Beam scanning engine and display system with multiple beam scanners
A display system includes a display screen, a light source to generate a light beam to be modulated in accordance with image data, and a beam scanning module to receive the light beams and to direct the light beam onto an associated display region of the display screen. The beam scanning module includes a resonant scanning mirror configured to scan the light beam along a first scanning direction across the associated display region, and a polygon scanning mirror to scan the light beam along a second scanning direction across the associated display region.
1. A display system comprising:
a display screen;
a light source to generate a light beam that is modulated in accordance with image data;
a beam scanning module to receive the light beams and to direct the light beam onto an associated display region of the display screen, the beam scanning module including
a resonant scanning mirror configured to scan the light beam along a first scanning direction across the associated display region, and
a rotating N-faceted polygon scanning mirror to scan the light beam along a second scanning direction across the associated display region such that in operation a combination of oscillation of the scanning mirror and rotation of the polygon scanning mirror creates a serpentine scan path for the light beam; and
a controller configured to set a ratio between an oscillating frequency f RES of the resonant scanning mirror and a rotation frequency f POLY of the polygon scanning mirror such that the scan path completes a cycle each n facets, wherein n is an integer greater than 2 and no more than N;
wherein the beam scanning module is configured to cause, for a first facet of the n facets, the light beam to follow a path including a first plurality of scan lines extending primarily along the first scanning direction and spaced apart along the second scanning direction, and to cause, for a second facet of the n facets, the light beam to follow a path that includes a second plurality of scan lines extending primarily along the first scanning direction and spaced apart along the second scanning direction, the first plurality of scan lines interlaced with the second plurality of scan lines.
2. The system of claim 1 , wherein N=n.
3. The system of claim 1 , wherein n<N, and the light beam is deactivated for (N-n) facets of the polygon scanning mirror.
4. The system of claim 1 , wherein
f
poly
=
f
res
n
(
Z
+
δ
)
where Z is a positive integer, and 0≤δ≤1.
5. The system of claim 4 , wherein δ is a irreducible fraction that is an integer multiple of 1/n.
6. The system of claim 4 , wherein Z is 24-40.
7. The system of claim 4 , wherein δ=1/n or δ=(n−1)/n.
8. The system of claim 1 , wherein a lateral position along the first scan direction of an end of the serpentine scan path for the n th facet corresponds to a lateral position along the first scan direction of a start of the serpentine scan path for the 1 st facet.
9. The system of claim 8 , wherein the serpentine scan path comprises a sinusoidal path.
10. The system of claim 1 , wherein a scanning speed of the light beam along the first scanning direction is greater than a scanning speed of the light beam along the second scanning direction.
11. The system of claim 1 , wherein the display screen comprises fluorescent material, and the light beam is an excitation beam to cause portions of the fluorescent material to fluoresce.
12. The system of claim 11 , wherein the fluorescent material comprises parallel stripes of extending along the second scanning direction.
13. The system of claim 1 , wherein the resonant scanning mirror causes the light beam to make n′ pluralities of interlaced scan lines extending primarily along the first scanning direction across the display region and spaced apart along the second scanning direction, and 1<n′≤N.
14. The system of claim 1 , further comprising a controller configured to receive image data including pixel data representing intensity values of pixels, to split the pixel data into a plurality of fields including a first field corresponding to the first plurality of scan lines and a second field, and to modulate the light beam in accordance with the image data of the first field while the light beam impinges the first facet, and to modulate the light beam in accordance with the image data of the second field while the light beam impinges the second facet.
15. The system of claim 1 , wherein each of the first and second pluralities of scan lines comprises the same number of scan lines.
16. The system of claim 15 , wherein between 60-80% of the number of scan lines fall within the display region.
17. The system of claim 1 , wherein the light beam is deactivated for scan lines positioned beyond opposite edges of the display region that are separated along the second scanning direction.
18. The system of claim 1 , wherein the rotating polygon scanning mirror is rotatable about an axis of rotation, and the N facets have a same angle of inclination relative to the axis of rotation.
19. The system of claim 18 , wherein the N facets are parallel to the axis of rotation.