WO2019092393A1

WO2019092393A1 - Augmented reality system

Info

Publication number: WO2019092393A1
Application number: PCT/GB2018/053020
Authority: WO
Inventors: Mohmed Salim Valera
Original assignee: Wave Optics Ltd
Priority date: 2017-11-09
Filing date: 2018-10-18
Publication date: 2019-05-16
Also published as: CN209281075U; GB2568265A; GB201718511D0; TW201932913A

Abstract

An augmented reality system (2) is disclosed for improving use in bright external 5 light conditions. The augmented reality system includes an augmented reality waveguide (4) and a filter device (8) fixed relative to the waveguide (4). The filter device (8) further comprises a first array of microlenses (12) arranged to receive light from an external environment, a second array of microlenses(14) arranged to receive light from the first array of microlenses (12) and direct light towards a 10 user, and an addressable layer (16) positioned between the two arrays of microlenses, where the addressable layer (16) can be addressed to act as a light filter.

Description

Augmented Reality System

The present invention relates to an augmented reality system, and a technique for improving use in bright light conditions such as daylight.

Head-mounted augmented reality systems can be worn on a user's head to augment a user's perception of the real world by supplying additional light. Known head-mounted systems include glasses and helmet structures. Augmented reality light may be provided to users using a waveguide structure. Diffraction gratings are positioned on or in the waveguides to couple light from a projector into a waveguide. A further diffraction grating structure can then be used to couple light out of the waveguide and towards a user. Other augmented reality technologies may be employed to generate similar results. For example, prism projector or prism-based design augmented reality systems may use multiple lenses, or prisms, to control the optical pathway of light from a display component to a user.

The optical components, such as the waveguides or prisms, in these applications are typically transparent so that the user can view light from the projector as well as light from their external environment.

However, many augmented reality systems present difficulties when they are used in bright light conditions, including daylight. These difficulties can arise because the optical components intended for controlling light from the projectors can also interact with light from the outside world.

Specifically, it has been found that in certain situations some incident light rays that are directed towards a user's eyes from an external environment may be excessively bright to the user. This high brightness may impair a user's vision of the external environment or decrease the visibility of the augmented computer-generated information. Examples of problematic light sources include the sun, or a reflection of the sun, and full beam headlights of an oncoming vehicle. An object of the invention is to improve the ability to use head-mounted augmented reality systems in diverse lighting conditions, and to reduce undesirable optical effects being experienced by a user. According to an aspect of the invention there is provided an augmented reality device comprising: an augmented reality waveguide; and a filter device fixed relative to the waveguide, the filter device comprising: a first array of microlenses arranged to receive light from an external environment; a second array of microlenses arranged to receive light from the first array of microlenses and direct light towards a user; and an addressable layer positioned between the first array of microlenses and the second array of microlenses, wherein the addressable layer can be addressed to act as a light filter.

In this way, it is possible for an augmented reality device to create a light filter. Advantageously, the filter device can reduce the brightness caused by external light in a specific area of augmented reality images that are presented to a user. For example, the filter device may be addressed to create a light filter in the area of an image where the sun is positioned, which will beneficially reduce the glare in the user's eyes.

The waveguide may be positioned between the filter device and the user. In this way, it is possible for the filter device to filter light of the external environment before the light reaches the waveguide. Advantageously, the augmented reality device can create augmented reality images that are projected to a user via the waveguide at optical settings that would not need to be further configured to compensate for any areas of high brightness. For example, the colour and brightness of a part of an augmented reality image that is viewed by a user is the same between area of high brightness (filtered by the filter device) and an area of lower brightness (not filtered by the device).

The filter device may be positioned between the waveguide and the user. In this way, it is possible for the filter device to filter light of the external environment and the waveguide. Advantageously, the filter device can be configured to manipulate the combined light (external environment and augmented reality light) that is presented to a user. The arrays of microlenses may be broken up into multiple elements that can be optimised for abberations. The augmented reality device may be a head-mounted device. In this way, it is possible for a user wearing the head-mounted augmented reality system to view projected augmented reality images and filter out any undesired areas of high brightness. Advantageously, the head mounting may help to fix or position the components relative to each other. The head mounting may also create a user's notional eye position when the head-mounted augmented reality system is worn on a user's head. Preferably there is a plurality of paths distributed in a solid angle extending from a user's notional eye position in the augmented reality device towards the filter device, wherein the addressable layer is configured to filter light along at least one of the paths.

