Light projector

Abstract

A projector (10) for an augmented reality or mixed reality head wearable device is disclosed, comprising: a display (20) defining an optical axis (9) configured to receive light (41) to produce first supply light (40); an exit pupil (80) configured to couple the first supply light into a waveguide for an augmented reality or mixed reality head-mounted device, the exit pupil comprising a first region and a second region; a first optical arrangement (60) configured to couple first supply light from the display towards the exit pupil; and a first light blocker (70). A first partial reflection (50) as an undesired reflection of the first supply light may be reflected back into the light projector. The light projector is configured to spatially separate the supply light and the reflected light and to prevent the reflected light from being coupled into the waveguide with a light blocker.

Description

Technical Field

[0001] The present invention relates to a light projector, and in particular, to a light projector for augmented reality or virtual reality applications. Background Art

[0002] In an augmented reality head mounted device, a transparent waveguide is provided in front of the eye. A light projector projects light into the waveguide. Light from the projector may be coupled into the waveguide by an input diffraction grating. The light then propagates within the waveguide by total internal reflection, and an output diffraction grating couples the light out of the waveguide toward a viewer. In use, the viewer may see light from their external environment transmitted through the transparent waveguide as well as the projected light from the projector. This may provide an augmented reality experience.

[0003] Some light projectors used for augmented or virtual reality applications produce a main image that is intended to be displayed to a user and a second image or "ghost image" that is not intended to be generated or seen by the user. In some light projectors, the second image may be coupled into the waveguide and unintentionally displayed to the user, which may blur the main image and reduce the clarity of the main image. Additionally, in augmented reality applications, bright ambient lighting from the external environment may negatively affect the contrast between the main image and the environment as perceived by the user.

[0004] The object of the present invention is to solve these problems. Summary of the invention

[0005] According to a first aspect of the present invention, a projector for an augmented reality or mixed reality head-mounted device is provided, comprising: a display, which defines an optical axis and is configured to provide a first supply light; an exit pupil, which is configured to couple the first supply light into a waveguide for the augmented reality or mixed reality head-mounted device, the exit pupil comprising a first region and a second region; a first optical arrangement, which is configured to couple the first supply light from the display toward the exit pupil; and a first light blocker; wherein the first region is positioned off-center relative to the optical axis in a first direction so that a first partial reflection formed by a partial reflection of the first supply light at the exit pupil can be reflected toward the display and reflected back by the display to the second region of the exit pupil, and the second region is off-center relative to the optical axis in a second direction so that the first region and the second region are at least partially spatially separated from each other; wherein the first light blocker is positioned at the second region to at least partially prevent the first partial reflection from being coupled into the waveguide, while enabling the first supply light to be coupled into the waveguide through the first region.

[0006] In this way, the first partial reflection that is not desired as a second image (commonly referred to as a ghost image) to the user can be spatially separated from the first supply light that is the first image to the user when coupled into the waveguide. The first partial reflection can then be at least partially prevented from being coupled into the waveguide by a first light blocker. This improves the user's experience by alleviating the ghosting effect. In addition, separating the first partial reflection from the first supply light in this way can be implemented in known light projectors without changing the size or number of pixels of the display. This means that the second image can be removed in a manner that is substantially compatible with existing light projectors.

[0007] The display may be a reflective display, such as a liquid crystal on silicon (LCoS) display or a digital micromirror device (DMD). Alternatively, the display may be an emissive display, such as a micro-LED array, a micro-light emitting diode (uLED) display, or an organic light emitting diode (OLED) display. In other embodiments, the display may be a transmissive display, which operates using principles similar to reflective displays. In particular, a transmissive display utilizing an integrated color filter may be used.

[0008] Strictly speaking, the term "image" refers to light with a specific focus coupled into a waveguide, which will be perceived as an image by the user during use, while "supply light" refers to light supplied by a display for forming an image in a waveguide. For the sake of simplicity and conciseness, the term "supply light", which forms the (desired) image viewed by the user during use, may be used interchangeably with the term "image" throughout the text. For example, it may be pedagogically useful to refer to the supply light as an image before it is coupled into the waveguide and provided to the user as an image. Similarly, for the sake of brevity, "reflected light", which may be presented to the user as an (undesired) image if allowed to couple into the waveguide, may also be referred to as an image throughout the text. Specifically, the first supply light and the first partial reflection may be referred to as the first image and the second image, respectively. As further described below, the second supply light generated by the display and the corresponding second partial reflection may similarly be referred to as the third image and the fourth image, respectively.

[0009] The first region and the second region are preferably arranged on respective sides (i.e. opposite sides) of the optical axis. The first optical arrangement may include one or more optical components such as lenses, mirrors, beam splitters, wave plates, polarizers or other components suitable for coupling light from the display to the exit pupil. The first optical arrangement may be configured to operate as a projection optical element and may be described as a projection optical element.

[0010] Preferably, the display is configured to provide the first supply light to the first optical arrangement off-center relative to the optical axis so that the first supply light is coupled toward the first region of the exit pupil. The display may couple the first supply light only toward the first region, or at least not toward the second region. In this way, the display avoids coupling light toward the light blocker at the second region, where the light will be absorbed. In some cases, this avoids about half of the light from the display being absorbed by the light blocker. Therefore, the projector is more efficient.

[0011] The display preferably provides one or more light cones in the first supply light. The one or more light cones may have a principal ray that is not parallel to the optical axis. In this way, the first supply light may be directed toward a first region of the exit pupil. Thus, a first partial reflection of the first supply light may be directed back to the display and then directed toward a second region of the exit pupil, where the light may be absorbed or otherwise diffusely scattered.

[0012] Depending on the type of display, the display can be provided off-center to the first optical arrangement in a variety of ways. In one example, an emissive display can include multiple asymmetric collimators or lenses, one for each pixel, each asymmetric collimator or lens being oriented in the same manner and configured to suppress light from the corresponding pixel from propagating toward one side of the optical axis. In another example, a reflective or transmissive display can be illuminated asymmetrically to enable an image with a reduced cone angle to be produced.

[0013] The first supply light may travel centered along a path at a non-zero angle relative to the optical axis such that the first supply light is coupled toward the first region.

[0014] Preferably, the projector comprises: a first light source configured to illuminate the display to generate a first supply light; and a second optical arrangement configured to couple light from the first light source to the display; wherein the display is a reflective display, and the first light source and / or the second optical arrangement are configured to provide asymmetric illumination to the display with respect to the optical axis, so that the display can provide the first supply light to the first optical arrangement off-center with respect to the optical axis. In this way, the display can couple the first supply light toward the first area to avoid it being absorbed by the first light blocker.

[0015] The first light source and the second optical arrangement can be arranged to provide asymmetric illumination to the display in a variety of ways. In one example, the first light source can be configured to illuminate half of a component of an illumination optical device (such as a microlens array), wherein the half of the component is completely positioned on one side of the component and the optical axis. Alternatively, the illuminated half of the component can overlap with the optical axis while being preferably positioned toward one side of the component. In these cases, the first light source can be aligned parallel to the optical axis but offset relative to the optical axis. In another example, the first light source can illuminate the second optical arrangement symmetrically, and the second optical arrangement can be tilted or otherwise arranged to provide light to the reflective display centered at a non-zero angle relative to the optical axis.

[0016] The second optical arrangement may include one or more optical components such as lenses, mirrors, beam splitters, wave plates, polarizers, or other components suitable for coupling light from the reflective display to the exit pupil. The second optical arrangement may be configured as an illumination optics suitable for coupling light from the first light source to the reflective display.

[0017] Reflective and transmissive displays generally require similar optical setups. Thus, embodiments using a reflective display may alternatively use a transmissive display.

[0018] Preferably, the first light source illuminates an entrance pupil. Any suitable optical components may be provided at the entrance pupil to adjust the spatial and angular characteristics of the light from the first light source. Suitable optical components may be provided as part of a second optical arrangement to couple the light from the first light source to the display. In one example, a microlens array may be provided at the entrance pupil. In another example, a homogenous light pipe may be provided at the entrance pupil to adjust the light. The entrance pupil and suitable optical components may be aligned centrally with each other, and the first light source may preferably illuminate the entrance pupil on one side. This may enable the optical components disposed at the entrance pupil to couple the light from the first light source toward the display at a reduced cone angle compared to full illumination of the entrance pupil. The second light source may be similarly arranged to preferably illuminate the entrance pupil on the opposite side.

[0019] Preferably, the second optical arrangement comprises a microlens array. The microlens array may provide a compact means of coupling light to the reflective display. Alternatively, the second optical arrangement may comprise one or more homogenous light pipes instead of a microlens array.

[0020] Preferably, the first light source is configured to illuminate the microlens array, preferably on one side of the microlens array. In this way, a portion of the microlens array does not receive light from the first light source, so that the microlens array couples light from the first light source towards the reflective display at a reduced cone angle, i.e., a reduced angular size, compared to full illumination of the microlens array. This enables the reflective display to generate the first supply light and couple the first supply light towards the first optical arrangement off-center relative to the optical axis. The second light source can be similarly arranged on the opposite side of the microlens array.

[0021] Preferably, the microlens array is arranged at the entrance pupil where light enters the light projector from the first light source, and couples the light to the remaining components of the second optical arrangement. In this way, the asymmetric illumination of the microlens array can reduce the angular size of the light from the first light source at the display. The remaining components of the second optical arrangement can then be configured to couple the light towards the reflective display so that the entire linear range of the reflective display is illuminated.

[0022] Preferably, the projector includes a waveguide for an augmented reality or mixed reality head mounted device, which is configured to receive light from an exit pupil and couple the received light toward a user. In this way, the projector can provide an augmented reality image to the user. A transmission component of the first supply light can be coupled into the waveguide, and a reflection component of the first supply light can be reflected from the waveguide back to the exit pupil and pass through the exit pupil. In this way, the first partial reflection may be caused by a reflection component of the first supply light at the waveguide. In other examples, the partial reflection may be caused by a reflection from a refractive optical component configured to couple light from a display to the waveguide. In one example, the refractive optical component can be arranged at the exit pupil.

[0023] Preferably, the first light blocker is switchable between a first state and a second state, the first state being configured to at least partially prevent the first partial reflection from being coupled into the waveguide, and the second state being configured to enable light to be coupled into the waveguide. In this way, the light projector can operate in different modes that may require light to be able to enter the second area. Alternatively, the light blocker can be a baffle configured to absorb light having a wavelength emitted by the first light source, arranged to permanently cover the second area. In other alternative embodiments, the first light blocker can be any other suitable non-switchable light absorber.

[0024] In another example, the light blocker may be implemented with no input coupling element present in, on, or for the waveguide, such that light is "blocked" from entering the waveguide because light is not coupled in. In this case, the light blocker may not physically absorb part of the reflection, but rather block part of the reflection from coupling toward the user.

