CN1702725A - Display - Google Patents

Abstract

This invention provides a long life display apparatus reducing power loss, in which high definition grayscale display is performed by substantially reducing luminance variations for each pixel in a display face of the display apparatus. A display has light emitting elements, a first driver, a power source, and a second driver. Each light emitting element includes three emission layers 3, 6 and 9 formed one over another to form a color dot in each pixel. The first drivers 16a to 16c drives the emission layers to emit light or no light. The power source passes a current through the first driver to the light emitting element. The second driver individually weights the n emission layers and makes the emission layers emit light so that each dot may express a gradation level.

Description

Display device

Technical field

The present invention relates to display device, particularly the display device of the stacked gray shade scale for the multilayer represent images of luminescent layers such as electroluminescent display.

Background technology

Organic electroluminescence display (OLED:organic electro luminescencedisplay), (below, electroluminescence also remember make EL) receives publicity as the display of ultrathin type, high-contrast, high-speed response, big angle of visibility.OLED display has utilized organic compound electricity to be become the electroluminescent phenomenon of light.Also have, adopt the driven with active matrix method, just can under the better state of energy efficiency, use OLED display, thereby can reduce energy loss.Because these advantages, reason, OLED display is expected as follow-on display.

For making OLED display luminous, generally adopt the layer shown in Figure 28 (a), 28 (b) to constitute.The basic layer of Figure 28 (a) expression OLED display constitutes.On glass substrate 40, form anode 41.Anode 41 in order to make light transmission with transparent ITO (Indium Tin Oxide) electrode.The ITO electrode is the oxide of indium and stannum, also is widely used in liquid crystal indicator etc.

On anode 41, form the luminescent layer of forming by organic compound 42 as fluorophor.Low subsystem and the macromolecular material of dividing arranged in the organic material, suitably select according to properties of materials, purposes, autofrettage.On luminescent layer 42, form negative electrode 43.Shown in Figure 28 (a) with precedent in, take out from the light of luminescent layer 42 outputs from the direction of glass substrate 40, thereby negative electrode 43 is to be the electrode of material with metals such as aluminium.

Between power supply 44 anode 41 and negative electrode 43, apply DC voltage, make the hole inject luminescent layer 42, on the other hand, make electronics inject luminescent layer 42 from negative electrode 43 from anode 41.Hole of having injected and electronics become the foment as unsettled higher-energy state in luminescent layer 42 combination again, after this get back to the former ground state that is used as stable low-energy state, and emit energy and luminous at luminescent layer 42 this moment at once.

Figure 28 (b) expression constitutes the OLED display of forming by 5 layers layer.These 5 layers of OLED display shown in Figure 28 (b), are the structures that has stacked gradually anode 46, hole injection layer 47, hole transporting layer 48, luminescent layer 49, electron supplying layer 50, electron injecting layer 51 and negative electrode 52 on glass substrate 45.

Should for taking out the hole easily, be provided with hole injection layer 47 and carry the hole transporting layer 48 in this hole with in the precedent to luminescent layer 49 from anode 46.On the other hand, for taking out electronics easily, be provided with electron injecting layer 51 and effectively to the electron supplying layer 50 of luminescent layer 49 these electronics of conveying from negative electrode 52.

Between power supply 53 anode 46 and negative electrode 52, apply DC voltage, make the hole inject luminescent layer 49 through hole injection layer 47 and hole transporting layer 48 respectively from anode 46.On the other hand, make electronics inject luminescent layer 49 through electron injecting layer 51 and electron supplying layer 50 respectively from negative electrode 52.Hole of having injected and electronics become the foment as unsettled higher-energy state in luminescent layer 49 combination again, after this get back to the former ground state that is used as stable low-energy state, and emit energy and luminous at luminescent layer 49 this moment at once.

Adopt the structure of having shared effect as mentioned above, OLED display will be more effectively luminous.

Layer formation is not limited to the formation shown in Figure 28 (a), 28 (b), also have from 2 layers to 4 layers of structure formation, luminescent layer and characteristic of electrode are cooperated and the employed hole injection layer of independent assortment, hole transporting layer, electron injecting layer, electron supplying layer.And, have the materials with function of hole injection layer and hole transporting layer in the organic material in addition concurrently, multiple choices are arranged.

OLED display as shown in the figure, is the structure that accompanies between anode 41,46 and negative electrode 43,52 as the luminescent layer 42,49 of the fluorophor of organic compound, and the luminescent layer 42,49 that this quilt clips is luminous.

Figure 29 represents the cut-open view of an example of the pixel structure in the former display device.On glass substrate 54, formed silicon oxide film 55 and thin film transistor (TFT) (TFT) 59.Silicon oxide film 55 has the function that metallic ion is not moved from glass substrate 54 anode 56, and TFT59 has the function of the luminous conduction and cut-off of the pixel of making.On silicon oxide film 55, form anode 56, on it, formed organic membrane luminescent layer 57.Organic membrane luminescent layer 57 is combined by luminescent layer, hole injection layer, hole transporting layer, electron injecting layer and electron supplying layer.

And, on organic membrane luminescent layer 57, formed negative electrode 58.Negative electrode 58 has adopted metals such as aluminium.Shown here is to go out from the lower light taking-up structure of the light of organic membrane luminescent layer 57 outputs from glass substrate 54 1 side-draws with TFT59 with precedent.

In addition, in order to improve luminescence efficiency, during from negative electrode 58 1 side-draw bright dippings, negative electrode 58 uses transparent ITO.Be called top light and take out structure.

Be reality show image on display, developed multiple pixel drive method.The most general method is in order to realize the gray shade scale driving, to carry analog memory and voltage-to-current translation circuit in pixel, with the corresponding method of controlling the drive current of organic EL of voltage of analog memory.Figure 30 represents an example of the display panel of this gray shade scale driving method.

Figure 30 represents to be used to drive the pie graph of an example of the display panel drive of the pixel 67 that is made of organic EL described later and active component.Dispose a plurality of pixels 67 by two-dimensional-matrix-like on the display panel.

On the display panel,, has horizontal driver 68 for driving the pixel of horizontal direction.Power circuit 69 provides supply voltage to all pixels 67.Driving for the pixel 67 of arranging in vertical direction has vertical driver 70.For example, in the occasion of the display line that will scan higher level, just the voltage that is provided by the display line of the higher level in the display line of the horizontal direction that is connected with vertical driver 70 makes the conducting respectively of each pixel by the gate drivers 65 (illustrating among Figure 31) that is located in the vertical driver 70.Also have, meanwhile, the display line output of the voltage that vertical driver 70 ends the gate drivers 65 of each pixel 67 on the display line beyond the display line that makes higher level beyond higher level's display line.

At this moment, from the vision signal corresponding voltage of horizontal driver 68 output, on the capacitor 62 of each pixel 67 of higher level's display line, add data voltage with 1 sweep trace (display line).Apply power supply and data voltage at the two ends of capacitor 62 like this, keep this potential difference (PD), just can put aside sufficient charge.That is, capacitor 62 is write, has stored video data.After this, if vertical driver 70 is ended, organic EL shows the image of 1 sweep trace with regard to the data of having stored in the capacitor 62 according to each pixel 67 of higher level's display line and luminous.Then same, drive vertical driver 70 in from top to bottom direction order with each display line unit, and synchronous with it, by per 1 line image output data, just can scan all interior pixels 67 of display panel from horizontal driver 68

Figure 31 represents the circuit diagram of each pixel 67.Organic EL60 is equivalent to the organic membrane luminescent layer 57 of Figure 29.Determine the data of the luminosity of organic EL60 to import from data input pin 64.The grid of 65 couples of TFT61 of gate drivers adds voltage herein, makes the TFT61 conducting, and the data of having imported on the terminal 64 are the grid that puts on capacitor 62 and TFT63 respectively of source electrode and the drain electrode by TFT61 just.The electric current that provides to organic EL60 between source electrode by TFT63 and drain electrode is provided according to this current potential.

After this, TFT61 is ended, the potential difference (PD) that power supply 66 and data input pin are 64 is just stored by capacitor 62.Organic EL60 is as the galvanoluminescence device, just with luminous with the proportional brightness of added electric current.Thereby the luminous brightness of organic EL60 depends on the current potential by the data of terminal 64 inputs, can be by the gray shade scale of this data performance to the image of display device output.

Figure 29 represents the picture layer structure of former display device, and Figure 31 represents to be used for to drive with the gray shade scale driving method its circuit, and but, driving method can be considered other the whole bag of tricks.For example, have with clamp inverter (CLAMPED INVERTER) method (for example, with reference to non-patent literature 1) of pulse-length modulation (PWM) signal carrying out analog-modulated between the light emission period in 1 frame.This method can compensate the deviation that belongs to as the threshold value of the element characteristic of the TFT of active component, and the quantity of TFT is also few, thereby circuit constitutes also simple.Also have, owing to exist between no light emission period, thereby have interrupted animation display.

In the numeral display drive method, organic EL is controlled by the switching transistor of pixel, becomes and lights or certain state of non-illuminating state.As one of this mode, the handlebar image is divided into a plurality of subframes at time-axis direction, expresses the method (for example, with reference to patent documentation 1) of gray shade scale with the weighted sum of subframe.

Also having in the display surface of display device pixel segmentation is a plurality of secondary image elements, comes the area split plot design (for example, with reference to patent documentation 2) of representing gradation grade with the luminous number of this pixel.Have again, as the mode that adopts same secondary image element, the 1st secondary image element is carried out analog-driven control, the multi-grayscale that comprises middle gray with demonstration, the 2nd secondary image element is carried out drive controlling, to show obviously or to show slinkingly that the method that 2 values shown show is known (for example, with reference to patent documentation 3).

Non-patent literature 1:An Innovative Pixel-Driving Scheme for 64-LevelGray Scale Full-Color Active Matrix OLED Displays, SID2002,32.2

Patent documentation 1: the spy opens flat 10-214060 communique

Patent documentation 2: the spy opens flat 11-073159 communique

Patent documentation 3: the spy opens the 2003-280593 communique

Summary of the invention

The problem that solution is planned in invention

According to circuit diagram shown in Figure 31, drive the former display device of each pixel with the gray shade scale driving method, in order to realize that gray shade scale drives, analog memory and voltage-to-current translation circuit have been carried in the pixel, and the drive current of control organic EL corresponding with the voltage of analog memory., have big deviation for every pixel, thereby deviation will take place in the magnitude of current that flows through organic luminous layer as the element characteristic of the TFT of active component.Therefore the deviation of every pixel luminosity becomes big, and the display brightness of device displaying result is just inhomogeneous, the raising difficulty of image quality.

The former display device of this having been carried out the clamp inverter method of non-patent literature 1 record that improves is with the device of effective driving method action for the deviation of eliminating TFT.Only control TFT, control (PWM) between light emission period with analog pulse width with conduction and cut-off, thus the representing gradation grade, adopt this simulation luminous during modulation system move, thereby can reduce the influence of the deviation of TFT., adopt the former display device of this driving method, the magnitude of current corresponding with luminosity all flows through 1 luminescent layer, thereby burden is big, and be unfavorable for long lifetime.And, every gray shade scale all have luminous and non-luminous during, thereby can predict problems such as flicker can take place.

Also having, in the display device before the digital drive method of the subframe method that adopts patent documentation 2 records, is the deviation of eliminating display brightness, the organic EL of pixel is carried out the 2 values driving of conduction and cut-off.Also have, be to obtain gray shade scale and drive, 1 frame time is divided into a plurality of subframes during, during every subframe, scan all pixels, the 2 value video datas that the bit of each gray shade scale is constituted write pixel, carry out the stipulated time by the brightness of every gray shade scale regulation and light during showing., in the display device before the digital drive method that adopts this subframe method, though the effect of the deviation of eliminating TFT is arranged, but, the problem of the interference of the doubtful profile of animation etc. can take place simultaneously.

Have again, in the display device before the area split plot design that adopts patent documentation 3 records, need a plurality of secondary image elements, the trend of the high resolving powerization of the panel that is not suitable for envisioning from now on for constituting a pixel.

The present invention in view of above some and propose, purpose is to provide the deviation of brightness of the every pixel in the display surface that is reduced in display device significantly, realizes that high-precision gray shade scale shows, and reduces electrical piano power loss, long-life display device.

Be used to solve the device of problem

For solving above-mentioned problem, the invention provides the display device of following (a)～(i).

(a) a kind of display device constitutes 1 pixel by the point of a plurality of looks, is arranged with a plurality of pixels, it is characterized in that having: stacked n (n is the natural number more than 2) luminescent layer (3,6,9) forms the light-emitting component of each point; Drive a said n luminescent layer of above-mentioned light-emitting component, make its luminous or non-luminous the 1st drive division (16a～16c); Make electric current flow through the power supply (38) of above-mentioned light-emitting component by above-mentioned the 1st drive division; And, under the state of the weighting of a said n luminescent layer having been set luminosity, drive a said n luminescent layer, make it luminous, thereby show the 2nd drive division (37,39) of the gray shade scale of above-mentioned each point.

(b) display device of putting down in writing according to (a), it is characterized in that, a said n luminescent layer is flow through the time length of above-mentioned electric current to above-mentioned the 2nd drive division handle and the side in the current value is set at same value, the opposing party is set at the value of m kind (m is the following natural number of n), thereby sets the weighting of m kind.

According to the display device of (a) record, it is characterized in that (c) above-mentioned the 2nd drive division is set at the value of m kind (m is the following natural number of n) to the combination of time length that a said n luminescent layer is flow through above-mentioned electric current and current value, thereby set the weighting of m kind.

(d) display device of putting down in writing according to (b), it is characterized in that, above-mentioned the 2nd drive division switches respectively the weighting of a said n luminescent layer with a frame or unit, makes at least one side circulation primary during n frame or n field of the time length of the current value of above-mentioned m kind and above-mentioned m kind.

According to the display device of (c) record, it is characterized in that (e) above-mentioned the 2nd drive division switches respectively the weighting of a said n luminescent layer with a frame or unit, make above-mentioned m kind be combined in n frame or n field during circulation primary.

(f) according to the display device of (a) record, it is characterized in that above-mentioned the 2nd drive division has: the m on the said n luminescent layer (m is the following natural number of n) luminescent layer carried out the digital drive portion of digital drive; And, (n-m) individual luminescent layer is carried out analog-driven, make it come luminous analog-driven portion with the middle gray level.

(g) display device of putting down in writing according to (f), it is characterized in that, above-mentioned digital drive portion sets the weighting of the kind below the above-mentioned m to an above-mentioned m luminescent layer, above-mentioned analog-driven portion sets above-mentioned (n-m) individual luminescent layer and makes it luminous with an above-mentioned m luminescent layer, thus the weighting that shows the gray shade scale of above-mentioned each point.

(h) a kind of display device, point by a plurality of looks constitutes 1 pixel, be arranged with a plurality of pixels, it is characterized in that, have: stacked n (n is the natural number more than 2) unit element forms the light-emitting component of each point, wherein, described unit element stacks gradually anode (402), illuminating part, negative electrode (410) and forms, and described illuminating part is by the organic membrane luminescent layer (403,405,407,409) of m layer (m is a natural number) and (m-1) the alternately laminated multi-photon structure that forms of charge generating layers (404,406,408) of layer; Drive above-mentioned illuminating part, make its luminous or non-luminous the 1st drive division (458); And, under the state of the weighting of the luminescent layer of the n on the above-mentioned light-emitting component having been set luminosity, drive a said n illuminating part, make it luminous, thereby show the 2nd drive division (457,459) of the gray shade scale of above-mentioned each point.

(i) according to the display device of (h) record, it is characterized in that, be clipped in 2 layers of above-mentioned charge generating layers between the above-mentioned organic membrane luminescent layer and inject electronics, to the opposing party's organic membrane luminescent layer injected hole to side's organic membrane luminescent layer.

The effect of invention

Can realize to reduce significantly the deviation of the brightness of the every pixel in the display surface of display device, realize that high-precision gray shade scale shows and reduces electrical piano power loss, long-life display device.

Also have, light-emitting component carried out digital drive, carry out the gray shade scale performance of 1 point with the weighted sum of brightness, thus can be under the state of the threshold deviation influence that does not have the 1st drive division driven light-emitting element.Therefore, the uneven luminance on the display device can be eliminated, power attenuation can also be reduced.

Also have, the magnitude of current corresponding with luminosity all do not flow through 1 luminescent layer, thereby the burden that can disperse each luminescent layer, and compares in the past, can realize more long-life display device.

Have again, make the gray shade scale of carrying out 1 point show with the summation of the luminosity of n luminescent layer, thereby with 1 luminescent layer in flow through the formation of all corresponding magnitude of current with luminosity former display device compare, can constitute long-life display device.

Description of drawings

Fig. 1 is the figure that the layer of the pixel in the display device of expression first embodiment constitutes.

Fig. 2 is the figure of the pixel structure of expression first embodiment.

Fig. 3 is that expression organic membrane luminescent layer is the figure of a luminance weighted example of each layer of each occasion of 3 layers of structure and 5 layers of structure.

Fig. 4 is the figure of an example of the gray shade scale performance method in the expression display device of the present invention.

Fig. 5 is the figure that the driver of the display panel of expression first embodiment constitutes.

Fig. 6 is the circuit diagram that expression is used to drive the pixel of first embodiment.

Fig. 7 is the figure that the driver of the display panel of expression second embodiment constitutes.

Fig. 8 is the circuit diagram that expression is used to drive the pixel of second embodiment.

Fig. 9 is the figure of the relation of expression frame signal and current value switching signal.

Figure 10 is the figure of complete list of gray shade scale performance method of every frame of the expression display device that is used for illustrating second embodiment.

Figure 11 is the timing diagram of the 5th embodiment.

Figure 12 is the timing diagram of the 6th embodiment.

Figure 13 is the timing diagram of the 7th embodiment.

Figure 14 is the figure that the layer of the pixel in the display device of expression the 3rd embodiment constitutes.

Figure 15 is the figure of the pixel structure of expression the 3rd embodiment.

Figure 16 is the figure that the driver of the display panel of expression the 3rd embodiment constitutes.

Figure 17 is the circuit diagram that expression is used to drive the pixel of the 3rd embodiment.

Figure 18 is the key diagram of first embodiment of gray shade scale performance method.

Figure 19 is the key diagram of second embodiment of gray shade scale performance method.

Figure 20 is the key diagram of the 3rd embodiment of gray shade scale performance method.

Figure 21 is the key diagram of the 4th embodiment of gray shade scale performance method.

Figure 22 is the figure that the layer of the pixel in the display device of expression the 4th embodiment constitutes.

Figure 23 is the figure of the principle of work of expression multi-photon.

Figure 24 is the figure of formation of the pixel of expression the 4th embodiment.

Figure 25 is the figure of the pixel structure of expression the 4th embodiment.

Figure 26 is the figure that the driver of the display panel of expression the 4th embodiment constitutes.

Figure 27 is the circuit diagram that expression is used to drive the pixel of the 4th embodiment.

Figure 28 is the basic layer formation of expression OLED display and the figure of 5 layers of formation.

Figure 29 is the cut-open view of an example of the pixel structure in the expression display device in the past.

Figure 30 is the figure of an example of the panel driver formation in the expression display device in the past.

Figure 31 is the figure of an example of the driving circuit in the expression display device in the past.

Embodiment

" first embodiment "

Fig. 1 represents that the layer of the pixel of the display device in first embodiment of the present invention constitutes.Display device for example is an OLED display.Glass substrate 1 is the display surface of display device.This glass substrate 1 if can form the layer of organic membrane, also can be the substrate of plastics one class.On this glass substrate 1, formed anode 2.As this anode 2, for example can use ITO as transparency electrode etc.

On anode 2, formed organic membrane luminescent layer 3.Organic membrane luminescent layer 3 constitutes with hole injection layer, hole transporting layer, electron injecting layer, electron supplying layer and by the combination as the luminescent layer of fluorophor that organic compound is formed.This combination must suitably be selected according to the characteristic of organic EL.

On organic membrane luminescent layer 3, formed negative electrode 4.As negative electrode 4, if use ITO, just can not directly move, thereby must between ITO and organic membrane luminescent layer 3, insert lithium that negative electrode uses etc. thinly as negative electrode as transparency electrode.

Power supply 13 connects for apply DC voltage between anode 2 and negative electrode 4.The principle of luminosity that is clipped in the organic membrane luminescent layer 3 between anode 2 and the negative electrode 4 is with identical with precedent.

On negative electrode 4, stack gradually and formed silicon oxide film 11 and anode 5.Silicon oxide film 11 has the effect that makes anode 5 and negative electrode 4 insulation.

Same as described above on anode 5, stack gradually and form organic membrane luminescent layer 6, negative electrode 7, silicon oxide film 12, anode 8, organic membrane luminescent layer 9 and negative electrode 10.As first embodiment, be that negative electrode 10 is metals such as aluminium not from the lower light taking-up structure of negative electrode 10 1 side-draw bright dippings.

Power supply 14,15 for respectively between anode 5 and the negative electrode 7, apply DC voltage between anode 8 and the negative electrode 10 and connect.Like this, just offer organic membrane luminescent layer 6,9 by power supply 14,15 from the electric current that anode 5,8 and negative electrode 7,10 are transformed into.

Each organic membrane luminescent layer 3,6,9 with the proportional brightness of the current value that is transformed into and luminous, light goes out from glass substrate 1 one side-draws.In addition, this structure is not limited to organic EL, and inorganic EL realizes certainly that also be not limited to active driving, the display device of passive drive also can realize.

Organic membrane luminescent layer 3,6,9 is that 2 values of the conduction and cut-off of power supply are switched light and turn off the light (luminous or not luminous) by digital drive.Organic membrane luminescent layer 3,6,9 is selected respectively to form with the luminous material of brightness of regulation.

Fig. 2 represents the pixel structure as the display device of first embodiment of the present invention.In Fig. 2, the component part identical with Fig. 1 paid with same-sign, omits this explanation.Fig. 2 represents to constitute 1 point in (for example red, green, blue etc.) of all kinds of 1 pixel., on glass substrate 1, formed thin film transistor (TFT) (TFT) 16a, 16b, 16c herein, be connected with anode 2,5,8 respectively as active component.As long as TFT16a～16c can drive controlling organic membrane luminescent layer 3,6,9, of which kind of active component of p-Si (the many silicon of low temperature), a-Si (amorphous silicon) etc. making can.

TFT16a～16c has the circuit function that makes the power turn-on that applies to organic membrane luminescent layer 3,6,9/end, and as mentioned above, by making power turn-on/end driving organic membrane luminescent layer 3,6,9, makes it luminous or not luminous.Also have, the silicon oxide film 17 that forms between glass substrate 1 and anode 2 is films that metallic ion is not moved from glass substrate 1 anode 2.Negative electrode 4, negative electrode 7, negative electrode 10 are common electrodes.

In occasion from the glass substrate 1 one side-draw bright dippings of the downside of pixel shown in Figure 2, do not leak for making light from negative electrode 10 as the upside of pixel, metals such as negative electrode 10 usefulness aluminium form.Like this, from organic membrane luminescent layer 3,6, the 9 just radiation up and down of light of outgoing respectively, but, to the light of negative electrode 10 1 side outgoing by negative electrode 10 reflections towards downside, thereby just only be removed from glass substrate 1 one sides.

In addition, in the present embodiment, has TFT16a～16c on the glass substrate 1, be lower light taking-up structure, but, also can make with transparency electrode and form negative electrode 10 from glass substrate 1 one side-draw bright dippings, form anode 2 with metals such as aluminium, light takes out structure above negative electrode 10 1 side-draw bright dippings.

Herein, TFT16a～16c is necessary for a plurality of usually.TFT16a～16c is called element drives portion (the 1st drive division) herein.Organic membrane luminescent layer and element drives portion are unit element.OLED display shown in Figure 2 is the light-emitting component that has 3 layers of structure that 3 luminescent layers are laminated in the display surface vertical direction to display device.

Fig. 3 (a) expression as depicted in figs. 1 and 2, pixel is each layer luminance weighted of occasion with 3 layers of structure of organic membrane luminescent layer 3,6,9.Luminance weightedly be meant that with certain value be benchmark, the luminosity relative number value of each organic membrane luminescent layer value.This is in organic membrane luminescent layer 3 as the 1st layer, and organic membrane luminescent layer 6 is as the 2nd layer, and organic membrane luminescent layer 9 is as the 3rd layer, when the 1st layer brightness is made as " 1 ", select organic membrane luminescent layer 3,6,9 materials, formation, make the 2nd layer to be brightness " 2 ", the 3rd layer is brightness " 4 ".

Herein, the luminosity when the supply voltage conducting is represented in the brightness of each organic membrane luminescent layer 3,6,9 comes each organic membrane luminescent layer 3,6,9 is carried out digital drive by the conduction and cut-off of supply voltage.

Fig. 3 (b) expression organic membrane luminescent layer is the luminance weighted example of each layer of the occasion of 5 layers of structure.In the occasion of 5 layers of structure, in structure illustrated in figures 1 and 2,2 unit elements are set again.These 5 organic membrane luminescent layers are the 1st layer, the 2nd layer, the 3rd layer, the 4th layer and the 5th layer from a side of the side that close light is removed in order, when the 1st layer brightness was made as " 1 ", the 2nd layer was brightness " 2 ", and the 3rd layer is brightness " 4 ", the 4th layer is brightness " 8 ", and the 5th layer is brightness " 16 ".

Organic membrane luminescent layer luminance weighted shown in Fig. 3 (a), 3 (b) preferably, carries out 2 the luminance weighted of n power and just can form the organic membrane luminescent layer less, but, is not so limited.Also have, the weighting of every layer brightness needn't come ascending order by the layer near a side of taking out light shown in Fig. 3 (a), 3 (b), but can change descending into, or arrange arbitrarily.In addition, this luminance weighted method is not limited to organic EL, and inorganic EL realizes certainly that also be not limited to active driving, the display device of passive drive also can realize.

Fig. 4 represents an example of the gray shade scale performance of the pixel in the display device of first embodiment of the present invention.This example is that the organic membrane luminescent layer shown in Fig. 3 (a) is the luminance weighted gray shade scale performance of the occasion of 3 layers of structure, and the organic membrane luminescent layer is 3 layers, can be used as 2 the i.e. performance of 8 gray shade scales of 3 powers.In Fig. 4, transverse axis represents which layer the organic membrane luminescent layer is, the longitudinal axis is illustrated in gray-scale displayed grade on the display device.Also have, bullet means that its layer of having selected lights, and does not have the layer of mark not luminous.

For example, when gray shade scale was " 0 ", the 1st layer, layers 2 and 3 were not luminous.Therefore for black.When gray shade scale is " 1 ", only light for the 1st layer, it is luminance weighted to be " 1 ", thereby expression gray shade scale " 1 ".When gray shade scale is " 2 ", only light for the 2nd layer, it is luminance weighted to be " 2 ", thereby expression gray shade scale " 2 ".When gray shade scale was " 3 ", layers 1 and 2 was together lighted, and each is luminance weighted to be " 1 ", " 2 ", and its summation " 3 " is a gray shade scale.When gray shade scale is " 4 ", only light for the 3rd layer, it is luminance weighted to be " 4 ", thereby expression gray shade scale " 4 ".

When gray shade scale was " 5 ", the 1st layer and the 3rd layer were together luminous, and each is luminance weighted to be " 1 " and " 4 ", and its summation " 5 " is a gray shade scale.When gray shade scale was " 6 ", layers 2 and 3 was together luminous, and each is luminance weighted to be " 2 " and " 4 ", and its summation " 6 " is a gray shade scale.When gray shade scale was " 7 ", the 1st layer, layers 2 and 3 were all lighted, and the summation " 7 " of its luminance weighted " 1 ", " 2 ", " 4 " is a gray shade scale.

Fig. 5 represents the driver pie graph of display panel of the display device of first embodiment of the present invention.In Fig. 5, a pixel 36 is equivalent to image element circuit described later among Fig. 6.Have on the display panel be used for to a plurality of pixels 36 that are configured to two-dimensional-matrix-like send data horizontal driver 37, be used to drive the power circuit 38 of pixel and the vertical driver 39 of selecting the line of vertical direction.In addition, herein horizontal driver 37 and vertical driver 39 as the 2nd drive division.

A plurality of pixels 36 are configured to the two-dimensional-matrix-like that the row X by capable Y that arranges in vertical direction and arrangement in the horizontal direction forms.As an example, 4 of expression Y1～Y4 goes, the display panels of 6 row of X1～X6 among Fig. 5.Actual display panel is more than ranks shown in Figure 5, but, and expression for convenience and so herein.

In first embodiment, assemble data driver 371～376 in the horizontal driver 37, assembled power supply unit 381～386 in the power circuit 38, assembled gate drivers 391～394 in the vertical driver 39.

For example, in the occasion that will scan as the capable display line of the higher level's of display panel shown in Figure 5 Y1, the gate drivers 391 of vertical driver 39 makes capable each pixel 36 conducting of Y1.Other display line Y2 is capable～and Y4 is capable to be ended by gate drivers 392～394.Offer each pixel 36 from the data of 1 line of horizontal driver 37 image output data this moment.

Secondly, gate drivers 391 ends each capable pixel 36 of Y1, thereby shows the image of 1 line that Y1 is capable.Then same, gate drivers 392 to Y4 capable gate drivers 394 orders that Y2 is capable drive vertical driver 39, press per 1 line image output data from horizontal driver 37, thereby just can scan the pixel 36 in all display panels.

Fig. 6 represents to be used to drive the circuit diagram of the pixel of first embodiment.In Fig. 6, organic EL luminescent layer 18,19,20 is equivalent to organic membrane luminescent layer illustrated in figures 1 and 23,6,9.

The pixel 36 of first embodiment forms organic EL luminescent layer 18,19,20 (organic membrane luminescent layer 3,6,9) with luminosity material inequality respectively, carries out the weighting shown in Fig. 3 (a) with this.Therefore the time of flowing through the electric current of organic EL luminescent layer 18,19,20 respectively and flowing through is identical.

Each end (being anode among the figure) of organic EL luminescent layer 18～20 is connected with the power supply 30～32 that constitutes power supply unit 381 by driving each source electrode, the drain electrode with TFT24～26.Also have, each grid of TFT24～26 is connected with each source electrode as TFT27～29 of gate transistor, passes through capacitor 21～23 on the other hand and is connected with power supply 30～32.

The power supply 30,31 and 32 of power supply unit 381 is equivalent to power supply shown in Figure 1 13,14 and 15.Power supply 30～32 can be an independent current source, can be common source also, sets organic EL luminescent layer 18～20, makes its weighting with regulation, in accordance with regulations brightness luminous.And each drain electrode of TFT27～29 is connected with the data maintaining part 350～352 in the data driver 371, and each grid and gate drivers 391 connect altogether.

, represented data driver 371, power supply unit 381, gate drivers 391 herein, but, as shown in Figure 6, data driver 372～376, power supply unit 382～386, gate drivers 392～394 also are identical formations.Data driver 371～376, power supply unit 381～386, gate drivers 391～394 drive each row Y of display panels, respectively are listed as the pixel 36 of X.

Secondly, the action of this driving circuit is described.In Fig. 6, at first, the data 33 (3 bit) of the regulation gray shade scale that shows on the pixel 36 input data driver 371.Data 33 are the serial data or the parallel data of numeral preferably.The data of having been imported by data driver 371 33 are used for making the corresponding organic EL luminescent layer of gray-scale displayed grade on the display device with organic EL luminescent layer 18,19,20 luminous.

Each bit of data 33 (1 or 0) is kept by data maintaining part 350～352, and the grid of 391 pairs of gate transistors 27～29 of gate drivers applies the 1st current potential of regulation, makes it become conducting state.From the data of data driver 371 output each drain electrode, source electrode, give capacitor 21～23 by gate transistor 27～29.Like this, power supply and data voltage are applied to the two ends of capacitor 21～23, keep this potential difference (PD), to put aside sufficient charge on capacitor 21～23.That is, the video data from data driver 371 outputs writes, is stored in the capacitor 21～23 that is used for the data maintenance.Then, the grid of 391 pairs of gate transistors 27～29 of gate drivers applies the 2nd current potential of regulation, makes it become cut-off state.Gate transistor 27～29 is ended, and the electric charge of having put aside on capacitor 21～23 just is held.The electric charge that is kept by capacitor 21～23 is the potential difference (PD) of the output voltage of power supply 30～32 and data driver 371.

Following illustrative examples is as the situation of the image of display gray scale grade " 5 " on display device.With reference to Fig. 4, gray shade scale " 5 " need make organic EL luminescent layer 18 and 20 of the 1st layer and the 3rd layer light.The data of having imported 33 are transformed to the relevant data rows of signal wire with corresponding organic EL luminescent layer by data driver 371, in this occasion, keep making organic EL luminescent layer 18 and 20 luminous data in the data maintaining part 350 and 352.

Apply the voltage that makes TFT24 conducting on the capacitor 21 this moment, also apply the voltage that makes the TFT26 conducting on the capacitor 23, thereby TFT24 and 26 becomes conducting state respectively.On the other hand, do not apply the voltage of drive TFT 25 on the capacitor 22, thereby TFT25 is a cut-off state.

Therefore, TFT24 and 26 is a conducting state, thus from power supply 30,32 by TFT24, each drain electrode of 26, source electrode provides electric current to organic EL luminescent layer 18,20, organic EL luminescent layer 18,20 will be luminous.Being weighted to of organic EL luminescent layer 18 and 20 luminosity this moment " 1 " and " 4 ", thereby just on display device, shown as the gray shade scale " 5 " of its summation.

In the driving of the pixel of first embodiment, drive and only carry out the action of conduction and cut-off with TFT24～26.Therefore circuit constitutes as shown in Figure 6, adopts savings to be used to make to drive with the capacitor 21～23 of the data of TFT24～26 conduction and cut-off and is used to keep the very simple circuit formation of its gate transistor 27～29 to get final product.

Also have, drive with TFT24～26 and only carry out the conduction and cut-off action, thereby move the zone of saturation that the caused threshold deviation of element characteristic of the problematic TFT as active component of organic EL display that can be former does not have to influence.Therefore, can infinitely reduce the interior problems such as the not even gray shade scale deviation of display brightness of display panel.And the electric power loss of TFT is few, thus the action of zone of saturation with compare with precedent, can reduce consumption of electric power.

Have, in the first embodiment, the electric current that provides to organic EL is disperseed by a plurality of luminescent layers again.2 powers that it is generally acknowledged the life-span of organic EL and current value are inversely proportional.Electric current can be reduced the magnitude of current of each layer by a plurality of layers of dispersion, thereby compares with former circuit formation, can life-saving.

" second embodiment "

Secondly, pixel in the display device of second embodiment of the present invention is described in detail in detail.In above-mentioned first embodiment, each organic membrane luminescent layer adopts the brightness with regulation to resemble luminous different material formation, carries out luminance weighted.In second embodiment, each organic membrane luminescent layer forms with identical materials, makes current value that gives each organic membrane luminescent layer and the asynchronism(-nization) that gives electric current, thereby the brightness of realization regulation is luminous.Below, the concrete formation of second embodiment is described in detail in detail and as the luminance weighted method of first embodiment to the, seven embodiment of the suitable embodiment of second embodiment.

The layer formation of pixel, pixel are constructed identical with the pixel of first embodiment illustrated in figures 1 and 2, thereby omit this explanation.Also have, the luminance weighted of each layer carries out according to Fig. 3 (a), and the gray shade scale performance is carried out according to Fig. 4.

Fig. 7 represents the driver pie graph of display panel of the display device of second embodiment of the present invention.In Fig. 7, a pixel 362 is equivalent to the image element circuit of Fig. 8 described later.In Fig. 7, the component part identical with Fig. 5 paid with same-sign, omits this explanation.Newly established on the display panel of second embodiment data driver 371 '～376 in time length control part 800, the horizontal driver 37 ', power supply unit 381 '～386 in the current control division 900, power circuit 38 '.

Fig. 8 represents to drive the circuit of the pixel 362 of second embodiment.In Fig. 8, the component part identical with Fig. 6 paid with same-sign, omits this explanation.

Be arranged in the time length complete list maintaining part 80 retention time length complete list of time length control part 800, time length control signal generating unit 81 bases are from the time length data that time length complete list is read, to selector switch control part 82 output time length control signals.Switching signal generating unit 820～822 according to time length control signal come switch data driver 371 ' in selector switch 830～832 selected terminal a, b.Each terminal a of selector switch 830～832 goes up each bit of input data 33, terminal b ground connection and import 0.In addition, the configuration that the data maintaining part represented among data driver 371 ' had before terminal a and Fig. 6 350～352 is equal.

Be arranged in the current value complete list maintaining part 90 holding current value complete lists of current control division 900, current controling signal generating unit 91 is according to the current value data of reading from the current value complete list, from the current value switching signal Si0～Si2 of current value switching signal generating unit 910～912 each bit of output.Also have, input has the frame signal Sf that becomes the frame-synchronizing impulse of high level in the front of each frame in the current switching signal generation 91.As shown in Figure 9, current value switching signal Si0～Si2 and frame signal Sf are switched synchronously.Current value switching signal generating unit 910～912 with constitute power supply unit 381 ' variable device 330～332 be connected respectively, variable device 330～332 comes the switch current value according to current value switching signal Si0～Si2 respectively.The electric current that provides from power supply 30～32 is provided variable device 330～332, and the electric current of predetermined electric current value is provided to organic EL luminescent layer 18～20 respectively.

In addition, time length complete list maintaining part 80 has been located in the time length control part 800 herein, current value complete list maintaining part 90 has been located in the current control division 900, but be not so limited, also can be located at time length complete list maintaining part 80 and current value complete list maintaining part 90 in the same memory storage.

Have again, represented herein data driver 371 ', power supply unit 381 ', gate drivers 391, but, as shown in Figure 8, data driver 372 '～376 ', power supply unit 382 '～386 ', gate drivers 392～394 also is identical formation.Data driver 371 '～376 ', power supply unit 381 '～386 ', gate drivers 391～394 drives each row Y of display panels, respectively is listed as the pixel 362 of X.

Herein, among all embodiment, each organic EL luminescent layer 18～20 luminous luminosity can be pressed " 1 ", " 2 " respectively, " 4 " come weighting, if not record especially, what weighting referred to is exactly this point.Also have, during display brightness weighting " 1 ", the electric current that flows to TFT24 from power supply 30 is made as I1 on organic EL luminescent layer 18, and the time of TFT24 conducting is made as T1.Equally, on organic EL luminescent layer 19 during display brightness weighting " 2 ", the electric current that flows to TFT25 from power supply 31 is made as I2, the time of TFT25 conducting is made as T2, on organic EL luminescent layer 20 during display brightness weighting " 4 ", the electric current that flows to TFT26 from power supply 32 is made as I3, and the time of TFT26 conducting is made as T3.

(first embodiment of weighting)

At first represent to flow through different current values respectively and the example of weighting to organic EL luminescent layer 18,19,20.The time of TFT24～26 conductings is T1=T2=T3=t.

Herein, the current value that flows to the electric current I 1 of organic EL luminescent layer 18 is made as i, and the current value that flows to the electric current I 2 of organic EL luminescent layer 19 is made as 2i, and the current value that flows to the electric current I 3 of organic EL luminescent layer 20 is made as 4i.The current value of having set like this is by power supply unit 381 in current control division 900 and the power circuit 38 ' provide.

In addition, flowing to the current value of organic EL luminescent layer 18～20 and time length multiplies each other and just becomes the luminance weighted of each layer.

(second embodiment of weighting)

Secondly expression is flow through the electric current of identical current value and the example of weighting with different time length respectively to organic EL luminescent layer 18,19,20.The current value that flows to organic EL luminescent layer 18～20 equates respectively, is I1=I2=I3=i.

Herein, the time length of the time T 1 that organic EL luminescent layer 18 is lighted is made as t, and the time length of the time T 2 that organic EL luminescent layer 19 is lighted is made as 2t, and the time length of the time T 3 that organic EL luminescent layer 20 is lighted is made as 4t.In time length control part 800, set each time length data like this.

Among first embodiment and second embodiment, as method to the weighting of the luminosity of organic EL luminescent layer 18～20, illustrated with the identical time and flow through the method for different current values and the method that flows through the electric current of identical current value respectively with different time length respectively, but, be not so limited, also can be as the 3rd embodiment described later, the 4th embodiment, shared 2 methods.

(the 3rd embodiment of weighting)

Then represent the example that current value and time length are all differently set respectively.The electric current I 1 that flows to organic EL luminescent layer 18 is made as current value i, the time T of lighting 1 is made as time length t, the electric current I 2 that flows to organic EL luminescent layer 18 is made as current value (3/2) i, light time T 2 be made as time length (4/3) t, the electric current I 3 that flows to organic EL luminescent layer 20 is made as current value 2i, and the time T of lighting 3 is made as time length 2t.

(the 4th embodiment of weighting)

As another example of shared 2 methods, the example that expression current value and time length are partly differently set respectively.For example, the electric current I 1 that flows to organic EL luminescent layer 18 is made as current value i, the time T of lighting 1 is made as time length t, the electric current I 2 that flows to organic EL luminescent layer 19 is made as current value i, the time T of lighting 2 is made as time length 2t, the electric current I 3 that flows to organic EL luminescent layer 20 is made as current value 2i, and the time T of lighting 3 is made as time length 2t.

Secondly, illustrate and further improve above-mentioned first embodiment～the 4th embodiment, current value and fluorescent lifetime length are differently set by every luminescent layer, and make the current value between each luminescent layer and the method for fluorescent lifetime length equalization at the appointed time under the situation of averaging.

Figure 10 (a), 10 (b), 10 (c) expression is used to illustrate the complete list of the gray shade scale performance method of every frame (interlacing is every when driving).Figure 10 (a)～10 (c) is illustrated in as in each organic EL luminescent layer 18～20 of the 1st layer～the 3rd layer, changes and the current value set and the relation of time length by every frame.Also having, all is that the luminous total brightness of all luminescent layers equates in 1 frame.

(the 5th embodiment of weighting)

Figure 10 (a) expression is set in each organic EL luminescent layer flows through different current values, presses the complete list of the 5th embodiment of per 1 frame switching, weighting.In addition, length t equates the time.With reference to the complete list of Figure 10 (a), in the 1st frame, the 1st layer current value is made as " i ", and the 2nd layer current value is made as " 2i ", and the 3rd layer current value is made as " 4i ".In the 2nd frame, the 1st layer current value is made as " 2i ", and the 2nd layer current value is made as " 4i ", and the 3rd layer current value is made as " i ".In the 3rd frame, the 1st layer current value is made as " 4i ", and the 2nd layer current value is made as " i ", and the 3rd layer current value is made as " 2i ".Like this, switch the current value of the electric current that provides to each organic EL luminescent layer, thereby switch weighting each organic EL luminescent layer by every frame by every frame.Among the 5th embodiment, the 4th frame later on successively repeatedly setting the current value from each layer of the 1st frame to the 3 frames.

That is, set by the current value circulation primary of each layer in 3 frames.Therefore, the 5th embodiment has set 3 kinds of weightings.

Have, under all luminous situation of all organic EL luminescent layers, the total brightness of each organic EL luminescent layer is a unit with 3 frames, all is identical value in all frames again.Owing to set like this, make the total amount equalization of the current value that flows through each organic EL luminescent layer, have the effect of the life-span homogenization that makes each organic EL luminescent layer.

As mentioned above, the complete list of the Figure 10 (a) that keeps according to current value complete list maintaining part 90 comes the switch current value.

Figure 11 is the timing diagram of the 5th embodiment.Figure 11 (A)～(C) expression applies state from the electric current of each organic EL luminescent layer of the 1st layer to the 3rd layer.The longitudinal direction of Figure 11 (A)～(C) is represented each row of display panel, represents that according to Fig. 7 Y1～Y4 is capable herein.Transverse direction express time (TIME).Also have, 1 frame is 16.6 millimeters seconds (ms), as time goes by switch frame successively.

At moment tm1, the gate drivers 391 of Fig. 7 makes each capable pixel 362 conducting of Y1, and each pixel 362 that Y1 is capable just is driven with the time length t till moment tm2.Then, gate drivers 392 makes each capable pixel 362 conducting of Y2, and each pixel 362 that Y2 is capable is driven with time length t.Like this, gate drivers 391～394 makes the capable conducting of Y1～Y4 successively.At moment tm3, make the capable conducting of Y4, drive with the time length t till moment tm4.

(the 6th embodiment of weighting)

Figure 10 (b) expression is set at the electric current that flows through different time length, identical current value in each organic EL luminescent layer (the 1st layer～the 3rd layer), by per 1 frame switch, the complete list of the 6th embodiment of weighting.In the 1st frame, the 1st layer time length is made as " t ", and the 2nd layer time length is made as " 2t ", and the 3rd layer time length is made as " 4t ".In the 2nd frame, the 1st layer time length is made as " 2t ", and the 2nd layer time length is made as " 4t ", and the 3rd layer of time length is set " t ".In the 3rd frame, the 1st layer time length is made as " 4t ", and the 2nd layer time length is made as " t ", and the 3rd layer of time length is set " 2t ".Switch weighting by every frame like this to each organic luminous layer, the 4th frame later on successively repeatedly setting the time length from each layer of the 1st frame to the 3 frames.

As mentioned above, the complete list according to Figure 10 (b) of time length complete list maintaining part 80 storage comes length switching time.

That is, set by the time length circulation primary of the electric current that flows through each luminescent layer in 3 frames.The 6th embodiment has set 3 kinds of weightings.

Owing to set like this, make the T.T. amount equalization of the current value that flows through each luminescent layer, have the effect of the life-span homogenization that makes each organic EL luminescent layer.Among the 6th embodiment, each luminescent layer is that the time-division (PWM) is luminous, can realize finer gray shade scale performance.

Figure 12 is the timing diagram of the 6th embodiment.Figure 12 (A)～(C) expression applies state from the electric current of each organic membrane luminescent layer of the 1st layer to the 3rd layer.That represents with transverse direction at longitudinal direction is identical with Figure 11, thereby omits explanation.In addition, among Figure 12 the time length t among Figure 11 1/4 as time length t.Therefore the time length 4t of Figure 12 equates with the time length t of Figure 11.

Identical with the 5th embodiment, make the words of each capable pixel 362 conducting of Y1 at the moment tm1 identical with the 5th embodiment, the 1st layer of each pixel 362 that Y1 is capable with the time length t till moment tm2, the 2nd layer with the time length 2t till tm3 constantly, and the 3rd layer is driven with the time length 4t till moment tm4.

(the 7th embodiment of weighting)

Figure 10 (c) expression is set at the electric current that flows through different current values and different time length in each luminescent layer respectively, presses the complete list of the 7th embodiment of per 1 frame switching, weighting.Among Figure 10 (c), in the 1st frame, the 1st layer current value is made as " i ", time length is made as " t ", and the 2nd layer current value is made as " (3/2) i ", time length is made as " (4/3) t ", and the 3rd layer current value is made as " 2i ", time length is made as " 2t ".After the 2nd frame, luminance weighted is the current value of " 1 ", " 2 ", " 4 " and the combination of time length, by per 3 frame unit's circulation primary, sets according to this in each layer.That is, in each layer between the 1st frame to the 3 frames, luminance weighted be the combination of the current value of " 1 ", " 2 ", " 4 " and time length with regard to circulation primary, the total brightness of each frame is " 7 " often, sets according to this.The 4th frame is set later on too, and the order of the combination of circulation primary can change by per 3 frames shown in Figure 10 (c), also can be made as identical.

Set the combination of 3 kinds of time length and current value among the 7th embodiment, set 3 kinds of weightings.

Owing to set like this, make the current value that flows through each luminescent layer and the total amount equalization of time length, have the effect of the life-span homogenization that makes luminescent layer.The 7th embodiment also is that each luminescent layer is that the time-division (PWM) is luminous, can realize finer gray shade scale performance.

Figure 13 is the timing diagram of the 7th embodiment.Figure 13 (A)～(C) expression applies state from the electric current of each organic membrane luminescent layer of the 1st layer to the 3rd layer.That represents with transverse direction at longitudinal direction is identical with Figure 11, thereby omits explanation.

Figure 10 (a)～10 (c) has represented that the organic membrane luminescent layer is a luminance weighted example of 3 layers occasion, but, is not so limited, and the occasion of more multi-layeredization also can be used.In this occasion, when the number of plies of luminescent layer is the n layer, switch weighting to each layer by every frame, n frame circulation primary is pressed in the current value of m kind (m is the following natural number of n) and the combination of time length, sets according to this.And as mentioned above, the total brightness when all luminescent layers are luminous in each frame all is identical value, sets according to this.Also have, all luminous occasion of all luminescent layers in all frames, the total brightness of each luminescent layer all is identical value by n frame unit, sets according to this.

Also have, among Figure 10 (a)～10 (c), each organic luminous layer all is made as different current values and time length, but, is not so limited.For example, the 1st layer～the 3rd layer current value can be made as current value identical as " 1 ", " 1 ", " 1 " and time length with time length, also can be made as part is identical as " 1 ", " 2 ", " 2 " current value and time length.

