JP2008216622A - Manufacturing method of display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a display device which is easily installed on a curved surface having a constant radius of curvature. <P>SOLUTION: Thicknesses, elastic moduli, and coefficients of thermal expansion of a glass substrate 17 and a back substrate 15 and a heating temperature at which the glass substrate 17 and back substrate 15 are heated to be joined together are set according to a desired radius of curvature on the basis of the relation among the respective thicknesses, elastic moduli, and coefficients of thermal expansion of the glass substrate 17 and back substrate 15, and the heating temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a method of manufacturing a display device such as a liquid crystal display device, an organic electroluminescence display device, an electrophoretic display device, and the like. Specifically, a glass substrate on which a pixel electrode wiring layer for driving a display layer is formed is provided. The present invention relates to a method for manufacturing a display device bonded to a back substrate.

Conventionally, as this type of display device, there is an electrophoretic display type as shown in FIG. The display device 50 includes a back electrode substrate 51, a front electrode substrate 52 facing the back electrode substrate 51, and an electrophoretic display disposed between the back electrode substrate 51 and the front electrode substrate 52. Layer 53. The back-side electrode substrate 51 is configured by bonding a back substrate 56 to a glass substrate 55 having a semiconductor circuit layer 54 formed on one surface. The front electrode substrate 52 is configured by forming a transparent common electrode 58 on a transparent substrate 57. The electrophoretic display layer 53 is configured by fixing a number of microcapsules 59 with a binder 60. In the display device 50, the glass substrate 55 is formed to be approximately the same size as the back substrate 56, and the periphery of the glass substrate 55 and the periphery of the back substrate 56 are at approximately the same position.

In the electrophoretic display device, components other than the glass substrate 55 are made of an organic material. For this reason, if a synthetic resin or metal substrate is used instead of the glass substrate 55, a flexible display device can be realized as electronic paper. However, when the active matrix driving method is used to display high-definition and high-definition images by dot-matrix display, it is softened to form thin film transistors that require a high-temperature generation process. A quartz glass or heat-resistant glass substrate having a high point and melting point and high rigidity is required. Therefore, after all, it has not been possible to realize a display device with high flexibility.

In order to solve such problems, the development of a method of transferring a thin film transistor once formed on a glass substrate onto a resin substrate and a method of directly forming a thin film transistor on a flexible resin substrate by a low temperature process are proceeding. However, none of them are in the practical stage yet.

Therefore, the glass substrate 55 is processed in a thickness of, for example, 200 μm or less and used in a state where a certain degree of flexibility is given (for example, Patent Document 1). Thus, the display device 50
A certain degree of flexibility is imparted.
JP 2006-41135 A

By the way, it is conceivable to install a thin display device along a circumferential surface of a cylinder, for example. In such a case, it is necessary to bend the display device in accordance with the curvature radius of the cylinder using its flexibility. However, a flat display device made of a glass substrate or the like as shown in FIG. 7 tries to return to its original state by elasticity even if it is curved. For this reason, it is necessary to fix the display device in a curved state having a repulsive force in the restoring direction, and for example, it is not easy to install the display device on the circumferential surface of a cylinder.

The present invention has been made paying attention to such problems existing in the prior art.
The object is to provide a method of manufacturing a display device that can be easily installed on a curved surface having a predetermined radius of curvature.

In order to achieve the above object, the present invention provides a method of manufacturing a display device in which a pixel electrode wiring layer for driving a display layer is formed on a glass substrate, and the glass substrate and the back substrate are heated and bonded. The relationship between the thickness of each of the glass substrate and the back substrate, the elastic modulus and the coefficient of thermal expansion, the heating temperature when the glass substrate and the back substrate are joined by heating, and the radius of curvature of both the joined substrates Based on the above, the thickness, elastic modulus and thermal expansion coefficient of each substrate and the heating temperature are set according to a desired radius of curvature.

