WO2013135943A1

WO2013135943A1 - Image providing apparatus and method

Info

Publication number: WO2013135943A1
Application number: PCT/FI2012/050248
Authority: WO
Inventors: Toni JÄRVENPÄÄ; Markus Virta
Original assignee: Nokia Corporation
Priority date: 2012-03-16
Filing date: 2012-03-16
Publication date: 2013-09-19

Abstract

An apparatus and method wherein the apparatus comprises: at least one light guide element (3) configured to guide light (5) from an image source (7) wherein the at least one light guide element (3) is configured to be positioned proximate to an eye (9) of a user to enable a user to view an image from the image source (7); and a mechanism (1 1 ) configured to move the at least one light guide element (3).

Description

TITLE

Image Providing Apparatus and Method TECHNOLOGICAL FIELD

Embodiments of the present invention relate to an image providing apparatus and method. In particular, they relate to an image providing apparatus and method which may be used in an apparatus such as a near eye display.

BACKGROUND

Near eye displays are apparatus which enable an image to be provided proximate to the eye of the user. An apparatus such as a near eye display may be used in applications such as virtual reality or augmented reality applications. Apparatus such as near eye displays may be transparent so as to enable overlaid viewing of virtual content and the real world. Apparatus such as near eye displays may be configured to have a focus set to infinity so that images and objects which are a long way from the user appear sharp and correctly converged so that the user does not view blurred objects or experience double vision.

However, if either real or virtual objects are closer to the user of a near eye display so that they do not have a focus set to infinity, it may be more difficult for the user to simultaneously view these images correctly. For example, if a user is viewing a real world object which is close to them their eyes will automatically adjust the lens of the eye and move so that the visual axis of the eye are incident on the object close to them. Other objects may then appear out of focus, due to the accommodation of the eye, or double due to the visual axis of the two eyes not converging on the other object.

It is beneficial for near eye displays to be able to take into account the accommodation of the eye of the user and the possible changes in the convergence point of the two visual axis to provide high quality images to the user.

BRIEF SUMMARY According to various, but not necessarily all, embodiments there is provided an apparatus comprising: at least one light guide element configured to guide light from an image source wherein the at least one light guide element is configured to be positioned proximate to an eye of a user to enable a user to view an image from the image source; and a mechanism configured to move the at least one light guide element. In some embodiments the mechanism configured to move the at least one light guide element may be configured to control the position of the at least one light guide element relative to an eye of a user. In some embodiments the mechanism configured to move the at least one light guide element may be configured to control alignment between an optical axis of the at least one light guide element and a visual axis of the eye of the user.

In some embodiments the mechanism configured to move the at least one light guide element may comprise a sliding component. The sliding component may be configured to rotate the at least one light guide element about an axis of rotation. The axis of rotation may be proximate to the eye of a user. The axis of rotation may pass through the eye of the user.

In some embodiments the mechanism configured to move the at least one light guide element may comprise a hinge.

In some embodiments the apparatus may comprise a near eye display.

In some embodiments the apparatus may be configured to be worn on the head of a user.

In some embodiments the at least one light guide element may comprise an exit pupil expander.

In some embodiments the at least one light guide element may comprise a flat substrate. In some embodiments the at least one light guide element may comprise a curved substrate.

In some embodiments the mechanism configured to move the at least one light guide element may be configured to enable the at least one light guide element to be moved automatically. In some embodiments the mechanism configured to move the at least one light guide element may be configured to enable the at least one light guide element to be moved manually.

In some embodiments the apparatus may comprise two light guide elements where each light guide element is configured to be positioned proximate to a different eye of the user.

According to various, but not necessarily all, embodiments there is provided a method comprising: configuring at least one light guide element to guide light from an image source to a position proximate to an eye of a user to enable a user to view an image from the image source; and moving the at least one light guide element using a mechanism. In some embodiments of the method moving the at least one light guide element using a mechanism may control the position of the at least one light guide element relative to an eye of a user. In some embodiments moving the at least one light guide element using a mechanism may control alignment between an optical axis of the at least one light guide element and a visual axis of the eye of the user.

