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
  • G09G3/32—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 semiconductive, e.g. using light-emitting diodes [LED]
  • G09G3/3208—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 semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
  • G09G3/3225—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 semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
  • G09G3/3233—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 semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element
• • 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
  • G09G3/32—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 semiconductive, e.g. using light-emitting diodes [LED]
  • G09G3/3208—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 semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
  • G09G3/3225—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 semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
  • G09G3/3258—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 semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the voltage across the light-emitting element
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2300/00—Aspects of the constitution of display devices
  • G09G2300/08—Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
  • G09G2300/0809—Several active elements per pixel in active matrix panels
  • G09G2300/0842—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor
• • 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
  • G09G2310/06—Details of flat display driving waveforms
  • G09G2310/066—Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2320/00—Control of display operating conditions
  • G09G2320/02—Improving the quality of display appearance
  • G09G2320/0261—Improving the quality of display appearance in the context of movement of objects on the screen or movement of the observer relative to the screen

Definitions

• the present invention relates to an electronic control cell for organic light emitting diode of active matrix display as well as operating methods. It has applications in the field of displays, in particular flat screens, of which elementary display units, pixels or segments, of the organic light-emitting diode type are controlled individually by control cells arranged in the form of one or more matrices.
• display in particular flat screens, of which elementary display units, pixels or segments, of the organic light-emitting diode type are controlled individually by control cells arranged in the form of one or more matrices.
• the development of industrial and consumer electronic and / or computer equipment requires the use of user interaction interfaces and in particular visual interfaces such as displays or segment or pixel screens, these four terms being considered two by two in an equivalent manner in the following.
• This control circuit is responsible for maintaining control and extinguishing the pixel OLED (s) by, at an appropriate time, an additional control signal, of the same type as that used for switching on or selecting the pixel and, in general, by a short pulse of ignition control in one case and extinction in the other.
• the major defect of such a current control results from the fact that it is generally carried out by a complex assembly of at least four transistors, called a "current mirror". This requires the passage of a strong current in all the transistors of the pixel as well as in the control circuits located upstream, and this, during the entire control cycle. In addition to the need for two control lines to control the current mirror, these high currents must flow in control lines arranged on the display with relatively high ohmic losses.
• the control of each of the pixels is multiplexed line x column and the display of a frame is done line by line (or column by column according to the chosen embodiment).
• the transition in light level from one frame to another can be abrupt. Such transitions can for example occur because a displayed object of a scene moves in the scene over time, Or such violent transitions are perceived by the eye and disturb the visual perception of the animated scene on the 'screen. This results in a “blurring” effect which can be quite unpleasant.
• the invention proposes to resolve these difficulties by proposing a pixel voltage control which also makes it possible to simplify the control circuit associated with each pixel or segment. It uses the memory effect of an additional or intrinsic capacitance discharging into an additional or intrinsic resistance of an electronic current switch of the pixel OLED (s).
• the implementation of a voltage control also makes it possible to limit the constraints on the size of the transistors and the electronic mobility (of the charge carriers). It is thus possible to produce such displays with thin film transistors, called TFTs, with low mobility or not and, for example in amorphous or microcrystalline or polycrystalline, or even organic silicon.
• the invention therefore relates to an electronic control cell for at least one organic light-emitting diode (OLED) of a pixel or segment of an active matrix display, the cell comprising at least: - a control circuit with a control input and functioning as an electronic switch in operation a control signal arriving on a control line at the control input and allowing the OLED (s) to be switched on or off as a function of said control signal,
• OLED organic light-emitting diode
• a selection circuit that functions as an electronic switch in accordance with a selection signal V ⁇ arriving on a select line and enabling the linking or electrical insulation of the capacitive storage circuit with / from a voltage command V com as a function of said selection signal.
• storage is temporary by discharging the capacity through a resistor Rf in parallel with the capacity.
