CN101031948A - Image displaying device and method for controlling displaying device - Google Patents

Abstract

The invention relates to an image display device of the active matrix type, comprising several light emitters (22, 23, 24), a current modulator (26) connected to each emitter, an Selection means (8, 14, 15), power supply means (36, 39, 40) for the transmitter and an operational amplifier (35) with an inverting (-) and non-inverting input (+) and output. According to the invention, the non-inverting input (+) or the inverting input (-) of the operational amplifier (35) is connected to the output (42) of the power supply (36, 39, 40) so that when the One of the transmitters (22, 23, 24), together with the gate of the modulator (26) connected to the output of the operational amplifier (35), forms the feedback loop of the operational amplifier (35). The invention also relates to a method of controlling such a display device.

Description

Image display device and display device control method

technical field

The invention relates to a display device, a display control circuit and a method for displaying images.

More specifically, the present invention relates to an active-matrix image display device comprising:

- several light emitters forming an array of emitters distributed in rows and columns, each emitter capable of being periodically addressed by the value of a display signal representing the display data for the duration of the image;

- a current modulator, connected in series to each light emitter of the array, thereby forming an emitter-modulator string, said modulator comprising a source, a drain, a gate, for one of the drain and source and the gate The voltage between the poles is greater than or equal to the release (trip) threshold voltage of the modulator, and the drain current can pass through the modulator to supply power to the light emitter;

- a storage capacitor of charge capable of maintaining the control voltage at the gate of each modulator for the duration of said image;

- Select device, able to select emitters in the same row;

- means for driving the emitters to emit light, comprising, for each column, means for powering these emitters, the power supply means being connected to one of the terminals of each emitter-modulator string of said column an output of one; and at least one operational amplifier, for controlling a corresponding modulator, having an inverting input (-), a non-inverting input (+), and an output, when a transmitter connected to the modulator is selected , the output of the amplifier may be connected to the gate of each modulator of the column, thereby applying the control voltage to the gate.

Background technique

Image display devices are increasingly used in various applications such as motor vehicles, digital cameras, or portable phones.

In display devices, it is known to form light emitters on the basis of organic light-emitting elements, such as OLED (Organic Light Emitting Diode) type display devices.

In particular, passive-matrix type (passive-matrix) OLED display devices have been widely available on the market. However, they consume a lot of power and have a short lifespan.

Active matrix type OLED display devices include integrated electronic components, and exhibit many advantages such as low consumption, high resolution, compatibility of video rates, and longer lifetime than passive matrix type OLED display devices.

Traditionally, these display devices comprise an active matrix, in particular formed by an array of light emitters. Each light emitter is tied to a pixel or sub-pixel of the image to be displayed and is addressed via an array of column and row electrodes via addressing circuitry.

The addressing circuit comprises in particular a current modulator capable of driving a current through the emitter and thus driving the light emission of each pixel or sub-pixel of the display device.

In active matrix, these modulators are thin-film transistors TFTs manufactured from polysilicon produced according to low-temperature polysilicon (LTPS) technology based on amorphous silicon layers. However, this technique introduces local spatial variation in the release threshold voltage between these transistors. These variations are due to the fact that the size and bonding of silicon particles are not sufficiently controllable during the crystallization step of amorphous silicon (Si-a) to polycrystalline silicon (Poly-Si).

Therefore, TFT transistors powered by the same supply voltage and controlled by the same display current or voltage produce currents of different magnitudes. Furthermore, the release threshold voltage of thin film transistors tends to vary in an inhomogeneous manner over time.

Now, since the emitter emits a luminous intensity proportional to the current passing through it, the heterogeneity of the release threshold of these transistors leads to non-uniform brightness of a display device comprising such transistors. This causes a discrepancy between the luminance levels and a noticeable visual discomfort to the user.

To limit this discomfort, various circuits for compensating the release threshold voltage have been proposed.

For example, document EP-1 340 019 describes a display device comprising a compensation circuit comprising an operational amplifier whose output is connected to the gate of a modulator and whose non-inverting input is connected in succession to The anodes of each emitter are in the same column without including the modulator associated with that emitter.

However, this device is extremely complex. It specifically requires the control of a large number of switches.

Contents of the invention

It is an object of the invention to achieve a simpler display device.

In view of this purpose, the subject of the invention is an image display device of the active matrix type, characterized in that one of the non-inverting and inverting inputs of an operational amplifier is connected to said output of the power supply means, so that when Selecting one of the transmitters forms a feedback loop of the operational amplifier with the gate of the modulator connected to the output of the operational amplifier.

Thus, unlike the pixel circuit described in the already cited document EP-1340019, the input of the operational amplifier is not connected to the common terminal of the emitter-modulator string of each pixel, but to one of the terminals of the string. one.

Thus, the invention makes it possible to directly command the currents used to power the emitters of each column to power the emitters, at least during their addressing periods. An advantage of the invention is that the instruction is executed without measuring the current.

Each emitter is addressed periodically when each image is to be displayed, or multiple times per image, depending on the display method used.

According to particular embodiments, the device includes one or more of the following characteristics.

One of the ends of each transmitter-modulator string of the column connected to the output of the supply means corresponds to the drain or the source of the modulator.

The output of the operational amplifier 35 then delivers a control signal V _c dependent on the display signals V _data22 , V _data23 and on the release threshold voltage V _th of the modulator 26 connected to the selected emitter 22 , 23 , 24 . The control signal V _c can charge the capacitor 30 .

One of the non-inverting (+) and inverting (-) inputs of an operational amplifier connected to the output, capable of receiving a signal dependent on the value of the display signal to be addressed to the column selected from said column launcher.

According to a first main variant, said power supply means also comprise a drive generator adapted to intermittently successively connect Power is fed to each emitter of a column, the drive signal is dependent on the display signal value to be addressed to the emitter selected from that column. Therefore, the drive generator successively powers the transmitter only during its addressing period.

