JP2009071019A - Display unit, and electronic apparatus equipped with the display unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To materialize a display unit capable of displaying a high-definition pattern, which can steadily form a bank and can form displayed elements while injected functional liquids are correctly applied to a pixel region without being intermingled. <P>SOLUTION: To lengthen a creepage path of a bank between adjoining picture elements, the height of the bank is made higher by the amount of BH. In addition, the bank is formed in an extendable manner so that the height of a pixel region from a substrate 10 may become higher by RH1 at every other picture element, and that the heights of the pixel regions from the substrate 10 may be mutually different between the adjacent pixel regions. Accordingly, the G functional liquid and the R functional liquid will never be intermingled. Further, since the height of a bank where a bank width is narrow is controlled to be low, the bank can be steadily formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a display device and an electronic apparatus including the display device, and in particular, a pixel region partitioned in a matrix by banks is provided on a substrate, and a display element including a predetermined functional layer is provided in the pixel region. The present invention relates to a display device to be formed.

  Conventionally, when a functional liquid is applied to a predetermined region formed on a substrate by using an ink jet method to form a functional layer having a predetermined pattern, due to process accuracy such as coating, It is known that a problem of mixing different functional liquids occurs. In particular, when a high-definition functional layer having a short distance along the substrate surface between regions to which the functional liquid is applied is formed, such a problem is likely to occur.

  Thus, many techniques have been disclosed in which banks that partition the respective regions are usually provided between the regions where the functional layers are formed, and the functional liquid is prevented from being mixed by the banks (for example, see Patent Document 1). .

JP 2000-353594 A

  By the way, in the normal ink jet method, when functional liquid droplets are ejected from nozzles and functional liquid is applied to a predetermined region formed by a bank on a substrate, nozzle position accuracy, shape error, or difference in ejection conditions For example, the landing positions of the ejected droplets may vary in the direction along the substrate surface.

  For this reason, in order to ensure that even if such variations occur, the ejected liquid droplets of the functional liquid do not flow over the bank and flow into the adjacent area and stay within the predetermined area, the bank width Needs to be set to be equal to or larger than the width in consideration of variations in the landing positions of the droplets. Therefore, the bank width cannot be narrower than the width considering the variation in landing position in the direction along the substrate surface, and as a result, there arises a problem that a high-definition pattern cannot be formed. become.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  [Application Example 1] A display device in which pixel regions partitioned in a matrix by banks are provided on a substrate, and a display element including a predetermined functional layer is formed in the pixel region, At least one is a functional layer formed by application of a functional liquid, and at least in the pixel region of either the partitioned row or the partitioned column, the display element formed in the adjacent pixel region The surfaces facing the substrate have different heights from the substrate.

  When the density of the pixels is increased, the banks that partition the pixel region are narrowed, so that the plane (creeping) distance between display elements formed in the pixel region is shortened. Therefore, according to this configuration, it is possible to increase the creeping distance of the banks existing between the display elements by making the heights of the adjacent display elements different from the substrate. As a result, it is possible to suppress the creepage distance of the bank from being shortened even if the planar distance between the display elements is shortened, so that the functional liquid applied to the pixel region for forming the display element is applied to adjacent pixels. Mixing between areas can be suppressed.

  Application Example 2 In the display device, on the creeping surface of the bank located between the adjacent pixel regions, there is a region around the pixel region where the display element having a higher height from the substrate is formed. The functional liquid applied to the pixel region is subjected to a liquid repellent treatment, and the height from the substrate is around the pixel region where the display element having a lower height from the substrate is formed. A lyophilic treatment is performed on the functional liquid applied to a pixel region where the display element having a higher height is formed.

  The functional liquid applied to the pixel area where the display element is formed at a position where the height from the substrate is high on the bank surface located between adjacent pixel areas is applied to the pixel area where the lower display element is formed by gravity. Easy to flow. Therefore, by making the periphery of the pixel region where the higher display element is formed liquid repellent, the functional liquid is less likely to flow to the pixel region where the lower display element is formed. Further, even if it flows, the bank surface around the pixel area where the lower display element is formed is made lyophilic so as not to flow to the pixel area where the lower display element is formed. By doing so, the applied functional liquid can be kept on the creeping surface of the bank. As a result, it is possible to prevent the functional liquid applied to the pixel region where the higher display element is formed from being mixed with the functional liquid applied to the pixel region where the lower display element is formed.

