JP2016100126A - Organic EL panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL panel of a segment display type with a see-through structure, having an excellent display quality.SOLUTION: An organic EL panel comprises: a substrate 10 having light transmissivity; and an organic layer 30 including a first electrode 20, a second electrode 40, and at least luminous layer. The first electrode 20 has the light transmissivity, and is formed in a shape equivalent to a segment S, and the second electrode 40 does not have the light transmissivity, and is formed by a plurality of band electrodes 41 extending in a first direction viewed from a substrate normal direction. The plurality of band electrode 41 is arranged in a predetermined pitch P in a second direction crossing to the first direction. A width D of the second direction of segment S is nearly 1/n times larger than the pitch P (n is a natural number that is equal 2 or more), and when viewing from the substrate normal direction, a gap formed between the plurality of band electrodes 41 becomes a translucent region.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an organic EL panel, and more particularly to a segment display type organic EL panel having a see-through structure.

  As a conventional organic EL (Electro-Luminescence) panel, there is one disclosed in Patent Document 1, for example. In the organic EL panel of Patent Document 1, an organic EL element in which a transparent electrode (anode), an organic EL layer, and an opaque electrode (cathode) are stacked is formed on a transparent substrate so as to constitute a pixel. The display unit is arranged in a matrix, and the anode and the cathode formed in a strip shape are orthogonal to each other, and the cathode is arranged so as to cross a pair of opposite sides of the pixel. . As a result, a see-through panel capable of transmitting light through a portion of the display portion where no cathode is disposed is realized.

JP 2011-23336 A

  Although the organic EL panel of Patent Document 1 is configured on the premise of dot matrix display, there is a current situation in which a segment display type having excellent display element clarity and the like is required depending on applications. However, in order to maintain the display quality of the organic EL panel having a see-through structure, a method specialized for the segment display type has not been sufficiently established.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a segment display type organic EL panel having a see-through structure and good display quality.

In order to achieve the above object, the organic EL panel according to the present invention includes:
An organic EL panel that lights up and displays a segment,
A substrate having translucency;
A first electrode and a second electrode provided on the substrate;
An organic layer provided on the substrate and positioned between the first electrode and the second electrode and including at least a light-emitting layer,
The first electrode has translucency and is formed in a shape corresponding to the segment,
The second electrode is not translucent and includes a plurality of strip electrodes extending in a first direction when viewed from the normal direction of the substrate, and the plurality of strip electrodes intersects the first direction. Arranged in a second direction with a predetermined pitch,
The width of the segment in the second direction is approximately n times the pitch (n is a natural number of 2 or more),
As seen from the normal direction, a space between adjacent ones of the plurality of strip electrodes is a light-transmitting region.
It is characterized by that.

  According to the present invention, a segment display type organic EL panel having a good display quality and a see-through structure can be provided.

It is a schematic front view of the organic electroluminescent panel which concerns on one Embodiment of this invention. (A) is the AA line schematic sectional drawing of the organic electroluminescent panel shown in FIG. 1, (b) is the schematic diagram which represented the relationship between a 1st electrode and a 2nd electrode corresponding to Fig.2 (a). It is. (A) is a table | surface figure which shows the segment appearance evaluation depending on the pitch of a strip | belt-shaped electrode, (b) is a table | surface figure which shows transparency evaluation depending on the width | variety of a strip | belt-shaped electrode. It is a figure for demonstrating the calculation conditions for finding a suitable segment width. (A) is the figure of the table | surface which shows the calculation result of the light emission area with respect to the shift | offset | difference of the 2nd electrode on the conditions shown in FIG. 4, (b) is the figure which showed the calculation result of Fig.5 (a) with the graph. . 10 is a schematic diagram showing a second electrode according to Modification 1. FIG. 10 is a schematic diagram showing a second electrode according to Modification 2. FIG.

  An organic EL panel according to an embodiment of the present invention will be described with reference to the drawings.