The power supply means then generally also comprise a sustain generator whose function is to power the emitters of the column outside of their addressing phase. Such equipment requires switching means suitable for switching the power supply to the transmitter between driving the generator and sustaining the generator. In practice it is therefore common to have two additional switches in each addressing circuit, one for connecting the transmitter-modulator string to the drive generator during the addressing phase and one for Externally connect the transmitter-modulator string to the sustain generator.

As mentioned earlier, the output of the drive generator is connected to one of the non-inverting (+) and inverting (-) inputs of the operational amplifier. Only during addressing of the transmitters of that column, this same output is also connected to said terminal of the corresponding transmitter-modulator string via the switch switched on for addressing.

The drive generator comprises a display voltage generator and a resistive element connected in series, and the voltage generator is adapted to generate a voltage dependent on the value of the display signal to be addressed to the emitter selected from the column.

The resistor may be a resistor internal to the voltage generator.

With the series resistor, the value of the current flowing in the resistor and thus in the emitter during the addressing period is independent of the release threshold voltage of the modulator associated with the emitter. This current value is then proportional on the one hand to the difference between said value of the display signal and the value of the voltage applied to the other of the non-inverting and inverting inputs of the operational amplifier and on the other hand inversely proportional to the resistance value of the resistive element.

According to a second preferred main variant, said power supply means comprise a drive generator capable of supplying the entire group of columns with one and the same drive signal to one of the terminals of each emitter-modulator string of the column The emitters are powered continuously, the drive signal being dependent on the sum of display signal values for the entire set of emitters previously addressed to the column and the entire set of emitters currently addressed to the column for the duration of the image value. Advantageously, no additional maintenance generator is required, which was required in the previous first main variant.

The drive generator comprises a display voltage generator and a resistive element connected in series, and the voltage generator is adapted to generate a display signal value dependent on the current addressing Voltage to the sum of the displayed signal values of the entire group of emitters for that column.

The resistor may be a resistor internal to the voltage generator. With the series resistor, the value of the current flowing in the resistor and thus in the emitter is independent of the release threshold voltage of the modulator associated with the emitter. The value of the current is then on the one hand proportional to the difference between the sum of the values of said display signal and the value of the voltage applied to the other of the non-inverting and inverting inputs of the operational amplifier and on the other hand inversely proportional to the resistance of the resistive element .

It comprises no switching means between the output of said supply means and each of the end points of the transmitter-modulator string of the column. Advantageously, compared to the first main variant, the addressing circuit of the transmitter is simplified, since it is no longer necessary to alternately switch one of the terminals of the transmitter-modulator string between different drive generators, whereas in This is required in the first main variant.

The output of the drive generator is connected on the one hand to one of the non-inverting (+) and inverting (-) inputs of an operational amplifier and on the other hand to the corresponding transmitter-modulator string without an intermediate switch. endpoint.

A voltage generator is connected to the resistive element to deliver the drive current obtained on the basis of the following relationship:

$\mathrm{<span\; class="notranslate">\; I</span>}\frac{<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; p</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; da</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; refn</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}$

where R is the resistive element,

V _{ref n} is the reference voltage associated with emitter n, and

V _{data n} is the value of the display voltage addressed to emitter n, and

p is the total number of emitters in the column.

The driving device also includes a reference generator capable of delivering a reference signal to the other of the inverting (-) and non-inverting (+) inputs of the operational amplifier.

Each emitter exhibits certain electrical and/or optical properties, and the value of each reference signal depends on said electrical and/or optical properties.

Each emitter is associated with a color emission, and the reference signal can be modulated as a function of the color assigned to said selected emitter.

Traditionally, a given shade of white is referenced by tristimulus coordinates. With the present invention, the color performance of the device can be easily optimized and aging differences between emitters can be compensated.

The emitters are grouped into groups of adjacent emitters each emitting a different color, and for each group the reference signal is assigned to the individual emitters of the group in such a way that they are addressed by the same display signal value These emitters cause the white hue to be emitted by the group.

The driving device further comprises data storage means capable of storing display signal values addressed to each emitter for the duration of the image.

The subject of the invention is also a method for an image display device of the active matrix type comprising: several light emitters forming an array of emitters distributed in rows and columns, each emitter capable of being periodic addressing of display signal values representing display data for the duration of the picture; current modulators, comprising source, drain, gate, one of drain or source of each modulator connected in series emitters connected to the array, forming an emitter-modulator string comprising two terminals; selection means capable of selecting rows of emitters; storage capacitors of charge capable of maintaining the or each modulator for the duration of the image The control voltage at the gate place; The device for driving the emitter of the column to emit light includes at least one operational amplifier with an inverting input, a non-inverting input and an output; the method includes the following steps:

- transmitting a selection signal (V _select ) to the emitter row via the selection means;

- applying a drive signal (I) to one of the endpoints of each emitter-modulator string of the column by the drive means;

- applying a control signal (V _c ) to the gate of each modulator connected to the selected emitter by the driving means,

It is characterized in that it also includes the following steps:

- select the rows of emitters so as to utilize the gates of the modulators connected to the outputs of operational amplifiers and to utilize the non-inverting and inverting inputs of said operational amplifiers connected to said outputs of the supply means for these emitters One, to form the feedback loop of the operational amplifier.

According to a particular embodiment, the method comprises the feature that the drive signal is dependent on the sum of the values of the display signals of the entire group of emitters addressed to the column for the duration of the image.

