Display device

Abstract

A display device comprises a frameless display panel, a backlight module and a cover plate. The frameless display panel is provided with a first surface and a second surface which are opposite. The backlight module comprises a frame body. The frame is connected with the first surface through the adjusting structure. The cover plate is connected with the second surface through the connecting piece. The assembly stress of the frameless display panel is less than 13N, and the Young's modulus of the frameless display panel is in a range of 74 GPa to 83 GPa, so that the black state uniformity of the display device is greater than 70%. Therefore, the display device can achieve sufficient black state uniformity, and the phenomenon of dark state light leakage of the display device is effectively avoided.

Description

Technical Field

[0001] The present disclosure relates to a display device. Background Art

[0002] Currently, after the complete assembly of many display devices, there is a phenomenon of dark state light leakage near the border. The phenomenon of dark state light leakage refers to the phenomenon that the human eye perceives uneven brightness in a state of lower brightness, that is, the black state uniformity (which can also be called the black screen brightness uniformity) is poor. The reason for dark state light leakage may be that when there is internal stress or external force on the liquid crystal panel, the liquid crystal will generate a certain twist angle. The polarization direction of the liquid crystal linear polarized light near the stressed area of the liquid crystal panel changes. From the paper "Research on the Improvement of the Black State Uniformity of Vehicle-mounted Liquid Crystal Display Modules" (OPTOELECTRONIC TECHNOLOGY, Vol. 42, No. 2), it can be seen that there are many solutions for vehicle-mounted display devices to achieve high black state uniformity. From materials A and B in Table III and Table IV of this paper, it can be seen that when the photoelastic coefficient of the glass is reduced, the black state uniformity of the display device can be improved. However, from other literatures, such as the description of Patent No. CN1597583A, it is not easy to reduce the photoelastic coefficient of the glass. For example, the glass with a low photoelastic coefficient must contain a large amount of Pb compounds, which is extremely harmful to the environment. In addition, the glass containing Pb compounds can also be obtained by using the ultra-quenching process, but the production yield is extremely low, and the content of Pb components is strictly limited, so industrialization is difficult. In view of this, it can be seen that it is not easy to improve the black state uniformity of the display device by selecting glass materials. The paper also mentions that if there is internal stress in the glass, it will also cause the liquid crystal near the stress to deflect and then cause light leakage. Therefore, it is necessary to select glass with low internal stress to solve this problem.

[0003] However, for the assembly factory, the glass or other components are selected after being certified by the terminal brand factory. The assembly factory cannot arbitrarily select materials. Moreover, the aforementioned glass with a low photoelastic coefficient cannot be mass-produced smoothly. That is to say, how to effectively solve the problem of low black state uniformity during the assembly process is one of the problems that the industry urgently wants to invest in research and development resources to solve. Summary of the Invention

[0004] In view of this, an object of the present disclosure is to propose a display device that can, under the condition of existing materials, starting from the perspective of reducing assembly stress, solve the problem of lower black state uniformity by controlling the stress during assembly.

[0005] To achieve the above object, according to an embodiment of the present disclosure, a display device includes a frameless display panel, a backlight module, and a cover plate. The frameless display panel has opposite first and second surfaces. The backlight module includes a frame body. The frame body is connected to the first surface via an adjustment structure. The cover plate is joined to the second surface via a joining member. The assembly stress of the frameless display panel is less than 13 N, and the Young's modulus of the frameless display panel is greater than in the range of 74 GPa to 83 GPa, such that the black state uniformity of the display device is greater than 70%.

[0006] In one or more embodiments of the present disclosure, the display device further includes a circuit board. The frameless display panel has a first side connected to the circuit board and a second side opposite to the first side. The assembly stress of the first side is less than the assembly stress of the second side.

[0007] In one or more embodiments of the present disclosure, the assembly stress of the first side is less than 8 N. The assembly stress of the second side is less than 13 N.

[0008] In one or more embodiments of the present disclosure, the assembly stress of the first side is between 6 - 8 N. The assembly stress of the second side is between 10 - 13 N.

[0009] In one or more embodiments of the present disclosure, the assembly stress of the first side is less than 0.5 times the assembly stress of the second side.

[0010] In one or more embodiments of the present disclosure, the frameless display panel includes a glass substrate. The aforementioned Young's modulus is defined by the glass substrate.