According to this configuration, the thickness, elastic modulus, and thermal expansion coefficient of the glass substrate and the back substrate and the heating (firing) temperature when the glass substrate and the back substrate are joined by heating (firing) are joined. In addition, a display device curved with a desired curvature radius is created by presetting the curvature (warpage) generated on both the substrates in accordance with the curvature radius at a predetermined substrate temperature. Therefore, since it is not necessary to bend the display device in accordance with the curvature radius of the curved surface on which the display device is to be installed, installation on a curved surface having a predetermined curvature radius is facilitated.

The present invention also includes the thicknesses of the glass substrate and the back substrate, the elastic modulus and the thermal expansion coefficient,
The relationship between the heating temperature when heating and bonding the glass substrate and the back substrate and the radius of curvature of both bonded substrates is that the thickness of the glass substrate is a1, the elastic modulus of the glass substrate is E1, and the glass substrate The thermal expansion coefficient is α1, the back substrate thickness is a2, the back substrate elastic modulus is E2, the back substrate thermal expansion coefficient is α2, the heating temperature is T1, the substrate temperature is T0, the radius of curvature is ρ, and h = A1
+ A2, m = a1 / a2, n = E1 / E2,

となるようにすることを特徴とする。

It is characterized by becoming.

In addition, the present invention is characterized in that the display layer is composed of electrophoretic particles and an electrophoretic dispersion medium in which the electrophoretic particles are dispersed.
Further, the present invention is characterized in that a pixel electrode wiring layer is formed on the glass substrate, and then the glass substrate is thinned to a predetermined thickness, and then the glass substrate is pasted on the back substrate.

In addition, the present invention is characterized in that the back substrate and the glass substrate are pressed and bonded together while being heated to a predetermined temperature.
Further, the present invention forms a transparent common electrode layer on a transparent substrate, and then forms the display layer on the transparent common electrode layer, and then joins the pixel electrode wiring layers of the back substrate and the glass substrate. The transparent substrate is stuck on the top.

Further, the present invention is characterized in that the back substrate, the glass substrate, and the transparent substrate are pressed and bonded in a state of being heated to a predetermined temperature.

According to the present invention, it is possible to manufacture a display device that can be easily installed on a curved surface having a certain radius of curvature.

Next, an embodiment in which the present invention is embodied in an electrophoretic display type display device will be described with reference to FIG.
Description will be given with reference to FIG.
As shown in FIG. 1, the display device 11 of this embodiment includes a back-side electrode substrate 12, a front-side electrode substrate 13 facing the back-side electrode substrate 12, and the back-side electrode substrate 12 and the front-side electrode substrate 13. And an electrophoretic display layer (hereinafter simply referred to as a display layer) 14 sandwiched between them.

The back-side electrode substrate 12 is configured by bonding a flexible back substrate 15 and a glass substrate 17 on which a semiconductor circuit layer 16 as a pixel electrode wiring layer is formed via an adhesive layer 18. . The semiconductor circuit layer 16 is configured by a plurality of pixel electrodes, a pixel driving circuit, wirings, and the like arranged in the row direction and the column direction, and the pixel driving circuit is configured by a thin film transistor (TFT). Each pixel drive circuit is connected to an external drive circuit via a row decoder and a column decoder (not shown). The back substrate 15 is made of a thermoplastic resin or thermosetting resin material excellent in flexibility, elasticity, etc., for example, polyethylene terephthalate, polycarbonate, polyimide, polyethylene, a mixture containing an epoxy-based cross-linking resin and an inorganic substance, and the like. It is formed in a thickness range of 300 μm or less. The glass substrate 17 is made of glass having a high softening point and melting point such as alkali-free glass, quartz glass, soda glass, heat-resistant glass, etc.
The thickness is 50 μm or more and 200 μm or less. Furthermore, the adhesive layer 18 is
It is provided in a thickness range of 5 μm or more and 10 μm or less by an epoxy resin or an acrylic resin.

The front-side electrode substrate 13 includes a transparent substrate 19 having flexibility, and a transparent common electrode layer 20 is formed on the lower surface thereof. The transparent substrate 19 is formed of a thermoplastic resin or a thermosetting resin material excellent in transparency and flexibility, for example, polyethylene terephthalate, polycarbonate, polyimide, polyethylene, and the like. The transparent common electrode layer 20 is formed of an electronically conductive polymer such as indium tin oxide or polyaniline.