• control signal is modulated in duration and / or in voltage level; (allows to vary the duration of lighting of the OLED (s) of the pixel according to the needs)
• V CO m the control voltage V CO m is modulated in voltage level
• V se ⁇ is modulated in duration
• the display is periodic in frames and the values of C and Rf are chosen so that under average operating conditions the duration of the memorization of an ignition state is less than the duration of a frame
• the storage duration is less than or equal to half the duration of a frame
• the capacitance C is essentially an added capacitor
• the capacitance C is essentially the capacitive part of the intrinsic input impedance of the control circuit
• the resistance Rf is essentially an added resistance
• the reported resistance Rf is produced from a transistor mounted in a resistive circuit
• the resistance Rf is essentially the resistive part of the intrinsic input impedance of the control circuit, - the resistance Rf is essentially a capacitance leakage resistance, (the capacitance is not perfect and has a leakage current and preferably according to a substantially ohmic law)
• the cell comprises a means reducing the rate of maximum rise and / or fall of the voltage across the terminals of the capacitance C when the latter is brought into contact with the control voltage V corr ⁇ ,
• control circuit is a field effect control transistor M 1
• control transistor M1 has a single gate
• control transistor M1 is double gate
• the selection circuit is a field effect selection transistor M2
• the selection transistor M2 has a single gate, the selection transistor M 2 has a double gate,
• control circuit is a P-type field effect control transistor M1 connected on the one hand directly to the positive pole V pp of the power supply and on the other hand through the OLED (s) to the ground of l power supply
• selection circuit is a P type field effect selection transistor M2 and the capacitance C and the resistance Rf in parallel return to the positive pole V pp ,
• control circuit is a control transistor M 1 with an N-type field effect connected on the one hand directly to the ground of the power supply and on the other hand through the OLED (s) to the positive pole V pp of the power supply
• selection circuit is a selection transistor M2 with N-type field effect and the capacitance C and the resistance Rf in parallel return to ground
• the transistors are thin film transistors, called TFTs
• the transistors are made of amorphous or microcrystalline or poly-crystalline silicon, or even organic.
• the invention also relates to a method for operating an electronic control cell for at least one organic light-emitting diode (OLED) of a pixel or segment of an active matrix display, the cell having at least: - a circuit for control with a control input and operating as an electronic switch as a function of a control signal arriving on a control line on the control input and allowing the OLED (s) to be lit or not as a function of said control signal, a capacitive storage circuit of the control signal with a capacitance C connected to the control line,
• OLED organic light-emitting diode
• a selection circuit that functions as an electronic switch in accordance with a selection signal V ⁇ arriving on a select line and enabling the linkage or electrically isolating the capacitive storage circuit with a control voltage V com as a function of said selection signal.
• a cell is implemented which has one or more of the preceding characteristics and in which the capacitance is discharged through a resistor Rf placed in parallel with the capacitor in order to obtain a temporary storage of an ignition state, and in which, under average operating conditions, the duration of the storage of an ignition state is less than the duration of a frame, and preferably less than or equal to the half the duration of a frame.
• a selection pulse V se ⁇ is applied to the selection line with a duration such that at the end of the pulse selection the voltage across the capacitor is a fraction of V com .
• control signal is modulated (in particular from one frame to another) in duration and / or in voltage level;
• V CO m the control voltage V CO m is modulated in voltage level
• the invention finally relates to a display with organic light-emitting diodes (OLED) of pixels and / or segments implementing a set of electronic control cells of said diodes organized in a matrix, each pixel or segment being able to be controlled individually by multiplexing line x column of the matrix, in which the cells are according to one or more of the cell characteristics indicated above.
• OLED organic light-emitting diodes
• the selection signals V himself ⁇ correspond to the lines of the matrix and the control voltages V CO m correspond to the columns of the matrix.
• the invention allows the production of a simplified display and if the simplification of the electronic control cells of the pixels of the display can be accompanied by an increase in the complexity of the control circuits upstream of the display and its cells, this increased complexity concerns circuits implementing well-known technologies, such as integrated circuits constructed from silicon wafers, and the overall impact of which in cost and / or consumption in complete electronic or computer equipment is minimal compared to the gain provided by the invention in the display. It can be implemented for the production of flexible flat screens.
