Method for controlling position of a linear MEMS mirror with variable resolution and/or light intensity
The method for controlling an angular position of a MEMS mirror, includes: applying a first driving moment to the MEMS mirror to generate a rotational scanning movement of the mirror; and, at a zooming instant, applying a second driving moment to the MEMS mirror, wherein the second driving moment is equal to the first driving moment plus an extra moment. The extra moment may be a DC offset. After a transient period of time from zooming instant, a third driving moment M 2 =k{dot over (θ)} 2 t is applied. The first and third driving moment are variable linearly with time. The driving moments are applied to torsional springs of the mirror.
1. A method for controlling an angular position of a MEMS mirror, comprising:
applying a first driving moment to the MEMS mirror, applying the first driving moment generating a rotational scanning movement of the mirror; and
performing a zooming, which modifies at least one of a resolution and a light intensity of the MEMS mirror, by applying a second driving moment to the MEMS mirror, wherein the second driving moment is equal to the first driving moment plus an extra driving moment, wherein the extra driving moment is a fixed moment.
2. The method according to claim 1 , wherein the first driving moment is variable linearly with time.
3. The method according to claim 2 , wherein the first and second driving moments are applied to torsional springs of the mirror and the first driving moment is given by the equation:
k{dot over (θ)} 1 t=M 1
wherein k is a stiffness constant of the springs, θ is a first derivative of an angular position of the mirror, and t is time.
4. The method according to claim 1 , wherein the first and second driving moments are applied to torsional springs of the mirror and the extra driving moment (M-M 1 ) is equal to:
M
-
M
1
=
θ
¨
0
[
k
t
2
2
+
j
]
+
k
θ
x
wherein k is a stiffness constant of the springs, {umlaut over (θ)} 0 is a second derivative of an angular position of the mirror at a zooming instant, j is an inertial angular mass of the mirror, t is time, and θ x is the angular position of the mirror at the zooming instant.
5. The method according to claim 1 , comprising applying a third driving moment M 2 =k{dot over (θ)} 2 t after a transient period of time t from a zooming instant, wherein k is a stiffness constant of the springs, and {dot over (θ)} 2 is a speed of the mirror.
6. The method according to claim 5 , wherein applying the first driving moment comprises rotating the MEMS mirror at a first constant speed {dot over (θ)} 1 and applying the third driving moment comprises rotating the MEMS mirror at the speed {dot over (θ)} 2 , which is constant.
7. The method according to claim 1 , comprising:
reading from a conversion table a control electrical quantity corresponding to an instant driving moment; and
controlling rotation of the MEMS mirror according to the control electrical quantity read from the conversion table.
8. A method, comprising:
controlling an angular position of a MEMS mirror, the controlling including:
applying a first driving moment to the MEMS mirror, applying the first driving moment generating a rotational scanning movement of the mirror; and
modifying at least one of a resolution and a light intensity of the MEMS mirror by applying a second driving moment to the MEMS mirror, wherein the second driving moment is equal to the first driving moment plus a fixed moment.
9. The method according to claim 8 , wherein the first driving moment is variable linearly with time.
10. The method according to claim 8 , wherein the first and second driving moments are applied to torsional springs of the mirror and the first driving moment is given by the equation:
k{dot over (θ)} 1 t=M 1
wherein k is a stiffness constant of the springs, {dot over (θ)} 1 is a first derivative of an angular position of the mirror, and t is time.
11. The method according to claim 8 , wherein the first and second driving moments are applied to torsional springs of the mirror and the extra driving moment (M-M 1 ) is equal to:
M
-
M
1
=
θ
¨
0
[
k
t
2
2
+
j
]
+
k
θ
x
wherein k is a stiffness constant of the springs, {umlaut over (θ)} 0 is a second derivative of an angular position of the mirror at a zooming instant, j is an inertial angular mass of the mirror, t is time, and θ x is the angular position of the mirror at the zooming instant.
12. The method according to claim 8 , comprising applying a third driving moment M 2 =k{dot over (θ)} 2 t after a transient period of time t from a zooming instant, wherein k is a stiffness constant of the springs, and {dot over (θ)} 2 is a speed of the mirror.
13. The method according to claim 12 , wherein applying the first driving moment comprises rotating the MEMS mirror at a first constant speed {dot over (θ)} 1 and applying the third driving moment comprises rotating the MEMS mirror at the speed {dot over (θ)} 2 , which is constant.
14. The method according to claim 8 , comprising:
reading from a conversion table a control electrical quantity corresponding to an instant driving moment; and
controlling rotation of the MEMS mirror according to the control electrical quantity read from the conversion table.
15. A method, comprising:
controlling an angular position of a MEMS mirror, the controlling including:
applying a first driving moment to the MEMS mirror, applying the first driving moment generating a rotational scanning movement of the mirror;
performing a zooming at a zooming instant by applying a second driving moment to the MEMS mirror, wherein the second driving moment is equal to the first driving moment plus an extra driving moment; and
applying a third driving moment M 2 =k{dot over (θ)} 2 t after a transient period of time t from the zooming instant, wherein k is a stiffness constant of the springs, and {dot over (θ)} 2 is a speed of the mirror.
16. The method according to claim 15 , wherein the first and second driving moments are applied to torsional springs of the mirror and the first driving moment is given by the equation:
k{dot over (θ)} 1 t=M 1
wherein k is a stiffness constant of the springs, {dot over (θ)} 1 is a first derivative of an angular position of the mirror, and t is time.
17. The method according to claim 15 , wherein the first and second driving moments are applied to torsional springs of the mirror and the extra driving moment (M-M 1 ) is equal to:
M
-
M
1
=
θ
¨
0
[
k
t
2
2
+
j
]
+
k
θ
x
wherein k is a stiffness constant of the springs, {umlaut over (θ)} 0 is a second derivative of an angular position of the mirror at a zooming instant, j is an inertial angular mass of the mirror, t is time, and θ x is the angular position of the mirror at the zooming instant.
18. The method according to claim 15 , wherein applying the first driving moment comprises rotating the MEMS mirror at a first constant speed {dot over (θ)} 1 and applying the third driving moment comprises rotating the MEMS mirror at the speed {dot over (θ)} 2 , which is constant.
19. The method according to claim 15 , comprising:
reading from a conversion table a control electrical quantity corresponding to an instant driving moment; and
controlling rotation of the MEMS mirror according to the control electrical quantity read from the conversion table.