  Application Example 3 In the display device, the creeping shape of the bank increases as the opening area of the pixel region in which the display element having a lower height from the substrate is formed approaches the substrate. It includes a reverse taper shape.

  A pixel region in which the functional liquid applied to the pixel region where the display element whose height is higher from the substrate surface is formed on the bank surface located between adjacent pixel regions is formed by the gravity. Easy to flow. Therefore, a reverse taper portion is formed along the bank surface that partitions the pixel region in which the lower display element is formed. In this way, the functional liquid that has spilled from the pixel area where the higher display element is formed is retained in the reverse tapered portion so that it does not enter the pixel area where the lower display element is formed. it can. As a result, it is possible to prevent the functional liquid applied to the pixel region where the higher display element is formed from being mixed with the functional liquid applied to the pixel region where the lower display element is formed.

  Application Example 4 In the display device, the pixel region in which the display element having a higher height from the substrate is formed is in contact with a surface of the display element facing the substrate. The bank is extended.

  According to this configuration, since the pixel region in which the higher display element is formed can be formed simultaneously with the formation of the bank, the pixel region for forming display elements having different heights can be easily formed. It becomes possible. In addition, since the pixel region in which the higher display element is formed is formed of a bank material, the generation of a region with a narrow bank width can be suppressed for the banks that partition the pixel region in a matrix. As a result, the bank can be easily formed.

  Application Example 5 In the display device, the functional layer formed by applying the functional liquid is a light emitting layer that forms an electroluminescence element, and the functional liquid is a light emitting material that forms the light emitting layer. It is characterized by including.

  Thus, by making the height of the formed display element from the substrate different between the adjacent pixel regions, the distance between the formed functional layers becomes longer. As a result, the creepage distance of the bank between adjacent pixel regions can be increased, so that even if a light emitting layer is formed by spraying and applying a functional liquid containing a light emitting material to each pixel region, the functional liquid Can be mixed. Therefore, the light emitting layer for forming the electroluminescence element can be formed by applying the functional liquid.

  Application Example 6 An electronic apparatus including the display device according to any one of Application Examples 1 to 5 described above.

  According to the display device, since the display device can have high-density pixels, an electronic device including the display device can display high-resolution characters and images.

  Hereinafter, the present invention will be described based on examples. FIG. 1 is an explanatory diagram showing a mobile phone 1 as an electronic apparatus equipped with a display device 100 according to an embodiment of the present invention. The display device 100 according to the present embodiment uses an organic EL as an electroluminescence element as a display element, and does not require a backlight and can be thinned. Therefore, the display device 100 is a thin type that displays images and characters with high resolution. This is a display device suitable for the electronic apparatus. Therefore, as in this embodiment, this is one of the display devices effective as a display device mounted on a mobile phone.

  A plurality of R (red), G (green), and B (blue) pixels are formed in the display device 100, and a predetermined image such as a color image or a character is displayed. In the present embodiment, in order to simplify the following description, as shown in FIG. 1, the display device 100 includes four pixels in the column direction (vertical direction in the drawing) and six pixels in the row direction (horizontal direction in the drawing). It is assumed that a total of 24 pixels are formed. Needless to say, in practice, many pixels such as several hundred pixels are formed in the direction of each matrix.

  Next, the display principle of the display device 100 of this embodiment will be described in sequence with reference to FIG. 2 and the structure of an organic EL serving as a display element with reference to FIG.

  FIG. 2 is a schematic diagram showing the overall layout of the display device 100 together with the circuit configuration. The display device 100 is an active matrix type device that is driven for display for each pixel as shown in the figure. Each pixel has an area divided in an oval shape by a bank, is regularly arranged in a matrix at the center of the substrate 10, and is formed on the substrate 10. Of course, each pixel may be partitioned into a shape other than an oval shape by a bank, and the arrangement may be irregular.

  In each pixel, an organic EL described later is formed as a display element, and TFTs (thin film transistors) 14 and 15 for driving the organic EL to display (that is, light emission) and a storage capacitor 16 are formed as a drive element. In this embodiment, the organic EL has a top emission structure. Therefore, the driving element is positioned so as to overlap the display element in a plan view, and is formed between the substrate 10 and the display element.

  A scanning drive circuit 11, a data drive circuit 12, and a power supply terminal 13 are formed on the outer peripheral portion of the substrate 10. The scanning drive circuit 11 has a scanning line Gate, the data drive circuit 12 has a data line Sig, and the power supply terminal 13 has a power supply line Com connected to the drive element formed in each pixel. On the other hand, wiring is performed as shown in FIG. 2, and the display element is driven to emit light.