[0025] Preferably, the projector includes a second light source configured to illuminate the display to generate a second supply light, wherein the second light source and / or the second optical arrangement is configured to provide asymmetric illumination of the second optical arrangement relative to the optical axis, so that the display can provide the second supply light to the first optical arrangement at a position off-center relative to the optical axis, so that the second supply light is coupled toward the second area of ​​the exit pupil. In this way, the light projector can utilize the second light source in a variety of ways. In one example, in the event of a failure of the first light source, the light projector has a backup light source. In another example, the light projector can use each light source independently to create a more complex overall image using the first supply light and the second supply light. Providing two light sources also provides the light projector with greater flexibility in thermal management of the heat generated by each light source.

[0026] The first light source and the second light source can each be configured as a full-color display. Alternatively, the first light source and the second light source can be configured as monochromatic light sources of different colors. For example, the first light source and / or the second light source can be configured to emit one or more of red, green, blue, cyan or purple light. The first light source and the second light source can be configured as any light source known in the art suitable for augmented reality or mixed reality applications.

[0027] In some examples, the projector may include two waveguides, each configured to couple one of the first supply light and the second supply light into a different eye of the user.

[0028] Preferably, the second area is positioned off-center relative to the optical axis so that a second partial reflection formed by a partial reflection of the second supply light at the exit pupil can be reflected toward the display and reflected by the display back to the first area of ​​the exit pupil. In this way, the undesirable second partial reflection (which may also form a ghost image in the waveguide) can be spatially separated from the second supply light. This makes it possible to prevent the second partial reflection from being coupled into the waveguide without hindering the coupling of the second supply light into the waveguide. The illumination from the first light source and the second light source is respectively asymmetric; however, the illumination from each light source is asymmetric in an equal and opposite manner relative to the optical axis. In other words, the illumination from the second light source is symbolically a "mirror image" of the illumination from the first light source. This symmetry of the (asymmetric) illumination from the first light source and the second light source around the optical axis enables each of the first supply light and the second supply light and its corresponding partial reflection to be aligned with the first area and the second area, respectively.

[0029] Preferably, the light projector includes a second light blocker positioned at the first region, wherein the second light blocker is switchable between a third state configured to at least partially prevent the second partial reflection from being coupled into the waveguide and a fourth state configured to enable light to be coupled into the waveguide. In this way, the light projector can be switched between a plurality of different configurations or modes that allow the first light source and the second light source to be used independently or in various other ways, while also preventing unwanted ghost images from being coupled into the waveguide.

[0030] Preferably, the first light source and the second light source are configured to operate simultaneously when the first light blocker is in the second state and the second light blocker is in the fourth state. In this way, the light projector can provide a user with an image of greater intensity using two light sources. This can improve the contrast of the image perceived by the user under bright ambient lighting conditions in augmented reality applications. The display can be configured to provide two identical or very similar images using the first supply light and the second supply light, respectively, so that a brighter overall image is coupled toward the user's eyes. In such a configuration, the projector can be said to operate in "bright mode". Alternatively, if the display is a reflective display, the display can be configured to generate two different images using sequential illumination from the first light source and the second light source.

[0031] Preferably, the projector is configured to switch between a first configuration and a second configuration, in which the first light source is turned on, the second light source is turned off, the first light blocker is in a first state and the second light blocker is in a fourth state; in the second configuration, the first light source is turned off, the second light source is turned on, the first light blocker is in a second state and the second light blocker is in a third state. In this way, the projector can be operated in an "anti-ghosting" mode, in which two light sources are used in tandem to prevent either the first partial reflection or the second partial reflection, that is, the unwanted ghost image, from entering the waveguide. The projector can switch between a bright mode and an anti-ghosting mode. Alternating between configurations can also illuminate a larger area of ​​the exit pupil compared to operation with a single light source. This can produce a more uniform waveguide image and reduce pupil banding effects, while also eliminating or reducing the presence of ghost images.

[0032] The projector can be configured to quickly switch between the first configuration and the second configuration. For example, the projector can be configured to provide images to the user at a specific frame rate, and the projector can be configured to switch between the first configuration and the second configuration between each frame. In this way, each light source can increase the proportion of time each light source is turned off. Subsequently, this can reduce the maximum operating temperature of the first light source and the second light source and distribute the heat load between the two components.

[0033] The projector can be configured to continuously alternate between the first configuration and the second configuration. For example, the light projector can turn on the first light source or the second light source at a specific frame rate, and the light projector can continuously switch between each configuration for each frame. Compared with turning on a single light source for each frame, this enables each light source to work half the time. The frame rate can be selected at least about 24 frames / second so that the user can perceive smooth motion.

[0034] In other embodiments, the projector may alternate between the first configuration and the second configuration in an irregular pattern. For example, one light source may be turned on more frequently or for a longer period of time than another light source. This may be beneficial for keeping one light source as a backup light source.

[0035] Preferably, the first light blocker includes a polarizer configured to block light of a first polarization angle and a switchable wave plate configured to selectively shift light coupled from a second polarization angle toward the polarizer, the second polarization angle being perpendicular to the first polarization angle. The second light blocker can be configured in the same manner as the first light blocker. In this way, the first light blocker and / or the second light blocker can be quickly switched by applying a time-varying voltage to the switchable wave plate. In addition, the light projector can typically include a polarization beam splitter, and this configuration of the light blocker utilizes the polarization beam splitter in the existing design.

[0036] Alternatively, the first light blocker and / or the second light blocker can be configured in a variety of alternative ways. For example, the light blocker can be configured as a mechanical shutter that is configured to open or close quickly to allow light to reach or be blocked from reaching the waveguide via the first region and the second region, respectively. In another example, the light blocker can be configured as a transmissive liquid crystal panel that can quickly switch states so that the liquid crystals in the panel absorb light or allow light to pass freely through the panel.

[0037] Preferably, the first area and the second area are spatially separated along the longitudinal axis, and the longitudinal axis is oriented to minimize the distance between the display and the exit pupil. In this way, the existing design of the projector can be used to provide the first area and the second area without increasing the distance between the reflective display and the exit pupil, which may otherwise make the design and optimization of the light projector more complicated.

[0038] The exit pupil is preferably configured as an elliptical exit pupil, and the first and second regions are separated along the long axis of the elliptical exit pupil. In other embodiments, the exit pupil may be circular, or more than one exit pupil may be provided, wherein each exit pupil covers one of the first and second regions.

[0039] Preferably, the reflective display is a Liquid Crystal on Silicon (LCoS) display or a Digital Micromirror Device (DMD). Other types of reflective displays suitable for augmented or virtual reality applications may also be implemented.

[0040] In one example embodiment, the second optical arrangement comprises a polarizing beam splitter, and the display is a reflective display comprising an LCoS panel. In this case, the first light blocker and / or the second light blocker may preferably comprise a polarizer and a switchable wave plate. In another example embodiment, the second optical arrangement comprises a total internal reflection prism, and the display comprises a digital micromirror device.

[0041] A projector can also be described as a light projector.

[0042] According to a second aspect of the present invention, a projector for an augmented reality or mixed reality head-mounted device is provided, comprising: a display defining an optical axis, which is configured to provide a first supply light and a second supply light; an exit pupil, which is configured to couple the first supply light and the second supply light into one or more waveguides for the augmented reality or mixed reality head-mounted device, the exit pupil comprising a first area and a second area; and a first optical arrangement, which is configured to couple the first supply light and the second supply light from the display toward the exit pupil; wherein the display is configured to provide the first supply light and the second supply light to the first optical arrangement, respectively, off-center relative to the optical axis, so that the first supply light is coupled toward the first area of ​​the exit pupil, and the second supply light is coupled toward the second area of ​​the exit pupil; wherein the first area is positioned off-center relative to the optical axis in a first direction, and the second area is positioned off-center relative to the optical axis in a second direction, so that the first area and the second area are at least partially spatially separated from each other.

[0043] In this way, the projector can flexibly operate in a variety of ways using the display to generate the first supply light and the second supply light. In one example, the first supply light and the second supply light can be configured to provide two identical or two different images to the user to produce different optical effects. The display can be operated to provide the first supply light and the second supply light at the same time, or the projector can alternate between configurations that only provide one of the first supply light and the second supply light at a time. Preferably, the first region is positioned off-center relative to the optical axis in a first direction so that a first partial reflection formed by partial reflection of the first supply light at the exit pupil can be reflected toward the display and reflected back by the display to the second region of the exit pupil; and the second region is positioned off-center relative to the optical axis in a second direction so that a second partial reflection formed by partial reflection of the second supply light at the exit pupil can be reflected toward the display and reflected back by the display to the first region of the exit pupil; and the projector also includes a first light blocker positioned at the second region, wherein the first light blocker can be switched between a first state and a second state, the first state being configured to at least partially prevent the first partial reflection from being coupled into one or more waveguides, and the second state being configured to enable light to be coupled into the one or more waveguides.

[0044] In this way, when the first light blocker is in the first state, the projector can prevent the first portion from being reflected into the waveguide to improve the clarity of the first image generated by the first supply light. The first light blocker can be switched from the first state to the second state. Providing a switchable light blocker makes the light projector more flexible. For example, when the first supply light and the second supply light are generated simultaneously, this enables the second supply light to be coupled into the waveguide. Operating in this configuration enables the projector to provide a brighter image to the user, which can improve the contrast of the image perceived by the user. This is particularly useful in augmented reality or mixed reality applications, in which the external environment may reduce the perceived contrast under bright ambient lighting conditions.

[0045] Preferably, the light projector includes a second light blocker positioned at the first area, wherein the second light blocker can be switched between a third state and a fourth state, the third state being configured to at least partially prevent the second partial reflection from being coupled into one or more waveguides, and the fourth state being configured to enable light to be coupled into one or more waveguides. In this way, the projector can also prevent the second partial reflection from being coupled into the waveguide when providing the second supply light. Therefore, when only one of the first supply light or the second supply light is generated, the projector can provide an image with improved clarity.

[0046] Preferably, the projector further comprises: a first light source and a second light source, the first light source and the second light source being configured to illuminate the display to generate a first supply light and a second supply light, respectively; and a second optical arrangement, which is configured to couple light from the first light source and the second light source to the display; wherein the display is a reflective display, and wherein the first light source, the second light source and / or the second optical arrangement are configured to provide asymmetric illumination of the display relative to the optical axis, so that the display can provide each of the first supply light and the second supply light to the first optical arrangement off-center relative to the optical axis. In this way, the display can couple the first supply light toward the first area and couple the second supply light toward the second area. This can avoid the first light blocker and the second light blocker from unnecessarily absorbing light from the light source, thereby making the projector more efficient. As described with respect to the first aspect of the present invention, the first light source and / or the second optical arrangement can be arranged in a variety of ways to asymmetrically illuminate the display, so that the display can generate a first supply light and a second supply light with a reduced cone angle toward the first area and the second area, respectively.

