Display system using multilayer optical film

Abstract

A display system including a plurality of layers is provided. The layers include a 5 display layer, an emissive layer, a multilayer optical film, and a detection layer. The emission layer includes: a plurality of visible light emitters configured to emit visible light, the visible light having a wavelength of 425 nm to 680 nm; and a plurality of infrared light emitters, the plurality of infrared light emitters being configured to emit infrared light, the infrared light having a wavelength of 800 nm to 1500 nm. The display layer transmits both the visible light and the infrared light at substantially all angles of incidence. The multi-layer optical film transmits the visible light at substantially all angles of incidence, but transmits the infrared light only along angles of incidence exceeding a first threshold angle, the first threshold angle being from 20 degrees to 40 degrees. The detection layer includes a plurality of detectors sensitive to the infrared light.

Description

Technical Field

[0001] An electronic display system is provided, and in particular an electronic display system with touch function is provided. Background Art

[0002] In order to provide touch functionality in large area displays, different touch technologies have been utilized in the art. One of the technologies uses an array of infrared light sources (e.g., light emitting diodes or LEDs) and infrared light detectors or sensors that are mounted around the edge of a touch screen placed above a display panel so that light is injected into it using total internal reflection. In some cases, an array of detectors may be placed on opposite sides of the touch screen to receive signals from the infrared light sources. When an object (e.g., a finger or stylus) touches the screen, the intensity of the infrared light at the detectors decreases, and the position of the object can be determined using a triangulation algorithm based on the relative distribution of infrared intensities at the various photodiodes.

[0003] While this principle works extremely well for relatively small screens, the cost can grow exponentially when applied to larger display panels due to the high costs associated with obtaining the high quality required to propagate a signal across a large area using total internal reflection (e.g., display uniformity, optical quality, flatness, etc.) Furthermore, additional challenges are presented in efficiently coupling infrared light into and out of the touch panel while maintaining a thin profile, eliminating interference from ambient light, and preventing surface contamination. Summary of the invention

[0004] There remains a technical need for display systems that provide reliable and high-resolution touch detection while being cost-effective and scalable to large-size display systems. The provided display system exploits the angular dependence of light transmission through a multilayer optical film to achieve a novel touch screen device architecture. Touch sensing under an LCD is contemplated by using a film that transmits a specific sensing wavelength within a specified angular range. Optionally, these display systems can use a resonant cavity with a narrow passband, whereby the film is transparent to a specific sensing wavelength within a narrow angular cone and reflective to other wavelengths, and outside the angular cone, the film is reflective. Multiple near-infrared (NIR) sensors can be provided under the display to obtain a display system with multi-touch capabilities.

[0005] In a first aspect, a display system is provided. The display system includes the following layers in the order provided: a display layer; an emission layer, the emission layer including a plurality of visible light emitters, the plurality of visible light emitters being configured to emit visible light, the visible light having a wavelength of 425 nm to 680 nm; and a plurality of infrared light emitters, the plurality of infrared light emitters being configured to emit infrared light, the infrared light having a wavelength of 800 nm to 1500 nm, wherein the display layer transmits both the visible light and the infrared light at substantially all incident angles; a multilayer optical film, the multilayer optical film transmitting the visible light at substantially all incident angles, but transmitting the infrared light only along incident angles exceeding a first threshold angle, the first threshold angle being 20 degrees to 40 degrees; and a detection layer, the detection layer including a plurality of detectors sensitive to the infrared light.

[0006] In a second aspect, a method for locating a position of an object when the object is placed near a display system is provided, the method comprising: providing the display system; emitting the infrared light from the plurality of infrared light emitters; reflecting the infrared light from the object at a position where the display system is touched; detecting the presence of reflected infrared light transmitted through the multilayer optical film using the plurality of detectors; and performing edge detection on the transmitted infrared light to determine an area of ​​the display system along which the display system is touched. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is an exploded side cross-sectional view of a display system according to an exemplary embodiment.