In some embodiments moving the at least one light guide element may comprise sliding the at least one light guide element along a sliding component. Sliding the at least one light guide element along a sliding component may cause rotation of the at least one light guide element about an axis of rotation. The axis of rotation may be proximate to the eye of a user. The axis of rotation may pass through the eye of the user. In some embodiments moving the at least one light guide element may comprise rotating the at least one light guide element about a hinge.

In some embodiments the at least one light guide element may comprise part of a near eye display.

In some embodiments the at least one light guide element comprises part of an apparatus which may be configured to be worn on the head of a user.

In some embodiments the at least one light guide element may comprise a flat substrate.

In some embodiments the at least one light guide element may comprise a curved substrate. In some embodiments the method may comprise moving the at least one light guide element automatically.

In some embodiments the method may comprise moving the at least one light guide element manually.

In some embodiments the method may comprise configuring a first light guide element to guide light from an image source to a position proximate to a first eye of the user and configuring a second light guide element to guide light from an image source to a position proximate to a second eye of the user. The apparatus may be for providing an image to a user. The apparatus may be for providing an image to a user in a virtual reality or augmented reality application.

BRIEF DESCRIPTION

For a better understanding of various examples of embodiments of the present disclosure reference will now be made by way of example only to the accompanying drawings in which: Fig. 1 illustrates an apparatus according to a first embodiment of the disclosure in a first configuration;

Fig. 2 illustrates the apparatus 1 of Fig. 1 in a second configuration;

Fig. 3 illustrates the apparatus of Fig. 1 in a third configuration;

Figs. 4A to 4C illustrate apparatus according to further embodiments of the disclosure; and Fig. 5 illustrates a method according to an embodiment of the invention.

DETAILED DESCRIPTION

The Figures illustrate an apparatus 1 comprising: at least one light guide element 3 configured to guide light 5 from an image source 7 wherein the at least one light guide element 5 is configured to be positioned proximate to an eye 9 of a user to enable a user to view an image from the image source 7; and a mechanism 1 1 configured to enable the at least one light guide element 3 to be moved.

Figure 1 schematically illustrates an apparatus 1 according to an examplary embodiment of the disclosure. The apparatus 1 illustrated in Fig. 1 comprises a cross section through a portion of the apparatus 1 . The cross section may be taken through a substantially horizontal plane when the apparatus 1 is in use.

The apparatus 1 may comprise a near eye display or other type of display which enables an image to be provided proximate to the eye of the user. The apparatus 1 may be configured to provide a user with images which enable the user to use virtual reality or augmented reality applications.

In some embodiments of the disclosure the apparatus 1 may be configured to be worn by the user. For example the apparatus 1 may comprise a mounting portion which enables the apparatus 1 to be mounted on the head or face of the user. When the apparatus 1 is mounted on the head or face of the user, the user's head or face may support the weight or at least a portion of the weight of the apparatus 1 . The examplary apparatus 1 illustrated in Fig. 1 comprises an image source 7, a light guide element 3 and a mechanism 1 1 for moving the light guide element 3. In the examplary apparatus 1 of Fig. 1 two image sources 7, two light guide elements and two mechanisms 17 are provided so that each eye 3 of the user is positioned proximate to a different image source 7, light guide element 3 and mechanism 17. The apparatus 1 illustrated in Fig. 1 is substantially symmetrical so that the right hand side of the apparatus 1 is a mirror image of the left hand side of the apparatus 1 . It is to be appreciated that the apparatus 1 need not be perfectly symmetrical and that in some embodiments of the disclosure there may be some differences between the two sides.

The image sources 7 may comprise any means which provides a light beam 5 to the light guide element 3. In some embodiments of the disclosure the image sources 7 may be configured to obtain the light beam 5 from a virtual image generating means such as a processor or other suitable means and provide this to the light guide element 3. The image sources 7 may be positioned within the apparatus 1 so that they are adjacent to the light guide elements 3. The image sources 7 may be coupled to the light guide elements 3 so that a part of the image source 7 touches the light guide element 3.

The light guide elements 3 may comprise any means which may be configured to guide the light beam 5 from the image source 7 to a position proximate to the eye 9 of the user of the apparatus 1 to enable the user of the apparatus 1 to view an image provided by the image source 7.