[0047] Preferably, the projector is configured to switch between a first configuration and a second configuration, in which the first light source is turned on, the second light source is turned off, the first light blocker is in a first state, and the second light blocker is in a fourth state; in the second configuration, the first light source is turned off, the second light source is turned on, the first light blocker is in a second state, and the second light blocker is in a third state. In this way, the projector can use any of the light sources to provide an image to the user while preventing the first part of the reflection and the second part of the reflection-that is, preventing unwanted ghost images-from being coupled into the waveguide. The projector can be configured to switch quickly between the first configuration and the second configuration. For example, the light projector can be configured to provide an image to the user at a specific frame rate, and the light projector can be configured to switch between the first configuration and the second configuration between each frame. In this way, each light source can increase the proportion of time each light source is turned off. Subsequently, this can reduce the maximum operating temperature of the first light source and the second light source, and disperse the heat load between more components.

[0048] Preferably, the projector is configured to switch continuously between the first configuration and the second configuration. More preferably, the light projector can turn on the first light source or the second light source at a specific frame rate, and the light projector can switch continuously between each configuration for each frame. Compared with turning on a single light source for each frame, this enables each light source to work half the time.

[0049] In other embodiments, the projector may alternate between the first configuration and the second configuration in an irregular pattern. For example, one light source may be turned on more frequently or for a longer period of time than another light source. This may be beneficial for keeping one light source as a backup light source.

[0050] Preferably, the first light source illuminates an entrance pupil. Any suitable optical components may be provided at the entrance pupil to adjust the spatial and angular characteristics of the light from the first light source. Suitable optical components may be provided as part of a second optical arrangement to couple the light from the first light source to the display. In one example, a microlens array may be provided at the entrance pupil. In another example, a homogenous light pipe may be provided at the entrance pupil to adjust the light. The entrance pupil and suitable optical components may be aligned centrally with each other, and the first light source may preferably illuminate the entrance pupil on one side. This may enable the optical components disposed at the entrance pupil to couple the light from the first light source toward the display at a reduced cone angle compared to full illumination of the entrance pupil. The second light source may be similarly arranged to preferably illuminate the entrance pupil on the opposite side.

[0051] In some embodiments, the display is a reflective display, and the second optical arrangement includes a microlens array. More preferably, the first light source and the second light source are each configured to preferentially illuminate one of two opposite sides of the microlens array. In this way, the microlens array can couple light from each light source toward the reflective display at a reduced cone angle. This enables the reflective display to generate a first supply light and a second supply light, each of which is coupled toward the first optical arrangement off-center relative to the optical axis, so that the first supply light and the second supply light can be coupled toward the first area and the second area, respectively. In other embodiments, the microlens array may include one or more homogenous light pipes, or other optical components suitable for enabling the reflective display to couple the first supply light and the second supply light to the exit pupil toward the first area and the second area.

[0052] Preferably, the first light source and the second light source are configured to operate simultaneously. The display can be configured to generate the first supply light and the second supply light in a similar or identical manner so that the two corresponding images appear to the user as a single brighter image. This can improve the contrast of the overall image perceived by the user.

[0053] In some embodiments, the light projector includes a first waveguide and a second waveguide, and the exit pupil is configured to couple the first supply light into the first waveguide and the second supply light into the second waveguide. Preferably, the first waveguide is configured to couple the first supply light into a first eye of a user, and the second waveguide is configured to couple the second supply light into a second eye of the user. In this way, the image provided to the user can be optimized for a specific eye, or the image can be optimized to produce a specific effect in the overall image perceived by the user.

[0054] In other embodiments, the light projector includes a waveguide configured to receive the first supply light and the second supply light from an exit pupil and to couple the first supply light and the second supply light toward a user.

[0055] According to a third aspect of the present invention, there is provided a projector for an augmented reality or mixed reality display, comprising: an optical axis, a display configured to provide one or more light cones, an optical arrangement configured to couple the one or more light cones from the display toward an exit pupil; the exit pupil is configured to couple the one or more light cones into a waveguide for the augmented reality or mixed reality display; and a first light blocker; wherein (a) each light cone has a chief ray that is not parallel to the optical axis and is configured to propagate the one or more light cones to obtain a first region of the exit pupil; (b) the first light blocker is configured to couple the one or more light cones to a waveguide that is not parallel to the optical axis and is configured to propagate the one or more light cones to obtain a first region of the exit pupil; The invention relates to a method for manufacturing a light-emitting diode (LED) optical filter comprising: (a) a first light blocker positioned at the second region to at least partially prevent the light cone at the second region from being coupled into the waveguide, while enabling the light cone at the first region to be coupled into the waveguide through the first region. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0057] Figure 1 is a schematic diagram of a subsection of a known light projector;

[0058] Figure 2 is a schematic diagram of a subsection of a known light projector;

[0059] Figure 3 is a schematic diagram of a subsection of a known light projector;

[0060] Figure 4 is a schematic diagram of a sub-portion of an embodiment of the present invention;

[0061] Figure 5 is a schematic diagram of a sub-portion of an embodiment of the present invention;

[0062] Figure 6 is a schematic diagram of a sub-portion of an embodiment of the present invention;

[0063] Figure 7 is a schematic diagram of a sub-portion of an embodiment of the present invention;

[0064] Figure 8is a schematic diagram of an embodiment of the present invention;

[0065] Fig. 9 is a schematic diagram of an embodiment of the present invention;

[0066] Fig.10 is a schematic diagram of an embodiment of the present invention;

[0067] Fig.11 is a schematic diagram of an embodiment of the present invention;

[0068] Fig.12 is a schematic diagram of an embodiment of the present invention;

[0069] Fig.13 is a schematic diagram of a sub-portion of an embodiment of the present invention;

[0070] Fig.14 is a schematic diagram of a sub-portion of an embodiment of the present invention;

[0071] Fig.15 is a schematic diagram of an embodiment of the second aspect of the present invention;

[0072] Fig.16 is a schematic diagram of an embodiment of the present invention;

[0073] Fig.17 is a schematic diagram of an embodiment of the present invention;

[0074] Fig.18 is a schematic diagram of an embodiment of the present invention;

[0075] Fig.19 is a schematic diagram of an embodiment of the present invention; and

[0076] Fig. 20 is a schematic diagram of a portion of a display that can be used to implement embodiments of the present invention. DETAILED DESCRIPTION

[0077] Figure 1 A schematic diagram of a sub-part of a known light projector is shown.A light projector 1 is provided comprising a display 2 configured to generate or provide light forming a first image 4. Figure 1A plurality of exemplary rays of supply light that together form a first image 4 are shown. The display 2 emits the supply light that forms the first image 4 in the propagation direction indicated by the arrow A1 toward the optical arrangement 6, which is configured to receive the light from the display 2 and couple the received light toward the exit pupil 8. The optical arrangement 6 shapes the light that forms the first image 4 into an appropriate or desired size in the position and angle space, and guides the light toward the exit pupil 8. In particular, the optical arrangement 6 can shape the light so as to form the first image 4 at an infinite distance, so that the first image 4 is suitable for being received by a waveguide for augmented reality. The exit pupil 8 contains all the information required to output the first image 4 from the waveguide to the user's eyes. Specifically, the exit pupil 8 can couple the first image 4 into a waveguide (not shown) suitable for augmented or virtual reality applications. The waveguide typically includes an input diffractive optical element and an output element, the input diffractive optical element being configured to couple light from the exit pupil 8 into the waveguide, and the output element being configured to couple light representing the first image 4 out of the waveguide toward the user's eyes. In augmented reality or mixed reality headsets, the waveguides are typically arranged so that they are located in front of the user's eyes and couple the image out towards the eyes.

[0078] Strictly speaking, the term "image" refers to light having a specific focus coupled into a waveguide that will be perceived as an image by a user in use, while "supply light" refers to light supplied by the display but forming an image in a waveguide. For simplicity and conciseness, the term "supply light" that forms the (desired) image viewed by a user during use may be used interchangeably with the term "image" throughout. For example, it may be pedagogically useful to refer to the supply light as an image before it is coupled into a waveguide and provided to a user as an image.

[0079] The display 2, the optical arrangement 6 and the exit pupil 8 are arranged centered on the optical axis A. The optical axis A is aligned with the geometric center of the portion of the reflective display 2 that generates the first image 4. The optical axis A also passes through the center of each component in the known light projector 1 that interacts with light. If the display 2 is a reflective or transmissive display, this may include the light source and any illumination optics that may be needed to couple light from the light source to the reflective or transmissive display. In this way, the light projector 1 has rotational symmetry about the optical axis A. Therefore, the light in the known light projector 1 is typically completely centered on the optical axis A. The rotational symmetry of the optical axis A can be illustrated by two reference light rays that are equidistant and parallel to the optical axis A, and the paths of these two reference light rays through the known light projector 1 are mirrored relative to the optical axis A.

[0080] exist Figure 1In the schematic example shown, the components of the known light projector 1 are shown as being arranged linearly, and the light from the display 2 follows a substantially linear path to the exit pupil 8. However, in practice, the optical arrangement 6 may include one or more optical components that turn the light, for example, by 90 degrees. In this case, the optical axis A will also be turned by 90 degrees, so that the optical axis A and the center of each component that interacts with the light are aligned. In the known light projector 1, the display 2 is configured to emit a first image 4 centered on the optical axis A.

[0081] Figure 2 and Figure 3 A schematic diagram of a sub-section of a known light projector 1 is shown in each case in order to highlight a problem that has been found with such known light projectors.

[0082] As described above, the first image 4 is coupled towards the exit pupil 8 and into a waveguide (not shown). The first image 4 may be partially reflected from the input diffractive optical element of the waveguide, and this reflection may propagate back through the light projector 1 as a partial reflection of the first image 4. This partial reflection will form a second image 5 in the waveguide.

[0083] For the sake of brevity, "partial reflections" of an image formed by the supplied light, which might appear to the user as an (undesirable) image if allowed to couple into the waveguide, may also be referred to throughout as "ghost images".

[0084] The second image 5 is along Figure 2 The second image 5 is at least substantially centered on the optical axis A. The reflected light forming the second image 5 is propagated through the optical arrangement 6, which couples the reflected light back to the display 2. As a result of the reflective properties of the display 2, the second image 5 is reflected from the display 2, which again Figure 3 The second image 5 is shown to propagate in the direction of arrow A1. The second image 5 is coupled from the display 2 via the optical arrangement 6 to the exit pupil 8. The second image 5, which is typically an inverted representation of the first image 4, is then coupled as a ghost image into a waveguide which couples the second image 5 towards the user.

