DE102005039538A1 - Display e.g. organic light emitting diode display, controlling method, involves carrying out recharging of diodes between natural and/or controlled precharge and reverse biasing of diodes using electrical resonant circuit - Google Patents

Abstract

It are a method and a circuit for driving a display described with a plurality of pixels (2), wherein the pixels (2) to turn on with Voltage controllable and at least temporarily energy-storing are constructed so that a pixel (2) after active operation a natural one Summons. When operating the ad, a pixel (2) precharged before being turned on with a controlled precharge and after switching off by means of a reverse polarity voltage charged with a reverse charge. To control electronically To simplify, takes place between the natural or controlled summons and the reverse charge of the pixels (2) each have a charge of the in charge present to the pixels (2).

Description

The The invention relates to a method and a circuit for driving a display with several pixels, which can be energized for switching on with voltage and are at least temporarily built energy storage, so that a pixel after active operation has a natural precharge, wherein precharged a pixel before powering up with a controlled precharge and after switching off by means of a reverse polarity voltage is charged with a reverse charge.

The Display can be in particular an OLED display or an LC display, in which individual pixels of the display are provided with electrodes, to apply voltage to the pixels and make the pixels glow bring or their translucency to change. The pixels internally have a capacity, the charge or energy stores.

Around the grayscale, for example, an OLED display high dissolve be the OLED diodes, of which typically a diode in one Pixel is usually pre-charged by applying a voltage. This process is also referred to below as a precharge. The Precharge takes place before due to the created Voltage of the active operating current through the controlled OLED diode begins to flow and the pixel of the display lights up. After switching off the on the voltage applied to the pixel, the OLED diode is in the off state after the operating current for a designated time has flowed through the diode. In this off state the diode becomes common with a negative voltage source reverse to the operating voltage connected. This process is referred to below as reverse biasing. The reverse biasing neutralizes hysteresis effects and can be the Extend service life of, for example, OLED diodes.

Before the OLED diode is again actively operated, i. turned on, it must be recharged with positive voltage again (precharge). During operation of the display, the consecutive ones are constantly repeated Processes of precharge, active operation (on-state) and of Off state of the pixels of a reverse biasing display. The transitions between reverse biasing, precharge and active reverse operation Biasing are technically difficult to accomplish.

It is known, the precharge or reverse biasing respectively isolated to treat. For example, OLED drivers are on the market available, the have a precharge and reverse bias function. The precharge voltage and the reverse biasing voltage, however, each with the help separate power sources for precharge and reverse Biasing the O-LED diode usually switched in two steps. It is starting, for example from the reverse biasing first the internal capacity of the pixel, i. the anode and the cathode become one with each other shorted. Then, between the anode and the cathode Precharge voltage applied.

something similar applies to the transition from active operation to reverse biasing after power off of the display pixel. After active operation is the OLED diode of the pixel is still positively poled because it has an internal capacitance and was positively charged during operation. This later explained in more detail effect will be below also as natural Summons or natural Precharge called. For the transition from the natural precharge For reverse biasing, the OLED diode is usually also first shorted and then with the voltage source for the reverse Biasing negatively poled.

Of course you can the OLED diode starting from the reverse charge (reverse biasing) without the transition Zero by shorting can be poled directly with the precharge voltage. The same applies to the reverse direction, i. the transition from the natural one Precharge to reverse biasing. All these transitions with or without zero intermediate due to a short-circuit however, the anode and cathode are so abrupt that high charge transfer currents can flow. With shorting the OLED diode as an intermediate, these Umladeströme at best halved and are still so high that they are the diode pixels of the Damage the display over time. This limits, in particular, in modern OLED-diplays, but also other ads the life of the ads. That is why in For some products, the recharge current for precharge and discharge limited.

However, these transitions forced by external power sources have the great disadvantage that the energy previously stored in the capacitance of the pixels is always destroyed. In addition, two external voltage sources are required for the controlled pre-charge (precharge) and the reverse charge (reverse biasing), whose voltage must be adapted to the respective display characteristics. However, this is extremely difficult, since the properties of the display constantly change during operation, in particular due to the heating, so that the voltage would have to be readjusted for an optimum life of the displays. In addition, the properties of the pixels scatter, for example of OLED diodes, production-related. To the life, in particular the OLED diode Anzei To extend gene, it is also necessary to provide an additional current limit for the Umladestrom. This makes the control electronics for displays electronically very expensive.

task The invention is therefore an energetic and circuit technology provide simplified control of a display with multiple pixels.

