KR101947495B1 - Flexible display device - Google Patents

Abstract

The flexible display device of the present invention further comprises an amorphous silicon thin film having a good laser absorption rate on the plastic substrate during ID marking of the panel using the plastic substrate to minimize the laser energy transmitted to the plastic substrate, An active area in which sub pixels are arranged in a matrix form to implement an image; And an ID marking pad provided on an outer side of the active area and indicating production related information, wherein the ID marking pad is formed on a plastic substrate in order, and the thin film transistor And an amorphous silicon thin film and a metal film.

Description

[0001] FLEXIBLE DISPLAY DEVICE [0002]

The present invention relates to a flexible display device, and more particularly, to a flexible display device using a plastic substrate.

In recent information society, the importance of display devices as visual information delivery media is getting more emphasized, and in order to take a major position in the future, it is necessary to meet requirements such as low power consumption, thinning, light weight, and high image quality.

The display device may include a cathode ray tube (CRT), an electroluminescence (EL), a light emitting diode (LED), a vacuum fluorescent display (VFD) A liquid crystal display (LCD), such as an organic light emitting display (OLED), a field emission display (FED), and a plasma display panel (PDP) ), Which can not emit light itself.

On the other hand, a flexible display device which is not damaged even if the display device is folded or rolled is expected to become a new technology in the display device field. Currently, various obstacles exist in the implementation of flexible display devices, but thin film transistor liquid crystal display devices and organic light emitting display devices will become mainstream along with technology development.

Hereinafter, the flexible display device will be described in detail with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing a typical flexible display device including an ID marking area. Fig.

The flexible display device is called a scroll display device. It is implemented in a thin substrate such as plastic and is not damaged even when folded or rolled like paper. It is one of the next generation display devices. Currently, The light emitting display is promising.

The liquid crystal display device is an apparatus for displaying an image using the optical anisotropy of a liquid crystal. Since it has excellent visibility and average power consumption as compared with conventional CRTs, it is smaller than CRTs with the same screen size, And is spotlighted as a display device.

Since the organic light emitting display device itself emits light by itself, visibility is good even when a dark place or external light enters, and since the response speed, which is an important criterion for judging the performance of a mobile display device, is fast among existing display devices, Video can be implemented. In addition, the organic light emitting display device can be slimmed in various mobile devices such as a mobile phone because the OLED display has an ultra-thin design.

In order to realize such a flexible display device, it is necessary to secure the flexibility of the substrate. Currently, plastic or stainless steel (SUS) flexible substrate is used instead of the conventional glass substrate in order to secure the flexibility of the substrate.

1, the panel 1 of the flexible display device is provided with an ID for indicating the production-related information of the panel 1 in an outer area of an active area AA for implementing an image, There is a marking portion MA.

A laser marking apparatus is generally used for patterning an ID marking pad for history management of the panel 1 in a display device process including the above-described organic light emitting display device or other semiconductor process.

Here, the ID marking pad is generally composed of a combination of characters and / or numbers indicating the production related information.

FIG. 2 is a schematic cross-sectional view of an ID marking pad in the general flexible display device shown in FIG. 1. FIG.

As shown in the figure, the ID marking pad includes a metal film 30 in a cross-sectional structure, and is formed by inserting characters into the metal film 30 using a laser during the process.

As described above, the ID marking pad has a metal film 30 for laser engraving characters on the substrate 11. At this time, inorganic films 12 and 15 for transmitting light are formed on the metal film 30 .

In order to implement the flexible display device, the substrate 11 is used as the plastic substrate 11, and an auxiliary substrate 10 made of a glass for the progress of the process is attached to the bottom of the substrate 11. At this time, after the process is completed, the plastic substrate 11 is separated from the auxiliary substrate 10 to realize the flexible characteristic.

At this time, when characters are inscribed in the metal film 30 by laser to pattern the ID marking pad in the flexible display device, there is a laser absorbed in the plastic substrate 11, ) Is subject to burning.

