Method and a system for driving a display panel of matrix type

A method of driving an electroluminescent display panel of a matrix type, the display panel having a plurality of scan electrodes, a plurality of data electrodes arranged relatively to the scan electrodes so as to form a matrix of spaced intersections between each of the plurality of data electrodes and each of the plurality of scan electrodes, and electrically luminous material at each intersection of the matrix of spaced intersections thereby to define a corresponding matrix of display cells, said method comprising the steps of:

• defining successive frame cycles, each successive frame cycle of a common duration;
• defining a pedestal pulse having a fixed pedestal voltage level, a duration less than the frame cycle duration and a fixed polarity in each frame cycle, successive pedestal voltages having respective, alternating polarities in corresponding, successive frame cycles;
• defining a succession of scan pulses, respectively corresponding to the plurality of scan electrodes, at respective, spaced time intervals synchronized with the pedestal pulse in each frame cycle, the succession of scan pulses in each frame cycle having a common scan pulse voltage level and a fixed polarity and the successions of scan pulses of the respective, successive frame cycles having alternating polarities;
• defining a succession of data pulse time intervals synchronized with the succession of scan pulse time intervals in each frame cycle, a data pulse voltage level which is constant and a data pulse polarity which is fixed in each frame cycle and data pulse polarities which alternate in successive frame cycles;
• driving the panel for lighting selected cells thereby to display data on the panel in accordance with, in each frame cycle, applying a pedestal pulse to all cells, selectively through the plurality of scan electrodes or through the plurality of data electrodes, applying corresponding scan pulses, in succession and during the respective scan pulse intervals, to the plurality of respectively corresponding scan electrodes for selecting same, in succession, and applying a data pulse to each data electrode corresponding to a cell defined by the intersection of the data electrode with the selected scan electrode and which is to be lit, thereby to produce, at each cell which is to be lit, a cell voltage comprising the sum of the pedestal voltage level, the scan pulse voltage level and the data pulse voltage level, the lighting of the cell producing a polarization charge at the cell and the number of cells which are commonly associated with a data electrode and which are lighted in a frame cycle producing a virtual pedestal pulse voltage level which is greater than the fixed pedestal pulse voltage level and which has a maximum virtual pedestal pulse voltage level determined in accordance with the maximum number of selected and lighted cells commonly associated with the data electrode in the frame cycle, the maximum value producing a corresponding maximum polarization charge;
• and
• applying a compensation pulse to all of the cells, in each frame cycle and in advance of at least the applying of the scan pulse for selecting a first one of the scan electrodes in that frame cycle, the applied compensation pulse having a polarity which is the same as the polarity of the pedestal pulse applied in that common frame cycle and having a voltage level and duration sufficient to generate a polarization charge in each cell which is at least substantially as great as the maximum polarization charge but which is insufficient to light any cell.

A system for driving an electroluminescent display panel of a matrix type having a write pulse voltage of a predetermined level with a first part and a second part and a plurality of scan electrodes intersecting a plurality of data electrodes orthogonally arranged to the scan electrodes, said system comprising:

• a cell, formed at an intersection of the scan electrodes and the data electrodes, producing an electrically luminous effect in response to receiving the write pulse voltage of the predetermined level;
• first switching elements in first push-pull configurations, operatively connected to corresponding ones of the data electrodes or the scan electrodes, receiving, controlling and providing the first part of the write pulse voltage to the corresponding ones of the data electrodes or the scan electrodes;
• power receiving terminals, operatively connected to the display panel, receiving the second part of the write pulse voltage;
• second switching elements arranged in second push-pull configurations, each of said second switching elements operatively connected to only one of said power-receiving terminals and each of said second push-pull configurations having an output terminal operatively connected to a corresponding one of the scan electrodes or the data electrodes, each of said second push-pull configurations receiving, controlling and providing the second part of the write pulse voltage to the corresponding one of the scan electrodes or the data electrodes;
• and
• first and second pulse generators each being operatively connected to a corresponding one of said power-receiving terminals and providing the second part of the write pulse voltage to said second switching elements, one of said first and second pulse generators operatively disconnecting from the corresponding one of said power-receiving terminals while another one of said first and second pulse generators provides the second part of the write pulse voltage to a cell to be lit via the corresponding connected power receiving terminal and the one of said power-receiving terminals corresponding to the disconnected one of said first and second pulse generators floating.