These The object is achieved with the features of the independent claims 1 and 10 solved. In the proposed method is in particular between the natural one or the controlled precharge and reverse charge of the pixels, respectively a transhipment of the charge present in the pixels made. This ensures that, for example, due to capacitive Properties of each pixel of the display reuses stored energy will and for the transhipment does not result in any significant loss of power. Further will the effect of the natural Vorladung by the active operation of the pixels, for example. In the manner of a OLED diode used, so no own voltage source for the precharge must be provided.

This Procedure leaves according to the invention especially advantageous if multiple pixels in a defined temporal Sequence can be switched on and off, so that the natural and / or controlled precharge of a first pixel with the reverse charge (reverse biasing) of a second pixel is reloaded and / or the reverse charge (reverse biasing) of a second pixel with the precharge (controlled Precharge) of a first pixel is transhipped without a connector to an external power source necessary for this Umladeprozess is. According to the invention is under Transhipment understood that the charge present in a pixel is used to set a defined state of charge in another Create pixels and vice versa. This defined state of charge in The other pixel should be in operation so in the display pixels existing energy can be achieved without - apart from possibly Existing energy losses - connections to separate Voltage sources for the controlled precharge and reverse biasing are necessary.

To can in the inventive method an electrical buffer may be used, for example in capacity to selectively transfer energy stored in one pixel to another pixel, in which it is needed in a subsequent control step.

A particularly advantageous embodiment this invention is when as an electrical buffer an electrical resonant circuit, in particular with an inductance between a first pixel or a first group of pixels, for example, in a first state of charge and a second pixel or a second one Group of pixels, for example, used in a second state of charge is, wherein the resonant circuit respectively according to the umzuladenden Pixel is switched. In this case, the power for reloading, for example due to the use of the resonant circuit a sinusoidal course have, so that a current limit is not necessary.

Especially The method of switching an OLED or LC display, preferably with multiple rows and / or columns of pixels. there can the desired temporal sequence of active operation, natural precharge, reverse Biasing and (controlled) precharge are transferred to the geometry of the ad, for example, by a series or column-wise control of pixels of a display, with several rows simultaneously or columns of pixels in active operation, in a natural Precharge state, in the reverse bias state and in one (controlled) Precharge state to prepare for active operation. there corresponds to the period for a frame of the temporal sequence of all rows or columns of the Displays, wherein the period is divided into a multiplex clock, each of the addressing clock or the addressing duration of a Corresponds to row or column.

Therefore the method according to the invention is suitable especially for a clocked operation, wherein a clocking preferably the residence time of a Pixels, such as an OLED diode, for active operation and possibly the natural one Precharge corresponds. The transhipment is preferably between two bars and the time and duration for the phases of the reverse charge, the natural one Precharge and / or controlled precharge preferably corresponds an integer multiple of a basic clock, which, for example, the Clock of active operation corresponds.

at the initialization of the display can according to the invention for a given Number of clocks the reverse charge to the clocked in the clock Pixels are supplied with an external power source. It will be like this many lines with the reverse charge, for example negatively polarized, which corresponds to the residence time of the OLED diode for reverse biasing.

In order to compensate for losses due to non-ideal electronic elements in the circuit, the state of reverse biasing can be compensated be refreshed from time to time as compared to the low frequency display timing by connecting to an external power source.

The The invention also relates to a circuit for driving a display with several pixels, which can be activated with voltage to switch on and at least temporarily built energy storage. This circuit is particularly suitable for carrying out the above Process. These are between a first pixel or a first Group of pixels and a second pixel or group of pixels a transfer circuit switchable to a summons a first pixel with a reverse charge reverse polarity of a second Pixels and / or an inverse charge of a second pixel with a Precharging a first pixel by means of an electrical buffer store.

According to one preferred embodiment of Invention is the Umladeschaltkreis an electrical resonant circuit in particular with an inductance as an electrical buffer. A reloading process is then ended in such a resonant circuit, when the current in the electrical resonant circuit is a first zero crossing reached.

This can be particularly easily realized by the Umladeschaltkreis via electronic switches connected to row and / or column electrodes of the pixels. To initiate the reloading process, the corresponding electronic switches closed and reopened after reloading. This Switching may occur within the normal timing of the display done so that an impairment the optical quality of the Display is not connected.

