JP2007265839A - Electroluminescent device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simultaneously display separate images on a front screen and a back screen having sizes different from each other, and to eliminate an EL (Electroluminescent) element without contributing to display of an image, in an electroluminescent device. <P>SOLUTION: This electroluminescent device has a double-sided part 12 and a single-sided part 11. The double-sided part 12 has a plurality of double-sided dots D2, and each double-sided dot D2 has a sub-dot D21 for the front surface and a sub-dot D22 for the back surface. The sub-dot D21 for the front surface transmits light from an organic EL element P2 of itself to emit it from the front surface F2 of the double-sided part 12. The sub-dot D22 for the back surface transmits light from an organic EL element P3 of itself to emit it from the back surface R2. The single-sided part 11 has a plurality of single-sided dots D1. Each single-sided dot D1 transmits light from an organic EL element P1 of itself to emit it from the front surface F1 of the single-sided part 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an electroluminescence device having an EL (Electro Luminescent) element and an electronic apparatus including the same.

Patent Document 1 and Non-Patent Document 1 disclose a flat electroluminescent device in which a number of EL elements are arranged in a plane on an element substrate. This apparatus can simultaneously display separate images on the front and back surfaces, and has a plurality of double-sided dots constituting a front screen (front screen) and a back screen (back screen). Each of these double-sided dots has one front side sub dot and one back side sub dot. The surface sub-dot has one EL element, and transmits light from the EL element to be emitted from the front screen. The sub-dot for the back surface has another EL element and transmits light from the EL element to be emitted from the back screen.
JP 2000-363034 A Chung-Wen Ko, 7 others, “Development of Full Color Double Sided Active Matrix OLED”, Information Display Society, Proceedings of the No. 12th International Display Workshop in Conjunction with Asia Display 2005 Volume 1 (Proceedings of The 12th International Display Workshops in conjunction with Asia Display 2005 Volume 1), p.625-628

Here, it is considered that the above-described electroluminescence device is applied to a device (for example, a mobile phone) in which the front screen and the back screen have different sizes. In this case, a large number of double-sided dots are provided even in a portion where the front screen and the back screen do not overlap, and the gradation of the back-side subdots of these double-sided dots must be made constant. Specifically, it is necessary to configure the apparatus so that the EL elements of these back-side subdots continue to emit no light or continue to emit light at a constant luminance. As a result, the device includes a large number of EL elements that do not contribute to image display.
Therefore, the present invention includes an electroluminescence device that can simultaneously display separate images on front and back screens having different sizes and does not include an EL element that does not contribute to image display. Provide electronic equipment.

The electroluminescence device according to the present invention has a plate-like double-sided portion that emits light from the front and back surfaces, and a single-sided portion that emits light from the surface that is flush with the surface of the double-sided portion, A plurality of double-sided dots exposed on the front and back surfaces of the double-sided portion, each of the plurality of double-sided dots each having a surface sub-dot exposed on the surface of the double-sided portion, Back surface sub-dots exposed on the back surface, and each of the front surface sub dots of the plurality of double-sided dots has only one EL element and transmits light from the EL element. Each of the back surface sub-dots emitted from the front surface of the double-sided portion and included in the plurality of double-sided dots has only one EL element, and transmits light from the EL element from the back surface of the double-sided portion. The single-sided portion is A plurality of single-sided dots exposed on the surface of the surface portion, each of the plurality of single-sided dots has only one EL element, and transmits light from the EL element from the surface of the single-sided portion. It is characterized by injecting.
Here, the “EL element” is an element having a solid light-emitting layer that emits light through excitation of excitons by electric energy and two electrodes that sandwich the light-emitting layer. Examples of the electrical energy here include current, voltage, and current density. Examples of the EL element include an organic EL element in which a light emitting layer is formed from an organic material and an inorganic EL element in which a light emitting layer is formed from an inorganic material. In addition, the screen for displaying an image is composed of a plurality of areas having a common size and variable gradation, and each of these areas having an end face is a “dot”.
One type is “double-sided dots” and “single-sided dots”.
According to the above electroluminescence device, it can be configured only by a double-sided portion where light from all internal EL elements is emitted from the front or back surface and a single-sided portion where light from all internal EL elements is emitted from the front surface. In addition, the front screen can be configured only by the surface of the double-sided portion and the surface of the single-sided portion, and the back screen narrower than the front screen can be configured only by the back surface of the single-sided portion. That is, separate images can be simultaneously displayed on the front and back screens having different sizes, and there is no need to provide EL elements that do not contribute to image display.