Description of drawings

The invention will be better understood by reading the following description, given by way of example only, with reference to the accompanying drawings, in which:

- Figure 1 is a schematic diagram of a display device according to the invention;

- Figure 2 is a schematic diagram of a part of the display device represented in Figure 1;

- Figure 3 is a flow chart schematically representing some steps of the control method according to the invention;

- FIG. 4 is a time profile representing the selection voltage applied to the selection electrodes of the first addressing circuit of the display device according to the invention;

- Figure 5 is a diagram representing the time profile of the selection voltage applied to the selection electrodes of the second addressing circuit of the display device according to the invention;

- FIG. 6 is a diagram representing the time profile of the display voltages generated by the drive generator for successively addressing the individual addressing circuits, in particular the first circuit and the second circuit, of the same column of the display device according to the invention;

- FIG. 7 is a graph representing the time profile of the drain current flowing through the modulator of the first addressing circuit;

- FIG. 8 is a time profile representing the drain current flowing through the modulator of the second addressing circuit of the display device according to the invention;

- FIG. 9 is a diagram representing the time profile of the driving current generated by the driving unit of the display device according to the present invention;

- FIG. 10 is a schematic diagram of a first variant embodiment of the portion represented in FIG. 2 of the display device;

- FIG. 11 is a schematic diagram of a second variant embodiment of the portion represented in FIG. 2 of the display device;

- FIG. 12 is a diagram comprising curves representing the currents flowing through the terminals of the respective emitters of the display device according to the invention as a function of the voltage applied to them;

- Figure 13 is a schematic view of a third variant embodiment of the part of the display device represented in Figure 2 .

Detailed ways

Fig. 1 shows an image display device according to the present invention. The latter consists of an active matrix 1 driven by a control device 2 .

In a manner known per se, the active matrix 1 comprises a plurality of addressing circuits 3, 4, 5, 6, each associated with a transmitter (not shown) and distributed in rows and columns.

The control device 2 of the active matrix includes a control system 7 , a selection control circuit 8 and an address control circuit 10 .

The control system 7 is able to receive the image display signal, to process the signal (eg decode and decompress) and to deliver synchronization signals to the selection control circuit 8 and display signals to the addressing control circuit 10 .

The selection control circuit 8 is connected to a plurality of row electrodes 14, 15, each associated with a row of emitters. On receipt of the synchronization signal, the circuit 8 is adapted to successively generate a selection pulse V _select at each row electrode 14 , at a scanning frequency corresponding to the duration of the picture, first sequentially selecting the whole set of addressing circuits 3 , 6 for that row. The select pulse V _select is logic data for selecting the transmitter.

The addressing control circuit 10 is connected to a plurality of column electrodes 16, 17 and a plurality of drive electrodes 18, 19, each associated with a column of emitters 21A, 21B. It comprises a plurality of addressing drive units 20A, 20B, each capable of being addressed via column electrodes 16, 17 and drive electrodes 18, 19 and supplying power to addressing circuits 3, 4, 5, 6 of columns 21A, 21B.

The row electrodes 14, 15, the column electrodes 16, 17 and the drive electrodes 18, 19 enable to select, address and supply power to a specific addressing circuit in a set of circuits 3, 4, 5, 6 of the display device respectively become possible.

Thus, by selecting only the row electrode 14 of the display device, and by activating the drive unit 20A capable of delivering the control voltage _Vc to the electrode 16 and the drive current I to the electrode 18 of the column 21A, the electrodes located in this row 14 and the electrodes 18 of the column 21A are activated. The circuit 3 at the intersection of the electrodes 16 and 18 of the column emitter 21A does not activate the other circuits 4, . . . , 5 of the same column.

Figure 2 shows light emitters 22, 23, 24, each with addressing circuits 3, 4, 5 of a group of pixels of emitter column 21A and the addressing drive unit 20A and addressing drive circuit 3 of the emitter column 21A , 4, 5, 6 selection control circuit 8 is associated.

The emitters 22, 23, 24 of the display device are organic light emitting diodes. They include an anode and a cathode. The structure of these diodes is "traditional", meaning that the anode is the lower layer, on the substrate side, the cathode is the upper layer.

These emitters emit luminous brightness proportional to the current flowing through them. Each emitter constitutes a primitive pixel. These basic pixels have the same properties (same color emission) in the case of monochrome screens, or are structured in red, green and blue trios in the case of color screens.

Within the framework of the invention, groups of emitters 22, 23, 24 of columns are associated with sub-pixels of the same color. Three adjacent columns of emitters are associated with the colors red, green, blue in succession. The bias voltage required to pass the same value of current through the emitters 22, 23, 24 varies as a function of the current-voltage characteristics of these emitters, and specifically as associated with each column of emitters 22, 23, 24 varies as a function of the color of the associated sub-pixels.

Since the addressing circuits 3, 4, 5 of the active matrix 1 are identical, only circuit 3 will be described in detail.

Circuit 3 comprises a current modulator 26 , a switch 28 formed by transistors, a storage capacitor 29 and a supply electrode 30 .

The current modulator 26 and the switch 28 are thin film transistors based on the use of polycrystalline silicon (Poly-Si), amorphous silicon (a-Si) or monocrystalline silicon (μc -Si) technology. This element includes three electrodes: a drain electrode and a source electrode, between which a modulated current called drain current flows; and a gate electrode, to which a control voltage _Vc is applied.

The source of modulator 26 is connected to the anode of emitter 22, in this way modulator 26 and emitter 22 are connected in series. One 31 of the terminals of the string, here the drain of the modulator 26 , is connected to the drive electrode 18 . The current passing electrode (drain or source) connects the gate of the modulator 26, on the one hand, to the first terminal of the capacitor 29 and, on the other hand, to the switch 28 via the wire 33 . The other current-passing electrode (drain or source) of the switch 28 is connected to the column electrode 16 . The gate of switch 28 is connected to row electrode 14 . The second terminal of each capacitor 29 of the set of circuits 3 , 4 , 5 of column 21A is connected to a supply electrode 30 . Finally, the other end 32 of each modulator-emitter string, here the cathode of the transmitter 22 , is connected to a power supply electrode 34 . Both power supply electrodes 30 and 34 may be connected together to the same potential by a wire (not shown).

The modulator 26 shown in Figure 2 is n-type so that its drain current flows between its drain and its source when in operation. It is worth noting that this device can also be used to drive a p-type TFT as shown in FIG. 10 which still has a diode of conventional structure.

A capacitor 29, arranged between the gate and the source of the modulator 26, is adapted to substantially keep the control voltage of the gate of the modulator 26 constant during a time interval corresponding to the duration of the images T1, T2, so that at Keeps the brightness of the emitter for this duration.

A power supply electrode 30 is capable of supplying a desired voltage biased to a desired potential to one terminal of capacitor 29 as is known in the art.