[0008] Figure 2 is combined with Figure 1 Transmission spectra of multilayer optical films in display systems.

[0009] Figure 3 is the characterization of transmission through Figure 1 and Figure 2 Intensity distribution of infrared light of the multilayer optical film shown.

[0010] Figure 4 is an exploded side cross-sectional view of a display system according to another exemplary embodiment.

[0011] Figure 5 is combined with Figure 4 Transmission spectra of multilayer optical films in display systems.

[0012] Figure 6 is the characterization of transmission through Figure 4 and Figure 5 Intensity distribution of infrared light of the multilayer optical film shown.

[0013] Figure 7is a side cross-sectional view illustrating multiple layers in an exemplary multilayer optical film that can be used in the provided display systems.

[0014] Figure 8 and Fig. 9 It is available for Figure 1 and Figure 4 Transmission spectra of exemplary multilayer optical film assemblies in display systems.

[0015] Reference symbols used repeatedly in the specification and drawings are intended to represent the same or similar features or elements of the present disclosure. It should be understood that those skilled in the art can design many other modifications and embodiments that fall within the scope and essence of the principles of the present disclosure. The drawings may not be drawn to scale.

[0016] definition

[0017] As used in this article:

[0018] When referring to a range, "between" means having values ​​falling between but not including the two end values.

[0019] "Substantially" means at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or 100%.

[0020] "Substantially all" means at least 90%, at least 95%, at least 97%, at least 98%, at least 99%, or 100%. DETAILED DESCRIPTION

[0021] As used herein, the terms "preferred" and "preferably" refer to embodiments described herein that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. In addition, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the invention.

[0022] As used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a", "an" or "the" component may include one or more components known to those skilled in the art or their equivalents. Additionally, the term "and / or" means one or all of the listed elements or a combination of any two or more of the listed elements.

[0023] It is worth noting that the term "including" and its variations do not have a restrictive meaning when appearing in the attached specification. In addition, "one", "a", "the / said", "at least one" and "one or more" are used interchangeably herein. Relative terms such as left, right, forward, backward, top, bottom, side, upper, lower, horizontal, vertical, etc. may be used herein, and if so, they are from the perspective observed in the specific drawings. However, these terms are only used to simplify the description and are not intended to limit the scope of the present invention in any way.

[0024] References throughout this specification to "one embodiment," "certain embodiments," "one or more embodiments," or "an embodiment" mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, phrases such as "in one or more embodiments," "in certain embodiments," "in an embodiment," or "in an embodiment" appearing in various places throughout this specification are not necessarily referring to the same embodiment of the present invention.

[0025] According to some aspects of the present disclosure, a display system is provided that allows infrared light (e.g., near infrared light) to be transmitted throughout the entire LCD, enabling the use of infrared LEDs and sensors directly behind and below the display panel. In other aspects, the display system utilizes optical film technology that is reflective to visible light at all incident angles and transparent to NIR only at certain incident angles. Therefore, the system provides the opportunity to use both visible and infrared light sources behind the display to implement touch detection functionality.

[0026] As mentioned herein, the constituent layers of the provided display systems may have opposing major surfaces that are generally parallel to each other. In some cases, the layers are continuous layers and are coextensive along their respective major surfaces.

[0027] A display system according to an exemplary embodiment Figure 1 1 and hereinafter referred to by the numeral 100. As depicted, display system 100 has a multi-layer construction that generally includes the following layers, in the order provided: display layer 102, emissive layer 104, multilayer optical film 106, detection layer 108, and optional printed circuit board 110.

[0028] Display layer 102 is aligned with top major surface 111 of display system 100. Top major surface 111 is an exposed touch-sensitive surface and is capable of detecting physical contact with a finger, stylus, or other pointing device. Display layer 102 need not be particularly limited and may include a liquid crystal panel 112, which optionally extends across an underlying reflective polarizer 114, which is disposed between the liquid crystal panel and the emissive layer. In order for a liquid crystal display (LCD) to be easily readable, light must be present, and ambient light (e.g., office light or sunlight) that passes through the glass front may be reflected from reflective polarizer 114 to provide further illumination for display system 100 (particularly for a reflective LCD device).

