Method and apparatus for operating an electrophoretic display between a display and a non-display mode
First Claim
1. A method of operating an electrophoretic display during a non-display mode to increase the life and resolution of said display, said display of the type having an anode electrode and a cathode electrode, comprising the steps of:
- applying an alternating voltage of a selected magnitude and frequency for a predetermined time between the anode and cathode electrodes during said non-display mode, said selected magnitude and frequency and said predetermined time being chosen to cause electrophoretic pigment particles in said electrophoretic display to be suspended between said cathode and anode and remain suspended between said cathode and anode during said non-display mode.
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Accused Products
Abstract
There is shown a method and apparatus for operating an electrophoretic display. The display is operated in a first mode where essentially it operates as a display having normal DC voltages applied to its electrodes. During a non-display mode, a suitable alternating voltage of a given frequency and magnitude is AC coupled to the anode electrode of the display for a predetermined time interval to cause pigment particles to settle between the anode and cathode whereby the effective life of said display is increased. The transfer of the display mode to the second mode is afforded by suitable switching circuitry.
242 Citations
15 Claims
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1. A method of operating an electrophoretic display during a non-display mode to increase the life and resolution of said display, said display of the type having an anode electrode and a cathode electrode, comprising the steps of:
applying an alternating voltage of a selected magnitude and frequency for a predetermined time between the anode and cathode electrodes during said non-display mode, said selected magnitude and frequency and said predetermined time being chosen to cause electrophoretic pigment particles in said electrophoretic display to be suspended between said cathode and anode and remain suspended between said cathode and anode during said non-display mode. - View Dependent Claims (2, 3, 4)
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5. Apparatus for operating an electrophoretic display, said display of the type having anode, cathode and grid electrodes for controlling the movement of pigment particles in a suspension to impinge upon said anode or cathode electrode in a display mode, said apparatus comprising:
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first selectable logic means coupled to said electrophoretic display electrodes for applying DC operating potentials thereto to enable said display to operate in a display mode, second means responsive to the termination of said display mode for applying to said display an alternating voltage waveform, said alternating voltage waveform having a magnitude, frequency and duration selected to cause said pigment particles in said electrophoretic display to go into suspension between said anode and cathode and remain in suspension therebetween until a display mode is initiated. - View Dependent Claims (6, 7, 8)
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9. Apparatus for operating an electrophoretic display in a first display mode and a second mode when said display mode is terminated to enable said display to operate at an increased life and resolution, said display of the type employing pigment particles and having a cathode, anode and grid electrode for propagating pigment particles therebetween, said apparatus comprising:
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timing means responsive to a first signal indicative of an end of display mode to commence a predetermined timing interal upon receipt of said first signal and including means for terminating said timing interval upon receipt of a second signal indicative of a display mode, first switching means responsive to said second signal to supply operating potential to said anode, cathode and grid electrodes during said display mode, and second switching means coupled to said timing means and operative to supply only an alternating voltage signal to said anode during said predetermined timing interval, said alternating voltage having a magnitude and frequency which in combination with said predetermined timing interval causes said pigment particles to migrate to a position where said pigment particles are suspended between said anode and cathode during said predetermined interval and are retained in suspension until operating potential is supplied to said anode, cathode and grid electrode during said display mode. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification