JP2010021098A - Display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL display device having a structure formed by laminating organic luminescent layers and having little unevenness in display. <P>SOLUTION: Pixels P1, P2 in which two or more luminescent layers 12, 14, 16 are laminated, intermediate electrodes 13a, 13b, 15a, 15b are disposed between two or more luminescent layers, and a repeller 21 and a light extracting electrode 11 are each disposed so as to hold the two or more laminated luminescent layers between them are two dimensionally disposed on a substrate 10 to form this display device. As to the two pixels P1, P2 adjacent to each other, the light extracting electrode and the repeller are connected with each other in the same layer, and they have equal potential. As to at least the two pixels adjacent to each other, the light extracting electrodes are electrically connected with each other and the repellers are connected with each other, and the light extracting electrodes are electrically connected with the repellers. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a display device, and more particularly to a display device using a stacked light emitting element, particularly a light emitting element in which organic EL elements are stacked.

In the organic EL display device, a display device has been proposed in which a pixel is a stacked light emitting element in which two or more organic EL light emitting layers of different colors are stacked. In the organic EL device disclosed in Patent Document 1, one pixel is composed of two subpixels, and two light emitting elements are stacked in one subpixel (FIG. 1 of Patent Document). The two stacked light-emitting elements have a first electrode, a first organic light-emitting layer, a transparent common electrode, a second organic light-emitting layer, and a second electrode. The transparent common electrode is supplied with a potential by a lead-out wiring. (FIG. 3 of Patent Document 1). The first electrode and the second electrode are connected in common by a contact hole for each subpixel.
Japanese Patent Laid-Open No. 2005-174639

  However, in order to connect the first electrode serving as the lower electrode and the second electrode serving as the upper electrode, it is necessary to provide contact holes in the first and second organic light emitting layers, that is, the two organic light emitting layers. In this case, it is required to form a contact hole for each subpixel while avoiding a short circuit with the transparent common electrode, which affects the yield in the manufacturing process. If a sufficient margin is provided between the transparent common electrode and the contact hole in order to avoid a short circuit with the transparent common electrode, the aperture ratio is reduced.

  The present invention has been made to solve the above-described problems of the prior art, and for each pixel (or subpixel), a contact hole is formed between the first electrode and the second electrode. Is to provide a display device such as an organic EL display device.

In the display device of the present invention, two or more light-emitting layers of the display device are laminated, and each intermediate electrode is disposed between the two or more light-emitting layers. In a display device in which pixels each having a first electrode and a second electrode arranged so as to sandwich a pixel are two-dimensionally arranged on a substrate,
The intermediate electrode is provided separately for each pixel,
For the plurality of pixels arranged in at least one direction, the first electrode is connected in the same layer,
The second electrode is connected in the same layer for at least the pixels arranged in one direction or the other direction.

  According to the present invention, since the intermediate electrode is provided separately for each pixel and the first electrode and the second electrode are connected in the same layer, the first electrode and the second electrode are A contact hole for connection need not be provided for each pixel, and the aperture ratio is improved. And by improving the aperture ratio, the current density per light emitting area can be kept low, and as a result, the lifetime can be improved.

Hereinafter, embodiments of a display device according to the present invention will be described with reference to the drawings. In addition, the well-known or well-known technique of the said technical field is applied regarding the part which is not illustrated or described in particular in this specification. The embodiment described below is one embodiment of the present invention and is not limited thereto.
(First embodiment)
FIG. 1 is a top view showing an example of a pixel arrangement of an organic EL display device which is a first embodiment of a display device according to the present invention. FIG. 2 is a diagram schematically showing a detailed cross-sectional structure in one pixel region. FIG. 3 is a perspective view showing the arrangement of electrodes of the organic EL display device according to the first embodiment. FIG. 4 is a perspective view of the organic EL display device of the first embodiment. The pixel array shown in FIG. 1 and the pixels having the cross-sectional structure shown in FIG. 2 constitute the display region 1 of the organic EL display device shown in FIG. In FIG. 4, 2 indicates a pixel.

  The configuration of an embodiment of the organic EL display device according to the present invention will be described with reference to FIG. Two pixels (first pixel P1 and second pixel P2) arranged in parallel constitute one component that displays one unit of an image signal, and each pixel P1 and P2 has three layers of light emitting elements. It is constructed by stacking. Each pixel is two-dimensionally arranged on the insulating substrate 10. Each light emitting element has a structure in which an organic EL layer including a light emitting layer that emits light of different colors is sandwiched between electrodes.

  The organic EL layer is a single layer type (light emitting layer), two layer type (light emitting layer / hole injection layer), three layer type (electron transport layer / light emitting layer / hole transport layer), four layer type (electron injection layer) / Light emitting layer / hole transporting layer / hole injection layer), and adopting any structure of 5 layers type (electron injection layer / electron transport layer / light emitting layer / hole transport layer / hole injection layer). May be.

