TW202331373A - Backlight unit with emission modification - Google Patents

Abstract

A display system and method are disclosed that includes an electronic display device and a backlight comprising a light-emitting array, a reflector adjacent to the light-emitting array, a diffuser opposite the reflector, a first brightness enhancing layer adjacent the diffuser, and an optical film that includes at least one light conversion material or at least one light conversion material. The light conversion or light absorbing material is structured and configured to reduce hazardous blue light emissions between about 400 nm to about 500 nm. The disclosed display device can include a liquid crystal panel configured to control transmission of light from the backlight to a viewer. The display device also includes one or more optical films that incorporate one or more light conversion or light absorbing materials. The optical films can be positioned between the layers of the disclosed display device and give enhanced blue-light absorption to the display device.

Description

Backlight unit with emission modification

Cross References to Related Applications

This patent application requests U.S. Patent Application No. 17/348,570, filed February 17, 2021 (now U.S. Patent No. 11,126,033, issued September 21, 2021) and U.S. Patent Application No. 1, filed June 15, 2021 17/348,570, the entire disclosure of which is hereby incorporated by reference.

This case relates to a backlight module for an electronic display system, the backlight module includes light conversion and/or light absorption materials.

Handheld, tablet, computer and other device displays have moved towards higher resolution and more realistic color balance. While resolution and color can be achieved using a variety of methods, many high-performance displays include LEDs that produce high-order blue in the output spectrum. Many of these devices are battery powered, and users typically expect long battery life. Longer battery life generally requires low power consumption, and various means for light conservation. Typically, these displays generally do not prioritize eye safety as a design goal. A growing body of medical research suggests that the "toxic" blue part of the color spectrum may have adverse effects on the eyes, making it possible to cause vision impairment in the long run. Additionally, a new body of knowledge suggests that certain parts of the light spectrum may have adverse effects on an individual's natural circadian rhythm. This case describes materials that are highly selective in their ability to reduce exposure to harmful blue and UV light and the incorporation of these materials in mobile devices, tablet or PC displays. These materials can be optimized based on wavelength to maintain the color white point. Many of these materials reduce the overall light transmission. However, as described in this case, some of these materials can convert or recycle harmful portions of the spectrum into harmless optical wavelengths. In this way, a balance can be struck between reducing unwanted color frequencies, maintaining optical clarity, and maintaining true white color balance with minimal loss of display brightness. Given recent medical discoveries, the increasing ubiquity of displays, and consumer demand for high-quality displays, the system in this case uniquely addresses multiple needs.

To address eye safety concerns, display systems that incorporate materials into mobile device, tablet or PC displays that reduce exposure to harmful or toxic blue and UV light are provided. This case provides a backlight module (unit) for a display system, which includes the ability to convert or recycle harmful parts of the visible electromagnetic spectrum into less harmful optical wavelengths, while maintaining the reduction of harmful color frequencies, maintaining optical clarity and A balance that maintains true white color balance while minimizing loss of display brightness.

In one aspect, a display system for use with an electronic display device is disclosed, the display system includes the electronic display device and a backlight unit, and the backlight unit includes a light emitting array. A reflector can be adjacent to the light emitting array, and a diffuser can be positioned opposite the reflector. The first brightness enhancing layer can be adjacent to the diffuser. The disclosed backlight unit may include an optical film having at least one light converting material or at least one light absorbing material. In some embodiments, at least one light converting material may be used in combination with at least one light absorbing material to reduce harmful blue light emission between about 400 nm and about 500 nm. In some embodiments, at least one light converting material can be quantum dots or luminescent nanoparticles. In some other embodiments, the disclosed backlight unit can include a light guide plate having an edge, a bottom surface, and a top surface, and the light emitting array can be constructed and arranged to inject light into the light guide plate. The disclosed backlight unit may further include a reflector adjacent to the bottom surface of the light guide plate and opposite the diffuser, a second brightness enhancing layer adjacent to the first brightness enhancing layer, and a polarizer adjacent to the second brightness enhancing layer. filter.

In another aspect, a method of enhancing blue light absorption (about 400 nm to about 500 nm) in a backlight unit is disclosed, the method comprising providing a display device for use with an electronic display device, the display device comprising an electronic display device and a backlight unit , the backlight unit includes an optical stack. The backlight unit may include a light emitting array, a reflector adjacent to the light emitting array, a diffuser opposite the reflector, and a first brightness enhancing layer adjacent to the diffuser. The method also includes inserting an optical film having at least one light converting layer or at least one light absorbing layer into the optical stack adjacent to the first brightness enhancing layer. In some embodiments, at least one light converting material can be quantum dots or luminescent nanoparticles. In some embodiments, at least one light converting layer may be used in conjunction with at least one light absorbing layer to reduce harmful blue light emission between about 400 nm and about 500 nm.

In this case,

The term "light-absorbing material" or "light-absorbing layer" refers to an optical film that only absorbs light within a specific wavelength range;

The term "light converting material" or "light converting layer" refers to an optical film that absorbs light in one wavelength range and re-emits light in a higher wavelength range; and

The term "optical film" refers to a layer of light-absorbing or light-converting material, which may be neat, or may be disposed on a transparent carrier layer.

The features and advantages of the present invention will be more readily understood from the following detailed description, which should be read in conjunction with the accompanying drawings.

Various embodiments will be described in detail with reference to the accompanying drawings. References to various embodiments do not limit the scope of the appended claims. Additionally, any examples set forth in this specification are not intended to be limiting and merely set forth some of the many possible embodiments for the appended claims. It should be understood that various omissions and substitutions of equivalents are contemplated where circumstances may suggest or provide modifications, but such omissions and substitutions are intended to cover applications or embodiments without departing from the spirit or scope of the appended claims. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting.

