Patent Application
20180151830
The present invention relates to a display device and an electronic device.
In recent years, an organic EL display device that is a self-emission device including an organic EL element has received attention as a flat panel display. A display device including a first electrode, an insulating film that covers the peripheral portion of the first electrode, an organic layer that covers the first electrode and the insulating film, and a second electrode that covers the organic layer is described in Japanese Patent Laid-Open No. 2012-216495. Japanese Patent Laid-Open No. 2012-216495 describes that the first electrode can have a structure in which a 15-nm thick aluminum film is stacked on a 20-nm thick titanium, tungsten, copper, tantalum, or molybdenum film.
In the display device described in Japanese Patent Laid-Open No. 2012-216495, the peripheral portion of the first electrode covered with the insulating film does not inject charges into the organic layer and therefore does not contribute to light emission. On the other hand, the peripheral portion of the first electrode of a certain pixel can reflect light generated by the organic layer at an upper position of the first electrode and make the light enter an adjacent pixel. This light is called stray light and can lower the resolution or cause color mixture in a color display device. In particular, if the upper face of the first electrode is made of a metal material having a high reflectance to increase the reflectance of the first electrode, as in the display device described in Japanese Patent Laid-Open No. 2012-216495, occurrence of such resolution lowering or color mixture can be more conspicuous.
The present invention provides a display device having a structure advantageous to suppress occurrence of resolution lowering and/or color mixture.
One of aspects of the present invention provides a display device comprising: an electrode structure including a first electrode arranged on a substrate, and a member arranged on the first electrode; an insulator configured to cover a peripheral portion of the electrode structure; an organic film configured to cover the first electrode and the insulator; and a second electrode configured to cover the organic film, wherein the member includes a first portion arranged in the peripheral portion of the electrode structure so as to cover a peripheral portion of an upper face of the first electrode, and a reflectance of the peripheral portion of the electrode structure is lower than a reflectance of a central portion that is a portion inside the peripheral portion of the electrode structure.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
The present invention will now be described with reference to the accompanying drawings by way of embodiments.
The substrate 10 may be an insulating substrate such as a glass substrate, may be a conductive substrate such as a metal substrate, or may be a semiconductor substrate such as a silicon substrate. Each of the plurality of driving circuits of the driving circuit layer 11 can include a transistor such as a TFT or MOSFET. If the substrate 10 is an insulating substrate such as a glass substrate, the transistor can be arranged on the substrate 10. If the substrate 10 is a semiconductor substrate, the active region of the transistor can be formed in the semiconductor substrate. The first planarizing layer 12 can be made of, for example, an inorganic material such as silicon oxide or silicon nitride because if moisture content is low. However, the first planarizing layer 12 may be made of an organic material.
The display device 100 can include an insulator 16 that covers the peripheral portion 31 of each of the plurality of electrode structures 30, an organic film 17 that covers the first electrode 14 of each of the plurality of electrode structures 30 and the insulator 16, and a second electrode 18 arranged to cover the organic film 17. In the first planarizing layer 12, a connection plug 13 that connects each driving circuit of the driving circuit layer 11 to a corresponding electrode structure 30 (first electrode 14) can be arranged. The insulator 16 can be arranged to separate the plurality of electrode structures 30 from each other. One pixel includes one electrode structure 30. The organic film 17 and the second electrode 18 can be shared by a plurality of pixels. The display device 100 can include, for example, a plurality of R pixels (red pixels), a plurality of G pixels (green pixels), and a plurality of B pixels (blue pixels).
The display device 100 can include a first protection layer 19 that covers the second electrode 18, a second planarizing layer 20 that covers the first protection layer 19, a color filter layer 21 arranged on the second planarizing layer 20, and a second protection layer 22 arranged on the color filter layer 21.
Each pixel has a size of, for example, about 1 to 5 μm. The interval between the adjacent electrode structures 30 can be, for example, 0.1 to 1 μm. For example, if the thickness of the organic film 17 is about 0.05 to 0.2 μm, it is necessary to prevent light generated by the emission layer 17c from mixing between adjacent pixels.
