JP2014053236A - Display device, imaging apparatus, light-emitting device, image forming apparatus, method for driving display device, and method for driving light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device which suppresses the damage of an organic compound layer in a pixel and further, suppresses crosstalk.SOLUTION: The display device includes a plurality of organic EL elements 3R, 3G, and 3B. The organic EL elements include a first electrode 11, the organic compound layer, and a second electrode 15. The display device includes a third electrode 20 formed between the first electrodes, in at least a part between the first electrodes 11 of the two adjacent organic EL elements. A part of the organic compound layer is formed across, and in contact with, the first electrode 11 and the third electrode 20 and either one of a voltage having the same polarity as that of a threshold voltage and having an absolute value smaller than the absolute value of the threshold voltage of either of the two adjacent organic EL elements, the same potential as the second electrode 15, and a voltage having a polarity reverse to that of the threshold voltage of the two adjacent organic EL elements is applied to the third electrode 20.

Description

  The present invention relates to a display device, an imaging device, a light emitting device, an image forming apparatus, a display device driving method, and a light emitting device driving method using an organic EL element.

  The organic EL element has a configuration in which an anode, an organic compound layer including at least a light emitting layer, and a cathode are laminated. In addition, a color display device using organic EL elements of three colors, red, green, and blue, has a configuration in which each light emitting layer of red, green, and blue is patterned into a pixel shape of each color, and a light emitting layer that emits white A configuration including red, green, and blue color filters provided in accordance with the pixel shape of each color is used. Part or all of the organic compound layer of the organic EL element used in such a color display device is formed in common for all pixels in order to facilitate the process.

  On the other hand, in recent years, high definition display devices have been studied. High definition reduces the pixel size and reduces the distance between the electrodes of two adjacent pixels. Therefore, current leaks to the pixel adjacent to the pixel that emits light through the organic compound layer formed in common for all the pixels. Then, adjacent pixels emit light and crosstalk occurs.

  In Patent Document 1, in order to suppress this crosstalk, an organic compound layer is formed in common for all pixels, and then a portion formed on the partition provided between the pixels is removed from the organic compound layer. An apparatus manufacturing method is described.

JP 2008-243559 A

  However, in the method of Patent Document 1, since the organic compound layer is patterned after the organic compound layer is formed, the organic compound layer in the pixel may be damaged. In addition, the organic compound layer on the partition wall cannot be completely removed, and crosstalk may not be sufficiently suppressed.

  An object of the present invention is to provide a display device that suppresses damage to an organic compound layer in a pixel and further suppresses crosstalk.

  One aspect of the present invention includes a plurality of organic EL elements, and the organic EL element includes a first electrode, an organic compound layer, and a second electrode, and the first electrode is formed for each organic EL element. The second electrode is a display device formed in common with the plurality of organic EL elements, and is formed between the first electrodes in at least a part between the first electrodes of two adjacent organic EL elements. And at least a part of the organic compound layer is formed across and in contact with the first electrode and the third electrode, and is applied to the third electrode. The potential difference obtained by subtracting the potential applied to the second electrode from the potential is used as the voltage applied to the third electrode, and the second electrode is determined from the potential applied to the first electrode when the organic EL element starts to emit light. The potential difference obtained by subtracting the potential applied to the threshold voltage Then, the third electrode has a voltage having the same polarity as the threshold voltage and a smaller absolute value than the absolute value of any of the two adjacent organic EL elements, or the same potential as the second electrode. Or a voltage having a polarity opposite to the threshold voltage of two adjacent organic EL elements is applied.

  Another aspect of the present invention includes a plurality of organic EL elements, wherein the organic EL element includes a first electrode, an organic compound layer, and a second electrode, and the first electrode is formed for each organic EL element. The second electrode is formed in common with the plurality of organic EL elements, and has a third electrode formed between the first electrodes in at least a part between the first electrodes of the plurality of organic EL elements. And at least a part of the organic compound layer is a method for driving a display device formed across and in contact with the first electrode and the third electrode, and is applied to the third electrode. The potential difference obtained by subtracting the potential applied to the second electrode from the potential is used as the voltage applied to the third electrode, and the second electrode is determined from the potential applied to the first electrode when the organic EL element starts to emit light. The threshold voltage is the potential difference obtained by subtracting the potential applied to A voltage having the same polarity as the threshold voltage and having an absolute value smaller than the absolute value of any of the two adjacent organic EL elements, or the same potential as the second electrode, One of the voltages having a polarity opposite to the threshold voltage of two adjacent organic EL elements is applied.

  Another aspect of the present invention includes a plurality of organic EL elements, wherein the organic EL element includes a first electrode, an organic compound layer, and a second electrode, and the first electrode is formed for each organic EL element. The second electrode is a light emitting device formed in common by the plurality of organic EL elements, and is formed between the first electrodes in at least a part between the first electrodes of two adjacent organic EL elements. And at least a part of the organic compound layer is formed across and in contact with the first electrode and the third electrode, and is applied to the third electrode. The potential difference obtained by subtracting the potential applied to the second electrode from the potential is used as the voltage applied to the third electrode, and the second electrode is determined from the potential applied to the first electrode when the organic EL element starts to emit light. The threshold voltage is the potential difference obtained by subtracting the potential applied to And the third electrode has the same polarity as the threshold voltage and has a smaller absolute value than the absolute value of the threshold voltage of the organic EL element, or the same potential as the second electrode, or the threshold of the organic EL element. Either a voltage having a polarity opposite to that of the voltage is applied.

  Another aspect of the present invention includes a plurality of organic EL elements, wherein the organic EL element includes a first electrode, an organic compound layer, and a second electrode, and the first electrode is formed for each organic EL element. The second electrode is formed in common with the plurality of organic EL elements, and has a third electrode formed between the first electrodes in at least a part between the first electrodes of the plurality of organic EL elements. At least a part of the organic compound layer is a driving method of a light emitting device formed across and in contact with the first electrode and the third electrode, and is applied to the third electrode The potential difference obtained by subtracting the potential applied to the second electrode from the potential is used as the voltage applied to the third electrode, and the second electrode is determined from the potential applied to the first electrode when the organic EL element starts to emit light. The threshold voltage is the potential difference obtained by subtracting the potential applied to And the third electrode has the same polarity as the threshold voltage and has a smaller absolute value than the absolute value of the threshold voltage of the organic EL element, or the same potential as the second electrode, or the threshold of the organic EL element. One of voltages having a polarity opposite to that of the voltage is applied.

