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EP-4737418-A1 - GLASS PLATE AND METHOD FOR PRODUCING SAME, IN-VEHICLE DISPLAY DEVICE, AND METHOD FOR SELECTING GLASS PLATE

EP4737418A1EP 4737418 A1EP4737418 A1EP 4737418A1EP-4737418-A1

Abstract

The present invention relates to a glass plate having a first main surface and a second main surface facing the first main surface, wherein the first main surface has an uneven structure on at least a portion thereof, the visibility index value T on the outermost surface of the region having the uneven structure on the first main surface side is 0.85 or more, the glare index value S is 0.80 or more, the average dynamic friction coefficient COF is 0.50 or less, the friction change amount delta is more than -0.210, and the lightness L* value is 4.7 or less.

Inventors

  • TAMADA MINORU
  • INOUE AICHI

Assignees

  • AGC INC.

Dates

Publication Date
20260506
Application Date
20240613

Claims (19)

  1. A glass plate comprising: a first main surface; and a second main surface opposite to the first main surface, wherein the first main surface has an uneven structure in at least a part thereof, the glass plate has a clarity index value T of 0.85 or more, an anti-sparkle index value S of 0.80 or more, an average dynamic friction coefficient COF of 0.50 or less, and a friction change amount delta of more than -0.210 on an outermost surface of a region having the uneven structure on a first main surface side, the glass plate has a brightness L* value of 4.7 or less in a specular component exclude (SCE) method, as measured by using a method in accordance with ASTM E313-73 standard, and the clarity index value T, the anti-sparkle index value S, the average dynamic friction coefficient COF, and the friction change amount delta are quantified by methods shown below: clarity index value T: SMS-1000 manufactured by DM&S is used, the glass plate is provided at a position 30 mm away from above a slit-shaped white light source having a length of 40 mm and a width of 0.1 mm such that the first main surface side is a light source side, and luminance on the outermost surface of the region having the uneven structure is measured from a second main surface side of the glass plate, a camera lens used is a lens having a focal distance of 16 mm at a diaphragm of 5.6, and a distance from the outermost surface of the glass plate on the first main surface side to the camera lens is set to 550 mm, and when a direction parallel to a thickness direction of the glass plate is defined as an angle θ = 0°, an average value of luminance in a range of the angle θ = 0° ± 0.1° is defined as T 1 , an average value of luminance in a range of the angle θ = 0.7° ± 0.1° is defined as T 2 , and an average value of luminance in a range of the angle θ = -0.7° ± 0.1° is defined as T 3 , a value calculated according to the following equation (1) is defined as the clarity index value T, Clarity index value T = 1 − T 2 + T 3 / 2 × T 1 anti-sparkle index value S: the glass plate is disposed on a display surface side of a display device having a resolution of 264 ppi such that the second main surface is in contact with the display surface side, a sparkle value on the outermost surface of the region having the uneven structure is defined as an anti-sparkle S a , where the sparkle value is determined by image analysis using SMS-1000 manufactured by DM&S provided on the first main surface side of the glass plate in a state where a green monochromatic image composed of RGB (0, 255, 0) is displayed on the display device, a distance d between the SMS-1000 manufactured by DM&S and the outermost surface of the glass plate on the first main surface side is set to 540 mm, and a camera lens used is a lens having a focal distance of 50 mm at a diaphragm of 5.6, in addition, a glass substrate (VRD140 glass, manufactured by AGC Glass Europe) having the same thickness as the glass plate, as a reference sample, is also subjected to image analysis under the same conditions, and the determined sparkle value is defined as an anti-sparkle S s , and a value calculated based on the values of S a and S s according to the following equation (2) is defined as the anti-sparkle index value S, Anti - sparkle index value S = 1 − S a / S s average dynamic friction coefficient COF and friction change amount delta: a dynamic friction coefficient is measured by sliding a pseudo finger at a scanning distance of 50 mm, a load of 100 g, and a scanning speed of 100 mm/sec on the outermost surface of the region having the uneven structure on the first main surface side of the glass plate in an environment of a room temperature of 23°C and a humidity of 21% in a static and dynamic friction measuring machine, a data acquisition frequency is set to 1 kHz, the pseudo finger is made of urethane, and a contact portion with the outermost surface is formed with linear convex portions in a direction perpendicular to a sliding direction at an interval of 0.5 mm in an area of 10 mm × 15 mm, and here, when going back from a time at which the dynamic friction coefficient is at maximum, a time point at which the dynamic friction coefficient is 0 or less for the first time is defined as a movement start time point, and a time point at which the dynamic friction coefficient is 5 or less for the first time after a time point represented by {(the movement start time point) + (0.75 × the scanning distance/the scanning speed)} is defined as a movement end time point, a value calculated according to the following equation (3) is defined as the average dynamic friction coefficient COF, and a value calculated according to the following equation (4) is defined as the friction change amount delta. Average dynamic friction coefficient COF = average value of dynamic friction coefficients at (intermediate time point between the movement start time point and the movement end time point) ± 0.2 seconds Equation (3) Friction change amount delta = (maximum dynamic friction coefficient after the movement end time point) - (the average dynamic friction coefficient COF) Equation (4)