The drive unit 20A is modulated so that the release threshold voltage _V of each modulator 26 of the set of addressing circuits 3, 4, 5 of the column 21A is compensated with a feedback loop described hereafter and is supplied to the transmitters 22, 23 of the transmitter column 21A. , 24 power supply.

To this end, it comprises an operational amplifier 35 with an inverting input -, a non-inverting input + and an output. The output of this amplifier 35 is connected to the column electrode 16 and its non-inverting input + is connected to the drive electrode 18 to ensure power supply to the emitters of the column via the modulator associated with them. Thus, the non-inverting input + is simultaneously connected to the anode of each emitter 22 , 23 , 24 of the column 21A via the modulator 26 associated with each emitter 22 , 23 , 24 of the column 21A.

Thus, each time the switch 28 of the addressing circuit 3, 4, 5 of the emitter column 21A is turned on, the signal is driven by the drive electrode 18, the terminal 31 of the modulator-emitter string, the modulator 26, the line 33 and the column electrode 16. A feedback loop for amplifier 35 is formed. It should be noted that in the embodiments presented in Figures 2 and 10, the end point 31 of the modulator-transmitter string forming part of the feedback loop corresponds to either the drain or the source of the modulators of the string.

The amplifier 35 can operate in feedback and thus compensate the release threshold voltage V _th of each modulator 26 of the addressing circuit 3 , 4 , 5 of the transmitter column 21A, as will be explained later in the description.

Furthermore, the drive unit 20A is capable of addressing and powering the emitters 22 , 23 , 24 of the column 21A with a drive current I. This current I depends on the sum of the values of the display voltages V _data22 , V _data23 , V _data24 addressed to the emitters 22 , 23 , 24 of the column 21A.

To this end, it comprises a drive current generator 36 and a reference voltage generator 38 connected to the non-inverting input + and the inverting input − of the amplifier 35 respectively.

The current generator 36 is formed by a variable voltage generator 39 connected in series to a resistor 40 . Drive electrode 18 is connected to the output of resistor 40 , to node 42 , thus forming one output of current generator 36 .

The generator 39 is a variable voltage generator whose voltage varies as a function of the value of the display signal _Vdata22 , _Vdata23 which is to be addressed to the transmitter 22, 23, as will be explained later in the description .

The generator 38 is a generator adapted to deliver a reference voltage fixed during setup of the display device and specific for each column. As a variant, it is also possible to use a variable voltage generator; the variation of the reference voltage is a function of the addressed emitter column 21A, as will be described later in the description.

The output of generator 38 is optionally connected via resistor 44 to the inverting input − of amplifier 35 . This resistor 44 is not absolutely necessary for the operation of the drive unit 20A. It merely has the advantageous function of balancing between the two inputs of the operational amplifier 35 .

Also optionally, a capacitor 46 is connected between the inverting input of amplifier 35 - and the output of this amplifier. Resistor 44 and capacitor 46 constitute a compensation arrangement which makes it possible to advantageously increase the accuracy and stability of the circuit.

The drive unit 20A also includes a data storage device 48 and a control module 50 for the generators 38 and 39 .

The memory means 48 comprise a database 52 adapted to store on the one hand the values of the display signals Vdata22, _Vdata23 addressed to each emitter ₂₂ , 23 of the column 21A during the previous image duration T1, and on the other hand On the one hand data is stored for identifying or locating the addressed transmitter 22, 23 which is the transmitter to which the value has been addressed.

The storage means 48 also include a directory 54 adapted to store reference voltage values associated with the group of emitters of column 21A. This value depends on the color red, green or blue associated with the emitters 22, 23 of column 21A.

As can be seen in Figure 12, emitters associated with different colors exhibit different current-voltage characteristics. Therefore, it is necessary to apply different voltages to the terminals of the red and blue emitters in order to obtain the same brightness and the same value of the current flowing through these emitters.

Here, the reference voltage value of the catalog 54 for each column is fixed as a function of the color of the emitters of column 21A. This is performed at the factory during display device setup performed before the display device is delivered for use. These reference values are established to compensate for variations between the current-voltage electrical characteristics and/or luminescence characteristics of the various emitters of the device, as described below.

Typically, since these characteristics are mainly dependent on the color emitted by the emitters, there will be three different reference voltage values: a first value V _ref.R common to groups of red emitters in the first column, A second value V _ref.G common to the group, and a third value V _ref.B common to the group of blue emitters of the third column. According to a more complex variant, these reference voltage values are specific for each column of emitters, compensating the current-voltage electrical characteristics and/or luminous characteristics between the emitters of the individual columns even if they have the same luminous color The change.

Current can flow through the emitter only when the display signal _Vdata addressed to the emitter is higher than its associated reference voltage _Vref . In order to avoid having to use display signals of excessively high values, during display device setup the lowest possible value of the reference voltage will preferably be established while still obtaining the desired compensation.

The control assembly 50 is connected to the storage device 48 for searching and recording information in said device.

Furthermore, assembly 50 is able to receive a display signal transmitted by system 7 and is able to control generators 38 and 39 as a function of this signal and the information stored in memory means 48 .

When operating, the circuits 8 and 10 are capable of addressing and powering the groups of transmitters 22, 23, 24 of the matrix 1 and selecting the groups of transmitters 22, 23, 24 of the matrix 1 in succession.

During step 60 shown in FIG. 3, at the beginning of the first image frame T1, the driver circuit 20A and the circuit 8 control the lighting of the first emitters 22 of the column 21A as soon as the switch is turned on. This step 60 includes steps 62 to 69 .

During step 62 , circuit 8 generates a selection pulse V _select22 at row electrode 14 . This pulse, represented in FIG. 4 , enables switch 28 to be turned on.

In parallel, during step 64 , assembly 50 queries directory 54 to determine the reference voltage associated with the column of transmitters 22 . In particular, the reference voltage depends on the color of the sub-pixel associated with the emitter 22, 23, 24 of the column.

During a step 66 , the assembly 50 controls the generator 38 so that the latter delivers a reference voltage V _ref21A for the emitters of the column 21A, the value of which is constant and equal to V _refa .

