Optical system with color filter for emissive display

Abstract

An electronic device can provide image light to an eyebox. A display can include a light source panel that emits the image light. A waveguide can direct the image light toward the eyebox. An input coupler can couple the image light into the waveguide, and an output coupler can couple the image light out of the waveguide. A color filter can be optically interposed between the light source panel and the output coupler. The color filter can filter the image light using a steep cutoff characteristic. The color filter can allow the image light to exhibit a desired color point while also allowing the light source panel to use light emitters having peak emission wavelengths that maximize efficiency of the light emitters and, thus, power efficiency of the device.

Description

[0001] This application claims priority to U.S. Provisional Application No. 63 / 077,424, filed on September 11, 2020, the entire contents of which are incorporated herein by reference. Background Technology

[0002] This invention relates generally to optical systems, and more specifically to optical systems for displays.

[0003] Electronic devices may include displays that present images to a user's eyes. For example, devices such as virtual reality and augmented reality headsets may include displays with optical elements that allow users to view the display.

[0004] Designing devices like these can be challenging. If not handled carefully, the components used to display content can be unsightly and bulky, consume excessive power, and fail to perform the expected level of optical performance. Summary of the Invention

[0005] Electronic devices such as head-mounted displays may have one or more near-eye displays that generate images for the user. A head-mounted display may be a pair of virtual reality glasses or an augmented reality headset, which allows an observer to view both computer-generated images and real-world objects in the observer's surrounding environment.

[0006] A near-eye display provides image light to the eye-friendly area. The display may include one or more light source panels that emit image light. A waveguide may have an input coupler that couples the image light into the waveguide. The waveguide may have an output coupler that couples the image light out of the waveguide and toward the eye-friendly area. A lens may be optically inserted between the light source panel and the input coupler, and may direct the image light toward the input coupler.

[0007] Color filters can be optically inserted between the light source panel and the output coupler. Color filters utilize steep cutoff characteristics to filter image light. Multiple color filters can be used to filter image light of different colors from different light source panels. If needed, a light combining filter assembly (X-plate) can be optically inserted between the light source panel and the lens (e.g., to combine image light of different colors from different light source panels).

[0008] If desired, the color filter can be stacked on a color filter panel. In another suitable arrangement, the color filter can be stacked on a prism wedge in a light-combining filter assembly. In yet another suitable arrangement, the color filter can be stacked on a partial reflector in a light-combining filter assembly. In yet another suitable arrangement, the color filter may include an absorbing coating located on a lens. If desired, the color filter may be a tilted dichroic filter in a lens. In yet another suitable arrangement, the color filter may be stacked on the reflective surface of the input coupler. If desired, the color filter may be a holographic optical element. The color filter allows image light to exhibit the desired color point while also allowing the light source panel to use a light emitter with peak emission wavelengths that maximize the efficiency of the light emitter and thus the power efficiency of the display. Attached Figure Description

[0009] Figure 1 These are illustrations of exemplary systems with displays based on some implementation schemes.

[0010] Figure 2 This is a top view of an exemplary optical system for a display according to some embodiments, the optical system having an emitting light source and a waveguide with an input coupler.

[0011] Figure 3 This is a top view of an exemplary optical system with an emitting light source and a color filter, according to some implementation schemes.

[0012] Figure 4 It is a top view of an exemplary optical system having a color filter on a portion of a reflector in a light-combining filter group, according to some embodiments.

[0013] Figure 5 This is a top view of an exemplary optical system according to some embodiments, having separate color filters for providing image light to separate input couplers.

[0014] Figure 6 This is a top view of an exemplary emitting light source panel that emits image light of multiple colors according to some implementation schemes.

[0015] Figure 7 This is a top view of an exemplary input coupler with a reflective color filter according to some implementation schemes.

[0016] Figure 8 This is a top view of an exemplary optical system with a tilted dichroic filter according to some implementation schemes.

[0017] Figure 9 It is a graph showing the normalized spectral intensity as a function of the wavelength of an exemplary emission source and a color filter, based on some implementation schemes.

[0018] Figure 10It is a graph showing the change of the cutoff wavelength of the color filter as a function of the average wavelength of the emitting light source, according to some implementation schemes. Detailed Implementation

[0019] Figure 1 An exemplary system is illustrated, having a device with one or more near-eye display systems. System 10 may be a head-mounted device having one or more displays, such as a near-eye display 14 mounted within a support structure (housing) 20. The support structure 20 may be shaped like a pair of glasses (e.g., a support frame), may be formed with a helmet-shaped housing, or may have other configurations for assisting in mounting and securing components of the near-eye display 14 to the user's head or near their eyes. The near-eye display 14 may include one or more display modules, such as display module 14A, and one or more optical systems, such as optical system 14B. Display module 14A may be mounted in the support structure, such as support structure 20. Each display module 14A may emit light 22 (sometimes referred to herein as image light 22), which is redirected toward the user's eye at an eye-friendly zone 24 using an associated optical system in optical system 14B.

[0020] The control circuit 16 can be used to control the operation of the system 10. The control circuit 16 may include storage and processing circuitry for controlling the operation of the system 10. The circuit 16 may include storage devices such as hard disk drive storage devices, non-volatile memory (e.g., electrically programmable read-only memory configured to form a solid-state drive), volatile memory (e.g., static or dynamic random access memory), etc. The processing circuitry in the control circuit 16 may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, graphics processing units, application-specific integrated circuits (ASICs), and other integrated circuits. Software code (instructions) may be stored on the memory in the circuit 16 and run on the processing circuitry in the circuit 16 to implement operations for the system 10 (e.g., data acquisition operations, operations involving the use of control signals to adjust components, image rendering operations to generate image content for display to a user, etc.).

[0021] System 10 may include input / output circuitry such as input-output device 12. Input-output device 12 may be used to allow system 10 to receive data from external devices (e.g., tethered computers, portable devices such as handheld devices or laptops) or other electrical devices, and to allow users to provide user input to head-mounted device 10. Input-output device 12 may also be used to collect information about the environment in which system 10 (e.g., head-mounted device 10) operates. Output components in device 12 may allow system 10 to provide output to a user and may be used to communicate with external electronic devices. Input-output device 12 may include sensors and other components 18 (e.g., image sensors, accelerometers, depth sensors, light sensors, haptic output devices, speakers, batteries, wireless communication circuitry for communication between system 10 and external electronic devices, etc.).