On the other hand, in the display device 100 according to the first embodiment, the member 15 is provided on the first electrode 14. The reflectance of the peripheral portion 31 of the electrode structure 30 is thus made lower than that of the central portion 32 of the electrode structure 30. Hence, as schematically shown in
The first electrode 14 can contain a high-reflectance material, for example, at least one of aluminum, silver, an aluminum alloy, and a silver alloy. The first electrode 14 may be formed by a single layer or may be formed by a plurality of layers. For example, a Ti layer or a Ti layer/TiN layer can be provided under an aluminum layer, thereby strengthening the orientation of the aluminum layer and improving the planarity of the aluminum layer. A layer that does not largely impede reflection performance, for example, a transparent layer such as an ITO layer or an IZO layer may be formed on the surface of the aluminum layer.
The member 15 in the electrode structure 30 can contain a material having a reflectance lower than that of the first electrode 14, for example, at least one of titanium (Ti) and titanium nitride (TiN). From another point of view, the member 15 in the electrode structure 30 can be made of a conductive material such as a metal or a metallic compound, which is a material having a reflectance lower than that of the first electrode 14.
In the member 15 of the electrode structure 30, the first portion 151 is thicker than the second portion 152 (the second portion 152 is thinner than the first portion 151). For example, the difference between a thickness t1 of the first portion 151 and a thickness t2 of the second portion 152 is 5 nm or more (t1>t2). Making the thickness t1 of the first portion 151 larger than the thickness t2 of the second portion 152 is advantageous in making the reflectance of the peripheral portion 31 of the electrode structure 30 lower than the reflectance of the central portion 32 of the electrode structure 30. The upper limit of the difference between the thickness of the first portion 151 and the thickness of the second portion 152 can be determined in accordance with the thickness of the organic film 17 or the like.
Letting the energy of visible light entering the electrode structure 30 be 100%, the intensity of the visible light reflected by the central portion 32 of the electrode structure 30 is preferably larger than the energy of the visible light reflected by the peripheral portion 31 of the electrode structure 30 by 5 points or more. The visible light is light whose wavelength ranges from 400 nm to 700 nm. In an example, the member 15 is made of titanium, and the difference between the thickness t1 of the first portion 151 and the thickness t2 of the second portion 152 is 5 nm or more (t1>t2).
The reflectance of the central portion 32 of the electrode structure 30 is preferably high. To raise the reflectance of the central portion 32, the thickness of the second portion 152 is preferably 8 nm or less.
The insulator 16 can have an opening OP at a position overlapping the first opening OP1 in a planar view. The opening OP1 exposes the central portion 32 of the electrode structure 30. The organic film 17 can include a portion arranged in the opening OP. In the orthogonal projection to the surface of the substrate 10, a shortest distance d1 between the opening OP and the connection plug 13 is preferably 0.1 μm (inclusive) to 0.5 μm (inclusive). Additionally, in the orthogonal projection to the surface of the substrate 10, a shortest distance d2 between the connection plug 13 and the outer edge of the first electrode 14 is preferably 0.1 μm (inclusive) to 0.5 μm (inclusive). The first portion 151 of the member 15 includes a first opening OP1. The organic film 17 can include a portion arranged in the first opening OP1 so as to be in contact with a side face SS of the first portion 151 facing the first opening OP1. The organic film 17 covers the side face SS of the first portion 151 and the upper face of the second portion 152 so as to be in contact with the side face SS of the first portion 151 and the upper face of the second portion 152. The organic film 17 preferably contacts the entire region of the side face SS of the first portion 151 and the entire region of the upper face of the second portion 152. This arrangement is advantageous in reducing variations in the thickness and area of the organic film 17 between the pixels and equalizing the emission characteristics.
The member 15 that forms the electrode structure 30 may be made of a material (inorganic material or organic material) other than the above-described conductive material such as a metal or a metallic compound. The material can be selected in consideration of the charge injection efficiency to the organic film 17.