• the advantages of the invention in the case of using a control transistor one can mention the elimination of the drag effect which is on the other hand observed on the displays of the state of the art.
• the invention also makes it possible to obtain structural simplification of the display, improved display characteristics in terms of reduction in consumption and, possibly as explained now, in visual perception. Indeed, among the other advantages of the invention, one can also cite the fact that the refreshment of the display of each OLED diode can allow modulation, in particular all or nothing, of the light energy produced over time. high frequencies (impulsive regime) not allowing a conscious perception of the modulation by the human user, but which however gives him an improved perception compared to a display which would be continuous.
• FIG. 1 which represents a first embodiment of the control cell
• FIG. 2 which represents a second example of realization of the control cell
• FIG. 3 which represents diagrams of time evolution of the selection voltage V himself ⁇ , the voltage across the capacitor and the current in the OLED.
• the electronic control cell for organic light-emitting diode (s) (OLED) of a pixel / segment of an active matrix display comprises a matrix set of such cells .
• Such a display operates sequentially in time units each corresponding to the display duration of a frame.
• the columns or rows of the matrix are scanned to allow the display configuration (level / intensity of switching on or off) of each of the pixels / segments.
• the pixel / segment OLED (s) are supplied via a control circuit which functions as an electronic switch as a function of a control signal arriving via a control line and making it possible to circulate or not in the OLED a variable intensity current obtained between a ground and a positive supply terminal V dd .
• the impedance (resistance) of passage of the control circuit in the on state is relatively low in order to cause the lighting of the OLEDs and to avoid ohmic dissipation (Joule effect) and too great losses.
• the control circuit In the blocked, non-conducting state, the control circuit has a high impedance (resistance) of passage, such that the leakage current is negligible and does not cause the OLEDs to ignite.
• the control circuit has a large control input impedance and very little load on the control line which has a capacitance C and a resistance Rf which return to ground or V dd depending on the case.
• the capacitance C and the resistance Rf may be added elements and / or intrinsic to other elements of the cell.
• C may be the “parasitic” input capacity of the control circuit and / or Rf the input impedance (resistance) of the control circuit (the control circuit therefore no longer has a large impedance / input resistance).
• Rf is the inherent leakage resistance of the capacitance (where then, conversely, C is the parasitic capacitance of the resistance Rf) which requires the manufacture of a particular capacitance (or conversely of a resistance) because the components usually available are generally practically pure components, that is to say resistors which are practically pure resistors and capacitors which are practically pure capacitors.
• This part of the cell with the control circuit and the control line with its capacity C and resistance Rf forms a switching element with temporary memory: when the voltage on the control line exceeds the conduction threshold V s [ of the control circuit, the latter becomes conducting, conductive and, conversely, when the voltage on the control line falls below the conduction threshold V s ⁇ of the control circuit, the latter becomes blocked, non-conductive.
• the control circuit can operate in all or nothing (substantially constant conductor / non-conductor) or linear as will be seen with transistors in the case of Figures 1 and 2. We understand that this explanation is simplified because in general the circuit may have hysteresis ("Schmidt trigger") and / or present progressive conduction zones as will be seen below in the case of the use of transistors.
• the conduction or non-conduction conditions above or below the threshold can be reversed depending on the type of inverter or not of the control circuit.
• the resistance which returns to the supply terminal opposite to that where the capacity returns the capacity and the resistance are in series between the two supply terminals and the control line is connected to the midpoint, between resistance and capacity.
• the selection circuit must cause a discharge for ignition and that the ignition of the OLED (s) by the control circuit must correspond to a discharge state.
• the capacity C will gradually discharge and if the initial charge of C is such that the voltage on the control line is greater than the threshold V s) the OLED (s) will remain on as long as the decreasing voltage on the control line is greater than the conduction threshold V s ⁇ of the control circuit.
• a selection circuit which also functions as a switch controlled by a selection signal V himself ⁇ , can apply (on, conducting state) or not (blocked, insulating state) on the control line a voltage V CO m-
• the voltage V CO m can be between a voltage below the threshold V s ⁇ , preferably at least 0V (to earth) and a voltage above the threshold V s ⁇ , preferably at most V dd .
