CN1776933A - Organic Electroluminescence Display Device - Google Patents

Abstract

The present invention discloses an organic electroluminescent display device. The device comprises: the display device comprises a first substrate, a second substrate, at least one organic electroluminescent device and at least one photochromic film. The first and second substrates are disposed in parallel and opposite to each other. The organic electroluminescent device is at least arranged on one substrate and between the first substrate and the second substrate. The photochromic film is at least arranged on the first substrate and/or the second substrate, so that a light source of the organic electroluminescent device passes through the photochromic film.

Description

Organic Electroluminescence Display Device

technical field

The present invention relates to a flat display device, in particular to an organic electroluminescence display device, which is used to maintain the contrast while improving the light transmittance (light utilization rate).

Background technique

An organic electroluminescent diode (OELD) is a self-luminous element using organic materials. Compared with traditional inorganic light-emitting diodes (LEDs), which require strict crystal growth requirements, organic electroluminescent diodes can be easily fabricated on large-area substrates to form amorphous thin films. On the other hand, OLED is also different from liquid crystal display technology and does not require a backlight module, so the process can be effectively simplified. With the rapid development of technology, organic electroluminescent diodes will be used in small-sized full-color display panels such as personal digital assistants and digital cameras in the future. Once this technology becomes more mature, it will be extended to large-sized computer and TV screens , and even applied to flexible displays.

Typically, an organic electroluminescent diode includes: an anode, a cathode, and an organic light-emitting layer disposed between the anode and the cathode. When a potential difference is applied between the cathode and the anode, electrons are injected from the cathode into the organic light emitting layer. At the same time, holes are injected from the anode into the organic light-emitting layer. Afterwards, the electrons and holes recombine in the organic light-emitting layer to release energy in the form of light. This self-illuminating element has a good contrast ratio (contrast ratio, CR) in a dark room, which is defined as follows:

CR＝(L _ON +B×R)/(L _OFF +B×R)

Among them, L _ON is the brightness of the organic electroluminescent display device turned on; L _OFF is the brightness of the organic electroluminescent display device turned on; B is the brightness of ambient light; R is the panel reflectance of the organic electroluminescent display device.

However, when outdoors, the strong external light reflection (B×R) is enhanced, so that the contrast ratio approaches 1. In order to improve this problem, a common practice is to add a polarizing film outside the display panel to reduce the reflectivity (R). Although the polarizing film can reduce the reflectivity and improve the contrast ratio of the display device outdoors, its transmittance is very low, about 40%, so that the organic electroluminescent diode needs to be higher than the original no matter whether it is indoors or outdoors. Driven by the brightness of the original organic electroluminescent diode, it shortens the life of the original organic light-emitting diode and consumes more power.

Contents of the invention

In view of this, the purpose of the present invention is to provide an organic electroluminescence display device, which controls the reflection intensity of the background light source by replacing the traditional polarizing film with a photochromic film/substrate, in order to effectively increase the display device under the strong external light source. At the same time of contrast, it can still maintain its high light transmittance indoors.

According to the above objective, the present invention provides an organic electroluminescent display device, comprising: first and second substrates, at least one organic electroluminescent device, and at least one photochromic film. The first and second substrates are arranged parallel to each other. The organic electroluminescent device is at least disposed on one of its substrates and interposed between the first and second substrates. The photochromic film is disposed on the first and/or second substrate, so that the light source of the organic electroluminescent device passes through the photochromic film.

According to the above objective, the present invention provides an organic electroluminescent display device, comprising: first and second substrates and at least one organic electroluminescent device. The first and second substrates are arranged parallel to each other. The organic electroluminescent device is at least disposed on one of its substrates and interposed between the first and second substrates. At least one of the first and second substrates is a color-changing substrate, so that the light source of the organic electroluminescent device passes through the color-changing substrate.

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be described in more detail below with reference to the accompanying drawings and preferred embodiments.

Description of drawings

1A to 1C are schematic cross-sectional views illustrating an organic electroluminescent display device using a photochromic film according to different embodiments of the present invention.

2A to 2C are schematic cross-sectional views illustrating organic electroluminescent display devices using light-chromic glass according to different embodiments of the present invention.

FIG. 3 is a schematic block diagram illustrating an organic electroluminescent display device with active contrast compensation according to an embodiment of the present invention.

simple notation

10, 11, 12, 20, 21, 22, 40～organic electroluminescence display device; 30～drive circuit; 32～photodetection device; 34～control unit; 100, 200～first substrate; 36, 102, 108 , 202, 204～organic electroluminescent device; 104, 112～color-changing film; 110, 210～second substrate; L～light source.

