Filter and optical protective sheet

Abstract

To maintain a display effect while improving a blue light cutting effect.SOLUTION: The present application provides a filter capable of maintaining a display effect while having a high blue light cutting effect, and an optical protective sheet using the filter. The filter is obtained by forming a light absorbing layer in which a plurality of dyes are mixed on a transparent substrate. The light absorbing layer may include a first light absorbing dye and a second light absorbing dye. The first light absorbing dye may absorb greater than or equal to about 50% of blue light of about 435 440nm. The second light absorbing dye may absorb about 40% or more of orange-red light in the range of about 580 nm to about 630nm (central wavelengths of about 590 nm to about 610nm). The present application can absorb the orange-red light near 600nm and directly correct the color temperatures of the blue light cut-off, so there is no need to adjust the three primary colors.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present application relates to blue light blocking technology, and in particular to a filter and optical protective sheet that have a high blue light blocking effect while maintaining display effectiveness. [Background technology]

[0002] In recent years, many research papers have disclosed that blue light in the 400-500 nm wavelength range can cause photochemical damage to the human eye. Different wavelengths of blue light cause different amounts of damage to the human eye, and the International Commission on Non-Ionizing Radiation Protection has published the "Blue Light Hazard (BLH)."

[0003] In 2018, TÜV Rheinland (Germany) released the Blue Light Reduction Standard (Table 1) for BLH, defining standards for blue light toxicity reduction rate, correlated color temperature shift (CCT), and transmittance. The blue light toxicity reduction rate can be calculated by incorporating BLH into the reduction rate integral formula to calculate eye damage caused by blue light. Furthermore, by limiting the color temperature shift, blue light blocking products can prevent their screens from appearing yellowish. Furthermore, by limiting transmittance, blue light blocking products can prevent their screens from appearing too dark. The standard defines three blue light blocking levels: 15%, 20%, and 30%. After years of promotion by TÜV Rheinland, consumers often refer to the blue light blocking standard when selecting screen protectors. This has significantly contributed to improving the quality of blue light blocking screen protectors.

[0004] [Table 1]

[0005] In 2023, TÜV Rheinland of Germany will further update the standard (Table 2), expanding the original three levels to seven levels and adding a standard for the reduction rate for 435-440nm. The new standard will require the highest level of blue light reduction to be 80%, meaning that blue light from 435-440nm must be reduced by 80% or more while maintaining a 40% reduction in blue light toxicity, a color temperature difference of 500K or less, and a brightness of 70% or more.

[0006] [Table 2]

[0007] Figure 1 shows the spectrum of a conventional blue light blocking screen protector. Commercially available absorptive blue light blocking screen protectors use blue light absorbing particles to absorb blue light (blue light absorbing region 10 in Figure 1). However, when blue light is absorbed, the color temperature drops and the screen becomes yellowish. Therefore, it is necessary to use dyes to compensate for the non-blue light band (e.g., red light compensation region 12 or green light compensation region 14 in Figure 1). Increasing the compensation region inevitably affects brightness, leading to a decrease in display quality. Furthermore, compensating for color coverage using the three primary colors requires extensive experimentation, making it difficult to put into practical use.

[0008] Therefore, related manufacturers aim to improve the blue light blocking effect while maintaining the display effect. Summary of the Invention [Problem to be solved by the invention]

[0009] The present application provides a filter that has a high blue light blocking effect while maintaining display effectiveness. [Means for solving the problem]

[0010] In one embodiment, the filter comprises a transparent substrate and a light-absorbing layer formed by mixing multiple dyes. The light-absorbing layer includes a first light-absorbing dye and a second light-absorbing dye. The first light-absorbing dye absorbs 50% or more of blue light in the range of 435 to 440 nm. The second light-absorbing dye absorbs 40% or more of orange-red light in the range of 580 to 630 nm (with a center wavelength of 590 to 610 nm).

[0011] In one embodiment, the first light-absorbing dye absorbs 80% or more of blue light in the range of 435 to 440 nm, and the second light-absorbing dye absorbs 60% or more of orange-red light in the range of 580 to 630 nm (center wavelength 590 to 610 nm).

[0012] The present application also provides an optical protective sheet that has a high blue light blocking effect while maintaining display effectiveness.