[0022] Display module 14A (sometimes referred to herein as display engine 14A, light engine 14A, or projector 14A) may include a reflective display (e.g., a display having an array of light sources that generate illumination light (which is reflected from a reflective display panel to produce image light), such as a liquid crystal on silicon (LCOS) display, a digital micromirror device (DMD) display, or other spatial light modulator), an emitting display (e.g., a micro-light-emitting diode (uLED) display, an organic light-emitting diode (OLED) display, a laser-based display, etc.), or other types of displays. Display module 14A is an example of an emitting display that includes an emitting light source, described herein by way of example. The emitting light source may include light-emitting diodes (LEDs) such as micro-light-emitting diodes (uLEDs), organic light-emitting diodes (OLEDs), or other LEDs, lasers, combinations of these components, or any other desired light-emitting component. Examples of emitting light sources including LEDs (e.g., uLEDs, OLEDs, or other LEDs) are described herein by way of example.

[0023] Optical system 14B can form lenses that allow an observer (see, for example, the observer's eye at eye zone 24) to view an image on display 14. Two optical systems 14B may be associated with the user's respective left and right eyes (e.g., for forming a left lens and a right lens). A single display 14 can generate images for both eyes, or a pair of displays 14 can be used to display images. In a configuration with multiple displays (e.g., a left-eye display and a right-eye display), the focal length and position of the lenses formed by components in optical system 14B can be selected such that any gaps between the displays will be invisible to the user (e.g., allowing the images from the left and right displays to seamlessly overlap or merge).

[0024] If desired, the optical system 14B may include components (e.g., an optical combiner, etc.) to allow optical combination of real-world image light from a real-world image or object 25 with virtual (computer-generated) images, such as virtual images in image light 22. In this type of system (sometimes called an augmented reality system), the user of system 10 can view both real-world content and computer-generated content overlaid on top of the real-world content. Camera-based augmented reality systems may also be used in device 10 (e.g., an arrangement where a camera captures a real-world image of object 25 and digitally merges that content with virtual content at optical system 14B).

[0025] If necessary, system 10 may include wireless circuitry and / or other circuitry to support communication with a computer or other external device (e.g., a computer that provides image content to display 14). During operation, control circuitry 16 may provide image content to display 14. This content may be received remotely (e.g., from a computer or other content source coupled to system 10) and / or may be generated by control circuitry 16 (e.g., text, other computer-generated content, etc.). The content provided to display 14 by control circuitry 16 may be viewed by an observer at eye level 24.

[0026] Figure 2 It is possible Figure 1 A top view of the exemplary display 14 used in system 10. (See figure) Figure 2 As shown, the display 14 may include one or more display modules such as display module 14A, and an optical system such as optical system 14B. Optical system 14B may include optical elements such as one or more waveguides 26. Waveguide 26 may include one or more laminated substrates (e.g., laminated planes and / or curved layers, sometimes referred to herein as "waveguide substrates") formed of optically transparent materials such as plastics, polymers, glass, etc.

[0027] If desired, waveguide 26 may also include one or more layers of holographic recording medium (sometimes referred to herein as a "holographic medium," "grating medium," or "diffraction grating medium") on which one or more diffraction gratings (e.g., holographic phase gratings, sometimes referred to herein as "holograms") are recorded. The holographic record may be stored as an optical interference pattern (e.g., alternating regions of different refractive indices) within a photosensitive optical material such as the holographic medium. This optical interference pattern can generate a holographic phase grating, which, when illuminated with a given light source, diffracts light to produce a three-dimensional reconstruction of the holographic record. The holographic phase grating may be a non-switchable diffraction grating encoded with a permanent interference pattern, or it may be a switchable diffraction grating where the emitted light can be modulated by controlling an electric field applied to the holographic recording medium. If desired, multiple holographic phase gratings (holograms) may be recorded within a holographic medium of the same volume (e.g., superimposed within a grating medium of the same volume). The holographic phase grating may be, for example, a volumetric hologram or a thin-film hologram in a grating medium. The grating medium may include photopolymers, gelatin such as dichromate gelatin, silver halide, holographic polymer dispersed liquid crystals, or other suitable holographic media.

[0028] The diffraction grating on waveguide 26 may include holographic phase gratings such as volumetric holograms or thin-film holograms, meta-gratings, or any other desired diffraction grating structure. The diffraction grating on waveguide 26 may also include surface-bump gratings formed on one or more surfaces of a substrate in waveguide 26, gratings formed by patterns of metallic structures, etc. The diffraction grating may, for example, include multiple multiplexed gratings (e.g., holograms) that at least partially overlap within a grating medium of the same volume (e.g., for diffracting light of different colors and / or light from different input angle ranges at one or more corresponding output angles).

[0029] Optical system 14B may include collimating optics such as collimating lens 34. Collimating lens 34 may include one or more lens elements that help direct image light 22 toward waveguide 26. Collimating lens 34 may be omitted if desired. If desired, display module 14A may be mounted on... Figure 1 The optical system 14B can be mounted within the support structure 20, and between portions of the support structure 20 (e.g., to form a lens aligned with the eye zone 24). Other mounting arrangements may be used if desired.

[0030] like Figure 2As shown, display module 14A may include one or more emission light sources 36 that generate (emit) image light 22 associated with image content to be displayed in eye-friendly area 24. In a suitable arrangement described herein by way of example, the emission light sources include one or more (e.g., three) emission light source panels. Each emission light source panel may include an array of light emitters such as LEDs (e.g., uLED, OLED, other LEDs, etc.) that emit light of a corresponding color (wavelength range). The image light 22 may be collimated using lenses such as collimating lens 34. Optical system 14B may be used to present the image light 22 output from display module 14A to eye-friendly area 24.

[0031] The optical system 14B may include one or more optical couplers such as an input coupler 28, a cross coupler 32, and an output coupler 30. Figure 2 In the example, input coupler 28, cross coupler 32, and output coupler 30 are formed at or on waveguide 26. Input coupler 28, cross coupler 32, and / or output coupler 30 may be completely embedded in the substrate of waveguide 26, partially embedded in the substrate of waveguide 26, or mounted to waveguide 26 (e.g., mounted to the outer surface of waveguide 26), etc.

[0032] Figure 2 The examples provided are merely illustrative. One or more of these couplers (e.g., cross coupler 32) may be omitted. Optical system 14B may include multiple waveguides stacked laterally and / or vertically relative to each other. Each waveguide may include one, two, all, or none of the couplers from couplers 28, 32, and 30. Waveguide 26 may be at least partially bent or folded if desired.

[0033] Waveguide 26 can guide image light 22 downward along its length via total internal reflection. Input coupler 28 can be configured to couple image light 22 from display module 14A into waveguide 26, while output coupler 30 can be configured to couple image light 22 from inside waveguide 26 to outside waveguide 26 and toward eye-friendly region 24. Input coupler 28 may include one or more input coupling prisms, one or more diffraction gratings, one or more facets or surfaces of waveguide 26, etc. As an example, display module 14A can emit image light 22 toward optical system 14B along the +Y direction. When image light 22 strikes input coupler 28, input coupler 28 can redirect image light 22 such that the light propagates within waveguide 26 via total internal reflection toward output coupler 30 (e.g., along the +X direction). When image light 22 strikes output coupler 30, output coupler 30 can redirect image light 22 away from waveguide 26 toward eye-friendly region 24 (e.g., along the -Y axis direction). For example, in a scenario where the cross coupler 32 is included at the waveguide 26, the cross coupler 32 can redirect the image light 22 in one or more directions as it propagates downward along the length of the waveguide 26.