[0011] In one or more embodiments of the present disclosure, the frame body is connected to the surface of the glass substrate facing the backlight module via an adjustment structure.

[0012] In one or more embodiments of the present disclosure, the adjustment structure includes two double-sided tapes and a buffer layer. The buffer layer is bonded between the two double-sided tapes.

[0013] In one or more embodiments of the present disclosure, the buffer layer includes foam.

[0014] In one or more embodiments of the present disclosure, the display device further includes a housing. The housing has a communicating opening and a receiving space. The frameless display panel and the backlight module are located in the receiving space. The cover plate is fixed to the opening.

[0015] In summary, in the display device of the present disclosure, by limiting the assembly stress and Young's modulus of the frameless display panel, the display device can achieve sufficient black state uniformity, thereby effectively avoiding the phenomenon of dark state light leakage in the display device. Moreover, by connecting the frame body of the backlight module and the frameless display panel through an adjustment structure with a specific stack structure, the assembly stress of the frameless display panel can be effectively absorbed.

[0016] The above is only used to illustrate the problems to be solved by this disclosure, the technical means for solving the problems, and the effects produced thereby. The specific details of this disclosure will be introduced in detail in the following embodiments and related drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] To make the above and other objects, features, advantages and embodiments of this disclosure more obvious and understandable, the accompanying drawings are described as follows:

[0018] Figure 1 FIG. is a schematic diagram of a display device according to an embodiment of this disclosure;

[0019] Figure 2 To illustrate Figure 1 a partial schematic diagram of some components of the display device in;

[0020] Figure 3 To illustrate Figure 1 a schematic diagram of the adjustment structure in;

[0021] Figure 4 FIG. is a top view showing the push-pull test points of the external circuit board and the frameless display panel.

[0022]

SYMBOL DESCRIPTION

[0023] 100: Display device

[0024] 110: Frameless display panel

[0025] 110a: First surface

[0026] 110b: Second surface

[0027] 111a, 111b: Glass substrate

[0028] 112a, 112b: Polarizer

[0029] 113: Color filter

[0030] 114: Liquid crystal molecules

[0031] 120: Backlight module

[0032] 121: Housing

[0033] 130: Adjustment structure

[0034] 131, 170: Double-sided tape

[0035] 131a: Substrate

[0036] 131b: Adhesive layer

[0037] 132: Buffer layer

[0038] 140: Cover plate

[0039] 141: Shielding member

[0040] 150: Joining member

[0041] 160: Housing

[0042] 161: Opening

[0043] 180: Fixing member

[0044] 191: System circuit board

[0045] 192: Display circuit board

[0046] 193: Electrical connector

[0047] 194: Shielding part

[0048] 195: External circuit board

[0049] D: Distance

[0050] P1, P2, P3, P4, P5, P6: Test points

[0051] S: Accommodating space Detailed implementation manners

[0052] The following will disclose multiple implementation manners of the present disclosure with the accompanying drawings. For the sake of clear illustration, many practical details will be described together in the following description. However, it should be understood that these practical details are not used to limit the present disclosure. That is to say, in some implementation manners of the present disclosure, these practical details are not necessary. In addition, for the purpose of simplifying the accompanying drawings, some conventional structures and elements will be shown in a simple schematic manner in the accompanying drawings.

[0053] Please refer to Figure 1 , which is a schematic diagram showing a display device 100 according to an implementation manner of the present disclosure. As Figure 1As shown, in the present embodiment, the display device 100 includes an open cell 110, a backlight module 120, and a cover plate 140. The open cell 110 has opposite first and second surfaces 110a and 110b. The backlight module 120 includes a frame 121. The frame 121 is connected to the first surface 110a of the open cell 110. The cover plate 140 is joined to the second surface 110b of the open cell 110 via a joining member 150. The assembly stress of the open cell 110 is less than 13 N (Newton), and the Young's modulus of the open cell 110 ranges from 74 GPa to 83 GPa (including the end values), such that the black state uniformity of the display device 100 is greater than 70%. That is to say, without specifically selecting a display panel with a high Young's modulus, the embodiments of the present invention can control the total stress during the assembly process (for example, less than 13 N), so that the display panel can withstand this stress without generating or reducing dark state light leakage.