The light guide element 3 may be positioned within the apparatus 1 so that when the user is using the apparatus 1 , for example, when the user is wearing the apparatus 1 , the light guide element 3 is positioned within a few centimetres of the eye 9 of the user. This enables the light beam 5 to be guided to a position proximate to the eye 9 of the user.

In the embodiments of the disclosure illustrated in Fig. 1 the light guide elements 3 comprise a single substrate 13. It is to be appreciated that in other embodiments other the light guide means may comprise a plurality of substrates 13 or any other suitable means for guiding the light beam 5.

In the examplary embodiment of Fig. 1 the substrate 13 is flat. In other embodiments of the disclosure the light guide element 3 the substrate 13 may be a different shape, for example, the substrate 13 may be curved. The shape of the light guide element 3 may be configured to control the focal point or convergence point of images provided by the image source 7. The substrate 13 may be made of any suitable material which enables the beam of light 5 to be transmitted through the substrate 13. For example, the substrate 13 may be made of glass or plastic. In the examplary embodiment illustrated in Fig. 1 the light guide elements 3 comprise an exit pupil expander 15. It is to be appreciated that other types of light guide elements could be used in other embodiments of the disclosure.

In the exit pupil expander 15 illustrated in Fig. 1 the substrate 13 is transparent and comprises a first surface 17 and a second surface 19. As the substrate 13 is flat both the first surface 17 and a second surface 19 are also flat and parallel to each other. As mentioned above the substrate 13 may have a different shape in other embodiments of the disclosure.

A first diffraction grating 21 is provided in the second surface 19 of the substrate 13. The first diffraction grating 21 may comprise any suitable periodic structure. The first diffraction grating 21 may be an in-coupling grating which couples the incident beam of light 5 into the substrate 13.

The first diffraction grating 21 may be provided on the surface of the exit pupil expander 15 at the point where the image source 7 is coupled to the light guide element 3. This may cause the beam of light 5 to pass through the first diffraction grating 21 as it enters the light guide element 3.

A second diffraction grating 23 is also provided. In the examplary embodiment illustrated in Fig. 1 the second diffraction grating 23 is also provided in the second surface 19 of the substrate 13 so that the first diffraction grating 21 and the second diffraction grating 23 are provided on the same surface of the substrate 13. This may provide the benefit that it may be easier to accurately manufacture an exit pupil expander 15 having both of the diffraction gratings 21 , 23 on the same surface 19 of the substrate 13. However, it is to be appreciated that in other embodiments of the disclosure the diffraction gratings 21 , 23 may be provided on different surfaces 17, 19 of the substrate 13.

The first diffraction grating 21 and the second diffraction grating 23 may have different sizes. In the examplary embodiment of Fig. 1 the second diffraction grating 23 is larger than the first diffraction grating 21 such that it covers a larger area of the surface 19 of the substrate 19. This may cause expansion of the exit pupil of the beam of light 5. The sizes and period of the diffraction gratings 21 , 23 may be selected to enable a focused image to be provided to the user of the apparatus 1 . The thickness of the substrate 13 which is used may be dependent upon the width of the diffraction gratings 21 , 23 which are used and the proximity of the light guide element 3 to the eye 9 of the user. In the examplary embodiment in Fig. 1 a beam of light 5 is incident on the first diffraction grating 21 . The first diffraction grating 21 couples the incident beam of light 5 into the substrate 13. In the embodiment illustrated in Fig. 1 in-coupled beam of light 25 propagates through the substrate 13. The exit pupil expander 5 is configured to enable total internal reflection of the in- coupled beam of light 25. This means that the in-coupled beam of light 25 remains inside the substrate 13 until it is incident upon the second diffraction grating 23.

The second diffraction grating 23 may be configured to diffract the in-coupled beam of light 25 out of the substrate 13 to provide an out-coupled beam of light 27. As the light guide element 3 of Fig. 1 comprises an exit pupil expander the out-coupled beam of light 27 may have a larger exit pupil than the beam of light 5 which is provided by the image source 7.