[0029] In a broader sense, the reflective polarizer 114 can transmit the polarization of light parallel to the transmission axis of the absorptive polarizer in the LCD, and reflect the orthogonal polarization that is scrambled after reflection from the layers below it. Therefore, most of the light that impinges on the bottom absorptive polarizer of the LCD has a polarization state parallel to the transmission axis of the absorptive polarizer. In the absence of the reflective polarizer, 50% of the light would be absorbed by the absorptive polarizer.

[0030] In some embodiments, the reflective polarizer 114 can be configured such that for substantially vertically incident light, the reflective polarizer 114 has an average optical reflectivity greater than about 50%, or 55%, or 60%, or 70%, or 75%, or 80%, or 85%, or 90% for visible light polarized along a first direction in the plane (e.g., polarized along the x-axis of the reflective polarizer), and has an average optical transmittance greater than about 50%, or 55%, or 60%, or 65%, or 70%, or 75% when the incident light is polarized along an orthogonal second direction in the plane (e.g., the y-axis of the reflective polarizer). In some embodiments, the reflective polarizer 114 can also be configured such that for light with substantially normal incidence, the reflective polarizer 114 has an optical transmittance of greater than about 30%, or 35%, or 40%, or 45%, or 50%, or 55%, or 60%, or 65%, or 70%, or 75%, or 80% for infrared light in at least one of the above-mentioned first polarization state or second polarization state.

[0031] As an additional optional layer, the display layer 102 can include an optical diffuser layer. The optical diffuser layer can be disposed between the reflective polarizer 114 and the emissive layer 106 and can evenly distribute the light from the visible LEDs while also disrupting the polarization state of the light reflected by the reflective polarizer.

[0032] In the absence of ambient light, backlighting from a light source is necessary because, by its very nature, the LCD panel does not generate light itself. Color filters are typically used to provide colored light based on an additive combination of the primary colors red, green, and blue. The LCD panel includes numerous pixels, each of which is subdivided into sub-pixels aligned with the primary colors, where each sub-pixel transmits only light of their respective primary color and absorbs all other colors. The coordinated presentation of the pixels can therefore generate the desired image.

[0033] Display layer 102 transmits both the visible light and the infrared light at substantially all angles of incidence. Transmission of LCD backlight illumination, typically provided by emissive layer 104, enables a viewer to see an image generated by display system 100, preferably with minimal or no brightness degradation. In addition, transmission of infrared light (such as provided by emitter 118) is typically required for display system 100 to detect touch based on reflection of infrared light at major surface 111.

[0034] The presence of an object (typically a finger or stylus) pressed against the top major surface 111 of the display system 100 can be detected by reflecting infrared light from the object. Figure 1 As shown, a finger 120 approaching or touching the top major surface 111 may interact with the propagating light at the touch point. In this interaction, part of the light may be scattered by the finger, part of the light may be absorbed by the finger, and part of the light may continue to propagate in its original direction. The signal from the reflection of the sensed infrared illumination can be used for edge detection, where the boundaries of the area in contact with the object can be delineated based on the electronic signal provided by the display system 100 to the computer.

[0035] The emission layer 104 extends below the display layer 102. The emission layer 104 provides two functions, first, it provides a visible light source (i.e., backlighting) for the generated image, and second, it provides an infrared light source for touch detection. In order to provide this dual function, the emission layer includes a plurality of visible light emitters 116 configured to emit visible light and a plurality of infrared light emitters 118 configured to emit infrared light. The visible light typically has a wavelength in the range of 425nm to 680nm, for example, a wavelength less than, equal to, or greater than 425nm, 430nm, 435nm, 440nm, 445nm, 450nm, 460nm, 470nm, 480nm, 490nm, 500nm, 510nm, 520nm, 530nm, 540nm, 550nm, 560nm, 570nm, 580nm, 590nm, 600nm, 610nm, 620nm, 630nm, 640nm, 650nm, 655nm, 660nm, 665nm, 670nm, 675nm or 680nm.