Detailed ways

An organic electroluminescent display device using a photochromic film according to different embodiments of the present invention will be described below with reference to FIGS. 1A to 1C .

First, please refer to FIG. 1A , the organic electroluminescent display device 10 includes: a first substrate 100 , a second substrate 110 , at least one organic electroluminescent device 102 and at least one photochromic film 104 . The first substrate 100 and the second substrate 110 are parallel and oppositely disposed. In this embodiment, the first substrate 100 and the second substrate 110 can be transparent substrates, such as glass or quartz substrates. Furthermore, the first substrate 100 can be an active array substrate with a plurality of thin film transistors thereon, and the second substrate 110 can be a filter substrate with a plurality of filters thereon. Here, to simplify the drawing, only a flat substrate is shown.

The organic electroluminescent device 102 is at least disposed on the upper surface of the first substrate 100 and/or the second substrate 110 and interposed between the first substrate 100 and the second substrate 110 . In this embodiment, it is described as being disposed on the upper surface of the first substrate 100 . Here, the "upper surface" of a substrate refers to a surface facing another substrate. Likewise, the "lower surface" of a substrate refers to the surface opposite the upper surface of the substrate. The organic electroluminescent device 102 can be a top emitting organic electroluminescent diode or a bottom emitting organic electroluminescent diode. For example, the organic electroluminescent device 102 is a bottom-emitting organic electroluminescent diode, so that the light source L emitted by it travels from the upper surface of the first substrate 100 to the lower surface thereof to reach the outside. Generally speaking, an organic electroluminescent diode includes: an anode, a cathode, and an organic light-emitting layer between the anode and the cathode, which may include: a hole transport layer adjacent to the anode, an electron transport layer adjacent to the cathode, And a light emitting layer arranged between the hole transport layer and the electron transport layer. Here, to simplify the drawing, only a flat block is used to represent it.

A photochromic film 104, such as a plastic film containing reactive photochromic spirooxazine (spirooxazine), a plastic film containing an inorganic color-changing material (such as WO ₃ ), etc., is arranged at least on the lower surface of the first substrate 100, so that the organic electroluminescent The light source L of the device 102 passes through the photochromic film 104 . In other embodiments, the photochromic film 104 may be disposed on the upper surface of the first substrate 100 between the first substrate 100 and the organic electroluminescent device 102 . When the photochromic film 104 is indoors, it receives less ultraviolet light and is transparent. Therefore, it will not affect the penetration of the light source L of the organic electroluminescent device 102 like the traditionally used polarizing film, so it can maintain the organic electroluminescent device. The excitation light displays the brightness of the device 10 . On the other hand, when the photochromic film 104 is in an outdoor strong light environment, it receives more ultraviolet light and presents a dark color. Although it will affect the penetration of the light source L of the organic electroluminescent device 102, it can effectively reduce the external intensity. Light reflection, while exhibiting a preferred contrast ratio (CR). Therefore, according to the organic electroluminescent display device 10 of this embodiment, there is no need to increase the brightness of the organic electroluminescent device 102 when used indoors, which has the advantages of saving power and prolonging its lifespan. And when it is used outdoors, it can also provide a preferable contrast ratio and provide a preferable visual quality.

Next, please refer to FIG. 1B , which shows an organic electroluminescent display device 11 according to an embodiment of the present invention, wherein the components that are the same as those in FIG. 1A use the same reference numerals, and related descriptions are omitted. Different from the embodiment in FIG. 1A, the organic electroluminescent device 102 of this embodiment is a top-emitting organic electroluminescent diode, and the photochromic film 104 is arranged on the lower surface of the second substrate 110, so that the organic electroluminescent device 102 The light source L of 102 can pass through the photochromic film 104 . In other embodiments, the photochromic film 104 may be disposed on the upper surface of the second substrate 110 between the second substrate 110 and the organic electroluminescent device 102 . The organic electroluminescent display device 11 according to this embodiment also has the advantages described in the embodiment of FIG. 1A , which will not be repeated here.