The path which is followed by the out-coupled beam of light 27 defines the optical axis 29 of the light guide element 3. In the embodiment illustrated in Fig. 1 the optical axis 29 of the light guide element 3 is at an angle which is not perpendicular to the flat surface 19 of the substrate 13. It is to be appreciated that in other embodiments of the disclosure the optical axis 29 of the light guide element 3 may be provided at an angle different to that illustrated in Fig.1 . The angle of the optical axis 29 relative to surface 19 of the substrate 13 may be dependent upon factors such as the period, size or position of the second diffraction grating 23. The mechanism 1 1 for moving the light guide element 3 may comprise any means which enables the light guide element 3 to be moved. The mechanism 1 1 may enable the light guide element 3 to be moved relative to the other portions of the apparatus 1 such as the means for coupling the apparatus 1 to the head of the user. In some embodiments of the disclosure the mechanism 1 1 may be configured to move other portions of the apparatus 1 in addition to the light guide element 3. For example the mechanism 1 1 may be configured to move both the light guide element 3 and the image source 7.

In the particular embodiment illustrated in Fig. 1 the mechanism 1 1 comprises a sliding component 31 . The sliding component 31 may comprise, for example, a slide rail. The at least one light guide element 3 is coupled to the sliding component 31 to enable the light guide element 3 to slide between two points.

In the particular embodiment in Fig. 1 the sliding component 31 may be horizontal with respect to the rest of the apparatus 1 so that when the light guide element 3 moves between the two points the horizontal position of the light guide element 3 does not change. It is to be appreciated that in other embodiments of the disclosure the mechanism 1 1 may enable the light guide element 3 to move so that its horizontal position relative to the rest of the apparatus 1 does change. In the particular embodiment illustrated in Fig. 1 the sliding component 31 is curved so that when the light guide element 3 is moved it follows a curved path as indicated by the arrows 33. The sliding component 31 enables the light guide element 3 to rotate about an axis of rotation 35 perpendicular to the horizontal plane of the sliding component. In the embodiment illustrated in Fig. 1 the axis of rotation 35 is indicated by the mark X as it extends into the page. In the particular embodiment of Fig. 1 the apparatus 1 and mechanism 1 1 are configured so that the axis of rotation 35 passes through the eye 9 of the user. In the examplary embodiment of Fig. 1 the axis of rotation 35 passes though the centre of the eye 9 of the user. It is to be appreciated that in other embodiments of the disclosure the axis of rotation 35 may have a different location. For example the axis of rotation may be proximate to the eye 9 of the user or pass through a different part of the head of the user.

In the examplary embodiment of Fig. 1 the light guide element 3 is coupled to the sliding component 31 at two points. In Fig. 1 the two ends of the substrate 13 are coupled to the sliding component 31. As the sliding component 31 is curved and the substrate 13 is flat the sections of the substrate 13 between the two end points are not touching the sliding component 31 . It is to be appreciated that in other embodiments of the disclosure different ways and arrangements for coupling the light guide element 3 to the sliding component 31 could be used.

In the configuration illustrated in Fig. 1 the user is focusing on an object 37 which is located at infinity. The eye 9 of the user is focused straight ahead. The visual axis 39 of the eye 9 is a straight line which extends from the fovea at the back of the user's eye 9 through the center of the cornea 41 . The user can focus on objects and images which coincide with the visual axis 39 of the eye 9. In Fig. 1 as the user is focusing on an object 37 which is located at infinity the visual axis 39 extends straight ahead of the user. The configuration illustrated in Fig.1 may be a default configuration such that the apparatus 1 may be automatically set in the configuration of Fig.1 unless the mechanism 1 1 is used to move the light guide element 3.

The apparatus 1 is configured so that when the user is focusing on an object 37 which is located at infinity the optical axis 29 of the light guide element and the visual axis 39 of the eye 9 coincide. This enables an image provided by the image source 7 to be viewed correctly by the user of the apparatus 1 . The image appears in focus and correctly converged as a single image so that there is no double vision experienced by the user.