One Pixel of the display according to the invention, an LCD element and / or an OLED element with an electrode for driving.

According to one particularly preferred embodiment the circuit is this in an integrated circuit, for example in the form of an OLED driver IC, integrated to easily connect with existing ones Ads to be used.

The inventive principle the lossless transfer between individual pixels of the display a display uses the natural Precharge effect, usually with capacitive properties provided pixels of the display or the display for a lossless transhipment between controlled and / or natural precharge and reverse Biasing used, whereby by a clocked operation of the transhipment a suitable sequence control for including the entire display the initialization can be achieved. Especially advantageous is that no external source required for the precharge is and due to the use of the amount of natural charge Precharge uses an automatically adjusted precharge voltage becomes. This is a high efficiency of the driver for driving the display with a sinusoidal, gentle transhipment current achieved.

Further Features, advantages or applications of the invention result also from the following description of exemplary embodiments and the drawings. All are described and / or illustrated illustrated features for itself or in any combination the subject matter of the invention, also independent their summary in the claims or their back references.

It demonstrate:

1 a multiplex driver scheme for an OLED display;

2 an equivalent circuit diagram for an OLED pixel (diode);

3 a circuit diagram for explaining the natural precharge (natural precharge) of an OLED pixel;

4 the control of an OLED display according to the present invention;

5 the temporal voltage curve at an OLED pixel;

6 a programming scheme for the control of the entire OLED display and

7 the initialization process for the provision of reverse charges.

A passive matrix OLED display 1 which is shown schematically in FIG 1 consists of several columns C1 to Cs and rows R1 to Rm, wherein at each intersection of a row Cx, x = 1 to s with a row Ry, y = 1 to m, an OLED pixel in the form of an OLED diode 2 is arranged.

In a multiplexing process for operating the display 1 At a certain point in time, a row Ry is selected and activated. The OLED diodes 2 in this series Ry are fed with a set current and emit light. For this purpose, respective switches are closed in each column to be controlled Cx and the selected row Ry, which in 1 are not specified. In the example shown, the Switch of row R1 closed, leaving the first row of OLED diodes 2 is selected for control. It will be the OLED diodes 2 of columns C1 and C2 are made to shine because the switches in columns C1 and C2 are closed. The switches in columns C3 to Cs are opened, so that the arranged in these columns C3 to Cs OLED diodes 2 the R1 series does not light up. The OLED diodes 2 the further rows R2 to Rm are also passive and are shown symbolically only with a capacitance Cp and a series resistor R_ito, which also becomes active in this non-activated state.

In the following, the effect of natural precharge (natural precharge) exploited in the context of the invention will be described with reference to FIG 2 shown, simplified circuit model for the OLED diode 2 explains which the OLED diode 2 between the line resistances R_col and R_row represents, however, for the effect of the natural Precharges explained below play no role. Diode N describes the static core of the OLED diode 2 and contains an exponential characteristic which has been confirmed by measurements. Cp is the internal capacitance of the OLED diode 2 , The series resistor R_ito increases the forward voltage of the diode 2 something.

Based on this OLED model is in 3 below, the formation of the natural Precharges explained in more detail. With the series switch S _R , the selected row Ry is selected and activated. With a corresponding column switch S _C , a column Cx is operated.

In the left half of 3 shown first phase (operating phase), both switches S _R and S _{C are} closed; the diode 2 is energized and lit. This is the active operation of this OLED diode 2 , The diode voltage is above the slip voltage Vth of the OLED diode 2 , When the programmed pulse width is reached, the in 3 on the right side shown phase (shutdown phase) initiated. For this purpose, the column switch S _C and / or the series switch S _{R are} opened. The anode or cathode of the OLED diode 2 floating. At this time, the voltage at the OLED diode is initially still high because the internal capacitance Cp of the diode 2 charged. However, this voltage decreases because, due to the OLED voltage, which is above the slip voltage Vth, a current flows from the internal capacitance Cp into the actual diode N. The current flow is indicated by the arrow in 3 indicated. This will also after switching off the OLED diode 2 Emitted light. However, as the diode voltage decreases, the diode current decreases dramatically as the diode current exponentially depends on the voltage.

Therefore, the voltage across the capacitor Cp decreases only to the slip voltage Vth, since below the voltage Vth the current is negligibly small and the capacitance Cp is no longer (quickly) discharged. This floating state of the diode 2 persists when the row Ry, on which the diode 2 is deselected, since the series switch S _{R is} turned off and the diode 2 so that it is open to the masses.