  First, the scanning line Gate is connected to the gate of the TFT 14 and performs on / off control of the TFT 14 in accordance with a current signal supplied via the scanning line Gate. When the TFT 14 is turned on, a predetermined voltage is held in the holding capacitor 16 by the power supplied from the power supply line Com in accordance with the image signal supplied from the data line Sig connected to the source of the TFT 14. Then, the voltage held in the holding capacitor 16 is applied to the gate of the TFT 15 to turn on the TFT 15. The source and drain of the TFT 15 are connected to the power supply line Com and the anode 120, respectively, and a current corresponding to the voltage held in the storage capacitor 16, that is, a current corresponding to an image signal is applied to the anode 120 via the power supply line Com. Is done.

  The display element formed in each pixel emits light by passing a current between the anode 120 and the cathode 180 (see FIG. 3). Therefore, the current applied to the anode 120 flows to the cathode 180 (not shown) formed over the surface of all the pixels, thereby emitting light with brightness according to the image signal. The display device 100 displays the image in this way.

  Next, a specific pixel structure in the display device will be described with reference to FIG. FIG. 3 is a schematic diagram illustrating a pixel configuration of the display device before application of the present embodiment. FIG. 3A is a plan view showing any three pixels arranged in the row direction (the horizontal direction in the drawing) among the pixels shown in FIG. 2, and FIG. It is the schematic cross section which showed the AA cross section in a), and has shown the state which formation of the display element was complete | finished. FIG. 3C is a schematic diagram showing a state in which a functional layer of organic EL is applied and formed by jetting a functional liquid. In addition, since each dimension is exaggerated as needed for convenience of explanation, it goes without saying that the actual dimension does not necessarily match.

  As shown in FIG. 3A, each pixel has a pixel region partitioned by a bank (hatched portion in the figure) made of an insulating organic material (for example, acrylic resin or polyimide resin) formed by etching, Each has an oval shape. In the pixel area of each pixel, display elements are formed so that the respective RGB emission colors are arranged in a predetermined arrangement. In this embodiment, each pixel is repeatedly arranged in the order of R, G, and B in the row direction. Therefore, FIG. 3A shows a state in which three pixel portions in which R pixels, G pixels, and B pixels are arranged in order in the row direction are extracted from a plurality of arranged pixels.

  Further, as shown in FIG. 3B, the display element includes a hole injection layer 140 and each light emitting layer (R light emitting layer 150, G light emitting layer 160, B light emitting layer) between the anode 120 and the cathode 180. 170). Therefore, when the formed light emitting layers are different, R pixels, G pixels, and B pixels having different emission colors are obtained.

  In this example, the hole injection layer 140 is made of PEDOT (polyethylenedioxythiophene) / PSS (polystyrene sulfonic acid) functional liquid (PEDOT: PSS weight ratio = 1: 50, solid content concentration 0.5%, solvent: After spraying diethylene glycol (50%, remaining pure water) onto the pixel region, vacuum drying and heat treatment (200 ° C., 10 minutes) are performed to form a PEDOT / PSS film having a thickness of 50 nm. In addition, each light emitting layer is sprayed with a functional liquid using a fluorescent material exhibiting each color of RGB as a solute and 100% cyclohexylbenzene as a solvent so that the weight of the functional liquid in each pixel region is the same, and thereafter vacuum dried. And a heat treatment in a nitrogen atmosphere (130 ° C., 1 hour) to form films each having a thickness of 100 nm.

  An inorganic insulating film 130 is formed between the bank and the anode 120 so that a predetermined width is exposed in the pixel region along the outer periphery of the oval pixel region. This enhances the lyophilicity with the functional liquid that forms the hole injection layer 140 and the light emitting layers 150, 160, 170, and the hole injection layer 140 and each light emitting layer (150, 160, 170) are properly located near the bank. This is to prevent a short circuit between the anode 120 and the cathode 180 by being formed. Of course, when the hole injection layer 140 and the light emitting layers 150, 160, and 170 can be properly formed near the bank, the inorganic insulating film 130 does not need to be formed.

  Further, since the display element of this embodiment is a top emission type organic EL, a reflective layer 110 is provided on the surface side of the anode 120 facing the substrate 10 so that the emitted light is emitted from the cathode 180 side. Is formed. Of course, when the anode 120 also serves as the reflective layer 110, the reflective layer 110 need not be formed.