In addition, in the foregoing description, constitute from the 1st layer to the 3rd layer, or, but, be not so limited from the 1st layer to the 5th layer organic membrane luminescent layer with identical materials.Even the material of organic membrane luminescent layer is inequality, as mentioned above, as long as constitute, for each organic membrane luminescent layer, make current value different, thereby make as the occasion of total brightness at Fig. 3 (a) with the time length that flows through electric current, the 1st layer is " 1 ", and the 2nd layer is " 2 ", and the 3rd layer is " 4 ", occasion at Fig. 3 (b), the 1st layer is " 1 ", and the 2nd layer is " 2 ", and the 3rd layer is " 4 ", the 4th layer is " 8 ", and the 5th layer is that " 16 " get final product.

Element according to second embodiment, under the state of the weighting of n light-emitting component having been set luminosity respectively, make n light-emitting component luminous, thereby carry out the gray shade scale performance of each point, thereby with only to 1 light-emitting component electric current is provided and the representing gradation grade before device compare, light-emitting component can be facilitated the realization of long-life display device.Also have, every gray shade scale do not have luminous and non-luminous during, thereby can eliminate flicker, and, owing to being digital drive, thereby can eliminate the occasion that has adopted TFT in element drives portion, the caused uneven luminance of the deviation of the element characteristic that TFT has.

Also have, element according to second embodiment, each luminescent layer for light-emitting component, flow through the time length of electric current and be made as identical value with a side in the current value, when the opposing party is made as the value of m kind, or the combination of time length and current value is when being made as the value of m kind, the value that makes the m kind by n frame (when interlacing drives for) during circulation primary, set according to this, thereby make the current value that flows through in each luminescent layer and the total amount equalization of time length, thereby can make the life-span homogenization of each luminescent layer.

" the 3rd embodiment "

Secondly, pixel in the display device of the 3rd embodiment of the present invention is described in detail in detail.The pixel that has adopted each organic membrane luminescent layer only to form in first and second embodiments by the digital drive layer of digital drive, but, the pixel that adopts analog-driven layer and digital drive layer by analog-driven to constitute in the 3rd embodiment.

Figure 14 represents that the layer of the pixel in the display device of the 3rd embodiment of the present invention constitutes.Display device for example is an OLED display.In Figure 14, glass substrate 301 is display surfaces of display device.This glass substrate 301 if can form the layer of organic membrane, also can be the substrate of plastics one class.On this glass substrate 301, formed anode 302.As this anode 302, for example can use ITO as transparency electrode etc.

Formed organic membrane luminescent layer 303 on the anode 302.This organic membrane luminescent layer 303 constitutes with hole injection layer, hole transporting layer, electron injecting layer, electron supplying layer and by the combination as the luminescent layer of fluorophor that organic compound is formed.This combination must suitably be selected according to the characteristic of organic EL.

On organic membrane luminescent layer 303, formed negative electrode 304.As negative electrode 304, if use ITO, just can not directly move, thereby must between ITO and organic membrane luminescent layer 303, insert lithium that negative electrode uses etc. thinly as negative electrode as transparency electrode.

Power supply 3013 connects for apply DC voltage between anode 302 and negative electrode 304.The principle of luminosity that is clipped in the organic membrane luminescent layer 303 between anode 302 and the negative electrode 304 is with identical with precedent.

On negative electrode 304, stack gradually and formed silicon oxide film 3011 and anode 305.Silicon oxide film 3011 has the effect that makes anode 305 and negative electrode 304 insulation.

Same as described above on anode 305, stack gradually and form organic membrane luminescent layer 306, negative electrode 307, silicon oxide film 3012, anode 308, organic membrane luminescent layer 309, negative electrode 3010, silicon oxide film 3103, anode 3100, organic membrane luminescent layer 3101 and negative electrode 3102.Do not taking out the structure from the lower light of negative electrode 3,102 one side-draw bright dippings as the 3rd embodiment, negative electrode 3102 is metals such as aluminium.

Power supply 3014,3015,3104 is respectively between anode 305 and the negative electrode 307, between anode 308 and the negative electrode 3010 and apply DC voltage between anode 3100 and the negative electrode 3102 and connect.Provide the electric current that from dc voltage conversion form from anode and negative electrode to each organic membrane luminescent layer 306,309,3101 by power supply 3014,3015,3104 like this.

Each organic membrane luminescent layer 303,306,309,3101 with the proportional brightness of the current value that is transformed into and luminous, light goes out from glass substrate 301 1 side-draws.In addition, this structure is not limited to organic EL, and inorganic EL realizes certainly that also be not limited to active driving, the display device of passive drive also can realize.

Herein, organic membrane luminescent layer the 303,306, the 309th, the digital drive layer that 2 values of the conduction and cut-off by power supply are switched is luminous and not luminous (light and turn off the light).Organic membrane luminescent layer 303,306,309 is selected the luminous material of brightness in accordance with regulations respectively and is formed.

By contrast, the proportional material of the magnitude of current that organic membrane luminescent layer 3101 selects brightness variation and power supply 3104 to provide makes its brightness in accordance with regulations luminous.That is, organic membrane luminescent layer 3101 is analog-driven layers that the brightness basis changes the action of the size variation of electric current, can realize the luminous of middle gray level.Therefore the element of the 3rd embodiment is that the digital drive layer is 3 layers, and the analog-driven layer is 1 layer of structure.

Figure 15 represents the pixel structure as the display device of the 3rd embodiment of the present invention.In Figure 15, the component part identical with Figure 14 paid with same-sign, omits this explanation.Figure 15 represents to constitute 1 point in (for example red, green, blue etc.) of all kinds of 1 pixel., on glass substrate 301, formed thin film transistor (TFT) (TFT) 3016a, 3016b, 3016c, 3016d herein, be connected with anode 302,305,308,3100 respectively as active component.As long as TFT3016a～3016d can drive controlling organic membrane luminescent layer 303,306,309,3101, waiting which kind of active component to make with p-Si (the many silicon of low temperature), a-Si (amorphous silicon) can.

TFT3016a～3016d has the circuit function that the power turn-on that provides to organic membrane luminescent layer 303,306,309,3101/end is provided.Also have, the silicon oxide film 3017 that forms between glass substrate 301 and anode 302 is films that metallic ion is not moved from glass substrate 301 anode 302.Negative electrode 304, negative electrode 307, negative electrode 3010, negative electrode 3102 are common electrodes.

At the downside from pixel shown in Figure 15 is the occasion of glass substrate 301 1 side-draw bright dippings, does not leak from the negative electrode 3102 as the upside of pixel for making light, and metals such as negative electrode 3102 usefulness aluminium form.Like this, from organic membrane luminescent layer 303,306,309, the 3101 just radiation up and down of light of outgoing respectively, but, to the light of negative electrode 3,102 one side outgoing by negative electrode 3102 reflections towards downside, thereby just only be removed from glass substrate 301 1 sides.

In addition, in the 3rd embodiment, has TFT3016a～3016d on the glass substrate 301, it is lower light taking-up structure from glass substrate 301 1 side-draw bright dippings, but, also can make with transparency electrode and form negative electrode 3102, form anode 302 with metals such as aluminium, light takes out structure above negative electrode 3,102 one side-draw bright dippings.

Herein, TFT3016a～3016d is necessary for a plurality of usually.TFT3016a～3016d is called element drives portion (the 1st drive division) herein.Organic membrane luminescent layer and element drives portion are unit element.OLED display shown in Figure 14 is the light-emitting component that has 4 layers of structure that 4 luminescent layers are laminated in the display surface vertical direction to display device.

The method that same Fig. 3 of luminance weighted method (a), 3 (b) of the organic membrane luminescent layer 303,306,309 in the pixel of Figure 14 and the 3rd embodiment shown in Figure 15 have represented.The 1st layer is that 303, the 2 layers of organic membrane luminescent layers are that the organic membrane luminescent layer is an organic membrane luminescent layer 309 for 306, the 3 layers.

Fig. 3 (b) expression organic membrane luminescent layer is the example of the occasion of 5 layers of structure, can regard 5 layers of structure that Figure 14 and structure shown in Figure 15 are established 1 unit element again as.One side of a side that is removed near light from 5 organic membrane luminescent layers is the 1st layer, the 2nd layer, the 3rd layer, the 4th layer and the 5th layer in order.

An example of the gray shade scale of the pixel of the display device of the 3rd embodiment performance as shown in Figure 4, with what illustrated.

Figure 16 represents the driver pie graph of display panel of the display device of the 3rd embodiment of the present invention.In Figure 16, pixel 3036 is equivalent to the image element circuit among aftermentioned Figure 17.Have on the display panel of the 3rd embodiment be used for to a plurality of pixels 3036 that are configured to two-dimensional-matrix-like send the numerical data of simulated data and 3 bits horizontal driver 3037, be used to drive the power circuit 3038 of pixel and the vertical driver 3039 of selecting the line of vertical direction.

A plurality of pixels 3036 are configured to the two-dimensional-matrix-like that the row X by capable Y that arranges in vertical direction and arrangement in the horizontal direction forms.As an example, 4 of expression Y1～Y4 goes, the display panels of 6 row of X1～X6 among Figure 16.Actual display panel is more than ranks shown in Figure 16, but, and expression for convenience and so herein.In the 3rd embodiment, assemble data driver 3371～3376 in the horizontal driver 3037, assembled power supply unit 3381～3386 in the power circuit 3038, assembled gate drivers 3391～3394 in the vertical driver 3039.In addition, herein horizontal driver 3037 and vertical driver 3039 as the 2nd drive division.

For example, in the occasion that will scan as the capable display line of the higher level's of display panel shown in Figure 16 Y1, the gate drivers 3391 of vertical driver 3039 (gating TFT) makes each capable pixel 3036 conducting of Y1.Other display line Y2 is capable～and Y4 is capable to be ended by gate drivers 3392～3394.Offer each pixel 3036 from the data (being made up of numerical data and simulated data) of 1 line of horizontal driver 3037 image output data this moment.

Secondly, gate drivers 3391 ends each capable pixel 3036 of Y1, thereby shows the image of 1 line that Y1 is capable.Then same, gate drivers 3392 to Y4 capable gate drivers 3394 orders that Y2 is capable drive vertical driver 3039, press per 1 line image output data from horizontal driver 3037, thereby just can scan the pixel 3036 in all display panels.

Figure 17 represents to be used to drive the circuit diagram of driving circuit of the pixel of the 3rd embodiment of the present invention.In Figure 17, organic EL luminescent layer 3018,3019,3020,3105 is equivalent to Figure 14 and organic membrane luminescent layer 303,306,309,3101 shown in Figure 15.The pixel of the 3rd embodiment represents that the numeral layer is 3 layers, and simulation layer is 4 layers of structure of meter of 1 layer, and luminance weighted and Fig. 3 (a) of each layer of formation numeral layer is identical, is " 1 ", " 2 ", " 4 ".

Each end (be anode among the figure) of organic EL luminescent layer 3018～3020,3105 is connected with the power supply 3030～3032,3109 of formation power supply unit 3381 by driving with TFT3024～3026,3107 each source electrode, drain electrode.Also have, TFT3024～3026, each grid of 3107 and be connected as TFT3027～3029 of gate transistor, each source electrode of 3108 pass through capacitor 3021～3023,3106 on the other hand and are connected with power supply 3030～3032,3109.

Power supply 3030,3031,3032 and 3109 is equivalent to power supply shown in Figure 14 3013,3014,3015 and 3104 respectively.Power supply 3030～3032 and 3109 can be an independent current source, can be common source also, sets organic EL luminescent layer 3018～3020, makes its weighting with regulation, in accordance with regulations brightness luminous.And each drain electrode of TFT3027～3029 is connected with the data maintaining part 3350～3352 in the data driver 3371, and each grid and gate drivers 3391 connect altogether.Also have, the grid of TFT3107 applies simulated data 3110 by source electrode, the drain electrode of TFT3108.

, represented data driver 3371, power supply unit 3381, gate drivers 3391 herein, but, as shown in figure 16, data driver 3372～3376, power supply unit 3382～3386, gate drivers 3392～3394 also are identical formations.Data driver 3371～3376, power supply unit 3381～3386, gate drivers 3391～3394 drives each row Y of display panels, respectively is listed as the pixel 3036 of X.

For convenience, illustrate the gate drivers 3391 (～3394) that is connected with gate transistor 3108 with gate transistor 3027～3029 in addition among Figure 17.

Secondly, the action of this driving circuit is described.Explanation is earlier carried out digital drive to the organic EL luminescent layer 3018,3019 and 3020 as the numeral layer, makes its 2 values according to conduction and cut-off carry out luminous/non-luminous situation.