As both the objects 37 and the images provided by the image source 7 may be correctly focused and converged by the user this enables the user to comfortable view both virtual and real objects. This may be useful, for example, in augmented reality applications or if the display is a transparent display which enables a user to view both images provided by the image source 7 and their real world surroundings. Fig. 2 schematically illustrates the apparatus 1 of Fig. 1 in a second configuration. As the same apparatus 1 is illustrated in both Fig.1 and Fig. 2 the same reference numerals are used in Fig. 2 as in Fig. 1 .

In the configuration illustrated in Fig. 2 the user is focusing on an object 37 which is not located at infinity. The object 37 is closer to the user and positioned at an angular location such that the user has to move the eye 9 inwards so that the visual axis 39 of the eye 9 coincides with the object 37.

As the visual axis 39 of the eye has moved between Fig. 1 and Fig. 2 the mechanism 1 1 is used to move the light guide element 3. If there was no movement of the light guide element 3 between Fig. 1 and Fig. 2 then the optical axis 29 of the light guide element 3 would not be aligned or coincide with the visual axis 39 of the eye 9 of the user. This would cause the images provided by the image source to appear blurred and incorrectly converged so that the user may see double images.

However, in the configuration of the apparatus 1 illustrated in Fig. 2 the mechanisms 1 1 have been used to move the light guide elements 3. In Fig. 2 the light guide element 3 has been moved along the sliding mechanism 31 so that the light guide element 3 has been rotated about the axis of rotation 35. The angle through which the light guide element 3 is rotated may vary in different embodiments of the disclosure. In the configuration illustrated in Fig. 2 the light guide element 3 has been rotated through approximately 5 degrees from the position as illustrated in Fig. 1 . This has changed the angular position of the light guide element 3 relative to the eye 9 of the user. The movement of the light guide element 3 using the mechanism 5 enables control of the position of the at least one light guide element 3 relative to an eye 9 of a user. The movement of the light guide element 3 using the mechanism 5 enables the alignment of the visual axis 39 and the optical axis 29 of the light guide element 3 to be controlled. In some embodiments of the disclosure, as is illustrated in Fig. 2 the movement of the light guide element 3 may enable the visual axis 39 and the optical axis 29 to be aligned when the user moves their eye.

In Fig. 2 the light guide element 3 is moved so that the optical axis 29 of the light guide element and the visual axis 39 of the eye 9 coincide. This enables an image provided by the image source 7 to be viewed correctly by the user of the apparatus 1 even when the user is viewing an object 37 which is not located at infinity. The image appears in focus and correctly converged as a single image so that there is no double vision experienced by the user. As both the objects 37 and the images provided by the image source 7 may be correctly focused and converged by the user this enables the user to comfortably view both virtual images and real objects even if the object is not located at infinity.

Fig. 3 schematically illustrates the apparatus 1 of Figs. 1 and 2 in a third configuration. As the same apparatus 1 is illustrated in Figs .1 and 2 the same reference numerals are used in Fig. 3 as in Figs. 1 and 2. In the configuration illustrated in Fig. 3 the user is focusing on an object 37 which is not located at infinity and which is located at the convergence point 51 of the two eyes 9 of the user. This is the point where the two visual axis 39 of the eyes 9 coincide. The user has moved their eyes 9 further inwards so that the visual axis 39 of the eye 9 coincides with the object 37. As the visual axis 39 of the eye has moved between Figs. 1 and 2 and Fig. 3 the mechanism 1 1 is used to move the light guide element 3 further. If there was no movement of the light guide element 3 between Fig. 2 and Fig. 3 then the optical axis 29 of the light guide element 3 would not be aligned or coincide with the visual axis 39 of the eye 9 of the user. This would cause the images provided by the image source to appear blurred. As the object 37 is located at the convergence point a misalignment between the optical axis 29 of the light guide element 3 and the visual axis 39 of the eye 9 might cause the user to see double images.

However, in the configuration of the apparatus 1 illustrated in Fig. 3 the mechanisms 1 1 have been used to move the light guide elements 3 similar to the movement described above in relation to Fig. 2. The light guide element 3 has been moved along the sliding mechanism 31 so that the light guide element 3 has been rotated about the axis of rotation 35. In the configuration illustrated in Fig. 3 the light guide element 3 has been rotated through approximately 5 degrees from the position as illustrated in Fig. 2 and about ten degrees from the position as illustrated in Fig. 1 . This has changed the angular position of the light guide element 3 relative to the eye 9 of the user.