The display layer 14 includes a large number of microcapsules 22 integrated with a binder 21 such as aliphatic acrylate. An electrophoretic dispersion medium 23 and electrophoretic particles 24 are enclosed in the microcapsule 22. The electrophoretic particles 24 migrate in the electrophoretic dispersion medium 23 according to the direction of the electric field applied to the microcapsules 22. The microcapsules 22 are made of, for example, gum arabic / gelatin compounds, urethane compounds, or the like. The electrophoretic dispersion medium 23 is made of, for example, water, methanol, ethanol, or the like, and the electrophoretic particles 24 are made of, for example, aniline black, carbon black, titanium dioxide, or the like.

The display device 11 has a form that is curved (that is, warped) into a cylindrical surface with the front electrode substrate 13 side convex. That is, the display device 11 is curved with a predetermined radius of curvature.

Next, the manufacturing method of this embodiment configured as described above will be described with reference to FIGS.
First, before actually manufacturing the display device 11, the radius of curvature of the display device 11 to be manufactured is determined to be a desired allowable value. And the conditions for producing the display apparatus 11 of the curvature radius are set using following Formula (1). This condition is the following element that determines the desired radius of curvature ρ. That is, this element includes the thickness a1, the elastic modulus E1, and the thermal expansion coefficient α1 of the glass substrate 17, the thickness a2, the elastic modulus E2, and the thermal expansion coefficient α2 of the back substrate 15, and the back substrate 15 and the glass bonded together. Heating temperature (firing temperature) when heating (firing) the substrate 17
It consists of T1.

ここで、ｈ＝ａ１＋ａ２、ｍ＝ａ１／ａ２、ｎ＝Ｅ１／Ｅ２であり、Ｔ０は基板温度で
ある。なお、基板温度Ｔ０は、所定の雰囲気温度下に一定時間以上放置されたときの背面
基板１５及びガラス基板１７の温度であって、そのときの雰囲気温度と同じ温度である。

Here, h = a1 + a2, m = a1 / a2, n = E1 / E2, and T0 is the substrate temperature. The substrate temperature T0 is the temperature of the back substrate 15 and the glass substrate 17 when left at a predetermined atmospheric temperature for a predetermined time or more, and is the same temperature as the atmospheric temperature at that time.

That is, the radius of curvature ρ of the display device 11 formed at a predetermined substrate temperature T0 is the thickness a1, a2 of each of the glass substrate 17 and the back substrate 15 bonded via the adhesive layer 18, the elastic modulus E1, E2, and The thermal expansion coefficients α1 and α2 and the heating temperature T1 at the time of joining the two substrates 15 and 17 have a relationship represented by the formula (1). Here, since the thickness of the adhesive layer 18 is relatively sufficiently thin as compared with the back substrate 15 and the glass substrate 17, the contribution of the mechanical negative surface of the adhesive layer 18 to the curvature (warp) of the display device 11. Is almost negligible. Further, since the elastic modulus of the front electrode substrate 13 and the display layer 14 is sufficiently smaller than that of the rear substrate 15 and the glass substrate 17, the contribution of the mechanical negative surface to the curvature of the display device 11 is almost ignored. it can. Therefore, each thickness a1, a2 of the glass substrate 17 and the back substrate 15 and the elastic modulus E1,
A display device having a desired radius of curvature ρ by setting E2 and thermal expansion coefficients α1 and α2 and the heating temperature T1 of both substrates 15 and 17 according to the radius of curvature ρ of the display device 11 to be manufactured. 11 can be produced.

Next, in order to produce the back-side electrode substrate 12, the adhesive layer 1 is applied to one surface of the back substrate 15.
The adhesive film (adhesive material) for forming 8 is stuck by a roll laminator, for example. Further, as shown in FIG. 3, on the glass substrate 17, for example, vacuum deposition, sputtering,
The semiconductor circuit layer 16 is formed by chemical vapor deposition (CVD) or the like, and then the semiconductor circuit layer 16
The glass substrate 17 on which is formed is thinned to, for example, 100 μm by wet etching.