[0054] With the open cell 110, the backlight module 120, and the cover plate 140 in the foregoing structural configuration, by controlling the assembly stress so that the stress does not exceed the bearing capacity of the open cell 110 (quantified by the Young's modulus hereinafter), the display device 100 can achieve sufficient black state uniformity, thereby effectively avoiding the phenomenon of dark state light leakage in the display device 100. The assembly stress here mainly controls the action of force during the assembly process, such as tightening screws and pressing bearings.

[0055] A method for testing the black state uniformity is as follows: (1) Prepare the test environment: Turn off the surrounding light sources to make the test environment as dark as possible (≤10 Lux), and use a pure black background. A professional test software or a completely black test picture can be used; (2) Locate the test points: Place the detection probe of the test instrument according to the usage instructions of the test instrument. A ruler or other tools can be used to accurately locate the position of the detection probe of the test instrument; (3) Measure the brightness of the black area: Use the test instrument to measure the brightness of the black picture area, measure the brightness results at different positions, and record the measurement results for subsequent analysis and comparison; and (4) Move the test instrument for multi-point testing: Move the test instrument along the horizontal and vertical directions to different areas of the display for testing, and record the measurement results of each test point. The test results can be plotted as a heat map or a scatter plot to more intuitively compare the black state uniformity of different test points. The black state uniformity is the percentage of the ratio of the darkest point to the brightest point among the test points on the acquisition surface: minimum brightness ÷ maximum brightness × 100%.

[0056] In some embodiments, the joining member 150 is, for example, a transparent optical adhesive (Optical Clear Adhesive, OCA), but the present disclosure is not limited thereto.

[0057] In some embodiments, the minimum thickness of the frameless display panel 110 is about 0.4 mm and the maximum thickness is about 2.6 mm, but the present disclosure is not limited thereto. Generally, after a display panel (such as an LCD) is manufactured and before being assembled, a rubber frame is used for fixation and protection. However, due to the demand for thinner displays, the assembly factory is required to directly assemble the display panel without a rubber frame, such as bonding it to a backlight module or connecting it to a circuit board. The "frameless display panel" referred to herein means a display panel without a rubber frame, which is directly assembled with other components. On the other hand, since the embodiments of the present invention assemble the frameless display panel 110, without a rubber frame, the frameless display panel 110 of the embodiments of the present invention is prone to deformation under stress, resulting in optical problems.

[0058] Please refer to Figure 2 which is a partial schematic diagram showing some components of the display device 100 shown in Figure 1 . As shown in Figure 1 and Figure 2 , in the present embodiment, the frameless display panel 110 includes a polarizer 112a, a glass substrate 111a, a color filter 113, liquid crystal molecules 114, a glass substrate 111b, and a polarizer 112b arranged in sequence from top to bottom. The two glass substrates 111a and 111b are respectively used as the bottom plates of the color filter 113 and the thin-film transistor (TFT). That is, the color filter 113 and the thin-film transistor are attached to both sides of the upper and lower glass substrates 111a and 111b. However, from common knowledge, compared with the two glass substrates 111a and 111b, the hardness / strength of the liquid crystal molecules 114 and the optical film (i.e., the polarizers 112a and 112b and the color filter 113) is very small. Therefore, the entire load-bearing or stress of the liquid crystal panel is almost on these two glass substrates 111a and 111b, and the Young's modulus of the material can be regarded as the physical property of the material under stress. Therefore, for the sake of simplicity, in the embodiments of the present invention, the Young's modulus of the two glass substrates 111a and 111b is used to simulate the Young's modulus of the entire liquid crystal panel / frameless display panel 110. Therefore, unless otherwise specified, the Young's modulus of the frameless display panel 110 referred to herein is defined by the glass substrates 111a and 111b.

[0059] As shown in Figure 2 , in the present embodiment, the frame 121 of the backlight module 120 is connected to the surface of the glass substrate 111b facing the backlight module 120 via an adjustment structure 130. In addition, the polarizer 112b of the frameless display panel 110 is disposed on the aforementioned surface of the glass substrate 111b facing the backlight module 120, and is separated from the adjustment structure 130 by a distance D.

