Method and apparatus for controlling deformable actuators

• US 7,424,330 B2
• Filed: 01/04/2005
• Issued: 09/09/2008
• Est. Priority Date: 07/04/2002
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V., Micronic Laser Systems AB (Mycronic AB)
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V., Micronic Laser Systems AB (Mycronic AB)
• Inventors: Duerr, Peter, Ljungblad, Ulric
• Primary Examiner(s): Kosowski; Alexander J
• Application Number:
  US11/028,963
• Publication Number:
  US 20060018048A1
• Time in Patent Office: 1,344 Days
• Field of Search: 700/11, 700/19, 359290-291, 359/318
• US Class Current: 700/19
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833

Abstract

In order to prevent negative effects of imprinting an the addressing accuracy of deformable actuators, a method for controlling deformable actuators has, during an event period, driving the first and the second deformable actuator for causing the deformable actuators to assume a first and a second deformation state, respectively; and, before or after the event period, driving the first and the second deformable actuator for causing the deformable actuators to assume deformations states to counteract an imprinting caused during the event period by approximating the loads applied to the deformable actuators to each other. According to an embodiment, before or after the event period, for a period substantially as long as the operation period, the first and the second deformable actuator are driven such that the first deformable actuator assumes the second deformation state and the second deformable actuator assumes the first deformation state.

Claims

1. An apparatus for controlling a first and a second deformable actuator, comprising:

a driver being operative in operation cycles comprising a programming period, an event period and a non-event period, the driver being configured to, in each operation cycle,

during the programming period, cause the first and second deformable actuator to assume an idle deformation state,

during the event period, cause the first deformable actuator to assume a first deformation state and cause the second deformable actuator to assume a second deformation state, and,

before or after the event period during the non-event period, cause the deformable actuators to assume deformations states to counteract an imprinting caused during the event period thereby approximating the loads applied to the deformable actuators during the operation cycle to each other;

wherein

the first deformable actuator is controllable by the difference between a first address signal and a driving signal, the second deformable actuator is controllable by the difference between a second address signal and the driving signal, and wherein the driver comprises,

an adjuster for, during the programming period, adjusting the first and the second address signal to a first and a second address value; and

a driver for driving the driving signal to a first driving value during the event period thereby causing the first deformable actuator to assume the first deformation state and the second deformable actuator to assume the second deformation state and, during the non-event period, driving the driving signal to a second driving value which is adapted such that the deformable actuators assume deformations states to counteract an imprinting caused during the event period thereby approximating the loads applied to the deformable actuators to each other.

2. The apparatus according to claim 1, wherein the driver is configured to, during the non-event period, cause the deformable actuators to assume deformations states to counteract an imprinting for a period substantially as long as the event period.

3. The apparatus according to claim 1, wherein the driver is configured to, during the non-event period, cause the first deformable actuator to assume the second deformation state and the second deformable actuator to assume the first deformation state.

4. The apparatus according to claim 1, wherein the driver is adapted such that the non-event period immediately precedes or follows the event period.

5. The apparatus according to claim 1, further comprising:

a compensator for compensating the deformation caused by the deformation state of the first and the second deformable actuator during the non-event time such that no deformation takes place during the non-event time.

6. The apparatus according to claim 1, further comprising:

at least one memory cell corresponding to the first and second deformable actuator, respectively, wherein the driver is configured to, during the programming period, adjust the first and the second address signal to a first and a second address value in accordance with control values stored in the storage.

7. The apparatus according to claim 1, wherein the second driving value is equal to the sum of the first and the second address value minus the first driving value.

8. The apparatus according to claim 7, wherein the driver is adapted such that the first and the second address values are either a value corresponding to an actuated state or a value corresponding to a non-actuated state, and wherein the first driving value is one of the values of the actuated state and the value of the non-actuated state and the second driving value is the other of the value of the actuated state and the value of the non-actuated state.

9. The apparatus according to claim 1, wherein the driver further comprises:

a driver for, during the programming period, driving the first and the second driving signal to a mean driving value which is the mean value between the first and the second driving value.

10. The apparatus according to claim 1, wherein each of the first and the second deformable actuators comprises:

an addressing electrode for receiving the first and the second address signal, respectively; and

an actuator element for receiving the driving signal, the actuator element being supported by a deformable portion thereof wherein the first and the second address signal and the driving signal correspond to respective voltage levels.

11. The apparatus according to claim 10, wherein the driver is adapted such that the first and the second address values are either a value corresponding to an actuated or a value corresponding to a non-actuated state, and wherein the first driving value is one of the values of the actuated state and the value of the non-actuated state and the second driving value is the other of the value of the actuated state and the value of the non-actuated state, wherein each of the first and the second deformable actuators comprises,

a counter electrode configured to be biased to a balancing potential during the programming period, for causing an electrostatic force between the actuator element and the counter electrode which is substantially equal to an electrostatic force between the actuator element and the first and second address electrode, respectively.

12. An apparatus for controlling a first and a second deformable actuator, comprising:

a driver being operative in operation cycles comprising a programming period, an event period and a non-event period, the driver being configured to, in each operation cycle,

during the programming period, cause the first and second deformable actuator to assume an idle deformation state,

during the event period, cause the first deformable actuator to assume a first deformation state and cause the second deformable actuator to assume a second deformation state, and,

before or after the event period during the non-event period, cause the deformable actuators to assume deformations states to counteract an imprinting caused during the event period thereby approximating the loads applied to the deformable actuators during the operation cycle to each other;

wherein

the first deformable actuator is controllable by a first address signal and a first and a second driving signal, the second deformable actuator being controllable by a second address signal and the first and the second driving signal, the extent of deformation of the first deformable actuator depending on the difference of the difference between the first addressing signal and the first driving signal and the difference between the first address signal and the second driving signal, and the extent of deformation of the second deformable actuator depending on the difference of the difference between the second address signal and the first driving signal and the difference between the second address signal and the second driving signal, and wherein the driver for driving the first and the second deformable actuator comprises,

an adjuster for adjusting a first and a second address signal to a first and a second address value; and

a driver for driving the first driving signal to a first driving value and the second driving signal to a second driving value different from the first driving value during the event period thereby causing the first deformable actuator to assume the first deformation state and the second deformable actuator to assume the second deformation state and, before and after the event period, driving the first driving signal to the second driving value and the second driving signal to the first driving value.

13. A method for controlling a first and a second deformable actuator in operation cycles comprising a programming period, an event-period and a non-event period, in each operation cycle, the method comprising:

during the programming period, causing the first and second deformable actuator to assume an idle deformation state by adjusting the first and the second address signal to a first and a second address value;

during the event period, causing the first deformable actuator to assume a first deformation state and causing the second deformable actuator to assume a second deformation state by driving the driving signal to a first driving value; and

before or after the event period during the non-event period, driving the driving signal to a second driving value, the second driving value being adapted such that the deformable actuators assume deformations states to counteract an imprinting caused during the event period, the driving of the driving signal to the second driving value causing the deformable actuators to assume the deformations states to counteract the imprinting caused during the event period, thereby approximating the loads applied to the deformable actuators to each other;

wherein

the first deformable actuator is controllable by the difference between a first address signal and a driving signal, the second deformable actuator is controllable by the difference between a second address signal and the driving signal.