Display panel maintenance method

Abstract

The invention discloses a laser cutting device for display panel maintenance and a display panel maintenance method based on the laser cutting device, and particularly relates to the technical field of display panel maintenance. Laser beams act on a display panel through a laser light path to cut down and groove a glass substrate or a polaroid on the surface of the display panel; the laser is a purple picosecond pulse laser with the wavelength of 355 nm, the pulse width is smaller than or equal to 20 ps, the power is 6 W, the light beam quality M2 is smaller than 1.3, and the focal length of an objective lens is smaller than or equal to 10 mm. The success rate of display panel maintenance can be greatly improved, the shipment grade of the display panel is improved, and higher economic benefits are obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of display panel repair, and more specifically, to a display panel repair method. Background Art

[0002] Each pixel of the display panel is composed of three sub-pixels (red, green, and blue). Each sub-pixel is controlled by a transistor to control the strength of its current, thereby changing the arrangement of liquid crystal molecules, and then changing the refractive index and transmittance of light. Any transistor short circuit or abnormal deflection of liquid crystal molecules will cause bright spots. The current maintenance technologies in the display panel industry have relatively large limitations, so a new technology is needed to overcome these shortcomings, greatly improve the success rate of maintenance, improve the shipment level of liquid crystal panels, and obtain higher economic benefits. Summary of the invention

[0003] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a laser cutting device for display panel repair, wherein a laser beam acts on the display panel through a laser optical path to cut and dig grooves on the glass substrate or polarizer on the surface of the display panel; The laser uses a 355nm ultraviolet picosecond pulse laser with a pulse width of ≤20ps, a power of 6W, and a beam quality of M 2 <1.3, the focal length of the objective lens ≤10mm.

[0004] In a preferred embodiment, a beam expander, a reflector, a galvanometer, a dichroic mirror and an objective lens are sequentially arranged on the laser optical path, and the laser beam sequentially passes through the beam expander, the reflector, the galvanometer, the dichroic mirror and the objective lens to act on the display panel.

[0005] A display panel repair method is provided, wherein the repair is performed by a repair device, wherein the repair device comprises a CCD optical imaging system, a UV light curing unit, a shading material coating unit, a device control unit and a laser unit; wherein the CCD optical imaging system is used to observe the display panel and confirm defective points, the UV light curing unit cures the coated shading material by controlling the UV light irradiation intensity and irradiation time, the shading material coating unit is used to control the spitting time, the spitting amount per unit time and the coating path of the shading material, and the laser unit emits laser to cut and dig grooves on the surface of the glass substrate or polarizer of the display panel: The repair of the display panel specifically includes the following steps: Step 1, bad point confirmation: Use the CCD optical imaging system to confirm the location of the bad point on the display panel, the type of the bad point, and whether it is a bad point to be repaired; Step 2, bad spot repair: Use the laser unit to cut and dig the surface of the glass substrate or polarizer at the bad spot, and then use the shading material coating unit to coat the cut area with shading material. After the coating is completed, the UV light curing unit performs light curing on the coated area; Step 3: Confirm the repair effect: Use the CCD optical imaging system to confirm the effect of the repaired display panel. If the effect is qualified, proceed to repair the next display panel. If the result is unsatisfactory, repeat step 2.

[0006] In a preferred embodiment, the laser unit is the above-mentioned laser cutting device for display panel repair.

[0007] In a preferred embodiment, the maintenance equipment further comprises a grinding unit for grinding the shading material that is higher than the glass surface after solidification.

[0008] Technical effects and advantages of the present invention: 1. The present invention reduces the focal length of the front-end objective lens to obtain a laser cutting device with a low focal depth. During cutting, the liquid crystal, metal circuit, ITO film layer and the like below the glass substrate are kept away from the focal depth range, thereby reducing the influence of the laser on them, increasing the panel grooving depth, and reducing the distance between the coating area and the bad point, thereby achieving the effect of reducing the area of ​​the coating area.