The insulator 16 may be made of, for example, an inorganic material such as silicon oxynitride, silicon oxide, or silicon nitride, an organic material such as acryl or polyimide, or another material.
The second electrode 18 is a transparent electrode and can be formed to cover the organic film 17 (electron injection layer 17e). The second electrode 18 can be made of a metal or a metal alloy. The second electrode 18 can be made of, for example, an alloy of magnesium and silver or an alloy of aluminum, sodium, and calcium. Alternatively, the second electrode 18 can be made of ITO or IZO.
The organic film 17 can include a portion arranged in the first opening OP1 so as to be in contact with side face SS1 of the first portion 151 of the member 15 of the electrode structure 30 facing the first opening OP1.
At the boundary between the first portion 151 and the insulator 16, the side face SS of the opening OP of the insulator 16 and the side face SS1 of the first opening OP1 of the first portion 151 can form a continuous surface. From another point of view, the maximum size of the first opening OP1 of the first portion 151 in a direction parallel to the surface of the substrate 10 may be less than or equal to the maximum size of the opening OP of the insulator 16 in the direction.
A method of manufacturing the display device 100 will be described with reference to
A description will be made next with reference to
A description will be made next with reference to
A description will be made next with reference to
After that, the central portion of each member 15b is etched via the opening OP to form an opening, thereby forming the member 15. This etching may be done under an etching condition in which the etch selectivity of the member 15b to the insulator 16 (third material film 16a) is 5 or more. After the member 15b is exposed, the etch selectivity may be adjusted by changing the RF power of the etching apparatus.
In addition, the member 15b may partially be removed by etching next to the etching for forming the opening OP in the third material film 16a. When the step of forming the opening OP of the insulator 16 and the step of forming the first opening OP1 of the member 15 are performed as one etching step, the efficiency of the manufacturing step can be increased.
The member 15 includes the second portion 152 having a surface etched using the third etching mask PR3, and the first portion 151 arranged outside the second portion 152 and having a thickness larger than that of the second portion 152. The first portion 151 includes the first opening OP1.
In an example, if the thickness of the first portion 151 is 7 nm, and the thickness of the second portion 152 is 5 nm, the reflectance of the first portion 151 in a case of incidence of light with a wavelength of 450 nm is higher than the reflectance of the second portion 152 by about 5 percent points. Note that in this example, the reflectance of the first electrode 14 in a case of absence of the member 15 is 90%.
A description will be made below with reference to
Next, the first protection layer 19 is formed on the second electrode 18 by a film formation method such as CVD or sputtering. The first protection layer 19 can be made of, for example, a low transparency material such as silicon nitride. The temperature when forming the first protection layer 19 is preferably 200° C. or less and more preferably 120° C. or less. Next, the second planarizing layer 20 is formed on the first protection layer 19 by a film formation method such as spin coating. The second planarizing layer 20 can be made of, for example, an organic material.
Next, the filter layer 21 including color filters of a plurality of colors is formed on the second planarizing layer 20. The color filter of each color can be formed by coating the second planarizing layer 20 with a filter material using spin coating or the like, patterning the coat by photolithography, and calcining it. Next, the second protection layer 22 is formed on the color filter layer 21 by a film formation method such as CVD or spin coating.
A display device 100 according to the second embodiment of the present invention will be described with reference to
In an example, the second portion 152 arranged at the central portion 32 can have a thickness of 5 to 10 nm, and the first portion 151a arranged in the peripheral portion 31 can have a thickness larger than that of the second portion 152 by 0.1 nm or more. The third portion 151b can have a thickness of 1 nm or more.
A display device 100 according to the third embodiment of the present invention will be described with reference to
A display device 100 according to the fourth embodiment of the present invention will be described with reference to
Additionally, in the fourth embodiment, the thickness of a first electrode 14 at the central portion 32 is smaller than the thickness of the first electrode 14 in a peripheral portion 31. In the fourth embodiment as well, the reflectance of the peripheral portion 31 of the electrode structure 30 is lower than the reflectance of the central portion 32 (first electrode 14) that is a portion inside the peripheral portion 31 of the electrode structure 30.
