Optical switch controller and movable body controller

• US 20080013143A1
• Filed: 06/25/2007
• Published: 01/17/2008
• Est. Priority Date: 09/03/2003
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Takahashi, Kensuke, Mori, Kazuyuki, Ide, Satoshi, Matsuyama, Toru
• Granted Patent: US 7,670,015 B2
• Time in Patent Office: Days
• US Class Current: 359/223
• CPC Class Codes: G02B 6/3518 the reflective optical element being an intrinsic part of a MEMS device, i.e. fabricated together with the MEMS device MEMS devices in general B81B; manufacture of MEM devices in general B81C; micromechanical devices controlling the direction of light G02B26/0833
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/3584 constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: G02B 6/3588 of the processed beams, i.e. controlling during switching of orientation, alignment, or beam propagation properties such as intensity, size or shape
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/003 using switches based on microelectro-mechanical systems [MEMS]
• CPC Class Codes: H04Q 2011/0039 Electrical control

Abstract

In an optical switch controller, in order that residual vibration at movement control of a movable body such as a tilt mirror can be reduced and controlled with high accuracy, a processing unit outputs a driving signal for controlling the angle of the tilt mirror, the driving signal is D/A converted by a D/A converter and then is changed to a high-voltage signal by a high-voltage amplifier to be supplied to the tilt mirror, the electrostatic capacity of the tilt mirror changes corresponding to angle change of the tilt mirror, a mirror-angle detecting unit detects the electrostatic capacity and feeds back it as a correction value to a processing unit, and the processing unit corrects the driving signal using a correction value obtained when the angle of the tilt mirror is actually changed.

Claims

1. An optical switch controller performing angle control of a mirror upon using electrostatic capacity changed corresponding to angular positions, comprising:

a mirror moving at angular position corresponding to one or more values of driving voltages of driving signals based on said driving signals having a plus and a minus driving voltage;

electrostatic capacity detection means for detecting a first electrostatic capacity obtained due to the driving signal of the plus driving voltage and a second electrostatic capacity obtained due to the driving signal of the minus driving voltage, when providing the driving signal of the plus driving voltage and the driving signal of the minus driving voltage for said mirror respectively; and

processing means for correcting the driving signals to change the angular position of said mirror at the time of angular position change, on the basis of said first electrostatic capacity and said second electrostatic capacity detected by said electrostatic capacity detection means.

2. An optical switch controller performing angle control of a mirror upon using electrostatic capacity changed corresponding to positions, comprising:

a mirror moving at angular position corresponding to values of driving voltages of driving signals based on said driving signals having a plus and a minus driving voltage;

electrostatic capacity detection means for detecting a first electrostatic capacity obtained due to the driving signal of the plus driving voltage and a second electrostatic capacity obtained due to the driving signal of the minus driving voltage, when providing the driving signal of the plus driving voltage and the driving signal of the minus driving voltage for said mirror respectively;

electrostatic capacity comparison means for obtaining the difference between the values of said first electrostatic capacity and said second electrostatic capacity detected by said electrostatic capacity detection means; and

processing means for correcting the driving signals to change the angular position of said mirror at the time of angular position change, on the basis of signal of the difference between the values of the electrostatic capacities obtained by said electrostatic capacity comparison means.

3. An optical switch controller according to claim 2, wherein said electrostatic capacity detection means uses an oscillating circuit for outputting a first oscillation frequency corresponding to said first electrostatic capacity and a second oscillation frequency corresponding to said second electrostatic capacity based on variations in said electrostatic capacity each;

and

said electrostatic capacity comparison means uses a frequency comparing circuit for obtaining the difference between said first oscillation frequency and said second oscillation frequency which have been output from said electrostatic capacity detection means.

4. An optical switch controller according to claim 3, wherein the frequency comparing circuit used as said electrostatic capacity comparison means outputs signals of different polarities corresponding to respective phase leads and lags of said first oscillation frequency and said second oscillation frequency outputted from said electrostatic capacity detection means;

and said processing means corrects said driving signals based on the value of the difference and the signals of polarities outputted from said electrostatic capacity comparison means.

5. An optical switch controller according to claim 4, wherein the frequency comparing circuit used as said electrostatic capacity comparison means is composed of a frequency-voltage conversion means for converting said first oscillation frequency and said second oscillation frequency outputted from said electrostatic capacity detection means into corresponding voltages;

in a state where said processing means corrects said driving signals based on the voltage of the value of the difference outputted from said electrostatic capacity comparison means.

6. An optical switch apparatus comprising:

a mirror whose angle is variable;

a pair of driving electrodes facing the mirror, electrostatic capacity of which between the mirror varies according to angular position of the mirror;

a driving unit supplying driving signal to the pair of driving electrodes;

an electrostatic capacity detection unit detecting the electrostatic capacity between the mirror and the driving electrodes; and

a processing unit for correcting the driving signal when the angular position of the mirror changes, on the basis of the electrostatic capacity detected by said electrostatic capacity detection unit.

7. An optical switch apparatus according to claim 6, wherein said electrostatic capacity detection unit uses an oscillating circuit in which oscillation frequency changes based on variations of said electrostatic capacity.

8. An optical switch apparatus according to claim 7, wherein the oscillating circuit used as said electrostatic capacity detection unit is an LC oscillating circuit whose oscillation frequency changes based on variations of said electrostatic capacity.

9. An optical switch apparatus according to claim 8, wherein the LC oscillating circuit used as said electrostatic capacity detection unit is a Colpitts oscillating circuit whose oscillation frequency changes based on variations of said electrostatic capacity.

10. An optical switch apparatus according to claim 6, wherein said electrostatic capacity detection unit comprises:

a resonance circuit whose resonance frequency changes based on variations of said electrostatic capacity; and

a frequency sweeper for sweeping frequencies to provide swept frequency signals for said resonance circuit.

11. An optical switch apparatus according to claim 6, wherein said mirror is supported at the center axis of it and has one end and another end which are able to swing in both directions, and has said first electrostatic capacity between said one end and a first driving electrode facing said one end, and said second electrostatic capacity between said another end and a second driving electrode facing said another end.

12. An optical switch apparatus according to claim 6, wherein the driving electrodes receive a driving signal simultaneously.