JP2005222915A - Color light emitting display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem where, because EL elements more are rapidly degraded when the density of supplied current is increased, the degree of degradation of colors increasingly differs over time when densities of the current to be supplied to the EL elements are changed for different color components to destroy brightness balance among colors, i.e. white balance as the usage time of the display device is increased. <P>SOLUTION: Areas of emissive regions corresponding to different color components are changed based on an emission luminance of an emissive element such as an EL element which is made of the same material and which has the same emission spectrum, efficiencies (transmission efficiency or color conversion efficiency) of color modifying elements such as color filters or color changing films, and required luminance of each of different color components necessary for obtaining white color in full-color display. This structure facilitates setting of the density of current supplied to an EL element corresponding to each emissive region to substantially the same value among the different emissive regions, which allows for realization of uniform rate of degradation of luminance, that is, lifetime in each emissive region. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a self-luminous element such as electroluminescence (EL), a color display device using a color conversion element such as a color filter for extracting light having an arbitrary spectrum, and the like.

  In recent years, an EL display device using an EL element has attracted attention as a display device that replaces a CRT or an LCD. As a method for colorizing this EL display device, in addition to a separate coating method using a light emitting material that emits R, G, and B primary colors, a monochromatic light emitting material such as a color filter or a color conversion film can be used. A method using a color conversion element that transmits or emits a color different from a color has been proposed.

FIG. 8A is a plan view showing an outline of such a color conversion type EL display device. Pixels each including an EL element are arranged in a matrix in each region surrounded by the gate signal line 51, the drain signal line 52, and the drive power supply line 53. Each pixel is assigned a color component, and light emitting areas E _R , E _G , E _B realized by EL elements are formed in each pixel area. The area of the light emitting regions E _R, E _G, E _B represents the respective color light-emitting area of actually visible. Each light emitting region is formed to have the same width (W) and height (H) so that this light emitting area is the same in any light emitting region of any color component.

FIG. 8B is a schematic view of the CC cross section of FIG. 8A. A color conversion element 89 that emits red (R), green (G), and blue (B) light is formed on the substrate 30, and a common emission color is provided at a corresponding position above the color conversion element 89. EL elements 80 are formed. By emitting the light from the EL element 80 to the outside through the color conversion element 89, a full color display is obtained while using the EL elements common to the respective pixels (same emission color).
International Publication No. 96/25020 Pamphlet (Figs. 4-6, 9-15)

  A color filter, which is a type of color conversion element, is characterized in that it transmits only light in a certain wavelength band of incident light to obtain a specific color component, and the transmission wavelength of each color filter of R, G, B Bandwidth and transmittance are different. That is, the transmission (absorption) spectrum is different for each color filter. Therefore, in order to make the light transmitted through the color filter and visually recognized from the outside have a desired luminance for each color component, the EL element for each color component according to the transmission (absorption) spectrum of the color filter and the emission spectrum of the EL element. The current density given to must be changed.

  In addition to the color filter, the color conversion film used as a color conversion element has a function of converting the original light into light of a certain wavelength band to obtain light of a specific color component, and more specifically, a phosphor. A material or the like is used, which is a film that absorbs incident light, emits light having a wavelength different from that of the incident light, and emits the light. Since such a color conversion film uses a different material for each color of the emitted light, the wavelength band of the emitted light and the conversion efficiency are different, and of course, the conversion efficiency is different depending on the emission spectrum of the incident light. Therefore, in order for the light emitted from the color conversion film to be visually recognized externally to have a desired luminance for each color component, depending on the conversion efficiency of the color conversion film for each color component and the emission spectrum of the EL element. The current density given to the EL element must be changed for each color component.

  However, since the EL element tends to deteriorate as the current density supplied increases, if the current density applied to the EL element is changed for each color component, the degree of deterioration of each color changes as the light emission time elapses. End up. That is, as the usage time of the display device increases, there is a problem that the luminance balance of each color, that is, the white balance is lost, and the lifetime of the display device is shortened.

In the present invention, the color light-emitting display device has a plurality of light-emitting regions corresponding to a plurality of color components, and each of the plurality of light-emitting regions has a light-emitting element layer between two electrodes and has the same color. A plurality of light emitting elements that are provided on the display viewing side of the device from the light emitting elements corresponding to at least some of the light emitting elements, and at least part of the emission spectrum of incident light is provided. A plurality of color conversion elements that emit light of different emission spectra, and
The emitted light from the plurality of light emitting elements is visually recognized through the corresponding color conversion element in the light emitting region associated with the plurality of color conversion elements,
The areas of the plurality of light-emitting regions are the ratio of the conversion efficiency according to the luminance of the emitted light with respect to the luminance of the incident light in the color conversion element, and the ratio of the different color components among the plurality of color components, and white It depends on the required luminance of each color component necessary for display or the required luminance of each color component necessary to realize a predetermined color expressed by additive color.

In another aspect of the invention,
The color light emitting display device has a plurality of light emitting areas corresponding to a plurality of color components,
The plurality of light emitting regions each have a light emitting element layer between two electrodes, the plurality of light emitting elements emitting light of the same color, and the plurality of light emitting elements closer to the display viewing side than the light emitting element of the apparatus A plurality of color conversion elements that are provided corresponding to at least some of the light-emitting elements and emit light having an emission spectrum that is at least partially different from the emission spectrum of incident light,
The emitted light from the plurality of light emitting elements is visually recognized through a corresponding color conversion element and at least one layer that absorbs at least part of incident light in a light emitting region in which the plurality of color conversion elements are associated. And
The area of the plurality of light emitting regions is the conversion efficiency according to the luminance of the emitted light with respect to the luminance of the incident light in the color conversion element, and the transmission efficiency of the one or more layers that absorb at least a part of the incident light. This corresponds to the ratio of different color components among the plurality of color components and the required luminance of each color component necessary for white display.

  In another aspect of the present invention, in the color display device, the area of each of the plurality of light emitting regions is light emitted through the color conversion element and at least one layer that absorbs at least part of incident light. The required luminance of each color component necessary for the white display with respect to the luminance of is proportional to the ratio of each color component.