1 is a schematic cross-sectional view of an example display system 100 with which the system of the present disclosure may be beneficially used. Display system 100 may be used in, for example, a liquid crystal display (LCD) monitor, LCD-TV, handheld device, tablet computer, laptop computer, or other computing device. However, display system 100 of FIG. 1 is exemplary only, and the system of the present application is not limited to use with systems similar or similar to system 100 . The system of the present application can be beneficially used in other kinds of display systems not necessarily involving liquid crystal display technology.

A display system according to the present application may comprise a backlight unit comprising an optical stack. The disclosed optical stacks can include light emitting systems such as light emitting diodes, light emitting diode arrays, or other sources of substantially white light. These optical stacks can include optical film layers that can pass light transparently or that can modify the properties of light passing therethrough. This can include reflective layers, diffusing layers, brightness enhancing layers (often prismatic) and polarizing filters, just to name a few. In some embodiments, an optical stack can include at least one optical film having at least one light converting layer therein. Additionally, also at least one optical film may have a light absorbing layer thereon or in it. Alternatively, the optical stack may include at least one optical film having at least one light converting material and at least one optical film having at least one light absorber disposed thereon or therein.

Display system 100 may include a liquid crystal (LC) panel 150 and an illumination assembly 101 positioned to provide illumination light to LC panel 150 . The LC panel 150 includes an LC layer 152 disposed between panel sheets 154 . The sheets 154 may include electrode structures and alignment layers on their inner surfaces for controlling the alignment of liquid crystals in the liquid crystal layer 152 . These luminaires can be arranged to define LC panel pixels. Color filters may also be included in one or more of the plates 154 for imparting color to the image displayed by the LC panel 150 .

LC panel 150 may be positioned between upper absorbing polarizer 156 and lower absorbing polarizer 158 . The combined absorbing polarizers 156, 158 and LC panel 150 can control the transmission of light from the illumination assembly 101 to a viewer positioned generally toward the top of FIG. 1 and looking generally downward at the display system 100 (relative to FIG. ). The controller 104 can selectively activate the pixels of the LC layer 152 to form the image seen by the viewer.

One or more optional layers 157 may be positioned over upper absorbing polarizer 156, eg, to provide optical functionality and/or mechanical and/or environmental protection to the display.

The lighting assembly 101 can include a backlight 108 and one or more light management films 140 positioned between the backlight 108 and the LC panel 150 . Backlight unit 108 may be used to collect light from light source 112 and redirect it toward the front of display system 100 . Backlight 108 of display system 100 may include light source 112 that generates light that illuminates LC panel 150 . Light source 112 may include any suitable lighting technology. In some embodiments, light source 112 may be a light emitting diode (LED), and in some cases, a white LED. The backlight 108 as shown may be a "direct-lit" backlight in which the array of light sources 112 is positioned behind the LC panel 150 substantially across most or all of the panel's area. However, the backlight 108 as shown is merely illustrative and many other backlight configurations are possible. Some display systems may include, for example, an "edge-lit" backlight having one or more sides of a light guide plate that may distribute light from the light source substantially over most or all of the area of the LC panel 150. A light source (such as an LED) at the side.

In some embodiments, the backlight 108 emits substantially white light, and the LC panel 150 is combined with a matrix of color filters to form multicolor pixel groups such that the displayed image is multicolor.

The backlight 108 also includes a reflective substrate 102 for reflecting light from the light source 112 traveling in a direction away from the LC panel 150 . Reflective substrate 102 may also be used to recycle light within display system 100 . In some embodiments, light emitting arrays are contemplated. Such light-emitting arrays may include a matrix of aligned light-emitting diodes, which in some embodiments may have embedded therein reflectors or individual reflectors and one or more diffusers. In these embodiments, the reflector and/or diffuser layer may not be a separate layer in the optical stack, but part of the light emitting array.

An arrangement 140 of light management films, which may also be referred to as a film stack, backlight film stack, or light management unit, may be positioned between the backlight 108 and the LC panel 150 . The light management film 140 can affect the illumination light propagating from the backlight 108 in order to improve the operation of the display system 100 . Light management unit 140 does not have to include all of the components shown and described herein.

The arrangement 140 of light management films may include the diffuser 120 . The diffuser 120 may diffuse light received from the light source 112 , which may result in improved uniformity of illumination light incident on the LC panel 150 . Diffuser layer 120 may be any suitable diffuser film or plate. As shown in FIG. 5 , the diffuser may include three basic layers: an anti-blocking layer 502 , a base layer 504 , and a diffusing layer 506 . The base layer 504 may be composed of polyethylene terephthalate (PET) or any other suitable polymer substrate, and the base layer may be extruded. Anti-blocking layer 502 and diffusing layer 506 may be layers coated on the base layer. Light can enter the diffuser through the anti-blocking layer 502 and exit through the diffusing layer 506 .

The light management unit 140 may include a reflective polarizer 142 . Light source 112 typically produces unpolarized light, but lower absorbing polarizer 158 transmits only a single polarization state; therefore, about half of the light produced by light source 112 is not transmitted through LC layer 152 . However, reflective polarizer 142 may be used to reflect light that would otherwise be absorbed in lower absorbing polarizer 158 . Thus, this light can be recycled by reflection between reflective polarizer 142 and the underlying display components, including reflective substrate 102 . At least some of the light reflected by reflective polarizer 142 may be depolarized and then returned to reflective polarizer 142 in a polarization state that is transmitted through reflective polarizer 142 and lower absorbing polarizer 158 to LC layer 152 . In this way, reflective polarizer 142 can be used to increase the portion of light emitted by light source 112 that reaches LC layer 152, thereby providing a brighter display output. Any suitable type of reflective polarizer may be used for reflective polarizer 142 .

