DRIVING A LIGHT SCANNER

• US 20090278824A1
• Filed: 04/10/2009
• Published: 11/12/2009
• Est. Priority Date: 05/06/2008
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: SEO, Jung Hoon, KIM, Jae Sung, KWON, Jae Wook, KIM, Suhwan, CHOI, Jung Hwan
• Granted Patent: US 8,941,627 B2
• Time in Patent Office: Days
• 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: G09G 5/12 Synchronisation between the display unit and other units, e.g. other display units, video-disc players
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161
• CPC Class Codes: H04N 9/3155 for controlling the light source light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406

Abstract

Driving a light scanner at a resonant frequency of the light scanner using a phase delay compensated driving signal.

Claims

1. A light scanner driving apparatus, comprising:

a reference signal generating unit configured to detect a phase difference between a driving signal for driving the light scanner and a sensed signal and configured to generate a reference signal based on the detected phase difference;

a phase delay compensating unit configured to detect a phase delay between the generated reference signal and the sensed signal and configured to generate a compensated signal based on the detected phase delay; and

a driving signal generating unit configured to generate the driving signal based on the compensated signal.

2. The apparatus of claim 1, further comprising;

a sensing unit configured to generate the sensed signal based on an operating characteristic of the light scanner; and

an amplification control unit configured to control amplification of the driving signal generated by the driving signal generating unit based on the sensed signal sensed at the sensing unit.

3. The apparatus of claim 2, wherein the amplification control unit includes;

a reference voltage generating unit configured to generate a reference voltage based on data from the driving signal generating unit,

a calculation unit configured to calculate a difference value between the generated reference voltage value and a voltage value of the sensed signal, and

a control unit configured to control amplification of the driving signal generated by the driving signal generating unit based on the calculated difference valve.

4. The apparatus of claim 3, wherein the calculation unit includes;

a first calculation unit configured to calculate a difference value between a reference voltage of a horizontal synchronizing signal and a sensed voltage of the horizontal synchronizing signal,

a second calculation unit configured to calculate a difference value between a reference voltage of vertical synchronizing signal and a sensed voltage of the vertical synchronizing signal,

a third calculating unit configured to integrate a value calculated at the first calculating unit, and

a fourth calculating unit configured to integrate a value calculated at the second calculating unit.

5. The apparatus of claim 2, wherein the amplification control unit includes;

a reference angle setting unit configured to set a reference angle based on the data from the driving signal generating unit,

a calculation unit configured to calculate a difference between the reference angle and a drive angle of the light scanner sensed by the sensing unit, and

a control unit configured to control amplification of the driving signal from the driving signal generating unit based on the difference calculated by the calculation unit.

6. The apparatus of claim 1, wherein the reference signal generating unit includes;

a noise removing unit configured to remove noise from the sensed signal,

a frequency adjusting unit configured to set a phase difference between the sensed signal and the driving signal to approximately 90°

, and

a synchronizing signal adjusting unit configured to adjust vertical and horizontal synchronizing signals of an external image signal based on the adjusted clock frequency to generate the reference signal.

7. The apparatus of claim 6, wherein the noise removing unit includes;

a differential amplification unit configured to amplify the sensed signal, and

an offset adjusting unit configured to adjust an offset of the amplified sensed signal.

8. The apparatus of claim 6, wherein the frequency adjusting unit includes;

a phase detection unit configured to detect a 90°

phase difference between the sensed signal and the driving signal,

a loop filter unit configured to provide a control voltage having a limited frequency component of the detected phase difference, and

a voltage control oscillation unit configured to generate a frequency based on the control voltage.

9. The apparatus of claim 6, wherein the reference signal generating unit further includes;

a first square wave converting unit connected between the noise removing unit and the frequency adjusting unit and configured to convert a signal applied thereto into a first clock signal, and

a second square wave converting unit connected between the drive signal generating unit and the frequency adjusting unit and configured to convert a signal applied thereto into a second clock signal.

10. The apparatus of claim 1, wherein the phase delay compensating unit includes;

a detection unit configured to detect a phase delay between the reference signal and the sensed signal,

a loop filter unit configured to provide a control voltage having a limited frequency component of the detected phase delay, and

a compensating unit configured to compensate the phase delay of the reference signal based on the control voltage.

11. The apparatus of claim 10, wherein the reference signal and the sensed signal provided to the detection unit are clock signals.

12. The apparatus of claim 11, wherein the reference signal is a clock signal converted at a clock converter, and wherein the sensed signal is a clock signal converted at the square wave converter.

13. The apparatus of claim 1, wherein the driving signal generating unit includes;

a memory unit configured to store the compensated reference signal,

a digital-analog converting unit configured to convert a reference signal stored in the memory unit from a digital signal into an analog signal,

a filter unit configured to remove high frequency components from the analog signal, and

a driving unit configured to drive the light scanner by using the analog signal.

14. The apparatus of claim 13, wherein the driving signal generated at the filter unit is provided to the reference signal generating unit.

15. The apparatus of claim 13, wherein the driving signal generating unit further includes a gain adjusting unit configured to adjust a gain of the reference signal stored in the memory unit based on a provided control signal.

16. A method for driving a light scanner, comprising:

detecting a phase difference between a driving signal and a signal sensed at the light scanner to generate a reference signal;

detecting a phase delay between the generated reference signal and the sensed signal;

compensating the phase delay to generate a compensated signal; and

generating the driving signal based on the compensated signal.

17. The method of claim 16, further comprising:

receiving an image signal generated outside of the light scanner, and

generating an initial driving signal based on a synchronizing signal of the received image signal before detecting the phase difference.

18. The method of claim 16, wherein detecting the phase difference includes sensing an operating characteristic of the light scanner to generate the sensed signal,

removing noise from the sensed signal, setting a phase difference between the sensed signal and the driving signal to approximately 90°

for adjusting a clock frequency, and adjusting vertical and horizontal synchronizing signals of the image signal based on the adjusted clock frequency for generating the reference signal.

19. The method of claim 16, wherein detecting a phase delay includes detecting a phase delay between the generated reference signal and the sensed signal, providing a control voltage having a limited frequency component of the detected phase delay, and compensating the phase delay of the reference signal based on the control voltage.

20. The method of claim 16, wherein generating the driving signal includes storing the compensated reference signal, converting the stored reference signal into an analog signal, removing a high frequency component from the analog signal to generate the driving signal, and driving the light scanner by using the generated driving signal.

21. The method of claim 20, further comprising, after storing the compensated reference signal, generating a reference voltage value from the generated reference signal;

calculating a difference value between the generated reference voltage value and a voltage value of the sensed signal; and

controlling amplification of the stored reference voltage based on the calculated difference value.

22. The method of claim 20, further comprising, after storing the compensated reference signal further comprising setting a reference angle of the driving angle for the light scanner based on the stored reference signal, calculating an difference value of a driving angle for the light scanner and the reference angle, and controlling amplification of the stored reference signal based on the calculated difference value.