  For example, Al is suitable as the reflective layer 110. The anode 120 is not limited to a light-transmitting material such as ITO (indium tin oxide), but may be a non-light-transmitting material such as tin oxide, gold, silver, or copper. The cathode 180 is made of a light transmissive material such as ITO. Of course, a metal material may be used as a cathode material as long as it is thin enough to transmit light. In this embodiment, the cathode 180 also serves as an electron injection layer and is formed by vapor deposition of LiF (thickness 5 nm) and Al (thickness 5 nm).

  In this embodiment, as can be seen from the description of FIG. 3, if the display element is a G pixel, for example, each of the reflective layer 110, the anode 120, the hole injection layer 140, the G light emitting layer 160, and the cathode 180. Consists of functional layers. It should be noted that a method for forming a layer related to each functional layer such as the hole injection layer 140 and each light emitting layer (150, 160, 170) for forming an organic EL serving as a display element, and the like that can be used as such each functional layer. Since the formation method and material currently disclosed, for example in patent document 1 etc. which were mentioned above can be applied about this material, description is abbreviate | omitted here.

  Incidentally, as described above, the driving element for driving the display element to emit light is formed between the substrate 10 and the display element at a position overlapping the display element in a plan view. In this embodiment, as shown in FIG. 3B, the TFTs 14 and 15 and the storage capacitor 16 as driving elements are located between the substrate 10 and the inside of the device layer 20 whose entire surface is flattened. Is formed. The drain electrode of the TFT 15 is connected to the anode 120 (or the reflective layer 110) in a portion other than the pixel region so as not to affect the film thickness of each light emitting layer by a through hole (not shown) formed in the device layer 20. Has been.

  Since the device layer 20 is not the essence of the present embodiment, a specific configuration description is omitted here. Further, in the drawings used for the following description, it is assumed that they are included in the substrate 10. Therefore, the height from the substrate 10 in the following description indicates the height from the planarized device layer 20. Of course, when the device layer 20 is not flat, it means the height from the plane of the substrate 10.

  In this embodiment, the hole injection layer 140 and each light emitting layer (150, 160, 170) are formed by spraying and applying a functional liquid to the pixel region. At this time, as shown in FIG. 3C, for example, when the G function droplet is ejected from the ejection head, even if the ejection head is displaced from the correct landing position (for example, the center of the pixel area), If a sufficient distance is secured between the applied R functional liquid (or B functional liquid) and the G functional liquid depending on the creepage distance, the applied G functional liquid is positioned as indicated by the broken line in the figure. Even if the shift occurs, mixing with the R functional liquid is suppressed. Further, the creeping surface of the bank is subjected to a liquid repellent treatment, and the G functional liquid is devised so as to return to the correct landing position by the surface tension. Thus, an organic EL corresponding to each pixel of RGB is formed on the substrate 10 as a display element.

  As for an example of a pixel array having a high-definition pattern with an increased pixel density, a problem that occurs in the formation of the display element when the pixel spacing in the row direction is reduced is shown in FIG. 4 will be described.

  FIG. 4A shows a case where the pixel interval in the row direction (horizontal direction in the drawing) is reduced in the pixel array shown in FIG. As shown in the figure, in the RGB image areas partitioned by the banks, the intervening banks are close to each other in the width of BW in the row direction. In such a case, the bank shape to be formed is shown in FIG.

  FIG.4 (b) is a schematic diagram which shows the BB cross section in Fig.4 (a). As shown in the figure, the bank is formed so that the height of the bank is higher by BH than the shape shown in FIG. By doing so, the creepage distance reduced by the narrowing of the bank width in the plane direction is increased in the height direction. For example, even when the landing position of the G functional liquid ejected from the ejection head is deviated. As shown in the figure, the creepage distance is secured, and it can be expected that the G functional liquid is prevented from being mixed with the R functional liquid.

  However, the bank shape shown in FIG. 4B may cause the following problems. For example, since the height of the wall surface of the bank is considerably higher than the width of the bank, the bank breaks or the like occurs. Further, the ejected functional liquid cuts the bank like a knife. As a result, even if the bank is subjected to the liquid repellent treatment, it is possible that the functional liquid is blocked by the surface tension and the sprayed functional liquid is not applied to the pixel region position. Alternatively, when the bank is formed by etching, the bank does not remain due to variations in the etching amount, or the wall surface height of the bank becomes low. In such a case, the functional liquid to be ejected cannot be retained in each pixel region, and the functional liquids are mixed with each other.

