Head-mounted display device with voice coil motors for moving displays
A head mounted display (HMD) includes a set of one or more lenses defining an optical axis, a display configured to project light through the set of the one or more lenses, a voice coil actuator coupled with the display and configured to move the display along the optical axis, and a first guide that is separate from the first voice coil actuator and coupled with the first display to guide the movement of the first display. The HMD additionally includes a set of one or more position sensors configured to determine a position of the display long the optical axis and an electronic controller configured to receive information identifying a reference position of the display along the optical axis and generate one or more electrical signals for initiating a movement of the first display toward the first reference point along the optical axis.
1. A head-mounted display device, comprising:
a display configured to project light;
a voice coil actuator coupled with the display and configured to move the display;
a guide that is separate from the voice coil actuator and coupled with the display to guide the movement of the display;
one or more position sensors configured to determine a position of the display; and
an electronic controller configured to receive information identifying the determined position of the display and generate one or more electrical signals for initiating a movement of the display toward a reference position, wherein:
the electronic controller is configured to repeat (i) receiving information identifying a determined position of the display and (ii) generating one or more electrical signals to continue the movement of the display toward the reference position until the determined position of the display is within a predefined distance from the reference position; and
the one or more electrical signals to continue the movement of the display toward the reference position are generated based on a difference between the reference position and the determined position of the display.
2. Head-mounted display device of claim 1 , further comprising:
one or more processors configured to determine the reference position of the display, wherein the electronic controller is further configured to receive information identifying the reference position of the display from the one or more processors.
3. The head-mounted display device of claim 2 , further comprising:
an eye tracking system configured to determine a position of an eye of a user, wherein the one or more processors are configured to determine the reference position of the display based on information identifying the determined position of the eye of the user and provide the reference position to the electronic controller.
4. The head-mounted display device of claim 3 , wherein:
determining the position of the eye of the user includes determining an interpupillary distance, an interocular distance, a three-dimensional position of the eye of the user relative to the display, or a gaze direction of the eye of the user.
5. The head-mounted display device of claim 1 , wherein:
the one or more electrical signals are based on one or more of: a derivative value corresponding to a difference between the reference position and the determined position of the display, or an integral value corresponding to the difference between the reference position and the determined position of the display.
6. The head-mounted display device of claim 1 , wherein:
the voice coil actuator includes a coil and a magnet that is slidingly coupled with the coil; and
the display is mechanically coupled with the magnet.
7. The head-mounted display device of claim 1 , wherein:
the voice coil actuator includes a coil and a magnet that is slidingly coupled with the coil; and
the display is mechanically coupled with the coil.
8. A head-mounted display device, comprising:
a display configured to project light;
a voice coil actuator coupled with the display and configured to move the display;
a guide that is separate from the voice coil actuator and coupled with the display to guide the movement of the display;
one or more position sensors configured to determine a position of the display;
an electronic controller configured to receive information identifying the determined position of the display and generate one or more electrical signals for initiating a movement of the display toward a reference position; and
a voltage limiter electrically coupled with the one or more position sensors and the electronic controller, the voltage limiter configured to control an acceleration of the voice coil actuator.
9. A method performed by an electronic controller for use in a head-mounted display device, the method comprising:
receiving, at the electronic controller, information identifying a determined position of a display; and
generating, with the electronic controller, one or more electrical signals for initiating a movement of the display toward a reference position, including:
generating, with the electronic controller, a first electrical signal that is based on a difference between the reference position and the determined position of the display.
10. The method of claim 9 , including:
repeating, with the electronic controller, (i) receiving information identifying a determined position of the display and (ii) providing one or more electrical signals to continue the movement of the display, until the determined position is within a predefined distance from the reference position.
11. The method of claim 10 , including:
smoothing electrical signals representing the determined position of the display.
12. The method of claim 10 , further comprising:
determining, with an eye tracking system, a position of an eye of a user; and
determining, with one or more processors, the reference position based on information identifying the determined position of the eye of the user and providing the reference position to the electronic controller.
13. The method of claim 9 , including:
generating, with the electronic controller, one or more electrical signals that are based on a derivative value corresponding to the difference between the reference position and the determined position of the display and/or an integral value corresponding to the difference between the reference position and the determined position of the display.
14. The method of claim 9 , including:
generating, with the electronic controller, a second electrical signal by (i) adding to the first electrical signal a first offset signal in accordance with a determination that the first electrical signal has a positive voltage or (ii) adding to the first electrical signal adding a second offset signal in accordance with a determination that the first electrical signal has a negative voltage.
15. The method of claim 9 , wherein:
the head-mounted display device includes a first voice coil actuator that includes a coil and a magnet; and
the method includes generating, with the electronic controller, a third electrical signal that is based on (i) the difference between the reference position and the determined position of the display and (ii) a position of the coil relative to the magnet.
16. The method of claim 9 , including:
generating, with the electronic controller, a fourth electrical signal by limiting the first electrical signal and/or limiting a rate of change of the first electrical signal.
17. The method of claim 9 , wherein:
the head-mounted display device includes one or more inertial measurement units configured to determine an acceleration of the head-mounted display device; and
the method includes generating, with the electronic controller, a fifth electrical signal by adding to the first electrical signal an electrical signal based on the acceleration of the head-mounted display device.