  According to the present invention, it is possible to provide a display device in which damage to an organic compound layer in a pixel is suppressed and crosstalk is further suppressed.

FIG. 3 is a schematic diagram illustrating an example of a display device according to the first embodiment. FIG. 2 is a schematic diagram illustrating an example of a peripheral circuit included in the display device according to the first embodiment. Schematic diagram showing pixel circuit and timing chart Equivalent circuit diagram of three adjacent pixels FIG. 3 is a schematic diagram illustrating an example of a pixel layout of the display device according to the first embodiment. FIG. 6 is a schematic diagram illustrating another example of the pixel layout of the display device according to the first embodiment. FIG. 6 is a schematic diagram illustrating another example of the pixel layout of the display device according to the first embodiment. Sectional schematic diagram showing an example of the display device according to the second and third embodiments Cross-sectional schematic diagram illustrating an example of a display device according to Embodiments 4 and 5 Sectional schematic diagram which shows an example of an imaging device provided with the display apparatus which concerns on Embodiment 1 thru | or 5. FIG. 9 is a schematic cross-sectional view illustrating an example of an image forming apparatus including a light emitting device according to Embodiment 6. FIG. 9 is a schematic plan view illustrating an example of a light emitting device according to Embodiment 6. The figure which shows the color reproduction range of a present Example The figure which shows the chromaticity of the green pixel of a present Example

  Hereinafter, the present invention will be described with reference to the drawings by way of embodiments. 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 especially in this specification. The embodiment described below is one embodiment of the invention and is not limited thereto.

(Embodiment 1)
FIG. 1A is a schematic perspective view showing a display device according to the present embodiment. The display device according to the present embodiment includes a plurality of pixels 100 including organic EL elements. The plurality of pixels 100 are arranged in a matrix and form a display area 101. Note that a pixel means a region corresponding to a light emitting region of one light emitting element. In the display device of this embodiment, the light emitting element is an organic EL element, and one color organic EL element is disposed in each pixel 100. Examples of the emission color of the organic EL element include red, green, blue, yellow, cyan, magenta, and white. In the display device of this embodiment, a plurality of pixel units each including a plurality of pixels having different emission colors (for example, a pixel that emits red, a pixel that emits green, and a pixel that emits blue) are arranged. The pixel unit is a minimum unit that enables light emission of a desired color by mixing colors of pixels.

  FIG. 1B is a partial schematic cross-sectional view taken along the line A-A ′ of FIG. The pixel 100 includes a first electrode (anode) 11, a hole transport layer 12, a light emitting layer 13R (13G, 13B), an electron transport layer 14, a second electrode (cathode) 15, It consists of organic EL element 3R (3G, 3B) provided with. The organic EL element 3R is an organic EL element that emits red light, and the red light emitting layer 13R in the element emits light. Similarly, the organic EL elements 3G and 3B are an organic EL element that emits green and an organic EL element that emits blue, respectively, and the green light emitting layer 13G and the blue light emitting layer 13B in the element emit light, respectively. The hole transport layer 12, the light emitting layers 13R, 13G, and 13B and the electron transport layer 14 are collectively referred to as an organic compound layer. The part of the organic compound layer refers to at least one of the hole transport layer 12, the light emitting layers 13R, 13G, and 13B and the electron transport layer 14.

  The first electrode 11 is formed separately from the first electrode 11 of the adjacent pixel, and the hole transport layer 12, the electron transport layer 14, and the second electrode 15 are formed in common for all the pixels. The first electrode 11, the hole transport layer 12, the light emitting layer, the electron transport layer 14, and the second electrode 15 are stacked in this order from the substrate 10 side, but the first electrode 11 and the electron transport layer are stacked from the substrate 10 side. 14, the light emitting layer, the hole transport layer 12, and the second electrode 15 may be laminated in this order. In the latter stacking order, the first electrode 11 is a cathode and the second electrode 15 is an anode.

  The hole transport layer 12 formed in common for all pixels is made of a material having a sheet resistance smaller than that of the light emitting layers 13R, 13G, and 13B in order to lower the driving voltage of the organic EL element. For this reason, when a current is passed through a pixel to be emitted, the current leaks to the adjacent pixel through the hole transport layer 12, and the adjacent pixel also emits light. As a result, crosstalk occurs. In particular, when crosstalk occurs when adjacent pixels emit different colors, the color purity of the pixels is lowered, and the color reproducibility is lowered in the color display device. Further, when the distance between the first electrodes 11 is reduced, the ratio of the resistance between the two adjacent pixels (organic EL elements) in the in-plane direction of the substrate 10 with respect to the resistance of the organic EL element itself is reduced. For this reason, current leakage tends to occur in the in-plane direction of the substrate 10, and crosstalk appears more remarkably.

  Therefore, in the display device of the present invention, in order to suppress crosstalk, as shown in FIG. 1B, a third electrode 20 is formed between the first electrodes 11 of two adjacent organic EL elements. It has the structure which was made. Furthermore, the hole transport layer 12 is formed across and in contact with the first electrode 11 and the third electrode 20. The third electrode 20 has the same polarity as the threshold voltage of two adjacent organic EL elements, and has a smaller absolute value than the absolute value of any of the two adjacent organic EL elements, or Either the same potential as the second electrode 15 or a voltage having a polarity opposite to the threshold voltage of two adjacent organic EL elements is applied.

  With this configuration, a current path of the first electrode 11, the hole transport layer 12, and the third electrode 20 of the pixel desired to emit light is created, and the current path to the adjacent pixel is eliminated or the current path to the adjacent pixel flows. The amount of current can be reduced. For this reason, no light is emitted from the adjacent pixels, and crosstalk is suppressed.