In Fig. 3, as in Fig. 2, the light guide element 3 is moved so that the optical axis 29 of the light guide element and the visual axis 39 of the eye 9 coincide. This enables an image provided by the image source 7 to be viewed correctly by the user of the apparatus 1 even when the user is viewing an object 37 which is located at the convergence point 51. The image appears in focus and correctly converged as a single image so that there is no double vision experienced by the user. As both the objects 37 and the images provided by the image source 7 may be correctly focused and converged by the user this enables the user to comfortably view both virtual images and real objects even if the object is located at the convergence point 51 . In the embodiments illustrated in Figs. 1 to 3 the axis of rotation 35 of the light guide element 3 passes though the centre of the eye 9. This enables the optical axis 29 of the light guide element 3 to stay in alignment with the visual axis 39 of the eye 9 of the user. In other embodiments of the disclosure the axis of rotation 35 may have a different location.

In the embodiments illustrated in Figs. 1 to 3 both of the light guide elements 3 are moved by the same sized angle so that the apparatus 1 illustrated in Figs. 1 to 3 is symmetrical even after the movement of the light guide elements 3. In such embodiments of the disclosure the mechanisms 1 1 of the two light guide elements 3 may be coupled to each other so that they are always adjusted by corresponding amounts.

In other embodiments of the disclosure the apparatus 1 may be configured so that the light guide elements 3 may be moved independently of each other. This may enable each of the light guide elements 3 to be moved by different amounts. For example the angle moved by the right hand side light guide element 3 may have a different size to the angle moved by the left hand side light guide element 3. It is to be appreciated that in such embodiments of the disclosure the apparatus might not be perfectly symmetrical. This may enable the user to adjust the apparatus 1 for their own comfort or to allow for asymmetry of the face of the user. In the embodiments illustrated in Figs. 1 to 3 the light guide elements 3 are moved so that the optical axis 29 remains aligned with the visual axis 39. In other embodiments of the disclosure it might not be possible to maintain the alignment of the optical axis 29 and the visual axis 39 so there might be some deviation between the two axis. The mechanism 1 1 for moving the light guide element 3 may be configured to control the alignment of the two axis and reduce any deviations from alignment when the user moves their eyes.

In some embodiments of the disclosure the light guide elements 3 may be moved automatically. For example, the mechanism 1 1 may be configured to cause the movement of the light guide elements 3 without any conscious input from the user. For example, the movement of the corneas 41 of the eyes 9 may be detected and this detection may cause the mechanism 1 1 to be used to move the light guide element 3.