[0034] The input coupler 28, cross coupler 32, and output coupler 30 may be based on reflective and refractive optics, or on holographic (e.g., diffractive) optics. In an arrangement where couplers 28, 30, and 32 are formed by reflective and refractive optics, couplers 28, 30, and 32 may include one or more reflectors (e.g., micromirrors, partial mirrors, louvered mirrors, or arrays of other reflectors). In an arrangement where couplers 28, 30, and 32 are based on holographic optics, couplers 28, 30, and 32 may include diffraction gratings (e.g., volume holograms, surface gratings, etc.).

[0035] In a suitable arrangement sometimes described herein as an example, the output coupler 30 is formed by a diffraction grating or micromirrors (e.g., a volume hologram recorded on a grating medium stacked between transparent polymer waveguide substrates, an array of micromirrors embedded in polymer layers interposed between transparent polymer waveguide substrates, etc.) embedded within the waveguide 26, while the input coupler 28 includes a reflecting prism mounted to the outer surface of the waveguide 26 (e.g., the outer surface defined by the waveguide substrate that contacts the grating medium or polymer layer used to form the output coupler 30).

[0036] In other words, display 14 can provide image light 22 from display module 14A to eye-friendly area 24 along optical path 38. Collimating lens 34, input coupler 28, cross coupler 32, and output coupler 30 can be (optically) inserted into optical path 38 (e.g., where cross coupler 32 is optically inserted into optical path 38 between input coupler 28 and output coupler 30, output coupler 30 is optically inserted into optical path 38 between cross coupler 32 and eye-friendly area 24, etc.). This example is merely illustrative, and in general, optical path 38 can include any desired optical components, including any desired number of holographic optical elements arranged in any desired manner.

[0037] In a suitable arrangement described herein as an example, light source 36 includes LEDs that emit image light 22. The LEDs can be arranged in an array within one or more emitting display panels (e.g., LED panels). Each display panel may include LEDs that emit light of a corresponding color. As an example, the LED panel may include a first LED panel with red LEDs emitting red light, a second LED panel with green LEDs emitting green light, and a third LED panel with blue LEDs emitting blue light. Achieving saturated color in red LEDs (e.g., red GaN-based LED pixels) and controlling the color point of green LEDs (e.g., GaN-based LED pixels) while maintaining a high level of panel emission power efficiency is challenging due to limitations in epitaxial growth techniques and limited emission spectral linewidths. This is because achieving and controlling desired wavelengths in the LED epitaxial film comes at the cost of LED efficiency (e.g., because longer wavelength InGaN red LEDs have poorer intraepitaxy efficiency and lower brightness due to lower luminance values). GaN-based LEDs may include, for example, GaN and / or AlGaN buffer layers, one or more InGaN quantum wells (QWs) located in an active layer (e.g., where the active layer is sandwiched between p-doped and n-doped regions), and an AlGaN electron blocking layer located between the active layer and the p-doped region.

[0038] To mitigate these issues and optimize system power efficiency, display 14 may include one or more color filters interposed on optical path 38 for spectral filtering of image light 22. The color filters may include long-pass filters, short-pass filters, band-pass filters, band-stop (notch) filters, or any other desired color filters. Color filters can be used to contain the color points of image light 22 without significantly sacrificing power efficiency and image quality. This may, for example, allow the use of LED spectra with specially configured (e.g., shorter) peak emission wavelengths, which in turn achieve much higher internal quantum efficiency and / or spectral average luminance, resulting in improved display panel power efficiency.

[0039] To meet the primary requirement of coloring a specific color gamut, red LEDs need to emit wavelengths longer than a certain limit. Meanwhile, blue and green LEDs need to emit wavelengths between these limits. The color gamut used by display 14 may include the DCIP3 color space or the sRGB color space, as just two examples. The wider spectrum of InGaN red LEDs typically requires a longer total spectral target. However, passing the red light emitted by the red LED through a long-pass filter can truncate the short-wavelength tail of the image light generated by the red LED, which helps to shift the color point to red. Meanwhile, due to the limited blue / green spectral linewidth, only a small range of wavelength tuning (e.g., + / - 3nm-4nm) is allowed for rendering DCIP3, which is difficult to control using epitaxial growth methods.

[0040] Generally speaking, color filters used to optimize the performance of display 14 can be inserted on optical path 38 at any desired location. Figure 3 This is a top view showing some possible locations for the color filter. (Example) Figure 3 As shown, display module 14A may include one or more light sources 36, such as a first light source 36R, a second light source 36G, and a third light source 36B. In a suitable arrangement described herein by way of example, light source 36R emits image light 22 at a red wavelength (e.g., red image light 22R) and is therefore sometimes referred to herein as red light source 36R; light source 36G emits image light 22 at a green wavelength and is therefore sometimes referred to herein as green light source 36G; and light source 36B emits image light 22 at a blue wavelength and is therefore sometimes referred to herein as blue light source 36B. This is merely illustrative, and in general, light sources 36R, 36G, and 36B may emit image light of any desired color (wavelength range). If desired, display module 14A may include fewer than all three light sources 36R, 36G, and 36B, or may include additional light sources 36 for emitting light in additional wavelength ranges.

[0041] Red light source 36R can be a panel comprising an array of red light emitting elements (red pixels) that emit red image light 22R. Blue light source 36B can be a panel comprising an array of blue light emitting elements (blue pixels) that emit blue image light. Green light source 36G can be a panel comprising an array of green light emitting elements (green pixels) that emit green image light. In a suitable arrangement described herein by way of example, the emitting elements (pixels) in light sources 36R, 36G, and 36B can be LEDs (e.g., uLED, OLED, or other types of LEDs).

[0042] Each light source 36 can emit image light 22 within a corresponding wavelength range. For clarity, Figure 3Only the red image light 22R is shown. The display module 14A may include optical elements such as a beam combining filter group 40 that combines the image light generated by each light source 36 into image light 22. The beam combining filter group 40 may include a first partial reflector 42 and a second partial reflector 44 intersecting with the partial reflector 42. The beam combining filter group 40 may include a prism wedge located between the partial reflectors 42 and 44, or may not have a prism. In scenarios where the beam combining filter group 40 includes a prism wedge, the beam combining filter group 40 may be referred to herein as a beam combining prism (X-cube) 40.