  Here, the voltage in the present invention is a potential difference based on the potential of the second electrode 15 formed in common to the plurality of organic EL elements, more specifically, the potential of the fixed voltage line connected to the second electrode 15. That's it. Further, the voltage applied to the target electrode is a value obtained by subtracting the potential of the second electrode from the potential of the electrode.

  Therefore, depending on whether the second electrode 15 is a cathode or an anode, the voltage applied to the first electrode 11 may be a positive value or a negative value. More specifically, when the second electrode 15 is a cathode, the first electrode 11 is an anode, and the voltage applied to the first electrode 11 is a positive value. On the other hand, when the second electrode 15 is an anode, the first electrode 11 is a cathode, and the voltage applied to the first electrode 11 is a negative value.

  The threshold voltage is a value obtained by subtracting the potential value of the second electrode 15 from the potential value of the first electrode 11 of the organic EL element when the organic EL element starts to emit light. Depending on whether 15 is a cathode or an anode, it may be a positive value or a negative value. More specifically, when the second electrode 15 is a cathode, the voltage applied to the first electrode 11 is a positive value, and the threshold voltage is a positive value. On the other hand, when the second electrode 15 is an anode, the voltage applied to the first electrode 11 is a negative value, and the threshold voltage is a negative value.

  “A voltage having the same polarity as the threshold voltage of two adjacent organic EL elements and having a smaller absolute value than the absolute value of any of the two adjacent organic EL elements is applied to the third electrode 20. "I have" is the following.

First, consider the case where the second electrode 15 is a cathode. In this case, if the threshold voltage of any two adjacent organic EL elements is a positive value, and the smaller absolute value is A, the voltage V ₃ applied to the third electrode 20 is 0 <V ₃ <A value that satisfies A.

On the other hand, consider the case where the second electrode 15 is an anode. In this case, if the threshold voltage of any two adjacent organic EL elements is a negative value, and the smaller absolute value is −B (B> 0), the voltage V applied to the third electrode 20 ₃ is a value satisfying −B <V ₃ <0.

  In addition, “the same potential as that of the second electrode 15 is applied to the third electrode 20” means that the voltage applied to the third electrode 20 is 0V.

  Further, “a voltage having a polarity opposite to the threshold voltage of two adjacent organic EL elements is applied to the third electrode 20” is as follows.

First, consider the case where the second electrode 15 is a cathode. In this case, the threshold voltage of any two adjacent organic EL elements is a positive value, and the voltage V ₃ applied to the third electrode 20 is a value that satisfies V ₃ <0.

On the other hand, consider the case where the second electrode 15 is an anode. In this case, the threshold voltage of any two adjacent organic EL elements has a negative value, and the voltage V ₃ applied to the third electrode 20 is a value that satisfies 0 <V ₃ .

In other words, when the second electrode 15 is the cathode (first electrode 11 is an anode), the voltage V ₃ applied to the third electrode 20, the absolute value of the threshold voltages of the two organic EL elements adjacent Assuming that the smaller value is A, the relationship V ₃ <A is satisfied. That is, a voltage smaller than the threshold voltage of any two adjacent organic EL elements is applied to the third electrode 20. V ₃ may be a positive value or a negative value as long as the relationship V ₃ <A is satisfied.

On the other hand, if the second electrode 15 is an anode (first electrode 11 is the cathode), the voltage V ₃ applied to the third electrode 20 is smaller absolute value among the threshold voltages of the two organic EL elements adjacent When the value of the square and -B, satisfy the relationship of -B _{<V 3.} That is, a voltage higher than the threshold voltage of any two adjacent organic EL elements is applied to the third electrode 20. V ₃ may be a positive value or a negative value as long as the relationship of −B <V ₃ is satisfied.

  Further, any third electrode 20 has the same polarity as the threshold voltages of all the organic EL elements 3R, 3G, and 3B, and has an absolute value that is greater than the absolute value of the threshold voltages of all the organic EL elements 3R, 3G, and 3B. A configuration in which a small voltage is applied may be employed. Alternatively, all the third electrodes 20 may be electrically connected to a common voltage line (not shown). The voltage applied to the third electrode 20 may be a fixed voltage or a variable voltage.

  The third electrode 20 is formed in the same layer as the first electrode 11, and it is desirable to form the third electrode 20 in the same process as the patterning of the first electrode 11. In the present embodiment, the third electrode 20 is disposed at an equal distance from the two adjacent first electrodes 11. However, the arrangement of the third electrode is not limited to this embodiment, and may be arranged, for example, biased toward one first electrode as long as it is between two adjacent first electrodes.

  Each organic EL element is sealed with a sealing film 30 so that external oxygen and moisture do not enter.

  Although the crosstalk generated through the hole transport layer 12 has been described, crosstalk occurs when a part of the organic compound layer is formed in contact with two adjacent first electrodes 11. That is, crosstalk occurs similarly even if a part of the organic compound layer formed in contact with the two adjacent first electrodes 11 is the electron transport layer 14 or the light emitting layer.

  The display device of the present invention may be a bottom emission type display device in which the light of the organic EL element is emitted from the substrate 10 side, or the top emission in which the light of the organic EL element is emitted from the side opposite to the substrate 10. Type display device.

  The present embodiment can also be applied to a monochrome display device. In this configuration, all organic EL elements have the same configuration and display the same color.

  Next, each member will be specifically described.

  As the substrate 10, an insulating substrate such as quartz, glass, or plastic, a metal substrate, a silicon substrate, or the like can be used. Further, the substrate 10 may have a switching element such as a transistor or an MIM element formed on the insulating substrate or the silicon substrate. In that case, the substrate 10 may have a planarization film for planarizing the unevenness of the switching elements.

  The first electrode 11 and the second electrode 15 are made of a transparent oxide conductive layer such as tin oxide, indium oxide, indium tin oxide, indium zinc oxide, Al, Ag, Cr, Ti, Mo, W, Au, Mg, Cs. It is possible to use a single metal such as a metal layer or a metal layer made of an alloy thereof. Furthermore, the 1st electrode 11 and the 2nd electrode 15 may be comprised by the laminated film of a transparent oxide conductive layer and a metal layer, or the laminated film of a some metal layer.