  2. The glass plate according to claim 1, wherein the first main surface further includes an antireflection film on at least a part thereof, the antireflection film covers at least a part of the uneven structure, the glass plate has a luminous transmittance of 20% to 85% measured on an outermost surface of a region having the antireflection film on the first main surface side, the glass plate has a b* value of 5 or less in the region having the antireflection film in a transmitted color under a D65 light source, as measured in accordance with JIS Z 8729 (2004), the glass plate has a luminous reflectance of 1% or less measured on the outermost surface of the region having the antireflection film covering the uneven structure on the first main surface side, and the antireflection film has a sheet resistance of 10 4 Ω/□ or more.
  3. The glass plate according to claim 2, wherein the glass plate has, on an outermost surface of a region having the uneven structure and the antireflection film on the first main surface side, a transmission haze of 15% or more, as measured by a method in accordance with JIS K 7136 (2000).
  4. The glass plate according to claim 2, wherein the antireflection film has a laminated structure in which two or more dielectric layers having different refractive indices are alternately laminated, a main component of each of the dielectric layers in the laminated structure is an oxide of at least one selected from the group consisting of Si, Nb, Ti, Zr, Ta, Al, Sn, and In, or a nitride of at least one of Si and Al, and in at least one of the dielectric layers, fine particles of at least one selected from the group consisting of Ag, Mo, W, Cu, Au, Pd, Pt, Ir, Ni, Co, Fe, Cr, C, TiC, SiC, TiN, and CrN are dispersed.
  5. The glass plate according to claim 2, wherein the antireflection film has a laminated structure in which two or more layers having different refractive indexes are alternately laminated, a main component of at least one layer of the layers in the laminated structure is an oxide of Si, a main component of at least another layer of the layers in the laminated structure is a mixed oxide containing an oxide of at least one selected from the group A consisting of Mo and W and an oxide of at least one selected from the group B consisting of Si, Nb, Ti, Zr, Ta, Al, Sn, and In, and a content of elements in the group B is less than 50 mass% with respect to a total of elements in the group A and the elements in the group B in the mixed oxide.
  6. The glass plate according to claim 2, wherein the glass plate has, on an outermost surface of a region having the uneven structure and the antireflection film on the first main surface side, a roughness curve element average length Rsm of less than 26 µm, an arithmetic average roughness Ra of 0.12 µm or more, a skewness Rsk of -1 to 1, and a kurtosis Rku of 2 to 4 among surface roughness.
  7. The glass plate according to claim 1, wherein the glass plate has, on the outermost surface of the region having the uneven structure on the first main surface side, a transmission haze of less than 15%, as measured by a method in accordance with JIS K 7136 (2000).
  8. The glass plate according to claim 7, wherein the glass plate has, on the outermost surface of the region having the uneven structure on the first main surface side, a roughness curve element average length Rsm of 26 µm or more, a skewness Rsk of -4 to -1.5, and a kurtosis Rku of 5 to 20 among surface roughness.
  9. The glass plate according to claim 7, wherein the first main surface further includes an antireflection film on at least a part thereof, the antireflection film covers at least a part of the uneven structure, the antireflection film has a laminated structure in which two or more layers of a low refractive index layer and a high refractive index layer are alternately laminated, and a main component of the high refractive index layer is at least one selected from the group consisting of SiN, TiO 2 , Nb 2 O 5 , Ta 2 O 5 , and ZrO 2 .
  10. The glass plate according to any one of claims 1 to 9, further comprising: a printed layer on at least a part of the second main surface.
  11. The glass plate according to any one of claims 1 to 9, wherein the glass plate is a chemically strengthened glass.
  12. The glass plate according to any one of claims 1 to 9, which is for use in a cover glass of an in-vehicle display device.
  13. An in-vehicle display device comprising: a cover glass made of the glass plate according to claim 12; and a display panel.
  14. A method for producing a glass plate, which is a method for producing the glass plate according to any one of claims 1 to 9 having the first main surface and the second main surface opposite to the first main surface, the method comprising: forming the uneven structure on at least a part of the first main surface.
  15. The method for producing a glass plate according to claim 14, wherein the formation of the uneven structure includes immersing the glass plate in a solution containing potassium fluoride and hydrogen fluoride and then immersing the glass plate in a solution containing hydrogen fluoride, and the method further includes forming an antireflection film to cover at least a part of the uneven structure.
  16. The method for producing a glass plate according to claim 14, wherein the formation of the uneven structure includes spraying a slurry onto the first main surface of the glass plate to roughen the first main surface, and then immersing the glass plate in a solution containing hydrogen fluoride to etch the glass plate.
  17. The method for producing a glass plate according to claim 16, wherein a spray angle of the slurry is 70° or less with respect to the first main surface.
  18. The method for producing a glass plate according to claim 16, wherein the formation of the uneven structure includes immersing the glass plate in a solution containing potassium fluoride and hydrogen fluoride and then immersing the glass plate in a solution containing hydrogen fluoride, and the method further includes forming an antireflection film to cover at least a part of the uneven structure.
  19. A method comprising selecting the glass plate according to any one of claims 1 to 9.