In the above electroluminescence device, usually, in each double-sided dot, the EL element of the front surface subdot and the EL element of the back surface subdot do not overlap each other in the direction perpendicular to the double-sided portion. Become. In this configuration, the light emitting layer of each EL element that each double-sided dot has is significantly narrower than the area occupied by the double-sided dot on the front screen. In general, in order to suppress variations in gradation between dots on the front screen, the light emitting layer of the EL element of the plurality of single-sided dots is narrowed to match the narrow light emitting layer, while the brightness of the entire front screen is reduced. In order to keep the brightness good, the luminance of all the light emitting layers is greatly increased. However, if this is done, the lifetime of all EL elements will be significantly shortened. If the number of EL elements that have reached the end of their life increases, the display quality of the image deteriorates.
It is important to reduce the number of elements.
Therefore, in the above-described electroluminescence device, each of the EL elements included in the plurality of single-sided dots may be wider than any of the EL elements included in the plurality of double-sided dots with respect to the area of the light emitting layer.
In the electroluminescence device of this aspect, it is not necessary to increase the luminance of the light emitting layer of each EL element for each EL element included in the plurality of single-sided dots. Therefore,
According to the electroluminescence device of this aspect, the number of EL elements whose lifetime is significantly shortened can be reduced.

An electronic apparatus according to the present invention includes any one of the above electroluminescence devices. Therefore, separate images can be displayed on the front and back screens having different sizes without providing two or more electroluminescence devices, and there is no need to provide EL elements that do not contribute to image display.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, in the drawings, the ratio of the dimensions of each part is appropriately changed from the actual one.

<Electroluminescence device>
FIG. 1 is a front perspective view of an electroluminescence device 10 according to the present embodiment, and FIG. 2 is a rear perspective view. The electroluminescence device 10 has a rectangular flat plate shape and has a front surface F and a back surface R. The electroluminescence device 10 is divided into a double-sided part 12 located in the center and a single-sided part 11 surrounding the double-sided part. In addition, you may deform | transform this Embodiment so that the double-sided part 12 may be located besides a center.

The double-sided portion 12 has a rectangular flat plate shape, and emits light from the front surface F2 and the back surface (back screen) R2. The single-sided portion 11 has a flat plate shape with the same thickness as the double-sided portion 12, and emits light from the front surface F1 and the back surface R1. The surface F2 and the surface F1 are flush and constitute the surface F. The front surface F corresponds to a front screen, and the dots constituting the front screen are only the dots in the single-sided portion 11 and the double-sided portion 12. The back surface R2 corresponds to the back screen, and the dots constituting the back screen are only the dots in the double-sided portion 12.

FIG. 3 is a diagram schematically showing the arrangement of dots in the electroluminescence device 10. As shown in this figure, in the electroluminescent device 10, a plurality of dots D that emit light are arranged in an array. The dots D are classified into three types according to the color of the emitted light. That is, R dot D that emits red (R) light, G that emits green (G) light
Dot D, B dot D emitting blue (B) light. In the array of dots D, these three types of dots D are regularly arranged.

All the dots D are divided into double-sided dots D2 in the double-sided part 12 (hatched dots D in FIG. 3) and single-sided dots D1 in the single-sided part 11. All of the double-sided dots D2 in the double-sided part 12 are exposed on the front surface F2 and the back surface R2 of the double-sided part 12. All of the single-sided dots D1 in the single-sided part 11 are exposed on the surface F1 of the single-sided part 11. The areas occupied by all the dots D on the front surface R are the same shape and size, and a plurality of dots D are formed on the back surface R.
The areas occupied in 2 are the same shape and size.

The structure of the dot D will be described with reference to FIGS. 4 is a plan view schematically showing the structure of a portion surrounded by a two-dot chain line in FIG. 3, FIG. 5 is a cross-sectional view taken along line AA in FIG. 4, and FIG. It is a BB arrow directional cross-sectional view. However, in each figure, illustration of some members is abbreviate | omitted suitably.

As shown in FIG. 4, each single-sided dot D1 has one organic EL element P (organic EL element) as a light source.
Element P1). Each double-sided dot D2 is a surface sub-dot D exposed on the surface F2.
21 and back surface subdots D22 exposed on the back surface R2. The front surface subdot D21 has one organic EL element P (organic EL element P2), and the rear surface subdot D22 has one organic EL element P (organic EL element P3). Each organic EL element P has a solid light-emitting layer formed of an organic material and two electrodes sandwiching the light-emitting layer, and emits light with luminance according to the current (density) flowing between these two electrodes. In FIG. 4, the same hatching is given to the light emitting layer formed from the same material.