  As shown in FIG. 2, the organic EL display device according to this embodiment is a bottom emission type organic EL display device. On the insulating substrate 10 having translucency, the light extraction electrode 11, the first organic light emitting layer 12, the first intermediate electrodes 13a and 13b, the second organic light emitting layer 14, the second intermediate electrodes 15a and 15b, and the third organic The light emitting layer 16, the reflective electrode 21, and the protective layer 22 are provided, and the pixel P1 and the pixel P2 are configured. The light extraction electrode 11 is a first electrode, and the reflection electrode 21 is a second electrode. The light extraction electrode 11 and the reflection electrode 21 are formed so as to sandwich the three stacked organic light emitting layers. The intermediate electrodes 13a, 13b, 15a, and 15b are formed between the organic light emitting layers, and are provided in a shape separated for each pixel. In the pixel P1, the first intermediate electrode 13a and the second intermediate electrode 15a are short-circuited, and in the pixel P2, the first intermediate electrode 13b and the reflective electrode 21 are short-circuited.

  The light extraction electrode 11 is made of a translucent conductive material. The reflective electrode 21 is made of a highly reflective conductive material. The light emitted from each pixel is extracted through the insulating substrate 10.

  The first organic light-emitting layer 12, the second organic light-emitting layer 14, and the third organic light-emitting layer 16 are all in the same order from the bottom to the electron transport layer / light-emitting layer / hole transport layer (that is, three layers of the above layer configuration) Type). A driving TFT, a switch TFT, and the like are formed on the insulating substrate 10 as necessary, and the driving TFT and the intermediate electrode are connected. FIG. 3 shows a case where the driving TFT is formed on the insulating substrate 10.

  As shown in FIG. 3, each of the light extraction electrode 11 and the reflection electrode 21 is formed of a common solid electrode over a display region composed of two-dimensionally arranged pixels. In FIG. 3, the first intermediate electrodes 13 a and 13 b are shown as the intermediate electrode 13, and the second intermediate electrodes 15 a and 15 b are shown as the intermediate electrode 15. When the intermediate electrodes 13a, 13b, 15a, 15b are connected to the driving TFT provided on the insulating substrate, a contact hole for connection is formed in the light extraction electrode 11. Here, reference numeral 102 denotes a driving TFT.

  Between the adjacent pixels P1 and P2, as shown in FIG. 2, the light extraction electrode 11 and the reflection electrode 21 are common electrodes, respectively. Further, the light extraction electrode 11 and the reflection electrode 21 are connected and supplied with the same voltage. The connection point between the light extraction electrode 11 and the reflection electrode 21 may be inside or outside the display area, but in this embodiment, as shown in FIG. 3, electrical connection is performed outside the display area. . When the light extraction electrode 11 and the reflection electrode 21 are connected in the display area, contact holes can be provided in the display area at an appropriate interval such as one in three pixels. Any number of contact holes for conducting the light extraction electrode 11 and the reflection electrode 21 may be arranged in the display region so that the potential of the reflection electrode 21 is kept equal.

  As the electrode material of the light extraction electrode 11, a material having high transmittance is preferable. For example, a transparent conductive film such as ITO, IZO, or ZnO, or a semi-transmissive film in which a metal such as Ag, Au, or Al is formed to a thickness of about 10 nm to 30 nm may be used. In order to reduce the sheet resistance of the light extraction electrode 11, it is possible to set the film thickness of the metal semi-transmissive film to an appropriate value by combining a transparent conductive film and a metal having a low sheet resistance.

  The planar layout of the light extraction 11, the first intermediate electrode 13, the second intermediate electrode 15, and the reflective electrode 21 will be described with reference to FIGS.

  In this embodiment, since the light extraction 11 and the reflection electrode 21 are formed of a solid electrode extending over the display area, the light extraction 11 and the reflection electrode 21 of all adjacent pixels are connected by a continuous film connected in the same layer. Will do.

  The first intermediate electrodes 13a and 13b and the second intermediate electrodes 15a and 15b are composed of pattern electrodes corresponding to the respective pixels. The light extraction electrode 11 and the reflection electrode 21 are formed as electrodes common to all adjacent pixels and are connected outside the display region of FIG. The connected light extraction electrode 11, the reflection electrode 21, and the second intermediate electrodes 15a and 15b are connected to the power source 23 in FIG.

  The pattern of the light extraction electrode 11 and the pattern of the reflection electrode 21 are related to the display method of the organic EL display device. For example, in the configuration of FIG.

  In the present embodiment, because of the configuration described above, the light extraction electrode 11 and the reflection electrode 21 have the same potential in all the pixels within the display area plane.

  By applying a positive or negative potential to the second intermediate electrode 15a on the basis of this potential, the first organic light-emitting layer 12 and the third organic light-emitting layer 12 in which the electrodes of the three organic light-emitting layers stacked in the pixel P1 are not short-circuited. A current flows through one of the light emitting layers 16. Then, the light emitting layer through which the current flows can emit light. Further, by applying a positive or negative potential to the second intermediate electrode 15b, the second organic light-emitting layer 14 and the third organic light-emitting layer 16 in which the electrodes of the three organic light-emitting layers stacked in the pixel P2 are not short-circuited are provided. Current flows through either one. Then, the light emitting layer through which the current flows can emit light. Which organic light emitting layer emits light is determined by the polarity of the potential of the intermediate electrode. The driving method is described in more detail below. In the present embodiment, the light extraction electrode 11 and the reflection electrode 21 are formed as a common electrode for all adjacent pixels and are connected outside the display region, so that the contact for connecting the light extraction electrode 11 and the reflection electrode 21 is used. It is not necessary to provide a hole for each pixel. As a result, the aperture ratio is improved, the current density per light emitting area can be kept low, and the life of the organic light emitting layer is improved.