An organic EL (Electro-Luminescence) panel 100 according to the present embodiment has a see-through structure described later. As shown in FIGS. 1 and 2, a substrate 10, a first electrode 20, and an organic layer. 30, a second electrode 40, a sealing plate 50, a variable display unit 60 and a fixed display unit 70, which are display units for lighting and displaying segments, and an IC (Integrated Circuit) 80 for driving the display unit. .
A segment (display element) represents a figure, a symbol, an icon, and the like, and represents predetermined information in one or a plurality of combinations. The organic EL panel 100 is of a static drive type, and displays numerical values by a combination of hexagonal segments S that are lit in the variable display section 60 (seven-segment display in the illustrated example). Note that the display is not limited to 7-segment display, and the predetermined display may be performed with fewer than 7 segments or a combination of more than 7 segments. Moreover, in the fixed display part 70, although not shown in figure, the segment showing an icon etc. is light-displayed.

  In the following, in order to facilitate understanding of the configuration, as shown in FIG. 1 and the like, the X axis along the left and right direction as viewed from the user viewing the display surface of the organic EL panel 100, the Y axis along the up and down direction, The description will be made as appropriate using the X axis and the Z axis orthogonal to the Y axis. Also, the direction in which the arrow indicating each axis faces is the + (plus) direction of each axis, and the opposite direction is the-(minus) direction.

  The substrate 10 has translucency and is formed, for example, in a rectangular shape in front view. The substrate 10 is made of glass (non-alkali glass or alkali glass) or resin. The normal direction of the main surface of the substrate 10 (hereinafter referred to as the substrate normal direction) coincides with the Z-axis direction. On the back surface (the surface on the −Z side) of the substrate 10, the first electrode 20, the organic layer 30, and the second electrode 40 are sequentially stacked.

  The first electrode 20 is a transparent electrode (translucent electrode), and functions as an anode for injecting holes in this embodiment. As shown in FIG. 2B, the first electrode 20 is formed in a shape corresponding to a segment. For example, the first electrode 20 is formed by forming a transparent conductive material such as ITO (Indium Tin Oxide), AZO (Aluminum Zinc Oxide), or IZO (Indium Zinc Oxide) on the back surface of the substrate 10 by sputtering (for example, film thickness). 50 to 500 nm), and is formed by patterning into a desired shape by a photolithography method. Although not shown, the anode wiring that connects the first electrode 20 and the IC 80 and the cathode wiring that connects the second electrode 40 and the IC 80 are formed on the substrate 10 with the same material in the same process as the first electrode 20. It is formed.

A transparent insulating film (not shown) that covers a part of the first electrode 20 is formed on the back surface of the substrate 10. This insulating film is formed, for example, by forming a transparent insulating material such as polyimide resin, novolac resin, or acrylic resin on the substrate 10 by spin coating and patterning it into a desired shape by photolithography. The transparent insulating film is provided to prevent a short circuit between the first electrode 20 and the second electrode 40 or to pattern the first electrode 20 into a predetermined shape. For example, the first electrode 20 in the variable display unit 60 is formed in a shape corresponding to the segment S only by patterning of the transparent electrode, while the first electrode 20 in the fixed display unit 70 is mainly segmented by patterning of the transparent insulating film. It is formed in a shape corresponding to.
That is, “the first electrode 20 is formed in a shape corresponding to a segment” is not limited to the patterning of the transparent electrode, but may be realized by using a transparent insulating film in combination.

  The organic layer 30 includes an organic light emitting layer made of an organic material, and is configured as a single layer or multiple layers. The organic layer 30 is formed on the first electrode 30 with a film thickness of, for example, about 60 nm to 150 nm. As an example of the multilayer structure, a hole injection transport layer, a first organic light emitting layer, a second organic light emitting layer, an electron transport layer, and an electron injection layer are sequentially stacked from the first electrode 20 side. . As long as the organic layer 30 includes a single organic light emitting layer, the organic layer 30 may not include a part of the above-described layers, or may include other layers. The organic layer 30 is formed in a desired shape on the back side of the substrate 10 through a vapor deposition mask, for example, by a vacuum vapor deposition method. The organic layer 30 may be formed by a coating method such as spin coating or a printing method such as inkjet.