This natural precharge effect is exploited in the invention to avoid the provision of an external precharge voltage source. This is particularly advantageous because the voltage of the natural Precharges always automatically the slip voltage Vth of the affected diode 2 at the current display temperature. The charge in the capacitance Cp after turning off the OLED diode 2 is first degraded by opening one of the switches S _C or S _R , is converted into light and thus is also useful energy. The remaining charge also corresponds to the charge that must be applied by the power source at the beginning of the active operating phase for charging the capacitor Cp. Thus, the charge delivered by the current source in the active phase is essentially used for light production.

This effect is achieved by the inventive control of the individual pixels or OLED diodes 2 of the display 1 according to the circuit in 4 exploited, being a pixel 2 precharged with a controlled precharge before being turned on, and charged after turning off by means of reverse polarity voltage with a reverse charge. Here, between the natural or controlled precharge and the reverse charge of the pixels 2 one charge each with the charge present in the pixels or their capacity. The principle of the lossless transfer circuit between precharge and reverse bias charging will now be described in detail with reference to FIG 4 explained.

The transfer takes place between two rows R _n and R _{n + a} , which are activated or deactivated by the series switches S _Rn and S _{Rn + a} by the driver for controlling the OLED display 1 the corresponding row R _n , R _{n + a} selected and connected to the ground, so that currents can be impressed into the desired columns C1 to Cs depending on the position of the column switch S _Cx . For each row, there is another transfer switch S _Un , S _{Un + a} , which is a series to an inductor 3 coupled, which in turn is connected to ground.

In the in 4 As shown, the row R _{n is} selected so that the diodes 2 of the series R _{n are} active. When the operating phase of this series R _{n is} over, the capacitances Cp of the OLED diodes 2 Of course summoned (natural precharge). This row R _n must now be reversed negatively (reverse biasing). In the illustrated state of the circuit according to 4 the row R _{n + a is} still biased negatively. To be actively operated later, the diodes must 2 on this row R _{n + a} still to be summoned. The exact time sequence in which sequence the two rows R _n and R _{n + a are} reloaded will be explained in more detail below.

The row R _n is therefore precharged in the illustrated state with the voltage of the natural precharge Vpre and must be negatively poled, while the series R _{n + a} with the voltage of the reverse charge Vrev is negative polarity and must be precharged controlled. According to the invention, the states between these two rows R _n and R _{n + a are} now reloaded without having to switch on external voltage sources for the precharge or reverse charge. The idea according to the invention therefore lies in an exchange of the charge states of the two series R _n and R _{n + a} . The total energy in the two rows R _n and R _{n + a} is the same as before, since the capacitances Cp of the OLED diodes 2 are the same size. According to the invention, the capacitances Cp in both rows R _n and R _{n + a} are reloaded against each other.

After the active phase of operation of a row R _{n is} over, all power sources are turned off. Before the next row R _{n + a is} activated, it is transferred between row R _n and row R _{n + a} . When reloading energy is released, which is converted according to the prior art either in heat and thus loss or can be cached according to the invention. According to the in 4 shown circuit of the OLED display 1 becomes an inductance 3 used.

The series switch S _Rn and the transfer switch S _{Un + a} are closed. Thus, the parallel-connected capacitances Cp of the series R _n and the parallel-connected capacitances of the series R _{n + a} with the inductance 3 one in 4 dashed line indicated electrical resonant circuit 4 , At the inductance 3 At the beginning, a voltage drops from Vpre + Vrev, so that the current begins to flow through the inductance. In this resonant circuit 4 are the OLED diodes 2 row R _{n + a} antiserial to the diodes 2 the series R _n switched. The capacitances Cp of the series R _n discharge charges and the voltage moves in the negative direction. The capacitances Cp of the series R _{n + a} get these charges and the voltage moves in the positive direction.

In such a resonant circuit 4 the current is zero again after half an oscillation period, the voltages in the two rows R _n and R _{n + a being} reversed. In this zero-crossing of the current, the switches S _Rn and S _{Un + a are} opened again. This is done by means of the known per se Zero-Current-Switching technology for resonant converters. After opening the switches S _Rn and S _{Un + a} , the circuit is again in a stable state, the diodes 2 of the series R _n , which previously had the natural precharge voltage Vpre, now have the reverse biasing voltage Vrev. The diodes 2 of the series R _{n + a} , which previously had the reverse biasing voltage Vrev, now have the precharge voltage Vpre. That's exactly the desired state change.