[0085] The second image 5 is generally undesirable and may obscure the first image 4, which is the image intended to be displayed to the user. The second image 5 is generally perceived by the user as a darker copy of the first image 4, which is generally inverted relative to the first image 4. Therefore, the second image 5 is sometimes referred to as a "ghost image". The second image 5 is constantly present in the overall image presented to the user during use, and reducing or eliminating the presence of the second image 5 is challenging. One focus of the present invention is to make the ghost image absent from the overall image presented to the user.

[0086] Figure 4A schematic diagram of a sub-portion of a light projector according to an embodiment of the invention is shown.A light projector 10 is provided comprising a display 20 configured to generate a first image 40 .

[0087] The display 20 may be a reflective display, a transmissive display, or an emissive display. When the display 20 is a reflective or transmissive display, a light source is provided that can illuminate the display with, for example, red, green, and blue or red, green, cyan, and violet light to obtain a full-color image; alternatively, when the display 20 is intended to produce a monochrome image, a monochrome light may be used. When the display 20 is an emissive display, it includes an integrated light source, such as a micro light emitting diode (uLED) or an organic light emitting diode (OLED) that directly generates the first image 40. The uLED or OLED may provide red, green, and blue light to produce a full-color image, or may be monochrome.

[0088] Figure 4 A plurality of exemplary light rays that together form a first image 40 are shown. The display 20 provides the first image 40 along a propagation direction indicated by arrow A1 to an optical arrangement 60 configured to receive light from the display 20 and couple the received light toward an exit pupil 80. The first image 40 is provided in a plurality of light cones, each light cone having a principal ray that is not parallel to the optical axis 9. The optical arrangement 60 shapes the first image 40 to an appropriate or desired size in position and angle space. The optical arrangement 60 shapes the light so that the first image 40 is formed at an infinite distance, which is a focal length suitable for receiving the first image 40 through an augmented reality waveguide. The exit pupil 80 receives the first image 40 and allows the first image 40 to be coupled into a waveguide (not shown) suitable for augmented or virtual reality applications. The waveguide typically includes an input diffractive optical element and an output diffractive element, the input diffractive optical element being configured to couple light from the exit pupil 80 into the waveguide, and the output diffractive element being configured to couple light from the waveguide out toward the user's eye. The waveguide can also be configured to expand the first image 40 using an intermediate grating or an output grating. "Extension of the image" means that the exit pupil containing the entire first image 40 is replicated on an area of ​​the output diffractive element, sometimes also called an "eye box", through which the user's eyes are viewed when they move through a certain range of angles, such as up, down, left, and right. The larger the eye box, the greater the possibility that the user will perceive the first image 40 at any viewing angle.

[0089] The display 20, the optical arrangement 60, and the exit pupil 80 are arranged centered about the optical axis 9. The display 20 and the exit pupil 80 are arranged perpendicular to the optical axis 9. The components of the optical arrangement 60 may also be arranged perpendicular to the optical axis 9. The optical axis 9 is aligned with the geometric center of the portion of the display 20 that generates the first image 40 and is perpendicular to the surface of the display 20. Therefore, the display 20 defines the optical axis 9. The optical axis 9 passes through Figure 4 The center of each of the components of the light projector 10 shown. In this way, the optical axis 9 defines a line of rotational symmetry so that two light rays emitted from the display 20 parallel to and equidistant from the optical axis 9 will follow similar but opposite paths through Figure 4 These reference rays will end up at the exit pupil 80.

[0090] It will be appreciated that, unlike the optical axis A of the known light projector 1, the optical axis 9 may not be centrally aligned with all components of the light projector 10, particularly as described below with reference to Figure 8 The described light source is used in conjunction with a reflective display.

[0091] exist Figure 4 In the schematic example shown, for the purpose of illustration, the components of the light projector 10 are arranged side by side, and the light from the display 20 appears to arrive at the exit pupil 80 along a substantially straight path. However, in practice, the optical arrangement 60 can generally include one or more optical components that turn the light, for example, 90 degrees. In this case, the optical axis 9 will also turn 90 degrees so that the center of each component that interacts with the light is aligned. Some components of the light projector, such as a beam splitter in a coaxial air guide configuration (birdbath configuration), can create a temporary branch path of light before recombining the light into a single beam. Such a component can be centered on the optical axis 9, and the optical axis 9 can be turned in the above manner only when the component is configured to cause the light to produce a resulting change in direction.

[0092] exist Figure 4 In an example embodiment, when the display 20 is a reflective display, it can be a liquid crystal on silicon (LCoS) display configured to generate an image based on the received light. The operation of the display 20 is described in more detail below. In other embodiments, the display 20 can be a digital micromirror device (DMD) display or any other type of reflective display. If the display 20 is an emissive display, it can be formed using a microLED or OLED array, which can include red, green and blue or red, green, cyan and violet light sources, or it can be monochrome.

[0093] For illustrative purposes, Figure 4The optical arrangement 60 shown in FIG. 6 includes a single focusing lens. In practice, the optical arrangement 60 may include any number of various optical components, such as lenses, mirrors, beam splitters, wave plates, polarizers, or other components suitable for coupling light from the display 20 to the exit pupil 80. The optical arrangement 60 may include components in a barrel or coaxial air-guide configuration or some other configuration.

[0094] Exit pupil 80 is configured as an elongated hole in the housing of light projector 10. Alternatively, exit pupil 80 may include two or more separate holes, or a single hole that is not elongated. In other embodiments, exit pupil 80 may include an optical component, such as clear glass, configured to couple first image 40 into a waveguide.

[0095] The waveguide is positioned relative to the exit pupil 80 so that the first image 40 is incident on the input grating of the waveguide. In other embodiments, intermediate optical components can couple the first image 40 from the exit pupil 80 to the input grating. The input grating is configured to couple the first image 40 into the waveguide, and the first image 40 propagates through the waveguide toward the output grating by total internal reflection. The output grating then couples the first image 40 toward the user's eye. In augmented reality applications, the waveguide is typically transparent so that the external environment can be observed through the waveguide. The first image 40 can be provided to the eye so that the first image 40 is viewed as an overlay on the surrounding environment.

[0096] Unlike the display 2 of the known light projector 1, the display 20 is configured to transmit the first image 40 off-center relative to the optical axis 9, such as Figure 4 In particular, the first image 40 is coupled centrally towards the optical arrangement 60 along a path that makes a non-zero angle with the optical axis 9. This enables the optical arrangement 60 to couple the first image 40 towards a first region 82 of the exit pupil 80 that is also off-center relative to the optical axis 9.

[0097] In particular, the first region 82 is offset relative to the optical axis 9 such that the optical axis 9 is tangential to the peripheral edge of the first region 82. The second region 84 of the exit pupil 80 is also disposed off-center relative to the optical axis 9 in the opposite direction to the first region 82. Similarly, the second region 84 is offset relative to the optical axis 9 such that the optical axis 9 is tangential to the peripheral edge of the first region 84.

[0098] Compared to the exit pupil 8, the exit pupil 80 is enlarged and Figures 4 to 6In the embodiment of the present invention, the width of the exit pupil 80 is twice that of the exit pupil 8. Specifically, each of the first region 82 and the second region 84 has a width equal to the width of the exit pupil 8, and the exit pupil 80 is elongated along the same axis that separates the first region 82 and the second region 84. As will be further described below in conjunction with other embodiments of the present invention, this enables the exit pupil 80 to be wide enough to receive additional images from other light sources.

[0099] In other example embodiments, the first region 82 and the second region 84 may partially overlap. Alternatively or additionally, the first region 82 and the second region 84 may also be positioned such that the optical axis 9 is positioned within the first region 82 and / or the second region 84 rather than being tangential thereto.

[0100] The first image 40 is coupled into the waveguide via the first region 82 of the exit pupil 80 so that the waveguide can provide the first image 40 to the user. In this example, the second region 84 does not receive any light that forms the first image 40. For example, in an augmented reality head mounted device, the user experiences the first image 40 as an overlay on the environment.

[0101] Figure 5 and Figure 6 Each shows a schematic diagram of a subsection of light projector 10 . Figure 5 and Figure 6 It is shown how the light projector 10 separates the first image 40 from the resulting ghost image.

[0102] The first image 40 may be partially reflected from the input diffractive element of the waveguide, as described above with respect to the known light projector 1, so that the second image 50 is along Figure 5 The direction A2 shown propagates from the exit pupil 80 toward the display 20. As previously described, the second image 50 is a "ghost" or "partial reflection" of the first image 40 and is coupled to the display 20 from the first region 82 of the exit pupil 80 by the optical arrangement 60. For purposes of clarity and illustration, only the second image 50 is shown. Figure 4 The first image 40 is shown in FIG. 4 , however, in practice, the first image 40 and the second image 50 will exist in the light projector 10 at the same time.

[0103] Advantageously, the second image 50 propagates from the first region 82 located to one side of the optical axis 9. This causes the second image 50 to propagate towards the optical arrangement 60 at a non-zero angle (i.e. along a path that is not parallel to the optical axis 9) and arrive at the optical arrangement 60 off-center relative to the optical axis 9, as shown in FIG. Figure 5This causes the optical arrangement 60 to couple the second image 50 toward the display 20, so that the second image 50 is incident on the display 20 at a non-zero angle of incidence relative to the surface of the display 20. The second image 50 is then reflected from the display at a reflection angle that is equal to and opposite to the angle of incidence. The reflected second image 50 is then as shown. Figure 6 It is shown propagating back in direction A1 towards the exit pupil 80 .

[0104] The reflective properties of the second image 50 may vary depending on the type of display used as display 20. For an LCoS display, the reflection is a specular reflection of light that has not undergone a change in polarization through interaction with the liquid crystal. For a DMD display, the reflection will be a zero-order diffraction. For a uLED or OLED display, the reflection is a specular reflection from the display surface. However, in any case, the final propagation direction of the reflected light is the same as the propagation direction of the specular reflection, where the angles of incidence and reflection are equal and opposite.

[0105] Back to Figure 6 , the second image 50 is coupled towards the optical arrangement 60 off-center relative to the optical axis 9. The second image 50 is coupled towards the optical arrangement 60 centered along a path at an angle to the optical axis 9, which is equal to the angle of incidence of the second image 50 when it encounters the reflective display 20. The optical arrangement 60 then couples the second image 50 towards the second region 84 of the exit pupil 80, such that the first region 82 does not receive any light that forms the second image 50. In this way, the first image 40 and the second image 50 can be spatially separated, which enables the second image 50 to be prevented from being coupled into the waveguide while enabling the first image 40 to be coupled into the waveguide.

