Bipolar staggered comb drive for bidirectional MEMS actuation
Embodiments of the disclosure provide a comb drive, a comb drive system, and a method of operating the comb drive to rotate bi-directionally in a MEMS environment. An exemplary comb drive system may include a comb drive, at least one power source, and a controller. The comb drive may include a stator comb having a first electrically conductive layer spaced apart from a second electrically conductive layer. The comb drive may also include a rotor comb having a first electrically conductive layer spaced apart from a second electrically conductive layer. The controller may be configured to apply first and second voltage levels having opposite polarities to the first and second electrically conductive layers of the rotor comb, respectively. The controller may also be configured to apply an intermediate voltage level to one of the first or second electrically conductive layers of the stator comb.
1. A comb drive system, comprising:
a comb drive comprising:
a stator comb having a first electrically conductive layer spaced apart from a second electrically conductive layer; and
a rotor comb having a first electrically conductive layer spaced apart from a second electrically conductive layer;
at least one power source; and
a controller connected between the at least one power source and the comb drive, the controller being configured to:
apply a first voltage level from the at least one power source to the first electrically conductive layer of the rotor comb;
apply a second voltage level from the at least one power source to the second electrically conductive layer of the rotor comb, the first and second voltage levels having opposite polarities;
apply an intermediate voltage level to one of the first and second electrically conductive layers of the stator comb, wherein the intermediate voltage level is lower than the first voltage level and higher than the second voltage level; and
change the intermediate voltage level to one of the first or second voltage level after a rotation of the rotor comb is initiated such that voltage levels applied to the first and second conductive layers of the stator comb have opposite polarities.
2. The comb drive system of claim 1 , wherein the controller is configured to apply one of the first or second voltage level to another one of the first and second electrically conductive layers of the stator comb.
3. The comb drive system of claim 2 , wherein the controller is configured to change a rotational direction of the rotor comb by:
changing the voltage level applied to the one of the first or second electrically conductive layer of the stator comb from the first or second voltage level to the intermediate level; and
changing the voltage level applied to another one of the first or second electrically conductive layer of the stator comb from the intermediate level to the first or second voltage level.
4. The comb drive system of claim 1 , wherein the controller is configured to bi-directionally rotate the rotor comb from a neutral position.
5. The comb drive system of claim 1 , wherein the first voltage level is a positive voltage level and the second voltage level is a negative voltage level.
6. The comb drive system of claim 1 , wherein the controller is configured to apply the intermediate voltage level by connecting the one of the first and second electrically conductive layers of the stator comb to ground.
7. The comb drive system of claim 1 , wherein each of the rotor and stator combs includes an insulating layer disposed between the first and second electrically conductive layers.
8. A method of operating a comb drive having a stator comb and a rotor comb, comprising:
applying a first voltage level from at least one power source to a first electrically conductive layer of the rotor comb;
applying a second voltage level from the at least one power source to a second electrically conductive layer of the rotor comb, the first and second voltage levels having opposite polarities;
applying an intermediate voltage level to one of the first and second electrically conductive layers of the stator comb, wherein the intermediate voltage level is lower than the first voltage level and higher than the second voltage level; and
changing the intermediate voltage level to one of the first or second voltage level after a rotation of the rotor comb is initiated such that voltage levels applied to the first and second conductive layers of the stator comb have opposite polarities.
9. The method of claim 8 , comprising applying one of the first or second voltage level to another one of the first or second electrically conductive layer of the stator comb.
10. The method of claim 9 , comprising changing a rotational direction of the rotor comb by:
changing the voltage level applied to the one of the first or second electrically conductive layer of the stator comb from the first or second voltage level to the intermediate level; and
changing the voltage level applied to another one of the first or second electrically conductive layer of the stator comb from the intermediate level to the first or second voltage level.
11. The method of claim 8 , comprising bi-directionally rotating the rotor comb from a neutral position.
12. The method of claim 8 , wherein the first voltage level is a positive voltage level and the second voltage level is a negative voltage level.
13. The method of claim 8 , comprising applying the intermediate voltage level by connecting the one of the first and second electrically conductive layers of the stator comb to ground.
14. The method of claim 8 , comprising connecting the first and second electrically conductive layers of the stator comb to ground to allow the rotor comb to return to a neutral position.