In another aspect of the present invention, in the color display device,
The color conversion element filters and emits light of a specific wavelength band from the incident light, or converts the incident light to light of a different wavelength and emits it.

  In another aspect of the invention, the conversion efficiency of the color conversion element corresponds to the transmission efficiency of a filter or the color conversion efficiency of a color conversion material.

  In another aspect of the present invention, in the color display device, when power is supplied to the light emitting elements respectively provided in the plurality of light emitting regions at the same current density to emit light, a predetermined value is set on the viewing side. Color display such as white is achieved.

  In another aspect of the present invention, in the color display device, the at least one layer that absorbs at least part of incident light includes an optical functional layer. Furthermore, an insulating layer formed between the light emitting element and the display viewing side of the device may be included.

In another aspect of the invention,
In a color display device having a first light emitting region and a second light emitting region associated with different color components,
A plurality of light emitting elements each having a light emitting element layer between two electrodes and emitting light of the same color;
Provided on the display viewing side from the light emitting element of the apparatus corresponding to at least a part of the light emitting elements of the plurality of light emitting elements, and at least a part of the emission spectrum of the incident light is an emission spectrum different from each other in color. A first color conversion element and a second color conversion element that emit light;
In the first light emitting region, light emitted from the light emitting element is visually recognized through the first color conversion element,
In the second light emitting region, the emitted light from the light emitting element is visually recognized through the second color conversion element,
The conversion efficiency according to the ratio of the emitted light to the incident light of the first color conversion element is higher than the conversion efficiency according to the ratio of the emitted light to the incident light of the second color conversion element, and the area of the first light emitting region. Is smaller than the area of the second light emitting region.

In another aspect of the present invention, in the color display device,
The ratio of the area of the first light emitting region to the area of the second light emitting region is:
The luminance required for white display of the color component associated with the first light emitting region with respect to the emission light luminance from the first color conversion element;
This corresponds to the ratio of the luminance required for white display of the color component associated with the second light emitting region to the luminance of the emitted light from the second color conversion element.

  According to the present invention, a light emitting element that emits light of the same color is used, and even if each color component is associated with this light emitting element, the same current density is applied to any light emitting element that is responsible for light emission of any color component. For example, white and other colors expressed by additive colors can be displayed, and the degree of deterioration (e.g., luminance half time) of the light emitting material of the light emitting element such as an EL material such as an EL element can be kept equal. It is possible to realize a color display device that is easy to do.

  Furthermore, if the aging process is performed to make the deterioration rate of light emission in some wavelength bands constant, even in an EL element having different deterioration rates in different wavelength bands, the current density is substantially reduced when an arbitrary color is displayed on the entire surface. Can be kept equal to. Therefore, it is possible to supply a high-quality and long-life EL display device in which the luminance is balanced even when the cumulative usage time is long.

FIG. 1 is a diagram conceptually showing light emitting areas of a plurality of pixels of the EL display device according to the first embodiment of the present invention. In FIG. 1, so-called stripes in which the light emitting regions of the pixels associated with the respective color components of the three primary colors (R, G, B) are periodically arranged in the row direction and the same color components are arranged in the same column. The case of an array is shown. In the EL display device of the present embodiment, each of the pixels is associated with one of R, G, and B, and full color display is performed by combining light from the R, G, and B pixels. Further, as will be described later, EL elements that emit light of the same color (for example, white light emission) are formed in the light emitting areas of the respective pixels, and white light from each EL element corresponds to each other. By the color conversion element (29) such as the provided color filter or color conversion film, the light is converted into R, G, and B having different emission spectra (including wavelength conversion and filtering) and emitted to the outside. Emitting region _E R which emits each _color, E G, _{E B} has a common height (vertical length) H and intrinsic width (horizontal _length) W _R, W G, the _{W B,} respectively . A method for setting the height and width of these light emitting areas will be described later.

A plurality of gate signal lines 51 are horizontally arranged around the plurality of light emitting regions E _R , E _G , and E _B arranged in this manner, and a plurality of drain (data) signal lines 52 and a plurality of drive power supply lines 53 are arranged in the horizontal direction. Are formed in the vertical direction. Distance D _H from the gate signal line 51 to the light emitting _regions, the distance D _W from the drive power supply line 53 to each light emitting region, the width W _R of the light emitting _regions, W _G, regardless of W _B, a constant value It is set to be. By setting in this way, when the gate signal line 51 and the drive power supply line 53 are arranged, the spaces formed on the upper side and the left side of the light emitting region E have a common shape, and transistors described later have the same shape. This is because they can be arranged at the same position. According to the above aspect, the light emitting region E corresponding to each color component can be set to a desired area, and the space can be used more effectively.

Although the configuration described above is considered to be the most preferable aspect of the present invention, the present invention is not limited to this aspect. For example, the arrangement method of the light emitting regions is not limited to the stripe arrangement, but may be a so-called delta arrangement. In this delta arrangement, light emitting areas corresponding to different color components are periodically arranged in the row direction and also in the column direction. In particular, the arrangement of the light emitting areas in the column direction is In this arrangement, the three light emitting areas adjacent to each other in both the row direction and the column direction are light emitting areas corresponding to different color components. Further, at least one of the height and the width of the light emitting region may be a value unique to each color component, and _DH and _DW may not be constant values. However, when considering the ease of arrangement of the light emitting region, it is preferable to share one of the height and width of the light emitting region. When further considering the effective use of the space, the height of the light emitting region is preferred. Is more preferable.

  Hereinafter, a method for setting the light emitting region of such an EL display device will be described in the case of using a color filter which is one type of color conversion element having a color (wavelength) conversion function. As the EL element has a higher current density when a current is passed, the deterioration is accelerated, and this deterioration causes a change in luminance (in many cases, a reduction in luminance). It is very important for maintaining the brightness balance (white balance) for a long time as the whole device. Therefore, by using the same EL element material for all the light emitting regions by aligning the current density of the current flowing through the EL element in each light emitting region, the light emitting region corresponding to each color component can be obtained by combining the initial luminance L0 of each color component. The degree of deterioration of the EL material can be made more uniform, more specifically, the luminance half-life. That is, the overall luminance balance can be maintained.