  Therefore, the display device according to the present embodiment is a display device capable of displaying a high-definition pattern, can stably form a bank, and is correctly applied to the pixel region without being mixed with the ejected functional liquid. A display device capable of forming an element is realized. This will be described with reference to FIGS.

  FIG. 5 shows the state of the bank formed when the pixel interval in the row direction (horizontal direction in the drawing) is reduced to increase the pixel density in the pixel array shown in FIG. Each of the RGB image areas partitioned by the bank is assumed to have a bank interval close to the BW width in the row direction, as in FIG. 4A. At this time, as shown in FIG. 5, the R pixel region and the B pixel region are pixel regions that are partitioned by banks as in FIG. 4A, and are adjacent to the G pixel region (and next to the B pixel region (right side of the drawing)). For the (R pixel region), unlike the case of FIG. 4A, a bank is formed to extend over the entire pixel region.

  FIG. 6 is a schematic diagram showing a CC cross section in FIG. 5. As shown in the figure, in order to increase the creepage distance of the bank between adjacent pixels, the height of the bank is increased by BH as in FIG. Unlike FIG. 4B, the G pixel region (and the adjacent R pixel region) is formed so that the height from the substrate 10 is higher by RH1 than the R pixel region and the B pixel region. Yes. Of course, in this embodiment, banks are formed to extend every other pixel in the row direction so that the height of the pixel region from the substrate 10 is increased by RH1, and the pixel regions of the substrate 10 are adjacent to each other between adjacent pixel regions. The height from is different. Accordingly, in FIG. 5, the R pixel and the B pixel are pixel regions having a lower height from the substrate 10 in the pixel region, and the G pixel (and the adjacent R pixel) are the heights from the substrate 10 in the pixel region. Is the higher pixel region.

  As a result, the bank height dimension of the portion where the bank width becomes narrower to BW can be made shorter than the shape shown in FIG. Accordingly, the bending stress applied to the bank is reduced by reducing the height of the narrow bank portion, so that the breakage of the bank is suppressed. In addition, when a bank is formed by etching, even if there are variations in the etching amount, the etching depth for forming one pixel region is small, so the etching amount for forming one wall surface of the bank is small. Therefore, the probability that the bank remains is higher than that in the case where the both sides of the bank are etched deeply. Further, since the height of the narrow bank is suppressed to be low, the possibility that the bank cuts the ejected functional liquid like a knife becomes low. As a result, the functional liquid can be integrated together by the surface tension accompanying the liquid repellent treatment applied to the surface of the bank. As a result, the display element is correctly formed.

  The height dimension RH1 from the substrate 10 is preferably determined according to the bank width BW between the pixels and the increased bank dimension BH. For example, the raised bank dimension BH may be the value of the height dimension RH1. Alternatively, in order to collect all the functional liquid ejected from the substrate 10 to the pixel region having a high height, the height dimension required for the bank wall surface defining the pixel region is obtained, and from the obtained bank wall height The value of the height dimension RH1 may be calculated. Further, the value of the height dimension RH1 may be different for each pixel. This is because when the total amount of functional liquid ejected to the pixel region is different or the value of the surface tension is different, the required wall height is different.

  Here, in the display device of this embodiment, as shown in FIG. 6, in the pixel region where the bank extends, the reflective layer 110, the anode 120, and the inorganic insulating film 130 are formed on the extending bank. It will be. That is, the reflective layer 110, the anode 120, and the inorganic insulating film 130 are formed on the bank every other pixel in the row direction like the G pixel region (and the adjacent R pixel region) having the higher pixel region. . Therefore, in this embodiment, the reflective layer 110, the anode 120, and the inorganic insulating film 130 corresponding to the R pixel region and the B pixel region are first formed on the substrate 10, and then the bank is formed on the entire surface, and then the bank is etched. Thus, each pixel region is formed. At that time, the R pixel region and the B pixel region are fully etched to completely remove the bank, while the G pixel region (and the adjacent R pixel region) is half-etched, and the height from the substrate 10 becomes RH1. It is formed by leaving the bank surface. Then, the reflective layer 110, the anode 120, and the inorganic insulating film 130 are formed again on the bank in the formed G pixel region (and the adjacent R pixel region).

