electric field so that a highly stabilized operation can be realized.
A four terminal liquid crystal display device includes orthogonally related row and column electrodes separated by a dielectric and disposed in respective sets above and below the liquid crystal medium. The electrodes in proximity to the LC medium are the column electrodes which have a small alternating square wave bias voltage.+-.Vo imposed therebetween so that a voltage of 2Vo magnitude is normally impressed across the LC medium. When an impulse voltage of magnitude 4Vo is impressed across the exterior row electrodes (+2Vo and -2Vo respectively), since the column electrodes are foraminated or have microapertures therethrough, the electric field established between the row and column electrodes in opposite sets, 3Vo, extends through the microapertures into the LC medium to establish a fringe electric field normal to the surfaces of the column electrodes tending to retain the LC directors in the vertical position. This arrangement avoids the imposition of large voltages directly across the LC media and permits the application of low voltages to the electrodes and thereby increases the life of only the column LC media which are otherwise degraded by high voltages.
A display device and operational method wherein driving and controlling electronic circuits are provided along with a liquid crystal layer as part of a unitary structure. An array of independent pixel reflective electrodes are provided behind the liquid crystal layer and are individually driven by the electronic circuits provided as part of the device. A light and electrostatic shield is provided between the electrode array and the integrated electronic circuit. The shield can also be utilized as a third electrode to bias the liquid crystal for faster response when voltages are applied to the individual electrodes.