In some embodiments, a polarization control layer 144 may be disposed between the diffuser plate 120 and the reflective polarizer 142 . Polarization control layer 144 may be used to alter the polarization of light reflected from reflective polarizer 142 such that an increased portion of recycled light is transmitted through reflective polarizer 142 .

The arrangement 140 of light management films may also include one or more brightness enhancing layers. The brightness enhancing layer may include surface structures that redirect off-axis light into a direction closer to the axis of the display. This increases the amount of light that travels on-axis through the LC layer 152, thereby increasing the brightness of the image seen by the observer. One example of a brightness enhancing layer is a prismatic brightness enhancing layer, which has a plurality of prismatic ridges that redirect illuminating light by refraction and reflection. An example of a prismatic brightness enhancing layer includes BEF Prismatic Film available from 3M Company. Other kinds of brightness enhancing layers may encompass non-prismatic structures.

The exemplary embodiment shown in FIG. 1 illustrates a first brightness enhancing layer 146 a disposed between reflective polarizer 142 and LC panel 150 . Prismatic brightness enhancing layer 146a generally provides optical gain in one dimension. An optional second brightness enhancing layer 146b may also be included in the arrangement of light management layers 140, with its prismatic structure oriented orthogonally to the prismatic structure of the first brightness enhancing layer 146a. This configuration provides an increase in the optical gain of the display system 100 in two dimensions. In other exemplary embodiments, brightness enhancing layers 146 a , 146 b may be positioned between backlight 108 and reflective polarizer 142 .

The different layers in light management unit 140 may be independent. In other embodiments, two or more layers in light management unit 140 may be laminated together. In other exemplary embodiments, light management unit 140 may include two or more subgroup components.

It should be understood that, as a schematic illustration, the components of the display system 100 are not shown to scale and are generally shown with greatly exaggerated thicknesses (in the up-down direction of FIG. 1 ) compared to their lateral extent (in the left-to-right direction). Many of the elements of display system 100, including (but not necessarily limited to) 102, 120, 142, 144, 146a, 146b, 152, 154, 156, and 157, can be formed in a substantially normal to their thickness (i.e., perpendicular to the plane of FIG. ) in two dimensions spanning an area approximately equal to the viewable area of the display which may be referred to as the "display area".

Returning to the backlight 108, in some embodiments the light source 112 may emit significant amounts of light in potentially harmful wavelength ranges such as the UV and blue light ranges (especially below about 455nm). In a display system 100 that does not include the system of the present application, a significant amount of this potentially harmful light may be emitted by the display system 100 toward the user (upward with respect to FIG. 1 ). In this context, a "significant" amount of light may mean an amount of light that may cause adverse health effects to a user of the display. In view of this danger, the present application provides a system for reducing the amount of harmful blue light emitted from a display system such as system 100 .

In some approaches for mitigating the hazards of blue light emissions from electronic device displays, absorbing materials may be used to reduce the amount of light reaching a user's eyes in certain wavelength ranges, such as the UV and blue light wavelength ranges. Some of these solutions are described in U.S. Patent Application Serial No. 14/719,604, filed May 22, 2015, entitled "LIGHT EMISSION REDUCING FILM FOR ELECTRONIC DEVICES," filed May 22, 2015. Patent Cooperation Treaty-compliant International Patent Application No. PCT/US2015/032175 filed on June 22 and titled LIGHT EMISSION REDUCING FILM FOR ELECTRONIC DEVICES and filed on June 14, 2016 PCT Patent Application Serial No. PCT/US2016/037457, entitled "LIGHT EMISSION REDUCING COMPOUNDS FOR ELECTRONIC DEVICES", which applications are incorporated by limited reference so as not to be incorporated herein The explicit disclosure of the opposite theme.

Methods for blue light emission mitigation based on light absorption (or otherwise removal of light) without subsequent emission of light in the visible region of the electromagnetic spectrum are generally likely to result in The (measured and/or perceived) brightness of the display is reduced. In some cases, to compensate for this absorption-related decrease in brightness, the power input to the display (relative to the power input to the reference display) may be increased. In general, an increase in display power consumption may be undesirable, especially in portable devices where it may negatively impact battery life.

In this case, a system for modifying light emitted from a display is disclosed wherein a light converting or light absorbing material may be used remote from a light source of the display, such as light source 112 of FIG. 1 . Light converting materials typically absorb light in a first wavelength range and emit light in a second wavelength range (thereby "converting" light from one wavelength range to another). Light-absorbing materials absorb light in a range of wavelengths. In this case, the conversion from shorter wavelengths to longer wavelengths may be referred to as "up-conversion" and the conversion from longer wavelengths to shorter wavelengths may be referred to as "down-conversion". It should be recognized, however, that these definitions may not be universal, and that other notations may define up-conversion and down-conversion in reverse (eg, some notations may define such terms in relation to frequency, while frequency is inversely proportional to wavelength).

Systems using light-converting materials from light sources remote from the display can be used to absorb light in less useful or harmful wavelength ranges such as the UV and blue light ranges (especially below about 455nm) and re-emit light that may be more useful in (from health point of view) light in a more temperate wavelength range, such as in the green and/or red wavelength range. In some cases, light can be up-converted from shorter blue wavelengths (around 455nm or lower) to longer blue wavelengths that are less harmful and can also be used for display illumination. In ways such as these, systems using light converting materials remote from the light source can modify the emission of light from a display system relative to display systems that do not employ such light converting materials.

