FIELD

The present specification relates to displays and methods of operating thereof, and in particular to wearable head-us displays and methods of operating thereof to provide enhanced image uniformity.

BACKGROUND

Displays may be used to form still or moving images. Some displays may use a display panel to form images. Examples of such display panels include Light Emitting Diode (LED) display panels, Liquid Crystal Display (LCD) panels, and the like. In addition, some displays may use projectors to project still or moving images. Small displays may be used to form, or as a part of, mobile or wearable devices. For example, some displays may form or be part of a wearable heads-up display.

SUMMARY

According to an implementation of the present specification there is provided a method of operating a wearable heads-up display (WHUD), the WHUD comprising a light source, a spatial modulator, and a display optic, the method comprising: generating, by the light source, an output light to form an image viewable by a user of the WHUD; receiving a position of a pupil of the user relative to an eyebox of the WHUD; obtaining an image correction map based on the position of the pupil; adjusting the output light to form an adjusted output light, the adjusted output light adjusted based on the image correction map to reduce at least one of an intensity non-uniformity and a color balance non-uniformity of the image; and directing, by the display optic, the adjusted output light into a field of view of the user.

The receiving the position of the pupil may comprise tracking a gaze of a corresponding eye of the user.

The method may further comprise: obtaining a region of interest in the image corresponding to the gaze; and wherein: the adjusting the output light based on the image correction map may comprise adjusting the output light based on the image correction map to reduce at least one of the intensity non-uniformity and the color balance non-uniformity in the region of interest of the image.

The obtaining the image correction map may comprise retrieving the image correction map from a repository storing a plurality of image correction maps in association with corresponding positions of the pupil relative to the eyebox.

The obtaining the image correction map may comprise calculating the image correction map based on the position of the pupil.

The adjusting the output light may comprise controlling the light source to adjust an intensity of the output light.

The light source may comprise a red light source, a green light source, and a blue light source; and the adjusting the output light may comprise controlling at least one of the red light source, the green light source, and the blue light source to adjust an intensity of a corresponding red output light, a green output light, and a blue output light respectively.

The adjusting the output light may comprise adjusting a polarization of the output light.

The obtaining the image correction map may comprise obtaining the image correction map further based on an indication of a size of the pupil.

The indication of the size of the pupil may comprise an ambient brightness; and the obtaining the image correction map further based on the indication of the size of the pupil may comprise obtaining the image correction map further based on the ambient brightness.

The method may further comprise: operating the WHUD to display a plurality of corrected test images to the user; and receiving user input selecting a given corrected test image from the plurality of corrected test images; and wherein: the obtaining the image correction map may comprise determining the image correction map corresponding to the given corrected test image.

The WHUD may further comprise a controller in communication with the light source and the spatial modulator; the generating the output light may comprise the controller controlling the light source to generate the output light; the receiving the position of the pupil may comprise receiving the position of the pupil at the controller; the obtaining the image correction map may comprise obtaining the image correction map by the controller; and the adjusting the output light may comprise the controller controlling the light source to adjust the output light.

The output light may comprise a plurality of wavelengths; the display optic may comprise: a light guide; an incoupler carried by the light guide, the incoupler to receive the output light from the spatial modulator and direct at least a portion of the output light into the light guide, the light guide to internally reflect the portion of the output light to form a reflected light, the output light having a plurality of incoupling losses corresponding to the plurality of wavelengths of the output light; an outcoupler carried by the light guide, the outcoupler to direct at least a portion of the reflected light out of the light guide towards an eye of the user wearing the WHUD; and the adjusting the output light may comprise adjusting the output light based on the image correction map to reduce at least one of the intensity non-uniformity and the color balance non-uniformity of the image caused by the incoupling losses.