In other embodiments of the disclosure the light guide elements may be moved manually. For example the apparatus 1 may be configured to enable a user to make a conscious input so that in response to detecting the input the mechanism 1 1 is used to move the light guide element 3. This may enable the user to adjust the positions of the light guide elements 5 to improve their own vision or make the apparatus 1 more comfortable for them to use. Figs. 4A to 4C illustrate a similar apparatus 1 according to other embodiments of the disclosure. Where features of the apparatus 1 of Figs. 4A to 4C correspond to features of Figs. 1 to 3 the same reference numerals have been used. As in Figs. 1 to 3 the apparatus 1 of Figs. 4A to 4C may comprise a near eye display or other type of display which enables an image to be provided proximate to the eye of the user. The apparatus 1 illustrated in Figs. 4A to 4C also comprises an image source 7, a light guide element 3 and a mechanism 1 1 for moving the light guide element 3 for each eye 9 of a user. The apparatus 1 illustrated in Figs. 4A to 4C is also substantially symmetrical so that the right hand side of the apparatus 1 is a mirror image of the left hand side of the apparatus 1. As in Figs. 1 to 3 the light guide elements 3 in Figs. 4A to 4C may comprise exit pupil expanders 15 as described above. It is to be appreciated that in other embodiments of the disclosure other types of light guide elements 3 may be used instead. The embodiments of Figs. 4A to 4C differ from the embodiments of Figs. 1 to 3 in that the in the embodiments of Figs. 4A to 4C the mechanism 1 1 for moving the light guide elements 3 comprises a hinge 61. The hinge 61 may couple the light guide element 3 to the rest of the apparatus 1 . The hinge 61 may be configured to enable the light guide element 3 to pivot about the axis of rotation 65 of the hinge 61 as indicated by the arrows 63. In the embodiments illustrated in Figs. 4A to 4C the axis of rotation 65 is indicated by the mark X as it extends perpendicular to the plane of the schematic cross section of the apparatus 1 and so extends into the page. In each of the embodiments illustrated in Figs. 4A to 4C the hinge 61 is provided at a different location. As the hinge 61 is provided at a different location, each of the embodiments illustrated in Figs. 4A to 4C also have a different location for the axis of rotation 65 for movement of the light guide element 3. In Fig. 4A the hinge 61 is provided at the end of the light guide element furthest away from the image source 7 and closest to the nose of the user. In Fig 4B the hinge 61 is provided on the end of the light guide element closest to the image source 7 and furthest away from the nose of the user. In Fig. 4C the hinge 6 is provided on the image source 7. It is to be appreciated that in other embodiments of the disclosure the hinge 61 and axis of rotation 65 may be provided at different points within the apparatus 1 . The apparatus of Figs. 4A to 4C enable the light guide elements to be moved so as to adjust the position of the optical axis 9 of the light guide element 3 relative to the eye of the user. In some implementations of the embodiments of the disclosure it may be more difficult to obtain alignment between the visual axis 39 and the optical axis 29 using the hinges rather than a slide components 31 as the as the axis of rotation 65 of the hinge 61 does not pass through the eye 9 of the user. This may result in misalignment if the hinge 61 is the only mechanism 1 1 used to move the light guide element 3. However the hinge 61 may provide a simple mechanism for coupling the light guide element 3 to the apparatus 1 and may be useful for making small adjustments to the position of the light guide element 3. Fig. 5 illustrates a method of using an apparatus 1 as described above in accordance with Figs. 1 to 4A-C.

The method comprises configuring 71 at least one light guide element 3 to guide light 5 from an image source 7 to a position proximate to an eye 9 of a user. This may enable a user to view an image from the image source 7. The light guide element 3 may comprise any suitable means such as an exit pupil expander 15 as described above.

The method also comprises moving 73 the at least one light guide element using a mechanism 1 1 . The moving of the at least one light guide element 3 using a mechanism 1 1 may comprise controlling alignment between an optical axis 29 of the at least one light guide element 3 and a visual axis 39 of the eye 9 of the user.

The movement of block 73 may occur automatically in response to a movement detected by the apparatus 1 , for example, the movement of the eye 9 of the user. In some embodiments the movement of block 73 may occur in response to a manual input made by the user. For example the user may be adjusting the apparatus 1 to a more comfortable setting.

Embodiments of the disclosure as described above provide an apparatus 1 which enables a near eye display to be used to view images and objects which are positioned close to the user without blurring or double vision.

The blocks illustrated in the Fig. 5 may represent steps in a method and/or sections of code in the computer program. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some blocks to be omitted.

In the embodiments described above the term "coupled" means operationally coupled and any number or combination of intervening elements may exist between coupled components (including no intervening elements).

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed. For example in the embodiments of the disclosure described above the mechanism 1 1 configured for moving the light guide elements 3 comprises either a slide component 31 or a hinge 61 . It is to be appreciated that in other embodiments of the disclosure any combination of these mechanisms may be used or any suitable alternative mechanisms. Also, in the above described embodiments, the light guide elements 3 and mechanisms 1 1 for moving the light guide elements 3 enable rotational movement of the light guide elements 3. It is to be appreciated that in other embodiments of the disclosure other types of movement could be used instead or in addition to the rotational movement. For example in some embodiments of the disclosure the light guide elements 3 and mechanisms 1 1 for moving the light guide elements 3 may enable translational movement of the light guide element.

Features described in the preceding description may be used in combinations other than the combinations explicitly described. Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

I/we claim:

Claims

I . An apparatus comprising:

at least one light guide element configured to guide light from an image source wherein the at least one light guide element is configured to be positioned proximate to an eye of a user to enable a user to view an image from the image source; and

a mechanism configured to move the at least one light guide element.