At first, the data 3033 (3 bit) of the regulation gray shade scale that shows on the pixel 3036 input data driver 3371.Data 3033 are the serial data or the parallel data of numeral preferably.The data of having been imported by data driver 3,371 3033 are used for making the corresponding organic EL luminescent layer of gray-scale displayed grade on the display device with organic EL luminescent layer 3018～3020 luminous.

Each bit of data 3033 (1 or 0) is kept by data maintaining part 3350～3352, and the grid of 3391 pairs of gate transistors 3027～3029 of gate drivers applies the 1st current potential of regulation, makes it become conducting state.From the data of data driver 3371 output each drain electrode, source electrode, write, be stored in and be used for the capacitor 3021～3023 that data keep by gate transistor 3027～3029.

Then, the grid of 3391 pairs of gate transistors 3027～3029 of gate drivers applies the 2nd current potential of regulation, makes it become cut-off state.Gate transistor 3027～3029 is ended, and the electric charge of having put aside on capacitor 3021～3023 just is held.The electric charge that is kept by capacitor 3021～3023 is the potential difference (PD) of the output voltage of power supply 3030～3032 and data driver 3371.

Following illustrative examples is as the situation of the image of display gray scale grade " 5 " on display device.With reference to Fig. 4, gray shade scale " 5 " need make organic EL luminescent layer 3018 and 3020 of the 1st layer and the 3rd layer light.Herein, the 1st layer is that 3018, the 2 layers of organic EL luminescent layers are that 3019, the 3 layers of organic EL luminescent layers are organic EL luminescent layer 3020.

The data of having imported 3033 are transformed to the related data rows of signal wire with corresponding organic EL luminescent layer by data driver 3371, in this occasion, are keeping making organic EL luminescent layer 3018 and 3020 luminous data in the data maintaining part 3350 and 3352.

Apply the voltage that makes TFT3024 conducting on the capacitor 3021 this moment, also apply the voltage that makes the TFT3026 conducting on the capacitor 3023, thereby TFT3024 and 3026 becomes conducting state respectively.On the other hand, do not apply the voltage of drive TFT 3025 on the capacitor 3022, thereby TFT3025 is a cut-off state.

Therefore, TFT3024 and 3026 is a conducting state, thus from power supply 3030,3032 by TFT3024, each drain electrode of 3026, source electrode provides electric current to organic EL luminescent layer 3018,3020, organic EL luminescent layer 3018,3020 will be luminous.Being weighted to of organic EL luminescent layer 3018 and 3020 luminosity this moment " 1 " and " 4 ", thereby shown on display device as the gray shade scale " 5 " of its summation.

Secondly, illustrate with organic EL luminescent layer 3105 and carry out the luminous of middle gray level and it is carried out the situation of analog-driven.At first, want the simulated data 3110 of gray-scale displayed grade on the input pixel.Simulated data 3110 is used for the data of the gray shade scale corresponding with the luminosity of the little level of the minimum luminosity that can show than numerical data 3033.

Consider the example of display gray scale grade " 0.3 " on display device herein.Input simulated data 3110, gate drivers 3391 just makes TFT3108 become conducting state, thereby simulated data 3110 is being used for capacitor 3106 savings that data keep by drain electrode, the source electrode of TFT3108.Then, gate drivers 3391 is controlled to be cut-off state to TFT3108, thereby simulated data 3110 is maintained in the capacitor 3106.

At this moment, the electric charge that is kept by capacitor 3106 is the potential difference (PD) of power supply 3109 and simulated data 3110, and it is that the magnitude of current corresponding with gray-scale data " 0.3 " flows through the value that drives with TFT3107.According to the electric charge that keeps in the capacitor 3106, drive and move with TFT3107, electric current offers organic EL luminescent layer 3105 from drain electrode, the source electrode of power supply 3109 by TFT3107, and organic EL luminescent layer 3105 will be luminous.At this moment, gray shade scale " 0.3 " is shown on display device.

In the digital drive method of the 3rd embodiment, driving shown in Figure 17 is only carried out the conduction and cut-off action with TFT3024～3026.Therefore circuit constitutes and comprises that savings is used for making the gating that drives with the capacitor 3021～3023 of the data of TFT3024～3026 conduction and cut-off and be used for keeping above-mentioned data at these capacitors 3021～3023 to get final product with the very simple circuit formation of TFT3027～3029.Also have, drive with TFT3024～3026 and only carry out the conduction and cut-off action, thereby move the zone of saturation that the caused threshold deviation of element characteristic of the problematic TFT as active component of organic EL display that can be former does not have to influence.Therefore, can infinitely reduce the interior problems such as the not even gray shade scale deviation of display brightness of display panel.

Also have, in the digital drive method of the 3rd embodiment, drive and only carry out the switch motion of conduction and cut-off, thereby can move few zone of saturation in the electric power loss of TFT with TFT3024～3026.Therefore, compared, can reduce consumption of electric power with former display device.

Have, in the 3rd embodiment, the electric current that provides to organic EL is disperseed by a plurality of luminescent layers again.2 powers that it is generally acknowledged the life-span of organic EL and current value are inversely proportional.Electric current can be reduced the magnitude of current of each layer by a plurality of layers of dispersion, thereby compares with former circuit formation, can life-saving.

Have again, in the 3rd embodiment,, illustrated that simulated data 3110 constitutes the method for the data that are used for the gray shade scale corresponding with the luminosity of the little level of the minimum luminosity that can show than numerical data 3033 as the method for digital drive and analog-driven, but, be not so limited.Also can be that simulated data 3110 constitutes the method for the data that are used for the gray shade scale corresponding with the luminosity of the big level of the maximum luminousing brightness that can show than numerical data 3033.

(first embodiment of gray shade scale performance)

Secondly, the gray shade scale performance method of the pixel in the display device of the 3rd embodiment is described.

Figure 18 represents to show with the pixel of the 3rd embodiment shown in Figure 14 first embodiment of the gray shade scale with linear characteristic.As mentioned above, the digital drive layer according to the action of the conduction and cut-off of power supply and luminous/not luminous, the analog-driven layer makes the size variation of electric current change brightness.

In Figure 18, the longitudinal axis is represented the luminosity of whole pixel, and transverse axis represents to import data (input gray level grade).Figure 19～Figure 21 described later is also identical.Zheng Ti luminosity is the luminosity (the brightness summations of a plurality of organic membrane luminescent layers) of integral body that constitutes stacked a plurality of organic membrane luminescent layers of 1 pixel herein.

At the digital drive layer is the occasion of 3 layers of structure, and the gray shade scale performance of numeric only Drive Layer can only show and comprise 08 steps, and shown in I among Figure 18, the differential change of luminosity level is big, and difficulty has careful gray shade scale performance.If increase the number of plies of digital drive layer, the gray shade scale number also can correspondingly increase, but panel structure also can become complicated pro rata, and it is complicated that method of work also becomes.

Therefore, as the pixel of the 3rd embodiment, append 1 layer of simulation layer, carry out interpolation and make it luminous the gray shade scale of numeral layer is differential.Particularly, in the input data is the occasion of the multiple of " 32 ", " 64 ", " 96 ", " 128 ", " 160 ", " 192 ", " 224 " this 32, by above-mentioned the 1st layer to the 3rd layer be the luminance weighted gray shade scale level of coming to improve the digital drive layer of organic membrane luminescent layer 303,306,309 from 0～7 substep, improve luminosity.3 kinds of weightings shown in Fig. 3 (a) have been set to the 1st layer to the 3rd layer herein.

In the input data is the occasion of " 0 "～" 31 ", and the digital drive portion that drives the digital drive layer is made as " 0 " to the gray shade scale level.The analog-driven portion that drives the analog-driven layer sets the gray shade scale level, makes organic membrane luminescent layer 3101 luminous according to input data " 0 "～" 31 ".

Equally, in the input data is the occasion of " 32 "～" 63 ", the gray shade scale level of digital drive layer is made as " 1 ", is made as the gray shade scale level of analog-driven layer according to deduct " 0 "～" 31 " after " 32 " from input data " 32 "～" 63 " luminous.In the input data is the occasion of " 64 "～" 95 ", the gray shade scale level of digital drive layer is made as " 2 ", is made as the gray shade scale level of analog-driven layer according to deduct " 0 "～" 31 " after " 64 " from input data " 64 "～" 95 " luminous.In the input data is the occasion of " 96 "～" 127 ", the gray shade scale level of digital drive layer is made as " 3 ", is made as the gray shade scale level of analog-driven layer according to deduct " 0 "～" 31 " after " 96 " from input data " 96 "～" 127 " luminous.

Equally, in the input data is the occasion of " 128 "～" 159 ", the occasion of " 160 "～" 191 ", the occasion of " 192 "～" 223 ", the occasion of " 224 "～" 255 ", make the gray shade scale level of digital drive layer increase to " 4 ", " 5 ", " 6 ", " 7 ", be made as the gray shade scale level of analog-driven layer according to " 0 "～" 31 " luminous.

Owing to set like this, the luminance level of analog-driven layer has the gray shade scale performance of linear characteristic shown in II among Figure 18.Like this, the analog-driven layer has with the structure that the digital drive layer is only arranged to be compared, and can realize the effect of multi-grayscale, and the digital drive layer has with the structure that the analog-driven layer is only arranged to be compared, and reduces the effect of uneven luminance.

(second embodiment of gray shade scale performance)

Figure 19 represents that the pixel of the 3rd embodiment has second embodiment of gray shade scale of the linear characteristic of gamma characteristic rather than Figure 18.For the occasion of the structure of digital drive layer is only arranged, shown in III among Figure 19, the gray shade scale of input data is big more in pixel, luminosity level differential just big more, and difficulty has careful gray shade scale performance.Therefore, append 1 layer of analog-driven layer, carry out interpolation and make it luminous the gray shade scale of digital drive layer is differential.

, different with first embodiment shown in Figure 180, the gray shade scale level of analog-driven layer is made as, do not make it proportional, but make it have gamma characteristic and luminous with input data " 0 "～" 31 ".That is, the luminance level of analog-driven layer is carried out the setting shown in IV among Figure 19 according to the input data, makes the relation of importing the data and the luminosity of integral body have the gamma characteristic as the curve of Figure 19.

Because set like this, the analog-driven layer has with the structure that the digital drive layer is only arranged to be compared, and can realize the effect of multi-grayscale, the digital drive layer has with the structure that the analog-driven layer is only arranged to be compared, and reduces the effect of uneven luminance.Can also carry out the gamma revisal that cooperates with the characteristic of display.

(the 3rd embodiment of gray shade scale performance)

Figure 20 represents to use the pixel that is made of the 3rd embodiment of light-emitting component (multilayer portion) 3 layer digital Drive Layer and 2 layers of analog-driven layer, and performance has the 3rd embodiment of the gray shade scale of gamma characteristic.As mentioned above, the digital drive layer is 3 layers of structure, and the gray shade scale performance of numeric only Drive Layer can only show and comprise 08 steps.Therefore, the input data are fastened with the pass of the luminosity of integral body had gamma characteristic, shown in V among Figure 20, the differential of luminosity level will become big, and difficulty has careful gray shade scale performance.

Therefore, shown in VI among Figure 20, the input data of the 1st layer analog-driven layer and the relation of luminosity level are used for the differential interpolation of carrying out of the gray shade scale of digital drive layer, among Figure 20 shown in the VII, the input data of the 2nd layer analog-driven layer and the relation of luminosity level are used for gamma characteristic is carried out inching and makes it luminous for another example.The 2nd layer analog-driven layer be made as can with the characteristic deviation of every display, through the time change and cooperate and change gamma characteristic.

Because set like this, the analog-driven layer has with the structure that the digital drive layer is only arranged to be compared, and can realize the effect of multi-grayscale, the digital drive layer has with the structure that the analog-driven layer is only arranged to be compared, and reduces the effect of uneven luminance.Can also carry out the gamma revisal that cooperates with the characteristic of display.

(the 4th embodiment of gray shade scale performance)

The pixel that constitutes the 3rd embodiment of multilayer portion by 3 layer digital Drive Layer and 2 layers of analog-driven layer of representing Figure 21 to use improves the 4th embodiment of technique of expression of occasion of the gray shade scale of peak brightness.The digital drive layer is 3 layers of structure, and the gray shade scale performance of numeric only Drive Layer can only show and comprise 08 steps.Therefore, setting, to improve the occasion of the input data and the peak brightness of the relation of the luminosity of integral body, shown in VIII among Figure 21, the differential of luminosity level will become big, and difficulty has careful gray shade scale performance.