  For the hole transport layer 12, a known material can be suitably used. For example, a triphenyldiamine derivative, an oxodiazole derivative, a polyphylyl derivative, a stilbene derivative, or the like can be used. In addition, oxides such as molybdenum oxide and tungsten oxide, organic substances such as 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), and mixtures thereof can be used. . The hole transport layer 12 includes a single layer or a plurality of layers of an organic compound having a hole injection property and a hole transport property. Further, if necessary, the hole transport layer 12 can also have a function as an electron blocking layer in order to suppress movement of electrons from the light emitting layer to the first electrode 11 side.

  There is no restriction | limiting in particular as a light emitting layer, It is possible to apply a well-known material. The light emitting layer may be composed of only a light emitting material, or may be a mixed layer of a light emitting dopant material and a host material. The light emitting layer may contain an assist dopant material in addition to the light emitting dopant material and the host material. In the present invention, the host material means a material having the highest weight concentration among the components in the light emitting layer. Further, the light emitting material and the light emitting dopant material may be either a fluorescent material or a phosphorescent material.

  A known material can be suitably used for the electron transport layer 14, and examples thereof include an aluminum quinolinol derivative, an oxadiazole derivative, a triazole derivative, a phenylquinoxaline derivative, a silole derivative, and a phenanthroline derivative. In addition, alkali metals, alkaline earth metals, rare earth metals, and compounds thereof can be used. Moreover, the mixture of the illustrated material can also be used suitably. It consists of a single layer or a plurality of layers of an organic compound having electron injection properties and electron transport properties. The electron transport layer 14 can also have a function as a hole blocking layer.

  Moreover, the hole transport layer 12 and the electron transport layer 14 can also have a function as an exciton blocking layer for suppressing diffusion of excitons generated in the light emitting layer. Note that the hole transport layer 12 and the electron transport layer 14 are not essential, and may be omitted depending on the configuration of the organic EL element.

  The sealing film 30 has a function of preventing oxygen and moisture from entering the organic EL element, and an inorganic material such as silicon nitride, silicon oxide, or alumina oxide can be used. Moreover, the sealing film 30 may be comprised by the laminated film which consists of two or more layers of inorganic materials, and may be comprised by the laminated film of the inorganic material and the resin material.

  Any structure may be used as long as the organic EL element is sealed, and a sealing cap may be used instead of the sealing film 30. As the sealing cap, a cap-shaped member such as glass or plastic can be used. In addition, the sealing cap may be configured by a plate-like member such as a glass plate and a sealant disposed around the display region 101 in order to bond the member and the substrate 10. The space between the sealing cap and the second electrode 15 of the organic EL element may be filled with a gas such as nitrogen or argon, or may be filled with a resin material such as acrylic resin. A desiccant may be disposed in the space.

(Driving method of display device)
A driving method of the display device of the present invention will be described with reference to FIG. FIG. 2 is a schematic diagram showing the display area 101 of the display device, each wiring, and peripheral circuits.

  The display device includes a data line driving circuit 102, a scanning line driving circuit 103, and a power supply line driving circuit 104 in addition to a display region 101 configured by two-dimensionally arranging pixels 100 in m rows × n columns. ing. A data line is inputted to the data line driving circuit 102 from a display panel controller (not shown), and a data line having n data voltages as gradation display data corresponding to the video signal from each output terminal of the data line driving circuit 102 105 is output. A control signal is input to the scan line driver circuit 103 from a display panel controller (not shown), and control voltages for controlling the operation of the pixels 100 are output from the output terminals of the scan line driver circuit 103 to the m scan lines 106. The Further, the power supply line driving circuit 104 applies a voltage to the power supply line 107 arranged in parallel with each scanning line 106.

  FIG. 3A shows the pixel circuit 200 in the i-th row and the k-th column. The pixel circuit 200 includes an n-type selection transistor 201, a p-type drive transistor 202, and a storage capacitor 203 that stores a data voltage. The gate electrode of the selection transistor 201 is connected to the scanning line 106 (i), one of the source electrode and the drain electrode is connected to the data line 105 (k), and the other is connected to the gate electrode of the driving transistor 202. The source electrode of the driving transistor 202 is connected to the power supply line 107, and the drain electrode is connected to the organic EL element 3. The storage capacitor 203 has one terminal connected to the gate electrode of the driving transistor 202 and the other connected to the power supply line 107. Note that one end of the organic EL element 3 is connected to the drive transistor 202, while the other end is connected to the fixed voltage line 108. The scanning line 106 (i) represents the i-th scanning line 106, and the data line 105 (k) represents the k-th data line 105.

  FIG. 3B is a timing chart showing a driving method of the pixel circuit 200 of FIG. 3A and a driving method of the pixel circuit in the i−1 and i + 1 rows, and an example of line sequential driving. Show. In the writing period A of the i-th pixel, the control voltage P (i) applied to the i-th scanning line 106 (i) is High level. For this reason, the selection transistor 201 is turned on, the data voltage V (i) is applied to the pixel circuit 200 from the data line 105 (k), and the charge corresponding to the data voltage V (i) is held in the storage capacitor 203. Is done. After that, the control voltage P (i) becomes a low level, and the selection transistor 201 is turned off. In the light emission period B, a current corresponding to the data voltage V (i) written in the storage capacitor 203 in the writing period A flows from the power supply line 107 to the organic EL element through the driving transistor 202. Then, the organic EL element 3 emits light with a luminance corresponding to the amount of current. A total of the writing period A and the light emission period B is one frame. When the light emission period B ends, a writing period A ″ for the next frame starts. Strictly speaking, not only the light emission period B but also the pixel circuit 200 in FIG. Yes.

