Display screen module of in-vehicle dimmable rearview mirror and preparation method thereof

Abstract

The invention discloses a display screen module of an in-vehicle dimmable rearview mirror and a preparation method thereof. The display screen module comprises a cover plate, a first optical glue, a color-variable liquid crystal dimming layer, a second optical glue, a liquid crystal display screen and a backlight assembly; a side sealing glue is arranged between the backlight assembly and the cover plate; the preparation method comprises assembling the display module and the backlight assembly separately, then assembling them, and then filling the side sealing glue in the gap between the backlight assembly and the cover plate, thereby solving the light leakage defect caused by the increase of the thickness of the display module, improving the display effect and the yield rate, realizing automatic adjustment of the transmittance and reflectivity of the display module according to the light intensity and voltage, and improving the adaptability to light of different intensities.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle rearview mirrors, and in particular relates to a display screen module of an in-vehicle dimmable rearview mirror and a preparation method thereof. Background Art

[0002] The rearview mirror inside the vehicle is an important device for the driver to observe the rear view of the vehicle, so there are corresponding standards for its quality and installation. When the driver is in a long dark tunnel at night or in a dark tunnel, the headlights of the car behind the car shine on the rearview mirror inside the vehicle through the rear window of the vehicle, and the reflected light of the rearview mirror reflects on the driver's eyes, which will cause glare, stimulate the driver's eyeballs, and make the driver suddenly dizzy. If there are people and cars in the front at a close distance, traffic accidents are very likely to occur. In addition, the driver generally adjusts the rearview mirror to his best vision, and the best vision is the most complete position of the rearview mirror light reflected to the driver's eyes, so the glare is stronger. Most drivers will look at the rearview mirror every 3-5 seconds when driving. When the driver looks at the rearview mirror, if the lights of the rear vehicle shine on the rearview mirror of the car, the driver will not only not be able to see the things behind clearly, but also will be dizzy.

[0003] In order to reduce the stimulation of strong light reflected by the rearview mirror to the driver, the existing technology adds a color-changing liquid crystal dimming layer in the original liquid crystal display module. Through the electrochromic glass technology, that is, when there is strong light from behind, the photoelectric control system gives a certain voltage to the color-changing liquid crystal dimming layer to adjust its transmittance, thereby reducing the reflectivity and eliminating the strong light stimulation, allowing the driver to see the front and rear affairs in time, so as to improve driving safety and relieve driving fatigue.

[0004] Chinese patent CN103963711A discloses a semi-transparent and semi-reflective electronic anti-glare rearview mirror lens, which includes two pieces of transparent glass and a conductive layer. The two conductive layers are bonded to form an electrochromic material layer and filled with electrochromic material or electrochromic liquid crystal. The outer frame of the electrochromic material layer is sealed with epoxy resin glue, thereby solving the problems of insufficient transmittance of the current anti-glare rearview mirror, and the inability to display clearly even when the display screen behind the glass is adjusted to the brightest or a high-brightness screen is used.

[0005] Chinese patent CN10516661A discloses an electrochromic anti-glare mirror display screen, which includes a liquid crystal screen rear layer glass, a liquid crystal material filling layer, a lens reflective layer glass, an electrochromic material layer, a lens projection layer glass, etc. The display screen has the functions of a traditional display screen and an anti-glare lens function.

[0006] However, the increase in the electrochromic material layer increases the thickness of the entire display module, causing the original backlight baffle to be unable to block the side of the liquid crystal dimming layer, causing the light in the backlight to penetrate the liquid crystal display and the liquid crystal dimming layer and then scatter from the side. Therefore, when observing the display module from the front, light can be clearly seen leaking out from its edge, which is the light leakage phenomenon, affecting the display effect and yield rate of the entire product. As the trend in the industry is to continuously increase the proportion of LCD screens, it is necessary to continuously compress the width of the backlight baffle, which is easy to expand the size of the LCD screen. Under the trend of a very small backlight baffle width, if the backlight baffle made of die-casting material is raised too much, the thin backlight baffle is prone to deformation. The inner wall of the backlight baffle is uneven due to insufficient structural strength, which is easy to cause extrusion damage to the side of the LCD display; at the same time, if the backlight baffle is too high, the yield rate in its production will also be reduced accordingly. Considering the comprehensive yield rate and cost, the light leakage phenomenon cannot be solved by simply raising the backlight baffle.