In some examples, systems using light-converting materials or light-absorbing materials that are remote from the light source of the display can be used with electronic device displays to mitigate blue light emissions such that the resulting display system can achieve the same results as those without light-converting materials or light-absorbing materials that are remote from the light source. Comparable brightness of the reference display of the layer, while consuming no more than 10% of the power of the reference display.

Systems using light-converting or light-absorbing materials remote from the light source can improve the color balance of the display compared to some known prior methods of reducing blue light emissions from displays that do not employ light-converting or light-absorbing materials remote from the light source. Some such known prior methods can reduce blue light emission by absorbing or otherwise removing a portion of the blue light from the spectrum, thereby altering the spectral balance of the light emitted from the display. In the system of the present case, in addition to reducing the amount of harmful blue light emitted from the electronic display device, the light-converting material located away from the light source can Re-emitting light may contribute to, account for, or otherwise improve the color balance of light emitted from the electronic display device. In some embodiments, a display system including the system of the present application incorporates a light converting material or a light absorbing material remote from the light source to maintain a D65 white point. In some embodiments, a display system comprising the system of the present invention incorporating light converting material or light absorbing material remote from the light source can maintain a correlated color temperature (CCT) substantially the same as a reference display system without the blue light mitigation system of the present invention.

In some embodiments of the systems of the present application, at least one light converting material may be used in combination with at least one light absorbing material to reduce unwanted blue light emission from the display system and improve or maintain the color balance of the display system.

The system of the present invention may include a variety of light converting materials or light absorbing materials that can absorb light from multiple wavelength ranges, including wavelength ranges other than the UV or blue wavelength ranges.

In some embodiments, the systems of the present invention may employ light-converting or light-absorbing materials that absorb light from wavelength ranges not considered to pose health risks. Absorption and emission of such light converting or light absorbing materials can be employed, for example, to improve or otherwise contribute to the color balance of a display.

Any suitable light converting or light absorbing material may be used in the present system. Without limitation, light converting/absorbing materials employed may include: -organic material – Inorganic materials, which may be mined materials – Raman scattering materials – Anti-Stokes material –Materials for other non-display applications such as fingerprint dust removal - Fluorescent pigments, such as those available from the company DayGlo Color (eg, DAYGLOA-594-5). Surprisingly, materials normally used in applications requiring fluorescent behavior can be used in light filtering applications with high spectral efficiency. - Luminescent nanocrystals, such as SUNSTONE Luminescent UCP Nanocrystals available from Sigma Aldrich Ltd.

Organic light converting and light absorbing materials may include, for example, fluorescent or phosphorescent molecules, organic light emitting semiconductors (eg OLEDs), and polymers including fluorescent or phosphorescent chromophores. Inorganic materials may include, for example, fluorescent or phosphorescent molecules, Raman scattering materials, anti-Stokes materials, fluorescent or phosphorescent pigments, luminescent nanocrystals, and quantum dots.

Raman scattering materials are light scattering materials that absorb photons, emit or absorb phonons, and finally emit photons. In the case of phonon emission, this procedure is called "Stokes", while phonon absorption is called "anti-Stokes". In anti-Stokes materials, the energy absorbed by the phonons is greater than the energy required for the emitted photons to occur at high temperatures in these materials. These materials are described, for example, in Cantarero "Raman scattering applied to materials science", Procedia Materials Science, 9 (2015) pp. 113-122, which is incorporated by reference This article.

Quantum dots (luminescent nanocrystals) are semiconductor particles with a size of a few nanometers, whose optical and electronic properties differ from larger particles due to quantum mechanical effects. The optoelectronic properties of quantum dots can vary depending on size, shape, composition and structure (solid or hollow).

In some embodiments of the present system, the light converting material and/or the light absorbing material may be located at any suitable location remote from the light source of the display. In some embodiments, light converting material and/or light absorbing material may be included in one or more films in light management film 140 and/or in one or more other films not shown in FIG. on or included with the membrane. In general, a light converting material can re-emit light with a different directionality and/or polarization than light absorbed by the light converting material. Thus, in some embodiments, light converting material may be included below (relative to the orientation of FIG. 1 ) reflective polarizer 142 and/or one or more of brightness enhancing layers 146a, 146b such that Prior to display, light is re-emitted through films 142, 146a and 146b (if such films are present in the display system). However, this is not limiting, and the light converting material could potentially be located in, on, or with any component of the light management film 140 .

In some embodiments of the present system, the light converting material and/or the light absorbing material may be included in, on, or in conjunction with a display layer (such as layer 157 of FIG. 1 ) between the LC layer 152 and the user. The display layer is included together. In some embodiments of the present system, light converting material and/or light absorbing material may be included in, on, or with reflective substrate 102 .

In some embodiments of the system of the present invention, light converting material and/or light absorbing material may be included in, on, or in conjunction with a diffuser layer (such as diffuser layer 120 or 216). layer is included together. As previously mentioned, the diffuser layer may include an anti-blocking layer, a base layer, and a diffusing layer. Accordingly, the light converting material and/or the light absorbing material may be included in an anti-blocking or diffusing layer which may be applied to a polymeric substrate layer (such as but not limited to a PET substrate) superior. This configuration is a way to separate the light converting/absorbing layer from other layers in the stack. Alternatively, light converting material and/or light absorbing material may be included in the base layer prior to coating with the anti-blocking layer and diffuser layer. For example, a light converting material and/or a light absorbing material can be mixed with a polymer resin and then extruded into a film.