As shown in FIGS. 5 and 6, the electroluminescence device 10 includes a flat element substrate 21 formed of a material having a high light transmittance such as glass or plastic. The lower surface of the element substrate 21 is the surface F. On the element substrate 21, for each organic EL element P, a thin film transistor T that supplies a current to the corresponding organic EL element P is formed. Each thin film transistor T drives a corresponding organic EL element P. The thin film transistor T has a channel width of W1.
There are two types: a thin film transistor T1 and a thin film transistor T2 having a channel width W2.
At this time, the channel width W1 of the thin film transistor T1 and the channel width W2 of the thin film transistor T2 are assumed to be the same, and this is applied when the same current is supplied.
Further, the case where the channel width W1 and the channel width W2 are different is considered, and this is applied when a different current supply is required for each organic EL element P.

Each thin film transistor T includes a semiconductor layer 22 formed of a semiconductor material such as silicon on the element substrate 21, a gate electrode Gt formed on the semiconductor layer 22 with a light-transmitting insulating layer 23 interposed therebetween, and an insulating layer. 23 and the source electrode St and the drain electrode Dt formed on the gate electrode Gt with the light-transmissive insulating layer 24 interposed therebetween. The semiconductor layer 22 includes a channel region CR that faces the gate electrode Gt, and a source region SR and a drain region DR that sandwich the channel region CR. The source region SR is electrically connected to the source electrode St, and the drain region DR is electrically connected to the drain electrode Dt. The drain electrode Dt is connected to a power supply line (not shown). The channel width of each thin film transistor T is the length of the channel region CR of the thin film transistor T in the direction perpendicular to the plane of FIG. 5 and FIG.

As shown in FIG. 5, a thin film transistor T1 is formed as the thin film transistor T in the single-sided dot D1. A light-transmitting anode layer 26 is formed on the thin film transistor T1 and the insulating layer 24 with a light-transmitting insulating layer 25 interposed therebetween. The translucent anode layer 26 is made of ITO (In
such as dium tin oxide), which is made of a conductive material having a sufficiently high light transmittance, and is electrically connected to the drain electrode Dt of the thin film transistor T1. That is, the translucent anode layer 26 functions as an anode (one electrode) of the organic EL element P1 in the single-sided dot D1.

A partition wall 27 is formed on the insulating layer 25 and the translucent anode layer 26 so as to surround the upper surface of the translucent anode layer 26. The partition wall 27 is made of polyimide, for example. The translucent anode layer 26 and the partition wall 27 define a recess, and the light emitting layer 28 is formed in the recess.
Each light-emitting layer 28 in the single-sided portion 11 has a color of light emitted from the single-sided dot D1 having the light-emitting layer 28 (
R, G, B) are formed from organic materials, and the area (S1) is all organic EL
Common to the element P1.

On the partition wall 27 and the light emitting layer 28, a sufficiently thick light-shielding cathode layer 29 made of a conductive material such as a magnesium silver alloy is formed in common to all the single-sided dots D1 so as to cover them. Yes. The light-shielding cathode layer 29 is connected to a ground line (not shown), and functions as a cathode (the other electrode) of the organic EL element P1 in the single-sided dot D1.

On the light-shielding cathode layer 29, a sealing layer (not shown) that covers all the organic EL elements P and protects them from the outside air is formed. The sealing layer is made of a material having a high light transmittance such as glass or plastic, and the surface opposite to the light-shielding cathode layer 29 (back surface R) is flat over the entire surface. In addition, you may deform | transform this Embodiment so that only a part of this surface (back surface R2) may become flat.

In each single-sided dot D1, when a constant power supply voltage is supplied to the source electrode St of the thin film transistor T1 in the single-sided dot D1 and a voltage is supplied to the gate electrode Gt, the organic EL element P1 in the single-sided dot D1 Driven to emit light. The light emitted from the light emitting layer 28 of the organic EL element P1 to the surface F1 is sequentially transmitted through the light-transmitting anode layer 26, the insulating layers 25 to 23, and the element substrate 21, and is emitted from the surface F1. The gradation of the region occupying the surface F1 corresponds to the voltage supplied to the gate electrode Gt of the thin film transistor T1. On the other hand, light emitted from the light emitting layer 28 to the back surface R1 is blocked by the sufficiently thick light-shielding cathode layer 29.