[0106] Figure 7 Shows Figures 4 to 6 Schematic diagram of a sub-portion of a light projector 10, wherein a first image 40 and a second image 50 are simultaneously shown by exemplary light rays. Figure 7 , but for illustration purposes Figures 4 to 6 , the light projector 10 further includes a light blocker 70 configured to prevent the second image 50 from being coupled into the waveguide at the exit pupil 80. The light blocker 70 is located at the second region 84 and absorbs a portion of the reflected light that forms the second image 50. Therefore, the light blocker 70 prevents the second image 50 from entering the waveguide.

[0107] Figures 4 to 7 The light blocker 70 includes an absorbing material covering the second region 84 of the exit pupil. The material may be any material suitable for absorbing visible light. Alternatively, other forms of light blockers may be used. For example, the light blocker 70 may be a switchable light blocker that can be turned on or off, as described below with respect to other embodiments of the present invention.

[0108] One method in which the light projector 10 provides the first image 40 to the optical arrangement off-centre with respect to the optical axis 9 will now be described.

[0109] Figure 8 FIG. 1 is a schematic diagram of an exemplary light projector 10 implemented using a reflective display 21. The light projector 10 further includes a light source 30 disposed on one side of the optical axis 9. Figure 8 9 is shown as being above the optical axis 9. The light projector 10 includes an illumination optics 62, i.e. an additional “optical arrangement”, which in this case includes a microlens array 64. The illumination optics 62 is centered on the optical axis 9, and the microlens array 64 is oriented perpendicular to the optical axis 9. The light source 30 is configured to emit light 41 toward one side of the microlens array 64, which in turn couples the light 41 toward the rest of the illumination optics 62. The illumination optics 62 is configured to couple the light 41 received from the light source 30 to the reflective display 21. The illumination optics 62 also shapes the light and interacts with the light to impart the desired properties to the reflective display 21 for providing light that forms the first image 40 using the light 41 from the light source 30.

[0110] The light source 30 includes an LED array and a collimator. However, in other embodiments, the light source 30 can be or include any form of light source suitable for augmented or virtual reality applications. For example, the light source 30 can include one or more individual monochromatic light sources, each of which can be spatially combined into a single light beam incident on the microlens array 64.

[0111] For illustrative purposes, Figure 8 The illumination optics 62 shown in FIG. 6A includes a focusing lens. In practice, the illumination optics 62 may include any number of various optical components, such as lenses, reflectors, beam splitters, wave plates, polarizers, or other composite components suitable for coupling the light 41 from the light source 30 to the reflective display 21. The illumination optics 62 may include components in a barrel or coaxial air guide configuration or some other configuration. As described above with respect to the optical arrangement 60, each component of the illumination optics 62 is centrally aligned with the optical axis 9.

[0112] For illustrative purposes, Figure 8 The light projector 10 is shown in a linear configuration. However, the light projector 10 may be arranged in a more compact arrangement, for example with additional optical components in the illumination optics 62 as described above. Fig.16 One such arrangement is shown in . Fig.16A schematic diagram of a light projector 10 is shown in which the illumination optics 62 includes an additional reflector 66 that couples the light 41 from the light source 30 to the reflective display 21. The reflector 66 reflects the light 90 degrees toward the reflective display 21 to achieve a more compact arrangement. In one example, the reflector 66 can be positioned above or below the path from the reflective display 21 to the optical arrangement 60. It should be understood that Figure 8 and Fig.16 is a simplified embodiment and in practice the light projector can be significantly more compact.

[0113] Microlens array 64 is disposed at an entrance pupil through which light 41 from light source 30 passes to interact with the remaining components of light projector 10. In other embodiments, microlens array 64 may be an alternative optical component, such as a homogenizing light pipe, which may also be disposed at the entrance pupil, for example.

[0114] The light source 30 is arranged on one side of the optical axis 9 so as to illuminate the microlens array 64 preferably on one side of the microlens array 64. Figures 4 to 8 In the embodiment of the present invention, the light source 30 illuminates approximately half of the array; however, any off-center illumination of the microlens array 64 relative to the optical axis 9 will be sufficient for the purposes of the present invention. Compared to the uniform and complete illumination of the microlens array 64, this partial and off-center illumination of the microlens array 64 causes the light 41 to be coupled asymmetrically about the optical axis 9 toward the rest of the illumination optics 62 at a reduced angular magnitude. This in turn causes the light 41 to be coupled to the reflective display 21 through the rest of the illumination optics 62 at an asymmetric cone angle. This reduced cone angle can be Figure 8 Seen in Figure 8 It is shown that the reflective display 21 is preferably illuminated from above the optical axis 9 rather than from below the optical axis 9. Therefore, the first image 40 has a similarly reduced cone angle compared to the light 41 reaching the reflective display 21. This reduced cone angle of the first image 40 enables the reflective display 21 to provide the first image 40 off-center relative to the optical axis 9, so that the first image 40 is coupled into the first region 82 of the exit pupil 9.

[0115] Illumination optics 62 shapes and directs light 41 so that it is incident over the entire linear range of reflective display 21, such as Figure 8 This enables the reflective display 21 to generate light that forms the first image 40 having the same number of pixels as the first image 4, even though the angular size of the light 41 has been reduced.

[0116] Therefore, compared with the known light projector 1, Figures 4 to 8The illustrated coupling of light from the light source 30 to the first region 82 enables the first image 40 and the second image 50 to be spatially separated without compromising the size or number of pixels of the reflective display 21. Additionally, this method of separating the first image 40 from the second image 50 does not change the field of view of the first image 40 compared to the first image 4.

[0117] The first region 82 is displaced in equal and opposite directions relative to the optical axis 9 compared to the light source 30. This is partly due to the unit magnification of the light from the entrance pupil or, in this embodiment, from the microlens array 64 by the illumination optics 62 and the optical arrangement 60. However, other magnification levels and other relative positions are possible.

[0118] To generate the first image 40, light 41 from the light source 30 illuminates the reflective display 21. The surface of the reflective display 21 includes a pixel array that can be selectively switched between two or more states so that the incident light 41 from the light source 30 is selectively transmitted or blocked toward the optical arrangement 60. In this way, the reflective display 21 spatially modulates the incident light 41 to turn the illumination into a specific image. The reflective display 21 is configured as an LCoS display, however, alternatively, other reflective spatial light modulators such as DMD displays may be used.

[0119] exist Figure 8 In the configuration shown, the light projector 10 utilizes a light source 30 aligned with the optical axis 9 but displaced relative to the optical axis 9 so as to preferentially illuminate one side of the microlens array 64. This provides asymmetric illumination of the reflective display 21, thereby enabling the reflective display 21 to provide light that is off-center relative to the optical axis 9. In other embodiments, the light source 30 may be configured or arranged in other ways.

[0120] Fig.17 One such configuration is shown in FIG, which shows a schematic diagram of a light projector 10 in an alternative configuration. Figure 8 Unlike the arrangement of FIG. 6 , the light source 30 fully and uniformly illuminates the microlens array 64. However, the illumination optics 62, the microlens array 64 and the light source 30 are tilted relative to the optical axis 9 so that the light 41 from the light source 30 is coupled towards the reflective display 21 and is centered on a path that is at a non-zero angle to the optical axis 9. This alternative arrangement also enables the reflective display 21 to supply light to the optical arrangement off-center relative to the optical axis 9.

[0121] In other embodiments, the light source 30 and the illumination optics 62 may be arranged in various ways. The light source 30 may be arranged with any suitable combination of tilt and displacement relative to the optical axis 9. Alternatively, the light source 30 and the microlens array 64 may be fully aligned with and centered on the optical axis 9, and alternatively, the illumination optics 62 may shape the light 41 so that it is incident on the reflective display 21 asymmetrically relative to the optical axis 9.

[0122] Similar embodiments may include additional light sources. In such cases, additional entrance pupils and microlens arrays or any other suitable components may be required for each of the additional light sources to illuminate the illumination optics 62 from a different direction than the first light source 30 in order to couple the corresponding images to different regions of the exit pupil 80.

[0123] Fig. 9 1 shows a schematic diagram of a light projector according to another embodiment of the present invention. A light projector 100 is provided and includes a first light source 130, a first prism 132, a second light source 134, and a second prism 136. The first prism 132 and the second prism 136 are configured to couple light from the first light source 130 and the second light source 134 into an imaging system 160, respectively. The imaging system 160 includes Figure 8 The illumination optical device 62 including the microlens array 64, the reflective display 21 and the optical arrangement 60 are described. The components of the imaging system 160 operate in the same manner as described with respect to the light projector 10. The components of the imaging system 160 are provided in a compact arrangement suitable for use in an augmented or virtual reality head-mounted device, and are also centered on the optical axis 9 in the same manner as previously described. The light projector 100 also includes an exit pupil 180, which has a first area 182 and a second area 184 disposed off-center relative to the optical axis 9 on opposite sides of the optical axis 9. As described above with respect to the light projector 10, the first area 182 and the second area 184 are each disposed on one side of the optical axis 9 so that the optical axis 9 is tangential to each area. The first light blocker 170 is disposed at the second area 184. A waveguide 102 is provided and is configured to receive light from the first area 182 and the second area 184 of the exit pupil 180.

[0124] The first light source 130 and the second light source 134 may each include an arrangement of LEDs, such as an LED array or a single LED. The first light source 130 and the second light source 134 may also be provided with a collection or collimation optical device to collimate the light from the corresponding arrangement of LEDs. The collection or collimation optical device may also be referred to as a collimator.

[0125] In other embodiments, the first light source 130 and the second light source 134 may be any form of light source suitable for illuminating the reflective display 21 to generate an image. A first prism 132 and a second prism 136 may be included to provide a more compact arrangement of the light projector 100. However, other optical components may be provided to couple light from the first light source 130 and the second light source 134 to the imaging system 160. In an alternative embodiment, the reflective display 21 may be an emissive display, such as a uLED or OLED display as described above, in which case separate light sources 130, 134 may not be required.

[0126] The first light blocker 170 differs from the light blocker 70 in that the first light blocker 170 is switchable from a first state to a second state. In the first state, the first light blocker 170 absorbs light received from the imaging system 160 to prevent the light from coupling toward the waveguide 102. In the second state, the first light blocker 170 enables the light to couple toward the waveguide 102. The light blocker includes a polarizer 172 configured to absorb light of a first polarization angle while allowing light of a perpendicular polarization angle to pass through the polarizer 172 uninhibited. The polarizer 172 may be any type of polarizing filter known in the art. A wave plate 174 is disposed on the polarizer 172, between the polarizer 172 and the optical arrangement 60. For clarity, the first light blocker 170 is Fig. 9 180 and the waveguide 102, whose components are separated. In practice, the first light blocker 170 is arranged at the second region 184, and the wave plate 174 is arranged on the polarizer 172. In other embodiments, the first light blocker 170 can be positioned at any suitable position between the optical arrangement 60 and the waveguide 102.