[0043] Partial reflectors 42 and 44 may include material interfaces such as coatings. The coatings may configure partial reflectors 42 and 44 to transmit image light of certain wavelengths while reflecting image light of other wavelengths. For example, partial reflector 44 may reflect red image light 22R while transmitting blue image light from light source 36B and green image light from light source 36G. Simultaneously, partial reflector 42 may reflect blue image light from blue light source 36B while transmitting green image light from light source 36G and red image light from light source 36R.

[0044] like Figure 3 As shown, the red light source 36R emits red image light 22R. A partial reflector 44 reflects the red image light 22R towards the collimating lens 34. The lens 34 directs (focuses) the red image light 22R onto the input coupler 28. The lens 34 may include elements inserted into... Figure 2 One or more lens elements 46 on the optical path 38. Input coupler 28 couples the red image light 22R into (… Figure 2 Waveguide 26. Input coupler 28 in Figure 3 In the example, it is shown as a reflective input coupling prism (e.g., for clarity, waveguide 26 is not shown in the image). Figure 3 (As shown in the figure). This is merely illustrative, and if desired, the input coupler 28 can be a transmission input coupling prism, a diffraction or holographic element, or any other desired input coupling structure for waveguide 26.

[0045] The display may include an optically inserted optical path 38 ( Figure 2One or more color filters 50 are disposed on the red light source 36R and the light combining filter group 40. If desired, the color filters 50 can be optically interposed between the red light source 36R and the light combining filter group 40. For example, the color filters 50 can be stacked on the surface of the light combining filter group 40 (e.g., the prism wedge used to form the light combining filter group 40). Alternatively, the color filters 50 can be spaced apart from both the light combining filter group 40 and the red light source 36R (e.g., in a scenario where the light combining filter group 40 does not include the prism wedge). Furthermore, the color filters 50 can be stacked on the surface of the red light source 36R (e.g., at position 52). Forming the color filters 50 on the surface of the red light source 36R can help minimize stray light. For example, forming the color filters 50 on the prism wedge used to form the light combining filter group 40 can reduce manufacturing costs and complexity relative to position 52.

[0046] If needed, the color filter 50 can be optically inserted between the light combining filter group 40 and the input coupler 28 in the optical path 38. Figure 2 For example, the color filter 50 may be inserted at one or more locations 48 between lens elements 46 in the collimating lens 34 and / or between the collimating lens 34 and the input coupler 28. Locations 48 may be between lens elements 46 or on the surface of the lens elements 46 (e.g., the color filter 50 may be formed by an absorbing coating on the surface of one or more lens elements 46). Multiple color filters 50 may be used if desired, such that the color filters 50 are located as follows: Figure 3 At one or more of the locations shown. When the red image light 22R is passed to the input coupler 28, the red image light can pass through and be filtered by the color filter 50. The color filter 50 can be used to spectrally filter the red image light 22R to include the color points of the image light 22 (e.g., so that the image light 22 contains the desired wavelength mix of the corresponding color gamut), thereby allowing the image at the eye-friendly area to exhibit (e.g., the desired wavelength mix of the corresponding color gamut), while also allowing the LEDs in the red light source 36R to exhibit the desired peak or average emission wavelength that maximizes the efficiency of the LEDs and therefore the power efficiency of the display 14 (e.g., the peak or average wavelength of the desired wavelength mix of the corresponding color gamut would not be provided without the color filter 50).

[0047] Although Figure 3The operation of color filter 50 on red image light 22R is illustrated, but color filters such as color filter 50 can also be used to filter green image light from green light source 36G and / or blue image light from blue light source 46B (e.g., at position 48, on the prism wedge of the light combining filter group 40, and / or on the light source itself). In a suitable arrangement sometimes described herein as an example, color filter 50 may be a long-pass filter (e.g., a long-pass filter that allows red wavelengths to pass through while blocking the shorter wavelength tails of red image light 22R) when used for filtering red image light 22R, and may be a band-pass filter when used for filtering blue or green image light. This example is merely illustrative, and in general, color filter 50 may be a short-pass filter, a long-pass filter, a band-pass filter, a band-stop filter, or any other desired filter for any of the colors produced by light sources 36R, 36G, and 36B.

[0048] In a suitable arrangement described herein as an example, the color filter 50 at position 52 or on the light-combining filter group 40 (e.g., as shown in the image) Figure 3 The color filter 50 (shown) can be an absorption filter that transmits filtered red image light 22. This is merely illustrative, and in general, the color filter 50 can be a reflection or transmission filter. Generally, by way of example, the color filter 50 can be a dichroic filter, an absorption filter (film), or a holographic filter.

[0049] If needed, light sources 36R, 36G, and 36B can be replaced by a single RGB panel. In these cases, the light combining filter group 40 can be omitted, and the color filter 50 can be located at one or more positions 48 in the collimating lens 34. In these scenarios, the color filter 50 can be optimized to appropriately allow light corresponding to the red, green, and blue bands of the image light emitted by the red, green, and blue light sources in the single RGB panel to pass through.

[0050] If necessary, the color filter 50 can be stacked on one or both of the partial reflectors 42 and 44. Figure 4 This is a top view showing how the color filter 50 can be layered onto the partial reflector 42. (See image.) Figure 4 As shown, the color filter 50 can be formed from a film or coating on the partial reflector 42. After the red image light 22R has been reflected from the partial reflector 44, the color filter 50 can filter the red image light. The color filter 50 can also filter the red image light 22R that has been directly received from the red light source 36R. Then, the filtered red image light 22R is transmitted through the partial reflector 42 and reflected from the partial reflector 44 towards the collimating lens. As an example, Figure 4 The color filter 50 can be an absorption filter that blocks the reflection of green light from the green light source 36G.

[0051] In this example, the blue light source 36B emits blue image light 22B transmitted by color filters 50 and partial reflectors 42 and 44. The green light source 36G emits green image light reflected by partial reflector 42. Additional color filters 50, such as green and / or blue bandpass filters (not shown), may be stacked on partial reflectors 44 and / or 42 for use with green and blue image light. These bandpass filters may be cross-coordinated between colors to allow red, green, and blue image light to be transmitted as image light 22 to the collimating lens.

[0052] If needed, a separate input coupler 28 can be used for each light source 36 in the display module 14A. In these scenarios, a separate color filter 50 can be used for each light source 36. Figure 5 This is a top view showing how individual input couplers and color filters can be used for each of the 36 light sources. Figure 5 As shown, each light source 36 can generate image light 22, which is coupled into waveguide 26 by a corresponding input coupler 28. Figure 2 Part of ).

[0053] If desired, the color filter 50 may be stacked on the surface of one or more light sources 36 (e.g., red light source 36R, blue light source 36B, etc.). Forming the color filter 50 on the surface of the light source 36 can, for example, minimize stray light in the system. In another suitable arrangement, the color filter 50 may be formed at or on the input coupler 28 (e.g., on the side of the input coupler 28 facing the light source 36).