(1) Determine the organic EL element to be used and the color filter for each color. Since the organic EL element has a specific emission spectrum, and the color filter has a specific transmission (absorption) spectrum, from these two products,
The chromaticity of the light of each color component after passing through the color filter (emission spectrum of the emitted light),
The luminance (incident light luminance and outgoing light luminance) before and after transmission of each color filter when an equal current density is applied to the EL element corresponding to each light emitting region and / or the ratio of the incident light luminance and the outgoing light luminance can be known. .

The luminance of the EL element in each light emitting region before transmitting the color filter is set to L _R , L _G , and L _B , respectively, and the transmission efficiency of each color filter (here, the ratio of the emitted light (transmitted light) luminance to the incident light luminance (transmitted) equal the rate)) respectively _{TE R, TE G,} when the TE _B, consisting each luminance after color filters transmitting _{L R · TE R, L G} · TE G, and L _B · TE B. Here, as an example, the luminance ratio of each color component after passing through the color filter
L _R · TE _R : L _G · TE _G : L _B · TE _B = 3: 8: 2
And

(2) From the chromaticity determined in (1), the luminance required on the viewing side of each color to achieve white having the chromaticity necessary for display on the viewing side is automatically determined. As an example, the required luminance ratio of light of each color of R, G, B on the viewing side
a _R : a _G : a _B = 1: 2: 1
And

(3) From the ratio of (1) and (2), the luminance of the organic EL element before the color filter transmission necessary to achieve the required luminance on the viewing side of each color (in the path between the element and the color filter) If the optical loss is almost zero, it is found that the luminance is equal to the incident light luminance to the color filter). The luminance ratio of the organic EL elements in the light emitting region corresponding to each color component before the color filter transmission required in the case of the previous example is
a _R / (L _R · TE _R ): a _G / (L _G · TE _G ): a _B / (L _B · TE _B ) = 1/3: 2/8: 1/2 = 4: 3: 6
It becomes.

(4) The light emission area of each color component is set according to the luminance ratio obtained in (3). In the case of the present embodiment, the emission areas (S _R , S _G , S _B ) of the respective color components are set so as to be proportional to this ratio. That is, it sets so that the following formula | equation (i) may be satisfy | filled.
S _R : S _G : S _B = a _R / (L _R · TE _R ): a _G / (L _G · TE _G ): a _B / (L _B · TE _B ) (i)
Applying this equation (i) to the above example,
S _R : S _G : S _B = 1/3: 2/8: 1/2 = 4: 3: 6
Therefore, the areas of R, G, and B may be set so as to satisfy this ratio. The width W _R of the light emitting regions corresponding to the respective color components in accordance with the ratio of the _luminance, W _G, W _B is preferably set to be proportional to the ratio of sauce obtained in the above (3). With this setting, the heights H _R , H _G , and H _B of the light emitting regions can be made equal in all the light emitting regions, so that the design is easy and the space can be effectively used.

  Note that an antireflection film and / or a polarizing film may be used on the viewing side of the organic EL element in order to prevent the contrast from being lowered by reflected light of light incident from the outside of the display device. In addition, an optical functional layer such as a UV cut film may be used on the viewing side of the organic EL element so that the EL element is not damaged by UV light from the outside. Each of these optical functional layers such as an antireflection film / polarizing film and UV cut film has a unique transmission (absorption) spectrum, and absorbs at least a part of incident light thereto. Therefore, when these optical functional layers are used, it is necessary to set the emission area in consideration of the transmission efficiency (transmission (absorption) spectrum or light loss) in addition to the transmission (absorption) spectrum of the color filter. is there. In this case, the luminance change (luminance ratio) in the above (1) is not the ratio of the emitted light to the incident light in the color filter, but the entire transmission of the color filter, antireflection film, polarizing film and / or UV cut film. The change in luminance before and after (luminance ratio) may be used. In addition, other films such as a buffer layer, a TFT gate insulating layer, an interlayer insulating layer, a planarizing layer, etc., which will be described later, are formed on the viewing side of the EL element between the substrate and the like. In addition, it is more preferable to further consider the transmission efficiency (transmission absorption spectrum) of these membranes. More specifically, the incident light luminance × conversion efficiency (transmission efficiency in this case) of a color conversion element such as a color filter × transmission efficiency value (integrated value) of the optical functional layer is read as “L · TE”. Good.

In an EL display device having color conversion elements such as a color filter and a color conversion film, an organic EL element having a common structure is formed on the entire surface, that is, only a common (made of the same material) organic layer is stacked on the entire surface. Therefore, as long as an equal current density is applied to the EL elements in each light emitting region, the deterioration rate of the light emission luminance can be made uniform in all the light emitting regions. However, depending on the layer structure of the light emitting layer, the light emitting material used, and the like, the luminance half-life may be different because different deterioration rates are exhibited in different light emission bands. For example, in the case where different multi-layered light emitting layers that emit light of complementary colors are used to represent white color by adding light from each light emitting layer, the luminance half-life of each light emitting layer is different. And the case where the emission spectrum of a single light emitting material changes with the lapse of light emission time. In such a case, if the luminance half-life in each wavelength band is further added in the determination of the emission area, the luminance half-life can be made more uniform in all emission regions. That is, when the luminance half-lives of the emission luminance in each wavelength band corresponding to R, G, and B are T _R , T _G , and T _B , they are expressed as in equation (ii).
S _R : S _G : S _B
= A _R / (L _R · TE _R · T _R ): a _G / (L _G · TE _G · T _G ): a _B / (L _B · TE _B · T _B ) (ii)
In addition, the deterioration rate (luminance change) of light emission in the entire light emitting layer or in an arbitrary wavelength band varies greatly at the initial stage of light emission, and the deterioration rate may become constant after a predetermined period. In such a case, the light emitting area must be determined in consideration of the change in deterioration rate with time in the initial stage of light emission. It is also possible to perform an aging process before shipping the display device (or display panel) to the factory so that it is not necessary to take into consideration the large size. In this case, by using the luminance half-life measured or simulated after the aging process as the T (T _R , T _G , T _B ), the luminance half-life can be more accurately aligned. Specifically, for example, when the degradation rate changes uniformly in all wavelength bands, or when the degradation rate changes only in an arbitrary wavelength band, it is preferable to perform aging processing until the degradation rate does not change. In addition, when different deterioration rates change with time in different wavelength bands, it is preferable to perform an aging process until the deterioration rate becomes constant in at least one wavelength band. However, since the aging process and the luminance half-life are in a trade-off relationship, if the main focus is to align the luminance half-life strictly, it is better to perform the aging process until the degradation rate is constant in all wavelength bands. Preferably, when focusing on increasing the luminance half-life, it is more preferable to perform aging until the deterioration rate becomes constant in one wavelength band.

