Optical switch controller and movable body controller

• US 7,670,015 B2
• Filed: 06/25/2007
• Issued: 03/02/2010
• Est. Priority Date: 09/03/2003
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Takahashi, Kensuke, Mori, Kazuyuki, Ide, Satoshi, Matsuyama, Toru
• Primary Examiner(s): Stultz; Jessica T
• Application Number:
  US11/819,145
• Publication Number:
  US 20080013143A1
• Time in Patent Office: 981 Days
• Field of Search: 359/877
• US Class Current: 359/877
• 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 based upon electrostatic capacity changes corresponding to angular positions, comprising:

a mirror which moves at angular positions 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;

an electrostatic capacity detection unit which detects a first electrostatic capacity obtained due to the plus driving voltage of a driving signal, and a second electrostatic capacity obtained due to the minus driving voltage of the driving signal, when applying the plus driving voltage and the minus driving voltage of the driving signal to said mirror respectively; and

a processing unit which corrects the driving signal applied to change the angular position of said mirror while the angular position is changed, based on said first electrostatic capacity and said second electrostatic capacity detected by said electrostatic capacity detection unit, wherein

said electrostatic capacity detection unit provides values of the first electrostatic capacity and the second electrostatic capacity to the processing unit which applies the plus driving voltage and the minus driving voltage.

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

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

an electrostatic capacity detection unit which detects a first electrostatic capacity obtained due to the plus driving voltage and a second electrostatic capacity obtained due to the minus driving voltage, when the plus driving voltage and the minus driving voltage are provided to said mirror respectively;

an electrostatic capacity comparison unit which obtains a difference between said first electrostatic capacity and said second electrostatic capacity detected by said electrostatic capacity detection unit; and

a processing unit which corrects the driving signals to change the angular position of said mirror while the angular position is changed, based on the difference between the first and second electrostatic capacities obtained by said electrostatic capacity comparison unit, wherein

said electrostatic capacity detection unit provides values of the first and second electrostatic capacities to the electrostatic capacity comparison unit.

3. An optical switch controller according to claim 2, wherein

said electrostatic capacity detection unit uses an oscillating circuit which outputs 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 unit uses a frequency comparing circuit which obtains the difference between said first oscillation frequency and said second oscillation frequency which have been output from said electrostatic capacity detection unit.

4. An optical switch controller according to claim 3, wherein

the frequency comparing circuit used as said electrostatic capacity comparison unit 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 unit;

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

5. An optical switch controller according to claim 4, wherein

the frequency comparing circuit used as said electrostatic capacity comparison unit is composed of a frequency-voltage conversion unit which converts said first oscillation frequency and said second oscillation frequency outputted from said electrostatic capacity detection unit into corresponding voltages;

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

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 positions of the mirror;

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

a driving unit supplying a driving signal to the pair of 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, wherein

said electrostatic capacity detection unit provides a driving signal to the processing unit which applies a plus driving voltage and a minus driving voltage to the electrodes, respectively.

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.