[0007] In addition, the existing electrochromic material layer has only two states, namely light-transmitting and light-opaque, and is therefore only suitable for scenes with no light behind and strong light behind, and does not have the function of adjusting the transmittance according to the light intensity. Summary of the invention

[0008] In view of the above technical problems, the present invention provides a display screen module for an in-vehicle dimmable rearview mirror and a preparation method thereof, which solves the light leakage defect caused by the increase in the thickness of the display module, improves the display effect and yield rate, realizes automatic adjustment of the transmittance of the display module according to the light intensity and voltage, and improves the adaptability to light of different intensities.

[0009] In order to achieve the above-mentioned purpose, the present invention provides a display screen module for an in-vehicle dimmable rearview mirror, comprising a cover plate, a first optical glue, a color-variable liquid crystal dimming layer, a second optical glue, a liquid crystal display screen and a backlight assembly; a side sealing glue is provided between the backlight assembly and the cover plate.

[0010] Preferably, the backlight assembly includes a backlight baffle, a backlight bottom plate, a backlight inner film and a backlight boss.

[0011] Further preferably, the calculation formula for the amount of the side sealing glue is (W1+W2)×H / 2×(a+b)×2; wherein W1 is the width of the backlight baffle, W2 is the width difference between the cover plate and the liquid crystal dimming layer, H is the height difference between the cover plate and the backlight baffle; a is the length of the display module, and b is the width of the display module.

[0012] More preferably, the side sealing glue is black hot melt glue or UV curing glue.

[0013] Preferably, the color-variable liquid crystal dimming layer has an operating voltage of 0-15V, a transmittance of 20-75%, and a reflectivity of 10-50%.

[0014] Further preferably, when the operating voltage of the color-changing liquid crystal dimming layer is 0V, the transmittance of the display screen module is ≤25%, and the reflectivity is ≥50%; when the operating voltage of the color-changing liquid crystal dimming layer is 5V, the transmittance of the display screen module is 45±5%, and the reflectivity is 40±5%; when the operating voltage of the color-changing liquid crystal dimming layer is 10V, the transmittance of the display screen module is 60±5%, and the reflectivity is 20±5%; when the operating voltage is 15V, the transmittance of the display screen module is ≥75%, and the reflectivity is ≤10%.

[0015] More preferably, the color-changing liquid crystal dimming layer is a two-layer laminated glass component made using PDLC technology (polymer dispersed liquid crystal); the PDLC dimming component includes two glass substrates with electrodes and liquid crystal particles encapsulated between the two glass substrates. Preferably, the first optical adhesive and the second optical adhesive are OCA optical adhesives with a viscosity of 15-16 N / cm, an optical transmittance of ≥95%, and a thickness of 200-300 μm.

[0016] Further preferably, the OCA optical adhesive is capacitive OCA optical adhesive.

[0017] Preferably, the thickness of the cover plate is 1.5-2.0 mm, the thickness of the first optical glue is 0.2-0.3 mm, the thickness of the color-changing liquid crystal dimming layer is 2.0 mm, the thickness of the second optical glue is 2.0-3.0 mm, the thickness of the liquid crystal display is 1.0 mm, and the thickness of the backlight assembly is 7.0-8.0 mm.

[0018] Further preferably, in the backlight assembly, the thickness of the backlight base plate is 4.0-5.0 mm, and the thickness of the backlight baffle is 2.0-3.0 mm.