[0054] If needed, red, green, and blue light sources can be integrated into a single RGB panel equipped with color filter 50. Figure 6 This is a top view showing how red, green, and blue light sources can be integrated into a single RGB panel equipped with color filters 50. (See image.) Figure 6 As shown, the light source 36 can be an emitting display panel having an array of light emitters / pixels (e.g., LEDs). Red LEDs emit red image light 22R oriented toward the collimating lens 34. Blue LEDs emit blue image light 22B oriented toward the collimating lens 34. Green LEDs emit green image light 22G oriented toward the collimating lens 34.

[0055] like Figure 6 As shown, color filters 50, such as a red color filter 50R and a green color filter 50G, can be stacked on the surface of the light source 36. The red color filter 50R can be superimposed on the red LED in the light source 36, and the blue color filter 50B can be superimposed on the blue LED. Figure 6In the example, the blue LED in light source 36 is not equipped with any color filter 50. This is merely illustrative, and a blue color filter can be stacked on top of the blue LED if desired. In a suitable arrangement described herein as an example, the red color filter 50R is a long-pass filter that allows red wavelengths to pass through while blocking the short-wavelength tail of the red image light, and the green color filter 50G is a green bandpass filter. This example is merely illustrative.

[0056] If needed, color filter 50 can be a reflective color filter stacked on the reflective surface of input coupler 28. Figure 7 This is a top view showing how color filter 50 can be a reflective color filter stacked on the reflective surface of input coupler 28. (See image.) Figure 7 As shown, the input coupler 28 can be a reflective input coupling prism mounted to the waveguide 26 (e.g., the surface of the waveguide 26 opposite the display module). The reflective input coupling prism may have a reflective surface 60 (e.g., a surface angled relative to a side surface of the waveguide 26). Image light 22 can pass through the waveguide 26 and the input coupler 28, and can be reflected from the reflective surface 60 into the waveguide 22. The color filter 50 can be adapted to an angle of total internal reflection (e.g., an angle within the total internal reflection range of the waveguide) to reflect only the desired wavelength of the image light 22 into the waveguide 26. This can be used to filter out other wavelengths from the image light reaching the eye-friendly area.

[0057] In a suitable arrangement Figure 7 The color filter 50 can be a holographic filter with one or more multiplexed holograms. The holograms can diffract light within a desired wavelength range into waveguide 26 for total internal reflection. The holograms can also diffract light of other wavelengths at angles outside the total internal reflection range of waveguide 26. For example, the holograms can diffract light of other wavelengths toward optical absorber 64, thereby diffracting these wavelengths from optical path 38 (…). Figure 2 Remove.

[0058] A single color filter 50 for reflecting red image light 22R, blue image light, or green image light may be stacked on the reflective surface 60. In another suitable arrangement, multiple color filters 50 for reflecting different colors may be stacked on the reflective surface 60. When using a single RGB panel to generate image light 22, the color filter 50 may be configured to allow (or reflect) image light of the corresponding red, green, and blue bands to pass through (or reflect image light of these bands).

[0059] If needed, color filter 50 can be a tilted dichroic filter. Figure 8 This is a top view showing different positions of the color filter 50 in an example where the color filter 50 is a tilted dichroic filter. (See attached image.) Figure 8As shown, the collimating lens 34 may include a tilted dichroic filter (e.g., a color filter 50) at position 66 between the collimating lens 34 and the input coupler. For example, the tilted dichroic filter may be tilted such that image light is incident on the filter at a non-orthogonal angle relative to the lateral plane of the filter. When the tilted dichroic filter is at position 66, the filter allows filtered image light (e.g., red image light 22R) to pass through while reflecting other wavelengths of the image light out of the optical path, such as to the aperture 72 (e.g., the aperture inserted between lens elements 46-1 and 46-2 of the collimating lens 34), as indicated by arrow 78.

[0060] As another example, the collimating lens 34 may include a tilted dichroic filter (e.g., color filter 50) at position 68 between lens elements 46-1 and 46-2. When the tilted dichroic filter is at position 68, the filter allows filtered image light (e.g., red image light 22R) to pass through while reflecting other wavelengths of the image light out of the optical path, such as to the light trap 74 (e.g., an optical absorber), as indicated by arrow 80.

[0061] As another example, the collimating lens 34 may include a tilted dichroic filter (e.g., color filter 50) at position 70 between lens elements 46-1 and 46-2. When the tilted dichroic filter is at position 70, the filter allows filtered image light (e.g., red image light 22R) to pass through while reflecting other wavelengths of the image light out of the optical path, such as via the light combining filter group 40 to the absorption mask 76. Although Figure 8 Only the operation of color filter 50 with red image light 22R is shown, but color filter 50 can similarly operate with green image light emitted by green light source 36G and / or blue image light emitted by blue light source 36B.

[0062] Although an LED emitting light at its peak wavelength that maximizes the efficiency of the LED and thus the power efficiency of the display is used, the use of a color filter 50 allows the display 14 to exhibit the desired color point. Without a color filter, the LED emitting light at its peak wavelength that maximizes the efficiency of the LED may not be able to recover the desired color point. To recover the desired color point, the color filter 50 can exhibit a relatively steep cutoff with varying wavelength.

[0063] Figure 9 This is a graph illustrating an example of how color filter 50 can filter red image light 22R to recover the desired color point of image light 22. Figure 9 In the diagram, the horizontal axis plots the wavelength (e.g., in nm). The vertical axis plots the spectral intensity normalized to the peak intensity of a given light emitter (e.g., a red LED in the red light source 36R). Figure 9 In the example, the color filter is a long-pass filter. This is merely illustrative, and if desired, the color filter can be a band-pass filter that absorbs light with wavelengths longer than the red emission range.

[0064] Figure 9 Curve 100 plots an example of the modulation spectral response of the red LED in light source 36R. As shown in curve 100, the red LED can achieve a peak emission wavelength λ. PEAK The peak intensity is exhibited at (e.g., red wavelength). The color filter 50 used to filter the red image light 22R generated by the red LED may have a transmission coefficient as given by curve 102. As shown by curve 102, the color filter may be a long-pass filter that allows relatively long wavelengths to pass through and blocks (absorbs) relatively low wavelengths (e.g., the color filter may absorb or deflect the orange spectral tail of the red image light).