[0013] In one embodiment, the optical protective sheet has a transparent substrate. The transparent substrate has a filter made of a light absorbing layer containing a mixture of multiple dyes. The light absorbing layer contains a first light absorbing dye, a second light absorbing dye, and a third light absorbing dye. The first light absorbing dye absorbs 60% or more of blue light in the range of 435 to 440 nm. The second light absorbing dye absorbs 40% or more of orange-red light in the range of 580 to 630 nm (center wavelength: 590 to 610 nm). The third light absorbing dye absorbs 10% or more of green light in the range of 500 to 580 nm.

[0014] To summarize the above, while conventional blue light blocking products require extensive experimentation to correct color coverage using the three primary colors, this application corrects color temperature by absorbing orange-red light in the 580-620 nm range (center wavelength 590-610 nm), and then adds a dye that absorbs green light in the 500-580 nm range, achieving a white balance effect close to the actual color without the need for complex color adjustment. [Brief explanation of the drawings]

[0015] [Figure 1] This is a spectrum diagram of a conventional blue light blocking protector. [Figure 2]FIG. 2 is a spectral diagram of one embodiment of the filter of the present application. [Figure 3] FIG. 10 is a spectral diagram of another embodiment of the filter of the present application. [Figure 4] FIG. 10 is a spectral diagram of another embodiment of the filter of the present application. [Figure 5] FIG. 3 is a spectrum comparison diagram in which FIGS. 1 and 2 are superimposed. [Figure 6] 1 is a schematic diagram of one embodiment of an optical protective sheet of the present application. [Figure 7] FIG. 2 is a schematic diagram of another embodiment of the optical protective sheet of the present application. [Figure 8] FIG. 2 is a schematic diagram of another embodiment of the optical protective sheet of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0016] 2 is a spectrum diagram of one embodiment of the filter of the present application. In this embodiment, the filter is formed by coating a light-absorbing layer containing a mixture of dyes on a transparent substrate. The light-absorbing layer includes a first light-absorbing dye, a second light-absorbing dye, and a third light-absorbing dye.

[0017] For ease of explanation, the spectral diagrams in the drawings are based on the transmittance of light emitted from a light source when it passes through the transparent substrate, with 60% absorption corresponding to 40% transmittance. As shown in FIG. 2, the first light-absorbing dye of the present application absorbs 50% to 79% of the blue light band 20 from 435 to 440 nm (i.e., transmittance of 50% to 21%). The second light-absorbing dye absorbs the orange-red light band 22 from 580 to 630 nm, with a maximum absorption of 40% to 70% (i.e., the minimum transmittance in FIG. 2 is 60% to 30%). Adding a light-absorbing dye that absorbs orange-red light can reduce the color temperature difference.

[0018] In the above embodiment, the color temperature difference of a single light source is controlled to within 500 K. For example, light from a light source with a color temperature of 6500 K is absorbed by the first light absorbing dye, resulting in a yellow color temperature of 5000 K, and the orange-red light is absorbed by the second light absorbing dye, correcting the color temperature to 6000 K to 6500 K. Experiments by the inventors have shown that the absorptivity of the first light absorbing dye in the 435 to 440 nm range is positively correlated with the maximum absorptivity of the second light absorbing dye in the 580 to 630 nm range, with the ratio of the absorptivities being 0.7 to 2.

[0019] FIG. 3 is a spectrum diagram of another embodiment of the filter of the present application. Generally, the wavelength of visible light visible to the human eye is 380 to 780 nm, of which violet-blue light between 380 and 410 nm has the highest energy, followed by blue light. While blue light wavelengths between 400 and 500 nm cause photochemical damage to the human eye, visible violet-blue light between 380 and 410 nm is closest to ultraviolet A, has high energy, and is highly permeable to the skin, reaching the dermis layer. It destroys collagen fibers and elastic fibers, generating unnecessary free radicals, accelerating skin aging and causing melanin production. Therefore, in this embodiment, as shown in FIG. 3, the first light-absorbing dye absorbs 50 to 79% of blue light between 435 and 440 nm, and also absorbs 80 to 100% of the violet-blue light band 24 between 380 and 410 nm (transmittance between 20 and 0%). In FIG. 2, the transmittance in the range of 380 to 440 nm has a valley-like waveform, whereas in FIG. 3, the transmittance in the range of 380 to 440 nm has a slope-like waveform.