Therefore, shown in IX among Figure 21, the input data of the 1st layer analog-driven layer and the relation of luminosity level are used for the differential interpolation of carrying out of the gray shade scale of digital drive layer, for another example among Figure 21 shown in the X, the input data of the 2nd layer analog-driven layer and the relation of luminosity level only are used for making it luminous now at peak brightness to have surpassed 100% water-glass.

Because set like this, the analog-driven layer has with the structure that the digital drive layer is only arranged to be compared, and can realize the effect of multi-grayscale, the digital drive layer has with the structure that the analog-driven layer is only arranged to be compared, and reduces the effect of uneven luminance.Can also obtain the image output of impulsive force by the raising peak brightness.

The element of the 3rd embodiment that has more than illustrated is combined by numeral layer and simulation layer, thereby with all n luminescent layer is carried out digital drive and its luminous formation is compared, can show multi-grayscale owing to form simulation layer, the gray shade scale performance of the scale grade characteristic of the hope of 1 point that can also wish.Also have, and all n luminescent layer is carried out analog-driven and its luminous formation is compared, can reduce the deviation of the brightness of every pixel significantly, thereby can reduce uneven luminance and gray shade scale deviation, and can reduce power attenuation.

Above-mentioned Figure 18 is to first embodiment shown in Figure 21～with having represented among the 4th embodiment that the pixel employing has an example of 3 layer digital Drive Layer and 1 layer or 2 layers analog-driven layer, but, be not so limited, and also can use making more multi-layered occasion.

" the 4th embodiment "

Figure 22 represents to constitute as the layer of the pixel of the display device of the 4th embodiment of the present invention of the embodiment that has adopted multi-photon.Display device for example is an OLED display.In Figure 22, glass substrate 401 is display surfaces of display device.This glass substrate 401 if can form the layer of organic membrane, also can be the substrate of plastics one class.On this glass substrate 401, formed anode 402.As this anode 402, for example can use ITO as transparency electrode etc.

Formed organic membrane luminescent layer 403 on the anode 402.Organic membrane luminescent layer 403 constitutes (described later organic membrane luminescent layer 405,407,409 also identical) with hole injection layer, hole transporting layer, electron injecting layer, electron supplying layer and by the combination as the luminescent layer of fluorophor that organic compound is formed.This combination must suitably be selected according to the characteristic of organic EL.

On organic membrane luminescent layer 403, formed charge generating layers 404 as shown in figure 22.Charge generating layers 404 is as the input horizon in electronics and hole and move.Can adapt to ITO or V2O5 etc. on the charge generating layers 404.Form organic membrane luminescent layer 405 on the charge generating layers 404, stacked gradually charge generating layers 406, organic membrane luminescent layer 407, charge generating layers 408, organic membrane luminescent layer 409 more thereon.And, on organic membrane luminescent layer 409, having formed negative electrode 410, power supply 411 is connected with anode 402 with negative electrode 410.

The display device of the 4th embodiment is the structure of alternately multilayer laminated organic membrane luminescent layer and charge generating layers between anode 402 and negative electrode 410, and this structure is called multi-photon (マ Le チ Off オ ト Application).The light-emitting component portion that is clipped in the multi-photon structure between anode 402 and the negative electrode 410 is called luminescence unit herein.

In the occasion of taking out light from glass substrate 401, catoptrical metal such as negative electrode 410 usefulness aluminium forms.The principle of luminosity that is clipped in each the organic membrane luminescent layer 403,405,407,409 between anode 402 and the negative electrode 410 is with identical with precedent.Also has power supply 411.

Figure 23 represents the principle of work of multi-photon.Component part identical with Figure 22 among Figure 23 is paid with same-sign.In Figure 23, charge generating layers 404,406,408 has function from hole to the organic membrane luminescent layer 403,405,407,409 of adjacency that inject electronics and.In organic membrane luminescent layer 403,405,407,409 electronics and hole again in conjunction with and luminous.From the brightness of organic EL output is summation from each luminous brightness of each organic membrane luminescent layer 403,405,407,409.

Herein, multi-photon is made of 4 layers of organic membrane luminescent layer 403,405,407,409, but, each organic membrane luminescent layer uses the luminescent material of identical characteristics, in the occasion that each layer has been applied the voltage identical with 1 layer occasion, with former organic membrane luminescent layer is that 1 layer formation is compared, and can obtain 4 times brightness.Like this, obtain with multi-photon with before the occasion of the identical brightness of formation, can make the electric current that flows through each organic membrane luminescent layer is 1/4th, thereby can realize the long lifetime of organic membrane luminescent layer.In the 4th embodiment, prerequisite is the identical luminescent material of each layer use of multi-photon, but, is not so limited in the occasion that can obtain the identical characteristics of luminescence.

Figure 24 has represented to adopt the pixel of display device of the 4th embodiment of multi-photon to constitute.In the 4th embodiment, at first, on glass substrate 415, form anode 416, formed organic membrane luminescent layer 417 more thereon.Organic membrane luminescent layer 417 is identical with formation with precedent.On organic membrane luminescent layer 417, formed negative electrode 418.Apply voltage from power supply 430 antianodes 416 and negative electrode 418.

On these layers, formed silicon oxide film 419.Silicon oxide film 419 have make the anode 420 that formed on the silicon oxide film 419 and under the effect of negative electrode 418 electrical isolations that formed.Organic membrane luminescent layer 421a, charge generating layers 422, organic membrane luminescent layer 421b and negative electrode 423 on anode 420, have been stacked gradually.Structure between anode 420 and negative electrode 423 is the multi-photon of 2 layers of formation.

Organic membrane luminescent layer 421a and 421b use with organic membrane luminescent layer 417 identical materials and form, when each layer added identical voltage, just with identical characteristic radiation pattern.Between anode 420 and negative electrode 423, be connected with power supply 431 and apply voltage.

On negative electrode 423, formed silicon oxide film 424.Silicon oxide film 424 have make the anode 425 that formed on the silicon oxide film 424 and under the effect of negative electrode 423 electrical isolations that formed.Organic membrane luminescent layer 426a, charge generating layers 427a, organic membrane luminescent layer 426b, charge generating layers 427b, organic membrane luminescent layer 426c, charge generating layers 427c, organic membrane luminescent layer 426d and negative electrode 428 on this anode 425, have been stacked gradually.Structure between anode 425 and negative electrode 428 is the multi-photon of 4 layers of formation.

Organic membrane luminescent layer 426a～426d uses with organic membrane luminescent layer 417 identical materials and forms, when each layer added identical voltage, just with identical characteristic radiation pattern.Between anode 425 and negative electrode 428, be connected with power supply 432 and apply voltage.In addition, in the occasion of taking out structure as light above negative electrode 428 1 side-draw bright dippings, transparency electrodes such as negative electrode 428 usefulness ITO constitute.

Each organic membrane luminescent layer 417,421a, 421b, 426a～426d are with luminous with the proportional brightness of the electric current that is applied, and light goes out from glass substrate 415 1 side-draws.Herein, for the brightness that makes each organic membrane luminescent layer 417,421a, 421b, 426a～426d output identical, by each organic membrane luminescent layer 417,421a, 421b, 426a～426d are applied the power values that identical voltage decides power supply 430,431,432.Apply the supply voltage of 1: 2: 4 ratio herein, on the power supply 430,431,432.In addition, the structure of the 4th embodiment is not limited to organic EL, and inorganic EL realizes certainly that also be not limited to active driving, the display device of passive drive also can realize.

Each multi-photon layer switches luminous and not luminous (light and turn off the light) by 2 values of the conduction and cut-off of power supply, thereby brightness respectively in accordance with regulations is luminous.That is, the action of the conduction and cut-off by power supply is carried out digital drive to organic membrane luminescent layer 417,421a, 421b, 426a～426d.

As mentioned above, calling luminescence unit, construct the display device of representing Figure 24 with pixel shown in Figure 25 herein by the illuminating part that is clipped in the multi-photon that organic membrane luminescent layer between an anode and the negative electrode and charge generating layers constitute.Expression herein constitutes 1 point in (for example RGB etc.) of all kinds of 1 pixel.Among Figure 25, the component part identical with Figure 24 paid with same-sign.

In Figure 25, on glass substrate 415, stack gradually silicon oxide film 433, anode 416, luminescence unit 434, negative electrode 418, stack gradually silicon oxide film 419, anode 420, luminescence unit 435, negative electrode 423 more thereon.Stack gradually silicon oxide film 424, anode 425, luminescence unit 436, negative electrode 428 more thereon.

Luminescence unit 434 is equivalent to organic membrane luminescent layer 417, and luminescence unit 435 is equivalent to the illuminating part of 2 layers multi-photon being made up of organic membrane luminescent layer 421a, charge generating layers 422 and organic membrane luminescent layer 421b.Luminescence unit 436 is equivalent to the illuminating part of 4 layers multi-photon being made up of organic membrane luminescent layer 426a, charge generating layers 427a, organic membrane luminescent layer 426b, charge generating layers 427b, organic membrane luminescent layer 426c, charge generating layers 427c and organic membrane luminescent layer 426d.

This is in the 4th embodiment, provide a luminescence unit, the anode that clips it and negative electrode and anode and negative electrode the power supply of supply voltage to call unit element altogether, anode 416, luminescence unit 434, negative electrode 418 constitute a unit element with not shown power supply.Equally, anode 420, luminescence unit 435, negative electrode 423 constitute a unit element with not shown power supply, and anode 425, luminescence unit 436, negative electrode 428 constitute a unit element with not shown power supply.Therefore, OLED display shown in Figure 25 is the light-emitting component that has 3 layers of structure that 3 unit elements are laminated in the display surface vertical direction to display device.

Also have, on glass substrate 415, as shown in figure 25, formed thin film transistor (TFT) (TFT) 437a, 437b, 437c, be connected with anode 416,420,425 respectively as active component.As long as TFT437a～437c can drive controlling organic membrane luminescent layer, of which kind of active component of p-Si (the many silicon of low temperature), a-Si (amorphous silicon) or organic transistor etc. making can.

TFT437a～437c has the circuit function that makes the power turn-on that applies to luminescence unit 434～436/end.Make power turn-on/end, as mentioned above, thereby make TFT437a～437c carry out digital drive, make it luminous or not luminous luminescence unit 434～436 (illuminating part).

Silicon oxide film 433 is films that metallic ion is not moved from glass substrate 415 anode 416.Though not shown, but negative electrode 418, negative electrode 423, negative electrode 428 are common electrodes.

From occasion as the glass substrate 415 1 side-draw bright dippings of the downside of pixel, do not leak for making light from negative electrode 428 as the upside of pixel, metals such as negative electrode 428 usefulness aluminium form.Like this, from the just radiation up and down of the light of luminescence unit 434～436 outgoing, but, to the light of negative electrode 428 1 side outgoing by negative electrode 428 reflections towards downside, thereby just only be removed from glass substrate 415 1 sides.

Have on the glass substrate 415 herein and have TFT437a～437c, take out structure from the lower light of glass substrate 415 1 side-draw bright dippings, and, form negative electrode 428 with transparency electrode, form anode 416 with metals such as aluminium, light takes out structure above negative electrode 428 1 side-draw bright dippings, and but, which kind of structure can use among the present invention.Herein, TFT437a～437c is necessary for a plurality of usually.TFT437a～437c is called element drives portion (the 1st drive division) herein.

As shown in figure 25, be the occasion of 3 layers of structure at luminescence unit, the luminance weighted of each layer undertaken by Fig. 3 (a).Luminance weightedly be meant that with certain value be benchmark, the luminosity relative number value of each luminescent layer value.

Herein, Figure 24 and luminescence unit 434 shown in Figure 25 are made as the 1st layer, and luminescence unit 435 is made as the 2nd layer, and luminescence unit 436 is made as the 3rd layer, and the 1st layer brightness is made as " 1 ", and the 2nd layer brightness is made as " 2 ", and the 3rd layer brightness is made as " 4 ".The identical occasion of voltage that this applies on each organic membrane luminescent layer of multi-photon structure, the integral multiple of the number of the organic membrane luminescent layer that just becomes each luminescence unit and had from the brightness of each luminescence unit output.Herein, the luminosity the when brightness of each luminescence unit is represented to make the supply voltage conducting, each luminescence unit carries out digital drive by the conduction and cut-off of supply voltage.