The transhipment is gentle due to the sinusoidal nature of the oscillation, with the magnitude of the current amplitude from the inductance 3 is determined. The energy loss is negligible, since the current is very small and the losses at the switches S _Rn and S _{Un + a are} very low. The switching losses are also negligible because the current is switched on and off at a current of zero. The natural precharge effect is exploited, so no external power source is required during normal operation. The amount of precharge voltage Vpre is always on the individual display 1 adapted at the current temperature. The duration of the transhipment is negligible compared to the multiplexing period with which the individual rows Ry of the display are switched, since the capacitances Cp are small overall.

While the precharge voltage Vpre can be set by the active operation, the reverse biasing voltage Vrev must be artificially generated the first time. This requires an external power source. It is used to initialize the OLED diode 2 with the reverse biasing voltage Vrev, which will be described later in detail. After initialization, the external voltage source for reverse biasing is only needed during a refresh to compensate for a small amount of energy lost by a resistor in the circuit. However, the refresh rate is very small and the charging current is low.

The magnitude of the reverse biasing voltage Vrev is set externally and may simply correspond to the voltage of the external voltage source. Also, the duration and the on and / or off time of reverse biasing can be externally programmed to extend the life of the display 1 to maximize.

After a series R _{n is} no longer active and has been turned off, the diodes are 2 still loaded. However, this series R _n need not be reversed immediately to the reverse biasing. Since the series switch S _{Rn is} turned off or opened, is the cathode of the OLED diodes open on this row. The naturally pre-charged state (natural precharge) of the OLED diodes 2 remains. This condition is also for the life of OLED diodes 2 or displays 1 uncritical, since the stress is negligible. This also applies to the controlled precharge before active operation, which is generated by the reloading according to the invention. The state of this pre-charge also remains due to the storage possibilities of the individual pixels 2 readily obtained.

In 5 is the time course of the active diode voltage Vak at the diodes 2 shown in a row Ry. The period is constant for the multiplex clock and is 1 / f _frame , where f _{frame is} the frame rate. A multiplexing period can consist of four phases. In the active phase t1 a series switch S _{R is turned} on or closed. The length of this phase is constant and is approximately 1 / m of the total multiplexing period, where m is the number of rows Rm to be multiplexed on the display 1 is. We have t1 = 1 / (m · f _frame ).

When the pulse width modulation duty cycle d is not 100%, no current is impressed in the period t1 after the time d · t1. Depending on the d-value, the diode voltage Vak thus also drops to the level of the natural pre-charge Vpre during the active phase t1. After the active phase t1 the switch S _R is open. At the latest at this time, the diode voltage Vak drops to the level of the natural pre-charge Vpre. A defined time t2 in which the diodes 2 naturally pre-charged, after the reverse biasing is started for reverse charge, can be freely entered or programmed. At time t1 + t2, the lossless transfer operation described above takes place. All diodes 2 the affected row Ry are now poled negatively. The amount of the reverse biasing voltage Vrev is set at initialization and refresh, respectively. The duration of the reverse biasing is set with the time t3. It is thus possible to program the amount, duration and timing of reverse biasing to implement the optimal conditions for maximizing display life.

The reverse biasing is terminated at time t1 + t2 + t3, to which the diodes 2 be summoned on the considered series Ry with the controlled precharge. Then this row will be reloaded with another row that is naturally preloaded and reverse biased. The voltage Vpre during the time period t4 is artificially charged, but corresponds to the level of natural precharge (natural precharge) Vpre, since the two rows are arranged on the same display and thus have the same precharge voltage Vpre, as well as the temperature of the two rows are essentially the same.

The length of time t4 in which the diode 2 is preloaded, can be specified again. As with phase t2, the precharge state for the lifetime of the OLED diodes is also here 2 uncritical, since the stress is negligible. Thus, a full period is programmed in which the diode is operated actively, twice on precharge voltage and once on reverse biasing voltage lingers.