[0127] Wave plate 174 is configured as a half-wave plate that rotates the polarization angle of light passing through wave plate 174 by 90 degrees. In addition, wave plate 174 is switchable, that is, it can be turned on or off. In one example, this can be achieved by applying different voltages to wave plate 174. When closed, first light blocker 170 is in a first state, and wave plate 174 can be completely transparent or does not interact with incident light. When wave plate 174 is turned on, first light blocker 170 is in a second state, and the polarization angle of light passing through wave plate 174 is turned to 90 degrees.

[0128] A linear polarizing film such as the polarizer 172 absorbs half the intensity of the incident non-polarized light. Therefore, in order to ensure that the polarizer 172 can block the entire intensity of the incident light, one of the optical arrangement 60 or the illumination optical device 62 includes an optical device that preferably transmits light of a given polarization, such as a polarizing beam splitter (not shown), which is configured to convert the non-polarized light from the first light source 130 and the second light source 134 into linear polarized light of a specific orientation. In particular, the polarizing beam splitter converts the light into an orientation parallel to the specific light-blocking orientation of the polarizer 172. Therefore, by default, the light from the first light source 130 and the second light source 134 is blocked by the polarizer 172, that is, unless the wave plate 174 is turned on. The polarizing beam splitter can be provided in a coaxial air-guided configuration including a quarter wave plate, which is configured to convert the incident non-polarized light beam into a polarized light beam, as is known in the art. In other embodiments, other polarization optical components may be provided alternatively or in addition to the polarizing beam splitter.

[0129] The wave plate 174 can be turned on to switch the first light blocker 170 from the first state to the second state by applying a voltage to the wave plate 174. Then, the polarization angle of the light reaching the wave plate 174 is turned 90 degrees, so that the light can pass through the polarizer 172 unimpeded. The wave plate 174 can be rapidly switchable so that the first light blocker 170 can be rapidly switched between the first state and the second state.

[0130] In other example embodiments, the switchable first light blocker 170 may be configured as a transmissive liquid crystal (LC) panel configured to change the orientation of the liquid crystal therein in response to a change in voltage. In this way, the LC panel may selectively absorb or not absorb incident light of a specific polarization angle. In another example, the first light blocker 170 may be a mechanical shutter configured to switch between an open state and a closed state.

[0131] Next, the operation of the light projector 100 will be described in more detail.

[0132] The first light source 130 emits light toward the prism 132, such as Fig. 9As shown. The prism 132 guides the light from the first light source 130 to one side of the microlens array 64 provided in the imaging system 160. Therefore, the light is provided to the microlens array 64 asymmetrically and off-center relative to the optical axis 9. As previously described, the light propagates through the imaging system 160 so that the light from the first light source 130 is received by the reflective display 21 at a reduced angle. The reflective display 21 uses the received light to generate a first image 140 off-center relative to the optical axis 9. The first image 140 is coupled toward the first region 182 of the exit pupil 180 and toward the waveguide 102. The first light blocker 170 is positioned at the second region 184 and therefore does not block the first image 140 coupled toward the first region 182.

[0133] like Fig. 9 As shown by the dashed line in FIG. 1 , the first image 140 is partially reflected from the waveguide 102 to form a second image 150. The second image 150 propagates toward the reflective display 21 until it is reflected by the reflective display 21 about the optical axis 9. The second image 150 then returns to the exit pupil 180, moving generally away from the optical axis 9 toward the second region 184.

[0134] The second image 150 is linearly polarized due to the polarizing beam splitter provided in the optical arrangement 60 or illumination optics 62 of the imaging system 160. The polarizing beam splitter linearly polarizes the light so that it is parallel to the specific blocking orientation of the polarizer 172. The second image 150 reaches the wave plate 174 of the first light blocker 170, which is Fig. 9 In the example shown, the polarizer 172 is turned off, meaning that the wave plate 174 does not interact with the second image 150. Thus, the polarizer 172 absorbs the second image 150 and prevents it from entering the waveguide 102.

[0135] The first light blocker 170 can be configured in a variety of different configurations. For example, the first light blocker 170 can receive light of a first orientation, and the polarizer 172 can be configured to block light of a second, perpendicular orientation. In this case, the wave plate 174 can be opened to block the incident light instead of allowing it to pass through the polarizer 172. The specific orientation will generally depend on the specific implementation of the imaging system 160.

[0136] In an augmented reality head mounted device, bright ambient lighting conditions may cause the image from a light projector disposed on the augmented reality head mounted device to appear faint or low contrast compared to the environment. In these cases, it may be desirable to have an additional light source that can be turned on to improve the contrast of the image perceived by the user. The light projector 100 may include a second light source 134, such as Fig.10 As shown, it can be opened to alleviate this problem.

[0137] Fig.10A schematic diagram of a light projector 100 operating in a "bright mode" is shown, wherein both the first light source 130 and the second light source 134 are turned on simultaneously. Light from the first light source 130 is formed into a first image 140 and coupled toward the first region 182, as described above with respect to Fig. 9 However, when the first light source 130 and the second light source 134 are operated simultaneously, the first light blocker 170 is configured to operate in the second state. Therefore, the wave plate 174 is turned on so that the polarization angle of the light received by the wave plate 174 is turned 90 degrees, thereby allowing the received light to pass through the polarizer 172 without being inhibited. This also makes the second image 150 (not shown for clarity) Fig.10 ) can enter the waveguide 102. However, the second image 150 (or any other partial reflection) tends to be significantly fainter than the first image 140 and thus may be significantly less visible or completely invisible to the user under bright ambient lighting conditions.

[0138] The second light source 134 is configured to operate in the same manner as the first light source 130, except that the position and orientation of the second light source 134 are flipped symmetrically about the optical axis 9. Therefore, the path followed by the light from the second light source 134 is a mirror image of the path taken by the light from the first light source 130, and is mirrored about the optical axis 9.

[0139] Specifically, the second light source 134 is directed by the second prism 136 to preferentially illuminate one side of the microlens array 64, such that the first light source 130 and the second light source 134 preferentially illuminate opposite sides of the array. Fig. 9 and Fig.10 In an embodiment of the present invention, the second light source 134 illuminates the remaining half of the microlens array 64. This in turn causes the microlens array 64 to provide light from the second light source 134 to the remaining parts of the illumination optics 62 asymmetrically with respect to the optical axis 9 at a reduced cone angle. The reduced cone angle causes the reflective display 21 to provide a third image 142 that is also off-center with respect to the optical axis 9, but off-center in the opposite direction to the first image 140. The optical arrangement 60 of the imaging system 160 is then configured to couple the third image 142 toward the second region 184 of the exit pupil 180. The third image 142 passes through the first light blocker 170 unimpeded, thereby allowing the third image 142 to be coupled into the waveguide 102.

[0140] Exit pupil 180 is elongated in the same manner as exit pupil 80, as described above with reference to Figure 8As described, the exit pupil 80 has space to accommodate the first image 140 and the third image 142. The optical arrangement 60 of the imaging system 160 is configured symmetrically with respect to the optical axis 9 so that the third image 142 is provided to the first region 182 with the same linear size as the first image 4, similar to the first image 140.

[0141] The light projector 10 provides the same field of view for the first image 140 and the third image 142, in particular the same field of view as the first image 4 of the known light projector 1. In bright mode, the light projector 100 can be programmed to generate the first image 140 and the third image 142 as the same image, so that the first image 140 and the third image 142 can be presented to the user as a single image with greater intensity. In augmented reality applications, this improves the perceived contrast relative to the environment.

[0142] Alternatively, in other operating modes, the first and second light sources 130, 134 and / or the reflective (or in other embodiments, emissive) display 21 may be used to generate different images.

[0143] The reflected component of the third image 142 at the waveguide 102 generates a fourth image 152, which is a ghost image of the third image 142. The approximate path of the fourth image 152 is Fig.10 The symmetry of light projector 100 about optical axis 9 enables fourth image 152 to be directed by imaging system 160 towards first region 182 where fourth image 152 can enter waveguide 102 .

[0144] In particular, the second light source 134 also provides light to the illumination optics 62 asymmetrically with respect to the optical axis 9. However, this asymmetry is equal and opposite to the asymmetrical manner in which the first light source 130 illuminates the illumination optics 62. This mutual asymmetry about the optical axis 9 allows the first image 140 and the fourth image 152 to be coupled toward the first region 182; while allowing the second image 150 and the third image 142 to be coupled toward the second region 184.

[0145] Similar to the second image 150, the fourth image 152 may be very faint or invisible under bright lighting conditions. This makes the presence of the second image 150 and the fourth image 152 less obtrusive when the light projector 100 is operated in a bright mode.

[0146] However, providing two separate light sources in the manner described above may have advantages in other situations where a bright mode may not be required.

[0147] Fig.11 and Fig.12An alternative embodiment of the light projector 100 is shown, which includes a second light blocker 171 disposed at the first region 182. The second light blocker 171 includes a polarizer 176 and a wave plate 178, each of which is configured to operate in the same manner as the previously described polarizer 172 and wave plate 174. The second light blocker 171 is switchable between a first state, in which the wave plate 178 does not change the polarization angle of the incident light, and a second state, in which the wave plate 178 turns the polarization angle of the incident light by 90 degrees so that it can be absorbed by the polarizer 176, as described with respect to the light blocker 170.

[0148] exist Fig.11 and Fig.12 In an embodiment, the second light blocker 171 is provided as a separate light blocker from the first light blocker 170. In other embodiments, the first light blocker 170 and the second light blocker 171 may be configured as a single polarizer covering the exit pupil 180, wherein two independently switchable wave plates are provided on the shared polarizer.

[0149] The light projector 100 may be configured to switch between a first configuration in which only the first light source 130 is turned on and a second configuration in which only the second light source 134 is turned on.

[0150] Fig.11 The light projector 100 is shown operating in a first configuration. In the first configuration, the second light blocker 171 is configured to operate in a second state. Thus, the wave plate 178 turns the polarization angle of the light forming the first image 140 by 90 degrees so that the polarizer 172 does not prevent the first image 140 from entering the waveguide 102. Thus, the second image 150 is generated and passes through the second light blocker 171 to be guided by the imaging system 160 toward the second region 184. In the first configuration, the first light blocker 170 is configured to operate in a first state to prevent the second image 150 from entering the waveguide 102.

[0151] Fig.12 The light projector 100 is shown operating in a second configuration. In the second configuration, the first light blocker 170 is configured to operate in the second state. Thus, the wave plate 174 turns the polarization angle of the light forming the third image 142 by 90 degrees so that the polarizer 176 does not prevent the third image 142 from entering the waveguide 102. Thus, the fourth image 152 is generated and passes through the first light blocker 170 to be guided by the imaging system 160 toward the first region 182. In the second configuration, the second light blocker 171 is configured to operate in the first state to prevent the fourth image 152 from entering the waveguide 102.