  The driving method of the pixel circuits in the (i−1) th row and the (i + 1) th row is the same, but in the writing period in the (i−1) th row, the control voltage P (i−1) is high in FIG. This is the period when the level is set. Then, it ends before the writing period A of the i-th row starts and overlaps the light-emitting period B 'of the previous frame of the i-th row. The writing period for the (i + 1) th row is a period in which the control voltage P (i + 1) is at a high level, which starts after the end of the writing period A for the ith row and overlaps the light emission period B of the current frame for the ith row. . In this way, the data voltage is written to each pixel in the order of the (i-1) th row, the ith row, and the (i + 1) th row, and the i-1th row, the ith row, and the i + 1th row are according to the data voltage. In order, the organic EL element emits light.

  FIG. 4 shows an equivalent circuit of the pixel circuit and the organic EL element corresponding to FIG. The configuration of the pixel circuit is the same as that of FIG. 3A, but the third electrode 20 is disposed between the pixel circuits, and the third electrode 20 and the first electrode 11 side of the organic EL element are electrically connected via a resistor 300. It is an equivalent circuit connected to. Here, the resistor 300 is a part of the organic compound layer (hole transport layer 12) formed in common contact with the two first electrodes 11 of two adjacent organic EL elements in the in-plane direction of the substrate 10. It represents resistance.

  In the present invention, the leakage current flows through the third electrode 20 by providing the third electrode 20 and controlling the voltage applied to the third electrode 20. Therefore, for example, when the organic EL element 3G emits light, the organic EL elements 3R and 3B do not emit light. Moreover, it is preferable that a voltage smaller than the threshold voltage of any two adjacent organic EL elements is applied to the third electrode 20 while the display device is driven.

(Layout)
FIG. 5 is a schematic plan view of a part of the display device shown in FIG. For ease of viewing, elements other than the third electrode 20 and each pixel, the organic compound layer, the first electrode 11, the second electrode 15, and the like are omitted.

  The third electrode 20 is provided between the red pixel 100R and the green pixel 100G, the green pixel 100G and the blue pixel 100B, and the blue pixel 100B and the red pixel 100R. That is, it is disposed between the first electrodes 11 of two adjacent organic EL elements that emit different colors, and is not disposed between the first electrodes 11 of two adjacent organic EL elements that emit the same color. . The third electrode 20 may have an island shape, but is preferably connected to each other and formed in a stripe shape. Note that the size of each pixel may be the same or different from the viewpoint of the lifetime.

  Further, the pixel layout is not limited to FIG. 5, and a third electrode 20 is also formed between the first electrodes 11 of two adjacent organic EL elements emitting the same color as shown in FIG. 6A. May be. In this case, it is desirable that the third electrodes 20 are not in an island shape but are connected to each other and formed in a lattice shape.

  The present invention can also be applied to a case where a green pixel is composed of two pixels 100Ga and 100Gb as shown in FIG. 6B. Also in this case, it is desirable that the third electrode 20 be formed in a lattice shape. 6B, the green pixel 100Ga may be a green pixel 100G and the green pixel 100Gb may be a white pixel. Other color combinations are possible.

  The present invention can be applied even in a delta arrangement as shown in FIG. Further, as shown in FIG. 7B, the present invention can be applied even in a configuration in which the area of the blue pixel 100B is larger than that of other pixels in the delta arrangement. This configuration is preferable because the lifetime of the blue pixel 100B can be extended.

(Embodiment 2)
FIG. 8A shows a schematic cross-sectional view of the display device of this embodiment. In the first embodiment, the light emitting layer is formed for each color. However, in the present embodiment, the light emitting layer 13 is formed in common with organic EL elements that emit red, green, and blue, and emits white. In the present embodiment, for color display, red, green, and blue color filters 40R, 40G, and 40B are formed on the sealing film 30 corresponding to each pixel. The rest is the same as in the first embodiment. In this embodiment, all the organic compound layers are formed in common for all pixels.

  The light emitting layer 13 may be a single layer or a structure in which two or more light emitting layers emitting different colors are stacked. When the light emitting layer 13 is a single layer, examples include a layer made of red, green, and blue light emitting dopant materials and a host material, and a layer made of cyan and yellow light emitting dopant materials and a host material. In a configuration in which two or more light emitting layers are laminated, a configuration in which a first light emitting layer emitting red, a second light emitting layer emitting green, and a third light emitting layer emitting blue are laminated, or red and green light emitting dopants. Examples include a configuration in which a first light emitting layer containing a material and a second light emitting layer emitting blue light are stacked. Note that in a configuration in which two or more light emitting layers are stacked, the light emitting layers do not need to be in contact with each other, and a layer that does not emit light may be provided between the two light emitting layers.

  Known materials can be used for the color filters 40R, 40G, and 40B. Further, as shown in FIG. 8A, the color filters 40R, 40G, and 40B may be formed by patterning on the sealing film 30, or the color filters 40R, 40G, and 40B are formed on a substrate (not shown). Then, they may be laminated on the sealing film 30.

  A black matrix may be formed between the color filters patterned for each pixel.

(Embodiment 3)
FIG. 8B is a schematic cross-sectional view of the display device of this embodiment. In the second embodiment, the light emitting layer 13 is a light emitting layer that emits white. However, the present embodiment is different in that it is a light emitting layer that emits blue. In the present embodiment, for color display, on the sealing film 30, a color conversion layer 50 </ b> R that converts blue to red corresponding to the red and green pixels, and a color that converts blue to green. A conversion layer 50G is formed. The rest is the same as in the second embodiment.

  Known materials can be used for the color conversion layers 50R and 50G. The color conversion layers 50R and 50G may be formed by patterning on the sealing film 30, or the color conversion layers 50R and 50G may be formed on a substrate (not shown) and bonded to the sealing film 30. Good.

(Embodiment 4)
FIG. 9A shows a schematic cross-sectional view of the display device of the present embodiment. The present embodiment is different from the first embodiment in that the end portion of the first electrode 11 is covered with the insulating layer 61 so that the first electrode 11 and the second electrode 15 are not short-circuited. That is, in this embodiment, the insulating layer 61 is disposed between the first electrode 11 and the third electrode 20. The rest is the same as in the first embodiment.

  For the insulating layer 61, a resin material such as polyimide resin or acrylic resin, or an inorganic material such as silicon oxide or silicon nitride can be used. Moreover, the structure which laminated | stacked the resin material and the inorganic material may be sufficient.