[0020] However, reducing the color temperature difference to achieve a better display effect does not necessarily reduce the visual color difference. Even if the color temperature is corrected using a second light-absorbing dye, the wavelengths that the human eye can see are different, so even if the color temperature is the same, the color may differ from what the human eye sees, meaning that color tolerance exists.

[0021] According to the inventor's experiments, after absorbing orange-red light with the second light-absorbing dye of the present application, the white color at a color temperature of 6000K to 6500K after correction still has a visual color difference compared to the original spectrum. To improve this, a third light-absorbing dye is further added to the light-absorbing layer of the present application. The third light-absorbing dye absorbs the green light band 26 from 500 to 580 nm, with a maximum absorption of 10% to 40% (i.e., in Figure 2, the minimum transmittance is 90% to 60%). The maximum absorption of the second light-absorbing dye from 580 to 630 nm is positively correlated with the maximum absorption of the third light-absorbing dye from 500 to 580 nm, with the ratio of the maximum absorptions being 1 to 7.

[0022] As shown in FIG. 3, experimental data from this embodiment reveals that, assuming an overall transmittance of 80% or more, the first light-absorbing dye absorbs approximately 65% ​​of the blue light band 20 around 435 nm (transmittance of approximately 35%). The second light-absorbing dye has a maximum absorption in the orange-red light band 22 around 600 nm, with an absorption rate of approximately 55% (minimum transmittance of approximately 45%). The ratio of the absorption rates of the first light-absorbing dye and the second light-absorbing dye is 1.18. The third light-absorbing dye has a maximum absorption in the green light band 26 around 550 nm, with an absorption rate of approximately 25% (minimum transmittance of approximately 75%). The absorption rate of the second light-absorbing dye is positively correlated with that of the third light-absorbing dye, with the ratio of the two being 2.2. This method effectively reduces the risk of blue light, maintains optical clarity (overall transmittance of 80% or more), and achieves a white balance effect that is close to the actual color.

[0023] The absorption band of the light-absorbing dye is the band in which the material has good absorption properties for any wavelength within the band. However, due to potential overlap with other parts of the spectrum, the absorption may be the absorption of one or more materials combined. For example, the first light-absorbing dye may be a combination of two or more light-absorbing particle materials with absorption between 380 and 500 nm.

[0024] FIG. 4 is a spectral diagram of another embodiment of the filter of the present application. In this embodiment, assuming an overall transmittance of 70% or more, the first light-absorbing dye absorbs 80% to 100% of the blue light band 30 from 435 to 440 nm (transmittance 20% to 0%). To control the color temperature difference within 500 K, the second light-absorbing dye absorbs 60% to 90% of the orange-red light band 32 from 580 to 630 nm (transmittance 40% to 10%). The ratio of the absorptance of the first light-absorbing dye to the absorptance of the second light-absorbing dye is 0.88 to 1.67. As in the previous embodiment, the third light-absorbing dye absorbs 25% to 55% of the green light band 34 from 500 to 580 nm (transmittance 75% to 45%). The ratio of the absorptance of the second light-absorbing dye to the absorptance of the third light-absorbing dye is 1.09 to 3.6.

[0025] Figure 5 is a spectral comparison diagram that overlays Figures 1 and 2. It should be noted that commercially available blue light blocking products, particularly those that use dyes to absorb blue light, focus on color temperature correction after blue light blocking. The spectrum of the three primary colors (red R, green G, blue B, RGB) is adjusted within the target color temperature and acceptable transmittance range so that the color gamut after blue light blocking is as similar as possible to the color gamut (color coverage) before blue light blocking. However, this approach is extremely difficult to implement in practice, requiring not only finding the appropriate dye but also extensive experimentation. As can be seen from the conventional spectrum 40 in Figure 5, the transmittance of the green light band 402 (near 580 nm) is significantly reduced, and there is a large full width at half maximum in the red light band 404 (near 680 nm). This means that the blocked blue color is compensated for (toned) by using different green and red ratios.