[0019] The present invention also provides a method for preparing a display screen module of an in-vehicle dimmable rearview mirror, comprising the following steps: (1) Assembling the display screen module: using a first optical adhesive to bond the cover plate to the color-changing liquid crystal dimming layer; and then using a second optical adhesive to bond the liquid crystal display screen to the color-changing liquid crystal dimming layer; (2) Assembling the backlight assembly: placing the backlight inner film on the backlight base plate, and backlight baffle walls are arranged on both sides of the backlight base plate; (3) Assembling the display screen module: Assemble the display screen module and the backlight assembly; (4) Glue sealing: Fix the display screen module vertically, apply glue on both sides, cure, and clean up excess glue to obtain the display screen module of the dimmable rearview mirror.

[0020] Preferably, the backlight base plate and the backlight baffle wall described in step (2) are integrally die-cast, and a backlight boss protrudes from the inner side of the backlight baffle wall, and the backlight boss is inserted into a slot on the inner wall of the backlight baffle wall.

[0021] Further preferably, the lower surface of the backlight boss presses the backlight film to fix the film, and the upper surface is adhered with double-sided tape to be bonded and fixed to the lower surface of the display screen module.

[0022] Preferably, the curing method in step (4) is static curing or UV irradiation curing.

[0023] Further preferably, the static curing time is 2-4 minutes, and the light intensity of UV light curing is 3000mj / cm 2 .

[0024] The beneficial effects of the present invention are: 1. A side sealant is set between the backlight baffle and the cover plate to solve the problem of side scattering, light divergence to the edge of the entire display module, and light leakage caused by the backlight baffle being unable to block the side of the liquid crystal dimming layer. This improves the display effect and yield rate of the display module and promotes the application and promotion of dimmable rearview mirror display modules.

[0025] 2. After the side sealant is cured, the bonding strength between the backlight baffle and the ink layer on the lower side of the cover is enhanced, and the impact resistance of the entire display module is improved, thereby improving the display module's resistance to severe vibration, collision, and high temperature and high humidity conditions, and extending the service life of the display module.

[0026] 3. A color-changing liquid crystal dimming layer capable of gradient-changing transmittance is adopted, and the transmittance of the color-changing liquid crystal dimming layer is controlled by the gradient change of voltage; when no voltage is applied, the color-changing liquid crystal dimming layer is in a dark and basically opaque state, and the rearview mirror module has a strong reflection of external light; when a predetermined voltage is applied to the liquid crystal dimming layer, the dimming layer is in a light-colored and translucent state, and the rearview mirror absorbs and filters external light and reflects less external light; when voltages of different gradients are applied, the color of the liquid crystal dimming layer can change from light to dark in different gradients, thereby realizing different degrees of reflection and absorption and filtering of light, so that the light intensity in the rearview mirror is within a comfortable range for the human eye. The color-changing liquid crystal dimming layer uses a PDLC dimming component, which has the following characteristics: when an external electric field is applied to the two layers of glass, the optical axis direction of the internal phase-matched liquid crystal molecules is uniformly along the direction of the electric field, and the refractive index of the liquid crystal particles matches that of the matrix to a certain extent, so that light can pass through the matrix and appear transparent or translucent; when the external electric field is removed, the liquid crystal particles return to their original disordered arrangement state, and the transmitted light appears in a scattered state, achieving the effect of blocking the light, so that the PDLC has the characteristics of an electrically controlled optical switch, so that the purpose of controlling the transmittance by voltage can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a display screen module in the prior art.

[0028] Figure 2 This is the display screen module prepared in Example 1.

[0029] Figure 3 This is a schematic diagram of glue dispensing in Example 1.

[0030] In the figure, 1 is a cover plate, 2 is a first optical glue, 3 is a color-variable liquid crystal dimming layer, 4 is a second optical glue, 5 is a liquid crystal display screen, 6 is a backlight assembly, 7 is a side sealing glue, 61 is a backlight baffle, 62 is a backlight bottom plate, 63 is a backlight inner film, and 64 is a backlight boss. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be understood as limiting the present invention. The protection scope of the present invention shall be based on the contents recorded in the claims. Any modification or replacement made by those skilled in the art to the technical solution of the present invention without creative work shall fall within the protection scope of the present invention.