  By the above method, the light emitting region for realizing a desired white display (full color display) can be set for each color component while keeping the current density applied to each organic EL element having the same structure constant. Therefore, when all the organic EL elements are driven at the same current density for the same time, the brightness half timing can be reached almost simultaneously. For design reasons, there may be a case where the light emitting area cannot be secured according to the luminance ratio required for the EL elements in the light emitting region corresponding to each color component. In that case, even if the luminance half-life of the element is different from that of the EL element associated with the other color component, the current density to be applied is changed from that of the EL element of the other color component within a range that does not hinder the display device. The required brightness may be ensured (large or small). In the present embodiment, it is considered that the luminance half-life is substantially the same as long as the display device has no problem.

  As a color conversion element, instead of the color filter, a fluorescent material or the like is used as an example, and when a color conversion film that obtains light of a specific color component by converting incident light into light of a certain wavelength band is used as described above. By replacing the transmission efficiency of the color filter with the conversion efficiency, the luminance required for color display while equalizing the current density to the organic EL element in the light emitting region of each color component by the same method as (1) to (4) above. Can be achieved.

  Furthermore, when a color conversion film and a color filter are combined as a color conversion element, it is only necessary to consider the transmission efficiency (transmission (absorption) spectrum) of the color filter in addition to the conversion efficiency of the color conversion film. The luminance ratio (emitted light luminance / incident light luminance) may be a ratio of luminance before and after transmission through the color conversion film and the color filter.

  When a color conversion film is used and an antireflection film and / or a polarizing film is used, the conversion efficiency of the color conversion film and the transmission efficiency (transmission (absorption) spectrum) of the antireflection film and / or the polarizing film are determined. Therefore, the luminance ratio of (1) may be the luminance ratio before and after transmission through the color conversion film, the antireflection film and / or the polarizing film.

  In addition, in the case of either the color filter or the color conversion film, if the required color component on the viewing side matches the emission color of the organic EL element among the plurality of emission regions, the emission region has a color. The light emitted from the EL element can be emitted as it is without providing the conversion element. In such a case, the luminance change rate (efficiency: TE) of (1) is only 1 for the color component of the original light, and the others are as described above. In addition, when the luminance half-life is added to the setting of the light-emitting area, the deterioration rate and luminance half-life of the light-emitting layer in the wavelength band corresponding to the color component of each pixel are not taken into account as in the case of the color filter method. The degradation rate and luminance half-life of the light in the wavelength band used for conversion by each color conversion film among the emitted light of the EL element may be considered as described above.

Figure 2 is a plan view of the peripheral light-emitting region _{E B} in FIG. 1, FIG. 3A, 4B is A-A, B-B sectional view of FIG. The structure near the light emitting region of the EL display device according to the embodiment of the present application will be described with reference to these drawings.

First, two first TFT10 are connected in series to the drain signal line 52, a part of the storage capacitor electrode line 54 and the storage capacitor electrode 55 is disposed between the light-emitting region E _B and the gate electrode 51 ing. Further, the gates 14 of the two TFTs 10 are respectively connected to the gate signal line 51 (however, in this example, the gate 14 and the gate signal line 51 are integrated). Further, the drain 12 d of the TFT 10 disposed on the drain signal line 52 side is connected to the drain signal line 52. The source 12s of the drain signal line 52 is not directly connected to TFT10 is, the storage capacitor electrode 55 constituting the storage capacitor C _S with a storage capacitor electrode line 54 are electrically connected (however, in this example The source 12s of the TFT 10 and the storage capacitor electrode 55 are formed integrally using the same semiconductor layer). Further, the source 12 s of the TFT 10 is connected to the gates 24 of the two second TFTs 20, and the second TFT 20 is connected in parallel to each other between the drive power line 53 and the organic EL element 60. Yes. Specifically, the sources 22 s of the two TFTs 20 are connected to the drive power supply line 53, respectively, and the drains 22 d of the two TFTs 20 are connected to the drain electrode 26, and will be described later via the drain electrode 26. It is connected to the electrode 61 of the organic EL element 60. Note that a light emitting element layer 65 and an electrode 66 are stacked on the electrode 61 of the organic EL element 60.

The storage capacitor electrode line 54 is formed so as to face the active layer (semiconductor layer) 12 serving also as the storage capacitor electrode 55 connected to the source 12 s of the TFT 10 through the gate insulating film 13. As a result, charges are accumulated between the storage capacitor electrode line 54 and the storage capacitor electrode 55 to form a capacitor. This volume is a storage capacitor _{C S} which holds the voltage applied to the gate electrode 24 of the second TFT 20.

2, the light-emitting region E _B is shown with a rectangle, in fact in order to ensure the light emitting area even slightly, or may not be rectangular for convenience of design. In the present embodiment, what is not strictly a rectangle may be in a range that can be roughly regarded as a rectangle, and such a thing will be described as a rectangle. Further, in the above drawings, the light emitting region EB corresponding to _B and the peripheral structure thereof have been described, but the light emitting regions EG and ER corresponding to _G and _R and the peripheral structure thereof are also substantially common.