[0036] The infrared light typically has a wavelength in the range of 850nm to 1500nm, such as less than, equal to, or greater than 850nm, 855nm, 860nm, 865nm, 870nm, 875nm, 880nm, 885nm, 890nm, 895nm, 900nm, 910nm, 920nm, 930nm, 940nm, 950nm, 960nm, 970nm, 980nm, 990nm, 1000nm, 1050nm, 1100nm, 1150nm, 1200nm, 1250nm, 1300nm, 1350nm, 1400nm, 1450nm, or 1500nm. Useful infrared light emitters 118 can be based on light emitting diodes, lasers, vertical cavity surface emitting lasers, or combinations thereof. Optionally, the infrared light emitters can emit half-Lambertian radiation. Emitting half-Lambertian radiation may illuminate an object such that light reflected from the object is also half-Lambertian and is directed toward a plurality of detectors for identifying its position.

[0037] Visible light emitters 116 and infrared light emitters 118 are typically arranged in respective two-dimensional arrays, wherein emitters 116, 118 are evenly distributed across the major surface of display system 100. The two-dimensional array may be based on, for example, a rectangular grid pattern that is repeated across the major surface of emissive layer 104. To minimize the thickness of emissive layer 104, visible light emitters 116 and infrared light emitters 118 may be coplanar with each other. If desired, visible light emitters 116 and infrared light emitters 118 may also be arranged in two or more discrete layers so that they are not coplanar.

[0038] Refer again Figure 1 , emitters 116, 118 are disposed on the multilayer optical film 106. In the depicted embodiment, the emitters 116, 118 are mounted directly to the multilayer optical film 106. Alternatively, the emitters 116, 118 may be disposed on a common support layer located between the emissive layer 104 and the multilayer optical film 106. The support layer is preferably transparent to both visible light and infrared light from the emitters 116, 118, respectively. Useful support layers may be made of glass, polyethylene terephthalate, or a combination thereof. The emitters 116, 118 may be in direct contact with the support layer or have at least one intervening layer, such as an adhesive, a socket, or a connector. The support layer may have a transmittance greater than 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% of visible light and / or infrared light.

[0039] Alternatively, visible light emitter 116 and infrared light emitter 118 may be separated from each other by a gap, wherein the gap is at least partially filled with an infrared absorbing material. Useful infrared absorbing materials may include NIR absorbing dyes and pigments (e.g., those sold under the trade name OPTLION from Toyo Visual Solutions Co., Ltd. (Tokyo, Japan) or under the trade name LUNIR5 from Luminochem Kft. (Budapest, Hungary). Advantageously, such a configuration may help minimize undesirable reflections and improve the resolution of touch detection at major surface 111.

[0040] The multilayer optical film 106 may be made of any suitable multilayer optical film known in the art. Suitable multilayer optical films provide desired transmission and / or reflection properties by an arrangement of constituent layers having different refractive indices. As is well known, such multilayer optical films are made by depositing a series of inorganic materials in the form of optically thin layers (or "microlayers") on a substrate in a vacuum chamber. Inorganic multilayer optical films are described in textbooks such as H.A. Macleod, Thin-Film Optical Filters, 2nd Ed., Macmillan Publishing Co. (1986) and A. Thelan, Design of Optical Interference Filters, McGraw-Hill, Inc. (1989).