Next, as shown in FIG. 4, the glass substrate 17 is placed on the adhesive film 25 on the back substrate 15.
Paste. At this time, for example, using a roll laminator, the back substrate 15 and the glass substrate 17 are pressed and bonded together while being heated to, for example, 100 ° C. Adhesive film 2
Instead of using 5, the surface of the back substrate 15 may be melted by heating, and the glass substrate 17 may be directly bonded to the molten surface.

Next, the back substrate 15 and the glass substrate 17 bonded together through the adhesive film are put in an oven and heated (baked) for 1 hour at a heating temperature T1 of 120 ° C., for example, and then cooled at room temperature. In this step, the adhesive film 25 is once melted by heating, and then the adhesive is cured by cooling to form the adhesive layer 18. The back substrate 15 and the glass substrate 17 are bonded by the adhesive layer 18. As a result, the joined back substrate 15 and glass substrate 17 have a predetermined curvature based on the differences between the thicknesses a1 and a2, the elastic moduli E1 and E2, and the thermal expansion coefficients α1 and α2, and the heating temperature T1. It bends itself and is fixed in its curved state.

On the other hand, in order to produce the front electrode substrate 13, the transparent common electrode layer 20 is formed on one surface of the transparent substrate 19 by, for example, sputtering.
Next, the microcapsule 22 and the binder 21 are formed on the transparent common electrode layer 20 of the transparent substrate 19.
The transparent substrate 19 to which the mixed solution is applied is dried at a predetermined temperature for a predetermined time to form the display layer 14 on the transparent common electrode layer 20.

Finally, as shown in FIG. 5, the display layer 14 is formed on the semiconductor circuit layer 16 of the back-side electrode substrate 12.
The front-side electrode substrate 13 on which is formed is affixed. At this time, for example, using a roll laminator, the back side electrode substrate 12 and the front side electrode substrate 13 are heated to, for example, 100 ° C., and the back side electrode substrate 12 is pressed and bonded in a state of extending in a planar shape.

The display device 11 is manufactured through the above steps. The display device 11 includes a glass substrate 17.
And each thickness a1, a2, elastic modulus E1, E2 and thermal expansion coefficient α1, α2 of the back substrate 15,
From the heating temperature T1 when heating the bonded back substrate 15 and glass substrate 17,
It has a radius of curvature ρ determined according to the equation (1). As shown in FIG. 2, the display device 11 has a warp amount W obtained by the following equation (2) according to its length L.

以上のように製造されたこの実施形態は、以下の効果を有する。

This embodiment manufactured as described above has the following effects.

(1) Since the display device 11 curved with the same radius of curvature ρ as the radius of curvature of the outer periphery of the cylinder on which the display device 11 is to be installed can be manufactured, the display device 11 after manufacture is different from the conventional display device. Can be easily installed along the circumferential surface of the cylinder without forcibly bending.

(2) By setting each thickness a1, a2, elastic modulus E1, E2 and thermal expansion coefficient α1, α2 of the glass substrate 17 and the back substrate 15, and a heating temperature T1 at the time of joining both the substrates 15, 17, There is no need to provide a special manufacturing process, that is, a manufacturing process in which a dynamic external force is applied to the display device 11, and the display device 11 curved with a desired curvature radius ρ can be obtained.

In addition, this embodiment can also be changed and embodied as follows.
As shown in FIG. 6, the present invention is embodied in a display device 11 that includes an electrophoretic display layer 14 that does not use a microcapsule 22. That is, this electrophoretic display layer 14
Is configured by filling an electrophoretic dispersion liquid composed of the electrophoretic dispersion medium 23 and the electrophoretic particles 24 into a large number of chambers 31 of a frame 30 formed on the back-side electrode substrate 12. The frame 30 is formed on the semiconductor circuit layer 16 of the back substrate 15 by photoresist or offset printing. In addition, the electrophoretic dispersion liquid can be produced by, for example, a frame 3 by a droplet discharge method (inkjet method).
Each of the zero chambers 31 is filled.