[0060] In some embodiments, the distance D between the polarizer 112b and the adjustment structure 130 is in the range of about 0.5 mm to about 1.15 mm. If the distance D is too small, it cannot resist the deformation caused by the thermal expansion and contraction of the polarizer 112b; if the distance D is too large, the visible area affected by the polarizer 112b is very small, and a small visible area is not conducive to the display effect, but the present disclosure is not limited thereto.

[0061] Please refer to Figure 3 which shows a schematic diagram of the adjustment structure 130 in Figure 1 . As shown in Figure 3 , in the present embodiment, the adjustment structure 130 includes two double-sided tapes 131 and a buffer layer 132. The buffer layer 132 is bonded between the two double-sided tapes 131. Each double-sided tape 131 includes a substrate 131a and two adhesive layers 131b. The two adhesive layers 131b are respectively disposed on opposite surfaces of the substrate 131a. The buffer layer 132 is bonded to one of the adhesive layers 131b of each double-sided tape 131.

[0062] Since the adjustment structure 130 has the foregoing specific stack structure, by connecting the frame 121 of the backlight module 120 and the frameless display panel 110 through the adjustment structure 130, the assembly stress of the frameless display panel 110 can be effectively absorbed, so as to achieve the purpose of making the assembly stress of the frameless display panel 110 less than 8 N.

[0063] In some embodiments, the material of the substrate 131a of the double-sided tape 131 is plastic, such as polyethylene terephthalate (PET), but the present disclosure is not limited thereto.

[0064] In some embodiments, the material of the adhesive layer 131b of the double-sided tape 131 includes, for example, acrylic pressure-sensitive adhesive (Acrylic PSA), but the present disclosure is not limited thereto.

[0065] In some embodiments, the buffer layer 132 of the adjustment structure 130 includes foam. The buffer layer 132 includes, for example, polyurethane (PU) foam, such as Poron PU foam produced by Rogers Corporation, but the present disclosure is not limited thereto. Thereby, the buffer layer 132 can be the main part of the adjustment structure 130 to absorb the assembly stress of the frameless display panel 110.

[0066] In some embodiments, the overall thickness of the adjustment structure 130 is about 0.6 mm, but the present disclosure is not limited thereto. For example, the thickness of the substrate 131a of each double-sided tape 131 is about 0.012 mm, the thickness of the adhesive layer 131b of each double-sided tape 131 is about 0.045 mm, and the thickness of the buffer layer 132 is about 0.4 mm.

[0067] As shown in Figure 1As shown, in the present embodiment, the display device 100 further includes a housing 160. The housing 160 has a communicating opening 161 and a receiving space S. The frameless display panel 110 and the backlight module 120 are located in the receiving space S. The cover plate 140 is fixed to the opening 161 of the housing 160.

[0068] As Figure 1 shown, in the present embodiment, the cover plate 140 is adhered to the opening 161 of the housing 160 via a double-sided tape 131. Specifically, a shielding member 141 is provided on the side of the cover plate 140 facing the receiving space S. The peripheral area of the cover plate 140 is defined by the vertical projection of the shielding member 141. The cover plate 140 further has a visible area connecting the peripheral area. In other words, the visible area can be defined as the part of the cover plate 140 that does not overlap with the vertical projection of the shielding member 141.

[0069] In some embodiments, the double-sided tape 170 may have the same structure and material as the double-sided tape 131, but the present disclosure is not limited thereto. In other embodiments, the material of the base material 131a used for the double-sided tape 170 can be replaced with acrylic foam.

[0070] In some embodiments, the shielding member 141 is a black ink layer, but the present disclosure is not limited thereto. Thereby, when the user views the display device 100 from the side of the cover plate 140 away from the receiving space S, the black ink layer can be used to shield the underlying traces in the peripheral area. In addition, the shielding member 141 also has the effect of preventing light leakage.

[0071] In some embodiments, the shielding member 141 can be formed on the side of the cover plate 140 facing the receiving space S by a printing process. In practical applications, the number of ink layers of the shielding member 141 and the thickness of each ink layer can be adjusted flexibly according to actual requirements or process limitations.

[0072] In some embodiments, the side of the cover plate 140 away from the receiving space S can be coated with a film or subjected to evaporation plating, sputtering, film laminating, etc. For example, the film coating can have anti-reflection and anti-fouling properties, but the present disclosure is not limited thereto.