[0041] Multilayer optical films have also been demonstrated by coextrusion of alternating polymer layers including a first polymer and a second polymer having different refractive indices, see, e.g., U.S. Pat. No. 3,610,729 (Rogers), U.S. Pat. No. 4,446,305 (Rogers et al.), U.S. Pat. No. 4,540,623 (Im et al.), U.S. Pat. No. 5,448,404 (Schrenk et al.), and U.S. Pat. No. 5,882,774 (Jonza et al.). In these polymeric multilayer optical films, the polymer material is used primarily or exclusively in the preparation of the individual layers. These polymeric multilayer optical films may be referred to as thermoplastic multilayer optical films. Such films are amenable to high-volume manufacturing processes and can be made into large sheets and rolls.

[0042] Similar to display layer 102, multilayer optical film 106 reflects visible light at substantially all incident angles. Unlike display layer 102, multilayer optical film 106 reflects visible light only at and above a certain threshold angle θ. c The incident angle θ c It can be 20 to 40 degrees, 20 to 30 degrees, 25 to 30 degrees, or in some embodiments, less than, equal to, or greater than 20 degrees, 25 degrees, 30 degrees, 35 degrees, or 40 degrees. However, it is worth noting that the threshold angle θ c May depend on the wavelength of the infrared light.

[0043] Figure 1 The properties of selective light transmission described above for infrared light of a given wavelength are also illustrated. At the point of contact where finger 120 contacts major surface 111, infrared light emitted from emitter 118 is reflected from finger 120 and redirected back into display system 100 over a wide range of angles as shown. Reflected light rays 122 (represented by solid lines) have a wavelength at and above a threshold angle θ. c θ and passes through the multilayer optical film 106 unimpeded. In contrast, reflected light 124 (represented by the dashed line) has an incident angle less than the threshold angle θ. c The incident angle is small and therefore reflects from the multilayer optical film 106 rather than passing through the multilayer optical film.

[0044] Light passing through the multilayer optical film 106 can be detected by a plurality of detectors 126, which include the detector layer 108. To facilitate electronic communication with a computer, the detectors 126 can be disposed on the printed circuit board 110, as shown. Similar to the emitters 116, 118, the detectors 126 are a plurality of tiny devices dispersed on the major surface of the display system 100. These detectors 126 are independently sensitive to infrared light and can communicate with the computer to report any local exposure of the detector layer 108 to infrared light. Useful detectors may include, for example, solid-state photon detectors including inorganic silicon photodiodes, thin film transistors, organic photodiodes, or combinations thereof.

[0045] Figure 2 1 is a schematic diagram showing the transmittance of the multilayer optical film 106, this time as a function of wavelength. The figure shows a number of response curves corresponding to different incident angles θ. For light in the visible wavelength spectrum, which generally corresponds to the range of 425nm to 680nm, approximately 100% of the light is reflected regardless of the incident angle θ. For light at significantly higher wavelengths, as shown, the ability of the light to be transmitted through the multilayer optical film 106 depends on the incident angle θ. For light at Figure 2 When the incident angle θ is less than the threshold value θ, the monochromatic light at the sensing wavelength defined in cWhen the incident angle θ is higher than the threshold θ, the transmittance becomes zero. c The transmittance is about 100% when θ is a fixed angle. The sensing wavelength may be, for example, the wavelength of light emitted by the emitter 118 and detected by the detector 126. In the case where the incident angle θ is a fixed angle, there is usually a threshold wavelength λ c , below this threshold wavelength, the transmittance is approximately zero, and above this threshold wavelength, the transmittance is approximately 100%.

[0046] In a preferred embodiment, the multilayer optical film 106 substantially reflects the infrared light at all incident angles, and the multilayer optical film does not transmit the infrared light at all incident angles. That is, for a given sensing wavelength, there may be minimal or zero light absorption. In such cases, light incident on the multilayer optical film 106 is reflected or transmitted. Such scenarios are generally beneficial to avoid generating excessive heat within the layers of the display system 100 (excessive heat is generally undesirable). In alternative applications without such problems, the multilayer optical film 106 may substantially absorb infrared light at all incident angles, and the multilayer optical film does not transmit the infrared light at all incident angles.