A display device 100 according to the fifth embodiment of the present invention will be described with reference to
The display device 100 as described above can be incorporated in various electronic devices. Examples of such an electronic device are a camera, a computer, a portable terminal, and an onboard display device. The electronic device can include, for example, the display device 100 and a driving circuit that drives the display device 100.
An embodiment in which the above-described display device is applied to a digital camera will be described with reference to
A mechanical shutter 903 is arranged between the lens unit 901 and the imaging element 905, and its driving is controlled by the control unit 909 via a shutter driving device 904. The imaging element 905 is arranged to receive light that enters from the lens, and converts an optical image formed by the lens unit 901 into an image signal by a plurality of pixels.
A signal processing unit 906 receives the image signal output from the imaging element 905, and performs A/D conversion, demosaicing processing, white balance adjustment processing, encoding processing, and the like for the image signal. The signal processing unit 906 also executes focus detection processing of detecting a defocus amount and direction by a phase difference detection method based on a signal obtained from the image signal output from the imaging element 905.
A timing generation unit 907 outputs various kinds of timing signals to the imaging element 905 and the signal processing unit 906. The control unit 909 includes, for example, memories (ROM and RAM) and a microprocessor (CPU), and implements various kinds of functions of the digital camera by loading a program stored in the ROM into the RAM and causing the CPU to execute it to control the units. The functions implemented by the control unit 909 include automatic focus detection (AF) and automatic exposure control (AE). The control unit 909 receives a signal based on the signal output from the imaging element 905, and inputs a signal for an electronic viewfinder to a display unit 912.
A memory unit 908 is used by the control unit 909 or the signal processing unit 906 to temporarily store image data or as a work area. A medium I/F unit 910 is an interface configured to perform read/write access to a recording medium 911 that is, for example, a detachable memory card. The display unit 912 is used to display a shot image or various kinds of information of the digital camera. An operation unit 913 includes user interfaces such as a power switch, a release button, and a menu button configured to allow a user to do an instruction or setting for the digital camera.
When the display device described in any one of the above-described embodiments is used in the display unit 912, an image to be shot can be displayed more accurately. A driving unit that drives the display device includes, for example, the control unit 909.
The operation of the digital camera at the time of image shooting will be described. When the power is turned on, a shooting standby state is set. The control unit 909 starts moving image shooting processing of causing the display unit 912 to operate as an electronic viewfinder and display processing. If a shooting preparation instruction (for example, half stroke of the release button of the operation unit 913) is input in the shooting standby state, the control unit 909 starts focus detection processing. For example, the control unit 909 can perform focus detection processing by a phase difference detection method. More specifically, the control unit 909 obtains an image shift amount based on the phase difference between signal waveforms obtained by combining signals of the same type of A image signals and B image signals obtained from a plurality of pixels, and obtains the defocus amount and direction.
The control unit 909 obtains the moving amount and the moving direction of the focus lens of the lens unit 901 based on the obtained defocus amount and direction, drives the focus lens via the lens driving device 902, and adjusts the focus of the imaging optical system. After the driving, focus detection based on a contrast evaluation value may be further performed as needed to finely adjust the focus lens position.
After that, if a shooting start instruction (for example, full stroke of the release button) is input, the control unit 909 executes a shooting operation for recording, processes obtained image data by the signal processing unit 906, and stores it in the memory unit 908. The control unit 909 records the image data stored in the memory unit 908 in the recording medium 911 via the medium I/F unit 910. Note that the image data may be output from an external I/F unit (not shown) to an external device such as a computer.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Applications No. 2016-233498, filed Nov. 30, 2016 and No. 2017-208514, filed Oct. 27, 2017, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-233498 | Nov 2016 | JP | national |
| 2017-208514 | Oct 2017 | JP | national |