  This embodiment can be combined with the second and third embodiments.

(Embodiment 5)
FIG. 9B is a schematic cross-sectional view of the display device of the present embodiment. In the present embodiment, the end portion of the first electrode 11 is covered with the insulating layer 62 so that the first electrode 11 and the second electrode 15 are not short-circuited, and the third electrode 20 is disposed on the insulating layer 62. It is a configuration. The rest is the same as in the first embodiment.

  For the insulating layer 62, a resin material such as polyimide resin or acrylic resin, or an inorganic material such as silicon oxide or silicon nitride can be used. Moreover, the structure which laminated | stacked the resin material and the inorganic material may be sufficient.

  This embodiment can be combined with the second and third embodiments.

  The display device described above is used in a display unit of a television receiver or a personal computer. In addition, it may be used for a display unit or an electronic viewfinder of an imaging apparatus such as a digital camera or a digital video camera.

  As shown in FIG. 10, the imaging device includes an imaging element 93 such as a low-pass filter 91, an infrared cut filter 92, and a CMOS sensor in a housing 90. The display device 94 described in the first to fifth embodiments is arranged in the housing 90 of the imaging device, and can display an image captured by the imaging device 93 and imaged by the image processing circuit. In FIG. 10, the imaging apparatus includes a lens 95 outside the housing 90, and the lens 95 and the housing 90 can be attached and detached. However, the display device of this embodiment can also be applied to an imaging device in which the housing 90 and the lens are provided integrally.

  In addition, the display device of the present embodiment may be used for a display unit of a mobile phone, a display unit of a portable game machine, and the like, and further, a display unit of a portable music player, a display of a personal digital assistant (PDA) May be used for a display part of a car navigation system.

(Embodiment 6)
The present embodiment relates to a light emitting device. In particular, the light emitting device of this embodiment can be used as an exposure light source of an image forming apparatus as shown in FIG. The image forming apparatus includes a light emitting device, a photoconductor on which a latent image is formed by the light emitting device, and a charging unit that charges the photoconductor.

  The light emitting device of this embodiment has a plurality of light emitting regions 400 each including an organic EL element. In FIG. 12A, the plurality of light emitting regions 400 are arranged in a staggered pattern, and in FIG. 12B, the plurality of light emitting regions 400 are arranged in one row. Examples of the emission color of the organic EL element include red, green, blue, yellow, cyan, magenta, white, and the like, and the configuration of the organic EL element may be appropriately adopted according to the photosensitive characteristics of the photoreceptor.

  FIG. 12C is a partial schematic cross-sectional view taken along the line B-B ′ of FIG. The light emitting region 400 includes a first electrode (anode) 11, a hole transport layer 12, a light emitting layer 13, an electron transport layer 14, and a second electrode (cathode) 15 on the substrate 10. It consists of element 3. The hole transport layer 12, the light emitting layer 13, and the electron transport layer 14 are collectively referred to as an organic compound layer. The part of the organic compound layer refers to at least one of the hole transport layer 12, the light emitting layer 13, and the electron transport layer 14.

  The first electrode 11 is formed separately from the first electrode 11 of the adjacent pixel, and the hole transport layer 12, the electron transport layer 14, and the second electrode 15 are formed in common for all the pixels. Each organic EL element is sealed with a sealing film 30 so that external oxygen and moisture do not enter.

  In the light emitting device used in the image forming apparatus as in this embodiment, crosstalk due to leakage current becomes a problem as in the display device. When crosstalk occurs, image blurring on the photosensitive member of the image forming apparatus occurs, and a predetermined image cannot be output.

  On the other hand, in the light emitting device of the present embodiment, as in the first embodiment, as shown in FIG. 12C, the third electrode 20 is provided between the first electrodes 11 of two adjacent organic EL elements. It has a formed configuration. Furthermore, the hole transport layer 12 is formed across and in contact with the first electrode 11 and the third electrode 20. The third electrode 20 has the same polarity as the threshold voltage of the organic EL element and has a smaller absolute value than the absolute value of any of the two adjacent organic EL elements, or the second electrode 15. Or a voltage having a polarity opposite to the threshold voltage of the organic EL element is applied. Note that all the organic EL elements of the present embodiment emit the same color and have the same configuration.

  Next, an image forming apparatus including the light emitting device of this embodiment as an exposure light source will be described. The image forming apparatus of FIG. 11 includes a color mode in which four color toners of yellow (Y), magenta (M), cyan (C), and black (K) are superimposed to form a color image, and black (K). A monochrome mode in which a monochrome image is formed using only toner can be selectively executed. FIG. 11 is a cross-sectional view of the main part in the sub-scanning direction. In the image forming apparatus, when code data Dc is input from an external device such as a personal computer to a print controller (not shown), the code data Dc is converted into image data (dot data) Di. The image data Di is input to exposure units 70Y, 70M, 70C, and 70K built in the image forming apparatus. The exposure units 70Y, 70M, 70C, and 70K are controlled based on the image data Di.

  The exposure unit 70Y includes the light emitting device of the present embodiment and a lens that collects the light emitted from the light emitting device and irradiates the surface of the photosensitive drum 85Y with the exposure light. Further, the exposure unit 70Y may have a light absorbing member so that light is not irradiated to other than a predetermined position on the surface of the photosensitive drum 85Y.

  In addition to the exposure units 70Y, 70M, 70C, and 70K, a print controller, a transfer belt 81, a paper feed unit 82, a fixing roller 83, and a pressure roller 84 are disposed in the housing 80 of the image forming apparatus. Further, photosensitive drums 85Y, 85M, 85C, 85K, charging rollers 86Y, 86M, 86C, 86K, developing devices 87Y, 87M, 87C, 87K, and transfer rollers 88Y, 88M, 88C, 88K are arranged in the housing 80. ing. The paper feed unit 82 is configured to be detachable.

  The image forming operation is as follows. In the following, a case where a yellow (Y) image is latent is described. However, a sheet is conveyed by the transfer belt 81, and magenta (M), cyan (C), and black (K) images are yellow ( The image is sequentially formed in the same manner as the image formation of Y).