In some embodiments of the system of the present application, when included or provided in a film of light management film 140, reflector 102 or another layer (such as layer 157), the film of light management film 140, reflector 102 or When included or provided on another layer or with the film of the light management film 140, the reflector 102 or another layer, the light converting material or light absorbing material can be distributed substantially over the entire area corresponding to the display area of the display around. In some such embodiments, the light converting material or light absorbing material can be substantially evenly distributed over this area.

Light converting material or light absorbing material may be included or provided in any suitable manner in the film of light management film 140, reflector 102 or another layer (such as layer 157), the film of light management film 140, reflector 102 or Included or provided on or with the film of the light management film 140, the reflector 102, or another layer. In some embodiments, light converting material or light absorbing material may be extruded, cast or diffused within the film along with it. In some embodiments, a light converting material or a light absorbing material may be coated onto the film. In some embodiments, the light converting material or the light absorbing material may be included as a separate film layer or coated on any of the layers making up the backlight unit. In some embodiments, light-converting or light-absorbing materials may be provided in or with an adhesive used to bond or laminate one or more layers of a display system, such as any suitable layer or film of display system 100. Binder provided together. Such adhesives incorporating light-converting or light-absorbing materials may be substantially optically transparent, exhibiting transmission through the adhesive in addition to light redirection associated with absorption and re-emission of the light-converting material. The scattering of light is negligible.

In some embodiments, the light-converting material or light-absorbing material may be distributed or dispersed, soluble or insoluble, throughout a material (such as a polymeric resin or adhesive) that is a component or precursor to any suitable film or layer of the display system 100. agent). In some embodiments, light-converting or light-absorbing materials may include nanoparticles, some of which may be insoluble in polymers and common solvents. While uniform distribution may be easier to achieve in some systems with soluble light converting/absorbing materials, non-uniform distributions can be achieved with insoluble light converting/absorbing materials with proper handling during fabrication.

In some embodiments, the light-converting or light-absorbing material can be index-matched to the material or medium with which it is combined such that the light-converting or light-absorbing material can absorb and re-emit light in wavelength ranges other than the range in which they absorb and re-emit light. The interior appears substantially optically "invisible," and the film or other material incorporating the light converting/absorbing material appears substantially optically transparent. In some other embodiments, the difference in refractive index between the light-converting material, the light-absorbing material, and the materials or media combined therewith can be used for other optical functions, such as (but not necessarily limited to) diffusion and reflection. Reflectance matching or reflectance tuning can be affected by making inorganic nanoparticles suitably small and chemically coupling them to an organic binder. Likewise, the design of the organic molecules themselves can be tuned for reflectivity. For example, silicones tend to have relatively low optical reflectance, while complex hydrocarbons tend to have relatively high optical reflectance. Organofunctional ligand ends can modify the reflectivity of the adhesive.

The present system incorporating light-converting or light-absorbing materials can be custom designed to retrofit into existing display systems, where selectable design parameters include light-converting materials, light-absorbing materials, and other non-converting light blocking or filtering compounds choose. In other examples, new display systems can be designed that employ systems of the present application incorporating light converting and/or light absorbing materials. Through judicious selection of LEDs (and/or other light sources), light-converting materials, light-absorbing materials, and other non-converting light-shielding or filtering compounds, and other optical films and devices, a combination of approaches can be developed to provide solutions for eye health problems. While providing a display with high display quality.

Figure 2 is a schematic cross-sectional view of an embodiment of a backlight unit according to the present application, indicating where a light converting or light absorbing (blue filter) layer may be inserted. The backlight unit 200 includes a light guide plate 202 . Typically, a light guide is a block of transparent or translucent colorless material (glass or polymer) that transmits light. Light guides can be made from many materials such as glass, polyacrylate (acrylic), polycarbonate, or other transparent polymers. The light emitting diode array 204 arranged in stripes as a light source may be arranged such that light 205 may enter the backlight unit 200 through one edge of the light guide plate 202 . Alternatively, the LED array 204 can be located under the light guide plate 202 . The light guide plate 202 may have a reflector 206 adjacent thereto at one or more sides to direct light from the LED array 204 upward (as shown in FIG. 2 ) and through the backlight unit 200 . In addition, light in the backlight unit 200 can be reflected from the reflector 206 and on the edge of the light guide plate 202 due to the refractive index difference between the light guide plate and air and reflection from the reflector and parts of the backlight unit to be described. The internal reflection of will distribute itself uniformly across the light guide plate 202. A light guide plate can be placed between the reflector and the diffuser. The effect of this type of construction (shown in Figures 1 and 2) is to redirect the light from the light source at the edge of the display screen so that it is spread evenly over the display surface, such as the layers in Figure 1 157 or the upper surface of layer 212 in FIG. 2 . The uniformity of light distribution and the efficiency of light collection (the amount of light reaching the display surface versus the amount of light entering the light guide from the light source) is related to the efficiency of the light guide, reflector layer and one or more diffuser layers.

As shown in FIG. 2 , a diffuser 216 may be disposed adjacent to the light guide plate 202 . Diffuser 216 can evenly distribute light and eliminate bright spots. Diffusers are available in various types such as holographic white diffuser glass and frosted glass, for example. Diffusers can be translucent and reflect light in many different directions. The first brightness enhancing layer 213 and the second brightness enhancing layer 214 may be prismatic brightness enhancing films. The prismatic brightness enhancing film was described in an earlier part of this case. Adjacent the second brightness enhancing layer 214 may be one or more polarizing filters 212 that pass light of a particular polarization while blocking light waves of other polarizations. In some embodiments, polarizing filters can help reduce reflections and glare by filtering out light that becomes polarized due to reflections from non-metallic surfaces. The goal of the backlight unit 200 is to uniformly distribute light on the two-dimensional plane of the light guide plate 202, thereby providing light to display images on the entire display.