Next, please refer to FIG. 1C , which shows a double-sided display organic electroluminescent display device 12 according to an embodiment of the present invention, wherein the components that are the same as those in FIG. 1A or 1B use the same reference numerals, and related descriptions are omitted. In this embodiment, the double-sided organic electroluminescent display device 12 includes: a first substrate 100 , a second substrate 110 , organic electroluminescent devices 102 and 108 , and photochromic films 104 and 112 . The organic electroluminescent devices 102 and 108 are disposed on the upper surfaces of the first substrate 100 and the second substrate 110 respectively, and the organic electroluminescent devices 102 and 108 are interposed between the first substrate 100 and the second substrate 110 . In this embodiment, the organic electroluminescent devices 102 and 108 can be bottom emitting organic electroluminescent diodes.

The photochromic films 104 and 112 are respectively arranged on the lower surfaces of the first substrate 100 and the second substrate 110, so that the light source L of the organic electroluminescent device 102 passes through the photochromic film 104, and the light source L of the organic electroluminescent device 108 passes through the photochromic film 104. Photochromic film 112 . In other embodiments, the photochromic film 104 can be disposed on the upper surface of the first substrate 100 between the first substrate 100 and the organic electroluminescent device 102 , and the photochromic film 112 can be disposed on the second substrate 110 The upper surface is between the second substrate 110 and the organic electroluminescent device 108 . The organic electroluminescent display device 12 with double-sided display according to this embodiment also has the advantages described in the embodiments of FIGS. 1A and 1B , which will not be repeated here.

An organic electroluminescence display device using a photochromic substrate according to different embodiments of the present invention will be described below with reference to FIGS. 2A to 2C .

Referring to FIG. 2A , the organic electroluminescent display device 20 includes: a first substrate 200 , a second substrate 210 and at least one organic electroluminescent device 202 . In this embodiment, like the organic electroluminescent display device 10 in FIG. 1A , the first and second substrates 200 and 210 are arranged parallel to each other, and the organic electroluminescent device 202, such as a bottom-emitting organic electroluminescent diode, is arranged On the upper surface of the first substrate 200 and between the first and second substrates 200 and 210, the difference from FIG. 1A is that the first substrate 200 is a color-changing substrate, such as containing reactive photochromic spiroxazine (spirooxazine) substrates, substrates containing inorganic color-changing materials (such as WO ₃ ), etc., so that the light source L of the organic electroluminescent device 202 travels through the first substrate 200 . In other embodiments, the organic electroluminescent device 202 can be a top-emitting organic electroluminescent diode, and the second substrate 210 is a color-changing substrate, so that the light source L of the organic electroluminescent device 202 passes through the second substrate 210, as shown in FIG. 2B organic electroluminescent display device 21 is shown.

Next, please refer to FIG. 2C , which shows a double-sided display organic electroluminescence display device 22 according to an embodiment of the present invention, wherein the same components as those in FIG. 2A or 2B use the same reference numerals. In this embodiment, the double-sided organic electroluminescent display device 22 includes: a first substrate 200 , a second substrate 210 and organic electroluminescent devices 202 and 204 . The organic electroluminescent devices 202 and 204 are disposed on the upper surfaces of the first substrate 200 and the second substrate 210 respectively, and the organic electroluminescent devices 202 and 204 are interposed between the first substrate 200 and the second substrate 210 . In this embodiment, both the first substrate 200 and the second substrate 210 are color-changing substrates, and the organic electroluminescent devices 202 and 204 are bottom-emitting organic electroluminescent diodes, so that the light sources L of the organic electroluminescent devices 202 and 204 passing through the first substrate 200 and the second substrate 210 respectively.

Similarly, the organic electroluminescent display devices 20, 21 and 22 according to the embodiments of FIGS. 2A to 2C also have the advantages described in the organic electroluminescent display devices 10, 11 and 12 of FIGS. 1A to 1C, which are not described here. be repeated.

Next, please refer to FIG. 3 , which shows a schematic block diagram of an organic electroluminescent display device 40 with active contrast compensation according to an embodiment of the present invention. Here, the organic electroluminescent display device 40 can use a photochromic film or a photochromic substrate, as shown in the organic electroluminescent display device of FIG. 1A, 1B, 1C, 2A, 2B or 2C, and also includes: at least one driver The circuit 30 , at least one light detection device 32 and a control unit 34 . The driving circuit 30 is coupled to the at least one organic electroluminescent device 36 to drive the organic electroluminescent device 36 . Here, the organic electroluminescent device 36 can be a top-emitting or bottom-emitting organic electroluminescent diode, depending on the location of the photochromic film/substrate, so that the light source of the organic electroluminescent diode can pass through the photochromic film / Substrate. The light detecting device 32 is used for detecting the intensity of external light. The control unit 34 is coupled between the driving circuit 30 and the light detection device 32 to control the driving circuit 30 according to the intensity of the ambient light detected by the light detection device 32 . For example, when the organic electroluminescent display device 40 is used indoors, the intensity of the external light detected by the light detection device 32 is weak, so the brightness of the organic electroluminescent device 36 can be lowered by the driving circuit 30 to save energy. power and extend the lifetime of the organic electroluminescent device 36. On the other hand, when the organic electroluminescent display device 40 is used outdoors, the intensity of the external light detected by the light detection device 32 is relatively strong, so the brightness of the organic electroluminescent device 36 can be adjusted through the driving circuit 30, and at the same time cooperate with The photochromic film/substrate reduces the reflection of strong external light, and compensates for the contrast, presenting an optimal contrast ratio (CR).