[0073] As Figure 1 shown, in the present embodiment, the display device 100 further includes a fixing member 180. The frame 121 of the backlight module 120 is fixed to the inner surface of the housing 160 via the fixing member 180.

[0074] In some embodiments, the fixing member 180 is a foam tape, but the present disclosure is not limited thereto. In practical applications, the fixing member 180 can be omitted.

[0075] As Figure 1As shown, in the present embodiment, the display device 100 further includes a system circuit board 191, a display circuit board 192, and an electrical connector 193. The system circuit board 191 and the display circuit board 192 are located within the accommodation space S of the housing 160 and are disposed at the bottom of the frame 121 of the backlight module 120. The system circuit board 191 and the display circuit board 192 are electrically connected to each other, and the display circuit board 192 is electrically connected to the frameless display panel 110 via traces. The electrical connector 193 is connected to the system circuit board 191 and passes through the housing 160 from the accommodation space S.

[0076] For example, the electrical connector 193 can be electrically connected to a vehicle, such that the display device 100 can be applied as an in-vehicle display, but the present disclosure is not limited thereto.

[0077] In some embodiments, the electrical connector 193 is a High Speed Date connector, which can transmit data and signals with a frequency up to 6 GHz without being interfered by noise, making it very suitable for applications in the automotive industry.

[0078] As Figure 1 shown, in the present embodiment, the display device 100 further includes a shielding member 194. The shielding member 194 covers the system circuit board 191 and the display circuit board 192 disposed at the bottom of the frame 121 of the backlight module 120 and extends along the side surface of the frame 121 of the backlight module 120 to the side surface of the frameless display panel 110, so as to achieve the purpose of reducing electromagnetic interference (EMI) to the system circuit board 191 and the display circuit board 192. In some embodiments, the material of the shielding member 194 includes metal.

[0079] In the embodiment of the present invention, the assembly stress generated during the process of assembling the frameless display panel 110 and other components into Figure 1 the in-vehicle display device 100 is controlled. Figure 4 FIG. is a top view showing the push-pull test points of the external circuit board 195 and the frameless display panel 110, which shows the stress test points P1, P2, P3, P4, P5, P6 of the frameless display panel 110 of the present invention during the assembly process. Additionally, Figure 4Also shows the positional relationship between the frameless display panel 110 of the embodiment of the present invention and the external circuit board 195. Among them, the test points P1, P2, and P3 are on the side where the frameless display panel 110 is connected to the external circuit board 195, while the test points P4, P5, and P6 are on the other side where the frameless display panel 110 is connected to the external circuit board 195. In the first embodiment, a frameless liquid crystal panel with a Young's modulus of 83 GPa is used for testing. At the test points P4, P5, and P6, stresses of 11.3 N, 12.1 N, and 10.8 N are applied respectively. By measurement and calculation, a black state uniformity greater than 70% (about 75%) can be obtained. In the second and third embodiments, frameless liquid crystal panels with Young's moduli of 81 GPa and 74 GPa are used for testing respectively. Under the same stress conditions as in the first embodiment, by measurement and calculation, black state uniformities of 76.2% and 71.8% can be obtained. Combining the foregoing embodiments, in the case of not specifically selecting a glass / frameless liquid crystal panel with a high Young's modulus (for example, the Young's modulus is between 74 - 83 GPa), the embodiments of the present invention propose that by controlling the assembly stress to be less than 13 N, 12.5 N, or less than 12.1 N, a display device with a black state uniformity greater than 70% can be achieved.

[0080] Furthermore, due to the assembly relationship between the frameless display panel 110 and the external circuit board 195, stress concentration is more likely to occur on the side where the frameless display panel 110 is connected to the external circuit board 195 than on the other side, resulting in light leakage due to the force on the glass / frameless liquid crystal panel. In other words, from a mechanical perspective, a smaller assembly stress may be required on the side where the frameless display panel 110 is connected to the external circuit board 195 to avoid light leakage. The fourth embodiment of the present invention is based on the first embodiment. At the test points P1, P2, and P3, stresses of 6.2 N, 7.7 N, and 6.5 N are applied respectively. By measurement and calculation, a black state uniformity of 75.4% can be obtained. Combining the first and fourth embodiments, in the case of not specifically selecting a glass / frameless liquid crystal panel with a high Young's modulus (for example, the Young's modulus is between 74 - 83 GPa), the embodiments of the present invention propose that by controlling the assembly stress on the side where the frameless display panel 110 is connected to the external circuit board 195 to be less than 8 N, 7.7 N, or less than 6 N, and controlling the assembly stress on the other side to be less than 13 N, 12.5 N, or less than 12.1 N, a display device with a black state uniformity greater than 70% can be achieved.