In this way, it is possible for the addressable layer to filter light along at least one of the plurality of paths that are within a user's field of view. Advantageously, the light filter can be selectively addressed to only filter the undesired light that may be seen by the user. The user's notional eye position may correspond to a notional focal point from which the plurality of paths can extend. The actual position of a user's eye is likely to be slightly different from the notional eye position because users have different shaped heads. However, the filter device may be effective for a range of eye positions within the vicinity of the notional eye position.

The augmented reality device may be a head-up display. In this way, it is possible for the head-up augmented reality system to be used in different situations. For example, a pilot cockpit, a vehicle windscreen, or a building window (where the sun may move across the window in the day).

Preferably there is a plurality of paths distributed in at least one solid angle extending from at least one user's line of sight in the augmented reality device towards the filter device, wherein the addressable layer is configured to filter light along at least one of the paths.

In this way, it is possible for the addressable layer to filter light along at least one of the plurality of paths that are within a user's line of sight. Advantageously, the light filter can be selectively addressed to only filter the undesired light that may be seen by the user. It is considered that a user's notional line of sight would be different due to different user heights or distances from the display. The head-up display may be configured to allow adjustment of at least one user's notional line of sight due to these differences.

Preferably the augmented reality device of any of the preceding claims further comprising: a projector; an input diffractive optical element configured to receive light from the projector and to couple it into the waveguide; and an output diffractive optical element configured to couple light out of the waveguide towards a user.

Embodiments of the invention are now described, by way of example, with reference to the drawings, in which:

Figure 1 is a side view of the augmented reality device;

Figure 2 is a side view of another augmented reality device in another embodiment of the invention;

Figure 3 is a side view of another augmented reality system as a head-mounted device; and Figure 4 is a side view of another augmented reality system as a head-up display.

As shown in Figure 1 , an augmented reality device 2 has an augmented reality waveguide 4, a projector 6 and a filter device 8. The augmented reality device 2 has a frame 10 on which the waveguide 4, projector 6 and filter device 8 are fixed. The waveguide 4 is fixed to the frame 10 between a user and the filter device 8. The filter device 8 comprises a first array of microlenses 12, a second array of microlenses 14 and an addressable layer 16.

The filter device 8 may be a Gabor superlens optical system that comprises two arrays of microlenses in which there is a slight difference in pitch between each of the microlenses, relative to one another. The relative displacement of each microlens causes light to be focused like a conventional lens. The microlenses may be constructed using refractive, diffractive, or Fresnel techniques. The addressable layer 16 may be a Fourier filter located within the Gabor superlens in between the first array of microlenses 12 and the second array of microlenses 14. The Fourier filter comprises a pixelated liquid crystal absorber wherein a plurality of pixels can be addressed. Advantageously, the function of addressing the plurality of pixels will allow a user to suppress outside world light or occlude selected views by use of 'black pixels' to enhance an augmented reality image.

An input diffractive optical element 18 is positioned on the waveguide 4 to receive light from the projector 6 and to couple light into the waveguide 4. An output diffractive optical element 20 is positioned on the waveguide 4 to couple light within the waveguide 4 out of the waveguide 4 towards the user. In this way, light from the projector 6 can augment a user's view of the external environment, which they can perceive through the transparent waveguide 4. Alternative optical components other than a waveguide, for example a prism, for use in an augmented reality device would readily occur to a person skilled in the art.