In parallel, during a step 68, the assembly 50 receives from the control system 7 the value _Va of the display voltage V _data22 to be addressed to the transmitter 22 and the identification or position of the addressed transmitter 22 associated with this value . The component 50 then records in the database 52 this value _Va and the identity of the transmitter to which the value is addressed.

Simultaneously, during a step 69 , the assembly 50 controls the generator 39 so that the latter generates the value V _a of the display voltage V _data22 to be addressed to the transmitter 22 , as shown in FIG. 6 .

Thus, the generator 38 provides a reference voltage V _ref21A equal to V _refa to the inverting input − of the amplifier 35 . At the same time, the generator 39 supplies the voltage V _data22 equal to _Va shown in FIG. 6 to the resistor 40 . This voltage V _a generates a drive current I=I ₂₂ , which is introduced into the drain of the modulator 26 via the drive electrode 18 . The drive current I=I ₂₂ represented in FIG. 7 is defined by the following relationship:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; two</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; ref\; a</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}$

where V _a is the value of the display voltage V _data22 generated by the generator 39 , V _refa is the value of the reference voltage generated by the generator 38 , and R is the value of the resistor 40 . It should be noted that optional resistor 44 is not entered into the current calculations since no significant current, at least with respect to the value of drive current I22 , flows through it.

Considering that the modulator 26 of the circuit 3 connected in series to the first emitter 22 operates in its saturation mode (V _gs −V _th < V _ds ), the drain current through it is equal to the drive current I, and the following relation holds:

$\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; two</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; gs</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; gs</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$

$<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; ref\; a</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}$

where I22 is the drain current through the modulator 26, _Vgs is the voltage between the gate and source of the modulator 26, k is a constant dependent on the intrinsic characteristics of the modulator 26, and _Vth is the release of the modulator 26 The threshold voltage, and V _ds is the voltage between the drain and source of the modulator 26 .

With the feedback loop according to the invention, the potential difference between the inverting input − and the non-inverting input + of the amplifier 35 disappears. The voltage at node 42 is then equal to V _refa . Amplifier 35 thus delivers a control voltage _Vc to the gate of modulator 26, which is automatically modulated to a value such that current I=(Va _{- Vrefa} )/R passes through modulator 26 and emitter 22 in series, thus This current is independent of the release threshold voltage of modulator 26 . Compensation for the release threshold voltage of the emitter 22 of the device is thus obtained directly without including measurement of the current through this emitter.

The value V _gs is automatically derived from the value of the control voltage V _c .

The value of the control voltage V _c depends not only on the display signal V _{data 22} of the emitter and the reference voltage V _refa associated with that emitter, but also on the release threshold voltage V _th of the modulator 26 .

When the generator 39 imposes the value _Va of the display voltage V _data22 , since the generator 38 imposes the voltage V _refa , the release threshold voltage V _th is adjusted by the amplifier 35 since it is inherent to the structural characteristics of the modulator 26 and modulates the control voltage _Vc applied to the gate of the modulator 26, thereby compensating the modulator's release threshold voltage _Vth .

Thus, the control voltage _Vc at the output of amplifier 35 is precisely modulated to the voltage required to address transmitter _{22 with the value Va of display voltage Vdata 22 and} is independent of the value of release threshold voltage _Vth of modulator 26. This modulation occurs, and does so even though the voltage varies over time.

This control voltage is then maintained at the gate of modulator 26 via capacitor 29 for the remainder of the picture duration, while switch 28 of circuit 3 is opened again, as is known in the prior art.

During step 70, the second emitter 23 of column 21A is illuminated. Step 70 includes steps 72 to 79 .

During a step 72 , the circuit 8 transmits to the row electrode 15 a selection pulse V _select23 , such as that represented in FIG. 5 .

During step 74 , assembly 50 determines a reference voltage V _ref21A associated with the column of transmitters 23 by interrogating memory device 48 . Because emitter 23 is in the same column as emitter 22, and since these emitters are all associated with the same color, the value V _refa of this reference voltage V _ref21A is equal to the reference voltage V generated during addressing of the first emitter 22 The value V _refa of _ref22 .

During step 76 , assembly 50 controls reference generator 38 such that the latter generates voltage V _refa determined during step 74 .

In parallel, during a step 77, the assembly 50 receives from the system 7 the value _Vb of the display voltage _Vdata23 to be addressed to the transmitter 23 and represented in FIG. The identity or location of the addressed transmitter 23 is recorded in the database 52.

During step 78, the assembly 50 compares the value V a _of the display voltage V _data22 of the emitter 22 previously addressed to the same column with the value V _b of the display voltage V _data23 of the next emitter 23 to be addressed. add.

Then, during a step 79 , the assembly 50 controls the generator 39 so that the latter delivers a display voltage equal to the voltage value calculated during the step 78 , ie V _a +V _b .

Thus, the new drive current flowing through resistor R and drive electrode 18 becomes I=I ₂₃ +I ₂₂ as represented in FIG. 9 , where the common point of resistor R and drive electrode 18 is connected to the non-inverting Input terminal +, and is defined by the following relationship:

$\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; two</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; three</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; data</span>}\mathrm{<span\; class="notranslate">\; twenty\; two</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; data</span>}\mathrm{<span\; class="notranslate">\; twenty\; three</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; ref\; a</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}$

The current I ₂₂ =(V _data22 −V _refa )/R required to turn on the transmitter 22 continues to power the modulator 26 . In particular, since the switch 28 of the circuit 3 is now open, the same control voltage V _c is maintained at the gate of the modulator 26 of the first circuit 3 by the capacitor 29 rather than by the amplifier 35 . This voltage V _c controls the intensity of the current supplied to the transmitter 22 such that it is equal to the intensity programmed during step 60 .