[0047] Figure 3 1 shows a two-dimensional intensity graph of infrared light detected corresponding to the display system 100 being touched at two locations simultaneously. Dark areas 130, 132 are concentric with the locations of the touches and can be attributed to the infrared light being detected below θ. c The incident angle θ is the total reflection from the multilayer optical film. The bright regions 134 and 136 surround the dark regions 130 and 132 and are relatively much brighter, which indicates that when the incident angle θ exceeds the threshold c If a film is used that transmits light only over a small range of angles, interference can be significantly reduced because most of the ambient light will be blocked before reaching the detector.

[0048] Figure 4 A display system 200 is shown, which is relative to Figure 1 The display system provided in has further enhancements. The display system 200 has various features generally similar to those in the previous embodiments, including a display layer 202, an emissive layer 204, a multilayer optical film 206, a detection layer 208, and an optional printed circuit board 210. The functional aspects of the display layer 202, the emissive layer 204, the detection layer 208, and the printed circuit board 210 are similar to those functional aspects already described and are not repeated here.

[0049] However, if Figure 4 and Figure 5As shown, the multilayer optical film 206 has both similarities and differences in its spectral response to infrared light at a certain sensing wavelength. Infrared light reflected from the touch surface and impinging on the multilayer optical film 206 at a relatively sharp angle (close to 0 degrees) is totally reflected as previously described. Such behavior is maintained for incident angles up to but not including the first threshold angle θ1. Then, at incident angles within the range of the first threshold angle θ1 to the second threshold angle θ2, the infrared light is completely transmitted through the multilayer optical film 206. Finally, in the case of exceeding the second threshold angle θ2, the infrared light is again totally reflected from the multilayer optical film 206.

[0050] This is due to Figure 4 , where infrared light transmission occurs only over a narrow annular band around the touch location. As shown here, infrared light is reflected at other angles. Light that can transmit through oil or water needs to meet some conditions to transmit through the display. By manipulating the angles θ1, θ2, we can design the system so that when oil and water are present on the display, it does not reflect light back to the detector.

[0051] Both the first threshold angle θ1 and the second threshold angle θ2 can be designed independently based on the architecture of the multilayer optical film 206. For example, the first threshold angle θ1 can be 20 to 40 degrees, 20 to 30 degrees, 25 to 30 degrees, or in some embodiments, less than, equal to, or greater than 20, 25, 30, 35, or 40 degrees. The second threshold angle θ2 can be 25 to 35 degrees, 28 to 35 degrees, 30 to 35 degrees, or in some embodiments, less than, equal to, or greater than 25, 28, 30, 32, or 35 degrees.

[0052] The first threshold angle and the second threshold angle θ1 and θ2 may have an angle difference of 5 to 15 degrees, 5 to 10 degrees, 5 to 8 degrees, or in some embodiments, less than, equal to, or greater than 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 degrees. Figure 5 As illustrated, when light transmission is measured relative to its wavelength, the multilayer optical film 206 exhibits a very narrow passband that shifts with the angle of incidence. Touch is detected by sensing infrared light transmitted through the multilayer optical film 206 along a narrow envelope between concentric cones, thereby significantly reducing interference from ambient light and obtaining a higher quality signal.

[0053] Since ambient NIR light can impinge on the display surface at all incident angles, the benefit of a narrow passband is realized. c , the multilayer optical film has an angle greater than the threshold angle θ cAll ambient light with an incident angle greater than this angle will be transmitted, interfering with the signal that will be detected by the detector. If we have a film that transmits light only within a small range of angles, the interference can be significantly reduced since most of the ambient light will be blocked by the optical film before reaching the detector.

[0054] The above threshold angles θ1 and θ2 can be adjusted to help reduce or eliminate sensitivity to water and oil that may be present on the touch surface. Light that can be transmitted through oil or water needs to meet certain conditions to be transmitted through the display. By adjusting the angles θ1 and θ2, a system can be provided in which oil and water present on the display does not reflect light back to the detector.