  Therefore, in this embodiment, the reflective layer 110 and the anode 120 formed in the pixel region having a higher height from the substrate 10 (for example, the G pixel region) have an oval shape substantially the same shape as the pixel region. Although the detailed description is omitted, the connection with the TFT 15 can be performed by providing a through hole (not shown) in the bank and the anode 120 (or the reflective layer 110) having an oval shape.

  As described above, according to the display device of this embodiment, the creepage distance of the bank between the adjacent pixel regions can be secured, so that the functional liquid applied to the pixel region in order to form the display element. However, mixing between adjacent pixel regions can be suppressed. In addition, even when the pixel interval is narrow, the height of the narrow bank can be suppressed low, so that the bank can be formed stably.

  Although the present invention has been described using one embodiment as described above, the present invention is not limited to such an embodiment and can be implemented in various forms without departing from the spirit of the present invention. Of course. Hereinafter, a modification will be described.

(First modification)
In the above-described embodiment, for example, as illustrated in FIG. 6, the bank shape between the pixels has been described as having a positive taper shape that increases in width as it approaches the substrate 10 side. In this modification, the pixel region is at least in the direction in which the space between the pixels is narrowed (in the row direction in the above embodiment) among the wall surface shapes of the banks that define the lower pixel region from the substrate 10. The wall surface shape of the partitioning bank may be formed in an inversely tapered shape in which the opening area of the pixel region increases as it approaches the substrate 10. By doing this, even if a part of the functional liquid ejected to the pixel area flows into the adjacent pixel area, the probability that the functional liquid that has flowed in remains on the wall surface portion of the formed reverse tapered shape is increased. Can do. As a result, it can be expected that mixing with the functional liquid ejected to adjacent pixel regions is suppressed.

  This modification will be specifically described with reference to FIG. FIG. 7A shows a state of the bank formed when the pixel interval in the row direction (the horizontal direction in the drawing) is reduced, as in FIG. Here, in the present modification, among the RGB image areas partitioned by the bank, in the row direction, at least each pixel area is located in an area close to each other (area T surrounded by a one-dot chain line in the drawing). The wall surface shape is a reverse taper. The reverse taper shape will be described with reference to FIG.

  FIG.7 (b) is a schematic diagram which shows the DD cross section in Fig.7 (a). As shown in the figure, for the R pixel region and the B pixel region, the wall surfaces of the banks in the row direction are formed in a reverse taper in which the opening area of the pixel region increases (the width increases) as it approaches the substrate 10. The inversely tapered shape can be formed by a known technique such as anisotropic etching, etching solution concentration control, or plasma etching. Note that it is needless to say that a reverse taper can be formed in the bank because one of the adjacent pixel regions is extended so that the height from the substrate 10 is increased.

  As a result, for example, as shown in the drawing, even when the G functional liquid ejection position is shifted and a part flows into the adjacent R pixel region, the angle formed by the wall surface of the reverse tapered portion and the surface of the substrate 10 is an acute angle. Therefore, there is a high probability that the G functional liquid that has flowed in stays in the reverse tapered portion due to the surface tension. Therefore, mixing with the injected R functional liquid can be suppressed. Even if they are mixed, the mixed region can be expected to remain at the end of the pixel region, so that the influence on the display performance of the formed display element can be suppressed.

  Further, in the present modification, the wall surface of the bank that defines the lower pixel region from the substrate 10, and the higher one from the adjacent substrate 10 in the vicinity of the boundary with the pixel region. You may make it perform a lyophilic process with respect to the functional liquid injected to a pixel area. By doing so, the functional liquid that has flowed in easily adheres to the lyophilic-treated bank wall surface, so that the probability of staying in the vicinity of the periphery of the pixel region can be further increased.

  An example of this modification is shown in FIG. As shown in the figure, the bank is formed of two layers, an upper bank and a lower bank, and the lower bank formed on the substrate 10 side, for example, is injected into a G pixel region having a higher height from the substrate 10. It is formed of a material having lyophilicity with respect to the functional liquid or a material that can be lyophilicly processed. The upper bank is formed of a material having liquid repellency with respect to the G functional liquid sprayed to the G pixel region or a material capable of liquid repellency treatment. For example, the upper bank may be formed of a polyimide resin, and the lower bank may be formed of the same material as the inorganic insulating film 130.