[0009] 2. The present invention can greatly improve the success rate of display panel repair, enhance the shipment level of display panels, and obtain higher economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1a This is a diagram of the shading effect when the panel is blackened.

[0011] Figure 1a-1 This is a schematic diagram of ITO blackening repair.

[0012] Figure 1b This is another picture of the shading effect when the panel is blackened.

[0013] Figure 1c A schematic diagram of the interior of the display panel after Ink repair.

[0014] Figure 1d Schematic diagram of a glass substrate for direct coating repair.

[0015] Figure 1e Schematic diagram of another glass substrate being repaired by direct coating.

[0016] Figure 1f Schematic diagram of light leakage on a glass substrate repaired by direct coating.

[0017] Figure 1g Another schematic diagram of light leakage on a glass substrate repaired by direct coating.

[0018] Figure 2 It is a schematic diagram of the laser cutting device of the present invention.

[0019] Figure 3 It is a schematic diagram of the surface of a glass substrate after being cut by the laser cutting device of the present invention.

[0020] Figure 4 Schematic diagram of the surface of a glass substrate after cutting with traditional laser equipment.

[0021] Figure 5 It is a schematic diagram of the structure of the maintenance equipment of the present invention.

[0022] Figure 6 This is a schematic diagram of confirming the processing area of ​​the display panel of the present invention.

[0023] Figure 7 It is a schematic diagram of coating the light-shielding material of the present invention.

[0024] Figure 8 Schematic diagram of glass substrate trenching and repair in one embodiment of the present invention.

[0025] Fig. 9 Schematic diagram of polarizer trenching and maintenance in one embodiment of the present invention.

[0026] Fig.10 FIG1 is a maintenance example of the present invention.

[0027] Fig.11 Maintenance example for the present invention Figure 2 .

[0028] The reference numerals are: 1. CCD optical imaging system; 2. UV light curing unit; 3. light shielding material coating unit; 4. equipment control unit; 5. laser unit; 6. grinding unit. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention are provided for the purpose of illustration and description, and are not intended to be exhaustive or to limit the present invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

[0030] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0031] In the related technology, the repair methods for bright spots on LCD panels include BM diffusion repair, ITO blackening repair and direct coating method. Among them, the common point of BM diffusion repair and ITO blackening repair is to repair the bright spot pixels of the LCD panel into dark spot pixels, so that they can achieve the effect of shading and are not easily noticed in the macroscopic view. The direct coating method does not change the bright spot pixels themselves, does not destroy the structure of the display panel surface, and achieves the shading effect through coating.

[0032] Among them, BM diffusion repair uses laser to break up the BM around the sub-pixel and cover it on the sub-pixel, so that it no longer emits light. With the update and iteration of current LCD panel products, the BM area between sub-pixels is getting smaller and smaller, and the amount of BM that can be used to cover sub-pixels is getting smaller and smaller. The success rate of repair using this technology is getting lower and lower, and its applicability is getting narrower and narrower.

[0033] like Figure 1a-1 As shown in the figure, ITO blackening repair uses laser to act on the ITO and insulating layer on the TFT side, causing the substances therein to undergo chemical changes, thereby achieving pixel blackening and making the pixel no longer emit light. If the materials or material ratios used in the ITO and insulating layer change, the blackening will fail. Therefore, this technology can only be used for specific products and is highly dependent on the product being repaired.

[0034] like Figure 1c As shown, when the panel is internally repaired during the production process and a metal bridge made of tungsten powder or nano-silver material exists, ITO blackening repair will damage the metal bridge, causing the ITO blackening repair to be unable to proceed normally. Therefore, ITO blackening repair has great limitations in actual application.

[0035] like Figure 1a In the repair method shown, the panel material is burned by laser above the sub-pixel, so that the burned panel part is blackened to form a light-shielding area, and the sub-pixel is shielded from light, achieving an effect that is not easily noticed from a macroscopic perspective. However, since the light has a certain divergence angle during the light emission of the sub-pixel. During the blackening process, if only the area with the same area as the sub-pixel is processed, due to the thickness of the product, there will be a certain angle of light leakage within the side view range of the sub-pixel, making the light-shielding effect unclear; like Figure 1b One repair method shown is to perform laser burning on an area on the panel that is far larger than the sub-pixel area, forming a blackened area that effectively shields the sub-pixel. Large-scale laser burning treatment will cause abnormal energy accumulation during the burning process, causing certain damage to the liquid crystal, metal circuits, and ITO film layers in the panel.