[0081] In another embodiment, the embodiments of the present invention propose that by controlling the assembly stress on the side where the frameless display panel 110 is connected to the external circuit board 195 to be less than 0.5 times the assembly stress on the other side (based on the calculation results of 13 N and 6 N above), a display device with a black state uniformity greater than 70% can be achieved.

[0082] In the first comparative example, the assembly stress on the side of the frameless display panel 110 connected to the external circuit board 195 is greater than 8 N, and the black state uniformity of the frameless display panel 110 is measured and calculated to be 60%.

[0083] In the second comparative example, the assembly stress on the other side of the frameless display panel 110 connected to the external circuit board 195 is greater than 13 N, and the black state uniformity of the frameless display panel 110 is measured and calculated to be 68.9%.

[0084] It should be noted that although the assembly stress should be as small as possible, in the actual assembly process, it is impossible to completely avoid generating assembly stress. Therefore, the embodiment of the present invention provides an assembly structure: without specifically selecting a glass / frameless liquid crystal panel with a high Young's modulus (for example, the Young's modulus is between 74 - 83 GPa), the assembly stress on the side of the frameless display panel 110 connected to the external circuit board 195 is controlled to be between 6 - 8 N, and the assembly stress on the other side of the frameless display panel 110 connected to the external circuit board 195 is between 10 - 13 N, and the black state uniformity can be greater than 70%.

[0085] From the above detailed description of the specific embodiments of the present disclosure, it can be clearly seen that in the display device of the present disclosure, by limiting the assembly stress and Young's modulus of the frameless display panel, the display device can achieve sufficient black state uniformity, thereby effectively avoiding the phenomenon of dark state light leakage in the display device. And by connecting the frame of the backlight module and the frameless display panel through an adjustment structure with a specific stack structure, the assembly stress of the frameless display panel can be effectively absorbed.

[0086] Although the present disclosure has been disclosed as above in embodiments, it is not intended to limit the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be determined by the scope defined by the appended claims.

Claims

1. A display device, characterized in that, Comprising: A frameless display panel having a first surface and a second surface opposite thereto; A backlight module including a housing, wherein the housing is connected to the first surface via an adjustment structure; and A cover plate joined to the second surface via a joining member, wherein an assembly stress of the frameless display panel is less than 13 N, and a Young's modulus of the frameless display panel is in a range of 74 GPa to 83 GPa, such that a black state uniformity of the display device is greater than 70%.

2. The display device according to claim 1, characterized in that, Further comprising a circuit board, wherein the frameless display panel has a first side connected to the circuit board and a second side opposite to the first side, and an assembly stress of the first side is less than an assembly stress of the second side.

3. The display device according to claim 2, characterized in that, The assembly stress of the first side is less than 8 N, and the assembly stress of the second side is less than 13 N.

4. The display device according to claim 2, characterized in that, The assembly stress of the first side is between 6 - 8 N, and the assembly stress of the second side is between 10 - 13 N.

5. The display device according to claim 2, characterized in that, The assembly stress of the first side is less than 0.5 times the assembly stress of the second side.

6. The display device according to claim 1, characterized in that, The frameless display panel includes a glass substrate, and the Young's modulus is defined by the glass substrate.

7. The display device according to claim 6, characterized in that, The housing is connected to a surface of the glass substrate facing the backlight module via the adjustment structure.

8. The display device according to claim 1, characterized in that, The adjustment structure includes: Two double-sided tapes; and A buffer layer adhered between the two double-sided tapes.

9. The display device according to claim 8, characterized in that, The buffer layer includes foam.

10. The display device according to claim 1, characterized in that, Further comprising a housing having a communicating opening and a receiving space, the frameless display panel and the backlight module are located in the receiving space, and the cover plate is fixed to the opening.

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