As shown in FIG. 6, the structure of the double-sided dot D2 is the same as that of the single-sided dot D1. However, in each front surface subdot D21 and each rear surface subdot D22, there is a thin film transistor T.
A thin film transistor T2 is formed. Further, in the sub-dot D22 for the back surface, the reflective layer 30 is formed between the insulating layer 25 and the translucent anode layer 26. The reflective layer 30 is made of a conductive material having a high light reflectance such as aluminum. The back surface subdot D22 is electrically connected to the drain electrode Dt of the thin film transistor T2 in the reflective layer 30.
The reflective layer 30 and the translucent anode layer 26 function as an anode (one electrode) of the organic EL element P3.

Moreover, the area (S2) of each light emitting layer 28 in the double-sided part 12 is common to all the organic EL elements P2 and all the organic EL elements P3. S2 <S1, and S2 is about ½ times S1. The light-shielding cathode layer 29 is formed in common for all the front surface subdots D21, but is not formed on the light emitting layer 28 of the back surface subdots D22. In the double-sided dot D2, the light-shielding cathode layer 29, the light emitting layer 28, and the partition wall 27 are sufficiently thin and formed of a material such as magnesium silver alloy under the sealing layer so as to cover them. A translucent cathode layer 31 is formed. The translucent cathode layer 31 is common to all the double-sided dots D2, and the surface sub-dot D21 functions as a cathode (the other electrode) of the organic EL element P2 together with the light-shielding cathode layer 29. The back surface subdot D22 functions alone as a cathode (the other electrode) of the organic EL element P3.

In each surface subdot D21, when a constant power supply voltage is supplied to the source electrode St of the thin film transistor T2 in the surface subdot D21 and a voltage is supplied to the gate electrode Gt, the surface subdot D21 The organic EL element P2 is driven to emit light. Light emitted from the light emitting layer 28 of the organic EL element P2 to the surface F2 is transmitted through the light-transmitting anode layer 26, the insulating layers 25 to 23, and the element substrate 21 in this order, and is emitted from the surface F2. The gradation of the region occupied by the double-sided dot D2 including D21 on the surface F2 corresponds to the voltage supplied to the gate electrode Gt of the thin film transistor T2. On the other hand, light emitted from the light emitting layer 28 to the back surface R2 is blocked by the sufficiently thick light-shielding cathode layer 29.

In each back surface sub dot D22, when a constant power supply voltage is supplied to the source electrode St of the thin film transistor T2 in the back surface sub dot D22 and a voltage is supplied to the gate electrode Gt, the back surface sub dot D22 The organic EL element P3 is driven to emit light. Light emitted from the light emitting layer 28 of the organic EL element P3 to the back surface R2 is sufficiently thin.
1 and the sealing layer (not shown) are sequentially transmitted and emitted from the back surface R2, and the back surface sub-dot D
The gradation of the area occupied by the double-sided dot D2 including 22 on the back surface R2 is the thin film transistor T2.
This corresponds to the voltage supplied to the gate electrode Gt. On the other hand, the emitted light from the light emitting layer 28 to the surface F <b> 2 passes through the translucent anode layer 26 and is blocked by the reflective layer 30.

The gradation of the area occupied by each dot D on the surface F corresponds to the luminance of the light emitting area occupied in the area. Since the area (S2) of the light emitting layer of each organic EL element P2 is about ½ times the area (S1) of the light emitting layer of each organic EL element P1, the area occupied by each single-sided dot D1 on the surface F and the both surfaces In order to make the gradation uniform with the area occupied by the dots D2, the luminance of each organic EL element P1 needs to be about ½ times the luminance of each organic EL element P2. That is, the current density for driving each organic EL element P1 is approximately 1 / of the current density for driving each organic EL element P2.
Must be doubled. When compared in terms of current (amount), they are almost equivalent.