[0065] To recover the desired color point in the image light, color filter 50 (curve 102) can exhibit a relatively steep cutoff characteristic. For example, curve 102 can exhibit a transmittance of 0.9 (90%) at wavelength λ2 and 0.1 (10%) at wavelength λ1. The steepness (sharpness) of the cutoff of color filter 50 can be characterized by a 90% / 10% cutoff characteristic W. For example, the 90% / 10% cutoff characteristic W can be the wavelength interval between 90% and 10% transmittance exhibited by the color filter (e.g., the 90% / 10% cutoff characteristic W can be equal to λ2-λ1). As used herein, the 90% / 10% cutoff characteristic W can also describe the filtering effect on the coating on partial reflectors 42 and / or 44 in a scene where the color filter is inserted between the light combining filter group 40 and the light source 36. The 90% / 10% cutoff characteristic can be used to characterize the rising or falling cutoff of color filter 50. The 90% / 10% cutoff characteristic is sometimes also referred to as the 10% / 90% cutoff characteristic.

[0066] Color filter 50 can also be configured with a corresponding cutoff wavelength λ CUT Characterization. Cutoff wavelength λ CUT It can be defined, for example, as half the wavelength between wavelengths λ2 and λ1 (e.g., half the wavelength corresponding to the 90% / 10% cutoff characteristic W). Generally speaking, a shorter 90% / 10% cutoff characteristic is associated with a steeper filter response (e.g., a steeper transition in the transmission coefficient as the wavelength changes from blocking image light to allowing image light to pass through), while a longer 90% / 10% cutoff characteristic is associated with a shallower filter response.

[0067] Figure 9The dashed curve 104 shows the spectral intensity of the red image light 22R that has been filtered by color filter 50 (e.g., by applying a long-pass filter associated with curve 102 to the LED response associated with curve 100). As shown by curve 104, color filter 50 can cut off the shorter wavelength tail associated with curve 100. For example, this can allow the red LED to be selected to exhibit a shorter peak emission wavelength or a shorter average emission wavelength (e.g., centroid wavelength) λ compared to the emission wavelength that would otherwise be possible (for recovering the desired color point) without the color filter. AVG (For example, where λ) AVG =sum(Int(λ)*λ) / sum(Int(λ)) where Int() is the integral of curve 100 over wavelength. Red LEDs operating at these shorter peak or average emission wavelengths can, for example, exhibit higher efficiency compared to red LEDs that peak at longer wavelengths. This can therefore be used to optimize the power efficiency of display 14, while color filter 50 is used to recover the desired color point, even though the peak or average emission wavelength of the red LED is shorter.

[0068] Figure 9 The example shown is merely illustrative. Curves 100-104 may have other shapes in practice. Although Figure 9 The example illustrates the operation of color filter 50 on red image light 22R, but other color filters 50 can also operate on green image light 22G emitted by a green light source and / or blue image light 22B emitted by a blue light source. For example, these color filters 50 can be bandpass filters. Bandpass filters may have a corresponding passband with a shorter cutoff wavelength λ on either side of the passband. CUT and longer cutoff wavelength λ CUT To recover the desired color point in image light 22, red, green, and / or blue color filters 50 are used with respect to each cutoff wavelength λ. CUT The 90% / 10% cutoff characteristic can be relatively steep (e.g., less than the maximum threshold 90% / 10% cutoff characteristic value, such as 10nm).

[0069] Generally speaking, the cutoff wavelength λ of each color filter in color filter 50 is... CUT It can be selected based on the peak or average emission wavelength of the corresponding LED. Figure 10 This indicates the cutoff wavelength λ. CUT How can we base our approach on the average wavelength λ of the corresponding LED? AVG To select the curve. Figure 10 In the figure, the average wavelength λ of the LED is plotted on the horizontal axis. AVG Furthermore, the cutoff wavelength λ was plotted along the vertical axis. CUT Curve 110 plots the average wavelength λ corresponding to each LED. AVGThe most effective filter cutoff wavelength λ OFF Generally speaking, any cutoff wavelength within the margin 114 between curve 110 and dashed curve 112 can recover the appropriate color point in the image light.

[0070] For any given color filter 50, the cutoff wavelength λ CUT This can be selected based on curves 110 and 112. For example, the most efficient average wavelength λ can be identified first. AVG (For example, it can be identified that produces a wavelength λ corresponding to the average or centroid.) AVG (Specific LED composition / design of the image light). Then, curves 110 and 112 can be used to select the cutoff wavelength λ of the color filter 50 used for filtering the image light. CUT For example, if the optimal efficiency and average wavelength λ are identified... A For LEDs, the corresponding cutoff wavelength λ on curve 110 is... CUT (For example, the cutoff wavelength λ) B This can be the most efficient cutoff wavelength for this LED. However, generally speaking, the wavelength corresponding to the average wavelength λ lies within the margin 114 between curves 110 and 112. A Any cutoff wavelength λ CUT It can be used with color filter 50.

[0071] Figure 10 The examples provided are merely illustrative. Curves 110 and 112 may have other shapes in practice (e.g., depending on the color gamut to be used). In other words, by selecting LEDs with optimized LED efficiency and therefore power efficiency for the display module 14A for the light sources 36R, 36G, and / or 36B, and then for exhibiting the corresponding cutoff wavelength λ... CUT and relatively steep cutoff characteristics (e.g., a relatively steep 90% / 10% cutoff characteristic W, such as...) Figure 9 One or more of the light sources (shown) provide a color filter 50, which maximizes the power efficiency of the display module 14A without sacrificing the color point in the image provided to the eye-friendly area.

[0072] For example, to recover the desired color point, the color filter 50 used to filter the red image light emitted by the red light source 36R can be a long-pass filter with a 90% / 10% cutoff characteristic W of less than or equal to 20 nm, less than 18 nm, less than 15 nm, 18 nm, less than 25 nm, or less than or equal to 30 nm, or another suitable steep cutoff characteristic. The cutoff wavelength λ of the red color filter... CUT The wavelength can be between 580nm and 605nm. The peak emission wavelength λ of the corresponding red LED in the red light source 36R is [not specified]. PEAKThe wavelengths can be between 580nm and 620nm. Although these wavelengths are described herein as examples in terms of peak wavelength, they can also be described in terms of average or centroid wavelength. The color filter 50 used to filter green image light emitted by the green light source 36G or blue image light emitted by the blue light source 36B can be a bandpass filter having a passband (bandpass) width of 20nm-80nm and a sharp cutoff on either side of the passband. The 90% / 10% cutoff characteristics of the green and blue color filters on either side of the passband can be, for example, less than 10nm, less than 5nm, less than 15nm, or another suitable steep cutoff characteristic. For example, the peak emission wavelength λ of the corresponding blue LED in the blue light source 36B... PEAK It can be between 457nm and 470nm, and the peak emission wavelength λ of the corresponding green LED in the green light source 36G is within the range of 457nm-470nm. PEAK It can be between 525nm and 550nm.