  First, based on a signal from the print controller, the photosensitive drum 85Y, which is an electrostatic latent image carrier, is rotated clockwise by a motor (not shown). With this rotation, each photosensitive surface of the photosensitive drum 85Y rotates with respect to each exposure light. Below the photosensitive drum 85Y, a charging roller 86Y for charging the surface of the photosensitive drum 85Y with a desired pattern is provided in contact with the surface. The exposure unit 70Y irradiates exposure light onto the surface of the photosensitive drum 85Y that is uniformly charged by the charging roller 86Y.

  The exposure light emitted from the exposure unit 70Y is adjusted in irradiation position, irradiation timing, irradiation time, irradiation intensity, and the like based on the image data Di, and an electrostatic latent image is formed on the surface of the photosensitive drum 85Y by the exposure light. . The electrostatic latent image is developed as a toner image by a developing unit 87Y disposed so as to be in contact with the photosensitive drum 85Y downstream of the exposure light irradiation position in the rotation direction of the photosensitive drum 85Y.

  The toner image developed by the developing unit 87Y is transferred onto a sheet as a transfer material by a transfer roller 88Y disposed below the photosensitive drum 85Y so as to face the photosensitive drum 85Y. The paper is stored in a paper cassette in the paper supply unit 82, but paper can be fed even by a manual feeder. A paper feed roller is disposed at the end of the paper cassette, and feeds the paper in the paper cassette into the transport path.

  The sheet having the toner image transferred thereon as described above is conveyed to the fixing device by the transfer belt 81. The fixing device includes a fixing roller 83 having a fixing heater (not shown) therein and a pressure roller 84 disposed so as to be in pressure contact with the fixing roller 83, and the conveyed paper is fixed to the fixing roller. The toner image on the sheet is fixed by heating while pressing with the pressure roller 83 and the pressure roller 84.

  A display device having the configuration shown in FIG. 1 was produced. This example corresponds to the second embodiment.

  First, a pixel circuit (not shown) was formed on a silicon substrate, and an interlayer insulating film made of silicon oxide was formed thereon, so that a substrate 10 shown in FIG. A Ti film having a thickness of 50 nm was formed on the substrate 10 by sputtering. Subsequently, the Ti film was patterned for each pixel to form the first electrode (anode) 11. The pixel layout is shown in FIG.

  On the 1st electrode 11, the following organic compound layers were formed into a film in common with all the pixels by the vacuum evaporation method. First, the hole transport layer 12 was formed. The hole transport layer 12 includes a first hole transport layer, a second hole transport layer, and an electron block layer. The first hole transport layer was formed by doping 0.5% by weight of NDP9 (manufactured by NOVALED) into the host material shown in the following compound 1 and forming a film at 15 nm. On the 1st positive hole transport layer, the 2nd positive hole transport layer was formed into a film with the material of the compound 1 at 10 nm. On the second hole transport layer, an electron blocking layer was formed to a thickness of 10 nm from the material shown in Compound 2.

  Next, as the light emitting layer 13 that emits white light, 2 wt% of the light emitting dopant material shown in Compound 4 and 0.2 wt% of TRR-D125 (manufactured by Toray Industries, Inc.) Doped and formed to a thickness of 10 nm. Further, the host material represented by Compound 3 was doped with 1 wt% of the light-emitting dopant material represented by Compound 5 to form 10 nm.

A first electron transport layer and a second electron transport layer were formed as the electron transport layer 14 on the light emitting layer 13. In the first electron transport layer, the following compound 6 was formed at 10 nm. In addition, the second electron transporting layer was formed to have a thickness of 10 nm by co-evaporating the host material shown in Compound 6 and Cs ₂ CO ₃ so that the cesium concentration in the layer was 8.3 wt%.

  On top of that, indium zinc oxide was deposited at 500 nm as the second electrode 15.

  A silicon nitride sealing film 30 was formed on the second electrode 15 at a thickness of 4 μm. Further, color filters 40R, 40G, and 40B in which pigments are dispersed in a negative acrylic photosensitive material are formed thereon by patterning for each pixel. The thickness of each color filter was 2 μm.

  The display device manufactured as described above was driven to display a predetermined image. The pixel circuit of each pixel of this display device is as shown in FIG.

  When the organic EL element emits light, a predetermined voltage of 2.6 V or more which is a threshold voltage is applied to the first electrode 11 according to the luminance, and a current flows through the organic EL element via the driving transistor 202. On the other hand, when the organic EL element did not emit light, current supply to the pixel circuit 200 was cut off.

  The second electrode 15 is common to all pixels, and 0 V was always applied while the display device was driven.

  The third electrode 20 is connected to the second electrode 15 outside the display region, and 0 V, that is, a voltage smaller than the threshold voltage is always applied.

  FIG. 13 shows the color reproducibility of the display device when a voltage smaller than the threshold voltage is applied to the third electrode 20 as described above. FIG. 13 was created as follows.

  First, of the red, green, and blue pixels, only the green pixel was caused to emit light with a desired luminance, and the chromaticity was measured when the other two colors were not emitted. The chromaticity was measured at a predetermined luminance from low luminance to high luminance. The result is shown in FIG. Next, the chromaticity was measured in the same manner for red and blue pixels. From the chromaticity data for each color and a plurality of luminances, the ratio to the NTSC color coordinate system was calculated as 100%, and FIG. 12 was created.

  Further, the same color reproducibility as described above is calculated in a configuration in which the third electrode 20 is not provided, and a plotted result is shown in FIG. 13 for comparison.

  From FIG. 13, it can be seen that the color reproducibility is suppressed at any luminance when the third electrode 20 is provided and a voltage smaller than the threshold voltage is applied, compared to the case where the third electrode 20 is not provided. I understand. Further, when the third electrode 20 is provided and a voltage smaller than the threshold voltage is applied, the color reproducibility is kept substantially constant at any luminance. These are considered to be a result of suppressing crosstalk generated between pixels.