The disclosed backlight unit with emission modification also includes an optical film that includes at least one light converting material or at least one light absorbing material or both. A light converting material or a light absorbing material can absorb light in a first wavelength range and re-emit light in a second wavelength range having a higher wavelength. In the present case, light-converting or light-absorbing materials that absorb blue light, in particular toxic blue light, are envisaged. Useful light-converting materials and light-absorbing materials are described in, for example, the applicant's application on November 14, 2017 and titled "LIGHT EMISSION REDUCING COMPOUNDS FOR ELECTRONIC DEVICES" currently approved jointly owned It is described in US Patent Application Serial No. 15/813,010.

Referring again to FIG. 2 , when light 205 is injected into light guide plate 202 , it may reflect within light guide plate 202 , from reflector 206 , from diffuser 216 and from prismatic brightness enhancing layers 213 and 214 . The light 205 will eventually necessarily pass through the layers of the backlight unit 200 multiple times, and thus be distributed over the entire area of the display located above the top layer of the backlight unit 200 . This can create an opportunity to amplify the effect of selective light converting or light absorbing materials that filter out blue or toxic blue light or any other film or layer that can modify the spectrum. These selective light converting materials or light absorbing materials may be included or coated as separate films on or within any layer making up the disclosed backlight unit.

In some embodiments, light-converting materials (filters) placed at different locations in the backlight unit have been shown to have absorption magnifications as much as 10 to 12 times, which greatly improves the ability to filter out, for example, blue or toxic blue light. The efficiency of selective light converting materials or light absorbing materials.

Figure 3 illustrates the effective transmission of a light converting or absorbing material (blue filter layer) over the visible spectrum as a function of where the light converting or absorbing material is placed within the display backlight. The effective transmission is calculated by dividing the emission from the display with light converting material or light absorbing material by the emission from the display without light converting material or light absorbing material. The different spectra shown in Figure 3 illustrate the effect of the layer of light converting or light absorbing material when placed in different orientations (positions) in the display, ie outside the backlight unit and inside the backlight unit.

FIG. 3 illustrates the transmission spectra of different configurations of the embodiment shown in FIG. 2 , where layers of light converting or light absorbing material (blue filter) are located at different positions as indicated in FIG. 2 . They illustrate the transmission spectra of a typical backlit display configuration (Figure 2) with layers of light-converting or light-absorbing material positioned at three different locations in the backlight filter. In position 1 , the light converting or light absorbing material is between the light guide plate 202 and the diffuser 216 . In position 2, the light converting or light absorbing material is between the first prismatic brightness enhancing film 213 and the second prismatic brightness enhancing film 214 . In position 3, a light converting material or light absorbing layer is placed on top of the polarizer (between the backlight unit 200 and any liquid crystal imaging layers illuminated by the backlight unit 200). Figure 1 is a schematic diagram showing a liquid crystal electro-imaging device on top of a backlight as disclosed above. When the light-converting or light-absorbing material layer is positioned above the polarizer at position 3 (top curve in Figure 3), the transmission spectrum shows very little absorption and re-emission of light from the light-converting material layer. The spectral line at position 3 is relatively flat with little absorption from the photoconverting material layer. The light transmittance in the blue region of the spectrum (400nm to 500nm) ranges from 91% to 100%, with the lowest transmittance peak around 405nm to 415nm at about 91% to 93%.

When the same light converting or light absorbing material layer is placed between the first prismatic brightness enhancing layer and the second prismatic brightness enhancing layer at position 2, the effect of the light converting or light absorbing material layer is shown in the middle curve of FIG. 3 Show. Light transmission in the blue region of the spectrum (400nm to 500nm) can be reduced by as much as 24% and can range from 76% to 95% transmission, with the lowest transmission peak around 425nm to 435nm at approximately 76% to 78% . The layer of light converting or light absorbing material may also have a color balancing (color correcting) component that reduces the transmittance of the red region of the spectrum (640nm to 740nm) and the yellow region of the spectrum (550nm to 620nm). The transmittance in the red region can be reduced by as much as 10% and can range between 90% to 98% transmittance, with the lowest transmittance peaking around 685nm to 695nm around 90% to 92%. The transmittance in the yellow region can be reduced by as much as 12%, and can range between 88% and 98% transmittance, with the lowest transmittance peaking around 580nm to 590nm at about 88% to 90%.

When the same layer of light-converting or light-absorbing material is positioned between the light guide plate and the diffuser layer as shown in position 1 (bottom curve in Figure 3), the absorption of the same film can be enhanced and the blue region of the spectrum (400nm to 500nm) can be reduced by as much as 34% and can range between 66% to 95% transmittance, with the lowest transmittance peaking around 425nm to 435nm around 66% to 68%. As with position 2, when a layer of light-converting or light-absorbing material is positioned at position 1, the layer can also have properties that reduce the transmittance of the red region of the spectrum (640nm to 740nm) and the yellow region of the spectrum (550nm to 620nm) Color balance (color correction) component. The transmittance in the red region can be reduced by as much as 16%, and can range between 84% to 96% transmittance, with the lowest transmittance peaking around 685nm to 695nm at about 84% to 86%. The transmittance in the yellow region can be reduced by as much as 17%, and can range between 83% and 93% transmittance, with the lowest transmittance peaking around 580nm to 590nm at about 83% to 85%.

In a separate experiment, the transmittance of the light-converting or light-absorbing layer was calculated by subtracting the transmittance of the backlit display without the light-converting layer. The results show that about 12 layers of the analog film are required to produce the absorbance shown in position 1 in Figure 3.