A method of driving a matrix type electroluminescent display system having a display panel of matrix type in which an electroluminescent cell is formed at each intersection of a plurality of scan electrodes intersecting a plurality of data electrodes orthogonally arranged thereto;

• a plurality of first switching elements connected to the data electrodes receiving, providing and controlling application of a data pulse voltage onto each of the data electrodes;
• a pedestal pulse generator, connected to the display panel, generating and providing a pedestal pulse voltage having a first voltage level, to the display panel;
• a scan pulse generator, connected to the display panel, generating and providing a scan pulse voltage level higher than the first voltage level of said pedestal pulse to the display panel and having a same polarity as the first voltage level of said pedestal pulse;
• a plurality of second switching elements arranged in a plurality of push-pull configurations, each of said second switching elements operatively connected to the display panel and one of two power-receiving terminals, a first one of the two power-receiving terminals operatively connected to said pedestal pulse generator, and a second one of the two power-receiving terminals operatively connected to said scan pulse generator said method comprising the steps of:
• applying said pedestal pulse voltage through each of said push-pull configurations to each of the scan electrodes from said pedestal pulse generator, and charging all of the cells up to the first voltage level of said pedestal pulse generator;
• holding the first power-receiving terminal in a floating state;
• applying said scan pulse voltage through a selected one of said second switching elements from the second power-receiving terminal to a corresponding one of the scan electrodes;
• applying said data pulse voltage through a selected one of said first switching elements to a corresponding one of the data electrodes synchronized with said step of applying said scan pulse voltage, and additionally charging a selected cell from the first voltage level of said pedestal pulse generator up to a second voltage level and producing an electrically luminous effect lighting the cell.

A method of driving an electroluminescent display panel in each of successive frame cycles, the panel having a matrix of plural luminescent cells arranged in rows and columns, each cell being disposed at the intersection of a row and a column, for selective lighting by establishing a write voltage across the cell in an initial frame cycle, comprising the steps of:

• applying a pedestal pulse having a polarity and a pedestal pulse voltage level, to all the cells during each frame cycle, the polarity of the pedestal pulse being constant during each frame cycle and alternating in successive frame cycles;
• applying a scan pulse to each row of cells for individually selecting each row thereof during each frame cycle, each scan pulse having a fixed voltage level and a constant polarity in each frame cycle and the polarity alternating in successive frame cycles in synchronization with the alternating polarity of the pedestal pulses so as to be in additive relationship therewith and produce a half-select pulse at each cell associated with the selected row of cells;
• applying a data pulse to each column of cells for selecting each column thereof in which an associated cell is to be selectively lighted, in the frame cycle and in synchronization with the selection of the row associated with each cell to be selectively lighted, each data pulse having a fixed data voltage level and a constant polarity in each frame cycle and being synchronized relatively to the polarity and voltage level of the pedestal pulse so as to be in additive relationship therewith and to form a half-select pulse at each cell associated with the selected column of cells;
• the additive relationship of a scan pulse, a data pulse and a pedestal pulse at each cell, disposed at the intersection of a selected row and a selected column, defining a write pulse of a voltage level sufficient to light the corresponding cell and the lighted cell producing a polarization charge at the cell, the number of cells in a column thereof which are simultaneously lighted producing a virtual pedestal pulse voltage level which is greater than the pedestal pulse voltage level of the pedestal pulse and which has a maximum value determined by the maximum number of selected and lighted cells of the column of cells in the frame cycle, the maximum value producing a corresponding maximum polarization charge;
• and
• applying a compensation pulse to all of the cells prior to the application thereto of the pedestal pulse, the compensation pulse having a polarity which is the same as the polarity of the pedestal pulse in each frame cycle and having a voltage level which produces a polarization charge which is at least substantially as great as the maximum polarization charge but which is insufficient to light any cell.

A method of driving an electroluminescent display panel having a plurality of scan electrodes, a plurality of data electrodes arranged orthogonally to and intersecting the scan electrodes and defining cells at the intersections, each cell thereby being associated with a respective scan electrode and a respective data electrode, and electrically luminous material at the cell-defining intersections, said method comprising the steps of:

• applying a pedestal pulse having a polarity and a predetermined pedestal voltage level, through the data electrodes or the scan electrodes to all of the cells, the polarity of the pedestal pulse being constant during predetermined periods and varying for each of a plurality of frame cycles;
• applying a scan pulse, having a polarity and a scan voltage level for selecting one of the scan electrodes, to a selected scan electrode, the scan pulse being superposed onto the pedestal pulse when the pedestal pulse is applied thereto, the polarity of the scan pulse varying for each of the frame cycles;
• applying a data pulse, having a data voltage level for selecting a cell on the selected scan electrode, to a corresponding data electrode in synchronization with selecting the selected scan electrode, the data pulse being superposed onto the pedestal pulse when the pedestal pulse is applied thereto;
• applying a write pulse voltage to a selected cell the write pulse voltage comprising a sum of the pedestal voltage level, the scan voltage level and the data voltage level, each of the voltages having a same polarity across the selected cell, the write pulse voltage being high enough to light the selected cell, and a polarity of the write pulse voltage varying for each of the frame cycles;
• and
• applying a compensation pulse, having a voltage level, to all of the cells prior to applying the scan pulse, and in each of the frame cycles the applied compensation pulse having a same polarity as the polarity of said applied pedestal pulse and varying with the applied pedestal pulse for a next predetermined period having a duration sufficient for the voltage level to induce a polarization charge of all of the cells to a saturated amount at least equal to a maximum polarization charge generated by applying a maximum of the pedestal voltage, the voltage level of the applied compensation pulse being higher than the predetermined first voltage level of the applied pedestal pulse and low enough not to light the cells, wherein the compensation pulse is generated by:
• while applying the pedestal pulse having a first pedestal voltage level of a first polarity to all of the scan electrodes, applying the data voltage level having a second polarity opposite to the first polarity of the pedestal pulse to all of the data electrodes, a sum of the first pedestal voltage level across the cells and the data pulse voltage level across the cell acting as the compensation pulse of the second polarity, and
• while applying the pedestal pulse having a second pedestal voltage level of the second polarity to all of the scan electrodes, further applying a substantially ground level in the next frame cycle to all of the data electrodes, the second pedestal voltage level applied across the cell acting as the compensation pulse of the first polarity.