2. An apparatus as claimed in claim 1 wherein the mechanism configured to move the at least one light guide element is configured to control the position of the at least one light guide element relative to an eye of a user.

3. An apparatus as claimed in any preceding claim wherein the mechanism configured to move the at least one light guide element is configured to control alignment between an optical axis of the at least one light guide element and a visual axis of the eye of the user.

4. An apparatus as claimed in any preceding claim wherein the mechanism configured to move the at least one light guide element comprises a sliding component.

5. An apparatus as claimed in claim 4 wherein the sliding component is configured to rotate the at least one light guide element about an axis of rotation.

6. An apparatus as claimed in claim 5 wherein the axis of rotation is proximate to the eye of a user.

7. An apparatus as claimed in any of claims 5 to 6 wherein the axis of rotation passes through the eye of the user.

8. An apparatus as claimed in any preceding claim wherein the mechanism configured to move the at least one light guide element comprises a hinge.

9. An apparatus as claimed in any preceding claim wherein the apparatus comprises a near eye display.

10. An apparatus as claimed in any preceding claim wherein the apparatus is configured to be worn on the head of a user.

I I . An apparatus as claimed in any preceding claim wherein the at least one light guide element comprises an exit pupil expander.

12. An apparatus as claimed in any preceding claim wherein the at least one light guide element comprises a flat substrate.

13. An apparatus as claimed in any of claims 1 to 1 1 wherein the at least one light guide element comprises a curved substrate.

14. An apparatus as claimed in any preceding claim wherein the mechanism configured to move the at least one light guide element is configured to enable the at least one light guide element to be moved automatically.

15. An apparatus as claimed in any preceding claim wherein the mechanism configured to move the at least one light guide element is configured to enable the at least one light guide element to be moved manually.

16. An apparatus as claimed in any preceding claim wherein the apparatus comprises two light guide elements where each light guide element is configured to be positioned proximate to a different eye of the user.

17. A method comprising:

configuring at least one light guide element to guide light from an image source to a position proximate to an eye of a user to enable a user to view an image from the image source; and

moving the at least one light guide element using a mechanism.

18. A method as claimed in claim 14 wherein moving the at least one light guide element using a mechanism controls the position of the at least one light guide element relative to an eye of a user.

19. A method as claimed in any of claims 17 to 18 wherein moving the at least one light guide element using a mechanism controls alignment between an optical axis of the at least one light guide element and a visual axis of the eye of the user.

20. A method as claimed in any of claims 17 to 19 wherein moving the at least one light guide element comprises sliding the at least one light guide element along a sliding component.

21 . A method as claimed in claim 20 wherein sliding the at least one light guide element along a sliding component causes rotation of the at least one light guide element about an axis of rotation.

22. A method as claimed in claim 21 wherein the axis of rotation is proximate to the eye of a user.

23. A method as claimed in any of claims 21 to 22 wherein the axis of rotation passes through the eye of the user.

24. A method as claimed in any of claims 17 to 23 wherein moving the at least one light guide element comprises rotating the at least one light guide element about a hinge.

25. A method as claimed in any of claims 17 to 24 wherein the at least one light guide element comprises part of a near eye display.

26. A method as claimed in any of claims 17 to 21 wherein the at least one light guide element comprises part of an apparatus which is configured to be worn on the head of a user.

27. A method as claimed in any of claims 17 to 26 wherein the at least one light guide element comprises an exit pupil expander.

28. A method as claimed in any of claims 17 to 27 wherein the at least one light guide element comprises a flat substrate.

29. A method as claimed in any of claims 17 to 28 wherein the at least one light guide element comprises a curved substrate.

30. A method as claimed in any of claims 17 to 29 comprising moving the at least one light guide element automatically.

31 . A method as claimed in any of claims 17 to 30 comprising moving the at least one light guide element manually.

32. A method as claimed in any of claims 17 to 31 comprising configuring a first light guide element to guide light from an image source to a position proximate to a first eye of the user and configuring a second light guide element to guide light from an image source to a position proximate to a second eye of the user.