Classifications

• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
  • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
  • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2310/00—Command of the display device
  • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
  • G09G2310/0264—Details of driving circuits
  • G09G2310/0267—Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2310/00—Command of the display device
  • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
  • G09G2310/0264—Details of driving circuits
  • G09G2310/0275—Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current

Definitions

• the present invention concerns a method in accordance with the preamble of claim 1.
• the invention also concerns a wiring system to be used for the implementation of this method.
• An AC electroluminescent display based on the thin film technique comprises a bi-dimensional matrix, in respect of the drive circuits, consisting of X and Y electrodes, in which matrix the X electrodes form lines and the Y electrodes, on the other hand, form columns.
• the necessary modulation voltage is lower than half the entire drive voltage, - after the refresh pulse, the luminance is lowered at a time constant typically of approximately 1 ms, and
• the capacitance of the display is high, typically about 50 to 200 pF/mm 2 .
• each line in its turn receives a high amplitude line selection pulse while the other lines are floating.
• a modulation voltage corresponding to the desired luminance is applied to the columns.
• a refresh pulse of reversed polarity is applied simultaneously to all lines.
• the method described in the reference publication (2) corresponds to the former method regarding its withstand voltage requirements.
• the methods differ from each other in the respect that, in the former method, high-voltage pulses are applied to the ground point of the line drive circuits, and the ground point of the column drive circuits is connected to the ground point of the entire drive system.
• the ground point of the line drive circuits is connected to the system ground, and the high-voltage pulses are applied to the ground point of the column drive circuits.
• the object of the present invention is to eliminate the drawbacks occurring in the systems of prior art.
• a further object of the invention to provide a refresh method for driving particularly an AC electroluminescent display based on the thin film technique, which refresh method lowers the requirements of withstandvoitage to be imposed on the drive circuits of the display, reduces the power consumption of the display, and permits a drive voltage completely free from a DC voltage component.
• a further object is to provide a wiring system for the implementation of the method.
• the invention is based, e.g., on the following ideas:
• the capacitances of the whole display are charged at a maximum basic voltage, however, so that the line selection pulses or column modulation pulses alone are not sufficient to ignite any display element.
• the line selection and column modulation voltages are superimposed on the basic voltage so that no change occurs in the voltage of the non-selected display elements.
• the absolute value of the semi-selected display elements is increased at the maximum by the line selection or column modulation voltage, and the absolute value of the voltage of the selected display ele ments is increased by the sum of the line selection voltage and column modulation voltage.
• the polarity of the basic voltage is preferably not reversed until after all the lines have, in their turn, received the line selection pulse.
• the apparatus includes two sources of DC voltage, one of them being the drive voltage source of the line drive circuits and the other one the drive voltage source of the column drive circuits. Moreover, the apparatus includes an AC voltage source, which is connected in series with one of the DC voltage sources. More specifically, the method in accordance with the invention is characterized by what is stated in the characterizing part of claim 1.
• the withstand voltage required both from the line drive circuits and from the column drive circuits is only equal to the maximum values of the modulation voltages, about 30 V.
• the prior art refresh methods have required a withstand voltage of about 60 V from the column drive circuits and a withstand voltage of about 200 V from the line drive circuits.
• a lower withstand voltage requirement facilitates the integration and results in less expensive and more reliable circuits.
• Both of the drive circuits may be of the same type, which reduces the number of circuit types to be integrated.
• the drive voltage of the display does notcontain a DC voltage component, which increases the service life of the display.
• the power consumption of the display is low, because the amplitude of the line selection pulses and of the column modulation pulses is low and because the frequency of the basic voltage may be low, even lower than 25 Hz.
• Figure 1 shows one wiring system in accordance with the invention as applied to a 2 x 2 matrix display.
• Figure 2 is a graphical presentation as a function of time of the various drive pulses related to the wiring system shown in Fig. 1.
• the display matrix comprises the lines X1 and X2 as well as the columns Y1 and Y2.
• the dis play elements C11 , C12, C21 and C22 are located.
• the voltages measured at the elements from the X electrodes to the Y electrodes are denoted with U C11 , U C12 , U C21 and U C22 , respectively.
• the ground point SE of the column drive circuits SA is preferably connected to the ground point JE of the entire drive system.
• the ground point RE of the line drive circuits RA is connected to the AC voltage U B generated by the AC voltage source B.
• the selected line X2 receives the voltage U B + U RM
• the non-selected line X1 receives the voltage U B
• the selected column Y2 is connected to the ground point SE and the non-selected column Y1 to the voltage U SM .
• the positive amplitude of the basic voltage (U BIAS ) is formed by subtracting the maximum value U SM of the column modulation voltages from the positive peak value ⁇ B of the AC voltage.
• U B is negative, the selected line X2 is connected to the voltage - ⁇ B and the nonselected line to the voltage - ⁇ B + U RM .
• C12, C21 and C22 are AC voltages, the peak values being ⁇ B in the cases of semi-selected display elements C11,
• the line selection voltage U RM and the maximum value U SM of the column modulation voltages are equally high in the example of Figures 1 and 2. They may also be different. Symmetry of the drive voltage can then be maintained by selecting the positive and the negative amplitude of the AC voltage U B to differ as to their magnitudes by the difference between the line selection voltage U RM and the maximum value
• the non-selected lines are always connected either to the positive pole or to the negative pole of the line selection voltage source RM depending on the phase of the AC voltage U B . If the line selection voltage U RM is selected at least twice as high as the maximum value U SM of the column modulation voltages, the non-selected lines may be allowed to float while the selected line receives the selection pulse. This reduces the power consumption.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)
• Control Of El Displays (AREA)
• Electroluminescent Light Sources (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8515126

Family Applications (1)

Country Status (6)

Cited By (5)

Families Citing this family (1)

Citations (2)

Family Cites Families (3)

• 1982
  • 1982-02-17 FI FI820522A patent/FI64248C/fi not_active IP Right Cessation
• 1983
  • 1983-02-17 JP JP58500762A patent/JPS59500289A/ja active Granted
  • 1983-02-17 DE DE19833332440 patent/DE3332440T1/de not_active Ceased
  • 1983-02-17 GB GB08327190A patent/GB2127199B/en not_active Expired
  • 1983-02-17 WO PCT/FI1983/000012 patent/WO1983003021A1/en active IP Right Grant
  • 1983-02-17 EP EP19830900715 patent/EP0101702B1/en not_active Expired

Patent Citations (2)

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