The remaining current I ₂₃ =II ₂₂ =V _data23 /R on the drive electrode 18 supplies the modulator 26 of the second circuit 4 . Since during step 72 the switch 28 of the circuit 4 has been turned on, the column electrode 16, the amplifier 35, the drive electrode 18, the terminal 31 of the modulator-emitter string, the modulator 26 of the second circuit 4 and the second Line 33 of circuit 4 forms a new feedback loop of amplifier 35 . Thus, the control voltage _Vc from the amplifier 35 compensates the release threshold voltage _Vth of the modulator 26 of the second circuit 4 as before.

By performing steps similar to steps 72 to 79 for each addressing circuit 3, 4, 5 of column 21A, during the same first image frame duration T1, by addressing the entire set of emitters 22, 5, 23, 24, to continue to execute the method for addressing a display device according to the present invention. Specifically, the database 52 then contains the value V _data.n of the display voltage of each emitter addressed to the column 21A during this first image frame, and the assembly 50 controls the generator 39 so that the latter Pass display voltage $V=\underset{\mathrm{no}}{\mathrm{\&Sigma;}}{V}_{\mathrm{data}.\mathrm{no}}.$ Then, the drive current I flowing through the drive electrode 18 is defined by the following general relationship:

$\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; p</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; data</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}\mathrm{<span\; class="notranslate">\; twenty\; one</span>}\mathrm{<span\; class="notranslate">\; A</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}$

in:

I is a driving current generated by the driving unit 20A and flowing through the driving electrode 18;

_In is the current flowing through emitter n;

V _datan is the value of the image display voltage addressed to emitter n;

V _ref21A is the value of the reference voltage associated with the emitters of column 21A; and

p is the number of emitters in column 21A.

After the image duration T1, the entire set of emitters 22, 23, 24 of column 21A are lit as a function of the display voltage representing the image data to be displayed by these emitters, during step 80 the circuit 3 second times are addressed. This step 80 includes step 82 to step 89 .

Steps 82, 84, 86, 87, 88 and 89 are respectively equivalent to steps 62, 64, 66, 68 and 69, and will not be described again. For this second addressing of circuit 3, the steps are adjusted such that assembly 50:

- receiving from the database 52 the value V _a of the display voltage V _data22 previously addressed to the emitter 22 during the previous image frame and receiving from the system 7 the new value of the display voltage V' _data22 to be addressed to the emitter 22 V' _a , and this new value V' _a is recorded in the database 52 to replace the old value V _a .

中减去旧值V_a并将新值V′_a加到其上。- from and

Subtract the old value V _a from and add the new value V' _a to it.

的新值的显示电压。Assembly 50 then controls generator 39 so that the latter delivers a value equal to the calculated sum

The new value of the displayed voltage.

The second addressing of circuit 4 is performed in the same way. After the image duration T2, the entire set of emitters 22, 23, 24 of column 21A is illuminated as a function of the display voltage representing the new image data to be displayed by these emitters.

The other image frames then follow the previous image frame just as image frame T2 follows image frame T1.

In an exemplary embodiment of the invention, as shown in FIG. 6, during the image duration T1 a value of the reference voltage V _ref22 equal to V _ref has been applied to the inverting input − of the amplifier 35, and A value of display voltage V _{data 22} equal to _Va has been addressed to emitter 22 . This value V _a of the addressing voltage is continued during the new picture duration T2.

并且没有修改在先前图像持续时间T1的过程中由电路3的电容器29存储的电荷。Therefore, during the second image duration T2, there is no modification and

And the charge stored by the capacitor 29 of the circuit 3 during the previous image duration T1 is not modified.

Likewise, during the step of illuminating emitter 23 (not shown in FIG. 3 ), during the first and previous image duration T3 ( FIG. 6 ), the value of the display voltage addressed to emitter 23 is equal to V _b , then during the next picture duration T4 the value of the display voltage addressed to the emitter 23 is equal to zero.

简单地减小了值V_data，使得消除了在电路4的电容器29上积累的全部电荷，并且使得后者展示出零电势，即未点亮的二极管的特征。Therefore, and

Simply reducing the value _Vdata removes all charge accumulated on capacitor 29 of circuit 4 and causes the latter to exhibit zero potential, characteristic of an unlit diode.

Advantageously, it can be seen that the display device and the display method make it possible to avoid an initialization phase before programming the addressing circuits 3 , 4 , 5 .

Advantageously, using a reference voltage applied to one of the inputs of the amplifier 35 and specific for each column of emitters or for groups of columns of different colors as here, advantageously makes it possible to reduce the consumption of the display device. In particular, if the values of the reference voltages are chosen not only in such a way as to compensate for variations in the electrical and/or luminous properties of the emitters of the columns, but also in such a way as to obtain the lowest possible average value of the reference voltages per column value, the value V _data of the display signal can be shifted and reduced accordingly, thus reducing the power to be generated by the power generator 39 .

In the case of FIG. 2 of an OLED display device of conventional construction, forming the interface of the active matrix 1 are the anodes of the emitters 22, 23 (diodes of "conventional" construction): the drain of the modulator 26 ( n-type case) or source (p-type case) to drive electrode 18 and connects the cathodes of emitters 22 , 23 to electrode 34 . Drive electrode 18 is then connected to node 42 where one of the outputs of power supply 36 and the non-inverting input + of amplifier 35 are connected together.

However, as shown in Figure 11, the invention also applies to display devices with a so-called inverting structure, where the cathodes of the emitters form the interface to the active matrix: the drain (p-type case) or source of the modulator 26 is then connected to The pole (n-type case) is connected to the drive electrode 18 and the anodes of the emitters 22 , 23 are connected to the electrode 34 . The drive electrode 18 is connected to a node 42 where one of the outputs of the power supply means 36 is in this case connected to the inverting input of the amplifier 35 . This circuit is more stable than the circuit described with respect to diodes of conventional construction, advantageously, no resistor 44 or any balancing and/or compensating capacitor 46 is now required. The display signal then corresponds to a negative voltage and "pulls" the diode's current from the supply electrode 34 .

As a variant, the generator 38 can alter the reference voltage as a function of the aging of the transmitter, or can reduce it in low consumption mode.