  In the present embodiment, the light extraction electrode 11 and the reflection electrode 21 are both formed as a solid electrode (common electrode). Accordingly, when any display pattern that can be displayed as an organic EL display device is formed, shading caused by the reflective electrode and the light extraction electrode is unlikely to occur. In order not to recognize the shading, the potential difference between the pixels is preferably ± 1 mV or less. The potential difference ± 1 mV is the amount of voltage drop between pixels necessary to suppress the voltage drop to the allowable luminance distribution limit or less at the end and center of the display area.

  The potential difference ± 1 mV was calculated as follows. When the voltage width required for light emission control is 3V (controls from the non-light emitting state to the maximum luminance within the range of 3V) and a luminance distribution of ± 5% occurs in the display area plane, it is recognized as display unevenness. Set. When the resolution is QVGA (320 × 240 pixels), the number of long side pixels up to the central pixel of the display area is set to 160. 3v × (± 0.05) /160=±0.94 mV, and considering the error, it can be seen that it is preferably ± 1 mV or less.

  In the present embodiment, since the light extraction electrode 11 and the reflection electrode 21 are both formed as a solid electrode (common electrode), the potential difference between the pixels can be ± 1 mV or less. Therefore, in the configuration of the present embodiment, it is possible to suppress potential unevenness in the light extraction electrode 11 and the reflection electrode 21 that are common electrodes in the display area surface, and to suppress the occurrence of shading.

  A first organic light emitting layer is deposited on the substrate on which the light extraction electrode 11 is formed by a known means.

  For the first organic light emitting layer, at least one selected from an organic light emitting material, a hole injection material, an electron injection material, a hole transport material, and an electron transport material can be used. The range of color selection can be expanded by doping the hole injection material or the hole transport material with an organic light emitting material, or doping the electron injection material or the electron transport material with an organic light emitting material. Furthermore, the organic light emitting layer is preferably an amorphous film from the viewpoint of light emission efficiency.

  Organic light-emitting materials for each color include triarylamine derivatives, stilbene derivatives, polyarylenes, aromatic condensed polycyclic compounds, aromatic heterocyclic compounds, aromatic heterocyclic condensed ring compounds, metal complex compounds, etc., and single oligos or composites thereof. Oligobodies can be used. However, the material of the present embodiment is not limited to these exemplified materials.

  The organic light emitting layer may be a layer having a single function of hole injection, hole transport, electron injection, or electron transport, or a layer having a composite function.

  The thickness of the organic light emitting layer is preferably about 0.05 μm to 0.3 μm, and preferably about 0.05 to 0.15 μm.

  As the hole injection and transport material, a phthalocyanine compound, a triarylamine compound, a conductive polymer, a perylene compound, an Eu complex, or the like can be used, but the structure of the present invention is not limited.

  As an example of the electron injection and transport material, Alq3 in which a trimer of 8-hydroxyquinoline is coordinated to aluminum, an azomethine zinc complex, a distyrylbiphenyl derivative system, or the like can be used.

  Next, a contact hole 18b is formed. As a forming method, laser processing is preferable, and a YAG laser (including SHG and THG), an excimer laser, or the like generally used for thin film processing is used. These laser beams are scanned with being reduced to several μm, or are irradiated on the substrate in a predetermined pattern through a mask that transmits the contact hole portion as a planar light source. The diameter of the contact hole is preferably 2 μm to 15 μm.

  Next, a transparent electrode is formed and patterned to form first intermediate electrodes 13a and 13b. At this time, the light extraction electrode 11 and the first intermediate electrode 13b are connected through the contact hole 18b. As the electrode material, a material having high transmittance is preferable. For example, the electrode material is preferably made of a transparent conductive film such as ITO, IZO, ZnO, or an organic conductive film such as polyacetylene. It may be a semi-permeable membrane formed about 30 nm. The patterning method can be performed by the laser processing described above. Alternatively, the electrode material may be formed by heating and vapor deposition using a metal mask. Alternatively, the substrate on which the electrode material is formed may be transferred to the substrate 10 by laser ablation.

  Next, the second organic light emitting layer 14, the contact hole 19a, the second intermediate electrodes 15a and 15b, and the third organic light emitting layer 16 are sequentially formed by the same method as described above. As the material of the second intermediate electrodes 15a and 15b, a material having a high transmittance is preferable like the first intermediate electrodes 13a and 13b.

  Next, the reflective electrode 21 is formed by sputtering, vapor deposition, or the like. The electrode material is preferably a light-reflective member, and is preferably made of a film in which a metal such as Cr, Al, Ag, Au, or Pt is formed to a thickness of about 50 to 300 nm. This is because the higher the reflectance, the higher the light extraction efficiency. The reflective electrode having the above-described configuration can reduce the sheet resistance, and the occurrence of a potential drop in the display area plane can be suppressed to a very small level.

  Further, silicon nitride oxide was formed as the protective film 22 to obtain an organic EL display device.

  An equivalent circuit of the organic EL display device thus formed is shown in FIG.

  In FIG. 5, the pixel circuit of each pixel includes switching TFTs 101a and 101b, driving TFTs 102a and 102b, organic light emitting elements 12a to 16a and 12a to 16a, and capacitors 103a and 103b.