[0152] Enabling light projector 100 to operate in both the first configuration and the second configuration provides many different benefits to light projector 100. For example, the arrangement can provide functional redundancy so that even if one of first light source 130 or second light source 134 fails, light projector 100 can still operate to provide images to a user. Fig.11 and Fig.12 The embodiment enables this redundancy while continuing to prevent ghost images from being displayed to the user. In addition, the light projector 100 is capable of generating the first image 140 and the third image 142 having the same field of view as the first image 4. This further improves the redundancy of the first light source 130 and the second light source 134, because each of the first light source 130 and the second light source 134 can provide a full field of view to the user.

[0153] Light projector 100 can be configured to switch quickly between these first configuration and second configuration with multiple possible modes. In one example, light projector 100 can alternate between first configuration and second configuration continuously and periodically at a rate equal to the frame rate of the projector to provide an image to the user. This enables the first light source 130 to provide an image on a frame, and the second light source 134 can provide an image on the next frame in a repeating pattern. Operating in this way enables the first light source 130 and the second light source 134 to be opened to reach a single light source and be opened to provide an image at the same frame rate. Half the time. The thermal management of the first light source 130 and the second light source 134 can be improved in this way, for example, by reducing the maximum temperature of the first light source 130 and the second light source 134 operations.

[0154] Light projector 100 may also be configured to operate in other regular or irregular patterns, where alternation between the first configuration and the second configuration does not necessarily occur between every frame. Fig.11 and Fig.12 In other uses of embodiments, light projector 100 can use each light source to provide a completely different image rather than the same image.

[0155] The light projector 100 can also be configured to operate in a third configuration, in which the light projector 100 can operate in a bright mode. In the third configuration, both the first light source 130 and the second light source 134 are turned on, and both the first light blocker 170 and the second light blocker 171 are in the second state, so that no light is blocked from coupling into the waveguide 102. This makes Fig.11 and Fig.12 The implementation method can be Fig. 9 and Fig.10 The embodiment operates in the same manner as in bright mode. Fig.11 and Fig.12The light projector 100 may be switched from the bright mode (ie, the third configuration) to an "anti-ghosting" mode, in which the light projector 100 switches between the first configuration and the second configuration as described above.

[0156] In another example embodiment (not shown), light projector 100 may include multiple waveguides. For example, a first waveguide may be configured to couple a first image into a first eye of a user. A second waveguide may be configured to couple a third image 142 into another eye of a user. In this case, second image 150 is generated due to reflection of first image 140 from the first waveguide. Similarly, fourth image 152 is generated due to reflection of third image 142 from the second waveguide. Such an embodiment of light projector 100 may be similar to that described above with respect to Figures 9 to 12 Any of the embodiments described may operate and be configured in the same manner.

[0157] Figures 9 to 14 The light projector 100 in any of the figures may include an optical element disposed in the path of the first image, the optical element being configured to angularly shift the first image 140 relative to the third image 142. The optical element is configured to angularly shift the first image 140 relative to the third image 142 by an angle corresponding to the angular width of half a pixel of the reflective display 21. This can artificially increase the resolution of the overall image provided to the user. The optical element can be a refractive wedge of glass, or any other suitable material for refracting light. Any other component may also be implemented. In one example, the optical element can be provided as a layer on one of the first light blocker 170 or the second light blocker 171, or as a separate component within the optical arrangement 60.

[0158] Fig.13 and Fig.14 Shows Figures 9 to 12 Schematic diagram of an example imaging system 160 . Fig.13 Imaging system 160 is shown from a first viewpoint. Fig.14 The imaging system 160 is shown rotated, as shown by Fig.13 and Fig.14 A plurality of example light rays are also shown to illustrate how light is coupled from the reflective display 120 to the first region 182 and the second region 184 of the exit pupil 180. In this example imaging system 160, the optical arrangement 60 includes a lens 164 configured to direct light to the polarizing beam splitter 166. For clarity, the Fig.13 and Fig.14 The first light blocker 170 and the second light blocker 171 are omitted.

[0159] As from Fig.14As best seen, reflective display 120 couples light toward polarizing beam splitter 166 in a direction substantially parallel to the y-axis. Fig.13 As best seen in FIG. 1 , first region 182 and second region 184 are separated along the x-axis rather than along the y-axis. This is advantageous over separation along the y-axis, which would require an increase in the distance between exit pupil 180 and reflective display 120 compared to known light projectors. In particular, separating first region 182 and second region 184 in this manner allows for the use of a shorter focal length, which results in a larger field of view for a given display size. Furthermore, designs and optimizations of existing imaging systems can even be used with the enlarged exit pupil 180 of the present invention. This increases backward compatibility and reduces the design cost and difficulty of light projector 100. Fig.13 and Fig.14 The separation axis between the first region 182 and the second region 184 can also be applied to Figures 4 to 8 The light projector 10.

[0160] Imaging system 160 may have other configurations, and optical arrangement 60 may have other types of components. In this case, the axis along which first region 182 and second region 184 are separated may be selected to avoid increasing the distance between reflective display 120 and exit pupil 180.

[0161] In reference Figures 9 to 14 In the described embodiments, the first image 140 and the third image 142 may be referred to as the first supplied light and the second supplied light, as previously described. Similarly, the second image 150 and the fourth image 152 may be referred to as the first partial reflection and the second partial reflection.

[0162] Fig.15 A schematic diagram of a light projector 200 according to another embodiment of the present invention is shown.

[0163] A light projector 200 is provided and includes a first light source 230, a first prism 232, a second light source 234, and a second prism 236. The first prism 232 and the second prism 236 are configured to couple light from the first light source 230 and the second light source 234, respectively, into an imaging system 260. The imaging system 260 includes Figures 4 to 14The illumination optics 62 including the microlens array 64, the reflective display 21 and the optical arrangement 60 are described. The components of the imaging system 260 operate in the same manner as described with respect to the light projector 10 and the light projector 100. The components of the imaging system 260 are provided in a compact arrangement suitable for use within an augmented or virtual reality head mounted device, and are also centered on the optical axis 9 in the same manner as previously described. The light projector 200 also includes an exit pupil 280 having a first region 282 and a second region 284 disposed off-center relative to the optical axis 9 on opposite sides of the optical axis 9. As described above with respect to the light projector 10, the first region 282 and the second region 284 are each disposed on one side of the optical axis 9, on opposite sides. A waveguide 202 is provided and is configured to receive light from the first region 282 and the second region 284 of the exit pupil 280. Light projector 200 is configured to generate first image 240 , resulting in second image 250 , and third image 242 , resulting in fourth image 252 , in the same manner as light projector 100 .

[0164] As described above, the first image 240 and the third image 242 may be referred to as the first supplied light and the second supplied light. Similarly, the second image 250 and the fourth image 252 may be referred to as the first partial reflection and the second partial reflection.

[0165] Light projector 200 is configured to operate in substantially the same manner as light projector 100. Light projector 200 differs from light projector 100 in that light projector 200 does not include any light blocker. Thus, light projector 200 can separate first image 240 from second image 250 and third image 242 from fourth image 252. However, light projector 200 cannot prevent second image 250 or fourth image 252 from being coupled into waveguide 202.

[0166] Light projector 200 may also operate in different modes similar to the modes of light projector 100. Light projector 200 may operate in different modes similar to the modes of light projector 100. Fig.10 The bright mode operates in which the first image 240 and the third image 242 are the same image and are displayed simultaneously to increase the contrast of the overall image seen by the user.

[0167] In another mode, projector 200 can also switch between a first configuration in which only first light source 230 is turned on and a second configuration in which only second light source 234 is turned on. Similar to light projector 100, light projector 200 can quickly switch between these configurations to improve thermal management of light projector 200 or perform other functions.

[0168] In another example embodiment (not shown), the light projector 200 may include multiple waveguides. For example, the first waveguide may be configured to couple the first image 240 into the first eye of the user. The second waveguide may be configured to couple the third image 242 into the other eye of the user. In this case, the second image 250 is generated due to the reflection of the first image 240 from the first waveguide. Similarly, the fourth image 252 is generated due to the reflection of the third image 242 from the second waveguide.

[0169] The above embodiments utilize a display that can direct light toward a specific area of ​​the exit pupil. Typically, this enables the supply light that forms the first image in the waveguide to avoid encountering a light blocker (or a light blocker that is in a light blocking state) so that the supply light is not wasted. However, in simpler embodiments, partial reflections of the first image into the waveguide can still be prevented without using a display that supplies light to the optical arrangement off-center relative to the optical axis 9.

[0170] Fig.18 A schematic diagram of such an embodiment of a light projector 10 is shown, wherein the display 20 supplies light to the optical arrangement 60 along the direction A1 centered on the optical axis 9. The light forming the first image 40 (also referred to as the first image 40 for simplicity) is provided to the optical arrangement 60 centered on the optical axis 9. The light is then coupled by the optical arrangement 60 from the display 20 towards the exit pupil 80. In this case, Figures 4 to 16 Unlike the configuration of , the display 20 does not supply light at a reduced cone angle. Therefore, the first image 40 is coupled toward both the first region 82 and the second region 84. The light blocker 70 is disposed at the second region 84, which absorbs half of the light originally supplied by the display 20.

[0171] The first image 40 may reflect from the waveguide or any other reflective component disposed after the exit pupil 80, thereby producing a partial reflection that, if coupled into the waveguide, will form the second image 50. For simplicity, the partial reflection may be referred to as the second image 50.

[0172] Fig.19 The resulting return path of the second image 50 is shown, which starts from the first area 82 and propagates in the direction A2, reflects at the display 20, and ends at the light blocker 70. Since the light blocker 70 covers the second area 84, only light from the first area 82 (which is located on one side of the exit pupil 80) is coupled back into the light projector 10. This causes the second image 50 to have a reduced cone angle relative to the supply light from the display 20, and causes the second image 50 to illuminate the optical arrangement 60 asymmetrically. The first area 82 is positioned to one side of the optical axis 9, so that the optical arrangement 60 focuses the second image 50 towards the display 20 at a non-zero angle relative to the optical axis 9.

[0173] The partial reflection 50 is then reflected again at the display 20 and propagates back in the direction indicated by the arrow A1 toward the exit pupil 80. The non-zero travel angle of the second image 50 relative to the optical axis 9 causes the optical arrangement 60 to couple the second image 50 toward a second region 84 of the exit pupil 80 where it encounters the light blocker 70 and is absorbed. In this way, ghost images can be prevented without utilizing a display configured to provide an image with a reduced angular size.