Compared with the prior art using a polarizing film, the organic electroluminescent display device of the present invention can use relatively low brightness to drive the organic electroluminescent display device because the photochromic film/substrate is transparent when used indoors. device to save its power and prolong its life. Furthermore, when used outdoors, in addition to achieving the function of the polarizing film through the photochromic film/substrate, since the transmittance of the photochromic film/substrate is higher than that of the polarizing film, relatively low brightness can also be used to drive active Electromechanical excitation of light-emitting devices saves their power and extends their life. In addition, the organic electroluminescent display device of the present invention can dynamically adjust the brightness of the organic electroluminescent device through the light detection device and the control unit to perform contrast compensation and present a preferred contrast ratio (CR).

Although the present invention is disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art can make some changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention It shall prevail as defined in the appended claims.

Claims (10)

1. An organic electroluminescent display device, comprising: a first and a second substrate, the first and the second substrate are arranged parallel to each other; a first organic electroluminescent device disposed on the first substrate and between the first and the second substrate; and A first photochromic film is arranged on the first or the second substrate, so that the light source of the first organic electroluminescent device passes through the first photochromic film. 2. The organic electroluminescent display device according to claim 1, further comprising a second organic electroluminescent device disposed on the second substrate and between the first and the second substrate, wherein the The traveling direction of the light source of the first organic electroluminescent device is opposite to that of the second organic electroluminescent device. 3. The organic electroluminescence display device according to claim 2, further comprising a second photochromic film disposed on the first or the second substrate not provided with the first photochromic film, so that the first photochromic film The light sources of the two organic electroluminescent devices pass through the second photochromic film. 4. The organic electroluminescence display device according to claim 3, further comprising: at least one driving circuit, coupled to the first and the second organic electroluminescent device, to drive the first and the second organic electroluminescent device; At least one light detection device, used to detect the intensity of external light; and A control unit, coupled between the driving circuit and the light detection device, controls the driving circuit according to the intensity of the external light detected by the light detection device. 5. The organic electroluminescent display device according to claim 1, further comprising: a driving circuit, coupled to the first organic electroluminescent device, to drive the first organic electroluminescent device; a light detection device for detecting the intensity of external light; and A control unit, coupled between the driving circuit and the light detection device, controls the driving circuit according to the intensity of the external light detected by the light detection device. 6. An organic electroluminescence display device, comprising: a first and a second substrate, the first and the second substrate are arranged parallel to each other; and A first organic electroluminescent device, disposed on the first substrate and between the first and the second substrate; Wherein one of the first and the second substrate is a color-changing substrate, so that the light source of the first organic electroluminescent device passes through the color-changing substrate. 7. The organic electroluminescent display device according to claim 6, further comprising a second organic electroluminescent device disposed on the second substrate and between the first and the second substrate, wherein the The traveling direction of the light source of the first organic electroluminescent device is opposite to that of the second organic electroluminescent device. 8. The organic electroluminescent display device as claimed in claim 7, wherein both the first and the second substrates are color-changing substrates, so that the light sources of the first and second organic electroluminescent devices respectively pass through the corresponding Some color-changing substrates. 9. The organic electroluminescence display device according to claim 8, further comprising: at least one driving circuit, coupled to the first and the second organic electroluminescent device, to drive the first and the second organic electroluminescent device; At least one light detection device, used to detect the intensity of external light; and A control unit, coupled between the driving circuit and the light detection device, controls the driving circuit according to the intensity of the external light detected by the light detection device. 10. The organic electroluminescence display device according to claim 6, further comprising: a driving circuit, coupled to the first organic electroluminescent device, to drive the first organic electroluminescent device; a light detection device for detecting the intensity of external light; and A control unit, coupled between the driving circuit and the light detection device, controls the driving circuit according to the intensity of the external light detected by the light detection device.

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