[0026] In contrast, the present invention is easier to prepare. As can be seen from the spectrum 42 of the present invention in Figure 5, the absorbance of the first light-absorbing dye in the 435-440 nm range is 40% or more. Furthermore, the second light-absorbing dye can be used to absorb orange-red light within an acceptable color temperature difference (500K or less), allowing for color temperature correction. The ratio of the absorbance of the second light-absorbing dye to the absorbance of the first light-absorbing dye is approximately 1.2. The second light-absorbing dye has a maximum absorption of 55% (minimum transmittance of approximately 45%) in the orange-red light band 420 of 590-610 nm. Finally, by adding a small amount of a third light-absorbing dye that absorbs green light in the 520-580 nm range without significantly changing the color temperature, a white balance effect close to the actual color can be achieved without the need for complex color adjustment.

[0027] The present application can satisfy the 80% standard, which is the highest level set by TÜV Rheinland in Germany for 2023. The experimental data of the present application are shown in Table 3 below.

[0028] [Table 3]

[0029] FIG. 6 is a schematic diagram of one embodiment of the optical protective sheet of the present application. In this embodiment, the optical protective sheet can be used as a screen protector. Examples of screen display products include personal computers, tablets, televisions, and smartphones. As shown in FIG. 6, the optical protective sheet for screen display products includes a filter 60 and a transparent cover 62. The filter 60 is formed by coating or spraying a light-absorbing layer 610 containing a mixture of multiple dyes onto a transparent substrate 600. The transparent cover 62 is attached to the light-absorbing layer 610 via an optical adhesive.

[0030] 7 is a schematic diagram of another embodiment of the optical protective sheet of the present application. The optical protective sheet further includes a silicone adhesive layer 64. The silicone adhesive layer 64 is provided on one side of the transparent substrate 600, opposite the light absorbing layer 610, to attach the optical protective sheet 6 to the screen. In this embodiment, the filter 60 is formed by laminating multiple transparent substrates 600 and multiple light absorbing layers 610.

[0031] In one embodiment, the material of the transparent substrate 600 or the substrate of the transparent cover 62 is made of a material selected from the group consisting of glass, polymethylmethacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), thermoplastic polyurethane (TPU), polyurethane (PU), colorless transparent polyimide (CPI), or other transparent materials.

[0032] 8 is a schematic diagram of another embodiment of the optical protective sheet of the present application. As can be seen from the above embodiment, increasing the absorptivity of the first light-absorbing dye reduces the transmittance, which in turn reduces the brightness of the electronic product, making it necessary to improve the output. For blue light blocking products, especially those that prioritize eye care (e.g., eyeglass lenses or low-transmittance sunglasses), blue light blocking is a priority.

[0033] As shown in Figure 8, in this embodiment, the transparent substrate 80 of the optical protective sheet is a spectacle lens. A light absorbing layer 82 is applied or sprayed on one side of the transparent substrate 80. A protective coating 84 is formed on the other side of the light absorbing layer 82 opposite the transparent substrate 80. UV-blocking sunglasses absorb UV rays using a UV dye, similar to the light absorbing dye. By further mixing a UV dye into the light absorbing layer 82 or protective coating 84, spectacle lenses that simultaneously block blue light and UV rays can be provided.

[0034] Also, in the case of non-semi-finished lenses, the transparent substrate of the optical protection sheet can be formed by die-casting or injection molding the substrate material and the dye in the filter.

[0035] To summarize, the present invention provides a filter and optical protective sheet with high blue light blocking effect by determining the optimal absorbance (e.g., 50% or more) of a first light-absorbing dye in the 430-440 nm wavelength range based on the acceptable transmittance. Then, within an acceptable color temperature difference range (e.g., 350K or 500K), a second light-absorbing dye (where the ratio of the absorbance of the second light-absorbing dye to the absorbance of the first light-absorbing dye is approximately 1.2) is used to absorb orange-red light in the 580-630 nm wavelength range to correct the color temperature. Finally, by adding a small amount of a third light-absorbing dye that absorbs green light in the 520-580 nm wavelength range without significantly changing the color temperature, blue light blocking and a white balance effect that is close to the actual color can be achieved. [Explanation of symbols]