Next, the structure of the holding capacitor C _S to be connected to the 1 TFT 10 and its source for switching. Here, the first TFT 10 employs a so-called top gate type TFT in which the gate 14 is located above the active layer 12. An insulating film (buffer film) 11 made of, for example, SiN or SiO ₂ is stacked on the substrate 30. On top of that, an active layer 12 made of a polycrystalline silicon (hereinafter abbreviated as p-Si) film is formed, and a drain 12d, a source 12s, and a channel 12c positioned therebetween are provided. Further, the source 12s is formed integrally with the storage capacitor electrode 55 made of the same p-Si and is electrically connected (the source 12s and the storage capacitor electrode 55 are not necessarily formed integrally). But at least they must be electrically connected). Further, a gate insulating film 13 made of SiO ₂ and SiN is laminated so as to cover the active layer 12 and the storage capacitor electrode 55. A gate electrode 14 and a storage capacitor electrode line 54 made of a refractory metal such as chromium (Cr) or molybdenum (Mo) are formed thereon. The gate electrode 14 is provided so as to straddle the channel 12c, the first TFT 10 is formed in this region, and the storage capacitor electrode line 54 is provided to face the storage capacitor electrode 55. A storage capacitor _CS is formed in the region.

Further, an interlayer insulating film 15 made of a SiO ₂ film, a SiN film or the like is formed on the entire surface covering the gate electrode 14 and the gate insulating film 13. A drain electrode 16 made of a metal such as Al is provided through a contact hole formed at a position corresponding to the drain 12d of the interlayer insulating film 15, and further, a planarizing film 17 made of an organic resin or the like for flattening the surface over the entire surface. Is formed.

Next, the structure of the second TFT 20 for driving the organic EL element and the organic EL element 60 laminated thereon will be described. The second TFT 20 is also composed of a top gate type TFT like the first TFT 10, and the layers and films common to the first TFT 10 are formed at the same time. As can be seen from a comparison between FIGS. 3A and 4B, the same reference numerals are used. An insulating film 11 made of, for example, SiN or SiO ₂ is stacked on the substrate 30. On top of that, an active layer 22 made of a p-Si film is formed as in the first TFT 10. The active layer 22 is provided with a drain 22d, a source 22s, and a channel 22c positioned therebetween. Further, a gate insulating film 13 made of SiO ₂ and SiN is laminated so as to cover the active layer 22. A gate electrode 24 made of a refractory metal such as Cr or Mo is formed on the channel 22c. Thereby, the second TFT 20 is configured. Note that the first TFT 10 and the second TFT 20 may have the same conductivity or different conductivity depending on the configuration of the TFT provided in each pixel, that is, the circuit configuration in each pixel. However, the active layers 12 and 22 for any TFT can be formed at the same time except that the impurities doped in the p-Si film are different. That is, for example, it can be obtained by first forming an a-Si film or the like and then polycrystallizing it by laser annealing or the like. Note that a layer formed and patterned simultaneously with the gate electrode 14 of the first TFT 10 can also be used for the gate electrode 24 of the second TFT 20.

Further, an interlayer insulating film 15 made of a SiO ₂ film, a SiN film or the like is formed on the entire surface of the gate electrode 24 and the gate insulating film 13. A drain electrode 26 made of metal and a drive power supply line 53 connected to a drive power supply are disposed through contact holes formed at positions corresponding to the source 22s and the drain 22d of the interlayer insulating film 15. Furthermore, a color conversion element 29 composed of a color filter or a color conversion film for extracting light of a specific wavelength band from the light emission from the organic EL element 60 is disposed at a predetermined position on the interlayer insulating film 15, A flattening film 17 for flattening the surface is laminated so as to cover it. An electrode 61 made of ITO (Indium Tin Oxide) connected to the drain electrode 26 is formed on the planarizing film 17 through a contact hole formed through the planarizing film 17. Next, on the electrode 61, as an example, a light emitting element layer 65 having a three-layer structure of a hole transport layer 62, a light emitting layer 63, and an electron transport layer 64 is laminated. An electrode 66 made of an aluminum alloy or the like is formed so as to cover it. The light-emitting element layer 65 is not limited to the illustrated three-layer structure, and may have a single-layer, two-layer, four-layer, or more multilayer structure depending on the organic material used. Here, in the example of FIG. 3B, a hole transport layer 62 which is the lowermost layer of the light emitting element layer 65 and a second planarizing film 67 made of an insulating resin are laminated in a partial region between the electrodes 61. Is formed. When the lowermost layer of the light emitting element layer 65 is, for example, a hole injection layer, the second planarization film 67 is formed between the hole injection layer and the electrode 61. Further, an opening is formed on the electrode 61 in the second planarizing film 67, and the area where the surface of the electrode 61 is exposed to directly contact the light emitting element layer 65 is limited. That is, the light emitting region E is defined by the opening portion of the second planarization film 67.

  Here, the color conversion element 29 is preferably as close to the emission end (here, the substrate 30 side) as possible from the viewpoint of reducing parallax, and is disposed on, for example, the interlayer insulating film 15 as shown in FIG. 3B. Is preferable from the viewpoint of parallax and manufacturing process. However, as long as it is on the viewing side from the electrode 61 (organic EL element 60), it may be disposed on the viewing side surface of the substrate 30 or on any other layer. Moreover, when forming the anti-reflective film and polarizing film which were mentioned above, these films | membranes are provided in the surface at the side of visual recognition of the board | substrate 30, for example.

  In addition, when the light emitting material (EL material) of the organic EL element 60 is not a white material, for example, a material that emits one of R, G, and B necessary for full color display is used, the corresponding R, G, It is not necessary to dispose the color conversion element 29 in the light emission region of any one of the color components B. As an example, when a blue light emitting material is used as the material of the light emitting layer 63, it is not necessary to arrange a color conversion element in the light emitting region corresponding to blue. For example, when a color conversion film is used as the color conversion element 29, it is not necessary to form all the color conversion films corresponding to the respective colors. However, even in such a case, if the color purity of the emitted light of the organic EL element 60 is low, a color filter having a low transmittance of the wavelength of other components may be used as the color conversion element 29, for example, blue A color conversion film that performs wavelength conversion (color conversion) of incident light into, for example, blue light with higher purity may be used.

  As a method of manufacturing the light emitting region E in the above-described embodiment in a set shape, in addition to the first method using the second planarizing film 67 described above, the second planarizing film 67 is formed. Instead, there is a second method of adjusting the shape of the electrode 61 of the organic EL element as shown in FIG. 4A. In this case, the light emitting region E is defined by the electrode 61. Similarly, there is a third method in which the second planarizing film 67 is not used and the light emitting layer 63 is used for adjustment as shown in FIG. 4B. The light emitting region E in this case is defined by the pattern of the light emitting layer 63.

