SCANNING MIRROR AND SCANNING IMAGE DISPLAY DEVICE

• US 20140375898A1
• Filed: 03/14/2013
• Published: 12/25/2014
• Est. Priority Date: 03/23/2012
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Kurozuka, Akira, Yamamoto, Yuta, Nakazono, Shinsuke, Komaki, Kazuki
• Granted Patent: US 9,291,816 B2
• Time in Patent Office: Days
• US Class Current: 348/760
• 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 26/085 the reflecting means being moved or deformed by electromagnetic means
• 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
• CPC Class Codes: G02B 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence
• CPC Class Codes: G09G 3/002 to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT
• CPC Class Codes: G09G 3/025 with scanning or deflecting the beams in two directions or dimensions
• CPC Class Codes: H04N 9/3135 Driving therefor
• 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
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

A scanning mirror includes a mirror unit configured to reflect a laser beam, a supporter configured to cause the mirror unit to rotate and oscillate, and an oscillation sensor configured to output a monitor signal indicating oscillation of the mirror unit. A photodetector detects an intensity of the laser beam. When a value of the monitor signal falls out of a predetermined range of a normal operation and a value of the intensity detected by the photodetector fails to decrease, a breaking signal for causing the supporter to oscillate more than a breaking limit angle of the supporter is input. This scanning mirror and an image projection device using this scanning mirror can display an image at sufficient brightness safely.

Claims

1. A scanning mirror configured to be used with a photodetector and to reflects and scans a laser beam, the scanning mirror comprising:

a mirror unit configured to reflect the laser beam;

a supporter configured to cause the mirror unit to rotate and oscillate; and

an oscillation sensor configured to output a monitor signal indicating oscillation of the mirror unit,

wherein the photodetector detects an intensity of the laser beam, and

wherein, if a value of the monitor signal falls out of a predetermined range of a normal operation and a value of the intensity detected by the photodetector fails to decrease, a breaking signal for causing the supporter to oscillate more than a breaking limit angle of the supporter is input to the suporter.

2. The scanning mirror according to claim 1,

wherein the supporter includes:

a lower-speed supporter configured to rotate the mirror unit; and

a higher-speed supporter configured to cause the mirror unit to rotate and oscillate at a speed higher than the lower-speed supporter,

wherein, if the value of the monitor signal falls out of the predetermined range of the normal operation and the value of the intensity detected by the photodetector fails to decrease, a breaking signal for causing the higher-speed supporter to get broken is input to the higher-speed supporter, and then, a breaking signal for causing the lower-speed supporter to get broken is input to the lower-speed supporter.

3. The scanning mirror according to claim 1,

wherein the supporter includes:

a lower-speed supporter configured to rotate the mirror unit; and

a higher-speed supporter configured to cause the mirror unit to rotate and oscillate at a speed higher than the lower-speed supporter,

wherein the higher-speed supporter has a first resonance frequency and a second resonance frequency, the first resonance frequency being a resonance frequency of oscillation of the higher-speed supporter in a normal operation, the second resonance frequency being a resonance frequency of oscillation when a part of the higher-speed supporter is broken,

wherein the lower-speed supporter has a third resonance frequency and a fourth resonance frequency, the third resonance frequency being a resonance frequency of oscillation of the lower-speed supporter in the normal operation, the fourth resonance frequency being a resonance frequency of oscillation when a part of the lower-speed supporter is broken,

wherein, if the value of the monitor signal falls out of the predetermined range of the normal operation and the value of the intensity detected by the photodetector fails to decrease, a first breaking signal based on the first resonance frequency is input to the higher-speed supporter so as to break the higher-speed supporter, and then a second breaking signal based on the second resonance frequency is input to the higher-speed supporter so as to break the higher-speed supporter, and

wherein, if the value of the monitor signal falls out of the predetermined range of the normal operation and the value of the intensity detected by the photodetector fails to decrease, a third breaking signal based on the third resonance frequency is input to the lower-speed supporter so as to break the lower-speed supporter, and then a fourth breaking signal based on the fourth resonance frequency is input to the lower-speed supporter so as to break the lower-speed supporter.

4. A scanning image display device comprising:

a light source configured to output a laser beam;

a scanning mirror configured to scan the laser beam, the scanning mirror including

a mirror unit configured to reflect the laser beam,

a supporter configured to cause the mirror unit to rotate and oscillate, and

an oscillation sensor configured to output a monitor signal indicating oscillation of the mirror unit;

a mirror driver configured to drive the scanning mirror and output a synchronization signal;

an image processor configured to output a video signal synchronously with the synchronization signal;

a laser controller configured to modulate an intensity of the laser beam based on the video signal; and

a photodetector configured to detect the intensity of the laser beam,

wherein, if a value of the monitor signal falls out of a predetermined range of a normal operation and the intensity of the laser beam fails to decrease, the mirror driver is operable to break the scanning mirror.