  The second electrode 40 is an opaque electrode, and functions as a cathode for injecting electrons in this embodiment. The second electrode 40 is a low-resistance conductive film formed on the organic layer 30 (for example, formed from a single metal or an alloy such as Al, Ag, Mg, Co, Li, Zn, etc., with a film thickness of 50 to 200 nm. Have been). The second electrode 40 is formed on the back side of the substrate 10 through a vapor deposition mask, for example, by a vacuum vapor deposition method. As shown in FIG. 2B, the second electrode 40 is composed of a plurality of strip electrodes 41 extending in the Y direction, and has a stripe shape.

  The strip electrode 41 is formed such that its width (length in the X direction; hereinafter, width W) is 1 mm or less (W ≦ 1 mm). Moreover, it arrange | positions so that the distance (space | interval in the X direction between mutual centerlines. Hereinafter, pitch P) between the strip | belt-shaped electrodes 41 adjacent may become equal. The pitch P is set to 2 mm or less (P ≦ 2 mm). The segment width D that is the width of the segment S in the X direction (that is, the width of the first electrode 20 corresponding to one segment S in the X direction) is approximately n times the pitch P (n is a natural number of 2 or more). (Including exactly n times). The reason why the width W, the pitch P, and the segment width D are set in this way will be described later.

As shown in FIG. 1, the organic EL panel 100 includes, as the segment S, a first segment S1 extending in the Y direction and a second segment S2 extending in the X direction. FIG. 2B shows an example in which the segment width D of the second segment S2 is approximately a natural number times the pitch P, but the segment width D of the first segment S1 is also approximately a natural number times the pitch P. It is preferable. However, if at least one of the first segment S1 and the second segment S2 is substantially n times the pitch P of the strip electrode 41, the display quality of the organic EL panel 100 can be kept good for the reason described later.
Although not shown, it is preferable that the width of the segment in the fixed display unit 70 is also a substantially natural number of the pitch P of the strip electrode 41.

  The sealing plate 50 has translucency and hermetically accommodates each part on the substrate 10 described above. The sealing plate 50 is formed in a concave shape from, for example, a glass material by molding, sandblasting, cutting, etching, or the like, and is provided on the substrate 10 via an adhesive, for example. The sealing plate 50 may have a flat plate shape. In this case, the sealing plate 50 is provided on the substrate 10 via a spacer.

  The IC 80 is provided, for example, at an appropriate position on the substrate 10 and is connected to an external circuit via an unillustrated FPC (Flexible Printed Circuit board), and a variable display unit 60 and a fixed display unit according to information acquired from the external circuit. 70 and each of them are driven. As described above, the IC 80 is connected to the first electrode 20 via the anode wiring (not shown) and to the second electrode 40 via the cathode wiring (not shown). Supply drive current. Thereby, the organic light emitting layer in the region where the drive voltage is applied to the organic layer 30 emits light, and the segment is lit. The organic EL panel 100 according to the present embodiment is of a bottom emission type that emits light emitted from the organic light emitting layer from the substrate 10 side.

Although not shown, it is preferable to provide a UV (Ultraviolet) prevention layer (UV cut film, UV cut coating, etc.) on the light emitting surface (surface on the substrate 10 side) of the organic EL panel 100.
In an organic EL panel not having a see-through structure, a circularly polarizing plate is often provided in order to prevent reflection of external light. However, if a circularly polarizing plate is provided in an organic EL panel having a see-through structure, the light emitting surface becomes dark. Therefore, it is preferable not to provide the circularly polarizing plate in the organic EL panel according to this embodiment, but there is a concern that the organic layer 30 and the like are deteriorated by external light. The reason why it is better to provide a UV prevention layer is to prevent such deterioration. In addition, you may provide a UV prevention layer also in the back side (sealing board 50 side) of a panel.