[0174] As previously mentioned, in this embodiment, light blocker 70 absorbs half of the light initially supplied by display 20. This allows Fig.18 and Fig.19 This configuration is less efficient than the previously described embodiment because half of the supplied light is effectively wasted. However, this configuration can be easily implemented in existing projector designs by providing a light blocker on the half of the exit pupil that is on one side of the optical axis 9. Fig.18 and Fig.19 This method can be implemented using any kind of display.

[0175] Fig. 20 A schematic diagram of a portion of an emissive display 22 that may be used in embodiments of the present invention is shown. Specifically, Fig. 20 It is shown how an emissive display can be used to generate light with a reduced cone angle to enable emission of an image provided off-center relative to the optical axis.

[0176] The emissive display 22 includes a substrate 23 on which a plurality of pixels are disposed, including an exemplary first pixel 24a and an exemplary second pixel 24b. Each pixel includes one or more LEDs 25 configured to generate light 26 of one or more colors. The pixels can be individually turned on or off to generate an image, which can be provided to an optical arrangement for coupling to an exit pupil. In practice, a larger array of pixels can be provided on the emissive display 22. The pitch of the pixels can also be larger than Fig. 20 More densely depicted in .

[0177] Each pixel includes a collimator 27 that is asymmetric so that the emitted light 26 is preferentially coupled toward one side of the optical axis 9 that perpendicularly bisects the geometric center of the emissive display 22. The first pixel 24a and the second pixel 24b are provided with a collimator 27 that expands only on the right side thereof. The non-expanded side of the collimator 27 prevents the emitted light from propagating toward the non-expanded left side, thereby reducing the cone angle of the emitted light in that direction. In this way, the emitted light 26 from the emissive display 22 can have a reduced cone angle so that an image can be provided off-center relative to the optical axis 9. As previously described, this enables the image to be coupled toward one of the two opposing regions of the exit pupil that are offset from the optical axis 9.

[0178] In the light projector of the present invention, such as Figures 4 to 17 Those light projectors described have each pixel on the emissive display 22 having a collimator 27 that reduces the cone angle in the same direction, regardless of the position of the pixel on the emissive display 22. This enables the entire extent of the emissive display 22 to be used to provide a single image that is coupled toward one area of ​​the exit pupil.

[0179] In embodiments of the invention comprising multiple imaging channels, i.e., Figures 9 to 15 In the described embodiments of light projector 100 or light projector 200, separate emissive displays may be used to implement the present invention. For example, a first emissive display may be provided with a collimator 27 oriented to block light propagating toward a first side of the optical axis 9, and a second emissive display may be provided with a collimator 27 oriented oppositely to block light propagating toward a second side of the optical axis 9 opposite the first side. This enables each emissive display to provide an off-center image in opposite directions, which off-center images may be coupled into different regions of the exit pupil.

[0180] The partial reflections produced by the (desired) image entering the waveguide may reach the emissive display 22 in the same manner as previously described. For the emissive display 22, these partial reflections may be re-reflected or scattered from the surface of the LED 25 or substrate 23. The non-zero angle of incidence of the partial reflections means that the partial reflections may be at least partially reflected or scattered back to the exit pupil at a non-zero angle relative to the optical axis 9. The re-reflected or scattered light may have an intensity distribution that peaks at a relative region of the exit pupil where the partial reflection occurs. The re-reflected or scattered light may be absorbed by a light blocker at the relative region. Thus, even when an emissive display 22 is used, ghosting may be prevented, or at least its intensity may be greatly reduced.

[0181] Fig. 20One way to reduce the cone angle of the emitted image from the emissive display is shown. It is contemplated that other ways of achieving the same effect using the emissive display 22 are possible. In another example, the collimator 27 can be replaced with a microlens located above each LED 25 that shapes the emitted light 26 into a narrower cone angle on one side. This can provide multiple cones of light, each with a chief ray that is not parallel to the optical axis of the system.

[0182] Various embodiments of the light projector 100 and the light projector 200 have been described above by using a single reflective display that uses two light sources to independently generate two sets of images. However, it should also be understood that the light source and reflective display of the light projectors 100 and 200 can be implemented using multiple emissive displays. For example, an embodiment of the emissive display 22 can replace the reflective display and the light source to provide two or more sets of images to the user while effectively preventing ghost images.

[0183] The embodiments of light projectors 100 and 200 discussed above have two opposing "image channels" (e.g., two light sources and a reflective display or two separate emissive displays) configured to independently generate images. Each image channel is positioned symmetrically about optical axis 9 relative to the other image channel so that a ghost image from one channel is aligned with an input region on the exit pupil used by the other channel, and vice versa. As described above, this alignment enables the use of switchable light blockers at each input region to selectively block ghost images from both channels.

[0184] In other embodiments, one or more additional image channels may be added at spaced locations around the optical axis 9 in the light projector 100 or the light projector 200. For example, if a first emissive display and a second emissive display are provided as relative imaging channels using the upper region and the lower region of the exit pupil, respectively, a third emissive display and a fourth emissive display may be provided that couple images toward the left region and the right region of the exit pupil, respectively. In this case, each region of the exit pupil may not overlap with other regions, and each region may be positioned off-center relative to the optical axis 9 in a direction equal to and opposite to its relative region. A corresponding light blocker may be positioned on each of the upper region, the left region, the right region, and the lower region of the exit pupil.

[0185] Likewise, reflective or transmissive displays and multiple light sources may be used to provide multiple imaging channels.

[0186] It is contemplated that in some embodiments, the light projectors 100, 200 may be provided with three or more pairs of opposing imaging channels.

[0187] In embodiments where multiple image channels are used, each image channel may be used sequentially to provide a different image or the same image to the user. The image channel in use may change each frame. In one example, two channels from different channel pairs may be activated simultaneously, with each respective channel pair in an anti-ghosting mode to prevent ghost images from either activated channel from entering the waveguide. Alternatively, multiple imaging channels may be activated simultaneously in a bright mode to increase the brightness perceived by the user in bright ambient lighting conditions.

[0188] Two or more imaging channels can be activated simultaneously to achieve various effects. Any aspect of the light that forms the image can be varied between imaging channels. For example, the hue, intensity, saturation, color, resolution, field of view, frame rate, gamma, or any other feature of the display that can be adjusted can be adjusted. Two or more imaging channels can also be used to provide a stereoscopic image to a user.

Claims

1. A projector for an augmented reality or mixed reality head mounted device, comprising: a display defining an optical axis configured to provide a first supplied light; an exit pupil configured to couple the first supply light into a waveguide for an augmented reality or mixed reality head mounted device, the exit pupil comprising a first region and a second region; a first optical arrangement configured to couple a first supply light from the display towards the exit pupil; as well as a first light blocker; wherein the first region is positioned off-center relative to the optical axis in a first direction so that a first partial reflection formed by partial reflection of the first supply light at the exit pupil can be reflected toward the display and reflected by the display back to a second region of the exit pupil, and the second region is off-center relative to the optical axis in a second direction so that the first region and the second region are at least partially spatially separated from each other; The first light blocker is positioned at the second region to at least partially prevent the first partial reflection from being coupled into the waveguide while enabling the first supply light to be coupled into the waveguide through the first region.

2. The projector according to claim 1, wherein: The display is configured to provide the first supply light to the first optical arrangement off-center with respect to the optical axis such that the first supply light is coupled towards a first region of the exit pupil.

3. The light projector according to claim 2, further comprising: a first light source configured to illuminate the display to produce the first supplied light; as well as a second optical arrangement configured to couple light from the first light source to the display; wherein the display is a reflective display, and the first light source and / or the second optical arrangement are configured to provide asymmetric illumination to the display relative to the optical axis so that the display can provide the first supply light to the first optical arrangement off-center relative to the optical axis.

4. A projector according to any one of the preceding claims, wherein: The first light blocker is switchable between a first state configured to at least partially prevent the first partial reflection from being coupled into the waveguide and a second state configured to enable light to be coupled into the waveguide.

5. The projector of claim 4 when dependent on claim 3, comprising a second light source configured to illuminate the display so that the display can produce a second supply light, wherein The second light source and / or the second optical arrangement is configured to provide asymmetric illumination to the display relative to the optical axis so that the display can provide the second supply light to the first optical arrangement at a position off-center relative to the optical axis, so that the second supply light is coupled towards a second region of the exit pupil.

6. The projector according to claim 5, wherein: The second region is positioned off-center relative to the optical axis so that a second partial reflection formed by partial reflection of the second supply light at the exit pupil can be reflected toward the display and by the display back to the first region of the exit pupil.

7. The projector according to claim 5 or 6, comprising a second light blocker positioned at the first area, wherein The second light blocker is switchable between a third state configured to at least partially prevent the second supply light from being coupled into the waveguide and a fourth state configured to enable light to be coupled into the waveguide.

8. The projector according to claim 7, wherein: The first light source and the second light source are configured to operate simultaneously when the first light blocker is in the second state and the second light blocker is in the fourth state.

9. The projector according to claim 7 or 8, wherein: the light projector being configured to switch between a first configuration and a second configuration in which the first light source is on, the second light source is off, the first light blocker is in the first state, and the second light blocker is in the fourth state; In the second configuration, the first light source is off, the second light source is on, the first light blocker is in the second state, and the second light blocker is in the third state.

10. The projector according to any one of claims 3 to 9, wherein: The second optical arrangement comprises an array of microlenses.

11. The projector according to claim 10, wherein: The first light source is configured to illuminate the microlens array, preferably on one side of the microlens array.

12. A projector according to any one of the preceding claims, wherein: The first light blocker includes a polarizer configured to block light at a first polarization angle and a switchable wave plate configured to selectively shift light coupled toward the polarizer from a second polarization angle, the second polarization angle being perpendicular to the first polarization angle.

13. A projector according to any one of the preceding claims, wherein: The first region and the second region are spatially separated along a longitudinal axis, and wherein the longitudinal axis is oriented to minimize a distance between the display and the exit pupil.

14. A projector according to any preceding claim, comprising a waveguide for an augmented reality or mixed reality head mounted device configured to receive supply light from the exit pupil and couple the supply light towards a user.

15. A projector for an augmented reality or mixed reality head mounted device, comprising: a display defining an optical axis configured to produce a first supplied light and a second supplied light; an exit pupil configured to couple the first supply light and the second supply light into one or more waveguides for an augmented reality or mixed reality head mounted device, the exit pupil comprising a first region and a second region; as well as a first optical arrangement configured to couple first and second supplied light from the display toward the exit pupil; wherein the display is configured to provide the first supply light and the second supply light, respectively, to the first optical arrangement off-center relative to the optical axis such that the first supply light is coupled towards a first region of the exit pupil and the second supply light is coupled towards a second region of the exit pupil; Wherein, the first region is positioned off-center relative to the optical axis in a first direction, and the second region is positioned off-center relative to the optical axis in a second direction, such that the first region and the second region are at least partially spatially separated from each other.

Images