• This voltage V CO m is one of the means of adjusting the display brightness in the case of a transistor control circuit as shown in Figure 1 or 2.
• FIGS. 1 and 2 give two particularly advantageous embodiments since they are relatively simple to carry out with only two transistors.
• the control circuit consists of a single control transistor 61, M1, connected between V dd by line 7 and OLED (s) 9 and return to ground by line 8.
• the input of the control transistor 61 is connected to the control line 5 'on which there is a capacitor C and a resistor Rf all returning two to V dd .
• the selection circuit consists of a single selection transistor 41, M2, connected between line 2 at voltage V com and the 5 'command line.
• the selection transistor 41 receives as input the line 3 of the selection signal V himself ⁇ -
• the control circuit consists of a single control transistor 62, M1, connected between V dd via an OLED via line 7 'and a return to ground via line 8'.
• the input of the control transistor 62 is connected to the control line 5 on which there is a capacitor C and a resistor Rf both returning to ground.
• the selection circuit consists of a single selection transistor 42, M2, connected between line 2 at voltage V CO m and the control line 5.
• the selection transistor 42 receives as input the line 3 'of the selection signal V himself ⁇ .
• V himself When the voltage of control line 5 is higher than the conduction threshold of the control transistor 62, the latter is on and the OLED (s) are on.
• Vse ⁇ must be as high as possible during the selection (selection pulse) and, for example, at V dd .
• M2 as a switch with a clipping and charge equalizing effect because, since the voltage difference must be greater than the conduction threshold of M2, the voltage across the terminals of the capacitance cannot be greater than the maximum voltage of V himself ⁇ .
• the invention can be implemented in a display comprising redundant components, in particular cells and / or transistors and / or light-emitting diodes, which can compensate for faulty components in order to reduce the rebus of manufacture of the displays which may include millions of components .
• the invention consists, basically, in controlling a pixel by voltage by charging a capacitance by a selection transistor M2 with a control voltage Vcom (which is preferably kept substantially constant during charging but which can be varied from one frame to another in order to modify the brightness of the successive pixels of a column) during the pulse duration of the selection signal V himself ⁇ corresponding to the pixel.
• Vcom which is preferably kept substantially constant during charging but which can be varied from one frame to another in order to modify the brightness of the successive pixels of a column
• This voltage control circuit behaves like a sampler-blocker which makes it possible to charge a capacity during the sampling period and to keep the charge (decreasing here) during the blocking period.
• This capacity is directly connected to the gate of a switching transistor M1 which makes it possible to supply the OLED (s) of the pixel.
• This grid has a high input impedance and the discharge of the capacitance through the grid (and the possible resistance in parallel of the capacitance) is relatively slow, preferably such that the OLED (s) are supplied during half of the duration of a frame.
• This capacity can be an added capacity or the input capacity, possibly increased by construction, of the control gate of the switching transistor M1.
• the selection signal V himself ⁇ goes to a positive voltage level during a pulse of duration t himself ⁇ which makes passing 2 during the said duration.
• the capacity charges up to the voltage value V 0 ied at the end of the selection pulse (rapidly increasing part of the curve) then, at the end of the selection pulse, the capacity gradually discharges (slowly decreasing part of the curve).
• the OLED (s) are on and, conversely, below, the OLED (s) are off.
• the control transistor operates in linear mode and the current follows the evolution of the voltage of the control line to the nearest offset due to the existence of the threshold voltage of the transistor M1. It is however envisaged that the transistor may be for a certain time in a saturation regime (while the capacitance is near its peak of charge) but the control of the brightness becomes more difficult. It is therefore possible to obtain a variation in the brightness of the pixels by modulating the control signal in duration and / or in voltage level (initial, at the end of the selection pulse) from one frame to another.