In the organic EL panel 100 configured as described above, a slit portion formed between adjacent strip electrodes 41 transmits light. That is, external light from the front side of the panel (substrate 10 side) and external light from the back side of the panel (sealing plate 50 side) are transmitted. Further, as described above, the strip electrode 41 is formed with a narrow width W. For this reason, the organic EL panel 100 has a transmission structure (see-through structure) that allows the user to visually recognize a real scene (such as an object located on the back side of the panel) through the self.
On the other hand, the specific lighting region of the segment is a region where the first electrode 10 and the strip electrode 41 overlap in the substrate normal direction. Therefore, the thinner the opaque electrode 41 is, the greater the transmittance of external light that passes through the panel and the transparency of the panel can be secured, while the light emitting area of the segment decreases. That is, in the see-through structure as in the present embodiment, the external light transmittance of the panel and the luminance of the segment are in a trade-off relationship.
Therefore, in order to find suitable values of the pitch P and the width W of the strip electrode 41, the inventor of the present application created a prototype, and evaluated the appearance of the segment and the transparency of the panel. The evaluation results are shown in FIGS.

FIG. 3A shows the result of visual evaluation of the appearance of the lighting segment when the pitch P of the strip electrode 41 is changed while keeping the width W constant at 0.2 mm. The symbols in the “Look” evaluation column in the figure have the following meanings.

◎: The shape of the segment can be clearly recognized. ○: The shape of the segment can be recognized. △: The shape of the segment can be distinguished temporarily. ×: The shape of the segment is unknown.

Based on these evaluation results, the inventor of the present application has found that “the pitch P of the belt-like electrodes 41 is 2 mm or less” is preferable in consideration of the visibility of the lighting segment.

FIG. 3B shows the transparency of the panel when the width W of the belt-like electrode 41 is changed while ensuring the visibility of the lighting segment by keeping the pitch P of the belt-like electrode 41 constant at 2 mm. This represents the result of visual evaluation. The symbols in the “transparency” evaluation column in FIG.

◎: The background can be clearly seen through the panel. ○: The background can be seen through the panel. △: The background can be seen through the panel. ×: The background is unknown.

Based on these evaluation results, the inventor of the present application has found that “the width W of the strip electrode 41 is 1 mm or less” is preferable in consideration of the transparency of the panel.
In addition, the measured value of the transmittance | permeability (%) of a panel and the brightness | luminance (cd / m < ² >) of a segment was also described in FIG.3 (b) together with evaluation of transparency. From these measured values, it can be seen that the transmittance of the panel and the luminance of the segment are in a trade-off relationship.

As described above, the conditions for the strip electrode 41 that satisfies both the appearance of the segment and the transparency of the panel are determined.
However, if no countermeasures are taken, when the first electrode 10 and the second electrode 40 are relatively displaced in the X direction during electrode patterning or panel assembly (when misalignment occurs), 1 The number of the strip-like electrodes 41 to be overlapped with the first electrodes 10 corresponding to one segment is reduced, and the brightness of the segment may not be maintained, or the shape of the light emitting segment may not be clear.
Therefore, in order to obtain a suitable relationship between the segment (that is, the first electrode 20 corresponding to one segment) and the strip electrode 41, a simulation was performed using the calculation model shown in FIG. The simulation results are shown in FIGS.
In this simulation, the width W of the strip electrode 41 is fixed to 0.25 mm and the pitch P is fixed to 1.0 mm, and the first electrode 20 and the second electrode 40 are relatively moved in the X direction. It represents the misalignment. In FIG. 5A and FIG. 5B, this deviation is referred to as “second electrode deviation”.
The light emission area mm ² (that is, the width in the X direction of the first electrode 20 corresponding to one segment (that is, the segment width D) is 1.75 mm, 2 mm, 2.25 mm, and 2.5 mm. The area of the portion where the first electrode 20 and the second electrode 40 overlap was determined. The width in the Y direction of the first electrode 20 corresponding to one segment was fixed at 5.0 mm. The shape of the segment S is rectangular for convenience.