[0073] In a more specific example, when display 14 operates using the DCIP3 color gamut, the red LED in red light source 36R may have a peak emission wavelength λ between 605nm and 620nm. PEAK And the corresponding (red) color filter 50 can be a wavelength with an absorption cutoff wavelength between 595nm and 605nm (e.g., λ). CUT The display 14 uses a long-pass or band-pass red color filter (or a combination of color filters). Meanwhile, when the display 14 operates using the DCIP3 color gamut, the green LED in the green light source 36G can have a peak emission wavelength λ between 525nm and 550nm. PEAK Furthermore, the corresponding (green) filter 50 can be a bandpass green filter having a passband with a bandwidth (e.g., passband bandwidth) of 30nm-50nm and a sharp (steep) 90% / 10% cutoff characteristic on both sides of the passband of less than 10nm. Configuring the green filter in this manner can, for example, reduce the λ of the green image light... AVG The tolerance has been relaxed from 7nm to greater than 12nm.

[0074] When the display 14 operates using the sRGB color gamut, the red LED in the red light source 36R can have a peak emission wavelength λ between 600nm and 615nm. PEAK And the corresponding (red) color filter 50 can be a wavelength with an absorption cutoff wavelength between 580nm and 595nm (e.g., λ). CUT The display 14 uses a long-pass or band-pass red color filter (or a combination of color filters). When the display 14 operates using the DCIP3 or sRGB color gamut, the blue LED in the blue light source 36B may have a peak emission wavelength λ between 457nm and 470nm. PEAKFurthermore, the corresponding (blue) filter 50 can be a bandpass blue filter with a passband bandwidth (e.g., passband bandwidth) of 20nm-30nm and a sharp (steep) 90% / 10% cutoff characteristic on both sides of the passband of less than 10nm. The passband bandwidth can be defined as the cutoff wavelength λ at the upper end of the corresponding passband. CUT and the cutoff wavelength λ at the lower end of the corresponding passband CUT The wavelength difference between them (e.g., where the cutoff wavelength λ) CUT (Limited by the midpoint corresponding to the 90% / 10% cutoff characteristic).

[0075] In an example where color filter 50 is a dichroic long-pass filter (e.g., for filtering red image light 22R), color filter 50 may be formed of a multilayer thin-film interference filter if desired. The thin-film interference filter may comprise alternating layers of high-refractive-index material and low-refractive-index material (such as TiO2 and SiO2). As just one example, the thin-film interference filter may comprise a first SiO2 layer with a thickness between 2 nm and 3 nm, a second TiO2 layer with a thickness between 25 nm and 28 nm, a third SiO2 layer with a thickness between 90 nm and 100 nm, a fourth TiO2 layer with a thickness between 170 nm and 175 nm, a fifth SiO2 layer with a thickness between 90 nm and 100 nm, a sixth TiO2 layer with a thickness between 170 nm and 175 nm, a seventh SiO2 layer with a thickness between 90 nm and 100 nm, an eighth TiO2 layer with a thickness between 170 nm and 175 nm, and a ninth TiO2 layer with a thickness between 90 nm and 100 nm. The document describes a series of layers: a ninth SiO2 layer with a thickness between 100 nm and 170 nm; a tenth TiO2 layer with a thickness between 170 nm and 175 nm; an eleventh SiO2 layer with a thickness between 90 nm and 100 nm; a twelfth TiO2 layer with a thickness between 170 nm and 175 nm; a thirteenth SiO2 layer with a thickness between 90 nm and 100 nm; a fourteenth TiO2 layer with a thickness between 170 nm and 175 nm; a fifteenth SiO2 layer with a thickness between 60 nm and 70 nm; a sixteenth TiO2 layer with a thickness between 40 nm and 50 nm; and a seventeenth SiO2 layer with a thickness between 70 nm and 80 nm. Other stacks may be used. If desired, any color filter described herein may be a thin-film interference filter.

[0076] According to one embodiment, a display system configured to display image light is provided, the display system comprising: a waveguide having an input coupler configured to couple image light into the waveguide and an output coupler configured to couple image light out of the waveguide; a light source panel configured to emit image light; intersecting partial reflectors optically interposed between the light source panel and the input coupler, the intersecting partial reflectors being configured to orient the image light toward the waveguide; and a color filter optically interposed between the waveguide and the light source panel, the color filter being configured to filter the image light.

[0077] According to another implementation, the color filter is stacked onto the light source panel.

[0078] According to another embodiment, the display system includes a prism wedge located on the intersecting partial reflectors, and a color filter stacked on the prism wedge.

[0079] According to another embodiment, these intersecting partial reflectors include: a first partial reflector configured to transmit image light emitted by a light source panel; a second partial reflector configured to reflect image light emitted by the light source panel; and a color filter stacked on the first partial reflector.

[0080] According to another embodiment, the color filter is configured to transmit blue light and to absorb or deflect green light.

[0081] According to another embodiment, the color filter is further configured to allow red light to pass through while absorbing or deflecting the orange spectral tail of the red light.

[0082] According to another embodiment, the image light emitted by the light source panel includes red image light, and the color filter includes a filter selected from a group consisting of a long-pass filter and a band-pass filter.

[0083] According to another embodiment, the color filter is configured to filter the red image light with a 90% / 10% cutoff characteristic of less than or equal to 20 nm.

[0084] According to another implementation, the color filter is an absorption color filter.

[0085] According to another embodiment, the light source panel includes an array of micro light-emitting diodes (uLEDs) having a peak emission wavelength between 600 nm and 620 nm, and the color filter having a cutoff wavelength between 580 nm and 605 nm.

[0086] According to one embodiment, a display system configured to display image light is provided, the display system comprising: a waveguide having an input coupler configured to couple image light into the waveguide and an output coupler configured to couple image light out of the waveguide; a light source panel configured to emit image light; a lens optically inserted between the light source panel and the waveguide, the lens being configured to orient the image light toward the input coupler; intersecting partial reflectors optically inserted between the light source panel and the lens, the intersecting partial reflectors being configured to orient the image light toward the lens; and a color filter optically inserted between the light source panel and the output coupler, the color filter being configured to filter the image light.

[0087] According to another embodiment, the input coupler includes a reflective input coupling prism located on the waveguide, and the color filter is stacked on the reflective surface of the reflective input coupling prism.

[0088] According to another embodiment, the color filter includes a set of holograms configured to reflect a range of wavelengths of image light into the waveguide within the total internal reflection range, and the set of holograms is configured to reflect wavelengths of image light outside the wavelength range toward an optical absorber.

[0089] According to another embodiment, the color filter includes an absorbing coating located on the lens.

[0090] According to another embodiment, the display system includes an aperture, and the color filter includes a tilted dichroic filter optically inserted between a lens and an input coupler. The tilted dichroic filter is configured to transmit a wavelength range of image light to the input coupler and to reflect wavelengths of image light outside the wavelength range toward the aperture.

