Control device for a micromirror, method for controlling a micromirror and image projection system

• US 8,963,898 B2
• Filed: 08/03/2012
• Issued: 02/24/2015
• Est. Priority Date: 08/16/2011
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Steffen, Kurth, Hilberath, Thomas, Gessner, Thomas, Krayl, Oliver, Billep, Detlef, Specht, Hendrik
• Primary Examiner(s): XAVIER, ANTONIO J
• Application Number:
  US13/566,810
• Publication Number:
  US 20130127800A1
• Time in Patent Office: 935 Days
• Field of Search: None
• US Class Current: 345/204
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129

Abstract

A method for controlling a micro-mirror, having the following: generating a first control signal which encodes a tilting motion of the micro-mirror about a first tilt axis, at a first frequency; generating a second control signal which encodes a tilting motion of the micro-mirror about a second tilt axis which is perpendicular to the first tilt axis, at a second frequency which is lower than the first frequency; modulating the second control signal by binary modulation of the second control signal, at the first frequency; and controlling force coupling elements of the micro-mirror, using the modulated second control signal and the first control signal.

Claims

1. A method for controlling a micro-mirror, the method comprising:

generating a first control signal which encodes a tilting motion of the micro-mirror about a first tilt axis, at a first frequency;

generating a second control signal which encodes a tilting motion of the micro-mirror about a second tilt axis which is perpendicular to the first tilt axis, at a second frequency which is lower than the first frequency;

modulating the second control signal by binary modulation of the second control signal, at the first frequency; and

controlling force coupling elements of the micro-mirror, using the modulated second control signal and the first control signal.

2. The method of claim 1, wherein the first frequency is a resonant frequency of the micro-mirror with regard to the deflection about the first tilt axis, and the second frequency is below the resonant frequency of the micro-mirror with regard to the deflection about the second tilt axis.

3. The method of claim 1, further comprising:

splitting the modulated second control signal and the first control signal into partial control signals which in each case are configured for controlling different force coupling elements of the micro-mirror.

4. The method of claim 1, the method comprising:

comparing the amplitude of the second control signal to a pulse width threshold value;

generating a converted control signal from the second control signal based upon the comparison, the converted control signal on average having a greater signal amplitude than the second control signal; and

generating a third control signal from the converted control signal, the third control signal being binary-modulated at the first frequency.

5. The method of claim 4, wherein the third control signal on a time average basis encodes the tilting motion, which is encoded by the second control signal, of the micro-mirror about the second tilt axis.

6. A control device for controlling a micro-mirror, comprising:

a first signal generator which is configured to generate a first control signal which encodes a tilting motion of the micro-mirror about a first tilt axis, at a first frequency;

a second signal generator which is configured to generate a second control signal which encodes a tilting motion of the micro-mirror about a second tilt axis which is perpendicular to the first tilt axis, at a second frequency which is lower than the first frequency;

a modulator which is connected to the first signal generator and the second signal generator and which is configured to modulate the second control signal by binary modulation of the second control signal, at the first frequency; and

an actuator device which is connected to the modulator and which is configured to control force coupling elements of the micro-mirror, using the modulated second control signal and the first control signal.

7. The control device of claim 6, further comprising:

a first signal splitter which is coupled between the first signal generator and the actuator device, and which is configured to split the first control signal into first partial signals for controlling different force coupling elements of the micro-mirror; and

a second signal splitter which is coupled between the second signal generator and the modulator, and which is configured to split the second control signal into second partial signals for controlling different force coupling elements of the micro-mirror.

8. The control device of claim 6, wherein the first frequency is a resonant frequency of the micro-mirror with regard to the deflection about the first tilt axis, and the second frequency is below the resonant frequency of the micro-mirror with regard to the deflection about the second tilt axis.

9. An image projection system, comprising:

a micro-mirror system which includes at least one micro-mirror having a plurality of force coupling elements;

an image generation device which is configured to generate light beams according to predetermined image data and to direct the light beams onto the at least one micro-mirror of the micro-mirror system;

an image data generation device which is configured to generate predetermined image data and to supply same to the image generation device; and

a control device, which is configured to generate tilting motions of the at least one micro-mirror by controlling the plurality of force coupling elements so that the light beams generated by the image generation device are deflected by the at least one micro-mirror to generate an image which corresponds to the image data control device for controlling a micro-mirror,

wherein the control device includes;

a first signal generator which is configured to generate a first control signal which encodes a tilting motion of the micro-mirror about a first tilt axis, at a first frequency;

a second signal generator which is configured to generate a second control signal which encodes a tilting motion of the micro-mirror about a second tilt axis which is perpendicular to the first tilt axis, at a second frequency which is lower than the first frequency;

a modulator which is connected to the first signal generator and the second signal generator and which is configured to modulate the second control signal by binary modulation of the second control signal, at the first frequency; and

an actuator device which is connected to the modulator and which is configured to control force coupling elements of the micro-mirror, using the modulated second control signal and the first control signal.