As can be seen from FIGS. 5A and 5B, when the segment width D is 2 mm, which is a natural number multiple of the pitch P, the displacement of the second electrode 40 is 0 mm to 0.75 mm. The light emission area is constant at 2.5 mm ² . On the other hand, when the segment width D is other than 2 mm (1.75 mm, 2.25 mm, 2.5 mm), it is understood that when the alignment shift occurs, the emission area of the segment varies.
Based on this result, the inventor of the present application can keep the light emitting area constant even if the alignment is deviated if the segment width D is approximately n times the pitch P (n is a natural number of 2 or more). It was thought that the display quality of the organic EL panel 100 can be kept good. Note that “nearly” “nearly” means that the width of the segment cannot be uniquely determined depending on the manufacturing error or the shape of the segment. In other words, the term “substantially n times” includes, as an idea, a configuration in which the segment width D is n times the pitch P.

  In addition, this invention is not limited by the above embodiment and drawing. Changes (including deletion of components) can be made as appropriate without departing from the scope of the present invention. An example of modification is shown below.

(Modification 1)
As shown in FIG. 6, in the display method using a combination of a plurality of segments (seven-segment display in the illustrated example), the segments may be formed obliquely in consideration of design. As a specific example, among the seven-segment components, the first segment S1 that extends substantially in the Y direction is inclined by a predetermined angle α (0 ° <α ≦ 20 °) with respect to the Y axis, while extending in the X direction. The second segment S2 is not tilted and represents a numerical value in italics.
In this case, it is preferable that the direction L in which the belt-like electrode 41 extends coincides with the direction in which the first segment S1 extends (that is, the direction L is also inclined by a predetermined angle α with respect to the Y direction). If it does in this way, it can prevent that the edge part of 1st segment S1 is visually recognized, and a display quality can be kept favorable.
In addition, this modification 1 is an example suitable as shown in FIG. 1 when the organic EL panel 100 is placed horizontally (that is, a substantially rectangular shape having a long side in the X direction as shown in FIG. 1). is there. When the organic EL panel 100 is placed vertically (that is, in a substantially rectangular shape having a long side in the Y direction), if the strip electrode 41 is formed to extend in the Y direction, the strip electrode 41 is formed to be long. Since the gradient becomes remarkable, it is not preferable. Therefore, when the organic EL panel 100 is placed vertically, it is preferable to form the strip electrode 41 so as to extend in the X direction (that is, to form the horizontal direction as viewed from the viewer of the display image).

(Modification 2)
In addition, when the segment S has a certain length in the longitudinal direction (for example, 30 mm or more), the unevenness of the brightness of the segment S in the longitudinal direction may occur due to the influence of the resistance (anode resistance) of the first electrode 20.
In order to prevent this, as shown in FIG. 7, in the region overlapping with the first electrode 20 corresponding to one segment S, the light emission luminance of the segment S is made uniform by changing the width W of the strip electrode 41. Is effective. Specifically, in consideration of the voltage drop, the width W of the strip electrode 41 is gradually increased (thickened) as the distance from the power feeding side increases, so that the luminance can be made uniform. However, when the segment S is turned off, the width of the strip electrode 41 is within 30% (in the region where the segment S is formed, the width of the strip electrode 41 opposite to the feed side (upper side in the figure) is less than the feed side (see FIG. It is preferable that the width of the strip electrode 41 on the lower side is within 1.3 times the width).

  In the above description, the organic EL panel 100 element is a bottom emission type, but may be a top emission type. Further, the organic EL panel 100 may be operated by duty drive. Further, the shape of the segment S is not limited to the hexagonal shape, and is arbitrary.

  Moreover, although the example in which the strip electrode 41 is formed to extend linearly has been described above, the strip electrode 41 may be formed in a curved shape or a zigzag shape and extend in a predetermined direction. In this case, the pitch P of the strip-shaped electrodes 41 may be considered as the distance between the centers of the adjacent strip-shaped electrodes 41 in a direction crossing the predetermined direction (for example, the orthogonal direction).