[0032] Example 1 (1) Take a cover plate 1 glass, apply a first optical adhesive 2 on the ink layer on the back thereof, and laminate it to one side of a color-changing liquid crystal dimming layer 3, then apply a second optical adhesive 4 on the other side of the color-changing liquid crystal dimming layer 3, and laminate it to a liquid crystal display screen 5, to prepare a display screen module; (2) Take an integral die-cast backlight base plate 62 containing a backlight baffle 61, embed a backlight inner film 63 on one side of the backlight base plate 62, and then insert the backlight boss 64 into the inner side of the backlight baffle 61, fix the backlight inner film 63, and obtain a backlight assembly 6; (3) Adhere double-sided tape to the backlight boss 64 in the backlight assembly 6, and connect the side provided with the backlight inner film 63 to the display screen module to obtain a connected product; (4) Fix the connected product vertically on the operating table, use a caliper to measure the width W2 of the backlight baffle 61, the width difference W2 between the cover plate 1 and the liquid crystal dimming layer 3, the height difference H between the cover plate 1 and the backlight baffle 61, the length a of the display module, and the width b of the display module, and calculate the amount of side sealant 7; (5) Take black hot melt adhesive, melt it at 120°C until it is in a fluid state, and deliver it to the needle through a hose. The needle discharges the adhesive vertically downward and injects it into the adhesive dispensing area formed by the backlight baffle 61 and the cover plate 1 according to the amount calculated in step (4). During the dispensing process, the needle moves along the four sides of the adhesive dispensing area to evenly fill and bond the backlight baffle 61 and the cover plate 1. The adhesive is allowed to stand at room temperature for 4 minutes before curing. (6) The other end of the connected product is cured according to the method described in steps (4) to (5) to obtain a display screen module of a dimmable rearview mirror.

[0033] Example 2 Steps (1) to (4) are the same as in Example 1; (5) Take black UV glue, melt it at 120°C until it flows, and deliver it to the needle through a hose. The needle discharges glue vertically downward and injects it into the glue dispensing area formed by the backlight baffle 61 and the cover plate 1 according to the amount calculated in step (4). During the glue dispensing process, the needle moves along the four sides of the glue dispensing area to evenly fill and bond the backlight baffle 61 and the cover plate 1. Room temperature, 3000mj / cm 2 The curing is completed by irradiating under ultraviolet light for 1 minute; (6) The other end of the connected product is cured according to the method described in steps (4) to (5) to obtain a display screen module of a dimmable rearview mirror.

[0034] Comparative Example 1 (1) Take a cover plate 1 glass, apply a first optical adhesive 2 on the ink layer on the back thereof, and laminate it to one side of a color-changing liquid crystal dimming layer 3, then apply a second optical adhesive 4 on the other side of the color-changing liquid crystal dimming layer 3, and laminate it to a liquid crystal display screen 5, to prepare a display screen module; (2) Take an integral die-cast backlight base plate 62 containing a backlight baffle 61, embed a backlight inner film 63 on one side of the backlight base plate 62, and then insert the backlight boss 64 into the inner side of the backlight baffle 61, fix the backlight inner film 63, and obtain a backlight assembly 6; (3) Double-sided tape is adhered to the backlight boss 64 in the backlight assembly 6, and the side provided with the backlight inner film sheet 63 is connected to the display screen module to obtain a connected product, which is the dimmable rearview mirror display screen film assembly.

[0035] Comparative Example 2 The method and steps are the same as those in Example 1, except that hot melt adhesive is not used, and solid foam adhesive is manually filled in the area between the backlight baffle 61 and the lower surface of the cover plate to prepare a dimmable rearview mirror display screen film group.