  In the first modification, when the cathode 180 (see FIG. 3) is formed by vapor deposition, the cathode 180 may be cut off in the bank portion where the reverse taper is formed. . Therefore, when the cathode 180 is formed by vapor deposition in the first modified example, at least a part of the wall surface of the bank defining the pixel region having a lower height from the substrate 10 is made to be a positive taper. Is preferred. Of course, in the case of forming a reverse taper in the entire circumference of the pixel region, the cathode 180 is formed by a method other than vapor deposition (for example, thick film printing). It is preferable that electrical connection is possible.

(Second modification)
In the above embodiment, as described with reference to FIG. 6, the pixel region having the higher height from the substrate 10 is formed by half etching of the bank. Therefore, although the probability that the bank will be destroyed by reducing the height dimension of the narrow bank portion is reduced, a bank having a narrow width remains between the pixel regions, and the risk of destruction of the bank. Will survive. Therefore, in this modification, the pixel region is partitioned without forming a narrow bank. In this way, bank destruction is avoided and bank formation is facilitated. This modification will be described with reference to FIG.

  FIG. 8A is the same as the schematic cross-sectional view of the display device of the above-described embodiment shown in FIG. As shown in the figure, in the above-described embodiment, the bank between pixels is made higher by BH in order to increase the creepage distance of the bank as described above. For this reason, a bank having a narrow width (FIG. 5, BW) is present between adjacent pixel regions.

  On the other hand, in this modification, as shown in FIG. 8B, the height of the pixel region from the substrate 10 is set to a height RH2 equal to the height of the bank. Specifically, the half-etching described above may not be performed. In this way, since a narrow bank is not formed, it is possible to avoid the risk of the bank being destroyed.

  In the case of this modification, it is preferable that the pixel region having a higher height from the substrate 10 is partitioned by the inorganic insulating film 130 instead of being partitioned by the wall surface of the bank. In this way, due to the lyophilicity of the inorganic insulating film 130, for example, as shown in the drawing, the G function injected into the G pixel region by the lyophobic treatment and the lyophilic inorganic insulating film 130 applied to the bank surface. It is possible for the liquid to remain in the partitioned G pixel area. Therefore, for example, a display element can be formed without being mixed with the R functional liquid sprayed to the adjacent R pixel region.

(Third Modification)
In the above embodiment, the display device is described as having a high-definition pattern by increasing the pixel density by narrowing the pixel interval in the row direction. However, the pixel density may be increased by narrowing the pixel interval in the column direction. In this case, although explanation is omitted, a bank may be extended every other pixel in the column direction to increase the height of the pixel region from the substrate 10.

  Further, the pixel density may be increased by narrowing the pixel interval at the same time in the row direction and the column direction. An example of this case is shown in FIG. As shown in the drawing, if the pixel areas partitioned by the banks are arranged such that the pixel areas with a high height and the low pixel areas from the substrate 10 are staggered in the row direction and the column direction. Good.

(Other variations)
In the above-described embodiment, the display device is described as being mounted on a mobile phone. However, the display device is not limited to this and may be mounted on an electronic device other than the mobile phone. For example, the display device of this embodiment and the modification is suitable for an electronic device that is desired to display a high-definition pattern, such as a video camera, a digital camera, or a portable personal computer.

  In the above embodiment, the top emission method is described in which the emission direction of the emitted light of the display element is the cathode side. However, the present invention is not limited thereto, and the bottom is the emission direction of the emitted light of the display element. It may be an emission method. In this case, the material of the substrate may be a light transmissive material (for example, glass). In addition, since a driving element such as a TFT cannot overlap with the light emitting element in a planar manner, a device layer is not interposed between the substrate and the display element. Therefore, in the case of bottom emission, the height of the pixel region from the substrate does not include the device layer.

  In the above embodiment, when the bank width is narrowed, the height of the bank is uniformly increased by BH. However, the present invention is not limited to this. For example, when the creepage distance required for the banks between adjacent pixel regions differs according to the surface tension of each RGB functional liquid, a necessary step is formed between the adjacent pixel regions according to the creepage distance. As described above, the bank height may be determined for each pixel region.

  In the above embodiment, the organic EL is formed as the electroluminescence element, and the functional layers formed by applying the droplets by jetting are described as the hole injection layer and the light emitting layer. Of course, it is not limited to this. For example, when an electron injection layer is formed separately from the cathode, the electron injection layer may be a functional layer formed by droplet ejection. Alternatively, in the case where the light emitting layer also serves as the hole injection layer, only the light emitting layer may be a functional layer formed by application of droplets. Further, the electroluminescence element is not limited to the organic EL, and may be an inorganic EL. In short, any functional layer may be used as long as it is applied and formed by jetting droplets in the functional layer constituting the display element.