The output light may comprise a first light having a first wavelength and a second light having a second wavelength; the incoupler may be to direct at least a portion of the first light and at least a portion of the second light into the light guide, the light guide may be to internally reflect the portion of the first light and the portion of the second light to form a first reflected light and a second reflected light respectively, the first reflected light may be incident upon a reflective surface of at least one of the incoupler and the light guide at a first bounce position and the second reflected light may be incident upon the reflective surface of at least one of the incoupler and the light guide at a second bounce position, the first light may have a first incoupling loss based on the first bounce position and the second light may have a second incoupling loss based on the second bounce position; and the adjusting the output light may comprise adjusting the output light based on the image correction map to reduce at least one of the intensity non-uniformity and the color balance non-uniformity of the image caused by a difference between the first incoupling loss and the second incoupling loss.

The image may comprise a plurality of pixels, each pixel having a corresponding field position comprising spatial coordinates of the pixel in the image; for each given pixel, the incoupler may be to receive the output light at an incidence position on and an incidence angle relative to the incoupler based on the field position of the given pixel; and the adjusting the output light may comprise adjusting the output light based on the image correction map to reduce at least one of the intensity non-uniformity and the color balance non-uniformity of the image further caused by variations in the incidence position and the incidence angle from one pixel to another.

According to another implementation of the present specification there is provided a wearable heads-up display (WHUD) comprising: a light source to generate an output light; a spatial modulator to receive the output light from the light source; a display optic to receive the output light from the spatial modulator and direct the output light towards an eye of a user of the WHUD to form an image viewable by the user; and a controller in communication with the light source and the spatial modulator, the controller to: receive a position of a pupil of the user relative to an eyebox of the WHUD worn by the user; obtain an image correction map based on the position of the pupil; and adjust the output light based on the image correction map to reduce at least one of an intensity non-uniformity and a color balance non-uniformity of the image.

To receive the position of the pupil the controller may be to receive gaze position information of a gaze of the eye of the user.

The WHUD may further comprise: a gaze tracking module to track the gaze of the eye of the user, the gaze tracking module in communication with the controller; and wherein: to receive the position of the pupil the controller may be to receive the gaze position information from the gaze tracking module.

The controller may be to receive an indicator of a region of interest in the image corresponding to the gaze; and to adjust the output light based on the image correction map the controller may be to adjust the output light based on the image correction map to reduce at least one of the intensity non-uniformity and the color balance non-uniformity in the region of interest of the image.

To obtain the image correction map the controller may be to retrieve the image correction map from a repository storing a plurality of image correction maps in association with corresponding positions of the pupil relative to the eyebox.

To obtain the image correction map the controller may be to calculate the image correction map based on the position of the pupil.

To adjust the output light the controller may be to control the light source to adjust an intensity of the output light.

The light source may comprise a red light source, a green light source, and a blue light source; and to adjust the output light the controller may be to control at least one of the red light source, the green light source, and the blue light source to adjust an intensity of a corresponding red output light, a green output light, and a blue output light respectively.

To adjust the output light the controller may be to adjust a polarization of the output light.

To obtain the image correction map the controller may be to obtain the image correction map further based on an indication of a size of the pupil.

The indication of the size of the pupil may comprise an ambient brightness; and to obtain the image correction map further based on the indication of the size of the pupil the controller may be to obtain the image correction map further based on the ambient brightness.

The WHUD may further comprise: an ambient brightness sensor in communication with the controller, the ambient brightness sensor to sense the ambient brightness and to communicate the ambient brightness to the controller.

The controller may be further to: control the light source and the spatial modulator to display a plurality of corrected test images to the user; and receive user input selecting a given corrected test image from the plurality of corrected test images; and wherein: to obtain the image correction map the controller may be to determine the image correction map corresponding to the given corrected test image.

The light source may comprise a laser light source; the spatial modulator may comprise a scan mirror; and the light source and the spatial modulator may be parts of a laser projector.