As a variant, a reference voltage is associated with each column of emitters. In this case, the storage means 48 comprise a database capable of storing the value of the reference voltage to be applied to each column of emitters. The drive unit 50 is adapted to search the database for the value of the reference voltage to be applied to the inverting input - of the amplifier 35 as a function of the identity or position of the transmitter column.

According to the invention, the difference (V _refx −V _refy ) is preferably established during setup before the device is put into service in such a way as to compensate for differences in the electrical and/or luminous properties of the individual emitter columns.

A part of a display device according to a third variant embodiment of the present invention is shown in FIG. 13 .

The same electronic components of the display device as those of the display device shown in FIG. 2 are designated with the same reference numerals.

The display device comprises an addressing circuit 103 connected on the one hand to the addressing drive unit 20A via column electrodes 16 and drive electrodes 18 and on the other hand to the selection circuit 8 via row electrodes 14 .

The circuit 103 is adapted to address and power the transmitter 22 , the cathode of which is connected to the power supply electrode 34 .

The circuit 103 comprises a current modulator 26 , three switches 28 , 106 , 108 formed by transistors, a storage capacitor 29 , and a ground electrode 110 .

The drain of the modulator 26 is connected to the anode of the transmitter 22 so that the modulator 26 and the transmitter 22 are connected in series. The gate of the modulator 26 is connected on the one hand to the first terminal of the capacitor 29 and on the other hand to a current-passing electrode (drain or source) of the switch 28 via a wire 33 . The other current-passing electrode (drain or source) of the switch 28 is connected to the column electrode 16 . The gate of switch 28 is connected to row electrode 14 . The second end of the capacitor 29 is connected to the ground electrode 110 . The source of the modulator 26 is connected on the one hand to the drain of the switch 108 and on the other hand to a current-passing electrode (drain or source) of the switch 106 . The source of switch 108 is connected to ground electrode 110 . The gate of switch 108 is connected to row electrode 14 . The other current pass electrode (drain or source) of the switch 106 is connected to the drive electrode 18 . The gate of switch 106 is connected to row electrode 14 .

The drive circuit 20A has been partially shown. It contains the same components as the driver circuit shown in Figure 2 and operates in the same way.

Drive electrode 18 is connected to the inverting input of operational amplifier 35 and resistor 40 .

The column electrodes 16 are connected to the output 35 of the operational amplifier.

The drive circuit 20A is adapted to power each emitter 22 of the circuit 103 intermittently in succession to address the column 21A by passing the circuit I ₂₁ to one of the endpoints of the emitter 22 -modulator 26 string.

The non-inverting input of the operational amplifier 35 is adapted to receive a reference voltage for the emitters 22 of the column 21A, the value of which reference voltage depends on the color of the sub-pixel associated with the emitters 22 of the column.

The display voltage V _data to be addressed to the transmitter 22 is supplied to a resistor 40 . This voltage generates a drive current that is applied to the current-pass electrodes of the switch 106 .

During the refresh phase of addressing circuit 103, row electrode 14 is in logic state 0, whereby switches 28 and 106 are open and switch 108 is closed.

A feedback loop for amplifier 35 is formed by drive electrode 18 , switch 106 , modulator 26 , and switch 28 . This feedback loop allows the current I21A flowing through the drive electrode 18 to be stabilized such that the current satisfies the following equation:

I _21A =(V _21A -V _ref )/R

Amplifier 35 operating in feedback mode compensates the release threshold voltage of the gate of modulator 26 independently of the characteristics of modulator 26 .

The voltage on the gate of modulator 26 is then stored in capacitor 29 .

During the phase of storing current I _21A , row electrode 14 switches to logic state 1, and thus switches 28 and 106 are on, and switch 108 is off.

Advantageously, during the period from the refresh phase to the storage phase, the voltages on the drain electrode, the source electrode, and the gate electrode of the modulator 26 do not change, so the same current flows through the period from the refresh phase to the storage phase. Launcher 22.

Advantageously, this device according to the third embodiment of the invention makes it possible to finally control the current flowing through the emitters 22, thereby generating precise grid scales, uniform brightness and low noise, even at high resolution The same goes for the rate screen.

Advantageously, the time required to program the display device is less than that of a non-feedback display device.

Advantageously, this display device allows a wide spread of characteristics, especially with regard to the valve voltage of the modulator 26 .

Claims (16)