Figure 4 illustrates the transmission spectrum for the embodiment of the backlight unit shown in Figure 2, where the light conversion layer is located at various locations in the backlight below the diffuser. In Figure 4, the light conversion layer is coated on a poly(ethylene terephthalate) (PET) film, which is placed over the reflector, light guide and diffuser layers. It turns out that if a light-converting or light-absorbing layer is positioned anywhere below the prismatic brightness-enhancing layer of the backlight, it produces absorption amplification. While not wishing to be bound by theory, it was observed that when a light converting or light absorbing layer is located within the backlight unit (beneath the prismatic brightness enhancing layer and the polarizing layer), absorption is maximized due to multiple internal reflections within the backlight unit .

FIG. 4 illustrates three effective transmission curves for three different configurations of the backlight stack as shown in FIG. 2 . In FIG. 4, one curve is the absorption curve of the backlight unit shown in FIG. 2 with light conversion on the PET layer positioned above the reflector and below the light guide plate. The second absorption curve is a measurement of the spectrum of the same backlight unit with light absorbing material on the PET layer on top of the light guide plate. The third absorption curve is the spectrum of the same backlight unit with light conversion on the PET layer between the light guide plate and the diffuser (shown as position 1 on Figure 2). All three curves substantially overlap each other, indicating that any position of the layer of light-absorbing material below the prismatic brightness enhancing film does not significantly change the absorption, and the absorption of the backlight unit for all three configurations shows substantially about that at the top of the backlight unit. Light absorbing materials have the same amount of absorption amplification.

More specifically, the light transmittance in the blue region of the spectrum (400nm to 500nm) can be reduced by as much as 34%, and can range between 66% and 97% transmittance, with the lowest transmittance peak around 425nm to 435nm around 66 % to 70%. The layer of light converting or light absorbing material may also have a color balancing (color correcting) composition that reduces the transmittance of the red region of the spectrum (640nm to 740nm) and the yellow region of the spectrum (550nm to 610nm). The transmittance in the red region can be reduced by as much as 16%, and can range between 84% and 96% transmittance, with the lowest transmittance peaking around 680nm to 695nm at approximately 84% to 88%. The transmittance in the yellow region can be reduced by as much as 17% and can range from 83% to 94% transmittance, with the lowest transmittance peaking around 580nm to 590nm at about 83% to 85%.

While embodiments of the present invention have been shown and described, it will be apparent that various modifications may be made without departing from the spirit and scope of the invention. It is also contemplated that various combinations and subgroups of specific features and aspects of the disclosed embodiments may be combined or substituted for each other to form different modes of the invention. Accordingly, it is not intended that the invention be limited, except as defined by the scope of the appended claims. Any reference cited herein is hereby incorporated by reference in its entirety.

100: display system 101: Lighting components 102: Reflective base 104: Controller 108: backlight 112: light source 120: diffuser 140: light management film 142: reflective polarizer 144: Polarization control layer 146a: the first brightening layer 146b: the second brightening layer 150:LC panel 152:LC layer 154: panel sheet 156: Upper absorbing polarizer 157: optional layer 158: Lower absorbing polarizer 200: backlight unit 202: light guide plate 204: Light emitting diode array 205: light 206: reflector 212: layer 213: The first brightening layer 214: the second brightening layer 216: diffuser 502: anti-adhesion layer 504: basal layer 506: Diffuse layer

The drawings are schematic and are not intended to limit the scope of the invention in any way. The drawings are not necessarily drawn to scale.

FIG. 1 is a schematic cross-sectional view of an exemplary display system according to the present disclosure.

Figure 2 is a schematic cross-sectional view of an embodiment of a backlight unit according to the present application, indicating where a light converting or light absorbing (blue filter) layer may be inserted.

FIG. 3 illustrates transmission spectra for different configurations of the embodiment shown in FIG. 2 , where the blue filter layer is in different positions as indicated in FIG. 2 .

Figure 4 illustrates the transmission spectrum of the embodiment of the backlight unit shown in Figure 2 with the blue filter layer at various locations below the diffuser.

Fig. 5 is a schematic cross-sectional view of a diffuser.

In this case:

The term "adjacent" means layers that are directly adjacent to each other or separated by at most one additional layer;

The term "blue light" or "toxic blue light" refers to light having a wavelength range of about 400 nm to about 500 nm or about 415 nm to about 455 nm, respectively;

The term "disposed on" refers to a layer that is in direct contact with or adjacent to another layer;

The term "light-emitting diode array" means one or more light-emitting diodes in a usually two-dimensional matrix; and

The term "optical stack" refers to a layer in a backlight unit that emits light, is optically transparent to that light, or modifies the properties of that light. These layers may be adjacent to each other.

Domestic deposit information (please note in order of depositor, date, and number) none Overseas storage information (please note in order of storage country, institution, date, and number) none

100: display system

101: Lighting components

102: Reflective base

104: Controller

108: backlight

112: light source

120: diffuser

140: light management film

142: reflective polarizer

144: Polarization control layer

146a: the first brightening layer

146b: the second brightening layer

150:LC panel

152:LC layer

154: panel sheet

156: Upper absorbing polarizer

157: optional layer

158: Lower absorbing polarizer

Claims (33)