[0036] The direct coating method is to directly coat the shading material on the display panel area above the defective point to block the light. Figure 1d As shown, a coating area is preset on the surface of the glass substrate directly above the defective pixel. The coating area does not affect the display of the neighboring pixels of the defective pixel while being able to cover the light within the divergence angle of the defective pixel. At this time, a shading material is directly coated on the surface of the glass substrate to achieve a good shading effect; or as shown in FIG. Figure 1e As shown, when a polarizer is present, a coating area is preset on the surface of the glass substrate directly above the defective sub-pixel. The coating area does not affect the display of the adjacent sub-pixels of the defective sub-pixel while being able to cover the light within the divergence angle of the defective sub-pixel. At this time, the shading material is directly coated on the surface of the glass substrate to achieve a good shading effect.

[0037] However, in actual applications, due to the divergence angle of light or the thickness of the display panel, light leakage may occur at the edge of the shading material. Figure 1f As shown, a coating area is preset on the surface of the glass substrate above the defective pixel. The coating area cannot completely cover the light within the divergence angle of the defective pixel without affecting the display of the neighboring sub-pixels of the defective pixel; or as Figure 1g As shown, a coating area is preset on the surface of the polarizer above the defective sub-pixel. The coating area cannot completely cover the light within the divergence angle of the defective sub-pixel without affecting the display of the neighboring sub-pixels of the defective sub-pixel.

[0038] As can be seen from the above, BM diffusion repair, ITO blackening repair and direct coating methods all have certain technical defects. For this reason, the present invention proposes to use laser to first thin and groove the defective points of the panel, and then perform light-shielding coating on the thinned area to solve the above technical problems.

[0039] The technical difficulty of using laser to thin and groove the panel defective points lies in the precise control of the laser. This embodiment provides a laser cutting device for display panel repair, which is used for display panel repair to avoid the defects in the above repair method.

[0040] This embodiment provides a laser cutting device for display panel repair, comprising a laser, a beam expander, a reflector, a galvanometer, a dichroic mirror and an objective lens arranged in sequence, and the laser beam acts on the display panel through the beam expander, the reflector, the galvanometer, the dichroic mirror and the objective lens. Figure 2 The laser is a 355nm ultraviolet picosecond pulse laser with a pulse width of ≤20ps, a power of 6W, and a beam quality of M 2 <1.3, the focal length of the objective lens ≤10mm.

[0041] Different from the existing high focal length objective lens, the objective lens here adopts a low focal length objective lens. From the depth of focus calculation formula DOF= It can be seen that the focal depth is proportional to the square of the focal length f of the focusing lens. The larger the focal length f, the greater the focal depth, the greater the depth of laser action, and the easier it is to damage the metal circuits, film layers, etc. under the glass substrate.

[0042] Note: M 2 is the laser beam quality factor, is the laser wavelength, f is the focal length of the focusing lens, and D is the diameter of the laser beam before passing through the focusing lens. Within the focal depth range, the laser spot shape, size, energy distribution, etc. change very little, which can ensure a good processing effect.

[0043] The display panel is thinned using a picosecond 355nm ultraviolet laser, reducing the focal length of the front objective lens to obtain a smaller depth of focus. This keeps the liquid crystal, metal circuits, ITO film layers, etc. under the glass substrate away from the depth of focus, reducing the impact of the laser on them and increasing the thinning depth of the panel.

