| 摘要 |
A driving scheme for a variable iris diaphragm (1) based on an electrophoretic cell (3) is disclosed. In one embodiment there is a three-electrode (7,8,9) configuration in the cell. Two electrodes (7,8) are arranged on a first transparent substrate (4) and are shaped to correspond to the open and closed positions of: the diaphragm. The third electrode (9) is a control electrode, which facilitates the initiation of particle (2) motion towards the inside of the cell. As a result friction effects are reduced and a shorter response time is achieved. The control electrode (9) can be located either on the opposing substrate (5) or at the cell wall (6); alternatively, it may form the cell wall. The electrodes may be transparent but the outermost electrodes may be opaque. In another embodiment dielectric layers (15,16) located between the electrodes and the liquid medium in which the particles (2) are located obviates the effects of corrosion or erosion at the electrodes. The diaphragm has a pulse driver for applying voltage pulses to the electrodes (7,8,9). |