  Here, the gate electrodes of the switching TFTs 101 a and 101 b are connected to the gate signal line 105. The source electrodes of the switching TFTs 101a and 101b are connected to the source signal lines 106a and 106b, and the drain electrodes are connected to the gate electrodes of the driving TFTs 102a and 102b. The source electrodes of the driving TFTs 102a and 102b are connected to the power supply line 107, and the drain electrodes are connected to the anode electrodes of the organic EL elements 16a and 16b. The source electrode of the driving TFT 102a is connected to the cathode electrode of the organic EL element 12a, and the organic EL element 14a is short-circuited between the anode electrode and the cathode electrode. The source electrode of the driving TFT 102b is connected to the cathode electrode of the organic EL element 14b, and the anode electrode and the cathode electrode of the organic EL element 12b are short-circuited.

  Referring to FIG. 2, in the first pixel P1, the source electrode of the driving TFT 102a is connected to the second intermediate electrode 15a, and in the second pixel P2, the source electrode of the driving TFT 102b is the second pixel. Connected to the intermediate electrode 15b. The cathode electrodes of the organic EL elements 16a and 16b are connected to the reflective electrode 21 in FIG. 5 (corresponding to the reflective electrode 21 in FIG. 2), and the anode electrodes of the organic EL elements 12a and 12b are the light extraction electrodes 11 in FIG. (Corresponding to the first electrode 11 in FIG. 2). Further, the capacitors 103a and 103b are formed so that the electrodes are connected to the gate electrodes of the driving TFTs 102a and 102b and GND (not necessarily GND but any fixed potential). In this way, the driving TFTs 102a and 102b and the organic EL elements 16a, 12a, 16b, and 14b are connected, and the current flowing through the organic EL elements 16a, 12a, 16b, and 14b is controlled by the driving TFTs 102a and 102b. .

  In the present embodiment, the driving TFT is connected to the second intermediate electrodes 15a and 15b, and the light extraction electrode 11 and the reflection electrode 21 are connected to all the pixels as a common electrode. Further, the light extraction electrode 11 and the reflection electrode 21 are electrically connected outside the display area and have the same potential. With the above configuration, the light extraction electrode 11 formed on the substrate can be easily provided with a function as a power supply line, the potential drop of the common electrode can be extremely small, and shading can be suppressed. Can do.

  Next, a driving method of the organic EL device having the above structure will be described with reference to FIG. FIG. 6 is a diagram showing an example of a driving waveform of the organic EL display device by the power supply means 23.

  At time t1, when the potential of the gate signal line 105 is set to Vg, the switching TFTs 101a and 101b are turned on. Then, the potential Vsig1 of the source signal lines 106a and 106b is charged to the gate capacitances of the capacitors 103a and 103b and the driving TFTs 102a and 102b via the switching TFTs 101a and 101b.

  At time t2, the potential of the gate signal line 105 is set to 0V, the switching TFTs 101a and 101b are turned off, and the voltages charged in the capacitors 103a and 103b are held.

  At time t3, the potentials of the light extraction electrode 11 and the reflection electrode 21 are set to Vc. At this time, since the power supply line 107 remains at 0 V, a potential difference is generated between the organic light emitting layer and the source and drain of the driving TFTs 102a and 102b. As a result, electrons are injected from the first intermediate electrode 13a and the second intermediate electrode 15b into the first organic light emitting layer 12 and the second organic light emitting layer 14, and holes are injected from the light extraction electrode 11 and the first intermediate electrode 13b. Is done. Then, light emission is obtained when organic molecules excited by recombination of electrons and holes relax to the ground state, and the emitted light is emitted from the insulating substrate 10 side. Thus, the organic EL elements 12a and 14b emit light. The third organic light emitting layer 16 does not emit light because a reverse voltage is applied. The current flowing in the first organic light emitting layer 12 and the second organic light emitting layer 14 is controlled by the driving TFTs 102a and 102b, and the current between the source and drain of the driving TFTs 102a and 102b is controlled according to the voltage charged in the capacitors 103a and 103b. I1 flows. This state is maintained until time t4.

  At time t4, the potentials of the light extraction electrode 11 and the reflection electrode 21 are set to 0V. Then, since there is no potential difference between the organic light emitting layer and the source and drain of the driving TFTs 102a and 102b, the first organic light emitting layer 12 and the second organic light emitting layer 14 do not emit light. Subsequently, a signal Vsig2 for causing the third organic light emitting layer to emit light is set to the source signal lines 106a and 106b.

  At time t5, the potential of the gate signal line 105 is set to Vg. The switching TFTs 101a and 101b are turned on, and the potential Vsig2 of the source signal lines 106a and 106b is charged to the gate capacitors of the capacitors 103a and 103b and the driving TFTs 102a and 102b via the switching TFTs 101a and 101b.

  At time t6, the potential of the gate signal line 105 is set to 0V, the switching TFTs 101a and 101b are turned off, and the voltages charged in the capacitors 103a and 103b are held.