  5A to 6D are cross-sectional views for each manufacturing process showing the method for manufacturing the EL display device according to the present embodiment. These figures correspond to the BB cross-sectional view of FIG. The manufacturing process of the EL display device using the first method will be described with reference to these drawings.

  FIG. 5A is a cross-sectional view in the first step. In this step, first, the second TFT 20 is formed by an existing method, the interlayer insulating film 15 is laminated so as to cover the TFT 20, and then the source 22 s of the TFT 20 is connected via the contact hole formed at the corresponding position. A drain electrode 26 connected to the connected drive power line 53 and the drain 22d of the TFT 20 is formed. Subsequently, a color conversion element 29 is formed in a region corresponding to the light emitting region on the interlayer insulating film 15 using a color filter or a color conversion film. When a color filter is employed as the color conversion element 29, it is formed using a transfer method, a spin coating method, or the like. Here, the transfer method will be described. First, the color filter material of any color is transferred to the entire surface of the substrate by a transfer film, and the color filter material transferred to an unnecessary area is removed by etching, thereby removing the first color filter. Form. Next, a color filter material of a color different from the previous color is similarly transferred, and unnecessary portions are removed by etching to form a second color filter. At this time, it is necessary to use means for preventing the first color filter formed earlier from being damaged. Further, a color filter material of a color different from the previous two colors is similarly transferred to form a third color filter. Also at this time, as described above, it is necessary to use means that does not damage the first and second color filters. When the color conversion element 29 is formed by a color conversion film, patterning is performed by wet etching.

  FIG. 5B is a cross-sectional view in the second step. In this step, first, the first planarizing film 17 made of resin or the like is laminated on the interlayer insulating film 15 by a spin coating method or the like so as to cover the color conversion element 29, the drive power supply line 53, and the drain electrode 26. . Next, a contact hole CT that penetrates the planarizing film 17 and reaches the drain electrode 26 is formed.

  Then, an ITO layer 28, which is a transparent material that covers the contact holes CT and the entire surface of the planarizing film 17, is laminated by sputtering. Subsequently, a resist is coated on the ITO layer 28, exposed using a mask, and developed to pattern the resist. Thereafter, by using the patterned resist as a mask, the ITO layer 28 is etched to form an electrode 61 made of ITO connected to the drain electrode 26 in the contact hole CT portion.

FIG. 5C is a cross-sectional view in the third step. In this step, first, a second planarizing film material made of an organic resin or the like is laminated on the electrode 61 and the planarizing film 17 by a spin coat method or the like. Next, the second planarizing film 67 is formed by exposing and developing the second planarizing film material using the mask 105. As shown in FIG. 6, for example, the mask 105 used here has a plurality of openings R50, G50, and B50. Each opening of the mask R50, G50, B50 has a corresponding light emitting region _{(E R, E G, E} B) as wide as _{W R,} the W G, _{W B} and a height H. By patterning the second planarizing material layer by a so-called photolithography method using such a mask 105, the second planarizing film 67 is opened at a position corresponding to the shape corresponding to the light emitting region E, and the inside of the opening is formed. Then, the surface of the electrode 61 is exposed.

  FIG. 5D is a cross-sectional view in the fourth step. In this step, first, a light emitting element layer 65 including a hole transport layer 62, a light emitting layer 63, and an electron transport layer 64 is deposited on the entire surface of the substrate so as to cover the exposed electrode 61. . Subsequently, an electrode 66 is deposited on the light emitting element layer 65. Note that since the resistance of these light emitting materials is relatively high, only the light emitting element layer 65 in the region sandwiched between the electrode 61 and the electrode 66 becomes the light emitting region.

  Next, a manufacturing method for adjusting the light emitting region E by the electrode 61, which is a second method, will be described. This method may be substantially the same as the first method described above, but differs in that the second planarizing film 67 is not formed. That is, the electrode 61 is formed in the same shape and position as the light emitting region using a mask, and the light emitting element layer 65 and the electrode 66 that cover the electrode 61 are formed thereon. As a result, an EL display device having a cross-sectional structure as shown in FIG. 4A is obtained. As the mask for forming the electrode 61, for example, a mask having an opening at a position and a shape corresponding to the light emitting region E may be used similarly to the mask of FIG.

  According to the embodiment described above, by setting the light emitting area so as to achieve a desired luminance for each color component and to align the deterioration of the EL material in all the light emitting areas, It is possible to obtain a high-quality EL display device in which the luminance balance (white balance) of the color components is not lost regardless of the usage time.

  In the embodiment described above, the bottom emission type EL display device has been described as an example. However, the present invention is a so-called top emission type EL display in which the light emission of the EL element is output from the side opposite to the TFT substrate. It can also be applied to devices. In the case of the top emission type, the organic EL element is arranged on the viewing side of the opaque material such as TFT and each signal line, that is, the material that blocks light emission. The light emission area can be increased. That is, as shown in FIGS. 1 and 2, a light emitting region is substantially formed only in a region surrounded by TFTs, signal lines, and drive power supply lines and where an opaque substance is not disposed on the viewing side from the organic EL element 60. There is no restriction that you can't. A light emitting region can be formed over the entire region surrounded by each signal line and the drive power supply line 53, and each signal line and drive power supply line can be used as long as the drain electrode 26 and the electrode 61 of the corresponding TFT 20 can contact each other. The light emitting region E can be formed beyond 53. However, even in the top emission type, when considering the ease of arrangement of the light emitting region, it is preferable to share either the height or the width of the light emitting region, and to make the height of the light emitting region common. More preferably.