[0091] According to another embodiment, the display system includes: a light catcher; a first lens element located within a lens; and a second lens element located within the lens. The color filter includes a tilted dichroic filter optically inserted between the first and second lens elements, the tilted dichroic filter being configured to transmit a wavelength range of image light to the second lens element, and the tilted dichroic filter being configured to reflect wavelengths of image light outside the wavelength range toward the light catcher.

[0092] According to another embodiment, the display system includes: an absorption mask located between a light source panel and intersecting partial reflectors; a first lens element located within a lens; and a second lens element located within the lens. The color filter includes a tilted dichroic filter optically inserted between the first and second lens elements, the tilted dichroic filter being configured to transmit a wavelength range of image light to the second lens element, and the tilted dichroic filter being configured to reflect wavelengths of image light outside the wavelength range toward the absorption mask via the intersecting partial reflectors.

[0093] According to one embodiment, a display system configured to display image light is provided, the display system comprising: a waveguide having an input coupler configured to couple image light into the waveguide and an output coupler configured to couple image light out of the waveguide; a light source panel configured to emit image light; a lens optically disposed between the light source panel and the waveguide, the lens being configured to orient the image light toward the input coupler; and a color filter optically disposed between the light source and the output coupler, the color filter being configured to filter the image light with a 90% / 10% cutoff characteristic of less than or equal to 30 nm.

[0094] According to another embodiment, the light source panel includes a micro light-emitting diode (uLED) configured to emit image light at a peak wavelength between 600 nm and 620 nm, and the color filter has a cutoff wavelength between 580 nm and 605 nm.

[0095] In another embodiment, the light source panel includes a micro light-emitting diode (uLED) configured to emit image light at a peak wavelength between 525 nm and 550 nm, the color filter including a bandpass filter having a passband with a bandwidth between 30 nm and 50 nm, and the 90% / 10% cutoff characteristic on both sides of the passband being less than or equal to 10 nm.

[0096] In another embodiment, the light source panel includes a micro light-emitting diode (uLED) configured to emit image light at a peak wavelength between 457 nm and 470 nm, the color filter including a bandpass filter having a passband with a bandwidth between 20 nm and 30 nm, and the 90% / 10% cutoff characteristic on both sides of the passband being less than or equal to 10 nm.

[0097] According to another embodiment, the light source panel includes a red emitting diode (LED) configured to emit a first portion of image light, a green LED configured to emit a second portion of image light, and a blue LED configured to emit a third portion of image light. A color filter is stacked on the red LED, and the display system includes a bandpass filter stacked on the green LED, wherein the bandpass filter has a passband with a bandwidth between 30 nm and 80 nm.

[0098] According to another embodiment, the display system includes: an additional input coupler located on a waveguide; an additional light source panel configured to emit additional image light; and an additional color filter optically interposed between the additional light source panel and the additional input coupler, the additional color filter being configured to filter the additional image light, and the additional input coupler being configured to couple the additional image light into the waveguide.

[0099] According to another embodiment, the color filter is stacked on the light source panel, and the additional color filter is stacked on another light source panel.

[0100] According to another embodiment, the color filter is stacked on the input coupler, and the additional color filter is stacked on another input coupler.

[0101] The foregoing description is merely illustrative and various modifications can be made to the described implementation scheme. The described implementation scheme can be implemented independently or in any combination.

Claims

1. A display system configured to display an image light, the display system comprising: A waveguide having an input coupler configured to couple the image light into the waveguide and an output coupler configured to couple the image light out of the waveguide; A light source panel configured to emit the image light; Intersecting partial reflectors, optically interposed between the light source panel and the input coupler, wherein the intersecting partial reflectors are configured to orient the image light toward the waveguide; as well as A reflective color filter is optically inserted between the waveguide and the light source panel, wherein the reflective color filter is configured to filter the image light, wherein the reflective color filter is stacked on the input coupler, wherein the reflective color filter includes a set of holograms, wherein the set of holograms is configured to reflect a wavelength range of the image light into the waveguide within the total internal reflection range, and wherein the set of holograms is configured to reflect wavelengths of the image light outside the wavelength range toward an optical absorber.

2. The display system according to claim 1, further comprising: An additional light source panel, which is configured to emit additional image light; as well as Additional color filters, which are stacked on the input coupler, are configured to filter the additional image light.

3. The display system according to claim 2, wherein the image light comprises red image light and the additional image light comprises green image light.

4. The display system of claim 1, wherein the image light emitted by the light source panel comprises red image light, and wherein the reflection color filter comprises a filter selected from the group consisting of a long-pass filter and a band-pass filter.

5. The display system of claim 4, wherein the reflective color filter is configured to filter the red image light with a 90% / 10% cutoff characteristic of less than or equal to 20 nm.

6. The display system according to claim 4, wherein the image light includes red image light, blue image light and green image light.

7. The display system of claim 1, wherein the light source panel comprises an array of micro light-emitting diodes (uLEDs) having a peak emission wavelength between 600 nm and 620 nm, and the reflective color filter has a cutoff wavelength between 580 nm and 605 nm.

8. A display system configured to display an image light, the display system comprising: A waveguide having an input coupler configured to couple the image light into the waveguide and an output coupler configured to couple the image light out of the waveguide; A light source panel configured to emit the image light; A lens, optically inserted between the light source panel and the waveguide, wherein the lens is configured to direct the image light toward the input coupler, and wherein the lens includes a first lens element and a second lens element; Intersecting partial reflectors, optically interposed between the light source panel and the lens, wherein the intersecting partial reflectors are configured to direct the image light toward the lens; as well as A color filter, optically inserted between the lens and the input coupler or between the first lens element and the second lens element, wherein the color filter is configured to transmit the wavelength range of the image light to the input coupler and reflect wavelengths of the image light outside the wavelength range out of the optical path.

9. The display system of claim 8, wherein the color filter comprises an absorptive coating located on the lens.

10. The display system of claim 8, wherein the color filter comprises a tilted dichroic filter optically inserted between the lens and the input coupler, and the tilted dichroic filter is configured to transmit the wavelength range of the image light to the input coupler and reflect the wavelengths of the image light outside the wavelength range toward the aperture.

11. The display system of claim 8, wherein the color filter comprises a tilted dichroic filter optically inserted between the first lens element and the second lens element, the tilted dichroic filter being configured to transmit the wavelength range of the image light to the second lens element, and the tilted dichroic filter being configured to reflect the wavelengths of the image light outside the wavelength range toward an optical absorber.

12. The display system of claim 8, wherein the color filter comprises a tilted dichroic filter optically interposed between the first lens element and the second lens element, the optical absorber comprises an absorption mask located between the light source panel and the intersecting partial reflector, the tilted dichroic filter being configured to transmit the wavelength range of the image light to the second lens element, and the tilted dichroic filter being configured to reflect wavelengths of the image light outside the wavelength range toward the absorption mask via the intersecting partial reflector.

Images