[0055] This behavior of the multilayer optical film 206 can be achieved using a multilayer optical film having a resonant cavity whose spectral properties are Fig. 9 When light having different wavelengths enters between two partially reflective interfaces (such as provided by a multilayer optical film), only light having wavelengths within a narrow range is transmitted. The wavelengths transmitted may depend, for example, on the spacing between those opposing interfaces. When the spacing satisfies the resonance condition for the sensed light, the light may be transmitted through the multilayer optical film. In International Publication No. WO 2022 / 137060 (Wheatley et al.) (e.g., in Figure 6 C and the related paragraph on page 13, lines 21 to 33) show and describe certain aspects associated with an optical film having a resonant cavity.

[0056] Figure 6 The display system 200 is shown in FIG. Figure 3 FIG. 2 is a two-dimensional intensity map of infrared light detected by a touch at the same location as shown in the display system 100 in FIG. As previously described, there are dark regions 234, 236 centered at the touch location, with annular bright regions 230, 232 surrounding the dark regions 234, 236. Advantageously, in this case, due to the narrow passband, the bright regions 230, 232 do not overlap, thereby avoiding convolution of discrete touch sensing signals and enabling improved resolution of touch detection. Higher resolution, in turn, enables the display system 200 to distinguish between touch objects that are closer to each other than was previously possible.

[0057] Figure 7 Provided are multilayer optical films (including Figure 1 The reflective polarizer 114 and Figure 1 and Figure 4206, as previously discussed). In some embodiments, any of these films can be a multilayer optical film having a plurality of alternating polymer layers 252 and 254, the total number of which is at least 10, or at least 50, or at least 100, or at least 150, or at least 200, or at least 250, or at least 300. In some embodiments, each of the polymer layers 252 and 254 can have an average thickness of less than 500 nm, or less than 450 nm, or less than 400 nm, or less than 350 nm, or less than 300 nm, or less than 250 nm, or less than 200 nm. In some embodiments, the multilayer optical film can also include one or more outer layers 256. By configuring the refractive indices of the alternating layers 252 and 254, the multilayer film can be configured to match any of the light transmission curves provided herein, such as those described herein. Figure 8 and Fig. 9 . The polymer layers 252, 254 may include one or more of the following: polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), CoPMMA with PET, glycol-modified polyethylene terephthalate (PETG), polyethylene naphthalate (PEN), PC:PETG alloy, and PEN / PET copolymer. Additional aspects are described in U.S. Patent Application No. WO 2020 / 053832 (Fabick et al.).

[0058] The transmission spectra of the optical films described herein were calculated using a 4×4 transfer matrix multilayer optical response calculation engine. All calculations were performed using MATLAB software from Mathworks Inc., Natick, Mass. The accuracy of the model was tested against measured data.

[0059] Figure 8 The transmission spectrum of a near infrared specular reflector (NSR) based on an exemplary multilayer optical film is shown. For this reflector, a sensing wavelength of 800 nm was selected so that the NSR reflects substantially all wavelengths of light at angles of incidence up to about 40 degrees and reflects visible light at all angles of incidence.

[0060] Fig. 9The transmission spectra of the improved multilayer optical film with resonant cavity are shown. In this case, the sensing wavelength of 850nm is selected so that light is transmitted only over a very narrow angular range centered around about 34 degrees and is reflected at all other wavelengths (including all visible light wavelengths). In both cases, improved resolution and accuracy are obtained using multilayer optical films with sharp right band edges, resulting in sharp cutoff angles.

[0061] In various embodiments, a display system is provided that can provide a method for locating the position of an object when the object is placed near the display system. Such a method can include emitting the infrared light from the plurality of infrared light emitters and then reflecting the infrared light from the inner surface of the display layer, wherein the reflection occurs at the location where the display system is touched. The plurality of detectors can be used to detect the infrared light reflected from the touch surface and then transmitted through the multilayer optical film. A computer in communication with the detectors can then perform edge detection on the transmitted infrared light to determine the following area of ​​the display system: along which the display system is touched.