  At time t7, the potential of the power supply line 107 is set to Vc. At this time, since the potentials of the light extraction electrode 11 and the reflection electrode 21 are 0 V, a potential difference is generated between the organic light emitting layer and the source and drain of the driving TFTs 102a and 102b. Thereby, electrons are injected from the reflective electrode 21 into the third organic light emitting layer 16 and holes are injected from the second intermediate electrodes 15a and 15b. Then, light emission is obtained when organic molecules excited by recombination of electrons and holes relax to the ground state, and the emitted light is emitted from the insulating substrate 10 side. Thus, the organic EL elements 16a and 16b emit light. The first organic light emitting layer 12 and the second organic light emitting layer 14 do not emit light because a reverse voltage is applied. The current flowing in the light emitting layer is controlled by the driving TFTs 102a and 102b, and a current I2 flows between the source and drain of the driving TFTs 102a and 102b in accordance with the voltage charged in the capacitors 103a and 103b. This state is maintained until time t8.

  At time t8, the potential of the power supply line 107 is set to 0V. Then, since there is no potential difference between the organic light emitting layer and the source and drain of the driving TFTs 102a and 102b, the third organic light emitting layer 16 does not emit light.

  By repeating the above operation, the organic light emitting layers 12, 14, and 16 can emit light in a time division manner. Specifically, the power source 23 is driven at a period that cannot be identified by humans, for example, about 60 Hz or higher, so that the emission colors of the first organic light-emitting layer 12 and the second organic light-emitting layer 14 and the third organic light emission. Light of any mixed color with the emission color of the layer 16 can be expressed. The power source 23 serves as a voltage application unit.

  In such an organic EL display device, it is possible to suppress shading by suppressing potential unevenness in the light extraction electrode 11 and the reflection electrode 21 which are common electrodes in the display region plane. Therefore, display unevenness can be reduced or eliminated.

  In the present embodiment, a configuration in which a bottom emission type stacked organic EL display device that extracts light from the substrate side is displayed by active matrix driving is shown. However, the same effect can be obtained even in a configuration in which a top emission type stacked organic EL display device that extracts light on the side opposite to the substrate is displayed by active matrix driving.

Furthermore, since it is not necessary to provide a contact hole for connecting a common electrode for each pixel, the aperture ratio is improved, and the current density per light emitting area can be kept low, leading to an improvement in life.
(Second Embodiment)
7 and 8 are perspective views showing an example of a pixel arrangement of an organic EL display device which is a second embodiment of the display device according to the present invention. FIG. 9 is a diagram schematically showing a detailed cross-sectional structure in one pixel region. The display region 1 of the organic EL display device shown in FIG. 4 is configured by the pixel array shown in FIG. 7 or FIG. 8 and the pixels having the cross-sectional structure shown in FIG.

  FIG. 9 is a diagram schematically showing a cross section of an organic EL display device according to the second embodiment of the present invention. In FIG. 9, the organic EL display device according to the present embodiment is a top emission type organic EL display device. In the organic EL display device according to the present embodiment, one component that displays one unit of an image signal includes a first pixel P1 and a second pixel P2. 30 is an insulating substrate, 31 is a reflective electrode, 32 is a first organic light emitting layer, 33a and 33b are first intermediate electrodes, 34 is a second organic light emitting layer, 35a and 35b are second intermediate electrodes, and 36 is a third organic light emitting layer. The light emitting layer, 41 is a light extraction electrode, and 38b and 39a are contact holes. Reference numeral 42 denotes a protective layer having translucency. The light emitted from each pixel is extracted through the light extraction electrode 41. The intermediate electrodes 33a, 33b, 35a, and 35b are provided separately for each pixel.

  Each of the first organic light emitting layer 32, the second organic light emitting layer 34, and the third organic light emitting layer 36 has a four-layer structure, and is composed of an electron injection layer / electron transport layer / light emitting layer / hole transport layer. .

  If necessary, a reflective electrode 31 is formed in the pixel region on the insulating substrate 30 on which the drive TFT, the switch TFT, and the like are formed.

  The layout of the reflective electrode 31, the first intermediate electrode 33, the second intermediate electrode 35, and the light extraction electrode 41 will be described with reference to FIGS.

  The configuration example of FIG. 7 shows a case where both the reflective electrode 31 and the light extraction electrode 41 are connected by a continuous film connected in the same layer as the pixels adjacent in the X-axis direction. In the configuration example of FIG. 8, the reflective electrode 31 is electrically connected to a pixel adjacent in the X-axis direction, and the light extraction electrode 41 is electrically connected by a continuous film connected in the same layer as the pixel adjacent to the Y-axis direction. Show. Here, a plurality of pixels arranged in one direction means a plurality of pixels arranged in the X direction, and a plurality of pixels arranged in the other direction means a plurality of pixels arranged in the Y direction. A plurality of pixels arranged in one direction may be a plurality of pixels arranged in the Y direction, and a plurality of pixels arranged in the other direction may be a plurality of pixels arranged in the X direction.

  The 1st intermediate electrode 33 and the 2nd intermediate electrode 35 are comprised from the pattern electrode corresponding to each pixel. The reflective electrode 31 and the light extraction electrode 41 are electrically connected by connecting a continuous film connected in the same layer outside the display region of FIG. The reflective electrode 31, the light extraction electrode 41, and the second intermediate electrode 35 are connected to the power supply 43 in FIG.

  Also in this embodiment, the first intermediate electrode 33 and the second intermediate electrode 35 of each pixel are configured as separated electrodes, and the reflective electrode 31 and the light extraction electrode 41 are formed as electrodes common to adjacent pixels. . Therefore, a contact hole for connecting the reflective electrode 31 and the light extraction electrode 41 may not be provided for each pixel. As a result, the aperture ratio is improved, the current density per light emitting area can be kept low, and the life of the organic light emitting layer is improved.