  Further, the use of the organic EL panel 100 is not limited, but is particularly suitable for use in which there is a need to visually recognize the background through the own device. As this type of application, a display on a dashboard of a vehicle, a display arranged so as to be superimposed on a light-transmitting door (such as an automatic door), and the like can be considered.

The organic EL panel 100 described above is an organic EL panel 100 that lights up and displays the segment S. The substrate 10 has translucency, and the first electrode 20 and the second electrode 40 provided on the substrate 10. And an organic layer 30 that is provided on the substrate 10 and is located between the first electrode 20 and the second electrode 40 and includes at least a light emitting layer.
The first electrode 20 has translucency and is formed in a shape corresponding to the segment S, and the second electrode 40 does not have translucency and has a first direction (for example, viewed from the normal direction of the substrate) A plurality of strip electrodes 41 extending in the Y direction and the direction L (FIG. 6), and the plurality of strip electrodes 41 are arranged at a predetermined pitch P in a second direction (for example, the X direction) intersecting the first direction. It is arranged.
The width of the segment S in the second direction (segment width D) is approximately n times the pitch P (n is a natural number of 2 or more), and is adjacent to the plurality of strip electrodes 41 when viewed from the substrate normal direction. A space between objects is a translucent region.
Since it did in this way, display quality is favorable as mentioned above.

  Further, there are a plurality of segments S, including a first segment S1 extending in the first direction and a second segment S2 extending in the second direction, and at least one of the first segment S1 and the second segment S2. The width in the direction 2 may be approximately n times the pitch P (n is a natural number of 2 or more).

  Further, the first direction coincides with the vertical direction as viewed from the viewer viewing the display image (example shown in FIG. 2B), or is inclined with respect to the vertical direction (shown in FIG. 6). Example).

  Further, the second direction may coincide with the left-right direction as viewed from the viewer viewing the display image (example shown in FIG. 2B or FIG. 6).

  When the organic EL panel 100 is so-called “vertical”, it is preferable to match the first direction with the left-right direction as viewed from the viewer viewing the display image.

  In the above description, in order to facilitate the understanding of the present invention, the description of known unimportant technical matters is appropriately omitted.

100 Organic EL Panel 10 Substrate 20 First Electrode 30 Organic Layer 40 Second Electrode 41 Strip Electrode W Width P Pitch 50 Sealing Plate 60 Variable Display Part S Segment S1 First Segment S2 Second Segment D Segment Width 70 Fixed Display Part 80 IC

Claims (5)

An organic EL panel that lights up and displays a segment,
A substrate having translucency;
A first electrode and a second electrode provided on the substrate;
An organic layer provided on the substrate and positioned between the first electrode and the second electrode and including at least a light-emitting layer,
The first electrode has translucency and is formed in a shape corresponding to the segment,
The second electrode is not translucent and includes a plurality of strip electrodes extending in a first direction when viewed from the normal direction of the substrate, and the plurality of strip electrodes intersects the first direction. Arranged in a second direction with a predetermined pitch,
The width of the segment in the second direction is approximately n times the pitch (n is a natural number of 2 or more),
As seen from the normal direction, a space between adjacent ones of the plurality of strip electrodes is a light-transmitting region.
An organic EL panel characterized by that. A plurality of the segments, including a first segment extending in the first direction and a second segment extending in the second direction;
The width in the second direction of at least one of the first segment and the second segment is approximately n times the pitch (n is a natural number of 2 or more).
The organic EL panel according to claim 1. The first direction coincides with the vertical direction as viewed from the viewer viewing the display image, or is inclined with respect to the vertical direction.
The organic EL panel according to claim 1 or 2. The second direction coincides with the left-right direction as viewed from a viewer viewing the display image.
The organic EL panel according to any one of claims 1 to 3, wherein The first direction coincides with the left-right direction as viewed from a viewer viewing the display image.
The organic EL panel according to claim 1 or 2.

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