As a result, a marking recognition error occurs in the process of reading the production information by reading the ID marking unit during the process.

3A and 3B are photographs showing, for example, an image and a microscope image of a damaged ID marking pad in the general flexible display device shown in FIG.

3A and 3B show a laser marking defective image. Particularly, FIG. 3A shows a read error screen, and FIG. 3B shows a microscope image of a damaged ID marking pad.

It is an object of the present invention to provide a flexible display device which prevents damage to a plastic substrate caused by ID marking of a panel using a plastic substrate.

Other objects and features of the present invention will be described in the following description of the invention and the claims.

According to an aspect of the present invention, there is provided a flexible display device including: an active area in which sub pixels are arranged in a matrix to implement an image; And an ID marking pad provided on an outer side of the active area and indicating production related information, wherein the ID marking pad is formed on a plastic substrate in order, and the thin film transistor And an amorphous silicon thin film and a metal film.

In this case, the plastic substrate is formed of polyimide (PI).

The ID marking pad is characterized in that second and first inorganic films, which transmit light, are formed on the metal film and the lower metal film, respectively.

In this case, the amorphous silicon thin film is formed between the first inorganic film and the metal film.

And the first inorganic film of the ID marking pad is formed of a buffer film of the active region.

And the amorphous silicon thin film of the ID marking pad is formed of an amorphous silicon thin film constituting an active layer of the active region.

And the metal film of the ID marking pad is composed of a gate electrode and a source / drain electrode of the active region.

And the second inorganic film of the ID marking pad is made of an interlayer insulating film, a protective film or a planarizing film of the active region.

As described above, the flexible display device according to the present invention further comprises an amorphous silicon thin film having a good absorption rate of laser in the ID marking of the panel using the plastic substrate to minimize the laser energy transmitted to the plastic substrate Whereby the damage of the plastic substrate by the laser can be prevented.

Accordingly, it is possible to prevent the marking recognition error, thereby improving the yield and enhancing the price competitiveness.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an exemplary view showing a general flexible display device including an ID marking portion. Fig.
FIG. 2 is a schematic view of a cross section of an ID marking pad in the general flexible display device shown in FIG. 1; FIG.
FIGS. 3A and 3B illustrate an image and a microscope image of a damaged ID marking pad in the general flexible display device shown in FIG. 1. FIG.
4 is a view exemplarily showing a flexible display device according to an embodiment of the present invention including an ID marking portion.
FIG. 5 schematically shows a cross section of an ID marking pad in the flexible display device according to the embodiment of the present invention shown in FIG. 4; FIG.
FIG. 6 is a photograph showing an image of an ID marking pad, for example, in the flexible display device according to the embodiment of the present invention shown in FIG.
7 is a graph showing laser transmittance according to presence or absence of an amorphous silicon thin film.
8 is a cross-sectional view schematically showing a part of a structure of a flexible organic light emitting display according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the flexible display device according to the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Fig. 4 is a view exemplarily showing a flexible display device according to an embodiment of the present invention including an ID marking unit.

5 is a schematic cross-sectional view of the ID marking pad of the flexible display device according to the embodiment of the present invention shown in FIG.

As shown in FIG. 4, the panel 101 of the flexible display device according to the embodiment of the present invention includes an ID for marking the production-related information of the panel 101 in the outer area of the active area AA, There is a marking portion MA.

A laser marking apparatus may be used to pattern the ID marking pad for history management of the panel 101 in a display device process including the above-described organic light emitting display device or other semiconductor process. In order to pattern the ID marking pad, the process line may be composed of the cleaning area, the laser marking, and the photo area in this order, but the present invention is not limited thereto.

Here, the ID marking pad may be composed of a combination of letters and / or numbers indicating corresponding production related information.

As shown in FIG. 5, the ID marking pad includes a metal film 130 in a cross-sectional structure, and may be formed by inserting characters into the metal film 130 using a laser during the process .

As described above, the ID marking pad has a metal film 130 for laser engraving characters on the substrate 111. At this time, the inorganic markers 112 and 115, which transmit light, .