Figure 2 is another embodiment of the augmented reality device 102, wherein the device 102 has an augmented reality waveguide 104, a projector 106 and a filter device 108. The augmented reality device 102 has a frame 1 10 on which the waveguide 104, projector 106 and filter device 108 are fixed. The filter device 108 is fixed to the frame 110 between a user and the waveguide 104. The filter device 108 comprises a first array of microlenses 1 12, a second array of microlenses 114 and an addressable layer 116. An input diffractive optical element 118 is positioned on the waveguide 104 to receive light from the projector 106 and to couple light into the waveguide 104. An output diffractive optical element 120 is positioned on the waveguide 104 to couple light within the waveguide 104 out of the waveguide 104 towards the user. Figure 3 is another embodiment of the augmented reality device 202, wherein a frame 210 is configured for the device 202 to be a head-mounted device. The frame 210 is arranged for a waveguide 204, a projector 206 and a filter device 208 to be fixed. In one arrangement the frame 210 is similar to a frame of a pair of spectacles. In another arrangement the frame 210 is a helmet.

The frame 210 is configured to space the waveguide 204 and the filter device 208 at positions with respect to a user's notional eye position 212. In this way, the filter device 208 can filter light along at least one of the plurality of paths with respect to the user's notional eye position 212.

In one arrangement the waveguide 204 is positioned between a user and the filter device 208. In another arrangement the filter device 208 is positioned between the user and the waveguide 204. Figure 4 is another embodiment of the augmented reality device 302, wherein a frame 310 is configured for the device 302 to be a head-up display device. The frame 310 is arranged for a waveguide 304, a projector 306 and a filter device 308 to be fixed. The frame 310 is configured to space the waveguide 304 and the filter device 308 at positions with respect to at least one user's notional line of sight 312. In this way, the filter device 308 can filter light along at least one of the plurality of paths with respect to the user's notional light of sight 312. A user's notional line of sight would change with respect to different user heights or distances from the display. The head-up display may be configured to allow adjustment of at least one user's notional line of sight due to these differences.

In one arrangement the waveguide 304 is positioned between a user and the filter device 308. In another arrangement the filter device 308 is positioned between the user and the waveguide 304.

Figure 5 shows another embodiment of the filter device 402, where a first array of microlenses 404 comprises two sets of microlenses 406 and 408. The first array of microlenses 404 is arranged to receive light from an external environment and direct the light toward an addressable layer 410 and a second array of microlenses 412.

Figure 6 shows another embodiment of the filter device 502, where a first array of microlenses 504 comprises two sets of microlenses 506 and 508, The first array of microlenses 504 is arranged to receive light from an external environment and direct the light toward an addressable layer 510 and a second array of microlenses 512. The second array of microlenses 512 comprises two sets of microlenses 514 and 516.

Alternative configurations of a filter device for use in an augmented reality system would readily occur to a person skilled in the art.

Claims

1. An augmented reality device comprising:

an augmented reality waveguide; and

a filter device fixed relative to the waveguide, the filter device comprising: a first array of microlenses arranged to receive light from an external environment;

a second array of microlenses arranged to receive light from the first array of microlenses and direct light towards a user; and

an addressable layer positioned between the first array of microlenses and the second array of microlenses, wherein the addressable layer can be addressed to act as a light filter.

2. The augmented reality device of claim 1 , where the augmented reality waveguide is positioned between the filter device and the user.

3. The augmented reality device of claim 1 , where the filter device is positioned between the augmented reality waveguide and the user.

4. The augmented reality device of claim 2 or 3, wherein the augmented reality device is a head-mounted device.

5. The augmented reality device of claim 4, wherein there is a plurality of paths distributed in a solid angle extending from a user's notional eye position in the augmented reality device towards the filter device, wherein the addressable layer is configured to filter light along at least one of the paths..

6. The augmented reality device of claim 2 or 3, wherein the augmented reality device is a head-up display.

7. The augmented reality device of claim 6, wherein there is a plurality of paths distributed in at least one solid angle extending from at least one user's line of sight in the augmented reality device towards the filter device, wherein the addressable layer is configured to filter light along at least one of the paths.

8. The augmented reality device of any of the preceding claims further comprising: a projector;

an input diffractive optical element configured to receive light from the projector and to couple it into the augmented reality waveguide; and

an output diffractive optical element configured to couple light out of the augmented reality waveguide towards a user.