5. The scanning image display device according to claim 4, wherein, if the value of the monitor signal falls out of the range of the normal operation and the detected intensity of the laser beam fails to decrease, the mirror driver is operable to output a breaking signal for breaking the scanning mirror to the scanning mirror.

6. The scanning image display device according to claim 4, wherein, if the value of the monitor signal falls out of the range of the normal operation and the detected intensity of the laser beam fails to decrease, the mirror driver is operable to sweep a frequency of the breaking signal from a frequency lower than a resonance frequency of the supporter to a frequency higher than the resonance frequency.

7. The scanning image display device according to claim 4,

wherein the supporter of the scanning mirror includes:

a lower-speed supporter configured to rotate the mirror unit; and

a higher-speed supporter configured to cause the mirror unit to rotate and oscillate at a speed higher than the lower-speed supporter,

wherein, if the value of the monitor signal falls out of the predetermined range of the normal operation and the value of the intensity detected by the photodetector fails to decrease, the mirror driver is operable to;

input a breaking signal for causing the higher-speed supporter to get broken to the higher-speed supporter; and

then, input a breaking signal for causing the lower-speed supporter to get broken to the lower-speed supporter.

8. The scanning image display device according to claim 7,

wherein the higher-speed supporter is configured to be driven at a resonance frequency of the higher-speed supporter, and

wherein the lower-speed supporter is configured to be driven in a non-resonant manner by a drive signal of a voltage higher than a voltage of the higher-speed supporter.

9. The scanning image display device according to claim 8, wherein the breaking signal for breaking the higher-speed supporter is generated at a voltage for rotating the lower-speed supporter.

10. The scanning image display device according to claim 4,

wherein the supporter of the scanning mirror includes:

a lower-speed supporter configured to rotate the mirror unit; and

a higher-speed supporter configured to cause the mirror unit to rotate and oscillate at a speed higher than the lower-speed supporter,

wherein the higher-speed supporter has a first resonance frequency and a second resonance frequency, the first resonance frequency being a resonance frequency of oscillation of the higher-speed supporter in a normal operation, the second resonance frequency being a resonance frequency of oscillation when a part of the higher-speed supporter is broken,

wherein, if the value of the monitor signal falls out of the predetermined range of the normal operation and the value of the intensity detected by the photodetector fails to decrease, the mirror driver is operable to;

input a first breaking signal based on the first resonance frequency to the higher-speed supporter so as to break the higher-speed supporter; and

then, input a second breaking signal based on the second resonance frequency to the higher-speed supporter so as to break the higher-speed supporter.

11. The scanning image display device according to claim 10,

wherein the lower-speed supporter has a third resonance frequency and a fourth resonance frequency, the third resonance frequency being a resonance frequency of oscillation of the lower-speed supporter in the normal operation, the fourth resonance frequency being a resonance frequency of oscillation of the lower-speed supporter when a part of the lower-speed supporter is broken, and

wherein, if the value of the monitor signal falls out of the predetermined range of the normal operation and the value of the intensity detected by the photodetector fails to decrease, the mirror driver is operable to:

input a third breaking signal based on the third resonance frequency to the lower-speed supporter so as to break the lower-speed supporter; and

then, input a fourth breaking signal based on the fourth resonance frequency to the lower-speed supporter in order to break the lower-speed supporter.

12. The scanning image display device according to claim 11,

wherein, if the value of the monitor signal falls out of the predetermined range of the normal operation and the value of the intensity detected by the photodetector fails to decrease, the mirror driver is operable to:

input the first breaking signal to the higher-speed supporter so as to break the higher-speed supporter;

then, input the second breaking signal to the higher-speed supporter so as to break the higher-speed supporter;

then, input the third breaking signal to the lower-speed supporter so as to break the lower-speed supporter; and

then, input the fourth breaking signal to the lower-speed supporter so as to break the lower-speed supporter.

13. The scanning image display device according to claim 4,

wherein the supporter of the scanning mirror includes:

a lower-speed supporter configured to rotate the mirror unit; and

a higher-speed supporter configured to cause the mirror unit to rotate and oscillate at a speed higher than the lower-speed supporter,

wherein the lower-speed supporter has a first resonance frequency and a second resonance frequency, the first resonance frequency being a resonance frequency of oscillation of the lower-speed supporter in a normal operation, the second resonance frequency being a resonance frequency of oscillation of the lower speed supporter when a part of the lower-speed supporter is broken,

wherein, if the value of the monitor signal falls out of the predetermined range of the normal operation and the value of the intensity detected by the photodetector fails to decrease, the mirror driver is operable to;

input a first breaking signal based on the first resonance frequency to the lower-speed supporter so as to break the lower-speed supporter; and

then, input a second breaking signal based on the second resonance frequency so as to break the lower-speed supporter.

14. The scanning image display device according to claim 5, wherein, if the value of the monitor signal falls out of the range of the normal operation and the detected intensity of the laser beam fails to decrease, the mirror driver is operable to sweep a frequency of the breaking signal from a frequency lower than a resonance frequency of the supporter to a frequency higher than the resonance frequency.