  The top emission type EL display device will be described below. FIG. 7 shows a cross-sectional structure of a main part of the top emission type EL display device. In addition, the same number was attached | subjected to the same layer as FIG. 3B. The TFT 20, the drain electrode 26 thereon, and the drive power supply line 53 are the same as in FIG. 3B. A flattening film 17 for flattening the surface is laminated so as to cover the drain electrode 26, the drive power supply line 53 and the interlayer insulating film 15. An electrode 71 made of a conductor such as ITO or metal is formed on the planarizing film 17 so as to cover the contact hole formed through the planarizing film 17, and the electrode 71 is formed in the contact hole at the drain electrode 26. Is electrically connected. In FIG. 7, the electrode 71 is formed so as to cover the TFT 20. However, in a case where the light emitting region is further expanded, a structure that covers the TFT 10 used as a switching element, the storage capacitor electrode 55 and the like (not shown) may be used. Next, a light emitting element layer 65 is formed on the electrode 71, and an electrode 76 made of a transparent conductive material is formed so as to cover the light emitting element layer 65. A transparent protective film 78 made of an acrylic resin is laminated on the electrode 76 so as to cover the organic EL element 70 constituted by the electrode 71, the light emitting element layer 65, and the electrode 76, and the color conversion element 39 is formed thereon. Is formed. As in FIG. 3B, the region where the electrode 71 is exposed through the opening of the second planarization film 67 is the light emitting region E. Like other bottom emission types, the region shown in FIG. 4A or 4B is used. The light emitting area E may be determined.

  The top emission type EL display device to which the present invention is applied is not limited to the above configuration. For example, the transparent substrate 78 is not laminated on the organic EL element 70, and the sealing substrate (counter substrate) 40 is the organic material of the substrate 30. A structure in which the element 70 is sealed by bonding to the periphery of the formation surface side of the EL element 70 may be employed. In this case, the color conversion element 39 may be formed on one main surface of the sealing substrate 40, for example, on the side facing the element as shown by a dotted line in FIG. It may be formed on the electrode 76 (cathode) as in the case of realization. Further, a structure in which both the transparent protective film 78 and the sealing substrate (counter substrate) 40 are provided and the color conversion element 39 is formed between either one of them or the cathode 76 and the transparent protective film 78 may be adopted.

  The present invention is not limited to the embodiment described above. As described above, the arrangement method of each light emitting region may be a stripe arrangement or a delta arrangement, and of course, the light emitting area for each row in the column direction in the delta arrangement. Various arrangements such as 0.5 region, 1 region, 1.5 region, 2 region, etc. can be adopted as the shift amount. In addition, the shape of the light emitting region is not limited to a rectangle, and may be an L shape, a polygon, or other shapes, and a reasonable shape can be adopted in designing a display device. In addition, existing methods and materials can be used for the TFT manufacturing method and materials, and of course, new materials can be used. As the TFT, a so-called top gate type TFT has been described, but a bottom gate type TFT in which the gate electrode is provided on the substrate side from the active layer may be adopted.

Schematic which shows arrangement | positioning of the light emission area | region of EL display apparatus concerning embodiment of this invention. Plan view of a light emitting region and its periphery of an EL display device according to an embodiment of the present invention Sectional drawing of EL display device concerning embodiment of this invention Sectional drawing of EL display device concerning embodiment of this invention Sectional drawing according to process of EL display device concerning embodiment of this invention Schematic of a mask used for manufacturing an EL display device according to an embodiment of the present invention. Sectional drawing of EL display device concerning embodiment of this invention Schematic showing the arrangement of light emitting areas of a conventional EL display device

Explanation of symbols

11, 13, 15 Insulating film 12, 22 Active layer 12s, 22s Source 12d, 22d Drain 14, 24 Gate electrode 16, 26 Drain electrode 17, 67 Planarizing film 29 Color conversion element 30 Substrate 51 Gate signal line 52 Drain signal line 53 Drive power supply line 54 Retention capacitance electrode line 55 Retention capacitance electrode 61, 66, 71, 76 Electrode 65 Light emitting element layer 78 Transparent protective film

Claims (20)