[0044] Cut grooves on the surface of the glass substrate and apply shading material. The thickness of the glass substrate is 400um. The laser wavelength used is 355nm ultraviolet picosecond pulse laser, the pulse width is ≤20ps, the power is 6W, and the beam quality is M 2 <1.3, the diameter of the laser beam before passing through the objective lens is 5mm, and the focal length of the objective lens is 10mm. Substituting the corresponding data into the calculation formula of the depth of focus, the depth of focus DOF≈4.7um can be obtained. The thickness of the panel glass substrate to be processed is about 400um, that is, the thickness of the glass surface from the pixel area, film layer, etc. is about 400um. 4.7 is much smaller than 400, and the processing effect is as follows Figure 3 As shown in the figure, 100um trenching is performed. During processing, the laser has little impact on the pixel area and film layer on the lower surface of the glass, ensuring the integrity of the components below.

[0045] If the objective lens (focusing lens) is replaced with a focal depth of 100mm, the focal depth DOF≈470um. At this time, the focal depth is greater than the thickness of the glass substrate (400um). During processing, the laser has a great impact on the pixel area and film layer on the lower surface of the glass. The processing effect is as follows: Figure 4 As shown, the metal circuits, film layers, etc. are obviously damaged.

[0046] The embodiment of the present invention provides a display panel repair method, which is repaired by a repair device, such as Figure 2 and Figure 5 As shown, the maintenance equipment includes a CCD optical imaging system, a UV light curing unit, a light shielding material coating unit, an equipment control unit, a grinding unit and a laser unit. The laser unit is Figure 2The laser in the CCD optical imaging system is specifically a camera configured in the optical path of the laser unit. The light reflected by the objective lens and the dichroic mirror is obtained, and a reflector and a lens that are distinguished from the laser unit are separately set in the optical path received by the camera. A camera light source is set in the optical path for fill light, and the image information of the display panel is obtained through the camera.

[0047] The maintenance methods include the following: Use the CCD optical imaging system to confirm the location of the bad spot on the display panel, the type of the bad spot, and whether it is the bad spot to be repaired; Using the computer control system, an XY axis is established on the surface of the defective point, and the defective point processing area to be reduced is divided by the XY axis, the position of the defective point processing area is confirmed, and the processing mark is made through the computer control system, such as Figure 6 As shown; The computer controls the galvanometer to scan the processing area plane along the XY axis. During the scanning process, the distance between the objective lens and the display panel is maintained. The laser unit is used to cut and dig grooves at the defective points of the panel, and the area above the defective points is thinned. Then, the thinned area is injected with shading material for coating. Figure 7 As shown; Then, the material is cured by UV light curing, and the shading material whose height is higher than the glass surface after curing is ground flat by a grinding unit; The CCD optical imaging system is used to confirm the effect of the repaired display panel. If the effect is satisfactory, the next display panel will be repaired. If the effect is unsatisfactory, the cutting, grooving and coating processes are repeated.

[0048] In another embodiment of the present invention, the laser to be repaired is the above-mentioned Figure 2 The laser in the display panel is used to cut and dig grooves through the laser, and the coating and curing are completed. The display panel includes a sub-pixel located in the middle and a glass substrate attached to the upper and lower sides of the sub-pixel, as follows: like Figure 8 As shown, the laser unit emits laser to cut and groove the surface of the glass substrate on the light-emitting side of the sub-pixel, the shading material coating unit coats the shading material on the grooved area of ​​the glass substrate, the UV light cures the coated shading material, and then the coated material is smoothed. Due to the use of the above-mentioned low-focus depth laser, the groove depth can be increased during the groove reduction process, the distance between the coating area and the bad point is reduced, and the area of ​​the coating area is reduced. At this time, the shading material does not affect the display of the sub-pixels adjacent to the bad point while being able to cover the light within the divergence angle of the sub-pixel of the bad point, thereby achieving the effect of shading, which is not noticeable on a macro scale.