[0036] Comparative Example 3 (1) Take a cover plate 1 glass, apply a first optical adhesive 2 on the ink layer on the back thereof, and laminate it to one side of a color-changing liquid crystal dimming layer 3, then apply a second optical adhesive 4 on the other side of the color-changing liquid crystal dimming layer 3, and laminate it to a liquid crystal display screen 5, to prepare a display screen module; (2) Take an integral die-cast backlight base plate 62 containing a backlight baffle 61, embed a backlight inner film 63 on one side of the backlight base plate 62, and then insert the backlight boss 64 into the inner side of the backlight baffle 61, fix the backlight inner film 63, and obtain a backlight assembly 6; (3) Adhere double-sided tape to the backlight boss 64 in the backlight assembly 6, and connect the side provided with the backlight inner film 63 to the display screen module to obtain a connected product; (4) Turn the connected product upside down, with the cover plate 1 facing downward and the backlight assembly 6 facing upward, and use a caliper to measure the width W2 of the backlight baffle 61, the width difference W2 between the cover plate 1 and the liquid crystal dimming layer 3, the height difference H between the cover plate 1 and the backlight baffle 61, the length a of the display module, and the width b of the display module, and calculate the amount of side sealant 7; (5) Take black hot melt adhesive, melt it at 120°C until it flows, and deliver it to the needle through a hose. Then, make the needle dispense adhesive downward obliquely and inject it into the adhesive dispensing area formed by the backlight baffle 61 and the cover plate 1 according to the amount calculated in step (4). During the dispensing process, the needle moves along the four sides of the adhesive dispensing area to evenly fill and bond the backlight baffle 61 and the cover plate 1. Let it stand at room temperature for 4 minutes to complete the curing. (6) The other end of the connected product is cured according to the method described in steps (4) to (5) to obtain a display screen module of a dimmable rearview mirror.

[0037] Results test: The display screen modules of the dimmable rearview mirror prepared in the above embodiments and comparative examples were used to assemble the dimmable rearview mirror, and the appearance was checked to confirm whether there was edge light leakage, other defects that did not meet the appearance requirements, and mechanical impact between the cover plate 1 and the backlight baffle 61 to test the adhesion strength. The results are shown in Table 1: The method of light leakage inspection is as follows: the prepared display screen module is placed on a test stand at an angle of 45° to the horizontal direction, the inspector's eyes are 30±10cm away from the display screen, and the line of sight is perpendicular to the display screen surface within the range of ±45°, and observe whether there is light emitted from the four edges of the display module; if light leakage is visible, the product is judged as a defective product, and if light leakage is invisible, it is a good product; The mechanical shock test method is as follows: the display screen module is fixed on the mechanical shock test bench and subjected to a three-directional shock test; the pulse waveform used is: half-sine, the number of shocks in each direction (±X, ±Y, ±Z) is 10 times, the peak acceleration is: 500 m / s2, and the pulse duration is: 6 ms. After the test is completed, the structure and appearance of the display screen module are checked for any component peeling or breakage, otherwise the test is considered to be successful; The high temperature and high humidity resistance test conditions are: place the display screen module at 60℃ / 90%RH for 1000 hours, and then perform appearance / power-on performance inspection. After the test, if there is no moisture intrusion, display abnormality or other defects in the display screen module, the test is considered to be successful, otherwise the test will fail; Table 1 Performance of display module

[0038] The results are shown in Table 1: By filling the black side sealant between the backlight assembly and the display module, the light leakage defect of the display film group due to the increase in thickness is solved. In addition, the addition of the side sealant enhances the adhesion between the backlight assembly and the display module, significantly improves the resistance to mechanical impact, and improves the resistance to high temperature and high humidity environments.

[0039] The yield of the display screen modules prepared in Example 1 and Example 2 is ≥95%, and the probability of light leakage defects is 0.

