Control scheme for a scanning display
Described is a display system comprising a light source, a scanning assembly, and a controller. The light source includes a first plurality of emitters forming a column that emits a first color. The light source also includes a second plurality of emitters forming a column that emits a different color. The scanning assembly includes a reflective surface rotated by the controller using a control signal having a nonlinear, pulsed waveform. The controller drives the first plurality of emitters and the second plurality of emitters in sequence, during respective portions of the nonlinear waveform, and in synchronization with rotation of the reflective surface such that light emitted by the first plurality of emitters and the second plurality of emitters is reflected onto a same pixel of an output image. The controller also adjusts emission durations of individual emitters to compensate for changes in the rotational speed of the reflective surface.
1. A method for forming an output image, comprising:
rotating a reflective surface using a control signal, wherein the control signal is a nonlinear waveform comprising pulses that repeat at a particular frequency, and wherein a rotational speed of the reflective surface depends on a slope of the pulses in the control signal;
driving a first plurality of emitters and a second plurality of emitters in sequence, wherein:
the first plurality of emitters forms a column of emitters configured to emit light of a first color,
the second plurality of emitters forms a column of emitters configured to emit light of a second color different from the first color,
the first plurality of emitters is driven during a different portion of the nonlinear waveform than the second plurality of emitters, and
the driving is performed in synchronization with the rotating of the reflective surface such that light emitted by the first plurality of emitters and the second plurality of emitters is reflected onto a same pixel of the output image; and
adjusting emission durations of individual emitters in the first plurality of emitters and the second plurality of emitters to compensate for changes in the rotational speed of the reflective surface.
2. The method of claim 1 , wherein the driving of the first plurality of emitters and the second plurality of emitters comprises:
driving the first plurality of emitters during a first part of a first pulse; and
driving the second plurality of emitters during a second part of the first pulse, wherein a duration of the first part is equal to a duration of the second part.
3. The method of claim 2 , wherein the first part and the second part correspond to a rising or falling portion of the first pulse.
4. The method of claim 1 , wherein the driving of the first plurality of emitters and the second plurality of emitters comprises:
driving the first plurality of emitters during a first part of a first pulse and a second part of a second pulse; and
driving the second plurality of emitters during a third part of a third pulse and a fourth part of a fourth pulse, wherein a combined duration of the first part and the second part is equal to a combined duration of the third part and the fourth part.
5. The method of claim 4 , wherein the first pulse and the second pulse precede the third pulse and the fourth pulse.
6. The method of claim 4 , wherein the first part is less linear than the second part, and wherein the third part is less linear than the fourth part.
7. The method of claim 4 , wherein the first part comprises two less linear portions of the first pulse, and wherein the second part comprises a more linear portion of the second pulse.
8. The method of claim 4 , wherein the first part and the third part are identical in shape, and wherein the second part and the fourth part are identical in shape.
9. The method of claim 1 , wherein the adjusting of the emission durations of individual emitters in the first plurality of emitters and the second plurality of emitters comprises:
increasing an emission duration when the reflective surface is rotating at a slower rotational speed, relative to an emission duration when the reflective surface is rotating at a faster rotational speed.
10. A display system, comprising:
a light source including a first plurality of emitters and a second plurality of emitters, wherein the first plurality of emitters forms a column of emitters configured to emit light of a first color, and wherein the second plurality of emitters forms a column of emitters configured to emit light of a second color different from the first color;
a scanning assembly including a reflective surface facing the light source, the reflective surface being rotatable in at least one dimension; and
a controller configured to:
rotate the reflective surface using a control signal, wherein the control signal is a nonlinear waveform comprising pulses that repeat at a particular frequency, and wherein a rotational speed of the reflective surface depends on a slope of the pulses in the control signal;
drive the first plurality of emitters and the second plurality of emitters in sequence, wherein the controller drives the first plurality of emitters during a different portion of the nonlinear waveform than the second plurality of emitters, and wherein the controller performs the driving in synchronization with rotation of the reflective surface such that light emitted by the first plurality of emitters and the second plurality of emitters is reflected onto a same pixel of an output image; and
adjust emission durations of individual emitters in the first plurality of emitters and the second plurality of emitters to compensate for changes in the rotational speed of the reflective surface.
11. The display system of claim 10 , wherein to drive the first plurality of emitters and the second plurality of emitters, the controller is configured to:
drive the first plurality of emitters during a first part of a first pulse; and
drive the second plurality of emitters during a second part of the first pulse, wherein a duration of the first part is equal to a duration of the second part.
12. The display system of claim 11 , wherein the first part and the second part correspond to a rising or falling portion of the first pulse.
13. The display system of claim 10 , wherein to drive the first plurality of emitters and the second plurality of emitters, the controller is configured to:
drive the first plurality of emitters during a first part of a first pulse and a second part of a second pulse; and
drive the second plurality of emitters during a third part of a third pulse and a fourth part of a fourth pulse, wherein a combined duration of the first part and the second part is equal to a combined duration of the third part and the fourth part.
14. The display system of claim 13 , wherein the first pulse and the second pulse precede the third pulse and the fourth pulse.
15. The display system of claim 13 , wherein the first part is less linear than the second part, and wherein the third part is less linear than the fourth part.
16. The display system of claim 13 , wherein the first part comprises two less linear portions of the first pulse, and wherein the second part comprises a more linear portion of the second pulse.
17. The display system of claim 13 , wherein the first part and the third part are identical in shape, and wherein the second part and the fourth part are identical in shape.
18. The display system of claim 10 , wherein to adjust emission durations of individual emitters in the first plurality of emitters and the second plurality of emitters, the controller is configured to increase an emission duration when the reflective surface is rotating at a slower rotational speed, relative to an emission duration when the reflective surface is rotating at a faster rotational speed.
19. A non-transitory computer readable storage medium storing instructions that, when executed by one or more processors of a computer system, cause the one or more processors to:
rotate a reflective surface using a control signal, wherein the control signal is a nonlinear waveform comprising pulses that repeat at a particular frequency, and wherein a rotational speed of the reflective surface depends on a slope of the pulses in the control signal;
drive a first plurality of emitters and a second plurality of emitters in sequence, wherein:
the first plurality of emitters forms a column of emitters configured to emit light of a first color,
the second plurality of emitters forms a column of emitters configured to emit light of a second color different from the first color,
the first plurality of emitters is driven during a different portion of the nonlinear waveform than the second plurality of emitters, and
the driving is performed in synchronization with rotation of the reflective surface such that light emitted by the first plurality of emitters and the second plurality of emitters is reflected onto a same pixel of an output image; and
adjust emission durations of individual emitters in the first plurality of emitters and the second plurality of emitters to compensate for changes in the rotational speed of the reflective surface.
20. The non-transitory computer readable storage medium of claim 19 , wherein to adjust emission durations of individual emitters in the first plurality of emitters and the second plurality of emitters, the instructions cause the one or more processors to increase an emission duration when the reflective surface is rotating at a slower rotational speed, relative to an emission duration when the reflective surface is rotating at a faster rotational speed.