[0049] In another embodiment of the present invention, the laser to be repaired is the above-mentioned Figure 2 The laser in the display panel is used to cut and dig grooves through the laser, and the coating and curing are completed. The display panel includes a sub-pixel located in the middle, a glass substrate attached to the upper and lower sides of the sub-pixel, and a polarizer attached to the side of the glass substrate away from the sub-pixel. The details are as follows: like Fig. 9 As shown, the laser unit emits laser to cut and groove the surface of the polarizer on the light-emitting side of the sub-pixel, the shading material coating unit coats the shading material on the grooving area of ​​the polarizer, UV light cures the coated shading material, and then the coated material is smoothed. Due to the use of the above-mentioned low-focus depth laser, the grooving depth can be increased during the grooving process, reducing the distance between the coating area and the bad point, thereby achieving the effect of reducing the area of ​​the coating area. At this time, the shading material does not affect the display of the sub-pixels adjacent to the bad point while being able to cover the light within the divergence angle of the sub-pixel of the bad point, thereby achieving the effect of shading, which is not noticeable on a macro scale.

[0050] Based on the above repair method, after the bad point of the display panel is repaired, a photo is taken on the luminous side of the pixel point of the display panel, such as Fig.10 As shown, the observed bad pixel point is covered by the shading material to achieve the shading effect, which is not noticeable on a macro scale.

[0051] Based on the above repair method, after the bad spot of the display panel is repaired, the image images obtained on both sides of the light source of the display panel are as follows: Fig.11 As shown, the positive light is the image on the back side of the display panel pixel, while the backlight is the image on the front side of the display panel pixel. By cutting grooves and applying shading materials, the shading effect of bad points can be achieved without affecting the normal display of adjacent pixels.

[0052] In summary, by using the laser cutting device and display panel repair method provided by the present invention, when repairing defective points on the panel, the repair success rate can be greatly improved, the shipment level of the display panel can be improved, and higher economic benefits can be obtained.

[0053] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field and related fields without creative work should fall within the scope of protection of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention are implemented according to the conventional means in the field unless otherwise specified and limited.

Claims

1. A laser cutting device for display panel repair, characterized in that: The laser beam acts on the display panel through the laser optical path to cut and dig grooves on the glass substrate or polarizer on its surface; The laser uses a 355nm ultraviolet picosecond pulse laser with a pulse width of ≤20ps, a power of 6W, and a beam quality of M 2 <1.3, the focal length of the objective lens ≤10mm.

2. The laser cutting device according to claim 1, characterized in that: A beam expander, a reflector, a galvanometer, a dichroic mirror and an objective lens are sequentially arranged on the laser optical path, and the laser beam sequentially passes through the beam expander, the reflector, the galvanometer, the dichroic mirror and the objective lens to act on the display panel.

3. A display panel repair method, which is repaired by a repair device, characterized in that: The repair equipment includes a CCD optical imaging system, a UV light curing unit, a shading material coating unit, an equipment control unit and a laser unit; wherein the CCD optical imaging system is used to observe the display panel and confirm the defective points, the UV light curing unit cures the coated shading material by controlling the UV light irradiation intensity and irradiation time, the shading material coating unit is used to control the spitting time of the shading material, the spitting amount per unit time and the coating path, and the laser unit emits laser to cut and dig grooves on the surface of the glass substrate or polarizer of the display panel; The repair of the display panel specifically includes the following steps: Step 1, bad point confirmation: Use the CCD optical imaging system to confirm the location of the bad point on the display panel, the type of the bad point, and whether it is a bad point to be repaired; Step 2, bad spot repair: Use the laser unit to cut and dig the surface of the glass substrate or polarizer at the bad spot, and then use the shading material coating unit to coat the cut area with shading material. After the coating is completed, the UV light curing unit performs light curing on the coated area; Step 3: Confirm the repair effect: Use the CCD optical imaging system to confirm the effect of the repaired display panel. If the effect is qualified, proceed to repair the next display panel. If the result is unsatisfactory, repeat step 2.

4. A display panel repair method according to claim 3, characterized in that: The laser unit is the laser cutting device for display panel repair as described in claim 1.

5. A display panel repair method according to claim 3 or 4, characterized in that: The maintenance equipment also includes a grinding unit, which is used for grinding the shading material that is higher than the glass surface after solidification.

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