During this period the diode becomes 2 Reloaded twice without loss. The period is 1 / f _frame = t1 + t2 + t3 + t4. The period duration t1 is at the same time the basic unit for t2, t3 and t4, by which this duration can be varied. The beginning and end of the transhipment can only be in the time gap between deselecting one row and selecting the next row. The beginning and the end of the active phase are in any case subject to the clock of t1. Therefore, all four transitions for the four phases t1 to t4 are at this t1 clock. Normalized to t1, the above equation is now: m _row = 1 + n ₂ + n ₃ + n ₄ , where n ₂ , n ₃ and n _{4 are} the number of basic units t1 in times t2, t3 and t4. For a display with 100 rows, the duration t2, t3 and t4 can be programmed to 1%, which is sufficient for a normal application.

This in 5 shown temporal scheme applies to a number. In 6 becomes the scheme for programming an entire display 1 Of course, each Umladeschalter S _U with the inductance 3 connected is. For the sake of clarity, however, only the transfer switches S _{Un2 + 1} and S _{Un3 + n2 + 1} are shown.

In 6 the first row R1 is currently active. The series switch S _R1 is closed. The closed column switches S _C1 and S _C2 symbolize that the pixels 2 in the columns C1 and C2 in the active row R1 are energized. The open column switches C3 to Cs symbolize that due to the image data no current through these pixels 2 flows because of these pixels 2 should not shine or because their pulse widths are already advanced. The following n2 rows R2 to R _n2 are naturally pre-charged. Further n3 rows are negatively polarized (reverse biasing). The last n4 rows (up to the row Rm) are preloaded under control (precharge).

When the active phase t1 of row R1 is over and the switch S _{R1 is} open, between the row R _{n2 + 1} , which is naturally precharged, and the row R _{n3 + n2 + n1} , which poles negatively and with reverse biasing loaded, reloaded. For this purpose, the switch S _{Rn2 + 1} and the switch S _{Un3 + n2 + 1 are} closed. With the help of inductance 3 thus creates an electrical resonant circuit, the Reloading between rows R _{n2 + 1} and R _{n3 + n2 + 1} without loss. The charge transfer process is short in comparison to the duration of the active phase t1, since the participating capacitances Cp of the OLED diodes 2 are small.

After the recharge, the series _switch S _Rm for the last row R _m that was precharged is turned on. This is now the active series. The boundaries between natural precharge, reverse bias and precharge are pushed up one row at a time. At each additional multiplex clock t1, the four phases are also shifted up one row. So the time sequence is according to 5 translated into the display geometry in rows. This is the sequence control for the entire display 1 derived.

The initialization of the reverse biasing voltage Vrev is performed in a similar scheme, which is described below with reference to FIG 7 is explained. The voltage Vrev of the OLED diodes 2 a display 1 that was not active and is turned on are usually undefined and may be zero, for example. However, the undefined state is immaterial to the invention since all states are defined after a first complete multiplex cycle. In 7 the states of all series are represented R1 to R _m during the first multiplex cycle cyclically for each clock pulse length t1. The letters u are undefined, a for active, n for natural precharge, r for reverse biasing and p for controlled precharge.

In the first t1 clock after switching on, first the first row R1 is activated, for example the lowest row R1 of the display 1 can be. When operating from an undefined state, the luminance achieved is unlikely to correspond to the set point because the diodes are not precharged (no precharge). However, this is not a problem since, after a first multiplex cycle, all rows R1 to Rm have defined states, as in FIG 7 shown. The picture is refreshed at the frame rate, so that the effect of the first power is usually not perceived.

At the second multiplex clock t1, the second row R2 is active while the first row is now naturally precharged. All other rows R3 to R _n are still undefined. In this rhythm, it continues now row by row. In the clock n2 + 1, therefore, a total of n2 rows are naturally pre-charged and the row R _{n2 + 1} is active. At the clock R _{n2 + 2} , the lowest row is now poled with the external reverse biasing voltage source. According to the active rows, the external reverse biasing polarity also continues to move after each clock, row by row. At n3 + n2 + 1, the bottom n3 rows are reverse biased, the next n2 rows are at natural precharge, and one row is active. After clock n3 + n2 + 1, reverse biasing is no longer generated externally. Row 1 and row n3 + 1 are reloaded, so that the bottom row is now precharged (Precharge) and row R _{n3 + 1 is} negative polarity (reverse biasing). The states at clock n3 + n2 + 1 are accordingly active with the bottom row on precharge, the next n3 rows on reverse biasing, another n2 rows on natural precharge, and the next row.

The two rows of transhipment go up one row at each bar, like the active row. At the end of the first multiplex cycle at the clock m, the states of all rows are defined as in 7 shown. At this time, the initialization according to the invention is completed.