  7 shows a case where the pattern of the reflective electrode 31 and the pattern of the light extraction electrode 41 match, and FIG. 8 shows a case where the pattern of the reflection electrode 31 and the pattern of the light extraction electrode 41 intersect. However, the pattern of the reflective electrode 31 and the pattern of the light extraction electrode 41 are not limited to the above embodiment, and how the pattern of the reflection electrode 31 and the pattern of the light extraction electrode 41 that connect adjacent pixels are arranged. It does not matter.

  The pattern of the reflective electrode 31 and the pattern of the light extraction electrode 41 are related to the display method of the organic EL display device. For example, line-sequential driving is possible in the configuration of FIG. 7, and dot-sequential in the configuration of FIG. Drive can be performed. Specifically, driving for each line, line inversion pattern driving, dot inversion pattern driving, or the like can be selected.

  In any of the electrode patterns described above, the electrode pattern width can be secured to about the pixel width, and by setting the electrode film thickness to an appropriate value, the sheet resistance is reduced, and the potential drop is reduced between adjacent pixels. can do.

  The reflective electrode 31 is preferably a light-reflective member, and is preferably formed of a film in which a metal such as Cr, Al, Ag, Au, or Pt is formed to a thickness of about 50 to 300 nm. This is because the higher the reflectance, the higher the light extraction efficiency. The reflective electrode 31 is a common electrode in the X direction, and is conductive by a continuous film connected in the same layer between adjacent pixels.

  Contact holes 38b and 39a are formed by laser processing, the first intermediate electrode 33a and the second intermediate electrode 35a of the first pixel P1 are connected, and the reflective electrode 31 and the first intermediate of the second pixel P2 are connected. The electrodes 33b are connected to each other.

  The reflective electrode 31 having the above-described configuration can reduce the sheet resistance, and the occurrence of a potential drop in the display area plane can be suppressed to an extremely low level.

  In the present embodiment, because of the above-described configuration, the reflection electrode 31 and the light extraction electrode 41 that simultaneously perform light emission drive have the same potential in the pixels in the display area plane. In any pixel, the potentials of the reflective electrode and the light extraction electrode are equal in at least two adjacent pixels. Therefore, in the configuration of the present embodiment, it is possible to suppress potential unevenness in the reflective electrode 31 and the light extraction electrode 41 that are common electrodes in the display area surface, and to suppress shading.

  The driving of the organic EL display device of the present embodiment can be performed by the same method as that of the first embodiment. However, in this embodiment, the reflective electrode 31 and the light extraction electrode 41 are subjected to line sequential scanning in the configuration of FIG. 7, and the reflective electrode 31 and the light extraction electrode 41 are subjected to dot sequential scanning in the configuration of FIG. Since the configuration and operation of the line sequential operation and the dot sequential scanning are well known, the description is omitted here.

  In such an organic EL display device, it is possible to suppress potential unevenness in the reflective electrode 31 and the light extraction electrode 41 which are common electrodes in the display area surface, and to suppress the occurrence of shading. Therefore, display unevenness can be reduced or eliminated.

In the present embodiment, the configuration in which the top emission type stacked organic EL display device is displayed by active matrix driving is shown. However, the same effect can be obtained by the configuration in which the bottom emission type stacked organic EL display device is displayed by active matrix driving. Is obtained.
(Third embodiment)
FIG. 10 is a perspective view showing an example of a pixel arrangement of an organic EL display device which is a third embodiment of the display device according to the present invention. FIG. 11 is a diagram schematically showing a detailed cross-sectional structure in one pixel region. The display region 1 of the organic EL display device shown in FIG. 4 is configured by the pixel array shown in FIG. 10 and the pixels having the cross-sectional structure shown in FIG.

  FIG. 11 is a diagram schematically showing a cross section of an organic EL display device according to the third embodiment of the present invention. In FIG. 11, the organic EL display device according to the present embodiment is a top emission type organic EL display device. In the organic EL display device according to the present embodiment, one component that displays one unit of an image signal includes a first pixel P1 and a second pixel P2. 50 is an insulating substrate, 51 is a reflective electrode, 52 is a first organic light emitting layer, 53a and 53b are first intermediate electrodes, 54 is a second organic light emitting layer, 55a and 55b are second intermediate electrodes, and 56 is a third organic light emitting layer. The light emitting layer, 61 is a light extraction electrode, and 58b and 59a are contact holes. The intermediate electrodes 53a, 53b, 55a, 55b are provided separately for each pixel.

  Each of the first organic light emitting layer 52, the second organic light emitting layer 54, and the third organic light emitting layer 56 has a five-layer structure, and is an electron injection layer / electron transport layer / light emitting layer / hole transport layer / hole injection layer. It consists of

  A reflective electrode 51 is formed in the pixel region on the insulating substrate 50 on which drive TFTs, switch TFTs, and the like are formed as necessary.

  The layout of the reflective electrode 51, the first intermediate electrode 53, the second intermediate electrode 55, and the light extraction electrode 61 will be described with reference to FIGS.