In a color display device,
It has a plurality of light emitting areas corresponding to a plurality of color components,
The plurality of light emitting regions each have a light emitting element layer between two electrodes and emit light of the same color;
A plurality of light-emitting elements provided on the display viewing side of the device corresponding to at least some of the plurality of light-emitting elements and emitting light having an emission spectrum at least partially different from the emission spectrum of incident light; A color conversion element,
The emitted light from the plurality of light emitting elements is visually recognized through the corresponding color conversion element in the light emitting region associated with the plurality of color conversion elements,
The area of the plurality of light emitting regions is
Each ratio for different color components of the plurality of color components of the conversion efficiency according to the luminance of the emitted light with respect to the luminance of the incident light in the color conversion element,
A color display device that supports the required luminance of each color component necessary for white display. The color display device according to claim 1,
The area of the plurality of light emitting regions is proportional to the ratio of the required luminance of each color component necessary for the white display to the luminance of the light emitted from the color conversion element for each color component. The color display device according to claim 1,
The color conversion device is a color display device that converts the incident light into light having a different wavelength, and filters and emits light of a specific wavelength band from the converted light. The color display device according to claim 1,
The color conversion element is provided between the light emitting element and the display viewing side of the device in a light emitting area where a color component of light emitted from the light emitting element is different from a color component required in a corresponding light emitting area. Color display device. In a color display device,
It has a plurality of light emitting areas corresponding to a plurality of color components,
The plurality of light emitting areas are:
A plurality of light emitting elements each having a light emitting element layer between two electrodes and emitting light of the same color;
A plurality of light-emitting elements provided on the display viewing side of the device corresponding to at least some of the plurality of light-emitting elements and emitting light having an emission spectrum at least partially different from the emission spectrum of incident light; A color conversion element,
The emitted light from the plurality of light emitting elements is visually recognized through a corresponding color conversion element and at least one layer that absorbs at least part of incident light in a light emitting region in which the plurality of color conversion elements are associated. And
The area of the plurality of light emitting regions is
The conversion efficiency according to the brightness of the emitted light with respect to the brightness of the incident light in the color conversion element and the transmission efficiency of the one or more layers that absorb at least a part of the incident light are different from each other among the plurality of color components. Each proportion of color components,
A color display device that supports the required luminance of each color component necessary for white display. The color display device according to claim 5,
The areas of the plurality of light emitting regions are required brightness of each color component necessary for the white display relative to the brightness of light emitted through the color conversion element and at least one layer that absorbs at least part of incident light. A color display device proportional to the proportion of each color component. The color display device according to claim 1 or 5,
The color conversion device is a color display device that filters and emits light of a specific wavelength band from the incident light. The color display device according to claim 7.
The color display device in which the conversion efficiency of the color conversion element corresponds to the transmission efficiency of a filter. The color display device according to claim 1 or 5,
The color conversion device is a color display device that emits light after converting the incident light into light of different wavelengths. The color display device according to claim 9.
The color conversion device corresponds to the color conversion efficiency of the color conversion material. The color display device according to claim 1 or 5,
A color display device that achieves a predetermined white display on the viewing side when power is supplied to the light emitting elements provided in the plurality of light emitting regions at the same current density to emit light. The color display device according to claim 5,
The color display device, wherein the at least one layer that absorbs at least part of incident light includes an optical functional layer. The color display device according to claim 5,
The color display device, wherein the at least one layer that absorbs at least part of incident light includes an insulating layer formed between the light emitting element and the display viewing side of the device. In a color display device having a first light emitting region and a second light emitting region associated with different color components,
A plurality of light emitting elements each having a light emitting element layer between two electrodes and emitting light of the same color;
Provided on the display viewing side from the light emitting element of the apparatus corresponding to at least a part of the light emitting elements of the plurality of light emitting elements, and at least a part of the emission spectrum of the incident light is an emission spectrum different from each other in color. A first color conversion element and a second color conversion element that emit light;
In the first light emitting region, light emitted from the light emitting element is visually recognized through the first color conversion element,
In the second light emitting region, the emitted light from the light emitting element is visually recognized through the second color conversion element,
The conversion efficiency according to the ratio of the emitted light to the incident light of the first color conversion element is higher than the conversion efficiency according to the ratio of the emitted light to the incident light of the second color conversion element,
The color display device has an area of the first light emitting region smaller than an area of the second light emitting region. The color display device according to claim 14.
The ratio of the area of the first light emitting region to the area of the second light emitting region is:
The luminance required for white display of the color component associated with the first light emitting region with respect to the emission light luminance from the first color conversion element;
A color display device corresponding to a ratio of a luminance required for white display of a color component associated with the second light emitting region to a luminance of light emitted from the second color conversion element. In a color display device having a first light emitting region and a second light emitting region associated with different color components,
A plurality of light emitting elements each having a light emitting element layer between two electrodes and emitting light of the same color;
Provided on the display viewing side from the light emitting element of the apparatus corresponding to at least a part of the light emitting elements of the plurality of light emitting elements, and at least a part of the emission spectrum of the incident light is an emission spectrum different from each other in color. A first color conversion element and a second color conversion element that emit light;
In the first light emitting region, light emitted from the light emitting element is visually recognized through the first color conversion element,
In the second light emitting region, the emitted light from the light emitting element is visually recognized through the second color conversion element,
The areas of the first and second light emitting regions are S ₁ and S ₂ , respectively.
The luminances of the incident light to the first and second color conversion elements are L ₁ and L ₂ ,
The transmission efficiencies of the first and second color conversion elements are TE ₁ and TE ₂ , respectively.
The luminance of the first color component required in the first light emitting area and the luminance of the second color component required in the second light emitting area for the predetermined color expressed by the additive color are a ₁ and a ₂ , respectively. and when,
S ₁ : S ₂ = a ₁ / (L ₁ · TE ₁ ): a ₂ / (L ₂ · TE ₂ )
A color display device that meets the requirements. In a color display device having a first light emitting region and a second light emitting region associated with different color components,
A plurality of light emitting elements each having a light emitting element layer between two electrodes and emitting light of the same color;
Provided on the display viewing side from the light emitting element of the apparatus corresponding to at least a part of the light emitting elements of the plurality of light emitting elements, and at least a part of the emission spectrum of the incident light is an emission spectrum different from each other in color. A first color conversion element and a second color conversion element that emit light;
In the first light emitting region, light emitted from the light emitting element is visually recognized through the first color conversion element,
In the second light emitting region, the emitted light from the light emitting element is visually recognized through the second color conversion element,
The areas of the first and second light emitting regions are S ₁ and S ₂ , respectively.
The luminances of the incident light to the first and second color conversion elements are L ₁ and L ₂ ,
The transmission efficiencies of the first and second color conversion elements are TE ₁ and TE ₂ , respectively.
The luminance of the first color component required in the first light emitting area and the luminance of the second color component required in the second light emitting area for the predetermined color expressed by the additive color are a ₁ and a ₂ , respectively. ,
The luminance half-life period of the first color component in the first light emitting region when the light emitting elements in the first and second light emitting regions are driven at the same current density, and the second color in the second light emitting region. When the luminance half-life of the components is T ₁ and T ₂ ,
S ₁ : S ₂ = a ₁ / (L ₁ · TE ₁ · T ₁ ): a ₂ / (L ₂ · TE ₂ · T ₂ )
A color display device that meets the requirements. The color display device according to claim 17.
The luminance half-life period of the first color component in the first light-emitting area and the luminance half-life period of the second color component in the second light-emitting area are the first and second light-emitting areas after performing an aging process. A color display device in which the luminance of the light of the first and second color components is reduced by half when each of the light emitting elements is driven at the same current density. The color display device according to claim 18,
A color display device in which at least one of the first and second color components has a constant deterioration rate of light emission luminance. In a color display device,
It has a plurality of light emitting areas corresponding to a plurality of color components,
The plurality of light emitting areas are:
A plurality of light emitting elements each having a light emitting element layer between two electrodes and emitting light of the same color;
A plurality of light-emitting elements provided on the display viewing side of the device corresponding to at least some of the plurality of light-emitting elements and emitting light having an emission spectrum at least partially different from the emission spectrum of incident light; A color conversion element,
The emitted light from the plurality of light emitting elements is visually recognized through the corresponding color conversion element in the light emitting region associated with the plurality of color conversion elements,
The area of the plurality of light emitting regions is
Each ratio for different color components of the plurality of color components of the conversion efficiency according to the luminance of the emitted light with respect to the luminance of the incident light in the color conversion element,
A color display device that responds to the required luminance of each color component necessary to realize a predetermined color expressed by additive color.

Images