1. An active matrix image display device (1), comprising: - several light emitters (22, 23, 24), forming an array of emitters distributed in rows and columns (21A, 21B), each emitter (22, 23, 24) capable of being displayed the value of a signal (V _data22 , V _data23 ) periodically addressing, this value represents the display data of the image duration (T1, T2, T3, T4); and - a current modulator (26) connected in series to each light emitter (22, 23, 24) of said array to form an emitter-modulator string, said modulator (26) comprising a source, a drain, gate, for voltages between one of the drain and source and the gate greater than or equal to the release threshold voltage (V _th ) of the modulator, drain current can pass through the modulator to the emitter ( 22, 23, 24) power supply; and - a storage capacitor (29) of charge capable of maintaining the control voltage at the gate of each modulator (26) during said image duration (T1, T2, T3, T4); and - selection means (8, 14, 15) capable of selecting emitters (22) of the same row; and - means (20A, 35, 36, 38, 39, 40, 48) for driving said emitters to emit light, comprising, for each column (21A), means for powering these emitters (22, 23, 24) ( 36, 39, 40), the supply means comprising an output (42) connected to one of the terminals (31, 32) of each transmitter-modulator string of said column (21A); and at least one operational amplifier (35) for controlling the corresponding modulator (26), having an inverting input (-), a non-inverting input (+) and an output, when the transmitter (22, 23, 24), the output of the amplifier (35) may be connected to the gate of each modulator (26) of the column (21A), thereby applying the control voltage to the gate; It is characterized in that one of the non-inverting input terminal (+) and the inverting input terminal (-) of the operational amplifier (35) is connected to the output terminal (42) of the power supply device (36, 39, 40), Thus when one of said transmitters (22, 23, 24) is selected, said operational amplifier (35) is formed with the gate of said modulator (26) connected to the output of said operational amplifier (35). ) feedback loop. 2. Apparatus according to claim 1, characterized in that each transmitter-modulator string of said column (21A) is connected to an output (42) of said supply means (36, 39, 40) One of said terminals (31, 32) corresponds to the drain or source of said modulator (26). 3. The device according to claim 1 or 2, characterized in that the non-inverting input (+) and the inverting input (-) of the operational amplifier (35) connected to the output (42) One of them is able to receive a signal dependent on the value (V _data22 , V _data23 ) of the display signal to be addressed to the transmitter ( 22 , 23 , 24 ) selected from said column ( 21A). 4. The device according to any one of claims 1 to 3, characterized in that: said power supply device (36, 39, 40) further comprises a drive generator (36, 39, 40), said drive generator (36, 39, 40) adapted to intermittently succeed nematics ( 21A) to power each emitter (22, 23, 24), the drive signal (In) depends on the value of the display signal (V _data22 , V _data23 ) to be addressed from the column (21A ) selected emitter (22, 23, 24). 5. A device as claimed in claim 4, characterized in that said drive generator (36, 39, 40) comprises a display voltage (V _data22 , V _data23 ) generator (39) and a resistive element (40) connected in series ), and the voltage generator (39) is adapted to generate a voltage dependent on the value (V _data22 , V _data23 ) of the display signal to be addressed to the transmitter selected from said column (21A) (22, 23, 24). 6. The device according to any one of claims 1 to 3, characterized in that: said power supply device (36, 39, 40) further comprises a driving generator (36, 39, 40), said driving generator (36, 39, 40) can be continuously fed to a column (21A) by supplying the same drive signal (I) to one of said endpoints (31, 32) of each transmitter-modulator string of the column (21A) ) powers the entire set of emitters (22, 23, 24) which drive signal (I) depends on the previously addressed and currently addressed column (21A The sum of the values (V _data22 , V _data23 ) of the display signals of the entire set of emitters (22, 23) of ). 7. A device as claimed in claim 6, characterized in that said drive generator (36, 39, 40) comprises a display voltage (V _data22 , V _data23 ) generator (39) and a resistive element (40) connected in series ), and the voltage generator (39) is adapted to generate the entire set of emitters (22, 23 ) shows the voltage of the sum of the signal values (V _data22 , V _data23 ). 8. A device as claimed in claim 7, characterized in that it comprises no switching means between the output of the power supply device and each end point of the transmitter-modulator string of the column. 9. The device according to any one of claims 7 to 8, characterized in that the voltage generator (39) is connected to the resistive element (40) to deliver the drive current (I) obtained on the basis of the following relationship : $\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; p</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; da</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; refn</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}$ Where R is a resistive element (40), V _refn is the reference voltage associated with emitter n, and V _datan is the value of the display voltage addressed to emitter n, and p is the total number of emitters in the column. 10. Apparatus according to any one of the preceding claims, characterized in that said drive means (20A, 35, 36, 38, 39, 40, 48) further comprise a reference generator (38), which A reference signal (V _ref ) can be passed to the other of the inverting (-) and non-inverting (+) inputs of the operational amplifier (35). 11. A device according to claim 10, characterized in that each emitter (22, 23, 24) exhibits specific electrical and/or optical properties, and that the value of each reference signal (V _ref ) depends on on the electrical and/or optical properties. 12. A device as claimed in claim 10 or 11, characterized in that each emitter (22, 23, 24) is associated with a color luminescence and can be assigned to said selected emitter (22, 23 , 24) modulates the reference signal (V _ref ) as a function of the color. 13. The device according to any one of claims 10 to 11, characterized in that the emitters (22, 23, 24) are grouped into groups of adjacent emitters (22, 23, 24), suitable for For each emission of a different color, and for each group, the reference signal (V _ref ) is assigned to the individual emitters of the group in such a way that these emissions are addressed by the same display signal value (V _data22 , V _data23 ). tor causes a white hue to be emitted by the group. 14. The device according to any one of the preceding claims, characterized in that the drive device (20A, 35, 36, 38, 39, 40, 48) further comprises a data storage device (48), the data storage device (48) Being able to store said display signal values (V _data22 , V _data23 ) addressed to each emitter (22, 23) for picture durations (T1, T2, T3, T4). 15. A control method for an active-matrix image display device (1), the active-matrix image display device comprising: several light emitters (22, 23, 24), formed by rows and columns (21A, 21B) array of emitters, each emitter (22, 23) can be addressed periodically by a display signal value (V _data22 , V _data23 ) representing The display data of current modulator (26), comprise source, drain, gate, one in the drain or source of each modulator (26) is connected in series to the emitter (22,23 of said array , 24), thereby forming an emitter-modulator comprising two terminals (31, 32); selection means (8, 14, 15), capable of selecting the emitter row (22); charge storage capacitor (29), capable of Maintain the control voltage at the gate of the or each modulator (26) for the duration of the image (T1, T2); means (20A, 35, 36, 20A, 35, 36, 38, 39, 40, 48) comprising at least one operational amplifier (35) having an inverting input (-), a non-inverting input (+) and an output; the method comprises the steps of: - transmit a selection signal (V _select ) to the emitter (22) row via the selection means; - applying a drive signal (I) to one of the endpoints (31, 32) of each emitter-modulator string of the column (21A) by drive means (20A, 35, 36, 38, 39, 40, 48); - applying a control signal ( _Vc ) to the gate of each modulator (26) connected to the selected emitter (22) by means of driving means (20A, 35, 36, 38, 39, 40, 48), It is characterized in that it also includes the following steps: - select rows of emitters to utilize the gate of said modulator (26) connected to the output of said operational amplifier (35) and to utilize the power supplies (36, 39) connected to these emitters (22, 23) , 40), one of the non-inverting input (+) and inverting input (-) of the operational amplifier (35) of the output (42) to form the feedback loop of the operational amplifier (35) . 16. A method as claimed in claim 15, characterized in that the drive signal (I) depends on the entire set of emitters ( 22, 23) the sum of the display signal values (V _data22 , V _data23 ).

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