  Moreover, although the case where an electroluminescence element is formed as a display element has been described in the above embodiment, the present invention is not necessarily limited to this as long as it functions as a display element. For example, a light emitting diode may be formed in the pixel region, or an RGB color filter layer may be formed in the pixel region as a display element. Of course, in such a case, it goes without saying that the functional layer to be formed is different from the above embodiment.

  In the above embodiment, the bank is extended to the pixel area so that the height of the pixel area from the substrate 10 is increased. However, the height of the pixel area may be increased using other than the bank. Good. For example, the inorganic insulating film 130 formed in the pixel region having a lower height from the substrate 10 may be used. In this case, the inorganic insulating film 130 also functions as a bank that partitions a pixel region having a lower height from the substrate.

  In the first modified example, the functional liquid is sprayed onto the bank wall surface in the vicinity of the boundary with the lower pixel region from the substrate 10 to the higher pixel region from the adjacent substrate 10. However, it is needless to say that the present invention may be carried out in the above-described embodiment or the second modification.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed the mobile telephone carrying the display apparatus used as one Example of this invention. The schematic diagram which showed the whole layout of the display apparatus with the circuit structure. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the pixel structure of the display apparatus before application of a present Example, (a) is the top view, (b) is the sectional drawing, (c) is a schematic diagram which shows a mode when a functional liquid is injected. . FIG. 2 is an explanatory diagram of a bank formed when the pixel interval is reduced before application of the present embodiment, (a) is a plan view thereof, and (b) is a sectional view thereof. An explanatory view of a bank formed when a pixel interval is reduced in this embodiment. FIG. 6 is a schematic diagram illustrating a partial cross section of the display device of the present embodiment. FIG. 6 is a schematic diagram illustrating a pixel configuration of a display device according to a first modification, where (a) is a plan view thereof, (b) is a sectional view thereof, and (c) is a schematic sectional view illustrating a further modification example of the first modification example. FIG. 6 is a schematic diagram illustrating a pixel configuration of a display device according to a second modification, where (a) is a cross-sectional view illustrating a pixel structure before application of the modification, and (b) is a cross-sectional view illustrating a pixel structure to which the modification is applied. . The schematic diagram which shows the pixel structure of the display apparatus of a 3rd modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Mobile phone, 10 ... Board | substrate, 11 ... Scanning drive circuit, 12 ... Data drive circuit, 13 ... Feed terminal, 14, 15 ... TFT, 16 ... Retention capacity, 20 ... Device layer, 100 ... Display apparatus, 110 ... Reflection Layer 120, anode, 130, inorganic insulating film, 140 hole injection layer, 150, R emission layer, 160, G emission layer, 170, B emission layer, 180, cathode.

Claims (6)

A display device in which a pixel region partitioned in a matrix by banks is provided on a substrate, and a display element including a predetermined functional layer is formed in the pixel region,
At least one of the functional layers is a functional layer formed by application of a functional liquid,
In at least the pixel regions of the partitioned rows or the partitioned columns, the surfaces of the display elements formed in the adjacent pixel regions facing the substrate are different from each other in height from the substrate. A display device characterized by that. The display device according to claim 1,
In the creeping area of the bank located between the adjacent pixel areas, the functional liquid applied to the pixel area is formed around the pixel area where the display element having a higher height from the substrate is formed. The liquid repellent treatment is performed, and the display element having the higher height from the substrate is formed around the pixel region where the display element having the lower height from the substrate is formed. A display device, wherein a lyophilic process is performed on the functional liquid applied to a pixel region. The display device according to claim 1, wherein
The creeping shape of the bank includes a reverse taper shape in which an opening area of a pixel region in which the display element having a lower height from the substrate is formed becomes larger toward the substrate. . The display device according to any one of claims 1 to 3,
In the pixel region where the display element whose height is higher from the substrate is formed, the bank extends so as to contact the surface of the display element facing the substrate. Display device. A display device according to any one of claims 1 to 4,
The functional layer formed by application of the functional liquid is a light emitting layer that forms an electroluminescence element, and the functional liquid includes a light emitting material that forms the light emitting layer.   The electronic device provided with the display apparatus as described in any one of Claims 1 thru | or 5.

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