Fig. 3 (b) expression luminescence unit is a luminance weighted example of the occasion of 5 layers of structure.In the occasion of 5 layers of structure, in Figure 24 and structure shown in Figure 25, stacked again 2 unit elements, totally 5 form luminescence unit.One side of a side that is removed near light from these 5 luminescence units is made as the 1st layer, the 2nd layer, the 3rd layer, the 4th layer and the 5th layer in order, shown in Fig. 3 (b), when the 1st layer brightness is made as " 1 ", the 2nd layer is brightness " 2 ", the 3rd layer is brightness " 4 ", the 4th layer is brightness " 8 ", and the 5th layer is brightness " 16 ".

The method of the gray shade scale performance of the luminance weighted occasion of Fig. 4 presentation graphs 3 (a) is as having illustrated.

Figure 26 has represented to adopt the driver pie graph of display panel of pixel of the display device of the 4th embodiment of the present invention.In Figure 26, a pixel 456 is equivalent to image element circuit described later.Have on the display panel be used for to a plurality of pixels 456 that are configured to two-dimensional-matrix-like send the numerical data of 3 bits horizontal driver 457, be used to drive the power circuit 458 of pixel and the vertical driver 459 of selecting the line of vertical direction.

A plurality of pixels 456 are configured to the two-dimensional-matrix-like that the row X by capable Y that arranges in vertical direction and arrangement in the horizontal direction forms.As an example, 4 of expression Y1～Y4 goes, the display panels of 6 row of X1～X6 among Figure 26.Actual display panel is more than ranks shown in Figure 26, but, and expression for convenience and so herein.

In the 4th embodiment, assemble data driver 471～476 in the horizontal driver 457, assembled power supply unit 481～486 in the power circuit 458, assembled gate drivers 491～494 in the vertical driver 459.In addition, herein horizontal driver 457 and vertical driver 459 as the 2nd drive division.

For example, in the occasion that will scan as the capable display line of the higher level's of display panel shown in Figure 26 Y1, the gate drivers 491 of vertical driver 459 makes each capable pixel 456 conducting of Y1.Other display line Y2 is capable～and Y4 is capable to be ended by gate drivers 492～494.Offer each pixel 456 from the data of 1 line of horizontal driver 457 image output data this moment.

Secondly, gate drivers 491 ends each capable pixel 456 of Y1, thereby shows the image of 1 line that Y1 is capable.Then same, gate drivers 492 to Y4 capable gate drivers 494 orders that Y2 is capable drive vertical driver 459, press per 1 line image output data from horizontal driver 457, thereby just can scan the pixel 456 in all display panels.

Figure 27 represents to be used to drive the circuit diagram of the pixel of the 4th embodiment of the present invention.In Figure 27, be equivalent to luminescence unit shown in Figure 25 434,435 and 436 with 434,435 and 436 of the sign flag of light emitting diode.In the 4th embodiment, 3 layers of structure of numeral layer expression, luminance weighted and Fig. 3 (a) of each organic membrane luminescent layer of formation numeral layer is identical, is " 1 ", " 2 ", " 4 ".

Also have, each end (being anode among the figure) of luminescence unit 434～436 is connected with the power supply 450～452 that constitutes power supply unit 481 by driving each source electrode, the drain electrode with TFT444～446.Also have, each grid of TFT444～446 is connected with each source electrode of TFT447～449, is connected with power supply 450～452 by capacitor 441～443 on the other hand.

Power supply 450～452 can be an independent current source, also can be common source, sets luminescence unit 434～436, makes it luminous with the weighting of regulation, in accordance with regulations brightness.And each drain electrode of TFT447～449 is connected with the data maintaining part 460～462 in the data driver 471, and each grid and gate drivers 491 connect altogether.

, represented data driver 471, power supply unit 481, gate drivers 491 herein, but, as shown in figure 27, data driver 472～476, power supply unit 482～486, gate drivers 492～494 also are identical formations.Data driver 471～476, power supply unit 481～486, gate drivers 491～494 drives each row Y of display panels, respectively is listed as the pixel 456 of X.

Secondly, the action of this driving circuit is described.At first, the data 453 (3 bit) of the regulation gray shade scale that shows on the pixel 456 input data driver 471.Data 453 are the serial data or the parallel data of numeral preferably.The data of having been imported by data driver 471 453 are used for making the corresponding luminescence unit of gray-scale displayed grade on the display device with luminescence unit 434,435,436 luminous.

Each bit of data 453 (1 or 0) is kept by data maintaining part 460～462, and the grid of 491 pairs of gate transistors 447～449 of gate drivers applies the 1st current potential of regulation, makes it become conducting state.From the data of data driver 471 output each drain electrode, source electrode, write, be stored in and be used for the capacitor 441～443 that data keep by gate transistor 447～449.

Then, the grid of 491 pairs of gate transistors 447～449 of gate drivers applies the 2nd current potential of regulation, makes it become cut-off state.Gate transistor 447～449 is ended, and the electric charge of having put aside on capacitor 441～443 just is held.The electric charge that is kept by capacitor 441～443 is the potential difference (PD) of the output voltage of power supply 450～452 and data driver 471.

Illustrative examples is as the situation of the image of display gray scale grade " 5 " on display device now.With reference to Fig. 4, gray shade scale " 5 " need make the luminescence unit 434 and 436 of the 1st layer and the 3rd layer light.The data of having imported 453 are transformed to the data rows related with the signal wire of corresponding luminescent layer by data driver 471.In this occasion, keeping making luminescence unit 434 and 436 luminous data in the data maintaining part 460 and 462.

Apply the voltage that makes TFT444 conducting on the capacitor 441 this moment, also apply the voltage that makes the TFT446 conducting on the capacitor 443, thereby TFT444 and 446 becomes conducting state respectively.On the other hand, do not apply the voltage of drive TFT 445 on the capacitor 442, thereby TFT445 is a cut-off state.

Therefore, TFT444 and 446 is a conducting state, thus from power supply 450,452 by TFT4444, each drain electrode of 446, source electrode provides electric current to luminescence unit 434,436, luminescence unit 434,436 will be luminous.This moment luminescence unit 434,436 being weighted to of luminosity " 1 " and " 4 ", thereby on display device, shown as the gray shade scale " 5 " of its summation.

In the digital drive method of the display panel of the 4th embodiment, drive and only carry out conduction and cut-off with TFT444～446 and move.Therefore circuit constitutes and comprises that savings is used for making the gating that drives with the capacitor 441～443 of the data of TFT444～446 conduction and cut-off and be used for keeping above-mentioned data at these capacitors 441～443 to get final product with the very simple circuit formation of TFT447～449.

Also have, drive with TFT444～446 and only carry out the conduction and cut-off action, thereby move the zone of saturation that the caused threshold deviation of element characteristic of the problematic TFT as active component of organic EL display that can be former does not have to influence.Therefore, can infinitely reduce the interior problems such as the not even gray shade scale deviation of display brightness of display panel.

Have again, can move few zone of saturation in the electric power loss of TFT.Therefore, compared, can reduce consumption of electric power with former display device.

In the element of the 4th embodiment, luminescence unit 434～436 has adopted the multi-photon structure, thereby can obtain above in the past brightness under the situation that has reduced the electric current that flows through each organic membrane luminescent layer.2 powers of the life-span of organic EL and current value are inversely proportional, thereby compare with former circuit formation, can life-saving.

Have, show that for carrying out numeral each luminescence unit adopts multi-photon, this each luminescent layer uses the material of identical characteristics, thereby just can easily obtain the gray shade scale that numeral shows the brightness of required integral multiple.

In addition, the present invention for example, can constitute from the 1st layer to the 3rd layer with identical materials or different materials shown in above first embodiment to the, four embodiments, or from the 1st layer to the 5th layer organic membrane luminescent layer (light-emitting component).For example, even the material of organic membrane luminescent layer is inequality, as mentioned above, as long as for each organic membrane luminescent layer, make current value and flow through the time length difference of electric current, thereby the brightness as sum is constituted in the occasion of Fig. 3 (a), the 1st layer is " 1 ", and the 2nd layer is " 2 ", and the 3rd layer is " 4 ", occasion at Fig. 3 (b) constitutes, the 1st layer is " 1 ", and the 2nd layer is " 2 ", and the 3rd layer is " 4 ", the 4th layer is " 8 ", and the 5th layer is that " 16 " get final product.

Also have, organic membrane luminescent layer and luminescence unit luminance weighted preferably can form 2 n power luminance weighted of luminescent layer less, but, is not so limited.Also have, the weighting of every layer brightness, needn't be shown in Fig. 3 (a), 3 (b) from layer ascending order near a side of taking out light, but can change descending into, or arrangement arbitrarily.

Have again, for example illustrated among Fig. 4 that each luminescent layer is different luminance weighted, but, is not so limited.For example, the 1st layer, the luminance weighted of layers 2 and 3 can be made as " 1 ", " 1 ", " 1 " so identical luminance weightedly, also can be made as identical luminance weighted of as " 1 ", " 2 ", " 2 " part.

Also have, the invention is not restricted to organic EL, inorganic EL realizes certainly that also be not limited to active driving, the display device of passive drive also can realize.Have again,, do not need to be used to constitute a plurality of secondary image elements of a pixel according to element of the present invention, thus can be fully the high resolving powerization of corresponding panel from now on.

Industrial applicibility

The present invention can be applicable to and adopt electroluminescent display device.And go in the display device beyond the electroluminescence can be the display device of the stacked structure for multilayer of luminescent layer.Also have, go for the display device from small-sized to large-scale, high-grade and long-life display device can be provided.

Claims (9)

1. display device constitutes 1 pixel by the point of a plurality of looks, is arranged with a plurality of pixels, it is characterized in that having:

Stacked n (n be 2 and above natural number) luminescent layer forms the light-emitting component of each point;

Drive described n luminescent layer of described light-emitting component, make its luminous or non-luminous the 1st drive division;

Make electric current flow through the power supply of described light-emitting component by described the 1st drive division; And

Under the state of the weighting of a described n luminescent layer having been set luminosity, drive a described n luminescent layer, make it luminous, thereby show the 2nd drive division of the gray shade scale of described each point.

2. display device as claimed in claim 1, it is characterized in that, a described n luminescent layer is flow through the time length of described electric current to described the 2nd drive division handle and the side in the current value is set at same value, the opposing party is set at the value of m kind (m is n and following natural number), thereby sets the weighting of m kind.

3. display device as claimed in claim 1, it is characterized in that, described the 2nd drive division is set at the value of m kind (m is n and following natural number) to the combination of time length that a described n luminescent layer is flow through described electric current and current value, thereby sets the weighting of m kind.

4. display device as claimed in claim 2, it is characterized in that, described the 2nd drive division switches respectively the weighting of a described n luminescent layer with a frame or unit, makes at least one side circulation primary during n frame or n field of the time length of the current value of described m kind and described m kind.

5. display device as claimed in claim 3 is characterized in that, described the 2nd drive division switches respectively the weighting of a described n luminescent layer with a frame or unit, make described m kind be combined in n frame or n field during circulation primary.

6. display device as claimed in claim 1 is characterized in that, described the 2nd drive division has:

M on the described n luminescent layer (m is n and following natural number) luminescent layer carried out the digital drive portion of digital drive; And

(n-m) individual luminescent layer is carried out analog-driven, make it come luminous analog-driven portion with the middle gray level.

7. display device as claimed in claim 6 is characterized in that,

Described digital drive portion sets the weighting of described m and following kind to a described m luminescent layer,

Described analog-driven portion sets described (n-m) individual luminescent layer and makes it luminous with a described m luminescent layer, thus the weighting that shows the gray shade scale of described each point.

8. display device constitutes 1 pixel by the point of a plurality of looks, is arranged with a plurality of pixels, it is characterized in that having:

Stacked n (n be 2 and above natural number) unit element forms the light-emitting component of each point, wherein, described unit element stacks gradually anode, illuminating part, negative electrode and forms, and described illuminating part is by the organic membrane luminescent layer of m layer (m is a natural number) and (m-1) the alternately laminated multi-photon structure that forms of charge generating layers of layer;

Drive described illuminating part, make its luminous or non-luminous the 1st drive division; And

Under the state of the weighting of the luminescent layer of the n on the described light-emitting component having been set luminosity, drive a described n illuminating part, make it luminous, thereby show the 2nd drive division of the gray shade scale of described each point.

9. display device as claimed in claim 8 is characterized in that, is clipped in 2 layers of described charge generating layers between the described organic membrane luminescent layer and injects electronics to side's organic membrane luminescent layer, to the opposing party's organic membrane luminescent layer injected hole.

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