A display system for use with an electronic display device comprising: an electronic display device; and A backlight unit, wherein the backlight unit includes: a light emitting array; a reflector adjacent to the light emitting array; a diffuser opposite the reflector; a first brightness enhancing layer adjacent to the diffuser; and at least one light converting material or at least one light absorbing material, Wherein the at least one light converting material or the at least one light absorbing material is constructed and arranged to reduce the transmission of blue light in a wavelength range between about 400 nm and about 500 nm. The display system according to claim 1, wherein the electronic display device is selected from an LCD monitor, an LCD-TV monitor, a handheld device, a tablet computer and a laptop display. The display system of claim 1, wherein the display system includes a liquid crystal panel and an illumination assembly positioned to provide illumination light to the liquid crystal panel. The display system according to claim 3, further comprising panel sheets, wherein the liquid crystal panel is arranged between the panel sheets. The display system according to claim 4, wherein the panel sheet includes an electrode structure and an alignment layer constructed and arranged to control the alignment of liquid crystals in the liquid crystal layer. The display system according to claim 5, further comprising a color filter constructed and arranged to impart color to an image displayed by the liquid crystal panel. The display system according to claim 1, wherein the light converting material or light absorbing material is soluble or insoluble dispersed throughout an optical film in the backlight unit. The display system according to claim 1, wherein the light converting material or light absorbing material comprises nanoparticles. The display system according to claim 8, wherein the nanoparticles include quantum dots or luminescent nanoparticles. The display system according to claim 1, wherein an optical film in the backlight unit includes a light-converting material or a light-absorbing material with matching refractive index. The display system of claim 1, wherein an optical film in the backlight unit includes a light conversion material or a light absorption material having a different refractive index from the optical film and used for a diffuser or a reflector. The display system according to claim 1, comprising inorganic nanoparticles, the inorganic nanoparticles are index-matched with the light conversion material or the light absorption material and coupled to an organic binder, and the organic binder is applied to the backlight unit an optical film. The display system of claim 1, comprising inorganic nanoparticles index matched to an optical film in the backlight unit and coupled to an organic binder applied to the optical film. The display system of claim 1, wherein the light converting material or light absorbing material can be included on the diffuser. The display system according to claim 1, wherein the light converting material or light absorbing material is soluble or insoluble dispersed throughout the diffuser. The display system according to claim 15, wherein the light converting material or light absorbing material is index matched. The display system according to claim 15, wherein the light conversion material or light absorption material has a refractive index difference. The display system according to claim 15, wherein the diffuser at least includes an anti-adhesion layer, a base layer and a diffusion layer. The display system according to claim 18, wherein the light conversion material or the light absorption material is in the anti-adhesion layer or the diffusion layer. The display system according to claim 19, wherein at least one of the anti-adhesion layer or the diffusion layer is coated on the base layer. The display system according to claim 18, wherein the light converting material or light absorbing material is in the base layer. The display system according to claim 21, wherein the light converting material or light absorbing material is blended with a polymer resin and extruded into a film. The display system of claim 15, wherein the at least one light converting material or at least one light absorbing material is structured and configured as reducing the transmission of blue light by as much as 34% in the wavelength range between about 400nm and about 500nm, with a transmission peak of about 66% to 68% near 425nm to 435nm; having a color balancing composition that reduces transmission by as much as 17% in the wavelength range between about 550nm and about 620nm, with a transmission peak around 580nm to 590nm of about 83% to 85%; and Having a color balancing component that reduces transmission by as much as 16% in a wavelength range between about 640nm and about 740nm, with a transmission peak around 685nm to 695nm of about 84% to 86%. A method of enhancing blue light absorption (400nm to 500nm) in a backlight unit, comprising the steps of: A display system is provided for use with an electronic display device, the display system comprising an electronic display device; and A backlight unit, wherein the backlight unit includes: a light emitting array; a reflector adjacent to the light emitting array; a diffuser opposite the reflector; a first brightness enhancing layer adjacent to the diffuser; and at least one light converting material or at least one light absorbing material, Wherein the at least one light converting material or the at least one light absorbing material is constructed and arranged to reduce the transmission of blue light in a wavelength range between about 400 nm and about 500 nm. The method of claim 24, wherein the backlight unit further comprises: a light guide plate, the light guide plate has an edge, a bottom surface and a top surface, Wherein the light emitting array is constructed and configured to inject light into the light guide plate. The method of claim 24, wherein the backlight unit further comprises: a second brightness enhancing layer adjacent to the first brightness enhancing layer; and a polarizing filter adjacent to the second brightness enhancing layer, Wherein the reflector is adjacent to the bottom surface of a light guide plate and opposite to the diffuser. The method of claim 26, further comprising the step of: inserting the at least one light converting material or at least one light absorbing material between the first brightness enhancing layer and the second brightness enhancing layer. The method according to claim 26, further comprising the step of inserting the at least one light converting material or at least one light absorbing material between the reflector and a bottom surface of the light guide plate. The method of claim 26, further comprising the step of: inserting the at least one light converting material or at least one light absorbing material between a top surface of the light guide plate and the diffuser. The method of claim 26, further comprising the step of inserting the at least one light converting material or at least one light absorbing material in at least one of the first brightness enhancing layer and the second brightness enhancing layer. The method of claim 26, further comprising the step of inserting the at least one light converting material or at least one light absorbing material in at least one of the reflector and a bottom surface of the light guide plate. The method of claim 24, wherein the at least one light converting material or at least one light absorbing material is dispersed on or within at least one of the reflector, diffuser or brightness enhancing layer. The method of claim 32, wherein the at least one light converting material or at least one light absorbing material is constructed and arranged as reducing the transmission of blue light by as much as 34% in the wavelength range between about 400nm and about 500nm, with a transmission peak of about 66% to 68% near 425nm to 435nm; having a color balancing composition that reduces transmission by up to 17% in the wavelength range between about 550nm and about 620nm, with a transmission peak around 580nm to 590nm of about 83% to 85%; and Having a color balancing component that reduces transmission by as much as 16% in a wavelength range between about 640nm and about 740nm, with a transmission peak around 685nm to 695nm of about 84% to 86%.

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