[0062] All references, patents and patent applications cited in the above patent applications are incorporated herein by reference in their entirety in a consistent manner. In the event of inconsistency or conflict between the incorporated references and the present application, the information in the foregoing description shall prevail. The foregoing description, which is given to enable a person of ordinary skill in the art to practice the present disclosure protected by the claims, should not be construed as limiting the scope of the present disclosure, which is defined by the claims and all equivalents thereof.

Claims

1. A display system, comprising the following layers in the order provided: Display layer; The transmitting layer comprises: a plurality of visible light emitters configured to emit visible light having a wavelength of 425 nm to 680 nm; and a plurality of infrared light emitters, the plurality of infrared light emitters being configured to emit infrared light, the infrared light having a wavelength of 800 nm to 1500 nm, wherein the display layer transmits both the visible light and the infrared light at substantially all angles of incidence; a multilayer optical film that transmits the visible light at substantially all incident angles, but transmits the infrared light only at incident angles exceeding a first threshold angle, the first threshold angle being between 20 degrees and 40 degrees; and A detection layer includes a plurality of detectors sensitive to the infrared light.

2. The display system of claim 1, wherein the multilayer optical film comprises at least 10 alternating polymer layers of a first polymer and a second polymer, the first polymer and the second polymer having different refractive indices.

3. The display system of claim 1 or 2, wherein the multilayer optical film comprises a resonant cavity disposed between opposing mirror layers.

4. The display system of any one of claims 1 to 3, wherein the multilayer optical film transmits the infrared light only along incident angles within a range from the first threshold angle to a second threshold angle, the second threshold angle being 25 degrees to 35 degrees. 5 . The display system according to claim 1 , wherein the first threshold angle and the second threshold angle have an angle difference of 5 to 15 degrees.

6. The display system of any one of claims 1 to 5, wherein the multilayer optical film reflects the infrared light at substantially all incident angles, the multilayer optical film not transmitting the infrared light at the all incident angles.

7. The display system of any one of claims 1 to 6, wherein the multilayer optical film substantially absorbs the infrared light at all incident angles, the multilayer optical film not transmitting the infrared light at all incident angles.

8. The display system of any one of claims 1 to 7, further comprising a support layer between the emissive layer and the multilayer optical film, the support layer being transparent to both the visible light and the infrared light. 9 . The display system according to claim 8 , wherein the visible light emitter and the infrared light emitter of the emission layer are disposed on the support layer and directly contact the support layer.

10. The display system according to any one of claims 1 to 9, wherein the visible light emitter and the infrared light emitter are separated from each other by a gap, and further wherein the gap is at least partially filled with an infrared absorbing material. 11 . The display system according to claim 1 , further comprising a printed circuit board, wherein the detection layer is disposed on the printed circuit board.

12. The display system according to claim 11, wherein the display layer comprises: LCD panel, and A reflective polarizer transmits the infrared light, and is disposed between the liquid crystal panel and the emission layer.

13. A display system according to any one of claims 1 to 12, wherein the visible light emitters, the infrared light emitters and the detectors extend across the display layer in respective repeating two-dimensional arrays.

14. The display system of any one of claims 1 to 13, wherein the infrared light emitter emits half-Lambertian radiation.

15. A method for locating a position of an object when the object is placed near a display system, the method comprising: Providing a display system according to any one of claims 1 to 14; emitting the infrared light from the plurality of infrared light emitters; reflecting the infrared light from an inner surface of the display layer at a location where the display system is touched; detecting, using the plurality of detectors, the presence of reflected infrared light transmitted through the multilayer optical film; as well as Edge detection is performed on the transmitted infrared light to determine an area of ​​the display system along which the display system is touched.

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