[0036] 10 Blue light absorption region 12 Red Light Compensation Area 14 Filter Correction Area 20, 30 Blue light band 22, 32, 420 Orange-red light band 24 Violet-blue light band 26, 34 Green light band 40 Conventional Spectrum 402 green light band 404 Red Light Band 42 Spectrum of the present application 60 filters 600, 80 transparent substrate 610, 82 Light absorbing layer 62 Transparent cover 64 Silicone adhesive layer 84 Protective Coating

Claims

1. A filter comprising a transparent substrate and a light absorbing layer formed by mixing a plurality of dyes, the light-absorbing layer includes a first light-absorbing dye and a second light-absorbing dye; the first light-absorbing dye absorbs 50% or more of blue light in the range of 435 to 440 nm; the second light-absorbing dye absorbs 40% or more of orange-red light in the range of 580 to 630 nm (center wavelength: 590 to 610 nm); Filter.

2. the band absorptance of the first light-absorbing dye is positively correlated with the band absorptance of the second light-absorbing dye; The filter of claim 1 .

3. a ratio of the band absorptance of the first light-absorbing dye to the band absorptance of the second light-absorbing dye is 0.7 to 2; The filter of claim 2.

4. The first light-absorbing dye has an absorptivity of 80% or more in the wavelength range of 380 to 410 nm. The filter of claim 1 .

5. further comprising a third light-absorbing dye; the third light-absorbing dye absorbs 10% or more of green light in the range of 500 to 580 nm; the band absorptance of the second light-absorbing dye is positively correlated with the band absorptance of the third light-absorbing dye; The filter of claim 1 .

6. the first light-absorbing dye, the second light-absorbing dye, or the third light-absorbing dye includes at least one type of light-absorbing particle; 6. The filter of claim 5.

7. a ratio of the band absorptance of the first light-absorbing dye to the band absorptance of the second light-absorbing dye is 0.7 to 2; a ratio of the band absorptance of the second light-absorbing dye to the band absorptance of the third light-absorbing dye is 1 to 7; 6. The filter of claim 5.

8. A filter comprising a transparent substrate and a light absorbing layer formed by mixing a plurality of dyes, the light-absorbing layer includes a first light-absorbing dye and a second light-absorbing dye; the first light-absorbing dye absorbs 80% or more of blue light in the range of 435 to 440 nm; the second light-absorbing dye absorbs 60% or more of orange-red light in the range of 580 to 630 nm (center wavelength: 590 to 610 nm); Filter.

9. further comprising a third light-absorbing dye; the third light-absorbing dye absorbs 10% or more of green light in the range of 500 to 580 nm; the absorptance of the second light-absorbing dye is positively correlated with the absorptance of the third light-absorbing dye; 9. The filter of claim 8.

10. a ratio of the band absorptance of the first light-absorbing dye to the band absorptance of the second light-absorbing dye is 0.88 to 1.67; a ratio of the band absorptance of the second light-absorbing dye to the band absorptance of the third light-absorbing dye is 1.09 to 3.6; 10. The filter of claim 9.

11. the first light-absorbing dye further absorbs 80% or more of violet-blue light in the range of 380 to 410 nm; 9. The filter of claim 8.

12. An optical protective sheet having a transparent substrate, the transparent substrate has a filter made of a light absorbing layer in which a plurality of dyes are mixed; the light absorbing layer comprises a first light absorbing dye, a second light absorbing dye, and a third light absorbing dye; the first light-absorbing dye absorbs 50% or more of blue light in the range of 435 to 440 nm; the second light-absorbing dye absorbs 40% or more of orange-red light in the range of 580 to 630 nm (with a center wavelength of 590 to 610 nm); the third light-absorbing dye absorbs 10% or more of green light in the range of 500 to 580 nm; Optical protection sheet.

13. The transparent substrate is formed by die-casting or injection molding a substrate material and the plurality of dyes in the filter. The optical protective sheet according to claim 12 .

14. The filter is formed by coating or spraying on one side of the transparent substrate. The optical protective sheet according to claim 12 .

15. It further has a transparent cover, the transparent cover is attached to one side of the filter opposite to the transparent substrate; The optical protective sheet according to claim 14 .

16. The transparent cover further includes an adhesive layer provided on a side opposite to the filter. The optical protective sheet according to claim 15 .

17. a protective coating on one side of the filter opposite the transparent substrate; The optical protective sheet according to claim 14 .

Images