  The reflective electrode 51 is electrically connected by a continuous film connected in the same layer between pixels adjacent in the X-axis direction. The light extraction electrode 61 is patterned in each pixel, and is drawn out of the display area by a wiring 64 extending in the X-axis direction. The wiring 64 can be made of a material having a sufficiently low sheet resistance, and a highly reflective conductive material can also be used. When a highly reflective conductive material is used, it is disposed outside the light emitting pixel region.

  Also in the configuration of this embodiment, since it is not necessary to provide a contact hole for connecting the reflective electrode 51 and the light extraction electrode 61, the aperture ratio is improved, the current density per light emitting area can be kept low, and the lifetime It leads to improvement.

  Further, an electrode material with higher transmittance can be used for the light extraction electrode 61, and the light extraction efficiency can be improved. When sheet resistance is increased by employing an electrode material with high transmittance, potential drop can be prevented by arranging wiring.

  The pattern of the reflective electrode 51 and the pattern of the light extraction electrode 61 are related to the display method of the organic EL display device. For example, in the configuration of FIG. 10, surface sequential driving, line sequential driving, dot sequential driving, and the like can be performed. it can.

  In the above electrode pattern, the reflective electrode 51 is patterned on a line with a pixel width, and further, by setting the electrode film thickness to an appropriate value, the sheet resistance is reduced, and a potential drop is caused between adjacent pixels. It can be made extremely small.

  The reflective electrode 51 and the light extraction electrode 61 are connected to the same power supply 63, but may be connected to a power supply capable of controlling the voltage separately. In the case of being connected to the same power source, the reflective electrode 51 and the light extraction electrode 61 can be connected. The connection location may be inside or outside the display area, and the same voltage is supplied.

  Contact holes 58b and 59a are formed by laser processing, the first intermediate electrode 53a and the second intermediate electrode 55a of the first pixel are connected, and the reflective electrode 51 and the second intermediate electrode 53b of the second pixel are respectively connected. It is connected.

  The reflective electrode 51 having the above-described configuration can reduce the sheet resistance, and the occurrence of a potential drop in the display area plane can be suppressed to a very low level.

  Also in the light extraction electrode 61, the potential drop between adjacent pixels can be extremely reduced by the connection with the wiring layer and the reflection layer 51.

  In the present embodiment, because of the above-described configuration, the reflection electrode 51 and the light extraction electrode 61 that simultaneously perform light emission drive have the same potential in the pixels in the display area plane. In any pixel, the potentials of the reflective electrode and the light extraction electrode are equal in at least two adjacent pixels. Therefore, in the configuration of the present embodiment, it is possible to suppress potential unevenness in the reflective electrode 51 and the light extraction electrode 61 that are common electrodes within the display region surface, and to suppress shading.

The driving of the organic EL display device of the present embodiment can be performed by the same method as that of the first embodiment.
(Fourth embodiment)
FIG. 12 is a perspective view showing an example of a pixel arrangement of an organic EL display device which is a fourth embodiment of the display device according to the present invention.

  In FIG. 12, 71 is a reflective electrode, 73 is a first intermediate electrode, 75 is a second intermediate electrode, and 81 is a light extraction electrode. Reference numerals 84 a and 84 b denote lead wirings connected to the second intermediate electrode 75. The configuration of the present embodiment is different from the configuration of the organic EL display device shown in FIG. 7 in that the driving TFT is not provided on the insulating substrate, but the lead-out wirings 84a and 84b are provided on the insulating substrate to be outside the display area. Driving is performed by the provided driving transistor. That is, in the second embodiment, data writing is performed by the pixel circuit, and light emission is performed in line-sequential or dot-sequential manner, but in this embodiment, scanning signals are sequentially applied to the reflective electrode 71 and the light extraction electrode 81. In addition, passive matrix driving is performed to give data signals to the lead wires 84a and 84b connected to the intermediate electrodes 73 and 75. In the present embodiment, the drive transistor does not have to be configured with a TFT.

  In each of the embodiments described above, the organic EL display device has been described as a representative example of the display device. However, the present invention is not limited to the organic EL display device, and the inorganic EL display device and other stacked display devices. It is also applicable to. Further, although the reflective display device in which the first electrode is the light extraction electrode and the second electrode is the reflection electrode has been described, a display device capable of displaying on both sides can also be configured by using the reflection electrode as the light extraction electrode.

  The present invention can be applied to a display device having two or more light emitting layers. In each embodiment, two layers of intermediate electrodes are formed between three layers of light emitting layers. However, in the case of having two layers of light emitting layers, the intermediate electrode is a single layer.

  In each of the embodiments, a display device having a pixel having three light emitting layers and two intermediate electrodes, one of which is short-circuited with the other electrode, has been described. However, the present invention can also be applied to a display device having pixels in which any of the two layers of intermediate electrodes are driven independently without being short-circuited and all of the three layers of light-emitting layers emit light.

  In each embodiment, two pixels of P1 and P2 are combined to display one image data. However, the present invention is not limited to this, and by using pixels that emit light from all the three light emitting layers, the three primary colors of RGB are emitted to one pixel, and this is used as a display unit for one image data. It can be applied to various display devices.

  Furthermore, in the second to fourth embodiments, the reflective electrode and the light extraction electrode are provided in a line shape. However, the pixel may be arranged in a honeycomb shape or the like. In some cases, the reflection electrode and the light extraction electrode are arranged in a meandering manner. Therefore, in the present invention, the reflective electrode and the light extraction electrode may not be provided in a line shape.