Description

TECHNICAL FIELD The present invention relates to a glass plate, a method for producing the same, an in-vehicle display device, and a method for selecting a glass plate. BACKGROUND ART In general, a cover composed of a transparent substrate such as a glass plate is disposed on a display surface side of a display device such as a liquid crystal display (LCD) device in order to protect the display device. However, in the case where such a transparent substrate is provided in the display device, when a display image on the display device is visually recognized through the transparent substrate, reflected glare of an object placed in the periphery may often occur. When such reflected glare occurs on the transparent substrate, a viewer of the display image may find it difficult to visually recognize the display image and furthermore may receive an unpleasant impression. In particular, in a cover glass of an in-vehicle display device, a distance between a driver and the display device is fixed. Therefore, when a strong light source such as sunlight is reflected, it becomes very difficult to visually recognize the display image, and necessary information cannot be read, which is likely to hinder driving. Therefore, in order to prevent such reflected glare, for example, a method of performing an antiglare treatment of forming an uneven shape on a surface of the transparent substrate has been adopted. With respect to this, Patent Literature 1 discloses a method of evaluating reflected glare in a display device by using a special device. However, optical properties required for the cover glass or the like in the in-vehicle display device are not limited to reduction of the reflected glare. That is, the cover glass in the in-vehicle display device is required to have optical properties at predetermined levels in terms of resolution or clarity, reflection image diffusiveness, anti-sparkle, and the like. Therefore, when selecting a transparent substrate such as a glass plate, it is insufficient to consider only one of the optical properties, and it is often necessary to consider a plurality of optical properties at the same time. Therefore, Patent Literature 2 discloses that when evaluation is performed by using three index values of a resolution index value T, a reflection image diffusiveness index value R, and an anti-sparkle index value S, once these index values satisfy specific ranges, a glass plate having resolution, reflection image diffusiveness, and anti-sparkle prevention properties suitable for an in-vehicle display device can be obtained. In addition, Patent Literature 3 discloses that when a transmission haze satisfies a specific range in addition to a clarity index value T, a reflection image diffusiveness index value R, and an anti-sparkle index value S, a glass plate also having excellent color reproducibility can be obtained. CITATION LIST PATENT LITERATURE Patent Literature 1: JP 2007-147343APatent Literature 2: JP 5867649BPatent Literature 3: JP 7067077B SUMMARY OF INVENTION TECHNICAL PROBLEM With respect to the above, the cover glass or the like in the in-vehicle display device is not only used for visual recognition but also for touching as a touch panel, and the opportunity is expected to increase in the future. As an index for evaluating a sense of touch in the touch panel, for example, as disclosed in Non-Patent Literature 1, an arithmetic average roughness or a dynamic friction coefficient is used. However, according to the studies of the present inventors, it is found that the above arithmetic average roughness or dynamic friction coefficient alone is insufficient as index for an actual sense of touch. Therefore, the present inventors have particularly focused on a swipe operation and have studied a new method for quantitatively evaluating the sense of touch. Accordingly, an object of the present invention is to provide a glass plate having an excellent sense of touch during a swipe operation while maintaining suitable clarity, and a method for producing the same. Another object of the present invention is to provide an in-vehicle display device using the above glass plate and a method for selecting the above glass plate. SOLUTION TO PROBLEM As a result of intensive studies on the above problems, the present inventors have conceived that, during the swipe operation, in addition to a dynamic friction coefficient, a friction change at an end portion when the swipe is stopped is important, and have completed the present invention. In addition, they found the fact that the shape of the outermost surface of the glass plate is important in order to realize a desired friction change, and found a method for realizing the shape. That is, the present invention relates to the following [1] to [19]. [1] A glass plate including: a first main surface; anda second main surface opposite to the first main surface, in whichthe first main surface has an uneven structure in at least a part thereof,on an outermost s