Production method for improving LCD (Liquid Crystal Display) lamination yellow spots

Abstract

The invention provides a fitting jig and a fitting method for improving LCD fitting yellow spots. The jig comprises an external platform, and the upper surface of the external platform comprises a continuous arc-shaped transition area and a plane area; the arc length of the arc-shaped transition area is less than 1 / 4 of a circle; the lowest point of the arc-shaped transition area is located on the outermost side of the externally-connected platform, and the highest point of the arc-shaped transition area is connected with the plane area. The curvature of any position of the arc-shaped transition area is smaller than the curvature of the attaching roller. OCA lamination is carried out by adopting the lamination jig, so that OCA indentation marks generated by the lamination roller at the initial position can be effectively avoided, and the problem of poor LCD lamination yellow spots at the initial position is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of liquid crystal display, in particular to a production method for improving LCD bonding yellow spot. BACKGROUND

[0002] In the prior art, due to the flowability of liquid crystal (LCD) material, when the surface of the liquid crystal panel is extruded by external force, the liquid crystal material inside the liquid crystal panel will appear uneven distribution or flow phenomenon, thereby causing display yellowing defect, which is called LCD yellow spot (MURA) in the industry.

[0003] The LCD yellow spot generation mechanism is as follows: due to the influence of the characteristics of the LCD liquid crystal, different LCD cell gap (box thickness) will have different transmittance for RGB three colors; when the LCD cell gap (box thickness) increases, the transmittance of blue light B will be significantly reduced, at this time the red light R and green light G will still maintain a certain transmittance, and the mixture of red light R and green light B is yellow light. The increase of the LCD cell gap (box thickness) leads to yellow spot; and the reason for the increase of the LCD cell gap is that the LCD display module is extruded by external force, so that the liquid crystal in the cell box gathers to the position around the extrusion, the cell gap (box thickness) at the position where the liquid crystal gathers is enlarged, and finally the LCD display module appears yellowing phenomenon.

[0004] As shown in Figure 6 , during the OCA bonding process, the starting position of the roller is located at the edge of the OCA, and since the starting position of the roller is not flat, stress exists, which is a common cause of LCD yellow spot. When the OCA is bonded from soft to hard, the starting position of the roller is prone to stop, which can cause uneven stress on the OCA, resulting in a concave corresponding to the roller at the starting position of the OCA, and the part of the concave will pull the LCD during the bonding and vacuumizing process, causing the cell gap (box thickness) to increase (similar to the effect of the suction nozzle). At this time, the transmittance of blue light B will be significantly reduced, but the transmittance of red light R and green light G will still maintain a certain transmittance, which finally leads to LCD bonding yellow spot.

[0005] In the process of bonding OCA from soft to hard, the starting position of the LCD bonding yellow spot can be reduced by formulating the best bonding pressure, bonding speed and bonding inclination angle of the roller, but the starting position of the LCD bonding yellow spot cannot be completely solved. SUMMARY

[0006] In view of the above problems, the present application provides a bonding jig for improving LCD bonding yellow spot, which comprises an external platform, and the upper surface of the external platform comprises a continuous arc-shaped transition area and a flat area; The arc length of the arc-shaped transition area is less than 1 / 4 of a circle; The lowest point of the arc-shaped transition zone is located at the outermost side of the outer platform, and the highest point of the arc-shaped transition zone is connected to the planar zone. The curvature of the arc-shaped transition zone at any point is less than the curvature of the roller.

[0007] Further, the bottom of the outer platform is connected to a base, and the base is used to support and fix the outer platform, and the base is a height-adjustable base; neither the outer platform nor the base interferes with the OCA and the cover plate.

[0008] Further, the height difference h of the arc-shaped transition zone is less than or equal to 20% of the thickness of the OCA.