The principle of lossless transhipment between rows or columns of the multiplexed display does not only apply to phase-modulated OLED displays, whose example has been described in detail above. This method can also be used in passive matrix displays, such as LCD displays. The pixels of the LC display are also capacitive in nature and have the ability to temporarily store energy. The voltage-driven pixels thus store energy for a certain time. The change of voltage can be done with the same circuit as for the pulse modulated OLED display 1 be realized lossless. This becomes all the more important as the layer thickness of the LCD becomes ever smaller and the capacitance increases accordingly.

Thus, with the present invention it is simultaneously possible to use the natural precharge, to enable reverse biasing, to achieve a smooth transfer without current limitation and the energy in the capacitances Cp of the diodes 2 to conserve.

1

OLED display

2

OLED diode, OLED pixels

3

inductance

4

electrical resonant circuit

cx

Column, x = 1 to s

Ry

Line, y = 1 to m

Cp

capacity

R_ito

series resistance

R_col

line resistance

R_row

line resistance

N

diode the OLED diode in the equivalent circuit diagram

S _R

series switch

S _C

column switch

S _U

Umladeschalter

Vpre

tension the natural one summons

V rev

tension the reverse charge

vak

active diode voltage

t1 to t4

Multiplexed phase

Claims (14)

Method for controlling a display with several pixels ( 2 ), which are energized to turn on with power and at least temporarily energy-storing, so that a pixel ( 2 ) has a natural precharge after active operation, wherein a pixel ( 2 ) is precharged before being turned on with a controlled precharge and, after being turned off, charged by means of a reverse polarity voltage with a reverse charge, characterized in that between the natural or controlled precharge and the reverse charge of the pixels ( 2 ) each a transhipment of the in the pixels ( 2 ) existing charge takes place. Method according to claim 1, characterized in that several pixels ( 2 ) are switched on and off in a defined time sequence, so that the pre-charging of a first pixel ( 2 ) with the reverse charge of a second pixel ( 2 ) and / or the reverse charge of a second pixel ( 2 ) with the summons of a first pixel ( 2 ) is transhipped. Method according to Claim 1 or 2, characterized in that an electrical intermediate store ( 4 ) is used. Method according to Claim 3, characterized in that an electrical oscillating circuit ( 4 ) between a first pixel ( 2 ) or a first group of pixels ( 2 ) and a second pixel ( 2 ) or a second group of pixels ( 2 ), each corresponding to the pixels to be reloaded ( 2 ) is switched. Method according to one of the preceding claims, characterized characterized in that the current for transhipment a sinusoidal course having. Method according to one of the preceding claims, characterized in that the method for switching an OLED or LC display ( 1 ), preferably with several rows and columns of pixels ( 2 ), is used. Method according to one of the preceding claims, characterized characterized in that the method is applied clocked, wherein the transhipment preferably takes place between two cycles and the time as well as the duration for the phases of the reverse charge, the natural subpoena and / or the controlled precharge preferably an integer multiple corresponds to a basic clock. A method according to claim 7, characterized in that upon initialization of the display for a predetermined number of timings, one pixel ( 2 ) the reverse charge is supplied to an external power source. Method according to one of the preceding claims, characterized characterized in that the state of the reverse charge with low frequency Refreshed by means of an external power source. Circuit for driving a display with several pixels ( 2 ), which are controllable for switching on with voltage and at least temporarily energy-storing, characterized in that between a first pixel ( 2 ) or a first group of pixels ( 2 ) and a second pixel ( 2 ) or a second group of pixels ( 2 ) a transfer circuit ( 4 ) is switchable to a pre-charge of a first pixel ( 2 ) with a reverse charge of reverse polarity of a second pixel ( 2 ) and / or an inverse charge of a second pixel ( 2 ) with a summons of a first pixel ( 2 ) by means of an electrical buffer ( 3 ) reload. Circuit according to Claim 10, characterized in that the charge-reversing circuit is an electrical oscillating circuit ( 4 ) with an inductance ( 3 ) is as an electrical buffer. Circuit according to one of claims 10 or 11, characterized in that the transfer circuit ( 4 ) via electronic switches (S _U ) on row and / or column electrodes of the pixels ( 2 ) connected. Circuit according to one of Claims 10 to 12, characterized in that a pixel ( 2 ) is an LCD element and / or an OLED element with an electrode for driving. Circuit according to one of Claims 10 to 13, characterized that the circuit is integrated into an integrated circuit is.