At this time, a plastic substrate 111 such as polyimide (PI) is used as the substrate 111 in order to implement the flexible display device, and an auxiliary substrate 110 made of a glass for processing progress is formed under the substrate 111 . At this time, after the process is completed, the plastic substrate 111 is separated from the auxiliary substrate 110 to realize the flexible characteristic.

On the other hand, burning occurs in the plastic substrate 111 during the laser irradiation for patterning the ID marking pad because a part of the laser reaches the plastic substrate 111 to absorb the laser energy to the plastic substrate 111 .

Therefore, in order to prevent this, in the embodiment of the present invention, an amorphous silicon thin film 120 having a high laser absorption rate is added between the plastic substrate 111 and the metal film 130, And the energy of the laser transmitted to the substrate 111 is minimized.

However, the present invention is not limited to the amorphous silicon thin film 120, and another thin film having a good laser absorption rate may be applied. 5 illustrates an example in which the amorphous silicon thin film 120 according to an embodiment of the present invention is formed between the first inorganic film 120 and the metal film 130 on the plastic substrate 111 However, the present invention is not limited thereto. The amorphous silicon thin film 120 according to the embodiment of the present invention may be formed between the plastic substrate 111 and the first inorganic film 120.

FIG. 6 is a photograph showing an image of the ID marking pad in the flexible display device according to the embodiment of the present invention shown in FIG.

As shown in the figure, the ID marking pad according to the embodiment of the present invention improves the defective laser marking as the amorphous silicon thin film is formed between the plastic substrate and the metal film to absorb laser energy.

FIG. 7 is a graph showing the laser transmittance according to the presence or absence of the amorphous silicon thin film, and shows the laser transmittance to the laser energy wavelength.

Referring to FIG. 7, in the case where the amorphous silicon thin film is not present for a laser having a wavelength of 400 nm or more (Comparative Example), more laser is transmitted than in the case where the amorphous silicon thin film exists .

For example, for a laser with a wavelength of 532 nm, about 77% of the laser is transmitted when the amorphous silicon thin film is not present, whereas about 34% is transmitted when the amorphous silicon thin film is present It can be seen that the amorphous silicon thin film plays a role of absorbing the laser.

Meanwhile, the ID marking pad according to the embodiment of the present invention can be formed at the time of TFT formation in the active area of the panel, which will be described in detail with reference to the drawings.

First, the panel may be configured as one of a liquid crystal display device and an organic light emitting display device.

Although not shown, when the panel is constituted by a liquid crystal display device, for example, an upper polarizer plate having a light absorption axis in the horizontal direction is disposed on the panel. Further, a backlight unit is disposed under the panel, and a lower polarizer plate is disposed between the panel and the backlight unit.

When the panel is constituted by a liquid crystal display device, the panel may be composed of two substrates and a liquid crystal layer formed therebetween.

At this time, a thin film transistor array is formed on the lower substrate. The thin film transistor array includes a plurality of data lines to which R, G, and B data voltages are supplied, a plurality of gate lines to which gate pulses are supplied to cross the data lines, A plurality of pixel electrodes for charging a data voltage to the liquid crystal cells, and a storage capacitor connected to the pixel electrode to maintain the voltage of the liquid crystal cell. A color filter array is formed on the upper substrate, and the color filter array includes a black matrix, a color filter, and the like.

8 is a cross-sectional view schematically showing a part of a structure of a flexible organic light emitting display according to an embodiment of the present invention.

When the panel is configured as an organic light emitting display, sub pixels are arranged in a matrix in an active area for implementing an image, and a scan driver and a data driver for driving sub-pixels outside the active area Located.

At this time, the sub-pixel includes an organic light emitting diode (OLED) and a driving circuit. Referring to FIG. 8, the organic light emitting diode OLED includes a first electrode 118, an organic compound layer 119, and a second electrode 108.