  In the first embodiment, the reflective electrode and the light extraction electrode are formed of a solid electrode, and in the second to fourth embodiments, the reflection electrode and the light extraction electrode are formed in a line shape. One of the electrode and the light extraction electrode may be formed as a solid electrode and the other as a line.

  The present invention is used in EL display devices, particularly organic EL display devices. Specifically, it is used for a display unit of a mobile phone, a flat-screen television, a camera viewfinder, and the like.

1 is a top view showing an example of a pixel arrangement of an organic EL display device as a first embodiment of a display device according to the present invention. It is a schematic sectional drawing which shows 1 pixel of the organic electroluminescence display in 1st Embodiment. It is a perspective view which shows arrangement | positioning of the electrode of the organic electroluminescent display apparatus of 1st Embodiment. 1 is a perspective view of an organic EL display device according to a first embodiment. It is a figure which shows the equivalent circuit of the organic electroluminescent display apparatus in 1st Embodiment. It is a figure which shows an example of the waveform of a power supply in the organic electroluminescent display apparatus in 1st Embodiment. It is the perspective view which showed an example of the pixel arrangement | sequence of the organic electroluminescence display which shows 2nd Embodiment of the display apparatus which concerns on this invention. It is the perspective view which showed an example of the pixel arrangement | sequence of the organic electroluminescence display which shows another structural example in 2nd Embodiment of the display apparatus which concerns on this invention. It is a schematic sectional drawing which shows 1 pixel of the organic electroluminescence display which shows 2nd Embodiment of the display apparatus which concerns on this invention. It is the perspective view which showed an example of the pixel arrangement | sequence of the organic electroluminescence display which shows 3rd Embodiment of the display apparatus which concerns on this invention. It is a schematic sectional drawing which shows 1 pixel of the organic electroluminescence display which shows 3rd Embodiment of the display apparatus which concerns on this invention. It is the perspective view which showed an example of the pixel arrangement | sequence of the organic electroluminescence display which shows 4th Embodiment of the display apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display area 2 Pixel 10 Insulating substrate 11 Light extraction electrode 12 1st organic light emitting layer 13a, 13b 1st intermediate electrode 14 2nd organic light emitting layer 15a, 15b 2nd intermediate electrode 16 3rd organic light emitting layer 17a, 17b Contact hole 21 reflective electrode 22 protective film 23 power source 30 insulating substrate 31 reflective electrode 32 first organic light emitting layer 33a, 33b first intermediate electrode 34 second organic light emitting layer 35a, 35b second intermediate electrode 36 third organic light emitting layer 38b, 39a Contact hole 41 Light extraction electrode 42 Protective film 43 Power supply means 50 Insulating substrate 51 Reflective electrode 52 First organic light emitting layer 53a, 53b First intermediate electrode 54 Second organic light emitting layer 55a, 55b Second intermediate electrode 56 Third organic light emission Layer 58b contact hole 61 light extraction electrode 62 protective film 63 power supply means 101a, 101b TFT for switching
102a, 102b TFT for driving
103a, 103b Capacitor 105 Gate signal line 106a, 106b Source signal line 107 Power supply line P1 First pixel P2 Second pixel

Claims (12)

Two or more light emitting layers are laminated, and each intermediate electrode is disposed between the two or more light emitting layers, and the first electrode is sandwiched between the two or more light emitting layers and the intermediate electrode. In a display device in which a pixel provided with a second electrode is two-dimensionally arranged on a substrate,
The intermediate electrode is provided separately for each pixel,
For the plurality of pixels arranged in at least one direction, the first electrode is connected in the same layer,
The display device, wherein the second electrode is connected in the same layer for at least the pixels arranged in one direction or the other direction.   The display device according to claim 1, wherein the first electrode and the second electrode are electrically connected. The pixel is formed by stacking three light emitting layers,
In two adjacent pixels,
In one pixel, two intermediate electrodes sandwiching the central light emitting layer among the three light emitting layers stacked are electrically connected,
The other pixel is formed by electrically connecting the first electrode or the second electrode and an intermediate electrode facing the first electrode or the second electrode through a light emitting layer. The display device according to claim 1 or 2.   4. The display device according to claim 2, wherein electrical connection between the first electrode and the second electrode is performed outside a display region in which the pixels are arranged. 5.   The display device according to claim 1, wherein the intermediate electrode is made of a light-transmitting conductive material.   6. The display device according to claim 1, wherein the first electrode and the second electrode are connected to the same voltage application unit. The first electrode is a light extraction electrode, and the second electrode is a reflection electrode;
The display device according to claim 1, wherein the light extraction electrode is formed on the substrate side, and the pixel is a bottom emission type pixel that performs light extraction on the substrate side. The first electrode is a light extraction electrode, and the second electrode is a reflection electrode;
7. The top emission type pixel according to claim 1, wherein the reflective electrode is formed on the substrate side, and the pixel is a top emission type pixel that extracts light on the side opposite to the substrate. Display device.   The display device according to claim 1, wherein active matrix driving is performed.   The display device according to claim 1, wherein a driving transistor that independently drives each pixel is connected to the intermediate electrode.   The display device according to claim 1, wherein passive matrix driving is performed.   11. The device according to claim 1, wherein at least one of the first electrode and the second electrode is a common electrode for two-dimensionally arranged pixels. The display device described.