As is clear from the above description, the electroluminescence device 10 employs a configuration in which a voltage corresponding to the gradation of each primary color component of the pixels constituting the full color image to be displayed is supplied to the gate electrode Gt of each thin film transistor T. Thus, it functions as a display device capable of simultaneously displaying separate full color images on the front screen (front surface F) and the back screen (back surface R1) having different sizes. Moreover, since the electroluminescence device 10 does not include the organic EL element P that does not contribute to image display, the electroluminescence device 10 has a configuration that does not waste.
In addition, according to the electroluminescence device 10, variations in gradation on the front screen between the double-sided dots D2 and the single-sided dots D1 are suppressed. Further, for each organic EL element P1, there is no need to significantly increase the current supplied to the organic EL element P1. Therefore, the number of organic EL elements P whose lifetime is significantly shortened can be reduced.
In the electroluminescence device 10, the anode of the organic EL element P <b> 3 is the reflective layer 3.
0, a light-transmitting cathode in which the cathode of the organic EL element P2 functions as the cathode of the organic EL element P1, and the light-transmitting anode layer 26 that functions as the anode of the organic EL element P1 and the organic EL element P2 Since it consists of two layers of the layer 29 and the translucent cathode layer 31 which functions as the cathode of the organic EL element P3, it can be manufactured by a simple process.

In the present embodiment, the driving method of the organic EL element is based on an active driving method in which each single-sided dot D1, each surface sub-dot D21 and each surface sub-dot D22 has a thin film transistor T. It is good also as a form which deform | transforms and presupposes the passive drive system. Further, the present embodiment may be modified to adopt an inorganic EL element instead of the organic EL element P.

<Electronic equipment>
Next, an electronic device using each of the above electroluminescence devices will be described.
Here, a mobile phone 3000 to which the electroluminescence device 10 is applied is given as an example of the electronic apparatus. FIG. 7 shows the appearance of the front side of the mobile phone 3000, and FIG. 8 shows the appearance of the back side. As shown in these drawings, the cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and the electroluminescence device 10 as a display device. By operating the scroll button 3002, a full-color image is scroll-displayed on the front surface (front screen) F. In addition, another full-color image is displayed on the back side (back screen) R2 on the back side.

Electronic devices to which the electroluminescence device according to the present invention is applied include personal computers, personal digital assistants (PDAs), digital still cameras, televisions, video cameras, car navigation devices, pagers, electronic notebooks, Electronic paper, calculator, word processor, workstation, video phone, PO
Examples include an S terminal, a printer, a scanner, a copying machine, a video player, and a device equipped with a touch panel. Moreover, the use of the electroluminescence device according to the present invention is not limited to display of an image.

It is a perspective view which shows the external appearance of the surface side of the electroluminescent apparatus 10 which concerns on embodiment of this invention. 1 is a perspective view showing an appearance of a back side of an electroluminescence device 10. FIG. FIG. 3 is a diagram schematically showing the arrangement of dots in the electroluminescence device 10. It is a top view which shows typically the structure of the part enclosed with the dashed-two dotted line of FIG. FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. FIG. 5 is a cross-sectional view taken along line BB in FIG. 4. 1 is a perspective view showing an external appearance of a front side of a cellular phone 3000 to which an electroluminescence device 10 is applied. It is a perspective view showing the appearance of the back side of mobile phone 3000. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Electroluminescent apparatus, 11 ... Single-sided part, 12 ... Both-sided part, 28 ... Light emitting layer,
D ... dot, D1 ... single-sided dot, D2 ... double-sided dot, D21 ... surface sub-dot, D22
... sub-dots for back side, F ... front side (front screen), F1, F2 ... front side, P (P1, P2, P3)
... Organic EL element, R, R1... Back surface, R2... Back surface (back screen), T, T1, T2.

Claims (3)

Plate-like double-sided portions that emit light from the front and back surfaces;
Having a single-sided portion that emits light from the surface of the double-sided portion and the same surface,
The double-sided portion has a plurality of double-sided dots exposed on the front and back surfaces of the double-sided portion,
Each of the plurality of double-sided dots has a front surface sub-dot exposed on the surface of the double-sided portion, and a back surface sub-dot exposed on the back surface of the double-sided portion,
Each of the surface subdots of the plurality of double-sided dots has only one electroluminescent element, transmits light from the electroluminescent element, and is emitted from the surface of the double-sided part,
Each of the sub-dots for the back surface of the plurality of double-sided dots has only one electroluminescent element, transmits light from the electroluminescent element, and is emitted from the back surface of the double-sided part,
The single-sided portion has a plurality of single-sided dots exposed on the surface of the single-sided portion,
Each of the plurality of single-sided dots has only one electroluminescent element, transmits light from the electroluminescent element, and exits from the surface of the single-sided part.
An electroluminescence device. Each of the electroluminescent elements that the plurality of single-sided dots have is wider than any of the electroluminescent elements that the plurality of double-sided dots have about the area of the light emitting layer.
The electroluminescent device according to claim 1. An electronic device comprising the electroluminescence device according to claim 1.

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