[0009] The application also provides a production method for improving the bonding of the yellow spot of an LCD, which uses the bonding jig described above, and the steps are as follows: (1) Place the cover plate on the bonding platform, and set an outer platform outside the OCA bonding starting position: adjust the height and position of the base so that the lowest point of the arc-shaped transition zone is flush with the upper surface of the OCA, the outer platform does not directly contact the OCA, the horizontal distance a between the lowest point of the arc-shaped transition zone and the OCA bonding starting position is 0.2-0.5 mm, and the lower surface of the side of the outer platform close to the OCA is located above the cover plate; (2) Complete the bonding of the OCA and the cover plate by rolling the OCA with the bonding roller: the starting point of the bonding roller is located in the planar zone of the outer platform, the bonding roller travels from the planar zone to the arc-shaped transition zone, and then to the upper surface of the OCA, thereby completing the bonding of the OCA and the cover plate.

[0010] Further, in step (2), the bonding speed includes a bonding speed increasing stage and a bonding speed stable stage; the speed of the bonding speed increasing stage is 10-300 mm / s, and the speed of the bonding speed stable stage is 300 mm / s; before the bonding roller contacts the OCA, the bonding speed has reached the bonding speed stable stage.

[0011] Further, in step (2), the bonding inclination angle α formed by the OCA plane and the bonding platform is 5°-15°.

[0012] Further, in step (2), the roller pressure of the bonding roller is 100-300 KPa.

[0013] Further, in step (2), the diameter of the bonding roller is 20-25 mm.

[0014] Further, in step (2), the distance L between the starting point of the bonding roller and the edge of the OCA is greater than or equal to 50 mm.

[0015] Further, after the OCA and the cover plate are bonded, the OCA is bonded with an LCD to form a G-LCD; and the G-LCD is assembled with a backlight module to obtain a complete G-LCM.

[0016] The beneficial effects of this invention are as follows: This invention adds an external platform with considerable height and an arc-shaped transition to the outside of the OCA bonding platform. By adjusting the starting position of the OCA bonding roller to the external platform and controlling the roller speed, it can avoid OCA indentation marks caused by the bonding roller at the starting position and solve the problem of poor LCD bonding yellow spots at the starting position. Attached Figure Description

[0017] Figure 1 Schematic diagram of the fitting fixture structure described in Example 1; Figure 2 Schematic diagram of the OCA bonding process described in Example 2; Figure 3 Schematic diagram of the OCA bonding process described in Example 3; Figure 4 A schematic diagram of the OCA bonding process described in Comparative Example 1; Figure 5 A schematic diagram of the OCA bonding process described in Comparative Example 2; Figure 6 A schematic diagram of the OCA bonding process in the prior art; Figure 7 A schematic diagram of the G-LCM structure of this invention.

[0018] Explanation of markings in the diagram: External platform 1, arc-shaped transition area 2, flat area 3, base 4. Detailed Implementation

[0019] The embodiments of the present invention will be described in detail below with reference to the examples. The following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0020] Example 1 An adhesive jig for improving the adhesion of LCDs to the yellow spot includes an external platform 1, the upper surface of which includes a continuous arcuate transition area 2 and a planar area 3. The arc length of the arc-shaped transition zone 2 is less than 1 / 4 of a circle; The lowest point of the arc-shaped transition zone 2 is located on the outermost side of the external platform 1, and the highest point of the arc-shaped transition zone 2 is connected to the planar area 3. The curvature at any point in the arc-shaped transition zone 2 is less than the curvature of the conforming roller.

[0021] Furthermore, the bottom of the external platform 1 is connected to the base 4, which is used to support and fix the external platform 1. The base 4 is a height-adjustable base. Neither the external platform 1 nor the base 4 interferes with the OCA and the cover plate.

[0022] Furthermore, the height difference h of the arc-shaped transition zone 2 is ≤ 20% of the OCA thickness.

[0023] Example 2 A manufacturing method for improving the bonding of the yellow spot on an LCD, using the bonding fixture described in Example 1, includes the following specific steps: (1) Set up an external platform on the outside of the OCA bonding start position: Adjust the height and position of the base so that the lowest point of the arc transition area is flush with the upper surface of the OCA and the lower surface of the external platform on the side close to the OCA is above the cover plate; the lowest point of the arc transition area does not directly contact the side of the OCA and the horizontal distance a between them (i.e. the horizontal distance between the lowest point of the arc transition area and the OCA bonding start position) is kept at 0.2~0.5mm.