The output light may comprise a plurality of wavelengths; the display optic may comprise: a light guide; an incoupler carried by the light guide, the incoupler to receive the output light from the spatial modulator and direct at least a portion of the output light into the light guide, the light guide to internally reflect the portion of the output light to form a reflected light, the output light having a plurality of incoupling losses corresponding to the plurality of wavelengths of the output light; an outcoupler carried by the light guide, the outcoupler to direct at least a portion of the reflected light out of the light guide towards an eye of the user wearing the WHUD; and to adjust the output light the controller may be to adjust the output light based on the image correction map to reduce at least one of the intensity non-uniformity and the color balance non-uniformity of the image caused by the incoupling losses.

The output light may comprise a first light having a first wavelength and a second light having a second wavelength; the incoupler may be to direct at least a portion of the first light and at least a portion of the second light into the light guide, the light guide may be to internally reflect the portion of the first light and the portion of the second light to form a first reflected light and a second reflected light respectively, the first reflected light may be incident upon a reflective surface of at least one of the incoupler and the light guide at a first bounce position and the second reflected light may be incident upon the reflective surface of at least one of the incoupler and the light guide at a second bounce position, the first light may have a first incoupling loss based on the first bounce position and the second light may have a second incoupling loss based on the second bounce position; and to adjust the output light the controller may be to adjust the output light based on the image correction map to reduce at least one of the intensity non-uniformity and the color balance non-uniformity of the image caused by a difference between the first incoupling loss and the second incoupling loss.

The image may comprise a plurality of pixels, each pixel having a corresponding field position comprising spatial coordinates of the pixel in the image; for each given pixel, the incoupler may be to receive the output light at an incidence position on and an incidence angle relative to the incoupler based on the field position of the given pixel; and to adjust the output light the controller may be to adjust the output light based on the image correction map to reduce at least one of the intensity non-uniformity and the color balance non-uniformity of the image further caused by variations in the incidence position and the incidence angle from one pixel to another.

According to yet another implementation of the present specification there is provided a wearable heads-up display (WHUD) comprising: a light source to generate an output light comprising a plurality of wavelengths, the output light to form an image; a spatial modulator to receive the output light from the light source; a light guide; an incoupler carried by the light guide, the incoupler to receive the output light from the spatial modulator and direct at least a portion of the output light into the light guide, the light guide to internally reflect the portion of the output light to form a reflected light, the output light having a plurality of incoupling losses corresponding to the plurality of wavelengths of the output light; an outcoupler carried by the light guide, the outcoupler to direct at least a portion of the reflected light out of the light guide towards an eye of a user wearing the WHUD; and a controller in communication with the light source and the spatial modulator, the controller to: obtain an image correction map; and adjust the output light based on the image correction map to reduce at least one of an intensity non-uniformity and a color balance non-uniformity of the image caused by the incoupling losses.

The output light may comprise a first light having a first wavelength and a second light having a second wavelength; the incoupler may be to direct at least a portion of the first light and at least a portion of the second light into the light guide, the light guide may be to internally reflect the portion of the first light and the portion of the second light to form a first reflected light and a second reflected light respectively, the first reflected light may be incident upon a reflective surface of at least one of the incoupler and the light guide at a first bounce position and the second reflected light may be incident upon the reflective surface of at least one of the incoupler and the light guide at a second bounce position, the first light may have a first incoupling loss based on the first bounce position and the second light may have a second incoupling loss based on the second bounce position; and the controller may be to adjust the output light based on the image correction map to reduce at least one of intensity non-uniformity and the color balance non-uniformity of the image caused by a difference between the first incoupling loss and the second incoupling loss.

The image may comprise a plurality of pixels, each pixel having a corresponding field position comprising spatial coordinates of the pixel in the image; for each given pixel, the incoupler may be to receive the output light at an incidence position on and an incidence angle relative to the incoupler based on the field position of the given pixel; and the controller may be further to: adjust the output light based on the image correction map to reduce at least one of the intensity non-uniformity and the color balance non-uniformity of the image further caused by variations in the incidence position and the incidence angle from one pixel to another.