The organic compound layer 119 may further include various organic layers for efficiently transporting a hole or an electron carrier to a light emitting layer, in addition to a light emitting layer for actually emitting light. The organic layers include a hole injection layer and a hole transport layer located between the first electrode 118 and the light emitting layer, a second electrode 108 and an electron injection layer injection layer and an electron transport layer.

The driving circuit portion includes at least two thin film transistors and at least one storage capacitor. The thin film transistor basically includes a switching transistor (not shown) and a driving transistor (TFT).

The switching transistor is connected to the scan line and the data line and transmits a data voltage input to the data line to the driving transistor according to a switching voltage input to the scan line. The storage capacitor is connected to the switching transistor and the power supply line, and stores a voltage corresponding to a difference between a voltage received from the switching transistor and a voltage supplied to the power supply line.

The driving transistor TFT is connected to the power supply line and the storage capacitor to supply an output current proportional to the square of the difference between the voltage stored in the storage capacitor and the threshold voltage to the organic light emitting diode OLED, And emits light by current. The driving transistor TFT includes a gate electrode 121, a source electrode 123 and a drain electrode 122. The first electrode 118 of the organic light emitting diode OLED is connected to the drain electrode (Not shown).

However, the structure of such a sub-pixel is not limited to the above-described example and can be variously modified.

As described above, the OLED display device includes a substrate 111 made of plastic or stainless steel, and a first electrode 118 made of transparent oxide is formed on the first electrode 118. A hole transport layer, a light emitting layer, An organic compound layer 119 composed of an electron transporting layer, an electron injecting layer, and a second electrode 108 which is a cathode are stacked.

Based on the above structure, the organic electroluminescent device is configured such that the holes injected from the first electrode 118 and the electrons injected from the second electrode 108 are coupled to each other in the light emitting layer via the transport layer for transport, And generates light having a wavelength corresponding to an energy difference in the light emitting layer.

At this time, the light emitting layer may more specifically include a red light emitting layer, a green light emitting layer, and a blue light emitting layer in order to emit white light.

In the organic light emitting display having the above structure, for example, when forming the buffer film 112 in the active region, a first inorganic film of the ID marking pad is formed, and an active layer 124 is formed in the active region The amorphous silicon thin film of the ID marking pad can be formed.

A metal film of the ID marking pad is formed when the gate electrode 121 and the source and drain electrodes 123 and 122 are formed in the active region and the interlayer insulating film 114, The second inorganic film of the ID marking pad can be formed when the planarizing film 116 is formed.

For reference, reference numerals 113 and 117 denote a gate insulating film and a pixel defining film, respectively.

While a great many are described in the foregoing description, it should be construed as an example of preferred embodiments rather than limiting the scope of the invention. Therefore, the invention should not be construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

110: auxiliary substrate 111: plastic substrate
112, 115: inorganic film 120: amorphous silicon thin film
130: metal film AA: active region
MA: ID marking unit

Claims (8)

An active area in which sub pixels are arranged in a matrix to implement an image; And
And an ID marking pad provided at an outer portion of the active area,
The ID marking pad includes:
A first inorganic film, an amorphous silicon thin film, a metal film, and a second inorganic film sequentially formed on the plastic substrate with the constituent elements of the thin film transistor in the sub-pixel,
The metal film has production-related information,
Wherein the amorphous silicon thin film absorbs a laser to minimize the energy of a laser transmitted to the plastic substrate. The flexible display device according to claim 1, wherein the plastic substrate is made of polyimide (PI). The flexible display device according to claim 1, wherein the first and second inorganic films transmit light on and below the metal film. delete The flexible display device according to claim 3, wherein the first inorganic film of the ID marking pad comprises a buffer film of the active region. The flexible display device according to claim 3, wherein the amorphous silicon thin film of the ID marking pad comprises an amorphous silicon thin film constituting an active layer of the active region. The flexible display device according to claim 3, wherein the metal film of the ID marking pad comprises a gate electrode and a source / drain electrode of the active region. The flexible display device according to claim 3, wherein the second inorganic film of the ID marking pad is formed of an interlayer insulating film, a protective film or a planarizing film of the active region.

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