Method and system for reducing line separation artifacts in interlaced image projection
An image display system includes an optical subsystem configured to emit a modulated light beam, and a scanning mirror for generating a reflected light beam that is scanned according to randomly selected or pseudo-randomly selected scan patterns to generate multiple image fields of a multiple interlaced scan image. A plurality of different scan patterns can be cycled through, randomly or pseudo-randomly selected, for the different image fields to reduce artifacts that may be observed while viewing a projected image.
1 . An image projection system comprising:
an illumination source configured to emit collimated light;
a scanning mirror configured to receive and reflect light from the illumination source;
a viewing assembly comprising one or more optical components configured to receive and redirect light reflected by the scanning mirror to a user; and
control circuitry operatively coupled to the illumination source and the scanning mirror, and configured to:
display a sequence of a plurality of images of virtual content to the user through the viewing assembly; and
control the illumination source and the scanning mirror by randomly or pseudo-randomly identifying, from among a set of k available scan patterns, a set of n scan patterns for displaying an image from the sequence of the plurality of images, wherein n represents an integer greater than or equal to four and k represents an integer greater than n, and wherein the illumination source and the scanning mirror are controlled to sequentially implement the set of n scan patterns for displaying the image.
2 . The image projection system of claim 1 , wherein the collimated light comprises laser light.
3 . The image projection system of claim 1 , wherein the viewing assembly comprises an augmented or virtual reality display for presenting virtual content to the user.
4 . The image projection system of claim 1 , further comprising:
an actuator controllable to induce movement in the scanning mirror about one or more rotational axes thereof to adjust an orientation of the scanning mirror in accordance with the set of n scan patterns.
5 . The image projection system of claim 4 , wherein the control circuitry is further configured to:
synchronously control (i) the illumination source to emit collimated light corresponding to pixels of the plurality of images of virtual content in the sequence, and (ii) the actuator of the scanning mirror to induce a sequence of different movements in the scanning mirror about the one or more rotational axes in accordance with the set of n scan patterns.
6 . The image projection system of claim 5 , wherein the sequence of different movements comprise a sequence of different oscillations in the scanning mirror about a first rotational axis of the one or more rotational axes, and wherein the different oscillations in the sequence are offset in phase from each other.
7 . The image projection system of claim 1 , wherein the plurality of images in the sequence are displayed using a quantity of m different scan patterns, m representing a value greater than one and less than or equal to k.
8 . The image projection system of claim 7 , wherein the control circuitry is configured to control an actuator of the scanning mirror to induce a sequence of m different oscillations in the scanning mirror about a first rotational axis in accordance with each of a plurality of scan patterns identified for the plurality of images of virtual content in the sequence, respectively, and wherein the m different oscillations are offset in phase from each other by at least 2π/k radians.
9 . The image projection system of claim 8 , wherein the control circuitry is configured to control the actuator of the scanning mirror to induce a sequence of n different oscillations in the scanning mirror about the first rotational axis in accordance with the quantity of n scan patterns identified for each of the m different images of virtual content in the sequence, the n different oscillations being offset in phase from each other by at least 2π/k radians.
10 . A method of operating an image projection system, the method comprising:
emitting collimated light at an illumination source;
reflecting light from the illumination source at a scanning mirror;
redirecting light reflected by the scanning mirror at a viewing assembly comprising one or more optical components;
displaying a sequence of a plurality of images of virtual content to a user through the viewing assembly; and
controlling the illumination source and the scanning mirror by randomly or pseudo-randomly identifying, from among a set of k available scan patterns, a set of n scan patterns for displaying an image from the sequence of the plurality of images, wherein n represents an integer greater than or equal to four and k represents an integer greater than n, and wherein the illumination source and the scanning mirror are controlled to sequentially implement the set of n scan patterns for displaying the image.
11 . The method of claim 10 , wherein the collimated light comprises laser light.
12 . The method of claim 10 , wherein the viewing assembly comprises an augmented or virtual reality display for presenting virtual content to the user.
13 . The method of claim 10 , wherein the scanning mirror comprises an actuator controllable to induce movement in the scanning mirror about one or more rotational axes thereof to adjust an orientation of the scanning mirror in accordance with the set of n scan patterns.
14 . The method of claim 13 , further comprising:
synchronously controlling (i) the illumination source to emit collimated light corresponding to pixels of the plurality of images of virtual content in the sequence, and (ii) the actuator of the scanning mirror to induce a sequence of different movements in the scanning mirror about the one or more rotational axes in accordance with the set of n scan patterns.
15 . The method of claim 14 , wherein the sequence of different movements comprise a sequence of different oscillations in the scanning mirror about a first rotational axis of the one or more rotational axes, and wherein the different oscillations in the sequence are offset in phase from each other.
16 . The method of claim 10 , wherein the plurality of images in the sequence are displayed using a quantity of m different scan patterns, m representing a value greater than one and less than or equal to k.
17 . The method of claim 16 , wherein an actuator of the scanning mirror is controlled to induce a sequence of m different oscillations in the scanning mirror about a first rotational axis in accordance with each of the plurality of scan patterns identified for a plurality of images of virtual content in the sequence, respectively, and wherein the m different oscillations are offset in phase from each other by at least 2π/k radians.
18 . The method of claim 17 , wherein the actuator of the scanning mirror is controlled to induce a sequence of n different oscillations in the scanning mirror about the first rotational axis in accordance with the quantity of n scan patterns identified for each of the m different images of virtual content in the sequence, the n different oscillations being offset in phase from each other by at least 2π/k radians.