Instead of the semiconductor circuit layer 16, the present invention is embodied in the display device 11 provided with a circuit of a passive drive system configured by a plurality of electrodes and wiring for energizing each electrode.
The present invention is embodied in a display device including a particle rotation type particle display layer using a spherical twist ball, a magnetic twist ball, or a cylindrical twist ball.

Further, the present invention is embodied in a display device including a particle movement type particle display layer using a charged toner or an electronic powder fluid.
Further, the present invention is embodied in a display device including a magnetophoresis type or magneto-sensitive type electrophoretic particle display layer.

-The present invention is embodied in a display device including a liquid crystal display unit as a display layer.
-The present invention is embodied in a display device having an organic electroluminescence display section as a display layer.

The schematic longitudinal cross-sectional view which shows the display apparatus of one Embodiment. The schematic diagram of the display apparatus for demonstrating curvature. The longitudinal cross-sectional view which shows the manufacturing process of a display apparatus. The longitudinal cross-sectional view which shows the manufacturing process of a display apparatus. The longitudinal cross-sectional view which shows the manufacturing process of a display apparatus. The longitudinal cross-sectional view which shows the display apparatus of other embodiment. The longitudinal cross-sectional view which shows the conventional display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Display apparatus, 14 ... Electrophoretic display layer as a display layer, 15 ... Back substrate, 16 ... Semiconductor circuit layer as a pixel electrode wiring layer, 17 ... Glass substrate, 19 ... Transparent substrate, 20 ... Transparent common electrode layer, 23 ... electrophoretic dispersion medium, 24 ... electrophoretic particles, a1, a2 ... thickness, E1, E2 ...
Elastic modulus, T0: substrate temperature, T1: heating temperature, α1, α2: thermal expansion coefficient, ρ: radius of curvature.

Claims (7)

In a manufacturing method of a display device in which a pixel electrode wiring layer for driving a display layer is formed on a glass substrate, and the glass substrate and the back substrate are heated and bonded.
Based on the relationship between each thickness, elastic modulus and thermal expansion coefficient of the glass substrate and the back substrate, the heating temperature when the glass substrate and the back substrate are joined by heating, and the radius of curvature of the joined substrates. A method of manufacturing a display device, wherein the thickness, elastic modulus, thermal expansion coefficient, and heating temperature of each substrate are set according to a desired radius of curvature. The relationship between the thicknesses of the glass substrate and the back substrate, the modulus of elasticity and the thermal expansion coefficient, the heating temperature when the glass substrate and the back substrate are joined by heating, and the radius of curvature of both the joined substrates,
The thickness of the glass substrate is a1, the elastic modulus of the glass substrate is E1, the thermal expansion coefficient of the glass substrate is α1,
The thickness of the back substrate is a2, the elastic modulus of the back substrate is E2, the thermal expansion coefficient of the back substrate is α2, the heating temperature is T1, the substrate temperature is T0, the radius of curvature is ρ, and h = a1 + a2, m = a1 /
As a2, n = E1 / E2,

The method for manufacturing a display device according to claim 1, wherein: The method for manufacturing a display device according to claim 1, wherein the display layer includes electrophoretic particles and an electrophoretic dispersion medium in which the electrophoretic particles are dispersed. 4. A pixel electrode wiring layer is formed on the glass substrate, and then the glass substrate is thinned to a predetermined thickness, and then the glass substrate is attached to the rear substrate.
The manufacturing method of the display apparatus as described in any one of these. 5. The method for manufacturing a display device according to claim 4, wherein the back substrate and the glass substrate are pressed and bonded together while being heated to a predetermined temperature. A transparent common electrode layer is formed on the transparent substrate, and then the display layer is formed on the transparent common electrode layer, and then the transparent substrate is formed on the pixel electrode wiring layer of the bonded back substrate and glass substrate. The method for manufacturing a display device according to claim 4, wherein the display device is attached. The method for manufacturing a display device according to claim 6, wherein the back substrate, the glass substrate, and the transparent substrate are pressed and bonded while being heated to a predetermined temperature.

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