3R, 3G, 3B Organic EL element 11 First electrode 15 Second electrode 20 Third electrode

Claims (18)

A plurality of organic EL elements, wherein the organic EL element includes a first electrode, an organic compound layer, and a second electrode; the first electrode is formed for each organic EL element; A display device formed in common with the organic EL element,
A third electrode formed between the first electrodes in at least a part between the first electrodes of two adjacent organic EL elements;
At least a part of the organic compound layer is formed across and in contact with the first electrode and the third electrode,
A potential difference obtained by subtracting a potential applied to the second electrode from a potential applied to the third electrode is defined as a voltage applied to the third electrode.
When the threshold voltage is a potential difference obtained by subtracting the potential applied to the second electrode from the potential applied to the first electrode when the organic EL element starts to emit light,
The third electrode has the same polarity as the threshold voltage and has a smaller absolute value than the absolute value of any of the two adjacent organic EL elements, or the same potential as or adjacent to the second electrode. Either of the threshold voltages of the two organic EL elements that match and a voltage having a reverse polarity is applied.   The display device according to claim 1, wherein the same potential is applied to the third electrode and the second electrode.   The display device according to claim 1, wherein the third electrode and the second electrode are electrically connected.   A voltage having the same polarity as the threshold voltages of all the plurality of organic EL elements and having a smaller absolute value than the absolute value of the threshold voltages of all the organic EL elements 3R, 3G, 3B is applied to the third electrode. The display device according to claim 1, wherein: The plurality of organic EL elements include a plurality of organic EL elements that emit light of different colors,
The organic compound layer includes a light emitting layer that emits white light and is commonly formed in the plurality of organic EL elements,
The display device according to claim 1, wherein each of the plurality of organic EL elements includes a color filter. The plurality of organic EL elements include a plurality of organic EL elements that emit light of different colors,
5. The display device according to claim 1, wherein each of the organic EL elements that emit light of different colors has a light emitting layer that emits light of different colors. 6. The plurality of organic EL elements include a plurality of organic EL elements that emit light of different colors,
The organic compound layer includes a light emitting layer that emits blue light and is formed in common to the plurality of organic EL elements, and the plurality of organic EL elements include a color conversion layer. The display device according to any one of the above.   The first electrode and the third electrode are formed in the same layer, and an insulating layer is disposed between the first electrode and the third electrode. Item 1. A display device according to item 1.   The insulating layer is disposed between the first electrodes of the adjacent organic EL elements, and the third electrode is formed on the insulating layer. The display device described in 1. The plurality of organic EL elements include a plurality of organic EL elements that emit light of different colors,
The third electrode is disposed between the first electrodes of two adjacent organic EL elements that emit light of different colors, and between the first electrodes of two adjacent organic EL elements that emit light of the same color. The display device according to claim 1, wherein the display device is not disposed on the display device.   The display device according to claim 1, wherein the third electrode is arranged in a stripe shape.   The display device according to claim 1, wherein the third electrodes are arranged in a grid pattern. An image sensor, and a display device that displays an image captured by the image sensor,
An image pickup apparatus, wherein the display apparatus is the display apparatus according to any one of claims 1 to 12. A plurality of organic EL elements, wherein the organic EL element includes a first electrode, an organic compound layer, and a second electrode; the first electrode is formed for each organic EL element; A light-emitting device formed in common with the organic EL element,
A third electrode formed between the first electrodes in at least a part between the first electrodes of two adjacent organic EL elements;
At least a part of the organic compound layer is formed across and in contact with the first electrode and the third electrode,
A potential difference obtained by subtracting a potential applied to the second electrode from a potential applied to the third electrode is defined as a voltage applied to the third electrode.
When the threshold voltage is a potential difference obtained by subtracting the potential applied to the second electrode from the potential applied to the first electrode when the organic EL element starts to emit light,
The third electrode has the same polarity as the threshold voltage and a smaller absolute value than the absolute value of the threshold voltage of the organic EL element, or the same potential as the second electrode, or the threshold voltage of the organic EL element. One of the voltages of reverse polarity is applied, The light-emitting device characterized by the above-mentioned.   An image forming apparatus comprising: the light emitting device according to claim 14; a photoconductor on which a latent image is formed by the light emitting device; and a charging unit that charges the photoconductor. A plurality of organic EL elements, wherein the organic EL element includes a first electrode, an organic compound layer, and a second electrode; the first electrode is formed for each organic EL element; A third electrode formed between the first electrodes in at least a portion between the first electrodes of the plurality of organic EL elements, and at least part of the organic compound layer. A part of the method is a driving method of a display device formed across and in contact with the first electrode and the third electrode,
A potential difference obtained by subtracting a potential applied to the second electrode from a potential applied to the third electrode is defined as a voltage applied to the third electrode.
When the threshold voltage is a potential difference obtained by subtracting the potential applied to the second electrode from the potential applied to the first electrode when the organic EL element starts to emit light,
A voltage having the same polarity as the threshold voltage and having an absolute value smaller than the absolute value of any of the two adjacent organic EL elements, or the same potential as or adjacent to the second electrode. One of the threshold voltages of two organic EL elements and the voltage of reverse polarity are applied, The drive method of the display apparatus characterized by the above-mentioned.   The display device driving method according to claim 16, wherein the third electrode and the second electrode are applied with the same potential to the third electrode. A plurality of organic EL elements, wherein the organic EL element includes a first electrode, an organic compound layer, and a second electrode; the first electrode is formed for each organic EL element; A third electrode formed between the first electrodes in at least a portion between the first electrodes of the plurality of organic EL elements, and at least part of the organic compound layer. A part of the driving method of the light-emitting device formed across and in contact with the first electrode and the third electrode,
A potential difference obtained by subtracting a potential applied to the second electrode from a potential applied to the third electrode is defined as a voltage applied to the third electrode.
When the threshold voltage is a potential difference obtained by subtracting the potential applied to the second electrode from the potential applied to the first electrode when the organic EL element starts to emit light,
The third electrode has the same polarity as the threshold voltage and a smaller absolute value than the absolute value of the threshold voltage of the organic EL element, or the same potential as the second electrode, or the threshold voltage of the organic EL element. A driving method of a light emitting device, characterized in that any one of reverse polarity voltages is applied.