[0024] (2) The OCA is bonded to the cover plate by rolling with bonding rollers: the bonding rollers start at the flat area of ​​the outer platform, move from the flat area to the arc transition area, and then to the upper surface of the OCA to complete the bonding between the OCA and the cover plate; during this process, The bonding process is divided into a bonding speed enhancement stage (i.e., the first speed stage) and a bonding speed stabilization stage (i.e., the second speed stage). The first speed is 10~300mm / s, and the bonding speed must be achieved and stabilized before entering the OCA application starting position. The second speed is 300mm / s, which is the actual bonding speed for OCA application. At this stage, the speed is stable, ensuring optimal control of the OCA application effect (bubbles, indentations). Starting position of bonding roller: Adjust the starting position of OCA bonding roller to the flat area of ​​the external platform. The distance L from the starting position of bonding roller to the edge of OCA should be ≥ 50mm to ensure that the bonding speed has reached a stable state when the OCA bonding starts. Arc-shaped transition zone: The outer platform and the edge of the OCA form an arc-shaped transition, where the curvature of the arc-shaped transition zone of the outer platform is less than the curvature of the bonding roller. This ensures that when the bonding roller travels from the outer platform to the OCA interface, the roller pressure is mainly borne by the outer platform, greatly reducing the pressure at the beginning of OCA application. Furthermore, the stable bonding speed at the second stage allows for a stable transition, effectively avoiding edge indentations at the beginning of OCA application. Figure 2 ); The bonding angle should be 5°~15°. The OCA plane and the bonding platform need to form a certain bonding angle to allow the bonding air bubbles to be expelled in the bonding direction and avoid the formation of bonding air bubbles. The bonding angle should not be too small, otherwise it will affect the expulsion of bonding air bubbles. The bonding angle should not be too large either, otherwise OCA crease marks will be produced. Roller pressure: 100~300KPa. In order to achieve the best balance between air bubbles and indentation marks, the appropriate roller pressure needs to be adjusted for application. If the roller pressure is too low, the OCA will not be applied tightly and more air bubbles will be formed. If the roller pressure is too high, the OCA surface will be subjected to greater pressure and deformed, resulting in poor macular appearance. Roller diameter: 20~25mm. A reasonable roller diameter setting can take into account both the control of air bubbles and the control of indentation marks.

[0025] (3) The cover plate after lamination is bonded to the LCD via OCA to form G-LCD; (4) Assemble the G-LCD and the backlight module to form a complete G-LCM ( Figure 7 ); (5) Light up and test to confirm whether there are yellow spots on the LCD bonding.

[0026] The product obtained by the bonding method in this embodiment does not exhibit any bonding yellow spots.

[0027] Example 3 like Figure 3 As shown, unlike Example 2, the curvature of the arc-shaped transition zone is less than that of the arc-shaped transition zone in Example 2; otherwise, it is the same as Example 2. No yellow spots appeared on the product.

[0028] Comparative Example 1 like Figure 4 As shown, unlike Example 2, the curvature of the external platform's arc-shaped transition area is greater than that of the bonding roller; otherwise, it is the same as Example 2. Due to the large curvature of the external platform, it cannot form a good interlocking transition with the arc shape of the roller, causing the roller to jump slightly when it travels to the interface. The OCA bonding starting position is subjected to a slight jumping impact, resulting in a slight indentation and causing slight yellow spots on the LCD bonding.

[0029] Comparative Example 2 like Figure 5 As shown, unlike Example 2, the curvature of the external platform's arc-shaped transition area is equal to the curvature of the bonding roller; otherwise, it is the same as Example 2. Because the curvature of the external platform is too large, it cannot form a good interlocking transition with the arc shape of the roller, causing the roller to jump slightly when it reaches the interface. The starting position of the OCA bonding is subjected to a slight impact force from this jump, resulting in a slight indentation and causing slight yellow spots on the LCD bonding.