[0040] Example 3 Take the display screen module prepared in Example 1, connect the power supply and simulate the transmittance and reflectivity of the display screen module under different voltages: The working voltage of the color-changing liquid crystal dimming layer 3 is adjusted to 15V. At this time, the transmittance of the display module is 78.74% and the reflectivity is 8.13%; The working voltage of the color-changing liquid crystal dimming layer 3 is adjusted to 10V. At this time, the transmittance of the display module is 61.53% and the reflectivity is 20.44%; The working voltage of the color-changing liquid crystal dimming layer 3 is adjusted to 5V. At this time, the transmittance of the display module is 45.92% and the reflectivity is 38.62%; The working voltage of the color-variable liquid crystal dimming layer 3 is adjusted to 0V. At this time, the light transmittance of the display screen module is 21.08% and the reflectivity is 57.46%.

Claims

1. A display screen module for a vehicle interior dimming rearview mirror, characterized in that: It comprises a cover plate (1), a first optical adhesive (2), a color-variable liquid crystal dimming layer (3), a second optical adhesive (4), a liquid crystal display screen (5) and a backlight assembly (6); a side sealing adhesive (7) is provided between the backlight assembly (6) and the cover plate.

2. The display screen module of the in-vehicle dimming rearview mirror according to claim 1, characterized in that: The backlight assembly (6) comprises a backlight blocking wall (61), a backlight bottom plate (62), a backlight inner film (63) and a backlight boss (64).

3. The display screen module of the in-vehicle dimming rearview mirror according to claim 1 or 2, characterized in that: The calculation formula for the amount of the side sealant (7) is (W1+W2)×H / 2×(a+b)×2; wherein W1 is the width of the backlight baffle (61), W2 is the width difference between the cover plate (1) and the liquid crystal dimming layer (3), H is the height difference between the cover plate (1) and the backlight baffle (61); a is the length of the display module, and b is the width of the display module.

4. The display screen module of the in-vehicle dimming rearview mirror according to claim 3, characterized in that: The side sealing glue (7) is hot melt glue or UV curing glue.

5. The display screen module of the in-vehicle dimming rearview mirror according to claim 1, characterized in that: The color-variable liquid crystal dimming layer (3) has an operating voltage of 0-15V and a light transmittance of 0-75%.

6. The display screen module of the in-vehicle dimming rearview mirror according to claim 5, characterized in that: When the operating voltage is 0V, the transmittance is ≤25%; when the operating voltage is 5V, the transmittance is 45±5%; when the operating voltage is 10V, the transmittance is 60±5%; when the operating voltage is 15V, the transmittance is ≥75%.

7. The display screen module of the in-vehicle dimming rearview mirror according to claim 1, characterized in that: The first optical adhesive (2) and the second optical adhesive (4) are OCA optical adhesives with a viscosity of 15-16 N / cm, an optical transmittance of ≥95%, and a thickness of 200-300 μm.

8. A method for preparing a display screen module of an in-vehicle dimming rearview mirror according to any one of claims 1 to 7, characterized in that: The steps include: (1) Assembling a display screen module: using a first optical adhesive (2) to bond the cover plate (1) to the color-changing liquid crystal dimming layer (3); and then using a second optical adhesive (4) to bond the liquid crystal display screen to the color-changing liquid crystal dimming layer (3); (2) Assembling the backlight assembly: placing the backlight inner film (63) on the backlight base plate (62), and backlight baffle walls (62) are provided on both sides of the backlight base plate (61); (3) Assembling the display screen module: Assemble the display screen module and the backlight assembly; (4) Glue sealing: Fix the display screen module vertically, apply glue on both sides, cure, and clean up excess glue to obtain the display screen module of the dimmable rearview mirror.

9. The preparation method according to claim 8, characterized in that: The curing method described in step (4) is static curing or UV irradiation curing.

10. The preparation method according to claim 9, characterized in that: The static curing time is 2-4 minutes, and the light intensity of UV light curing is 2500-4000mj / cm 2 .

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