A method of driving an electroluminescent display panel having a plurality of scan electrodes, a plurality of data electrodes arranged orthogonally to and intersecting the scan electrodes and defining cells at the intersections, each cell thereby being associated with a respective scan electrode and a respective data electrode, and electrically luminous material at the cell-defining intersections, the method comprising:

• applying a pedestal pulse having a pedestal pulse voltage level, selectively through the data electrodes or the scan electrodes, to all of the cells in each frame cycle, successive pedestal pulses applied in respective, successive frame cycles having respective, alternating polarities;
• in each frame cycle, applying a scan pulse having a scan voltage level to a corresponding scan electrode thereby to select the corresponding scan electrode, each scan pulse in each frame cycle having a polarity relative to the pedestal pulse of that frame cycle such that the scan voltage level and the pedestal voltage level are in voltage-additive relationship and produce a half-select voltage at the cells associated with the corresponding, selected scan electrode, scan pulses applied in successive frame cycles having respective, alternating polarities;
• in each frame cycle, applying a data pulse having a data voltage level to a corresponding data electrode thereby to select the corresponding data electrode, to each data electrode associated with a cell to be lighted during that frame cycle, the data pulse in each frame cycle having a polarity relative to the pedestal pulse of that frame cycle such that the data voltage level and the pedestal voltage level are in voltage-additive relationship and produce a half-select voltage at the cells associated with the corresponding, selected data electrode, data pulses applied in successive frame cycles having respective, alternating polarities;
• in each frame cycle and for each cell at the intersection of associated and selected scan and data electrodes, the sum of the data voltage level, the scan voltage level and the pedestal voltage level defining a write pulse voltage across the cell of a voltage level sufficient to light the cell and produce a polarization charge at the lighted cell resulting in producing a virtual pedestal pulse voltage level on the selected data electrode which is greater than the pedestal voltage level and which is determined by, and corresponds to, the number of lighted cells associated with the selected data electrode;
• and
• in advance of selecting a first scan electrode and in each frame cycle, applying, to all of the cells, a compensation pulse having a polarity which is the same as the respective pedestal pulse polarity and having a voltage level and a duration which generate, in each cell, a polarization charge which is substantially as great as the polarization charge produced by the virtual pedestal voltage level at the cell in the current frame cycle, and which are insufficient to light any cell.

A method of driving an electroluminescent display panel having a plurality of scan electrodes, a plurality of data electrodes arranged orthogonally to and intersecting the scan electrodes and defining cells at the intersections, each cell thereby being associated with a respective scan electrode and a respective data electrode, and electrically luminous material at the cell-defining intersections, the method comprising:

• applying a pedestal pulse to all of the cells in each frame cycle, successive pedestal pulses applied in respective, successive frame cycles having respective and alternating, opposite polarities;
• in each frame cycle, applying scan pulses of the respective polarity in individual succession to the plurality of scan electrodes for selecting the scan electrodes in individual succession;
• in each frame cycle, for each successively selected scan electrode and for the cells respectively associated therewith and selected for lighting, applying data pulses through the associated, and thereby selected, data electrodes to the associated and selected cells, the data, scan, and pedestal pulses having respective voltage levels in additive relationship at each selected cell and the sum thereof comprising a write pulse of a voltage level sufficient to light the cell and produce a polarization charge at the lighted cell, a virtual pedestal pulse voltage level being produced on each data electrode which is greater than the pedestal pulse voltage level and which is determined by, and corresponds to, the number of lighted cells associated with the selected data electrode;
• and
• in advance of applying scan pulses in each frame cycle, applying, to all of the cells, a compensation pulse of the respective polarity, the compensation pulse having a voltage level and duration which are sufficient to produce a polarization charge in each cell which is substantially as great as the polarization charge produced in a lighted cell and which are insufficient to light any cell.