[0030] Comparative Example 3 Unlike Example 2, the second-speed starting point is on the OCA, meaning the speed only reaches 300 mm / s when the bonding roller travels to the OCA surface; otherwise, it is the same as in Example 2. Because the bonding roller did not achieve the required and stable second-speed bonding before entering the OCA application starting position, slight yellowing spots appeared on the product.

[0031] Comparative Example 4 Unlike Example 2, a = 0.18 mm, otherwise the same as Example 2. Since the horizontal deviation between the external platform and the OCA is 0.2 mm, a < 0.2 mm poses a risk of the external platform pressing against the OCA, resulting in damage and adhesive overflow at the edge of the OCA.

[0032] Comparative Example 5 Unlike Example 2, a = 0.55 mm, otherwise the same as Example 2. When a > 0.5 mm, the bonding roller cannot complete the transition of this gap well, which puts pressure on the starting position of OCA and causes bonding yellow spots.

Claims

1. A bonding fixture for improving the adhesion of the macula to an LCD screen, characterized in that, It includes an external platform (1), and the upper surface of the external platform (1) includes a continuous arc-shaped transition area (2) and a planar area (3). The arc length of the arc-shaped transition area (2) is less than 1 / 4 of a circle; The lowest point of the arc-shaped transition area (2) is located on the outermost side of the outer platform (1), and the highest point of the arc-shaped transition area (2) is connected to the plane area (3). The curvature of any point in the arc transition zone (2) is less than the curvature of the fitting roller.

2. The fitting fixture according to claim 1, characterized in that, The bottom of the external platform (1) is connected to the base (4), which is used to support and fix the external platform (1). The base (4) is a height-adjustable base. Neither the external platform (1) nor the base (4) interferes with the OCA and the cover plate.

3. The fitting fixture according to claim 2, characterized in that, The height difference h of the arc transition zone (2) is less than or equal to 20% of the OCA thickness.

4. A manufacturing method for improving the bonding of yellow spots on LCDs, characterized in that, Using the fitting fixture according to any one of claims 1-3, the steps are as follows: (1) Place the cover plate on the bonding platform and set an external platform on the outside of the OCA bonding start position: Adjust the height and position of the base so that the lowest point of the arc transition area is flush with the upper surface of the OCA, the external platform does not directly contact the OCA, the horizontal distance between the lowest point of the arc transition area and the OCA bonding start position is a=0.2~0.5mm, and the lower surface of the external platform on the side closer to the OCA is above the cover plate; (2) The OCA is bonded to the cover plate by the bonding roller: the starting point of the bonding roller is located in the flat area of ​​the external platform. The bonding roller moves from the flat area to the arc transition area, and then to the upper surface of the OCA to complete the bonding of the OCA and the cover plate.

5. The manufacturing method for improving LCD bonding yellow spots according to claim 4, characterized in that, Step (2) includes a bonding speed enhancement stage and a bonding speed stabilization stage; the bonding speed enhancement stage has a speed of 10~300mm / s, and the bonding speed stabilization stage has a speed of 300mm / s; the bonding roller has reached the bonding speed stabilization stage before contacting the OCA.

6. The manufacturing method for improving LCD bonding yellow spots according to claim 4, characterized in that, In step (2), the bonding tilt angle α formed by the OCA plane and the bonding platform is 5°~15°.

7. The manufacturing method for improving LCD bonding yellow spots according to claim 4, characterized in that, In step (2), the roller pressure of the bonding roller is 100~300KPa.

8. The manufacturing method for improving LCD bonding yellow spots according to claim 4, characterized in that, In step (2), the diameter of the bonding roller is 20~25mm.

9. The manufacturing method for improving LCD bonding yellow spots according to claim 4, characterized in that, In step (2), the distance L from the starting point of the bonding roller to the edge of the OCA is ≥50mm.

10. The manufacturing method for improving LCD bonding yellow spots according to claim 4, characterized in that, After the OCA is bonded to the cover plate, the OCA is bonded to the LCD to form G-LCD; the G-LCD is then assembled with the backlight module to obtain a complete G-LCM.

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