• This modulation can be obtained in several ways, that one modulates the control voltage V co m in voltage level and / or that the selection signal V is modulated himself ⁇ in duration, or even that one modulates in voltage level the selection pulse V himself ⁇ -
• the duration of a line is then 17.6 ⁇ s, which corresponds to the width of the selection pulse V himself ⁇ .
• the correction of the control signal can be done in the upstream electronic circuit for controlling the display.
• the preferred operating method is that in which the OLEDs are only lit for only part of the frame duration, i.e. there is a dead time during which each OLED is not lit for a duration of frame (it is understood that an OLED of a pixel which must not be visible will be unlit for the whole duration of the frame and that an OLED of a pixel which must be visible will be lit for only part of the duration of the frame). Dead time allows OLEDs to rest and can have a beneficial effect on the life of OLEDs.
• a voltage control allows modulation of the duration of the current sent in OLEDs.
• the control circuit 61, 62 works essentially in all or nothing, passing and turning on the OLED when the voltage on its control line 5, 5 'is above a threshold and blocked below.
• the selection circuit 41, 42 which receives an essentially binary selection signal Vsel is made on or off as a function of said signal Vsel for a substantially constant duration (pulse duration of Vsel) and the charge received by the capacitor C (therefore the voltage across its terminals) therefore essentially depends on the level of the control voltage Vcom.
• the variation of the voltage Vcom therefore allows coding in modulation of the ignition pulse width of the OLED.
• the voltage Vcom remains substantially constant for the duration of the pulse Vsel (neglecting the impact of the internal resistance of the source Vcom) and will be modified outside the pulses Vsel.
• the Vcom generator can be a digital analog converter with voltage output.
• the choice of the values of Rf and C will therefore be made as a function in particular of the frame duration and the possible values of Vcom provided as well as the threshold of the control circuit. so that there is indeed a dead time (no ignition) during a frame for an OLED for which the maximum of Vcom has been sent in the capacity during the Vsel pulse.
• the calculation of the time constant can be done as follows:
• the first stage is the adjustment of the time constants of the assembly to the type of screen envisaged, in this case a 1024x768 pixel display at the frequency of 75 Hz gives a duration of the frame equal to 13.3 ms, and a time selection less than or equal to 17 ⁇ s.
• the main characteristic time of the assembly is the constant RC, where C designates the storage capacity of the control, and R is the leakage resistance across its terminals.
• RC the constant RC, where C designates the storage capacity of the control, and R is the leakage resistance across its terminals.
• the transient phenomena in the transistors, with the gate length fixed at 10 microns do not play in a perceptible manner. We are therefore looking for a solution with RC of the order of a microsecond.
• the OLED lit for a duration close to half of the frame duration.
• the frame duration is roughly twice the time discernment of the human vision system, the generally accepted value of which is approximately 5 ms.
• the ignition of the OLED (s) can be obtained with a voltage greater than the threshold at the terminals of the capacity or, conversely zero and the loading / unloading of the capacity can be obtained with a voltage V himself ⁇ positive or, conversely, zero.
• the term positive voltage is relative and depending on the reference used and / or the components used, positive and negative, or even only negative, voltages with respect to ground can be implemented. It is however preferable to use cells in a device with display which are satisfied with a single voltage, and, in particular that of its power source which can consist of batteries or rechargeable batteries.

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• 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)
• Electroluminescent Light Sources (AREA)
• Control Of El Displays (AREA)

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• 2003
  • 2003-12-11 FR FR0351026A patent/FR2863758B1/fr not_active Expired - Fee Related
• 2004
  • 2004-12-13 CN CNA2004800402466A patent/CN1902676A/zh active Pending
  • 2004-12-13 JP JP2006543592A patent/JP2007518112A/ja active Pending
  • 2004-12-13 KR KR1020067013875A patent/KR20060134970A/ko not_active Withdrawn
  • 2004-12-13 US US10/582,493 patent/US20070091030A1/en not_active Abandoned
  • 2004-12-13 EP EP04816539A patent/EP1695332A2/de not_active Withdrawn
  • 2004-12-13 WO PCT/FR2004/050685 patent/WO2005059883A2/fr not_active Ceased

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